Patent GB-754326-A (GB)
Title: A machine for moulding heads made of thermoplastic material upon tubular containers
IPC: B29C45/06
Filed: 1954-12-07
Abstract: 754,326. Injection-moulding container heads. UNI-TUBO SOC. ANON. Dec. 7, 1954 [Dec. 31, 1953], No. 35460/54. Class 87(2) An injection-moulding machine for casting a polythene &c. head H on one end of a preformed polythene &c. tube 5 comprises a horizontal table 1 rotating clockwise about a vertical column 2. The table rotates stepwise to bring sequentially each of six moulds 3 caried thereby into six position A, B, C, D, E, F. At station A a tube 5 is fitted in the mould. From A to B the mould is closed. At B the mould is locked and injection takes place. From B to E the injected material cools. At E the mould is unlocked. At F the tube with head cast thereon is ejected from the mould. Each mould comprises a matrix 6 and a mandrel head 27 carried by a plunger 4, a casing 9 having an injection duct 13, a sleeve 10 having mould-locking pins 46 (see below), two semi-circular plates 15 in which are formed semi-circular screw-threaded recesses, and a vertically-slidable block 12. The plates 15 are normally held apart by springs (not shown) but at station B are urged to the operative position shown in Fig. 2 by upward movement of block 12, the plates sliding along inclined surfaces 14 in the underside of casing 9. Block 12 is pushed upwardly by a hydraulic ram 40 acting through the intermediary of a piston 29 and plunger 4. The tube 5 rests on a projection 28a on mandrel 28 that is mounted inside plunger 4 and carries head 27 and when piston 29 rises the tube is raised and its upper end is clamped between mandrel head 27 and block 12. Ascent of piston 29 also raises injection nozzle 41 off its seat and molten polythene thereupon flows under pressure from injection cylnider 39 through an axial channel in the nozzle into the mould cavity. At station B also, the parts are locked in the Fig. 2 position by means of a locking ring 42 secured to plunger 4; when plunger 4 is raised, bayonet slots 45 in the ring receive pins 46 on sleeve 10 whereupon the ring is rocked (clockwise, Fig. 1) by a hydraulic pusher 52 which engages roller 53 on arm 54 on the ring and moves the arm from J to K. The mould being thus locked and filled, ram 40 is lowered and a spring 34 retracts the assembly from the Fig. 2 position to the Fig. 5 position. the mould sliding downwardly on a rod 19 secured to table 1. As the material in the mould cools from B to E (the mould including a housing 16 through which cooling liquid flows) a spring 58 exerts a follow-up pressure to eliminate stresses due to shrinkage of the cooling polythene in the mould. When the assembly arrives a E a cam 55, acting on roller 53, unlocks the mould whereupon (the pressure of plunger 4 on block 12 being released) springs return block 12 to its lower position and other springs force plates 15 apart, the matrix being thus freed from the moulded article which remains on mandrel 28. A spring 25 then raises the matrix to the Fig. 6 position. As the opened mould travels from E to F a cam 49 engages a finger 48 on a plate 33 that carries plunger 4, and rocks the plate and plunger (about pivot 33<1>) out of vertical alignment with the matrix, and at F compressed air blows the moulded article off mandrel 28. At A fresh tube 5 is fitted over mandrel 28. Between A and B finger 48 leaves cam 49 and a spring 50 pulls the plate 33 back to the aligned position shown in Fig. 2.