GB1314451A - Injection moulding - Google Patents

Abstract

1314451 Punching injection moulded articles IMPERIAL CHEMICAL INDUSTRIES Ltd 3 May 1971 [6 May 1970] 21855/70 Heading B5A An injection moulded article having at least one orifice is made by a process in which after the mould cavity is filled and while the plastics material 7 is still molten a first tool 5 having the shape of the desired orifice is forced through the material in the cavity and at the same time a second tool 6 is retracted to form a recess into which the first tool 5 is forced and a plug 8 of material is severed from the material in the cavity and forced into the recess. The plug 8 is maintained in the severed position showh in Fig. 3 until at least the surface thereof and the surface of the material surrounding the orifice have solidified. The tools may then be restored to their original positions, and when the material has completely solidified, the moulded article is removed from the cavity and the plug 8 removed by hand. Alternatively the mould component 1 and tool 6 may be retained in position and the mould component 2 and tool 5 retracted. Fig. 6 shows a modification in which tools 5, 6 with chamfered ends are forced towards each other to form a thinner plug 8 before being moved to the position seen in Fig. 7 (not shown) corresponding to Fig. 3. This arrangement is particularly suitable for articles having a foamed core and unfoamed skin. In a further modification (Fig. 9) each tool 5, 6 has a sleeve 13, 14 slidable thereon. The sleeves and tools are first moved together (Fig. 8, not shown) to compress and fuse together opposed portions of the surface layers 10, 11. The tools 5, 6 are then moved to the position seen in Fig. 9 to sever a plug 16 from layer 15. In Fig. 10 each tool 5, 6 is a ring or sleeve with a further sleeve 13, 14 thereon. Reference has been directed by the Comptroller to Specification 1,247,400.