Research And Application Of Flexible Assembly System For Automobile Threaded Joint

The threaded joint assembly is a key technology and important process in automobile assembly manufacturing. Flexible assembly system of threaded joint is the main way to realize the complex threaded joint assembly process, improve assembly efficiency and ensure the quality of assembly. With the research background based on engineering application of threaded joint assembly in automobile assembly line, many problems in threaded joint assembly are detailedly investigated such as structure design, process control, coordinated control and process optimal control. The research and developing results are applied in the actual engineering field of threaded joint assembly, which is very important for automobile assembly manufacturing. The following research works have been completed in this dissertation:(1) The mathematical model of preload process for threaded joint assembly is established, relationship model of tightening torque and angle is established by preload equivalence principle for application of actual control system. In order to solve the problem of process assembly, different threaded joint assembly control technologies are developed and realized for threaded joint assembly.(2) Mathematical model of planetary gear transmission mechanism and PMSM AC servo system based on SVPWM is deduced. Dynamic simulation model of PMSM AC servo vector control system and mechanical transmission system is established. Speed control system of electromechanical coupling for AC servo tightening is simulated and verified.(3) Aiming at AC servo tightening assembly of single threaded joint, process control system of AC servo tightening assembly based on PFC is designed. Control algorithm and control system are proposed and verified by simulation. Aiming at coordinated control of multi-threaded joint assembly, dynamic deviation decoupling of coordinated control structure and control strategy of fuzzy parallel distributed compensation are designed. Application results of practical engineering prove that whole assembly control accuracy is improved.(4) Aiming at engineering application of automobile threaded joint assembly, network structure of assembly process control system based on distributed field bus is designed. By integrating of CAN bus, embedded control, database management, SPC and OPC network technology, flexible assembly system of threaded joint is designed which can replace similar imported equipment from abroad on the structure and performance. Distributed coordinated control of assembly process control and structure of network flexible assembly are realized for engineering application of automobile threaded joint assembly.(5) Aiming at process optimization of locking nut assembly for automobile driving taper gear assembly, a fuzzy positioning assembly controller based model predicted tightening is proposed. Multivariable target intelligent control for bevel gear axial pre-tightening force, locking nut tightening torque and angle position of driving taper gear is realized. Control accuracy and assembly efficiency are improved. Aiming at process optimization of pretension assembly for automotive tapered bearing, improved assembly method based on start friction online control is designed as control target of tapered bearing start friction. Not only a kind of problem for preloading assembly of tapered bearing and start friction moment of control on line is solved, but also consistency of start friction for tapered bearing preload assembly is improve. Integrated assembly structure of ABS wheel speed sensor based on online fault diagnosis is designed. Integrated assembly control of ABS wheel speed sensor based on online fault diagnosis is realized in assembly system of tapered bearing preload. Assembly process of the wheel speed sensor is optimized; length of the assembly line is shortened and assembly beat is improved.