| 摘要 |
A web-tensioning apparatus has stationary and movable clamps for clamping the opposite ends of a length of web, the movable clamp having a first spring for elastically forcing it in a direction towards the length and a second spring for elastically forcing it in a direction away from the length, the second spring providing greater spring force than the first spring plus the clamped length's initial resistance to stretching. If the web does stretch a little, the first spring relaxes so that the second spring can exert more force to move the movable clamp away from the stretched length. |
