Preheating thermoplastic plate before forming - by passing through heating zone, cooling zone and second heating to produce an even temp.

摘要

The arrangement is intended for pre-heating a sheet or plate (1) in thermoplastic material, such as polypropylene prior to a deep-drawing operation or the like. The plate is passed through a first heating section (A) and then through a cooling section (B) after which it moves through a second heating section (C) before being shaped. The two sections (A and B) may be vertically arranged whilst the final heating section (C) is horizontal. The plate pref. passes through the section (A) in vertically upward, and through section (B) in vertically downward direction. The arrangement ensures that the plate is at the same temp. throughout its thickness which makes it easier to process and produces a better quality prod. than achieved with existing methods, which produce a temp. gradient from outside to inside.