GB783667A - Improvements in or relating to method and apparatus for buffing pneumatic tyre casings - Google Patents

Abstract

783,667. Buffing tyres. RAWLS, V. Nov. 30, 1955 [Dec. 15, 1954; May 16, 1955], No. 34259/55. Class 31 (1). A pneumatic tyre is prepared for re-treading or re-lugging by buffing a stretched area of its surface. The tyre is stretched by placing it over a two-part sphere 36, Figs. 1 and 10, mounted on a horizontal shaft 38, causing one or more rollers 34 carried by arms 24 to engage the inner bead of the tyre so as to pull it downwardly over the sphere, and rotating the sphere. The arms 24 are mounted on shafts 26 which extend rearwardly into a casing 23 and there carry interconnected bell-cranks which are operated by a pneumatic or other motor to apply the rollers to the tyre for the buffing operation and thereafter returned to inoperative position by a spring ; the return action of the spring also causes rollers 45 carried by further arms 25 on the shafts 26 to engage under the tyre and lift it from the sphere. The sphere is rotated from a motor through first a belt-andpulley drive including a reduction gear and then a chain 40. Brakes associated with the shafts 26 for application by a pedal 50 ensure that the tyre is held in its stretched condition during the buffing operation. The buffing wheel 52, which consists of a cylindrical member studded with a large number of protruding points for ripping away the tyre, is mounted in a housing 59 carried by a transversely-extending tube 54 supported at its outer end in a ball joint 55 on a pillar 57 ; a tube 61 extends in the opposite direction from the housing 59 to means on a pillar 84 for swinging the wheel arcuately over the surface of the tyre. The drive shaft 53 of the wheel is journalled in the tube 54 and driven by a motor 58 at the outer end of the tube. The outer end of the tube 61 is connected to a hollow box 73, Figs. 1 and 3, slidable on a swinging arm 92 and carrying a vertically-adjustable slide supporting a roller 77 for engagement with a template 78 which is shaped to the desired form of the finished tyre and is detachably mounted on a frame 80 arranged to be vertically adjusted between gibs 83 on the pillar 84 by means of a horizontally-slidable wedge 85 actuated by a hand-operated screw 87. A yoke 93 on the lower end of the arm 92 straddles a driving lug 94 on the driven disc of a friction clutch 96 of which the driving disc is rotated through reduction gearing 99 by a motor 100. The clutch discs are engaged in order to swing the arm 92 from one side to the other by rocking a handle 103 so as to compress a spring 104, and the template roller 77 is maintained in contact with the template 78 by a spring 107 which is connected between the casing 73 and driving lug 94 and controlled by a handle 109. The motor 100 is automatically stopped after the arm 92 has been swung through a buffing arc by means of a suitably-positioned limit switch. The margins of the tyre beyond the area treated by the buffing wheel 52 are touched by a buffing wheel 67, Fig. 1, on the shaft of a motor 66 pivoted on a vertical axis on a carriage 68 slidable horizontally on the pillar 57. The housing 59, which almost entirely encloses the buffing wheel 52, is connected by a pipe 63 with a suction dust collector. It is stated that the wheel 52 produces a multiplicity of spaced disconnected slits or grooves in the surface of the tyre.