| 摘要 |
1,268,437. Injection moulding foam material. BRITISH UNITED SHOE MACHINERY CO. Ltd. 19 March, 1969 [20 March, 1968], No. 14402/69. Heading B5A. In an apparatus for injection moulding articles of foam material, fluid blowing agent is fed to the injection cylinder 3 at a rate dependent upon the rate at which moulding material is fed towards a nozzle 10 by a screw 6, and means 46, 55 are provided for varying the ratio of these two rates. Fluid blowing agent is contained in a cylinder 52 having a piston 50 operated by a piston 43 in a cylinder 40. Fluid under pressure is supplied to one side or the other or to neither side of piston 43 under control of a valve 30 having a slidable valve member 32. Valve 30 is secured to the rod 44 of piston 43 and valve member 32 is biased to the left by a spring 31. A member 46 pivoted at 55 has a head 47, and a lower end bale portion located in a bracket 70 fixedly connected to the screw 6. The screw 6 is rotated by an electric motor 22 and advanced axially by a fluid pressure cylinder 16. Cooling fluid is circulated through passages 82, 69 to cool the cylinder 3 and mould 67, 68 respectively. Operation.-When the screw 6 reaches its forward position the bracket 70 contacts a switch 58 which starts the motor 22 and operates a valve 60 to apply a small pressure from a line 63 to cylinder 16. As the screw 6 rotates it feeds material forwardly and is thereby moved rearwardly. The member 46 is thus moved anticlockwise so allowing the valve member 32 to move to the left to allow fluid under pressure to reach the right hand side of piston 43. The piston 50 is thus moved to the left and blowing agent supplied through a conduit 54 to the cylinder 3. Movement of rod 44 is faster than screw 6 so that the valve member 32 re-engages the head 47 and is returned to its neutral position. The ratio of the rates of feed of blowing agent and moulding material can be varied by moving the pivot 55 along a slot in member 46. When screw 6 reaches its rearmost position a switch 62 operates the valve 60 to apply high pressure to the drive piston 18 and to stop the motor 22. On completion of injection the mould members 67, 68 are separated slightly to enlarge the mould cavity. |
