Abstract: Workpieces of a synthetic plastics material are heated to enable further lding thereof to be effected. Heating is effected by infra-red radiators and, in order to ensure that localized overheating is avoided, the surface of the workpiece which is exposed to radiation is cooled during the heating process.

Abstract: A blow mold structure for the blowing of containers, bottles or the like rein a coolant fluid is circulated through the mold. The blow mold includes a pair of openable and closable mold blocks, each carrying a mold insert. The changeable inserts cooperably define the mold cavity, and coolant fluid is circulated between each insert and the adjacent mold block to cool the cavity-defining inserts. A series of grooves is formed in the exterior surface of the mold insert, the insert is sealed to its mold block and coolant fluid is introduced into and removed from the grooves through supply passages in the mold block. A chamfered abutment at one end of each insert and a mounting flange at the other end insures quick changing of inserts while maintaining structural rigidity during use.

Abstract: Method for manufacturing blanks from a synthetic plastics material includes mould cavity defined between a mandrel and an outer mould. A retractable sleeve is slidably mounted on the mandrel and is displaceable within the cavity at a rate which depends on the rate at which the plastics material is injected into the cavity.