GB706854A - Improvements in injection presses - Google Patents

Abstract

706,854. Injection-moulding machines. CAYLA, G. April 24, 1951 [April 24, 1950; Sept. 16, 1950], No. 9584/51. Class 87 (2) The mould halves of an injection-moulding machine are closed by jacks which lock the halves together without subjecting the supporting columns of the machine to additional. stresses. The mould halves 8, 9 and the injection cylinder 5 are mounted on vertically movable platens whilst the injection piston (not shown), is fixed. When the press is fully opened the pistons 35, 36, Fig. 3, lie at the bottom of hydraulic cylinders 34, 37. To close the press, fluid is admitted to the cylinders 34 -via valves 56, 39 and the piston 35 rises rapidly until the mould has been closed and brought into communication with the injection cylinder 5. At the same time, fluid flowing into jacks 60 tends to displace pistons 59, 61 in opposite directions and locks the mould parts. As injection cylinder 5 commences to move over the fixed plunger, pressure increases in the cylinder 34 and the liquid displaces piston 36. Pin 41 now allows the valve 39 to close and the injection stroke is completed under the high pressure exerted by the large-area piston 36. During the injection stroke this high pressure is transmitted to the jacks 60. In an alternative form of the press of Fig. 3, the parting plane of the mould lies in the direction of displacement of the injection cylinder and the jacks lie perpendicularly to this direction. A further alternative is briefly described, in which the injection cylinder is fixed and its plunger movable. In the modified press of Fig. 9. the jacks 60 are four in number and are supplied with fluid from the cylinder 34 via a valve box 72 containing two valves 73, 74 each controlling two of the jacks 60. By means of screws 92, 93 the valves 73, 74 may be raised against their seats and two of the jacks, or all of them put out of action: To open the press, distributer box 90 is manipulated to supply fluid to the upper faces of pistons 35, 36 and also to the lower faces of pistons 87, 88 via the pipe 89. The valves 73, 74 are raised and the jacks 60 connected to the exhaust pipe 85.