GB1109285A - Improvements in the moulding from synthetic plastics material of a hollow article having an internal groove - Google Patents

Abstract

1,109,285. Moulding internal grooves in pipes. PLAST-INDUSTRIE S.A. 16 July, 1965 [12 March, 1965], No. 30399/65. Heading B5A. [Also in Division F2] A synthetic plastics hollow article 23, e.g. a P.V.C. pipe coupling, is provided with an internal circumferential groove, e.g. for a sealing device, which is cast into the article by including in the mould (10, 11, 12) (Fig. 1, not shown), a core 13 on which is slidably mounted a flexible or fracturable ring 14, e.g. of acetal or polyamide resin, whereby the core is slidably extracted from the moulded article prior to removal of the ring 14 from the article by inserting a screw into a blind tapped hole (16) thereof and either deforming the ring, if flexible, or applying traction (Fig. 7, not shown) to break the ring at fracture initiators provided by recesses (18) (Figs. 2 and 3, not shown) extending from the tapped hole (16) to adjacent the lateral sides (19, 20) of the ring or by recesses (21) (Fig. 4, not shown) adjacent the tapped hole (22). The insert 14 may be of square, rectangular or trapezoidal section and may form stepped bores or grooves (31, 32) (Fig. 8, not shown).