Research On Process Parameters And Straightening Process Simulation Of Ten-Roll Thin-Walled Tube Straightener

With the rapid development of the national economy, processing quality of mechanical products is getting more and more attention by people in some areas. Because of the quality of light, good rigid, and sufficient strength and toughness, thin-walled tubes are widely used in aviation, aerospace, nuclear, defense, automotive and other industries. Because all walks of life pay more attention to the safety and reliability of mechanical products, so people made very high quality requirements on the thin-walled tubes. However, in the process of rolling,forging, machining, thin-walled tubes will occur different levels of bending or distortion deformation, resulting in some errors of longitudinal straightness and cross-sectional roundness. In order to repair various errors of tubes and obtain qualified products, we must do straightening process to the tubes.Currently the straightening device which most widely used in the tube straightening is the cross-roll straightener, including two-roll straightener and multi cross-roll straightener. The two-roll straightener mainly relies on the roll type when straightening, which has high straightening precision but low straightening speed and low production efficiency, In addition, the design for roll type is complicated, which increases difficulty for the research. Because of the staggered bending effect of the cross-roll straightener’s rolls, it can produce enough plastically bent,so as to achieve the purpose of straightening. The straightening speed is high and the straightening precision can meet the requirements, so it is particularly suitable for the straightening of the thin-walled tube.However, the existing proprietary thin-walled tube straightening equipment is less in domestic. When using ordinary multi cross-roll straightening thin-walled tubes, it may produce a lot of straightening defects due to the thin wall, so the rejection rate is high. So it is necessary to make a detail study on straightening process of the thin-walled tube, in order to developing a thin-walled tube straightener with high-precision and high-efficiency. Based on the existing straightening process theory of thin-walled tubes, this paper doing some study on ten roll thin-walled tube straightening by using of theoretical study and finite element analysis method.Firstly, this paper analyzes lateral crack, cross-sectional distortion and inside wrinkling defects which occur during bending of thin-walled tubes. It analysis the generation mechanism and influencing factors of the defects, which provides a potent theoretical support for the formulation of the straightening program.According to the design method of roll curve for cross roll straighteners, this paper designs straightening roll for the ten-roll thin-walled tube, and establishes a model for the ten-roll thin-walled tube straightening.Straightening process parameters can influence the final straightening quality of the thin-walled tube. After analyzing and calculating, this paper selects the optimum straightening process parameters for the thin-walled tube.The finite element software ANSYS/LS-DYNA is used to simulate the straightening process of titanium seamless thin-walled tube. At last, this paper analyzes errors of longitudinal straightness and cross-sectional roundness of the straightened tube, verifying that the ten roll thin-walled tube straightening model and the design for straightening roll is reasonable which established in this paper. Through the simulation analysis on several different numerical sets of straightening process parameters, this paper verifies the correctness about the selection of straightening process parameter, thereby obtains the rules that straightening process parameters effect on the final quality of the tube and provides some reference for the study on new thin-walled tube straightener.