Improvements in or relating to moulding of plastics material

摘要

1,083,732. Extrusion/blow-moulding. AGK A.G. FUR KUNSTSTOFFPRODUKTE. Sept. 17, 1964 [Sept. 20, 1963], No. 37961/64. Heading B5A. In extrusion blow-moulding apparatus, the tubular extrudate has a non-uniform wall thickness so that the finished article e.g. a barrel, is thickened in particular cross-sectional areas. The non-uniform tubular extrudate is obtained by the movement of the mandrel 14, Fig. 5, in the extruder head 13 being made to correspond with the movement of the piston 32 which controls the supply of plastics to the extruder head 13. The blow mould comprises body parts 41, 411, top parts 43, 431 and bottom parts 45, 451. In operation, the tube is extruded over the blowing nozzle 58, the top and bottom mould parts 43, 431 and 45, 451 which are axially spaced from the body parts 41, 411 close and pinch the extrudate. The body parts 41, 411 then close and blowing is started. The top and bottom mould parts 41, 411 and 43, 431 are moved axially to abut the body parts after which blowing may be continued. The bottom mould parts 45, 451 are provided with separable wedgeshaped thread forming members. In another example, Fig. 6 (not shown), the extruder mandrel and impeller are separately controlled from programme cams.