Patent GB-1140034-A (GB)
Title: An improved method of forming articles from thermoelastically deformable materials
Inventor: WEBER EUGEN
IPC: B29C43/36
Filed: 1965-02-22
Abstract: 1,140,034. Injection moulding. H. D. WRIGHT, and R. E. LECLERC. 2 Feb., 1966 [22 Feb., 1965], No. 7666/65. Heading B5A. A slug of thermoelastically deformable material is forced under pressure into a mould cavity through a gap subtending an angle of 360 degrees at the axis of the mould cavity. In one example (Fig. 2) a slug 23 is first injected into a chamber 24 by a nozzle 27. By moving a slide 28 so that holes 30 therein are aligned with the chamber 24, a ram 31 can be moved downwardly to force the slug 23 through an annular gap 32 into a mould cavity 10 between an outer mould part 11 and an inner core 12. Biaxial orientation is established in the material by making the ratio of the cross-sectional area of the slug 23 to the area of the base of the cup at the point 33 approximately 1:4, but for certain materials a ratio as high as 1: 2 may be sufficient. After injection the core 12 and cup are moved downwards. When the core is clear of the mould 11 a block 18 is arrested and strips the cup from the core 12. A cooling system for the core includes an inlet 15, outlet 16 and partition 17. A water jacket 20 cools the mould part 11. Figs. 5 to 8 (not shown) illustrate a similar embodiment but the moulded container is a deep rectangular box and the injection ram (31) is of rectangular section and moves upwards to effect injection. The injected material flows up the surface of the core but does not enter indentations (47) in the outer mould part. When injection is complete four L-shaped cutters (41) are advanced simultaneously to sever excess material (48), Fig. 8 (not shown), and to cause the cut edge to form a seal against the surface of the core. Air under pressure is now introduced through ducts (34, 35) in the core to expand the material into the indentations (47). The cutters (41) are obliquely slotted at (42), Fig. 6 (not shown), to fit over flat-sided guide pins (43). Fig. 9 shows a machine for forming a tapered cup with a rolled-over rim. When the injected material reaches an annular recess formed by mating grooves (51, 52), Fig. 10 (not shown), in a ring 50 and flange 12a, respectively, air under pressure admitted through an inlet 56 and an annular duct 54 and nozzle 55 forces the material to form into a rolled lip 66. After injection the core is separated axially from the outer mould 11 and air pressure supplied at 65 acts through a groove 62 to move a conical headed stripper rod 57 downwardly (Fig. 10, not shown). In the example shown in Fig. 11 the material is forced through a short narrow section 10 and is guided over the surface of the core 12 by an annular curtain of air or other fluid discharging from an upwardly inclined annular port 70 (see Fig. 12, not shown). The port 70 is supplied with fluid through ducts 34, 35, the fluid escaping from the mould through grooves 74. When the free edge of the injected material reaches a point 75 beyond a groove 76 it is clamped, e.g. by mechanism similar to the cutters (41), Figs. 5, 6, 8 (not shown). Air under pressure dilates the material against the internal walls of the mould part 40 but the wall thickness remains constant due to continuing supply through the cavity 10. Figs. 13, 14 (not shown) show a machine for making a long tube having a threaded nozzle. The injection ram (31) works in a bore (80) in the core (12). The threaded nozzle is formed in a section (83) in the form of a gear-wheel which is rotated by a rack (84) during initial withdrawal of the core (12). Operation of injection ram.-This may be mechanical, electrical or hydraulic but alternatively the ram may be constituted by an idle washer or gasket forming a gas-tight seal and actuated by igniting a propellant in a closed chamber.