| Thin-walled parts are widely used in aerospace,automobile manufacturing and other industrial fields because of their light weight and compact structure.At the same time,because of its small wall thickness and irregular structure shape,it is difficult to ensure the quality of thin-walled parts in traditional processing and high processing cost.Firstly,on the basis of the traditional hierarchical algorithm,the geometric model of the formed section is modeled and the mathematical model for the prediction of the hierarchical height is established to calculate the estimation of the hierarchical height.The offset of prefabricated parts in Z-axis direction is calculated by the edge curve equation,and the height compensation prediction is carried out to improve the stratification accuracy,and the optimization of the stratification algorithm based on the height prediction is realized.For complex thin-walled parts,rational B-spline curve is introduced to calculate the welding trajectory.Through rational B-spline function definition formula and rational B-spline curve fitting method,the trajectory calculation algorithm is designed.Based on the three-dimensional model of prefabricated parts,the trajectory curve equation is extracted and the forming path is automatically generated.Then,a fast calibration method is proposed,which assists the rapid calibration of special points.Through the quaternion pose matrix obtained from the model prediction theory,and according to the vector rotation theory,the calibration of the added material manufacturing forming system is completed.The off-line programming flow chart is designed.Robotstudio,an off-line programming simulation software,is used to extract the path automatically by combining the calculated path curve fitting equation,and VB programming software is used to generate Rapid language program for robot forming.Using the arc discrete local approximation algorithm,the section curve equation of complex thin-walled parts is differentiated,and the quaternion matrix is calculated to realize the automatic adjustment of welding torch position and posture to ensure the forming quality.Further,aiming at the problem of forming dimension accuracy and quality control of forming surface,on the basis of welding process test,the forming rules are recorded,and the forming accuracy is controlled through process improvement.The matching curve of welding parameters is obtained and the appropriate welding parameters are selected to meet the requirements of forming accuracy control.Reciprocating welding mode and special two-step welding mode are adopted to optimize the forming process of thin-walled parts manufactured by adding materials.Aiming at the problem of high welding height at the intersection of thin-walled parts with intersection characteristics,the optimal path is designed based on the idea of opposite and tangent forming path to minimize the error caused by stress concentration and thermal accumulation.At the same time,the forming law of variable cross-section is explored to verify the feasibility of thin-walled parts with variable forming width in the forming system.Finally,some typical thin-walled parts are tested and validated.The experimental results show that the accuracy of the optimized hierarchical algorithm is controlled to less than 1 mm,and the welding path planning and trajectory automatic extraction are realized.At the same time,the forming quality is obviously controlled by process optimization and real-time adjustment of the robot terminal position and posture. |
