Improvement in tire building machine


232,595. Backdahl, K. G. A. April 17, 1924, [Convention date]. Tyre covers, making.-A tyre casing is shaped from flat band form by rotating the band at high speed, the edges being caused to approach one another whilst the intermediate portion is forced outwardly and expanded into arched section by the centrifugal action. To increase the centrifugal effect, water or other liquid, or finely divided solid matter (such as shot) may be fed into the rotating casing during the operation. In the machine shown for carrying out this method, the flat band 41 is built up on a collapsable drum 34 which is detachably mounted between a pair of coned rings 30, 32. After assembling the bead wires 42, the edges of the band are clamped by rings 47, 48 and the drum 41 removed. The next operation consists in rotating the band whilst causing the edges 43 to approach one another. For this purpose, the ring 32 is connected to the outer ends of guide,- rods 11, the inner ends of which are connected to a spider 10 keyed to a sleeve 3 surrounding a shaft 1. A disc 12 secured to the outer end of the shaft 1 is connected to the ring 30, means being provided for axially moving the shaft along the sleeve 3 to effect the approach of the edges 43 of the band. The inner end of the shaft 1 is screwed through a sleeve 4 adapted to be coupled to the sleeve 3 through a thrust bearing 17 and clutch 15. Fitted to the sleeve 4 is a brake 25 the operation of which is controlled by a treadle 27. The sleeve 3 is driven from a motor 21 through a friction clutch 22 and a 3- speed reversible gear 20, and chain 18. In operation, the casing being under rapid rotation, the clutch 15 is temporarily withdrawn and the brake 25 gently applied. The retardation of the sleeve 4 with respect to the shaft 1 causes the latter to unscrew and travel in the direction of the arrow 29 to effect a corresponding movement of the inner edge 43 of the casing. The sleeves 3, 4 are again coupled and this sequence of operations continued until the rings 30, 32 meet, the (rotating) casing then having the form shown in Fig. 5. The motor is then unclutched and whilst the sleeves 3, 4 are still coupled the brake 25 is applied to stop the rotation of the casing which then assumes the form shown in Fig. 6. The rings 30, 32 are then clamped together by bolts 53 to permit removal of the casing for the vulcanizing or other finishing processes. If liquid (indicated at 49) has been used to increase the centrifugal effect, the internal pressure in the shaped casing may be adjusted by means of a valve 54. If solid material has been used the valve may be utilized for injecting air to maintain the desired internal pressure. Packing-rings 51, 52 are provided to make the necessary fluid - tight joints. Specification 214,704, [Class 87 (ii), Moulding plastic &c. substances], is referred to.




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