Diamond cutting tool and method for manufacturing the same

Abstract

A diamond cutting tool includes a blade tip portion, wherein the blade tip portion includes single crystal diamond or binderless polycrystalline diamond, and graphite, wherein the carbon constituting the single crystal diamond or binderless polycrystalline diamond is set as the first carbon, and the carbon constituting the graphite is set as the second carbon, and when Raman spectroscopic analysis is performed on the surface of the blade tip portion, a ratio R1 of the sum of a peak intensity Id1 of the first carbon in the surface and a peak intensity Ig1 of the second carbon in the surface is greater than 0.5 and less than 1, and when Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of the sum of a peak intensity Id2 of the first carbon in the surface located at a depth of 1 μm from the surface and a peak intensity Ig2 of the second carbon in the surface located at a depth of 1 μm from the surface is greater than 0.01 and less than 0.3.

Description

Technical Field

[0001] The present disclosure relates to a diamond cutting tool and a method for manufacturing the same. This application claims priority based on Japanese Patent Application No. 2019-193506 filed on October 24, 2019. All the contents described in the Japanese patent application are incorporated herein by reference. Background Art

[0002] In the case of processing hard-to-cut materials such as non-ferrous metals headed by aluminum alloys, carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), ceramics, ceramic matrix composites (CMC), and superhard alloys, diamond cutting tools whose blades are substantially made of diamonds have been widely used. However, for such cut materials, cutting oil (hereinafter, also referred to as "coolant") cannot be used in most cases during processing. In this case, the wear of the blade becomes severe during processing, so it is required to improve the wear resistance of the diamond cutting tool.

[0003] In view of the above-mentioned requirements, Japanese Patent Publication No. 2005-088178 (Patent Document 1) discloses a diamond sintered body tool in which a graphite layer is actively precipitated on the flank face by electrical discharge machining. In this diamond sintered body tool, the wear resistance of the flank face is improved by the lubricity possessed by the above-mentioned graphite layer. Japanese Patent Publication No. 2011-121142 (Patent Document 2) discloses a diamond coated cutting tool, which is formed with a continuous graphite phase in the film thickness direction of the diamond coating coated on the surface of the tool matrix. In this diamond coated cutting tool, the wear resistance is improved by the above-mentioned graphite phase, and the diamond coating can be prevented from peeling off because of residual stress.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-088178

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-121142 Summary of the invention

[0008] The diamond cutting tool involved in the present disclosure includes a blade tip portion, which has single crystal diamond or binderless polycrystalline diamond, and graphite, wherein the carbon constituting the above-mentioned single crystal diamond or the above-mentioned binderless polycrystalline diamond is set as the first carbon, and the carbon constituting the above-mentioned graphite is set as the second carbon, and when Raman spectroscopic analysis is performed on the surface of the above-mentioned blade tip portion, the ratio R1 of the above-mentioned Ig1 to the sum of the peak intensity Id1 of the above-mentioned first carbon in the above-mentioned surface and the peak intensity Ig1 of the above-mentioned second carbon in the above-mentioned surface is greater than 0.5 and less than 1, and when Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the above-mentioned surface, the ratio R2 of the above-mentioned Ig2 to the sum of the peak intensity Id2 of the above-mentioned first carbon in the surface located at a depth of 1 μm from the above-mentioned surface and the peak intensity Ig2 of the above-mentioned second carbon in the surface located at a depth of 1 μm from the above-mentioned surface is greater than 0.01 and less than 0.3.

[0009] The manufacturing method of the diamond cutting tool involved in the present disclosure is the manufacturing method of the above-mentioned diamond cutting tool, wherein the manufacturing method includes: a process of preparing the above-mentioned single crystal diamond or the above-mentioned binderless polycrystalline diamond; a process of performing laser processing on the above-mentioned single crystal diamond or the above-mentioned binderless polycrystalline diamond under a first irradiation condition, thereby obtaining the above-mentioned blade tip portion formed with a cutting edge; and a process of performing laser processing on the above-mentioned blade tip portion under a second irradiation condition different from the above-mentioned first irradiation condition, thereby generating graphite on the above-mentioned blade tip portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a graph showing the change in the ratio (Ig / (Ig+Id)) of graphite to the sum of single crystal diamond or binderless polycrystalline diamond and graphite from the surface of the tip portion (surface of the back face) toward the depth direction of the diamond cutting tool involved in this embodiment.

[0011] Figure 2 Yes Figure 1 The change in the ratio of graphite from the surface of the blade tip toward the depth direction in the diamond cutting tool involved in this embodiment shown in the graph is schematically reflected in the explanatory diagram shown in a cross section of a part of the above-mentioned blade tip (a part of the back face) cut from the surface along the depth direction. DETAILED DESCRIPTION

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

[0013] For the diamond sintered body tool disclosed in Patent Document 1, since the precipitated graphite layer only exists on the surface of the back face, the improvement of wear resistance based on the lubricity of the graphite layer is only a temporary effect, and there is room for improvement in that the above lubricity needs to be sustained. For the diamond coated cutting tool disclosed in Patent Document 2, since the above graphite phase exists continuously in a certain amount in the film thickness direction, there is room for improvement in that the lubricity to cope with initial wear is insufficient. Therefore, a diamond cutting tool having lubricity to cope with initial wear and suppressing the wear of the tool tip during processing by sustaining the above lubricity has not yet been realized, and therefore it is urgently desired to develop a diamond cutting tool with improved wear resistance.

[0014] In view of the above-mentioned actual situation, an object of the present disclosure is to provide a diamond cutting tool with improved wear resistance and a method for manufacturing the same.

[0015] [Effects of the present disclosure]

[0016] According to the present disclosure, it is possible to provide a diamond cutting tool having improved wear resistance and a method for manufacturing the same.

[0017] [Description of Embodiments of the Present Disclosure]

[0018] The inventors of the present invention have repeatedly conducted in-depth research to solve the above-mentioned problems, thereby completing the present disclosure. Specifically, for the blade tip portion composed of single crystal diamond or binderless polycrystalline diamond in a diamond cutting tool, laser processing is performed under predetermined irradiation conditions, thereby generating graphite at the above-mentioned blade tip portion. It is found that in this case, the above-mentioned graphite decreases approximately monotonically from the surface of the blade tip portion toward the depth direction in the single crystal diamond or binderless polycrystalline diamond and exists to a predetermined depth. It is found that the diamond cutting tool having the above-mentioned graphite at the blade tip portion has excellent lubricity that can cope with initial wear, and the above-mentioned lubricity is sustained, thereby realizing a diamond cutting tool with improved wear resistance.

[0019] First, embodiments of the present disclosure will be described by way of examples.

[0020] [1] A diamond cutting tool according to one embodiment of the present disclosure includes a cutting edge portion, the cutting edge portion having single crystal diamond or binderless polycrystalline diamond, and graphite, wherein the carbon constituting the single crystal diamond or binderless polycrystalline diamond is a first carbon, and the carbon constituting the graphite is a second carbon, and when Raman spectrometry is performed on the surface of the cutting edge portion, a ratio R1 of the Ig1 relative to the sum of a peak intensity Id1 of the first carbon in the surface and a peak intensity Ig1 of the second carbon in the surface is greater than or equal to 0.5 and less than or equal to 1, and when Raman spectrometry is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of the Ig2 relative to the sum of a peak intensity Id2 of the first carbon in the surface located at a depth of 1 μm from the surface and a peak intensity Ig2 of the second carbon in the surface located at a depth of 1 μm from the surface is greater than or equal to 0.01 and less than or equal to 0.3. The diamond cutting tool having such characteristics has excellent lubricity that can cope with initial wear, and can improve wear resistance by maintaining the lubricity.

[0021] [2] Preferably, in the diamond cutting tool, when Raman spectroscopic analysis is performed on a surface located at a depth of 0.5 μm from the surface, a ratio R3 of the Ig3 relative to the sum of the peak intensity Id3 of the first carbon located at a depth of 0.5 μm from the surface and the peak intensity Ig3 of the second carbon located at a depth of 0.5 μm from the surface is smaller than R1 and larger than R2. This can further improve wear resistance.

[0022] [3] Preferably, the surface is a flank surface. Thus, it is possible to provide a diamond cutting tool having excellent lubricity on the flank surface that can cope with initial wear and that functions to maintain the lubricity.

[0023] [4] A method for manufacturing a diamond cutting tool according to one embodiment of the present disclosure is the method for manufacturing the diamond cutting tool, wherein the method comprises: a step of preparing the single crystal diamond or the binderless polycrystalline diamond; a step of performing laser processing on the single crystal diamond or the binderless polycrystalline diamond under a first irradiation condition to obtain the blade tip portion having a cutting edge; and a step of performing laser processing on the blade tip portion under a second irradiation condition different from the first irradiation condition to generate graphite at the blade tip portion. The method for manufacturing a diamond cutting tool having such a feature has excellent lubricity that can cope with initial wear, and maintains the lubricity, thereby being able to manufacture a diamond cutting tool having improved wear resistance.

[0024] [5] Preferably, as the second irradiation condition, the laser wavelength is 532 nm to 1064 nm, the laser spot diameter is 5 μm to 70 μm in half-value width, the laser focus depth is 1 mm or more, the laser output is 1 W to 20 W at the processing point, the laser scanning speed is 5 mm / s to 100 mm / s, and the laser repetition frequency is 10 Hz to 1 MHz. As a result, graphite that imparts lubricity that can cope with initial wear and that maintains the lubricity can be produced at a high yield at the tool tip.

[0025] [Details of the embodiments of the present disclosure]

[0026] Below, refer to Figure 1 The embodiment of the present disclosure (hereinafter, also referred to as "the present embodiment") is described in detail. In the following description, the expression in the form of "A to B" refers to the upper and lower limits of the 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.

[0027] 〔Diamond cutting tools〕

[0028] The diamond cutting tool involved in this embodiment is a diamond cutting tool including a blade tip portion, the blade tip portion having single crystal diamond (hereinafter, also referred to as "SCD") or binderless polycrystalline diamond (hereinafter, also referred to as "BLPCD"), and graphite. Hereinafter, the carbon constituting the SCD or BLPCD is sometimes described using the term "first carbon", and the carbon constituting the graphite is sometimes described using the term "second carbon".

[0029] In the diamond cutting tool, when Raman spectroscopic analysis is performed on the surface of the blade tip portion, a ratio R1 of the Ig1 relative to the sum of the peak intensity Id1 of the first carbon in the surface and the peak intensity Ig1 of the second carbon in the surface is greater than or equal to 0.5 and less than or equal to 1. Furthermore, in the diamond cutting tool, when Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of the Ig2 relative to the sum of the peak intensity Id2 of the first carbon in the surface located at a depth of 1 μm from the surface and the peak intensity Ig2 of the second carbon in the surface located at a depth of 1 μm from the surface is greater than or equal to 0.01 and less than or equal to 0.3.

[0030] In the above-mentioned diamond cutting tool, when the above-mentioned R1 is greater than 0.5 and less than 1, and the above-mentioned R2 is greater than 0.01 and less than 0.3, it is possible to obtain excellent lubricity based on graphite that can cope with initial wear and the effect of maintaining the above-mentioned lubricity at the tip portion. As a result, the wear resistance of the diamond cutting tool is improved. Here, the above-mentioned diamond cutting tool typically exists in the following form: it includes a tip portion having the above-mentioned characteristics and a base portion to which the tip portion is joined by means such as brazing. The above-mentioned diamond cutting tool sometimes also exists in a form that is composed only of the tip portion having the above-mentioned characteristics. In addition, the above-mentioned diamond cutting tool can also be a form in which the entirety of the diamond cutting tool is composed of single crystal diamond or adhesive-free polycrystalline diamond, and graphite, and the tip portion has the above-mentioned characteristics.

[0031] Hereinafter, in the present embodiment, a diamond cutting tool including a cutting edge portion having the above-mentioned features and the above-mentioned base portion will be described in detail as one aspect of the diamond cutting tool, but the present disclosure does not exclude diamond cutting tools of other aspects.

[0032] <Blade Tip>

[0033] The diamond cutting tool involved in this embodiment includes a cutting edge portion, which has SCD or BLPCD, and graphite. The cutting edge portion has a front cutting face, a back cutting face, and a cutting edge formed between the front cutting face and the back cutting face. The cutting edge is a portion that directly participates in the processing of the cut material, and is composed of a part of the front cutting face, a part of the back cutting face, and a ridge line intersecting the front cutting face and the back cutting face. In this specification, the "front cutting face" refers to the surface that sweeps away the chips cut from the cut material during cutting, and the "back cutting face" refers to the surface that faces the cut surface of the cut material during cutting.

[0034] The above-mentioned tool tip portion is a block with the above-mentioned SCD or BLPCD as the main component, and has a block shape. Therefore, this shape is different from the above-mentioned diamond coating in the diamond coated tool that forms the tool tip by coating any substrate such as superhard alloy with a diamond coating. Further, the shapes of the above-mentioned diamond coating and the above-mentioned tool tip portion in the present embodiment are different from each other, so that not only the characteristics are different, but also the purpose of use and the manufacturing method are different. This is also the same in the relationship between the diamond coated tool with a diamond coating containing graphite disclosed in the above-mentioned patent document 2 and the diamond cutting tool with a tool tip portion of the present embodiment. For example, if the diamond coated tool of the above-mentioned patent document 2 is compared with the diamond cutting tool of the present embodiment, not only the manufacturing method is different, but also the method of generating graphite at the tool tip portion is completely different.

[0035] Furthermore, in diamond coated tools, generally speaking, the thickness of the diamond coating is about 5 to 10 μm, and it is essentially impossible to produce a thin film with a thickness of more than 100 μm. In contrast, in the diamond cutting tool involved in this embodiment, it is easy to make the thickness of the SCD or BLPCD as the cutting edge portion more than 100 μm.

[0036] (SCD and BLPCD)

[0037] The blade tip has SCD or BLPCD. SCD can be prepared by performing a conventionally known manufacturing method such as a high-temperature high-pressure synthesis (HPHT) method or a chemical vapor deposition (CVD) method. BLPCD is a polycrystalline diamond in which diamond particles are bonded to each other without an adhesive (bonding material). BLPCD can be prepared by using graphite as a starting material, converting it into diamond particles by a conventionally known HPHT method, and sintering the diamond particles without using a bonding material to bond them. In particular, the SCD and BLPCD prepared as the blade tip preferably have a wavelength of 3 cm with respect to the laser used in the second irradiation condition described later. -1 Over and less than 10cm -1 Thus, the blade tip portion that achieves the effect of the present disclosure can be efficiently formed.

[0038] The absorption coefficient of light (laser) of SCD and BLPCD can be obtained by using the following measurement method. First, a plate-shaped SCD or BLPCD of a determined thickness is prepared, for example, by appropriately using the manufacturing method of a diamond cutting tool described later. Next, for the above-mentioned SCD or BLPCD, the transmittance T of light at the wavelength of the laser (for example, 532nm or 1064nm) is measured by ultraviolet visible spectroscopy. Here, the transmittance T of the above-mentioned light is the ratio (I / I0) of the intensity of the incident light I0 directed to the object and the intensity of the transmitted light I of the object. When the thickness of the object is set to L, the reflectivity of the light inherent to the object is set to R, and the absorption coefficient of the light is set to α, the ratio (I / I0) can be obtained by “I / I0=T=(1-R) 2 exp(-αL)". Therefore, by substituting the light transmittance T (=I / I0) measured in the above SCD or BLPCD, the thickness L of the SCD or BLPCD, and the light reflectance R inherent to the object (in the case of diamond, R=0.172) into the above formula, the light absorption coefficient α can be calculated. Based on the above, whether the SCD or BLPCD has a 3 cm wavelength relative to the laser wavelength used in the second irradiation condition described later is determined. -1 Over and less than 10cm -1The light absorption coefficient can be determined by calculating the light absorption coefficient α based on the above formula.

[0039] In the above-mentioned SCD and BLPCD, the content of impurity elements other than carbon is preferably 1% by mass or less. The content of the above-mentioned impurity elements is more preferably 0.5% by mass or less. The impurity elements are sometimes one or more metal elements selected from the group consisting of rare earth elements, alkaline earth metals, Co, Fe, Ni, Ti, W, Ta, Cr and V. Furthermore, the impurity elements are sometimes one or more non-metallic elements or semi-metallic elements selected from the group consisting of nitrogen, oxygen, boron, silicon and hydrogen. The content of impurity elements in the above-mentioned SCD and BLPCD may also be 0% by mass.

[0040] The method for determining the content of impurity elements is as follows. That is, by using secondary ion mass spectrometry (SIMS), first, in the SCD or BLPCD prepared as the blade tip, the secondary ion intensity (counts / sec) of the impurity element to be measured is measured. Furthermore, based on the measurement results, spectrum data of the impurity element is obtained as a graph in which the horizontal axis represents the analysis depth and the vertical axis represents the secondary ion intensity. Next, a known energy (kev) and dose (atoms / cm 2 ) A reference sample of the impurity element to be measured is ion-implanted into the SCD or BLPCD. Further, for the reference sample, the secondary ion intensity is measured under the same conditions as those for the measurement of the SCD or BLPCD, thereby obtaining the spectral data of the impurity element in the reference sample. Finally, by comparing the spectral data of the impurity element in the SCD or BLPCD with the spectral data of the impurity element in the reference sample, the content (atoms / cm 3 ).

[0041] Here, when the content of impurity elements other than carbon is 1 mass % or less, a 3 cm-long laser beam having a wavelength of 1.5 cm-1 with respect to the laser beam used in the second irradiation condition can be obtained with good yield. -1 Over and less than 10cm -1 The SCD and BLPCD having an absorption coefficient of light (laser) of 1.5 wt %. The SCD and BLPCD having an impurity element content other than carbon of 1 mass % or less can be obtained by a conventionally known production method.

[0042] (graphite)

[0043] The blade tip portion has graphite as described above. As described in detail in the item [Manufacturing method of diamond cutting tool] described later, the graphite can be generated by laser processing SCD or BLPCD under a first irradiation condition to obtain a blade tip portion having a cutting edge, and then laser processing the blade tip portion under a second irradiation condition different from the first irradiation condition.

[0044] Here, Figure 1 This is a graph showing the change in the ratio of graphite to the sum of SCD or BLPCD and graphite from the surface of the cutting edge toward the depth direction of the diamond cutting tool according to the present embodiment. Figure 1 As shown, in the blade tip, the graphite decreases approximately monotonically from the surface of the blade tip toward the depth direction in SCD or BLPCD and exists at least to a surface located at a depth of 1 μm from the surface of the blade tip. As a result, the blade tip can be endowed with lubricity based on graphite that can cope with initial wear and maintain the above lubricity, thereby improving the wear resistance of the diamond cutting tool. In this embodiment, Figure 1 Such a change in the ratio of graphite can be obtained as a ratio of graphite in the blade edge portion to the sum of the SCD or BLPCD and graphite (R=Ig / (Ig+Id)) based on Raman spectroscopic analysis described later.

[0045] on the other hand, Figure 1 The change in the ratio of graphite shown by the dotted line indicates that in this diamond cutting tool, a graphite layer (hereinafter also referred to as "conventional graphite layer") is actively deposited at the tip of the blade by conventional laser processing or the like. In this case, the thickness of the conventional graphite layer is as thin as about 100 nm. Figure 1 In the present invention, if the blade tip with the conventional graphite layer exceeds a depth of 100 nm from the surface of the blade tip, the ratio of graphite is sharply reduced. Therefore, the lubricity effect of the diamond cutting tool with the conventional graphite layer is temporary, and it is difficult to make the lubricity continue during processing.

[0046] Further, Figure 2 Yes Figure 1 The change in the ratio of graphite from the surface of the blade tip toward the depth direction in the diamond cutting tool according to the present embodiment shown in the graph is schematically reflected in the explanatory diagram showing a cross section of a portion of the blade tip (a portion of the back face) cut from the surface in the depth direction. Specifically, Figure 2, a cross section S cut from the surface (surface of the back face 11) in the depth direction in a part of the cutting edge portion 1 of the diamond cutting tool is enlarged and shown, thereby using the gray density (density of dots) to represent the change in the ratio of graphite in the cross section S. That is, in the cross section S, in the area where the gray appears darker due to the density of dots, the ratio of graphite is higher. Figure 2 It can be understood that in the cross section S, the ratio (content) of graphite decreases approximately monotonically from the surface of the flank 11 toward the depth direction, but exists at least from the surface of the flank 11 to a predetermined depth and does not become zero.

[0047] Here, in the present specification, the "surface of the blade tip" refers to the surface of the front cutting edge, the surface of the back cutting edge, and the surface of the cutting edge. However, the "surface of the blade tip" which is the analysis object of the Raman spectroscopic analysis described later is preferably the surface of the back cutting edge from the viewpoint of fully exerting the effect of the present disclosure. This is because the back cutting edge is the surface that faces the cut surface of the cut material during cutting, and therefore is required to have better wear resistance than the front cutting edge. In addition, compared with the cutting edge, the area in which Raman spectroscopic analysis can be performed is larger, so it is easier to be the analysis object than the cutting edge. That is, the above-mentioned surface is preferably the surface of the back cutting edge. Furthermore, in the present specification, the "surface" referred to as the "surface of the blade tip" refers to the outermost surface of the blade tip, and does not include the concept of thickness in the depth direction.

[0048] (R1, R2, and R3 obtained by Raman spectroscopy)

[0049] In the diamond cutting tool involved in the present embodiment, when the carbon constituting SCD or BLPCD is set as the first carbon and the carbon constituting the graphite is set as the second carbon as described above, and when Raman spectroscopic analysis is performed on the surface of the blade tip, the ratio R1 of the above Ig1 relative to the sum of the peak intensity Id1 of the above first carbon in the above surface and the peak intensity Ig1 of the above second carbon in the above surface is greater than or equal to 0.5 and less than or equal to 1. The above R1 refers to the ratio of the graphite in the surface of the blade tip to the sum of SCD or BLPCD and graphite, and can be expressed by the formula Ig1 / (Ig1+Id1). That is, in the present embodiment, the ratio of the graphite in the surface of the blade tip to the sum of SCD or BLPCD and graphite (R1=Ig1 / (Ig1+Id1)) is greater than or equal to 0.5 and less than or equal to 1.

[0050] The above R1 is preferably 0.7 or more and 1 or less, and more preferably 0.9 or more and 1 or less. When the above R1 is less than 0.5, the ratio of graphite in the surface of the blade tip portion becomes somewhat small, so it is difficult to obtain lubricity that can cope with initial wear. On the other hand, according to the formula of Ig1 / (Ig1+Id1), it is impossible for the above R1 to exceed 1.

[0051] Furthermore, in the blade tip, when Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of the Ig2 relative to the sum of the peak intensity Id2 of the first carbon located at a depth of 1 μm from the surface and the peak intensity Ig2 of the second carbon located at a depth of 1 μm from the surface is greater than or equal to 0.01 and less than or equal to 0.3. The R2 refers to the ratio of graphite located at a depth of 1 μm from the surface of the blade tip to the sum of SCD or BLPCD and graphite, and can be expressed by the formula Ig2 / (Ig2+Id2). That is, in the present embodiment, the ratio (R2=Ig2 / (Ig2+Id2)) of graphite located at a depth of 1 μm from the surface of the blade tip to the sum of SCD or BLPCD and graphite is greater than or equal to 0.01 and less than or equal to 0.3. In this specification, "a surface located at a depth of 1 μm from the surface of the blade tip" refers to a surface that is parallel to the surface of the blade tip at a distance of 1 μm in the depth direction. In addition, "a surface located at a depth of 1 μm from the surface of the blade tip" is a surface (surface to be measured) that is virtually set for Raman spectroscopic analysis and is exposed during Raman spectroscopic analysis as described later.

[0052] The above R2 is preferably 0.1 or more and 0.3 or less, and more preferably 0.15 or more and 0.25 or less. When the above R2 is less than 0.01, the ratio of graphite from the surface of the blade tip to the surface at a depth of 1 μm becomes somewhat small, so that lubricity is difficult to maintain during processing. When the above R2 exceeds 0.3, the ratio of graphite from the surface of the blade tip to the surface at a depth of 1 μm becomes too much, so it is difficult to obtain sufficient processing performance due to the decrease in hardness.

[0053] Here, in the present embodiment, the reason why the ratio of the graphite in the surface at a depth of 1 μm from the surface of the blade tip to the sum of SCD or BLPCD and graphite is specified as R2 is as follows. That is, the processing of the difficult-to-cut material to be cut using such a diamond cutting tool is called mirror finishing, etc., and most of them require finishing to a processing surface with a very small surface roughness. In this case, generally when the diamond cutting tool is used for processing the above-mentioned cut material until the surface at a depth of 1 μm from the surface of the blade tip is exposed, it is judged that the diamond cutting tool has reached the end of its life. Therefore, by specifying R2, it can be clearly determined whether the lubricity continues until it is judged that the diamond cutting tool has reached the end of its life.

[0054] The diamond cutting tool involved in this embodiment, when having the above-mentioned relationship between R1 and R2, that is, when R1 is greater than 0.5 and less than 1, and R2 is greater than 0.01 and less than 0.3, can obtain excellent lubricity based on graphite that can cope with initial wear at the cutting edge and the effect of maintaining the above-mentioned lubricity.

[0055] Specifically, first, lubricity sufficient to cope with initial wear can be obtained by setting the ratio (R1) of graphite in the surface of the cutting edge portion to 0.5 or more and 1 or less. This is because graphite occupies a majority of the surface of the cutting edge portion.

[0056] Furthermore, by making the ratio (R2) of graphite in the surface located at a depth of 1 μm from the surface of the blade tip portion 0.01 or more and 0.3 or less, excellent processing performance can be exerted. This is because SCD or BLPCD having a relatively high hardness accounts for the majority of the surface located at a depth of 1 μm from the surface of the blade tip portion. In addition, since graphite exists in the surface located at a depth of 1 μm from the surface of the blade tip portion, lubricity can also be maintained.

[0057] Next, in the tip portion of the diamond cutting tool, when Raman spectroscopic analysis is performed in a surface located at a depth of 0.5 μm from the surface, the ratio R3 of the Ig3 relative to the sum of the peak intensity Id3 of the first carbon located at a depth of 0.5 μm from the surface and the peak intensity Ig3 of the second carbon located at a depth of 0.5 μm from the surface is smaller than the R1 and larger than the R2. The R3 refers to the ratio of the graphite located at a depth of 0.5 μm from the surface of the tip portion to the sum of SCD or BLPCD and graphite, and can be expressed by the formula Ig3 / (Ig3+Id3). That is, in the present embodiment, the ratio (R3=Ig3 / (Ig3+Id3)) of the graphite located at a depth of 0.5 μm from the surface of the tip portion to the sum of SCD or BLPCD and graphite is preferably smaller than the R1 and larger than the R2. In other words, the diamond cutting tool involved in this embodiment preferably satisfies the relationship of R1>R3>R2. In this specification, "a surface located at a depth of 0.5 μm from the surface of the blade tip" refers to a surface parallel to the above surface at a distance of 0.5 μm from the surface of the blade tip in the depth direction. In addition, "a surface located at a depth of 0.5 μm from the surface of the blade tip" is a surface (measurement target surface) set virtually for Raman spectroscopic analysis, and is exposed during Raman spectroscopic analysis as described later.

[0058] The diamond cutting tool satisfies the relationship of R1>R3>R2, which means that a considerable amount of graphite exists in the SCD or BLPCD in the surface located at a depth of 0.5 μm from the surface of the blade tip, so lubricity can be maintained. Furthermore, SCD or BLPCD accounts for more than half of the surface located at a depth of 0.5 μm from the surface of the blade tip, so excellent processing performance can be exerted. On the other hand, in the case where the above R3 is larger than the above R1, the ratio of graphite in the surface located at a depth of 0.5 μm from the surface of the blade tip becomes too much, and it is possible that sufficient processing performance cannot be obtained due to the reduction in hardness. Alternatively, in the case where the above R3 is larger than the above R1, the ratio of graphite in the surface of the blade tip becomes somewhat small, and it is possible that it is difficult to obtain lubricity that can cope with initial wear.

[0059] Furthermore, when R3 is less than R2, the ratio of graphite in the surface at a depth of 0.5 μm from the surface of the blade tip becomes somewhat small, and lubricity may not be sustained during machining. Alternatively, when R3 is less than R2, the ratio of graphite in the surface at a depth of 1 μm from the surface of the blade tip becomes excessive, and sufficient machining performance may not be obtained due to a decrease in hardness. Specifically, R3 is preferably 0.1 or more and 0.75 or less, and more preferably greater than 0.3 and less than 0.5.

[0060] Specifically, a diamond cutting tool including a blade tip portion satisfying the above relationship of R1>R3>R2 is obtained by a diamond cutting tool manufacturing method described below. In view of the content of the manufacturing method, it is presumed that the graphite in the blade tip portion is Figure 1 as well as Figure 2 As shown in the figure, the graphite ratio in the SCD or BLPCD decreases approximately monotonically from the surface of the blade tip toward the depth direction and exists at least to a surface located at a depth of 1 μm from the surface of the blade tip. Therefore, in the present specification, when the graphite ratio in the blade tip satisfies the relationship of R1>R3>R2, the graphite in the blade tip is regarded as "approximately monotonically decreasing in the SCD or BLPCD from the surface of the blade tip toward the depth direction and exists at least to a surface located at a depth of 1 μm from the surface of the blade tip". Therefore, as long as the above-mentioned graphite ratio satisfies the above-mentioned relationship of R1>R3>R2, whether it is a case where the graphite ratio in the direction from the surface of the blade tip toward the depth direction is constant, or a case where the graphite ratio in the direction from the surface of the blade tip toward the depth direction is increased, as long as the effect of the present disclosure is achieved, any case does not deviate from the diamond cutting tool of the present embodiment.

[0061] The above graphite ratios (R1, R2, and R3) can be obtained by performing Raman spectroscopic analysis according to the following steps. First, regarding R1, a diamond cutting tool is obtained based on, for example, the manufacturing method of a diamond cutting tool described later, thereby preparing a sample to be measured. Next, the surface of the tip portion of the sample (the surface of the back face) is irradiated with a laser having a wavelength of 532 nm as excitation light at room temperature, thereby performing Raman spectroscopic analysis. In the above Raman spectroscopic analysis, based on the use of a 0.25 cm -1 The phonon peaks obtained by spectrum analysis using the following wave number resolution spectrometer (trade name: "LabRAM HR UV-VIS NIR", manufactured by Horiba, Ltd.) were fitted to a composite function of a Lorentzian function and a Gaussian function using the least squares method to obtain the peak intensities of diamond and graphite. Specifically, the peak at 1333 cm -1 The peak intensity of diamond (Id1) and the peak intensity of 1400-1700 cm -1 The peak intensity (Ig1) of graphite appearing near the flank is measured. R1 can be calculated from Id1 and Ig1 using the formula Ig1 / (Ig1+Id1). R1 ​​can be calculated from Ig1 / (Ig1+Id1) at any five locations on the flank surface and expressed as their average value.

[0062] Next, R2 can be obtained by the following method. First, the back face of the blade tip in the above-mentioned sample is ground to expose a surface at a depth of 1 μm from the surface of the blade tip, and the exposed surface is used as the measurement target surface. Raman spectroscopic analysis is performed on the measurement target surface in the same way as the method for obtaining R1, thereby R2 can be obtained according to the formula Ig2 / (Ig2+Id2). Regarding R3, the back face of the blade tip in the above-mentioned sample is ground to expose a surface at a depth of 0.5 μm from the surface of the blade tip, and the exposed surface is used as the measurement target surface. Raman spectroscopic analysis is performed on the measurement target surface in the same way as the method for obtaining R1, thereby R3 can be obtained according to the formula Ig3 / (Ig3+Id3). It should be noted that when performing the above-mentioned Raman spectroscopic analysis, it is preferred to obtain the values ​​in the order of R1, R3, and R2.

[0063] <Other structures in diamond cutting tools: base body>

[0064] As mentioned above, the diamond cutting tool has the situation that it also includes a base part while including the tip of the blade. As the base part of the diamond cutting tool, any base part known in the past as such a base part can be used. For example, the base part is preferably composed of any one of a superhard alloy (for example, including a WC-based superhard alloy, a superhard alloy containing Co or carbonitrides such as Ti, Ta, Nb in addition to WC), a cermet (cermet with TiC, TiN, TiCN, etc. as the main component), a high-speed steel, a ceramic (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, etc.), a cubic boron nitride sintered body or a diamond sintered body.

[0065] As the raw material of the matrix, it is preferred to select superhard alloy (especially WC-based superhard alloy) or cermet (especially TiCN-based cermet). The above raw materials have excellent balance between hardness and strength at high temperature, and the matrix of the diamond cutting tool for the above purposes has excellent characteristics. When using WC-based superhard alloy as the matrix, free carbon and abnormal layers such as η phase or ε phase may also be included in its organization.

[0066] Furthermore, the substrate may be a substrate whose surface is modified. For example, in the case of a superhard alloy, a de-β layer may be formed on the surface, and in the case of a metal ceramic, a surface hardened layer may be formed. The substrate exhibits the desired effect even if its surface is modified.

[0067] When the diamond cutting tool is a cutting tool such as a drill, the base body may be referred to as a shank or the like.

[0068] <Application of Diamond Cutting Tools>

[0069] The above-mentioned diamond cutting tools are not limited to the above-mentioned drill bits, and can be used as various cutting tools such as end mills (such as ball-end mills), replaceable cutting blades for drill bits, replaceable cutting blades for end mills, replaceable cutting blades for milling, replaceable cutting blades for turning, metalworking saws, gear cutting tools, reamers, taps, etc.

[0070] <Function>

[0071] In the diamond cutting tool of the present embodiment, the graphite decreases approximately monotonically from the surface of the blade tip toward the depth direction in the SCD or BLPCD and exists at least to a surface located at a depth of 1 μm from the surface of the blade tip. Thus, the blade tip can be provided with lubricity based on graphite that can cope with initial wear and the effect of maintaining the lubricity, thereby improving the wear resistance of the diamond cutting tool.

[0072] [Manufacturing method of diamond cutting tool]

[0073] The manufacturing method of the diamond cutting tool involved in the present embodiment can be manufactured by appropriately using the previously known method for manufacturing such a diamond cutting tool, except for the third step described later. That is, the manufacturing method of the diamond cutting tool described later generates graphite in the above-mentioned blade tip portion in a manner that is approximately monotonically reduced in the SCD or BLPCD from the surface of the blade tip portion toward the depth direction and at least to a surface that is 1 μm deep from the surface of the blade tip portion, thereby obtaining a diamond cutting tool with improved wear resistance. From the viewpoint of obtaining the above-mentioned diamond cutting tool with a good yield, the manufacturing method of the diamond cutting tool involved in the present embodiment preferably uses the following method.

[0074] The manufacturing method of the diamond cutting tool involved in this embodiment is the manufacturing method of the above-mentioned diamond cutting tool, wherein the manufacturing method includes: a process of preparing the above-mentioned SCD or BLPCD (first process); performing laser processing on the above-mentioned SCD or BLPCD under a first irradiation condition, thereby obtaining the above-mentioned blade tip portion with a cutting edge (second process); and performing laser processing on the above-mentioned blade tip portion under a second irradiation condition different from the above-mentioned first irradiation condition, thereby generating graphite on the above-mentioned blade tip portion (third process).

[0075] <First step>

[0076] This process is a process for preparing SCD or BLPCD. Both SCD and BLPCD can be prepared by using a previously known manufacturing method for obtaining the SCD and BLPCD. For example, SCD can be prepared by using a previously known HTHP method, a CVD method, etc. Furthermore, BLPCD can be prepared by converting graphite into diamond particles by sintering it using a previously known HTHP method as a starting material, and combining the diamond particles with each other. For example, in the case where the diamond cutting tool is a tip-replaceable cutting blade for turning, the SCD and BLPCD are preferably prepared as a blade shape with a length of 2 to 6 mm, a width of 1 to 6 mm, and a thickness of 0.3 to 2 mm. For example, in the case where the diamond cutting tool is a drill bit, the SCD and BLPCD are preferably prepared as a cylindrical shape with a length of 0.5 to 5 mm and a diameter of 0.5 to 5 mm.

[0077] As described above, the above-mentioned SCD and BLPCD can be obtained by a conventionally known manufacturing method. However, from the viewpoint of giving full play to the effect of the present disclosure, it is preferred to select an SCD and a BLPCD obtained by a conventionally known manufacturing method that have a wavelength of 3 cm relative to the laser used in the second irradiation condition described later. -1 Over and less than 10cm -1 The SCD and BLPCD are prepared based on the SCD and BLPCD of the light absorption coefficient.

[0078] This process preferably includes a process of joining the above-mentioned SCD or BLPCD to the base part by means such as brazing (base part joining process). The base part can be prepared using previously known materials such as superhard alloy as described above. For example, as the material of the above-mentioned base part, IGETALLOY (registered trademark, material types: G10E, AFU, etc.) manufactured by Sumitomo Electric Industries, Ltd. can be preferably used. The shape of the base part can be formed corresponding to the shape of the above-mentioned SCD and BLPCD. Here, the above-mentioned base part joining process can also be performed after graphite is generated at the tip of the blade in the third process described later, instead of being performed in this process.

[0079] <Second step>

[0080] This process is a process of obtaining the above-mentioned blade tip portion with a cutting edge by laser processing the above-mentioned SCD or BLPCD under the first irradiation condition. Specifically, first, the above-mentioned SCD or BLPCD is installed in a conventionally known laser processing machine (for example, the product name "PreCutter", manufactured by LASERPLUS). Further, the surface of the above-mentioned SCD or BLPCD is processed by scanning with the laser of the above-mentioned laser processing machine under the first irradiation condition, thereby forming a cutting edge on the SCD or BLPCD. In this way, a blade tip portion with a cutting edge can be obtained.

[0081] As the first irradiation condition, conventionally known conditions can be used. For example, the following first irradiation conditions can be used: the laser wavelength is 532 nm or more and 1064 nm or less, the laser spot diameter is 5 μm or more and 70 μm or less in half-value width, the laser focus depth is 0.5 mm or more and 20 mm or less, the laser output at the processing point is 1 W or more and 20 W or less, and the laser scanning speed is 5 mm / s or more and 100 mm / s or less.

[0082] <Third step>

[0083] This process is a process for generating graphite at the tool tip by laser processing the tool tip under a second irradiation condition different from the first irradiation condition. Specifically, first, the tool tip is mounted on the laser processing machine or a second laser processing machine different from the laser processing machine. Then, the surface of the tool tip is scanned and processed using the laser of the laser processing machine or the second laser processing machine under the second irradiation condition, thereby generating graphite at the tool tip.

[0084] The second irradiation condition is preferably a laser wavelength of 532nm or more and 1064nm or less, a laser spot diameter of 5μm or more and 70μm or less in half-value width, a laser focus depth of 1mm or more, a laser output of 1W or more and 20W or less at the processing point, and a laser scanning speed of 5mm / second or more and 100mm / second or less. The second irradiation condition is more preferably a laser wavelength of 532nm or 1064nm, a laser spot diameter of 10 to 50μm in half-value width, a laser focus depth of 1.5mm or more, a laser output of 2 to 10W, and a laser scanning speed of 30 to 100mm / min. The upper limit of the laser focus depth is not particularly limited and may be 20mm or less. As a laser pulse width, it is preferably 1f (femto) seconds or more and 1μ seconds or less. As a laser repetition frequency, it is preferably 10Hz or more and 1MHz or less.

[0085] In the above-mentioned second irradiation condition, when the laser spot diameter is less than 5 μm in half-value width, due to the low laser power, there is a tendency that it is difficult to form a distribution in which graphite decreases approximately monotonically from the surface of the blade tip toward the depth direction in SCD or BLPCD and exists to a predetermined depth. When the laser spot diameter exceeds 70 μm in half-value width, due to the high laser power, there is a tendency that SCD or BLPCD breaks. When the laser focus depth is less than 1 mm, there is a tendency that it is difficult to form a distribution in which graphite decreases approximately monotonically from the surface of the blade tip toward the depth direction in SCD or BLPCD and exists to a predetermined depth due to defocusing. When the laser output is less than 1 W at the processing point, due to the low laser power, there is a tendency that it is difficult to form a distribution in which graphite decreases approximately monotonically from the surface of the blade tip toward the depth direction in SCD or BLPCD and exists to a predetermined depth. When the laser output exceeds 20 W at the processing point, due to the high laser power, there is a tendency that SCD or BLPCD breaks.

[0086] When the laser scanning speed is less than 5 mm / sec, there is a tendency for the laser to penetrate too deeply into the SCD or BLPCD and cause the SCD or BLPCD to break. When it exceeds 100 mm / sec, there is a tendency for almost no laser-based processing to be performed. When the laser pulse width is less than 1f seconds, the SCD or BLPCD tends to break due to the high laser power. When it exceeds 1μ seconds, thermal processing dominates and there is a tendency for the SCD or BLPCD to break. When the laser repetition frequency is less than 10 Hz, thermal processing dominates and there is a tendency for the SCD or BLPCD to break. When the laser repetition frequency exceeds 1 MHz, the next laser pulse arrives before the energy of the irradiated laser pulse is consumed at the processing point, so the heat load at the processing point becomes large, and it is difficult to form a distribution in which graphite decreases roughly monotonically from the surface of the blade tip toward the depth direction in the SCD or BLPCD and exists to a predetermined depth.

[0087] In this step, it is preferred to perform laser processing on the blade tip portion formed by SCD or BLPCD having a wavelength of 3 cm with respect to the laser used in the second irradiation condition. -1 Over and less than 10cm -1 In this case, the laser light travels from the surface of the blade tip toward the depth direction, thereby being able to penetrate into the inside of the blade tip. When the laser light penetrating into the inside of the blade tip has an energy exceeding the threshold value for graphitizing diamond in the penetrated region, the SCD or BLPCD in the region can be graphitized.

[0088] On the other hand, the deeper the laser travels from the surface of the blade tip toward the depth direction, the more energy it loses. Therefore, the deeper the laser travels from the surface of the blade tip toward the depth direction, the less it can graphitize the SCD or BLPCD in that area. If this is graphed, it can be expressed as follows: Figure 1 The change in the ratio of graphite to SCD or the sum of BLPCD and graphite as shown.

[0089] Here, the first irradiation condition for performing laser processing on the above-mentioned SCD or BLPCD and the second irradiation condition for performing laser processing on the above-mentioned blade tip portion include overlapping ranges in various parameters, but in this process, as long as the laser processing is performed under conditions different from the first irradiation condition, the effect of the present disclosure can be exerted. This is because the first irradiation condition is a laser processing of forming a blade tip portion having the above-mentioned cutting edge by a blocky SCD or BLPCD, and in contrast, the second irradiation condition is a laser processing of generating graphite at a predetermined ratio from the surface of the above-mentioned blade tip portion toward the depth direction, so the energy of the laser in the irradiated portion (SCD or BLPCD, or blade tip portion) is naturally used differently. Specifically, in the laser processing under the first irradiation condition, the surface roughly perpendicular to the laser beam becomes the main irradiated portion, so the power density is relatively high. In contrast, in the laser processing under the second irradiation condition, the surface roughly horizontal to the laser beam becomes the main irradiated portion, so the power density becomes relatively low.

[0090] <Effects>

[0091] The diamond cutting tool involved in the present embodiment can be obtained by the above manufacturing method. In the diamond cutting tool obtained by the above manufacturing method, the blade tip portion composed of SCD or BLPCD is laser processed by the above second irradiation condition, so that the graphite in the blade tip portion can be roughly monotonically reduced from the surface of the blade tip portion toward the depth direction in the SCD or BLPCD and exists at least to a surface located at a depth of 1 μm from the surface of the blade tip portion. Therefore, by the above manufacturing method, it has excellent lubricity that can cope with initial wear based on the above graphite, and the above lubricity is sustained, thereby obtaining a diamond cutting tool with improved wear resistance.

[0092] [Note]

[0093] The above description includes the following additional embodiments.

[0094] <Additional Note 1>

[0095] A diamond cutting tool comprises a blade tip portion, wherein the blade tip portion comprises single crystal diamond or binderless polycrystalline diamond and graphite, wherein:

[0096] The carbon constituting the single crystal diamond or the binderless polycrystalline diamond is defined as first carbon, and the carbon constituting the graphite is defined as second carbon,

[0097] When Raman spectroscopic analysis is performed on the surface of the blade tip, a ratio R1 of the Ig1 relative to the sum of the peak intensity Id1 of the first carbon on the surface and the peak intensity Ig1 of the second carbon on the surface is greater than or equal to 0.5 and less than or equal to 1,

[0098] When Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of Ig2 to the sum of a peak intensity Id2 of the first carbon in the surface located at a depth of 1 μm from the surface and a peak intensity Ig2 of the second carbon in the surface located at a depth of 1 μm from the surface is greater than 0.01 and less than 0.3.

[0099] <Note 2>

[0100] The diamond cutting tool according to Supplementary Note 1, wherein R1 is greater than or equal to 0.7 and less than or equal to 1.

[0101] <Addendum 3>

[0102] The diamond cutting tool according to Supplementary Note 1 or Supplementary Note 2, wherein R1 is 0.9 or more and 1 or less.

[0103] <Addendum 4>

[0104] The diamond cutting tool according to any one of Supplementary Notes 1 to 3, wherein R2 is 0.1 or more and 0.3 or less.

[0105] <Addendum 5>

[0106] The diamond cutting tool according to any one of Supplementary Notes 1 to 4, wherein R2 is 0.15 or more and 0.25 or less.

[0107] <Addendum 6>

[0108] A diamond cutting tool according to any one of Notes 1 to 5, wherein, when Raman spectroscopic analysis is performed in a surface located at a depth of 0.5 μm from the above-mentioned surface, a ratio R3 of the above-mentioned Ig3 to the sum of the peak intensity Id3 of the above-mentioned first carbon in the surface located at a depth of 0.5 μm from the above-mentioned surface and the peak intensity Ig3 of the above-mentioned second carbon in the surface located at a depth of 0.5 μm from the above-mentioned surface is greater than 0.1 and less than 0.75.

[0109] <Addendum 7>

[0110] The diamond cutting tool according to any one of Supplementary Notes 1 to 6, wherein the R3 is greater than 0.3 and less than 0.5.

[0111] <Addendum 8>

[0112] The diamond cutting tool according to any one of Supplementary Notes 1 to 7, wherein the single crystal diamond or the binderless polycrystalline diamond has a 3 cm -1 Over and less than 10cm -1 The absorption coefficient of light.

[0113] Example

[0114] The present disclosure is described in more detail below by listing examples, but the present disclosure is not limited to these examples. In the following examples and comparative examples, two diamond cutting tools are manufactured respectively. Furthermore, in the examples and comparative examples, one of the two diamond cutting tools is used for the measurement of the surface roughness Ra of the flank and the cutting test, and the other is used for the measurement of the ratio (R1, R2 and R3) of graphite in the SCD or BLPCD in the blade tip.

[0115] 〔Manufacture of diamond cutting tools〕

[0116] <Example 1>

[0117] (First process)

[0118] By using the conventionally known HTHP method, a block of BLPCD in the shape of a blade of CCMW09T304 specified by ISO (International Organization for Standardization) is prepared. The BLPCD is joined to a base portion formed by processing a superhard alloy using IGETALLOY (registered trademark, material type: G10E) manufactured by Sumitomo Electric Industries, Ltd. by brazing, thereby producing a workpiece for the second step described later. For the above-mentioned BLPCD, the absorption coefficient of light with a laser wavelength of 1064nm is obtained by the above-mentioned measurement method, which is 3cm -1 .

[0119] (Second process)

[0120] Using a processing machine with the same performance as the above-mentioned laser processing machine, the surface of the BLPCD in the above-mentioned workpiece is scanned with a laser under the following first irradiation conditions, thereby performing laser processing. As a result, a cutting edge portion having a rake face, a flank face, and a cutting edge formed between the rake face and the flank face is formed on the BLPCD, thereby obtaining a diamond cutting tool precursor for the third step described later.

[0121] The first irradiation conditions are as follows.

[0122] Laser wavelength: 1064nm

[0123] Laser spot diameter: 50μm (half-value width)

[0124] Laser focus depth: 1.5μm

[0125] Laser output: 10W (processing point)

[0126] Laser scanning speed: 50mm / min

[0127] (Third process)

[0128] The cutting edge of the diamond cutting tool precursor was laser processed by scanning with laser light using the laser processing machine under the following second irradiation conditions. Graphite was generated on the cutting edge, thereby obtaining the diamond cutting tool (cutting edge replaceable cutting insert for turning) of Example 1.

[0129] The second irradiation conditions are as follows.

[0130] Laser wavelength: 1064nm

[0131] Laser spot diameter: 40μm (half-value width)

[0132] Laser focus depth: 1.5μm

[0133] Laser output: 5W (processing point)

[0134] Laser scanning speed: 10mm / min

[0135] Laser pulse width: 10ps (picoseconds)

[0136] Laser repetition frequency: 200kHz

[0137] <Example 2>

[0138] Prepare a light absorption coefficient of 7cm for a 532nm laser wavelength. -1 A diamond cutting tool was obtained by using the same method as in Example 1, except that the second irradiation condition was set as follows.

[0139] The second irradiation conditions are as follows.

[0140] Laser wavelength: 532nm

[0141] Laser spot diameter: 40μm (half-value width)

[0142] Laser focus depth: 1.5μm

[0143] Laser output: 6W (processing point)

[0144] Laser scanning speed: 8mm / min

[0145] Laser pulse width: 10ps (picoseconds)

[0146] Laser repetition frequency: 50Hz

[0147] <Example 3>

[0148] Prepare a laser with a wavelength of 1064 nm and a light absorption coefficient of 9 cm -1 A diamond cutting tool was obtained by using the same method as in Example 1 except for the above.

[0149] <Example 4>

[0150] Prepare a laser with a wavelength of 532 nm and a light absorption coefficient of 5 cm -1 A diamond cutting tool is obtained by using the same method as in Example 1 except that the SCD is set to the same as in Example 2 and the second irradiation conditions are the same as in Example 2.

[0151] <Comparative Example 1 and Comparative Example 2>

[0152] Prepare a laser with a wavelength of 532 nm and a light absorption coefficient of 15 cm -1 A diamond cutting tool is obtained by using the same method as in Example 1 except that the second irradiation conditions are the same as in Example 2.

[0153] <Comparative Example 3>

[0154] Prepare a laser with a wavelength of 532 nm and a light absorption coefficient of 20 cm -1 A diamond cutting tool is obtained by using the same method as in Example 1 except that the SCD is set to the same as in Example 2 and the second irradiation conditions are the same as in Example 2.

[0155] <Comparative Example 4>

[0156] Prepare a light absorption coefficient of 1 cm for a laser wavelength of 532 nm. -1 A diamond cutting tool is obtained by using the same method as in Example 1 except that the SCD is set to the same as in Example 2 and the second irradiation conditions are the same as in Example 2.

[0157] <Comparative Example 5>

[0158] Prepare a light absorption coefficient of 1 cm for a laser wavelength of 1064 nm. -1A diamond cutting tool was obtained by using the same method as in Example 1 except for the above.

[0159] [Measurement of surface roughness Ra of the back face]

[0160] For the diamond cutting tools of Examples 1 to 4 and Comparative Examples 1 to 5, three measurement areas were set on the back face of the blade tip, and the surface roughness Ra of the measurement area was calculated according to JIS B 0601 (2001) using a laser microscope (trade name: "OLS5000", manufactured by Olympus Corporation). The results are shown in Table 1. The value of "back face surface roughness Ra" in Table 1 is the average value of the surface roughness Ra measured in the measurement areas of the above three locations. When the value of "back face surface roughness Ra" in Table 1 is less than 0.1 μm, it can be evaluated that the diamond cutting tools produced in each of the Examples and Comparative Examples have at least the performance of mirror finishing the cut material.

[0161] 〔Cutting test〕

[0162] Using the diamond cutting tools of Examples 1 to 4 and Comparative Examples 1 to 5, a round bar material ( The hardness (HRA) is 87, manufactured by Sumitomo Electric Industries, Ltd.) for cutting. In this cutting test, the cutting is stopped at the time point when the cutting distance of the above-mentioned cut material reaches 1 km, and the maximum wear width (in μm) of the back face of the diamond cutting tool at this time point is magnified and observed using a microscope, thereby measuring. The results are shown in Table 1. The smaller the value of the above-mentioned maximum wear width of the back face, the more it can be evaluated as improved wear resistance. In Table 1, the "maximum wear width of the back face" of the diamond cutting tool is indicated in the item of "back face wear width (μm)".

[0163] <Cutting conditions>

[0164] Processing machine: NC lathe

[0165] Cutting speed: 20m / min

[0166] Feed speed: 0.05mm / rev

[0167] Cutting amount: 0.2mm / rev

[0168] Cutting oil (coolant): None (however, in the cutting test using the diamond cutting tool of Comparative Example 2, a water-soluble emulsion was used).

[0169] 〔Graphite ratio (R1, R2, R3)〕

[0170] For the tip of the diamond cutting tool of Examples 1 to 4 and Comparative Examples 1 to 5, the ratios of graphite in SCD or BLAPCD (R1, R3, and R2) were obtained using the above method on the surface of the tip (flank), the surface at a depth of 0.5 μm from the surface of the tip (flank), and the surface at a depth of 1 μm from the surface of the tip (flank). The results are shown in Table 1.

[0171]

[0172] 〔Investigation〕

[0173] According to Table 1, the diamond cutting tools of Examples 1 to 4 and Comparative Examples 1 to 5 all have the same degree of surface roughness Ra of the flank. The R1 of the diamond cutting tools of Examples 1 to 4 is 0.5 or more and 1 or less, and R2 is 0.01 to 0.3. Furthermore, R3 is less than R1 and greater than R2. On the other hand, the R1 of the diamond cutting tools of Comparative Examples 1 to 3 is 1, and R2 is 0. In this case, the diamond cutting tools of Examples 1 to 4 have a smaller maximum wear width of the flank than the diamond cutting tools of Comparative Examples 1 to 3. Comparative Examples 4 and 5 are diamond cutting tools with R1 less than 0.5 or R2 exceeding 0.3, and have a larger maximum wear width of the flank than the diamond cutting tools of Examples 1 to 4. Therefore, it can be evaluated that the diamond cutting tools of Examples 1 to 4 have improved wear resistance compared with the diamond cutting tools of Comparative Examples 1 to 5. It should be noted that the diamond cutting tool of Comparative Example 2 was manufactured using the same method as Comparative Example 1 as described above, but the maximum wear width of the flank was larger than that of Comparative Example 1. The reason for this is presumably that the cutting test was performed without causing a decrease in the hardness of the cut material due to a temperature rise by cooling the cut material with a coolant.

[0174] As mentioned above, although the embodiment and the example of this disclosure were described, it is also planned from the beginning that the configurations of each embodiment and the example described above are appropriately combined or variously modified.

[0175] The embodiments and examples disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is not represented by the above-mentioned embodiments and examples, but by the technical solutions, and is intended to include all changes within the meaning and scope equivalent to the technical solutions.

[0176] Description of Reference Numerals

[0177] 1: tool tip; 11: back surface; S: cross section.

Claims

1. A diamond cutting tool comprising a blade tip portion, wherein the blade tip portion comprises single crystal diamond or binderless polycrystalline diamond and graphite, wherein: The carbon constituting the single crystal diamond or the binderless polycrystalline diamond is defined as first carbon, and the carbon constituting the graphite is defined as second carbon, When Raman spectroscopic analysis is performed on the surface of the blade tip, a ratio R1 of the Ig1 relative to the sum of the peak intensity Id1 of the first carbon on the surface and the peak intensity Ig1 of the second carbon on the surface is greater than or equal to 0.5 and less than or equal to 1, When Raman spectroscopic analysis is performed on a surface located at a depth of 1 μm from the surface, a ratio R2 of Ig2 to the sum of a peak intensity Id2 of the first carbon in the surface located at a depth of 1 μm from the surface and a peak intensity Ig2 of the second carbon in the surface located at a depth of 1 μm from the surface is greater than 0.01 and less than 0.

3.

2. The diamond cutting tool according to claim 1, characterized in that When Raman spectroscopic analysis is performed on a surface located at a depth of 0.5 μm from the surface, a ratio R3 of the Ig3 to the sum of the peak intensity Id3 of the first carbon in the surface located at a depth of 0.5 μm from the surface and the peak intensity Ig3 of the second carbon in the surface located at a depth of 0.5 μm from the surface is smaller than R1 and larger than R2.

3. The diamond cutting tool according to claim 1 or 2, characterized in that: The surface is the surface of the flank.

4. The diamond cutting tool according to claim 1 or 2, characterized in that: The ratio R1 is greater than or equal to 0.7 and less than or equal to 1.

5. The diamond cutting tool according to claim 1 or 2, characterized in that: The ratio R1 is greater than or equal to 0.9 and less than or equal to 1.

6. The diamond cutting tool according to claim 1 or 2, characterized in that: The ratio R2 is greater than or equal to 0.1 and less than or equal to 0.

3.

7. The diamond cutting tool according to claim 1 or 2, characterized in that: The ratio R2 is greater than or equal to 0.15 and less than or equal to 0.

25.

8. The diamond cutting tool according to claim 1 or 2, characterized in that: When Raman spectroscopic analysis is performed on a surface located at a depth of 0.5 μm from the surface, a ratio R3 of Ig3 to the sum of a peak intensity Id3 of the first carbon in the surface located at a depth of 0.5 μm from the surface and a peak intensity Ig3 of the second carbon in the surface located at a depth of 0.5 μm from the surface is greater than 0.1 and less than 0.

75.

9. The diamond cutting tool according to claim 1 or 2, characterized in that: When Raman spectroscopic analysis is performed on a surface located at a depth of 0.5 μm from the surface, a ratio R3 of Ig3 to the sum of the peak intensity Id3 of the first carbon in the surface located at a depth of 0.5 μm from the surface and the peak intensity Ig3 of the second carbon in the surface located at a depth of 0.5 μm from the surface is greater than 0.3 and less than 0.

5.

10. The diamond cutting tool according to claim 1 or 2, characterized in that: The single crystal diamond or the binder-free polycrystalline diamond has a 3 cm -1 Over and less than 10cm -1 The absorption coefficient of light.

11. A method for manufacturing a diamond cutting tool, which is the method for manufacturing a diamond cutting tool according to any one of claims 1 to 10, characterized in that: The manufacturing method comprises: A step of preparing the single crystal diamond or the binderless polycrystalline diamond; A step of performing laser processing on the single crystal diamond or the binderless polycrystalline diamond under a first irradiation condition to obtain the blade tip portion having a cutting edge formed thereon; and The step of performing laser processing on the blade tip portion under a second irradiation condition different from the first irradiation condition, thereby generating graphite on the blade tip portion.

12. The method for manufacturing a diamond cutting tool according to claim 11, characterized in that: As the second irradiation condition, The laser wavelength is between 532nm and 1064nm. The laser spot diameter is 5 μm or more and 70 μm or less in half-value width. The laser focus depth is more than 1mm. The laser output at the processing point is 1W or more and 20W or less. The laser scanning speed is 5 mm / s or more and 100 mm / s or less. The laser repetition frequency is 10 Hz or more and 1 MHz or less.

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