Patent GB-828453-A (GB)
Title: Improvements in apparatus for making resin bonded mouldings
Inventor: POLLARD HAROLD JOHN
IPC: B29C39/00
Filed: 1956-11-16
Abstract: 828,453. Moulding resin-impregnated fibrous materials. BRISTOL AIRCRAFT Ltd. Nov. 11, 1957 [Nov. 16, 1956], No. 35134/56. Class 87(2). Apparatus for making a moulding by impregnating fibrous material with a setting liquid resin comprises an assessing device in a mould inlet or escape passage for the resin, responsive to a quantity related to the proportion of air in fluid leaving the mould through an escape passage during the last stages of filling the cavity with resin and arranged to close a shut off valve in an inlet or escape passage when the quantity passes a predetermined value. Resin in a container 8, Fig. 1, is maintained under pressure by compressed air supplied through a pipe 10 and regulating valve 11, and is admitted to a mould cavity 3 through a pipe 6 containing a shut off valve 7. The resin is allowed to run through the mould cavity to discharge through an outlet pipe 12 to a container 16 suspended from an arm 17. When an amount of resin (determined by experiment) has passed into the container 16 such that the resin in the pipe 12 is substantially free from air the arm 17 is actuated by the weight of the container 16 and contents to close a valve 14 in the pipe 12. Simultaneously an arm 22 moving with the arm 17 closes contacts 22 to complete the energizing circuit of the operating coil 19 of the inlet valve 7 to close the latter, and to operate a signalling device 23. One or more additional outlet pipes 12 may be provided each associated with a valve 14 and container 16, so that the valve 7 is not closed until all the contacts such as 21a associated with the additional valves 14 are closed. In a modified arrangement the resin is drawn by suction into the mould cavity through one or more inlet passage or passages from a container or containers each adapted to close an inlet valve when a predetermined amount has passed through the associated inlet passage. In another modification the container 16, Fig. 1, is replaced by a smaller container from which resin is allowed to overflow into a container not supported by the arm 17, the smaller container closing the valve 14 when filled with substantially airfree resin. In a further modification the container 16 is replaced by a tank containing a float which operates a switch to close an electromagnetic valve when a predetermined amount of resin is in the tank. In the alternative apparatus illustrated in Fig. 4 the mould cavity 3 communicates with two outlet pipes 60, 50a each containing an electrically operated shut-off valve 51 or 51a. Resin overflowing from the mould cavity through the pipe 50 passes through two glass walled chambers 60, 61, separated by a compartment containing a lamp 62 from which light may pass through the chambers 60, 61 into light sensitive cells 63, the electrical resistance of which decreases with the intensity of illumination. The cells 63 are connected in a bridge circuit with two resistances 66, 67, a relay 68 having an energizing winding 69 in series with an indicating device 70 being connected across one diagonal of the bridge and a source of power 59 across the other. The resistance 67 is adjusted to balance the bridge when the chambers 60, 61 are empty. Resin is drawn by suction through the chambers 60, 61 to a vacuum chamber 54 and when air-free resin fills the chamber 60 the resistance of the more strongly illuminated cell 63 falls below that of the cell 64 to unbalance the bridge circuit. The relay 68 is then energized to close the valve 51 and contacts 58 associated therewith. The closing of the valve 51a and of contacts 58a is similarly controlled. When both contacts 58 and 58a are closed the operating coil 19 of the inlet valve 7 is energized to close that valve. The apparatus may incorporate a rotary conveyer comprising a platform 74, Fig. 5, rotated about a vertical shaft 71 supporting a stationary platform 75 carrying the pressurised resin supply vessel 8 and an air drier 76. A sleeve 84 rotating with the platform 70 is provided with ports 85 at each of four locations around the sleeve and connected by pipes 89 to moulds 87 mounted on the platform 70. At the four stations (a) the assessing devices are placed on the platform 70, (b) the mould is connected to the air drier 12, (c) the mould is connected to the resin supply vessel, and (d) the mould is unloaded.