GB1376790A - Method and apparatus for the mass production of hollow bodies of plastics material - Google Patents

Abstract

1376790 Extrusion blow-moulding A DI SETTEMBRINI 23 March 1972 [13 April 1971 14 June 1971 9 Aug 1971] 13715/72 Heading B5A In an extrusion blow-moulding process, moulds are moved around a closed path receiving at least one piece of extrudate from an extrusion head and blow-moulding the extrudate as the moulds move on, the article produced being taken from the mould after opening thereof and moved along a path substantially parallel to at least part of the path of the moulds. As shown in Figs. 1, 2, two upper tables 3 and two lower tables 4 rotate at the same speed on columns 2, the lower table carrying split moulds 5 on guide track 6 past extruder head 7 which is mounted to swivel for access. The upper table carries a corresponding number of rotatable blowheads 9 each having at least two vertically reciprocable blowing and removing mouthpieces 10, 11. Moulds 5 are opened and closed by means of rollers 12 moving in cam tracks 13, 14, the rapid closing under the extruder head being assisted by jack (15, Fig. 3, not shown). The extrudate is blow-moulded by one of mouthpieces 10/11 which is lowered into it and after mould opening, the blown article is retained on it when it is raised. At position 16, shaft 9 is rotated so that the vacant mouthpiece 10/11 can operate on the newly extruded extrudate while the blown article makes another circuit before being released at position 17 on to delivery conveyer 18. On mould closure, jaws (19, 20, Figs. 4-6, not shown), grip the bottom flash and subsequently move downwardly to sever the flash and eject it. In the embodiment of Figs. 7-11 (not shown), the removal devices (22) constitute a vertically reciprocable rod (28) mounted on radially movable arm (23) which also carries a vertically reciprocable stripper (30), blow-moulding being effected by a nozzle (not shown), forming part of the mould. A separate removal conveyer (32, 33) is provided for each turntable, blown articles being taken from device (22) at position (38) via rotary table (40) having funnels formed by plates (46, 47) to which they are fed by stripper (30). Table (40) rotates until hole (48) in the underlying table (41) is reached, whereupon the blown article falls through shoot (49) onto table (50) and thence on to conveyer (32/33). In Figs. 12, 13 (not shown), the article is stripped from its removal rod to fall through shoot (60) on to a rotating perforated plate (62) through which vacuum is drawn to hold it upright, before passing it to conveyer (71). The extruder may provide a plurality of lengths of extrudate and the blow-moulds correspondingly multi-cavity.