Flow control of servo valves for tension cylinders based on speed feedforward

The workpiece was held by two grip holders with assembled hydraulic tension cylinders to move and hold tension for hydraulic-tension reversible experimental cold mill. Flow control of servo valves was designed in the control system to keep steady tension when the cylinders were stopping or moving. Only a tension feedback closed loop was not sufficient when the cylinders were moving. A suitable combined controller consisted of a speed feedforward controller and a tension feedback controller was developed to control the flow of serve valves with good performance. This technique has been applied successfully in a 450mm hydraulic-tension experimental cold mill in Taiyuan Iron & Steel (group) Co. LTD.