CN116490304A

CN116490304A - Rotary cutting tool

Info

Publication number: CN116490304A
Application number: CN202280007581.4A
Authority: CN
Inventors: 藤田隼
Original assignee: Kanefusa KK
Current assignee: Kanefusa KK
Priority date: 2021-03-02
Filing date: 2022-03-02
Publication date: 2023-07-25
Also published as: JPWO2022186253A1; WO2022186253A1

Abstract

The present invention provides a rotary cutting tool having a cutting edge with a helical angle, which can be manufactured more easily than before. The device comprises: a cutting insert (20) in which at least a cutting edge (E) that is a ridge line between a rake surface and a flank surface is formed of a hard sintered body that contains diamond and/or cubic boron nitride; and a main body (10), wherein the blade (20) is joined to a back surface (111) of a seat of the main body, the back surface (111) of the seat is flat and inclined with respect to the axis (Ax), and the rake surface and the flank surface are curved surfaces having a predetermined relief angle, a predetermined rake angle, and a predetermined helix angle. Particularly preferably, when a plane perpendicular to the back surface (111) of the holder and including the axial center (Ax) is viewed in the vertical direction, one end of the back surface (111) of the holder, which is joined to the insert (20), is located at a position forward of the axial center (Ax) in the rotational direction of the rotary cutting tool, and the rear end of the back surface (111) of the holder is located at a position rearward of the axial center (Ax) in the rotational direction of the rotary cutting tool. In a conventional rotary cutting tool, both ends of the back surface of the seat are located at the rear side in the rotation direction from the axial center (Ax).

Description

Rotary cutting tool

Technical Field

The present invention relates to a rotary cutting tool for machining nonferrous metals such as aluminum and aluminum alloys, wood, resins, CFRP, and the like, the rotary cutting tool having a cutting edge formed of a hard sintered body including a polycrystalline diamond (PCD) sintered body and/or a Cubic Boron Nitride (CBN) sintered body, and having a helix angle of an insert.

Background

There are cases where the cutting edge of the rotary cutting tool is formed of a hard sintered body. In a conventional rotary cutting tool having a helical angle, when forming a cutting edge made of a hard sintered body, the cutting edge is manufactured by grinding a round bar formed by sintering PCD together with a cemented carbide body, and the hard sintered body is spirally arranged in accordance with the helical angle of the cutting edge (patent documents 1 to 4, etc.).

Patent document 1: japanese patent No. 2934927

Patent document 2: japanese patent laid-open No. 2002-18630

Patent document 3: japanese publication Hei 5-2247

Patent document 4: japanese patent No. 3477183

In conventional rotary cutting tools, it is necessary to prepare cylindrical members such as round bars for integrating hard sintered bodies at different angles according to the magnitude of the helix angle, and it is difficult to say that the rotary cutting tools are suitable for various kinds of manufacturing.

Disclosure of Invention

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a rotary cutting tool having a cutting edge with a helix angle that can be manufactured more easily than before.

The rotary cutting tool of the present invention for solving the above problems comprises: the insert, at least the cutting edge of the ridge line intersecting the rake face and the flank face, is formed of a hard sintered body containing diamond and/or cubic boron nitride; and a main body, the blade being coupled to a seat of the main body,

the back surface of the seat is planar and inclined with respect to the axis of the rotary cutting tool, the rake surface and the flank surface are curved surfaces,

the difference between the maximum value and the minimum value of the helix angle at the axial center of the rotary cutting tool and the relief angle and the rake angle as viewed from the vertical cross section is 10 DEG or less within the effective range of the cutting edge,

when a plane perpendicular to the back surface of the holder and including the axial center is viewed in the vertical direction, one of both ends of the back surface of the holder, which is joined to the insert with respect to the axial center direction, is positioned forward of the axial center in the rotational direction of the rotary cutting tool, and the other end is positioned rearward of the axial center in the rotational direction of the rotary cutting tool.

The difference between the maximum value and the minimum value of the helix angle, the relief angle, and the rake angle is 5 ° or less, 3 ° or less, 2 ° or less, and more preferably 0 °. The effective range of the cutting edge refers to a range formed between one end and the other end of the cutting edge of the insert.

Further, the blade preferably has a length in the radial direction shorter than a length in the middle of the blade.

Further preferably, the insert is formed of a laminate of a hard sintered body layer formed of a hard sintered body and a cemented carbide layer made of cemented carbide forming a joint surface with the seat, and the cemented carbide layer is provided on the axial center side of the rake face at the front end in the rotational direction.

The rotary cutting tool according to the present invention has the above-described configuration, and thus, the back angle, the front angle, and the helix angle are each controlled within a predetermined range, whereby high performance can be exhibited, and the back surface of the seat is planar, so that the rotary cutting tool can be manufactured easily.

Drawings

Fig. 1 is a side view of a rotary cutting tool according to embodiment 1. Fig. 1 is a view of a plane perpendicular to the back surface of the seat and including the axial center, as viewed in the vertical direction.

Fig. 2 is an end view and a cross-sectional view as seen from the left side of fig. 1 at each of positions S to Z of the axial center in the direction perpendicular to the axial center of the rotary cutting tool of embodiment 1. The distance from the front end of the main body (left side of the paper surface of fig. 1) is as follows: s is 0mm, T is 5mm, U is 10mm, V is 15mm, W is 20mm, X is 25mm, Y is 30mm, and Z is 34mm.

Fig. 3 is a side view of the main body of embodiment 1.

Fig. 4 is a side view of the rotary cutting tool according to embodiment 2.

Fig. 5 is an end view and a cross-sectional view as seen from the left side of fig. 4 at each of positions S to X of the axial center in the direction perpendicular to the axial center of the rotary cutting tool of embodiment 2. The distance from the front end (left in the plane of the paper of fig. 4) is as follows: s is 0mm, T is 5mm, U is 10mm, V is 15mm, W is 20mm, X is 23mm.

Fig. 6 is a side view of the main body of embodiment 2.

Fig. 7 is a partial perspective view of the rotary cutting tool according to embodiment 3.

Fig. 8 is a partial front view of the rotary cutting tool according to embodiment 3.

Fig. 9 is a partial perspective view of components constituting the rotary cutting tool of embodiment 3.

Fig. 10 is an enlarged view of a portion where the blade is joined to the body of embodiment 3.

Fig. 11 is a side view of a conventional rotary cutting tool. Fig. 11 is a view of a plane perpendicular to the back surface of the seat and including the axial center, as viewed in the vertical direction.

Fig. 12 is an end view and a cross-sectional view from the left side of fig. 11 at each of positions S to X of the axial center in the direction perpendicular to the axial center of the conventional rotary cutting tool. The distance from the front end (left in the paper surface of fig. 11) is as follows: s is 0mm, T is 5mm, U is 10mm, V is 15mm, W is 20mm, X is 23mm.

Fig. 13 is a partial perspective view of the tip end portion of the rotary cutting tool according to modification 2.

Fig. 14 is a partial enlarged view of fig. 13.

Fig. 15 is a front partial enlarged view of the tip end portion of the rotary cutting tool according to modification 2.

Detailed Description

Hereinafter, the rotary cutting tool according to the present invention will be described in detail with reference to embodiments. The rotary cutting tool according to the present embodiment is a tool in which a cutting edge is formed on the outer periphery, and cutting processing can be performed on the outer periphery. The tip side may be formed with a cutting edge. The rotary cutting tool according to the present embodiment can be applied to a milling cutter such as an end mill. The cutting edge of the rotary cutting tool according to the present embodiment is formed of a hard sintered body. The hard sintered body is formed of PCD and/or CBN. The size of the rotary cutting tool of the present embodiment is not particularly limited. The lower limit of the diameter can be 10mm, 15mm, 20mm, 25mm, or 30mm, and the upper limit can be 50cm, 30cm, 20cm, or 10 cm. In the present specification, the drawings are schematic, and the structures of the scale and the detailed portions are emphasized and omitted for convenience of description. In addition, the same reference numerals (axis, cutting edge, etc.) may be given to the same functional components even though they are different.

(embodiment 1)

As shown in fig. 1 and 2, the rotary cutting tool 1 according to the present embodiment is a tool that rotates in a counterclockwise direction (R direction in fig. 2) when viewed from the front end side (left in fig. 1) to perform cutting. The rotary cutting tool 1 has a main body 10 (fig. 3) and an insert 20 fixed to a back surface 111 of a seat provided in a groove 10a of the main body 10. The groove 10a is a groove formed in the outer peripheral portion of the blade 11 in a spiral shape from the front end toward the rear. The blade 20 engages in the groove 10a.

The blades 20 are provided at 180 ° intervals on the outer periphery of the main body 10, and are engaged with the rear surface 111 of the seat provided in the groove 10a via the engagement surface 20a. The groove 10a also serves to discharge chips generated during cutting. As shown in fig. 2, when a plane (a plane parallel to the paper surface of fig. 1) perpendicular to the rear surface 111 of the holder and including the axial center Ax is viewed in the vertical direction, one of both ends (left end and front end of fig. 1) of the rear surface 111 of the holder with respect to the axial center Ax direction is located at a position (upper side of fig. 1) forward (upper side of fig. 1) of the axial center Ax in the rotational direction of the rotary cutting tool 1, and the other end (right end and rear end of fig. 1) is located at a position (lower side of fig. 1) rearward (lower side of fig. 2) of the rotational direction of the rotary cutting tool 1) with respect to the axial center Ax. In the conventional rotary cutting tool 3, as shown in fig. 11 and 12, when a plane perpendicular to the back surface 311 of the holder and including the axial center Ax is viewed in the vertical direction, both ends (one end and the other end) of the end of the back surface 311 of the holder with respect to the axial center Ax direction are all located at positions rearward of the axial center Ax in the rotation direction of the rotary cutting tool 5 (fig. 11 and 12 (S)).

The body 10 is formed of a usual material such as tool steel or cemented carbide. The main body 10 is composed of a blade 11, a transition 12, and a shank 13 in this order from the tip end side in the axial direction Ax. The blade 11 may have a cylindrical shape or a tapered shape.

In the blade 11, a seat back surface 111 is formed in the groove 10a, and the seat back surface 111 is a part of a plane inclined at a predetermined angle (10 ° in the rotary cutting tool 1) with respect to the axis Ax which is the rotation axis of the rotary cutting tool 1. The insert 20 is joined to the back surface 111 and the bottom surface of the seat by welding such as brazing.

The insert 20 has an engagement surface 20a that engages with the seat back surface 111 and is formed with a cutting edge E. The insert 20 has a double-layer structure in which a hard sintered body layer 21 made of a hard sintered body and formed with a cutting edge E and a cemented carbide layer 22 made of cemented carbide and provided on the side of a joint surface 20a are joined.

With the insert 20, the cutting edge E can be formed by electric discharge machining, laser machining, grinding machining based on a diamond wheel or the like, or the like after joining the insert blank of a rectangular parallelepiped of a double-layer structure to the back surface 111 and the bottom surface of the seat of the main body 10, so that the rake angle and the relief angle are constant in any rotational section in the axial direction. Here, the relief angle is 8 °, and the rake angle is 10 °, but is not particularly limited. The cutting edge E can be manufactured simply as compared to the case where it is formed and then bonded to the back surface 111 of the seat. Furthermore, the method of forming the cutting edge E first is not excluded.

The back surface 111 of the seat is a portion of a plane, i.e., a flat surface. The blade 20 is engaged on the back face 111 of the seat. The length of the back surface 111 of the seat in the radial direction becomes shorter near the front end and near the rear end. In particular, for processing reasons, the surface is curved after passing over the joint surface on the rear end side of the seat rear surface 111. The insert 20 is a rectangular parallelepiped member, and a surface (inner surface 20 b) orthogonal to the surface (joint surface 20 a) joined to the rear surface 111 of the seat and on the side close to the axial center Ax is a surface substantially parallel to the axial center Ax. The surface intersecting the rear surface 111 of the seat of the main body 10 and abutting the inner surface 20b of the blade 20 has a shape (in this embodiment, a flat surface) complementary to the shape of the inner surface 20b of the blade 20.

The rotary cutting tool of the present embodiment can be manufactured as follows, for example. First, the main body 10 is manufactured. The body 10 may be manufactured by cutting the same rod as a whole, or may be manufactured by separately forming a plurality of portions (for example, the blade portion 11, the transition portion 12, and the shank portion 13) and then connecting and engaging the plurality of portions. The blade 11 is formed with a spiral groove 10a extending rearward from the front end by cutting or the like. A back surface 111 of the seat for engagement of the blade 20 is also formed in the slot 10a. The formation of the seat back surface 111 may be performed together with the groove 10a or may be performed independently after the groove 10a is formed.

After the back surface 111 and the bottom surface of the seat are formed, the insert 20 is joined to the back surface 111 and the bottom surface of the seat by brazing or the like. After the insert 20 is joined, the cutting edge E is formed by performing electric discharge machining, grinding, or the like on the insert 20 so as to be a predetermined flank surface and a predetermined rake surface. The cutting edge E is a ridge line where the flank surface and the rake surface intersect. In forming the cutting edge E, a portion of the insert 20 protruding outward from the outer peripheral surface of the body 10 is also removed by grinding or the like to have a predetermined diameter. In this structure, the length in the radial direction of both ends (front end and 34 mm) of the blade 20 is shorter than the length in the middle.

(embodiment 2)

As shown in fig. 4 and 5, the rotary cutting tool 5 of the present embodiment includes a main body 50 and a blade 60. The main body 50 (fig. 6) has the same structure except that the inclination of the spiral groove 50a (i.e., the inclination of the blade 60) is 15 ° different from that in the case of 10 ° in the main body 10. The insert 60 has a double-layer structure in which a hard sintered body layer 61 and a cemented carbide layer 62 are joined, and has the same structure as the insert 20 except that the insert has a fine shape formed by cutting according to the shape of the groove 50a provided in the main body 50.

As shown in fig. 4, when a plane perpendicular to the back surface 511 of the seat and including the axial center Ax is viewed in the vertical direction, the front end serving as one end of the back surface 511 of the seat is located at a position forward of the axial center Ax in the rotational direction of the rotary cutting tool 5 (fig. 5 (S)), and the rear end serving as the other end is located at a position rearward of the axial center Ax in the rotational direction of the rotary cutting tool 5 (fig. 5 (W) (X)). In the conventional rotary cutting tool 3, as shown in fig. 11 and 12, when a plane perpendicular to the back surface 311 of the holder and including the axial center Ax is viewed in the vertical direction, the front end of the back surface 311 of the holder is located at a position rearward of the axial center Ax in the rotational direction of the rotary cutting tool 5 (fig. 11 and 12 (S)).

When the inclination of the insert 60 increases, in the conventional rotary cutting tool configuration, the inclination of the insert 60 at both ends is too large to be accommodated in the groove 50a, and the length of the insert 60, which can form the cutting edge E, becomes short. Alternatively, as shown in fig. 11, the inclination (helix angle) is weakened. With this configuration, the length in the radial direction of the blade 60 accommodated in the groove 50a of the main body 50 can be increased to ensure the length in the axial direction Ax of the blade 60 required for forming the cutting edge E. In this structure, the radial length of both ends (front end and 23 mm) of the blade 60 is shorter than the intermediate length.

Embodiment 3

As shown in fig. 7 and 8, the rotary cutting tool 7 of the present embodiment is a tool that rotates in a rotation direction R, and includes main bodies 70 and 80 and blades 90 (91 and 92). The main bodies 70 and 80 are substantially disk-shaped members, and are integrally overlapped in the thickness direction (axial direction).

As shown in fig. 9, in the main body 70, six blades 91 disposed on the outer periphery are disposed so as to open outward in the axial direction (an angle with respect to the axial direction is 70 ° in the counterclockwise direction) toward the rotation direction R. In the main body 80, six blades 92 disposed on the outer periphery are disposed so as to open outward in the axial direction (an angle with respect to the axial direction is 70 ° in the clockwise direction) toward the rotation direction R. The blades 91 and 92 are arranged to overlap in the axial direction when the bodies 70 and 80 are integrated.

The main bodies 70 and 80 are formed with blade engaging portions 71 and 81, and the blade engaging portions 71 and 81 are formed with flat seat back surfaces 711 and 811, and the blades 91 and 92 are engaged with the seat back surfaces 711 and 811.

When the rear surface 711 of the holder is viewed in the vertical direction in a plane perpendicular to the rear surface 711 of the holder and including the axial center, one end 71a of both ends 71a and 71b of the rear surface 711 of the holder with respect to the axial center direction is positioned forward (downward in fig. 8) of the axial center Ax in the rotation direction of the rotary cutting tool 7, and the other end 71b is positioned rearward (upward in fig. 8) of the axial center in the rotation direction of the rotary cutting tool 7.

When a plane perpendicular to the back surface 811 of the seat and including the axial center is viewed in the vertical direction, the back surface 811 of the seat is opposite in pitch angle to the back surface 711 of the seat, and one end 81a of both ends 81a and 81b of the back surface 811 of the seat with respect to the axial center direction is located forward of the axial center in the rotational direction of the rotary cutting tool 7, and the other end 81b is located rearward of the axial center in the rotational direction of the rotary cutting tool 7.

The inserts 91 and 92 are machined by electric discharge machining, laser machining, grinding machining, or the like so that rake angles and relief angles are constant at any portion of the cutting edge.

(modification 1)

In the embodiment, the inner surface 20b of the insert 20 near the axial center Ax is a plane, but it is preferable that a portion of the inner surface 20b near the axial center Ax (in the vicinity of V in fig. 2, in the vicinity of U in fig. 5) forms a concave surface that is the most concave. Accordingly, the shape of the surface to be joined by the blade may be a shape complementary to the inner surface of the blade.

This makes it possible to increase the size of the blades 20 and 60 while maintaining the strength of the main bodies 10 and 50. The description is based on fig. 5. The length of the blade 60 in the radial direction is shorter than the length of the portion of the blade 60 in the radial direction at the tip (fig. 5 (S)), the portion of the blade 60 in the 23mm (fig. 5 (W)), because the size (the length in the radial direction) of the blade 60 is determined so that the portion of the blade 60 in the 10mm closest to the axial center Ax on the inner side surface thereof (fig. 5 (U)) can exhibit sufficient strength. Therefore, although the length of the blade 60 in the radial direction may be insufficient in the portions at both ends, the shape of the inner surface of the blade 60 may be a concave surface recessed in the vicinity of the portion closest to the axial center Ax (a shape of the bottom surface of the seat, conversely, a shape of bulging in the vicinity of the center), and the length of the blade 60 in the radial direction may be increased as it is moved away from both ends from the concave surface. As a result, the length of the insert 60 in the axial direction Ax can be increased, and therefore, the cutting edge E can be increased in length, and the inclination of the cutting edge E can be further increased (or alternatively). Further, although the back surface of the seat is substantially planar, when a slight concave-convex is provided around the seat, and grooves or pits are formed, it is allowed to remove the formed concave-convex or the like to be substantially planar.

(deformation form 2)

The helix angle (angle of the cutting edge) of the rotary cutting tool 1 according to embodiment 1 is positive, but may be negative. For example, as shown in fig. 13 to 15, the rotary cutting tool A1 according to the present modification is a tool that rotates counterclockwise when viewed from the front end side (upper right in fig. 13) to perform cutting. The rotary cutting tool A1 has: a main body a10 having two grooves a10a provided at 180 ° intervals on the outer periphery; and a blade a20 fixed to the back surface of a seat a112 provided in a margin portion (japanese) between two grooves a10a of the main body a10. The back of the seat is a portion of a plane, i.e., a flat face.

The tip end portion of the main body a10 is fixed with a bottom edge blade a30 and a tip end outer peripheral edge blade a40. The bottom edge insert a30 is provided with a cutting edge in a direction perpendicular to the axial center Ax of the rotary cutting tool A1 of the present modification, and machines the tip direction by rotating the rotary cutting tool A1 of the present modification. The tip peripheral edge blade a40 is set to a positive helix angle with the axial center Ax of the rotary cutting tool A1 of the present modification, and the rotary cutting tool A1 of the present modification is rotated to machine the peripheral direction of the tip.

The groove a10a is formed on the outer peripheral portion of the blade a11 so as to face rearward from the front end and so that the helix angle is positive. The groove a10a also serves to discharge chips generated during cutting.

The blades a20 are provided with four and eight in total, respectively, at the margin portions of the outer periphery of the main body a10 so as to have a negative helix angle. As shown in fig. 15, when a plane perpendicular to the back surface of the holder and including the axial center Ax is viewed in the vertical direction, one end Tf of both ends Tf and Te of the back surface of the holder with respect to the axial center Ax direction is located at a position rearward (leftward in fig. 15) of the axial center Ax in the rotational direction of the rotary cutting tool A1, and the other end Te is located at a position forward (rightward in fig. 15) of the axial center Ax in the rotational direction of the rotary cutting tool A1.

The four blades a20 provided in each margin portion are uniformly arranged in the direction of the axial center Ax of the main body a10, and the end portions thereof are arranged at positions overlapping with a part of the cutting edge of the other margin portion in the direction of the axial center Ax of the adjacent blade a20.

The insert a20 has an engagement surface engaged with the back surface of the seat, and is formed with a cutting edge E. The insert a20 has a double-layer structure in which a hard sintered body layer a21 formed of a hard sintered body and provided with a cutting edge E and a cemented carbide layer a22 formed of cemented carbide and provided on the joint surface side are joined.

In the insert a20, after the double-layered rectangular parallelepiped insert body is joined to the back surface and the bottom surface of the seat of the main body a10, a curved cutting edge E can be formed by electric discharge machining, laser machining, grinding machining by a diamond wheel or the like, so that the rake angle and the relief angle are constant at any position in the axial direction. Here, the relief angle is 8 °, and the rake angle is 10 °, but is not particularly limited. The relief angle of one end (the tip side of the rotary cutting tool A1) of the insert may be set to 15 °, the rake angle may be set to 5 °, and the relief angle of the other end (the shank side) may be set to 5 ° and the rake angle may be set to 15 °. The cutting edge E can be manufactured simply as compared to forming it first and then bonding it to the back surface of the seat. Furthermore, the method of forming the cutting edge E first is not excluded.

The rotary cutting tool A1 of the present modified form reduces cutting resistance by increasing the helix angle of the insert a20, and improves sharpness and accuracy of the machined surface. In particular, by forming the rake surface of the cutting edge E with a curved surface, the rake angle of the cutting edge E can be set to an appropriate value, and thus the accuracy of the machined surface can be further improved. Since the chips are led out in the rear end direction by the grooves a10a formed to have a positive helix angle, the chips are excellent in the chip discharge performance as compared with the case where the grooves are also formed to have a negative helix angle.

Description of the reference numerals

1. 5, 7, a 1; rotary cutting tools (prior art); 10. 30, 50, 70, 80, a 10..a subject; 10a, 50a, a10 a..grooves; 11. 31, 51, a 11..blade; 111. 311, 511, 711, 811; a112. the seat; 12. 32, 52, a 12..transition; 13. 33, 53, a 13..handle; a30. bottom edge blade; a40. front end peripheral edge blade; 20. 40, 60, 90, 91, 92, a 20..blade; joint surface; inner side; 21. 41, 61, a 21..a hard sintered body layer; 22. 42, 62, a22.

Claims

1. A rotary cutting tool, comprising a rotary cutting tool,

the rotary cutting tool has: a cutting insert, at least a cutting edge that is a ridge line between a rake face and a flank face, is formed of a hard sintered body containing diamond and/or cubic boron nitride; and a body, the blade being coupled to a seat of the body,

the rotary cutting tool is characterized in that,

the back surface of the seat is a plane and is inclined relative to the axis of the rotary cutting tool, the front tool surface and the rear tool surface are curved surfaces,

within the effective range of the cutting edge, the difference between the maximum value and the minimum value of the helix angle of the rotary cutting tool and the relief angle and the rake angle, as viewed from a section perpendicular to the axis, is 10 DEG or less,

when a plane perpendicular to the back surface of the seat and including the axial center is viewed in the vertical direction, one of both ends of the back surface of the seat with respect to the axial center direction is located forward of the axial center in the rotational direction of the rotary cutting tool, and the other end is located rearward of the axial center in the rotational direction of the rotary cutting tool.

2. The rotary cutting tool according to claim 1, wherein,

the difference between the maximum and minimum of each of the helix angle, the relief angle, and the rake angle is 0 °.

3. The rotary cutting tool according to claim 1 or 2, wherein,

the length of the blade in the radial direction is shorter at both ends than in the middle.

4. The rotary cutting tool according to any one of claims 1 to 3, wherein,

the insert is composed of a laminate of a hard sintered body layer composed of a hard sintered body and a cemented carbide layer made of cemented carbide forming a joint surface to be joined to the back surface of the holder,

at the front end in the rotation direction, the axial center side of the rake face is the cemented carbide layer.