GB932792A - Improvements in or relating to the manufacture of pneumatic tyres - Google Patents

Abstract

932,792. Tyre building machines. DUNLOP RUBBER CO. Ltd. Dec. 23, 1959 [Jan. 2, 1959; April 8, 1959], Nos. 136/59 and 11799/59. Class 144 (1). A machine for accurately assembling inextensible breaker and or tread bands on to a shaped tyre carcase comprises an inflatable shaping unit 8 formed by two mutually axially approachable or retractable end members 9, 10 for supporting the beads of a cylindrical tyre carcase, a collapsible drum 52, coaxial with the shaping unit, for building or supporting the breaker and/or tread band, and a cylindrical carrier ring 68, having gripping means on its inner periphery for supporting the breaker and/or tread band, mounted for axial movement between positions surrounding the drum 58 and the shaping unit 8 in each of which it is located symmetrically with respect to the mid-plane of said drum or shaping unit. As shown, the collapsible drum 52 is supported by a disc 55 secured to a flange 5 of a tubular shaft 4 which is rotatably supported in a frame 1, the disc 55 being attached to a cylindrical body 53 of the drum. A rotatable annulus 56 is supported on bearings 58 on the body 53 and is drivable by a gear ring 59 thereon, the annulus 56 carrying an inflatable air bag 62 surrounded by a plurality of segments 63 in turn surrounded by a rubber ring 64 which defines the expansible cylindrical building surface of the drum. The shaping unit 8 comprises an end plate 11 mounted on a sleeve 14 which is slidable on a tubular shaft 7 coaxially secured by a flange 6 to the flange 5 of the shaft 4. The plate 11 supports the end ring 9 and clamps one edge of an annular diaphragm 13, the other end of which is clamped a plate 12 detachably carrying the other end ring 10. The plate 12 is mounted on the end of a shaft 25 which extends through the shaft 7 to terminate in a piston 35 slidable within the shaft 4. The sleeve 14 and shaft 25 are each provided with racks 48, 49 engaging a common pinion 45 journalled with the shaft 7 so that the end plates 11 and 12 necessarily move in unison. To effect retraction of the end plates, pressure fluid is fed via a conduit 40 to an annular space 37 in advance of the piston 35, and thence via a conduit 22 to an annular space 18 between the sleeve 14 and shaft 7 defined by sealing rings 17 and 19, whereby the shaft 25 is forced into the shaft 4 and the sleeve 14 is forced along the shaft 7. Adjustable stop rods 50 carried by the end plate 12 locate the rings 9, 10 in their rear positions, Fig. 5d. Retraction of the plates is effected by exhaust of the pressure fluid from the spaces 37 and 18, and supply of fluid to the shaft 4 to project the shaft 25, and thereby, through the rack-andpinion connection, to retract the sleeve 14. The carrier ring 68 comprises a rigid cylinder 80 with an inflatable inner peripheral rubber lining 83 and outer peripheral strengthening flanges 81, 82, one of which carries a ring of headed studs 87. The ring 68 is supported in a frame 67 running on guide rails 65, 66 flanking the frame 1. Movement of the frame 67 to locate the ring 68 accurately in either of the two positions symmetrically surrounding the drum 52 or the shaping unit 8 is effected by an adjustable link or crank 73 pivoted at one end to an adjustable anchorage 75 on the guide rail 65, and pivoted at its other end to a parallel bar link or connecting rod 74 which is pivoted at 74a to the framework 67, the link 73 being rotated 180 degrees about its anchorage 75 to move the carrier ring 68 from the shaping unit to the drum. Ancillary equipment may comprise a treadapplying conveyer 92 associated with the drum 52, tread and sidewall stitching units 102, 103 associated with the shaping unit 8, and an auxiliary carrier ring 89, Fig. 3, having bayonet catch attachment with the studs 87 to lie concentrically within the carrier ring 68. In operation, a breaker 114 and tread 83 assembly is built up on the expanded drum 52 and then secured by the inflatable bag 83 of the carrier ring 68, whereupon the drum 52 is collapsed and the ring 68 moved to surround a cylindrical carcase 111 on the shaping unit 8, Fig. 5c. The end rings 9 and 10 are then approached simultaneously with inflation of the diaphragm 13 to shape the carcase into toroidal form centrally within the breaker and tread assembly, whereupon the carrier ring 68 is deflated and moved back to surround the drum 52 leaving the tread assembly to be stitched to the shaped carcase. The shaping unit is then returned to its cylindrical state, the end ring 10 is detached and the shaped tyre is removed. In an alternative method, a preformed breaker 118, which may be of the form described in Specification 808,341 or 894,706 is located within the auxiliary carrier ring 89, and a layer 121 of parallel cord fabric having a 60 to 90 degrees cord angle is built on the collapsed drum 52. The ring 89 is then secured within the carrier ring 68 which is moved to surround the drum 52, Fig. 6c, and the drum is expanded to press the layer 121 against the breaker 118. The auxiliary ring diaphragm 89a is then deflated and the ring 89 removed. A tread band is then applied to the breaker assembly on the expanded drum, and transfer of the breaker and tread assembly to the shaped carcase is then effected by the ring 68 as described above. In an alternative construction of the shaping unit, the diaphragm 13 may be omitted, each end ring 9, 10 carrying an inflatable annulus to seal against the carcase beads.