| 摘要 |
A tension control system for use with a device which includes at least one roll over or around which a web or strand of material passes, a tension responsive transducer associated with the roll, a reference tension selector, a drive unit for effecting movement of the web or strand over or around the roll, and a tension controller associated with a tension control roll, the tension controller responsive to the outputs of the transducer and of the reference tension selector for controlling the torque applied to the tension control roll in order to control tension on the web or strand, the improvements comprising a control circuit connected between the transducer and the tension controller including an error limiter circuit responsive to the outputs of the transducer and of the reference tension selector to produce an error signal, the control circuit having circuit elements responsive to the error signal and connected to vary the torque applied to the torque control roll in a manner to maintain the web or strand tension substantially constant at the reference tension selected. The subject system optionally also includes circuits therewith for rapidly reducing or eliminating the torque applied to the drive control roll whenever the web or strand tension is greater than the reference tension selected, for limiting the maximum possible torque that can be applied, for eliminating all torque during starting and restarting and for thereafter gradually reestablishing a desired torque corresponding to the reference tension selected.
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