Patent GB-1407264-A (GB)
Title: Pneumatic tyres and their manufacture
IPC: D04B23/12
Filed: 1972-07-07
Abstract: 1407264 Pneumatic tyres UNIROYAL Inc 7 July 1972 [8 July 1971 (2)] 31967/72 Heading B7C [Also in Division D1] A raw 0 degree belted tyre capable of undergoing radical expansion to toroid form comprises a body of tread rubber surrounding the medial section of a substantially cylindrical carcass C and between these two a belt forming structure B formed by a helically wound tape comprising a plurality of full turns round the carcass and comprising at least one reinforcing cord held in substantially planar undulations by means such that, during the shaping of the tyre, these means are released and the cord at least pulled straight. The plane of the undulations will usually be normal to the tread and the tape may be wound uni- or bi-directionally. The cords of steel wire, cotton, rayon, nylon, polyester, polyvinyl alcohol, glass fibre or like cords may be coated with rubber or latex and may be weakened at intervals not equal to the length of one turn of cord in a tyre or a multiple thereof. The usually sinusoidal undulations of the cord may be held by warp knitted chain stitches 4 and an almost straight laid in yarn 6 all of weak cotton, rayon or the like. More than one cord may be laid into the stitches and the undulations of adjacent cords will be 180 degrees out of phase and their weakened points will not coincide. Several tapes may be joined together side-by-side. The cord may be held by more than one warp chain or by a frangible strip 5 to which it is stitched. Apparatus for making the tapes comprises a weakening device 10 (chemical or physical) from which cords 2 pass in sets 2a, 2a<SP>1</SP>, 2b, 2b<SP>1</SP> and 2c, 2c<SP>1</SP> respectively directly and over phasing rolls 14, 15 so that the weakened portions are staggered to a warp knitting machine 17 where two tapes are formed. These tapes pass respectively directly and via a roller 21 to stagger further the weakened portions and are joined in device 24 with a liquid cement or adhesive into a tape 25 which is taken up on roller 26. The weakening device may be nicking mechanism in which the cords are engaged by a cutting block 100 and pressed against a member 101 to form a weakening. Two bearded needles 103 in needle bar 102 knit yarns 4 coming from guides 105 carried on an angularly and axially movable guide bar 104. Axially reciprocable guide bars 111, 112, 113, 114 carry respectively pairs of rods 115, 116, 117, 118 with guiding tubes 119, 120, 121, 122. Tubes 120 guide yarns 6 while tubes 119, 121, 122 guide cords 2. Bars 111-114 are controlled by pattern chains, bar 112 being moved very little while bars 111, 113 and 114 move substantially to produce the undulations in the cords, bar 113 being 180 degrees out of phase with the other two. Adhesive is applied to the tapes by means 123 and the tapes are pressed together by rollers 129, 130. The tyre liner, body plies, beads, chafer and filler strips are assembled on a low diameter drum D. The body ply portion of carcass C is constituted by any desired number of plies of tyre cord fabric whose cords are so orientated that, after shaping, they assume an angle between about 25 and 90 degrees, e.g. 80 to 90 degrees for radial ply tyres or 25 to 45 degrees or 50 to 75 degrees for cross ply tyres. Tape 25 is wound with the undulations of the cords perpendicular to the circumference and the turns of tape separated by a small gap and at an angle less than 2 degrees to the plane of the tyre and preferably less than 1 degree.