Blow moulding for a rubble chute segment - uses a prepared blank with an inner relief contour within a mould.

摘要

The blow moulding action, to form inner contours in hollow bodies of malleable plastics material, uses a hose-shaped blank with a relief inner contour with a smaller cross section than the final hollow body and with a wall thickness and inner contour thickness greater than in the final body. The softened blank is placed in one of the outer moulds and closed at both sides. The interior of the blank is subjected to a gas overpressure until the outer surface of the blank rests against the surface of the mould and the blank is cut at both ends. Also claimed is an appts. with a build-up head (1) with a jet prong (3) moving axially through a jet ring (2). The jet prong (3) has a radially expanded section, where its outer cross section contour matches the cross section of the relief inner contour. USE/ADVANTAGE - The blow moulding action is the prodn. of plastics hollow bodies with a structured inner contour, such as for chute segments to carry building rubble. The method gives hollow plastics bodies with high mechanical strength and resistant to wear from the coarse material in contact with it.