JP2835709B2 - Manufacturing method of composite tool material in which steel and cemented carbide are joined - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite tool comprising a cemented carbide and a steel member, and more particularly, to a high-strength and highly-reliable composite tool used for punching and hot forging.
It is intended to provide a method for manufacturing a material .

[0002]

2. Description of the Related Art Heretofore, this type is as follows. For punching tools, rotating and forging tools, it has excellent wear resistance,
Materials that can withstand impact loads and thermal shocks are desired. However, it is difficult to satisfy such contradictory characteristics (hardness and toughness) with one material, and therefore, material development has been promoted from the viewpoint of compounding the materials. Cemented carbides have lower toughness than ordinary hardened steels, but their hardness far exceeds the hardness of hardened steels and exhibits excellent wear resistance. Hardened steel, on the other hand, is inferior to cemented carbide in terms of hardness, but its toughness (strength) far exceeds that of cemented carbide. For tool applications such as those described above, the machined part that comes into contact with the workpiece requires high hardness and excellent wear resistance, but the parts that support it are more resistant to repeated load stress and impact rather than wear resistance. It is required to be able to withstand excellent strength. In order to satisfy such demands, a tool in which the supporting portion is made of hardened steel and a cemented carbide is directly or indirectly joined to a processed portion is manufactured.

[0003] For joining steel and cemented carbide, joining using a filler metal or a thin metal plate is widely used, and in addition, there are a welding method, a sintering joining method using an intermediate material, and a direct joining method. Although there is a caulking method as a mechanical joining method, it is unsuitable for use applications where a repeated load or impact is applied. In the diffusion bonding method using a filler material, silver filler, copper filler, Ni filler, and the like are used. Japanese Patent Publication No. 7-12566 proposes a method of improving bonding strength by preventing a diffusion material from existing in a bonding interface in a single phase after bonding in a diffusion bonding method. As a joining method by welding, a method using a high energy beam is disclosed in, for example, Japanese Patent Publication No. 2-28428,
It has been proposed in Japanese Patent Publication No. 4-52180. In this method, a metal thin plate or filler is inserted between the joining materials, and the cemented carbide side near the joint is heated by a laser beam or the like while applying pressure, and the heat is transmitted to the inserted material side to melt and join with the steel I do. JP-A-53-1609 discloses a method in which a WC powder containing 80% of a metal component is disposed as an intermediate layer between steel and a cemented carbide, and the two materials are sintered and joined while sintering the intermediate layer. A method has been proposed. Further, Japanese Patent Application Laid-Open No. 52-509
No. 07 proposes a method of directly joining a cemented carbide containing 15% of Co to carbon steel.

[0004]

The above-mentioned prior art has the following problems. As the cemented carbide constituting the machined part of the tool, a cemented carbide of high hardness, in which the amount of contained metal binder phase is minimized, is used in order to secure the wear resistance. In conventional diffusion bonding using filler metal and thin metal sheets, the cementability of the cemented carbide having such properties and the filler metal and metal components melted at high temperatures (wetability) is poor, resulting in a joint strength. There was a problem that it was difficult to come out. Further, in common with other joining methods, there is a problem of generation of residual stress after joining based on a difference in thermal expansion between steel and cemented carbide. If the difference in thermal expansion between the two is large and the residual stress exceeds the tensile strength of the cemented carbide, cracks may occur on the cemented carbide side near the joint surface or peel off at the joint surface with the release of stress. was there. Even when such cracking or peeling does not occur, a certain amount of stress remains at the joint,
Due to the residual stress, there is a problem that the bonding strength itself is reduced or a sudden breakdown occurs during use.

Attempts have been made to reduce the temperature rise on the steel side during welding by local heating with a laser beam, reduce the amount of shrinkage after welding on the steel side, and consequently reduce the residual stress at the joint. In this method, the cemented carbide is first heated locally. It is also heated instantaneously by inputting large energy at once. For this reason, there has been a problem that micro and macro cracks are generated in a cemented carbide portion intended to constitute a processed portion due to a thermal shock, and the cemented carbide itself is deteriorated. The application of this method is limited to small items due to the nature of the method. Furthermore, in this method, the energy supplied instantaneously is enormous, delicate temperature control is difficult, and there are problems in the quality of the bonding material such as generation of a brittle compound due to overheating and bonding strength failure due to insufficient heating. .

[0006] On the other hand, in the direct joining of a sintered cemented carbide and steel, it is difficult to achieve perfect adhesion between both joining surfaces until the joining temperature is reached, and the joining surfaces are contaminated in the atmosphere during the heating stage, and the contaminants are contaminated by both. In addition, it inhibits the diffusion of the alloy, which is one of the causes of the decrease in the bonding strength. In addition, in order for the steel to soften and fill the micro-roughness of the cemented carbide to join, it is necessary to apply heat and pressure to a point close to the melting point of the steel. Further, there has been a problem that a brittle compound is generated by the reaction between the cemented carbide and iron at such a high temperature. WC containing 80% by weight of metal binder phase between sintered cemented carbide and steel
The method of arranging the powder is effective for improving the above-mentioned adhesion, but has a large metal content and cannot be expected to serve as a stress relaxation layer between the steel and the cemented carbide. In addition, the bonding between the intermediate layer and the steel side is relatively strong because both materials are similar, but the bonding between the intermediate layer and the sintered cemented carbide is the same as that of the conventional type. , Strong joints cannot be obtained. As described above, the conventional two joining methods of steel and cemented carbide have the following two main problems. The generation of residual stress due to the difference in thermal expansion between steel and cemented carbide and the resulting decrease in bonding strength, the lack of fusion between high-hardness cemented carbide and steel or other metals, and the resulting decrease in joint strength. .

[0007] The present invention has been made to solve these problems. That is, a cemented carbide having a large amount of a metal bonding phase that can be welded to steel is disposed in a portion in contact with steel, and a superhard and highly wear-resistant superhard alloy is formed directly or through an intermediate layer with the weldable cemented carbide. By joining with a hard alloy, it secures fusibility with steel and increases the joining force.Furthermore, by making this weldable cemented carbide and the intermediate layer part a stress relaxation layer, the generation of residual stress is minimized. An object of the present invention is to reduce the stress and disperse the stress in each layer to provide a strong composite tool material having the high hardness inherent in cemented carbide and the high toughness of steel.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention is as follows. One of the inventors of the present invention is to select and combine the upper and lower punch materials appropriately in accordance with the combination of the materials to be sintered in the electric current sintering of the inclined material composed of the combination of metal and ceramic. As a result, it has been found that the gradient material can be sintered in a short time without difficulty under an appropriate temperature gradient according to the gradient composition, and an application of Japanese Patent Publication No. 6-102803 was filed.
Also, in Japanese Patent Publication No. 7-84352, when electrically conducting sintering of the same inclined material as described above, the heat of the material constituting the inclined material whose thickness in the pressing axis direction of the molding outer frame is to be sintered is considered. Invented a method of sintering under the required temperature gradient by adjusting according to the mechanical properties. further,
Japanese Patent Application Laid-Open No. 7-300375 invents a cemented carbide-based wear-resistant material having both excellent wear resistance and weldability to steel. In producing this cemented carbide-based wear-resistant material by an electric current sintering method, The thickness of the molding outer frame in the pressing axis direction is appropriately adjusted in accordance with the amount of the metal binding phase in the raw material powder to be sintered, and the heat balance is adjusted by using the difference in heat capacity to obtain the raw material powder. Has been invented a method of sintering under a temperature gradient suitable for its constituent material without any excess or shortage.

The present invention has been made based on these inventions. That is, a weldable layer 1b made of a WC-based cemented carbide containing 20% by weight or more and 60% by weight or less of a metal bonding phase which is sintered and bonded directly or via an intermediate layer;
With a processed part 1 comprising a wear-resistant layer 1a made of a WC-based cemented carbide containing 3% by weight or more and less than 20% by weight of a metal binder phase, a composite tool material integrally joined to steel is formed into an outer frame 3 In the method of manufacturing by the electric current sintering method using
The thickness of the molded outer frame in the direction of the pressing axis is abrasion-resistant layer raw material powder 1a.
By increasing the shape of the molding outer frame from at least one to the side of the weldable layer raw material powder 1b1 continuously or stepwise, and making the formed outer frame at least one energizing path, the pressurized axial direction of the processed part raw material powder 4 during energization The present invention provides a method for producing a composite tool material in which steel and a cemented carbide are joined by sintering and joining to a steel 2 while sintering the raw material powder while forming a temperature gradient in the workpiece.

In this case, the following configuration can be adopted.
Wear. Joining a steel having a mean particle size of WC particles of 1 μm or less and a cemented carbide in a WC-based cemented carbide constituting a wear-resistant layer
You. In addition, a steel and a cemented carbide are used in which the metal binding phase of the WC-based cemented carbide constituting the machined part is one or more of Co, Ni, and Fe, or an alloy containing these metals.
I do .

In a normal electric sintering method using a forming outer frame and upper and lower punches, first, a powder to be sintered is filled in a state where the lower punch is set in the forming outer frame, and then the upper punch is pushed into the upper and lower punches. Pressurized via In this state, a direct current or an alternating current or a superimposed current is passed through the upper and lower punches, and sintering is performed by Joule heat using the electric resistance of the material to be sintered. Here, when the molding die is designed so that the molding outer frame serves as one energizing path, and the thickness of the molding outer frame in the pressing axis direction is changed, the heat generated there is changed in accordance with the thickness change. The amount can be controlled, and a temperature gradient including irregularities can be provided as needed in the direction of the pressure axis of the sample portion. The electrical resistance is high in the part where the molded outer frame is thinner than the others, the amount of heat generated under a constant current is large, and the temperature is high. On the other hand, in the thickened portion, on the other hand, the resistance is low, the heat generation is small, and a low temperature region is formed.

According to this method, on the material side requiring a high temperature for sintering, the temperature can be increased by making the thickness of the surrounding outer frame thinner than the others, and at the same time, the temperature on the other material side is higher than necessary. The rise can be suppressed. If a large temperature difference is required,
A method in which a jig having a large heat capacity is placed on one side and used as a heat sink, or a method using a combination of materials having different thermal conductivities as upper and lower punches as in JP-A-102803 and JP-A-7-300375 is adopted. be able to. The degree of the change in the thickness of the molded outer frame here needs to be in a range that allows the molded outer frame to function as a pressure vessel while having a low pressure, and that its strength is acceptable.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 shows that the processed part of the composite tool material is composed of a wear-resistant layer 1a having a small amount of a metal binding phase and a weldable layer 1b having a large amount of a metal binding phase. It is a longitudinal cross-sectional view of the composite tool material which joined the cemented carbide. FIG. 2 shows an intermediate layer 1c made of a cemented carbide having a metal binder phase intermediate between the two layers.
FIG. 3 is a longitudinal sectional view of a composite tool material in which steel and cemented carbide are joined by sintering and joining with steel using a weldable layer.

Whether the cemented carbide portions having different amounts of metal bonding phases constituting the processed portion are formed by direct joining or joining with an intermediate layer is determined by the cemented carbide constituting the wear-resistant layer 1a and the weldable layer 1b. Due to the amount of metal binding phase in the alloy and the difference between them,
Also, it is appropriately selected according to the use. As a rough guide, the direct sintering bonding of FIG. 1 can be adopted for a combination in which the difference between the amounts of the metal binding phases in both layers is less than 15%.
The thickness of the intermediate layer and the number of steps are appropriately determined according to the amount of the metal bonding phase in the cemented carbide constituting the wear-resistant layer and the weldable layer, that is, the thermal expansion difference between the two and the use environment.

By using one or more of Co, Ni and Fe or an alloy containing them as the metal binder phase in the cemented carbide constituting the machined part 1, the hardness and strength of the tool machined part can be reduced. As a result, a strong bond with the steel base material can be formed. Here, the type of the metal binding phase in each layer of the cemented carbide constituting the processed portion does not necessarily need to be the same, and a different metal binding phase can be selected according to the purpose. It is desirable that the amount of metal binder phase in the cemented carbide constituting the wear-resistant layer be as small as possible from the viewpoint of wear resistance and corrosion resistance, but it is necessary to have a certain level of impact strength in practical use. The amount required was 3% by weight or more and less than 20% by weight. Preferably, the content was 5% by weight or more and 15% by weight or less. If the content is less than 3% by weight, sintering itself becomes difficult, and it becomes weak to impact load, so that a practical tool material cannot be obtained. On the other hand, when the amount is 20% by weight or more, chipping resistance is excellent, but abrasion resistance becomes inferior.
The significance of joining cemented carbide to steel and turning it into a tool is diminished. Further, by setting the size of the WC particles in the cemented carbide constituting the wear-resistant layer to 1 μm or less, a processed portion having excellent wear resistance can be formed.

In addition to joining with steel, the amount of metal binder phase in the cemented carbide constituting the weldable layer serving as a stress relaxation layer between the cemented carbide of the wear-resistant layer and the steel is 20% by weight or more. , 6
It was necessary to be 0% by weight or less. Preferably,
The content was 25% by weight or more and 50% by weight. If the amount of the metal bonding phase is less than 20% by weight, the effect as a stress relaxation layer between the steel and the steel cannot be exerted, and a strong bond with the steel cannot be obtained. On the other hand, if the amount exceeds 60% by weight, the difference in the amount of the metal bonding phase with the cemented carbide constituting the wear-resistant layer becomes too large, making it difficult to integrally sinter, and also as a stress relaxation layer. Will not work. Further, the hardness of a cemented carbide containing 60% by weight or more of a metal binder phase is so low that it does not reach the hardness of hardened steel, and is not practical.

FIG. 3 schematically shows an electric current sintering method for explaining one embodiment of the present invention. FIG. 3 shows a sintered sample configuration for producing a composite tool material in which a wear-resistant layer and a weldable layer are sinter-bonded via an intermediate layer and which are sinter-bonded to steel using the weldable layer of a processed portion formed by sinter-bonding. , Large amount of metal binding phase,
Therefore, the weldable layer raw material powder 1b1 which does not require high temperature for sintering
Is filled on the steel 2 also serving as the lower punch, and the intermediate layer raw material powder 1c1 and the wear-resistant layer raw material powder 1a1 are stacked and filled thereon, and the upper punch 5 is set. The thickness of the forming outer frame 3 in the pressing axis direction is adjusted according to the required sintering temperature of each layer and the thickness of each layer after sintering. In the present embodiment, the forming around the steel as the lower punch is performed. Increase the thickness of the outer frame,
An example is shown in which a molded outer frame whose wall thickness is reduced stepwise in the order of the weldable layer raw material powder, the intermediate layer raw material powder, and the wear-resistant layer raw material powder is shown.

In the sinter joining step, the steel 2 also serving as a lower punch is set on the molded outer frame 3 which has been thickened as described above.
A processing part raw material powder 4 consisting of a wear-resistant layer raw material powder 1a1, an intermediate layer raw material powder 1c1, and a weldable layer raw material powder 1b1 is filled, and an upper punch 5 is set. I do. After setting, the atmosphere is adjusted to a vacuum or inert atmosphere, and then pressurized to a predetermined pressure.
Thereafter, energization is started by the power supply 8 via the upper and lower electrodes 6 and 7, and the raw material powder 4 to be processed is joined to the steel 2 while sintering. FIG. 5 shows an embodiment in which a sleeve jig 10 is arranged on the steel side of the molded outer frame 3. By the arrangement of this sleeve jig,
It is used when the relative position between the steel joint surface and the molding outer frame can be fixed, the heat can escape from the molding outer frame can be increased, and a larger temperature gradient is required than the sample configuration shown in FIG. Also,
By processing and arranging the inner diameter of the sleeve jig 10 so as to be in contact with the outer shape of the steel, deformation of the steel during sintering while pressing is advantageously suppressed. Here, the molded outer frame 3 and the sleeve jig 10 can be manufactured integrally. When a larger temperature gradient is required, a sample configuration as shown in FIG. 4 can be used. In this embodiment, a block jig 9 having a large heat capacity is arranged on the steel side.

In the method according to the invention, steel can be arranged as the lower punch. Steel has a low electrical resistance and is less likely to generate heat than graphite, and has a high thermal conductivity, which is convenient for heat diffusion, and is convenient for forming a temperature gradient in the portion of the raw material powder in the processed part. 4 and 5 are selected depending on the degree of difference in sintering temperature of the cemented carbide constituting the wear-resistant layer and the weldable layer. However, here, it is a sinter joint with steel, and since there is an upper limit temperature of the joint with the steel, a temperature gradient in consideration of this temperature is necessary. Therefore, when the amount of the metal binder phase in the cemented carbide constituting the wear-resistant layer is small, the sintering temperature is high, and a large temperature gradient is required. .

Although the shape of the molded outer frame 3 is an important component of the present invention, the material is not particularly limited as long as it has heat resistance and conductivity, but graphite is suitable for practical use. The same applies to the upper punch 5, the block jig 9, and the sleeve jig 10. FIGS. 6 to 9 show examples of the cross-sectional shape of the molded outer frame 3 and the processed part raw material powder 4 which can be used in the present invention, and can be appropriately selected according to a desired tool shape. In the method for manufacturing a composite tool material according to the present invention, the degree of fitting between the formed outer frame and the upper punch, steel as the lower punch is particularly important in achieving the intended temperature gradient during energization, The clearance there was 2/100 mm or less, preferably 1/100 mm or less.

[0021]

An embodiment will be described with reference to the drawings. Example 1 A round bar of SKH9 having a diameter of 20 mm and a length of 50 mm was used as a steel also serving as a lower punch, and a composite tool material having a machined portion 10 mm including an abrasion-resistant layer 1 a, an intermediate layer 1 c, and a weldable layer 1 b at one end. Was prototyped. Referring to FIG. 3, first, 15 wt% of Co powder having an average particle diameter of 1 μm was added to WC powder having an average particle diameter of 0.7 μm, and the mixed powder was used as raw material powder 1 for wear-resistant layer.
a1, and 20 wt% of Ni powder having an average particle size of 3 μm was added to WC powder having an average particle size of 1.5 μm and mixed to obtain an intermediate layer raw material powder 1c1. Furthermore, 20% by weight of Ni powder having an average particle diameter of 3 μm and 5 μm of WC powder having an average particle diameter of 10 μm were added.
Then, 10 wt% of Fe powder of m was added and mixed to prepare a weldable layer raw material powder 1b1. A graphite mold having an inner diameter of 20 mm and a height of 60 mm was used as the outer molding frame 3 for electric current sintering. The thickness of the molded outer frame is 25 mm from one end, 5 mm, 25 mm.
9 mm from 40 mm to 40 mm, 1 from 40 mm to 60 mm
5 mm. Upper punch 5 is φ20mm, length 40mm
Was used. Here, the clearance between the inner diameter of the molded outer frame and the upper punch 5 and steel 2 was 1/100 mm at the maximum.

Using these sintered parts, first, a SKH9 round bar was placed on the 15 mm thick portion of the molded outer frame from the tip thereof.
Insert and fix to 0 mm as shown in FIG. next,
From the top surface of the SKH9, 9.8 of the raw material powder of the weldable layer was obtained.
g, intermediate layer raw material powder 10.4 g, wear resistant layer raw material powder 2
2.0 g are sequentially stacked and filled, and an upper punch is set thereon. This sintered sample configuration was set in an electric current sintering machine, and a pressure of 3
After the pressure was increased to 00 kg / cm ² , energization was started. The sintering joining temperature was measured using a radiation thermometer from the outer peripheral surface of the molded outer frame at a position corresponding to the wear-resistant layer and a position corresponding to the bonding surface after sintering. Approximately 6 up to 1250 ° C measured at the position corresponding to the wear-resistant layer
Then, the temperature was maintained for 1.5 minutes at that temperature, the energization was stopped, and cooling was performed. At this time, the measured temperature at the position corresponding to the bonding surface is 10
70 ° C.

The length of the composite tool material recovered after cooling is about 6
0.5 mm. The composite tool material was cut in half by a plane parallel to the direction of the pressure axis, the cross section was polished, and the hardness and the structure were observed. The processed part consists of a wear-resistant layer, an intermediate layer, and a weldable layer of 5.2 mm, 2.6 mm, and 2.7 mm, respectively, and has a hardness of 1820, 1050, and 910 kg /, respectively.
mm ² , and all the layers were sintered well to the true density. In addition, no defects such as cracks and micropores were observed on the bonding surface, and a good bonding state was obtained. In addition, the formation of brittle intermetallic compounds was not observed in the compound analysis by micro X-ray diffraction near the bonding surface. The shear strength of the joint measured on a sample cut into a plate shape from the halved composite tool material was 55 kg / mm ²
High value was obtained, and it was found that the material had a strength more than twice that of the conventional type.

Example 2 A 30 mm square, 20 mm high square material, SKD61, was used as a steel also serving as a lower punch, and a worked portion 12 mm was sintered and joined to one end of the material to produce a prototype composite tool material. Referring to FIG.
First, WC powder having an average particle size of 0.5 μm was
8% by weight of Ni powder having an average particle diameter of 8% by weight, and the mixed powder is referred to as a wear-resistant layer raw material powder 1a1. Also, 10% by weight of a Ni powder having an average particle diameter of 3 μm and 10% by weight of an 5% by weight of Fe powder was added and mixed to obtain the upper intermediate layer raw material powder 1c11.
30 wt% of a Co powder of μm was added and mixed to prepare a lower intermediate layer raw material powder 1c12. The average particle size is 9 μm
Was added and mixed with WC powder having an average particle size of 3 μm to obtain a weldable layer raw material powder 1b1.

Referring to FIG. 4, a graphite mold having a height of 70 mm and a square hole of 30 mm inside was used as the molding outer frame 3 for electric current sintering. The molded outer frame 3 had an outer diameter of 55 mm at 30 mm from one end and an outer diameter of 85 mm at 20 mm from the other end, and was smoothly connected between them with a surface having a curvature of 20 mm. Upper punch 5
Used a 30 mm square, 50 mm long graphite round bar. Here, the clearance between the molded outer frame 3, the upper punch 5, and the steel 2 was 1/100 mm at the maximum. As the block jig 9 as shown in the figure, a graphite block having a diameter of 60 mm and a height of 30 mm was used. Using these sintered parts, first, an SKD61 square member is inserted into a portion of the forming outer frame 3 having a diameter of 85 mm as shown in FIG.
Set it so that it adheres to the top. Next, the SKD
61, 41.4 g of the above weldable layer raw material powder,
Lower middle layer raw material powder 22.5 g, upper middle layer raw material powder 2
5.2 g and 53.6 g of the wear-resistant layer raw material powder are sequentially stacked and filled, and the upper punch 5 is set thereon.

This sintered sample configuration was set in an electric sintering machine, and after applying pressure to 450 kg / cm ² , energization was started. The sintering joining temperature was measured using a radiation thermometer from the outer peripheral surface of the molded outer frame at a position corresponding to the wear-resistant layer and a position corresponding to the bonding surface after sintering. 1270 measured at the position corresponding to the wear layer
The temperature was increased to about 8 minutes in about 8 minutes, and the temperature was maintained for 1 minute to stop energization and cool. The measurement temperature at the position corresponding to the bonding surface at this time was 1090 ° C. The height of the composite tool material recovered after cooling was about 32.0 mm. This composite tool material was cut in half on a plane parallel to the direction of the pressure axis, and the cross section was polished to observe the hardness and the structure. The processed part has a wear-resistant layer, an intermediate layer, and a weldable layer of 3.9 mm, 4.1 mm, and 4.0 m, respectively.
m, the hardness of the wear-resistant layer was 1950 kg / mm ² , and all the layers could be sintered well to the true density. In addition, no defects such as cracks and micropores were observed on the bonding surface, and a good bonding state was obtained. Furthermore, the formation of brittle intermetallic compounds was not observed in the compound analysis by micro X-ray diffraction near the bonding surface. In a shear strength measurement of a joint performed on a sample cut into a plate shape from the halved composite tool material, a high value of 61 kg / mm ² was obtained.

Example 3 A round tool bar of SKH55 having a diameter of 10 mm and a length of 100 mm was used as a steel serving also as a lower punch, and a composite tool material having a processed portion of 20 mm formed of a wear-resistant layer and a weldable layer at one end was prototyped. . Referring to FIG. 5, first, W having an average particle size of 0.4 μm is formed.
12.5% by weight of a Co powder having an average particle size of 1 μm was added to the C powder, and the mixed powder was used as a wear-resistant layer raw material powder 1a1.
15 wt% of powder and 15 wt% of 5 μm Fe powder are added,
By mixing, a weldable layer raw material powder 1b1 was obtained. Referring to FIG. 5, a graphite mold having an inner diameter of 10 mm and a height of 80 mm was used for the outer molding frame 3 for electric current sintering. The thickness of the molded outer frame was 7.5 mm at 45 mm from one end and 20 mm at 15 mm from the other end, and the gap was connected by a conical surface. As the upper punch 5, a graphite round bar having a diameter of 10 mm and a length of 60 mm was used.
Here, the clearance between the inner diameter of the molded outer frame and the upper punch and steel was 1/100 mm at the maximum. As shown in the figure, a thick sleeve made of graphite having an inner diameter of 10 mm, an outer diameter of 60 mm, and a height of 85 mm was used as the sleeve jig 10. By using these sintered parts, first, the inner diameter of the sleeve jig 10 is
mm SKH55 round bar is inserted and its protruding 15m
Fig. 5
Set as follows.

Next, from the upper surface of the SKH55 round bar, 4.9 g of the weldable layer raw material powder 1b1 and 16.6 g of the wear-resistant layer raw material powder 1a1 are stacked and charged in this order, and an upper punch is set thereon. This sintered sample configuration was set in an electric current sintering machine, and after applying a pressure of 250 kg / cm ² , energization was started. The sintering joining temperature was measured using a radiation thermometer from the outer peripheral surface of the molded outer frame at a position corresponding to the wear-resistant layer and a position corresponding to the bonding surface after sintering. 1220 measured at the position corresponding to the wear-resistant layer
The temperature was raised to about 10 minutes in about 10 minutes, and the temperature was maintained for 3 minutes, the energization was stopped, and the temperature was cooled. The measurement temperature at the position corresponding to the bonding surface at this time was 1060 ° C. The length of the composite tool material recovered after cooling was about 120 mm. This composite tool material was cut in half on a plane parallel to the direction of the pressure axis, and the cross section was polished to observe the hardness and the structure. The processed portion was composed of a wear-resistant layer and a weldable layer of 15.0 mm and 5.0 mm, respectively, and had a hardness of 1780 and 950 kg / mm ² , respectively. In addition, no defects such as cracks and micropores were observed on the bonding surface, and a good bonding state was obtained. Furthermore, a minute X near the joining surface
The formation of brittle intermetallic compounds was not observed in the compound analysis by line diffraction. The shear strength of the joint performed on a sample cut into a plate shape from the halved composite tool material was 52 kg / mm ² .

[0029]

Since the present invention is configured as described above, the following effects can be obtained. According to the present invention, the fusibility with steel can be enhanced without sacrificing the original characteristics of the cemented carbide constituting the processed portion. In addition, it can reduce and disperse the residual stress due to the difference in thermal expansion with steel, and by sintering the cemented carbide raw material powder and joining it with steel at the same time, it is possible to produce highly reliable, high-grade composite tool materials at low cost. It can be manufactured stably. According to this method, a composite tool material in which steel having excellent wear resistance and toughness is combined with a cemented carbide can be widely provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a composite tool material in which steel and a cemented carbide are joined.

FIG. 2 is a longitudinal sectional view of another embodiment of a composite tool material in which steel and a cemented carbide are joined.

FIG. 3 is a longitudinal sectional view for explaining a method for manufacturing a composite tool material in which steel and cemented carbide are joined in Example 1.

FIG. 4 is a longitudinal sectional view for explaining a method of manufacturing a composite tool material in which steel and a cemented carbide are joined in Example 2.

FIG. 5 is a longitudinal sectional view for illustrating a method for manufacturing a composite tool material in which steel and a cemented carbide are joined in Example 3.

FIG. 6 is an enlarged sectional view taken along line AA.

FIG. 7 is an enlarged sectional view of another embodiment taken along line AA.

FIG. 8 is an enlarged sectional view of another embodiment taken along line AA.

FIG. 9 is an enlarged sectional view of another embodiment taken along line AA.

[Explanation of symbols]

 Reference Signs List 1 processed part 2 steel 3 molded outer frame 4 processed part raw material powder 5 upper punch 6 upper electrode 7 lower electrode 8 power supply 9 block jig 10 sleeve jig 1a wear-resistant layer 1b weldable layer 1c intermediate layer 1a1 wear-resistant layer raw material powder 1b1 welding Possible layer raw material powder 1c1 Middle layer raw material powder 1c11 Upper middle layer raw material powder 1c12 Lower middle layer raw material powder

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B32B 15/01 C22C 29/08 C22C 29/08 B22F 3/10 N (72) Inventor Hideo Ando 594 Akahira, Akahira-shi, Hokkaido 1 Sumitomo Coal Mining Co., Ltd. Hokkaido Research Institute (56) References JP-A-7-300375 (JP, A) JP-A-3-94930 (JP, A) JP 6-102803 (JP, B2) JP Hei 7-84352 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21D 28/14 B21D 37/01 B21D 37/20 B22F 3/10

Claims (3)

(57) [Claims] 1. Sinter-bonded directly or via an intermediate layer
Metal binder phase content of 20% by weight or more and 60% by weight or less
Weldable layer (1b) made of WC-based cemented carbide
W containing at least 3% by weight and less than 20% by weight
Working with wear-resistant layer (1a) made of C-base cemented carbide
With the part (1), the composite tool material integrally joined to the steel
Method for manufacturing by electric current sintering method using molded outer frame (3)
In the above, the thickness of the molding outer frame in the pressing axis direction is
Raw material powder (1b1) weldable from the powder (1a1) side
Side to increase continuously or stepwise.
By making the outer frame at least one energizing path,
A temperature gradient is formed in the direction of the pressing axis of the raw material powder during energization
While sintering the raw material powder, sinter bonding to steel
A method for producing a composite tool material in which steel and a cemented carbide are joined. 2. The composite tool material according to claim 1, wherein the average particle size of the WC particles in the WC-based cemented carbide constituting the wear-resistant layer is 1 μm or less . Manufacturing method . 3. The WC-based cemented carbide forming the working portion has one or more of Co, Ni, and Fe metal binder phases;
2. The method for producing a composite tool material according to claim 1, wherein the composite tool material is made of an alloy containing these metals.