GB584932A - Improved apparatus for the injection moulding of plastic materials - Google Patents

Abstract

584,932. Injection moulding m a c h i n e s. GENERAL MOTORS CORPORATION. April 24, 1944, No. 7558. Convention date, Aug. 19, 1943. [Class 87 (ii)] Between the mould cavity 36 and the nozzle 66 are disposed electric heaters 80, one group in each part 32, 34 of a split mould. Thermosetting resin passing through the cylinder 40 is plasticized by electric heating coils 48, is then heated to a point above the setting temperature by the heaters 80, and finally enters the mould cavity, where it is heated by steam coils. When the mould cavity has been filled, the current to heaters 80 is cut off. The spherical end 68 of the nozzle is clamped in a two-part socket 70. To prevent conduction of heat back along the nozzle into the cylinder, the blocks 74 containing the heaters 80 are embedded in insulating sheaths 78, the socket 70 is fluidcooled by ducts 71 and may be insulated, and the nozzle is cooled by a water coil. To facilitate removal of curved resin from the passage 76 between the blocks 74, the passage is tapered vertically. The mould shown is for making a steering wheel having an insert. The mould parts are held together by a hydraulic piston 26. The bottom.of the injection cylinder is cooled at 50. Resin is transferred from hopper 54 to the cylinder by a feed slide 60 reciprocating with the injection plunger 42. When a plug 90 is removed, the nozzle may be cleaned with a ram-rod.