Patent GB-933609-A (GB)
Title: Method and apparatus for moulding articles from slugs of heat-curable material
IPC: B63B35/44
Filed: 1959-12-09
Abstract: 933,609. Continuous moulding of articles from rubber &c. slugs. DUNLOP RUBBER CO. Ltd., and A. P. GROVER. Dec. 9, 1959, No. 41872/59. Class 87(2). Articles are continuously moulded from slugs which are successively cut from the the end of a strand of moulding material, e.g. rubber, fed step-by-step, and are then conveyed one at a time to a loading station and positioned between moulding dies which are continuously advanced in pairs and separated at the loading station, each pair of dies being then partially closed to grip a slug and thereafter closed together as they continue to advance, so moulding the slug. The slug cutting and feeding operations are controlled by the successive engagement of cams 19, on the rim 18 of a rotary mould carrier 10, with four pilot valves 130, 131, 132, 133 on a bracket 134. The dies are actuated from a stationary cam track 15. When the pilot valve 130 is engaged by a cam 19 a control valve V1, Fig. 8, is operated to supply air pressure to a cylinder 96, Fig. 5, and to cause air pressure in a cylinder 36a to be exhausted. The piston 98 advances from the cylinder 96 and thereby advances a reciprocable plate 91 to which are pivoted the ends of actuator links 94, 95. These links move the actuator arms 79b, 88 of one-way clutches 78, 85 and cause drive to be imparted to feed rollers 76, 77 which combine to advance the strand S of moulding material, unwinding it from a flat coil on a rotary tray, (not shown). The retraction of a pusher pin 47, consequent on the exhaustion of the cylinder 36a, allows a spring to swing a finger 38 towards another finger 39, Fig. 7, till a pre-set gap separates the ends of the fingers, which gap is small enough to retain a slug K of material cradled between them. When the next pilot valve 131 is engaged by a cam 19 a control valve V2 operates a cylinder 123, the piston-rod of which swings a frame 118, to the end of which it is pivoted at 124, from the dot-dash position P to the position shown in full line in Fig. 5. The frame 118 is connected by links 121, 122 with upper and lower knives 116, 117 which slide in vertical guides 114, 115; the movement thus causes a slug K to be cut from the end of the strand S. When the pilot valve 132 is engaged by a cam 19 the control valve V1 operates to retract the piston-rod of the cylinder 96 and to supply air to the cylinder 36a, so advancing the pusher pin 47 and releasing a slug from the fingers 38, 39. When the plate 91 is retracted the drive through the clutches 78, 85 is discontinued and the rollers 76, 77 are held to their position by a brake band 103, common to both. When the pilot valve 133 is engaged by a cam 19 the control valve V2 retracts the piston-rod of the cylinder 123 and opens the knives 116, 117. The cut-off slugs are transferrred from the knives 116, 117 to the fingers 38, 39 on the continuously-moving band of a conveyer unit C. When the fingers are moved apart to release a slug K it drops into a pocket 28 of a rotary slug transfer member 29 driven from a shaft 22 which also carries a knife-edged disc 21, Fig. 7. This disc, by partially slicing into a slug K, lifts it from the member 29 and carries it round to a position between the dies of one of the moulding units 12 on the rotary carrier 10. The slug is then moulded into, e.g. a cylindrical shape Z, Fig. 10. A die member 13 and a core die member 14a move together and grip the slug which is thus released from the disc 21 as the carrier 10 continues its movement. The die member 13 continues to advance while the core member 14a is moved into the cavity of the die 14 by a spring 160 and the dies are then fully closed to mould the material round the core. The article is stripped by the retraction of the die member 13, leaving the article seated in the die member 14, from which it is then pushed by the advance of the member 14a. As the article is carried round on the member 14a by the continued rotation of the carrier 10 it is removed therefrom by a pair of stationary stripper rails. The stationary cam track 15 from which the dies are operated is shown in Fig. 9. Each moulding unit secured to the rim of the rotary mould carrier 10 includes a housing 137 in which is slidable a bar 139 carrying a roller 140 engaged by the stationary cam track 15. A block 141 projects from the slide bar 139 and has a slot 142 in which operates a roller 143 carried by a bell crank 144. The bell crank is pivoted at 145 to a thrust rod 146 and at 147 to a link 148 connected to the plunger 13a of the die member 13. As the mould carrier rotates, the cam track 15 causes the roller 140 to move the slide bar 139 in a direction to close the dies and this movement brings the pivots 145, 147 and 149 into line, the pivot 147 moving slightly over dead centre position, against an abutment 150, to lock the dies closed by toggle action and remove the pressure from the cam track 15. A spring 152 at the end of the thrust rod 146 allows for expansion of material in the mould cavity and for the slight recession of the pivot 145 as the pivot 147 passes over dead centre. The dies operate in heating chambers 157, 158 having pipe connections 159, 160 to a swivel connector for heating fluid. The material is thus semicured and at the end of the semi-curing period, as the moulding units again approach the zenith of their cyclic path and the moulding dies are opened, the semi-cured moulded article is released and falls through a discharge shoot U on to a conveyer V which carries it to a curing oven N.