GB688668A - Improvements in or relating to a hydraulic drive, such as may particularly be applied to die and press moulding machines - Google Patents

Abstract

688,668. Injection moulding machines. SAUTER, H., and HAHN, W., (trading as HAHN & KOLB (Firm of)). April 2, 1951 [April 12, 1950], No. 7521/51. Class 87 (ii). [Also in Group XXIX] In a hydraulic drive for machines having a hydraulic driving network 13, 11, 14, 12, 8 common to a pair, or a plurality of pairs, of cooperating cylinders 1, 21 and pistons 2, 22, one (21) of each pair of cylinders and its piston (22) is connected with a pressure accumulator 20 and with the common driving network in such a manner that, in one stroke direction, the piston 22 is relieved from the driving network and is driven by the accumulator and, in the other stroke direction, the piston 22 is driven directly from the driving network, the working movement of the piston 22 being unable to exert any influence over the pressure upon the remaining piston(s) 2. Fluid in a container 10 is drawn through a pipe 13 by a low pressure pump 11 and delivered into a pipe 14 connected to both a non-return valve 18 and a high pressure pump, 12 ; the valve 18 controls a pipe 8 leading to both a valve 5, and a non-return valve 19 in a pipe 15 leading to a valve 25. The valve 5 controls the supply to the piston 2 to which is connected the movable mould half 41 of a die moulding machine, which half carries a piston 39 controlling the movement of the core and an ejector piston 42, these pistons 39, 42, being connected to the hydraulic network. The valve 25 supplies the piston 22 to which is connected an injecting piston 33 projecting into an injection cylinder 34 leading to the cavity 37 in the fixed half 40 of the mould. A mass for moulding is delivered to the cylinder 34 from a tank 35 via a distributing device 36. With the control valves 5, 25 in the positions shown, pressure fluid is supplied via a pipe 7 to the space 4 in the cylinder 1, fluid in the space 3 being exhausted via pipe 6, valve 5 and pipe 9, and the piston 2 moves to close the mould 41, 40. At the same time fluid flows through a pipe 26 into the space 23 in the cylinder 21 to retract the piston 22, fluid in the space 24 being forced through a throttle valve 32 into a pipe 27 to charge the accumulator 20. When the mould 41-40 is closed, pressure builds up in the space 4 and is maintained by the high pressure pump 12. Reversal of the control valve 25 blocks the pipe 26 and cylinder 21 from the driving network and connects them to the exhaust pipe 29. Fluid then flows into the space 24 from the accumulator 20 and the piston 22 moves the injecting piston 33 into the injecting cylinder 34. Reversal of the valve 5 connects the pipe 7 to the exhaust pipe 9' and the pipe 6 with the supply pipe 8 so that fluid enters the space 3 to retract the piston 2. A normally closed valve 30 may be opened e.g. automatically, to charge the accumulator 20 from the pipe 15, and a normally closed valve 31 may be opened to reduce the pressure in the accumulator.