| 摘要 |
<p>1441657 Blow-moulding; parisons ILLINOIS TOOL WORKS Inc 3 July 1973 [3 July 1972] 31622/73 Heading B5A In the blow-moulding of a parison by means of a mandrel on which the parison is placed, the parison comprises an inner surface generally complementary to the outer surface of the mandrel but also has a plurality of circumferentially spaced internal protuberances which initially contact the mandrel and provide passageways therebetween for air evacuation therefrom to enable uniform heating thereof by the mandrel. The protuberances may be in the form of knobs or longitudinal ribs. The passageways therebetween disappear on heating to provide, on blow-moulding, an article of uniform wall thickness.</p> |
