| 摘要 |
PROBLEM TO BE SOLVED: To prevent lowering of injection pressure when switching operation from electric power to oil hydraulic power in an injection apparatus for die casting which performs injection, filling, boosting, and holding of molten metal by an electric motor and a hydraulic cylinder. SOLUTION: A hydraulic cylinder 6 and a nut 24 of a ball screw mechanism 8 are connected to a rod 5 of a plunger 4 which fills a cavity C of a die 2 with molten metal in parallel, and an injection motor 9 is connected to the screw shaft 23 of the ball screw mechanism 8. The cavity C of the die 2 is filled with molten metal M by driving the plunger 4 by means of the injection motor 9 and the ball screw mechanism 8. The hydraulic cylinder 6 is actuated by a hydraulic device 7 to boost the pressure of molten metal. At this time, the speed of the injection motor 9 is controlled, thereafter is switched to a torque control, thereby surely imparting a constant thrust force to the plunger 4, so as to prevent the lowering of injection pressure when switching the operation from electric power to oil hydraulic power to improve the molding quality. COPYRIGHT: (C)2008,JPO&INPIT
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