阅读说明：本技术 可转位刀片式钻头、切削刀片及钻头主体 (Indexable insert drill, cutting insert and drill body ) 是由 臼井正洋 于 2020-03-18 设计创作，主要内容包括：在该可转位刀片式钻头中,在钻头主体(1)的刀片安装座(6)以能够装卸的方式安装形成有切削刃(14)的切削刀片(10)。在刀片安装座(6)形成有朝向钻头主体(1)的前端侧的底面(6a)和向前端侧延伸并朝向钻头旋转方向(T)的壁面(6b)。在切削刀片(10)形成有：落座面(15),朝向钻头主体(1)的后端侧并落座于底面(6a)；抵接面(16),朝向与钻头旋转方向(T)相反的一侧并与壁面(6b)抵接；凸部(17),在抵接面(16)的前端侧向与钻头旋转方向(T)相反的一侧突出；及安装孔,从前端后刀面(12)贯穿到落座面(15)。(In the indexable drill, a cutting insert (10) having a cutting edge (14) is detachably mounted on an insert mounting seat (6) of a drill body (1). A bottom surface (6a) facing the front end side of the drill body (1) and a wall surface (6b) extending toward the front end side and facing the drill rotation direction (T) are formed in the insert mounting seat (6). A cutting insert (10) is provided with: a seating surface (15) that faces the rear end side of the drill body (1) and is seated on the bottom surface (6 a); an abutment surface (16) which faces the opposite side of the drill bit rotation direction (T) and abuts against the wall surface (6 b); a convex portion (17) that protrudes to the side opposite to the drill rotation direction (T) at the distal end side of the contact surface (16); and a mounting hole that penetrates from the front end flank surface (12) to the seating surface (15).)

1. An indexable insert drill, comprising:

a drill body having a tip attachment seat formed at a distal end portion thereof and rotating around an axis; and

a cutting blade detachably mounted on the blade mounting seat,

a body chip groove that is open at a distal end surface of the drill body and extends toward a rear end side of the drill body is formed on an outer periphery of a distal end portion of the drill body,

an insert chip groove opened at a front end flank of the cutting insert and communicating with the body chip groove is formed at the cutting insert,

a cutting edge is formed on a crossing ridge line portion between a wall surface of the insert chip groove facing a drill rotation direction and the tip flank surface,

the blade mount is provided with: a bottom surface facing the front end side of the drill main body; a wall surface extending toward the front end side of the drill body with respect to the bottom surface and facing in the drill rotation direction; and a screw hole opened on the bottom surface,

the cutting insert is formed with: a seating surface that faces a rear end side of the drill body and is seated on the bottom surface; an abutment surface that abuts against the wall surface from the drill rotation direction toward a side opposite to the drill rotation direction; a convex portion that protrudes further to the opposite side of the drill bit rotation direction than the abutment surface on the distal end side of the abutment surface; and a mounting hole penetrating from the front end flank surface to the seating surface,

the cutting insert is mounted to the insert mounting seat by screwing a clamping screw inserted into the mounting hole into the screw hole.

2. The indexable drill of claim 1, wherein,

the convex portion is formed with a side surface facing the opposite side to the drill rotation direction and adjacent to the tip flank surface.

3. The indexable drill according to claim 1 or 2, wherein,

a shaft portion centered on the axis is formed on one surface of a seating surface of the cutting insert and a bottom surface of the insert mounting seat, and a hole portion into which the shaft portion is fitted is formed on the other surface of the seating surface and the bottom surface,

the hole portion opens in the body chip groove or the insert chip groove.

4. The indexable drill according to any one of claims 1 to 3, wherein,

the axial width of the wall surface and the contact surface is wider on the outer peripheral side than on the inner peripheral side of the drill body.

5. The indexable drill according to any one of claims 1 to 4, wherein,

a recess recessed from the bottom surface and the wall surface is formed from the body chip groove to the outer peripheral surface of the drill body at a corner where the bottom surface and the wall surface of the insert attachment seat intersect,

the recess has an opening with a larger cross-sectional area on the outer peripheral surface side of the drill body than an opening on the chip discharge groove side of the drill body.

6. The indexable drill according to any one of claims 1 to 5, wherein,

the intersecting edge line portion between the wall surface and the inner peripheral surface of the main chip groove is chamfered.

7. A cutting insert detachably mounted to the insert mounting seat of the drill body in the indexable insert drill according to any one of claims 1 to 6,

the cutting insert has an insert body having a cutting insert body,

an insert chip groove opened at a front end flank face of the insert body and communicating with the body chip groove is formed at the cutting insert,

a cutting edge is formed on a crossing ridge line portion between a wall surface of the insert chip groove facing a drill rotation direction and the tip flank surface,

the cutting insert is formed with: a seating surface facing a rear end side of the drill body and seated on the bottom surface of the insert mounting seat; an abutting surface that abuts against the wall surface of the insert attachment seat from the drill rotation direction toward a side opposite to the drill rotation direction; a convex portion that protrudes further to the opposite side of the drill bit rotation direction than the abutment surface on the distal end side of the abutment surface; and an attachment hole penetrating from the tip flank surface to the seating surface.

8. A bit body in the indexable drill according to any one of claims 1 to 6, wherein,

a blade mounting seat is formed at the front end of the drill main body,

a body chip groove that is open at a distal end surface of the drill body and extends toward a rear end side of the drill body is formed on an outer periphery of a distal end portion of the drill body,

the blade mount is provided with: a bottom surface facing the front end side; a wall surface extending toward the bit rotation direction with respect to the bottom surface toward the tip end side; and a screw hole opened in the bottom surface and screwed into the clamp screw.

Technical Field

The present invention relates to an indexable drill, a cutting insert and a drill body of the indexable drill. The indexable drill has an insert mounting seat formed at a front end portion of a drill body that rotates about an axis, and a cutting insert is detachably mounted to the insert mounting seat. The cutting insert is detachably mounted to an insert mounting seat of the blade replacement type drill.

The present application claims priority based on patent application No. 2019-50081 filed on japanese application at 18.3.2019 and patent application No. 2020-25571 filed on japanese application at 18.2.2020, and these contents are incorporated herein by reference.

Background

For example, in an insert-indexable drill described in patent document 1, a splitting surface extending perpendicular to an axis and a torque transmission surface adjacent to the splitting surface are formed in an insert mounting seat of a drill main body, and a splitting surface extending perpendicular to the axis and a torque receiving surface extending from the splitting surface toward a tip flank surface and adjacent to the tip flank surface are formed in a cutting insert. The cutting insert is detachably mounted to the insert mounting seat by a fastening screw.

Patent document 1: european patent specification No. 2408581

However, in the insert-indexable drill described in patent document 1, the torque-receiving surface of the cutting insert is adjacent to and intersects the tip flank surface, and the abutment portion of the torque-receiving surface and the torque-transmitting surface of the drill body is exposed to the tip portion of the insert-indexable drill. Therefore, in particular, in the case of wet cutting in which drilling is performed while supplying a coolant, fine cutting powder generated by cutting tends to form sludge together with the coolant and enter a portion where the torque receiving surface and the torque transmitting surface are in contact from the distal end side of the drill body, and the torque receiving surface and the torque transmitting surface are worn by the sludge, which may shorten the life of the drill.

Disclosure of Invention

The invention aims to prevent the shortening of the life of a drill by preventing sludge from entering the contact part between a cutting blade and a blade mounting seat from the front end side of a drill body.

An indexable insert drill according to an aspect of the present invention includes: a drill body having a tip attachment seat formed at a distal end portion thereof and rotating around an axis; and a cutting insert detachably mounted to the insert mounting seat.

A body chip groove that opens at a distal end surface of the drill body and extends toward a rear end side of the drill body is formed in an outer periphery of a distal end portion of the drill body, and an insert chip groove that opens at a distal end flank of the cutting insert and communicates with the body chip groove is formed in the cutting insert.

A cutting edge is formed at an intersecting ridge line portion between a wall surface of the insert chip groove facing a drill rotation direction and the tip flank surface, and the insert attachment seat is formed with: a bottom surface facing the front end side of the drill main body; a wall surface extending toward the front end side of the drill body with respect to the bottom surface and facing in the drill rotation direction; and a screw hole opened in the bottom surface.

The cutting insert is formed with: a seating surface that faces a rear end side of the drill body and is seated on the bottom surface; an abutment surface that abuts against the wall surface from the drill rotation direction toward a side opposite to the drill rotation direction; a convex portion protruding to a side opposite to a drill rotation direction at a distal end side of the abutment surface; and an attachment hole penetrating from the tip flank surface to the seating surface. The cutting insert is mounted to the insert mounting seat by screwing a clamping screw inserted into the mounting hole into the screw hole.

In the indexable drill according to the above aspect, in a state in which the cutting insert is mounted on the insert mounting seat, a tip portion of a portion of the abutment surface abutting the wall surface is covered with a convex portion that protrudes to a side opposite to a drill rotation direction at a tip side of the abutment surface. That is, the convex portion protruding to the opposite side of the drill rotation direction from the abutment surface receives the tip of the abutment interface between the abutment surface and the wall surface. This can prevent foreign matter such as sludge from entering from the tip of the portion where the contact surface and the wall surface contact each other.

A cutting insert according to the present invention is a cutting insert detachably mounted to the insert mounting seat of the drill body in the drill body of the blade-replacement drill, wherein an insert chip groove is formed in the cutting insert, the insert chip groove opens into a tip flank of the insert body and communicates with the body chip groove, a cutting edge is formed at an intersecting ridge line portion between a wall surface of the insert chip groove facing a drill rotation direction and the tip flank, and the cutting insert comprises: a seating surface facing a rear end side of the drill body and seated on the bottom surface of the insert mounting seat; an abutting surface that abuts against the wall surface of the insert attachment seat from the drill rotation direction toward a side opposite to the drill rotation direction; a convex portion that protrudes further to the opposite side of the drill bit rotation direction than the abutment surface on the distal end side of the abutment surface; and an attachment hole penetrating from the tip flank surface to the seating surface.

A drill body according to the present invention is the drill body in the indexable insert drill as described above, wherein an insert attachment seat is formed at a front end portion of the drill body, a body chip groove is formed on an outer periphery of the front end portion of the drill body, the body chip groove opens at a front end surface of the drill body and extends toward a rear end side, and the insert attachment seat is formed with: a bottom surface facing the front end side; a wall surface extending toward the bit rotation direction with respect to the bottom surface toward the tip end side; and a screw hole opened in the bottom surface and screwed into the clamp screw.

In the indexable drill, the cutting insert, and the drill body, a convex portion that protrudes further to the side opposite to the drill rotation direction than the abutment surface is formed on the tip side of the abutment surface (torque receiving surface) that abuts against the wall surface (torque transmission surface) of the insert attachment seat from the drill rotation direction toward the side opposite to the drill rotation direction of the cutting insert, and the abutment surface of the cutting insert is not adjacent to the tip flank surface and is discontinuous. In a state where the cutting insert is mounted on the insert mounting seat, the convex portion is disposed on a front end side of a portion where the abutment surface abuts against the wall surface, and the abutment portion is thereby covered with the convex portion, so that the portion where the abutment surface of the cutting insert abuts against the wall surface of the insert mounting seat is not exposed to a front end portion of the indexable insert drill.

Therefore, even in the case of wet cutting in which drilling is performed while supplying a coolant, it is possible to prevent fine cutting powder generated by cutting from entering a portion where the contact surface of the cutting insert and the wall surface of the insert attachment seat come into contact from the distal end side of the drill body as sludge together with the coolant, and to prevent the contact surface and the wall surface from being worn due to the sludge. Therefore, according to the insert-replaceable drill, the cutting insert, and the drill body configured as described above, it is possible to prevent the drill life from being shortened due to such wear, and to perform stable drilling for a long time.

However, in such an indexable drill, when the cutting edge is worn and the cutting edge becomes dull during the drilling process for such a long time, the distal end flank surface of the cutting insert is reground, and a new cutting edge may be ground at an intersecting ridge line portion between the reground distal end flank surface and a wall surface of the insert chip groove facing the drill rotation direction. In this case, since the side surface adjacent to the tip flank surface is formed on the convex portion in the direction opposite to the drill rotation direction, whether or not the regrinding is possible can be visually confirmed by confirming the width of the side surface in the axial direction.

In the indexable insert drill described in patent document 1, a shaft portion is formed on a parting surface of the cutting insert, a hole portion is formed on a parting surface of the insert mounting seat, and the shaft portion is inserted into the hole portion. However, if the hole portion is a blind hole having a continuous inner peripheral surface and the difference between the inner diameter of the hole portion and the outer diameter of the shaft portion of the cutting insert is small, the air in the hole portion is compressed when the shaft portion is inserted, and a force for ejecting the cutting insert is applied by the pressure.

Therefore, in the indexable drill having the above-described configuration, it is desirable that a shaft portion centered on the axis be formed on one of the seating surface of the cutting insert and the bottom surface of the insert mounting seat, and a hole portion into which the shaft portion is fittable be formed on the other of the seating surface of the cutting insert and the bottom surface of the insert mounting seat, the hole portion opening into the body chip groove or the insert chip groove.

Accordingly, in the case where the hole portion is a blind hole having a bottom surface, even if the difference between the inner diameter of the hole portion and the outer diameter of the shaft portion is reduced, air in the hole portion is discharged from the opening portion of the body chip groove or the insert chip groove, and therefore, a force for ejecting the cutting insert does not act. By reducing the difference between the inner diameter of the hole portion and the outer diameter of the shaft portion in this manner, the runout accuracy of the cutting edge of the cutting insert can be ensured.

Further, by forming the wall surface and the abutment surface such that the width in the axial direction is wider on the outer peripheral side than on the inner peripheral side of the drill body, the abutment area of the abutment surface that abuts against the wall surface can be secured large on the outer peripheral side of the drill body on which the largest cutting load acts during drilling. Therefore, the stress of the insert attachment seat acting on the outermost periphery of the drill body can be reduced.

In the corner portion where the bottom surface and the wall surface of the insert mounting seat intersect, a recessed portion recessed from the body chip pocket to the outer peripheral surface of the drill body with respect to the bottom surface and the wall surface is formed, whereby it is possible to prevent the mounting stability of the cutting insert from being impaired due to interference between the intersecting edge line portion of the seating surface and the abutment surface of the cutting insert and the corner portion where the bottom surface and the wall surface of the insert mounting seat intersect.

In the case of forming such a recess, the cross-sectional area of the recess is set so that the opening on the outer peripheral surface side of the drill body is larger than the opening on the main body chip groove side, whereby the stress concentration on the recess can be relieved on the outer peripheral surface side of the drill body on which the largest cutting load acts during drilling work as described above. On the other hand, since the cross-sectional area of the opening on the chip groove side of the body is small, the rigidity of the projecting wall portion of the drill body forming the wall surface is not impaired.

By chamfering the intersecting edge line portion of the wall surface and the inner peripheral surface of the body chip groove, scratches can be prevented as compared with a case where the intersecting edge line portion holds a sharp edge.

As described above, according to the present invention, even in wet cutting in which drilling is performed while supplying a coolant, it is possible to prevent cutting chips from entering a portion where the contact surface of the cutting insert and the wall surface of the insert attachment seat come into contact from the tip end side of the drill body as sludge together with the coolant, and therefore, it is possible to prevent abrasion from occurring on the contact surface and the wall surface, and to perform stable drilling for a long time.

Drawings

Fig. 1 is a perspective view showing a1 st embodiment of an indexable drill according to the present invention.

Fig. 2 is a perspective view of the embodiment shown in fig. 1, viewed from another direction.

Fig. 3 is a front view of the embodiment shown in fig. 1.

Fig. 4 is a side view of the embodiment shown in fig. 1 as viewed from the direction of arrow a in fig. 3.

Fig. 5 is a side view of the embodiment shown in fig. 1 as viewed from the direction of arrow B in fig. 3.

Fig. 6 is a side view of the embodiment shown in fig. 1 as viewed from the direction of arrow C in fig. 3.

Fig. 7 is an exploded view of the embodiment shown in fig. 1.

Fig. 8 is a front view showing embodiment 1 of the drill body according to the present invention.

Fig. 9 is a side view of the embodiment shown in fig. 8 as viewed from the direction of arrow a.

Fig. 10 is a perspective view showing a cutting insert according to embodiment 1 of the present invention.

Fig. 11 is a perspective view of the embodiment shown in fig. 10 viewed from another direction.

Fig. 12 is a front view of the embodiment shown in fig. 10.

Fig. 13 is a side view of the embodiment shown in fig. 10 as viewed from the direction of arrow a in fig. 12.

Fig. 14 is a side view of the embodiment shown in fig. 10 as viewed from the direction of arrow B in fig. 12.

Fig. 15 is a perspective view showing a2 nd embodiment of an indexable drill according to the present invention.

Fig. 16 is a perspective view of the embodiment shown in fig. 15 viewed from another direction.

Fig. 17 is a front view of the embodiment shown in fig. 15.

Fig. 18 is a side view of the embodiment shown in fig. 15 as viewed from the direction of arrow a in fig. 16.

Fig. 19 is a side view of the embodiment shown in fig. 15, as viewed from the direction of arrow B in fig. 16.

Fig. 20 is a side view of the embodiment shown in fig. 15, as viewed from the direction of arrow C in fig. 16.

Fig. 21 is an exploded view of the embodiment shown in fig. 15.

Fig. 22 is a front view showing embodiment 2 of the drill body according to the present invention.

Fig. 23 is a side view of the embodiment shown in fig. 22 as viewed from the direction of arrow a.

Fig. 24 is a side view of the embodiment shown in fig. 22, as viewed from the direction of arrow B.

Fig. 25 is a perspective view showing a cutting insert according to embodiment 2 of the present invention.

Fig. 26 is a perspective view of the embodiment shown in fig. 25 viewed from another direction.

Fig. 27 is a front view of the embodiment shown in fig. 25.

Fig. 28 is a side view of the embodiment shown in fig. 25 as viewed from the direction of arrow a in fig. 27.

Fig. 29 is a side view of the embodiment shown in fig. 25 as viewed from the direction of arrow B in fig. 27.

Fig. 30 is a side view of the embodiment shown in fig. 25 as viewed from the direction of arrow C in fig. 27.

Fig. 31 is an exploded cross-sectional view of the embodiment shown in fig. 15 cut along the axis of the cutting insert and the bit body.

Detailed Description

Fig. 1 to 6 show a1 st embodiment of an insert-indexable drill according to the present invention, and fig. 7 shows an exploded view of the insert-indexable drill of the 1 st embodiment. Fig. 8 and 9 show a drill body 1 of the embodiment 1 used in the indexable insert drill, and fig. 10 to 14 show a cutting insert detachably mounted to the drill body 1.

The drill body 1 is formed in a multi-stage cylindrical shape centered on an axis O from a metal material such as a steel material. The drill body 1 has a shank portion 2 with a large diameter at a rear end portion (a right-hand portion in fig. 1, 2, 4 to 7, and 9), and a cutting edge portion 3 of an insert body 11 to which a cutting insert 10 is detachably attached at a front end portion (a left-hand portion in fig. 1, 2, 4 to 7, and 9). In the present specification, unless otherwise defined, "front end side" refers to the front end side of the drill body 1, and "rear end side" refers to the rear end side of the drill body 1. The cutting edge portion 3 has a diameter smaller than that of the shank portion 2, and a flange portion 4 is formed between the shank portion 2 and the cutting edge portion 3, and the flange portion 4 has a diameter which is the same as that of the cutting edge portion 3 by being reduced in diameter after being further enlarged in diameter toward the tip end side than the shank portion 2.

In this indexable insert drill, a shank 2 of a drill body 1 is held by a spindle of a machine tool, and is fed toward a tip side in the direction of an axis O while rotating in a drill rotating direction T about the axis O, whereby a workpiece is drilled by a cutting edge of a cutting insert 10. A flat surface 2a extending parallel to the axis O is formed on the outer peripheral surface of the shank 2 at a distance from the front end and the rear end of the shank 2, and a flat surface 4a parallel to the flat surface 2a is also formed on a portion of the flange portion 4 that is enlarged in diameter relative to the shank 2.

A plurality of body flutes 5 are formed at intervals in the circumferential direction from the tip of the cutting edge portion 3 to the front of the rear end of the flange portion 4 in the outer circumferential portion of the drill body 1. In the present embodiment, two body flutes 5 are formed at equal intervals in the circumferential direction, and these body flutes 5 are formed in a spiral shape that gradually twists about the axis O toward the opposite side to the bit rotational direction T as they go toward the rear end side of the bit body 1.

An insert attachment seat 6 is formed at the tip of the cutting edge portion 3. As shown in fig. 5, 7, and 8, the insert attachment seat 6 is formed by cutting out a central portion of the tip of the cutting edge portion 3 in a rectangular shape when viewed from a direction perpendicular to the axis O. As shown in fig. 8, the cut-away region extends in a radial direction with respect to the axis O and passes from one of the body flutes 5 to the other body flute 5. The width of the rectangular region to be cut is from the wall surface of each of the body flutes 5 facing the drill rotation direction T to the wall surface facing the side opposite to the drill rotation direction T. Regarding the cut-off region, the depth in the direction of the axis O is smaller than the width in the radial direction when viewed from the direction perpendicular to the axis O, and is flat.

As shown in fig. 8, the insert attachment seat 6 includes: a bottom surface 6a extending in a direction perpendicular to the axis O and facing the front end side of the bit body 1; and two wall surfaces 6b extending from both side portions of the bottom surface 6a perpendicularly to the bottom surface 6a and in parallel with the axis O, and facing the drill rotation direction T. The wall surfaces 6b face each other and are parallel to each other. In the present embodiment, each of the wall surfaces 6b has a rectangular shape having a longitudinal direction in a radial direction with respect to the axis O.

In the present embodiment, a hole 6c is formed to extend toward the rear end side of the drill body 1, and the hole 6c is opened at the center of the bottom surface 6a and has a circular cross-section with a constant inner diameter around the axis O. The inner diameter of the hole 6c is larger than the diameter of an imaginary circle inscribed in the bottom surface of the body flute 5 facing the outer periphery of the drill body 1 in a cross section perpendicular to the axis O. Therefore, both sides of the hole 6c are opened in a rectangular shape in the bottom surface of each of the main chip grooves 5, and the bottom surface 6a of the insert attachment seat 6 is divided by the hole 6c into two portions that are rotationally symmetric at 180 ° about the axis O. The hole 6c is a blind hole having a bottom surface facing the distal end side of the drill body 1.

A screw hole 6d having a center at a distance equal to the axis O is formed in each of the bottom surfaces 6a divided into two by the hole 6c and spaced from the hole 6 c. In the drill body 1, a cooling hole 1a is formed from the rear end surface of the shank 2 toward the tip end side along the axis O, the cooling hole 1a is branched into two in the vicinity of the insert attachment seat 6, and the tip ends are opened in wall surfaces of the body chip grooves 5 facing the side opposite to the drill rotation direction T.

A convex wall portion 7 is left on the side of the wall surface 6b of the insert attachment seat 6 opposite to the drill rotation direction T, the convex wall portion 7 is surrounded by the wall surface 6b, the outer peripheral surface of the cutting edge portion 3, and the wall surface of the main chip groove 5 facing the side opposite to the drill rotation direction T, and a tip end surface 7a of the convex wall portion 7 is a plane perpendicular to the axis O. In the present embodiment, as shown in fig. 8 and 9, a recess 6e as a relief portion is formed at a corner portion where the bottom surface 6a and the wall surface 6b intersect, and the recess 6e is circular in cross section with a constant inner diameter and is recessed with respect to the bottom surface 6a and the wall surface 6 b. The recess 6e is for avoiding interference between the bottom surface 6a and the wall surface 6b of the insert mounting seat 6 and the cutting insert 10. Further, the insert mounting seat 6 and the two body flutes 5 are each shaped to be 180 ° rotationally symmetric about the axis O.

As shown in fig. 10 to 14, the cutting insert 10 detachably mounted on the insert mounting seat 6 includes an insert body 11 formed of a hard material such as cemented carbide having a hardness higher than that of the drill body 1. The insert body 11 has a shape rotationally symmetrical about the axis O of the drill body 1 by 180 ° in a state attached to the insert attachment seat 6.

The insert body 11 is formed with a tip flank surface 12 facing the tip end side of the drill body 1 and insert chip grooves 13 opening in the tip flank surface 12 and communicating with the two body chip grooves 5, respectively, in a state of being attached to the insert attachment seat 6, and cutting edges 14 are formed at intersecting ridge line portions between the tip flank surface 12 and wall surfaces of the insert chip grooves 13 facing the drill rotation direction T. The tip flank surface 12 is inclined toward the rear end side of the drill body 1 as it goes toward the side opposite to the drill rotation direction T and the outer peripheral side of the drill body 1, thereby giving a relief angle and a drill taper angle to the cutting edge 14.

As shown in fig. 13 and 14, in the state of being attached to the insert attachment seat 6, the rear end surface of the insert main body 11 is a plane perpendicular to the axis O and is a seating surface 15 facing the rear end side of the drill main body 1 and seated on the bottom surface 6a of the insert attachment seat 6. A multi-stage cylindrical shaft portion 15a having a large diameter at a front end portion and a slightly small diameter at a rear end portion is formed to protrude from the center of the seating surface 15 toward the rear end side with respect to the axis O, and the outer diameter of the front end portion of the shaft portion 15a is sized to be fitted into the hole portion 6c of the insert attachment seat 6.

Further, an abutment surface 16 is formed from a wall surface of the two insert chip grooves 13 facing the side opposite to the bit rotation direction T to the outer peripheral surface of the insert body 11, and the abutment surface 16 abuts against the wall surface 6b of the insert attachment seat 6 from the bit rotation direction T facing the side opposite to the bit rotation direction T. These abutment surfaces 16 are formed so as to intersect perpendicularly with the seating surface 15 and to be parallel to the axis O, and these abutment surfaces 16 also extend parallel to each other. The abutment surface 16 of the present embodiment is a rectangle having a longitudinal direction in a radial direction with respect to the axis O.

Two mounting holes 11a penetrating from the tip flank surface 12 to the seating surface 15 are formed in the insert body 11 at intervals from the shaft portion 15 a. These mounting holes 11a are disposed coaxially with the two screw holes 6d of the insert mounting seat 6, respectively, in a state where the abutment surface 16 abuts against the wall surface 6b of the insert mounting seat 6. As shown in fig. 12, the inner diameter of the mounting hole 11a gradually decreases from the opening portion on the side of the distal end flank surface 12 toward the seating surface 15, and is constant on the seating surface 15 side.

As shown in fig. 10 and 11, a convex portion 17 is formed on the insert body 11 of the cutting insert 10, and the convex portion 17 protrudes to the opposite side of the drill rotation direction T from the abutment surface 16 on the tip side of the abutment surface 16. Therefore, in a state where the shaft portion 15a of the insert body 11 is fitted into the hole portion 6c of the insert attachment seat 6, the seating surface 15 is brought into close contact with the bottom surface 6a, and the contact surface 16 is brought into contact with the wall surface 6b, the convex portions 17 are disposed on the distal end side of the contact portion P between the contact surface 16 and the wall surface 6b with almost no gap, and cover the distal end portion of the contact portion P. Thus, the contact portion P between the contact surface 16 and the wall surface 6b is received by the projection 17 with almost no gap, and entry of foreign matter from the tip is prevented.

That is, the rear end surface 17a of the convex portion 17 facing the rear end side of the drill body 1 is a plane that can be brought into sliding contact with the front end surface 7a of the convex wall portion 7 that is a plane perpendicular to the axis O and that is perpendicular to the axis O in a state where the seating surface 15 of the insert body 11 is brought into close contact with the bottom surface 6a of the insert attachment seat 6 as described above, and the rear end surface 17a of the convex portion 17 is brought into contact with the front end surface 7a of the convex wall portion 7, whereby the front end portion of the contact portion P between the contact surface 16 and the wall surface 6b is covered with the convex portion 17.

A side surface 17b of the convex portion 17 facing the side opposite to the drill rotation direction T extends parallel to the abutment surface 16 and is adjacent to the tip flank surface 12, that is, the side surface 17b extends parallel to the axis O and perpendicular to the rear end surface 17a, and intersects the tip flank surface 12 of the insert body 11 at a certain angle on an intersecting ridge line Q. The convex portion 17 of this embodiment does not cover all the distal end surfaces 7a of the convex portion 7 of the bit body 1, but exposes the distal end surfaces 7a on the side opposite to the bit rotation direction T of the side surface 17 b. When the front end of the contact portion P between the contact surface 16 and the wall surface 6b is covered with the rear end surface 17a of the projection 17, an effect of suppressing the entry of sludge can be obtained. However, the projection 17 may cover all the distal end surfaces 7a of the projecting wall portion 7 of the drill body 1.

As described above, the insert body 11 of the cutting insert 10 is detachably mounted to the insert mount 6 by fitting the shaft portion 15a into the hole portion 6c of the insert mount 6 to bring the seating surface 15 into close contact with the bottom surface 6a and bring the abutment surface 16 into abutment with the wall surface 6b, and then screwing the clamp screw 18 inserted into the mounting hole 11a from the front end side of the drill body 1 into the screw hole 6d as shown in fig. 7.

In the indexable drill and the cutting insert 10 configured as described above, a coolant such as a cutting oil is discharged from the cooling hole 1a formed in the drill body 1, and the cutting edge 14 of the insert body 11 of the cutting insert 10 cuts a workpiece to drill the workpiece. At this time, since the convex portion 17 is formed in the insert body 11, the convex portion 17 protrudes to the opposite side of the drill rotation direction T from the abutment surface 16 on the front end side of the abutment surface 16 abutting against the wall surface 6b of the insert attachment seat 6, and the convex portion 17 is disposed on the front end side of the abutment portion P of the abutment surface 16 and the wall surface 6b to cover the front end portion of the abutment portion P, the front end portion of the abutment portion P is received by the convex portion 17, and the abutment portion P is not exposed to the front end portion of the indexable insert drill.

Therefore, as described above, even if the fine cutting powder produced by cutting becomes sludge together with the cutting oil in the wet cutting in which the cutting oil is discharged, the sludge can be prevented from entering the contact portion P between the contact surface 16 of the cutting tip 10 and the wall surface 6b of the tip attachment seat 6 from the distal end side of the bit body 1. Therefore, the contact surface 16 and the wall surface 6b can be prevented from being worn by the sludge, and the life of the indexable drill can be prevented from being shortened by the wear, so that stable drilling can be performed for a long time.

In the present embodiment, the side surface 17b is adjacent to the tip flank 12 on the opposite side to the drill rotation direction T, and the side surface 17b is formed on the convex portion 17 so as to intersect the tip flank 12 at a certain angle at the intersection ridge line Q. Therefore, when the cutting edge 14 is worn and becomes dull, the end flank surface 12 is reground to sharpen a new cutting edge 14 at the intersecting ridge line portion with the wall surface of the insert chip groove 13 facing the drill rotation direction T, and the width of the side surface 17b between the intersecting ridge line Q and the seating surface 15 in the axis O direction is checked to visually check whether regrinding is possible. Therefore, it is possible to avoid the occurrence of wear or the like on the convex wall portion 7 of the drill body 1 due to the excessively thin convex portion 17.

In the present embodiment, a shaft portion 15a centered on the axis O is formed on the seating surface 15 of the insert body 11 of the cutting insert 10, and a hole portion 6c capable of being fitted into the shaft portion 15a is formed on the bottom surface 6a of the insert mounting seat 6 centered on the axis O. Therefore, the cutting insert 10 can be accurately mounted centering on the axis O of the drill body 1, and the runout accuracy of the cutting edge 14 can be ensured.

Since the hole 6c opens in the body chip groove 5 of the drill body 1, air in the hole 6c can be discharged when the shaft portion 15a is fitted into the hole 6c, and the air in the hole 6c can be prevented from being compressed. Therefore, a force for pushing out the insert body 11 to the tip side of the drill body 1 is not generated by the pressure of the compressed air, and therefore, according to the present embodiment, the cutting insert 10 can be firmly and stably attached to the insert attachment seat 6.

In the present embodiment, as described above, the shaft portion 15a centered on the axis O is formed on the seating surface 15 of the insert main body 11, and the hole portion 6c capable of being fitted into the shaft portion 15a is formed on the bottom surface 6a of the insert mounting seat 6 centered on the axis O, but on the contrary, a hole portion centered on the axis O may be formed on the seating surface 15 of the insert main body 11, and a shaft portion capable of being fitted into the hole portion may be formed on the bottom surface 6a of the insert mounting seat 6 centered on the axis O, and the hole portion may be opened in the insert chip groove 13.

Further, in the present embodiment, the cooling hole 1a is formed in the drill main body 1 from the rear end surface of the shank 2 toward the tip end side along the axis O, the cooling hole 1a is branched into two in the immediate front of the insert attachment seat 6, and the wall surface of the main chip groove 5 facing the side opposite to the drill rotation direction T is opened, but instead, two cooling holes may be formed from the rear end surface of the shank 2 through between the two main chip grooves 5 toward the tip end side of the drill main body 1, and these cooling holes may be opened in the immediate front of the insert attachment seat 6 at the wall surface of the main chip groove 5 facing the side opposite to the drill rotation direction T.

In the present embodiment, the two mounting holes 11a penetrating from the distal end flank surface 12 to the seating surface 15 are disposed in the insert body 11 so as to be coaxial with the two screw holes 6d of the insert mount 6 in a state where the abutment surface 16 is brought into abutment with the wall surface 6b of the insert mount 6, but instead, the two mounting holes 11a may be disposed so as to be slightly eccentric to the two screw holes 6d of the insert mount 6 on the side opposite to the abutment surface 16.

Next, fig. 15 to 20 show a2 nd embodiment of the insert-indexable drill according to the present invention, and fig. 21 and 31 show exploded views of the insert-indexable drill according to the 2 nd embodiment. Fig. 22 to 24 show a2 nd embodiment of a drill body in the present invention of the indexable insert drill of the 2 nd embodiment, and fig. 25 to 30 show the 2 nd embodiment of a cutting insert 10 detachably attached to the drill body. In the indexable drill, the drill body, and the cutting insert 10 according to embodiment 2, the same reference numerals are given to portions common to embodiment 1 shown in fig. 1 to 14, and the description of embodiment 1 will be applied to the matters not mentioned in the description to be given later.

While in embodiment 1 the wall surface 6b of the insert attachment seat 6 facing the drill rotation direction T and the contact surface 16 of the insert body 11 of the cutting insert 10 in contact with the wall surface 6b are rectangular and the widths of the wall surface 6b and the contact surface 16 in the axis O direction are constant in the radial direction with respect to the axis O, in embodiment 2 the widths of the wall surface 6b and the contact surface 16 in the axis O direction are larger on the outer peripheral side than on the inner peripheral side of the drill body 1.

In embodiment 2, as shown in fig. 21, 24, 29, and 30, the wall surface 6b and the contact surface 16 are formed such that the widths in the axis O direction gradually increase from the inner circumferential side toward the outer circumferential side of the drill body 1, and the wall surface 6b and the contact surface 16 are formed in a substantially trapezoidal shape.

In addition, while in embodiment 1 the recess 6e as a relief portion formed at the corner where the bottom surface 6a and the wall surface 6b of the insert attachment seat 6 intersect is circular in cross section with a constant inner diameter, the cross sectional area is constant, in embodiment 2 the cross sectional area of the recess 6e is formed so that the opening on the outer peripheral surface side of the drill body 1 is larger than the opening on the body chip discharge groove 5 side.

In embodiment 2, as shown in fig. 22, the recess 6e is formed by a portion having a circular cross section and a portion having a concave curved cross section two-step larger in cross section than the circular cross section in order from the opening on the body chip flute 5 side toward the opening on the outer circumferential surface side of the drill body 1, and the length of the portion having a circular cross section and opening on the body chip flute 5 side in the recess 6e is longest. As shown in fig. 22 and 23, in embodiment 2, the intersecting edge line portion between the wall surface 6b of the insert attachment seat 6 and the inner circumferential surface of the body chip groove 5 is chamfered, and a chamfered portion 6f intersecting the wall surface 6b and the inner circumferential surface of the body chip groove 5 is formed.

In the indexable drill, the cutting insert 10, and the drill body 1 according to embodiment 2, it is needless to say that the same effects as those of embodiment 1 can be obtained, and since the width of the wall surface 6b of the insert attachment seat 6 in the axis O direction of the abutment surface 16 of the cutting insert 10 is first set to be wider on the outer peripheral side than on the inner peripheral side of the drill body 1, the abutment area of the abutment surface 16 that abuts against the wall surface 6b can be secured to be large on the outer peripheral side of the drill body 1 on which the largest cutting load acts during drilling.

Therefore, the stress of the insert attachment seat 6 acting on the outermost periphery of the drill body 1 can be reduced, the cutting insert 10 can be stably held against the cutting load during drilling, and high-precision drilling can be performed. In particular, in the present embodiment, the width of the wall surface 6b and the contact surface 16 in the axis O direction is formed so as to gradually increase from the inner circumferential side toward the outer circumferential side of the drill body 1, and therefore the contact area of the contact surface 16 with the wall surface 6b can be ensured to be large.

In embodiment 2, a recess 6e as a relief portion is formed at a corner portion where the bottom surface 6a and the wall surface 6b of the insert attachment seat 6 intersect so as to be recessed with respect to the bottom surface 6a and the wall surface 6b, and the cross-sectional area of the recess 6e is formed such that an opening portion on the outer circumferential surface side of the drill body 1 is larger than an opening portion on the body chip discharge groove 5 side. Therefore, as described above, the stress concentration in the recess 6e can be relieved on the outer peripheral surface side of the drill body 1 on which the largest cutting load acts during drilling.

On the other hand, since the cross-sectional area of the opening portion on the body flute 5 side is small, the rigidity of the convex wall portion 7 of the drill body 1 forming the wall surface 6b is not impaired, and the stability of the cutting insert 10 is not hindered. In particular, in the present embodiment, the cross-sectional area of the recess 6e is formed to be gradually increased, and the length of the segment of the portion having a circular cross-section on the side of the body chip groove 5 is longest, so that the rigidity of the convex wall portion 7 can be more reliably maintained. The cross-sectional shape of the recess 6e may be a circular or non-circular concave curve.

As in embodiment 2, by chamfering the intersecting ridge line portion between the wall surface 6b of the insert attachment seat 6 and the inner peripheral surface of the body flute 5 to form a chamfered portion 6f intersecting the wall surface 6b and the inner peripheral surface of the body flute 5, it is possible to prevent the occurrence of scratches and chipping compared to the case where the intersecting ridge line portion holds a sharp edge. The chamfered portion 6f is formed in a concave curved surface shape which is mostly inclined in the axis O direction, without contacting the insert main body 11.

The shaft portion 15a and the hole portion 6c in embodiment 2 will be described in detail with reference to fig. 31. In the present embodiment, in the hole portion 6c in which the bottom surface 6a of the insert attachment seat 6 of the drill body 1 is open, the portion on the tip end side is a large diameter portion 6c1 having a cross-sectional circular shape with a constant inner diameter centered on the axis O and a long length in the axis O direction, and the portion on the rear end side is a small diameter portion 6c2 having a cross-sectional circular shape with a constant inner diameter slightly smaller than the large diameter portion 6c1 centered on the axis O and a short length in the axis O direction than the large diameter portion. However, the large-diameter portion 6c1 and the small-diameter portion 6c2 are cut away from the bottom surface of the body flute 5 that opens toward the bottom surface on the outer periphery of the drill body 1.

On the other hand, as in embodiment 1, the shaft portion 15a projecting from the seating surface 15 of the insert body 11 of the cutting insert 10 is formed in a multi-stage cylindrical shape centered on the axis O, the front end portion of which is the large diameter portion 15a1, and the rear end portion of which is the small diameter portion 15a2 having a diameter slightly smaller than that of the large diameter portion 15a1, and the length of the large diameter portion 15a1 in the axis O direction is longer than that of the small diameter portion 15a2 in the axis O direction. However, in the shaft portion 15a, the portion forming the insert chip groove 13 is also cut along the bottom surface of the insert chip groove 13 facing the outer peripheral side.

In the present embodiment, the outer diameter of the large diameter portion 15a1 of the shaft portion 15a is set to a size that can be fitted into the large diameter portion 6c1 of the hole portion 6c, so that the insert body 11 of the cutting insert 10 can be coaxially mounted with high accuracy about the axis O of the drill body 1, and high runout accuracy can be secured for the cutting edge 14. In order to ensure such high runout accuracy, the following is specified in JIS B0401-1: 1998(ISO 286-1: 1988), it is desirable that shaft portion 15a be in the range of H6-H7 and that hole portion 6c be in the range of H6-H7.

The length of the shaft portion 15a in the direction of the axis O is slightly smaller than the length (depth) of the hole portion 6c in the direction of the axis O, the length of the large diameter portion 15a1 of the shaft portion 15a in the direction of the axis O is also slightly smaller than the length (depth) of the large diameter portion 6c1 of the hole portion 6c in the direction of the axis O, and when the shaft portion 15a is fitted into the hole portion 6c, no gap is formed between the bottom surface 6a of the insert attachment seat 6 of the drill body 1 and the seating surface 15 of the insert body 11 of the cutting insert 10. These configurations are the same as in embodiment 1, except that the inner diameter of the hole 6c is constant.

Industrial applicability

According to the present invention, even in wet cutting in which drilling is performed while supplying a coolant, it is possible to prevent cutting chips from becoming sludge together with the coolant and entering a portion where the contact surface of the cutting tip and the wall surface of the tip attachment seat come into contact from the distal end side of the drill body, and therefore it is possible to prevent wear from occurring on the contact surface and the wall surface, and to perform stable drilling over a long period of time. This enables industrial use.

Description of the symbols

1 drill bit body

1a cooling hole

5 chip groove of main body

6 blade mount pad

Bottom surface of 6a blade mount 6

6b wall surface of blade mounting seat 6

6c hole part

6c1 Large diameter portion of hole 6c

6c2 minor diameter portion of hole 6c

6d screw hole

6e recess

6f chamfer part

7 convex wall part

7a front end surface of the projecting wall portion 7

10 cutting insert

11 blade body

11a mounting hole

12 front end flank face

13 blade chip groove

14 cutting edge

15 seating surface

15a shaft part

15a1 Large diameter portion of shaft portion 15a

15a2 small diameter portion of shaft portion 15a

16 abutting surface

17 convex part

17a rear end surface of the projection 17

17b side surface of the convex portion 17 facing the opposite side to the bit rotation direction T

18 clamping screw

Axis of the O-bit body 1

Direction of rotation of the T-bit

Contact portion between the P-wall surface 6b and the contact surface 16

Intersection ridge between the Q-tip flank surface 12 and the side surface 17b of the convex portion 17