Patent GB-594860-A (GB)
Title: Improved moulding machine for plastic materials
IPC: B30B11/10
Filed: 1945-07-03
Abstract: 594,860. Rotary mould-table machines. ACSPHINX SPARKING PLUG CO., Ltd., CORBIN, D. H., and OLSEN, O. W. DOKK-. July 3, 1945, No. 16861. [Class 87 (ii)] [Also in Group XXIX] A moulding machine comprises a plurality of sets of die members rotatable in stages through a moulding cycle, the relative movements of the die members being effected by hydraulic means under pneumatic pressure. A machine is shown for moulding sparking- plug insulators from a powdered mixture of a ceramic material and a thermoplastic thermosetting resin, such as a mixture of refractory oxides and phenol condensation product. The machine comprises 24 sets of piston and cylinder assemblies 32, 71, Fig. 1, (only two are shown) carrying upper and lower die members 51, 62. An electric motor, through reduction gearing and a Geneva motion, Figs. 11-13, (not shown), drives a pinion engaging the gear ring 14 to rotate the machine step by step. Cams on the reduction gear shaft operate air valves, Figs. 14-17 (not shown), controlling the ejection, delivery and die-cleaning mechanisms. An interlock switch may be provided by which the motor cannot be started until the air supply is turned on. A master valve 110 comprising a perforated and grooved disc, Figs. 6-9 (not shown). controls the supply and exhaust of compressed air from the pipe 112 through pipes 94. 95, 96 to each cylinder 32 to operate the dies in sequence as the machine rotates. Branch pipes 94A. 95A. 96A lead to a block 24 in which are valves for controlling a die assembly by hand if necessary. Each lower die is heated electrically by a coil 63. Fig. 3, controlled by a thermostat 77. A sequence of operations for one die assembly is as follows:- Feeding. A weighing mechanism of known type, controlled by the electric switch 264, actuated by the pegs 263, delivers a measured quantity of moulding powder through the funnel 267 to the lower die. By removing the corresponding peg 263, feed to any. particular die can be prevented. Pressing. The machine then rotates by one step, whereupon the master valve admits air to the pipe 95, Fig. 2. The part of the cylinder 32 between the float 41 and the piston 43 is filled with oil, so that the mass of oil, together with the piston 43 is forced down, driving the upper die 51 into the lower die, and exerting a moderate pressure on the moulding powder. The oil pressure is also transmitted through the pipe 93 to the piston 70, Fig. 3, carrying ejector rod 65. The machine then rotates by another step, during which the pipe 95 is cut off from the compressed air supply and opened to exhaust, and compressed air is admitted through the pipe 94 so that the piston 33 moves down, forcing the rod 34 into the passage in the sealing ring 36 to exert a high pressure on the oil trapped below the ring. This pressure is also transmitted by the pipe 93 to the piston 70 and forces the rod 65 upwards against the pressure of the spring 72, while the upper die yields, compressing the spring 49. The machine rotates through several steps while high pressure is thus exerted on the powder to form it into a moulded article. Then the master valve opens the pipe 94 to exhaust and the pipe 95 to pressure so that the piston 33 is raised, oil passing through the valve-controlled bye-pass 37. The relief of the high pressure on the oil in the cylinder 32 allows the springs 49 and 72 to expand again, and with the moulded article thus under moderate pressure the machine moves through several more steps. Eventually the pipe 95 is opened to exhaust and the pipe 96 to pressure so that the piston 43 rises and raises the upper die 51 away from the moulded article while air pressure, transmitted through the bore 45 depresses the small piston 52 against the tension of the springs 56. The hollow rod 55, carried by the piston 52 and slidable over the rod 64, is thus moved down to ensure the detachment of the article from the upper die. The upper die is held up by engagement of the flange 60, Fig. 1, with a spring. A fixed arcuate member may be substituted for the spring. Ejection. A valve controlled by a cam on the driving-shaft of the machine then admits air to the oil reservoir 91, Fig. 1, so that oil pressure is transmitted through the pipe 88 to the cylinder 82, raising the piston 83, Fig. 5, and bringing the rod 84 into engagement with the bottom of the rod 65. Fig. 3, to raise it, together with the centre pin 64, to lift the moulded article out of the lower die. Cleaning the dies. At the same time compressed air is admitted to the pipe 87 and passes through the bore in the rod 84 to the bore 66 in the rod 65 and so through the branches 67 to blow surplus powder out of the die 62. Delivery. The ejected insulator is gripped by a rubber bag 201, Fig. 18, protruded, by air pressure in the space 202, through apertures 200 in the cup 198. The sleeve 197 carrying the bag 201 and cup 198 is rotated by the electric motor 194 through the flexible drive 212 and gears 208, 207, so that the insulator is unscrewed from a screw thread at the base of the pin 64, the sleeve 197 being carried on counterweighted pivoted arms 189 so that it may rise with the insulator. The whole mechanism is mounted on a carriage 183 which is advanced to operative position by air pressure in the cylinder 185 and retracted to the dotted-line position by springs 186. When the mechanism is retracted air pressure in the space 202 is released and the insulator falls into a delivery shoot. Air supply to the cylinder 185 and space 202 is controlled by cams on the driving shaft of the machine. The plates 190, supporting the arms 189, are mounted on a pivot 188 to be rotatable, against the tension of the spring 214, in order to prevent damage if the machine rotates while the carriage 183 is in operative position. The motor 194 may run continuously or intermittently. The sleeve 198 may be lifted pneumatically as the insulator is unscrewed. The die assembly has now completed one moulding cycle and the next rotational step of the machine brings it back to the feeding position. Rendering a die assembly inoperative. If one of the pegs 263 is removed and placed in the corresponding lower hole 254, the switch 264 is not operated and so there is no feed to the corresponding die assembly. The peg 263, however, operates a switch 253 which cuts off the air supply to the ejector and delivery mechanisms when that die assembly is opposite them. A valve 98 may be operated manually to close the corresponding set of pipes 94, 95, 96.