Path Generation Technology Of Measuring & Welding For 3-D Butt Joint Based On Multi-constraints

Laser welding boasts many advantages, such as quick speed, good accuracy, high energy, and fine welding quality. As a promising welding approach in the 21st century, it is widely used in the aerospace, vehicle, shipbuilding, chemistry, electronics, and so on. Welding path generation is an important technology of laser welding, which has been widely utilized and studied in recent years. On the basis of the latest theoretical research and applications at home and abroad, this paper studies the related theories and key technologies of 3-D butt joint's path generation and dynamic compensation, aiming at solving the major problems which exist in laser welding & measuring path generation.According to the geometric characteristics of 3-D butt joint, the welding strategy is studied, and the motion strategy of 5+2 axes laser welding & measuring machine tool is analyzed. With homogeneous coordinate transformation, the machine tool's kinematics model is established, and the form-shaping function matrices of both welding torch and measuring device are derived, which are the foundation of joint modeling and path generation.To improve the accuracy and efficiency of manual teaching, an automotive teaching method using 2D/3D vision sensor is proposed. Though building the Joint space and Cartesian space's mapping, the positive and inverse calculation of measuring device are implemented one by one. Then, automotive teaching measurement of 3-D butt joint is realized.The path generation method of continuous measurement with multi-constraints is studied by using the joint's rude model. Though curve discrete and control point interpolation, the path of continuous measurement is generated. Meanwhile, the measuring speed is planned considering the balance between accuracy and efficiency. Then, the precise joint model which can be used for real-time welding is built.In the real-time welding process, measuring is implemented simultaneously. To meet this functional requirement, the welding path generation method based on coupling constraints is studied. Through matching the welding point and measuring point, the decoupling calculation is realized. Then, welding and measuring can be implemented at the same time.To compensate the welding thermal deformation, a dynamic compensation method is studied. By using positive calculation of the measuring device and inverse calculation of the welding torch, the motion compensation value of X,Y,Z axis are calculated to compensation value of process parameters are obtained to compensate the joint clearance's error.At last, on the basis of research work and achievements mentioned above, an initial CAM system oriented at laser welding of 3-D butt joint is developed, which perfectly realizes laser welding and measuring path generation.