Research On Virtual Design Of Large Size Cold Ring Rolling Mill

Ring rolling is a high-efficiency and high-quality advanced manufacture technology, with which the diameter of the ring increases as the ring cross-section decreases by ring rolling mill. It has many characteristics such as saving forming force and production cost, increasing utilization ratio of energy and material, rising productivity, widening processing range of ring products etc. As a result, ring rolling has become the main manufacture method of many kinds of superior seamless ring parts.It was submitted that the design requirements of large size cold ring rolling mill which can produce ring part with utmost diameterφ350mm, and utmost width 70mm. The task of virtual design of the machine was accomplished, and the 3D models and the prototyping were established.With the modularization design way, CAD models were created by using the 3D software Pro/E after rolling process parameters and structure parameters of key components. The CAD models were made up of eight main components, such as spindle assembly, mandrel assembly, guide roll assembly, sliding block, feed system, manipulator and housing assembly. These components were assembled into the CAD models of the machine according to inter-part orientation.The key components were analyzed by using the finite element analysis software ANSYS. The distributing regulations of stress and strain of the spindle, ball screw and housing were found, and also the design weaknesses. Corresponding modifications were proposed. Dynamic characteristics of the spindle and ball screw had critical influence on the machine dynamic characteristics and the manufacture precision, so the kinematical analysis was accomplished on them, the free frequencies were gained. The results of modal analysis indicated that the free frequencies of the spindle and ball screw were high enough to avoid the resonance region, and the resonance vibration wouldn't happen. In order to make the structure more compact, more proper, by choosing the weight of housing as objective function, the optimization of the housing was accomplished. Guaranteeing enough rigidity and strength, the weight of the housing was reduced by 15.6%, the width of the side plates was reduced by 16.7%, the width of the bottom plate was reduced by 16.7%, and the radius of the bar was reduced by 25%.The virtual prototyping was established by using the multi-body system dynamic simulation software of ADAMS. After setting feeding parameters according to rolling process, kinematical simulation was done, the working process of machine was observed, and the curves of kinematic characteristics were gained during the working cycle process.The hydraulic feeding system principle was designed, and the main hydraulic parts were chose according to working characteristics of the cold ring rolling mill. The system block diagrams were established by using MATLAB/SIMULINK. By adjusting K_I,K_P and K_D of PID controller, the dynamic characteristics of the hydraulic cylinder system was analyzed which was controlled by proportion servo valve, and the system step response curves were obtained subsequently. It indicated that the effect of the control system was much better when K_P was equal to 0.6, K_I was equal to 0.1, K_D was equal to 0.0008.