GB1103242A - Injection valve pressure regulator - Google Patents

Abstract

1,103,242. Injection nozzles. INVENTIONS FINANCE CORPORATION. 3 May, 1965 [4 May, 1964], No. 18503/65. Heading B5A. An injection nozzle 1 with associated chambers 4, 6 and a valve 9 is substantially as described in Specification 1,010,008, but is provided with a fluid-pressure operated piston 21 which holds rod 19 and hence valve 9, via linkage 14, 16, against increasing back-pressure of moulding material in chamber 4 as the injection mould is filled, and thereby prevents premature closing of nozzle passageway 13. Hydraulic fluid is admitted to cylinder 23 via coupling 31 and duct 32 at a pressure greater than the maximum back-pressure, the throw of piston 21, and hence the size of passageway 13, being determined by a ring 28 screwed on to cylinder 23 and accurately positionable by means of vernier scale 30. Cylinder 23 is provided with a curved surface 24 so that it may rock on a support 25. As the filling of the mould is completed, pressure on piston 21 is automatically released by switch mechanism associated with an injection piston (not shown) within cylinder 8, see Specification 1,075,801, and valve 9 consequently moves to close passageway 13. When the injection mould is removed a further piston 20 attached to rod 19 and situated within cylinder 21 is moved relative thereto, Fig. 3 (not shown), by admitting hydraulic fluid via coupling (33) and duct (34) to chamber (35). This movement causes projection (36) of valve 9 to close nozzle orifice 3. Fluid pressure circuits are also described, Figs. 4-6 (not shown). The application of fluid via coupling (33) may be effected by actuation of contact switches when the mould and nozzle are separated or by the increase of pressure within the nozzle due to back pressure from the filled mould.