Patent GB-677635-A (GB)
Title: Improvements in means for controlling hydraulic moulding presses and other hydraulic apparatus
IPC: B30B15/16
Filed: 1949-02-10
Abstract: 677,635. Hydraulic machines. CARTER, A. March 27, 1950 [Feb. 10, 1949], No. 3607/49. Class 69 (ii) [Also in Group V] Means for controlling the operation of hydraulic moulding presses and other hydraulic apparatus having a plurality of cylinders comprises a plurality of fluid-operated control or distributing valves respectively connected to different cylinders for reversing the movement of the pistons therein, a main pump, a fluid-operated neutralising valve adapted to connect the pump either to exhaust or through the respective control valves to different cylinders of the apparatus, a fluid-operated isolating valve between the neutralising valve and pipe lines leading to the control valves in order to connect the outlet of the neutralising valve selectively to the control valves of different cylinders, and a plurality of pilot valves under the personal control of the operator arranged to cause operation of the control valves the neutralising valve and the isolating valve by fluid pressure in the desired sequence. Fig. 1 is a diagrammatic view of the lower portion of a hydraulic system of a hydraulically operated moulding press and Fig. la is a diagrammatic view of the upper portion of the system, this Fig. being intended to be read as an upward continuation of Fig. 1. The press comprises horizontal cylinders 1 housing pistons 4 for moving together half dies or moulding boxes (not shown) first to a charging position and then to a closed position for compression and moulding. A top cylinder 2 houses a piston 6 for effecting the moulding operation and a bottom cylinder 3 houses a piston 7 for ejecting moulded articles from the die or mould. A main high-pressure pump 8 supplies liquid under pressure for operation of the pistons 4, 4, 6, 7. The system comprises four valves 19, 20, 21, 22, each of which controls the supply of liquid from an inlet port 26 to pipes connected to one or other of two connections 27a, 28a, the other pipe being connected to exhaust. A relief valve 34 is provided. Each valve is pressure operated and when pressure from an auxiliary pump 17 is applied to an end connection 41 of the valve it corrects the inlet 26 to the connection 28a and when pressure from the pump is applied to a connection 36 the valve connects the inlet to the connection 27a. The pressure is supplied to the various connections 41, 36 under control of four pilot valves 53, 75, 85 and 89. Each pilot valve has two pistons. In a normal position it connects the pump 17 which delivers to an inlet connection 63 of the valve to connection 64, and connects a connection 65 to exhaust. When the valve is operated it connects the pump to the connection 65 and the connection 64 to exhaust. Two further pilot valves 16, 18 are employed, each of which when operated connects the auxiliary pump 17 to outlet 47. The pilot valve 16 controls the opening of a neutralising valve 10 by means of which the delivery of the pump 8 may be connected either to exhaust or to the inlet 26 of the valve 19. The pilot valve 81 controls the opening of a non-return valve 43 by which the pressure can be held in the outer ends of the cylinders 1. The pilot valves 16, 53 are operated by a common handle 68 by which the valve 16 is first operated and then while it is still held in its operative position the valve 53 is operated. After the valve 16 has been operated and before the valve 53 is operated the pilot valve 75 is employed to move the valve 22 into a position in which liquid pressure is supplied to the ends of the cylinders 1. Before the pistons have quite closed, the moulding dies the handle 68 is released to arrest the pistons. The pilot valve 75 is then released and the dies changed. Then the pilot valve 75 is again operated and the pilot valve 16 depressed to fully close the dies. When the handle 68 is depressed to operate both of the pilot valves the auxiliary pump moves the isolating valve 19 into a position in which it supplies liquid to the control valve 20 and at the same time the pilot valve supplies pressure to an intensifier cylinder 72 causing the intensifier to create a high pressure in. the outer ends of the cylinders 1. While the pilot valve 53 is held down the pilot valve 89 is depressed to operate the control valve 20 and move the ram 6 down to complete the moulding operation. The full sequence of operations is described in the Specification. The valves 81, 85 are pedal operated. The construction of the valves 29, 20, 21, 22 is shown in Fig. 2. In the left-hand position of the valve member 24 a groove 29 and holes 30 connect the connection 27a to exhaust. A piston 37 of greater diameter than a piston 30 is employed for operating the valve member when pressure is supplied to an inlet 36. Fig. 6 shows a convenient constructional form of the press. The upper cylinder 2 is supported on a frame 98 and carries guides 99 in which slide rods 100 carried by a tool holding plate 101. The horizontal cylinders 11 are mounted on a table 102 so that they can be adjusted angularly. Two arcuate plates associated with each cylinder slide in concentric circular slots of inverted T section in the table, the plates each being carried by the lower ends of two bolts or studs provided with nuts. The bolts pass through a further plate which carries the associated cylinder and by means of the nuts the cylinder can be locked to the table. Each cylinder is mounted on its associated plate by means of a keyway which fits a slot in the plate, two slots being provided in order to give two positions of adjustment of the cylinders to provide for either large or small mouldings. Below the table is a reservoir 114 housing the control valves. The pilot valve handles 93, 79, 68 are mounted at the front of the tank and the foot pedal 88 is at the lower part of the structure. The pumps are driven by an electric motor 115.