Finite Element Simulation For Axis-Thrust Bending Process Of Thin-Walled Tube

Thrust-bending process of thin-walled tube using local induction heatingcan realize flexible manufacturing and automatic production, so it is widelyutilized in the fields of aviation, aerospace and automobile industries and so on.However, in the thrust-bending process, there exist failures of dehiscence,wrinkle, wall-thickness extreme thinning and cross-section flatting and so on,because of non-uniform temperature field around the tube. Therefore,thrust-bending process of thin-walled tube is complex. There exist a lot ofinfluence factor and have no perfect theories currently. Studying ofthrust-bending process of thin-walled tube have important instruction meaningfor deciding reasonable technical parameters and completing the pieceefficiently.According to the basic theory of plastic, the mechanical models of tube ofdifferent simplified patterns have been analyzed and compared;the qualitativerelations of thickness reduction and ellipticity have been discussed. Assumptionthat pivoted arm hinged with pipe, axis-thrust bending problem has beenresolved;the result of moment of flexure expression and neutrosphere positionconform to actual instance much more.Mechanics of cross-section flatting of bending tube has been analyzed,obtaining the method of controlling cross-section ellipticity by modifyingtemperature fields distribution in circumference of pipe. It can raise theresistance of part transformation metals that set transformation temperaturedifferently in two sides of inside and outside of bending pipe and two sides oftop and bottom of bending pipe, attaining to lower an oval rate of tubecross-section.Bending thin-walled tube process of loading transient temperature field hasbeen simulated by finite element method using ANSYS/LS-DYNA.Non-uniform cooling type around circumference direction has been studied, it iscool off the top and bottom side vertical the tube bending surface in theinduction heating area and non-heating area, it can obtain the variation rules ofellipticity of cross-section and thickness reduction with bending angle.Otherwise, controlling axial direction width of deforming area can attain to evensmallness ellipticity of cross-section, comparing without controlling width ofheating areas. Reducing speed of pushing forward can change axial directiontemperature distribution of pipe, also acquire small value of ellipticity ofcross-section. Synthesize a comparison to various cooling method, cooling thetop and bottom side vertical the tube bending surface in non-heating can obtainsmall ellipticity. The data curve and the relations of tube wall thick reduce andellipticity of cross-section has been analyzed. While an oval rate of the materialcross section to lower, the thickness reduction increase immediately, two varietytrends of are contrary.