MANUFACTURE OF PLASTICS MATERIAL ARTICLES

摘要

In the continuous heating of plastics sheet material the expansion of the undesirable material tends to result inwrinkling which causes undesirable temperature variations. To compensate for the expansion without wrinkling the material 16 is supported on spikes 14A integral with links 12 of an endless chain 5 which are caused to progressively spread further apart as the material is carried through the heating zone. The spreading is effected by gradually straightening out kinks, which are initially introduced into the chain to bring the supporting links closer together at the entry E to the heating zone. The technique is particularly applicable in the heat softening of plastics sheet material prior to thermoforming of articles such as drinking cups.