JP5964794B2 - Cutting tools - Google Patents

Description

  The present invention relates to a cutting tool that is attached to a rotary spindle of a cutting machine and removes material from a workpiece mainly made of a highly brittle material such as glass or ceramics while rotating a cutting blade. In particular, the present invention relates to a cutting tool having an equilateral triangular outer shape on a cutting surface of a cutting site provided on the tip side.

  When cutting a workpiece, the shape of the cutting tool used varies depending on the desired shape. For example, in a cutting machine that performs drilling such as a drilling machine, a drill having a spiral cutting edge is used. 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 highly brittle materials such as ceramics and glass, a cutting tool with a diamond cutting edge is advantageous, but when cutting into such a highly brittle material, the work material is hard. The life of the steel was short, and high-precision machining over a long period was difficult.

  In Patent Document 1, an outer peripheral blade is formed at a corner portion of a tip portion having a polygonal cross section of a tool body, and chips (cutting powder) are discharged between adjacent corner portions on the tip surface of the tool body. A cutting tool is disclosed, in which a recess is formed, and a bottom blade is formed on a ridge line of a protrusion having corners partitioned by the recess. According to the cutting tool of the invention of Patent Document 1, the tip end portion of the tool body has a polygonal cross-sectional shape, the outer peripheral blade is formed at the corner portion, and the recessed groove formed between the corner portions of the tip end surface. Since the bottom blade is formed on the ridge line of the convex part with the corners partitioned by, the tip surface is the flank, and the cutting to the cutting material by the outer peripheral blade during cutting is relatively shallow, and cutting by the bottom blade is high. It is said that high-precision finishing can be performed with high precision, and the rigidity and strength of the outer peripheral edge and bottom edge are high, so that the cutting edge can be prevented from being broken and worn, resulting in a long life. In the invention of Patent Document 1, the tip of the tool body is preferably a polygon having four or more corners.

JP 2012-236242 A

  However, when processing highly brittle materials such as ceramics and glass, the chips at the time of processing become fine powder, and the cutting tool entrains the chips, and a load is applied between the work material and the work material. There is a concern that fine chips and cracks (so-called chipping) occur in any of the cutting tools.

  In addition, if a highly brittle material is processed as a work material using a conventional cutting tool whose cutting edge is made of diamond, cracks are generated on the surface of the work piece, forming innumerable recesses, There is a concern that the surface roughness will deteriorate. In addition, the side surface of the workpiece may have a chipped shape due to chipping caused by fine powdery chips generated during cutting.

  In addition, the higher the machining shape accuracy required in cutting, the higher the accuracy required for the outer peripheral shape 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-accuracy cutting tool for processing a highly brittle material suitable for fine processing that is rotated and used, which further improves the processing accuracy of the cutting surface of the workpiece, The main object of the present invention is to provide an improved cutting tool for processing a highly brittle material that can be used for a longer time. Some of the advantages of the cutting tool for machining highly brittle materials of the present invention will be specifically described each time in the description of the preferred embodiment.

  In order to solve the above problems, the cutting tool according to claim 1 includes a cutting part (10) provided on the front end side and a shank (20) provided on the rear end side and holding the cutting part. A cutting tool (1) used for processing a highly brittle material, wherein the cutting part (10) has an outer peripheral shape of an equilateral triangle and three side peripheral blades (P) formed at the apex (P) of the triangle ( 10B), three tip face cutting edges (2B) formed by a flat face of an equilateral triangle shape from each vertex (P) of the regular triangle toward the central axis (O) on the tip face, and the tip face cutting edge Three inclined portions (2C) having an isosceles trapezoidal shape toward the central axis (O) with one side positioned on the central axis side of the regular triangle of the part (2B) as an upper base, and three inclined portions (2C ) In the plane part (2D) formed by the lower base line of the trapezoid located on the central axis (O) side When, characterized by comprising in.

In the cutting tool according to claim 2, when the cutting tool (1) rotates around the central axis (O), the cutting sites (10) are spaced at intervals of 120 degrees radially about the central axis (O). The outer diameter of the circle of the orbit made by each apex (P) of the equilateral triangle having a cross-sectional outer peripheral shape (10C) of D is D, and the triangle height of the tip face cutting edge (2B) is 0.05D to 0.2D. It is characterized by becoming.

  The cutting tool according to claim 3 is characterized in that relief portions (2E) are provided on both leg portions of the isosceles trapezoidal shape of the inclined portion (2C).

  The cutting tool according to claim 4 is characterized in that the cutting part (10) is formed of polycrystalline sintered diamond.

The cutting tool used for processing the highly brittle material according to claim 1 is formed such that the outer peripheral shape is an equilateral triangle and is formed from each vertex of the equilateral triangle toward the central axis of the cutting tool on the tip surface of the cutting portion and is not coupled to each other. Since the regular triangular cutting edges of the equilateral triangle shape are formed in an evenly distributed shape, the strength of the cutting part can be secured, the wear can be made uniform, and a highly brittle material can be cut as a workpiece. In this case, the effect of minimizing the contact of the high-hardness blade and suppressing the occurrence of cracks and cracks on the surface of the workpiece is obtained.
In addition, since the cutting edge portion of the distal end surface is not connected to each other by the inclined portion and the flat portion, the region where the cutting blade does not contact the workpiece on the cutting surface is relatively wide, and the frictional resistance is further reduced. As well as being able to escape chips more efficiently, the amount of wear can be reduced.

When the cutting tool according to claim 2 is rotated around the central axis of the cutting tool, each of the equilateral triangles that are radially spaced 120 degrees around the central axis and have a cross-sectional outer peripheral shape of the cutting site. The outer diameter of the circle of the orbit formed by the apex is D, the triangle height of the tip face cutting blade is 0.05D to 0.2D, and the area of the tip face cutting blade is reduced, thereby improving chip burnability. Can be planned. In particular, the cutting tool of the present invention uses a horizontal wire electric discharge machine that stretches a wire electrode in the horizontal direction to cut a workpiece, and wire the outer periphery and cutting edge of the cutting site by rotation and angle indexing. Since it can be manufactured by cutting, it can be manufactured more easily even though it is a precise cutting tool suitable for fine processing made of a high-hardness material. In particular, the cutting tool of the present invention has higher roundness and smaller shape errors of the three cutting edges. Therefore, the machining shape accuracy and the machining speed are improved.

  In the cutting tool according to the third aspect, the escape portions are provided on both legs of the isosceles trapezoidal shape of the inclined portion. This escape section discharges chips more actively, so that chipping with high hardness such as fine glass powder or ceramic powder remains between the cutting edge of the tip surface and the work material is suppressed. Can do.

  In the cutting tool according to the fourth aspect, since the cutting site is formed of polycrystalline sintered diamond, high-precision processing of highly brittle materials such as ceramics and glass can be expected. Also, application to non-ferrous high hardness steel materials such as cemented carbide can be expected.

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. Since the cutting tool 1 is provided with the cutting surface 10A and the side outer peripheral blade 10B, it has a layer of polycrystalline sintered diamond over the entire surface including at least the cutting surface 10A and the side outer peripheral blade 10B of the cutting site 10. . Parts other than the polycrystalline sintered diamond layer of the cutting part 10 are made of cemented carbide.

  The shank 20 is formed of a cylindrical cemented carbide. The shank 20 holds the cutting site 10 directly or indirectly. 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 outer peripheral shape of the cutting part 10 is a regular triangular prism. 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 triangle. Therefore, the cutting tool 1 according to the embodiment has an advantage that the balance of the cutting amounts of the three cutting edges 2 can be obtained relatively easily.

  The side outer peripheral blade 10B is provided at each vertex P of the equilateral triangle of the outer periphery 10C of the cutting site 10. Therefore, the cutting tool 1 has the three cutting edges 2 as well as the number of apexes P of the regular triangle on the outer periphery 10C.

  Each of the three cutting edges 2 forms a front end face cutting portion 2B having the same shape as a regular triangle with each vertex P of the regular triangle on the outer periphery 10C of the cutting portion 10 as one vertex.

  The inclined portion 2C is formed as a trapezoid-shaped inclined portion with one side of the center axis side of the regular triangle of the front end face cutting edge portion 2B as an upper base, and the three cutting edges 2 are equal to each other due to standard friction. It is necessary to maintain the cutting ability continuously for a longer period of time due to excessive wear. Further, since the inclined portion 2C does not come into contact with the machining surface, it plays a role of releasing cutting powder entering between the inclined portion 2C and the machining surface.

  The flat portion 2D is formed by the lower base line of the inclined portion 2C that forms the trapezoidal shape of the three cutting edges 2. Since the flat surface portion 2D does not come into contact with the processing surface, it plays a role of escaping the cutting powder entering between the processing surface.

  The escape portion 2E is provided on both leg portions of the inclined portion 2C having an isosceles trapezoidal shape, and plays a role of further releasing chips that enter between the inclined portion 2C and the processing surface.

  The three cutting edges 2 are dissipated in the same shape at each vertex P in a state where the cutting edges 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 evenly arranged at the same interval (120 °) radially about the central axis O on the cutting surface 10A. In the cutting tool 1, the cutting edges 2 are arranged in the same shape, so that the frictional resistance is relatively small, and the chips are efficiently released through the space where the cutting edge 2 and the workpiece do not contact. As a result, the cutting tool 1 can reduce the amount of wear.

  Moreover, in the cutting tool 1 of embodiment, since the cutting blade 2 is arrange | positioned at each vertex P of an equilateral triangle, there exists an advantage which is easy to process the cutting blade 2 comparatively easily and uniformly with high precision. And when the cutting tool 1 rotates, the roundness of the track 10D formed by the cutting edges P of the three cutting edges 2 can be made higher, so that the apparent runout is kept 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 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 of the shank 20 is obtained.

  Next, the material 3 formed into a stepped columnar shape is once removed from the main shaft, and the part having a large stepped outer diameter is cut in a later step so that the outer shape becomes an equilateral triangle. 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. 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 D of the track 10D formed by the cutting 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 stretched horizontally are moved relative to each other in the horizontal direction X and the vertical direction Z. To cut the surface of the polycrystalline sintered diamond layer 3A at a portion having a large stepped outer diameter into an equilateral triangle. Since the cutting tool 1 of the embodiment has an equilateral triangle shape on the outer periphery 10C, each surface is cut out while calculating the rotation angle of the main shaft by 120 degrees. In addition, it is good to chamfer each vertex 10B of the equilateral triangle which hits the blade edge | tip P of the cutting blade 2 collectively.

  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 equilateral triangle in 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 the electric discharge machining is performed by relatively moving the wire electrode 4 parallel to the direction 3C, the height of the main shaft is higher than the end of the blade end 2B (2B1) of the cutting blade 21, as shown in FIG. After the inclined portion 2C (2C1) is obtained while gradually changing the angle, 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. After obtaining the surface, the inclined portion 2C (2C2) is obtained while gradually changing the height of the main shaft, and the cutting edge 22 having the flat surface 2B (2B2) is obtained. Further, each time the above machining is completed, the rotation angle of the main shaft is calculated at a rotation angle (60 degrees or 120 degrees) depending on the equilateral triangle of the shape of the outer periphery 10C, and the same as the machining in the direction 3C. Each cutting blade 2 is partially cut out. 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, the three cutting edges 2 can be processed into a diffused and isomorphic shape at once by only wire cutting without breaking the relative positional relationship between the material 3 and the wire electrode 4 once positioned. As a result, it is possible to relatively easily obtain a highly accurate cutting tool having high roundness and small variations in the three cutting edges 2.

  Since the cutting tool 1 shown above is provided with the same shape of the cutting blades 2 from the vertices P of the equilateral triangle of the shape of the outer periphery 10C toward the central axis O in a dissipative shape with the cutting blades 2 not connected, Three precise cutting edges 2 can be simultaneously formed by wire cutting that can cut 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 processing machines for cutting highly brittle materials. 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 highly brittle processing machines.

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 Cutting edge 2A Cutting edge 2B Tip surface cutting edge part 2C Inclined part 2D Plane part 2E Relief part 10 Cutting part 10A Cutting surface 10B Side surface peripheral blade 20 Shank 3 Material 4 Wire electrode

Claims (4)

  A cutting tool used for processing a highly brittle material comprising a cutting part provided on the front end side and a shank provided on the rear end side and holding the cutting part, wherein the cutting part has a cross-sectional outer periphery. Three side surface outer peripheral blades that are formed in equilateral triangles at the apexes of the triangles, and three tip end surfaces that are formed by equilateral triangle flat surfaces from the apexes of the equilateral triangles toward the central axis on the tip surface A cutting blade portion, three inclined portions that form an isosceles trapezoidal shape toward the central axis with one side located on the central axis side of the regular triangle of the tip surface cutting blade portion as an upper base, and the three inclined portions A cutting tool comprising: a flat portion formed by a trapezoidal lower base line located on the center axis side of the cutting tool. When the cutting tool rotates about the central axis, the vertices of the equilateral triangle that form the transverse cross-sectional outer peripheral shape of the cutting portion are formed at intervals of 120 degrees radially around the central axis. The cutting tool according to claim 1, wherein the outer diameter of the circle of the track is D, and the triangular height of the tip face cutting blade is 0.05D to 0.2D.   The cutting tool according to claim 1, wherein relief portions are provided at both leg portions of the isosceles trapezoidal shape of the inclined portion.   The cutting tool according to claim 1, wherein the cutting part is formed of polycrystalline sintered diamond.

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