The Research On Velocity Control System Of Walking-beam-type Reheating Furnace In Silicon Steel

Now, walking-beam-type reheating furnace is widely used in hot reduction of board, bars and wire stock. It transports hot or cold billet steel step by step in furnace and heat it. Because the hydraulic system of walking furnace moves in program loop and the walking furnace have the characteristics as follows: low step walking periodicity, high velocity, heavy overpass loading, synchronizing multi-cylinder, continuously work, high reliability. We consider of the process requirements of walking furnace, therefore, it needs to design the velocity control system of walking beam type reheating furnace.According to the naked problems in practicable production process of the No.4 walking-beam-type reheating furnace hydraulic system in hot rolling plant, WuHan Iron & Steel(Group) Corp. , the paper analyzes the designing idea and technical measures of rebuilding hydraulic system, makes certain of reliable reform scheme in reality. It upgrades main pump, slippage system, valve station, redesign system circuit to adapt to modern production, increases output and quality.Referring to walking-beam-type reheating furnace's velocity feature, consulting the velocity control modes which have been put into production in home and overseas, combining the practical production condition and work requirements, on the base of analyzing and comparing all kinds of control modes' merits and faults, the paper makes certain of the velocity control version which adapts to the system. It is capacity speed governing circuit of pump controlling cylinder. In order to ensure walking beam run in preset rate curve, to avoid happening some accidents in system, for example, the big inertia will result in the ahead impacting of walking beam, the system uses advanced electro-hydraulic control technology. In the walking beam's velocity electro-hydraulic control system, proportional variable pump is the key components. It depends on the control signal which given by electricity control system to drive proportional directional valve and control the variable pump's variable piston moved to relevant position after power amplification by proportional amplifier. The main pump discharges flow which needed to operate the whole system. At the same time, the pump's sloping cam plate angle is measured and translated into electronic signal of closed-loop control. The flow control accuracy is high. In this velocity control system, it makes full use of the merits of electro-hydraulic proportional control, replaces axial plunger variable pump controlled by four-grade-pressure valve block with high performance electro-hydraulic proportional variable pump. The control method changes from mechanical-hydraulic servo controlling to electricity control. It simplifies hydraulic system and flow control system, reduces fault, realizes wholly standardization of system, increases the control performance and production efficiency highly of system, raises economic benefits andsocial benefits.The paper analyzes the fundamental characteristics of walking beam reheating furnace's velocity control system in theory, and exactly builds the mathematical model of walking-beam-type reheating furnace's velocity control system by mechanics analysis. It analyzes capacity speed governing system's dynamic characteristic and anti-interference performance in load. It also simulinks the system. It provides theoretical basis for further research on electro-hydraulic proportional velocity control system. Moreover, it proves capacity speed governing circuit perfectly satisfied walking beam's processing curve and qualification which needed in practical production by doing experiments and field installation and debugging. The hydraulic control system which has reformed is reliable.In addition, referring to the reformed hydraulic control system put into production for a time, and some problems occurred, the paper represents the common fault in walking beam's working times and corresponding processing methods.