Improvements in mechanisms for maintaining constant tension in strip, thread and wire material

摘要

850,970. Unwinding thread &c. GEOFFROY-DELORE S. A. Jan. 25, 1957. [April 5, 1956], No. 2775/57. Class 120(2). [Also in Group XVI] A braking mechanism for maintaining a substantially constant tension in strip, thread, or wire being unwound from a roll 4b comprises a brake member 6, a spring 11 for causing the brake member to exert a braking action on a reel 4a carrying the roll, and a first idle roller 16 disposed between the reel and a second idle roller 20 for engagement with the material being unwound, the roller 16 being mechanically coupled to the brake member 6 and mounted so that its rotational axis can move only in a direction substantially normal to a line passing through the axes of the reel and roller 16, so that the roller 16 exerts a force on the brake member which varies as a function of the radius of the roll of material on the roll. The material 4 being unwound exerts forces Q 1 , Q 2 , Q 3 , Q 4 and Q 4 on the roller 16 as the radius of the roll diminishes, these forces having components q 1 , q 2 , q 3 , q 4 acting along a link 15 which are respectively approximately proportional to the quantities (R 0 -R 1 ), (R 0 -R 2 ) &c. The components exert forces on a two-armed lever 7, 8 which cause the braking pressure exerted by the member 6 to vary according to the radius of the roll of material.