阅读说明：本技术 硬质烧结体用基材、硬质烧结体及切削工具 (Base material for hard sintered body, and cutting tool ) 是由 越山将行 松尾俊彦 深田耕司 浜田阳一 于 2020-03-27 设计创作，主要内容包括：本发明的硬质烧结体用基材,其具备具有中心轴并在中心轴的轴向上延伸的柱部,其中,柱部具有：第1外周部,构成柱部的外周部的一部分；第2外周部,构成柱部的外周部的一部分；及基材凸条部,在与中心轴垂直的横截面视图中,位于彼此相连的第1外周部与第2外周部的连接部分并在轴向上延伸,在该横截面视图中,第1外周部中的一侧部分位于比另一侧部分更靠径向内侧的位置,在该横截面视图中,第2外周部中的一侧部分位于比另一侧部分更靠径向外侧的位置,基材凸条部位于第1外周部的另一侧部分与第2外周部的一侧部分的连接部分并向径向外侧突出。(The present invention provides a substrate for a hard sintered body, comprising a column portion having a central axis and extending in an axial direction of the central axis, wherein the column portion comprises: a 1 st outer peripheral portion constituting a part of an outer peripheral portion of the pillar portion; a 2 nd outer peripheral portion constituting a part of an outer peripheral portion of the pillar portion; and a base material convex strip portion which is located at a connecting portion of a 1 st outer peripheral portion and a 2 nd outer peripheral portion which are connected with each other in a cross-sectional view perpendicular to the central axis and extends in the axial direction, wherein in the cross-sectional view, one side portion of the 1 st outer peripheral portion is located more radially inward than the other side portion, in the cross-sectional view, one side portion of the 2 nd outer peripheral portion is located more radially outward than the other side portion, and the base material convex strip portion is located at a connecting portion of the other side portion of the 1 st outer peripheral portion and the one side portion of the 2 nd outer peripheral portion and protrudes radially outward.)

1. A base material for a hard sintered body, comprising a columnar portion having a central axis and extending in an axial direction of the central axis,

the pillar portion has:

a 1 st outer circumferential portion arranged at an outer circumferential portion of the pillar portion and constituting a part of the outer circumferential portion;

a 2 nd outer peripheral portion disposed on an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion; and

a base material convex strip portion located at a connecting portion of the 1 st outer peripheral portion and the 2 nd outer peripheral portion connected to each other in a cross-sectional view perpendicular to the center axis and extending in an axial direction,

in the cross-sectional view, one side portion of the 1 st outer peripheral portion extending in the circumferential direction or the radial direction is located more radially inward than the other side portion,

one side portion of the 2 nd outer peripheral portion extending in the circumferential direction or the radial direction is located more radially outward than the other side portion in the cross-sectional view,

the base convex strip is located at a connecting portion between the other side portion of the 1 st outer peripheral portion and the one side portion of the 2 nd outer peripheral portion and protrudes radially outward.

2. The substrate for a hard sintered body according to claim 1, wherein,

the base material ridge portion has a sharp corner on a radially outer end of the base material ridge portion.

3. The substrate for a hard sintered body according to claim 1, wherein,

in the cross-sectional view, the raised strip portions of the base material are in the shape of a raised curve.

4. The substrate for a hard sintered body according to any one of claims 1 to 3,

the 1 st peripheral portion is provided in plural,

the 2 nd peripheral portion is provided in plurality,

the base material convex strip portion is provided in plurality at intervals in the circumferential direction.

5. The substrate for a hard sintered body according to claim 4, wherein,

in the cross-sectional view, the plurality of substrate ridges are arranged to be rotationally symmetrical about the central axis.

6. The substrate for a hard sintered body according to any one of claims 1 to 5,

the pillar portion has a base material concave portion located at a connecting portion of the 1 st outer peripheral portion and the 2 nd outer peripheral portion connected to each other in the cross-sectional view and extending in the axial direction,

the base concave portion is located at a connecting portion between one side portion of the 1 st outer peripheral portion and the other side portion of the 2 nd outer peripheral portion and is recessed radially inward.

7. The substrate for a hard sintered body according to any one of claims 1 to 6,

in the cross-sectional view, the pillar portion has a polygonal shape.

8. A hard sintered body comprising:

a base material for a hard sintered body, which has a column part having a central axis and extending in an axial direction of the central axis; and

a cylindrical portion having a cylindrical shape covering the column portion from a radially outer side, the cylindrical portion having a smaller linear expansion coefficient and a higher hardness than the hard sintered body base material, the cylindrical portion and the hard sintered body base material being integrally sintered,

the pillar portion has a 1 st outer peripheral portion disposed at an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion,

one side portion of the 1 st outer circumferential portion extending in the circumferential direction or the radial direction is located more radially inward than the other side portion in a cross-sectional view perpendicular to the center axis,

the cylinder portion has a 1 st inner circumferential portion arranged at an inner circumferential portion of the cylinder portion and constituting a part of the inner circumferential portion,

in the cross-sectional view, one side portion in the 1 st inner peripheral portion extending in the circumferential direction or the radial direction is located more radially inward than the other side portion,

the 1 st outer peripheral portion and the 1 st inner peripheral portion are engaged with each other.

9. The hard sintered body according to claim 8,

the 1 st outer peripheral portion is located radially inward as going toward one side in the circumferential direction,

the 1 st inner peripheral portion is located radially inward as it goes to one side in the circumferential direction.

10. The hard sintered body according to claim 8 or 9, wherein,

the pillar portion has:

a 2 nd outer peripheral portion disposed on an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion; and

a base material convex strip portion located at a connecting portion of the 1 st peripheral portion and the 2 nd peripheral portion connected to each other in the cross-sectional view and extending in an axial direction,

one side portion of the 2 nd outer peripheral portion extending in the circumferential direction or the radial direction is located more radially outward than the other side portion in the cross-sectional view,

the base material convex strip is positioned at the connecting part of the other side part of the 1 st outer peripheral part and one side part of the 2 nd outer peripheral part and protrudes outwards in the radial direction,

the tube portion has:

a 2 nd inner peripheral portion disposed on an inner peripheral portion of the cylindrical portion and constituting a part of the inner peripheral portion; and

a barrel portion concave portion located at a connecting portion of the 1 st inner circumferential portion and the 2 nd inner circumferential portion connected to each other in the cross-sectional view and extending in an axial direction,

in the cross-sectional view, one side portion in the 2 nd inner peripheral portion extending in the circumferential direction or the radial direction is located more radially outward than the other side portion,

the tube part concave strip part is positioned at the connecting part of the other side part of the 1 st inner circumference part and one side part of the 2 nd inner circumference part and is concaved towards the radial outer side,

the 2 nd outer peripheral portion and the 2 nd inner peripheral portion are engaged with each other,

the base material convex strip part and the cylinder part concave strip part are jointed with each other.

11. The hard sintered body according to any one of claims 8 to 10,

in the cross-sectional view, the 1 st outer peripheral portion is inclined at an angle of 4 ° or more and 170 ° or less with respect to a 2 nd straight line, the 2 nd straight line being orthogonal to a 1 st straight line that passes through a radial outer end portion of the 1 st outer peripheral portion and the central axis and extends in a radial direction, and the 2 nd straight line passing through a radial outer end portion of the 1 st outer peripheral portion.

12. The hard sintered body according to claim 11, wherein,

the 1 st outer peripheral portion is provided in plurality at intervals from each other in the circumferential direction,

in the cross-sectional view, the respective angles of the plurality of 1 st peripheral portions are equal to each other.

13. The hard sintered body according to any one of claims 8 to 12,

the substrate for a hard sintered body has a Young's modulus of 300GPa or more,

the cylinder portion has a Young's modulus of 600GPa or more.

14. The hard sintered body according to any one of claims 8 to 13,

the substrate for a hard sintered body is made of any one of a hard alloy, a cermet and a ceramic,

the cylindrical portion is made of either polycrystalline diamond or polycrystalline cubic boron nitride.

15. A cutting tool is provided with:

a blade portion provided with a chip groove and a cutting edge extending in an axial direction on an outer peripheral portion of the hard sintered body according to any one of claims 8 to 14; and

a shank connected to the blade in an axial direction,

the cutting blade is disposed on the cylindrical portion.

16. The cutting tool of claim 15,

the other side portion of the 1 st outer peripheral portion intersects the cutting edge when viewed in a radial direction.

17. The cutting tool of claim 15 or 16,

the 1 st outer peripheral portion is provided in plurality at intervals from each other in the circumferential direction,

the number of the cutting edges is more than one,

the number of the 1 st outer peripheral portions is equal to or greater than the number of the cutting edges.

Technical Field

The present invention relates to a base material for a hard sintered body, and a cutting tool.

The present application claims priority based on patent application No. 2019-061639, filed in japan on 27/3/2019, the contents of which are incorporated herein by reference.

Background

Conventionally, cutting tools such as an end mill, a reamer, and a drill are known. The cutting tool is manufactured by grinding a cylindrical tool blank to form a chip groove, a cutting edge, and the like. The tool material is produced by joining a hard sintered body constituting the blade portion and a shank portion made of cemented carbide by brazing.

The hard sintered body includes a multi-stage cylindrical base material and a cylindrical tube portion covering a small-diameter portion of the base material. The base material is made of hard alloy, and the cylinder part is made of polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PcBN). The base material and the cylindrical portion are integrally sintered to form a hard sintered body. As conventional hard sintered bodies, for example, patent documents 1 and 2 are known.

Patent document 1: japanese patent No. 5906355

Patent document 2: japanese patent No. 3055803

When a conventional hard sintered body is used for a cutting tool (rotary cutting tool) such as an end mill, a reamer, and a drill, for example, cracks or chipping may occur in the vicinity of the interface between the base material and the cylindrical portion. Specifically, it is considered that the above-described disadvantage occurs because, among loads applied to the cutting tool during cutting, a load applied in a direction perpendicular to the central axis of the tool generates a force in a shearing direction along the interface between the base material and the cylindrical portion.

For example, if the cutting conditions are adjusted to reduce the load on the cutting tool by reducing the feed amount during cutting, the machining efficiency is reduced. Further, the machining demand for difficult-to-cut materials such as Carbon Fiber Reinforced Plastic (CFRP) tends to increase, and the load on the cutting tool is expected to increase even more.

Disclosure of Invention

In view of the above circumstances, an object of the present invention is to provide a base material for a hard sintered body, and a cutting tool, which can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

One aspect of the present invention is a base material for a hard sintered body, including a column portion having a central axis and extending in an axial direction of the central axis, the column portion including: a 1 st outer circumferential portion arranged at an outer circumferential portion of the pillar portion and constituting a part of the outer circumferential portion; a 2 nd outer peripheral portion disposed on an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion; and a base material ridge portion that is located at a connecting portion between the 1 st outer peripheral portion and the 2 nd outer peripheral portion that are connected to each other in a cross-sectional view perpendicular to the center axis and extends in the axial direction, wherein one of the 1 st outer peripheral portion extending in the circumferential direction or the radial direction is located radially inward of the other, one of the 2 nd outer peripheral portion extending in the circumferential direction or the radial direction is located radially outward of the other, and the base material ridge portion is located at a connecting portion between the other of the 1 st outer peripheral portion and the one of the 2 nd outer peripheral portion and protrudes radially outward.

The base material for a hard sintered body of the present invention has base material ridges protruding radially outward. Further, the cylindrical portion integrally sintered with the base material is provided with a portion (a cylindrical recessed portion described later) to be joined to the base material raised portion. Therefore, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the edge portion of the cutting tool, the load applied in the circumferential direction of the cutting tool can be received by the base material ridge portion. This can suppress the load applied in the direction perpendicular to the central axis of the tool, of the loads applied to the cutting tool during cutting, from acting along the interface between the base material and the cylindrical portion, i.e., can reduce the shear force along the interface, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion. Therefore, the chipping resistance of the cutting tool produced using the hard sintered body can be improved, and the tool life can be extended.

In the above-described substrate for a hard sintered body, the substrate ridges may have sharp corners at radially outer ends of the substrate ridges.

In this case, the function (action) of the raised strip portion based on the base material is further improved.

In the above-described substrate for a hard sintered body, the substrate convex portions may be in the shape of a convex curve in the cross-sectional view.

In this case, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the edge portion of the cutting tool, the load concentration at the leading end (radially outer end) in the ridge portion of the base material can be suppressed. Therefore, the occurrence of cracks or chipping in the vicinity of the raised strip portion of the base material can be easily suppressed.

Preferably, in the base material for a hard sintered body, the 1 st outer peripheral portion is provided in plurality, the 2 nd outer peripheral portion is provided in plurality, and the base raised strip portion is provided in plurality at intervals in the circumferential direction.

In this case, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the cutting edge portion of the cutting tool, the function based on the above-described base material ridges is obtained at a plurality of locations in the circumferential direction of the cutting tool. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion can be stably suppressed, and the chipping resistance of the cutting tool can be further improved.

Preferably, in the base material for a hard sintered body, the plurality of base material ridges are arranged in rotational symmetry about the central axis in the cross-sectional view.

In this case, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the cutting edge of the cutting tool, the load is uniformly applied to each of the base material ridges. That is, it is possible to suppress a large load from continuously acting on the specific base material ridge portion, and to more stably suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Preferably, in the base material for a hard sintered body, the pillar portion has a base material concave portion that extends in an axial direction at a connecting portion between the 1 st outer peripheral portion and the 2 nd outer peripheral portion that are connected to each other in the cross-sectional view, and the base material concave portion is recessed radially inward at a connecting portion between one side portion of the 1 st outer peripheral portion and the other side portion of the 2 nd outer peripheral portion.

In this case, the base material concave portion is provided, so that the 1 st outer peripheral portion can be easily oriented in the circumferential direction. Therefore, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the edge portion of the cutting tool, the load can be more easily received at the 1 st outer peripheral portion. In addition, the base material has an increased degree of freedom in the arrangement of the raised strip portion or the 1 st outer peripheral portion of the base material, and can be easily applied to various hard sintered bodies used for various cutting tools.

Preferably, in the above base material for a hard sintered body, the columnar portion has a polygonal shape in the cross-sectional view.

In this case, the structure of the present invention can be realized simply and the manufacturing is easy.

In addition, an aspect of the hard sintered body of the present invention includes: a base material for a hard sintered body, which has a column part having a central axis and extending in an axial direction of the central axis; and a cylindrical portion having a cylindrical shape covering the column portion from the radially outer side, the cylindrical portion being formed in a manner such that, compared with the base material for a hard sintered body, the cylindrical portion has a small linear expansion coefficient and a high hardness, and is integrally sintered to the hard sintered body base material, the pillar portion has a 1 st outer peripheral portion disposed at an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion, one side portion of the 1 st outer circumferential portion extending in the circumferential direction or the radial direction is located more radially inward than the other side portion in a cross-sectional view perpendicular to the center axis, the cylinder portion has a 1 st inner circumferential portion arranged at an inner circumferential portion of the cylinder portion and constituting a part of the inner circumferential portion, in the cross-sectional view, one side portion of the 1 st inner peripheral portion extending in the circumferential direction or the radial direction is located more radially inward than the other side portion, and the 1 st outer peripheral portion and the 1 st inner peripheral portion are engaged with each other.

In addition, one aspect of the cutting tool of the present invention includes: a blade portion provided with a chip groove and a cutting edge extending in an axial direction on an outer peripheral portion of the hard sintered body; and a shank portion axially connected to the blade portion, the cutting edge being disposed on the cylindrical portion.

In the hard sintered body and the cutting tool of the present invention, in a cross-sectional view perpendicular to the central axis, one of the 1 st outer peripheral portions of the base material is located radially inward of the other, i.e., the 1 st outer peripheral portion is oriented in the circumferential direction. In the cross-sectional view, one of the 1 st inner peripheral portion of the cylindrical portion is located radially inward of the other, i.e., the 1 st inner peripheral portion is oriented in the circumferential direction. Further, the 1 st outer peripheral portion and the 1 st inner peripheral portion facing the circumferential direction are joined to each other.

When this hard sintered body is used for cutting at the edge portion of a cutting tool, a load applied in the circumferential direction of the cutting tool can be received at the 1 st outer peripheral portion of the base material by setting the 1 st outer peripheral portion to a posture in the tool rotation direction. This can suppress the load applied in the direction perpendicular to the central axis of the tool, of the loads applied to the cutting tool during cutting, from acting along the interface between the base material and the cylindrical portion, i.e., can reduce the shear force along the interface, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion. Thus, the cutting tool produced using the hard sintered body can have improved chipping resistance and can have a prolonged tool life.

Preferably, in the above hard sintered body, the 1 st outer peripheral portion is located radially inward as it goes to one side in the circumferential direction, and the 1 st inner peripheral portion is located radially inward as it goes to one side in the circumferential direction.

In this case, the 1 st outer peripheral portion of the base material faces one side in the circumferential direction. When the hard sintered body is used for cutting at the edge of a cutting tool, the circumferential direction is set to the tool rotation direction, whereby a load applied to the cutting tool in the circumferential direction can be applied to the 1 st outer peripheral portion of the base material. This can suppress the load applied in the direction perpendicular to the central axis of the tool, among the loads applied to the cutting tool during cutting, from acting along the interface between the base material and the cylindrical portion, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Preferably, in the hard sintered body, the pillar portion has: a 2 nd outer peripheral portion disposed on an outer peripheral portion of the pillar portion and constituting a part of the outer peripheral portion; and a base material convex portion that is located at a connecting portion between the 1 st outer peripheral portion and the 2 nd outer peripheral portion that are connected to each other in the cross-sectional view and extends in the axial direction, one side portion of the 2 nd outer peripheral portion that extends in the circumferential direction or the radial direction is located more radially outward than the other side portion in the cross-sectional view, the base material convex portion is located at a connecting portion between the other side portion of the 1 st outer peripheral portion and the one side portion of the 2 nd outer peripheral portion and protrudes radially outward, the tube portion including: a 2 nd inner peripheral portion disposed on an inner peripheral portion of the cylindrical portion and constituting a part of the inner peripheral portion; and a tube portion concave portion that is located at a connecting portion of the 1 st inner circumferential portion and the 2 nd inner circumferential portion that are connected to each other and extends in the axial direction in the cross-sectional view, in which one side portion of the 2 nd inner circumferential portion that extends in the circumferential direction or the radial direction is located more radially outward than the other side portion, the tube portion concave portion is located at a connecting portion of the other side portion of the 1 st inner circumferential portion and the one side portion of the 2 nd inner circumferential portion and is recessed radially outward, the 2 nd outer circumferential portion and the 2 nd inner circumferential portion are joined to each other, and the base material convex portion and the tube portion concave portion are joined to each other.

In this case, the base material has a base material ridge portion protruding radially outward, and the cylindrical portion concave portion of the cylindrical portion is joined to the base material ridge portion. Therefore, when the hard sintered body is used for cutting at the edge portion of the cutting tool, the load applied to the cutting tool in the circumferential direction can be received by the base material ridge portion. This can suppress the load applied in the direction perpendicular to the central axis of the tool, among the loads applied to the cutting tool during cutting, from acting along the interface between the base material and the cylindrical portion, and can further suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Preferably, in the hard sintered body, in the cross-sectional view, the 1 st outer peripheral portion is inclined at an angle of 4 ° or more and 170 ° or less with respect to a 2 nd straight line, the 2 nd straight line being orthogonal to a 1 st straight line extending in a radial direction through a radial outer end portion of the 1 st outer peripheral portion and the central axis, and the 2 nd straight line passing through a radial outer end portion of the 1 st outer peripheral portion.

In a cross-sectional view perpendicular to the central axis, a 2 nd straight line corresponds to a tangent line of a circumscribed circle of the pillar portion passing through the radial outer end portion of the 1 st outer circumferential portion, the 2 nd straight line being orthogonal to a 1 st straight line passing through the radial outer end portion of the 1 st outer circumferential portion and the central axis, and the 2 nd straight line passing through the radial outer end portion of the 1 st outer circumferential portion.

When the angle of inclination of the 1 st outer peripheral portion with respect to the 2 nd straight line is 4 ° or more in a cross-sectional view perpendicular to the central axis, when a hard sintered body obtained by sintering a base material and a cylindrical portion is used for cutting at the cutting edge portion of a cutting tool, the 1 st outer peripheral portion of the base material can stably receive a load in the circumferential direction of the cutting tool by assuming an attitude in which the 1 st outer peripheral portion faces the tool rotation direction. This can suppress the load applied in the direction perpendicular to the central axis of the tool, among the loads applied to the cutting tool during cutting, from acting along the interface between the base material and the cylindrical portion, and can further suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Further, when the angle of inclination of the 1 st outer peripheral portion with respect to the 2 nd straight line is 170 ° or less in a cross-sectional view perpendicular to the center axis, the thickness of the base material in the vicinity of the 1 st outer peripheral portion can be secured, and the rigidity of the base material can be secured. For example, a defect that the substrate becomes locally thin and becomes a crack starting point is suppressed. Therefore, the function based on the 1 st peripheral portion is stabilized.

Preferably, in the above hard sintered body, the 1 st outer peripheral portion is provided in plurality at intervals from each other in a circumferential direction, and the respective angles of the plurality of 1 st outer peripheral portions are equal to each other in the cross-sectional view.

In this case, when the hard sintered body obtained by sintering the base material and the cylindrical portion is used for cutting at the edge portion of the cutting tool, the function based on the 1 st outer circumferential portion is obtained at a plurality of positions in the circumferential direction of the cutting tool, and the load is uniformly applied to each 1 st outer circumferential portion. That is, it is possible to suppress a large load from continuously acting on the specific 1 st outer circumferential portion, and to more stably suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Preferably, in the hard sintered body, the base material for the hard sintered body has a young's modulus of 300GPa or more, and the cylindrical portion has a young's modulus of 600GPa or more.

When the young's modulus of the substrate for a hard sintered body is 300GPa or more, rigidity can be stably secured when the substrate is used for a cutting tool such as an end mill, for example.

Further, if the young's modulus of the cylindrical portion is 600GPa or more, the cylindrical portion can stably ensure wear resistance when used in a cutting tool such as an end mill, for example.

Preferably, in the above hard sintered body, the base material for the hard sintered body is made of any one of a hard alloy, a cermet and a ceramic, and the tube portion is made of any one of a polycrystalline diamond and a polycrystalline cubic boron nitride.

Preferably, in the cutting tool, the other side portion of the 1 st outer peripheral portion intersects with the cutting edge when viewed in a radial direction.

In this case, when the cutting tool is used for cutting, the 1 st outer peripheral portion of the base material can more easily receive a load in the circumferential direction applied to the cutting edge. Therefore, the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion can be suppressed, the chipping resistance of the cutting tool can be improved, and the tool life can be extended.

Preferably, in the cutting tool, the 1 st outer peripheral portion is provided in plurality at intervals from each other in a circumferential direction, the cutting edge is provided in one or more number, and the number of the 1 st outer peripheral portions is equal to or more than the number of the cutting edges.

In this case, the 1 st outer peripheral portion is easily arranged to intersect the cutting edge when viewed in the radial direction. When cutting is performed by the cutting tool, the load in the circumferential direction applied to each cutting edge can be easily and stably received in each 1 st outer peripheral portion of the base material. Therefore, the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion can be suppressed, the chipping resistance of the cutting tool can be improved, and the tool life can be extended.

According to the base material for a hard sintered body, the hard sintered body, and the cutting tool of one embodiment of the present invention, it is possible to suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion.

Drawings

Fig. 1 (a) is a cross-sectional view showing the hard sintered body of embodiment 1, and fig. 1 (b) is a longitudinal sectional view showing the hard sintered body of embodiment 1 (a side view of the base material for the hard sintered body and a longitudinal sectional view of the cylindrical portion).

Fig. 2 is a perspective view showing a substrate for a hard sintered body according to embodiment 1.

Fig. 3 is an enlarged cross-sectional view of a part of the hard sintered body according to embodiment 1.

Fig. 4 is a side view showing a cutting tool according to embodiment 1.

Fig. 5 is a cross-sectional view showing a 1 st modification of the base material for a hard sintered body according to embodiment 1.

Fig. 6 is a cross-sectional view showing a 2 nd modification of the base material for a hard sintered body according to embodiment 1.

Fig. 7 is a cross-sectional view showing a 3 rd modification of the base material for a hard sintered body according to embodiment 1.

Fig. 8 is a cross-sectional view showing a 4 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 9 is a cross-sectional view showing a 5 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 10 is a cross-sectional view showing a 6 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 11 is a cross-sectional view showing a 7 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 12 is a cross-sectional view showing an 8 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 13 is a cross-sectional view showing a 9 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 14 is a cross-sectional view showing a 10 th modification of the hard sintered body according to embodiment 1.

Fig. 15 (a) is a cross-sectional view showing an 11 th modification of the hard sintered body according to embodiment 1, and fig. 15 (b) is a longitudinal-sectional view showing the 11 th modification of the hard sintered body according to embodiment 1 (a side view of the base material for the hard sintered body and a longitudinal-sectional view of the cylindrical portion).

Fig. 16 is a perspective view showing a 12 th modification of the base material for a hard sintered body according to embodiment 1.

Fig. 17 (a) is a cross-sectional view showing a 13 th modification of the hard sintered body according to embodiment 1, and fig. 17 (b) is a longitudinal-sectional view showing the 13 th modification of the hard sintered body according to embodiment 1 (a side view of the base material for the hard sintered body and a longitudinal-sectional view of the cylindrical portion).

Fig. 18 (a) is a cross-sectional view showing a 14 th modification of the hard sintered body according to embodiment 1, and fig. 18 (b) is a longitudinal-sectional view showing the 14 th modification of the hard sintered body according to embodiment 1 (a side view of the base material for the hard sintered body and a longitudinal-sectional view of the tube portion).

Fig. 19 (a) is a cross-sectional view showing a 15 th modification of the hard sintered body according to embodiment 1, and fig. 19 (b) is a longitudinal-sectional view showing the 15 th modification of the hard sintered body according to embodiment 1 (a side view of the base material for the hard sintered body and a longitudinal-sectional view of the cylindrical portion).

Fig. 20 is a cross-sectional view showing a hard sintered body according to embodiment 2.

Fig. 21 is a cross-sectional view showing a 1 st modification of the hard sintered body according to embodiment 2.

Fig. 22 is a cross-sectional view showing a 2 nd modification of the hard sintered body according to embodiment 2.

Detailed Description

< embodiment 1 >

Hereinafter, a base material 1A (1) for a hard sintered body, a hard sintered body 10, and a cutting tool 50 according to embodiment 1 of the present invention will be described with reference to fig. 1 to 4. Fig. 1 and 3 show a hard sintered body 10 according to the present embodiment. Fig. 2 shows a substrate 1A for a hard sintered body according to the present embodiment. Fig. 4 shows a cutting tool 50 according to the present embodiment.

In the following description, the substrate 1A for a hard sintered body may be simply referred to as a substrate 1A. Further, the hard sintered body 10 may be referred to as an ultra-hard sintered body 10 or an ultra-high hardness sintered body 10 instead.

As shown in fig. 1 (a) and 1 (b), the hard sintered body 10 includes a base material 1A for a hard sintered body and a cylindrical portion 20 integrally sintered with the base material 1A for a hard sintered body. The Young's modulus of the substrate 1A is 300GPa or more. The base material 1A is made of any one of cemented carbide, cermet, and ceramics. The Young's modulus of the tube portion 20 is 600GPa or more. The cylindrical portion 20 is made of polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PcBN). The cylindrical portion 20 has a smaller linear expansion coefficient (thermal expansion coefficient) and higher hardness than the base material 1A.

The hard sintered body 10 is produced by filling a cylindrical container, not shown, with a base material 1A and a powdery tube portion 20 to be formed into a green compact, and sintering the same under ultra-high temperature and ultra-high pressure conditions.

As shown in fig. 1 to 3, the base material 1A has a multi-stage columnar shape with a central axis C as a center. The base material 1A includes a small diameter portion 2, a large diameter portion 3, and a base material end surface 4. The small diameter portion 2 is a "column portion" which is a constituent element of the present invention, and may be referred to as a column portion 2 in the following description. The small diameter portion 2 has a center axis C and extends in the axial direction of the center axis C. The large diameter portion 3 extends in the axial direction of the central axis C around the central axis C.

In the present embodiment, the direction in which the central axis C extends (the direction along the central axis C) is referred to as the axial direction. The small diameter portion 2 and the large diameter portion 3 are arranged at positions different from each other in the axial direction. In the axial direction, a direction from the large diameter portion 3 to the small diameter portion 2 is referred to as one axial side, and a direction from the small diameter portion 2 to the large diameter portion 3 is referred to as the other axial side.

The direction perpendicular to the central axis C is referred to as a radial direction. In the radial direction, a direction approaching the central axis C is referred to as a radially inner side, and a direction away from the central axis C is referred to as a radially outer side.

The direction of the circle around the central axis C is referred to as a circumferential direction. In the circumferential direction, a predetermined rotational direction is referred to as one circumferential side R1, and a rotational direction opposite to the predetermined rotational direction is referred to as the other circumferential side R2.

The central axis C of the base material 1A, the central axis C of the hard sintered body 10, and the central axis C of the cutting tool 50 are common axes and are disposed coaxially with each other.

The one axial side corresponds to a tip side (upper side in fig. 4) in the cutting tool 50 shown in fig. 4. The other axial side corresponds to a rear end side (lower side in fig. 4) of the cutting tool 50.

In the circumferential direction, a direction in which the cutting tool 50 is rotated by a spindle of a machine tool or the like during cutting is sometimes referred to as a tool rotation direction T, and a rotation direction opposite to the tool rotation direction T is sometimes referred to as an opposite direction to the tool rotation direction T (opposite direction to the tool rotation). In the present embodiment, one circumferential side R1 corresponds to the tool rotation direction T, and the other circumferential side R2 corresponds to the opposite direction of the tool rotation direction T.

In fig. 1 to 3, the small diameter portion (column portion) 2 is a columnar shape extending in the axial direction. In the present embodiment, the pillar portion 2 has a polygonal columnar shape. As shown in fig. 1 (a), the pillar portion 2 has a polygonal shape in a cross-sectional view perpendicular to the central axis C. In the present embodiment, the pillar portion 2 has a regular polygonal shape, specifically, a regular octagonal shape.

The pillar portion 2 has a 1 st outer peripheral portion 11, a 2 nd outer peripheral portion 12, and a raised base material portion 13.

The 1 st outer peripheral portion 11 is disposed on the outer peripheral portion of the pillar portion 2 and constitutes a part of the outer peripheral portion of the pillar portion 2. The 1 st outer peripheral portion 11 constitutes a part of the outer peripheral surface of the column portion 2 in the circumferential direction. The 1 st outer peripheral portion 11 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 3, the 1 st peripheral portion 11 extends in the circumferential direction or the radial direction. In the present embodiment, each 1 st outer circumferential portion 11 extends in the circumferential direction. Specifically, each of the 1 st outer peripheral portions 11 extends from each apex (each of the raised base material portions 13) located on the circumscribed circle of the pillar portion 2 toward the one circumferential side R1. Each apex of the pillar portion 2 is located on the outer peripheral surface of the pillar portion 2. A straight line denoted by symbol B in fig. 3 is a bisector B of an angle between a pair of straight lines connecting a pair of circumferentially adjacent apexes of the column part 2 and the central axis C. The 1 st outer peripheral portion 11 is located between the apex of the pillar portion 2 and the bisector B in the circumferential direction. The 1 st outer peripheral portion 11 extends from the apex of the pillar portion 2 to the circumferential one side R1 to the bisector B. In the cross-sectional view shown in fig. 3, the 1 st outer peripheral portion 11 is linear in the present embodiment. The 1 st outer peripheral portion 11 is located on a straight line connecting a pair of circumferentially adjacent apexes of the pillar portion 2.

In the cross-sectional view of fig. 3, one side portion (1 st end portion) 11a of the 1 st outer peripheral portion 11 is located more radially inward than the other side portion (2 nd end portion) 11 b. One side portion 11a of the 1 st outer peripheral portion 11 includes a portion located on the bisector B. The other side portion 11b of the 1 st outer peripheral portion 11 includes a portion located at the apex of the pillar portion 2. The 1 st outer peripheral portion 11 is located radially inward as it goes to the circumferential direction side R1. That is, the 1 st outer peripheral portion 11 extends radially inward toward the circumferential one side R1.

One side portion 11a of the 1 st outer peripheral portion 11 includes an end portion of the 1 st outer peripheral portion 11 on the circumferential direction side R1. The other side portion 11b of the 1 st outer peripheral portion 11 includes an end portion of the other circumferential side R2 in the 1 st outer peripheral portion 11. One side portion 11a of 1 st outer peripheral portion 11 includes a radially inner end portion which is an end portion on the radially inner side in 1 st outer peripheral portion 11. The other side portion 11b of the 1 st outer peripheral portion 11 includes a radially outer end portion that is a radially outer end portion of the 1 st outer peripheral portion 11.

In the cross-sectional view of fig. 3, a straight line denoted by a symbol L1 is a 1 st straight line L1 passing through the radially outer end portion of the 1 st outer peripheral portion 11 and the central axis C and extending in the radial direction. The 1 st line L1 is also a straight line passing through the apex (the raised base material portion 13) of the pillar portion 2 and the central axis C. The straight line denoted by reference character L2 is the 2 nd straight line L2 that is orthogonal to the 1 st straight line L1 and passes through the radially outer end portion of the 1 st outer peripheral portion 11. The 2 nd straight line L2 is also a straight line that is orthogonal to the 1 st straight line L1 and passes through the apex of the pillar portion 2. The 2 nd straight line L2 corresponds to a tangent line of a circumscribed circle of the pillar portion 2 passing through the radially outer end portion (the raised base material portion 13) of the 1 st outer peripheral portion 11.

In the present embodiment, in the cross-sectional view of fig. 3, the angle θ at which the 1 st outer peripheral portion 11 is inclined with respect to the 2 nd straight line L2 is 4 ° or more. Specifically, in this cross-sectional view, the angle θ is an angle between the other side portion 11b of the 1 st outer peripheral portion 11 and the 2 nd straight line L2. That is, the angle θ is an angle at which the 1 st outer peripheral portion 11 is inclined from the 2 nd straight line L2 toward the rotational direction of the circumferential one side R1. In this cross-sectional view, the respective angles θ of the plurality of 1 st peripheral portions 11 are equal to each other.

In the present embodiment, the 1 st outer peripheral portion 11 faces radially outward, specifically, the 1 st outer peripheral portion 11 extends from the radially outer end portion (the base material convex portion 13) of the 1 st outer peripheral portion 11 to the circumferential direction side R1, and the angle θ in this case is an acute angle out of an acute angle and an obtuse angle formed by the 2 nd straight line L2 intersecting the 1 st outer peripheral portion 11 in the cross-sectional view of fig. 3. Further, a more preferable range of the angle θ is 5 ° or more and 60 ° or less.

The 2 nd outer peripheral portion 12 is disposed on the outer peripheral portion of the pillar portion 2 and constitutes a part of the outer peripheral portion of the pillar portion 2. The 2 nd outer peripheral portion 12 constitutes a portion of the outer peripheral surface of the column portion 2 in a different circumferential direction from the 1 st outer peripheral portion 11. The 2 nd outer peripheral portion 12 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 3, the 2 nd peripheral portion 12 extends in the circumferential direction or the radial direction. In the present embodiment, each 2 nd outer peripheral portion 12 extends in the circumferential direction. Specifically, each of the 2 nd outer peripheral portions 12 extends from each apex (each of the raised base material portions 13) located on the circumscribed circle of the pillar portion 2 toward the other circumferential side R2. The 2 nd outer peripheral portion 12 is located between the apex of the pillar portion 2 and the bisector B in the circumferential direction. The 2 nd outer peripheral portion 12 extends from the apex of the pillar portion 2 to the other circumferential side R2 to the bisector B. In the cross-sectional view shown in fig. 3, the 2 nd outer peripheral portion 12 is linear in the present embodiment. The 2 nd outer peripheral portion 12 is located on a straight line connecting a pair of circumferentially adjacent apexes of the pillar portion 2. That is, in the present embodiment, on a straight line connecting a pair of circumferentially adjacent vertices of the pillar portion 2, the 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 are disposed adjacent to each other on both circumferential sides about the bisector B.

In the cross-sectional view of fig. 3, one side portion (1 st end portion) 12a of the 2 nd outer peripheral portion 12 is located radially outward of the other side portion (2 nd end portion) 12 b. One side portion 12a of the 2 nd outer peripheral portion 12 includes a portion located at the apex of the pillar portion 2. The other side portion 12B of the 2 nd outer peripheral portion 12 includes a portion located on the bisector B. The 2 nd outer peripheral portion 12 is located radially outward as it goes toward the circumferential direction side R1. That is, the 2 nd outer peripheral portion 12 extends radially outward as it goes to the circumferential direction side R1.

One side portion 12a of the 2 nd outer peripheral portion 12 includes an end portion of the circumferential direction one side R1 in the 2 nd outer peripheral portion 12. The other side portion 12b of the 2 nd outer peripheral portion 12 includes an end portion of the other circumferential direction side R2 in the 2 nd outer peripheral portion 12. One side portion 12a of the 2 nd outer peripheral portion 12 includes a radially outer end portion, i.e., a radially outer end portion, in the 2 nd outer peripheral portion 12. The other side portion 12b of the 2 nd outer peripheral portion 12 includes a radially inner end portion, i.e., a radially inner end portion, in the 2 nd outer peripheral portion 12.

In the present embodiment, since the pillar portion 2 has a regular polygonal shape in a cross-sectional view perpendicular to the center axis C, the angle at which the 2 nd outer peripheral portion 12 is inclined with respect to the 2 nd straight line L2 in the cross-sectional view of fig. 3 is the same value as the angle θ. Specifically, in this cross-sectional view, the angle is an angle between one side portion 12a of the 2 nd outer peripheral portion 12 and the 2 nd straight line L2. In this cross-sectional view, the respective angles of the plurality of 2 nd peripheral portions 12 are equal to each other.

The plurality of 1 st outer peripheral portions 11 and the plurality of 2 nd outer peripheral portions 12 are alternately arranged in the circumferential direction. In the cross-sectional view shown in fig. 3, the 1 st peripheral portion 11 and the 2 nd peripheral portion 12 are connected to each other. The 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 are connected to each other in the circumferential direction.

The 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 adjacent in the circumferential direction are connected to each other at the apex of the pillar portion 2. That is, the other side portion 11b of the 1 st outer peripheral portion 11 and the one side portion 12a of the 2 nd outer peripheral portion 12 are continuous at the apex of the pillar portion 2. The 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 adjacent in the circumferential direction are connected to each other on a bisector B. That is, one side portion 11a of the 1 st outer peripheral portion 11 and the other side portion 12B of the 2 nd outer peripheral portion 12 are connected on the bisector B.

In the cross-sectional view shown in fig. 3, the base material ridge portion 13 is located at a connecting portion of the 1 st peripheral portion 11 and the 2 nd peripheral portion 12 connected to each other, and extends in the axial direction. The base convex strip portion 13 is located at a connecting portion between the other side portion 11b of the 1 st outer peripheral portion 11 and the one side portion 12a of the 2 nd outer peripheral portion 12, and projects radially outward. In the present embodiment, the convex base material portion 13 has a sharp corner at the radially outer end of the convex base material portion 13.

As shown in fig. 1 (b) and 2, in the present embodiment, the base convex stripe 13 extends in the axial direction along the central axis C. The base material convex stripe portion 13 is provided in plurality at intervals in the circumferential direction. In the cross-sectional view of fig. 3, the plurality of substrate ridges 13 are arranged so as to be rotationally symmetrical (point-symmetrical) about the center axis C. That is, the plurality of base convex portions 13 are arranged at equal intervals in the circumferential direction.

As shown in fig. 1 and 2, the large diameter portion 3 has a cylindrical shape extending in the axial direction. The large diameter portion 3 has an outer diameter larger than the small diameter portion (column portion) 2. The outer diameter (diameter) of the large diameter portion 3 is, for example, approximately twice the outer diameter of the small diameter portion 2. The axial length of the large diameter portion 3 is smaller than that of the small diameter portion 2. An end surface 3a of the large diameter portion 3 facing the other axial side is a flat surface expanding in a direction perpendicular to the central axis C. The end face 3a is circular.

The base end surface 4 is located between an end portion on one axial side of the outer peripheral surface of the large diameter portion 3 and an end portion on the other axial side of the small diameter portion 2, and faces one axial side. The base end surface 4 is disposed between one axial end of the outer peripheral surface of the large diameter portion 3 and the other axial end of the outer peripheral surface of the small diameter portion 2. The base end surface 4 is annular with a center axis C as a center. In the present embodiment, the base end surface 4 is a flat surface extending in a direction perpendicular to the central axis C.

As shown in fig. 1 (a) and 1 (b), the cylindrical portion 20 has a cylindrical shape covering the small diameter portion (column portion) 2 from the radially outer side. The cylindrical portion 20 is cylindrical about the central axis C, and extends in the axial direction. In the present embodiment, the cylindrical portion 20 has a top cylindrical shape. The cylinder 20 has a peripheral wall 21, a ceiling wall 22, and a cylinder end surface 23.

The peripheral wall portion 21 is cylindrical and extends in the axial direction. The peripheral wall portion 21 surrounds the pillar portion 2 from the outside in the radial direction. In the cross-sectional view shown in fig. 1 (a), the inner peripheral surface of the peripheral wall portion 21 is polygonal. In the present embodiment, the inner peripheral surface of the peripheral wall portion 21 has a regular polygonal shape, specifically, a regular octagonal shape. The inner peripheral surface of the peripheral wall portion 21 is fixed to the outer peripheral surface of the pillar portion 2. The inner peripheral surface of the peripheral wall portion 21 (i.e., the inner peripheral surface of the cylindrical portion 20) is joined to the outer peripheral surface of the pillar portion 2.

The peripheral wall portion 21 has a 1 st inner peripheral portion 31, a 2 nd inner peripheral portion 32, and a tube portion concave portion 33. That is, the tube portion 20 includes a 1 st inner circumferential portion 31, a 2 nd inner circumferential portion 32, and a tube portion concave portion 33.

The 1 st inner circumferential portion 31 is disposed on the inner circumferential portion of the circumferential wall portion 21. That is, the 1 st inner circumferential portion 31 is disposed on the inner circumferential portion of the tube portion 20, and constitutes a part of the inner circumferential portion of the tube portion 20. The 1 st inner circumferential portion 31 constitutes a part of the inner circumferential surface of the circumferential wall portion 21 (the tube portion 20) in the circumferential direction. The 1 st inner circumferential portion 31 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 3, the 1 st inner peripheral portion 31 extends in the circumferential direction or the radial direction. In the present embodiment, each 1 st inner circumferential portion 31 extends in the circumferential direction. Specifically, the 1 st inner circumferential portion 31 extends from each apex (each tube portion concave portion 33) located on the inner circumferential surface of the circumferential wall portion 21 toward the one circumferential side R1. The bisector B is also an angle between a pair of straight lines connecting a pair of circumferentially adjacent apexes of the inner peripheral surface of the peripheral wall portion 21 and the central axis C. The 1 st inner circumferential portion 31 is located between the apex of the inner circumferential surface of the circumferential wall portion 21 and the bisector B in the circumferential direction. The 1 st inner peripheral portion 31 extends from the apex of the peripheral wall portion 21 to the bisector B toward the circumferential one side R1. In the cross-sectional view shown in fig. 3, the 1 st inner peripheral portion 31 is linear in the present embodiment. The 1 st inner peripheral portion 31 is located on a straight line connecting a pair of circumferentially adjacent apexes of the inner peripheral surface of the peripheral wall portion 21 to each other.

In the cross-sectional view of fig. 3, one side portion (1 st end portion) 31a of the 1 st inner circumferential portion 31 is located more radially inward than the other side portion (2 nd end portion) 31 b. One side portion 31a of the 1 st inner peripheral portion 31 includes a portion located on the bisector B. The other side portion 31b of the 1 st inner peripheral portion 31 includes a portion located at the apex of the inner peripheral surface of the peripheral wall portion 21. The 1 st inner circumferential portion 31 is located radially inward as it goes to the circumferential direction one side R1. That is, the 1 st inner circumferential portion 31 extends radially inward toward the circumferential direction one side R1.

One side portion 31a of the 1 st inner circumferential portion 31 includes an end of the circumferential direction one side R1 in the 1 st inner circumferential portion 31. The other side portion 31b of the 1 st inner circumferential portion 31 includes an end of the other circumferential direction side R2 in the 1 st inner circumferential portion 31. One side portion 31a of the 1 st inner circumferential portion 31 includes a radially inner end portion, i.e., a radially inner end portion, in the 1 st inner circumferential portion 31. The other side portion 31b of the 1 st inner circumferential portion 31 includes a radially outer end portion, i.e., a radially outer end portion, in the 1 st inner circumferential portion 31.

The 1 st straight line L1 also passes through the radially outer end portion and the central axis C of the 1 st inner circumferential portion 31 and extends in the radial direction. The 1 st straight line L1 is also a straight line passing through the apex (tube portion concave portion 33) of the inner peripheral surface of the peripheral wall portion 21 and the central axis C. The 2 nd straight line L2 is also a straight line that is orthogonal to the 1 st straight line L1 and passes through the radially outer end of the 1 st inner circumferential portion 31. The 2 nd straight line L2 is also a straight line that is orthogonal to the 1 st straight line L1 and passes through the apex of the inner peripheral surface of the peripheral wall portion 21.

In the present embodiment, in the cross-sectional view of fig. 3, the angle θ at which the 1 st inner peripheral portion 31 is inclined with respect to the 2 nd straight line L2 is 4 ° or more. Specifically, in this cross-sectional view, the angle θ is an angle between the other side portion 31b of the 1 st inner peripheral portion 31 and the 2 nd straight line L2. In the cross-sectional view, the respective angles θ of the plurality of 1 st inner peripheral portions 31 are equal to each other.

Each 1 st inner circumferential portion 31 is in contact with each 1 st outer circumferential portion 11. The 1 st outer circumferential portion 11 and the 1 st inner circumferential portion 31 are joined to each other. One side portion 11a of the 1 st outer peripheral portion 11 and one side portion 31a of the 1 st inner peripheral portion 31 are opposed in the radial direction and joined to each other. The other side portion 11b of the 1 st outer peripheral portion 11 and the other side portion 31b of the 1 st inner peripheral portion 31 are opposed in the radial direction and joined to each other.

The 2 nd inner peripheral portion 32 is disposed on the inner peripheral portion of the peripheral wall portion 21. That is, the 2 nd inner circumferential portion 32 is disposed on the inner circumferential portion of the tube portion 20, and constitutes a part of the inner circumferential portion of the tube portion 20. The 2 nd inner peripheral portion 32 constitutes a portion of the inner peripheral surface of the peripheral wall portion 21 in a circumferential direction different from the 1 st inner peripheral portion 31. The 2 nd inner peripheral portion 32 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 3, the 2 nd inner peripheral portion 32 extends in the circumferential direction or the radial direction. In the present embodiment, each 2 nd inner circumferential portion 32 extends in the circumferential direction. Specifically, the 2 nd inner circumferential portion 32 extends from each apex (each tube portion concave portion 33) located on the inner circumferential surface of the circumferential wall portion 21 toward the other circumferential side R2. The 2 nd inner peripheral portion 32 is located between the apex of the inner peripheral surface of the peripheral wall portion 21 and the bisector B in the circumferential direction. The 2 nd inner peripheral portion 32 extends from the apex of the peripheral wall portion 21 to the bisector B toward the other circumferential side R2. In the cross-sectional view shown in fig. 3, the 2 nd inner peripheral portion 32 is linear in the present embodiment. The 2 nd inner peripheral portion 32 is located on a straight line connecting a pair of circumferentially adjacent apexes of the inner peripheral surface of the peripheral wall portion 21 to each other. That is, in the present embodiment, the 1 st inner circumferential portion 31 and the 2 nd inner circumferential portion 32 are disposed adjacent to each other on both sides in the circumferential direction around the bisector B on a straight line connecting a pair of circumferentially adjacent apexes of the inner circumferential surface of the circumferential wall portion 21.

In the cross-sectional view of fig. 3, one side portion (1 st end portion) 32a of the 2 nd inner peripheral portion 32 is located more radially outward than the other side portion (2 nd end portion) 32 b. One side portion 32a of the 2 nd inner peripheral portion 32 includes a portion located at an apex of the inner peripheral surface of the peripheral wall portion 21. The other side portion 32B of the 2 nd inner peripheral portion 32 includes a portion located on the bisector B. The 2 nd inner peripheral portion 32 is located radially outward as it goes toward the circumferential direction one side R1. That is, the 2 nd inner peripheral portion 32 extends radially outward as it goes to the circumferential direction one side R1.

One side portion 32a of the 2 nd inner peripheral portion 32 includes an end portion of the circumferential direction one side R1 in the 2 nd inner peripheral portion 32. The other side portion 32b of the 2 nd inner peripheral portion 32 includes an end portion of the other circumferential direction side R2 in the 2 nd inner peripheral portion 32. One side portion 32a of the 2 nd inner peripheral portion 32 includes a radially outer end portion, i.e., a radially outer end portion, in the 2 nd inner peripheral portion 32. The other side portion 32b of the 2 nd inner peripheral portion 32 includes a radially inner end portion, i.e., a radially inner end portion, in the 2 nd inner peripheral portion 32.

In the present embodiment, since the inner peripheral surface of the peripheral wall portion 21 has a regular polygonal shape in a cross-sectional view perpendicular to the center axis C, the 2 nd inner peripheral portion 32 is inclined at the same angle as the angle θ described above with respect to the 2 nd straight line L2 in the cross-sectional view of fig. 3. Specifically, in this cross-sectional view, the angle is an angle between one side portion 32a of the 2 nd inner peripheral portion 32 and the 2 nd straight line L2. In this cross-sectional view, the respective angles of the plurality of 2 nd inner peripheral portions 32 are equal to each other.

The plurality of 1 st inner circumferential portions 31 and the plurality of 2 nd inner circumferential portions 32 are alternately arranged in the circumferential direction. In the cross-sectional view shown in fig. 3, the 1 st inner peripheral portion 31 and the 2 nd inner peripheral portion 32 are connected to each other. The 1 st inner peripheral portion 31 and the 2 nd inner peripheral portion 32 are connected to each other in the circumferential direction.

The 1 st inner circumferential portion 31 and the 2 nd inner circumferential portion 32 adjacent in the circumferential direction are connected to each other at the apex of the inner circumferential surface of the circumferential wall portion 21. That is, the other side portion 31b of the 1 st inner peripheral portion 31 is continuous with the one side portion 32a of the 2 nd inner peripheral portion 32 at the apex of the peripheral wall portion 21. The 1 st inner peripheral portion 31 and the 2 nd inner peripheral portion 32 adjacent in the circumferential direction are connected to each other on a bisector B. That is, one side portion 31a of the 1 st inner peripheral portion 31 is connected to the other side portion 32B of the 2 nd inner peripheral portion 32 on the bisector B.

Each 2 nd inner circumferential portion 32 is in contact with each 2 nd outer circumferential portion 12. The 2 nd outer peripheral portion 12 and the 2 nd inner peripheral portion 32 are engaged with each other. One side portion 12a of the 2 nd outer peripheral portion 12 and one side portion 32a of the 2 nd inner peripheral portion 32 are opposed in the radial direction and joined to each other. The other side portion 12b of the 2 nd outer peripheral portion 12 and the other side portion 32b of the 2 nd inner peripheral portion 32 are opposed in the radial direction and joined to each other.

In the cross-sectional view shown in fig. 3, the tube portion concave portion 33 is located at a connecting portion of the 1 st inner circumferential portion 31 and the 2 nd inner circumferential portion 32 connected to each other, and extends in the axial direction. The tube-section concave portion 33 is located at a connecting portion between the other side portion 31b of the 1 st inner circumferential portion 31 and the one side portion 32a of the 2 nd inner circumferential portion 32, and is recessed radially outward.

In the present embodiment, the cylindrical concave portion 33 extends in the axial direction along the central axis C. The plurality of barrel concave portions 33 are provided at intervals in the circumferential direction. In the cross-sectional view of fig. 3, the plurality of barrel concave portions 33 are arranged to be rotationally symmetrical about the central axis C. That is, the plurality of cylindrical concave portions 33 are arranged at equal intervals in the circumferential direction.

Each of the barrel concave portions 33 contacts each of the base material convex portions 13. The base material convex strip 13 and the barrel concave strip 33 are joined to each other.

As shown in fig. 1 (b), the top wall portion 22 is connected to one axial end of the peripheral wall portion 21. The top wall 22 has a circular plate shape centered on the central axis C. The pair of plate surfaces of the top wall portion 22 face the axial direction. The plate surface of the top wall portion 22 facing the other axial side is fixed to the end surface 2a of the pillar portion 2 facing the one axial side. An end surface 2a of the column part 2 facing the axial direction side is a flat surface perpendicular to the central axis C. An end surface 2a of the column part 2 facing one axial direction side is polygonal. The plate surface of the top wall portion 22 facing the other axial side is joined to the end surface 2a of the pillar portion 2 facing the one axial side.

The cylindrical end surface 23 is located at the other axial end of the peripheral wall portion 21 and faces the other axial end. The cylindrical end surface 23 is annular around the central axis C. In the present embodiment, the cylindrical end surface 23 is a flat surface extending in a direction perpendicular to the central axis C. The cylinder end surface 23 is fixed to the base end surface 4. The cylinder end surface 23 is joined to the base end surface 4.

The cutting tool 50 is a rotary cutting tool (milling tool), specifically, an end mill, a reamer, a drill, or the like. As shown in fig. 4, the cutting tool 50 of the present embodiment is an end mill.

The cutting tool 50 includes: a blade portion 51 provided with a chip groove 55 and a cutting edge (outer peripheral edge) 56 extending in the axial direction on the outer peripheral portion of the hard sintered body 10; and a shank 52 connected to the blade 51 in the axial direction. That is, the edge portion 51 is formed by grinding the chip groove 55 and the cutting edge 56 with a grinding wheel or the like on the outer peripheral portion of the hard sintered body 10. That is, the hard sintered body 10 is a blank for producing the blade portion 51, and is an intermediate of the blade portion 51 produced in the production process of the cutting tool 50. The outer peripheral surface of the blade 51 is disposed on the peripheral wall 21 of the cylinder 20.

The shank 52 is made of cemented carbide. The shank 52 has a cylindrical shape extending in the axial direction. The blade portion 51 and the shank portion 52 are joined to each other by brazing under induction heating under vacuum using Ag brazing filler metal, for example. That is, the end surface 3a facing the other axial side of the blade portion 51 (the end surface of the large diameter portion 3) and the end surface 52a facing the one axial side of the shank portion 52 are joined to each other by brazing.

In the cutting tool 50, a shank 52 is detachably attached to a spindle of a machine tool (not shown) or the like, and is rotated around a center axis C by the spindle of the machine tool or the like, thereby cutting (milling) a workpiece. The cutting tool 50 of the present embodiment is suitable for cutting a difficult-to-cut material, such as a non-ferrous titanium alloy or an aluminum alloy, a Carbon Fiber Reinforced Plastic (CFRP), or a carbon fiber reinforced carbon composite material called a C — C composite material, as a material to be cut.

The chip grooves 55 are recessed radially inward from the outer peripheral surface of the cutting tool 50, and extend in the axial direction. In the present embodiment, the chip grooves 55 extend spirally from one axial end portion (front end portion) of the cutting tool 50 toward the other axial end portion (rear end side) in the opposite direction to the tool rotation direction T.

One or more chip grooves 55 are provided in the cutting tool 50. In the present embodiment, the plurality of chip grooves 55 are provided. The plurality of chip grooves 55 are arranged at intervals in the circumferential direction. In the present embodiment, the plurality of chip grooves 55 are arranged at equal intervals (at equal intervals) in the circumferential direction on the outer periphery of the cutting tool 50 so as to be rotationally symmetrical with respect to the central axis C. Further, the plurality of chip grooves 55 may be arranged at unequal intervals (unequal pitches) in the circumferential direction.

The cutting edge 56 is disposed on the edge portion 51 and extends in the axial direction. The cutting edge 56 is formed on the intersecting ridge line between the wall surface of the chip groove 55 facing the tool rotation direction T and the outer peripheral surface of the blade portion 51. The cutting edge 56 extends spirally in a direction opposite to the tool rotation direction T from one end (tip end) in the axial direction of the blade portion 51 toward the other end in the axial direction.

The number of the cutting edges 56 is one or more. The number of cutting edges 56 is the same as the number of flutes 55. In the present embodiment, the cutting edge 56 is provided in plurality. Each cutting edge 56 extends along each flute 55. In the present embodiment, the plurality of cutting edges 56 are disposed at equal intervals (at equal intervals) in the circumferential direction on the outer periphery of the edge portion 51 so as to be rotationally symmetrical with respect to the central axis C. The plurality of cutting edges 56 may be arranged at unequal intervals (at unequal intervals) in the circumferential direction.

The cutting edge 56 is disposed on the peripheral wall portion 21 of the cylindrical portion 20 of the hard sintered body 10, and constitutes a part of the outer peripheral portion of the blade portion 51.

The chip groove 55 is disposed on the peripheral wall portion 21 of the cylindrical portion 20 and the column portion 2. In the wall surface of the chip groove 55 facing the tool rotation direction T, the outer peripheral portion adjacent to the cutting edge 56, that is, the rake surface of the cutting edge 56 is disposed on the peripheral wall portion 21 of the cylinder portion 20.

In the outer peripheral surface of the edge portion 51, a portion adjacent to the cutting edge 56, that is, a flank of the cutting edge 56 is disposed on the peripheral wall portion 21 of the cylinder portion 20.

As shown in fig. 4, the other side portion 11b of the 1 st outer peripheral portion 11 of the base material 1A intersects with the cutting edge 56 when viewed in the radial direction. The substrate ridge 13 intersects the cutting edge 56 when viewed in the radial direction. In the present embodiment, the number of the 1 st outer peripheral portion 11 is equal to or greater than the number of the cutting edges 56. The number of the base material ridges 13 is equal to or greater than the number of the cutting edges 56.

The blade portion 51 of the present embodiment includes a center groove 57 and a bottom edge 58 in addition to the chip grooves 55 and the cutting edges 56. The center groove 57 is located at an end portion on one axial side of the chip groove 55. The center groove 57 is a groove shape extending in the radial direction. The plurality of chip grooves 55 are provided with center grooves 57, respectively.

The end cutting edge 58 is disposed at one axial end of the blade portion 51 and extends in the radial direction. The bottom edge 58 is provided in plurality at intervals from each other in the circumferential direction. The bottom blade 58 may be disposed on the top wall portion 22 of the barrel portion 20.

The base material 1A for a hard sintered body of the present embodiment described above has the base material convex portions 13 protruding radially outward. Further, the cylindrical portion 20 integrally sintered with the base material 1A is provided with portions (cylindrical recessed portions 33) to be joined to the base material convex portions 13. Therefore, when the hard sintered body 10 obtained by sintering the base material 1A and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the load applied to the cutting tool 50 in the circumferential direction can be received by the base material ridges 13. This can suppress a load applied in a direction perpendicular to the central axis C of the tool, among loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1A and the cylindrical portion 20, that is, can reduce a shear force along the interface, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20. Accordingly, the chipping resistance of the cutting tool 50 manufactured using the hard sintered body 10 can be improved, and the tool life can be extended.

In the present embodiment, the convex base material portion 13 has a sharp corner at the radially outer end, and therefore the function (action) of the convex base material portion 13 is further improved.

In the present embodiment, a plurality of the raised base material strips 13 are provided at intervals in the circumferential direction.

In this case, when the hard sintered body 10 obtained by sintering the base material 1A and the cylindrical portion 20 is used for cutting by the cutting edge portion 51 of the cutting tool 50, the function based on the base material convex portion 13 can be obtained at a plurality of portions in the circumferential direction of the cutting tool 50. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20 can be stably suppressed, and the chipping resistance of the cutting tool 50 can be further improved.

In the present embodiment, the plurality of raised base material portions 13 are arranged in a rotational symmetry about the central axis C in a cross-sectional view perpendicular to the central axis C.

In this case, when the hard sintered body 10 obtained by sintering the base material 1A and the cylindrical portion 20 is used for cutting by the cutting edge portion 51 of the cutting tool 50, the load is uniformly applied to each of the base material ridges 13. That is, it is possible to suppress a large load from continuously acting on the specific substrate ridges 13, and to more stably suppress the occurrence of cracks or chipping in the vicinity of the interface between the substrate 1A and the cylindrical portion 20.

In the present embodiment, the pillar portion 2 has a polygonal shape in a cross-sectional view perpendicular to the central axis C.

In this case, the structure of the present embodiment can be easily realized, and the manufacturing is easy.

In the hard sintered body 10 and the cutting tool 50 of the present embodiment, in a cross-sectional view perpendicular to the central axis C, one side portion 11A of the 1 st outer peripheral portion 11 of the base material 1A is located radially inward of the other side portion 11b, that is, the 1 st outer peripheral portion 11 faces in the circumferential direction (one circumferential side R1). In the cross-sectional view, the one side portion 31a of the 1 st inner circumferential portion 31 of the cylindrical portion 20 is located radially inward of the other side portion 31b, that is, the 1 st inner circumferential portion 31 faces the circumferential direction (the other circumferential side R2). Further, the 1 st outer circumferential portion 11 and the 1 st inner circumferential portion 31 facing the circumferential direction are joined to each other.

When the hard sintered body 10 is used for cutting by the blade portion 51 of the cutting tool 50, the 1 st outer peripheral portion 11 of the base material 1A is oriented in the tool rotation direction T, and thus a load applied in the circumferential direction of the cutting tool 50 can be received in the 1 st outer peripheral portion 11. This can suppress a load applied in a direction perpendicular to the central axis C of the tool, among loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1A and the cylindrical portion 20, that is, can reduce a shear force along the interface, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20. Accordingly, the chipping resistance of the cutting tool 50 manufactured using the hard sintered body 10 can be improved, and the tool life can be extended.

In the present embodiment, the 1 st outer circumferential portion 11 is located radially inward toward the circumferential direction side R1, and the 1 st inner circumferential portion 31 is located radially inward toward the circumferential direction side R1. In this case, the 1 st outer peripheral portion 11 of the base material 1A faces one circumferential side R1. When the hard sintered body 10 is used for cutting the edge portion 51 of the cutting tool 50, a load applied in the circumferential direction of the cutting tool 50 can be received in the 1 st outer peripheral portion 11 of the base material 1A by setting the circumferential direction side R1 as the tool rotation direction T. This can suppress the load applied in the direction perpendicular to the central axis C of the tool, of the loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1A and the cylindrical portion 20, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20.

In the hard sintered body 10 of the present embodiment, the base material 1A has base material ridges 13 protruding radially outward, and the cylindrical recessed ridges 33 of the cylindrical portion 20 are joined to the base material ridges 13. Therefore, when the hard sintered body 10 is used for cutting by the blade portion 51 of the cutting tool 50, the load applied to the circumferential direction of the cutting tool 50 can be received by the base material ridge portion 13. This can further suppress the load applied in the direction perpendicular to the central axis C of the tool, among the loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1A and the cylindrical portion 20, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20.

In the present embodiment, the angle θ at which the 1 st outer peripheral portion 11 is inclined with respect to the 2 nd straight line L2 (the tangent to the circumscribed circle of the pillar portion 2) passing through the radially outer end portion (the raised base material portion 13) of the 1 st outer peripheral portion 11 is 4 ° or more in a cross-sectional view perpendicular to the central axis C.

When the angle θ at which the 1 st outer peripheral portion 11 is inclined with respect to the 2 nd straight line L2 is 4 ° or more in the cross-sectional view perpendicular to the central axis C, when the hard sintered body 10 obtained by sintering the base material 1A and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the 1 st outer peripheral portion 11 of the base material 1A can stably receive a load applied in the circumferential direction of the cutting tool 50 by assuming an orientation in which the 1 st outer peripheral portion 11 faces the tool rotation direction T. This can further suppress the load applied in the direction perpendicular to the central axis C of the tool, among the loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1A and the cylindrical portion 20, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20. In order to receive the load in the circumferential direction applied to the cutting tool 50 more stably by the 1 st outer peripheral portion 11, the angle θ is preferably 5 ° or more.

Further, as shown in the present embodiment, when the 1 st outer peripheral portion 11 is provided in plurality at intervals in the circumferential direction, if the angle θ at which the 1 st outer peripheral portion 11 is inclined with respect to the 2 nd straight line L2 is 60 ° or less in the cross-sectional view perpendicular to the center axis C, the thickness of the substrate 1A in the vicinity of the 1 st outer peripheral portion 11 can be ensured, and the rigidity of the substrate 1A can be ensured.

In the present embodiment, the angles θ of the plurality of 1 st outer circumferential portions 11 are equal to each other in a cross-sectional view perpendicular to the center axis C.

In this case, when the hard sintered body 10 obtained by sintering the base material 1A and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the function based on the 1 st outer peripheral portion 11 is obtained at a plurality of locations in the circumferential direction of the cutting tool 50, and the load is uniformly applied to each 1 st outer peripheral portion 11. That is, it is possible to suppress a large load from continuously acting on the specific 1 st outer peripheral portion 11, and to more stably suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20.

In the present embodiment, the young's modulus of the hard sintered body base material 1A is 300GPa or more, and the young's modulus of the sintered cylindrical portion 20 is 600GPa or more.

When the young's modulus of the substrate 1A for a hard sintered body is 300GPa or more, the substrate 1A can stably secure rigidity when used in a cutting tool 50 such as an end mill as in the present embodiment.

When the young's modulus of the cylindrical portion 20 is 600GPa or more, the cylindrical portion 20 can stably ensure wear resistance when used in the cutting tool 50 such as an end mill as in the present embodiment.

In the cutting tool 50 of the present embodiment, the other side portion 11b (the raised base material portion 13) of the 1 st outer peripheral portion 11 intersects with the cutting edge 56 when viewed in the radial direction.

In this case, when the cutting tool 50 is used for cutting, the 1 st outer peripheral portion 11 of the base material 1A can more easily receive a load in the circumferential direction applied to the cutting edge 56. Therefore, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20 can be suppressed, the chipping resistance of the cutting tool 50 can be improved, and the tool life can be extended.

In the present embodiment, the number of the 1 st outer peripheral portion 11 is equal to or greater than the number of the cutting edges 56.

In this case, the 1 st outer peripheral portion 11 is easily arranged to intersect the cutting edge 56 when viewed in the radial direction. When the cutting tool 50 is used for cutting, the 1 st outer peripheral portion 11 of the base material 1A can stably receive a load in the circumferential direction applied to each cutting edge 56. Therefore, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1A and the cylindrical portion 20 can be suppressed, the chipping resistance of the cutting tool 50 can be improved, and the tool life can be extended.

Fig. 5 shows a substrate 1B (1) for a hard sintered body according to modification 1 of the present embodiment. In the modification 1, the base material convex portion 13 has a convex curved shape in a cross-sectional view perpendicular to the center axis C shown in fig. 5. That is, in the cross-sectional view, the base material ridge portion 13 has a convex curved shape protruding radially outward. In this cross-sectional view, the end of the other circumferential side R2 in the other side portion 11b of the 1 st outer peripheral portion 11 has a convex curved shape, and the end of the one circumferential side R1 in the one side portion 12a of the 2 nd outer peripheral portion 12 has a convex curved shape.

Fig. 6 shows a substrate 1C (1) for a hard sintered body according to modification 2 of the present embodiment. In this modification 2, in a cross-sectional view perpendicular to the center axis C shown in fig. 6, the 1 st outer peripheral portion 11 is shaped like a concave curve, and the 2 nd outer peripheral portion 12 is shaped like a concave curve. That is, in this cross-sectional view, the 1 st outer peripheral portion 11 is formed in a concave curve shape that is concave inward in the radial direction, and the 2 nd outer peripheral portion 12 is formed in a concave curve shape that is concave inward in the radial direction. The 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 are located on one concave curve passing through a pair of apexes (base material convex portions 13) adjacent in the circumferential direction of the pillar portion 2, and are arranged adjacent to each other in the circumferential direction.

The amount of radial displacement per unit length in the circumferential direction (i.e., the inclination with respect to the circumferential direction) of the 1 st outer peripheral portion 11 increases toward the other circumferential direction side R2. That is, the amount of radial displacement per unit length in the circumferential direction at the other side portion 11b of the 1 st outer peripheral portion 11 including the end of the other circumferential side R2 is larger than the amount of radial displacement per unit length in the circumferential direction at the one side portion 11a of the 1 st outer peripheral portion 11 including the end of the one circumferential side R1.

The amount of radial displacement per unit length in the circumferential direction of the 2 nd outer peripheral portion 12 increases toward the circumferential direction side R1. That is, the amount of radial displacement per unit length in the circumferential direction at one side portion 12a of the 2 nd outer peripheral portion 12, which includes the end of the one circumferential direction side R1, is larger than the amount of radial displacement per unit length in the circumferential direction at the other side portion 12b of the 2 nd outer peripheral portion 12, which includes the end of the other circumferential direction side R2.

Fig. 7 shows a substrate 1D (1) for a hard sintered body according to modification 3 of the present embodiment. In this modification 3, in a cross-sectional view perpendicular to the center axis C shown in fig. 7, the 1 st outer peripheral portion 11 is shaped like a concave curve, and the 2 nd outer peripheral portion 12 is shaped like a concave curve. In the cross-sectional view, the substrate ridges 13 are formed in a convex curved shape.

In the cross-sectional view perpendicular to the central axis C of the base material 1B of fig. 5 and the base material 1D of fig. 7, the base material convex portions 13 are convex curved.

In this case, when the hard sintered body 10 obtained by sintering the base material 1 and the cylindrical portion 20 is used for cutting by the cutting edge portion 51 of the cutting tool 50, the load is suppressed from concentrating on the tip (radially outer end) in the base material ridge portion 13. Therefore, the occurrence of cracks or chipping in the vicinity of the raised base material strip 13 can be easily suppressed.

In the substrate 1C of fig. 6 and the substrate 1D of fig. 7, the amount of radial displacement per unit length in the circumferential direction of the 1 st outer peripheral portion 11 increases toward the other circumferential side R2.

In this case, it is easy to make the other side portion 11b including the end of the other circumferential side R2 in the 1 st outer circumferential portion 11 face the one circumferential side R1. Therefore, when the hard sintered body 10 obtained by sintering the base material 1 and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the load can be more easily received at the other side portion 11b of the 1 st outer peripheral portion 11. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1 and the cylindrical portion 20 can be stably suppressed, and the chipping resistance of the cutting tool 50 can be further improved.

Fig. 8 shows a substrate 1E (1) for a hard sintered body according to modification 4 of the present embodiment. Fig. 9 shows a substrate 1F (1) for a hard sintered body according to modification 5 of the present embodiment. Fig. 10 shows a substrate 1G (1) for a hard sintered body according to modification 6 of the present embodiment.

In the 4 th to 6 th modifications, the pillar portion 2 has the base material concave portion 14. In the cross-sectional views perpendicular to the central axis C shown in fig. 8 to 10, the base material concave portion 14 is located at a connecting portion of the 1 st outer peripheral portion 11 and the 2 nd outer peripheral portion 12 connected to each other, and extends in the axial direction. The base material concave portion 14 is located at a connecting portion between one side portion 11a of the 1 st outer peripheral portion 11 and the other side portion 12b of the 2 nd outer peripheral portion 12, and is recessed radially inward. Although not particularly shown, the base concave portion 14 extends in the axial direction along the central axis C.

The base material concave portion 14 is provided in plurality at intervals in the circumferential direction. The number of the base material concave portions 14 is the same as that of the base material convex portions 13, specifically, eight. In each of the cross-sectional views of fig. 8 to 10, the plurality of base material concave portions 14 are arranged so as to be rotationally symmetrical about the central axis C. That is, the plurality of base material concave portions 14 are arranged at equal intervals in the circumferential direction. The substrate groove portion 14 is located on the bisector B (see fig. 3).

Although not particularly shown, each of the tubular portions 20 integrally sintered with the base materials 1E, 1F, and 1G has a tubular portion ridge (see the tubular portion ridge 34 shown in fig. 21). In a cross-sectional view perpendicular to the center axis C, the barrel portion convex portion is located at a connecting portion of the 1 st inner peripheral portion 31 and the 2 nd inner peripheral portion 32 connected to each other, and extends in the axial direction. The cylindrical raised strip is located at a connecting portion between one side portion 31a of the 1 st inner circumferential portion 31 and the other side portion 32b of the 2 nd inner circumferential portion 32, and projects radially inward. The cylindrical projecting strip extends in the axial direction along the central axis C.

The plurality of cylindrical protruding strip portions are provided at intervals in the circumferential direction. The plurality of cylindrical protruding strip portions are arranged to be rotationally symmetrical about the central axis C. That is, the plurality of cylindrical portion ridges are arranged at equal intervals in the circumferential direction. The convex strip part of the cylinder part is positioned on the bisector B.

The cylindrical convex strip is in contact with the base concave strip 14. The base material concave portion 14 and the cylindrical portion convex portion are joined to each other.

According to the substrates 1E, 1F, and 1G of fig. 8 to 10, the substrate concave portion 14 is provided, so that the 1 st outer peripheral portion 11 can be easily oriented in the circumferential direction. Therefore, when the hard sintered body 10 obtained by sintering the base material 1 and the cylindrical portion 20 is used for cutting at the edge portion 51 of the cutting tool 50, the load can be more easily received in the 1 st outer peripheral portion 11. In addition, the substrate 1 has a greater degree of freedom in the arrangement of the substrate convex portion 13 or the 1 st outer peripheral portion 11, and can be easily applied to various hard sintered bodies 10 used in various cutting tools 50.

Fig. 11 shows a substrate 1H (1) for a hard sintered body according to modification 7 of the present embodiment. In this modification, in a cross-sectional view perpendicular to the central axis C shown in fig. 11, the pillar portion 2 has a pentagonal shape, specifically, a regular pentagonal shape. That is, the number of apexes (base material ridges 13) of the pillar portion 2 is less than eight. In this case, each 1 st outer peripheral portion 11 can be more easily oriented in the circumferential direction than in the case where the pillar portion 2 is, for example, octagonal in a cross-sectional view perpendicular to the center axis C.

Fig. 12 shows a substrate 1I (1) for a hard sintered body according to a 8 th modification of the present embodiment. Fig. 13 shows a substrate 1J (1) for a hard sintered body according to a 9 th modification of the present embodiment.

In the 8 th and 9 th modifications, the pillar portion 2 has the base material concave portions 14, and the number of the base material concave portions 14 is less than eight.

In this case, the degree of freedom in arranging the base convex portion 13 or the 1 st outer peripheral portion 11 is increased, and it is possible to cope with various hard sintered bodies 10 used in various cutting tools 50.

Fig. 14 shows a hard sintered body 10 according to a 10 th modification of the present embodiment and a base material 1K (1) for the hard sintered body. In this 10 th modification, the pillar portion 2 has a 3 rd outer peripheral portion 15 and a 4 th outer peripheral portion 16. The peripheral wall portion 21 (the cylindrical portion 20) has a 3 rd inner peripheral portion 35 and a 4 th inner peripheral portion 36.

The 3 rd outer peripheral portion 15 is disposed on the outer peripheral portion of the pillar portion 2 and constitutes a part of the outer peripheral portion of the pillar portion 2. The 3 rd outer peripheral portion 15 constitutes a part of the outer peripheral surface of the column portion 2 in the circumferential direction. The 3 rd outer peripheral portion 15 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 14, the 3 rd peripheral portion 15 extends in the circumferential direction or the radial direction. In the present embodiment, each of the 3 rd outer peripheral portions 15 extends in the circumferential direction. Specifically, each of the 3 rd outer peripheral portions 15 extends from an end of the one side portion 11a of the 1 st outer peripheral portion 11 on the circumferential direction side R1 toward the circumferential direction side R1. The 3 rd outer peripheral portion 15 is located between the end of the one side R1 in the circumferential direction of the one side portion 11a of the 1 st outer peripheral portion 11 and the bisector B in the circumferential direction. The 3 rd outer peripheral portion 15 extends from the one side portion 11a of the 1 st outer peripheral portion 11 toward the circumferential direction side R1 to the bisector B. In the cross-sectional view shown in fig. 14, the 3 rd outer peripheral portion 15 is linear in the present embodiment. The 3 rd outer peripheral portion 15 is located on a straight line connecting an end of one circumferential side R1 of one side portion 11a of the 1 st outer peripheral portion 11 adjacent in the circumferential direction and an end of the other circumferential side R2 of the other side portion 12b of the 2 nd outer peripheral portion 12.

In the cross-sectional view of fig. 14, one side portion (1 st end portion) 15a of the 3 rd outer peripheral portion 15 is located more radially inward than the other side portion (2 nd end portion) 15 b. One side portion 15a of the 3 rd peripheral portion 15 includes a portion located on the bisector B. The other side portion 15b of the 3 rd peripheral portion 15 is connected to the one side portion 11a of the 1 st peripheral portion 11. The 3 rd outer peripheral portion 15 is located radially inward as it goes toward the circumferential direction side R1. That is, the 3 rd outer peripheral portion 15 extends radially inward toward the circumferential direction side R1.

One side portion 15a of the 3 rd outer peripheral portion 15 includes an end portion of the circumferential direction one side R1 in the 3 rd outer peripheral portion 15. The other side portion 15b of the 3 rd outer peripheral portion 15 includes an end portion of the other circumferential direction side R2 in the 3 rd outer peripheral portion 15. One side portion 15a of 3 rd outer peripheral portion 15 includes a radially inner end portion, i.e., a radially inner end portion, in 3 rd outer peripheral portion 15. The other side portion 15b of the 3 rd peripheral portion 15 includes a radially outer end portion, i.e., a radially outer end portion, in the 3 rd peripheral portion 15.

The amount of radial displacement per unit length in the circumferential direction (i.e., the inclination with respect to the circumferential direction) of the 1 st outer peripheral portion 11 is larger than the amount of radial displacement per unit length in the circumferential direction of the 3 rd outer peripheral portion 15.

The 4 th outer peripheral portion 16 is disposed on the outer peripheral portion of the pillar portion 2 and constitutes a part of the outer peripheral portion of the pillar portion 2. The 4 th outer peripheral portion 16 constitutes a part of the outer peripheral surface of the column portion 2 in the circumferential direction. The 4 th outer peripheral portion 16 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 14, the 4 th peripheral portion 16 extends in the circumferential direction or the radial direction. In the present embodiment, each 4 th outer peripheral portion 16 extends in the circumferential direction. Specifically, each 4 th outer peripheral portion 16 extends from an end of the other circumferential side R2 of the other side portion 12b of the 2 nd outer peripheral portion 12 toward the other circumferential side R2. The 4 th outer peripheral portion 16 is located between the end of the other side R2 in the circumferential direction of the other side portion 12B of the 2 nd outer peripheral portion 12 and the bisector B in the circumferential direction. The 4 th outer peripheral portion 16 extends from the other side portion 12B of the 2 nd outer peripheral portion 12 to the bisector B toward the other circumferential side R2. In the cross-sectional view shown in fig. 14, the 4 th outer peripheral portion 16 is linear in the present embodiment. The 4 th outer peripheral portion 16 is located on a straight line connecting an end of one circumferential side R1 of one side portion 11a of the 1 st outer peripheral portion 11 adjacent in the circumferential direction and an end of the other circumferential side R2 of the other side portion 12b of the 2 nd outer peripheral portion 12. That is, in the present embodiment, on a straight line connecting one side portion 11a of the 1 st outer peripheral portion 11 and the other side portion 12B of the 2 nd outer peripheral portion 12 adjacent in the circumferential direction, the 3 rd outer peripheral portion 15 and the 4 th outer peripheral portion 16 are disposed adjacent on both sides in the circumferential direction around the bisector B.

In the cross-sectional view of fig. 14, one side portion (1 st end portion) 16a of the 4 th outer peripheral portion 16 is located radially outward of the other side portion (2 nd end portion) 16 b. One side portion 16a of the 4 th peripheral portion 16 is connected to the other side portion 12b of the 2 nd peripheral portion 12. The other side portion 16B of the 4 th peripheral portion 16 includes a portion located on the bisector B. The 4 th outer peripheral portion 16 is located radially outward as it goes toward the circumferential direction side R1. That is, the 4 th outer peripheral portion 16 extends radially outward as it goes to the circumferential direction side R1.

One side portion 16a of the 4 th outer peripheral portion 16 includes an end portion of the circumferential direction one side R1 in the 4 th outer peripheral portion 16. The other side portion 16b of the 4 th outer peripheral portion 16 includes an end portion of the other circumferential side R2 in the 4 th outer peripheral portion 16. One side portion 16a of the 4 th peripheral portion 16 includes a radially outer end portion, i.e., a radially outer end portion, in the 4 th peripheral portion 16. The other side portion 16b of the 4 th outer peripheral portion 16 includes a radially inner end portion, i.e., a radially inner end portion, in the 4 th outer peripheral portion 16.

In the cross-sectional view shown in fig. 14, the 3 rd peripheral portion 15 and the 4 th peripheral portion 16 are connected to each other. The 3 rd outer peripheral portion 15 and the 4 th outer peripheral portion 16 are connected to each other in the circumferential direction.

The 3 rd outer peripheral portion 15 and the 4 th outer peripheral portion 16 adjacent in the circumferential direction are connected to each other on a bisector B. That is, one side portion 15a of the 3 rd outer peripheral portion 15 and the other side portion 16B of the 4 th outer peripheral portion 16 are connected on the bisector B.

The amount of radial displacement per unit length in the circumferential direction of the 2 nd outer peripheral portion 12 is larger than the amount of radial displacement per unit length in the circumferential direction of the 4 th outer peripheral portion 16.

The 3 rd inner circumferential portion 35 is disposed on the inner circumferential portion of the circumferential wall portion 21. That is, the 3 rd inner circumferential portion 35 is disposed on the inner circumferential portion of the tube portion 20, and constitutes a part of the inner circumferential portion of the tube portion 20. The 3 rd inner circumferential portion 35 constitutes a part of the inner circumferential surface of the circumferential wall portion 21 (the tube portion 20) in the circumferential direction. The 3 rd inner circumferential portion 35 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 14, the 3 rd inner peripheral portion 35 extends in the circumferential direction or the radial direction. In the present embodiment, each 3 rd inner circumferential portion 35 extends in the circumferential direction. Specifically, each of the 3 rd inner circumferential portions 35 extends from an end of the one side portion 31a of the 1 st inner circumferential portion 31 on the circumferential direction side R1 toward the circumferential direction side R1. The 3 rd inner peripheral portion 35 is located between an end portion of one side portion 31a of the 1 st inner peripheral portion 31 on the one circumferential direction side R1 and the bisector B in the circumferential direction. The 3 rd inner peripheral portion 35 extends from the one side portion 31a of the 1 st inner peripheral portion 31 to the bisector B toward the one circumferential side R1. In the cross-sectional view shown in fig. 14, the 3 rd inner peripheral portion 35 is linear in the present embodiment. The 3 rd inner circumferential portion 35 is located on a straight line connecting an end of one circumferential side R1 of one side portion 31a of the 1 st inner circumferential portion 31 adjacent in the circumferential direction and an end of the other circumferential side R2 of the other side portion 32b of the 2 nd inner circumferential portion 32.

In the cross-sectional view of fig. 14, one side portion (1 st end portion) 35a of the 3 rd inner circumferential portion 35 is located more radially inward than the other side portion (2 nd end portion) 35 b. One side portion 35a of the 3 rd inner peripheral portion 35 includes a portion located on the bisector B. The other side portion 35b of the 3 rd inner peripheral portion 35 is connected to the one side portion 31a of the 1 st inner peripheral portion 31. The 3 rd inner peripheral portion 35 is located radially inward as it goes to the circumferential direction side R1. That is, the 3 rd inner peripheral portion 35 extends radially inward toward the circumferential direction one side R1.

One side portion 35a of the 3 rd inner circumferential portion 35 includes an end portion of the circumferential direction side R1 in the 3 rd inner circumferential portion 35. The other side portion 35b of the 3 rd inner circumferential portion 35 includes an end portion of the other circumferential direction side R2 in the 3 rd inner circumferential portion 35. One side portion 35a of the 3 rd inner circumferential portion 35 includes a radially inner end portion, i.e., a radially inner end portion, in the 3 rd inner circumferential portion 35. The other side portion 35b of the 3 rd inner circumferential portion 35 includes a radially outer end portion, i.e., a radially outer end portion, in the 3 rd inner circumferential portion 35.

The 1 st inner circumferential portion 31 has a larger amount of radial displacement per unit length in the circumferential direction (i.e., an inclination with respect to the circumferential direction) than the 3 rd inner circumferential portion 35 in the circumferential direction.

Each 3 rd inner circumferential portion 35 is in contact with each 3 rd outer circumferential portion 15. The 3 rd outer peripheral portion 15 and the 3 rd inner peripheral portion 35 are joined to each other. One side portion 15a of the 3 rd outer peripheral portion 15 and one side portion 35a of the 3 rd inner peripheral portion 35 are opposed in the radial direction and joined to each other. The other side portion 15b of the 3 rd outer peripheral portion 15 and the other side portion 35b of the 3 rd inner peripheral portion 35 are opposed in the radial direction and joined to each other.

The 4 th inner circumferential portion 36 is disposed on the inner circumferential portion of the circumferential wall portion 21. That is, the 4 th inner circumferential portion 36 is disposed on the inner circumferential portion of the tube portion 20, and constitutes a part of the inner circumferential portion of the tube portion 20. The 4 th inner circumferential portion 36 constitutes a part of the inner circumferential surface of the circumferential wall portion 21 in the circumferential direction. The 4 th inner circumferential portion 36 is provided in plurality at intervals from each other in the circumferential direction.

In the cross-sectional view shown in fig. 14, the 4 th inner peripheral portion 36 extends in the circumferential direction or the radial direction. In the present embodiment, each 4 th inner circumferential portion 36 extends in the circumferential direction. Specifically, each 4 th inner circumferential portion 36 extends from an end of the other circumferential side R2 of the other side portion 32b of the 2 nd inner circumferential portion 32 toward the other circumferential side R2. The 4 th inner peripheral portion 36 is located between the end of the other side R2 in the circumferential direction of the other side portion 32B of the 2 nd inner peripheral portion 32 and the bisector B in the circumferential direction. The 4 th inner peripheral portion 36 extends from the other side portion 32B of the 2 nd inner peripheral portion 32 to the bisector B toward the other circumferential side R2. In the cross-sectional view shown in fig. 14, the 4 th inner peripheral portion 36 is linear in the present embodiment. The 4 th inner peripheral portion 36 is located on a straight line connecting an end of one circumferential direction side R1 of one side portion 31a of the 1 st inner peripheral portion 31 adjacent in the circumferential direction and an end of the other circumferential direction side R2 of the other side portion 32b of the 2 nd inner peripheral portion 32. That is, in the present embodiment, the 3 rd inner peripheral portion 35 and the 4 th inner peripheral portion 36 are disposed adjacent to each other on both sides in the circumferential direction around the bisector B on a straight line connecting the one side portion 31a of the 1 st inner peripheral portion 31 and the other side portion 32B of the 2 nd inner peripheral portion 32 adjacent to each other in the circumferential direction.

In the cross-sectional view of fig. 14, one side portion (1 st end portion) 36a of the 4 th inner circumferential portion 36 is located more radially outward than the other side portion (2 nd end portion) 36 b. One side portion 36a of the 4 th inner peripheral portion 36 is connected to the other side portion 32b of the 2 nd inner peripheral portion 32. The other side portion 36B of the 4 th inner peripheral portion 36 includes a portion on the bisector B. The 4 th inner peripheral portion 36 is located radially outward as it goes to the circumferential direction side R1. That is, the 4 th inner circumferential portion 36 extends radially outward as it goes to the circumferential direction side R1.

One side portion 36a of the 4 th inner peripheral portion 36 includes an end portion of the circumferential direction one side R1 in the 4 th inner peripheral portion 36. The other side portion 36b of the 4 th inner peripheral portion 36 includes an end portion of the other circumferential direction side R2 in the 4 th inner peripheral portion 36. One side portion 36a of the 4 th inner circumferential portion 36 includes a radially outer end portion, i.e., a radially outer end portion, in the 4 th inner circumferential portion 36. The other side portion 36b of the 4 th inner circumferential portion 36 includes a radially inner end portion, i.e., a radially inner end portion, in the 4 th inner circumferential portion 36.

In the cross-sectional view shown in fig. 14, the 3 rd and 4 th inner peripheral portions 35 and 36 are connected to each other. The 3 rd inner circumferential portion 35 and the 4 th inner circumferential portion 36 are connected to each other in the circumferential direction.

The 3 rd inner peripheral portion 35 and the 4 th inner peripheral portion 36 adjacent in the circumferential direction are connected to each other on a bisector B. That is, one side portion 35a of the 3 rd inner peripheral portion 35 is connected to the other side portion 36B of the 4 th inner peripheral portion 36 on the bisector B.

The 2 nd inner peripheral portion 32 is larger in radial displacement amount per unit length in the circumferential direction than the 4 th inner peripheral portion 36.

Each 4 th inner circumferential portion 36 is in contact with each 4 th outer circumferential portion 16. The 4 th outer peripheral portion 16 and the 4 th inner peripheral portion 36 are joined to each other. One side portion 16a of the 4 th outer peripheral portion 16 and one side portion 36a of the 4 th inner peripheral portion 36 are opposed in the radial direction and joined to each other. The other side portion 16b of the 4 th outer peripheral portion 16 is radially opposed to the other side portion 36b of the 4 th inner peripheral portion 36, and joined to each other.

According to this 10 th modification, since the base material 1K has the 3 rd outer peripheral portion 15 and the 4 th outer peripheral portion 16, the thickness of the column portion 2 can be ensured and the rigidity of the column portion 2 can be ensured as compared with, for example, the base material 1J shown in fig. 13. Further, the 1 st outer circumferential portion 11 can be easily oriented in the circumferential direction. Further, when the hard sintered body 10 obtained by sintering the base material 1K and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the load can be easily received by the 1 st outer peripheral portion 11 and the 3 rd outer peripheral portion 15. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1K and the cylindrical portion 20 can be stably suppressed, and the chipping resistance of the cutting tool 50 can be further improved.

Fig. 15 (a) and 15 (b) show a hard sintered body 10 and a base material 1L (1) for a hard sintered body thereof according to modification 11 of the present embodiment. In this 11 th modification, in a cross-sectional view perpendicular to the center axis C shown in fig. 15 (a), the pillar portion 2 of the base material 1L has a hexadecagon shape, specifically, a regular hexadecagon shape. That is, the number of apexes (base material ridges 13) of the pillar portion 2 exceeds eight.

In this case, the 1 st outer peripheral portion 11 and the raised base material portion 13 can be easily disposed directly below the cutting edge 56, as compared with a case where the pillar portion 2 has, for example, an octagonal shape in a cross-sectional view perpendicular to the central axis C. That is, the 1 st outer peripheral portion 11 and the raised base material portion 13 more easily intersect the cutting edge 56 when viewed in the radial direction. This makes it possible to more easily receive a load at the 1 st outer peripheral portion 11 and the raised base material portion 13 during the cutting process. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1L and the cylindrical portion 20 can be stably suppressed, and the chipping resistance of the cutting tool 50 can be further improved.

Fig. 16 shows a substrate 1M (1) for a hard sintered body according to a 12 th modification of the present embodiment. In the 12 th modification, the base material convex stripe portion 13 extends in the circumferential direction as going toward the axial direction. That is, the base convex portion 13 is twisted and extended spirally around the central axis C. Specifically, the base material convex portion 13 extends toward the one circumferential direction side R1 as it goes toward the one axial direction side.

Although not particularly shown, the cylindrical portion 20 integrally sintered with the base material 1M has a cylindrical recessed portion 33 in the peripheral wall portion 21. The cylindrical concave portion 33 extends in the circumferential direction as it goes toward the axial direction. That is, the cylindrical concave portion 33 is twisted and extended spirally around the central axis C. Specifically, the cylindrical concave portion 33 extends toward the one circumferential side R1 as it goes toward the one axial side.

According to this 12 th modification, even when the cutting tool 50 is a reamer or the like, for example, and the cutting edge 56 is a so-called straight edge extending along the central axis C, the other side portion 11b (the raised base portion 13) of the 1 st outer peripheral portion 11 and the cutting edge 56 can be made to intersect stably when viewed in the radial direction. Therefore, when the cutting tool 50 is used for cutting, the circumferential load applied to the cutting edge 56 can be more easily received by the 1 st outer peripheral portion 11 and the raised base material portion 13 of the base material 1M. The occurrence of cracks or chipping in the vicinity of the interface between the base material 1M and the cylindrical portion 20 can be suppressed, the chipping resistance of the cutting tool 50 can be improved, and the tool life can be extended.

In addition, when this 12 th modification is used for the cutting tool 50 such as an end mill having the cutting edge 56 that is twisted and extended spirally about the central axis C, the other side portion 11b (the base material ridge portion 13) of the 1 st outer peripheral portion 11 of the base material 1M may be configured to be disposed directly below the cutting edge 56, that is, at a position substantially overlapping the cutting edge 56 when viewed in the radial direction, and to be twisted and extended spirally about the central axis C at a twist angle equal to that of the cutting edge 56.

The direction in which the raised base material strip 13 is twisted may be opposite to the direction in which the cutting edge 56 is twisted. That is, when the cutting edge 56 extends toward the one circumferential side R1 as it goes toward the one axial side, the raised base material strip 13 may be configured to extend toward the other circumferential side R2 as it goes toward the one axial side. In this case, the other side portion 11b (the raised base material portion 13) of the 1 st outer peripheral portion 11 intersects with the cutting edge 56 more stably when viewed in the radial direction.

Fig. 17 (a) and 17 (b) show a hard sintered body 10 and a base material 1N (1) for a hard sintered body thereof according to modification 13 of the present embodiment. In this 13 th modification, the base material 1N has the small diameter portion (pillar portion) 2 and does not have the large diameter portion 3 and the base material end surface 4. An end surface 2b of the column part 2 facing the other axial side is exposed on the other axial side. An end surface 2b of the column part 2 facing the other axial side is a flat surface perpendicular to the central axis C. An end surface 2b of the column part 2 facing the other axial side has a polygonal shape. The cylindrical end surface 23 of the cylindrical portion 20 is disposed on the same plane as the end surface 2b of the post portion 2 facing the other axial side. The cylindrical end surface 23 is exposed on the other axial side.

Fig. 18 (a) and 18 (b) show a hard sintered body 10 and a base material 1P (1) for a hard sintered body thereof according to modification 14 of the present embodiment. In the 14 th modification, the tube portion 20 has the peripheral wall portion 21 and the tube end surface 23, and does not have the top wall portion 22. An end surface 2a of the column part 2 facing one axial side is exposed at one axial side. An end surface 21a of the peripheral wall portion 21 facing the one axial side is annular with the center axis C as the center. An end surface 21a of the peripheral wall portion 21 facing one axial side is a flat surface perpendicular to the central axis C. An end surface 21a of the peripheral wall portion 21 facing the axial direction side is disposed flush with an end surface 2a of the pillar portion 2 facing the axial direction side. An end surface 21a of the peripheral wall portion 21 facing one axial side is exposed at one axial side.

Fig. 19 (a) and 19 (b) show a hard sintered body 10 and a base material 1Q (1) for a hard sintered body according to a 15 th modification of the present embodiment. In the 15 th modification, the cylindrical portion 20 covers the column portion 2 (base material 1Q) from the radially outer side and from both axial sides. The cylindrical portion 20 has a peripheral wall portion 21, a top wall portion 22, and a bottom wall portion 24. The bottom wall portion 24 is connected to the other axial end of the peripheral wall portion 21. The bottom wall portion 24 has a circular plate shape centered on the central axis C. The pair of plate surfaces of the bottom wall portion 24 face in the axial direction. The plate surface of the bottom wall portion 24 facing one axial side is fixed to the end surface 2b of the pillar portion 2 facing the other axial side. The plate surface of the bottom wall portion 24 facing one axial side is joined to the end surface 2b of the pillar portion 2 facing the other axial side.

< embodiment 2 >

Next, the hard sintered body 30 and the cutting tool 50 according to embodiment 2 of the present invention will be described with reference to fig. 20. In embodiment 2, the same components as those in embodiment 1 are denoted by the same reference numerals, and descriptions thereof are omitted.

The hard sintered body 30 of the present embodiment includes a base material 1R (1) and a cylindrical portion 20 integrally sintered with the base material 1R.

The base material 1R has a pillar portion 2. The pillar portion 2 has a 1 st peripheral portion 11 and a 2 nd peripheral portion 12. The cylindrical portion 20 has a peripheral wall portion 21. The peripheral wall portion 21 has a 1 st inner peripheral portion 31 and a 2 nd inner peripheral portion 32.

The 1 st outer circumferential portion 11 and the 1 st inner circumferential portion 31 are joined to each other. The 2 nd outer peripheral portion 12 and the 2 nd inner peripheral portion 32 are engaged with each other.

The cutting tool 50 of the present embodiment includes: a blade part 51 provided with a chip groove 55 and a cutting edge 56 extending in the axial direction on the outer peripheral part of the hard sintered body 30; and a shank 52 (see fig. 4) connected to the blade 51 in the axial direction.

According to the present embodiment, when the hard sintered body 30 is used for cutting by the blade portion 51 of the cutting tool 50, the 1 st outer peripheral portion 11 of the base material 1R is oriented in the tool rotation direction T, so that a load applied in the circumferential direction of the cutting tool 50 can be received in the 1 st outer peripheral portion 11. This can suppress a load applied in a direction perpendicular to the central axis C of the tool, among loads applied to the cutting tool 50 during cutting, from acting along the interface between the base material 1R and the cylindrical portion 20, that is, can reduce a shear force along the interface, and can suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material 1R and the cylindrical portion 20. Accordingly, the chipping resistance of the cutting tool 50 manufactured using the hard sintered body 30 can be improved, and the tool life can be extended.

Fig. 21 shows a hard sintered body 30 according to modification 1 of the present embodiment and a base material 1S (1) for the hard sintered body. In the first modification 1, the column portion 2 of the base material 1S includes a plurality of 1 st outer peripheral portions 11 arranged at intervals in the circumferential direction, a plurality of 2 nd outer peripheral portions 12 arranged at intervals in the circumferential direction, and a plurality of base material concave portions 14 arranged at intervals in the circumferential direction. The peripheral wall portion 21 of the tube portion 20 includes a plurality of 1 st inner peripheral portions 31 arranged at intervals in the circumferential direction, a plurality of 2 nd inner peripheral portions 32 arranged at intervals in the circumferential direction, and a plurality of tube portion ridges 34 arranged at intervals in the circumferential direction.

The 1 st outer peripheral portions 11 and the 1 st inner peripheral portions 31 are joined to each other. Each 2 nd outer peripheral portion 12 and each 2 nd inner peripheral portion 32 are joined to each other. The respective base material concave portions 14 and the respective barrel portion convex portions 34 are joined to each other.

According to the modification 1, when the hard sintered body 30 obtained by sintering the base material 1S and the cylindrical portion 20 is used for cutting by the blade portion 51 of the cutting tool 50, the function based on the 1 st outer peripheral portion 11 can be obtained at a plurality of positions in the circumferential direction of the cutting tool 50. Accordingly, the occurrence of cracks or chipping in the vicinity of the interface between the base material 1S and the cylindrical portion 20 can be stably suppressed, and the fracture resistance of the cutting tool 50 can be further improved.

Further, by providing the base concave portion 14, the 1 st outer peripheral portion 11 can be easily oriented in the circumferential direction. Therefore, when the hard sintered body 30 is used for cutting by the blade portion 51 of the cutting tool 50, the load can be more easily received in the 1 st outer peripheral portion 11.

Fig. 22 shows a hard sintered body 30 according to modification 2 of the present embodiment and a base material 1T (1) for the hard sintered body. In this modification 2, the column portion 2 of the base material 1T includes a plurality of groove portions 17 and a plurality of 1 st outer peripheral portions 11 arranged at intervals in the circumferential direction. The groove 17 is recessed radially inward from the outer peripheral surface of the column part 2 and extends in the axial direction. The 1 st outer peripheral portion 11 is disposed on a wall surface of the groove portion 17 facing the circumferential direction side R1. The 1 st outer peripheral portion 11 is disposed on an outer peripheral portion (i.e., a radially outer end portion) of the post portion 2, and constitutes a part of the outer peripheral portion of the post portion 2.

In a cross-sectional view perpendicular to the center axis C shown in fig. 22, one side portion (1 st end portion) 11a of the 1 st outer peripheral portion 11 is located radially inward of the other side portion (2 nd end portion) 11 b. The other side portion 11b of the 1 st outer peripheral portion 11 includes a portion located on the outer peripheral surface of the pillar portion 2. The 1 st outer peripheral portion 11 is located radially inward toward the other circumferential side R2. That is, the 1 st outer peripheral portion 11 extends radially inward toward the other circumferential side R2.

One side portion 11a of the 1 st outer peripheral portion 11 includes an end portion of the other circumferential direction side R2 in the 1 st outer peripheral portion 11. The other side portion 11b of the 1 st outer peripheral portion 11 includes an end portion of the 1 st outer peripheral portion 11 on one side in the circumferential direction R1. One side portion 11a of 1 st outer peripheral portion 11 includes a radially inner end portion, i.e., a radially inner end portion, in 1 st outer peripheral portion 11. The other side portion 11b of the 1 st outer peripheral portion 11 includes a radially outer end portion, i.e., a radially outer end portion, in the 1 st outer peripheral portion 11.

The peripheral wall portion 21 of the cylindrical portion 20 has a plurality of insertion portions 37 and a plurality of 1 st inner peripheral portions 31 arranged at intervals in the circumferential direction. The insertion portion 37 protrudes radially inward from the inner peripheral surface of the peripheral wall portion 21 and extends in the axial direction. Each insertion portion 37 is disposed in each groove portion 17. Each insertion portion 37 is engaged with each groove portion 17. The 1 st inner circumferential portion 31 is disposed on a wall surface of the insertion portion 37 facing the other circumferential side R2. The 1 st inner circumferential portion 31 is arranged at an inner circumferential portion (i.e., a radially inner end portion) of the cylinder portion 20, and constitutes a part of the inner circumferential portion of the cylinder portion 20.

In a cross-sectional view perpendicular to the center axis C shown in fig. 22, one side portion (1 st end portion) 31a of the 1 st inner circumferential portion 31 is located radially inward of the other side portion (2 nd end portion) 31 b. The other side portion 31b of the 1 st inner peripheral portion 31 includes a portion located on the inner peripheral surface of the peripheral wall portion 21. The 1 st inner circumferential portion 31 is located radially inward toward the other circumferential side R2. That is, the 1 st inner circumferential portion 31 extends radially inward toward the other circumferential side R2.

One side portion 31a of the 1 st inner circumferential portion 31 includes an end of the other circumferential direction side R2 in the 1 st inner circumferential portion 31. The other side portion 31b of the 1 st inner circumferential portion 31 includes an end portion of the 1 st inner circumferential portion 31 on the one side R1 in the circumferential direction. One side portion 31a of the 1 st inner circumferential portion 31 includes a radially inner end portion, i.e., a radially inner end portion, in the 1 st inner circumferential portion 31. The other side portion 31b of the 1 st inner circumferential portion 31 includes a radially outer end portion, i.e., a radially outer end portion, in the 1 st inner circumferential portion 31.

The 1 st outer circumferential portion 11 and the 1 st inner circumferential portion 31 are joined to each other.

In the cross-sectional view of fig. 22, the 1 st outer peripheral portion 11 is inclined at an angle θ' of 170 ° or less with respect to a 2 nd straight line L2, the 2 nd straight line L2 being orthogonal to a 1 st straight line L1 passing through the radially outer end portion of the 1 st outer peripheral portion 11 and the central axis C and extending in the radial direction, and the 2 nd straight line L2 passing on the radially outer end portion of the 1 st outer peripheral portion 11. The angle θ' is an angle of inclination of the 1 st outer peripheral portion 11 from the 2 nd straight line L2 to the rotational direction of the other circumferential side R2. In this cross-sectional view, the respective angles θ' of the plurality of 1 st peripheral portions 11 are equal to each other.

In the 2 nd modification, the 1 st outer peripheral portion 11 faces radially inward, specifically, the 1 st outer peripheral portion 11 extends from the radially outer end of the 1 st outer peripheral portion 11 toward the other circumferential side R2, and the angle θ' in this case is an obtuse angle out of an acute angle and an obtuse angle formed by the 2 nd straight line L2 intersecting the 1 st outer peripheral portion 11 in the cross-sectional view of fig. 22.

When the angle θ' at which the 1 st outer peripheral portion 11 is inclined with respect to the 2 nd straight line L2 is 170 ° or less in the cross-sectional view perpendicular to the center axis C, the thickness of the substrate 1T in the vicinity of the 1 st outer peripheral portion 11 can be ensured, and the rigidity of the substrate 1T can be ensured. For example, a defect that the substrate 1T becomes locally thin and becomes a starting point of a crack can be suppressed. Therefore, the function of the 1 st outer circumferential portion 11 is stabilized.

The present invention is not limited to the above-described embodiments, and for example, as described below, structural changes and the like may be made without departing from the scope of the present invention.

In the above embodiment, the cutting tool 50 is exemplified as an end mill, but is not limited thereto. The cutting tool 50 may be a reamer other than an end mill, a drill, a rotary cutting tool other than the end mill, or the like. For example, when the cutting tool 50 is a drill, the edge portion 51 includes a tip edge, a thinning chisel edge, a land, a shovel back surface, and the like, in addition to the chip groove 55 and the cutting edge 56.

In the above-described embodiment and modification, the angle θ is smaller than 90 ° when the 1 st outer peripheral portion 11 is directed radially outward as shown in fig. 3, and the angle θ' exceeds 90 ° when the 1 st outer peripheral portion 11 is directed radially inward as shown in fig. 22. That is, in a cross-sectional view perpendicular to the center axis C, the 1 st outer peripheral portion 11 may be inclined at an angle of 90 ° with respect to a 2 nd straight line L2, the 2 nd straight line L2 being orthogonal to a 1 st straight line L1 passing through the radially outer end portion of the 1 st outer peripheral portion 11 and the center axis C and extending in the radial direction, and the second straight line L2 passing through the radially outer end portion of the 1 st outer peripheral portion 11. In addition, the angle may be referred to as an angle at which the 1 st outer peripheral portion 11 intersects the 2 nd straight line L2 instead. In this case, the 1 st peripheral portion 11 extends in the radial direction in a cross-sectional view perpendicular to the center axis C.

In addition, the respective configurations (constituent elements) described in the above-described embodiment, modification, and "additional" may be combined, and addition, omission, replacement, and other changes of the configurations may be made without departing from the scope of the present invention. The present invention is not limited to the above embodiments, but is limited only to the claims.

Examples

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to this example.

Hard sintered bodies were prepared as examples of the present invention and comparative examples, respectively. The base material of the hard sintered body is made of cemented carbide, and the cylindrical portion is made of PCD. In the examples and comparative examples, the Young's modulus of the base material after sintering was 570GPa, and the Young's modulus of the cylindrical portion was 920 GPa. In the embodiment of the present invention, in the base material 1 of the hard sintered body 10, the column portions 2 have a regular polygonal shape in a cross-sectional view perpendicular to the central axis C. The radius, which is the distance from the central axis C of the pillar portion 2 to the raised base material portion 13 (the radially outer end portion of the 1 st outer peripheral portion 11), is set to 5mm, and the radius, which is the distance from the central axis C to the outer peripheral surface of the cylindrical portion 20, is set to 7 mm. The cross-sectional shape of the pillar portion 2, the number of the 1 st outer peripheral portions 11, and the angle θ are set as in table 1 below. The hard alloy shank 52 is joined by brazing using an Ag brazing filler metal to the hard sintered body 10 obtained by sintering the base 1 and the cylinder portion 20 integrally. The hard sintered body 10 is ground to form a cutting edge portion 51 of a three-edge end mill. The diameter (blade diameter) of the blade 51 was set to 12 mm.

In the comparative example, the columnar portion was circular in a cross-sectional view perpendicular to the center axis for the base material of the hard sintered body. That is, the column portion of the base material of the comparative example is cylindrical and does not have the 1 st outer peripheral portion 11. The radius of the column part is set to 5mm, and the radius of the cylinder part is set to 7 mm. The hard alloy shank was joined by brazing using an Ag brazing filler metal to a hard sintered body in which the base material and the cylinder portion were integrally sintered. In the same manner as in the above examples, the hard sintered body was subjected to grinding to form a cutting edge portion of a three-edge end mill. The diameter of the blade (blade diameter) was set to 12 mm.

In both examples and comparative examples, cutting tests were performed under the following cutting conditions.

< cutting Condition >

Material to be cut: CFRP (plate thickness 5mm)

Cutting speed: 300m/min

Feed speed: 955mm/min

Depth of cut: 5mm

Dry cutting (air blowing)

Then, the presence or absence of cracks or chipping at the interface between the base material and the cylindrical portion or the cylindrical portion was observed in units of a predetermined cutting length, and in the case of any cracks or chipping, the total cutting length from the start of cutting to the time of cutting was determined as a lifetime (lifetime cutting length). In addition, an optical microscope or an electron microscope is used for observation. The evaluation results are shown in table 1.

[ Table 1]

As shown in table 1, in examples 1 to 6 of the present invention, it was confirmed that the life cutting lengths were all 16m or more, and compared to the comparative examples, cracks or chipping at the interface between the base material and the cylindrical portion or the cylindrical portion was suppressed, and the tool life was extended. Among them, examples 2 to 5 are excellent in terms of life cutting length of 22m or more, and example 3 is particularly excellent in terms of life cutting length of 30 m.

Industrial applicability

According to the base material for a hard sintered body, the hard sintered body, and the cutting tool of the present invention, it is possible to suppress the occurrence of cracks or chipping in the vicinity of the interface between the base material and the cylindrical portion. Therefore, the method has industrial applicability.

Description of the symbols

1(1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1N, 1P, 1Q, 1R, 1S, 1T) substrate

2 small diameter part (column part) 10, 30 hard sintered body

11 the 1 st peripheral part

11a one side part of the 1 st peripheral part 11b the other side part of the 1 st peripheral part

12 nd 2 nd peripheral part

12a one side part of the 2 nd outer peripheral part 12b the other side part of the 2 nd outer peripheral part

13 raised strip portion of base material and 14 recessed strip portion of base material

20 barrel part

31 1 st inner peripheral part

31a one side part of the 1 st inner peripheral part 31b the other side part of the 1 st inner peripheral part

32 nd 2 nd inner peripheral part

32a one side portion of the 2 nd inner peripheral portion 32b the other side portion of the 2 nd inner peripheral portion

33 cylindrical concave part

50 cutting tool 51 edge

52 shank 55 flute

56 center axis of cutting edge C

L1 line 1, L2 line 2

One side in the circumferential direction of R1 and the other side in the circumferential direction of R2

Angle theta, theta