GB744801A - Improvements relating to methods of manufacturing pneumatic tyres for vehicle wheelsand to machines for carrying out such methods - Google Patents

Abstract

744,801. Tyre building machines. PIRELLI SOC. PER AZIONI. Nov. 6, 1953 [Nov. 13, 1952], No. 30840/53. Class 144 (1). In building a pneumatic tyre, the carcase plies are first built to band form on a cylindrical drum 3 which is then deformed to approximately toroidal form to shape the carcase accordingly, the breaker strips, tread and sidewalls being subsequently stitched on to the shaped carcase whilst in position on the deformed drum. Drum assembly.-As shown the building drum is formed with two rigid relatively axially adjustable end plates 1, 2, interconnected by a rubber band periphery 3 to form an inflatable assembly mounted on a cantilever drive shaft 8 driven by a motor 14. The end plates 1, 2 are respectively secured to two axially slidable rotatably keyed concentric sleeves 7, 10 the inner one of which is slidably keyed to the drive shaft 8. The two sleeves 7, 10 are respectively connected, through thrust bearings 17, 24 to oppositely-handed screw-threaded portions 20, 21 and 27, 28 of a pair of identical shafts 22, 23 operable by a motor 32 and gearing 33-37 for simultaneous uniform rotation to move the sleeves thereby mutually to advance or retract the plates 1 and 2. Bead application.-In operation carcase plies are wrapped around the drum periphery 3 in the position shown in Fig. 1, the end plates 1, 2 being relatively retracted and light air pressure applied to the drum interior via a passage 6a through the drive shaft 8. Bead wires are then applied to each end of the carcase band by means of two relatively approachable cap members 38, 39 arranged one on each side of the drum and each supporting a bead carrier 54, Fig. 6, which is resiliently mounted on headed studs 55 so that when, during the approach movement of the caps 38, 39 the carriers 54 are stopped by contact with the drum end plates, the studs 55 push the bead wires from the carrier against the carcase plies on continued approach of the caps 38, 39. The caps 38, 39 are operated by doubleacting fluid pressure piston and cylinder elements and each carry a tread supporting ring 40, 41 for use in subsequent tread application. Band shaping.-With the end caps 38, 39 retracted and ply turnover effected, the shafts 22, 23 are operated to cause approach of the drum end plates 1, 2 and simultaneously pressure air is supplied to the drum to expand the drum periphery 3. The caps 38, 39 are then advanced towards the drum until a final shaping position, Fig. 7, is reached wherein chamfered inner edges of the rings 40, 41 of the caps bear closely against the periphery of the shaped band near its crown which projects through a gap between the two rings 40, 41 centrally of the band to lie flush with the outer cylindrical surface of the rings. Tread application and stitching.-With the drum, and caps 38, 39 in the position shown in Fig. 7, a tread and sidewall strip is applied to the rings 40, 41 and centred thereon with respect to the shaped carcase band by side edge locating guides 40a, 41a on the rings, the drum and rings being rotated and stitching rollers 70, 71 being brought to bear on the tread to stitch it to the crown of the carcase in the gap between the rings 40, 41. The caps 38, 39 are then retracted to withdraw the rings 40, 41 and the stitching rollers 70, 71 operated to stitch the tread and sidewalls to the shaped carcase as shown in Fig. 9. The rollers 70, 71 are mounted for symmetrical but opposite rotation about an axis passing through the centre of curvature of the carcase band periphery in cross-section. Fig. 4 shows roller 70 rotatably carried on an arm 68 which is horizontally pivoted, for movement towards or away from the drum periphery, to a bracket 65 keyed to a vertical rotatable shaft 62. Roller 71, not shown, is similarly carried on an arm pivoted to a bracket 67 which is keyed to a sleeve 64 rotatably surrounding the shaft 62, the sleeve and shaft being oppositely rotated, for traverse of the rollers around the deformed drum periphery, through gears 65, 63 by a motor 77. Pivotal movement of each stitcher arm 68 to its operative position is effected by a piston and cylinder element 73, 72 connected between the arm and its mounting bracket 66 or 64. The finished tyre is finally stripped from the drum by further approach movement of the drum end plates 1, 2 accompanied by creation of a partial vacuum within the drum to collapse the periphery 3 radially inwardly, the tyre being ovalized to pass over the end plates 1, 2. Specification 700,435 is referred to.