Research On The Four-roller Forming Process Technology

Sheet metal bending forming technology is more and more important in manufacturing of modern society,various bending parts play great roles in all fields.Four-roller plate bending machines with the small remaining pre-bending edge,saving material occupy more and more important position in plate bending machines.At present,the forming accuracy and efficiency of multi-pass forming in four-roller plate bending are low.Therefore,processing technology of four-roller plate bending and deflection compensation technology of lower roller are studied in this dissertation.The main contents of this paper are as follows:(1)The relationships between bending moment and curvature of bilinear hardening model plate in the loading and unloading stages were derived.According to the unloading theorem,the formula of springback was derived.The force conditions of the plate during the process of pre-bending and continuous bending were analyzed theoretically,and the analytical model of pre-bending and multi-pass bending was developed.(2)The finite element models of forming and springback were established.Based on the models,the influences of roller speed,plate thickness,material property on forming curvature radius were investigated.The orthogonal experiment was designed to study the different influencing factors and the interaction between factors on multi-pass forming.(3)The driving torque force model of multi-pass bending was developed.Based on the model,the influences of the number of bending passes on the bending force and driving torque were discussed.The analysis programs of factors on multi-pass forming were designed to study the number of bending passes and interval values of two successive finished bend radius on forming results.The effects of different forming paths on the forming results were analyzed,and the forming path was optimized.(4)Aiming at the flexural deformation of the lower roller,a four-roller bending deflection compensation device with a freely adjustable position was designed.The deflection of the lower roller caused by gravity,forming force and supporting load were analyzed.Based on the analysis,the supporting load was calculated.