Patent GB-995249-A (GB)
Title: Improved method of and apparatus for making plastics articles
IPC: B29C48/09
Filed: 1961-09-22
Abstract: 995,249. Blow-moulding. OWENS ILLINOIS GLASS CO. Sept. 22, 1961 [Sept. 23, 1960 (2)], No. 33952/61. Heading B5A. Hollow plastics articles having a non-blow moulded portion integral with a blow moulded portion are formed by initially injecting or extruding plastics into a mould to chill the exterior surface through the interior of which axial extrusion is continued to form a tubular extension which is blow moulded. Polyethylene is extruded from plasticizer 20, Fig. 1, through vertical annular passage 22, into a small cavity formed by the extension of mandrel 25 beyond horizontal end face 28 of extrusion block 23 surrounded by neck mould sections 55 (which may be fluid cooled), horizontally slidable against compression springs 58 within integral extensions of blow mould sections 40, and closed by closure plate 60 having annular retaining grooves 62 which may be undercut. When a solidified thin exterior skin has formed, the mould is opened by downward movement of plate 60, which retains the tubular extrusion resulting from the simultaneous descent of annular piston sleeve 32. Blow mould sections 40 (Fig. 4) then close around tube 66 which is pinched shut at 69 and blow air, introduced through mandrel passage 26, inflates the tube. In a further embodiment (Fig. 7) the mandrel 104 is retractable to assist withdrawal of the moulded article and the neck moulds 112 are integral with blow moulds 110 and tube pinching plates 115 are provided together with filler plates 121 similarly movable to cut off further extrusion. After solidification, mandrel 104 and filler plates 121 are retracted to allow a severing knife to operate, aligned with the lower extremities of plates 121. Alternatively, moulds 110 may blow mould at a remote station by insertion of a blow head or the extrusion may be pre-expanded by the method of Specification 935,183. Wall thickness can be controlled by varying the speed of descent of plate 130 and by pre-expansion. The invention is applicable to the formation of a plurality of articles from each of a number of extruded tubes (Figs. 11 and 16) formed simultaneously from five orifice blocks 220. Each block is supplied with plastic from a common feed tube 235 through a regulating valve 241 and via passages 239 upwardly through annular passage 233 into a mould cavity above orifice 250, comprising upper and lower sections. The lower mould section comprises orifice sized head 253 of vertically reciprocable core pin 251 surrounded by lower mould sections 265 operable by cam projections 271. The upper mould section 280, comprising sprung and vertically slidable mandrel 296 surrounded by upper neck mould sections 300 retained within fixed guide casing 282, 284, 285 by horizontal guide surfaces 320 and upon cam dowels 315 anchored in slide block 286, is directly connected to lifting rod 289 and sprung against housing 285 upon guide pin 290. After the mould has been filled the extrusion is continued connected to the upper mould housing 285 as this is raised by rod 289 until guide block 282 abuts a stop on guide 281 and extrusion is then interrupted by retraction of head 253 after which blow mould sections 330 close and the desired article is blown. Subsequently, the rod 289 continues vertical movement without housing 285 and cam dowels 315 accordingly open mould sections 300. Simultaneously, lower mould sections 265 are opened upon cams 271. Blowing air may be supplied through core pin 251 or mandrel 296. The blow mould sections 330, Fig. 16, may each define upper and lower mould cavities 333 and 334 respectively with pinching edges 339 joined by a central recessed portion 340. Alternatively (Fig. 17, not shown), a single unit may be blow moulded having non- blow moulded sections at either end and which may be medially severed with each open end subsequently sealed by heat or adhesive. Additionally, further chilling may be obtained within the bubble by circulating the blow air by means of dual passages within the core pin and mandrel. Specification 935,183 is referred to.