Patent GB-812452-A (GB)
Title: Improvements in automatic rubber moulding machine
Filed: 1956-09-24
Abstract: 812,452. Injection-moulding machines. UNITED STATES RUBBER CO. Sept. 24, 1956 [Oct. 25, 1955], No. 29084/56. Class 87(2). A rubber articles, e.g. a shock absorbing mounting, is formed by injecting rubber stock in an injection cylinder 58, Fig. 1, through a sprue opening 126, Fig. 23, in a mould plate 116, the machine being operated by electircally controlled pneumatic and hydraulic systems. In operation, a mould cover plate 117 slides down a slide K, operating a switch S1, which brings into operation the plunger 221 of a pneu. matic cylinder 219 to push the plate on to landing bars 113, Fig. 2, and into contact with switches S6,S6<SP>1</SP>. A lug 223 on the piston 221 closes a switch S2. A hydraulic piston 167 pushes downwardly on a stack of moulds 116 and cover plates 117 and during this pushing down movement, rods 172 close switches S5,S19. The switch S19 causes a solenoid to be energized and pawls 145 which hold the top of mould stack to be rocked outwardly also causing switches S4,S3 to be closed. As the piston 167 engages the top mould plate, pawls 170 are biased outwardly to engage under lugs 118 on the mould plate. On the closing of switches Sl to S6 which are connected in series, a pneumatic cylinder 91 operates a valve 93 to cause fluid to be supplied to a cylinder 61 and push the injection unit C upwardly. As this occurs, lugs 75 on the injection head 57 push the landing bars aside, and the plate 117 rocks pawls 135, which hold the lower end of the mould stack, outwardly, until it overlies the prongs of the pawls. As the mould column forces the piston 167 upwardly, switch S19 is opened to deenergize the solemoid and rock pawls 145 together over the plate 117 immediately below the top mould 116. As the mould column continues to move upwardly, the pawls 145 are forced up until they reach stops (not shown). At this point, levers 139 are pivoted upwardly until switches S7,S8 are closed, which actuate valves 163 and 220 to return the piston 167 of motor 162, a n d plunger 221 of motor 129, respectively. As the piston 167 continues upwardly, a chain 175 is pulled to break contact with switch S7, to deenergize valve 163 and stop further movement of the piston 167. Simultaneously, one of the rods 172 closes a switch S9, and valve 93 is operated to ca,use the motor 61 to lift the injection unit C, but injection does not take place, as the plate above the injection unit is a cover plate 117. On receding, the injection unit C momentarily closes switch S14 which operates a valve 181 causing the plunger 182 to push the mould plate 116 which has been picked up by pawls 170 between horizontal bars 185, where the mould operates switch S10. At the same time, the mould 116 pushes the preceding cover plate 117 over ejection unit J the repositioned cover plate 117 pushing the preceding mould down slide K. The mould over the ejection cylinder 198 being released from a catch 195 by the action of the following mould on a cam not shown. As a mould 116 goes down slide K, it closes a switch S15 which acts to retract the plunger 182. The mould also opens switch S16 which prevents the plunger 200 of the ejection cylinder from operating as a cover plate is now positioned above the ejection cylinder, and also prevents a motor 40 which acts to push rubber stock coiled on a table 35 into the injection cylinder 58 which is still full, since no injection took place during the previous cycle. As the plunger 182 nears the end of its retraction stroke, switch S18 causes the piston 162 to push down on the mould assembly again. Meanwhile, a mould plate reaches the lower end of slide K hits a bumper 213 and falls backwards down the lower part 202 of slide K where it operates the switch S1 to cause the plunger 221 to push it over the landing bars 113. The cycle then begins again, but this time since a mould 116 now lies under switch S10 the valve 100 is operated which allows hydraulic fluid to be fed to the injection cylinder 58 and push the injection plunger upwardly to cut off a piece of stock and inject it through nozzle 74 into the mould. As the injection plunger moves upwardly, it closes a switch Sll to start timer T which after the desired period operates a switch to energize the valve 100 and retract the injection piston. As the injection nozzle 74 is withdrawn, a wire W, Fig. 3a, removes excess stock from the mould. As the injection unit continues to retract it closes switch S14 which actuates the piston 182 to push the mould over the ejection piston 200. As the cover plate 117 going down slide K cannot operate switch S16, the plunger 200 is raised. to eject the moulded article out of the mould 116. In addition, the normally closed switch S16 energizes the valve 41 to cause piston 42 to feed stock to the injection cylinder the piston being retracted by switch S17. It also operates switch S18 which causes the piston 162 to push downwardly and the ejection piston 200 to be retracted. , Meanwhile a cover plate 117 has passed down slide K and operated switch Sl to recommence the cycle. The injection unit is provided with heating coils 76, 80. The mould assembly is surrounded by heating elements 160 regulated by a rheostat and mounted within insulating walls 156.