Improvements in Apparatus for Applying Mouldable Stiffening Material to Shoe Parts

Abstract

1,165,814. Injection moulding footwear. COMPO SHOE MACHINERY CORP. 14 April, 1967 [25 May, 1966], No. 17133/67. Heading B5A. A mouldable stiffening material, e.g. PVC is applied to a shoe part 10 clamped between mould parts 20, 22, by injecting the material into a cavity C formed by a recess 48 in the face of the mould part 20, through an injection nozzle 60 having a tapered end portion 62 adapted to engage a tapered opening 50 in the mould part 20. The upper mould part 22 is moved by an hydraulic motor 54 downwardly to engage a lower plate 20, the two plates then moving downwardly together against the action of springs 42 until the injection nozzle 60 is contacted. Injection takes place and is terminated when pressure in the cavity C reaches a predetermined value detected by a pressuresensitive plunger 88 actuating a switch 96 on the mould part 22 (Fig. 7). Actuation of the switch 96 charges an hydraulic cylinder 86 to raise a valve rod 84 so that a conical upper end thereof closes the conical opening of the nozzle 60 to terminate injection. An electric control circuit, Fig. 4 (not shown), includes a timer which allows a predetermined time to elapse after injection before the motor 54 raises the mould part 22 and the part 20 is raised by springs 42 away from the injection nozzle. Running out of the timer also retracts a ram (80) actuated by a horizontal cylinder (78), Fig. 6 (not shown), and causes moulding material held in a reservoir 64 to be drawn therefrom past ball check valves (74), (76) to the forward side of the ram (80) ready for the next injection stroke. A platen 40 supporting the mould part 20 is heated by elements (r1), (r2), Fig. 4, and a beam 38 supporting the platen (40) is adjustable vertically on a machine frame 24. The polyvinyl chloride contains either homopolymer or copolymer groups and is suspended in a plasticizer with stabilizers and colouring agents, and the plasticizer may be modified by organic solvents. Organisols and plastisols may be used as the polymer carrier.

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