Patent GB-789220-A (GB)
Title: Improvements in or relating to moulding apparatus
IPC: B29C45/03
Filed: 1954-05-07
Abstract: 789,220. Injection-moulding machines. SIEGRIST, J. C., and CEPPI, G. Aug. 5, 1955 [May 7, 1954], No. 13447/54. Class 87(2). The nozzle 19, Fig. 2, has an injection passage 20 which is closed when an axially-movable needle valve 38 is in the lowered position shown. The valve is raised, to allow injection to take place, by air or oil pressure passing through a pipe (not shown), valve 47, Fig. 1, and pipes 46, this air &c. pressure depressing pistons 44 and rods 42 and rocking levers 41 about pivots 41a to raise a bar 39 off the valve, thus allowing the valve to rise under the pressure of the material in the nozzle 19 : alternatively the bar and nozzle may be fixed together. The bar 39 is disposed within a slot 18 in the injection cylinder. The air pressure supply through pipes 46, to open the valve may be controlled manually, by means of manually-operated valves 119, Fig. 1, or automatically by the attainment of a predetermined pressure above the hydraulic or pneumatic piston 26 that moves the injection plunger 23 : when the pressure in cylinder 27, Fig. 6, above piston 26 reaches a certain value a plunger 49 slidable in the upper end of cylinder 27 rises, against adjustable spring pressure 53, to operate a solenoid which opens valve 47 and admits air pressure to pipes 46. If, due to opening of the injection nozzle, pressure above piston 26 falls momentarily, springs 53 depress plunger 49 to compensate for the loss. After injection the solenoid is operated by a pushbutton to close valve 47 and hence valve 38. The injection cylinder 7 is secured to a stationary platen 3, and the mould A is pushed up against the nozzle by hydraulic apparatus 6. The mould is pushed up against a plate 33, Fig. 2, adjustably secured to a sleeve 8 within which the injection cylinder is disposed, and the degree to which the mould is allowed to rise is determined by the adjustment of the plate on the sleeve. The hydraulic apparatus 6 comprises, Fig. 1, two cylinders 85, 86 secured to opposite sides of a fixed support 87. The lower cylinder 85 has a piston 88 connected by rod 89 to a piston 90 in upper cylinder 86, piston 90 being secured to the mould-supporting table 4. The pistons are raised by oil supplies 92, 93 and lowered by 97 : or valve 94 may be closed, supply 92 only being operative ; or the pipe connections may be so arranged that either cylinder may be operated independently of the other, thus permitting raising of the mould under different pressures. The injection cylinder has a sleeve lining 11, Fig. 2, removably held in place by a bolt 14, Fig. 3, the lower end of the lining being a solid member having outlet passages 15 which register with passages 16 in a block 17 fixed to the lower part of the injection cylinder. Material is fed from hopper 12, Fig. 3, to the injection cylinder by an intermittentlyrotated screw 73. Between the hopper and the screw cylinder is disposed a reciprocatory slide 58 having a dosing chamber 59 the capacity of which can be altered by adjustment of a plate 60, Fig. 4. The slide is moved by air pressure from pipe 68, Figs. 1 and 2, via piston 65 and rod 66. The screw and slide are moved only when the injection plunger is in its raised position, in which position a contact 78, Fig. 1, on piston rod 25 operates (a) a valve 69 to provide air pressure through 68 and (b) a switch 77 to start motor 76 to turn the screw. The hopper 12 may be hermetically closed, electrically heated and connected to a vacuum pump, whereby the material (e.g., nylon) may be dried, and may have two compartments usable alternately. Each mould is slid onto table 4, from the left or the right, along guide 117 or 118. Safety device. The mould is correctly positioned on the table by stops 98, 99 which are slidable across table 4 to the correct mouldlocating position shown in Fig. 5, in which position a ramp 104 on each stop has cammed upwardly a roller 105 and slide 107 to lift a pin 109, thus opening valve 110 to allow air pressure to pass through pipes 111, 114, Fig. 1, to push back stops 113, 116 which, in the position shown in Fig. 1, prevent movement of handles 96, 31 to operate valves 95, 30 which control mouldraising and injection : if the stops 98, 99 are not in the correct position the handles 96, 31 cannot be moved. Mould-opening and -discharging. A filled mould is slid rightward, Fig. 1, along guide 118 onto a table 121 where it is positioned by stops 147, 148. A hydraulically-operated crosshead 126 is then lowered by operating valve 142, and a crank handle 133 is manually rotated to cause a cam 132 to pivot arms 127, 128 about their fulcra 129, whereby the lower ends of the arms enter slots in the upper part 134 of the two-part mould 134-134a as shown. Valve 142 is then reversed to raise the crosshead, the upper mould part being lifted off the lower mould part (which is held down by the stops 147, 148) by the arms 127, 128. As the upper mould part rises, carrying the moulded article, pins 145 on a fixed plate 144 eject the article from the mould part. The article may be a sliding clasp fastener, for which purpose clamps 153, 155 are provided to tension the tape 154 in the mould before the latter is slid back onto table 4. Two such mould-opening devices may be disposed on each side of table 4, a Y-shaped slideway being used to feed moulds selectively to the table. Specification 605,708 is referred to.