CONTROL METHOD FOR THE MANUFACTURE OF ORIENTED PLASTICS TUBES

摘要

PCT No. PCT/AU96/00514 Sec. 371 Date Apr. 29, 1998 Sec. 102(e) Date Apr. 29, 1998 PCT Filed Aug. 16, 1996 PCT Pub. No. WO97/06940 PCT Pub. Date Feb. 27, 1997A method of expanding a tube of plastics material in which a longitudinally travelling tube is progressively diametrically expanded in internal fluid pressure in an expansion zone between an upstream plug and an expandable downstream plug. Expansion of the tube is controlled in response to parameters which directly or indirectly indicate variation in the relative velocity at which material is delivered to and removed from the expansion zone, such as detecting upstream velocity, early expansion diameter, axial force on a sizing device or the tube diameter just before the expansion zone.