Modification On Hydraulic System Of Twin Bar Rolling Mill Reheat Furnace

Tianjin Iron and Steel Group Company Limited, a major project for the strategic east-moving of Tianjin industry deployment, was built and put into operation successively from2003and processes a production capacity of6,000,000t hot metal, liquid steel and steel product. As an important constituent of east-moving project, Twin Bar Rolling Mill is designed to have a1,500,000t production capacity with prime rebar and round as main products.The reheat furnace of Bar Rolling Mill adopts heat regenerative burner technique which is the most advanced in China at present. The billet conveying is realized by beam bottom in combination of walking beam type mechanism and the mechanical movements are fully powered by the hydraulic system. The computer system controls the entire process of the hydraulic system. Equipped with proportional speed-regulating valves and constant pressure variable displacement pumps, the hydraulic system is characterized by features such as:fast response speed, highly precise control, good control flexibility, nearly free of energy loss, high level automation and the stable operation performance of the system. The synchronization precision of mechanical movement is controlled by synchronous motors and balancing valves, while a centering device is installed at furnace bottom mechanism to ensure billet alignment during conveying.Since being put into operation from2006, the hydraulic system of reheat furnace basically meets the process requirement of the production line. However, two big defects are found on it during production:inappropriate type of hydraulic pump was selected in design, which leads to frequent piston and sliding shoe breakage and failure; due to the complicated design of walking beam lifting control circuit, there is a conflict between the synchronous movement of hydraulic cylinders and the mechanism, while the big pressure loss in hydraulic circuit results in difficult cyclic movement adjustment.The paper proposes a modification plan basing on the above problems in the hydraulic system of reheat furnace. Firstly, proper hydraulic pumps are to be chosen and a group of accumulators are to be added to ensure that the system is supplied with stable and adequate energy. Secondly, the hydraulic circuit is to be adjusted and redundant components are to be removed to reduce pressure loss and eliminate the conflict between hydraulics and mechanics so that the mechanism can run stably and reliably.After the modification is carried out with advantageous conditions on site, the existing problems for production equipment are solved, which improves the reliability of equipment running and provides guarantee for the stable high production of the production line. Meanwhile, the production cost is lowered and fluid drainage reduced.