Patent GB-979301-A (GB)
Title: Injection moulding machine
IPC: B29C45/70
Filed: 1961-04-27
Abstract: 979,301. Injection moulding machines. FMC CORPORATION. April 27, 1961 [May 3, 1960], No. 15194/61. Heading B5A. An injection moulding machine comprises a pair of co-operating mould sections, which, when closed together, define a moulding cavity, the closed sections being movable together to effect injection into the cavity of a predetermined volume of plastics material by means of a tubular piston connected to one mould section. A female mould section 50, Figs. 3, 4, has a recess 56 and is fixed to a frame 46 slidable in guides 48 on the base of the machine. A tubular piston 54 is fixed to the female mould section 50 and is slidable in a cylindrical chamber 62 of a housing 18 secured to the base of the machine. A male mould section 52 is fitted with a projection 52a to co-operate with the recess 56 and is reciprocable in the frame 46 by the use of an hydraulic cylinder 16 and the toggle lever system shown. A number, e.g. eight, of the units shown in Figs. 3, 4 are provided side by side in the machine and are fed with plastics material under a pressure, e.g. 500 p.s.i., which is not large enough to force it through the small orifice 58 leading into the recess 56, from a manifold 20 connected to a conventional hydraulic ram and cylinder unit (not shown). The material is forced into the chambers 62 through non-return valves 66. In operation, each hydraulic cylinder 16 is supplied with fluid under pressure through a conduit 34 which the piston-rod 74 and the toggle lever system from the position where the levers 78, 79 are in mutual coincidence, through the position shown in Fig. 3 to that shown in Fig. 4, where the mould sections 50, 52 are closed together and the end 74a of the rod 74, which is screw-threadedly adjustable and lockable by a nut 74b, abuts the male mould section 52. Further movement of the piston-rod 74 pushes the closed mould sections, the frame 46 and the tubular piston 54 to the left in Fig. 4 so that plastics material is forced into the mould cavity. Adjustable stops 102, 110 limit the extent of travel of the frame 46 and thus control the quantity of material injected and the density of the moulded article. The mould is opened by supply of fluid under a lower pressure than that in the conduit 34 to a conduit 36, the mould parts moving together until the stop 110 abuts a plate 112 when the toggle lever system is moved back through the position shown in Fig. 3 to open the mould. In the embodiment shown in Fig. 7, the manifold 20, chamber 163 and tubular piston 166 are heated, eg. by steam supplied to passages 177, 178, the mould sections 137, 146 are cooled, e.g. by water supplied to spaces 143, 144 respectively, an ejector ring 152 is provided and a different toggle system is used to close the mould sections. Toggle levers 191, 193 are pivotally connected to a pusher block 188 fixed to an hydraulic piston-rod 185. Rollers 198, 206 fixed to the levers 191, 193 move in cam tracks 219, 221, respectively, secured to a box frame 126 having an end plate 127, to which the female mould section 137 is fixed and an intermediate plate 129, to which the male mould section 146 is fixed, the box frame 126 being slidable on the machine frame and the plate 129 being movable in the box frame. Movement of the piston-rod 185 to the left in Fig. 7 first moves the toggle levers from the dotted line positions to the full line positions to close the mould sections through the use of arms 199, 207 connected to the plate 129. The mould sections then move together with the box frame 126 and tubular piston 166 to inject material into the moulding cavity. As the mould sections are opened, tongues 201, 208 integral with the arms 199, 207 respectively, abut the ends of rods 156 slidable in the mould section 146 and fixed to the ejector ring 152. The ring 152 thus pushes the moulded article off the male mould section so that it drops through a shoot 224 to a conveyer (not shown).