Patent GB-597012-A (GB)
Title: Improvements in or relating to presses, in particular for the manufacture of bodies from synthetic resins and the like
IPC: B30B11/10
Filed: 1945-08-08
Abstract: 597,012. Rotary-table moulding-presses. STUDLI, H. Aug. 8, 1945, No. 20348. [Class 87 (ii)] [Also in Groups II, XXIX and XXX] A press for forming articles of synthetic resin, comprising an intermittently-rotated turntable carrying a plurality of hydraulic moulding units, which are brought in turn to feeding, pressing and delivery stations, is characterised in that each of the moulding units is connected in turn to the pump supplying pressure fluid only at the moment when pressure is to be exerted, the pump running idly at other times. The turntable comprises a bottom section 4 and a top section having flanges 6, 7. Each moulding unit comprises a vertically stationary upper die 75, which is secured in the flange 7, and a lower die 13 carried in a block 12 secured by a stud 11 to a cylinder 10 surrounding a hollow piston 9 secured in the section 4. During the pressing stroke the parts 10-13 move upwardly from the Fig. 3 position to the Fig. 4 position. The pump 16 is driven continuously by a motor 15, oil normally returning from the pressure side back to the sump 120 by pipe 19. When, however, a moulding unit 9-13 comes into position above the cylinder 25, a valve 20, Fig. 4, is operated to close the pipe 19 so that oil passes into cylinder 25 and raises the piston 27 into contact with the bottom of the piston 9. The oil pressure then opens successively valves 32 and 35, so that oil passes through piston 9 and raises slidable cylinder 10, with its die 13, which is thus pressed towards die 75. Valve 20 then opens, allowing piston 27 to descend and valves 32. 35 to close, and the machine is indexed to bring the next moulding unit into position. Leakage oil from between piston 9 and cylinder 10 is caught in pan 122, Fig. 1, and flows back to the sum p through filter 123. It is stated that such leakage does not impair the action of the machine since air is forced by the incoming'oil past the valve stems 34 into the cylinder 10 and causes any pressure drop to be gradual. Pressure is finally released by the valve stem 34 encountering a roller 37, which opens valve 35 and allows the oil in the cylinder 10 to drop back into the sump 120. Cooling-water pipes 121 are provided in the sump, and an adjustable excess-pressure valve on the pressure side of the pump 16 permits regulation of the moulding pressure. The devices for rotating the turntable, feeding blanks to the moulding dies, admitting fluid to the press cylinder, and removing the moulded products are all operated by cams on a shaft 103 which is driven by motor 94 through a change speed device of the expanding pulley type. The turntable is indexed by means of a spring loaded pawl, mounted on a rocker arm actuated by shaft 103, which engages with ratchet elements 38 on the flange 4. An axially displaceable dog 47 operated by linkage 50 a, b, and c, locks the turntable in position after each step. Feeding. Blanks are placed on an inclined rotating disc 52 and fall into pockets 51 formed between the disc and a rim 58. They drop into an inclined channel 55 and so into the lower moulding dies 13. The disc 52 is driven faster than is necessary to feed a blank to each press by a pawl mounted on a swinging arm operated from the shaft 103. An arm 64, Fig. 6, carrying a feeler 65, is mounted on a spindle 66 which is rocked by each movement of the arm carrying the pawl so that the feeler 65 is lowered into and raised out of the channel 55. When the descent of the feeler 65 is arrested by a blank a stop on the spindle 66 prevents the pawl from engaging, thus interrupting the movement of the disc 52 and preventing clogging of the channel 55. Knives 70, 71 mounted on a swinging lever 69, operated oy the camshaft 103, allow one blank at a time to fall out of the channel 55 when a die 13 registers with it. Delivery. At the delivery station the moulded article, in this case a screw-threaded bottle cap 73, Fig. 3, is removed from the screw-threaded upper die 75 by grippers 79. The latter are carried on bell crank levers 82 mounted on a sleeve 78 and are actuated by the raising and lowering of a thimble 80. The sleeve 78 is carried by an arm 77 on the rockable spindle 83 and is rotated by the motor 94 through the belt 96 and gears 98-102. The thimble 80 is carried by a fork 81 pivoted to the arm 77. By means of suitable cams on the shaft 103 and levers 85, 88, 91, the shaft 83 is rotated to bring the sleeve 78 into position (full lines, Fig. 13) under the die 75, the sleeve is raised and the grippers actuated to grip the moulded article, which is unscrewed, the sleeve and thimble following its downward movement, the shaft 83 is rotated to bring the sleeve into the chain dotted position shown in Fig. 13, and finally the thimble 80 is lowered to cause the grippers to release the article, which drops into the chute 73'. Articles which are not screw threaded may be blown off the dies by compressed air. Heating. The dies air heated bv conduction and radiation from thermostatically controlled resistances 124 and 125, Fig. 1. Heat insulation is provided by layers 129 and by a counterweighted bell 130 suspended over the pulleys 132.