GB1379536A - Cyclic process for continuously blow-moulding containers - Google Patents

Abstract

1379536 Blow-moulding HERCULES Inc 27 June 1973 30642/73 Heading B5A Containers are blow-moulded from a continuously generated thermoplastic tube by heating it, closing each of a plurality of moulds successively about a portion of the tube between the heater and the preceding mould and moving away from the heater faster than the speed at which it is fed to the heater to stretch the portion from the heater, clamping the tube between the heater and the mould after each mould has moved a predetermined distance from the heater to stretch and orient the tube between the clamp and the mould and retarding the previously stretched tube portion between the clamp and the heater so that it relaxes during clamping, the portion in the mould being blow-moulded and this mould then being recycled. In operation, one mould 14, Fig. 6, closes on extrudate 10 from the oven and, after moving a distance "L" from the open clamps 12, at the position X (Fig. 5, not shown), the clamps 12 move at the same speed as the mould, i.e. faster than delivery of extrudate from the oven and after a further distance D (almost 1¢L) clamps 12 are closed, Fig. 6 and moved back to position X (Fig. 7, not shown), while the mould moves on further to position Z so that the length of extrudate between the mould and clamps is stretched from a length L to 2¢L and oriented, and the stretched length between the oven and the clamps merely recovers elastically. Meanwhile, the other mould 16 is open and is returned to the starting position (Fig. 7, not shown) and an article 18 is blow-moulded in the mould 14 and, after opening mould 14, is passed to a finishing station. In an alternative method of operation, (Fig. 8, not shown), the open clamps 12 and closed mould 14 move together a distance D, where clamps 12 stop and the mould then continues a distance L to position Y. The clamps 12 then close and move back to their initial position X while mould 14 moves on to Z.