| 摘要 |
1,068,318. Extrusion - blow moulding. OWENS-ILLINOIS Inc. June 11, 1964 [June 12, 1963], No. 24194/64. Heading B5A. [Also in Division B8] A shaped plastics article is formed in two stages from material containing an expanding agent, expansion being prevented during the first stage but allowed during the second stage so that part of the article is cellular and part non-cellular. In one application the invention is described as applied to the forming of a bottle by an extrusion-blow moulding process wherein the hot plasticized plastics material in the cavity (23) is injected by a reciprocating sleeve (25) into the space defined by a partible neck mould (26) and a hollow core (27) which then rise to allow extrusion of the tubular extrudate which is severed by a blade (31). The material within the neck mould is substantially unexpanded but the foaming agent expands the extrudate. A blow mould then closes on the extrudate which is blown to conform to the mould cavity. In a modification the reciprocating injection sleeve (25) has a groove (32) which by rotation of the sleeve can be brought into register with the supply channel (24). In another example, a bottle cap is formed in an injection mould (33). The injecting plunger (38) injects a measured quantity of plastics material into the mould and the plunger is retained in the mould while the material in contact with the mould wall sets. The mould then moves upwardly to allow the foaming agent to expand the central part of the cap. It is suggested that low or high pressure polyethylene or polystyrene may be used. |
