CONTAINER FORMING METHOD AND APPARATUS

... 1,200,794. Blow - moulding. DOW CHEMICAL CO. 17 Aug., 1967 [24 Aug., 1966], No. 37997/67. Heading B5A. Articles are produced from a preform by heating, compressing its periphery to extrude the material through an aperture and guiding it downwardly without drawing to form a closed end tubular parison and blowing the parison into a mould. A disc preform 26 is heated e.g. by heaters 24 in plate 18, its periphery compressed by piston 28 and the material extruded is guided downwardly into the mould 12, 14 by descent of mandrel 32 without drawing. Sleeve 30 shears the material from the preform and air is blown into the parison through hole 36 in the mandrel and through slit 41. Multiaxial orientation of the article may be effected by rotation of the mandrel or piston. Mould halves 12, 14 may be cooled by ducts 15. Layered preforms may also be used. The parison wall thickness is controlled by varying the rate of compression by the piston relative to the speed of descent of the mandrel.

SCRAPLESS FORMING OF PLASTIC ARTICLES