GB369239A - Improvements in or relating to devices for controlling the tension of paper, textile fabrics, or other flexible material during winding or unwinding - Google Patents

Abstract

369,239. Brakes. BETHLEHEM STEEL CO., Bethlehem, Pennsylvania, U.S.A.-(Assignees of Nieman, H. W. ; 115, East Market Street, Bethlehem, Pennsylvania, U.S.A.) Sept. 11, 1930, No. 27203. Convention date, Sept. 12, 1929. [Class ‹103 (i).] In apparatus for unwinding paper, textile fabrics, or other flexible material from a drum at constant tension, the rotation of the drum is controlled by a friction element engaging a cylindrical surface and acted upon at one end - by a force tangential to the cylindrical surface and opposed to the direction of rotation thereof, the wrap or angle of engagement of the friction element being sufficiently great that its torque is independent of the coefficient of friction, and the force applied to the friction element is automatically controlled by a member moving in accordance with the varying diameter of the material on the drum. In the device shown in Figs. 1 and 2, a cylindrical member 13 secured to the shaft of the unwinding roll 11 is engaged by a flexible friction element comprising a band 24 attached at one end to a link 37 and connected at the other end to a pin 30 spanning the adjacent ends of a pair of spaced outer bands 23, the other ends of which are connected to a link 29 pivoted to the end of a lever 43 acted upon by a tension spring 16. The bands 23, 24 comprise steel strips having facings.of friction material and together make more than a complete turn round the cylinder 13. Owing to the large angle of wrap and the fact that the spring 16 applies a tangential force to the friction element opposed to the rotation of the roll the torque exerted by the bands is independent of variations in the coefficient of friction. The link 37 is connected to an arm 39 fixed to a shaft 40 to which is also secured an arm 41 carrying a roller 17 held in constant engagement with the roll 11 by a spring 42. As the diameter of the roll decreases the link 37 rises, allowing circumferential movement of the bands 23, 24 and a gradual diminution of the tension of the spring 16 and thus of the braking action on the roll. One end of the spring 16 is attached to a block 46 adjustable on an arcuate guide 47 to enable the normal tension of the material to be varied.