JPS6256503A - Composite sintered body of powder metallurgy and its production - Google Patents

Abstract

PURPOSE:To eliminate the need for a brazing work and to obtain a composite sintered body of powder metallurgy having extremely stable quality by embedding a high melting metallic body having the m.p. higher than the sintering temp. into a sintered body of sintered hard alloy powder while exposing part thereof to the outside, then sintering the powder. CONSTITUTION:The powder of a sintered hard alloy such as WC or TiC and a binder are uniformly mixed at a prescribed compsn. and thereafter the mixture is packed into a metallic mold 4 recessed with a prescribed shape and is compressed under 5-45kg/mm<2> pressure to form a compression molding. An insertion hole for the high melting metal such as Mo or W is recessed to the compression molding simultaneously with or after compression molding. A metallic body 2 is inserted into the insertion hole to form the compression molding having 1-plural exposing points. Such compression molding is put into a sintering furnace and is subjected to preliminary sintering in a reducing or inert gaseous atmosphere or vacuum then to calcination at a high temp. of about 1,400 deg.C. The compression molding shrinks to the higher density during the calcination and compacts the metallic body 2. Both materials melt each other at the boundary thereof to form an intermediate layer 3. The thoroughly united composite sintered body 1 of powder metallurgy is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a powder metallurgy composite sintered body and a method for manufacturing the same. At least one surface of a high melting point metal body (2) for processing having a higher melting point is exposed to the outside, and the sintered body (1) is welded to the high melting point metal body (2). Regarding the characteristic powder metallurgy composite sintered body, the second invention is a high melting α metal body (2
) is buried with at least one side exposed to the outside, and
The present invention relates to a method for producing a powder composite sintered body, characterized in that a compression molded body is sintered together with a high melting point metal body (2).

Sintered bodies of cemented carbide powder alloys are generally widely used as bunching guids for brazing molds and as cutting tools for cutting tools. By the way, conventionally, the sintered body was attached to the press mold by fitting an iron piece into a mounting hole formed in the sintered body and soldering the piece. However, when brazing, the fit between the mounting hole and the piece is very strict, and if the gap is too wide, the strength of the brazing part will be low, and the brazing may break during use, or the brazing may break during use. If the gap is too narrow or the heating temperature is insufficient, the wax will not flow well into the gap, causing damage. The quality of the attached parts was not stable, which caused practical problems. Furthermore, the brazing technique requires skill, and the lack of skilled technicians has exacerbated the above-mentioned problems. Furthermore, brazing requires a considerable amount of processing time,
This was also a factor that hindered the rationalization of the 9I manufacturing process.

The present invention was made in view of the drawbacks of the conventional example, and
The purpose is to provide a powder metallurgy composite sintered body and a method for manufacturing the same, which can omit brazing work and greatly improve quality stability.

Hereinafter, the present invention will be described in detail according to illustrated embodiments.

Examples of cemented carbide powder materials include tungsten carbide, titanium carbide, zirconium carbide, and tantalum carbide, and binders include cobalt and nickel.

High melting point metal materials include molybdenum and tungsten, and molybdenum is mainly used from the viewpoint of workability.
11 has been done. First, cemented carbide powder and a binder are uniformly mixed in a predetermined composition. As the amount of binder increases, the hardness of the sintered body (1) decreases, but the toughness improves. First, this mixture is filled into a mold having a predetermined shape and compressed by applying a pressure of 8/mm2 to 2-1 to 45 to give a compression molded product. At this time, the insertion hole of the i0i molten metal body (2) is compressed 8. It is recessed at the same time as the mold or after compression molding, and the high melting point metal body (2) is inserted into this insertion hole and then fired. The high-melting point metal body (2) and the insertion hole may be loosely fitted together because the compression-molded body contracts during sintering. For compression molded objects with large shapes, perform compression in several batches. At least one surface of the inserted high melting point metal body (2) has a pressure of Jl? ! Exposed to the outside from the molded body. Of course,
The number of high melting point metal bodies (2) to be buried does not have to be one, it may be multiple according to the design, or one high melting point metal body (2) can be buried.
Multiple exposed areas for Hirokai member (2)! Of course, it is also good as the L location. In this way, first, from one place to multiple v! A compression molded body with an exposed portion of the LtIJ site is created.

Next, this compression molded body is placed in a sintering furnace and preheated in a reducing or inert gas atmosphere or in a vacuum, and then 1.
Fire at high temperatures around 400°C. During firing, the compression molded body contracts and becomes denser, melts at high pressure, and becomes an X'1 metal body (2
), and the two melt together at the boundary to form the intermediate layer (3), and are completely integrated. The sintered body (1) taken out from the sintering furnace is a high melting point metal body (2)
For example, the exposed portion is threaded and used by being screwed to a press mold (4) with bolts (5).

In the above case, the insertion hole is first formed, and then the high melting point metal body 2) is inserted and sintered. However, this is not limited to this, of course. High melting point metal body (
2) is placed in advance, and then the cemented carbide powder is filled and compressed into the mold. In addition, if the insertion hole is a blind hole, when the high melting point metal body (2) and the compression molded body are fired, the edge of the insertion hole and the high melting point metal body (2) will first meet as shown in Figure 6. is welded and gas remains at the bottom of the insertion hole 1H6)
occurs, and during sintering, the sintered body (6) expands and expands the sintered body (1).
Gas vent holes (7) in the high melting point metal body (2) as shown in the figure.
It is desirable to provide a hole. However, if the sintered body (1) is a polar, open-cell type, the gas vent hole (7) is not necessary.

As mentioned above, the present invention embeds a high melting point metal body with a melting point higher than the sintering temperature, so the high melting point metal body does not melt even at the sintering temperature, and the cemented carbide powder There is no possibility of the cemented carbide powder penetrating into the sintered body and causing deterioration of the sintered body.In other words, if a low melting point metal such as iron is used, the sintering During consolidation, the iron melts and soaks into the sintered body where the porous part remains, causing the processed part to disappear and at the same time, the part where the iron penetrates deteriorates. In addition, since at least one side of the high-melting metal body is buried and exposed to the outside, this exposed part can be used for processing such as tapping, and conventional brazing is not required. It is possible to completely eliminate the work. Further, the cemented carbide powder is compression molded into a predetermined shape, and at least one surface of a high melting primary metal body to be processed having a melting point higher than the sintering temperature is exposed to the outside and buried, and then the high melting point metal body is buried. Since the compression molded body is sintered together with the metal body, the sintered body shrinks during sintering and is strongly compressed by the sintered body of the high melting point metal body or cemented carbide powder, causing the gap between the two to close. 'l)'I disappears, and then an intermediate J is formed at the boundary between the high melting point metal body and the sintered body of cemented carbide powder, and the two are completely integrated. There is.

[Brief explanation of the drawing]

i@Figure 1... A vertical sectional view of an embodiment of the present invention, Fig. 2... A longitudinal sectional view showing the installed state of the present invention, Fig. 3...
U11!7i side view of an embodiment where the insertion hole of the sintered body of the present invention is a blind hole, Figure 4... Plan view of Figure 3 Figure 5... Sintering of the present invention A plan view of another embodiment in which the insertion hole of the body is a blind hole, and FIG. 6 is a longitudinal cross-sectional view when the insertion hole of the sintered body is a blind hole and the sintered body expands. (1)...Sintered body (2)...High melting point *metallic body (3)...Intermediate layer (4)...Press mold (5)
...The bolt (6)...is the stagnation (7)...the gas vent hole. Figure 1 Figure 2 Figure 3 Figure 4

Claims (6)

[Claims] (1) A high melting point metal body for processing having a melting point higher than the sintering temperature is buried in a sintered body of cemented carbide powder with at least one side exposed to the outside, and the sintered body is welded to the high melting point metal body. A powder metallurgy composite sintered body characterized by: (2) A powder metallurgy composite according to claim 1, characterized in that an intermediate layer is formed at the boundary between a sintered body of cemented carbide powder and a high melting point metal body by sintering. Sintered body. (3) Compression molding of cemented carbide powder into a predetermined shape and burying a high melting point metal body to be processed having a melting point higher than the sintering temperature with at least one surface exposed to the outside; A method for manufacturing a powder metallurgy composite sintered body, characterized in that a compression molded body is sintered together with a body. (4) A powder metallurgy composite according to claim 3, characterized in that an intermediate layer is formed at the boundary between a sintered body of cemented carbide powder and a high melting point metal body by sintering. A method for producing a sintered body. (5) Fill and compress cemented carbide powder in a compression molding mold to form a compression molded body of metal powder, and at the same time form an insertion hole for a high melting point metal body in the compression molded body, and then A method for producing a powder metallurgy composite sintered body according to claim 3, characterized in that a high melting point metal body is inserted into the powder metallurgy composite sintered body. (6) The method according to claim 3, characterized in that a high-melting point metal body is placed in a compression mold, and then cemented carbide powder is filled and compressed into the mold. A method for producing a powder metallurgy composite sintered body.