| 摘要 |
This invention provides an improved method and apparatus for controlling the tension in a tensionally fragile web of material being pulled by a constant speed processing machine from either one of a pair of supply rolls. A first festooning roller effects the control of the web tension during the normal operation of the machine. During the splicing of the web from one supply roll to another, the tension in the web would tend to dramatically increase. This tendency is offset by a second festooning roller engageable with the web and shiftable in a web tension decreasing direction only upon the occurrence of web tensions substantially in excess of the normal tension range. Means are provided to restrict the rate of return movement of the second festooning roller to that which falls within the control limits of the first festooning roller, thus eliminating any tendency to accelerate the new supply roll to a speed above the desired machine operating speed. |
