GB1258605A - - Google Patents

Abstract

1,258,605. Moulding pipe grooves. INDUSTRIFLE ONDERNEMING WAVIN N.V. 30 Sept., 1969 [3 Oct., 1968], No. 47888/69. Heading B5A. [Also in Division F2] In apparatus for forming an internal groove 18 in the socket end of a thermoplastic pipe 1, e.g. of polyvinylchloride or polyethylene without thinning of the pipe wall, the heated tube 1 is mounted on a mandril comprising a fixed part 2 and an axially movable part 3, the tube is clamped to each mandril part 2 and 3 by radial displacement of respective pairs of mould parts 7 and 8, and the mandrel part 3 is then axially displaced towards the part 2 simultaneously with the mould parts 7 until the latter are in abutment with the mould parts 8, and pressure is applied by the mandril internally of the tube to define the internal groove by deforming the length of tube 18 originally extending between the separated mould parts into contact with an annular recess 16 defined by the mould parts 7 and 8. The mandril parts may be heated prior to locating the tube thereon. Each pair of the jaws 7 or 8 is joined to its respective mandril part 3 or 2 for the radial movement with respect thereto, actuated by a pair of double-acting pneumatic cylinder piston arrangements 11, 10, which act on the jaws 8 and the movement whereof is simultaneously transmitted to the jaws 7 by bolts 15, which are fixed to the jaws 7 and extend through the jaws 8 and radial guide slits 13<SP>1</SP> of a plate, or struts, 13 fixed to a shaft 4, connecting the mandril part 3 to a pneumatic piston cylinder arrangement whereby it is axially displaced with respect to the mandril part 2. In the Figs. 1 and 2 embodiment, the pressure is applied internally of the tube by compressed air supplied through passages 17, 5 in the shaft 4, but, Figs. 3 and 4 (not shown), this may alternatively be applied by a rubber ring, which may be air filled and located between the mandril parts and outwardly deformed upon compression therebetween, or by a rubber ring inflated upon admitting air thereto, or by employing a mandril ring, the parts whereof are expanded on introducing a conical member axially thereinto. The tube 1 may be loaded and unloaded from the mandril by an hydraulic device (not shown) acting on the tube or mandril, and the pipe 1 may be located on the mandril in abutment with a flange extending from the part 2.