The Bending Quality Research Of Thin-walled Pipes In Small Bending Radius

The bending parts manufacturing by pipes are widely used in various industrial production which because of light weight,high stiffness,structural stability and a series of excellent characteristic.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 which has been the urgent need to solve technical problems.Because stainless steel material has good corrosion resistance,impact resistance and beautiful appearance and the pipes with small bending radius need small space occupation,it is in good graces of people,so study this kind of pipes have very important significance.In this paper,based on the theoretical basis of the plastic molding tube bending,using display dynamic analysis software ANSYS/LS-DYNA simulation analysis of thin-walled tubes,and experimentally verified.The main work and results are as follows:1.For the mechanism of the mandrel structure,proposes the mandrel structure simulation modeling strategies.Respectively,making a numerical research on thin-walled pipes which outside diameter of 37.4mm,thickness of 1mm,carried out in three different forms of modeling and simulation of the mandrel,proposes the mandrel structure simulation modeling strategies.And in contrast with the experimental results,discusses the rationality and application range of these three mandrel structure models.2.Propose using the equivalent method to reduce the simulation time,improve computational efficiency.Due to a large amount of highly nonlinear simulation calculation and time-wasting for thin-walled tube bending process simulation,so the paper deduces the basic formula of the equivalent method,and proposes using the equivalent method to reduce the simulation time,which combines coordinate translation with mass scaling for bending process simulation analysis,thus effectively improving the efficiency of the simulation.3.Study the mould structure parameters and process parameters on the quality of bending of the thin-walled pipe.Respectively,making a numerical research on thin-walled pipes which outside diameter of 120 mm,thickness of 2mm.For the phenomenon which the small bending radius pipes are easy to produce defects,proposes using the variable parabolic core head model to build the mandrel structure,to achieve better pipe wall support.While studied on the impact which the bending parameters such as the number of core head,the core head diameter,the thickness of core head,the gap between the moulds and the pipes,the coefficient of friction,a bending and speed springback compensation,etc on bending quality.4.Experimental verification.According to the simulation results of the analysis,design and processing bending mold,set a reasonable parameters,while let the core connectors-super elastic body model translate into the actual production mandrel connectors-wire rope,get the wire rope with the actual parameters of the model production requirements,and then make bending experiments.The simulation results compared with the experimental results show that the two results are basically identical,to verify the feasibility of the new mandrel model and reliability of the numerical simulations results,and then provide theoretical guidance for the actual production.