| 摘要 |
PURPOSE:To obtain a tool for hot plastic working having excellent service durability by composing the tool from a tool main-body made of silicon nitride having a formed working surface and a reinforcing body made of WC sintered hard alloy for backing up the main body. CONSTITUTION:A tool main body 2 made of silicon nitride has a working surface formed by grinding a silicon nitride which is hot-press sintered at a prescribed temperature. On the other hand, a ring 3 made of WC sintered hard alloy (a reinforcing body made of WC sintered hard alloy) having an inner diameter smaller than the outer diameter of body 2, is manufactured by a conventional method, and is tightly fastened to the body 2 by shrinkage fitting by utilizing the difference of thermal expansion coefficient between them. In this way, the excellent thermal-shock resisting force and burnout, corrosion, and wear-resisting properties, etc. of silicon nitride are utilized as a die characteristics, and the excellent mechanical strength is secured by the WC sintered- hard-alloy ring having comparatively high mechanical strength.
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