| 摘要 |
<p>1,035,989. Building pneumatic tyres. GENERAL TIRE & RUBBER CO. May 22, 1963 [June 27, 1962], No. 20433/63. Heading B7C. A method of forming a bead portion of a pneumatic tyre by mounting a band of parallel cord fabric plies on a tyre building drum 6 with an end portion projecting past one end of the drum and overlying an inflatable, radially expansible, elastic air bag 7 positioned at the said drum end, placing a bead ring against the portion of the ply band overlying the drum shoulder and folding the end of the ply band around the bead ring and against the ply band on the end portion of the drum by inflating the bag 7 to extend it radially and by forcing the radially extended portion of the bag axially over the end of the drum, is characterized in that the portion of the expanded bag 7 surrounding the drum is collapsed into gripping engagement with the ply band on the drum by holding that portion of the bag 7 against axially outward movement while deflating the bag. The bead ring is applied to the ply band by means of an annular support member 22 which is slidably attached, by circumferentially spaced, axially extending rods 25, to a backing plate 21 of a bag-engaging sleeve 20, the member 22 being biased towards the backing plate 21 by springs 27. When the sleeve 20 is retracted from the drum 6 the axially outer ends of the rods 25 engage the wall of the housing which supports the drum shaft so that the support 22 is held stationary and aligned with the axially inner end of the sleeve to facilitate the insertion of the bead ring. The sleeve 20 is then moved axially over the uninflated bag 7 towards the drum until the bead ring is pressed against the ply band. The sleeve is retracted and the bag 7 inflated. The annular bag 7, when uninflated, has a cylindrical radially outer wall, while its radially inner wall is radially inwardly contracted at its axially inner and outer ends to form enlargements 93, 94 such that, as the bag is inflated, a strong axially outward pull on the bag causes the ply band to be pulled axially outwards. When fully inflated the bag 7 presses the ply band against the axially outer face of the bead ring, and the sleeve 20 is advanced to force the radially extended portion of the bag together with the ply band around the bead ring and over the drum end. Slippage between the bag wall and the ply band or the interior of the sleeve 20 is prevented by means of circumferential ribs 101 formed on the exterior of the bag wall. Thus the portion of the bag wall which is collapsed over the drum is held against axially outward movement. The bag is released from gripping engagement with the drum by partially inflating the bag. The second bead portion of the tyre is formed simultaneously by an inflatable bag 8 and a second sleeve 20 which is cam-operated into a horizontal position below the drum to permit removal of the tyre. The bead ring support member 22 is fixed to the backing plate since the bead ring can be easily inserted when the sleeve 20 is swung down into its horizontal position.</p> |
