GB696797A - Tire bead stitching mechanism - Google Patents

Abstract

696,797. Tyre-building apparatus. WING- FOOT CORPORATION. Oct. 19, 1951 [March 17, 1951], No. 24478/51. Class 144 (i). In a " flat-band " bead stitching mechanism for turning and securing the inner and outer plies of a tyre about the bead, the stitcher unit 29 comprises a stitcher wheel 47 mounted for relative axial movement with respect to a cooperating roller 39, and is movable in an arcuate path radially about the bead. As shown a stitcher unit 29 for each end of a building drum is mounted on a body 33 pinned to the upper end of a shaft 28 which is rotatable against a return spring 32 by a fluid-pressure operated piston rack 26 engaging a pinion 27 on the lower end of the shaft 28. The shaft 28 is mounted on a crank arm 23 fixed to a shaft 19 parallel with but axially offset from the shaft 28 and rotatable in both directions by a worm-wheel and pinion 12, 13. The two worm-wheels 12 for the stitcher mechanisms are mounted on a common splined shaft 14 driven via a reduction unit 15 from a reversible motor 16 mounted on a machine support slide 4. Each shaft 19 is mounted on a casing 11 enclosing the wormwheel 12 and horizontally adjustable along the support 4. The support 4 is in turn slidably adjustable along an inclined surface 3 of a support 2 to cater for building drums of different diameters and to allow the shaft 19 to be positioned substantially tangentially to the drum. Each stitcher body 33 carries an axially bored sleeve 35 in which a shaft 43 is slidably received. A hollow roller 39 is rotatably mounted on the sleeve 35 and a stitcher wheel 47 is rotatably mounted on the shaft 43, the wheel 47 having a cylindrical rear portion which is freely received within the bore of the roller 39 so that the wheel 47 may be pulled outwardly from the roller 39 against the action of a return spring 51 surrounding the rear end of the shaft 43. The roller 39 has a rear cylindrical surface 71 which merges into a substantially conical or convex forwardly tapering portion 72 leading into a sharply convex portion 73 which in turn curves into a concave beadengaging portion 56. The portion 56 is substantially continuous with a co-operating concave surface 57 at the forward end of the stitcher wheel 47. The contoured surface of the roller 39 is axially fluted so that it provides a stepped " tacking " action in operation to avoid shifting and wrinkling of the plies. In operation, with the stitcher unit 29 in the position shown in Fig. 6 and a bead 64 applied to the inner plies 62 on the drum 63, the shaft 19 is rotated to swing the unit to the position shown in Fig. 7 where the piston rack 26 is operated to rotate the stitcher unit into pressure contact with the plies 62, Fig. 8. The shaft 19 is then rotated in the reverse direction, Figs. 9-12, to turn and stitch the inner plies about the bead 64, the wheel 47 and roller 39 rotating, and moving axially relatively to each other against the spring 51, according to the contour of the bead to ensure even stitching action about the bead. When in the position of Fig. 12 the pressure on the piston rack 26 is released and the unit 29 is rotated by the return spring 32 away from the drum, Fig. 13. The outer plies 68, chafing strip 69 and tread 70 are then applied and the piston rack again operated to rotate the unit 29 into engagement with the plies. The shaft 19 is then rotated in the reverse direction from the previous plystitching operation to turn down and stitch the outer plies and chafing strip about the bead.