| 摘要 |
PURPOSE:To finely adjust the tension of a travelling sheet within a low tension range with the use of a device including a dancer roller, for controlling the tension of a travelling sheet, by maintaining the dancer roller at a predetermined level with the use of an automatic sheet speed control section, and as well by providing a push-out force control section which controls the position of the fixed end of a spring for supporting the dancer roller. CONSTITUTION:A device for controlling the tension of a travelling sheet with the use of a dancer roller, comprises a dancer roller 1 which is directly or indirectly supported by a spring 4 to carry out floating motion in accordance with variations in the tension of a travelling sheet S between front and rear guide rollers 2, 2 set along a sheet path, and an automatic sheet speed control section 5 detecting the floating motion of the dancer roller 1, for adjusting the feed speed of the sheet to return the dancer roller 1 to a predetermined position A. Further, there are provided a spring end drive section 6 which supports the fixed end 4a of a support spring 4 for supporting the dancer roller 1 at the predetermined position A, for moving the fixed end 4a in the directions in which the reacting force of the spring 4 is increased and decreased, and a push-out force control section 7 for controlling the spring end drive section 6 for the dancer roller 7 so that the resultant force of the reaction force of the spring 4 and the weight of the dancer roller 1 exerts a predetermined tension to the travelling sheet S. |
