Abstract : In a fully continuous strip pickling line, the uncoiler tension has a significant impact on strip quality. To ensure strip quality, a tension-feedback-free open-loop tension control system for the uncoiler was designed. The paper details how to control tension through accurate calculation of the inverter torque setpoint, and the strip breakage protection scheme explored during commissioning. Using the strip pickling line of Tangshan Jianlong Cold Rolling Mill as an engineering example, a Rockwell L336 FORCE inverter was used to control the uncoiler tension, verifying the reliability of the tension open-loop control system. Keywords : Pickling line; Uncoiler; Tension control; Inverter. The quality of strip is mainly measured by its thickness and shape, both of which largely depend on the control of strip tension. Excessive tension will cause tensile deformation of the strip, while insufficient tension will result in uneven coiling. The effectiveness of tension control directly affects the quality of the strip; therefore, appropriate tension is a condition for ensuring the normal operation of the rolling process and a key to improving the quality of rolled products. Commonly used tension control systems often utilize tension measuring rolls to form a tension closed loop for tension control, but due to the high cost and nonlinearity of the tension measuring rolls… This makes the implementation of the control system quite difficult. In this paper, the authors propose a fully continuous strip pickling line uncoiler tension indirect control scheme based on the Rockwell 1336FORCE frequency converter for the strip pickling unit of Tangshan Jianlong Cold Rolling Mill. This scheme is a tension open-loop control system without tension feedback, which effectively meets the tension control requirements of the uncoiler and ensures the normal operation of the entire line. 1 Tension Control System Without Tension Feedback Since there is no tension feedback device in the tension open-loop control system without tension feedback, the following three issues must be addressed to control the tension: (a) After a constant tension setpoint is given, the basic automation system must calculate the corresponding torque setpoint in real time and input it into the frequency converter; (b) After receiving the torque setpoint command, the frequency converter should be able to output the corresponding control current to the motor; (c) During the speed change phase of the entire line, the uncoiler should be able to quickly follow the speed changes of the entire line, overcome (compensate) the influence of the dynamic torque generated by the speed change on the tension, and avoid strip breakage or steel piling caused by lag in the uncoiler's action. 1.1 Roll Diameter Calculation [b][align=center]For details, please click: Tension Control of Unwinding Machines Without Tension Feedback[/align][/b]