Patent GB-668075-A (GB)
Title: Improved method of and apparatus for manufacturing cord tyres
IPC: B29D30/00
Filed: 1948-09-17
Abstract: 668,075. Making tyre covers. GES. DER L. VON ROLL'SCHEN EISENWERKE AKT.- GES. Sept. 17, 1948 [Sept. 17, 1947], No. 24472/48. Class 144 (i). In a method of making cord-web tyres wherein cord webs are transferred from a twopart drum 3 onto a circular core or heating tube 13 by means of inner and outer grippers 35, 36 carrying elastic tapes 5, 4 respectively which seize the edges of the cord web, the webs are stretched radially of the core whilst being wrapped thereabout, the grippers moving in a curved path 58 (Fig. 7) which comprises an initial re-entrant portion d. The re-entrant portion d provides for initial stretch of the cord webs at the commencement of the wrapping curve. Figs. 1a, 1b show the left-hand portion only of a tyre building machine, which is symmetrical about the plane M-M, the drum part 3 being shown in full lines in its " open " or retracted position and in chain-dotted lines in its closed position. Each drum part 3 is slidable on a main shaft to its open and closed positions by means of a hydraulically-operated pivoted cranked lever 6, the two levers 6 being inter-connected by piston-rod racks 10, in the bed-plate of the machine, which engage a common pinion 11 to ensure uniform operation. In known manner the cord webs are fed on to the drum 3, rotating in its closed position, and smoothed free of air bubbles by a pivoted smoother 2 having a plurality of self-adjusting rollers 2a, the drum then being opened to leave the smoothed webs on the crown of core 13. The rollers 2a are rotatably mounted on slotted bushes non-rotatably juxtaposed on a flat-sided rod of the smoother. To ensure that the webs are not displaced during the " opening " movement, the surface of each drum part has radial bores 15 leading to a pressure-air chamber 14. With the drum in its " open '' position, the edges of the cord webs are supported on rollers 16 carried by lazy-tongs on the free ends of arms 21 which form part of the stretching mechanism. The stretching and wrapping of the cord webs about the core 13 is obtained by the co-operation of movable linkages with fixed, but adjustable, guide structures, during the advancement of the drum parts to the closed position. In the form shown, twelve such linkages (Fig. 2) each comprising a main arm 21 carrying the grippers 35, 36 are circularly arranged about the axis of the core. Figs. 6a-6h show successive positions of the movable linkages during the wrapping operation. Fig. 6a., showing the initial position with the drum 3 fully open and the gripper tapes 4, 5 spaced from each other by the action of a lever 18, pivoted to each arm 21, engaging an abutment 19 on the drum. The gripper 36 carrying tape 4 is mounted on a hammer-shaped element 4a which is slidably mounted in the arm 21 and has two lateral cross-pins 23 engaging guide tracks 22, provided on the guide structure, to maintain the spacing of the tapes 4, 5 during the initial advancement of the drum. The arms 21 are pivoted to a ring 32 which is slidable relative to the drum, and each arm carries two lateral slide blocks 25 and main rollers 26. The slide blocks 25 initially engage the guide tracks 22 (Fig. 6b) whilst the cross-pins 23 of the gripper 36 leave the tracks 22 and slide inwards on an incline 24 to allow the tape 4 to approach tape 5 and grip the edges of the cord webs. Fig. 6c shows the slide blocks 25 leaving the guide tracks 22 and rollers 26 engaging a rearwardly inclined face 27 so that on further advancement of the drum (Fig. 6d) the arm 21 is forced inwardly and rearwardly to describe the re-entrant portion d of the curve 58. When the rohers 26 leave the inclined surface 27 the arm 21 is pulled inwardly so that its underside engages a guide-roller 29 (Figs. 6e-6g) and the cross-pins 23 (which have left the inclined guide surface 24) engage the underside of an arcuate guide 30 to maintain the grip on the cord edges as the tension of the gripper tapes relaxes. The inward movement of arm 21 continues until a stop surface 31 on its pivot end abuts the ring 32, at which point the gripped cord edge is in line with the bead of the core 13. The final closing movement of the drum (Fig. 6h) drives the arm 21 with the cord web against the core holder 34 where the web is gripped by a series of barbed studs 32a, the tension of the web being relaxed slightly during this movement. On the initial opening movement of the drum an air valve 40 (Fig. 1a) is actuated via a rod 38 and lever 6 to supply pressure air to a cylinder 42 in the main shaft and force a piston end 44 (Fig. lb) against the inner ends of the hammershaped elements 4a to lift gripper tape 4 from tape 5. On further retraction of the drum the cross-pins 23 ride up a forwardly inclined surface 23a on the guide structure, causing a spring- loaded guide-ring 29f, to which the guide structures are fixed, to be moved rearwardly. At the outer position of the arms 21 (Figs. 6a- 6b) the ring 29f is released and urged forward by its springs 44a against a stop 30a. The stop 30a is adjustable, to vary the " opening width " a, Fig. 7, of the machine, by means of a screwthreaded spindle 29a which abuts lugs 29e fixed to a ring 29d which carries the guide rollers 29. The ring 29d is axially adjustable by spindles 29b to provide further adjustment of the wrapping curve 58. When the cord webs are wrapped around the core 13, the latter is wheeled on a pneumaticallyoperated carriage 46 into the axis of a beadsetting-and-pressing device which comprises two moulding rings whereby the folded cord edge portions of the webs may be preformed and pressed against the core holder.