Patent GB-586952-A (GB)
Title: Improvements in or relating to tyre building apparatus
IPC: B29D30/32
Filed: 1943-09-16
Abstract: 586,952. Making tyre covers. DUNLOP RUBBER CO., Ltd. Sept. 16, 1943, No. 15167. Convention date, Oct. 3; 1942. [Class 144 (i)] [Also in Group XXXVII] Tyre-building apparatus comprises a drum with automatically operated electric circuits to control cyclically in timed relationship means for bringing tyre elements successively into position for application to the drum and means for rotating the drum one revolution in a forward or reverse direction from any predetermined angular position. The electric control consists of automatic switches operated by cams rotating in synchronism with the drum together with certain manually operated switches. The drum may be rotated by a reversible electric motor and stopped by brakes, both operating at predetermined positions. The drum rotates in opposite directions alternately, the cord plies being correspondingly turned and moved axially. The supply means may consist of a rotatable turret with guides and edgeturning discs for the cord ply, rings being provided for subsequently applying the tyre bead. A tread strip may be applied and rolled down over a predetermined area, breaker and chafer strips being also applied. The embodiment shown relates to a four-ply tyre casing but it can be used for a six-ply or other multi-ply casings. The collapsable tyre-building drum 35, Fig. 1, is mounted on an inner shaft 36 and an outer shaft 37 projecting from a motor housing 38, rotation of the inner shaft with respect to the outer shaft causing the drum to expand or collapse. Shaft 37 is mounted in a bearing 40 which supports the. drum 42 of an hydraulic brake and shaft 36 is mounted in a bearing, which is in the opposite wall of the housing, and supports another hydraulic brake. Shaft 36 is rotated by a two-speed reversing electric motor 47 through pulleys 48, 49 and belts 51, pulley 49 having inclined vanes 52 to circulate air through the housing. In building a tyre, the drum is rotated forwardly while a single layer of bias fabric is wrapped on to form a ply and then is rotated reversely while a second layer is wrapped on to form a second ply with a reversed bias angle, these operations being repeated until the required number of plies have been built up. Between the application of the second and third of these plies; the ends of the first two plies which project from the drum are turned inwardly flat against the face of the drum and the beads are applied. The overhanging edges of the fabric plies built up on the drum are turned by-the means forming the subject of Specification 586,953 and beads are applied by the bead. rings 169, 170. That part of the ply extending beyond the bead is then turned up, around and over the bead to enclose it entirely. The edges of the fabric plies are folded over the beads by the means forming the subject of Specification 586,955. The final plies are then applied, overlapping the turned-over under plies. The breaker, chafer and tread strips are then applied. The breaker, chafer and tread strips are applied by the means forming, the subject of Specification 586,954, and the tread is rolled on to the assembled plies. The tread stitchers consist of rollers 226, 227, Fig. 17, slidably mounted on a hollow shaft 230 carried by a bracket 231 keyed to a hollow shaft 179, the bracket being in two parts connected together to enable the rollers to follow the contour of the tread. The rollers are slid. along the shaft 230 by a screw shaft 248 having right and left hand threads and carrying nuts 253, 254 which extend through a slot 257 in shaft 230 and engage the roller hubs 228, 229. Shaft 248 is geared to a shaft 263 which in turn is geared to a shaft 271 within shaft 179. Shaft 271 is driven from an individual motor 272 within the housing 38 by a belt 273 and pulleys 274, 275, the latter being connected to shaft 271 through an overload release device. Shaft 271 also drives through a gear wheel 286 a device for limiting the travel of the tread rollers 226, 227. The control mechanism consists of a timer driven by the drum shaft 36 and of hand- or foot-operated levers 304..308, Fig. 1, so connected that the timer determines when and to what extent an operation set in action by the levers shall take place. Levers 304, 308 may be locked down by a counterweight latch 309. The housing 38 carries a timer casing 310, Fig. 26, with devices driven from a vertical shaft 311 geared to the drum shaft. Shaft 311 is so geared to a timer shaft 318 that shafts 36, 318 rotate at the same speed and in the same direction. Shaft 318 carries cams 319..329 which in turn support and actuate a switch arm 331 travelling step-by-step over the cams and over corresponding micro-switches 332..342 mounted between inclined posts 343, 344. The switch arm 331 is rotatably mounted on a collar 356 which can slide along a square shaft 357 and which is continuously urged along by a rope 365 coupled to a piston and cylinder supplied with air under pressure. Arm 331 is stopped at each cam by a ring 373 mounted on collar 356 and having a stem 372 extending through a diagonal slot in the casing, the slot having a stepped edge. To move the stem from one step to the next and so permit the arm 331 to slide along the shaft 357 from one cam and switch to the next, shaft 357 carries a ratchet wheel 377 advanced tooth-by-tooth by a pawl engaging a cam 381 and actuated by a pneumatic piston and cylinder. A rack 394 serves to position the arm 331 accurately over the corresponding cam and switch.