| 摘要 |
In some process contexts it is desirable to maintain a constant strain on the web instead of constant tension. The novel system measures the caliper of the web material and adjusts the tension to achieve the desired constant strain. The caliper may be measured by monitoring the radius of the expiring web reel in connection with the angular position of the reel. The web caliper is input into a control scheme that includes an algorithm determining the appropriate tension to applied to the web in accordance with its caliper. The control scheme outputs a variable force command to a dynamic dancer which adjusts the web tension and thus sets the constant web strain. The variable force may be injected via an air cylinder, a hydraulic cylinder, a spring with a dynamic ground, or an electromagnetically driven actuator.
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