GB700746A - Improvements in covered rollers - Google Patents

Abstract

700,746. Inking-apparatus. THOMPSON & CO. (OTLEY), Ltd., J. R. Feb. 28, 1951 [April 17, 1950], No. 9361/50. Class 100 (2). [Also in Groups V and VIII] An inking roller comprises a central roller stock within a resilient thermoplastic coating formed of an outer covering (of plasticized polyvinyl chloride, polyvinyl acetate or a copolymer of vinyl chloride with vinyl acetate and/or vinylidene chloride) keyed to the stock by an intermediate core of composition which is at least as resilent as the covering and has a low melting point (e.g. up to 50‹ C.), so that, after it has set, any further cooling will be insufficient to cause appreciable contraction of the covering ; the composition may be of gelatine - glycerine - water or other thermoplastic material with or without a tanning agent to raise the melting point after manufacture of the roller. In one method of manufacture a solid or tubular metal or other roller stock 1, Fig. 3, is centralized within a preformed plasticized p.v.c. tube 3, e.g. while the latter is still within its forming mould, and the core 2 is then cast between ; the tube 3 is formed by heating p.v.c. to about 150‹ C. in a vertical cylindrical mould 4, Fig. 2, the hollow centre being produced either by a former 5 whose ends fit into holes in the base 7 and in a removable locator such as a spider 8, or by immersing the mould, filled with liquid p.v.c., in boiling water and in cold water for periods controlled to produce a semi-gelled sleeve of the required thickness, the excess liquid then being poured off ; short strips of cotton &c. tape are spaced around the inner surface at each end before heating as above. In another method of manufacture the core 2 is first formed on the stock 1 (e.g. with the stock preheated to 60‹ C., first a thin film and as it cools a thicker layer of core material is applied), and the p.v.c. coating 3 is then moulded around it and gelled at a temperature insufficient to cause the core material to boil. The stock 1 may be treated to assist adhesion, e.g. by wrapping with cotton &c. tape or roughening, and the tube 3 may be internally, or the core 2 externally, keyed by channels, flutings, ribs &c. Shrinkage during casting may be allowed for by providing extra core material at the roller ends or by making the tube 3 over-long and subsequently cutting the ends away to the required amount; or bosses 10 of end plates 11 may fill up the shrinkage spaces. The roller ends may be sealed, by applying a film of sealing medium or simply by the end plates 11, to prevent damage to the core by water, acid &c. The composition of the coating 3 may be polyvinyl chloride powder, tricresyl phosphate and lead stearate ; a pigment may be added.