| 摘要 |
A pair of freely rotatable rolls (22, 22') bears against the opposite edges of a moving web (10). Each roll (22, 22') is mounted with its axis (23, 23') generally coaxial with that of the other roll, parallel to the adjacent rollers (12, 15) of the web transport systems and perpendicular to the direction of web movement. A support arm (24, 24') for each roll (22, 22') is pivotally connected to a fixed support (26, 26'), with the pivotal axis generally parallel to that of the roll (22, 22'), so that the weight of the roll (22, 22') pivots the arms (24, 24') toward the vertical and causes the roll (22, 22') to bear against the upper surface of the web (10). A constant bias force may be applied to the pivotal support arm (24, 24') to decrease (or in some circumstances to increase) the force with which gravity causes the roll (22, 22') to bear against the web (10).
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