JP7575028B1 - Carbide Tools - Google Patents

Abstract

A cemented carbide tool using a cemented carbide alloy consisting of 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 the cemented carbide tool contains 2 to 20 mass % of Cr and/or V, calculated as carbide, with respect to the total amount of the binder phase.

Description

The present invention relates to a cemented carbide tool.

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. Iron cores for motors and other devices are often made of multiple laminated electromagnetic steel sheets to achieve low iron loss and high magnetic flux density. Amorphous alloy foil in particular exhibits excellent mechanical properties, magnetic properties, corrosion resistance, and other properties. As its magnetic properties are particularly excellent, using amorphous alloy foil instead of regular electromagnetic steel sheets is expected to significantly improve performance.

While magnetic steel sheets used in the iron cores of motors and the like are generally 100 to 500 μm thick, amorphous metal foil is around 10 to 100 μm thick, and therefore requires multiple punching operations. However, when continuously punching high-hardness, high-strength metal foil such as amorphous alloy foil into a specified shape, the punching tools wear out rapidly, resulting in a short tool life.

JP 2021-130131 A (Patent Document 1) discloses a method for forming a plastically processed groove that becomes a punched outline of a predetermined shape on the surface of an amorphous alloy ribbon, and performing punching along the plastically processed groove with a punching punch and die to obtain an amorphous alloy piece. By forming a plastically processed 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.

In addition, when punching amorphous alloy foil, multiple alloy foils may be stacked to ensure productivity, but as the number of layers 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.

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 sheets of amorphous alloy foil is provided with a first edge formed on the tip face of the punch and a second edge formed on the side face of the punch, and the horizontal distance from the first edge to the side face of the punch and the vertical distance from the second edge to the tip face of the punch are set to predetermined distances. When multiple laminated sheets of amorphous alloy foil are punched, the tip of the punching tool is shaped to a predetermined shape so that a product with no cracks and high dimensional stability can be obtained.

JP 2021-130131 A JP 2023-8048 A Patent No. 7129048

However, the manufacturing method of Patent Document 1 requires the pre-formation of a plastic processing groove that will become the punched contour line of a predetermined shape, which requires a special processing tool and increases the number of steps. The punching method of Patent Document 2 requires a process to create a laminated material in which an elastic coating is applied between alloy foils. The shear processing method of Patent Document 3 requires the tip of the punching tool to be shaped to a predetermined shape, which limits the freedom of processing.

As described above, research has been conducted into the processing of amorphous alloy foil and the shape of punching tools, but there has been no research into cemented carbide alloys that are suitable as materials for tools to continuously punch out high-hardness, high-strength metal foil (single layer or multiple laminated sheets) into a specified shape.

Therefore, the object of the present invention is to provide a carbide tool suitable for continuously punching high-hardness, high-strength metal foil (single layer or multiple laminated sheets) into a predetermined shape.

The present invention relates to a cemented carbide that is optimal for punching tools for punching high-hardness, high-strength metal foils (single layer or multi-layer laminates) such as amorphous alloy foils. In order to solve the above problems, the present invention investigated in detail the wear and damage patterns of punching tools for amorphous alloy foils and attempted to improve them.

The most important point is that the hardness and wear resistance of the cemented carbide used in punching tools for 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, to improve the wear resistance of punching tools, a cemented carbide with high hardness is selected, but this also reduces 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.

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. For this reason, the stress when the adhered material is pulled off during punching is also small, and the larger the WC grain size, the better the support force of the binder phase. Therefore, when comparing cemented carbide alloys with the same hardness but different WC grain sizes, cemented carbide alloys with a relatively large WC phase grain size have better wear resistance and do not drop out particles.

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, a large amount of material adheres to the punching tool of the processed material, and because amorphous alloys are hard and strong, the stress when the adhered material is peeled off is very large. As a result, even WC phases with large particle sizes and high support power by the binder phase fall off due to the stress when the adhered material is peeled off, causing wear on the punching tool.

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 loses less volume when it falls off, and therefore the total lost volume (i.e., wear amount) due to repeated falling off is smaller. In other words, 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 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 that has a higher hardness within the range where the punching tool does not chip under specified punching conditions and is used for the punching tool, it is possible to achieve both superior wear resistance and chipping resistance compared to conventional cemented carbide punching tools.

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 %. The following formulas (1), (2) and (3):
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, calculated as carbide, relative to the total amount of the binder phase.

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

In one embodiment of the present invention, the total amount Y (wt%) 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.

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% calculated as carbide,
It is preferable that the alloy 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.

In one embodiment of the cemented carbide tool of the present invention, it is preferable that the binder phase contains at least one of Ni and Fe.

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

In one embodiment of the present invention, in a cemented carbide tool, after a punching test of 500 or more times is performed on a laminated material made of five layers of amorphous alloy foil, each having a thickness of 25 μm and a hardness of 900 HV, with a clearance of 5% t and without lubrication, it is preferable that the surface roughness Ra of the cutting edge is 0.1 μm or less.

In one embodiment of the present invention, the carbide tool is preferably coated with a hard coating.

According to the present invention, a carbide tool is obtained that is suitable for continuously punching out high-hardness, high-strength metal foil (single layer or multiple laminated layers) into a predetermined shape.

FIG. 4 is a schematic diagram showing measurement positions of the line roughness Ra of the worn portion.

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 %. The following formulas (1), (2) and (3):
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, calculated as carbide, relative to the total amount of the binder phase.

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 any 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 high-hardness and high-strength metal foil (single layer or multiple laminated foils), making it 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.

The total amount Y (mass%) of the binder phase is 2 or more and satisfies 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.

In addition to the main component Co, the binder phase preferably contains at least one of Ni and Fe. 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. It may also contain components that can be used as binder phases, such as Al and Cu. These components correspond to the components added as the binder phase components described above. Furthermore, metal elements that make up the hard phase can be 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 be contained in 70 mass% or more of the total amount of the binder phase, and more preferably 80 mass% or more.

The cemented carbide of the present invention contains 2 to 20 mass% Cr and/or V in terms of carbide relative to the binder phase. Adding 2 to 20 mass% Cr in terms of carbide inhibits grain growth of WC during sintering and improves corrosion resistance. Adding 2 to 20 mass% V in terms of carbide provides an even greater grain growth inhibition effect than Cr. 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%.

At least one element selected from the group consisting of Groups 4 to 6 of the periodic table other than Cr and V may be included. 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.

It is preferable that the compound phase contains 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 present 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, (W, Ti, Nb)C, etc. It is more preferable that the particle size of the compound phase is 0.05 to 1 μm.

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 while increasing the amount of the binder phase mainly composed of Co, it is possible to obtain a more suitable cemented carbide metal foil punching tool that is less likely to chip at the cutting edge even when continuously punching a high-hardness, high-strength metal foil (single layer or multiple laminated sheets) into a predetermined shape.

In order to further improve chipping resistance and wear resistance as compared with conventional products, a cemented carbide tool according to one embodiment of the present invention has a composition 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.

In addition, the cemented carbide tool according to one embodiment of the present invention has an advantage of improving 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.

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. This can extend the tool life. There is no particular limitation on the method for coating the hard film, but known coating methods such as DLC, PVD, and CVD can be used.

In addition, the surface of the cemented carbide tool according to one embodiment of the present invention can be treated with shot peening, laser peening, or the like to enhance chipping resistance. For shot peening and laser peening, methods that are commonly used can be used.

An example of a method for manufacturing a cemented carbide tool of the present invention is described below. However, the method for manufacturing a 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 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 for 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 occurs 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.

The carbide tool of the present invention can be used to continuously punch out high-hardness and high-strength metal foils such as amorphous alloy foils into a predetermined shape. The carbide tool of the present invention is effective for workpieces of about HV200 or more, more effective for workpieces of HV500 or more, and even more effective for workpieces of HV700 or more. The thickness of the workpiece is not particularly limited, and can be applied to general metal plates of 100 to 500 μm thick, such as electromagnetic steel sheets, but is suitable for metal foils of about 10 to 100 μm thick, and particularly suitable for metal foils of about 25 to 50 μm thick. Depending on the workability of the workpiece, punching may be performed in a single layer or in a multi-layered form, and the punching method may be performed in an optimal manner. It is particularly suitable for punching out amorphous alloy foils without using lubricating oil. Even when punching out multiple layers of high-hardness and high-strength metal foils such as amorphous alloy foils, 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.

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 low wear surface roughness experiences less friction with the workpiece during punching and is less susceptible to wear.

That is, after a punching test of 500 times or more is performed on a laminated material consisting of five layers of amorphous alloy foil with 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, the method for measuring the surface roughness Ra of the cutting edge is explained using Figure 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 Figure 1 (1) and the distance from the tool end face to the end of the worn part (length perpendicular to the tool end face) is A (cutoff λc is 8 μm, and the rest conforms to JIS B 0601). If it is difficult to measure by avoiding adhered materials, 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.

In addition, if the cutting edge has been 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 indicated 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 has been 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).

The method for measuring line roughness Ra is preferably to avoid adhered matter or to remove the adhered matter and then measure at three or more locations with a measurement length of 258 μm or more so that the total measurement length is 1,000 μm or more. In order to make it easier to measure while avoiding adhered matter, it is desirable for the position of A/2 to be 10 μm or more from the tool end face. After the above 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.

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 sheets used for various purposes, not limited to punching motor cores.

In the following examples, performance evaluation was performed on tools made by grinding, and it was shown that the carbide tool of the present invention exhibits excellent performance under various punching conditions. If the punching tool has a complex shape, it may be made by electric discharge machining. In this case, for example, if the tool is made of a carbide alloy that emphasizes improved chipping resistance, it is possible to minimize defects that occur during electric discharge machining, which can cause chipping during punching, and exhibit excellent tool performance.

The present invention will be described in further detail with reference to the inventions, but the present invention is not limited thereto.

Example 1
The raw powders used were 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, and were wet mixed and dried to obtain a mixed powder as shown in Table 1. This mixed powder was pressurized and then vacuum sintered at 1320-1400℃, and further HIP treated to produce a sintered body (super hard alloy).

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

(WC phase grain size)
The average grain size X of the WC phase in the cemented carbide 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.

(Amount of binding phase)
The binder phase amount Y of the cemented carbide alloys of the invention products 1 to 15 and the comparative products 1 to 5 was determined as the mass ratio of the blended composition.

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

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

Punching tools with a punching shape of 5 mm square were produced by grinding each of the cemented carbide alloys of invention products 1 to 15 and comparison products 1 to 4. Corresponding dies were also produced from cemented carbide alloy (WC-1.0% _Cr3C2-15Co , WC phase grain size 1.4 μm), and punching tests of amorphous alloy foils ₍ thickness 25 μm) were carried out using these punching tools. At that time, since the tendency of tool life varies depending on the punching conditions, the punching tests were carried out under the following two conditions (Test A, Test B). Note that a punching test was not carried out for comparison 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.

After the test, the cutting edges of the punching tools were observed and evaluated for wear resistance and chipping resistance. Wear resistance was rated as ◯ for small wear, △ for some wear but still usable, and × for large wear. Chipping resistance was rated as ◯ for no visible chipping or chipping, △ for small chipping, and × for relatively large chipping. The results are shown in Table 3.

(1) Test A Comparative products 1 and 2 had low wear resistance because the WC phase grain size was larger than 1.2 μm. Comparative product 3 had a WC phase grain size smaller than 1.2 μm, but the binder phase amount was 27 mass% higher than 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 binder phase amount was 39 mass% higher than the WC phase grain size, so the hardness was very low and the wear resistance was poor. Invention products 1 to 5 and 14 had high hardness, so micro-chipping occurred, but it was not a problem for 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. 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.

(2) 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 binder phase amount was 27 mass% higher than 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 binder phase amount was 39 mass% higher than 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 enough to affect use. Invention product 9 also had excellent wear resistance because the WC phase grain size was small at 0.24 μm. It also had micro-chipping, but this was not enough to affect use. Invention products 11 to 13, and 15 had low hardness, so they were worn to some extent, but were still usable.

Example 2
In 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 invention products 5, 7 and 9, and comparative product 2. The measurement positions were the line roughness at the above-mentioned predetermined positions, and measurements were taken at four locations over a measurement length of 258 μm using a laser microscope OLS4100 (Olympus Corporation), avoiding any adhered matter or after removing the adhered matter, with a cutoff λc of 8 μm and the values calculated in accordance with JIS B 0601 for the rest being averaged. The results are shown in Table 4.

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. Comparison product 2 had poor wear resistance because the surface roughness Ra of the punch blade tip exceeded 0.1 μm.

Claims (13)

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
A carbide tool for punching metal foils or thin plates, comprising 2 to 20 mass% of Cr and/or V, calculated as carbide, based on the total amount of the binder phase. 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. 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 . The total amount Y mass% of the binder phase is determined 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 condition is satisfied. 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. Contains 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 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 . Carbides and/or carbonitrides of Cr and/or V, or Cr and/or V and periods other than Cr and V
Carbide and/or carbonitride with at least one element selected from the group consisting of Groups 4 to 6 of the fundamental table The metal foil or the metal sheet according to any one of claims 1 to 5, characterized in that it contains a compound phase consisting of an oxide. is a carbide tool used for punching thin plates. 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. 7. The method according to claim 6, wherein the binder phase contains at least one of Ni and Fe. A carbide tool for punching metal foil or thin plate. 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. The carbide tool for punching metal foils or thin plates according to claim 10 , wherein the metal foil is an amorphous alloy foil. 6. The carbide tool for punching metal foils or thin plates according to any one of claims 1 to 5, characterized in that after a punching test is conducted 500 times or more on a laminate material having five stacked amorphous alloy foils each 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 0.1 μm or less. 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.

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