Study Of Forming Defects And Influence Factors Of Flexible Roll Forming

Comparing to the traditional roll forming, flexible roll forming can use the same production line to produce different profiles with variable cross sections along the length direction freely. So this technology offers high flexibility, low cost, forming material diversity, energy conservation and emissions reduction etc., which has become the focus in the sheet forming industry.As the flexible roll forming is more complex than the traditional roll forming, there are some forming defects occur in the forming process, such as over reduce of the wall, edge wave, spring back, warping which are also occur in the traditional roll forming and convex arc wrinkling which is only occur in flexible roll forming. In order to study these forming defects,5quality evaluation indexes are putted forward, namely wall thickness change rate to evaluate wall thickness change, outline stability factor to evaluate outline stability, PE11standard deviation to evaluate overall edge wave, angle difference to evaluate over bending or spring back, and convex arc wrinkling factor to evaluate convex arc wrinkling and its wrinkling degree.In this paper, forming defects and their influence factors of roll forming with variable cross-sections are studied by means of finite element simulation. In order to reduce the time of modeling and result data processing and the probability of human error, automated modeling plug-in and special post-processing module for roll forming with variable cross-sections are developed. Simply input the different parameters, a corresponding finite element model and its result data will output. Both of the pre-processing plug-in and post-processing module are secondary development of ABAQUS by python.In this paper, in order to research the geometrical parameters and process parameters’influence to the forming quality, an orthogonal experiment about geometrical parameters, including AL,R2,θ,γ,and an orthogonal experiment about process parameters, including L,N,τ,t are performed based on the pre-processing plug-in; and then the maximum equivalent stress, the maximum equivalent plastic strain, the maximum thickness incrassation ratio, the maximum thickness reduction ratio, shape factor, the maximum over banding angle, the maximum spring back angle, and the cc ivex arc wrinkling factor are extracted by the special post-processing module; and then the factors’affecting primary order and regularity are analyzed.On the special convex arc wrinkling, in this paper, the plate wrinkling formula for compressing is improved to predict the wrinkling onset and a special wrinkling evaluation factor is putted forward, the wrinkling evaluation factor fringe outputted from the finite element simulation proved that the wrinkling criterion is correct. And the influence rule of AL and R2, which is extracted from orthogonal experiment about geometrical parameters, also is exactly the same as the conclusion which is gain from the theoretical derivation.