DRY EXPANSION DEVICE OF PLASTIC TUBE

摘要

PURPOSE:The title expansion device designed to manufacture an expanded plastic tube with a slight longitudinal elongation continuously, by preheating and precooling a tube before thermal expansion. CONSTITUTION:The plastic tube 5 fed under a low tension is heated in the preheating part 1 at a temperature not lower than the softening point but not higher than the melting point, and precooled in the part 2 directly to give a tube shrinkage of 0%. The tube 5 is then reheated in the heating part 3 to give a negative tube shrinkage, and expanded in the part 4 so that the longitudinal elongation is about + or -0% even when produced and increased with increasing linear velocity. The difference between the supply speed V1 and the winding speed V2 is a shrinkage speed applied to the tube 5 by the parts 1 and 2.