Patent GB-484244-A (GB)
Title: Improvements in and relating to die and pressure casting machines
IPC: B29C45/70
Filed: 1937-02-23
Abstract: 484,244. Moulding thermoplastic materials by injection. ECKERT & ZIEGLER GES. Feb. 23, 1937, No. 5487. Convention date, March 23, 1936. [Class 87 (ii)] [Also in Group XXII] In a die or pressure casting-machine wherein the thermoplastic material to be cast is ejected under high pressure by a plunger from a cylinder through a nozzle into a mould composed of relatively movable halves the means for operating the movable half of the mould and the means for moving the plunger are operated by a common controlling spindle driven by a single motor or by a suitable belt or chain drive. The movable half mould 9 is carried by a transverse bar 10 actuated along guide rods 8 by a linkage 21-24 and movable transverse bar 26 sliding on lower guide rods 33 ; the other mould half 12 is carried by a transverse bar 11 having limited movement on the guide rods 8 between stops and springs 14 abutting a fixed transverse bar 5 carrying the cylinder 15, and the plunger 20 is carried by a transverse bar 19 actuated by another linkage 27-30 and movable transverse bar 32 connected with limited relative movement by pins 51 and springs 53 to another movable transverse bar 34. A bearing 39 fixed to the shaft 34 receives a collar 40 on the end of the screw-threaded controlling spindle 41 which engages a screw-threaded bore in the transverse bar 26 and has a plain extension 38 grooved at 44 to engage a key 43 on the pinion 42 driven by the motor 49. At the beginning of a casting operation the bar 34 is held by spring locking pins 59 against longitudinal movement that so the rotating spindle 41 at first moves the bar 26 to the left thereby advancing the half mould 9 into casting position against the half mould 12 ; thereupon projections 54 on the bar 26 engaging slots 55 in control rods 56 move the latter to the left causing wedges 57 to withdraw the locking pins 59 from the bar 34 so that the spindle 41 advances through the bar 26 and moves the associated bars 34, 32 to the right, thereby actuating the linkage 27-30 and the plunger 20 to effect the casting operation. On reversing the driving motor 49, the plunger 20 is first withdrawn by the movement of the bars 34, 32 to the left; then the bar 34 is locked by the action of pins 61 thereon on levers 63 engaging the control rods 56 of the locking pins 59 and finally the half mould 9 is retracted. The driving motor circuit includes a number of safety contacts. The contact A<1> actuated by a cam 73 on the transverse bar 26 interrupts the current supply to the motor 49 when this bar reaches the end of its return movement and a contact A<2> carried by the bar 32 is opened by the bar 34 at the end of the plunger stroke when the bar 34 approaches the bar 32. Another contact A<3> on one of the stop sleeves 37 is adapted to be opened by the bar 32 if owing to insufficient material in the plunger cylinder 15 the bars 34, 32 should reach their extreme right-hand position without the bar 34 approaching the bar 32. Another contact A' is opened by a cam 74 on the transverse bar 34 on each working stroke of the machine, but another contact AS previously closed by the transverse bar 26 maintains the current supply to the motor unless the movement of the bar 26 is impeded as by a foreign body between the die halves, in which case the machine will be stopped by reason of both contacts A<4> , A<5> being open.