Mfr. of plastics screw-threaded and/or undercut crown closures - using multi-core deep-draw mould operated by both vacuum and pneumatic pressure

摘要

Mfr. of plastics crown closures comprises deep-drawing plastics sheet over matrices with corresp. cores; severing the resulting closures from the remainder of the sheet; and removing them from the cores by pressure exerted at the centre and a point at the periphery. This provides simultaneous mfr. of =1 screw-threaded crown closures from single plastics sheet. The number of simultaneous mouldings can be relatively great, thus rendering the claimed process economical. The centrally applied pressure is generated pneumatically, whilst the peripheral pressure is exerted mechanically, specifically by a plunger.