Patent GB-756986-A (GB)
Title: Improvements relating to methods of and apparatus for stitching the plies to form the carcasses of pnematic vehicle wheel tyres
IPC: B29D30/32
Filed: 1954-03-24
Abstract: 756,986. Building tyres. PIRELLI SOC. PER AZIONI. March 24, 1954 [March 5, 1954], No. 8646/54. Class 144 (1). In a flat-band tyre building machine wherein the overhanging plies at each end of the drum 1 are turned down around the drum shoulders, and subsequently turned axially outwardly and around bead cores, by a stitching roller 10 having a limited traverse movement axially of the drum adjacent the drum shoulders and rotational movement around the drum shoulders, the stitching roller is driven for rotation about its own axis, independently of its frictional contact with the plies, by a motor which would impart to the roller a freerunning peripheral speed greater than that of the plies on the drum, the driving torque of the motor being less than the frictional torque on the roller so that no slip occurs at the point or line of contact but the drag on the plies, which normally results in wrinkling, is substantially eliminated. As shown in Figs. 3, 7 and 8, the roller 10 at each end of the drum is secured to the rotor of a compressed-air motor having sliding radial blades, the stator being secured horizontally to a hollow roller support arm 9 through which compressed air is fed, via flexible tubes, to the motor. The arm 9 is fixed to a pin 12 supported for rotation and axial sliding movement in the forked end 13 of a hollow rotary shaft 17. Sliding movement of the pin 12, which imparts a rectilinear translational movement of the roller 10, is effected rapidly against a return spring 16 by a piston 14 at one end of the pin 12 working in an air cylinder 15 incorporated in the fork 13. Rotation of the shaft 17, which effects rotation of the roller 10 around the drum shoulder, or a bead core thereon, is effected by a gear wheel 18 fixed thereto and driven by a worm which is splined to a motor-driven shaft and journalled in a housing 19 which mounts the shaft 17 and gear 18. Axial setting of the roller support assembly is effected by a manual screw 31 engaging the housing 19 and incorporating an air-operated piston 33 and an oil dashpot piston 36. The piston 33 works in a two-way cylinder 34 which is secured to a bench 20 and has a stroke which effects, and limits, the initial traverse movement of the roller 10 parallel to the drum axis, the oil dashpot 35, 36 ensuring slow movement. Rotation of the pin 12, and thereby the arm 9, to bring the roller 10 into pressure contact with the plies on the drum, is effected by a pressureair operated, spring return piston 26 the rod 25 of which extends through the shaft 17 and is coupled to a lug (not shown) on the arm 9. In operation, for ply turn-down of the initial plies, pressure is applied to piston 26 to swing roller 10 against the plies and then simultaneously the drum 1 is rotated, pressure air is supplied to the roller drive motor, and piston 33 is operated to move the roller assembly axially of the drum towards the relevant shoulder. The roller 10 is profiled as shown in Figs. 9-12 to present alternating peaks and valleys of different diameters and for the initial traverse movement the large diameter edge 43, Fig. 9, effects stitching pressure until it is allowed to move radially inwardly by the drum shoulder to bring a cylindrical portion 44 of the roller against the plies. Traverse of the roller continues to position III, Fig. 10, which is limited by the stroke of the piston 33, and the worm shaft is then rotated to drive the gear 18 and rotate the roller 10 about the drum shoulder-position I, Fig. 11. During the initial rotational movement, the roller is rotated about its own axis at a peripheral speed determined by the contact of its cylindrical portion with the plies so that the large diameter edge 43 of the roller is given a higher peripheral speed whereby it effects a wiping and flattening action on the plies in advance of the stitching portion of the roller. After a bead core 46 has been applied to the turned-down plies, the roller 10 is rotated to position I, Fig. 12, and pressure applied to cylinder 15 to effect movement of the roller to bring its small diameter valley 48 into a position to engage the plies on operation of piston 26. Shaft 17 is then rotated and the roller 10 effects wrapping of the under plies about the bead, passing through positions I to V during which the valley 48 and peaks rand 43 of the roller profile are brought successively into operation. Subsequent stitching of the over plies about the bead is effected by the roller as for the initial ply turn-down except that, as in the bead wrapping operation, Fig. 12, the roller need not be driven by its own motor.