Blow moulding machine using the parison reheat process for prodn. of hollow plastic products

摘要

A blow moulding machine using the parison reheat process to produce hollow plastic prods. has a heating zone (1) for heating cold parisons and a blowing zone (7) in which appropriately spaced parisons are fed to and inflated in blowing mould cavities. Both zones (1, 7) have parison conveyers (2, 10) which are guided around diverting rolls (3, 9) respectively. Heaters (6) are located along the first conveyer (2) and blowing moulds (8a) alongside the second conveyer (10). Arms (4) along the sides of the heating zone conveyer (2) pick up and hold closely spaced parisons during passage of the heaters (6) and at the point where they pass around the diverting roll (3) opposite the blowing zone (7) spread out at their free ends due to the larger radius of travel of the mandrels compared to the conveyer (2). A transfer member (11) between the diverting roll (3) and the blowing zone (7) simultaneously removes a group of successive parisons from their mandrels in the spread out condition and places them at this spacing on the blowing zone conveyer (10), the spacing corresponding to the spacing of the blowing mould (8a) cavities. Pref. a control system for moving parisons along both conveyers (2, 10) in cycles comprises moving and stationary periods. Transfer of parisons between the heating (1) and blowing (7) zones occurs during a stationary period of both conveyers (2, 10). During each cycle the heating zone conveyer (2) advances a number of parisons equal to the number transferred to the blowing zone conveyer (10). Two blowing zones (7, 7a) each with a conveyer (10, 10a) may be supplied with parisons from a single heating zone (1), transfer between the latter zone (1) and former zones (7, 7a) being effected by a pair of transfer members (11, 11a), one on each side of an extension to the middle plane through the heating zone (1). Both conveyers (10, 10a) move in the same direction and each transfer member (11, 11a) transfers alternate batches of parisons to the conveyers (10, 10a).