Cutting tool
By optimizing the thickness and radius of curvature of the diamond layer in the cutting tool, and forming a structural cutting tip through laser processing and ion etching, the problems of wear resistance and sharpness of the cutting edge are solved, thus improving the tool's service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUMITOMO ELECTRIC HARDMETAL CORP
- Filing Date
- 2023-11-29
- Publication Date
- 2026-05-12
AI Technical Summary
When the cutting edge of a cutting tool is covered with a diamond layer, as the thickness of the diamond layer increases, the tool's wear resistance improves, but the sharpness of the cutting edge decreases, and chip aggregation is more likely to occur, leading to a reduction in tool life.
Design a cutting tool with a diamond-coated back face thickness of 10 μm or more and 25 μm or less, a cutting edge radius of curvature less than the back face thickness multiplied by 0.3, a rake face with a maximum height roughness of less than 2 μm in the first part, and a structural cutting tip formed by laser processing and ion etching to enhance the strength and sharpness of the cutting edge.
It effectively inhibits chip adhesion, improves tool wear resistance and cutting edge sharpness, and extends tool life.
Smart Images
Figure CN122028995A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to cutting tools. Background Technology
[0002] Japanese Patent Application Publication No. 2015-085462 (Patent Document 1) discloses a hard-film coated cutting tool in which a diamond film is coated onto a tool body having a cutting edge formed at the intersection of the flank and rake faces. In this hard-film coated cutting tool, the thickness of the diamond film on the flank face side is 8 μm or more and 30 μm or less. The radius of the arc approximating the fillet of the cutting edge tip is 0.1 times or more and 0.8 times the thickness of the diamond film on the flank face side.
[0003] Existing technical documents Patent documents Patent document 1: Japanese Patent Application Publication No. 2015-085462. Summary of the Invention
[0004] The cutting tool disclosed herein is a cutting tool having a substrate and a diamond layer covering the substrate. The cutting tool has a rake face and a flank face. The flank face is connected to the rake face. The edges of the rake face and the flank face constitute a cutting edge. The diamond layer has a flank cover portion. The flank cover portion constitutes the flank face. The thickness of the flank cover portion is 10 μm or more and 25 μm or less. In a cross-section perpendicular to the tangent of the cutting edge, the radius of curvature of the cutting edge is less than the value obtained by multiplying the thickness of the flank cover portion by 0.3. The rake face includes a first portion. The first portion is formed by the flank cover portion. The first portion is connected to the flank face. The maximum height roughness of the first portion is less than 2 μm. Attached Figure Description
[0005] Figure 1 This is a top view schematic diagram showing the cutting tool involved in the first embodiment.
[0006] Figure 2 It means Figure 1 An enlarged top view of region II.
[0007] Figure 3 This is an enlarged side view schematic diagram showing the structure of the cutting tool according to the first embodiment.
[0008] Figure 4 It is along Figure 2 A cross-sectional view of line IV-IV.
[0009] Figure 5 It means Figure 4 A magnified cross-sectional view of region V.
[0010] Figure 6 This is a flowchart that summarizes the manufacturing method of the cutting tool according to the first embodiment.
[0011] Figure 7 This is a cross-sectional schematic diagram showing the process of sharpening the cutting edge by laser processing the rake face.
[0012] Figure 8 This is a cross-sectional schematic diagram showing the structure of the cutting tool according to the second embodiment.
[0013] Figure 9 This is a cross-sectional schematic diagram showing the process of sharpening the cutting edge by laser processing the rake face in the manufacturing method of the cutting tool according to the second embodiment.
[0014] Figure 10 This is a partial cross-sectional schematic diagram showing the usage state of the cutting tool involved in this disclosure. Detailed Implementation
[0015] [The problem this disclosure aims to solve] When the cutting edge of a cutting tool is covered with a diamond layer, the tool's wear resistance increases with the thickness of the diamond layer. The sharpness of the cutting edge increases with the decrease in the radius of curvature of the cutting edge. This helps to suppress damage to the cutting tool. However, even with a thick diamond layer and a small radius of curvature of the cutting edge, chip adhesion can sometimes occur at the cutting edge due to the surface condition of the diamond layer. This can lead to the formation of a structural tool tip, making tool damage more likely to occur. As described above, it is difficult to improve tool life in cutting tools with diamond layers.
[0016] The purpose of this disclosure is to provide a cutting tool that can improve tool life.
[0017] [The Effects of This Disclosure] According to this disclosure, it is possible to provide a cutting tool that can improve tool life.
[0018] [Summary of Implementation Methods] First, a summary of the embodiments of this disclosure will be described.
[0019] (1) The cutting tool disclosed herein is a cutting tool having a substrate and a diamond layer covering the substrate. The cutting tool has a rake face and a flank face. The flank face is connected to the rake face. The edges of the rake face and the flank face constitute a cutting edge. The diamond layer has a flank cover portion. The flank cover portion constitutes the flank face. The thickness of the flank cover portion is 10 μm or more and 25 μm or less. In a cross section perpendicular to the tangent of the cutting edge, the radius of curvature of the cutting edge is less than the value obtained by multiplying the thickness of the flank cover portion by 0.3. The rake face has a first portion. The first portion is constituted by the flank cover portion. The first portion is connected to the flank face. The maximum height roughness of the first portion is less than 2 μm.
[0020] According to the cutting tool disclosed herein, it is possible to suppress the excessive protrusion of a portion of the first part. Therefore, it is possible to suppress the accumulation of chips originating from the excessively protruding portion. As a result, tool life can be improved.
[0021] (2) According to the cutting tool mentioned in (1) above, the rake face may have a first rake face and a second rake face. Alternatively, the first rake face may be separate from the flank face. Alternatively, the second rake face may be located between the first rake face and the flank face. Alternatively, the second rake face may be connected to both the first rake face and the flank face. Alternatively, the second rake face may be inclined relative to the first rake face in a direction from the first rake face toward the flank face. This increases the angle between the rake face and the flank face, thereby improving the strength of the cutting edge.
[0022] (3) According to the cutting tool mentioned in (2) above, the inclination angle of the second rake face relative to the first rake face may be 3° or more and 50° or less. By making the inclination angle of the second rake face 3° or more, it is possible to suppress the excessive reduction of the cutting edge strength. By making the second angle θ2 50° or less, it is possible to suppress the excessive reduction of the cutting edge sharpness.
[0023] (4) According to the cutting tool mentioned in (2) above, the thickness of the back blade cover can be 15 μm or more and 20 μm or less. This can improve the wear resistance of the cutting tool.
[0024] (5) According to any of (1) to (4) above, the cutting tool may also have a radius of curvature of the cutting edge that is less than the thickness of the back cover multiplied by 0.1 in a section perpendicular to the tangent of the cutting edge. This can improve the sharpness of the cutting edge.
[0025] (6) The cutting tool according to any one of (1) to (5) above may also have a substrate made of cemented carbide containing tungsten carbide particles. Alternatively, the average particle size of the tungsten carbide particles may be 2 μm or less. This suppresses the peeling of the diamond layer from the substrate. As a result, tool life can be further improved.
[0026] (7) The cutting tool involved in any of (1) to (6) above may also have a clearance angle of 15° or more and 35° or less on the flank face.
[0027] (8) The cutting tool involved in any of (1) to (7) above may also be such that the maximum height roughness of the first part is less than 1.5 μm.
[0028] [Details of the implementation method] Hereinafter, the embodiments of the present disclosure (hereinafter also referred to as the present embodiments) will be described in detail based on the accompanying drawings. It should be noted that the same or equivalent parts will be labeled with the same reference numerals in the following drawings, and their descriptions will not be repeated.
[0029] (First Implementation) <Structure of Cutting Tools> First, the structure of the cutting tool involved in the first embodiment will be described.
[0030] Figure 1 This is a top view schematic diagram showing the cutting tool according to the first embodiment. The cutting tool 100 according to the first embodiment has a front end portion 6, a main body portion 7, and a shank portion 8. The cutting tool 100 is, for example, a ball end mill. The cutting tool 100 is, for example, a rotary cutting tool that rotates about the axis X.
[0031] Figure 2 It means Figure 1 An enlarged top view of region II. Figure 3 This is an enlarged side view schematic diagram showing the structure of the cutting tool 100 according to the first embodiment. Figure 3 The enlarged side view diagram shown is along... Figure 2 A magnified side view diagram when observing arrow A.
[0032] like Figure 2 as well as Figure 3 As shown, the cutting tool 100 has a rake face 1 and a flank face 2. The rake face 1 is connected to the flank face 2. The edges of the rake face 1 and the flank face 2 form the cutting edge 3. Figure 2 As shown, when viewed perpendicular to the rake face 1, the tangent of the cutting edge 3 is the first imaginary straight line 91.
[0033] Figure 4It is along Figure 2 A cross-sectional view of line IV-IV. Figure 4 The cross section shown is perpendicular to the first imaginary straight line 91 (refer to...). Figure 2 A vertical cross-section. For example... Figure 4 As shown, the cutting tool 100 has a substrate 4 and a diamond layer 5.
[0034] The substrate 4 has a first surface 41 and a second surface 42. The first surface 41, for example, forms part of the rake face 1. The second surface 42 is connected to the first surface 41. The second surface 42 is substantially parallel to the flank face 2.
[0035] The diamond layer 5 covers at least a portion of the substrate 4. Specifically, the diamond layer 5 covers the second face 42. The diamond layer 5 constitutes the flank face 2. The portion of the diamond layer 5 constituting the flank face 2 is formed as the flank face covering portion 52. The first face 41 is exposed, for example, from the diamond layer 5.
[0036] Diamond layer 5 may contain diamond crystals, for example. Diamond layer 5 may be composed of polycrystalline diamond, for example. Diamond layer 5 may also contain components other than diamond (e.g., amorphous components). Diamond layer 5 may also not contain diamond crystals. Diamond layer 5 may be composed of DLC (Diamond Like Carbon), for example.
[0037] The rake face 1 is, for example, planar. The rake face 1 is composed of a flank cover portion 52 and a base material 4. The portion of the rake face 1 formed by the flank cover portion 52 is a first portion 16. The first portion 16 is connected to the flank face 2. From another viewpoint, the first portion 16 and the edge of the flank face 2 form the cutting edge 3. The portion of the rake face 1 formed by the base material 4 is a second portion 17. In other words, the rake face 1 has a first portion 16 and a second portion 17. The second portion 17 is substantially parallel to the first portion 16.
[0038] The thickness H of the rear blade covering portion 52 is 10 μm or more and 25 μm or less. Thickness H is the thickness of the rear blade covering portion 52 in the direction perpendicular to the rear blade surface 2. For example, thickness H can be 15 μm or more and 20 μm or less, or 15 μm or more and 17 μm or less. For example, thickness H can be 12 μm or more, or 14 μm or more. For example, thickness H can be 22 μm or less, or 18 μm or less.
[0039] Maximum height roughness As an indicator for quantifying surface roughness, there is a maximum height roughness (hereinafter also referred to as maximum height roughness Rz or Rz) specified as Rz. Maximum height roughness Rz is a surface property parameter specified in JIS (Japanese Industrial Standards) B0601:2013.
[0040] The Rz of the first part 16 is less than 2 μm. The Rz of the first part 16 can be, for example, less than 1.8 μm, less than 1.5 μm, or less than 1.2 μm. The Rz can be, for example, greater than 0.01 μm or greater than 0.5 μm.
[0041] Rz is measured, for example, using a laser microscope ("OPTELICS HYBRID" (trademark) manufactured by Lasertech). For example, five measurement regions are set at different locations within the first part 16. Each of the five measurement regions is a linear region. The location of each of the five measurement regions is arbitrary within the first part 16. The average of the Rz measured in each of the five measurement regions is the Rz of the first part 16. In other words, the sum of the Rz values of the five measurement regions divided by 5 is taken as the Rz of the first part 16. The measurement interval is, for example, 0.1 μm. The measurement range is, for example, 10 μm.
[0042] <Radius of curvature and second tilt angle> Figure 5 It means Figure 4 A magnified cross-sectional view of region V. (See diagram below.) Figure 5 As shown, in a cross-section perpendicular to the first imaginary straight line 91, the shape of the cutting edge 3 can also be substantially arc-shaped. In a cross-section perpendicular to the first imaginary straight line 91, the radius of curvature R of the cutting edge 3 is smaller than the thickness H of the flank cover portion 52 (refer to...). Figure 4 The value obtained by multiplying the thickness H by 0.3. The radius of curvature R can be, for example, less than the value obtained by multiplying the thickness H by 0.2, less than the value obtained by multiplying the thickness H by 0.1, or less than the value obtained by multiplying the thickness H by 0.08. The radius of curvature R can be, for example, greater than the value obtained by multiplying the thickness H by 0.001. The radius of curvature R is, for example, greater than 0.5 μm and less than 7 μm.
[0043] like Figure 4 as well as Figure 5As shown, in a cross-section perpendicular to the first imaginary line 91, the line perpendicular to the rake face 1 and tangent to the cutting edge 3 is the second imaginary line 92. In a cross-section perpendicular to the first imaginary line 91, the flank face 2 is inclined relative to the second imaginary line 92 in the direction from the cutting edge 3 toward the rake face 1. From another viewpoint, the flank face 2 is inclined relative to the second imaginary line 92 in the direction from the front end 58 toward the rear end 59. In a cross-section perpendicular to the first imaginary line 91, the inclination angle (first angle θ1) of the flank face 2 relative to the second imaginary line 92 is, for example, 15° or more and 35° or less. The first angle θ1 can be, for example, 17° or more or 19° or more. The first angle θ1 can be, for example, 33° or less or 30° or less. The first angle θ1 is the clearance angle of the flank face 2.
[0044] The radius of curvature R and the first angle θ1 are measured, for example, using the "PF-60" non-contact surface property measuring device manufactured by Mitsubishi Optical Equipment. For example, measurement areas are set at five different locations on the rake face 1 and the flank face 2. The measurement areas at the five locations are respectively along the tangent to the cutting edge 3 (the first imaginary straight line 91, referencing...). Figure 2 This is essentially a linear region that extends vertically and intersects the cutting edge 3. The measurement areas for each of the five locations are arbitrary positions within the first part 16. The measurement spacing is, for example, 0.1 μm. The measurement range is, for example, 200 μm.
[0045] In each of the five measurement regions, curves representing the shapes of the flank face 2, the cutting edge 3, and the rake face 1 are obtained. Based on the five obtained curves, the radius of curvature of the cutting edge 3 in each of the five measurement regions is measured. The average value of the radius of curvature of the cutting edge 3 in the five measurement regions is the radius of curvature R of the cutting edge 3 in the cutting tool 100. In other words, the value obtained by dividing the sum of the radii of curvature of the cutting edge 3 in the five measurement regions by 5 is set as the radius of curvature R of the cutting edge 3 in the cutting tool 100.
[0046] Similarly, based on the five obtained curves, the inclination angle of the back face 2 relative to the second imaginary straight line 92 in each of the five measurement areas is measured. The average value of the inclination angle of the back face 2 relative to the second imaginary straight line 92 in the five measurement areas is the first angle θ1. In other words, the first angle θ1 is the value obtained by dividing the sum of the inclination angles of the back face 2 relative to the second imaginary straight line 92 in the five measurement areas by 5.
[0047] <Materials constituting the substrate> The substrate 4 is, for example, made of a cemented carbide containing tungsten carbide (WC) particles. The cemented carbide constituting the substrate 4 contains, for example, tungsten carbide particles and a binder such as cobalt.
[0048] The average particle size of the WC particles contained in the cemented carbide constituting the substrate 4 is, for example, 2 μm or less. The average particle size of the WC particles contained in the cemented carbide constituting the substrate 4 may be, for example, 1.5 μm or less, or 1 μm or less. The average particle size of the WC particles contained in the cemented carbide constituting the substrate 4 may be, for example, 0.01 μm or more, or 0.1 μm or more.
[0049] In this specification, the average particle size of the WC particles is the average value of the equivalent circular diameter of the WC particles. The average value of the equivalent circular diameter of the WC particles refers to the arithmetic mean of the number of WC particles with equivalent circular diameters measured on the surface or cross-section of the cemented carbide. The average value of the equivalent circular diameter of the tungsten carbide particles is determined by the following steps.
[0050] Specifically, mirror finishing is performed on any surface or cross section of cemented carbide. Examples of mirror finishing methods include grinding with diamond polishing paste, using a focused ion beam (FIB) device, using a cross-section polisher (CP) device, and combinations thereof.
[0051] The machined surface of cemented carbide was photographed using a scanning electron microscope (S-3400N, manufactured by Hitachi High Tech Co., Ltd.). Three images were prepared. Each of the three images covered a different area. The photographed area could be arbitrarily set. The imaging conditions were set to reflected electron imaging. The magnification was 5000x. The accelerating voltage was set to 10kV.
[0052] The three captured electron reflection images were read into the computer using image analysis software (ImageJ, version 1.51j8: https: / / imagej.nih.gov / ij / ). The three images were then binarized. Binarization was performed after the images were read into the computer by pressing the "Make Binary" button on the screen, under the pre-set conditions in the image analysis software. In the binarized image, tungsten carbide particles and other areas can be distinguished by color intensity. For example, in the binarized image, tungsten carbide particles are represented by black areas, and other areas are represented by white areas.
[0053] In each of the three acquired binarized images, a rectangular measurement field of view of 25.3 μm in length and 17.6 μm in width was defined. Using the aforementioned image analysis software, the equivalent circle diameter (Heywood diameter: equivalent diameter of a circle with equal area) of all tungsten carbide particles (black areas) in the three measurement fields was measured. The arithmetic mean of the number of equivalent circle diameters of all tungsten carbide particles in the three measurement fields was calculated. In this specification, this arithmetic mean is equivalent to the average equivalent circle diameter of WC particles.
[0054] The following conditions have been confirmed: as long as the measurement is within the scope of the applicant's measurement and is performed on the same sample, even if the selected location of the measurement area is changed and the above measurement is performed multiple times, the deviation of the measurement results will be very small, and even if the measurement field of view is arbitrarily set, the results will not change arbitrarily.
[0055] <Methods for Manufacturing Cutting Tools> Next, the manufacturing method of the cutting tool 100 according to the first embodiment will be described.
[0056] Figure 6 This is a flowchart that schematically illustrates the manufacturing method of the cutting tool according to the first embodiment. For example... Figure 6 As shown, the manufacturing method of the cutting tool 100 includes: a step of forming a diamond layer on a substrate (S10); a step of sharpening the cutting edge by laser processing the rake face (S20); and a step of smoothing the rake face by ion etching (S30).
[0057] First, a process (S10) is performed to form a diamond layer on a substrate. Specifically, for example, a diamond layer 5 is formed on the substrate 4 using HFCVD (Hot Fiber Chemical Vapor Deposition). As a result, the first surface 41 and the second surface 42 of the substrate 4 are covered by the diamond layer 5.
[0058] Next, a process (S20) is performed to sharpen the cutting edge by laser processing the rake face. Figure 7 This is a cross-sectional schematic diagram showing the process (S20) in which the cutting edge is sharpened by laser processing of the rake face. For example... Figure 7 As shown, laser processing is used to remove at least a portion of the diamond layer 5 constituting the rake face 1. Specifically, a laser 81 is irradiated toward the cutting tool 100. The irradiation direction of the laser 81 is along the direction of arrow B. The irradiation direction of the laser 81 is, for example, substantially parallel to the rake face 1. From another viewpoint, the irradiation direction of the laser 81 is, for example, substantially parallel to the first face 41.
[0059] A laser processing area 82 is formed centered on the focal point F of laser 81. Laser processing area 82 is the region where the energy of laser 81 is concentrated. A portion of the cutting tool 100 located within laser processing area 82 is removed. By scanning laser 81, the diamond layer 5 constituting the rake face 1 is removed within a predetermined range. This allows the cutting edge 3 to become sharper. In other words, it allows the radius of curvature R of the cutting edge 3 to be reduced.
[0060] When the irradiation direction of laser 81 is perpendicular to the rake face 1, most of the irradiated laser 81 contacts the cutting tool 100. In this case, the area of the diamond layer 5 heated by the irradiation of laser 81 becomes larger. Consequently, the surface roughness of the diamond layer 5 easily deteriorates due to the heating. Specifically, for example, the surface roughness of the diamond layer 5 deteriorates due to an oxidation reaction occurring in the heated diamond layer 5.
[0061] According to the manufacturing method of the cutting tool 100 according to the first embodiment, the irradiation direction of the laser 81 is substantially parallel to the rake face 1. Therefore, a portion of the laser 81 passes through the focal point F without contacting the cutting tool 100. As a result, the area of the diamond layer 5 that heats up due to the irradiation of the laser 81 can be reduced. Consequently, the deterioration of the surface roughness of the diamond layer 5 can be suppressed. By suppressing the deterioration of the surface roughness of the diamond layer 5, the processing time in the process of smoothing the rake face using ion etching (S30) described later can be shortened.
[0062] Next, a process (S30) is performed to smooth the rake face using ion etching. Ion etching is performed so that both the rake face 1 and the flank face 2 are etched. The rake face 1 is smoothed. Specifically, the maximum height roughness of the first portion 16 is reduced. The processing time in the ion etching is, for example, 0.3 hours. By setting the processing time in the ion etching to approximately 0.3 hours, the thickness H of the flank face 52 can be suppressed (see reference). Figure 4 The situation becomes too small. Through the above, manufacturing... Figures 1 to 4 The cutting tool 100 shown in the first embodiment.
[0063] (Second Implementation) <Structure of Cutting Tools> Next, the structure of the cutting tool 100 according to the second embodiment will be described. The cutting tool 100 according to the second embodiment differs from the cutting tool 100 according to the first embodiment mainly in that the rake face 1 has a first rake face 11 and a second rake face 12; otherwise, it is substantially the same as the cutting tool 100 according to the first embodiment. Hereinafter, the description will focus on the differences from the cutting tool 100 according to the first embodiment.
[0064] Figure 8 This is a cross-sectional schematic diagram showing the structure of the cutting tool 100 according to the second embodiment. Figure 8 The cross section shown is Figure 4 The cross-section shown corresponds to the one depicted. For example... Figure 8 As shown, the diamond layer 5 may also cover the first surface 41 of the substrate 4. The portion of the diamond layer 5 covering the first surface 41 is formed as a front scalpel cover portion 51. From another viewpoint, the diamond layer 5 has a front scalpel cover portion 51 and a rear scalpel cover portion 52.
[0065] The front face 1 may have a first front face 11 and a second front face 12. The first front face 11 is, for example, made of a diamond layer 5. The first front face 11 is separate from the rear face 2. The first front face 11 is substantially parallel to the first face 41.
[0066] The second front cutting face 12 is disposed between the first front cutting face 11 and the rear cutting face 2. The second front cutting face 12 is connected to both the first front cutting face 11 and the rear cutting face 2. The edges of the second front cutting face 12 and the rear cutting face 2 form the cutting edge 3.
[0067] The second front cutting edge 12 is inclined relative to the first front cutting edge 11 in the direction from the first front cutting edge 11 toward the rear cutting edge 2. Specifically, in the direction perpendicular to the front cutting edge 1, the second front cutting edge 12 is inclined in the direction from the first front cutting edge 11 toward the rear cutting edge 2. It should be noted that when the front cutting edge 1 has a first front cutting edge 11 and a second front cutting edge 12, the direction perpendicular to the front cutting edge 1 is the direction perpendicular to the first front cutting edge 11.
[0068] The inclination angle of the second front cutting edge 12 relative to the first front cutting edge 11 is a second angle θ2. In a section perpendicular to the tangent of the cutting edge 3, the second angle θ2 is the angle formed by the extension line 93 of the first front cutting edge 11 and the second front cutting edge 12. The second angle θ2 is, for example, 3° or more and 50° or less. The second angle θ2 may also be, for example, 3° or more and 40° or less. The second angle θ2 may also be, for example, 5° or more and 10° or more. The second angle θ2 may also be, for example, 35° or less, 30° or less, or 20° or less.
[0069] The second front cutting face 12 is composed of a first part 16, a second part 17, and a third part 18. The first part 16 is disposed between the rear cutting face 2 and the second part 17. The second part 17 is a portion of the second front cutting face 12 made of substrate 4. The second part 17 is connected to the first part 16. The second part 17 is separate from the rear cutting face 2. The second part 17 is disposed between the first part 16 and the third part 18.
[0070] The third part 18 is a portion of the second front blade face 12 formed by the front blade covering part 51. The third part 18 is disposed between the second part 17 and the first front blade face 11. The third part 18 is connected to both the second part 17 and the first front blade face 11. The third part 18 is separate from the first part 16.
[0071] like Figure 9 As shown, with cutting edge 3 (refer to...) Figure 2 The width W of the second front cutting surface 12 in the direction perpendicular to the tangent of the first cutting surface 11 is, for example, 0.01 mm or more and 0.2 mm or less. In the substrate 4, the second portion 17 is connected to both the first surface 41 and the second surface 42. The second portion 17 is disposed between the first surface 41 and the second surface 42. The second portion 17 is inclined relative to the first surface 41 in the direction from the first front cutting surface 11 toward the rear cutting surface 2. The second surface 42 is separated from the first surface 41.
[0072] <Methods for Manufacturing Cutting Tools> Next, the manufacturing method of the cutting tool 100 according to the second embodiment will be described. Figure 9 This is a cross-sectional schematic diagram illustrating the step (S20) in the manufacturing method of the cutting tool 100 according to the second embodiment, in which the cutting edge is sharpened by laser processing of the rake face. For example... Figure 9 As shown, in the manufacturing method of the cutting tool 100 according to the second embodiment, the irradiation direction of the laser 81 (arrow B) is inclined relative to the rake face 1. From another perspective, the irradiation direction of the laser 81 is substantially inclined relative to the first face 41, for example. The inclination angle of the irradiation direction of the laser 81 relative to the rake face 1 is a second angle θ2 (refer to...). Figure 8 From another perspective, the irradiation direction of laser 81 is related to the second anterior face 12 (see reference). Figure 8 They are essentially parallel. Thus, while reducing the radius of curvature R of the cutting edge 3, a second rake face 12 is formed.
[0073] <Usage Status> Next, the usage status of the cutting tool 100 involved in this disclosure will be described.
[0074] Figure 10 This is a partial cross-sectional schematic diagram showing the usage state of the cutting tool 100 involved in this disclosure. For example... Figure 10As shown, a workpiece 90 is prepared. The workpiece 90 is made of, for example, cemented carbide. Specifically, the workpiece 90 is made of, for example, cemented carbide. The workpiece 90 may also be made of, for example, ceramics such as alumina, silicon carbide, silicon, or CFRP (Carbon Fiber Reinforced Plastics). The cutting tool 100 rotates about axis X, and the cutting edge 3 contacts the workpiece 90. Thus, the workpiece 90 is cut.
[0075] Next, the effects of the cutting tool 100 involved in this disclosure will be explained.
[0076] For example, when the workpiece is made of hard and brittle materials such as cemented carbide, it is necessary to use a cutting tool to cut high-hardness ceramic particles. In this case, a cutting tool with a high-hardness diamond layer is typically used. When the cutting edge of the cutting tool is covered by a diamond layer, the cutting edge becomes rounded as the diamond layer thickness increases. In this case, tool damage easily progresses due to the reduced sharpness of the cutting edge. On the other hand, if the diamond layer thickness is too thin, the tool's wear resistance becomes too low. Even when sufficient diamond layer thickness and high cutting edge sharpness are achieved through machining the diamond layer, chip adhesion to the cutting edge can sometimes occur due to the surface condition of the diamond layer. In this case, tool damage easily progresses by forming a structural tool tip. Especially when the workpiece is made of cemented carbide, the tungsten carbide particles contained in the cemented carbide easily adhere to the cutting edge. As described above, it is difficult to improve tool life in cutting tools with a diamond layer.
[0077] According to the cutting tool 100 disclosed herein, the diamond layer 5 has a flank cover portion 52. The flank cover portion 52 constitutes the flank face 2. The rake face 1 has a first portion 16. The first portion 16 is formed by the flank cover portion 52. The maximum height roughness of the first portion 16 is less than 2 μm. This suppresses the situation where a portion of the first portion 16 protrudes excessively. When the workpiece 90 is cut using the cutting tool 100, the chips easily come into contact with the first portion 16. Therefore, it is possible to suppress the formation of chips starting from the excessively protruding portion. As a result, tool life can be improved.
[0078] According to the cutting tool 100 disclosed herein, the thickness of the flank cover 52 is 10 μm or more and 25 μm or less. By making the thickness of the flank cover 52 10 μm or more, the wear resistance of the cutting tool 100 can be sufficiently improved.
[0079] According to the cutting tool 100 disclosed herein, in a cross-section perpendicular to the tangent of the cutting edge 3, the radius of curvature R of the cutting edge 3 is less than the value obtained by multiplying the thickness of the flank cover 52 by 0.3. This significantly improves the sharpness of the cutting edge 3. Consequently, tool damage is less likely to occur.
[0080] According to the cutting tool 100 of the second embodiment, the rake face 1 has a first rake face 11 and a second rake face 12. The second rake face 12 is inclined relative to the first rake face 11 in a direction from the first rake face 11 toward the flank face 2. As a result, the angle between the rake face 1 and the flank face 2 can be increased. Therefore, the strength of the cutting edge 3 can be improved.
[0081] According to the cutting tool 100 of the second embodiment, the inclination angle (second angle θ2) of the second front face 12 relative to the first front face 11 is 3° or more and 50° or less. By making the second angle θ2 3° or more, it is possible to suppress the situation where the angle between the second front face 12 and the flank face 2 becomes too small. As a result, it is possible to suppress the situation where the strength of the cutting edge 3 is excessively reduced. By making the second angle θ2 50° or less, it is possible to suppress the situation where the angle between the second front face 12 and the flank face 2 becomes too large. As a result, it is possible to suppress the situation where the sharpness of the cutting edge 3 is excessively reduced.
[0082] According to the cutting tool 100 disclosed herein, the substrate 4 is made of cemented carbide containing tungsten carbide particles. The average particle size of the tungsten carbide particles is 2 μm or less. As the average particle size of the tungsten carbide particles decreases, the adhesion between the substrate 4 and the diamond layer 5 improves. Therefore, by making the average particle size of the tungsten carbide particles 2 μm or less, the adhesion between the substrate 4 and the diamond layer 5 can be improved. As a result, the peeling of the diamond layer 5 from the substrate 4 can be suppressed. Consequently, the tool life can be further improved.
[0083] It should be noted that while the structure of the cutting tool 100 as a ball end mill has been described above, the cutting tool 100 involved in this disclosure is not limited to a ball end mill. For example, the cutting tool 100 may also be a fillet end mill, etc. The cutting tool 100 may also be a turning tool such as a cutting insert.
[0084] Example (Sample preparation) First, cutting tools 100 as described in Samples 1 to 22 were prepared. Samples 1, 3, 4, 8 to 18, and 22 are examples. Samples 2, 5 to 7, and 19 to 21 are comparative examples. The cutting tools 100 as described above were manufactured according to the manufacturing method of the cutting tool 100 disclosed herein. Specifically, the cutting tools 100 were manufactured using the conditions shown in Table 1 below.
[0085]
[0086] Table 1 shows the manufacturing conditions and parameters of the cutting tools 100 in samples 1 to 22. As shown in Table 1, in samples 1 to 18, 21, and 22, a process (S20) was performed to sharpen the cutting edge by laser machining the rake face. In samples 1 to 7, the irradiation direction of the laser 81 was parallel to the rake face 1. In samples 8 to 18 and 22, the irradiation direction of the laser 81 was inclined relative to the rake face 1. From another perspective, the cutting tools 100 involved in samples 8 to 18 and 22 have a second rake face 12. In sample 21, the irradiation direction of the laser 81 was perpendicular to the rake face 1. In samples 19 and 20, the process (S20) of sharpening the cutting edge by laser machining the rake face was not performed.
[0087] In samples 1 to 6, 8 to 19, 21, and 22, the ion etching process (S30) for smoothing the rake face using ion etching had a processing time of 0.3 hours. In samples 7 and 20, the process (S30) for smoothing the rake face using ion etching was not performed.
[0088] In samples 1 to 7 and samples 19 to 21, the second angle θ2 is 0°. In other words, in samples 1 to 7 and samples 19 to 21, the rake face 1 is planar (refer to...). Figure 4 In samples 8 to 18 and sample 22, the second angle θ2 is greater than 3° and less than 55°. In other words, in samples 8 to 18 and sample 22, the rake face 1 has a first rake face portion 11 and a second rake face portion 12 (see reference). Figure 7 ).
[0089] In the samples involved in the embodiments (sample 1, sample 3, sample 4, samples 8 to 18, and sample 22), the thickness H is 10.1 μm or more and 24.8 μm or less. The value obtained by dividing the radius of curvature R by the thickness H (R / H) is 0.076 or more and 0.272 or less. In other words, the radius of curvature R is greater than or equal to the value obtained by multiplying the thickness H by 0.076 and less than the value obtained by multiplying the thickness H by 0.272. The Rz of the first part 16 is 0.08 μm or more and 1.92 μm or less.
[0090] In samples 2, 19, and 20, the value obtained by dividing the radius of curvature R by the thickness H (R / H) is 0.3 or more. In sample 5, the thickness H of the rear blade cover 52 is less than 10 μm. In sample 6, the thickness H is greater than 25 μm. In samples 7 and 19 to 21, the Rz of the first part 16 is 2 μm or more.
[0091] In samples 1 to 22, the average particle size of the tungsten carbide particles contained in the cemented carbide constituting the substrate 4 is 0.5 μm or less and 3 μm or less. In samples 11 to 18, the average particle size of the tungsten carbide particles is 0.5 μm or more and 2 μm or less. In samples 1 to 22, the first angle θ1 is 15° or more and 40° or less. In samples 1 to 22, the radius of the front end portion 6 is 0.5 mm.
[0092] (Evaluation Method) Next, the tool life of the cutting tools 100 involved in Samples 1 to 22 was evaluated. Specifically, using the cutting tools 100 involved in Samples 1 to 22, a hemispherical hole with a diameter of 10 mm and a depth of 5 mm was machined into a workpiece 90. The workpiece 90 was made of cemented carbide. During machining, the rotational speed of the cutting tool 100 was 30,000 rpm. The table feed rate was 200 m / min. The depth of cut in the direction parallel to the axis X (axial depth of cut ap) was 0.04 mm. The depth of cut in the direction perpendicular to the axis X (radial depth of cut ae) was 0.2 mm. The volume of the workpiece 90 that could be cut before the cutting tool 100 broke (machined volume) was measured.
[0093] (Evaluation Results)
[0094] Table 2 shows the evaluation results for samples 1 to 22. As shown in Table 2, in the comparative examples (samples 2, 5 to 7, and 19 to 21), the processing volume was 679.9 mm. 3The following examples illustrate the processing volume of the samples (sample 1, sample 3, sample 4, samples 8 to 18, and sample 22) used in the embodiments, with a processing volume of 1046 mm². 3 above.
[0095] Based on the above results, it was confirmed that the tool life of the cutting tool 100 involved in the embodiment is improved compared with that involved in the comparative example.
[0096] The embodiments and examples disclosed herein should be considered exemplary in all respects, and not restrictive. The scope of the invention is defined not by the foregoing description, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.
[0097] Explanation of reference numerals in the attached figures 1: Rake face; 2: Back face; 3: Cutting edge; 4: Substrate; 5: Diamond layer; 6: Front end; 7: Main body; 8: Shank; 11: First rake face; 12: Second rake face; 16: First part; 17: Second part; 18: Third part; 41: First face; 42: Second face; 51: Rake face covering part; 52: Back face covering part; 58: Front end; 59: Rear end; 81: Laser; 82: Laser processing area; 90: Workpiece to be cut; 91: First imaginary straight line; 92: Second imaginary straight line; 100: Cutting tool; A, B: Arrows; F: Focal point; H: Thickness; R: Radius of curvature; W: Width; X: Axis; θ1: First angle; θ2: Second angle.
Claims
1. A cutting tool comprising a substrate and a diamond layer covering the substrate, wherein, The cutting tool has a rake face and a flank face connected to the rake face. The edges of the rake face and the flank face form the cutting edge. The diamond layer has a back face covering portion that constitutes the back face of the cutting tool. The thickness of the rear blade cover is 10 μm or more and 25 μm or less. In a cross-section perpendicular to the tangent of the cutting edge, the radius of curvature of the cutting edge is less than the value obtained by multiplying the thickness of the flank cover by 0.
3. The front cutting face includes a first portion, which is formed by the rear cutting face covering portion and is connected to the rear cutting face. The maximum height roughness of the first part is less than 2 μm.
2. The cutting tool according to claim 1, wherein, The rake face has: The first front cutting face is separated from the rear cutting face; and The second front cutting surface is disposed between the first front cutting surface and the rear cutting surface, and is connected to both the first front cutting surface and the rear cutting surface. The second front cutting face is inclined relative to the first front cutting face in the direction from the first front cutting face toward the rear cutting face.
3. The cutting tool according to claim 2, wherein, The tilt angle of the second front blade face relative to the first front blade face face is more than 3° and less than 50°.
4. The cutting tool according to any one of claims 1 to 3, wherein, The thickness of the rear blade cover is 15 μm or more and 20 μm or less.
5. The cutting tool according to any one of claims 1 to 4, wherein, In a cross section perpendicular to the tangent of the cutting edge, the radius of curvature of the cutting edge is less than the value obtained by multiplying the thickness of the back cover by 0.
1.
6. The cutting tool according to any one of claims 1 to 5, wherein, The substrate is made of a hard alloy containing tungsten carbide particles. The average particle size of the tungsten carbide particles is less than 2 μm.
7. The cutting tool according to any one of claims 1 to 6, wherein, The back angle of the back face is greater than 15° and less than 35°.
8. The cutting tool according to any one of claims 1 to 7, wherein, The maximum height roughness of the first part is less than 1.5 μm.