Patent ID: 6726873
Filing Date: 2004-04-27
Classification: B29C,B29K,B29L

Abstract:
A method of forming a plastics material article comprising the steps of:forming an injection moulded preform between a stationary base mould part and a movable substitutable part which together define an initial mould cavity for injection of the preform, moving the substitutable mould part after injection of plastics material into the initial mould cavity to leave the preform stationary on the base mould part, positioning over the preform in place of the substitutable mould part at least one replacement mould part to define a cavity larger than the initial mould cavity, stretching at least part of the preform away from the base mould part against the replacement mould part(s) to form a finished article shape, and removing the replacement mould part(s) in order to release the finish formed article, wherein the Substitutable Mould Past is separated from the preform after the latter has skinned against it, but before the preform has solidified throughout its thickness, at least in the portion of it to be stretched, wherein the method includes injection of gas between it and the Base Mould Part to separate at least part of the preform from the Base Mould Part, wherein the stretching of the preform is effected by injection of gas between it and the Base Mould Part,wherein the stretching of the preform is effected by lifting a portion of the preform from at least part of a main piece of the Base Mould Part by a movable piece of the Base Mould Part, wherein the lifted portion of the preform is moved by the movable piece of the Base Mould Part as far as a corresponding piece of the Replacement Mould Part(s), wherein the lifted portion of the preform is captivated between the movable piece of the Base Mould Part and the corresponding piece of the Replacement Mould Part(s) at the end of the stroke of the movable piece, and wherein the captivation of the lifted portion of the preform temporarily seals apertures in the lifted portion.