Patent GB-849351-A (GB)
Title: Improvements in or relating to injection moulding processes
Inventor: POLLARD HAROLD JOHN
IPC: B29C45/46
Filed: 1955-10-25
Abstract: 849,351. Mixing fluids. BRISTOL AIRCRAFT Ltd. Oct. 22, 1956 [Oct. 25, 1955], No. 30532/55. Class 86 [Also in Group V] A method of injection-moulding synthetic resins comprises mixing two separate quantities of a liquid resin, one with a catalyst and the other with an accelerator, the ratio of the ingredients of each resin mixture being such that when the two resin mixtures are themselves mixed together in a pre-determined ratio they form a moulding mixture causing the two resin mixtures to flow together to form the moulding mixture and passing the moulding mixture into a mould. Two identical containers 1, 2 are joined at their tops by a conduit 3 leaving a branch 4 connected through a T part valve 5 to air supply piping 6, a branch 11 connected to a pressure gauge 12 and branches connected to the tops of level gauges 23, 24 for the containers 1, 2 respectively. Conduits 13, 14 form the bottoms of the containers 1, 2, are connected to a mixing chamber 15 and have connections to the bottom of the level gauges 23, 24 and container refilling three-way cocks 21, 22. The mixing chamber 15 has a glass inspection cover 16, coaxial plugs 19 virtually loaded by a spring 20, closing the entries to the conduits 13, 14, an inspection pipe 17 with a union fitting 18 arranged for attachment to the mould, and a flushing conduit 33 with valve 34, attached to a flushing container 26 having an air supply pipe 31 and valve 32 and a gravity supply container 25 with valve 27, vent 29 and union 30 arranged to connect to the union 18 of the inspection pipe 17. For drying the mould prior to moulding an air dryer 35, with a supply pipe 39 and valve 40 and regenerator 36, has a conduit 41 with union 42 for attachment to the mould. In operation. resin mixture supply pipes are attached to the cocks 21, 22 and with the valve 5 set to discharge to atmosphere the containers 1, 2 are filled, the cocks 21, 22 and the valve 5 are then closed. The union 42 is then connected to the mould and the mould and any fibrous reinforcements material therein are dried and the union 42 disconnected. The drying air may be warmed. The union 18 is then connected to the mould, cocks 21, 22 set, and the valve 5 set to admit air to the containers 1, 2 thus discharging the resin mixtures into the mixing chamber 15 where they mix into the moulding mixture and are discharged into the mould. The proportions of the moulding mixture, as indicated by the level gauges 23, 24, may be adjusted by the cocks 21, 22 or the resin mixtures may be differently coloured so that on mixing together in the chamber 15 a visual inspection of a predetermined colour of a moulding mixture may be made through the inspection cover 16. A gravity fed apparatus (Fig. 3, not shown) is described. The apparatus of Fig. 1 may be made automatic by the use of a timer device (not described) for operating the valves and cocks. After moulding the mixing chamber and injection conduit may be flushed by connecting the union 18 to the union 30 of the container 25, opening cocks 27, 34 thus allowing air to force cleaning solvent from the container 26 through conduits 34, 17 into the container 25. Specifications 790,639 and 849,352 are referred to.