GB1031099A - Hydraulically operated apparatus having application in injection moulding machines - Google Patents

Abstract

1,031,099. Hydraulic presses; injection moulding machines. MANNESMANN-MEER A.G. Nov. 28, 1962, No. 45011/62. Headings B5A and B5F. Relates to hydraulic apparatus in which a member, e.g. the mould-carrying member 4 of an injection moulding machine is moved rapidly over the first and greater part of its advancing travel, locked against reverse movement and thereafter moved slowly over the last part of its travel, and is also moved slowly over the first part of its withdrawing travel and then rapidly for the remainder of its travel. According to the invention the member 4 is moved by apparatus comprising a movable cylinder 10 having two parts of different diameter, in the smaller of which is a fixed piston 8 and in the larger a movable piston 7, rapid movement being caused by movement of the cylinder 10 relatively to the fixed piston 8, and the slower movement by movement of the piston 7 relatively to the cylinder 10. For the first part of the advance movement, a lowpressure pump 13 supplies fluid through valves 15, 16, 17 and a bored piston-rod 18 to a chamber 20 within cylinder 10. Movement of piston 7 relative to cylinder 10 is prevented by springs 23 (Fig. 1, not shown), or a pressure accumulator 24 (Fig. 3b, not shown), or a high pressure pump 25 (Fig. 3c, not shown). When the cylinder 10 reaches the position seen in Fig. 2 (not shown), it is locked by means of plungers 11 and valve 15 is changed over so as to apply high pressure fluid from a pump 14 to the chamber 21. The pressure of springs 23 &c. is overcome, and a sealing element 22 lifted so as to expose the whole of piston 7 to the high pressure. By changing over valve 16 and then valve 15 low pressure high-speed opening is effected, the speed being further increased by changing over valve 17.