GB1327202A - Moulded plastics fastener elements - Google Patents

Abstract

1327202 Moulding plastic substances NEWEY GOODMAN Ltd 4 Dec 1970 [9 Dec 1969] 59964/69 Heading B5A [Also in Division E2] A strip of fastener elements, e.g. studs or sockets, is injection moulded from thermoplastic material and at least two adjacent elements of the strip formed in separate successive moulding operations are connected together by moulding a part of one element when in a fused condition on to a part of the other element. The strip of studs may be as shown in Fig. 2 comprising studs 3 joined together by integral web portions 5 and the strip of sockets may be as in Fig. 4 with sockets 4 similarly joined by integral webs. Each web includes a boss 13 on its rear face. Adjoining mouldings of each strip are connected together by moulding tag portions 14, 15 on to one another, one tag 14 including a cylindrical boss 16 with a hole 17 and a U-shaped slot into which the other tag 15 keys. A strip of studs and a strip of sockets are simultaneously formed in an injection moulding apparatus comprising fixed and movable die tools 20, 21 respectively together defining two parallel mould cavities 22, 23, one for each strip, an injection nozzle 24 and two similar endless steel carrier bands 27, 28 extending through the cavities and provided with holes 31 to form the bosses 13. The bands engage the sprockets 34, 35, Fig. 6 with pins engaging the band holes, and the sprockets 35 are driven intermittently by a piston and rack mechanism 42, 41 so that each band is moved a distance slightly less than the length of the mould cavities. The mould cavity 23 is in part determined by the band 28, the shaped ends of parts 56 core sleeves 51 and core pins 49; the cavity 22 is similarly determined by the band 27, the part 55, core sleeves 50 and core pins 48. The pins 48, 49 are carried by a plate 45, Fig. 8, the sleeves 50 by a plate 47, and the sleeves 51 by a plate 44; the pins and sleeves are movable relative to one another at different stages in the movement of the die tool 21. The reduced diameter ends of the pins provide holes 10 in the moulded strips. Ejector pins 57 and a control rod 58 which is notched at 59 to engage the sprue are carried by a plate 46. When closed together the mould tools are connected by latches 61, 61<SP>1</SP>, Fig. 10, pivoted to the tool 20 which engage projections 62 on members 63, 63<SP>1</SP> rigidly connected to plates 44, 45. The latches 61 engage just before latches 61<SP>1</SP> and disengagement is in the reverse order. On mould closure a nose part 67, Fig. 9 on the die tool 21 forces a slide 69 on the die tool 20 upwardly causing a block 72 to slide laterally and to force core pins 73 with reduced diameter ends into holes in the two carrier bands to define the holes 17 in the trailing tag portions 14 of the moulded strips. Lateral movement of the block 72 forces a detent 76 downwards to engage a notch 77 in the nose part 67. After an injection stage the die tool 21 is retracted and the moulded strips are held against their carrier bands by core pins 48, 49 whilst the parts 55, sleeves 50 and the rod 58 retract, causing the sprue to detach from the mouldings. The latches 611 are freed before latches 61 allowing plate 44 and its sleeves 51 to move back before the plate 45 and its pins 48, 49. Eventually an ejector shaft 60 meets a stop to prevent further retraction of the plate 46 and its pins 57 and rod 58 whereby the sprue is stripped from the movable die and falls away. The carrier bands with the moulded strips attached are then driven upwardly so that the tags 14 are retained in the mould cavities when the die tools are closed. The strips are removed from the bands by a stripper 80 Fig. 8 and fed around rollers 81, 82, Fig. 6 to a fault detecting means 83 which operates an alarm when appropriate, whereupon an operator may remove a defective element and manually heat seal the strip ends. A counter 85, a cutter 86 and windup spools 87 are provided.