Superhard tools

Abstract

A cemented carbide tool using a cemented carbide alloy including a WC phase and a binder phase containing Co, wherein an average grain size of the WC phase is X μm and a total amount of the binder phase is Y mass % and satisfies the following formulas (1), (2), and (3): X≦1.2 (1) 2≦Y (2) -6.7X+6≦Y≦-14X+38 (3) and containing 2 to 20 mass % of Cr and / or V, calculated as carbide, based on the total amount of the binder phase.

Description

[Technical field]

[0001] The present invention relates to a cemented carbide tool. [Background technology]

[0002] In the major trend towards a decarbonized society, the electrification of automobiles and other vehicles plays a major role. Motors used in electric vehicles are required to be lighter and have higher performance. To achieve low iron loss and high magnetic flux density, the cores of motors and other devices are often made of multiple laminated electromagnetic steel sheets. In particular, amorphous alloy foils exhibit excellent mechanical properties, magnetic properties, corrosion resistance, and other characteristics. As their magnetic properties are particularly excellent, using amorphous alloy foils instead of ordinary electromagnetic steel sheets is expected to significantly improve performance.

[0003] While magnetic steel sheets used for the iron cores of motors and the like are generally 100 to 500 μm thick, amorphous metal foils are about 10 to 100 μm thick, and therefore amorphous metal foils require multiple punching operations. However, when metal foils with high hardness and strength such as amorphous alloy foils are punched into a predetermined shape repeatedly, the punching tools wear out rapidly, resulting in a problem of short tool life.

[0004] JP 2021-130131 A (Patent Document 1) discloses a method for forming a plastically worked groove that becomes a punched outline of a predetermined shape on the surface of an amorphous alloy ribbon, and performing punching along the plastically worked groove with a punching punch and die to obtain an amorphous alloy piece. By forming a plastically worked groove that becomes a punched outline of a predetermined shape on the surface of an alloy foil, the punching load is reduced and the tool life is improved.

[0005] In addition, when punching amorphous alloy foil, in order to ensure productivity, multiple alloy foils may be laminated and punched, but as the number of laminated sheets increases, the punching load increases and the quality of the punched material decreases. JP 2023-8048 A (Patent Document 2) discloses a punching method in which an amorphous electromagnetic steel sheet is punched using a die and a punch, and an elastic coating is applied to the amorphous electromagnetic steel sheet before punching to reduce the punching load. In this way, by using a laminated material in which an elastic coating is applied between the alloy foils, the punching load is suppressed and tool wear is reduced.

[0006] There have also been attempts to improve the shape of punching tools. Patent No. 7129048 (Patent Document 3) discloses a shearing method for amorphous alloy foils, in which a punch used for punching multiple laminated amorphous alloy foils is provided with a first edge formed on the punch tip surface and a second edge formed on the punch side surface, and the horizontal distance from the first edge to the punch side surface and the vertical distance from the second edge to the punch tip surface are set to predetermined distances. When multiple laminated amorphous alloy foils are punched, the tip of the punching tool is shaped to a predetermined shape so that a product with high dimensional stability without cracks can be obtained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2021-130131 A [Patent Document 2] Patent Publication No. 2023-8048 [Patent Document 3] Patent No. 7129048 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the manufacturing method of Patent Document 1, it is necessary to form a plastic processing groove that will become a punched outline of a predetermined shape in advance, so a special processing tool is required and the number of steps is increased. In addition, the punching processing method of Patent Document 2 requires a process of producing a laminated material in which an elastic coating is applied between alloy foils. In the shear processing method of Patent Document 3, it is necessary to form the tip of the punching tool into a predetermined shape, so the degree of freedom of processing is limited.

[0009] As described above, the processing of amorphous alloy foils and the shapes of punching tools have been studied, but no studies have been conducted on cemented carbide suitable as a material for tools for continuously punching high-hardness, high-strength metal foils (single layer or multiple laminated foils) into a predetermined shape.

[0010] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a cemented carbide tool suitable for continuously punching out a high-hardness and high-strength metal foil (single layer or multiple layer laminate) into a predetermined shape. [Means for solving the problem]

[0011] The present invention relates to a cemented carbide that is optimal for a punching tool for punching a high-hardness, high-strength metal foil (single layer or multi-layer laminate), such as an amorphous alloy foil. In order to solve the above-mentioned problems, the present invention investigated in detail the wear and damage modes of the punching tool for amorphous alloy foil and attempted to improve them.

[0012] The most important point is that the hardness and wear resistance of the cemented carbide used in punching tools for punching amorphous alloy foils are not necessarily in a proportional relationship. Until now, the wear resistance of punching tools has been discussed in terms of the hardness of the tool material. In other words, in order to improve the wear resistance of punching tools, a cemented carbide with high hardness is selected, but this also reduces the toughness and chipping resistance. In the present invention, we have focused on the fact that the wear caused by adhesion of the alloy foil to the punching tool when punching amorphous alloy foils is largely dependent on the WC phase grain size of the cemented carbide of the punching tool, and that punching tools using cemented carbide with finer WC phase grains tend to have better wear resistance.

[0013] When punching conventional metal foils with a thickness of about 250 μm, such as electromagnetic steel sheets, using lubricating oil, the amount of the workpiece adhering to the punching tool is small. Therefore, the stress when the adhered material is pulled off during punching is also small, and the larger the WC grain size, the better the supporting force of the binder phase. Therefore, when comparing cemented carbide alloys with the same hardness but different WC grain sizes, the cemented carbide with a relatively larger WC phase grain size has better wear resistance as the particles do not fall off.

[0014] On the other hand, if lubricating oil is used when punching amorphous alloy foil with a thickness of about 10 to 100 μm, core adhesive lamination cannot be performed. On the other hand, if amorphous alloy foil is punched without using lubricating oil, the amount of adhered material to the punching tool of the processed material increases, and since amorphous alloys are hard and strong, the stress when the adhered material is peeled off is very large. Therefore, even WC phases with large particle size and high support by the binder phase fall off due to the stress when the adhered material is peeled off, and the punching tool is worn out.

[0015] As a result of intensive research based on the above findings, the inventors found that a cemented carbide with a smaller WC phase grain size has a smaller volume loss when it falls off, and therefore the total volume loss (=wear amount) due to repeated falling off is smaller. That is, when punching a metal foil (single layer or multi-layer laminate) with high hardness and strength, a cemented carbide with a smaller WC grain size has a lower wear resistance, even if the cemented carbide has the same hardness. As a result, the inventors found that by using an ultrafine-grain cemented carbide with a small WC grain size, which has a higher hardness in a range where the punching tool does not chip under specified punching conditions, for the punching tool, it is possible to achieve both superior wear resistance and chipping resistance compared to conventional cemented carbide punching tools.

[0016] That is, a cemented carbide tool for punching according to one embodiment of the present invention comprises a WC phase and a binder phase containing Co, The average grain size of the WC phase is X μm, and the total amount of the binder phase is Y mass %. X≦1.2 (1) 2≦Y (2) -6.7X+6≦Y≦-14X+38 (3) Fulfilling The alloy is characterized in that it contains 2 to 20 mass % of Cr and / or V in terms of carbide relative to the total amount of the binder phase.

[0017] The total amount Y mass% of the binder phase is calculated by the following formula (4): -7X+12≦Y (4) It is preferable that the following formulas (5) and (6): X≦0.9 (5) -11X+22≦Y (6) It is more preferable that the following conditions are satisfied:

[0018] In one embodiment of the present invention, the total amount Y (mass%) of the binder phase satisfies the following formulas (7) and (8): X≦0.7 (7) -6.7X+9.1≦Y (8) It is preferable that the following conditions are satisfied.

[0019] In one embodiment of the present invention, the cemented carbide tool preferably contains at least one element selected from the group consisting of Groups 4 to 6 of the periodic table other than Cr and V, and the total content of the elements is 0.2 to 5 mass% in terms of carbide, It is preferable that the composition contains a compound phase consisting of carbides and / or carbonitrides of the above elements, and the particle size of the compound phase is 0.02 to 2 μm.

[0020] In the cemented carbide tool according to one embodiment of the present invention, the binder phase preferably contains at least one of Ni and Fe.

[0021] Such a cemented carbide tool can be suitably used as a tool for punching metal foil having a thickness of 10 to 100 μm and a hardness of 700 HV or more, and the metal foil is preferably an amorphous alloy foil.

[0022] In the cemented carbide tool according to one embodiment of the present invention, after a punching test is conducted 500 times or more with a clearance of 5% t and without lubrication on a laminate of five amorphous alloy foils each having a thickness of 25 μm and a hardness of 900 HV, the surface roughness Ra of the cutting edge is preferably 0.1 μm or less.

[0023] The cemented carbide tool according to one embodiment of the present invention is preferably coated with a hard coating. Effect of the Invention

[0024] According to the present invention, a cemented carbide tool suitable for continuously punching out a high-hardness, high-strength metal foil (single layer or multiple-layer laminate) into a predetermined shape can be obtained. [Brief description of the drawings]

[0025] [Figure 1] FIG. 4 is a schematic diagram showing measurement positions of the line roughness Ra of the worn portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A cemented carbide tool for punching according to one embodiment of the present invention comprises a WC phase and a binder phase containing Co, The average grain size of the WC phase is X μm, and the total amount of the binder phase is Y mass %. X≦1.2 (1) 2≦Y (2) -6.7X+6≦Y≦-14X+38 (3) Fulfilling The alloy is characterized in that it contains 2 to 20 mass % of Cr and / or V in terms of carbide relative to the total amount of the binder phase.

[0027] The average grain size X of the WC phase is 1.2 μm or less. The average grain size X of the WC phase is determined by the Fullman formula based on the structure of an arbitrary cross section of the cemented carbide. If the average grain size X of the WC phase exceeds 1.2 μm, the WC phase is likely to wear away when punching a metal foil (single layer or multiple laminated layers) having high hardness and strength, and it is difficult to obtain sufficient wear resistance as a punching tool. The average grain size X of the hard phase is preferably 0.9 μm or less, more preferably 0.7 μm or less, even more preferably 0.6 μm or less, and particularly preferably 0.4 μm or less.

[0028] The total amount Y (mass%) of the binder phase is 2 or more and is expressed by the following formula (3): -6.7X+6≦Y≦-14X+38 (3) Here, the total amount Y of the binder phase means the sum of the components added as binder phase components in the binder phase, and the components that are solid-dissolved after being added as other components are not included in the total amount Y of the binder phase. If the total amount Y of the binder phase (mass%) is less than 2 or less than -6.7X+6, the toughness of the cemented carbide decreases, and the chipping resistance of the punching tool decreases. If the total amount Y of the binder phase (mass%) is more than -14X+38, the hardness of the cemented carbide is insufficient, and the wear resistance of the punching tool decreases. The total amount Y of the binder phase (mass%) is preferably -6.7X+9.1 or more, more preferably -6.7X+9.6 or more, even more preferably -6.7X+10.1 or more, even more preferably -7X+12 or more, and particularly preferably -11X+22.

[0029] The binder phase preferably contains at least one of Ni and Fe in addition to the main component Co. At least one of Ni and Fe may be contained in 30 mass% of the total amount of the binder phase, and if it is 20 mass%, the advantages can be further enhanced without deteriorating the properties. In addition, it may contain components that can be used as a binder phase, such as Al and Cu. These components correspond to the components added as the binder phase components described above. In addition, metal elements that constitute the hard phase can be solid-dissolved in the binder phase of the cemented carbide. When components other than Co are contained as binder phase components as described above, it is preferable that Co is contained in 70 mass% or more, and more preferably 80 mass% or more, of the total amount of the binder phase.

[0030] The cemented carbide of the present invention contains 2 to 20 mass% of Cr and / or V in terms of carbide relative to the binder phase. When 2 to 20 mass% of Cr is added in terms of carbide, the grain growth of WC during sintering is suppressed and the corrosion resistance is improved. When 2 to 20 mass% of V is added in terms of carbide, a more effective grain growth suppression effect than Cr can be obtained. The amount of Cr and / or V added is preferably 3 to 18 mass% in terms of carbide, and more preferably 4 to 15 mass%.

[0031] It may contain at least one element selected from the group consisting of Groups 4 to 6 of the periodic table other than Cr and V. The total content of the above elements is preferably 0.2 to 5 mass% in terms of carbide. The total content of the above elements is more preferably 0.5 to 4 mass%, and even more preferably 1 to 3 mass%, in terms of carbide. These components can also be dissolved in the binder phase.

[0032] It is preferable that the compound phase is composed of carbides and / or carbonitrides of the above elements, and the particle size of the compound phase is 0.02 to 2 μm. The compound phase may be composed of a plurality of compounds alone or may form a solid solution phase. Examples of the solid solution phase include (Ta, Nb)C, (W, Ti)C, (W, Cr, Ti)C, (W, Ti)CN, and (W, Ti, Nb)C. The particle size of the compound phase is more preferably 0.05 to 1 μm.

[0033] The cemented carbide tool according to one embodiment of the present invention has an improved chipping resistance and satisfies the following formula (4): -7X+12≦Y (4) By decreasing the grain size of the WC phase of the cemented carbide and increasing the amount of the binder phase mainly composed of Co, it is possible to obtain a more suitable cemented carbide tool for punching metal foil, which is less likely to chip at the cutting edge even when continuously punching a high-hardness and high-strength metal foil (single layer or multiple laminated sheets) into a predetermined shape.

[0034] In order to further improve chipping resistance and wear resistance as compared with conventional products, a cemented carbide tool according to an embodiment of the present invention has a structure satisfying the following formulas (5) and (6): X≦0.9 (5) -11X+22≦Y (6) Such a carbide tool is particularly suitable for punching multiple laminated metal foils having high hardness and strength, and is less likely to chip at the cutting edge even when the punching load increases, making it possible to suppress wear at the cutting edge of the punching tool. In other words, this tool is advantageous when punching is performed under conditions of high load or with a tool having a shape that is prone to chipping.

[0035] In addition, the cemented carbide tool according to one embodiment of the present invention emphasizes improvement in wear resistance while ensuring sufficient chipping resistance, and satisfies the following formulas (7) and (8): X≦0.7 (7) -6.7X+9.1≦Y (8) It is preferable that the above relationship is satisfied. By reducing the WC phase grain size of the cemented carbide to 0.7 μm, the wear resistance can be further improved. If the WC phase grain size is 0.6 μm or less, the wear resistance is further improved, and it is more preferable that the WC phase grain size is 0.4 μm or less. In addition, if the average grain size X μm of the WC phase and the total amount Y mass % of the binder phase satisfy the relationship -6.7X+9.6≦Y, the cutting edge of the punching tool is less likely to chip and stable processing can be achieved, which is more preferable, and -6.7X+10.1≦Y is even more preferable.

[0036] The surface of the cemented carbide tool according to one embodiment of the present invention may be coated with a hard film depending on the application, thereby extending the tool life. The method for coating the hard film is not particularly limited, and known coating methods such as DLC, PVD, and CVD can be used.

[0037] Furthermore, the surface of the cemented carbide tool according to one embodiment of the present invention can be treated with shot peening, laser peening, etc. Any commonly used method can be used for the shot peening and laser peening.

[0038] An example of the method for manufacturing the cemented carbide tool of the present invention will be described below. However, the method for manufacturing the cemented carbide tool of the present invention is not limited to the following, and any ordinary method for manufacturing a cemented carbide tool such as a tool for punching metal foil can be applied. The raw material powder is wet-mixed in a ball mill or the like, and then dried to prepare a molding powder that will be the raw material of the cemented carbide. The molding powder is molded by a method such as die molding or cold isostatic pressing (CIP). The obtained molded body is sintered in a vacuum or in an inert atmosphere at a temperature equal to or higher than the liquid phase appearance temperature. The liquid phase appearance temperature of the molded body is the temperature at which a liquid phase appears during the heating process of sintering, and is measured using a differential thermal analyzer. The upper limit of the sintering temperature is preferably the liquid phase appearance temperature + 100°C or less. The obtained sintered body may be further subjected to HIP treatment.

[0039] The carbide tool of the present invention can be used to continuously punch out a high-hardness and high-strength metal foil such as an amorphous alloy foil into a predetermined shape. The carbide tool of the present invention is effective for a workpiece having a thickness of about HV200 or more, more effective for a workpiece having a thickness of HV500 or more, and even more effective for a workpiece having a thickness of HV700 or more. The thickness of the workpiece is not particularly limited, and can be applied to a general metal plate having a thickness of 100 to 500 μm such as an electromagnetic steel plate, but is suitable for a metal foil having a thickness of about 10 to 100 μm, and is particularly suitable for a metal foil having a thickness of about 25 to 50 μm. Depending on the workability of the workpiece, punching may be performed in a single layer or a multilayer, and the punching method may be performed in an optimal manner. It is particularly suitable for punching out an amorphous alloy foil without using a lubricant. In addition, even when punching out a plurality of high-hardness and high-strength metal foils such as an amorphous alloy foil that are laminated, the wear of the punching tool can be suppressed. Therefore, the metal foil punching tool of the present invention can be suitably used even when punching a plurality of laminated amorphous alloy foils without using lubricating oil.

[0040] When the WC phase of the cemented carbide alloy falls off from the wear surface of a cemented carbide tool, that area becomes recessed and the sharp corners of the WC particles tend to protrude from the surrounding area, increasing the roughness of the wear surface. As a result, the frictional force between the workpiece and the wear surface during punching also increases, making the wear surface more susceptible to wear. In other words, it was found that the wear surface of a cemented carbide tool with small wear surface roughness experiences less friction with the workpiece during punching and is less susceptible to wear.

[0041] That is, after a punching test of 500 times or more is performed on a laminated material of 5 sheets of amorphous alloy foil having a thickness of 25 μm and a hardness of 900 HV with a clearance of 5% t and without lubrication, the surface roughness Ra of the cutting edge is preferably 0.1 μm or less. Here, a method for measuring the surface roughness Ra of the cutting edge is explained with reference to FIG. 1. The surface roughness Ra of the cutting edge means the line roughness Ra in the direction perpendicular to the punching direction at a position A / 2 from the tool end face when the worn part on the side around the cutting edge of the cemented carbide tool after the punching test is the worn part as shown in FIG. 1 (1) and the distance from the tool end face to the end of the worn part (length in the direction perpendicular to the tool end face) is A (cutoff λc is 8 μm and the rest conforms to JIS B 0601). When it is difficult to measure by avoiding the adhered matter, the value measured at a position in the range of A / 8 to A / 2 from the tool end face may be used as the surface roughness Ra of the cutting edge.

[0042] In addition, if the cutting edge is subjected to C-surface machining (Fig. 1(2)) or R-machining (Fig. 1(3)), etc., the line roughness Ra (cut-off λc is 8μm, and the rest conforms to JIS B 0601) in the direction perpendicular to the punching direction at the worn part position (positions shown by arrows in Fig. 1(2) and Fig. 1(3)) corresponding to the boundary between the machined part and the side part shall be measured. If it is difficult to measure by avoiding adhered matter, or if the cutting edge is machined but the boundary between the machined part and the side part is not clear, follow the measurement position for the tool in Fig. 1(1).

[0043] The method for measuring the line roughness Ra is preferably to measure at three or more locations over a measurement length of 258 μm or more, or after removing the adhered matter, so that the total measurement length is 1,000 μm or more. In order to make it easier to measure while avoiding the adhered matter, it is preferable that the position of A / 2 is located at a position 10 μm or more from the tool end face. After the punching test, the surface roughness Ra of the cutting edge is more preferably 0.06 μm or less, and even more preferably 0.04 μm or less.

[0044] The metal foil punching tool of the present invention can exhibit better wear resistance and chipping resistance when punching is performed using a lubricating oil. It also exhibits excellent performance with laminated materials such as those disclosed in Patent Document 2. It can exhibit excellent performance not only with amorphous alloys but also with nanocrystalline alloys, and can exhibit even better performance when punching normal electromagnetic steel sheets. It can also be applied to punching foils and thin plates used for various purposes, not limited to punching motor cores.

[0045] In the following examples, performance evaluation was performed using tools manufactured by grinding, and it was shown that the cemented carbide tool of the present invention exhibits excellent performance under various punching conditions. If the punching tool has a complex shape, it may be manufactured by electric discharge machining. In this case, for example, if the tool is made of a cemented carbide alloy that places importance on improving chipping resistance, defects that occur during electric discharge machining, which can cause chipping during punching, are minimized, and excellent tool performance can be exhibited. EXAMPLES

[0046] The present invention will be described in more detail with reference to the inventive products, but the present invention is not limited thereto.

[0047] Example 1 As raw powders, WC powder (0.07-1.4μm), Co powder (1.3μm), Ni powder (2.5μm), VC powder (2.2μm), TaC powder (1.2μm), Cr3C2 powder (2.3μm) and Mo2C powder (3.4μm) with different particle sizes were used, and the powders were mixed in the composition shown in Table 1, wet mixed, and dried to obtain a mixed powder. After pressing the mixed powder, it was vacuum sintered at 1320-1400℃, and further HIP processed to produce a sintered body (super hard alloy).

[0048] [Table 1]

[0049] The WC phase grain size, binder phase amount, transverse rupture strength and Vickers hardness of the cemented carbide alloys of the invention samples 1 to 15 and the comparison samples 1 to 5 were measured by the following methods. The results are shown in Table 2.

[0050] (WC phase grain size) The average grain size X of the WC phase in each of the cemented carbide alloys of the invention samples 1 to 15 and the comparative samples 1 to 5 was determined by the Fullman's formula based on the structure of an arbitrary cross section of the cemented carbide alloy.

[0051] (Amount of bonded phase) The binder phase amount Y of the cemented carbide of the invention samples 1 to 15 and the comparative samples 1 to 5 was determined as the mass ratio of the blended composition.

[0052] (transverse rupture strength) The flexural strength (MPa) of the cemented carbide alloys of the invention samples 1 to 15 and the comparative samples 1 to 5 was determined by flexural strength measurement (three-point bending test) according to the method of JIS B4104.

[0053] (Vickers hardness) The Vickers hardness (HV) of the cemented carbide alloys of the invention products 1 to 15 and the comparative products 1 to 5 was measured using a Vickers hardness tester HV30.

[0054] [Table 2]

[0055] Using the cemented carbide alloys of the invention products 1 to 15 and the comparative products 1 to 4, punching tools with a punching shape of 5 mm square were produced by grinding. Corresponding dies were also produced from cemented carbide alloy (WC-1.0%Cr3C2-15Co, WC phase grain size 1.4 μm), and using these punching tools, punching tests were performed on amorphous alloy foils (thickness 25 μm). At that time, since the tendency of tool life varies depending on the punching conditions, the punching tests were performed under the following two conditions (Test A, Test B). Note that a punching test was not performed on the comparative product 5 because the binder phase amount Y was as small as 1 mass%, and pores were generated. (1) Test A: A single layer of amorphous alloy foil (thickness 25 μm, hardness 900 HV) was punched with a clearance of 10% t and without lubrication. (2) Test B: Five sheets of the above amorphous alloy foil were simply stacked (total thickness 125 μm) and punched with a clearance of 5% t and without lubrication.

[0056] After the test, the cutting edge of each punching tool was observed and evaluated for wear resistance and chipping resistance. Wear resistance was evaluated as ◯ for small wear, △ for some wear but still usable, and × for large wear. Chip resistance was evaluated as ◯ for no chipping or chipping, △ for small chipping, and × for relatively large chipping. The results are shown in Table 3.

[0057] [Table 3]

[0058] (1) About Test A The comparative products 1 and 2 had low wear resistance because the WC phase grain size was larger than 1.2 μm. The comparative product 3 had a WC phase grain size smaller than 1.2 μm, but the binder phase amount was 27 mass% relative to the WC phase grain size, so the hardness was very low and the wear resistance was poor. The comparative product 4 had a WC phase grain size of 0.25 μm, but the binder phase amount was 39 mass% relative to the WC phase grain size, so the hardness was very low and the wear resistance was poor. The invention products 1 to 5 and 14 had high hardness, so micro-chipping occurred, but it was not a problem in use. In addition, the WC phase grain size was smaller than 1.2 μm and the hardness was high, so the wear resistance was excellent. The invention products 6 to 9, 11 and 12 had a hardness that was not too high, so no chipping or chipping was observed, and the WC phase grain size was smaller than 1.2 μm, so the wear resistance was also excellent. Invention samples 10 and 13 had low hardness due to the WC phase grain size of 1.0 μm and 0.90 μm, respectively, close to 1.2 μm, and therefore wore to some extent but were usable. Invention sample 15 had a small WC phase grain size of 0.25 μm, but a large binder phase amount of 34 mass%, and therefore low hardness, and therefore wore to some extent but was usable.

[0059] (2) About Test B Comparative product 1 had micro-chipping due to its high hardness, but this was not a problem for use. In addition, the WC phase grain size was larger than 1.2 μm, so the wear resistance was low. Comparative product 2 did not show any chipping or chipping, but the WC phase grain size was larger than 1.2 μm and the hardness was low, so the wear resistance was low. Comparative product 3 had a WC phase grain size smaller than 1.2 μm, but the amount of binder phase was 27 mass% relative to the WC phase grain size, so the hardness was very low and the wear resistance was poor. Comparative product 4 had a WC phase grain size of 0.25 μm, but the amount of binder phase was 39 mass% relative to the WC phase grain size, so the hardness was very low and the wear resistance was poor. Invention products 1 to 4 and 14 had too high hardness, so large chipping occurred in the early stages of punching. In addition, since they became unusable early on, a quantitative comparison of the wear amount was not possible. Invention products 5 and 6 had excellent wear resistance because the WC phase grain size was smaller than 1.2 μm, but large chipping occurred because the hardness was too high. Invention products 7, 8, and 10 had high hardness, so micro-chipping occurred, but this was not a problem for use. They also wore to a certain extent, but were usable. Invention product 9 had a small WC phase grain size of 0.24 μm, so it also had excellent wear resistance. They also wore to a certain extent, but this was not a problem for use. Invention products 11 to 13, and 15 had low hardness, so they wore to a certain extent, but were usable.

[0060] Example 2 In the punching test B carried out in Example 1, the surface roughness Ra of each worn portion of the cutting edge was measured after 500 shots and 1000 shots for the invention products 5, 7 and 9, and the comparative product 2. The measurement position was the line roughness at the specified position, and the measurement was carried out using a laser microscope OLS4100 (manufactured by Olympus Corporation) at four points over a measurement length of 258 μm, avoiding adhesions or after removing adhesions, and the cutoff λc was set to 8 μm, and the values ​​calculated in accordance with JIS B 0601 were averaged for the rest. The results are shown in Table 4.

[0061] [Table 4]

[0062] Invention product 5 had excellent wear resistance because the surface roughness Ra of the punch blade tip was 0.1 μm or less and the hardness was high at HV1530. Invention product 7 had some wear to the surface roughness of the punch blade tip, but was still usable. Invention product 9 had excellent wear resistance because the surface roughness Ra of the punch blade tip was very small. Comparative product 2 had poor wear resistance because the surface roughness Ra of the punch blade tip exceeded 0.1 μm.

Claims

1. The alloy includes a WC phase and a binder phase including Co. The average grain size of the WC phase is X μm, and the total amount of the binder phase is Y mass %. The following formulas (1), (2), and (3) are satisfied: X≦1.2 (1) 2≦Y ・・・(2) -6.7X+6≦Y≦-14X+38 ・・・(3) Fulfilling The alloy contains 2 to 20 mass% of Cr and / or V in terms of carbide relative to the total amount of the binder phase. A carbide tool for punching metal foil or thin plate.

2. The total amount Y mass% of the binder phase is determined by the following formula (4): -7X+12≦Y ... (4) 2. The cemented carbide tool for punching a metal foil or thin plate according to claim 1, wherein the above-mentioned satisfies the above.

3. The total amount Y mass% of the binder phase is determined by the following formula (5): X≦0.9 ・・・(5) 3. The cemented carbide tool for punching a metal foil or thin plate according to claim 2, wherein the above-mentioned satisfies the above.

4. The total amount Y mass% of the binder phase is expressed by the following formula (6): -11X+22≦Y ... (6) 2. The cemented carbide tool for punching a metal foil or thin plate according to claim 1, wherein the above-mentioned satisfies the above.

5. The total amount Y mass% of the binder phase is determined by the following formula (7): X≦0.67 ・・・(7) 2. The cemented carbide tool for punching a metal foil or thin plate according to claim 1, wherein the above-mentioned satisfies the above.

6. Contains at least one element selected from the group consisting of Groups 4 to 6 of the periodic table other than Cr and V. fruit, The total content of the elements is 0.2 to 5 mass % in terms of carbide.

6. A carbide tool for punching a metal foil or thin plate according to any one of claims 5 to 5.

7. Carbides and / or carbonitrides of Cr and / or V, or Cr and / or V and periodic elements other than Cr and V The cemented carbide tool for punching metal foil or thin plate according to any one of claims 1 to 5, characterized in that it contains a compound phase consisting of a carbide and / or carbonitride with at least one element selected from the group consisting of Groups 4 to 6 of the Taguchi table.

8. The cemented carbide tool for punching metal foils or thin plates according to any one of claims 1 to 5, characterized in that the binder phase contains at least one of Ni and Fe.

9. The carbide tool for punching metal foils or thin plates according to claim 6, characterized in that the binder phase contains at least one of Ni and Fe.

10. 6. The cemented carbide tool for punching metal foil or thin plate according to any one of claims 1 to 5, characterized in that it is a tool for punching metal foil having a thickness of 10 to 100 μm and a hardness of 700 HV or more.

11. 11. The carbide tool for punching metal foils or thin plates according to claim 10, wherein the metal foil is an amorphous alloy foil.

12. Clearance was applied to a laminate of five amorphous alloy foils with a thickness of 25 μm and a hardness of 900 HV. The carbide cutting tool for punching metal foil or thin plate according to any one of claims 1 to 5, characterized in that after a punching test of 500 times or more is performed with a 5% t lubrication and no lubrication, the surface roughness Ra of the cutting edge is 0.1 μm or less. Ingredients.

13. The cemented carbide tool for punching metal foil or thin plate according to any one of claims 1 to 5, characterized in that it is coated with a hard coating.