Abstract : This paper analyzes the challenges, control concepts, improvement methods, and implementation schemes for implementing Automatic Position Control (APC) in rolling mills using Impact frequency converters. A program control block diagram of the APC system is presented, highlighting the importance of designing multiple operating modes to improve system availability. Several improvement measures presented in this paper provide guidance for using AC drives to complete rolling mill reduction system control tasks. Keywords : APC, Electric Pressing, Impact, Frequency Converter, Vector Control, AC Drive 1. Introduction To further improve production capacity, reduce equipment failure rate, and optimize the process equipment configuration of the original production line, Jinan Iron and Steel Group Corporation converted the original three-roll Lauter mill at Jinan Iron and Steel Medium Plate Plant into a four-roll mill in November 2004, and implemented full AC drive in the mill system. After a series of scheme demonstrations, the main drive of the mill adopted Siemens' AC-AC frequency converter system, and the most important auxiliary drive, the four-roll electric pressing system, adopted AB's Impact frequency converter. To improve transmission performance, a master-slave control mode was adopted when the pressing operation side and the drive side were linked. To improve the automation level of the system, the electric pressing APC function was required. 2. Control Concept Electric pressing APC control is the foundation for realizing the automatic rolling process of the mill. It is generally used as the inner loop of AGC control in the finishing mill system. However, when the AGC system fails, the positioning accuracy of the electric APC should be able to guarantee the basic positioning requirements of the pressing system and meet the thickness accuracy requirements of some product specifications. The electrically operated pressing (APC) system can automatically adjust the position of the pressing screw to the target value pre-given by the process machine or HMI as quickly as possible, keeping the difference between the adjusted actual position and the target value within the allowable error range. The positioning accuracy requirement for the roughing mill pressing APC is ±1 mm. [b][align=center]For details, please click: Variable Frequency Drive-Based Electric Pressing APC Control for Roughing Mills[/align][/b]