MIDDLEEAND HIGHHPRESSURE TWOOSTAGE INJECTION CASTING METHOD AND CASTING MACHINE

摘要

PURPOSE:To enable precision castings without generating vent wells, vent gates and fins to be cast by injecting the material to be worked under low pressure in the state of a large sprue area, and decreasing the sprue area at the injection end thereby feeding the molten metal under high pressure. CONSTITUTION:When a cylinder 2 is advanced, a moving A die 4 and a moving B die 7 advance and approach to a stationary die 8. Thence, both dies 4, 7 and the die 8 are clamped, and the material to be worked is poured through a pouring port 13, thence a low-pressure injection plunger 12 and a high-pressure injection plunger 14 are advanced simultaneously under middle pressure, whereby the material is injected at a middle speed under the middle pressure. The gas in the molds at this time vents through the mating gaps of the respective molds. At the injection end, the sprue area is made smaller. Next, the material is fed under high pressure by a high-pressure injection plunger 14. When the work 11 solidifies, the cylinder 2 is retreated and the moving B die 7 is retreated simultaneously with the moving A die 4, thence the sprue is cut with a sprue cutting punch 19.