Patent GB-732785-A (GB)
Title: Improvements in or relating to an apparatus for casting hollow articles
Inventor: MARTIN HENRY
IPC: B29C41/06
Filed: 1953-02-26
Abstract: 732,785. Moulding hollow articles from vinyl resin. SUN RUBBER CO. Feb. 26, 1952, No. 4996/52. Class 87 (2). Hollow articles are made from plasticized vinyl resin by delivering a measured charge of the resin to non-porous moulds which are rotated about a number of axes as the resin is gelled, fused and finally cooled in the moulds. Each mould 105, Figs. 3, 4, is mounted in a yoke 100 which is rotated about a shaft 99 by bevel wheels 102, 103 and sprockets 80, 89 connected by a chain 90. The yoke is mounted on the extremity of an L-shaped crank 82 the inner end of which is fixed to a shaft 72. The shafts 72 are journaled in a double conveyer chain 24 which comprises rollers 28 and links 25. During a certain portion of the travel of the conveyer, a pinion 76 fixed to the centre of the shaft 72 engages a rack 78 and the crank 82 is caused to rotate. The sprocket 80, rotatably mounted on the shaft 72, rotates with the shaft until a pin 94, fixed to the sprocket, strikes the conveyer chain and holds the sprocket stationary. Under these conditions the chain 90 will drive the sprocket 89 as the crank 82 moves about the axis 72. The moulds will thus be rotated about two axes. The rack 78 extends from the filling station at the righthand end of the machine through a heat-insulated oven 55, Figs. 1, 3, where the plastic material is gelled and fused in the rotating moulds. The oven contains two long chambers enclosed by reflecting walls 58, 60. It is heated by heaters 59 and the temperature, which may vary from 300‹ to 650‹F., is controlled by heat-sensitive bulbs 69. On leaving' the oven, the moulds pass around the conveyer driving-wheel 39 and thence through a cooling tunnel 64 where the moulds are cooled by water sprays fixed to the roofs of two parallel cooling chambers. The pinions have by this time left the rack 78 so that the cranks hang under their own weight and the yokes take up a non-uniform angular position with respect to the conveyer. As each mould enters the cooling chamber a roller 92, Figs. 4, 13, strikes a pin 170 fixed to the girder 20 and the crank is rocked to the angular position shown in Fig. 13. During this rocking movement, rotation of the sprocket 80 is arrested by contact of the pin 94, which is now under the conveyer, with the underside of the chain and this results in a rotation of the yoke to a position at right-angles to the chain. As the roller 92 passes off the pin 170, the crank falls by gravity to the vertical position. The yoke, however, remains in the desired position since the pin rotates with the sprocket 80 away from the chain. Before the yokes enter the mould-opening mechanism, Fig. 14, it is necessary to turn them into a position parallel to the conveyer chain with the slide-bars 118 lowermost and this is done by interposing, in the path of cam shoes 96 on the cranks 82 a plate 182 which has a similar effect to the pin 170. The shoe 96 now passes from the plate 182 onto a curved cam track 185 and the yoke enters the flared opening between a pair of vertical plates 190, 191, Figs. 14, 16, the locking lever 134 being rotated to the open position as its arm 137 strikes a raised portion of the plate 191. The unlocked mould is opened by the curved cams 198 which engage the roller 125 on the end of the slide bar 118. It is then discharged by hand. As each mould passes from the opening station to the charging station, Fig. 20, it is guided by engagement of the roller 92 in a track 145. During passage through the charging station the roller rides on cams 148, 156 whilst the rollers 125 are guided on curved rails 161 fixed to the inside of a pair of parallel plates 164. The empty moulds may be sprayed with a plasticizer (acting as a wetting agent) by means of spray guns 320 actuated by a microswitch 323. At the charging station the yokes actuate two further microswitches 311, 312 one of which causes a pivoted solenoid-operated delivery nozzle (not shown) to tilt forward over the lower mould-half whilst the other causes a measured charge to be delivered to the nozzle. When the rollers reach the end of the rails 161 the upper mould-half falls and closes the mould. A pneumatic hammer 201 controlled by microswitches ensures that the mould is properly closed. Thereafter the locking lever 134 is closed as its arm strikes a spring-loaded roller (not shown). If the lock fails to operate, the arm strikes a microswitch which stops the conveyer.