JPH06287609A - Production of stepped cemented carbide material - Google Patents

Abstract

PURPOSE:To provide the process for production of the stepped cemented carbide material which improves quality and reliability together with productivity and reduces a cost by a clearance formed between both high-density compression molded articles of a large diameter and a small diameter and shrinkage on sintering varying from each other. CONSTITUTION:The high-density compression molded article 3 of the small diameter formed by press forming of sintered hard alloy powder is inserted into a central hole 2 of the high-density compression molded article 1 of the large diameter formed by press forming of the cemented carbide powder and after both high-density compression molded articles 1 and 3 are set in a stepped state by forming the clearance alpha therebetween, these two high-density compression molded articles 1, 3 are sintered and the clearance alpha is eliminated by the shrinkage on sintering varying from each other to form a sintered compact 10 which is integrally joined and stepped. The powder P for sintered hard alloy, such as Co powder or Ni powder, is otherwise injected into the clearance alphaformed between both high-density compression molded articles 1 and 3 and thereafter the high-density compression molded articles 1, 3 are sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a stepped cemented carbide material which is suitable as a material for metal mold parts and guide bushes made of cemented carbide.

[0002]

2. Description of the Related Art Conventionally, cemented carbide materials having excellent strength and hardness have been used for parts requiring wear resistance. For example, in various mold parts and guide bushes, cemented carbide material is used for the worn parts and steel material for the other parts, and the stepped shape is obtained by brazing steel to the cemented carbide and joining it. There is a case. However, in the case of the stepped shape as described above, the strength of the brazed portion is weak, so recently, there is a growing demand for integrally forming the whole body with a cemented carbide,
For those with a relatively small step, a high-density compression-molded body obtained by press-molding cemented carbide powder is sintered, and after sintering, it is ground to form a stepped sintered body. The stepped cemented carbide is formed by scraping the high-density compression molded body before sintering into a stepped high-density compression molded body, and sintering the stepped high-density compression molded body to form a stepped sintered body. The manufacturing method of wood is being developed.

[0003]

The conventional step cemented carbide material is ground into a stepped sintered body by grinding after the sintering of the high-density compression molded article as described above, or before sintering. After cutting and forming into a stepped high-density compression molded body, it is sintered and formed into a stepped sintered body, and the high hardness sintered body and stepped cutting processing of the high-density compression molded body before sintering Takes a lot of time and effort,
There are problems such as a decrease in productivity and an increase in cost, such as a large amount of shavings and uneconomical.

The present invention was developed in order to solve the above-mentioned problems, and the object of the present invention is to provide a clearance formed between high-density compression moldings of both large diameter and small diameter. The purpose of the present invention is to provide a method for manufacturing a stepped cemented carbide material, which improves the quality and reliability as well as the productivity by reducing the different sintering shrinkages and enables cost reduction.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a high-density compression molding of small diameter in which a cemented carbide powder is press-molded in the inner hole of a large-diameter high-density compression molding of press-molded cemented carbide powder. After inserting and inserting a clearance between the two high-density compression molded bodies to set them in a stepped state, the high-density compression molded bodies are sintered and the clearance is eliminated by different sintering shrinkage, and the steps are joined together. By forming a sintered body with a large diameter, high-density compression moldings of both large diameter and small diameter can be homogenously and integrally connected to improve the joining accuracy and reliability, and the step cutting process is almost unnecessary. And increase productivity.

Further, in the above method for producing a stepped cemented carbide material, after the powder for cemented carbide such as Co powder or Ni powder is injected into the clearance formed between both high density compression molded bodies, By sintering the density compression molded product, the joining accuracy and reliability of both high density compression molded products are further enhanced.

[0007]

[Function] Both of the high-density compression molded articles are obtained by inserting the small-diameter high-density compression molded article obtained by press-molding the cemented carbide alloy powder into the middle hole of the large-diameter high-density compression molded article obtained by press-molding the cemented carbide powder. After forming a clearance between and setting it in a stepped state,
Both high-density compression compacts are sintered to form a stepped sintered compact that eliminates clearance due to different sintering shrinkage and is joined together. By installing it, the joining accuracy and reliability are effectively improved, and the step cutting work is almost unnecessary.

In addition, by injecting a powder for cemented carbide such as Co powder or Ni powder into the clearance formed between the two high-density compression molded bodies, and then sintering both high-density compression molded bodies, The strength, precision, and reliability of the high-density compression-molded body are integrally joined.

[0009]

1A and 1B show an embodiment of the present invention. In the figure, 1 is a relatively large-diameter high-density compression-molded body obtained by press-molding a cemented carbide powder, 2 is a middle hole formed in the high-density compression-molded body 1, 3 is a relatively-high-density compression-molded body obtained by press-molding a cemented carbide powder. A high-density compression molded product with a small diameter, 5 a carbon plate for sintering, α
Is a clearance formed between the high-density compression molded bodies 1 and 3, P is a powder for cemented carbide such as Co powder or Ni powder injected into the inner hole 2, and 10 is a stepped sintered body,
The large-diameter high-density compression molded body 1 is composed of WC powder, Co powder, N
i powder, etc. or TiC powder, VC powder, Cr ₃ C
₂ powder, ZrC powder, NbC powder, Mo ₂ C powder, Hf
C powder, TaC powder, etc. are mixed in a desired ratio to form powders for powder metallurgy, that is, cemented carbide powder is uniformly press-molded by a die press or the like. After press forming, the inner hole 2 is formed.
Further, the small-diameter high-density compression molded body 3 is obtained by uniformly mixing powders for powder metallurgy having various compositions by mixing the above-mentioned powders in a desired ratio, that is, cemented carbide powder by a die press or the like. The high-density compression molded body 3 is formed by press molding, and the cross-sectional outer shape of the high-density compression molded body 3 is formed into a circle, an ellipse, a polygon, or the like. A desired clearance α is secured as a shape corresponding to the cross-sectional shape of the molded body 3. As the cemented carbide powder P injected into the inner hole 2, Co powder, Ni powder, or a mixed powder of Co powder and Ni powder is preferably applied.

The embodiment shown in FIG. 1 is a large-diameter high-density compression-molded body 1 obtained by compression-molding cemented carbide powder as shown in FIG. 1 (A).
A small-diameter high-density compression-molded body 3 obtained by compression-molding cemented carbide powder is fitted into the inner hole 2 of the hollow body, and an appropriate clearance α is formed between the high-density compression-molded bodies 1 and 3 to form a stepped state. After the above-mentioned steps, the two high-density compression-molded bodies 1 and 3 are sintered to form a stepped sintered body 10 (see FIG. 1B) integrally bonded by eliminating the clearance α due to different sintering shrinkages. In the method of manufacturing a stepped cemented carbide material, and in the method of manufacturing a stepped cemented carbide material by the powder metallurgy method, the clearance α formed between the both high-density compression molded bodies 1 and 3 is made of a cemented carbide such as Co powder or Ni powder. After the alloy powder P is injected, both the high-density compression-molded bodies 1 and 3 are sintered, which is a method for producing a stepped cemented carbide material by a powder metallurgy method.

Further, in the method for manufacturing the stepped cemented carbide material, the high-density compression molded bodies 1 and 3 are formed to have different compositions, if necessary. For example, a thick high-density compression molded body 1
Is a composition having a relatively high toughness such as WC-20% Co, and the thin high-density compression-molded body 3 has a composition having a relatively high hardness such as WC-7% Co and exhibits wear resistance. Increase the versatility of the product as a powder composition of cemented carbide corresponding to the product.

Further, as shown in FIG. 1 (A), the inner hole 2 formed in the large-diameter high-density compression molded body 1 is formed to have a large diameter reasonably large with respect to the small-diameter high-density compression molded body 3. Form the desired clearance α. This clearance α is preferably in the range of 0.5 to 5% of the diameter of the thin high-density compression molded body 3, while the shrinkage rate of the large-diameter high-density compression molded body 1 due to sintering is small. The density is appropriately larger than that of the high-density compression molded body 3. For example, the two high-density compression molded bodies 1 and 3 are molded by changing the pressing pressure (reducing the pressing pressure increases the shrinkage ratio). It is essential to increase the shrinkage rate of the high-density compression molded body 1 by 1 to 5.5%. As shown in FIG. 1 (A), both of the high-density compression molded bodies 1 and 3 have a carbon plate 5 for sintering. Set it in a stepped state on top and set it in the sintering furnace (1300-300).
When subjected to a sintering treatment at 1500 ° C. for 0.5 to 2 hours, it is sintered into a stepped sintered body 10 as shown in FIG. 1B, and at the time of this sintering, a small diameter high density compression molded body 3 On the other hand, the large-diameter high-density compression-molded body 1 has a moderately different large sintering shrinkage, so that the clearance α is effectively eliminated, and the high-density compression-molded bodies 1 and 3 are uniformly and integrally joined. That is, due to the balance between the clearance and the difference in sintering shrinkage, there is no excess or deficiency in the powder density of the joint portion and the particles are appropriately averaged, and the large diameter portion and the small diameter portion generated during the sintering of the stepped high density compression molded body are obtained. The density difference between the two is eliminated, and the large diameter portion 10a and the small diameter portion 10b
And the joint portion thereof is uniformly and integrally joined to the whole, so that excellent accuracy and quality can be obtained.

When the powder P for cemented carbide such as Co powder or Ni powder is injected into the clearance α formed between the two high-density compression molded bodies 1, 3, the clearance α is further +0. It is possible to increase up to 5%, and the cemented carbide powder P has a similar composition between the two high-density compression molded bodies 1 and 3 by sintering, and is joined more accurately to further improve reliability.

[0014]

Industrial Applicability The present invention has a small diameter high-density compression-molded product obtained by press-molding a cemented-metal alloy powder in the inner hole of a large-diameter high-density compression-molded product obtained by press-molding a cemented-metal alloy powder as described above. After inserting and inserting a clearance between the two high-density compression molded bodies to set them in a stepped state, the high-density compression molded bodies are sintered and the clearance is eliminated by different sintering shrinkage, and the steps are joined together. It can be easily and homogeneously formed on the attached sintered body with high accuracy, and the step cutting process is almost unnecessary, and the strength, precision, quality and reliability of both high density compression molded bodies are significantly improved along with the productivity. There is.

Further, by injecting the cemented carbide powder into the clearance formed between the two high-density compression molded bodies, and then sintering the two high-density compression molded bodies, the joining accuracy of both high-density compression molded bodies is improved. However, the reliability is further increased, and therefore, significant cost savings are also possible.

[Brief description of drawings]

FIG. 1 is a side view (partial cross section) (A) before sintering showing an embodiment of the present invention and a side view (B) of a stepped sintered body.

[Explanation of symbols]

 1 High Density Compression Molded Body (Large Diameter) 2 Medium Hole 3 High Density Compression Molded Body (Small Diameter) 10 Stepped Sintered Body α Clearance P Cemented Carbide Powder (Co Powder, Ni Powder, etc.)

Claims (2)

[Claims] 1. A small-diameter high-density compression molded product obtained by press-molding a cemented carbide powder is inserted into a middle hole of a large-diameter high-density compression molded product obtained by press-molding a cemented carbide powder, and both high-density compressions are performed. After forming a clearance between the compacts and setting them in a stepped state, sinter both high-density compression compacts to eliminate the clearances due to different sintering shrinkage and form a stepped sintered compact that is integrally joined. A method of manufacturing a stepped cemented carbide material characterized by. 2. The stepped cemented carbide material manufacturing method according to claim 1, wherein a powder for cemented carbide such as Co powder or Ni powder is injected into the clearance formed between the two high-density compression molded bodies. And then sintering both high-density compression-molded bodies, a method for producing a stepped cemented carbide material.