Bending Forming Research Of The Space Multi-thin-walled Pipe Based On ANSYS LS-DYNA

Thin-walled pipes are widely used in aerospace,automotive and ship building and other industrial production which because of light weight,high stiffness characteristic.Under the development of society and technology,people have higher quality requirements on the thickness of thin-walled pipe forming and bending.In the process of thin-walled pipe production,the outer pipe is prone to be thinning,even cracking,the inner pipe is prone to be wrinkling,the cross sections change and springback problems,meanwhile,for space-thin-walled pipes which without continuous line segments,the first bend will generate stress interference on the second bending,which be prone to cause mass destruction.In the actual production,based on the test method on the research of the thin-walled pipes,resulting in low efficiency and length cycle.In this paper,based on the large explicit dynamic analysis software ANSYS LS-DYNA,making a research on space-thin-walled pipes which outside diameter of 37.4mm,thickness of 1mm and compared experimental verification.The main work and research results are as follows:(1)Establish reasonable and effective pipe bending numerical model based on the characteristics of the pipe.Based on ANSYS LS-DYNA explicit dynamic analysis software,respectively,making a numerical research on thin-walled pipes which outside diameter of 33.7mm,thickness of 3mm,using solid and shell elements and compared experimental verification.Ultimately,perfect the analysis model to establish reasonable and effective numerical analysis model.(2)Presents a modeling approach on ball socket link mandrel.For large amount of calculation of physical contact mandrel modeled of ball socket link mandrel,presenting a modeling method which is presented with a rubber as a connecting unit and the core head part is rigid.Through experiments,it is shown that the modeling method can truly reflect the core head pipe bending motion state and the method is effective and reliable.(3)Studied the process parameters and die structure parameters on the quality of bending of the thin-walled pipe.Making a numerical research of bending factors on thin-walled pipes which outside diameter of 37.4mm,thickness of 1mm,including the number of core head,mandrel protrusion amount,the thickness of the core head,clearance between the dies and pipe,and obtained the high quality numerical mold by analysis the pipe forming factor.(4)Studied the space-thin-walled pipes which without continuous line segments cold bending forming technology.Making a research on the space-thin-walled pipes which without continuous line segments of 180° bending and 90° bending.Proposing a clamping die which possesses self-locking device,which changes the contact between the clamping die and the pipe.Compared to traditional fixtures,it improved the quality of pipe bending significantly.Studied the number of pairs of core head bend quality of space-thin-walled pipes based on the springback compensation method and obtained the merit conditions.(5)Bending experiment.Design and process the bending mold for bending experiment,based on the numerical analysis.Experimental results show that the clamping mold which proposed self-locking device,combined with the better process parameters,obtained the thinning rate,thickening,cross-sectional distortion rate which meet the requirements of high-quality space continuous pipe pieces.Through the Bending experiment,it shows the validity of the numerical simulation of continuous bending model.It shows great significance on the actual bending production and the research of CNC bending machine.