JPS62234634A - Cemented type hot-press working die - Google Patents

Abstract

PURPOSE:To remarkably prolong a service life of a hot-press working die by solid phase diffusion bonding a working part and a supporting part composed of a specific composition of a sintered hard alloy mutually and providing a high wear resistance to the working part and high toughness to the supporting part. CONSTITUTION:The supporting parts 2, 3 are provided outside the working part 1, furthermore, a reinforcing ring 4 of a tool steel is disposed outside thereof. As to the materials of the working part 1 and the supporting parts 2, 3, a sintered hard alloy composed of one or more of carbide and nitride of group IVa, Va and VIa of the periodic law and one or more of Co and Ni are used. Moreover, the high wear resistance and high toughness are provided to the working part 1 and the supporting parts 2, 3, respectively. The connection of both parts is performed mutually by solid phase diffusion bonding. In this way, the characteristics of each part are held as it is, and the service life of the hot-press working die is remarkably prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a compression die used for hot forging, hot forging, hot drawing, etc.

(Prior Art) Conventional dies for processing pressure parts have been used by press-fitting or baking a single-composition cemented carbide into a reinforcing ring made of tool steel or the like. It has also been used as a coach ink chip further coated with a surface hardening layer.

However, in conventional compression dies, the material used was a single-composition cemented carbide alloy, making it difficult to simultaneously satisfy two contradictory constraints on material strength: wear resistance and toughness. Ta.

This delay is particularly noticeable in hot gate dies. For example, in conventional hot dies, a superhard alloy with a relatively large amount of bonded metal is used to prevent heat cracks, but the life of the mold is shortened due to thermal shock, and the lifespan of the die is several thousand pounds. Heat cracks, seizing, galling, cracking, etc. often occur during processing. Thermal shock is a case where repeated heating/cooling cycles occur, and expansion due to heating/cooling,
Due to repeated shrinkage, cracks occur on the two processed surfaces (
This is the heat track). When heat cracks or the like occur, the mold has been regenerated by re-polishing.

Incidentally, increasing the amount of bonded metal to suppress heat cracks leads to a decrease in the wear resistance of the superhard alloy. In addition, if the hardened surface layer is coated with a hardened layer, peeling or chipping may occur in the hardened surface layer due to the low hardness of the cemented carbide base material.On the other hand, to prevent the hardened surface layer from peeling off, Furthermore, when a hardened layer is coated on a cemented carbide base material with a small amount of bonded metal, cracks occur at locations where repeated stress is concentrated due to the high elastic modulus of the cemented carbide, leading to fatigue failure.

(Problem to be solved by the invention) Therefore, a superhard alloy with excellent wear resistance (machined part)
A super-hard alloy with excellent toughness that can be processed easily.
It is conceivable to have the processed part supported by the support part).

BACKGROUND ART Conventionally, liquid phase diffusion bonding type superhard alloys have been produced by combining two or more types of superhard alloys (sintered products of green compacts of raw material powders) and heating them above their melting point. However, with this method, because there is an intermediate phase generated by heating above the melting point, it is difficult to obtain material properties as designed that have different properties, and it also causes variations in property values. , -4-

The present applicant, in Patent II No. fhΩ-48535,
A bonding type tool is disclosed in which a processing part and a support part are bonded using an in-phase diffusion bonding type. Since the in-phase diffusion bonding type is used, the bonding is performed below the melting point of the bonded members, so there is no intermediate phase and the material properties as designed can be obtained.゛This solid diffusion bonding type tool has a significantly improved lifespan as a die for cold working, but as a die for hot compression processing, it is possible to further improve the lifespan by reducing the frequency of occurrence of heat cracks, etc. desirable.

An object of the present invention is to provide a bonded tie for hot compression processing that is superior in both wear resistance and toughness properties.

(Means for Solving the Problems) The first joining type hot compression die according to the present invention has a processing section for performing hot compression processing on a workpiece material, and a processing section outside the processing section. The processed part and each layer of the supporting part are bonded to each other by solid-phase diffusion bonding, and the processed part and the supporting part are of the same type. The above-mentioned similar materials include one or more carbides, nitrides, and carbonitrides of elements of groups IVa, Va, and VIa of the periodic table, and one or more bonding metals, mainly cobalt and nickel. It is a super hard alloy consisting of the above, the processed part is made of a material with higher wear resistance among the same types of materials, and the support part is made of a material with higher toughness.

The second bonded hot compression die according to the present invention further includes a surface of the hot compression die made of various carbides, nitrides, carbonitrides, borides, or silicides of transition metals, and Alternatively, it is characterized by being coated with a hardened layer that is a single layer, multiple layers, or multiple layers of oxides such as aluminum, yttrium, and zinc.

(Function) The ultra-hard alloy mold, which was conventionally thought of as an integrated type, has been designed to be divided into a processing section that processes the workpiece material and a multi-layered support section that supports the processing section. The material is designed with an emphasis on wear resistance, and the support part is designed with an emphasis on toughness and thermal shock mitigation. Furthermore, by using a bonding type structure in which the processed part and the support part are in-phase diffusion bonded, the characteristics of each part are maintained as they are, and the above-mentioned contradiction in material strength can be resolved. Furthermore, by forming the support portion in multiple layers, thermal shock can be alleviated. Furthermore, regarding the coating depth covered with a hardened layer, if the material of the processed part, which is the base material, is designed with an emphasis on high hardness, it can be an effective means for preventing peeling and chipping of the hardened coating layer.

A bonded die using solid-phase diffusion bonding has significant effects on the following items.

(1) Since high-hardness cemented carbide is used as the material for the machined part, the wear resistance of the machined part is high.

(2) Since a high-elastic modulus super-hard alloy is used for the material of the machined part, the amount of elastic deformation under the same processing stress conditions is small. With this saw, there is little dimensional change in the machined part.

(3) Since the support part is made multi-layered and a material with excellent toughness can be sequentially adopted as the outer cemented carbide material, it has excellent thermal shock mitigation properties.

(4) In accordance with the multi-layer structure of the die, materials with large coefficients of thermal expansion can be sequentially adopted for the outer super-hard alloy material, so that the joining type die itself has an interference fit effect due to the multi-ring structure. Therefore, the compressive prestress effect is large.

(5) Since the processed part cemented carbide has high hardness and high elastic modulus, the amount of deformation of the cemented carbide base material under processing stress is small, and therefore the hardened surface layer is less likely to peel or chip. That is,
The life of the hardened surface layer is long.

(6) The synergistic effect of the above (1) to (5) improves heat crack resistance.

(Example) A joining type die for hot forging according to an example of the present invention includes a processing section l for processing a workpiece material, and a processing section l for supporting this processing section.
The supporting parts 2 and 3 of the layer are joined to each other by solid-phase diffusion bonding, the above-mentioned processed part and the above-mentioned supporting part are respectively formed of the same kind of material (superhard alloy), and the processed part is It is made of a material with higher wear resistance among ultra-hard alloys, and the support part is made of tungsten, which has higher toughness. This super-hard alloy is made of one or more carbides, nitrides, and carbonitrides of elements of the IVa, Va, and Vla groups of the periodic table, and one or more of cobalt and nickel as a combined metal content. It is an alloy.

FIG. 1 shows a sectional view of a hot forging tie. A supporting part (equivalent to wear-resistant and impact-resistant super-hard alloy ■3) is placed on the outside of the processing part (equivalent to wear-resistant super-hard alloy V2) that has a through-hole for processing.
2) A reinforcing ring (tool steel) 4 is arranged on the outside of the support part 3 (corresponding to impact-resistant superhard alloy V5).

For the tie to be manufactured, the material of joint +, I'l, 2.3 (for example, WC grain size, type or amount of bonding metal), joint position,
Design the joint surface shape. The larger the WC particle size, the better the impact resistance, and the smaller the WC particle size, the better the wear resistance. In terms of high-temperature strength, it is a little more complicated, and those with coarse grains have better strength.

Furthermore, as the amount of bonded metal increases, the impact resistance improves, and as the amount decreases, the wear resistance improves. In terms of high temperature strength,
The smaller the amount of bonded metal, the higher the high temperature strength, but the weaker it is against repeated thermal shock. As the material for the processed portion 1, a superhard alloy with higher wear resistance is selected, and as the material for the support portion 3, a superhard alloy with better toughness is selected. As the material of the support part 2, a material with properties intermediate between those of the processed part I and the support part 3 is used. The outer layers of the die have a higher amount of bonded metal and therefore a higher coefficient of thermal expansion. By reducing the wall thickness of processed parts with a small amount of bonded metal to the minimum necessary, heat conduction to the supporting parts with a larger amount of bonded metal is facilitated, and therefore, the heat storage area in the processed part is reduced. This has the effect of keeping the difference in partial expansion and contraction low.

In this example, the WC grain size of the material of the processed part 1 is 1 to 3 microns, and the amount of bonded metal is 4 to 9%. The WC particle size of the support part 2 is 2 to 4 microns, and the amount of bonded metal is 9 to 13%.

Further, the WC particle size of the support portion 3 is 4 to 7 μ, and the amount of bonded metal is 14 to 18%.

Next, as for the method of joining the processed part 1 and the support part 2.3, in-phase diffusion joining is performed using an encapsulation method. Figure 2 schematically shows the encapsulation method.

In this method, the bonding members 1, 2.3 are vacuum-sealed together with pressure medium particles 5 in an annealed copper capsule 6, and I-i IP diffusion bonding (
(1000-1350°C, 500-1000 atm). Normally, the temperature of solid-state diffusion bonding is sufficiently higher than the die temperature (for example, 1000° C.) during hot compression processing, so that an interference fit effect occurs due to the difference in the coefficient of thermal expansion of each part. Examples 11 and 2 below illustrate die processing conditions. Finally, the final shaped product is molded.

(Example 1); After casing the bonded die at about 500 to 600°C, a training process-1- is performed.

(Example 2) - CV I) processing (800 to 12
00°C) to form a surface hardening layer. Next, after the casing, a polishing process is performed.

In Example 2, the bonded die surface of Example 1 was subjected to CVD treatment (
800-1200°C), a hardened layer is deposited. This hardened layer is coated with a single layer, multiple layers, or multiple layers of various carbides, nitrides, carbonitrides, borides, or silicides of transition metals, and/or oxides such as aluminum, yttrium, and zirconium. do.

The table shows the production quantity per die when a material to be forged (Inconel) is forged using the die produced as described above. For comparison, a conventional one-piece die (corresponding to cemented carbide ■5) is also described.

As is clear from the table, the life of the bonded die according to the present invention was significantly longer than that of the conventional integrated die. This effect is even greater when a coating hardening layer is provided (Example 2).

(Effects of the Invention) The present invention has a die life of 100% compared to conventional dies.
].

The most effective bonded die can be obtained by changing the bonding location and bonding method depending on the application and usage conditions.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a bonded die according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the encapsulation method. ■... Processing part, 2.3... Support part, 4... Reinforcement ring.

Claims (5)

[Claims] (1) Consisting of a processing section that performs hot compression processing of the workpiece material, and a plurality of layers of support sections that sequentially support the processing section in a ring structure outside of this processing section, the processing section and the support section are The respective layers of the section are bonded to each other by solid-phase diffusion bonding, and the processed section and the supporting section are respectively formed of the same kind of material, and the same kind of material is used to form groups IVa, Va, and V of the periodic table.
one or more carbides, nitrides, and carbonitrides of Group Ia elements;
The joining metal is a super hard alloy made of one or more of cobalt and nickel, and the processed part is made of a material with higher wear resistance among the same types of materials, and the supporting part is made of a material with higher toughness. Die for mold hot compression processing. (2) In the joining type hot compression die described in claim 1, the processing section is made of a superhard alloy containing nickel as a bonding metal, and the supporting section is made of a superhard alloy containing nickel as a bonding metal. A joining type hot compression die made of nickel or cobalt, or a cemented carbide containing nickel and cobalt. (3) In the joining type hot compression die described in claim 1, a cemented carbide with a smaller amount of bonded metal is used as the material of the processing part, and the material of the support part is A joining die for hot compression processing, characterized in that the material used is a superhard alloy having a bonding metal content equal to or greater than that of the processing part material. (4) In the joining type hot compression processing die described in claim 1, the material of the processing portion is as follows:
A superhard alloy having a WC grain size suitable for the purpose is used, and the supporting part is made of a superhard alloy having a WC grain size that is equal to or larger than the material of the processed part. A die for joining type hot compression processing. (5) Consists of a processing section that performs hot compression processing of the workpiece material, and a high-toughness material that supports this processing section in a ring structure on the outside of this processing section, and each layer of the processing section and support section described above. are joined to each other by solid-phase diffusion bonding, the processed part and the support part are each made of the same kind of material, and the said same kind of material is a carbide of an element of group IVa, group Va, or group VIa of the periodic table. , one or more of nitrides and carbonitrides, and a bonding metal,
It is a super-hard alloy mainly composed of one or more of cobalt and nickel, and the processed part is made of a material with higher wear resistance than other materials of the same type, and the support part is made of a material with higher toughness. A hardened layer whose surface is a single layer, multiple layers, or multiple layers of various carbides, nitrides, carbonitrides, borides, or silicides of transition metals, and/or oxides of aluminum, yttrium, zinc, etc. A die for joining type hot compression processing characterized by being coated with.