| 摘要 |
PURPOSE:To improve the durability of pressurizing jig by plastic-working sintered alloy having the specific W content or more at the specific forging ratio or more and making the specific tensile strength and surface hardness or more at the constant temp. in a molten metal contacting part for the pressu rizing jig. CONSTITUTION:Molten metal 53 poured under pressurizing into a cavity 56 composing of dies 51, 52 or die-casting machine 50 through gate 59 by descend ing a counter 55 and a plunger 54, is solidified from the surface. Then, by loading high pressure by pushing of the local pressurizing jig 57, shrinkage cavity, etc., is eliminated. The molten metal contacting part of this local pressu rizing jig 57 is made of sintered alloy containing >=90% W and making >=70kg/cm<2> tensile strength at 600 deg.C. It is executed to plastic-working at 1:>=4 forging ratio and so the surface hardness becomes to >=350 Hv and the durabil ity service life is remarkably extended. In this way, service life of the local pressurizing jig is improved and productivity of the die-casting machine is im proved.
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