JP6080304B2 - Cutting tools - Google Patents

Description

  The present invention relates to a cutting tool that is attached to a rotary main shaft of a cutting machine and removes material from a metal workpiece mainly while rotating a cutting blade. In particular, the present invention relates to a cutting tool having a regular polygonal outer shape on a cutting surface of a cutting site provided on the tip side.

  When cutting a metal workpiece, the shape of the cutting tool used varies depending on the desired shape. For example, a drill having a spiral cutting edge is used in a cutting machine that drills holes such as a drilling machine. In addition, in the case of a cutting machine that performs a process of cutting a flat surface such as a chisel or plane in a woodwork, such as a lathe or a planer, a cutting tool having a single blade is basically applied. For example, in the case of a cutting machine that processes a groove or bottomed hole having an arbitrary shape such as a milling machine or a machining center, a milling machine having a plurality of rotary blades is mainly used.

  The material of each cutting tool differs depending on the material of the workpiece to be processed, the cutting direction, and the requirements for the processing result. The cutting tool is basically required to be formed of a material in which the cutting edge has a hardness equal to or higher than that of the workpiece and can reduce the amount of wear. When machining ferrous workpieces, which are typical metals, carbon tool steels, alloy tool steels, and high speeds that have a hardness that exceeds the hardness of the workpiece, corresponding to the hardness of the workpiece Steel-based cutting tools such as tool steel (His) are used.

  In milling, in many cases, a cutting tool is used in which a plurality of cutting blades whose cutting edges are directed in the rotation direction are radially extended from the central axis of a cylindrical cutting portion toward the outer periphery. Then, the workpiece is cut by moving the cutting tool having a plurality of cutting blades relative to the workpiece while rotating at high speed around the central axis. Depending on the material of the workpiece, high-speed tool steel, cemented carbide, polycrystalline cubic silicon nitride (PcBN), polycrystalline sintering A hard material with higher wear resistance, such as diamond (PCD), is selected.

  When cutting non-ferrous high-hardness materials such as cemented carbide, diamond cutting tools are advantageous. However, as the work material, high-hardness steel materials such as superalloys, ceramics, and glass When cutting into such a highly brittle material, the work material is hard, so the life of the cutting edge is short, and high precision machining over a long period of time is difficult.

  The invention of Patent Document 1 discloses a cutting tool in which a number of islands are formed in a layer of polycrystalline sintered diamond formed on the top surface of a cutting tool, and each island is a cutting edge. According to the cutting tool of the invention of Patent Document 1, the processing efficiency is considerably improved by a large number of island-shaped cutting edges, the discharge of cutting powder can be promoted, and the ground surface is also beautiful.

JP 2009-262286 A

  However, conventional cutting tools with diamond cutting edges use grinding action with a number of island-shaped cutting edges formed on the bottom of the cutting tool and negative outer peripheral edges formed on the sides. However, a fine material residue (so-called burrs) was generated on the cut surface.

  In general, negative-shaped cutting edges (hereinafter referred to as negative blades) have high grinding resistance, and a high load acts on the island-shaped cutting edge, which may cause damage to the tool peripheral edge along with the cutting edge in a wide range. was there.

  In addition, the higher the machining shape accuracy required in cutting, the higher the accuracy required for the shape of the outer periphery of the cutting site and the shape of the cutting edge. Precise machining of a large number of minute cutting edges in a cutting part made of a high-hardness material that is difficult to cut, such as diamond, is a very difficult task, and the improvement of workability in the production of this type of cutting tool It is desired.

  In view of the above problems, the present invention is a high-precision cutting tool suitable for fine processing that is rotated and used, further improving the processing accuracy of the cutting surface of the work material and reducing the risk of breakage of the cutting blade. It is a main object to provide an improved cutting tool that can withstand longer use. Some of the advantages of the cutting tool of the present invention are specifically described each time in the description of the preferred embodiment.

In order to solve the above-mentioned problems, the cutting tool according to claim 1 is provided on the front end side and the outer periphery (10C) in the cross section is a regular polygonal cutting part (10), and is provided on the rear end side for cutting. A shank (20) having an outer diameter for holding the portion (10) smaller than the minimum width of the cutting portion (10), wherein the cutting portion (10) is a regular polygon at the tip surface A plurality of tip cutting parts (10A) having the same shape and having a plurality of first cutting edges (2A) that are formed from each vertex (P) toward the central axis (O) of the cutting tool and are not coupled to each other; A second cut having a positive shape at the intersection (P) formed at each of the vertices (P) and having a predetermined twist angle (β) with respect to the central axis (O) and the tip cutting portion (10A). A plurality of isomorphous side cutting parts having a blade (2B) 10B), and the whole of the cutting portion (10) including the second cutting edge (2B) is formed of polycrystalline sintered diamond, and the tip cutting portion (10A) is the central axis (O). the first cutting edge flat face of the depth corresponding to the blade height (2A) possess in a direction parallel to said tip cutting site (10), said central axis (O) of the street the Seita A straight line parallel to the flat surface perpendicular to one side of a square is rotated around the central axis (O) by a predetermined rotation angle (δ) in the direction opposite to the rotation direction (R) of the cutting tool, and then the vertex (P The first cutting edge (2A) is formed on a straight line translated in the opposite direction to the rotation direction so as to pass through one of A straight line parallel to the flat surface perpendicular to one side and one side adjacent to the direction opposite to the rotation direction is Point (P) by providing a dissipation isomorphic to the center the center axis (O) of the cutting edge (2) of polygonal shape obtained by forming the trailing edge on a straight line is moved by a predetermined distance parallel to the direction (3C) of It is characterized by.

  In the cutting tool according to claim 2, the first cutting edge (2A) has an inclined surface (2C) inclined at a predetermined angle (α) in the opposite direction to the rotation direction (R) of the cutting tool. Features.

  The cutting tool according to claim 3 is characterized in that the tip cutting portion (10A) is a polygon of a triangle or more with one side of the first cutting edge (2A) on the tip surface.

  In the cutting tool according to the first aspect, the outer shape of the cutting surface is a regular polygon. On the front end surface of the cutting part, a plurality of the same front end cutting parts having a plurality of first cutting edges which are formed from each vertex of the regular polygon toward the central axis of the cutting tool and are not coupled to each other are formed. This tip cutting part has a relatively wide area where the cutting edge does not contact the workpiece on the cutting surface, and the cutting edges are not connected to each other, so that the frictional resistance can be reduced and the frictional heat can be released more efficiently. Therefore, the amount of wear can be reduced.

  Further, a plurality of identical side-surface cuttings formed at each vertex of the side surface and provided with a predetermined twist angle with respect to the central axis and having a positive second cutting edge at the intersection with the tip cutting site The site is formed. The positive-shaped cutting blade generated in this way (hereinafter referred to as a positive blade) can be cut, not ground, and can reduce cutting resistance and improve workability. Can be reduced.

  In the cutting tool concerning Claim 2, the inclined surface which inclines at a predetermined angle in the opposite direction with respect to the rotation direction of the cutting tool is comprised. This inclined surface has a function of escaping cutting powder, and it becomes difficult to bite between the processed surface of the workpiece and the occurrence of chipping is suppressed.

  In the cutting tool according to the third aspect, since the first cutting edge is a polygon of a triangle or more with one side, the outer periphery and the cutting edge of the cutting site can be formed by wire cutting in particular. Therefore, a precise cutting tool suitable for micromachining made of a high hardness material can be manufactured more easily. In particular, the cutting tool of the present invention has higher roundness and smaller shape errors of the plurality of cutting blades. Therefore, the machining shape accuracy and the machining speed are improved.

It is the top view which looked at the cutting tool of this invention from the front end side. It is a side view of the cutting tool of the present invention. It is the perspective view which looked at the cutting tool of this invention from the front end side. It is a schematic diagram which shows the process which processes the cutting tool of this invention by a wire cut. It is a schematic diagram which shows the process which processes the cutting blade of the cutting tool of this invention by a wire cut.

  1 and 2 show a cutting tool according to a preferred embodiment of the present invention. FIG. 3 shows the cutting blade of the cutting tool of the embodiment shown in FIGS. 1 and 2. In the present invention, the center line in the longitudinal direction of the cutting tool is used as the central axis, the side provided with the cutting blade and used for processing is the front end side, and the side attached to the cutting machine is the rear end side. And the front end surface of a cutting tool is called a top surface, and let the surface orthogonal to a top surface be a side surface. Further, the same surface as the top surface at the cutting site is called a cutting surface.

  The cutting tool 1 is attached to a rotating spindle (spindle) of a numerically controlled cutting machine such as a milling machine or a machining center. The cutting tool 1 mainly includes a cutting site 10 and a shank 20. The cutting part 10 is provided on the tip side of the cutting tool 1. The shank 20 is provided on the rear end side of the cutting tool 1. In the cutting tool 1 of the embodiment, the cutting site 10 and the shank 20 are integrally formed.

  The cutting part 10 is formed of polycrystalline sintered diamond. In the cutting tool 1, since the cutting edge 2 is provided along the cutting surface 10A and the side surface 10B, the polycrystalline sintered diamond layer is formed over the entire surface including at least the cutting surface 10A and the side surface 10B of the cutting site 10. Have Therefore, the cutting edge 2 is formed of polycrystalline sintered diamond. Parts other than the polycrystalline sintered diamond layer of the cutting part 10 are made of cemented carbide.

  The shank 20 is made of a cemented carbide. The shank 20 holds the cutting site 10 directly or indirectly. The shank 20 has a cylindrical shape. The outer diameter d of the shank 20 is smaller than the minimum width w of the cutting site 10. The shank 20 is a part on the rear end side of the cutting tool 1 that is fastened to the rotation main shaft of the cutting machine or a chuck of a tool holder attached to the rotation main shaft. The cutting tool 1 can be attached to the rotating spindle by fastening the shank 20 to the chuck.

  The shape of the cutting part 10 is a regular polygonal column. Therefore, the shape of the outer periphery 10 </ b> C in the cross section of the cutting part 10, simply speaking, the outer shape of the cutting surface 10 </ b> A of the cutting part 10 is a regular polygon. Specifically, in the cutting tool 1 of the embodiment, the outer shape of the cutting surface 10A is a regular hexagon. Therefore, the cutting tool 1 according to the embodiment has an advantage that the balance of the cutting amounts of the plurality of cutting blades 2 can be obtained relatively easily.

  The cutting blade 2 is provided at each vertex P of the regular polygon of the outer periphery 10C of the cutting site 10. Therefore, the cutting tool 1 is provided at each vertex P of the regular polygon of the outer periphery 10C. Accordingly, the cutting tool 1 has the same number of cutting edges 2 as the same number as the number of apexes P of the regular polygon on the outer periphery 10C. For example, the cutting tool 1 having a regular hexagonal outer shape shown in FIG. The plurality of identically shaped cutting blades 2 have a cutting edge 2 </ b> A in a rotation direction R around the rotation axis O. The cutting edge 2A is provided in a direction (processing feed direction) orthogonal to the rotation axis O. The cutting edge 2 has a cutting edge 2B on the side surface 10B. The cutting edge 2B is provided in a direction (processing depth direction) parallel to the rotation axis. The cutting edge 2B is formed at each vertex P of the side surface 10B, is provided with a predetermined twist angle β with respect to the central axis O, and constitutes a positive-shaped cutting edge at the intersection with the cutting edge 2A.

  Each of the plurality of isomorphous cutting blades 2 has a triangular or more polygonal isomorphic cutting edge portion 2 having a regular polygon apex P on the outer periphery 10C of the cutting portion 10 as a vertex in a direction opposite to the rotation direction. An inclined surface 2C that is inclined at an angle α is formed.

  The inclined surface 2 </ b> C is necessary for the plurality of cutting edges 2 to maintain their cutting ability continuously for a longer period of time due to uniform wear due to standard friction. However, since the inclined surface 2C does not contact the machining surface, the inclined surface 2C plays a role of releasing cutting powder entering between the inclined surface 2C and the machining surface.

  The plurality of cutting blades 2 are provided in a dissipative and isomorphic manner at each vertex P in a state where the cutting blades 2 are not connected to each other around the central axis O. In the present invention, the term “divergence isomorphism” means that the cutting edges 2 are arranged in the cutting surface 10A so as to be evenly distributed radially at the same interval around the central axis O. In the cutting tool 1, the cutting edges 2 are arranged in the same shape to dissipate, so that the frictional resistance is relatively small, and the frictional heat is efficiently released through the space where the wider cutting edge 2 and the workpiece do not contact. . As a result, the cutting tool 1 can reduce the amount of wear.

  It can be said that the greater the number of blades, the greater the cutting amount per rotation of the cutting tool 1. In the cutting tool 1 of the embodiment, the number of cutting edges 2 of the cutting edge 2B is provided by the number of regular polygonal vertices P on the outer periphery 10C of the cutting surface 10A, so that the amount of wear is sufficient while having sufficient cutting efficiency. Have been smaller.

  In the cutting tool 1 according to the embodiment, since the polygonal cutting blade 2 is disposed at each vertex P of the regular polygon, the cutting blade 2 can be relatively easily and uniformly processed with high accuracy. There are advantages. And when the cutting tool 1 rotates, since the roundness of the track | orbit 10D which the blade edge | tip 2B of the some cutting blade 2 makes can be made higher, it cuts in the state by which the apparent core runout was suppressed small. And high machining shape accuracy can be obtained.

  4 and 5 schematically show the process of cutting the cutting edge by wire cutting. FIG. 4 shows the side of the material for producing the cutting tool. FIG. 4 specifically shows a process from forming a cutting tool prototype to a cylindrical material. FIG. 5 shows the leading end surface of the material that hits the top surface of the cutting tool.

  The material 3 is formed of a high hardness conductive material. The material 3 is made of a material that can bond or cover the material of the cutting blade 2 except when the entire cutting tool 1 including the cutting blade 2 is formed of the same material. Specifically, the material 3 is high-speed tool steel or cemented carbide. The cutting edge 2 is formed of a conductive material having high hardness such as polycrystalline sintered diamond. On the other hand, the wire electrode 4 is a wire of φ0.1 mm or less made of a conductive metal or alloy having a high tensile strength such as tungsten or brass.

  As shown in FIG. 4A, the material 3 is mounted on a main shaft of a wire cut electric discharge machine (not shown), and the wire electrode 4 is stretched horizontally. Then, the material 3 and the wire electrode 4 are relatively moved in the horizontal direction X and the vertical direction Z while rotating the main shaft at a predetermined rotation number, and the surface of the material 3 is uniformly removed by electric discharge machining. Further, with the material 3 attached to the main shaft as it is, the surface of the portion corresponding to the shank 20 of the material 3 is uniformly removed until an appropriate outer diameter somewhat larger than the expected outer diameter d of the shank 20 is obtained. .

  Next, the material 3 formed in a stepped columnar shape is once removed from the main shaft, and a part having a large stepped outer diameter is cut in a later step so that the outer shape becomes a regular polygon. A layer 3A of polycrystalline sintered diamond having a required thickness larger than the blade height h of the cutting blade 2 is formed on the surface of the part. Then, the material 3 is remounted on the main shaft, and the wire electrode 4 is stretched horizontally.

  As shown in FIG. 4B, the material 3 and the wire electrode 4 are moved relative to each other in the horizontal direction X and the vertical direction Z while rotating the main shaft at a predetermined rotational speed, and the stepped outer diameter is small by electric discharge machining. Are uniformly removed until the outer diameter d of the shank 20 is reached. Further, with the material 3 attached to the main shaft as it is, the surface of the portion of the material 3 having a large outer diameter is uniformly removed until the diameter 2r of the track 10D formed by the blade edge 2B. Therefore, a stepped cylindrical material 3 having an outer shape with high roundness can be obtained.

  At this time, a layer of polycrystalline sintered diamond having a required thickness is formed on the entire top and side surfaces of the raw columnar material 3 in advance, and then the surface is removed by wire cutting. can do. Further, all of the material 3 or all of the parts corresponding to the cutting part 10 can be formed in advance by polycrystalline sintered diamond. In this case, there is a disadvantage that the material cost becomes higher, but it is not necessary to remove the material 3 from the main shaft in the process of manufacturing the cutting tool 1, so that there is an advantage that the burden on the work is further reduced.

  As shown in FIG. 4C, the main shaft is rotated by indexing the rotation angle by a predetermined angle, and the material 3 and the wire electrode 4 inclined by the angle β with respect to the horizontal axis are moved relative to each other in the horizontal direction X and the vertical direction Z. Then, the surface of the polycrystalline sintered diamond layer 3A is cut into a regular polygon at a portion having a large stepped outer diameter by electric discharge machining. Since the cutting tool 1 of the embodiment has a regular hexagonal shape on the outer periphery 10C, each surface is cut out while calculating the rotation angle of the main shaft by 60 degrees. In addition, it is good to chamfer each vertex 3B of the regular polygon which hits the blade edge 2B of the cutting blade 2 together.

  As shown in FIG. 5, the wire electrode 4 that is horizontally stretched while the material 3 is attached to the main shaft is disposed to face the front end surface of the material 3. The front end surface of the material 3 becomes the cutting surface 10 </ b> A of the cutting tool 1. The reference position for indexing the rotation angle is set to a position where the wire electrode 4 located at the origin extending horizontally and one side of the regular polygon of the shape of the outer periphery 10C are parallel to each other. Then, the wire electrode 4 is moved relative to the material 3 in parallel while being kept horizontal, and the cutting blade 2 is partially cut out by electric discharge machining.

  For example, when electric discharge machining is performed by relatively moving the wire electrode 4 parallel to the direction 3C, the height of the spindle is gradually gradually changed from the edge of the cutting edge 21 as shown in FIG. However, after obtaining the blade height, the wire electrode 4 is relatively moved in the 3C direction to obtain a flat surface as a region Σ1 to be subjected to electric discharge machining by wire cutting. Thereafter, as shown in FIG. 5 (B), the rotation angle of the main shaft is calculated at the rotation angle δ, and the flatness of Σ2 is obtained by the relative movement of the height of the main shaft and the relative movement of the wire electrode in the 3C direction. Get a plane. Further, each time the above machining is completed, the rotation angle of the main shaft is calculated at a rotation angle depending on the regular polygon of the shape of the outer periphery 10C, and each cutting edge 2 is moved in the same manner as the machining in the direction 3C. Cut out partially. In the cutting tool 1 of the embodiment, since the shape of the outer periphery 10C is a regular hexagon, the indexing angle is 60 degrees. In this way, the rotation angle is indexed sequentially and machining is performed in a fixed direction, and when the main shaft is rotated 360 degrees per revolution, the required number of the same shape cutting blades 2 are cut into a divergent shape.

  Basically, a plurality of cutting blades 2 can be processed into a diffused and isomorphic shape at once by only wire cutting without destroying the relative positional relationship between the material 3 and the wire electrode 4 once positioned. As a result, a highly accurate cutting tool having a high roundness and a small variation among the plurality of cutting blades 2 can be obtained relatively easily.

  In the cutting tool 1 shown above, a plurality of identically shaped cutting blades 2 are provided in a dissipative shape in a state where the respective cutting blades 2 are not connected from each vertex P of the regular polygon of the shape of the outer periphery 10C toward the central axis O. Therefore, a plurality of precise cutting blades 2 can be simultaneously formed by wire cutting capable of cutting the material 3 that is difficult to cut with high accuracy. As a result, workability is improved in manufacturing the cutting tool 1, and the work load is reduced.

  The cutting tool of the present invention should not be limited to the cutting tool of the embodiment described in detail. Although some examples have already been given, the cutting tool of the embodiment can be modified or applied without departing from the technical idea of the present invention.

  The present invention is used in the technical field of metal working machines for cutting metal. In the cutting tool of the present invention, the cutting edge is made of a high-hardness material, and is excellent in wear resistance. Further, the cutting tool is easier to manufacture, the work load is reduced, and the processing shape accuracy and processing speed are excellent. The present invention contributes to the development of the technical field of metal working machines.

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 Cutting edge 2A Cutting edge 2B Cutting edge 2C Inclined surface 2D Relief part 2E Remaining peripheral part 10 Cutting part 10A Cutting surface 10B Side face 10C Outer periphery 20 Shank 3 Material 4 Wire electrode

Claims (3)

A cutting part having a regular polygonal shape on the outer periphery in the cross section provided on the tip side,
A shank provided on the rear end side and holding the cutting portion, the outer diameter being smaller than the minimum width of the cutting portion;
A cutting tool comprising:
A plurality of identical tip cutting sites having a plurality of first cutting edges that are formed from each vertex of the regular polygon toward the central axis of the cutting tool on the tip surface and are not coupled to each other;
A plurality of isomorphous side cutting parts formed at each vertex of the side surface and having a predetermined twist angle with respect to the central axis and having a positive second cutting edge at the intersection with the tip cutting part And
All of the cutting part including the second cutting edge is formed of polycrystalline sintered diamond, and the cutting edge of the first cutting edge is in a direction parallel to the central axis. have a flat surface having a depth corresponding to the height,
The tip cutting part rotates a straight line parallel to the flat surface passing through the central axis and orthogonal to one side of the regular polygon at a predetermined rotation angle around the central axis in a direction opposite to the rotation direction of the cutting tool. Forming the first cutting edge on a straight line translated in a direction opposite to the rotation direction so as to pass through one of the vertices;
A trailing edge on a straight line that is parallel to the flat surface that is orthogonal to the one side of the regular polygon that passes through the central axis and that is adjacent to the side opposite to the rotation direction, by a predetermined distance in the direction of the vertex. A cutting tool characterized in that a polygonal cutting blade is formed in a diffused shape with the central axis as a center .   The cutting tool according to claim 1, wherein the first cutting edge has an inclined surface inclined at a predetermined angle in a direction opposite to a rotation direction of the cutting tool.   2. The cutting tool according to claim 1, wherein the tip cutting portion is a polygon of a triangle or more with one side of the first cutting edge on the tip surface.

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