Patent GB-814436-A (GB)
Title: Tyre spreader
IPC: B29D30/54
Filed: 1957-05-13
Abstract: 814,436. Retreading tyres. SUPER MOLD CORPORATION OF CALIFORNIA. May 13, 1957 [July 2,1956], No. 15150/57. Class 87(2). [Also in Group XXXIV] A tyre spreader for reducing the outer diameter of a tyre to permit insertion into, or removal from, a tyre retreading mould ring 20, comprises a frame 1, on which the mould ring 20 is located by devices 4, and power operated bead-engaging members 23, 39 for spreading the tyre beads and thereafter moving the tyre bodilyinto or out of the mould ring. As shown the frame 1 supports a platform 2 for the operator, and a horizontal support ring 3 on which the mould locating devices 4 are mounted. The devices 4 comprise three circumferentially spaced horizontal plates eccentrically rotatably mounted on the ring 3 by shafts 5 which project through the ring 3 and carry sprockets 6. Each plate 4 has an upstanding pin 18 some of which have enlarged heads 19 to engage, on rotation of the plates, in an outer peripheral groove 22 in the mould. Simultaneous rotation of the plates is effected by an endless chain 7 around the sprockets 6 and idlers 8, one of the shafts 5, Fig. 7, having a handle 15 pivoted thereto and being splined to a hub 11 of the plate 4, with the associated sprocket 6 loosely pinned to the hub 11. Normally the handle 15 hangs vertically so that a cam end 16 thereof, acting through a thrust washer 17, jams the sprocket 6 against the bearing boss 12 of the ring 3, in which the hub 11 is journalled, and thereby prevents rotation of the plates 4. In use the handle is swung to a horizontal position, in which it releases the sprocket 6, and then rotated to adjust the position of the plates as required. The lower bead engaging members 23 comprise a disc 26 supported horizontally on the end of piston rod 25 of a ram 24 which is mounted vertically coaxially with the ring 3. The disc 26 is of smaller diameter than the tyre bead and has four equi-spaced flat radial slides 27 guided thereon. Each slide 27 carries a bead engaging pad 29 which, on retraction of the slide, is received in a peripheral recess 30 in the disc, and which has upstanding and depending bead locating pins 37, 38, Fig. 1. Latching of each slide in extended or retracted position is effected by a plunger 36 in the disc 26 operating a dogleg catch 31, Fig. 6, engageable in suitably positioned holes 33, 34 in the slide. The upper bead engaging members 39 comprise two diametrically opposed swing arms 49 mounted on lateral extensions 42 of the support ring 3. Each extension 42 is supported on legs 43 and carries a pair of upstanding sleeves 48 which slidably guide rods 47 of a cross-head 46 on which the swing arm 49 is pivotally mounted by means of a pivot 50. The cross-head 46 is movable vertically by the piston rod 44 of a ram 40 which is supported vertically on the frame 1 to project through the extension 42. The pivot 50 of the swing arm 49 carries a torsion spring 52 acting to hold the arm in its upstanding position. The free end of the arm 49 slidably and rotatably receives a rod 53 which is held retracted within the arm by a tension spring 57. The outer end of each rod 53 supports a transverse carrier 54 which has a central handle 56, and a bead engaging hook 55 pivotally mounted at its end to swing about an axis which is upstanding when the arm 49 is swung into its operative radially inwardly projecting position, Fig. 4. In use, with the mould located on the plates 4 and a tyre loosely rested on the mould, the ram 24 is operated, with the slides 27 extended, to raise the tyre and permit centring thereof by means of the pads 29 and pins 37. The tyre is then lowered and the pads 29 engaged within the lower bead. Next the swing arms 49 are lowered and the hooks 55 engaged with the upper bead. With the lower bead anchored by the pads 29, the rams 40 are operated to raise the arms 49 and lift the upper bead. Thereafter the ram 24 is operated to lower the pads 29 and thereby the lower bead, Fig. 12. Finally, rams 24 and 40 are operated together to lower the tyre bodily axially into the mould ring 20, Fig. 13. After insertion of a curing bag and rim, the rams 24 and 40 are operated to allow return of the beads and thereby expansion of the tyre tread into the mould cavity C. The bead engaging members 29, 55 are released from the tyre and the mould and tyre assembly is then hoisted away.