Metal processing tool and method for manufacturing metal processing tool

Abstract

In the present invention, a cutting blade has a blade edge coated with a diamond thin film. The particle size of nano polycrystalline diamonds constituting the diamond thin film is 5nm to 300nm. The film thickness of the diamond thin film is 0.5μｍ to 5μｍ. The blade edge curvature is 0.5μｍ to 5μｍ.

Description

Metalworking tool and method for manufacturing the same

[0001] The present invention relates to a metalworking tool and a method for manufacturing a metalworking tool.

[0002] Conventionally, metalworking tools are used to cut or shape workpieces, such as films or sheet materials. Examples of metalworking tools include cutting blades, such as slitters or Thomson blades, and dies, such as press dies or punches. To improve the quality of the workpieces or the hardness of the metalworking tools, the ends of the metalworking tools have been coated with a thin film, such as a nitride film (e.g., TiN, TiAlN, CrN, etc.) or diamond-like carbon (DLC), to enhance the wear resistance and lifespan of the metalworking tools.

[0003] In recent years, thin films containing even harder metals or carbon-based materials have also been used, and specifically, metalworking tools with their ends coated with diamond thin films have been proposed. For example, as shown in Patent Document 1, a diamond thin film made of polycrystalline diamond with a grain size of about 1 μm to 10 μm is synthesized using a filament CVD device or the like, and the diamond thin film is used to coat the ends.

[0004] Also, as shown in Patent Document 2, for example, the curvature indicating the roundness of the end is controlled to a range of 0.1 μm to 10 μm, and the end is coated with a diamond thin film made of polycrystalline diamond with a grain size of about 1 μm to 10 μm. In this way, the sharp end is coated with the diamond thin film, improving the quality of the cut surface of the object to be processed.

[0005] JP 2019-181574 A JP 2019-048361 A

[0006] However, as shown in Patent Document 1, when the grain size of the polycrystalline diamond is about 1 μm to 10 μm, the thickness of the diamond thin film becomes 10 μm or more. If the film thickness is 10 μm, it becomes difficult to maintain the sharpness of the edge, so the cut surface of the object to be processed becomes irregular, and there is a risk of the quality of the object to be processed decreasing.

[0007] Furthermore, as shown in Patent Document 2, even if an attempt is made to control the curvature of the edge to a range of 0.1 μm to 10 μm and make the film thickness 10 μm or less, the grain size of the polycrystalline diamond that makes up the diamond thin film is about 1 μm to 10 μm, and the polycrystalline diamond particles are difficult to bond together. Therefore, the surface of the diamond thin film that covers the edge deviates from the curvature of the edge, making it difficult to maintain the sharpness of the edge of the metalworking tool.

[0008] Furthermore, when a diamond thin film having a thickness of 10 μm or less is made of polycrystalline diamond, the polycrystalline diamonds are difficult to bond together and tend to fall off from the diamond thin film, making it difficult to maintain the strength of the diamond thin film and reducing the wear resistance of the edge.

[0009] The present invention has been made to solve the above problems, and its main object is to maintain the sharpness of the edge of a metalworking tool and to improve the wear resistance of the edge.

[0010] That is, the metalworking tool according to the present invention is a metalworking tool having an end portion coated with a diamond thin film, and the average grain size of the nano-polycrystalline diamond constituting the diamond thin film is 5 nm or more and 900 nm or less or equal to the curvature of the end portion, the film thickness of the diamond thin film is 0.5 μm or more and 5 μm or less, and in Raman spectroscopic analysis with 325 nm excitation, the diamond thin film has a peak intensity derived from diamond that is 0.8 to less than 500 times the peak intensity of the G band derived from diamond-like carbon, the hardness of the diamond thin film is 30 GPa or more and 100 GPa or less, and the curvature of the end portion is 0.5 μm or more and 5 μm or less.

[0011] With this configuration, the edge of the metalworking tool is coated with a diamond thin film, thereby improving the wear resistance of the edge of the metalworking tool compared to metalworking tools coated with a nitride film or DLC. Furthermore, since the nano-polycrystalline diamond has a grain size of 300 nm or less, the nano-polycrystalline diamonds can be bonded together. Therefore, the nano-polycrystalline diamond can be prevented from falling off the diamond thin film, and the strength of the diamond thin film can be maintained even when the diamond thin film is thinned to 5 μm or less. As a result, in the above-mentioned metalworking tool, the edge curvature can be set to 5 μm or less to maintain the edge sharpness and wear resistance. Meanwhile, due to the limitations of diamond thin film production, the lower limit of the grain size of the nano-polycrystalline diamond is set to 5 nm. Furthermore, in order to maintain the bond between the nano-polycrystalline diamonds, the lower limit of the diamond thin film thickness is set to 0.5 μm, and the lower limit of the edge curvature is set to 0.5 μm. Furthermore, in the Raman spectroscopy analysis of diamond thin film with 325 nm excitation, the peak intensity of diamond-derived is 0.8 times or more and less than 500 times the peak intensity of the G band derived from diamond-like carbon, so that the crystallinity of diamond thin film can be improved.In addition, the hardness of diamond thin film is 30 GPa or more and 100 GPa or less, so that the life of metalworking tool can be extended.In addition, in order to suppress the frequency of chipping of metalworking tool and extend the life of metalworking tool, the hardness of diamond thin film is preferably 35 GPa or more and 70 GPa or less.

[0012] In order to improve the adhesion between the diamond thin film and the substrate of the metal-working tool, it is preferred that the substrate of the metal-working tool is a material containing iron or a cemented carbide containing tungsten carbide and cobalt, that chromium or titanium is formed on the substrate to a thickness of 0.01 to 1.5 μm, and that the diamond thin film is coated on the chromium or titanium formed on the substrate.

[0013] It is preferable that the substrate of the metalworking tool is a cemented carbide containing tungsten carbide and cobalt, the average grain size of the tungsten carbide in the substrate is 0.1 μm or more and 1.5 μm or less, the average cobalt content in the substrate is 1% or more and 5.5% or less, the cobalt-free layer in the substrate is 5 μm or less or the curvature of the end portion, the average surface roughness of the unevenness on the surface of the substrate is 0.1 μm or more and 3 μm or the curvature of the end portion, and the substrate is coated with a diamond thin film.

[0014] With this configuration, the average grain size of tungsten carbide in the substrate is 0.1 μm or more and 1.5 μm or less, and the average cobalt content in the substrate is 1% or more and 5.5% or less, so the mechanical strength of the metalworking tool can be maintained even if the curvature of the edge is small. Also, since the cobalt-free layer in the substrate is 5 μm or less or less than the curvature of the edge, the diamond thin film can be grown by CVD while maintaining high adhesion to the substrate. Furthermore, since the average surface roughness of the unevenness on the surface of the substrate is 0.1 μm or more and 3 μm or less than the curvature of the edge, the anchor effect of the unevenness can further increase the adhesion between the diamond thin film and the substrate.

[0015] In addition, a specific embodiment of the metalworking tool is one in which the length of the end portion in the longitudinal direction is 30 cm or more.

[0016] A specific embodiment of the metalworking tool is a cutting blade whose cutting edge is coated with a diamond thin film, and / or a mold whose end is coated with a diamond thin film.

[0017] Furthermore, a method for manufacturing a metalworking tool having an end portion coated with a diamond thin film includes supplying a source gas containing carbon, hydrogen, oxygen, and a rare gas into a vacuum chamber in which the end portion is placed, generating an inductively coupled plasma in the vacuum chamber by passing a high-frequency current through an antenna disposed inside or outside the vacuum chamber, the antenna having a conductor element and a capacitance element electrically connected in series with each other, and synthesizing the diamond thin film by a plasma CVD method using the generated inductively coupled plasma, and coating the end portion with the diamond thin film, characterized in that the grain size of the nano-polycrystalline diamond constituting the diamond thin film is 5 nm to 900 nm or less or less than the curvature of the end portion, the thickness of the diamond thin film is 0.5 μm to 5 μm, and the curvature of the end portion is 0.5 μm to 5 μm. In addition to the effects similar to those of the metalworking tool described above, this configuration uses an antenna having a conductor element and a capacitance element electrically connected in series with each other, so that plasma is generated more uniformly in the longitudinal direction of the antenna than in a configuration using a conventional plasma CVD apparatus. As a result, it is possible to manufacture a metalworking tool in which the end portion of the metalworking tool that is longer in the longitudinal direction is coated with a diamond thin film.

[0018] As a specific embodiment of the metalworking tool to be manufactured, it is preferable that the length of the end portion in the longitudinal direction is 30 cm or more.

[0019] The method for producing the metalworking tool may include coating the substrate of the metalworking tool with chromium or titanium, and synthesizing the diamond thin film by plasma CVD using inductively coupled plasma.

[0020] With this configuration, it is possible to obtain the same effects as the above-mentioned metalworking tool.

[0021] The method for manufacturing the metalworking tool includes coating the substrate of the metalworking tool with chromium or titanium, surface treating the substrate with inductively coupled plasma containing hydrogen and argon, and synthesizing the diamond thin film by a plasma CVD method using the inductively coupled plasma.

[0022] With this configuration, it is possible to obtain the same effects as the above-mentioned metalworking tool.

[0023] A method for manufacturing the metalworking tool includes forming a cobalt-free layer by chemical etching on a substrate of the metalworking tool made of a cemented carbide containing tungsten carbide and cobalt, and synthesizing the diamond thin film by a plasma CVD method using inductively coupled plasma.

[0024] With this configuration, it is possible to obtain the same effects as the above-mentioned metalworking tool.

[0025] According to the present invention configured as described above, in a metalworking tool, the sharpness of the edge can be maintained and the wear resistance of the edge can be improved.

[0026] 1 is a perspective view of a cutting blade according to an embodiment of the present invention; FIG. 2 is a perspective view of a mold according to the embodiment; FIG. 3 is an enlarged cross-sectional view taken along line A-A in FIG. 1 showing the cutting edge portion of the cutting blade according to the embodiment; FIG. 4 is an enlarged cross-sectional view taken along line B-B in FIG. 2 showing the end portion of the mold according to the embodiment; FIG. 5 is a diagram schematically showing the configuration of a film-forming apparatus according to the embodiment; and FIG. 6 is a diagram showing the gas composition range of a raw material gas supplied in the film-forming apparatus and the method for manufacturing a metal processing tool according to the embodiment.

[0027] Hereinafter, a metalworking tool and a method for manufacturing a metalworking tool according to an embodiment of the present invention will be described with reference to the drawings. Note that in any of the drawings shown below, some parts may be omitted or exaggerated in schematic form for ease of understanding. Identical components will be assigned the same reference numerals and their description will be omitted as appropriate.

[0028] The metalworking tool of this embodiment has an end coated with a diamond thin film and is used to cut or shape a workpiece, such as a film or sheet material. Here, the end of the metalworking tool refers to the part that comes into contact with the workpiece when cutting or shaping it, and is the cutting edge of the cutting blade if the metalworking tool is a cutting blade, or the end of the mold if the metalworking tool is a mold. Specifically, the metalworking tool is a cutting blade whose cutting edge is coated with a diamond thin film and / or a mold whose end is coated with a diamond thin film.

[0029] <Cutting Blade> First, a case where the metal processing tool is a cutting blade K will be described. The cutting blade K in this embodiment is, for example, a slitter or Thomson blade used to cut a processing object such as a film or sheet material, and the cutting edge K1 is coated with a diamond thin film F. Note that the cutting blade K is not limited to a slitter or Thomson blade, and may be something else.

[0030] The cutting blade K is plate-shaped and made of a material suitable for forming a diamond thin film F. Specifically, as shown in FIG. 1 , the cutting blade K has a rectangular shape in plan view, for example, and a cutting edge K1 is formed on one side of the rectangular shape along the longitudinal direction of the rectangle. Here, the longitudinal length of the cutting edge K1 is preferably 30 cm or more. Conventional methods such as filament CVD and microwave plasma CVD limit the length of diamond thin films formed to approximately 30 cm or less, so a longer cutting blade can achieve high mass productivity. While a longer cutting blade is more preferably 50 cm or more, the longitudinal length of the cutting edge K1 is not limited to this. The cutting edge K1 may also be formed on other sides or on a portion of one side of the rectangle. Furthermore, the shape of the cutting blade K may be other shapes, such as a circular shape, in plan view, as long as the cutting edge K1 is formed on the periphery of the cutting blade K.

[0031] <Mold> Next, a case where the metalworking tool is a mold T will be described. The mold T in this embodiment is, for example, a press mold or punch used to cut or shape a workpiece such as a metal plate or metal sheet material, and the end T1 of the mold T is coated with a diamond thin film F. The mold T referred to here has a flat surface M that comes into contact with the workpiece to cut or shape it, and the end T1 of the mold T is formed on the periphery of the flat surface M. By applying pressure to the mold T while the flat surface M is in contact with the workpiece, the end T1 of the mold T cuts or shapes the workpiece. Note that the mold T is not limited to a press mold or punch, but may be something else.

[0032] Specifically, the mold T is, for example, a round punch, and is composed of two roughly cylindrical members. More specifically, as shown in FIG. 2, the mold T has a small diameter portion where the end T1 of the mold T is formed, and a large diameter portion connected to the surface opposite the flat surface M in the longitudinal direction. Here, the longitudinal length of the mold T is preferably 30 cm or more. The limit for forming a diamond thin film using conventional filament CVD methods, microwave plasma CVD methods, etc. is approximately 30 cm or less, and high mass productivity can be achieved by using a long mold. A length of 50 cm or more is more preferable, but the longitudinal length of the mold T is not limited to this.

[0033] <Substrate of Metal-Working Tool> In the present embodiment, the substrate of the metal-working tool may be made of a material other than tool steel, such as glass, plastic, silicon, iron, titanium, copper, metals such as cemented carbide containing tungsten carbide and cobalt, other alloy materials, SiC, GaN, AlN, BN, diamond, or the like.

[0034] When the substrate of the metalworking tool is a cemented carbide containing tungsten carbide and cobalt, the average grain size of the tungsten carbide is 0.1 μm or more and 1.5 μm or less, and the average cobalt content is 1% or more and 5.5% or less, thereby enabling the metalworking tool to maintain sufficient mechanical strength even when the cutting edge curvature of the metalworking tool is small.

[0035] The metalworking tool may be subjected to a surface treatment such as a scratching treatment or a seeding treatment. For example, if the metalworking tool is made of silicon, it may be subjected to a scratching treatment or a seeding treatment in which it is immersed in alcohol together with diamond fine particles and ultrasonically treated to form irregularities on the surface. Furthermore, if the metalworking tool is made of cemented carbide, it may be immersed in an acidic solution such as a nitric acid solution to remove Co from the metalworking tool, or the surface of tungsten carbide (WC) particles may be chemically etched with an alkaline solution such as diluted NaOH, followed by the above-mentioned seeding treatment.

[0036] When a metalworking tool is surface-treated, the cobalt-free layer on the substrate of the metalworking tool is 5 μm or less, or the radius of curvature of the edge is less than 5 μm. This allows the diamond thin film to grow by CVD while maintaining high adhesion to the substrate. The cobalt-free layer referred to here refers to a layer in which cobalt is removed from the surface of the metalworking tool by treating the surface with an acid or the like.

[0037] Furthermore, the average surface roughness Sa of the unevenness on the surface of the substrate is 0.1 μm to 3 μm or less, or is equal to or less than the curvature of the edge of the metalworking tool, thereby further increasing the adhesion between the diamond thin film and the substrate due to the anchor effect of the unevenness.

[0038] Furthermore, chromium or titanium may be formed on the substrate to a thickness of 0.01 to 1.5 μm or less, or to a radius equal to or less than the curvature of the edge. Chromium or titanium has a high affinity with the substrate, which can further increase the adhesion between the diamond and the substrate.

[0039] Furthermore, the substrate may be coated with chromium or titanium, and the metalworking tool may be surface-treated with a plasma containing hydrogen and argon using inductively coupled plasma, after which a diamond thin film may be deposited by CVD using inductively coupled plasma. This allows the surface oxide layer of chromium or titanium to be removed, further increasing the adhesion of the diamond thin film.

[0040] <Diamond Thin Film> The diamond thin film F is formed on the end of the metalworking tool by a plasma CVD method using an inductively coupled plasma P, using a film-forming apparatus 100, which is a plasma CVD apparatus described below.

[0041] Specifically, the diamond thin film F is composed of nano-polycrystalline diamond. The grain size of the nano-polycrystalline diamond needs to be 900 nm or less or the curvature of the end portion in order to bond the nano-polycrystalline diamonds together with a film thickness smaller than the curvature of the end portion, and is more preferably 50 nm or less. Furthermore, from the viewpoints of manufacturing and mechanical strength, the grain size of the nano-polycrystalline diamond is preferably 5 nm or more.

[0042] The diamond thin film F covers the end portion with a substantially constant film thickness D. In this embodiment, the film thickness D of the diamond thin film F must be 0.5 μm or more in order to bond the nano-polycrystalline diamonds together, and must be 5 μm or less in order to maintain the sharpness of the end portion.

[0043] Furthermore, in order to increase the crystallinity of the diamond, the diamond thin film F has a peak intensity of 1333 cm in Raman spectroscopy with 325 nm excitation. －１ The diamond peak intensity around 1550 cm －１ It is preferably 0.8 times or more and less than 500 times, more preferably 2 times or more, and even more preferably 50 times or more, compared to the peak intensity of the nearby G band.

[0044] In a metalworking tool whose end is coated with a diamond thin film F, the curvature of the end is preferably 0.5 μm or more to maintain the bond between the nano-polycrystalline diamonds, and must be 5 μm or less to maintain the sharpness of the end. Here, the curvature of the end refers to the roundness of the surface of the diamond thin film F that coats the end, as shown in Figures 3 and 4. Specifically, when the metalworking tool is a cutting blade K, the curvature of the end is the cutting edge curvature R1, which is expressed as the radius of an imaginary circle centered on the cutting edge K1, and here, as shown in Figure 3, the radius is the distance between the cutting edge K1 and the surface of the diamond thin film F. On the other hand, when the metalworking tool is a mold T, the curvature R2 of the end T1 of the mold T is expressed as the radius of an imaginary circle centered on the end T1 of the mold T, and here, as shown in Figure 4, the radius is the distance between the end T1 of the mold T and the surface of the diamond thin film F.

[0045] The following describes a film-forming apparatus 100 for synthesizing the above-mentioned diamond thin film F and coating the diamond thin film F on the end of a metalworking tool, and a method for manufacturing the metalworking tool.

[0046] 5 , the film formation apparatus 100 includes a vacuum vessel 2 that is evacuated and into which a gas G is introduced, a gas supply mechanism 7 that supplies the gas G to the vacuum vessel 2, a linear antenna 3 disposed within the vacuum vessel 2, and a high-frequency power supply 4 that applies a high-frequency wave to the antenna 3 to generate an inductively coupled plasma P within the vacuum vessel 2. In this film formation apparatus 100, by applying a high-frequency wave from the high-frequency power supply 4 to the antenna 3, a high-frequency current IR flows through the antenna 3, an inductive electric field is generated within the vacuum vessel 2, and the inductively coupled plasma P is generated.

[0047] The vacuum vessel 2 is a vessel made of metal such as SUS or aluminum, and its interior is evacuated to a vacuum by a vacuum exhaust device 6. In this example, the vacuum vessel 2 is electrically grounded. The vacuum exhaust device 6 is equipped with a pressure regulator 61, such as a valve, that adjusts the pressure inside the vacuum vessel 2. By controlling this pressure regulator 61, the pressure inside the vacuum vessel 2 during plasma generation can be adjusted, for example, to a pressure of 1 Pa to 100 Pa. A pressure of 3 Pa to 50 Pa is more preferable, and a pressure of 5 Pa to 30 Pa is even more preferable.

[0048] A gas G such as a source gas is introduced into the vacuum vessel 2 via, for example, a flow rate regulator (not shown) and a plurality of gas inlets 21 arranged in a direction along the antenna 3 .

[0049] Also provided within the vacuum chamber 2 is a substrate holder 8 for holding a metalworking tool (here, a cutting blade K or a mold T), and a heater 81 for heating the metalworking tool is provided within the substrate holder 8. The substrate holder 8 does not necessarily have to be electrically connected to the vacuum chamber 2. The film formation apparatus 100 of this embodiment may have a function for adjusting the potential of the generated inductively coupled plasma, for example, within a range of +100 V to −100 V, by applying a bias voltage from a bias power supply 9 to the substrate holder 8. The applied bias voltage is, for example, a negative DC voltage, but is not limited thereto. Such a bias voltage can, for example, control the energy of positive ions in the plasma P when they are incident on the metalworking tool, thereby controlling the crystallinity of the film formed on the surface of the metalworking tool.

[0050] The gas supply mechanism 7 supplies gas G, such as a source gas, into the vacuum vessel 2 through a gas inlet 21. The gas supply mechanism 7 is configured to supply the gas G downward from the gas inlet 21 provided on the upper wall of the vacuum vessel 2. The gas supply mechanism 7 is configured to be able to supply a source gas containing at least C (carbon), H (hydrogen), O (oxygen), and a rare gas, and specifically, H ２ Gas, CH ４ Gas and CO ２ The gas supply mechanism 7 is configured to be able to supply a source gas containing C, H, and O into the vacuum chamber 2. ２ Gas, CH ４ Gas and CO ２ In addition to or instead of the gas, any other gas such as acetylene may be supplied as a source gas.

[0051] The rare gas acts as a catalyst during plasma generation, and decomposes the source gas and ２ ＊This promotes bonding between carbon atoms, such as radicals. Specifically, the gas supply mechanism 7 is configured to supply the catalyst gas so that the proportion of the catalyst gas relative to the total flow rate of all gases supplied into the vacuum chamber 2 (here, the total flow rate of the raw material gas and the catalyst gas) is, for example, 20% to 95%, preferably 70% to 90%. Specific examples of this catalyst gas include rare gases such as Ar gas, He gas, and Ne gas.

[0052] The gas supply mechanism 7 is ２ Gas, CH ４ Gas, CO ２ The gas supply mechanism 7 of this embodiment is configured to supply the H gas and the rare gas at any desired flow rate. ２ Gas, CH ４ Gas and CO ２ The source gas is configured to be supplied by adjusting the flow rate of each gas so that the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained therein (O / (O+H)) is, for example, 10 at % or more and 60 at % or less.

[0053] The antenna 3 is disposed above the metalworking tool within the vacuum chamber 2, along the surface of the metalworking tool. In this embodiment, a plurality of linear antennas 3 are disposed in parallel along the metalworking tool (e.g., substantially parallel to the surface of the metalworking tool). In this manner, plasma P with good uniformity can be generated over a wider area, and therefore larger metalworking tools can be processed.

[0054] The number of antennas 3 is not limited to multiple, and may be just one. When multiple antennas 3 are provided, the number is preferably an even number (for example, 2, 4, 6, etc.). When multiple antennas 3 are provided, the spacing between the antennas 3 is preferably 5 cm or more, more preferably 10 cm or more, and even more preferably 15 cm or more, in order to avoid radio wave interference. On the other hand, in order to deposit a uniform diamond thin film F, the spacing between the antennas 3 is preferably 25 cm or less.

[0055] As shown in Figure 5, the vicinity of both ends of the antenna 3 penetrates a pair of opposing side walls 2a, 2b of the vacuum vessel 2. Insulating members 11 are provided at the portions where both ends of the antenna 3 penetrate to the outside of the vacuum vessel 2. Both ends of the antenna 3 penetrate each insulating member 11, and the penetration portions are vacuum-sealed by, for example, packings 12. The antenna 3 is supported via the insulating members 11 in a state in which it is electrically insulated from the opposing side walls 2a, 2b of the vacuum vessel 2. The gap between each insulating member 11 and the vacuum vessel 2 is also vacuum-sealed by, for example, packings 13. The insulating members 11 are made of, for example, ceramics such as alumina, quartz, or engineering plastics such as polyphenylene sulfide (PPS) and polyether ether ketone (PEEK).

[0056] The antenna 3 is a so-called LC antenna having an L portion that serves as an inductor and a C portion that serves as a capacitor. Specifically, the antenna 3 includes at least two tubular metal conductor elements 31 (hereinafter referred to as metal pipes 31), tubular insulating elements 32 (hereinafter referred to as insulating pipes 32) that are provided between adjacent metal pipes 31 to insulate the metal pipes 31, and capacitors 33 that are capacitive elements that are provided between adjacent metal pipes 31 and electrically connected in series with the conductor elements 31 and capacitors 33. The conductor elements 31 function as the L portion, and the capacitors 33 function as the C portion.

[0057] In this embodiment, the number of metal pipes 31 is three, and the number of insulating pipes 32 and capacitors 33 is two each. Note that the antenna 3 may be configured to have four or more metal pipes 31, in which case the number of insulating pipes 32 and capacitors 33 is one less than the number of metal pipes 31.

[0058] The material of the metal pipe 31 is, for example, but not limited to, copper, aluminum, an alloy thereof, stainless steel, etc. The antenna 3 may be hollow and a refrigerant such as cooling water may be passed through it to cool the antenna 3.

[0059] In this embodiment, the insulating pipe 32 is formed from a single member, but is not limited to this. The insulating pipe 32 may be made of a material such as alumina, fluororesin, polyethylene (PE), or engineering plastic (such as polyphenylene sulfide (PPS) or polyether ether ketone (PEEK)).

[0060] Furthermore, the portion of the antenna 3 located inside the vacuum vessel 2 is covered by a straight tubular insulating cover (antenna protection tube) 10. Both ends of this insulating cover 10 are supported by insulating members 11. Note that it is not necessary to seal between both ends of the insulating cover 10 and the insulating members 11. This is because even if gas G enters the space inside the insulating cover 10, the space is small and the travel distance of electrons is short, so plasma P is not normally generated in the space. Note that the insulating cover 10 can be made of, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon, or the like.

[0061] By providing the insulating cover 10, it is possible to prevent charged particles in the plasma P from entering the metal pipe 31 that constitutes the antenna 3, thereby preventing an increase in plasma potential due to charged particles (mainly electrons) entering the metal pipe 31 and preventing the metal pipe 31 from being sputtered by charged particles (mainly ions), which would cause metal contamination of the plasma P and metal processing tools.

[0062] The length of the antenna 3 is preferably, for example, 30 cm or more, more preferably 50 cm or more, and even more preferably 100 cm or more, in order to coat the long end portion with the diamond thin film F. On the other hand, from the viewpoint of ensuring the strength of the insulating pipe 32, the length of the antenna 3 is preferably 2000 cm or less, and more preferably 1000 cm or less.

[0063] 5, the antenna 3 has a power feeding end 3a to which high frequency power is fed in the antenna direction (longitudinal direction X) and a grounded end 3b. Specifically, at both ends of each antenna 3 in the longitudinal direction X, the portion extending outward from one of the side walls 2a or 2b serves as the power feeding end 3a, and the portion extending outward from the other of the side walls 2a or 2b serves as the grounded end 3b.

[0064] Here, a high frequency is applied to the power supply end 3a of each antenna 3 from a high frequency power supply 4 via a matching box 41. The frequency of the high frequency is 400 kHz or more and 100 MHz or less, for example, the common frequency of 13.56 MHz, but is not limited to this. For example, it may be 27.12 MHz, 40.68 MHz, 60 MHz, etc.

[0065] <Method of Manufacturing Metalworking Tool> Next, a method of manufacturing a metalworking tool having an end portion coated with a diamond thin film F using the above-described film forming apparatus 100 will be described.

[0066] First, a metalworking tool is set on a substrate holder 8 in a vacuum chamber 2 of the film forming apparatus 100, and the vacuum chamber 2 is evacuated by the vacuum exhaust device 6. Then, the metalworking tool is heated by a heater 81, and the temperature of the metalworking tool is preferably set to 500°C or higher and 1000°C or lower.

[0067] (Supply of Source Gas) Next, H as a source gas is supplied by the gas supply mechanism 7. ２ Gas, CH ４ Gas, CO ２ The gas and rare gas are supplied at a predetermined flow rate into the vacuum chamber 2. In the method for producing the diamond thin film F of this embodiment, the atomic ratio of O atoms, C atoms, and H atoms in the source gas is adjusted to fall within the shaded range shown in the composition ternary diagram (C-H-O diagram) of FIG. ２ Gas, CH ４ Gas and CO ２ The flow rate of each gas is adjusted. The atomic ratio of each atom is explained below.

[0068] (Ratio of Number of Oxygen and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of O atoms to the total concentration of O atoms and H atoms contained therein (O / (O+H)) is preferably 10 at % or more and 60 at % or less, more preferably 20 at % or more and 50 at % or less. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0069] (Ratio of Number of Oxygen and Carbon Atoms) In the raw material gas to be supplied, the ratio of the concentration of C atoms to the total concentration of O atoms and C atoms contained therein (C / (O+C)) is preferably 30 at % or more and 50 at % or less, more preferably 35 at % or more and 45 at % or less, and H ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0070] (Ratio of Number of Carbon and Hydrogen Atoms) In the raw material gas to be supplied, the ratio of the concentration of H atoms to the total concentration of C atoms and H atoms (H / (C+H)) is preferably 40 at % or more and 90 at % or less, more preferably 50 at % or more and 80 at % or less. ２ Gas, CH ４ Gas and CO ２ The gases are supplied while controlling their respective flow rates.

[0071] (Supply of catalytic gas) Furthermore, a catalytic gas such as Ar gas is supplied into the vacuum chamber 2 together with the raw material gas by the gas supply mechanism 7. The flow rate of the supplied catalytic gas is set so that the ratio of the total flow rate of all gases supplied to the vacuum chamber 2 is preferably 50% or more and 90% or less, more preferably 75% or more and 90% or less. By setting the flow rate of the supplied catalytic gas in this range, it is possible to prevent the ionization of easily ionized gases, such as Ar, into CH during film formation. ４ C, which transfers energy to ２ This allows the generation of a large number of radicals. As a result, in the emission spectrum of the generated inductively coupled plasma, the C ２ ＊The ratio of the radical emission intensity can be set to 30% or more and 300% or less.

[0072] (Pressure in Vacuum Chamber) Then, the pressure in the vacuum chamber 2 is adjusted to 1 Pa or more and 100 Pa or less by the pressure regulator 61 while the raw material gas and catalyst gas are introduced by the gas supply mechanism 7 .

[0073] (Plasma generation and diamond thin film deposition) Then, with the flow rates of the raw material gas and catalyst gas adjusted as described above and the pressure inside the vacuum vessel 2 adjusted, high frequency power is supplied from the high frequency power supply 4 to the antenna 3. This generates an inductive electric field inside the vacuum vessel 2 to generate inductively coupled plasma P, and when a diamond thin film F is synthesized, the particle size of the nano-polycrystalline diamond that makes up the diamond thin film F is 5 nm or more and 1000 nm or less, more preferably 10 nm or more and 300 nm or less. The frequency of the high frequency power is 13.56 MHz. The power density of the supplied high frequency power is 0.1 W / cm ２ More than 0.5 W / cm is preferable. ２ More preferably, 1 W / cm or more ２ More preferably, the power density is 1000 W / cm. ２ Preferably, 100 W / cm or less ２ More preferably, 50 W / cm or less ２ The following is even more preferred:

[0074] Then, the edge of the metalworking tool is coated with a diamond thin film F, and the thickness D of the diamond thin film F is set to 0.5 μm or more and 5 μm or less. As a result, the curvature of the edge becomes 0.5 μm or more and 5 μm or less.

[0075] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and modifications can be made within the scope of the above and below-described aims, and all such modifications are within the technical scope of the present invention.

[0076] <Examples of Cutting Blade> In the following three examples, a film was formed on the cutting edge K1 of each sample by plasma CVD using the above-described film forming apparatus 100. The cutting blade material and surface roughness in each example are as follows.

[0077] Example 1: The substrate of the cutting blade K is a carbon tool steel SK105 substrate, on which a 0.5 μm thin chromium film is formed. The surface roughness Sa of the substrate is 0.02 μm. Example 2: The substrate of the cutting blade K is a superalloy substrate, on which a 0.5 μm average grain size of tungsten carbide, a 5% average cobalt content, a 2 μm cobalt-free layer, and a surface roughness Sa of 0.51 μm. Example 3: The substrate of the cutting blade K is a superalloy substrate, on which a 0.5 μm thin titanium film is formed. The substrate has a 0.5 μm average grain size of tungsten carbide, a 5% average cobalt content, a 2 μm cobalt-free layer, and a surface roughness Sa of 0.29 μm. Example 4: The substrate of the cutting blade K is a carbon tool steel SK105 substrate, on which a 0.5 μm thin chromium film is formed. The surface roughness Sa of the substrate is 0.02 μm.

[0078] In Examples 1 to 4, the frequency of the high-frequency power, the power density of the high-frequency power, the conditions of the supplied gas, and the temperature of the cutting blade were as follows: Frequency of the supplied high-frequency power: 13.56 MHz Power density of the supplied high-frequency power: Examples 1, 2, and 3: 1.4 W / cm ２ Example 4: 2.1 W / cm ２ Gas conditions to be supplied: Examples 1, 2, and 3: CH4 = 10 sccm, CO2 = 10 sccm, Ar = 80 sccm, pressure 20 Pa. Example 4: H2 = 20 sccm, CH4 = 2 sccm, CO2 = 8 sccm, Ar = 120 sccm, pressure 45 Pa. Cutting blade temperature: 400°C.

[0079] Diamond thin film F was produced under the above conditions, and the particle size of the nano-polycrystalline diamond constituting diamond thin film F was evaluated using a secondary electron microscope (SEM). As a result, the particle size of the nano-polycrystalline diamond was about 30 nm in all of Examples 1, 2, and 3. In Example 4, it was about 200 nm.

[0080] The thickness of the diamond thin film F was evaluated by etching the cutting edge of the edge that was not damaged in the cutting test with a focused ion beam (FIB) and examining the cross section with an SEM. The film thickness was 2 μm in all of Examples 1 to 4.

[0081] The cutting edge curvature was then evaluated by SEM on the cross section. The cutting edge curvature was 3 μm in all of Examples 1 to 4.

[0082] Furthermore, the crystallinity of the produced samples was evaluated by laser Raman spectroscopy (excitation at 325 nm). －１ The optical phonon peak of diamond is observed in the vicinity of the wavelength of 1550 cm －１ Compared with the optical phonon peak of the G band derived from diamond-like carbon observed in the vicinity of the wavelength of 1000 nm, Example 1 has an intensity 3.5 times, Example 2 has an intensity 4.1 times, Example 3 has an intensity 4.0 times, and Example 4 has an intensity 57 times, that is, an intensity of 0.8 times or more but less than 500 times. Therefore, it was confirmed that a diamond thin film F with high crystallinity could be produced.

[0083] Furthermore, the hardness of the produced samples was measured using a nanoindenter. The measurement position was a flat part 2 cm away from the cutting edge. The hardness was 54 GPa in Example 1, 71 GPa in Example 2, 68 GPa in Example 3, and 94 GPa in Example 4.

[0084] As a comparative example, a cutting blade having the same shape as that of the present invention was fabricated using carbon tool steel SK105 as a substrate, and the following was formed on the substrate instead of the diamond thin film.

[0085] Comparative Example 1: Diamond-like carbon t-aC was formed on a substrate to a film thickness of 2.0 μm. Comparative Example 2: Titanium nitride was formed on a substrate to a film thickness of 2.0 μm.

[0086] A cutting test was conducted to examine the difference in the lifespan of the cutting blades between the Examples and Comparative Examples. In the cutting test, an amorphous alloy steel plate made of Fe-B-Si-C and having a thickness of 0.025 mm was cut using the cutting blades produced in each Example and Comparative Example, and the number of cuts that could be made was counted. The number of cuts that could be made indicates the lifespan of the cutting blade, and the lifespan of the cutting blade was determined when burrs appeared on the cut surface of the amorphous alloy steel plate or wrinkles appeared in the plate.

[0087] The results of the cutting test are shown below: Example 1: 8,042 times Example 2: 16,066 times Example 3: 19,778 times Example 4: 41,000 times Comparative Example 1: 4,531 times Comparative Example 2: 2,602 times

[0088] As can be seen from the results of the cutting test, when the cutting edge is coated with a diamond thin film (Examples 1 to 4), the cutting blade life is improved compared to Comparative Examples 1 and 2. In addition, when the cutting blade substrate is a superalloy substrate (Examples 2 and 3), the cutting blade life is improved compared to when the cutting blade substrate is tool steel (Example 1). Furthermore, when the cutting blade substrate is a superalloy substrate (Examples 2 and 3), when titanium is formed on the substrate (Example 3), the cutting blade life is improved compared to when a diamond thin film is directly formed on the substrate (Example 2). Furthermore, Raman spectroscopy shows that when the diamond crystallinity is high (Example 4), the life is improved compared to when it is low (Example 1).

[0089] <Mold Examples> In the following three examples, samples were formed on the edge of a mold by plasma CVD using the above-described film formation apparatus 100. The mold materials and surface roughnesses in each example are as follows:

[0090] Example 1: The substrate of the mold is a carbon tool steel SK105 substrate, on which a 0.5 μm chromium thin film is formed. The surface roughness Sa of the substrate is 0.02 μm. Example 2: The substrate of the mold is a superalloy substrate, on which the average grain size of tungsten carbide is 0.5 μm, the average cobalt content is 5%, the cobalt-free layer is 2 μm, and the surface roughness Sa is 0.51 μm. Example 3: The substrate of the mold is a superalloy substrate, on which a 0.5 μm titanium thin film is formed. The substrate has an average grain size of tungsten carbide of 0.5 μm, the average cobalt content is 5%, the cobalt-free layer is 2 μm, and the surface roughness Sa is 0.29 μm.

[0091] In Examples 1, 2, and 3, the frequency of the high-frequency power, the power density of the high-frequency power, the conditions of the supplied gas, and the temperature of the mold were as follows: Frequency of the supplied high-frequency power: 13.56 MHz Power density of the supplied high-frequency power: Examples 1, 2, and 3: 1.4 W / cm ２ Example 4: 2.1 W / cm ２ Gas conditions to be supplied: Examples 1, 2, and 3: H2 = 10 sccm, CH4 = 5 sccm, CO2 = 15 sccm, Ar = 120 sccm, pressure 10 Pa. Example 4: H2 = 20 sccm, CH4 = 1 sccm, CO2 = 9 sccm, Ar = 120 sccm, pressure 30 Pa. Mold temperature: 400°C.

[0092] Diamond thin film F was produced under the above conditions, and the particle size of the nano-polycrystalline diamond constituting diamond thin film F was evaluated using a secondary electron microscope (SEM). As a result, the particle size of the nano-polycrystalline diamond was about 30 nm in all of Examples 1, 2, and 3. In Example 4, it was about 200 nm.

[0093] The thickness of the diamond thin film F was evaluated by etching the edge of the mold that was not damaged in the cutting test with a focused ion beam (FIB) and examining the cross section with an SEM. The film thickness was 2 μm in all of Examples 1 to 4.

[0094] The curvature R of the edge of the mold was then evaluated by SEM in cross section. The curvature R of the edge of the mold was 3 μm in all of Examples 1 to 4.

[0095] Furthermore, the crystallinity of the produced samples was evaluated by laser Raman spectroscopy (excitation at 325 nm). －１ The optical phonon peak of diamond is observed in the vicinity of the wavelength of 1550 cm －１ Compared with the optical phonon peak of the G band derived from diamond-like carbon observed in the vicinity of the wavelength of 1000 nm, Example 1 has an intensity of 3.0 times, Example 2 has an intensity of 4.1 times, Example 3 has an intensity of 3.9 times, and Example 4 has an intensity of 60 times, that is, an intensity of 0.8 times or more but less than 500 times. Therefore, it was confirmed that a diamond thin film F with high crystallinity could be produced.

[0096] Furthermore, the hardness of the produced samples was measured using a nanoindenter. The measurement position was a flat part 2 cm away from the edge of the mold. The hardness was 50 GPa in Example 1, 69 GPa in Example 2, 62 GPa in Example 3, and 95 GPa in Example 4.

[0097] As a comparative example, a mold having the same shape as that of the present invention was fabricated using carbon tool steel SK105 as a substrate, and the following was formed on the substrate instead of the diamond thin film.

[0098] Comparative Example 1: Diamond-like carbon t-aC was formed on a substrate to a film thickness of 2.0 μm. Comparative Example 2: Titanium nitride was formed on a substrate to a film thickness of 2.0 μm.

[0099] A cutting test was conducted to examine the difference in die life between the Examples and Comparative Examples. In the cutting test, an amorphous alloy steel plate made of Fe-B-Si-C and having a thickness of 0.025 mm was cut using the die prepared in each Example and Comparative Example, and the number of cuts that could be made was counted. The number of cuts that could be made indicates the die life, and the die life was determined as the time when burrs appeared on the cut surface of the amorphous alloy steel plate or wrinkles appeared in the plate.

[0100] The results of the cutting test are shown below: Example 1: 7,900 times Example 2: 15,500 times Example 3: 18,900 times Example 4: 42,000 times Comparative Example 1: 4,400 times Comparative Example 2: 2,700 times

[0101] As can be seen from the results of the cutting test, when the edge of the die is coated with a diamond thin film (Examples 1 to 4), the die life is improved compared to Comparative Examples 1 and 2. In addition, when the die substrate is a superalloy substrate (Examples 2 and 3), the die life is improved compared to when the die substrate is tool steel (Example 1). Furthermore, when the die substrate is a superalloy substrate (Examples 2 and 3), when titanium is formed on the substrate (Example 3), the die life is improved compared to when a diamond thin film is formed directly on the substrate (Example 2). Furthermore, Raman spectroscopy shows that when the crystallinity of the substitutive bonds and diamonds is high (Example 4), the die life is improved compared to when it is low (Example 1).

[0102] <Effects of this embodiment> According to this embodiment, since the edge is coated with a diamond thin film F, the wear resistance of the edge can be improved compared to metalworking tools coated with a nitride film or DLC. Furthermore, since the grain size of the nano-polycrystalline diamond in the diamond thin film F is 900 nm or less or the cutting edge curvature is less than the cutting edge curvature, the nano-polycrystalline diamonds can be bonded together. Therefore, it is possible to prevent the nano-polycrystalline diamond from falling off the diamond thin film F, and the strength of the diamond thin film F can be maintained even if the diamond thin film F is thinned to 5 μm or less. As a result, in a metalworking tool, the cutting edge curvature can be made 5 μm or less to maintain the sharpness of the edge and the wear resistance of the edge can be maintained.

[0103] Furthermore, according to this embodiment, an antenna 3 having a conductor element 31 and a capacitive element 33 electrically connected in series is used, so that plasma P is generated more uniformly in the longitudinal direction of the antenna 3 than in a configuration using a conventional plasma CVD apparatus. As a result, it is possible to manufacture a metalworking tool in which the longer longitudinal ends are coated with a diamond thin film F. In particular, it is possible to coat the diamond thin film F made of nano-polycrystalline diamond on ends having a longitudinal length of, for example, 30 cm or more.

[0104] Other Embodiments The film forming apparatus 100 of the present invention is not limited to the above-described embodiment.

[0105] In this embodiment, the end portion is covered with the diamond thin film F over the entire length, but it is also possible to cover only a portion of the end portion with the diamond thin film F.

[0106] For example, in the film formation apparatus 100 of the above embodiment, the antenna 3 that generates the inductively coupled plasma is disposed inside the vacuum chamber 2. However, this is not limiting. In other embodiments, the film formation apparatus 100 may have a structure in which the antenna 3 is disposed outside the vacuum chamber 2.

[0107] It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, it will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following aspects.

[0108] According to the present invention, the sharpness of the cutting edge of the cutting blade can be maintained and the wear resistance of the cutting edge can be improved.

[0109] REFERENCE SIGNS LIST 100: Plasma CVD device 2: Vacuum vessel 3: Antenna 7: Gas supply mechanism K: Cutting blade K1: Cutting edge T: Mold T1: End of mold F: Diamond thin film P: Plasma

Claims

1. A metalworking tool having an end coated with a diamond thin film, wherein the average grain size of nano-polycrystalline diamond constituting said diamond thin film is 5 nm or more and 900 nm or less or the curvature of said end, the film thickness of said diamond thin film is 0.5 μm or more and 5 μm or less, and in Raman spectroscopy analysis with 325 nm excitation, the diamond thin film has a diamond-derived peak intensity that is 0.8 times or more and less than 500 times the peak intensity of the G band derived from diamond-like carbon, the hardness of said diamond thin film is 30 GPa or more and 100 GPa or less, and the curvature of said end is 0.5 μm or more and 5 μm or less.

2. A metalworking tool according to claim 1, wherein the substrate of the metalworking tool is a material containing iron or a cemented carbide containing tungsten carbide and cobalt, chromium or titanium is formed on the substrate to a thickness of 0.01 to 1.5 μm, and a diamond thin film is coated on the chromium or titanium formed on the substrate.

3. A metal working tool according to claim 1 or 2, wherein the substrate of the metal working tool is a cemented carbide containing tungsten carbide and cobalt, the average grain size of the tungsten carbide in the substrate is 0.1 μm or more and 1.5 μm or less, the average cobalt content in the substrate is 1% or more and 5.5% or less, the cobalt-free layer in the substrate is 5 μm or less or the curvature of the end portion, the average surface roughness of the unevenness on the surface of the substrate is 0.1 μm or more and 3 μm or the curvature of the end portion, and the substrate is coated with a diamond thin film.

4. A metalworking tool according to claim 1 or 2, wherein the length of said end portion in the longitudinal direction is 30 cm or more.

5. The metalworking tool according to claim 1 or 2, wherein the metalworking tool is a cutting blade whose cutting edge is coated with a diamond thin film and / or a mold whose end is coated with a diamond thin film.

6. A method for manufacturing a metalworking tool having an end coated with a diamond thin film, comprising: supplying a raw material gas containing carbon, hydrogen, oxygen, and a rare gas into a vacuum vessel in which the end is placed; generating inductively coupled plasma in the vacuum vessel by passing a high-frequency current through an antenna placed inside or outside the vacuum vessel, the antenna having a conductor element and a capacitance element electrically connected in series with each other; synthesizing the diamond thin film by a plasma CVD method using the generated inductively coupled plasma, and coating the end with the diamond thin film; wherein the grain size of the nano-polycrystalline diamond constituting the diamond thin film is 5 nm to 900 nm or less or the curvature of the end, the film thickness of the diamond thin film is 0.5 μm to 5 μm, and the curvature of the end is 0.5 μm to 5 μm.

7. The method for manufacturing a metalworking tool according to claim 6, wherein the length of the end portion in the longitudinal direction is 30 cm or more.

8. The method for manufacturing a metalworking tool according to claim 6 or 7, wherein the substrate of the metalworking tool is coated with chromium or titanium, and the diamond thin film is synthesized by a plasma CVD method using inductively coupled plasma.

9. A method for manufacturing a metalworking tool according to claim 6 or 7, comprising coating a substrate of the metalworking tool with chromium or titanium, surface treating the substrate with inductively coupled plasma containing hydrogen and argon, and synthesizing the diamond thin film by a plasma CVD method using the inductively coupled plasma.

10. A method for manufacturing a metalworking tool according to claim 6 or 7, wherein a cobalt-free layer is formed by chemical etching on a substrate of the metalworking tool made of cemented carbide containing tungsten carbide and cobalt, and the diamond thin film is synthesized by a plasma CVD method using inductively coupled plasma.

11. A method for manufacturing a metalworking tool according to claim 6 or 7, wherein the metalworking tool is a cutting blade whose cutting edge is coated with a diamond thin film and / or a mold whose end is coated with a diamond thin film.

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