阅读说明：本技术 铣削方法和切削刀片的用途 (Milling method and use of cutting insert ) 是由 马卡斯·克拉比克勒 彼得·伯特切尔 于 2018-05-22 设计创作，主要内容包括：本发明涉及一种用于借助于至少一个大体上多边形的切削刀片(2)来铣削工件(1)的方法,所述切削刀片布置在刀架(3)中,其中所述刀架(3)的主轴轴线(S)与被加工工件表面(4)的平面法线(N)形成一个大于0°的角度(γ),并且其中所述切削刀片(2)的主切削刃(5)与所述被加工工件表面(4)之间的一个有效导程角(κ<Sub>eff</Sub>)在0°与20°之间。(The invention relates to a method for milling a workpiece (1) by means of at least one substantially polygonal cutting insert (2) which is arranged in a tool holder (3), wherein a spindle axis (S) of the tool holder (3) forms an angle (gamma) of more than 0 DEG with a plane normal (N) of a workpiece surface (4) to be machined, and wherein an effective lead angle (kappa) between a main cutting edge (5) of the cutting insert (2) and the workpiece surface (4) to be machined eff ) Between 0 ° and 20 °.)

1. Method for milling a workpiece (1) by means of at least one substantially polygonal cutting insert (2), the cutting insert (2) being arranged in a tool holder (3), wherein a spindle axis (S) of the tool holder (3) makes an angle (γ) of more than 0 ° with a plane normal (N) of a workpiece surface (4) to be machined, and wherein an effective lead angle (κ) between a main cutting edge (5) of the cutting insert (2) and the workpiece surface (4) to be machined_eff) Between 0 ° and 20 °.

2. A method according to claim 1, wherein the cutting insert (2) is inserted into the tool holder (3) in such a way that it is at a normal (N) to the spindle axis (S)_S) A theoretical lead angle (k) of between 20 DEG and 40 DEG with respect to a main cutting edge (5) of the cutting insert (2)_th)。

3. The method according to claim 1 or 2, wherein the at least one cutting insert (2) is configured as a substantially triangular or substantially quadrangular or substantially pentagonal indexable insert.

4. Method according to any of the preceding claims, wherein the angle (γ) between the spindle axis (S) and the plane normal (N) is between 3 ° and 35 °.

5. Method according to any one of the preceding claims, wherein the axial depth of cut (a)_p) Less than 3.0 mm.

6. Method according to any one of the preceding claims, wherein the feed per tooth (f) is_z) Between 0.60 and 0.90 mm.

7. Use of a substantially polygonal cutting insert (2) for a workpiece (1) to be machined, wherein the cutting insert (2) is arranged in a tool holder (3), the tool holder (3) is rotatable about a spindle axis (S), and the spindle axis (S) of the tool holder (3) makes an angle (γ) of more than 0 ° with a plane normal (N) of a workpiece surface (4) to be machined.

8. Use according to claim 7, wherein the cutting insert (2) is mounted in the tool holder (3) such that it is normal (N) to the spindle axis (S)_S) A theoretical lead angle (k) of between 20 DEG and 40 DEG with the main cutting edge (5) of the cutting insert (2)_th)。

9. Use according to claim 7 or 8, wherein the cutting insert (2) is configured as a substantially triangular or substantially quadrangular or substantially pentagonal indexable insert.

10. Use according to any one of claims 7 to 9, wherein the angle (γ) between the spindle axis (S) and the plane normal (N) is between 3 ° and 35 °.

11. Use according to any one of claims 7 to 10, wherein the axial depth of cut (a)_p) Less than 3.0 mm.

12. Use according to any one of claims 7 to 11, wherein the feed per tooth (f) is_z) Between 0.60 and 0.90 mm.

Technical Field

The invention relates to a milling method having the features of the preamble of claim 1.

Background

So-called high feed cutting has been widely used for efficient machining to produce planar and shaped surfaces. High feed cutting mills with a relatively small depth of cut and high feed rate. The depth of cut is limited by a small lead angle. The lead angle is the angle between the main insert and the surface of the workpiece of the cutting insert, usually an indexable insert.

In the method, the typical feed rate is of the order of 0.7 to 3 mm/tooth, the axial depth of cut a_pTypically less than 2 mm.

During high feed cutting, the spindle is perpendicular to the workpiece surface being machined. Advantageously, the cutting forces are generated mainly in the axial direction of the tool. The cutting forces are transmitted along the spindle axis and thus in a particularly rigid direction towards the tool.

Cutting inserts for this purpose are usually triangular or quadrangular indexable inserts. A typical indexable insert for high feed cutting is shown, for example, in AT12004U 1. A typical lead angle in high feed cutting is less than 20 °.

High feed cutting is commonly used to produce planar surfaces on flat workpieces.

Disclosure of Invention

The problem addressed by the present invention is to indicate a milling method with which the benefits of high feed cutting can be applied to the machining of curved surfaces.

The problem is solved by a method having the features of claim 1. Advantageous embodiments are indicated in the dependent claims.

In order to machine a workpiece of a complex shape, such as a turbine blade, it is common to incline the spindle axis of the milling cutter relative to the surface of the workpiece being machined. This inclination or skew of the spindle axis is also referred to as camber (Sturz) and it occurs in the feed direction, i.e. such that the spindle axis of the milling cutter forms an angle greater than 0 ° with the plane normal (normal vector) of the workpiece surface being machined. Thus, the angle is defined as positive in the feed direction. The inclination of the spindle axis is necessary in order to follow complex surface contours and to free straight cutting inserts of an unarticulated milling cutter. The machining is performed with a circular plate milling cutter, a ball end milling cutter or a ball spindle milling cutter made of cemented carbide.

According to the invention, a method is provided for milling a workpiece by means of at least one substantially polygonal cutting insert arranged in a tool holder, wherein a spindle axis of the tool holder makes an angle of more than 0 ° with a plane perpendicular to a surface of the workpiece to be machined, wherein a lead angle between a main cutting edge of the cutting insert and the surface of the workpiece to be machined is between 5 ° and 20 °.

A substantially polygonal basic shape means that the cutting insert has a polygonal basic shape, possibly with a circular outer contour.

Due to the inclination of the milling cutter spindle axis in the feed direction, the lead angle between the main cutting edge of the cutting insert and the workpiece surface decreases. With the usual mounting position of the cutting insert for high feed cutting on the tool holder, this will considerably reduce the maximum axial cutting depth achievable by the cutting insert, so that economical milling will no longer be possible.

As a remedy, it is proposed to modify the positioning of the cutting edges of the cutting inserts on the milling cutter in order to compensate for the inclined position of the spindle axis.

The proposed method makes it possible to use cutting inserts with a polygonal basic shape for high-feed cutting even in applications with an inclined spindle axis.

In other words, according to the present invention, a tool inherent lead angle that is too large for high feed cutting and therefore would not be suitable is selected. The tool inherent or theoretical lead angle refers to the lead angle that results between the cutting edge and the workpiece surface for an untilted spindle axis (i.e., 90 ° between the spindle axis and the workpiece surface).

By the inclination of the spindle axis only, an effective lead angle is achieved at the workpiece, allowing high feed cutting on workpieces of complex shape such as turbine blades.

Preferably, the cutting insert is inserted into the tool holder in such a way that a theoretical (tool-specific) lead angle of between 20 ° and 40 ° exists between the normal to the spindle axis and the main cutting edge of the cutting insert. In other words, when the spindle axis is positioned perpendicular to the surface of the workpiece being machined, there is a theoretical (tool-inherent) lead angle between the spindle axis and the main cutting edge of the cutting insert of between 20 ° and 40 °.

Preferably, at least one cutting insert is configured as a substantially triangular or substantially quadrangular or substantially pentagonal indexable insert. By "substantially" is here meant that the basic shape of the cutting insert is triangular, quadrangular or polygonal. This also includes deviations from the strict geometric definition of a triangle, quadrangle or pentagon.

Generally, the cutting insert has a circular shape of an equilateral triangle or a circular shape of a square or a circular shape of a regular pentagon in a plan view. The side edge on which the cutting edge is formed is bent outward in a convex manner. The radius of curvature of the main cutting edge is preferably at least 1.5 times greater than the radius of the inscribed circle of the contour of the cutting insert in top view.

However, in the case of the circular plate, the inclination of the spindle axis does not cause a change in the lead angle of the cutting edge with respect to the workpiece, and when a cutting insert having a polygonal base shape is used, the inclination of the spindle axis causes a change in the lead angle of the cutting edge. Now, if the cutting insert having a polygonal basic shape is oriented on the tool holder in such a way that when the spindle axis is perpendicular to the surface of the workpiece to be machined, there is a condition of high feed cutting, this suitability is lost due to the spindle axis being inclined.

The method according to the invention makes it now possible to use triangular, quadrangular or pentagonal plates instead of the previously typical circular plates for milling operations with inclined spindle axes.

Preferably, the angle between the spindle axis and the plane normal is between 3 ° and 35 °, further preferably between 10 ° and 30 °, particularly preferably between 15 ° and 25 °.

Preferably, the axial depth of cut (a)_p) Less than 3.0mm, preferably less than 2.50 mm.

Preferably, the feed per tooth (f)_z) Between 0.60mm and 0.90 mm.

The method is particularly suitable for performing milling operations on turbine blades: the complex shape of the turbine blades often requires a significant skew of the spindle axis of the milling cutter used. The method is particularly suitable for machining the blade body and for manufacturing the receiving groove at the blade root.

Protection is also sought for the use of substantially polygonal cutting inserts for the workpiece to be machined, wherein the cutting inserts are arranged in a tool holder which is rotatable about a spindle axis, and the spindle axis of the tool holder makes an angle of more than 0 ° with a plane perpendicular to the surface of the workpiece to be machined.

When using the cutting insert, the cutting insert is preferably mounted in the tool holder such that there is a theoretical lead angle between the normal to the spindle axis and the main cutting edge of the cutting insert of between 20 ° and 40 °.

Preferably, the cutting insert is configured as a substantially triangular or substantially quadrangular or substantially pentagonal indexable insert.

Preferably, the angle between the spindle axis and the plane normal is between 3 ° and 35 °.

Preferably, the machining is an axial depth of cut a_pHigh feed cutting of less than 3.0mm, more preferably less than 2.50 mm. Preferably, the feed per tooth f_zBetween 0.60mm and 0.90 mm.

Drawings

The invention will be explained in more detail below by means of the figures. Shown here are:

fig. 1a-1b are schematic views of a tool holder with a cutting insert

FIG. 2 is a schematic view of lead angles of a circular cutting insert

Fig. 3a-3c are top views of polygonal cutting inserts

FIG. 4 side view of the tool holder

FIGS. 5a-5b schematically illustrate the method

Detailed Description

Fig. 1a schematically shows the orientation of a cutting insert 2 on a proposed tool holder 3 with respect to a workpiece 1, said cutting insert being positioned with a non-inclined spindle axis S. The feed direction F of the cutting insert 2 is indicated by a block arrow. The tool holder 3 has a clockwise rotation, see direction of rotation R. The plane normal N is perpendicular to the workpiece surface 4 to be machined.

In the present embodiment, the spindle axis S makes an angle of 90 ° with the workpiece surface 4 to be machined, corresponding to a camber or inclination γ of the spindle axis with respect to the plane normal N of 0 °, and the theoretical lead angle κ between the main cutting edge 5 and the workpiece surface 4 to be machined is obtained_th. Due to the curvature of the main cutting edge 5, the lead angle is determined by the chord of the main cutting edge 5. The chord extends between the two ends of the main cutting edge 5.

Lead angle κ shown here_th30 deg., which is too large to be suitable for high feed cutting. From lead angle k_thThe obtained axial cutting depth a_{p th}Too large to allow high feed rates.

The dashed line drawn on the workpiece 1 represents the cutting cross-section to be removed during the next pass of the cutting insert 2.

Fig. 1b shows a configuration provided by the method according to the invention:

here, the spindle axis S is inclined at an angle γ of about 20 ° relative to the plane normal N, so that there is an effective lead angle κ of 10 ° between the main cutting edge 5 and the workpiece surface_eff。

Since the lead angle κ decreases due to the inclination of the spindle axis S, the feed amount per tooth f can be increased_z. Inherent lead angle k of the tool_thAnd the inclination of the spindle axis S by an angle gamma, to produce an effective lead angle kappa with respect to the surface of the workpiece to be machined_eff，

κ_eff＝κ_th–γ

Wherein κ_thIs the theoretical or inherent lead angle of the tool.

For curved workpiece surfaces, the plane normal N may be located at a radially inward point of action of a particular cutting insert, as shown in fig. 1 b.

The values of the inclination angle γ of the spindle axis S and the final lead angle κ between the main cutting edge 5 and the workpiece surface 4 shown here are exemplary. Preferred values of the inclination angle γ of the spindle axis S relative to the plane normal N lie in the range between 3 ° and 35 °, more preferably between 10 ° and 30 °, particularly preferably between 15 ° and 25 °.

Effective lead angle k between the main cutting edge 5 and the workpiece surface 4_effResulting from the mounting position of the cutting insert 2 on the tool holder 3 and the inclination angle gamma of the spindle axis S.

Fig. 2 shows a circular cutting insert 2' for engagement with a workpiece 1, for example a circular cutting insert not intended for the method according to the invention.

Fig. 2 shows two processing cases:

in configuration I, the cutting insert 2' is used for a large axial cutting depth a_pI. The result is a large lead angle κ_I。

In configuration II, the cutting insert 2' is used for a small axial cutting depth a_pII. The result is a small lead angle k_II。

For a circular cutting insert, the lead angle increases with increasing cutting depth to assume 45 ° for a maximum cutting depth corresponding to the radius of the circular cutting insert. Due to the circular arc shape of the cutting edge, there is an actual lead angle of 0 ° at the lowest point and 90 ° at the maximum cutting depth corresponding to the radius.

For a circular cutting insert, the length of the engaged cutting edge increases with increasing diameter of the cutting insert for a given depth of cut; the force on the cutting edge decreases with increasing length.

Since low cutting forces are desirable for high feed cutting, the largest possible diameter is preferred for high feed cutting with circular cutting inserts. This also constitutes a significant limitation of circular cutting inserts, since the radius of curvature of the cutting edge corresponds to the radius of the geometrical dimension. Thus, a large radius of curvature also means a large indexable insert.

Fig. 3a to 3c schematically show a substantially polygonal cutting insert 2, e.g. provided according to the method of the present invention, in top view.

The cutting insert of fig. 3a is shaped with a square basic shape (so-called S-plate) having a convex circular outer contour.

Preferably, a cutting edge is formed on each rounded side edge of the cutting insert 2 (the main cutting edge 5 is emphasized here). Thus, in the case of a square basic shape, a quadruple indexable cutting insert is obtained. Quadruple indexable means that four separate main cutting edges 5 are available for machining. In this case, the new machining position is adjusted by rotating the cutting insert 2 by 90 °. Thus, by means of the square basic shape of the cutting insert 2, four independent main cutting edges 5 are obtained.

To illustrate the shape of the cutting insert 2, an inscribed circle D is drawn_IK. Radius of curvature R of the main cutting edge 5_HSPreferably more than the inscribed circle D_IKIs at least 1.5 times larger.

In addition to the cutting insert 2 shown here having a quadrangular basic shape, the method according to the invention also contemplates cutting inserts having a substantially triangular basic shape or a pentagonal basic shape.

Figure 3b shows a cutting insert 2 having a substantially triangular basic shape (a so-called T-plate),

fig. 3c shows a cutting insert 2 having a substantially pentagonal basic shape, a so-called P-plate.

In this case, the radius of curvature of the main cutting edge is at least greater than that of the inscribed circle D, in contrast to a circular cutting insert_IKRadius R of_IK1.5 times larger.

For the method according to the invention, the quadrilateral plate (S-plate) has the most advantageous ratio of the available cutting depth and the number of index positions.

Fig. 4 shows a tool holder 3 with a spindle axis S and a plurality of cutting inserts 2. The tool holder 3 is adjusted relative to the work piece surface 4 such that the spindle axis S is perpendicular to the work piece surface 4.

The cutting insert 2 is mounted in the tool holder 3 in such a way thatNormal N of main shaft axis S_SAnd the main cutting edge 5 of the cutting insert 2, there is a theoretical lead angle k between 20 and 40_th. The mounting position of the cutting insert 2 produces a theoretical (tool-specific) lead angle κ in the tool holder 3 between the main cutting edge 5 and the workpiece surface 4 to be machined_th. However, the lead angle κ shown here_thToo large and therefore unsuitable for high feed cutting.

As shown in fig. 5a and 5b, the configuration of the tool holder 3 and the cutting insert 2 shown in fig. 4 can only be used for high feed cutting by means of the method according to the invention.

Fig. 5a and 5b show different views of a method according to the invention for milling a workpiece 1, which is a turbine blade in this case.

The tool holder 3 comprises a plurality of substantially polygonal cutting inserts 2. In the present exemplary embodiment, the cutting insert 2 has a square basic shape. The spindle axis S of the tool holder 3 has an angle γ of more than 0 ° with respect to a normal N to a plane perpendicular to the surface 4 of the workpiece to be machined. Preferred values of the inclination angle γ of the spindle axis S lie in the range between 3 ° and 35 °, more preferably between 10 ° and 30 °, particularly preferably between 15 ° and 25 °. As can be seen in the side view of fig. 5a, the angle γ is in this embodiment about 20 °. Said angle gamma is positive as measured in the feed direction F.

The effective lead angle κ between the main cutting edge 5 of the cutting insert 2 and the workpiece surface 4 being machined, caused by the inclination of the spindle axis S and the mounting position of the cutting insert 2 on the tool holder 3_effBetween 5 ° and 20 °. In the present embodiment, the effective lead angle κ_effIs approximately 12.

As a reference for the value of the angle with respect to the surface 4 of the workpiece to be machined, the radially inward point of action of the cutting insert 2 at engagement is used (detail a).

The method allows milling with high feed. Typical values obtained in the method according to the invention are f_zIs 0.60-0.90 mm/tooth. In contrast, when using the circular plate of the prior art, only a low feed of about 0.35-0.45 mm/tooth is possible.

Another advantage of using polygonal cutting inserts is that also greater cutting depths can be achieved when the machining situation requires: thus, for example, with reduced feed rates and without tool changes, cutting depths as low as 5mm can be achieved. Such a cutting depth cannot be produced with a circular plate.

Fig. 5b shows the method in a perspective view. Preferably, as can be seen in fig. 5b, the feed direction F is substantially perpendicular to the longitudinal axis L of the turbine blade.