JPS5967333A - Manufacture of sintered hard alloy - Google Patents

Abstract

PURPOSE:To obtain a sintered hard alloy having higher hardness at the outside and higher strength at the inside by making the amount of a binder such as Co in powder for the inside of a sintered hard alloy larger than that in powder for the outside when the sintered hard alloy is manufactured by a powder metallurgical method. CONSTITUTION:Hard powder 8 having a higher binder content is fed onto an under inner punch 4 and pressed under about 1 ton/cm<2> pressure with an upper punch 2. An under outer punch 5 is lowered to the position of the punch 4, and hard powder 9 having a lower binder content is fed and pressed under about 1 ton/cm<2> pressure with the punch 2. A sintered hard alloy having higher hardness at the outside and higher strength at the inside can be manufactured. In the figure, 1 is a die, 3 is a core, and 6 and 7 are feeders.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sintered cemented carbide by powder metallurgy.

Conventionally, the strength and hardness of sintered cemented carbide are changed mainly by changing the amount of a binder such as OO. However, in conventional manufacturing methods, as shown in Table 1, increasing the binder increases the strength but decreases the hardness, and decreasing the binder increases the hardness but decreases the strength. It has not been possible to produce a sintered cemented carbide that has both of these properties.

The present invention is intended to solve the above-mentioned drawbacks, and involves feeding two types of cemented carbide powders with different amounts of binder from separate feeders during press molding, so that cemented carbide powder with a large amount of binder is contained inside the press molded body. The present invention provides a method for producing a sintered cemented carbide having high external hardness and strong internal strength by molding powder into a cemented carbide powder with a small amount of binder.

An embodiment of the present invention will be described below based on the drawings. FIG. 1 shows a sectional view of the entire press apparatus for molding cemented carbide powder. 1 is the die, 2 is the upper punch, 3 is the core, 4 is the lower inner punch, 5 is the lower outer punch, 6 and 7 are the feeders, 8 is the carbide powder with a lot of binder, and 9 is the carbide powder with a little binder. are shown respectively. First, as shown in FIG. 2, cemented carbide powder containing a large amount of binder is supplied to the lower inner punch. Next, as shown in Figure 6, it is approximately i ton /
Press with CD pressure. Next, as shown in FIG. 4, the lower outer punch is aligned with the lower inner punch and cemented carbide powder containing less binder is supplied. Finally, as shown in Figure 5, it is approximately 1 ton/cn! Press with pressure.

By manufacturing in this manner, it is possible to manufacture a sintered cemented carbide having high external hardness and strong internal strength.

[Brief explanation of drawings]

1 to 5 are cross-sectional views that do not show the over-manufactured culms of the present invention. 1...Die 2...Top bunch 3...Core 4...Bottom inner punch 6.71 ... Feeder 8 ... Carbide powder with a lot of binder 9 ...
...Cemented carbide powder with less binder or higher Applicant Daini Seikosha Co., Ltd.

Claims (1)

[Claims] A method of manufacturing sintered cemented carbide using powder metallurgy, characterized by increasing the amount of binder such as 00 in the interior of the sintered cemented carbide compared to the outside to increase the hardness of the exterior and strengthen the strength of the interior. A method for manufacturing sintered cemented carbide.