Research On Roll Bending Of Profile For Variable Curvatures And Design Of The Control System

Variable curvature roll bending forming is a common bending forming process,which has the advantages of low cost,convenient replacement of rollers and strong versatility,and is suitable for the production of small batch bending parts.However,since the roll bending forming is a non-molded forming,the amount of springback of the formed part is very large,and it is difficult to control the forming accuracy.At the same time,the control system of roll bending forming equipment in China is backward at present,and it is difficult to produce a profile bending piece that meets the aerospace precision requirements.In order to build the roll bending forming control system and improve the precision of roll forming with variable curvature,this paper mainly carried out the following research work:Firstly,according to the theory of elasto-plasticity,deduces the expression of the relationship between the radius of curvature before and after roll forming and compensates the springback;Then based on the four-axis bending machine,the coordinate control system for the roll bending motion of the profile was established,and the mathematical model between the roller bending forming radius and the roller feed rate in the four process stages of roll bending,centering,pre-bending,continuous roll bending and unloading was solved.Furthermore,deduces the formulas for calculating the load on each roller and driving power of the driving roller in the molding process.Based on the above research,the roll-curvature control process for changing the profile from the digital model to the product was proposed.Secondly,the function requirements of the roll bending forming control system are analyzed,and the hierarchical classification and module division of the control system are determined.On this basis,the overall scheme of the control system was designed,and based on the overall functional requirements,the control system hardware was designed and selected.Finally,based on the TwinCAT and Visual C++6.0 environment,the development of roll-bending control system for the profile-changing curvature was implemented,and the control functions of the lower computer and the upper computer of the roll bending control system were realized.The lower computer mainly realizes real-time control functions,mainly including motion control function,IO control function,fault diagnosis function and auxiliary function;The upper computer mainly realizes non-real-time control functions,including roll bending forming control functions,database functions,finite element simulation functions,rebound influencing factors,defect inquiring functions,and auxiliary functions.Through the research on the roll bending control technology of the profile,the formula for calculating the radius of curvature of roll bending of the profile is derived,the control equation for roll curvature with variable curvature is established,the process flow of profile curvature control is designed,and the roll curvature control system with variable curvature is designed and implemented.It lays the foundation for further improving the precision control of roll forming.