Research On The Equipment And Methods For Straightening Thin-walled Tubes Of Tantalum And Niobium

A tube of Tantalum and Niobium is an important product because of its strong thermo stability and corrosion resistance, and widely used in aviation, aerospace and nuke industry. The demands for its quality and quantity are higher as these industries develop. But the quality is poor because a straightening machine is backward. Therefore it is necessary to develop a new equipment for meeting these demands.A straightening machine with twelve rollers is developed in this paper according to design parameters, the design demands and comparisons of straightening methods for multi-inclined rolls and two-inclined rolls. Firstly, mechanical analysis is obtained through calculation, then deformation law and requirements of creating flaws are analysed. Thirdly, design methods of the straightening machine for thin-walled tubes of tantalum and niobium are decided. Fourthly, overall plan is established and parameters are calculated. Force conditions and deformation of the frame during straightening analysed obtained by using ANSYS, distribution laws on stress and displacement of the frame are obtained when it is working, and suggestions are proposed for improving the functions of frame and quality of tubes.Also, the structure and design plan of the straightening machine are introduced, and the schematic diagram of hydraulic system is designed. Hydraulic system and electronic control system are devised according to characters and demands of the machine. The major components of hydraulic system are chosen, whose parameters are calculated and checked. 3D model of the system is established by using Solidworks. The principle of the control system, functions of components and the reason for choosing them are simply illustrated.Mathematical models of hydraulic system are established by using transfer functions and differential equations respectively, and PID controller is used to adjust the system. The curves of rod placement, flow at entrance and exit, and pressure in two chambers of cylinder are got by using Matlab/Simulink and DSHplus respectively, and these curves are compared. It is understood that these results are similar. But, numerical stability of Simulink model is poor whose fluctuation is large, and it is not suitable for analyzing high-frequency signals. On the other hand, DSHplus model can be used to simplify calculation process, and its numerical stability is high.PLC system for hydraulic system is designed in this paper. The program, human-computer interface are designed, dead zone of the proportional valve is compensated, and the curve of rod position is obtained. Based on magnitude margin and phase margin, relay feedback algorithm is adopted for setting PID.Then the program is made by Matlab for accomplishing the algorithm. At last, the advantages of Simulink and DSHplus are integrated for simulating the hydraulic system, and this algorithm is verified.