Patent GB-1326598-A (GB)
Title: Tyre building apparatus
IPC: B29C67/00
Filed: 1970-11-04
Abstract: 1326598 Tyre switching drums GOODYEAR TIRE & RUBBER CO 4 Nov 1970 [28 Nov 1969] 62396/70 Heading B7C A tyre building drum 12 comprises a tubular elastic membrane 44 including a cylindrical portion providing a tyre building surface 80, and a pair of annular inflatable bladders 140, disposed inside the membrane at opposite ends of the cylindrical portion, for effecting radial expansion and predetermined shaping of the cylindrical portion. Each bladder is in continuous circumferential contact with the membrane, the membrane 44 is secured at each end between annular clamp rings 50, 52, and the edges 142, 143 of the bladders 44 are clamped in grooves 144, 146 respectively in clamp rings 50 and cylindrical webs 24. As shown in Fig. 2, the membrane is supported in its unexpanded state by (a) central support means comprising rigid segments 82 each movable radially by means of pistons 88 and cylinders 90 mounted on a shaft 14 and (b) two cylindrical shell members 26 disposed coaxially on the shaft 14t, he two members 26 each having fingers 36 and slot 34, the shots of one shell being engageable with the fingers of the other when the two shells are moved sufficiently close by means of a screw 60, disposed inside the shaft 14, having right and left handed screw threads 62 and 70 engaging with threaded nuts 64, 72 attached to tubular sleeves 22 on the shells 26. The segments 82 are moved inwardly (Fig. 5, not shown) to allow the shells 26 to engage. Operation of the apparatus is as follows: (a) one or more plies of tyre fabric are placed circumferentially around the unexpanded drum 12, the plies extending outwardly on to auxiliary drums 170 situated at each side of the drum 12, Fig. 2; (b) bead setting devices 200, 202 then position beads 206 immediately adjacent the ends of the drum 12; (c) the bladders 140 are inflated through passages 106 in the clamp rings 50, and at the same time the shells 26 are moved toward each other, this resulting in the membrane 44 assuming the shape 12<SP>1</SP>, Fig. 3; (d) further expansion of the bladders 140 takes place with simultaneous movement inward of the bead setting devices 200, 202 and the shells 26, the hydraulic motors driving the devices 202, 200 and the screw 60 being operated by a timed control circuit; (e) after the beads 206 are set in position, as shown in Fig. 3, the devices 200, 202 are retracted, and the plies are turned up in known manner by turn up bladders 172 disposed on each drum 170; (f) additional components such as breakers or belt plies, are placed on the plies, followed by tyre tread material; (g) the bladders 140 are deflated and the shells 26 are moved outward to facilitate removal of the tyre from the drum. Alternatively, the drum may be used in its expanded state 121 in the manner of known collapsible drums. As seen in Fig. 2, the membrane 44, shaft 14 and cylindrical webs 24 define a fluid tight chamber 40 within the drum. The membrane 44 can thus be further expanded to a toroidal shape (12<SP>11</SP>, Fig. 1, not shown) to enable application to the shaped tyre carcase of a comparatively inextensible belt or breaker.