Patent GB-987983-A (GB)
Title: Improvements in or relating to the manufacture of pneumatic tyres
Inventor: WRIGHT JOSEPH
IPC: B29C70/20
Filed: 1961-03-08
Abstract: 987,983. Building tyres. DUNLOP RUBBER CO. Ltd. March 7, 1962 [March 8, 1961], No. 8390/61. Heading B7C. To obviate ply turn-down difficulties in the building of large earthmover tyres, the tyre is built up on a former 35, Figs. 6 and 7, by positioning a plurality of cord ply panels 63 thereon in side by side relation to form a complete ply extending around the whole circumference of the tyre, each panel 63 being of a length to extend from bead to bead of the tyre and of a width to extend part-way around the tyre circumference, and being formed by locating a plurality of cords 23, Figs. 1 and 3, one in each of a plurality of grooves 112 in a cord positioning member, such as the drum 6, so that the distances between the cords are equal at any transverse cross-section of the completed panel and said distances increase from a position at or near each end of the panel to a position mid-way between the panel ends, and sandwiching the cords between two sheets of rubber to complete the panel. The panels may be made separately using either a longitudinally and transversely humped cord positioning member, or a flat cord positioning member, a sheet of rubber being rolled on to cords positioned in the grooves of the member and the assembly then being reversed on to a complementary positioning member for rolling of the second sheet of rubber on to the underside of the cords. The surplus rubber at the sides of the panel so formed is trimmed to follow the line of the edge cords to provide the desired panel shape. Figs. 1 and 3 show an apparatus for forming the panels in a continuous strip which is subsequently cut into panel lengths. As shown the cords 23 are guided by a roller 22 and a spacing comb 24 into the nip between a driven calender bowl 4 and the outer grooved periphery of a cord positioning drum 6 which is supported by internal guide rollers 14 and urged against bowl 4 by a calender bowl 5 bearing on the inner periphery of the drum and driven by the bowl 4. The bowl 5 is urged towards the bowl 4, against the reaction of spring, by a fluid pressure control device 77, the diaphragm operated piston of which bears on the bowl 5 through an eccentric which is adjustable to control the nip between bowl 4 and drum 6. Strips of unvulcanized rubber 18, each with a liner 19 are also fed into the nip to sandwich the wires 23, the liners 19 being stripped from the composite strip 61 by blades 33 and taken up on reels 31 prior passage of strip 61 between a further pair of calender bowls 25, 26 for consolidation between further strips of unvulcanized rubber 30 to form a completed continuous strip 62 of cord ply panels. The drum 6 has a periphery equal in length to a single ply panel, and the positioning grooves therein increase in spacing over a 180 degrees arc and then decrease in spacing over the remaining 180 degrees arc to the starting position which represents adjacent ends of adjacent panels of the continuous strip. Figs. 6 and 7 show the apparatus for wrapping each ply panel about a former 35, which is rotatable in one direction only in steps determined by an indexing detent engaging spaced notches in a disc 37 keyed to the former shaft 55. The wrapping device comprises a horizontal frame 38 pivoted at one end on a pin 39 below the former 35 so that it may be swung out for loading of a ply panel thereon. The frame 38 supports two bent arms 44 the adjacent ends of which are secured to a pair of meshing pinions 44a rotatably mounted on shaft 45 whereby the arms may be simultaneously swung, as shown in Fig. 7, to embrace the former 35 symmetrically about its midcircumferential plane. The opposite ends of the arms 44 carry spring-loaded rollers 46 between which is tensioned a flexible fabric member 47 supporting thereon a further flexible member 48 which is recessed at 49 to locate a fly panel 63. The flexible members are supported in the horizontal position by a rigid metal platform 50 which is operable by a foot pedal 54 to raise the members 47, 48, and thereby the panel 63 into initial contact with the former prior to the ply wrapping movement of the arms 44. Specification 985,302 is referred to.