Patent GB-751314-A (GB)
Title: Apparatus for moulding plastic material and ejecting the moulded articles
IPC: B29C45/26
Filed: 1954-08-06
Abstract: 751,314. Injection-moulding brushes, &c. KUTIK, L. F. Aug. 6, 1954 [Aug. 26, 1953], No. 22857/54. Class, 87(2) In a mould wherein cavity-providing providing parts 24, 25 separate to allow ejection of the moulded article and ejector pins 42, 49 are reciprocable in the mould part 24, an ejector pin actuating mechanism thrusts out all the.ejector pins in the first part of the ejecting cycle and thrusts out the pins 49, which are distributed generally over the area of the mould cavity, at a different rate in a later part of the cycle. The machine described is adapted to the injection moulding of nail brushes. The backs of the brushes are moulded in the spaces formed by cavities 30, 31 in the mould parts. The bristles are moulded, integrally with the backs, in flutes in the sides of the pins 42, 49. The pins 42 are shorter than the pins 49 and are fixed to a plate 40 by a screwed-down plate 41, and pass through bores in the lower mould part 24. The longer pins 49 are fixed to a plate 46 by a screw-down plate 47 and pass through the plate 40 as well as the lower mould part 24. Plasticized plastic material is placed in a cavity 34 of a pot structure 35 carried by a crosshead 26, which also carries, underneath, the upper mould part 25. Pressure fluid is supplied to the underside of a ram 14 which rises and forces up a crosshead 17 on which is mounted a thrust plate 19 with a central boss 21 and two guide plates 22, one of which is shown, which support between them, at their upper ends, the lower mould part 24. This lower mould part is thrust strongly against the upper mould part and forces it upwards against springs 27, causing a plunger 36 to enter the cavity 34 and inject the plastic material into the mould cavities. The plate 40, carrying the pins 42, rests in the mould-closed position on the ends of thrust pins 93, which bear against the top, of the boss 21, and the tops of the pins 42 are then level with the upper surface of the lower mould part. The plate 46, carrying the pins 49, is also held in the position where the tops of these pins are level with the upper surface of the lower mould part because the heads of studs 52, depending from the plate 40, meet the ends of counterbores 56 in the plate 46. This relative position of the plates 40, 46 is ensured by pins 57 the tops of which meet the upper mould part 25 and the bottoms of which meet the plate 47 and which have shoulders 64 which meet the plate 41. After a suitable interval of time the apparatus automatically reverses the action of the ram 14 to retract the mould part 24 from the upper part 25. As the mould part 24 descends again;,the plate 40 meets the top ends of knockout pins 66 whose bottom ends, through adjusting studs 70, come to rest on a fixed lower head 11. The pins 42, 49 therefore cease to descend while the mould part 24 continues to do so, resulting in a stripping action of the bristles moulded in the flutes of the pins. On further descent, heads 80 on studs 79 which project from the thrust plate 19 press down the ends of levers 75 which are pivoted on supports depending from the plate 40 and cause the other ends of the levers to press the plate 46 upwards and thus to thrust the pins 49 outwards from the mould part 24 faster than the pins 42. Thus, at the end of the mould-opening movement, the bristles moulded in the flutes of the pins 42 are completely stripped and the only portion of the brush remaining adhered to a mould part are the bristles moulded in the flutes of the pins 49. The adhesion between all the moulded bristles and their pins would be too great for the moulding to be fired manually, but damage to the bristles might result if all were stripped mechanically, so the number of pins 49 is much less than the number of pins 42 and the operator is conveniently able to free the brushes whose bristles remain adhered only to the pins 49.