GB434113A - Improvements in or relating to the treatment of metal sheets and the like - Google Patents

Abstract

434,113. Altering physical structure by working. STEVENS, A. H., 5, Quality Court, Chancery Lane, London.-(Bethlehem Steel Co. ; Bethlehem, Pennsylvania, U.S.A.) Dec. 22, 1933, No. 36187. [Class 83 (iv)] Working at specified temperatures.-Tendency to flute or stretcher strain in annealed or normalized low carbon steel sheets is lessened by subjecting them to mechanical strain and preventing their reversion to their original state upon heating and subsequent cooling by subjecting them to mechanical strain during the cooling while still at an elevated temperature, above 700‹ F. and preferably about 750‹ F. The strain may be applied by a roller leveller or the metal strip may be unwound from one roll on to another roll. Alternatively, sheet on a braked drum 20 may be unwound past an idling roll 21 in a heated bath of salts and around two rolls 23, 24 geared together to run at the same speed, the second roll 24 having a diameter 1¢ per cent greater than the first roll 23. Such a stretching may take place in successive stages of 1 per cent each time at temperatures of 700‹ F., 600‹ F., 500‹ F., &c. The sheet material may be treated before tinning and the sheet then passed between nip rollers 34, Fig. 3, and through a tin pot 32, kept at about 600‹ F., to a roller leveller 33 which removes strains introduced by the tinning process. Specification 420,469 is referred to.