Injection moulding e.g. hollow articles - by injecting shot to completely fill mould and then injecting gas or liq. into that shot, so forcing part of it back out of the mould

摘要

Hollow or two-ply laminar plastic injection mouldings are produced by injecting one component into the mould and then injecting or blowing the second component or a gas respectively. Sufficient melt is injected to completely fill the mould; the second component, a gas, or a liq. is then injected into the shot of melt, and a part of the melt is forced out of the mould. ADVANTAGE - The procedure eliminates such faults as (e.g.) weld lines at the interface of the first and second injections, need for precise vol. of shot, problems with the non-return valve etc. which can arise with such a process hitherto.