IE36113L - Tyres, casings manufacture - Google Patents

Abstract

1384052 Pneumatic tyre manufacture DUNLOP HOLDINGS Ltd 11 Feb 1972 [22 Feb 1971 20 April 1971] 5066/71 and 10148/71 Addition to 1202702 Heading B7C A method of making a casing for a pneumatic tyre comprises the steps of building a carcass of uncured rubberized cord ply material, applying a breaker assembly, if required, of the same material, applying a layer of uncured undertread rubber on the carcass and breaker assembly, shaping the carcass to its final toroidal form either before or after applying the breaker or after applying the undertread material, and at least partially curing the casing. A complete tyre may then be made by applying further undertread material if required together with a tread portion and completing the curing. The curing of the casing may be substantially complete curing with the final curing of only the additional undertread material and the tread portion, which latter may be in a partially cured state. The material of the breaker may be slow curing and be finally cured with the tread portion. The thickness of undertread rubber first applied is at least 50% of the total thickness. The carcass is built on a flat or crown former and shaped to its toroidal configuration by an inflatable diaphragm. The undertread rubber may be applied in the form of an extruded strip or by strip winding. The curings take place in a mould with the tread pattern either imparted in the final mould during curing, or applied to the casing using individual lugs or provided on the tread portion. The total thickness of undertread rubber is between 40-50% of the thickness of the tread portion. In the finished tyre the maximum preferred buttress depth B is 0À35 A, where A is the section height, and the nominal tread edge of the partially cured tyre lies radially inwards of the buttress depth by an amount C which lies in the range 0À01 B to 0À15 B. [GB1384052A]