GB1319511A - Production of a continuous moulded plastics strip - Google Patents

Abstract

1319511 Moulding piled sheets SOC POUR LA RECHERCHE ET LE DEVELOPPEMENT TECHNOLOGIQUE SA 14 May 1970 [14 May 1969] 21764/70 Heading B5A An article comprising a base member from which other members project, for example a strip having hook shaped piles and suitable for use in a releasable fastening, is made by injetting plastics material into a series of mould cavities formed between relatively slidable plates in contacting surface-to-surface relationship, the mould cavities intersecting one edge of the plates and being defined by a recess in one plate and the oppositely located area of the adjacent contacting plate. Base material is extruded on to the moulding surface formed by the aligned edges of the plates after injection and when the materials have set alternate plates are slid relative to their neighbours so as to expose the recesses and the projections formed therein, thereby facilitating removal of the article from the moulds. In the particular embodiment, a strip of plastics having hooked projections on one surface is moulded by extruding material on to the surface of a suitably configured drum. The configured surface of the drum is made up from a circular array of eight sections A-H of plates, each set comprising interleaved mould plates 29 having cavities 33 and 34 and flat spacer plates 30. The mould plates are held in a fixed position upon the drum between side discs 27 by cross pins 31 which engage in correspondingly dimensioned apertures 32 in the mould plates and oversized apertures 59 in the spacer plates whilst the spacer plates are carried by means of cross-bars 69 from plates 60 slidable over the outside of side discs 27. The plates 60 are radially reciprocable by means of cam rollers 63 mounted at their radially inner ends and movable around a central cam surface 65, the rollers being biased into contact with the cam surface by hydraulic cylinders 71. The cross-bars 69 pass through exactly sized apertures 70 in each spacer plate and through oversized cavities 84 in each mould plate. In operation, as the drum revolves each set of plates is brought to the extrusion head 46 where the associated rollers engage part 79 of the cam surface to move the spacer plates to their outermost positions flush with the mould plates. A first charge of material is injected through outlet 37 into the mould cavities and a second charge, forming the supporting layer of the strip, is extruded on to the surface of the plates through outlet 38. Further rotation then brings the rollers into different regions of the cam surface where the spacer plates are first pulled inwardly to free the hooks for subsequent removal of the strip over rollers 85 and are then moved outwardly in readiness for passage past the extrusion head again.