Patent GB-802898-A (GB)
Title: Improvements in method of forming an endless tire tread and sidewall portion on a carcass band and product thereof
IPC: B29D30/60
Filed: 1956-09-05
Abstract: 802,898. Tyre treads. FIRESTONE TIRE & RUBBER CO. Sept. 5,1956 [May 16, 1956] No. 27145/56. Classes 144 (1) and 144 (2). An endless, spliceless, tread-sidewall portion T, S is built up on a pneumatic tyre carcass band 25 by rotating the band 25 about its axis and feeding thereto a heated continuous ribbon R of rubber or the like at a linear speed substantially equal to the peripheral speed of the band, the band and the ribbon being moved relatively in the axial direction to partially overlap adjacent turns of the ribbon, and the movement being reversed at intervals to superpose the windings and thereby provide the desired contour. As shown, a flat band 25 is built up on a collapsible drum 24 supported on a cantilever shaft 17 which is rotatably mounted in bearings 18, 22 supported on a carriage base 15. The shaft 17 is driven by a variable speed motor 28 (not shown) on the carriage base 15 through a gear-box 31, a chain 33 and a sprocket 34, the motor being controlled from a box 35 on a fixed stanchion 36. The carriage base 15 is mounted on flanged wheels 13 for traverse along spaced rails 11 to provide axial movement of the drum 24, traverse of the carriage being effected by rotation of an axially fixed nut 50, Fig. 6, having screw-threaded driving engagement with a screw 47 fixed longitudinally beneath the carriage base 15. The nut 50 is driven through a chain 53, universally jointed links 44, 43 and a gear-box 42 from a motor 40 mounted on fixed cross-members 12, 12<SP>1</SP>, the motor being controlled from a box 55, on the stanchion 36, provided with a speed control 57 and a reversing switch 56. The heated ribbon R, which may have a diamond or lenticular section, Figs. 3 and 4, is extruded from a tuber 60 mounted to the side of the drum opposite the stanchion 36, and is applied to the band 25 by a lay-down device 65 carried at the end of a Z-shaped bracket 69 fixed to an arm 66 which is pivotally mounted on the stanchion 36 to overhang the drum and is urged by a spring 71 towards the drum. The device 65 comprises a steel lay-down roller 70 journalled at the end of the bracket 69, a flanged silicone-treated steel roller 74 journalled on a lever 73 which is pivoted on the bracket 69 and urged by a spring 75 to cause the roller 74 to press against the roller 70, and a roller 76, mounted on a lever 77 pivoted to the lever 73, spring-urged against the roller 74. The ribbon R is fed between the rollers 76, 74 and 70 as shown in Fig. 9, being applied to the carcass band by the roller 70, and is stitched to the carcass by axially adjacent rollers 81, 82 disposed in the path of the ribbon at the underside of the drum. The rollers 81, 82 are mounted on arms 83, 84 respectively connected to independent spring- loaded rocker arms 87, 89. In operation, the peripheral speed of the drum is adjusted to be slightly greater than the linear speed of the ribbon R from the tuber 60 to apply the ribbon under slight tension. The axial speed of the drum carriage is set to give the partial overlap of adjacent turns, as shown in Fig. 5, and the direction of axial movement is reversed as necessary to provide the desired contour buildup. To provide a guide for this, a template 95 of the contour is mounted on the carriage adjacent the drum and a follower 96 co-operating with the template is carried on an arm 98 fixed to a rocker shaft 100 journalled in brackets fixed adjacent the carriage 15. A follower roller 97 is carried by a second arm 99 of the rocker shaft 100 to contact the applied ribbon behind the lay-down roller 70, the roller 97 and follower 96 thereby moving in unison with the latter indicating on the template 95 the amount of ribbon laid. The ribbon section has a thickness which may be of about 0.05 inch but must not exceed that of the thinnest part of the tread and sidewall to be laid, and a width not exceeding 0.5 inch. In alternative constructions, the lay-down device may comprise only a flanged lay-down roller, with a spring-loaded pinch roller bearing thereon to receive the ribbon therebetween. Further, the carriage drive may be effected from the drum-rotating motor 40A, Fig. 13, which drives two meshing gears 47A<SP>1</SP>, 47B<SP>1</SP> attached respectively to two rotatable screws 47A, 47B, journalled in the carriage. The screws 47A, 47B co-operate with half-nuts 51A, 51B carried on a shaft which is rockable by a solenoid 53A to bring one or other nut into engagement with its screw and thereby determine the direction of axial movement of the carriage.