Patent GB-724280-A (GB)
Title: Improvements relating to apparatus for stitching the plies to form the carcass of large-size (e.g. truck and tractor-size) pneumatic tyres
IPC: B29D30/28
Filed: 1952-01-10
Abstract: 724,280. Tyre building apparatus. PIRELLI SOC. PER AZIONI. Jan. 10, 1952 [July 14, 1951], No. 822/52. Class 144 (1) An apparatus for stitching carcass plies laid round a building drum having rounded shoulders comprises two rotatable stitching discs 43, mounted for simultaneous opposed traversing movement axially of the drum symmetrically with respect to a starting position A, A<SP>1</SP> adjacent the mid circumferential plane of the drum, each disc being supported on a pivoted arm 42 tiltable towards the drums and mounted on a lever assembly, forming parallelogram linkages, which is moved bodily with the discs during the axial traverse movement to a position B or B<SP>1</SP> and is then operated for relative movement of the linkages to rotate the disc 43 about the axis of curvature of the relevant drum shoulder to traverse the disc around the shoulder to a position C or C'. In the arrangement shown, the plies on the drum, Fig. 1, show radial end faces CD and C' D<SP>1</SP>, inner rounded shoulders DE and D<SP>1</SP> E<SP>1</SP> and axial re-entrant portions EF, E<SP>1</SP> F<SP>1</SP>, and the stitching discs 43 are mounted for forward or reverse traverse of these portions whilst maintaining stitching pressure on the plies, for stitching, ply-turndown and ply-turnover operations. As shown, a saddle 2 is guided for movement normal to the drum axis on a base 1 and is operable by a motor 4 on the saddle driving a screw 3 engaging a fixed nut 3a on the base 1. Two housings 8, 9 are guided on the saddle for opposed movement axially of drum operable by an oppositely threaded screw 10 engaging nuts 11, 12 in the housings and driven by a motor 13. Each housing supports for rotation about a vertical axis a worm wheel 18 engaged by a worm 19 slidably keyed on a shaft 20 operable by a motor 21, the worm wheel' having co-axial pins 25, 26 projecting from its end faces eccentric with the axis Z thereof. Mounted on each housing is a system of parallelogram linkages, Figs. 2 and 4, formed by levers 27, 29, 31, 33, 35, interpivoted at points 28, 30, 32, 39, 40, the lever 27 being keyed to the pin 25, the lever 29 having a generally F-shape, the lever 33 being pivoted at one end to a pin 34 fixed to the housing and the lever 35 having a vertical boss 37 with an arm 36 parallel to lever 35 pivotally engaging the pin 26 to strengthen the linkage assembly. An arm 42 supporting a stitching disc 43 is mounted on a horizontal pivot 41 carried by the lever 31, pivoting of the arm 42 effecting movement of the discs 43 towards and away from the drum periphery and being controlled by a spring-loaded pneumatic piston and cylinder 44, 45. The lever assembly forms in effect a system of four parallelograms, two of which have two common corners formed by the fixed pivots 34 and Z. Figs. 5, 6 and 8 show the linkages diagrammatically, in the positions in which the plane of the disc is normal to the drum axis (as at A, A'; B, B') 45 degrees to the drum axis and 135 degrees respectively to the drum axis (as at E, E<SP>1</SP>; F, F<SP>1</SP>). In operation, the saddle 2 is first moved by the motor 4 towards the drum to bring the discs 43 to bear, under air pressure in the cylinders 44, on the plies laid on the drum. Axial traverse of the discs 43 is then effected by operation of the motor 13 until positions B, B' are reached when the motor 13 is stopped and motor 21 started to operate the worms 18 and thereby the lever assemblies to rotate the discs through 90 degrees around the drum shoulders and about the vertical axes X, X' to the positions C, C<SP>1</SP>. Motor 21 is then stopped and motor 4 operated to move the discs radially inwardly to the positions D, D'. The motor 21 is then again operated to rotate the discs through a further 45 degrees to the positions E, E', pressure on the plies being maintained by pivoting of the arms 42 about the pins 41 under pressure in the air cylinder 44. The axial traverse from E, E' to F, F' is affected by further operation of the motor 4 to move the housings 8, 9 towards the drum axis, this movement allowing further pivoting of the arms 42 whereby the discs 43 are traversed to the positions F, F<SP>1</SP>. The various stages of movement and the operation of the motors 4, 13 and 21 are controlled by a system of limit switches, push buttons, relays and joy-stick control providing for control by one operator at one station, the limit switches being adjustably mounted to allow for a change of building drum size.