Research On Key Technology Of Cold Roll Forming Of Stainless Steel Side Shield Plate

Cold roll forming technology is developing rapidly in China,and the application of this technology to high-strength stainless steel is gradually becoming a hot topic for attention.Formed products can be used in many fields,such as automobile crash beams,B-pillars and other various parts,houses and other construction steel.The application of cold roll forming can gradually form stainless steel at room temperature into high precision,high quality,in line with the requirements of the product,effectively improving the operating environment,reducing labor costs and economic costs,so that economic benefits to maximize.This paper is based on the shape of the side cover plate of the high speed railway,simulating and analyzing the cold-forming of stainless steel SUS301L-ST material as a complex section.The forming process is mainly divided into three steps: the first step is to calculate,design and draw the flowers and rolls for the special section;the second part is to simulate the drawn flower and rolls pattern to verify the feasibility of the design,and then redesign or continue the analysis in response to the simulation results;finally,the process parameters of cold roll forming have a great influence on the product quality,so the parameters of the side cover plate are optimized to obtain a reasonable combination of process parameters,which can provide products with high forming quality and accuracy.The study and conclusions are as follows:(1)Design of side shield plate hole patternAccording to the basic principles of cold roll forming,the flower and rolls pattern of the side shield plate are designed and drawn.In the process of drawing the rolls,after several analyses and tests,a floating roll device is designed for the complex crosssection with asymmetry,large depth and long side legs in this paper,which successfully solves the problem that the large depth of the cross-section causes the upper roll to be oversized and overweight to affect the installation and commissioning,and effectively saves economic costs on the basis of ensuring the forming quality.(2)Establishment of finite element modelThe drawn flowers and rolls pattern are used to build a 3D finite element analysis model for cross-sections using the professional cold roll forming software COPRA.Integration of practical production experience of cold roll forming,the parameters of the side shield plate forming during the simulation were set up,including dividing mesh of the plate,setting boundary conditions,contact,working load,etc.(3)Analysis of cold forming process simulation resultsFirstly,the stresses and strains during the bite in process are analyzed and it is concluded that the sheet can successfully enter the rolls and continue to travel under these parameters.The bite in phase of the sheet during cold roll forming,the critical incremental step at which the sheet changes in equivalent stress and total strain at the important step of the node are evaluated.The stress and strain changes in the bite stage of the sheet,the key incremental step,and the key part nodes of the sheet during cold roll forming are analyzed.Secondly,in the actual production situation,four process parameters,namely,inter-distance,friction coefficient,roll diameter difference and forming velocity,were determined.And three levels were set up respectively,the stress clouds,edge longitudinal strains and forming angles during their forming process were analyzed.The resulting changes in parameters lead to changes in edge longitudinal strain values.The defect generation of the products could be reduced by the adjustment of process parameters.(4)Orthogonal experimental design and analyzeThe orthogonal experiments were designed for the above process parameters and their levels,and their effects on the maximum longitudinal strain values of the edges in cold forming of complex sections were analyzed.The results show that the roll diameter difference has the greatest influence on the maximum longitudinal strain value,and that an increase in the roll diameter difference can effectively reduce the strain value.The spacing of the passes needs to be chosen within a suitable range,too small a spacing is not conducive to the release of elastic deformation,too large a spacing will cause unintended displacement of the sheet and increase the cost of tooling.An increase in the coefficient of friction will help to reduce the maximum longitudinal strain on the sheet,but will cause defects such as scratches to the stainless steel material.Increasing the forming speed increases the strain at the edge of the sheet.The optimum process parameters for complex sections were finally successfully derived,providing a theoretical basis for practical production.