GB598555A - Improvements relating to injection or like moulding or die-casting machines - Google Patents

Abstract

598,555. Injection-moulding machines. E.M.B. Co., Ltd., and SMITH, S. Feb. 13, 1945, No. 3606. [Class 87 (ii)] [Also in Groups XXII and XXIX] The operator starts the machine and the following cycle of operations occurs automatically: (1) The slidable die-holder is advanced into engagement with the stationary die-holder by pneumatically-operated means at a speed which is controlled by a hydraulic device. (2) A pneumatically-operated intensifier then exerts pressure through the medium of a liquid on the slidable die-holder to lock it in the moulding position. Simultaneously (3) pneumaticallyoperated means move the injection plunger in the mould-filling direction at a speed which is controlled by a hydraulic device. (4) After a predetermined time interval, the parts return to their initial positions. Another cycle may start automatically. Compressed air from reservoir 83 stands in pipes 84, 85, 89. The attendant momentarily, presses plunger 106 to open valve 99, whereupon air pressure flows through pipe 102 and pushes to the right piston 117 thus allowing valve 109 to be opened. Air pressure through 108, 109, 112 then raises piston 19 to raise cam bar 27. This cam bar has a slot 26 which embraces a stop bar 25. The cam bar rises until its slot abuts the stop bar, and in so doing opens valve 29 to allow air through 34, 29, 35 to open valve 45. Air through 48, 45, 51 then pushes joined pistons r, s, to the right to advance die-holder b towards die-holder a. Oil trapped between these two pistons is thus transferred from cylinder t through conduit 7 to cylinder u, and the speed of the die-holder b is regulated hydraulically by the rate of this transference. As the mould support b completes its rightward movement, a part 25<1> on the stop bar allows the cam bar to rise a little further, this additional movement opening a valve 31 to apply an intensifying pressure to the mould support b and effect injection of material into the mould. When valve 31 opens, air through 38, 31, 39 opens valve 56 and air through 59, 56, 60 pushes piston 64 to the right, whereby piston rod 66 pushes oil through conduit 65 into cylinder u to apply the intensifying pressure to hold the die-holders together. Also, when valve 31 opens, air passes through 38, 31, 39 to urge leftward piston 70, thus opening valve 75 and allowing air through 81, 75, 82 to push leftward piston h, whereby plunger d injects material into the mould. The movement of plunger h is controlled by oil in chamber k passing through a port p in a piston j and a port n into oil reservoir o, h and j being fast on rod g. Return of piston 117 is delayed by a dashpot arrangement 123. If the machine is to perform automatically a series of cycles in succession, a projection 130 on the plunger 106 is turned down to be engaged by a lever 131 when a projection 132 on the returning stop bar 25 rocks the lever clockwise. If the machine is to be worked by hand, the valve 86 is closed and the cam bar 17 is moved by manual rotation of a pinion 23 which engages a rack 22 formed on the cam bar. The valves z, x, y are opened by springs 6 and closed by cams 4 on a shaft 5 rotated by a pinion 15 engaged by a rack 16 on the cam bar. To stop the mould support b in an emergency, a hand lever 13 is moved to rock a shaft 12, thereby removing the thrust on valve rods 2, whereupon valves x, y close and oil cannot pass between cylinder t and cylinder u. To stop the die-holder b in its forward movement and return it to its initial position, plunger 124 is moved by hand to open valve 109. To prevent damage to the machine if it is started before the mould parts c have been placed in position, a projection 138 is provided on the stop bar to close a valve 133. Specifications 532,495 and 536,568 are referred to.