OUTER DIAMETER SIZING METHOD* TUBE MANUFACTURED THEREBY AND SIZING DIE USED THEREFOR

摘要

PURPOSE:To prevent the generation of scratches at a tube outer surface and to obtain a smooth and beautiful tube good for direct printing by laying lubricant between a tube outer face pushed out by an extruder and a die inside wall. CONSTITUTION:In a sizing starting position of the end of a sizing die 34 on the side of an extruder 31 a pouring out hole 44 of cooling water as lubricant is provided. And with a core 33 of the die 32 of the extruder 31 and a ring 38, the plastic tube 36 is horizontally extruded to be passed through the water-cooled sizing die 34. Simultaneously from an air leading-in hole 35 provided to the core 33 air is fed to make the tube 36 stick to the die 34 closely. On the other hand, the lubricating cooling water from the pouring-out hole 44 is fed between the outer surface 47 of the tube 36 and an inside wall 48 of the die 34 through a ring-shaped groove 45 to form water film for preventing the generation of a scratch at the outer surface 47 of the tube 36. EFFECT:Foreign matters in the tube, roughness owing to bubbles appear on the inner surface and also the tube cooling is unified.