GB380310A - Improvements in or relating to friction material and method of making the same - Google Patents

Abstract

380,310. Friction material. COLT'S PATENT FIRE ARMS MANUFACTURING CO., 17, Van Dyke Avenue, Hartford, Connecticut, U.S.A.-(Assignees of Whitworth, H. ; 147, Zion Street, Hartford, Connecticut, U.S.A.) Dec. 8, 1931, No. 34031. Convention date, Dec. 19, 1930. Drawings to Specification. [Class 103 (i).] Friction material particularly adapted for use as a brake lining comprises unwoven sheet form and having perforations extending fibrous material and a binder, heat cured in partially therethrough from one or both surfaces, the perforations being formed prior to curing and remaining in the completed friction material. A method of making the material comprises (1) mixing a plastic mass containing unwoven fibrous material, e.g. asbestos, a binder preferably consisting in part of rubber and adapted to be cured when heated to a prescribed temperature, a vaporizable liquid, including a solvent, e.g. gasoline or naphtha, for the binder, and sulphur and other substances for effecting rapid curing of the binder, (2) forming the mass into a sheet and at the same time effecting vaporization of most of the liquid, (3) cutting the sheet into strips, in the case of brake linings, so that the fibres extend longitudinally of the strips, (4) perforating one surface of each strip by passing the strip between a smooth roller and a spiked roller, (5) drying the strip at a temperature below the curing temperature of the binder so as to vaporize the remainder of the liquid and expel it through the perforations, (6) perforating the strip on the opposite surface and again drying it, and (7) curing the strip preferably under pressure. If desired the first drying operation may be omitted and the sheet perforated on both sides and dried by a single operation. The strip may be used as a brake lining following the drying operation or operations, so that the heat developed during actual use effects the final curing. The mass is formed into a sheet by passing it between two rollers of different sizes, the material adhering to the larger roller in successive layers as the smaller roller is withdrawn, the fibres of the material being arranged circumferentially of the larger roll. During the perforating operation the fibres adjacent the perforations are displaced transversely to interlock with adjacent fibres and thus serve to prevent splitting of the strip. The perforations also make the strip flexible and may serve to collect water if the brake is applied in the presence of moisture.