Patent GB-550039-A (GB)
Title: Improvements in or relating to the stretching and levelling of metal strip material
IPC: B21D1/05
Filed: 1940-06-29
Abstract: 550,039. Stretching strip metal. DAVY & UNITED ENGINEERING CO., Ltd. June 29, 1940, No. 11062. Convention date, July 1, 1939. [Class 83 (iv)] In a method of continuously stretching and flattening metal strip, the strip is first cold worked to promote stretching and is then fed to a rotatable strip engaging member driven at a peripheral speed sufficiently in excess of the feeding rate to stretch the strip continuously beyond its elastic limit. The strip may be fed from an unwinding reel 1 to a winding reel 4 through a drag tension unit 2 and a full tension unit 3, the unit 3 being driven at a higher speed than the unit 2 so as to stretch the strip beyond its elastic limit and the reel 1 being driven by a motor 21 at a speed less than that of the unit 2 and the reel 4 being driven by a motor 24 at a speed higher than that of the unit 3 so as to tension but not stretch the strip between these points. The tension units consist of rollers 6 driven by motors 22, 23 and co-operating rollers 12 carried by toothed discs 9 and driven by gearing 13 from the rollers 6. The position of the rollers 12 is adjusted by motors 17 and gearing 14, 9 so that they may be arranged above the rollers 6 during threading of the strip through the machine, the rollers 12 being arcuately moved first outwardly and then inwardly and upwardly to loop the strip so that it travels round two reverse bends as it passes through each tension unit to work the metal to promote stretching. The motor 23 is driven at a peripheral speed in excess of that of the motor 22 to stretch the strip therebetween beyond its elastic limit the amount of elongation being indicated by a speed ratio meter 26. The tension may be maintained uniform by a loop tension control device 27, or the tension may be automatically varied so as to effect a uniform amount of stretching per lineal unit by driving the pull tension unit through a differential gear. The drag unit is driven by a motor 32, Fig. 3, connected by bevel gear 31, 33 to a shaft 34 carrying a bevel gear 36 in the differential cage, which contains also a bevel gear 38 on a shaft 39 connected by bevel gear 41, 43 to the pull tension unit. The casing 37 which carries the idler gears 43 is driven by bevel gear 44, 46 by a variable speed motor 47. The amount of elongation is indicated by a meter 48. In Fig. 4 the rollers 60, 61 of the drag and pull tension units are rotated in a fixed position and each roller is driven by a separate motor 62 so that the speed of each roller may be independently controlled and the desired pull exerted regardless of variation in the diameters of the rollers. A set of backed up bending rolls 71 may be mounted between the uncoiler and the drag tension rollers for reverse bending the strip sharply so as to cold work it sufficiently to prevent stretcher strains developing during the stretching between the drag and pull tension units. Each tension unit may comprise four or more rollers. The Specification as open to inspection under Sect. 91 states that when acting on strip having the same thickness throughout its width the stretching and flattening may be effected by the use merely of an uncoiler and a coiler driven at different speeds. This subject-matter does not appear in the Specification as accepted.