Patent GB-821561-A (GB)
Title: Building apparatus for pneumatic tyres
Inventor: MITCHELL WILLIAM ERIC
IPC: B29D30/28
Filed: 1956-10-16
Abstract: 821,561. Tyre building apparatus. DUNLOP RUBBER CO. Ltd. Oct. 8, 1957 [Oct. 16 1956], No. 31411/56. Class 144 (1). Tread and sidewall bands are stitched to a pneumatic tyre carcase 1, which is built up on a spherically - surfaced former 2 in the manner described in Specification 786,162, by a pair of rollers 27 mounted on a frame 32, 40 to lie on diametrically-opposite sides of the former on a line passing through the geometric centre thereof, the rollers 27 having means to urge them radially inwardly of the former to press against the tread side wall bands, and the frame being rotatable about an axis which passes through the centre of the former to cause the rollers to traverse from the median plane of the carcase to opposite edges thereof respectively. As shown, the former 2 with the carcase 1 thereon is mounted on the end 3a of a horizontal rotatable shaft 3 which is journalled in vertical frame members 7, 16 and is driven from a motor 12. The frame members 7 support a tread band carrying cylinder 6 having an inflatable expansible peripheral tube 5 to expand the tread band into contact with the interior of a tread holding and applying cylinder 10 in the manner described in Specification 812,155. The cylinder 10 is mounted on a bracket 17 carried by horizontal bars 18 which are slidably guided between pairs of rollers 19 on the frame so that the cylinder 10 can be moved into concentric relation with the former 2 for tread application. Mounted below the former 2 is a block 29 having a vertical pivot 28 journaled in a block 30 on a base frame 8, the axis of the pivot 28 passing through the centre of the former 2. The block 29 has upstanding ears 31 between which is horizontally pivoted a frame 32, the block 29 and frame 32 having aligned bifurcated extensions 36, 35, respectively, whereby they can be locked together by a bolt 37 and nut 39 against relative movement on the horizontal pivot 33. The frame 32 carries two vertical arcuate arms 40 which embrace diametrically opposite sides of the former 2 and terminate in horizontal plates 42 extending transversely thereof. Each plate 42 carries a handle 43 and pivotally supports a swinging lever 45 on the upper end of which is rotatably mounted a stitching roller 27. The lower end of each lever 45 is adjustably pivotally connected to the piston-rod 51 of a fluid-pressure operated, spring-return piston and cylinder 50 which is pivotally anchored to the base of the associated arm 40, and is operable to swing the roller 27 into pressure contact with a tread band located on the carcase 1. Traverse of the arms 40, and thereby the rollers 27, about the pivot 28 is effected either manually, by the handles 43, or mechanically from drive provided by a rotary shaft 70 driven by the motor 12. The shaft 70 is journalled between blocks 61, 62 on the base frame 8 and comprises a square or acme screw-thread 73 which is releasably engageable by a complementarily threaded end of a slide 76 slidably keyed to a carriage 64. Release and engagement of the slide 76 with the thread 73 is effected by a shaft 65 on which the carriage 64 slides, a key 78 on the shaft 65 engaging in a groove 79, Fig. 4 (not shown) in the slide 76 and the shaft 65 being oscillatable to move the slide by a hand lever 82, a connecting-rod 81 and a crank 80. The carriage 64 is connected by parallel rods 59 slidable in the block 61, and by a connecting-rod 58 to a crank-arm 57 of the block 29 so that movement of the carriage 64 by the screw 73 rotates the block 29, carrying the frame 32 and arms 40, about the pivot 28. The screw 73 is of such length that it disengages from the slide 76 when the rollers reach the edges 15 of the carcase 1. In operation, stitching is effected from any desired position along the path of traverse always outwardly towards the carcase edges 15, return of the stitchers to the median plane, or to the starting point being effected manually, the screw drive 73, 75 being disengaged by operation of the lever 82. When mounting a former on the shaft end 3a, the nut 39 and bolt 37 may be released to permit the stitcher frame 32, 40 to be swung towards the frame 7 about the horizontal pivot 33.