Method for manufacturing cutting tool and cutting tool

Abstract

A method for manufacturing a cutting tool, the cutting tool comprising a rake face, a flank face, and a cutting edge ridgeline connecting the rake face and the flank face, and a cutting edge region on the flank face from the cutting edge ridgeline to a location A separated by a distance X toward the flank face side, the method for manufacturing a cutting tool comprising a step of manufacturing and processing the flank face using a laser, the step of manufacturing and processing the flank face using the laser being the following step: when the distance X is set as the width of the cutting edge region, the cutting edge region is manufactured and processed along the cutting edge ridgeline using a first laser having a focal depth equal to or deeper than the width, and the distance X is greater than 0.2 mm and less than 5 mm.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a cutting tool and a cutting tool. This application claims priority based on Japanese patent application No. 2019-142400 filed on August 1, 2019. All the contents described in the Japanese patent application are incorporated herein by reference. Background Art

[0002] In the manufacturing process of cutting tools using raw materials such as polycrystalline diamond (hereinafter, also referred to as "PCD"), single crystal diamond (hereinafter, also referred to as "SCD"), and binderless cubic boron nitride (cBN) (hereinafter, also referred to as "BLCBN"), when grinding using a grindstone is applied, the processing requires a long time, and defects (hereinafter, also referred to as "chipping") often occur on the edge line of the blade connecting the front cutting face and the back cutting face. Furthermore, PCD, SCD, and BLCBN are insulators, so discharge machining cannot be applied in their manufacturing process. In this regard, for example, Japanese Patent Gazette No. 2016-203372 (Patent Document 1) proposes to manufacture and process such cutting tools by using a laser, thereby shortening the processing time and reducing chipping.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-203372 Summary of the invention

[0006] The present disclosure relates to a method for manufacturing a cutting tool, wherein the cutting tool comprises a rake face, a flank face, and a cutting edge ridgeline connecting the rake face and the flank face, and the area from the cutting edge ridgeline to a location A separated by a distance X toward the flank face is set as a cutting edge area on the flank face, and the method for manufacturing the cutting tool comprises a step of manufacturing and processing the flank face using a laser, and the step of manufacturing and processing the flank face using the laser is the following step: when the distance X is set as the width of the cutting edge area, the cutting edge area is manufactured and processed along the cutting edge ridgeline using a first laser having a focal depth equal to or deeper than the width, and the distance X is greater than 0.2 mm and less than 5 mm.

[0007] The cutting tool involved in the present disclosure comprises a rake face, a flank face and a cutting edge ridgeline connecting the rake face and the flank face, and a cutting edge region on the flank face is defined as a region from the cutting edge ridgeline to a point A separated by a distance X toward the flank face side, the distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm, a surface roughness of the cutting edge region represented by an arithmetic mean roughness Ra is less than or equal to 0.2 μm, and the cutting edge ridgeline does not have a chipping of a size greater than 5 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a photograph in lieu of a drawing illustrating the rounded shape of the edge and the feed mark formed by unnecessary manufacturing processing in the cutting edge region on the flank of a CVD single crystal diamond tool (Comparative Example 1) manufactured using laser manufacturing with a shallow depth of focus.

[0009] Figure 2 It is an explanatory diagram for explaining the features of the laser device including optical components for forming interference laser light exemplified as the first laser light.

[0010] Figure 3 This is an explanatory diagram for explaining interfering laser light formed by interference of primary light and secondary light having different focal positions.

[0011] Figure 4 This is an explanatory diagram for explaining the features of a laser device including a focusing optical system for obtaining a first laser beam. DETAILED DESCRIPTION

[0012] [Problems to be Solved by the Present Disclosure]

[0013] Cutting tools made of raw materials such as PCD, SCD, and BLCBN are mostly used for so-called mirror finishing to minimize the surface roughness of the cut material. Therefore, when using lasers to manufacture and process the above-mentioned cutting tools, it is required to manufacture and process the tip portion of the above-mentioned cutting tools to obtain the sharp edge shape required for finishing the surface of the cut material into a mirror surface and the strength to maintain the sharp edge shape during the cutting of the cut material. Furthermore, it is also required to manufacture and process the tip portion of the above-mentioned cutting tools to obtain a surface roughness that can perform mirror finishing.

[0014] Here, when using lasers to manufacture cutting tools, lasers with a shallow focal depth are generally used. The reason for this is to avoid unnecessary manufacturing and processing due to the undesired manufacturing and processing parts converging within the focal depth of the laser in cutting tools with complex shapes such as multi-edge tools. However, when using lasers with a shallow focal depth to manufacture the above-mentioned cutting tools, sometimes part of the tool tip is exposed to the above-mentioned laser near the focal point, and undesired manufacturing and processing is performed. For example, Figure 1 As shown, there is a case where a rounded corner (hereinafter also referred to as a "rounded corner shape") is given to the edge of the cutting edge region. Figure 1 In the enclosed portion X. In addition, Figure 1 The arrow in the figure indicates the irradiation direction of the laser). That is, when the cutting edge region is manufactured and processed using a laser having a shallow focal depth, the width direction ( Figure 1 The linearity of the cutting edge region that appears as a line in a cross section in a direction parallel to the vertical direction in the cutting edge (hereinafter, also referred to as "linearity of the cutting edge region") deteriorates, and sometimes a Figure 1 The rounded shape of the edges shown.

[0015] Furthermore, when a laser having a shallow focal depth is used to produce a machined cutting edge region, a machining trace (so-called feed mark) formed along the contour line of the focal depth of the laser light remains in the machined cutting edge region, and the desired surface roughness may not be obtained due to the feed mark (see Figure 1 Therefore, a cutting tool in which a feed mark is not formed on a cutting edge region and the linearity of the cutting edge region is improved has not yet been obtained by manufacturing processing using a laser, and development thereof is desired.

[0016] In view of the above points, the purpose of the present disclosure is to provide a method for manufacturing a cutting tool and a cutting tool obtained by the manufacturing method, wherein the method for manufacturing a cutting tool is used to obtain a cutting tool that does not form a feed mark on the cutting edge area and has improved linearity of the cutting edge area through manufacturing processing using a laser.

[0017] [Effects of the present disclosure]

[0018] According to the above, it is possible to provide a method for manufacturing a cutting tool for obtaining a cutting tool in which no feed mark is formed on a cutting edge region and the linearity of the cutting edge region is improved by manufacturing processing using a laser.

[0019] [Description of Embodiments of the Present Disclosure]

[0020] First, embodiments of the present disclosure will be described by way of examples.

[0021] [1] According to one embodiment of the present disclosure, there is provided a method for manufacturing a cutting tool, wherein the cutting tool has a front cutting face, a back cutting face, and a cutting edge line connecting the front cutting face and the back cutting face, and the cutting edge region on the back cutting face is defined as a region from the cutting edge line to a point A separated by a distance X toward the back cutting face. The method for manufacturing the cutting tool includes a step of manufacturing the back cutting face using a laser, wherein the step of manufacturing the back cutting face using the laser is as follows: when the distance X is set as the width of the cutting edge region, the cutting edge region is manufactured along the cutting edge line using a first laser having a focal depth equal to or deeper than the width, and the distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm. By using the method for manufacturing a cutting tool having such a feature, a cutting tool can be obtained in which no feed mark is formed on the cutting edge region and the linearity of the cutting edge region is improved.

[0022] [2] Preferably, the step of manufacturing the back cutting surface using the laser further includes the step of finishing the cutting edge region using a second laser having a focal depth shallower than the focal depth of the first laser. Thus, a cutting tool having a smaller surface roughness of the cutting edge region can be obtained.

[0023] [3] Preferably, the first laser is an interference laser in which the first light and the second light overlap on the same axis and interfere with each other, the first light is emitted from a single or multiple light sources and has a focal position on a first focal plane, the second light has a focal position on a second focal plane farther from the light source than the first focal plane, and the interference laser has a third focal plane with uniform cross-sectional intensity distribution between the first focal plane and the second focal plane. Thus, it is easy to form a first laser with a small change in cross-sectional intensity before and after the focal position and a focal depth equal to or deeper than the width of the cutting edge region, so that it is easy to obtain a cutting tool that does not form a feed mark on the cutting edge region and has improved linearity of the cutting edge region.

[0024] [4] Preferably, the first laser is a laser that passes through a focusing optical system that satisfies the relationship between the following equations a and b, wherein the focusing optical system includes a first optical portion having a focusing function and a second optical portion having a spherical aberration generating function.

[0025] |Z8|≥0.1λ, or, |Z 15 |≥0.05λ···a

[0026] Z8 / Z 15 ≥3, or Z8 / Z 15 <1···b

[0027] In the above formula a and formula b, λ represents the wavelength, Z8 represents the eighth coefficient of the coefficients of the Zernike marginal polynomial in the wavefront aberration, that is, the cubic spherical aberration, and Z 15 The fifteenth coefficient of the Zernike marginal polynomial representing wavefront aberration is fifth-order spherical aberration.

[0028] Thus, the first laser having a focal depth equal to or deeper than the width of the cutting edge region can be easily formed, thereby easily obtaining a cutting tool in which no feed mark is formed on the cutting edge region and the linearity of the cutting edge region is improved.

[0029] [5] Preferably, the cutting tool is a nano-polycrystalline diamond tool. Thus, a cutting tool made of nano-polycrystalline diamond can be manufactured without forming a feed mark on the cutting edge region and with improved linearity of the cutting edge region.

[0030] [6] Preferably, the cutting tool is a single crystal diamond tool. Thus, a cutting tool made of single crystal diamond can be manufactured without forming a feed mark on the cutting edge region and with improved linearity of the cutting edge region.

[0031] [7] Preferably, the cutting tool is a binderless cBN tool. Thus, a cutting tool made of binderless cBN can be manufactured without forming a feed mark on the cutting edge region and with improved linearity of the cutting edge region.

[0032] [8] One embodiment of the present disclosure relates to a cutting tool having a rake face, a flank face, and a blade edge line connecting the rake face and the flank face, wherein the cutting edge region on the flank face is defined as the region from the blade edge line to a point A separated by a distance X toward the flank face, the distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm, the surface roughness of the cutting edge region represented by the arithmetic mean roughness Ra is less than or equal to 0.2 μm, and the blade edge line does not have a chipping of a size greater than 5 μm. A cutting tool having such a feature can avoid forming a feed mark on the cutting edge region and improve the linearity of the cutting edge region, and is therefore suitable for mirror finishing applications.

[0033] [Details of the embodiments of the present disclosure]

[0034] Hereinafter, an embodiment of the present disclosure (hereinafter, also referred to as “the present embodiment”) is described in more detail. Here, in the present specification, expressions in the form of “A to B” refer to the upper and lower limits of a range (i.e., greater than A and less than B). When there is no unit recorded in A and only a unit is recorded in B, the unit of A is the same as the unit of B. Furthermore, in the present specification, when a compound is represented by a chemical formula, when the atomic ratio is not particularly limited, all conventionally known atomic ratios are included, and compounds are not necessarily limited to the stoichiometric range.

[0035] [Manufacturing method of cutting tool]

[0036] The manufacturing method of the cutting tool involved in the present embodiment is a manufacturing method of the following cutting tool, the cutting tool has a front cutting face, a back cutting face and a cutting edge line connecting the above-mentioned front cutting face and the above-mentioned back cutting face, and the cutting edge area on the above-mentioned back cutting face is from the above-mentioned cutting edge line to a point A separated by a distance X to the side of the above-mentioned back cutting face. The manufacturing method of the above-mentioned cutting tool includes a step of manufacturing and processing the above-mentioned back cutting face using a laser. The step of manufacturing and processing the above-mentioned back cutting face using the above-mentioned laser is the following step: when the above-mentioned distance X is set as the width of the above-mentioned cutting edge area, the above-mentioned cutting edge area is manufactured and processed along the above-mentioned cutting edge line using a first laser having a focal depth equal to or deeper than the above-mentioned width. By using the manufacturing method of the cutting tool having such a feature, a cutting tool can be obtained in which no feed mark is formed on the cutting edge area and the linearity of the cutting edge area is improved.

[0037] The "cutting edge area on the back blade face (hereinafter, also referred to as the "cutting edge area")" refers to an area defined by the length of the blade tip ridgeline connecting the front blade face and the back blade face and the width from the blade tip ridgeline to a point A separated by a distance X (specifically, greater than 0.2 mm and less than 5 mm) toward the back blade face. Furthermore, the "blade tip ridgeline" refers to an edge (sharp edge) where the front blade face and the back blade face intersect, but as long as the effect of the present disclosure is achieved, even if the edge appears rounded by magnifying and observing the edge, it shall be treated as a "blade tip ridgeline".

[0038] The inventors of the present invention, in the process of developing a method for manufacturing a cutting tool in which a feed mark is not formed on a cutting edge region defined as described above and the linearity of the cutting edge region is improved by manufacturing processing using a laser, paid attention to a laser having a focal depth deeper than conventional lasers used in the manufacturing processing of such a cutting tool. Specifically, the inventors came up with a solution of manufacturing the cutting edge region along the tool tip ridge line by using a laser having a focal depth equal to or deeper than the width of the cutting edge region.

[0039] In this case, it is not necessary to move the laser in the width direction of the cutting edge region to perform manufacturing processing, thereby forming no feed mark on the cutting edge region. Furthermore, since the entire width direction of the cutting edge region is converged within the deep focus depth of one laser, no rounded shape is formed on the edge of the cutting edge region (i.e., the edge line of the blade tip, etc.). Thus, the linearity of the cutting edge region can be improved.

[0040] Here, in this specification, "focal depth" refers to the depth of the laser travel direction before and after the focus of the laser, in which the laser can process the workpiece (cutting tool). Therefore, in this specification, "deep focal depth" means that the depth of the laser travel direction that can process the workpiece is large. In this specification, the depth of "focal depth" is distinguished by 0.2mm as the boundary, and the focal depth with a depth of more than 0.2mm is called "deep focal depth", and the focal depth with a depth of less than 0.2mm is called "shallow focal depth". In the case of a laser with a deep focal depth, the entire width direction of the above-mentioned cutting edge area can be converged within the focal depth, thereby forming no feed mark on the above-mentioned cutting edge area, and the linearity of the cutting edge area can be improved. The deep focal depth can generally be obtained by passing the laser through a long focus lens with a long focal length.

[0041] The manufacturing method of the cutting tool involved in this embodiment can manufacture and process the cutting tool by using a first laser having a focal depth (2 mm) deeper than the width of the cutting edge area on the back face of the cutting tool under predetermined conditions, as shown in the examples described later. Specifically, in a cutting tool having a base portion composed of cemented carbide and a blade tip portion composed of single crystal diamond (hereinafter also referred to as "CVD single crystal diamond") produced by a chemical vapor deposition (CVD: Chemical Vapor Deposition) method, the above-mentioned blade tip portion is manufactured and processed using a first laser. As a result, it is possible to manufacture and process the cutting edge area with a width of 1 mm on the back face included in the above-mentioned blade tip portion without forming a feed mark. In this case, the linearity of the above-mentioned cutting edge area is also improved. Here, the "blade tip portion" in the cutting tool refers to a portion in the cutting tool that is retained in the base portion by means such as brazing and functions as a cutting edge that directly cuts the material to be cut, and specifically refers to a portion including a rake face, a back face, and a blade tip ridge connecting the above-mentioned rake face and the above-mentioned back face.

[0042] Such a cutting tool can be obtained by a cutting tool manufacturing method including a step of manufacturing the back cutting surface using a laser, which will be described later. Hereinafter, as an example of the cutting tool manufacturing method involved in the present embodiment, a cutting tool manufacturing method including the following steps will be described: a step of manufacturing the back cutting surface using a laser, a step of preparing a cutting tool precursor for providing to the step of manufacturing the back cutting surface using a laser, and a step of preparing a laser device for providing to the step of manufacturing the back cutting surface using a laser.

[0043] <Step of Preparing a Cutting Tool Precursor>

[0044] In this process, a cutting tool precursor is prepared to be provided to the process of manufacturing the back cutting edge using laser. Such a cutting tool precursor can be manufactured using raw materials such as polycrystalline diamond (PCD), single crystal diamond (SCD) or binderless cBN (BLCBN) through conventionally known processes. For example, PCD, SCD or BLCBN formed into a predetermined tool shape can be used as a cutting tool precursor. Furthermore, a cutting tool precursor having a base portion composed of cemented carbide or the like and a cutting edge portion composed of PCD, SCD or BLCBN held to the base portion by brazing or the like can also be used.

[0045] <Step of Preparing Laser Device>

[0046] In this process, a laser device is prepared to be provided to the process of manufacturing the back cutting edge using laser. The laser device preferably has at least one of the optical components and focusing optical systems for forming interference lasers described later. That is, the laser device preferably has a laser medium and a laser oscillator having the laser medium, and at least one of the optical components and focusing optical systems described later. Regarding the laser medium included in the above-mentioned laser device and the laser oscillator having the laser medium, conventionally known laser media and laser oscillators can be used. For example, as the laser medium, neodymium, YAG, YVO4, etc. can be used.

[0047] <Process of manufacturing the back face using laser>

[0048] In this process, when the distance X (the distance from the blade edge line to the point A separated by 0.2 mm or more and 5 mm or less to the back face side) is set as the width of the cutting edge area, the cutting edge area is processed along the blade edge line using a first laser having a focal depth equal to or deeper than the width. Thus, the cutting edge area can be processed on the basis of being completely contained in a deep focal depth of the first laser in the width direction of the cutting edge area. Therefore, in this process, it is sufficient to move the first laser only in the direction along the blade edge line, and it is not necessary to move in the width direction of the cutting edge area.

[0049] (First Laser)

[0050] As described above, the first laser beam has a focal depth that is equal to or deeper than the width of the cutting edge region. The width of the cutting edge region can be represented by a distance X, specifically, the distance X is greater than 0.2 mm and less than 5 mm. Therefore, the first laser preferably has a focal depth of, for example, a depth of greater than 0.3 mm and less than 5 mm, depending on the width of the cutting edge region, and more preferably has a focal depth of greater than 1 mm and less than 5 mm. Such a first laser can be easily obtained by a laser device prepared by a process for preparing a laser device. That is, by a laser device having an optical component for forming an interference laser described later or a laser device having a focusing optical system described later, a first laser having a focal depth that is equal to or deeper than the width of the cutting edge region can be easily formed.

[0051] - Interference laser -

[0052] The first laser is preferably an interference laser in which the first light and the second light overlap on the same axis and the first light and the second light interfere with each other. The first light is irradiated from a single or multiple light sources and has a focal position on a first focal plane. The second light has a focal position on a second focal plane farther away from the light source than the first focal plane. The interference laser has a third focal plane with uniform cross-sectional intensity distribution between the first focal plane and the second focal plane. As a result, the change in cross-sectional intensity of the first laser before and after the focal position (the range from the first focal plane through the third focal plane to the second focal plane) becomes smaller, so that a deep focus depth can be obtained.

[0053] The first laser (interference laser) is not particularly limited, but can be obtained by using, for example, Figure 2 It is convenient to form a laser device including optical components as shown. Figure 3 The interference laser light shown can obtain the first laser light. Next, the structure of the optical component will be described.

[0054] like Figure 2 As shown, in the laser device, the optical component 1 includes a diffractive optical element 2 as a light generating unit and a convex lens 3 as a focusing unit. The diffractive optical element 2 and the convex lens 3 are arranged on the laser irradiation side of the laser oscillator 4 as a light source for irradiating the laser so that the optical axis of the laser is coaxial with the central axis of the diffractive optical element 2 and the convex lens 3. Thus, the laser device including the optical component 1 can form a focal plane 5 with a uniform cross-sectional intensity distribution of the interference laser light on the side opposite to the laser oscillator 4 across the diffractive optical element 2 and the convex lens 3. The focal plane 5 is equivalent to the third focal plane of the interference laser light located between the first focal plane and the second focal plane.

[0055] The laser beam emitted from the laser oscillator 4 passes through the diffractive optical element 2 and the convex lens 3 to become an interference laser beam. Specifically, the diffractive optical element 2 sets the laser beam emitted from the laser oscillator 4 as two diffracted beams with different focal positions. Figure 3 As shown in FIG. 1 , the diffractive optical element 2 converts the laser irradiated from the laser oscillator 4 into a first light 6 having a focal position on a first focal plane P1 and a second light 7 having a focal position on a second focal plane P2 farther from the laser oscillator than the first focal plane P1. The first light 6 and the second light 7 converted by the diffractive optical element 2 are overlapped on the same axis by a convex lens to form an interference laser. The interference laser has a third focal plane P3 ( Figure 2 In the third focal plane P3, the cross-sectional intensity distribution is substantially uniform near the central axis (optical axis) of the light beam.

[0056] The diffractive optical element 2 is disk-shaped, and a circular convex portion is formed on the surface of the laser oscillator 4 side. The laser irradiated from the laser oscillator 4 becomes +1st and -1st diffracted lights with different divergence angles at the convex portion of the diffractive optical element 2, thereby generating two lasers (first light and second light) with different focal positions. The height of the convex portion of the diffractive optical element 2 is set to a height that gives a phase difference of π (radians). The diameter of the convex portion is selected based on the beam diameter D of the laser irradiated to the diffractive optical element 2, specifically, it is selected within the range of 0.9 to 1.3 times the beam diameter D of the above-mentioned laser, and is preferably set to 1.2 times. The diameter and thickness of the diffractive optical element 2 can be appropriately selected according to the beam diameter D of the laser irradiated to the diffractive optical element 2. For example, the diameter of the diffractive optical element 2 can be set to 20 to 50 mm, and the thickness can be set to 3 to 5 mm.

[0057] In the diffractive optical element 2, the shape of the convex portion is not limited to a circle, and for example, a square convex portion can be provided. The diffractive optical element 2 can replace its convex portion with a concave portion that gives a phase difference of π. Furthermore, the diffractive optical element 2 can also replace the square convex portion with a square concave portion that gives a phase difference of π. The cross-sectional shape of the laser is not limited to a circle, so the shape of the circular or square convex or concave portion can also be changed to the shape of the elliptical or rectangular convex or concave portion according to its deformation.

[0058] In the optical component 1, the diffractive optical element 2 and the convex lens 3 may be arranged in the order of the convex lens 3 and the diffractive optical element 2 from the laser oscillator 4 side. The above-mentioned interference laser light can be formed by using the laser optical component described in Japanese Patent No. 5633849, for example.

[0059] - Focusing optical system -

[0060] Furthermore, it is preferable that the first laser light is a laser light that has passed through a focusing optical system that satisfies the relationship between the following equations a and b. The focusing optical system includes a first optical portion having a focusing function and a second optical portion having a spherical aberration generating function.

[0061] |Z8|≥0.1λ, or, |Z 15 |≥0.05λ···a

[0062] Z8 / Z 15 ≥3, or Z8 / Z 15 <1···b

[0063] In the above formula a and formula b, λ represents the wavelength, Z8 represents the eighth coefficient of the coefficients of the Zernike marginal polynomial in the wavefront aberration, that is, the cubic spherical aberration, and Z 15 The fifteenth coefficient among the coefficients of the Zernike marginal polynomial in wavefront aberration represents the fifth-order spherical aberration.

[0064] The laser after passing through the focusing optical system satisfying the relationship between the above-mentioned formula a and formula b will not cause the discontinuity of the cross-sectional intensity distribution before and after the focus, and will not cause the intensity of the laser at the focal position to decrease. Therefore, the above-mentioned laser can be obtained as a first laser with a deep focal depth. Therefore, through the above-mentioned focusing optical system, it is possible to easily form a first laser with a focal depth equal to or deeper than the width of the cutting edge area.

[0065] Here, Figure 4 FIG. 2 is an explanatory diagram for explaining the characteristics of a laser device having a focusing optical system for obtaining a first laser beam. Figure 4As shown, the focusing optical system 10 includes a first optical part having a focusing function and a second optical part having a spherical aberration generating function. Furthermore, sometimes a pair of galvano mirrors 11 having a function of polarizing the laser and an electric scanner 12 driving the pair of galvano mirrors are provided. As the first optical part, for example, an fθ lens 8 can be used. As the second optical part, for example, an aspherical phase plate 9 can be used. As the second optical part, a diffraction type phase plate can also be used.

[0066] When the light-collecting optical system 10 is mounted on a laser device, for example Figure 4 The laser irradiated from the laser oscillator 4 changes its direction of travel through two arc mirrors arranged near the laser oscillator 4, and then first passes through the aspherical phase plate 9 as the second optical part, thereby generating spherical aberration. Furthermore, the laser is deflected at a predetermined deflection angle by two galvano mirrors 11 and guided to the fθ lens 8 as the first optical part. Then, the laser on the optical axis and outside the optical axis after being deflected at a predetermined deflection angle by the galvano mirror 11 is parallel to the optical axis in the fθ lens 8, thereby focusing on the processing position of the processing object.

[0067] The above-mentioned focusing optical system 10 satisfies the absolute value of Z8 defined as above in the above-mentioned aspherical phase plate 9 being greater than 0.1λ and Z 15 The absolute value of is greater than 0.05λ, and satisfies at least one of the following relationships: Z8 / Z 15 The value is 3 or more and Z8 / Z 15 The value of is less than at least any one of the relations of 1. Thus, the laser light (first laser light) after passing through the above-mentioned focusing optical system 10 can obtain a deep focal depth.

[0068] Furthermore, the above-mentioned focusing optical system 10 preferably satisfies the following conditions: the absolute value of Z8 in the above-mentioned aspherical phase plate 9 is less than 1.4λ, and Z 15 The absolute value of is less than at least any one of the relationships in 0.5λ. Thus, the laser light (first laser light) after passing through the above-mentioned focusing optical system 10 passes through the above-mentioned aspherical phase plate 9, so that the intensity of the laser light at the focal position can be maintained. That is, from the viewpoint of maintaining the intensity of the laser light at the focal position, the above-mentioned focusing optical system further preferably satisfies at least any one of the relationships in the following equations c and d.

[0069] |Z8|<1.4λ···c

[0070] |Z 15 |<0.5λ···d

[0071] In the above formulas c and d, λ represents the wavelength, Z8 represents the eighth coefficient of the coefficients of the Zernike marginal polynomial in the wavefront aberration, that is, the cubic spherical aberration, and Z 15The fifteenth coefficient of the coefficients of the Zernike marginal polynomial representing wavefront aberration is the fifth-order spherical aberration.

[0072] As the above-mentioned light-converging optical system, for example, there can be mentioned the light-converging optical system described in Japanese Patent No. 5444448.

[0073] (effect)

[0074] The manufacturing method of the cutting tool involved in this embodiment can manufacture a cutting tool in which no feed mark is formed on the cutting edge area and the linearity of the cutting edge area is improved by performing a process of applying the above-mentioned laser device to the above-mentioned cutting tool precursor and using laser to manufacture the above-mentioned back cutting surface.

[0075] Furthermore, it is preferred that the process of manufacturing and processing the back cutting edge using a laser also includes the process of finishing the cutting edge area using a second laser having a focal depth shallower than the focal depth of the first laser. The second laser has a focal depth shallower than the first laser, so it is possible to accurately manufacture and process the part of the cutting edge area that needs to be manufactured and processed in order to obtain the desired surface roughness. Thereby, a cutting tool that makes the surface roughness of the cutting edge area smaller can be obtained. The second laser preferably has a focal depth of, for example, a depth of greater than 0.05 mm and less than 0.5 mm, and more preferably has a focal depth of greater than 0.1 mm and less than 0.2 mm. The second laser can be prepared by a conventionally known laser device.

[0076] Here, in the cutting tool obtained by the manufacturing method of the cutting tool, it is possible to confirm that no feed mark is formed on the cutting edge area by the following observation method using a laser microscope. That is, the cutting edge area on the back face of the cutting tool obtained by the manufacturing method is observed at a magnification of 10 times using a laser microscope (manufactured by Leica Corporation), thereby confirming the presence or absence of the feed mark. Regarding the evaluation of the presence or absence of the feed mark, five randomly selected fields of view on the cutting edge area of ​​one cutting tool are observed, and only when it is confirmed that there is no feed mark in all the fields of view, it can be judged that the cutting edge area on the back face of the cutting tool is not formed with the feed mark.

[0077] The linearity of the cutting edge area in the above-mentioned cutting tool can be evaluated by the following method. First, a cutting tool is manufactured by using the above-mentioned manufacturing method to obtain a sample for evaluating the linearity of the cutting edge area. Next, in the above-mentioned sample, from location A which becomes one end of the cutting edge area (i.e., location A separated by a distance X from the blade edge line to the back blade side), via the above-mentioned blade edge line, to a point on the front blade face separated by 100 μm from the above-mentioned blade edge line to the front blade side, a contour shape measuring instrument (Contracer, trade name: "PF60", manufactured by Mitaka Optical Instruments Co., Ltd.) is used to measure at a resolution of 0.1 μm. Thus, a point plot with a spacing of 0.1 μm is drawn from the cutting edge area in the above-mentioned sample via the blade edge line to the front blade face.

[0078] Furthermore, by using analytical software (trade name: "MitakaMap", manufactured by Mitaka Optical Instruments Co., Ltd.) on the above-mentioned point drawing, a location separated by 10 μm from the above-mentioned blade edge line to the back blade side is selected as location S, and a straight line portion on the back blade side is produced based on the point group from the selected location S to the above-mentioned blade edge line. Similarly, in the above-mentioned point drawing, a location separated by 10 μm from the above-mentioned blade edge line to the front blade side is selected as location T, and a straight line portion on the front blade side is produced based on the point group from the selected location T to the above-mentioned blade edge line. Next, the straight line portion on the back blade side and the straight line portion on the front blade side are extended to obtain a cross line where they intersect. Finally, by comparing the above-mentioned cross line with the above-mentioned point drawing, it is confirmed whether the blade edge line portion in the above-mentioned point drawing is consistent with the intersection portion of the above-mentioned cross line, or when the blade edge line portion in the above-mentioned point drawing is inconsistent with the intersection portion of the above-mentioned cross line, the distance between them is calculated. In the present embodiment, when the distance between the blade edge line portion in the above-mentioned dot plotting and the intersection of the above-mentioned intersection lines is within 1 μm, the radius of curvature of the ridge in the above-mentioned blade edge line is less than 1 μm, so in this case it can be judged that the linearity of the cutting edge area is improved. In other words, the case where it can be judged that the linearity of the cutting edge area is improved is limited to the case where the rounded shape that appears by magnifying the edge of the blade edge line has a radius of curvature of less than 1 μm. It should be noted that when the blade edge line portion in the above-mentioned dot plotting coincides with the intersection of the above-mentioned intersection lines, the distance between them is 0 (zero), so the radius of curvature of the ridge in the above-mentioned blade edge line is less than 1 μm.

[0079] 〔Nano polycrystalline diamond tools〕

[0080] The cutting tool obtained by the manufacture method of above-mentioned cutting tool is preferably nano polycrystalline diamond tool.That is, above-mentioned manufacture method is preferably the manufacture method of the cutting tool of manufacturing nano polycrystalline diamond tool.Nano polycrystalline diamond refers to polycrystalline diamond containing multiple particle diameters as nano-level diamond grains.Thus, can not form feed mark on cutting edge area, and make the linearity of cutting edge area improve and manufacture nano polycrystalline diamond tool.In this manual, " nano polycrystalline diamond tool " can be the form of the cutting tool consisting of nano polycrystalline diamond, can also be the form of the cutting tool having the matrix consisting of superhard alloy etc. and the cutting tool of the tip of a knife consisting of the nano polycrystalline diamond that is kept in this matrix by means such as brazing.

[0081] 〔Single crystal diamond tools〕

[0082] The cutting tool obtained by the manufacturing method of the cutting tool is preferably a single crystal diamond tool. That is, the manufacturing method is preferably a manufacturing method of a cutting tool for manufacturing a single crystal diamond tool. Thus, it is possible to manufacture a single crystal diamond tool without forming a feed mark on the cutting edge region and improving the linearity of the cutting edge region. In this specification, a "single crystal diamond tool" may be a cutting tool made of single crystal diamond, or a cutting tool having a base made of superhard alloy or the like and a blade tip made of single crystal diamond held on the base by methods such as brazing.

[0083] 〔Adhesive-free cBN tools〕

[0084] The cutting tool obtained by the above-mentioned method for manufacturing a cutting tool is preferably a binderless cBN tool. That is, the above-mentioned manufacturing method is preferably a method for manufacturing a cutting tool for manufacturing a binderless cBN tool. Binderless cBN (BLCBN) refers to a cBN polycrystal in which cBN particles are bonded to each other without a binder (binding material). BLCBN can be obtained by sintering cBN as a starting material under predetermined high temperature and high pressure conditions without using a binding material. Thus, a binderless cBN tool can be manufactured without forming a feed mark on the cutting edge area and improving the linearity of the cutting edge area. In this specification, a "binderless cBN tool" may be in the form of a cutting tool composed of binderless cBN, or may be in the form of a cutting tool having a base portion composed of cemented carbide or the like and a blade tip portion composed of binderless cBN held to the base portion by brazing or the like.

[0085] 〔Cutting Tools〕

[0086] The cutting tool of this embodiment has a rake face, a flank face, and a blade edge line connecting the rake face and the flank face, and the cutting edge area on the flank face is from the boundary with the blade edge line to a point A separated by a distance X toward the flank face side. The distance X is greater than 0.2 mm and less than 5 mm, the surface roughness of the cutting edge area represented by the arithmetic mean roughness Ra is less than 0.2 μm, and the blade edge line does not have a chipping of a size greater than 5 μm. The cutting tool having such characteristics does not form a feed mark on the cutting edge area, and the linearity of the cutting edge area is improved, so it is suitable for mirror processing.

[0087] The manufacturing method for manufacturing the cutting tool should not be limited as long as the cutting tool has a cutting edge region having a surface roughness expressed as an arithmetic mean roughness Ra of less than 0.2 μm and a blade edge line without a chipped blade edge line having a size of 5 μm or more. However, it is preferred to use the manufacturing method for the cutting tool because a cutting tool having the characteristics of the cutting edge region and the blade edge line can be obtained with good yield. In this specification, the terms "cutting edge region on the back face" and "blade tip" used to describe the cutting tool are defined as described in the item [Manufacturing method of cutting tool].

[0088] <Arithmetic mean roughness Ra>

[0089] In the cutting tool involved in the present embodiment, the surface roughness represented by the arithmetic mean roughness Ra of the cutting edge region is 0.2 μm or less. Thus, it is clear that no feed mark is formed on the cutting edge region. In the above-mentioned cutting tool, the surface roughness represented by the arithmetic mean roughness Ra of the cutting edge region is preferably 0.1 μm or less, and more preferably 0.05 μm or less. The lower limit of the surface roughness represented by the arithmetic mean roughness Ra of the cutting edge region should not be particularly specified, but can be set to 0.003 μm.

[0090] The surface roughness of the cutting edge region represented by the arithmetic mean roughness Ra can be obtained according to JIS B0601 (2001), and specifically, can be obtained by applying a laser surface roughness measuring instrument (trade name: "OLS4500", manufactured by Olympus Corporation) to the cutting edge region.

[0091] <Number of fragments>

[0092] In the cutting tool according to the present embodiment, the cutting edge ridgeline does not have a chipping of 5 μm or more. This shows that the cutting tool is suitable for mirror finishing. In the above-mentioned cutting tool, it is preferred that the cutting edge ridgeline does not have a chipping of 2 μm or more.

[0093] The fact that the cutting tool does not have any fragmentation larger than 5 μm on the blade edge line can be confirmed by observing the blade edge line at a magnification of 500 times using an optical microscope. Specifically, for the defect (depression) on the blade edge line obtained by the above observation using an optical microscope, the maximum amount of fragmentation from the blade edge line to the back blade face direction is measured. Similarly, the maximum amount of fragmentation from the blade edge line to the front blade face direction is also measured. In these measurements, it is verified that the notch (depression) on the blade edge line does not exceed 5 μm in either direction of the back blade face direction and the front blade face direction. Through the above, it can be confirmed that the cutting tool does not have any fragmentation larger than 5 μm on the blade edge line.

[0094] (Note)

[0095] The above description includes the following additional embodiments.

[0096] A method for manufacturing a cutting tool, wherein the cutting tool has a rake face, a flank face, and a cutting edge ridgeline connecting the rake face and the flank face, and the cutting edge region on the flank face is defined as a region from the cutting edge ridgeline to a point A separated by a distance X toward the flank face.

[0097] The manufacturing method of the cutting tool comprises the step of manufacturing the back cutting surface by using a laser.

[0098] The step of manufacturing the back face using the laser is a step of: when the distance X is set as the width of the cutting edge region, the cutting edge region is manufactured along the cutting edge ridgeline using a first laser having a focal depth equal to or deeper than the width,

[0099] The distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm.

[0100] Example

[0101] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0102] [Example 1]

[0103] <Step of Preparing a Cutting Tool Precursor>

[0104] First, a cutting tool precursor is prepared to be provided to a process of manufacturing a back cutting face using a laser. As such a cutting tool precursor, a cutting tool precursor using a CVD single crystal diamond obtained by a conventionally known method as a cutting tip portion is prepared. Specifically, for a base portion composed of cemented carbide, the above-mentioned CVD single crystal diamond is held on the base portion as a cutting tip portion by brazing, thereby manufacturing a cutting tool precursor. The above-mentioned cutting tool precursor has a front cutting face, a back cutting face, and a cutting edge line connecting the above-mentioned front cutting face and the above-mentioned back cutting face in the cutting tip portion composed of CVD single crystal diamond, and has a cutting edge area on the above-mentioned back cutting face with a width from the above-mentioned cutting edge line to a point A separated by a distance X of 1 mm to the above-mentioned back cutting face side.

[0105] <Step of Preparing Laser Device>

[0106] Next, a laser device is prepared for the process of manufacturing the back face by laser. As such a laser device, a laser device having a laser oscillator having YVO4 as a laser medium and an optical component is prepared, wherein the laser oscillator forms an interference laser into a first laser according to the laser irradiated from the laser oscillator. The optical component includes Figure 2 The diffractive optical element and the convex lens shown in the figure form an interference laser in which the first light and the second light overlap on the same axis and the first light and the second light interfere with each other. The interference laser (first laser) is set to a size from the first focal plane through the third focal plane to the second focal plane, and has a focal depth of 2 mm.

[0107] <Process of manufacturing the back face using laser>

[0108] By using the laser device, a cutting edge region having a width of 1 mm on the processed flank surface was produced along the cutting edge ridgeline in the cutting tool precursor. The irradiation conditions of the first laser beam in this step are as follows.

[0109] (Irradiation Conditions of the First Laser Light)

[0110] Wavelength: 532nm

[0111] Output: 10W

[0112] Pulse width: 50nsec.

[0113] Thus, a cutting tool (single crystal diamond tool) according to Example 1 was produced, in which CVD single crystal diamond was used as a cutting edge portion on a base portion made of cemented carbide.

[0114] [Comparative Example 1]

[0115] The cutting tool (single crystal diamond tool) of Comparative Example 1 was produced by the same steps as in Example 1, except that in the step of laser processing the back cutting edge, the cutting edge area of ​​the cutting tool precursor was processed by laser with a focal depth of 0.1 mm.

[0116] [Various reviews]

[0117] <Presence or absence of feed mark>

[0118] The cutting edge regions of the cutting tools of Example 1 and Comparative Example 1 were evaluated for the presence or absence of feed marks using the above method. As a result, no feed marks were confirmed on the cutting edge region of the cutting tool of Example 1, whereas feed marks were confirmed at 30 μm intervals on the cutting edge region of the cutting tool of Comparative Example 1 (see Table 1). Figure 1 The surrounding part Y).

[0119] <Linearity of cutting edge area>

[0120] The linearity of the cutting edge region in the cutting tools of Example 1 and Comparative Example 1 was evaluated using the above method. As a result, the cutting edge ridgeline portion of the cutting tool of Example 1 was consistent with the intersection of the intersection lines, and it can be evaluated that the linearity of the cutting edge region was improved. On the other hand, the cutting tool of Comparative Example 1 had a rounded shape with a curvature radius exceeding 1 μm at the edge of the cutting edge region (refer to Figure 1 The surrounding part X).

[0121] <Arithmetic mean roughness Ra>

[0122] The surface roughness expressed as the arithmetic mean roughness Ra was determined using the above method for the cutting edge regions of the cutting tools of Example 1 and Comparative Example 1. As a result, the surface roughness (Ra) of the cutting tool of Example 1 was 0.1 μm, while the surface roughness (Ra) of the cutting tool of Comparative Example 1 was 0.3 μm.

[0123] <Number of fragments>

[0124] The presence or absence of chipping of 5 μm or more was confirmed using the above method for the cutting edge ridges of the cutting tools of Example 1 and Comparative Example 1. As a result, no chipping of the above size was confirmed in the cutting tool of Example 1, but three chippings of the above size were found in the cutting tool of Comparative Example 1.

[0125] 〔Investigation〕

[0126] As can be seen from the above, the cutting tool of Example 1 is manufactured by using the first laser having a focal depth of 2 mm, so that no feed mark is formed on the cutting edge region, and the linearity of the cutting edge region is improved compared with the cutting tool of Comparative Example 1. Further, in the cutting tool of Example 1, the surface roughness expressed by the arithmetic mean roughness Ra in the cutting edge region is 0.1 μm or less, and the blade edge line does not have a chipping of 5 μm or more in size, so it can be understood that the surface roughness in the cutting edge region and the number of chippings in the blade edge line are both excellent compared with the cutting tool of Comparative Example 1.

[0127] As mentioned above, although embodiment and Example of this indication were demonstrated, it is planned to combine the structure of each embodiment and Example mentioned above as appropriate.

[0128] The embodiments and examples disclosed herein are illustrative in all aspects and are not restrictive. The scope of the present invention is indicated by the claims rather than the embodiments and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0129] Description of Reference Numerals

[0130] X, Y: surrounding part; 1: optical component; 2: diffractive optical element; 3: convex lens; 4: laser oscillator; 5: focal plane; 6: first light; 7: second light; 8: fθ lens; 9: aspheric phase plate; 10: focusing optical system; 11: galvanometer; 12: galvano-scanner; P1: first focal plane; P2: second focal plane; P3: third focal plane.

Claims

1. A method for manufacturing a cutting tool, wherein the cutting tool has a rake face, a flank face, and a cutting edge line connecting the rake face and the flank face, and the cutting edge area on the flank face is the area from the cutting edge line to a point A separated by a distance X toward the flank face, wherein: The manufacturing method of the cutting tool comprises the step of manufacturing the back cutting surface by using a laser. The step of manufacturing the back face using the laser is a step of: when the distance X is set as the width of the cutting edge region, the cutting edge region is manufactured along the cutting edge ridgeline using a first laser having a focal depth equal to or deeper than the width, The distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm.

2. The method for manufacturing a cutting tool according to claim 1, wherein: The step of manufacturing the flank surface using the laser light further includes the step of finishing the cutting edge region using a second laser light having a focal depth shallower than a focal depth of the first laser light.

3. The method for manufacturing a cutting tool according to claim 1 or 2, wherein: The first laser is an interference laser in which a first light and a second light overlap on the same axis and the first light and the second light interfere with each other. The first light is emitted from a single light source or multiple light sources and has a focal position on a first focal plane. The secondary light has a focal position at a second focal plane farther from the light source than the first focal plane, The first laser has a third focal plane with uniform cross-sectional intensity distribution between the first focal plane and the second focal plane.

4. The method for manufacturing a cutting tool according to claim 1 or 2, wherein: The first laser is a laser that passes through a focusing optical system that satisfies the following relationship: The focusing optical system comprises a first optical part having a focusing function and a second optical part having a spherical aberration generating function. |Z8| ≥ 0.1λ, or, |Z 15 | ≥ 0.05λ ··· a Z8 / Z 15 ≥3, or, Z8 / Z 15 <1···b In the above formula a and formula b, λ represents the wavelength, Z8 represents the eighth coefficient of the coefficients of the Zernike marginal polynomial in the wavefront aberration, that is, the cubic spherical aberration, and Z 15 The fifteenth coefficient of the coefficients of the Zernike marginal polynomial representing wavefront aberration is the fifth-order spherical aberration.

5. The method for manufacturing a cutting tool according to claim 1 or 2, wherein: The cutting tool is a nano polycrystalline diamond tool.

6. The method for manufacturing a cutting tool according to claim 1 or 2, wherein: The cutting tool is a single crystal diamond tool.

7. The method for manufacturing a cutting tool according to claim 1 or 2, wherein: The cutting tool is a binderless cBN tool.

8. A cutting tool comprising a rake face, a flank face, and a cutting edge line connecting the rake face and the flank face, wherein the cutting edge area on the flank face is the area from the cutting edge line to a point A separated by a distance X toward the flank face, wherein: The distance X is greater than or equal to 0.2 mm and less than or equal to 5 mm. The surface roughness of the cutting edge region expressed as an arithmetic mean roughness Ra is 0.2 μm or less, The blade edge line does not have any cracks with a size of 5 μm or more, The curvature radius of the ridge in the blade edge line is less than 1 μm, The material of the cutting tool is nano polycrystalline diamond, single crystal diamond or binder-free cBN. When five randomly selected fields of view in the cutting edge region on the flank face were observed at a magnification of 10 times using a laser microscope, no feed mark was found in any of the fields of view.

9. The cutting tool according to claim 8, wherein: The surface roughness of the cutting edge region represented by an arithmetic mean roughness Ra is 0.1 μm or less.

10. The cutting tool according to claim 8 or 9, wherein: The surface roughness of the cutting edge region represented by an arithmetic mean roughness Ra is 0.05 μm or less.

11. The cutting tool according to claim 8 or 9, wherein: The blade edge line does not have any cracks having a size of 2 μm or more.

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