GB803553A - Improved machine, of great power, for injection moulding of thermoplastic materials - Google Patents

Abstract

803,553. Injection-moulding machines. F.I.M.S.A.I. SOC. r. L. FABBRICA ITALIANA MACCHINE STAMPAGGIO AD INIEZIONE. Aug. 2, 1955 [May 12, 1955], No. 22146/55. Class 87(2). The cylinder-piston assembly 20, 21 that clamps two mould parts closed is movable as a whole and carries the movable mould part 10. In the mould-closing action first the cylinderpiston assembly 20, 21, with its mould part, moves towards the fixed mould part under the action of piston and cylinder 33, 30 until the mould is nearly closed, then the assembly is locked in position and finally the piston 20 is moved to clamp the mould parts together. The drawings show a horizontal-type machine having a fixed bed 14 and fixed crossheads 16, 17 (not shown) carrying four fixed rods 15. The movable mould part 10 is secured to a large piston 20 slidable within a cylinder 21 having four arms 23 ending in sleeves 24 which slide on the rods 15. The parts 10, 20, 21 form a unit slidable on the rods 15, this unit being pushed rightward towards the fixed mould part by small hydraulic pistons 33 secured to the cylinder 21 at 34 and pulled leftward, after injection, by small hydraulic pistons 36 also secured to the piston 20. When the unit has been pushed to nearly-mould-closed position it is locked on the rods by hydraulic pistons 44, 47, Fig. 48, which tighten jaws 41, 42 in grooves 40 on the rods 15. The cylinder 21 incorporates a pressure-regulating and pressuremultiplying device comprising a cylinder 54, Fig. 6, having a double piston comprising a larger part 52 slidable in 54 and a smaller part 50 slidable in a bore in cylinder 21. When hydraulic pressure is introduced into space 53, part 50 advances into space 51 in cylinder 21 and so raises the pressure in the latter. The axial movement of the double piston is restricted by a plate 55 adjustable by a screw 58.