| 摘要 |
1,102,614. Casting-machines. GEBR. BUHLER. 12 May, 1965 [13 May, 1964], No. 20030/65. Heading B3F. [Also in Division F1] In a machine in which casting material is injected into dies 4 through a sleeve 15 by a heatresistant plunger 13 attached to a piston 11, the latter is driven by oil (e.g. delivered by a pump 32) to give an initial slow injection and is then given a rapid injection movement by oil at higher pressure from an accumulator 20. In the embodiment shown, a valve 46 is opened to apply the higher pressure. To reduce the kinetic energy built up in the injection stroke, the plunger 13, piston 11 and its rod 12 are made of light material, e.g. aluminium, and the oil volume is kept low by locating the accumulator near the piston cylinder 10. In fact, the accumulator (20<SP>1</SP>), Fig. 3 (not shown), may be combined with the cylinder (10<SP>1</SP>), there being a dividing wall (61) defining a valve seat for a solenoid-controlled valve (63) which by slight, and then full, opening gives the slow then rapid injection. In either embodiment, the accumulator 20 (20<SP>1</SP>) is a chamber divided by a free piston 21 (21<SP>1</SP>) into two parts, one part 27 being connected to a cylinder 25 (25<SP>1</SP>) of compressed gas for giving the high injection pressure. In the present embodiment, a reversing-valve 40 in one position directs oil from the pump 32 to operate the piston 11 and, in the other, directs the oil to retract the piston. In the second embodiment, the reversing-valve (80) in the one position does not alone operate the piston (11<SP>1</SP>) but permits maintenance of the oil in the accumulator (20<SP>1</SP>) by the variabledelivery pump (70). |
