GB598078A - Improvements relating to moulding and die casting machines - Google Patents

Abstract

598,078. Injection and other moulding machines. E.M.B. CO., Ltd., CADBURY, G. N., and SMITH, S. June 26, 1945, No. 16320. [Class 87 (ii)] [Also in Groups XXII and XXVIII] Relates to a machine of the kind comprising fixed and slidable heads carrying complementary mould parts, pneumatic or hydraulic means for operating the various parts of the machine, and valves for controlling the said means. According to the invention, means for controlling the machine comprises the combination of a fluidoperated motor for actuating the valves of the machine, valves for controlling the motor, means adapted to be operated by a moving part of the machine for actuating the motorcontrolling valves, and a timing mechanism or mechanisms for causing the machine to dwell for a predetermined time in one or more stages of its action. The form shown is applicable to an injection-moulding machine in which the slidable head 11, when brought to the mouldclosing position, dwells there for the injection and setting- periods. The cam-shaft a which actuates the valves for controlling the various parts of the machine, and which is normally operated through a clutch by a hand lever b, is in the present instance operated by a pneumatic motor c under the control of a dash-pot i. The machine is started by turning counterclockwise a spindle 3 manually by means of a handle 4. The following operations then occur automatically :-(1) Valves n, o, are opened to admit compressed air from supply 2. through pipes s, t, to the left-hand side of motor c, whereby, by means of rack f and pinion h, shaft a is turned counterclockwise to operate valves which move head 11 to mould-closing position and cause injection of material into the mould. Simultaneously (a) air from supply 2 through pipe 40, valves 29, 30, and pipe 41 depresses catch 37 into a recess 38 in shaft a, and (b) injection timing device 12 is actuated, piston 16 being moved quickly to the left against spring 18. A piston 17, working in dash-pot cylinder 15, follows up piston 16 slowly under pressure of spring 19. The duration of this slow movement, which is controlled by the setting of a valve 23, determines the duration of the injection period. (2) As piston 17 reaches the end of its traverse, it moves lever 25 to operate valves 27, 28 to admit air to cylinder 9, whereupon piston 7 turns spindle 3 to its original position, as shown. This has two effects :-(a) Air is admitted to the right-hand side of motor c and tends to turn shaft a clockwise, but this clockwise movement is limited by catch 37 and recess 38 to an amount sufficient to terminate injection of material into the mould. The mould remains closed. (b) Air is admitted to timing device 13, which is similar to device 12 and determines the period of setting of the material in the mould. (3) As device 13 terminates its movement it operates valves 29, 30, to release catch 37, which is then raised from recess 38 by its spring. Motor c then turns shaft a to open the mould. Member 11 then returns, strikes lever 6, thus turning spindle 3, and another cycle commences. The machine is stopped by sliding lever 6 along spindle 3 away from member 11.