METHOD FOR PREPARING SYNTHETIC RESIN SPIRAL PIPE AND BENDING MOLDING APPARATUS USED THEREIN

摘要

PURPOSE:To efficiently prepare a synthetic resin spiral pipe of high accuracy by bending a strip of synthetic resin material in a semi-molten state continuously in a longitudinal direction with a definite curving degree before spirally winding a molding rotary shaft and cooling said resin material to temp. slightly lower than the softening temp. thereof. CONSTITUTION:A strip of synthetic resin material A1 in a semi-molten state supplied to the molding surface 7 of a molding plate 5 is molded into a ridge material A2 having a U-shaped cross-section provided with horizontal edge parts a1, a2 formed by the sliding with a step peripheral part 15 to be held to this shape while the ridge material A2 is passed through a water tank 13 while slid with the molding surface 7 to reach a control plate 9. During this time, the ridge material A2 is cooled to temp. slightly lower than the softening temp. of the resin thereof by the cooling water in the water tank 13 and formed into a state curved in the longitudinal direction along the molding surface 7 while the shape thereof is held. The ridge material A2 is further curved during the passage along the curved surface 10 of the control plate 9 and accurately adjusted to definite temp. slightly lower than the softening temp. by a heating mechanism 12 to be spirally wound around a molding rotary shaft 1.