Design Of Hydraulic Pressure System Of 3000 Tons Automatic Hydraulic Pressure Straightener

In recent years, the progress of technology promoted the development of machinery industry and manufacturing, which is in heavy demand of hot-drawn seamless steel tube. Owing to the glancing flatness of mandril which is the key frock in the process of seamless steel tube has important influence on the quality of steel tube,and flexural deformation of axial parts during the heat treatment,so the importance of straightening technology and straightening machine is obvious. The traditional straightening process cannot satisfy the developing requirement of enterprise in efficiency, precision, straightening range and so on. The 3000 tons automatic straightening machine which is a fully automatic hydraulic straightening machine with the most pressure at present in China is designed for the Baosteel to straighten the mandril of seamless steel tube,which has universal significance to the straightening of large-sized shaft-parts.The basic structure and operating principle of YJD45-3000 automatic hydraulic pressure straightening machine is introduced. According to draw on the research findings and straightening technology at home and aboard, the hydraulic pressure system of is designed, which is based on the working condition of mass flow, mass pressure, inverting move and precise rolling reduction of 3000 tons automatic hydraulic pressure straightening machine. Comparing the analysis on different control schemes, the proportional direction value with high frequency response is used as the core control element. The applications of electro-hydraulic proportional control technology, which incorporated the advantage of both electricity and hydraulic technology, has good control performance, large transmission capacity and is convenient for computer-control. The other valves are mainly cartridge valve with large flow. The hydraulic pressure system of seaming chuck and secondary circuit are designed detailedly, and then the main valves and elements of hydraulic system are opted which is based on the calculation of pressure, flow and so on. At last the heat and pressure drop is checked to ensure that the system is reasonable design.The proportional position control system of seaming chuck is the important component of hydraulic control system of straightening machine and its configuration and principles are analyzed. According to the flow continuity equation and force balance equation, mathematical model of each link with the form of transfer function is established to deduce the transfer function block diagram of cylinder system controlled by the valve, and then the parameter value is worked out. MATLAB with its control toolbox-LTIVIEW and SISO Design Tool are used to accomplish the simulation and property analysis of the model. The stability and response rate of the system has been improved by PID controller and the error analysis of system is researched considering load disturbance, the result of which is satisfying. Modelling and simulation result provide theoretical basis and reference for the subsequent debug and run procedure. The straightening machine runs well and can achieve the technical motions and control demands during site debugging, which prove that the design and control scheme is feasible. Thus, the application study of electro-hydraulic proportional position system controlled by computer is valuable in theory and significant in projects domain to improve the control performance and straightening precision.