Patent GB-799089-A (GB)
Title: Tyre building machine
IPC: B29D30/32
Filed: 1956-08-10
Abstract: 799,089. Tyre building machines. GENERAL TIRE & RUBBER CO. Aug. 10, 1956 [Aug. 17, 1955; July 17, 1956], No. 24579/56. Class 144 (1). In a tyre building machine wherein fabric plies 118 are wrapped around a radially expandable drum D with their ends 119 projecting axially beyond the drum shoulders to receive bead rings 53 placed thereover, the projecting ply ends 119 are turned and stitched around the bead rings 53, at each end of the drum, by a resilient expandable stitching ring, such as a garter spring 105, carried by the free ends of a circumferentially spaced series of radially extending curved fingers 84, the other ends of which are pivoted to an actuating member 85 (86) slidable within, and axially with respect to the drum and housed axially inwardly of the drum shoulders, the finger ends, and thereby the stitching ring 105, being swung radially outwardly and axially inwardly along a predetermined path to effect ply turn-over and stitching, on axially outward movement of the actuating member, Figs. 15 and 16, by engagement of the axially outer surfaces 114 of the fingers with a first guide means 112, and being retracted, Fig. 17, to their rest position, on reverse axial movement of the actuating member, out of contact with the plies along a second path radially outwardly of the first-mentioned path, by engagement of the axially inner surfaces 115 with a second guide means 113 radially outwardly of the first guide means 112. Drum assembly.-As shown, the building drum D is mounted on a hollow cantilever shaft 5 journalled in bearings 6, 7, on a support housing 2 and driven by a reversible motor 9. The drum D, Fig. 6, comprises two axially spaced rigid hub members 15, 16 slidably keyed to the shaft 5 and each supporting a rigid coaxial cylinder 13, 14 respectively. The hubs 15, 16 are relatively displaceable axially on the shaft, for adjustment of the axial width of the drum, by a screw 18 having oppositely screwthreaded ends engaged respectively by the hubs and being axially fixed to, but rotatable in, a rigid member 17 fixed to the shaft 5 between the hubs 15, 16. Each drum cylinder 13, 14 supports an inflatable rubber annulus 20, 21 the outer surface of which is covered by a circumferential series of metal strips 34, the ends of which project radially inwardly to embrace the drum shoulders and terminate in hooks 36 to receive garter springs 37. The springs 37 hold the strips 34 against the associated rubber annulus and serve as stops to limit the inflation expansion of the annulus by abutting the inner surface of the cylinders 13, 14. The gap between the cylinders 13, 14 is covered by a pair of over-lapping semi-cylindrical plates 43, 44, Fig. 20, resiliently held together by tension springs 47 to embrace adjacent ends of the strips 34 to form a continuous cylindrical surface which may be further covered by a rubber sheath. The ends of such a sheath may be thickened and extend around the drum shoulders to locate the sheath axially. Inflation of the rubber annuli 20, 21 is effected via inlets 22 and a conduit 23 supplied with pressure air via an annular space 31 within the shaft 5 defined by a hollow slide member 30 sealed at its ends 32 to the shaft interior and fed with pressure air via a pipe 29, a non-rotatable coupling 28, and a conduit 26 from a solenoid-controlled valve 27, Fig. 23. Bead placing means.-The rubber-coated inextensible bead rings 53 are placed over the fabric ply ends 119 adjacent each drum shoulder by a bead placing ring 50 (51) which has thin resilient axially projecting strips 54 to support the beads and is trunnion mounted in U-shaped supports 54 (55). The support 55 adjacent the housing 2 is rigidly connected to the piston rod 70 of a double-acting pneumatic motor 66 whereby it is moved axially of the drum D, and is connected also to a rack 78 which, by means of a pinion 79, drives a corresponding rack 77. The rack 77 engages a quadrant gear 62 which is fixed to a shaft 58 journalled in a mounting 59 and to which the other support 54 is keyed. The mounting 59 is guided. for movement axially of the drum on horizontal rods 60 and the support 54 carries a pair of cam followers 63 which co-operate with brackets 64 having cam slots 65 to determine the swinging and axial movements of the support 54, on movement of the rack 77, between the rest position, Fig. 1, and the operative position, Fig. 6. The motor 66 is controlled by a solenoid-operated valve 67, Fig. 23, and bead placing may be effected either before or after the fabric ply band has been expanded by inflation of the rubber annuli 20, 21. Bead supporting projections 38, having bevelled support faces 39, are carried by the ends 35 of the metal strips 34 to centre the bead on the plies. Ply turnover and stitching means.-Adjacent, but spaced from, each drum shoulder the shaft 5 carries a metal stop-member 109, the radially outer surface of which supports the projecting ply ends and the axially inner face of which is formed with an annular axial guide projection 112 to engage the axially outer surface of the arcuate turnover fingers 84. The fingers 84 have their outer ends 104 formed to support the garter stitching spring 105 and their axially inner ends are pivoted on pins 106 carried by an actuating ring member 85 (86) slidably mounted on the shaft 5. The two actuating members 85, 86 are connected for simultaneous axial movement by two racks 88, 87 within the shaft 5 engaging a common pinion 89. The racks are connected to their respective ring members 85, 86 by pins 98, 99 which extend transversely through slots 100, 101 in the shaft 5 and the rack 87 is additionally connected by a pin 97 to the axially inner end of the slide member 30. Movement of the racks 87, 88 is effected by a double-acting pneumatic motor 90, Fig. 23, which is controlled by a solenoid-operated valve 92, and has its piston-rod connected by a non- rotatable member 95 to the pipe 29, and thereby the slide 30. To effect the return movement of the fingers 84 and garter springs 105 from the position shown in Fig. 16, along a path radially outwardly of that followed in the turn-over and stitching operation, on axially inward movement of the actuating members 85, 86, Fig. 17, the axially inner surfaces of the fingers 84 are pulled against a circumferential series of guide stops 113 in the form of U-shaped bars which are axially adjustably bolted to the stop members 109 to lie radially outwardly of the guide projection 112. The bars 113 act as pivots about which the fingers are swung radially and axially outwardly to expand the garter springs 105. Tread stitching means.-The tread and sidewall rubber 120, Fig. 18, is stitched to the plies 118, with the annuli 20, 21 still in the inflated condition under which the ply ends were stitched around the beads 53, by a roller 147, Fig. 5, which is profiled to conform with the tread and sidewall contour. The roller comprises a series of flat discs 147 freely mounted with a clearance 148 on a sleeve 145 which is rotatably mounted on a shaft 126 mounted parallel with the drum D between the arms of a bracket 124. The bracket 124 is mounted on an arm 127 which is pivoted on a shaft 129 for swinging movement towards and away from the drum surface, such movement being effected by a pivotally mounted double-acting pneumatic motor 132 which is controlled by a solenoidoperated valve 143 and has its piston-rod pivotally connected to a bell-crank 133 fixed to the shaft 129. To provide a back-up for the roller discs 147, a second shaft 125 is mounted in the bracket 124 for adjustment about the axis of the shaft 126, the shaft 125 having rotatably mounted thereon a deformable soft rubber sleeve which profiled as shown in Fig. 5 to conform with the contour of the roller discs 147. In operation, the clearance 148 between the discs 147 and the shaft 126 allows the discs to conform resiliently with the exact shape of the tread and side wall strip. The relative disposition of the parallel shafts 5, 125 and 126 is such that the plane containing the axes of shafts 125 and 126 makes an angle of up to 30 degrees with that containing the axes of the shafts 5 and 126. In alternative arrangements, the roller discs are all of the same diameter but mounted with considerable clearance on their shaft, the back-up roll also being cylindrical in form and either in the form of an inflatable annulus or a soft rubber sleeve sufficiently deformable to permit movement of the discs to conform with the tread and sidewall contour. Figs. 32 and 33 illustrate an alternative connection of the turnover fingers 84a to the actuating member 85a wherein the pivot pins 106a engage in slots 188 in the fingers, the axially inner ends of each slot (with the fingers in the rest position) having a notch 238 to ensure engagement of the pins 106a with that end of the slot during the return axially inward movement of the actuating member. Further the guide projections 112 are replaced by a series of rollers 112a, and the separate guide bars 113 are replaced by a ring 113a. In the machine described embodying this arrangement, the semi-cylindrical plates 43, 44 completing the drum surface between the metal strips 34 are replaced by four arcuate overlapping plates each connected to a radial spoke which is telescoped and spring-urged radially inwardly within a hollow support radiating from the rigid intermediate member 17. Fig. 39 shows an alternative form of turnover finger 84b which is provided with a laterally and axially outwardly extending segmental head 420 which in the rest positions of the set of fingers 84b form almost a continuous ply-end supporting ring and which continue to support the ply-end during the turn-over operation. In this arrangement, the radially outer surface of each stop member 109 directly supports the finger heads and not the ply ends.