Design And Research Of Manipulator Of Automatic Ultrasonic Testing Machine For Mooring Chain

Mooring chains are important components for offshore structure's mooring, especially for the deep-sea mooring chains must meet the requirements of high strength and sufficient toughness, so the mooring chains must dependable. Weld as the weakest section of the chain, it must inspecting strictly by ultrasonic in the course of production. Manual ultrasonic testing has the problem of the wrong or lost judgment, hence the design of automatic ultrasonic testing machine which inspects the chain's weld reliably is urgent. An adaptive manipulator is designed by theoretical study and simulation, which is the technical difficulty during the design of automatic testing machine. The main contents are as follows:1. On the basis of detailed analysis of the characteristics of ultrasonic testing space, the scheme of adaptive manipulator is planed. The adjustable crank-slider mechanism is used to simulate the chain's contour, and terminal detection system with 5-DOFs is designed, the profile deviation of the manipulator, the chain's manufacturing errors and the changes of the chain arm's cross-section is compensated by this system.2. The design of crank-slider mechanism for continuous path generation is based on positional structural error of the fixed link, and the target function and constraints is established, optimal results are obtained through optimization using GA(genetic algorithm). The simulation of path and error analysis by Matlab proves that the adjustable mechanism can track chain's contour well and realize the adaptive testing of the manipulator.3. Through the motion analysis of crank-slider mechanism, the movement model of linkage point and slider are established. The motion of the crank as the linkage point in the same rate is got by numerical method, and also whole movement sections of the crank is planed. The simulation indicates that the motion of the crank could achieve the desired results, and slider-crank mechanism can moved steady.4. The speed-changing mechanism which realizes the motion of the crank is designed, and motion cycle and follower motion programme of the cam are established. As the speed-changing cam mechanism with the longest working life and the minimum structure size, parameters of the cam mechanism is got by optimal algorithm. Lastly, the virtual prototype modeling of speed-changing cam mechanism is set up and realized kinematics and dynamics simulation, results indicate that the speed-changing cam mechanism realizes the expected motion programme well and has good kinematic and dynamic performance.A series of simulation results showed that the ultrasonic probe can adaptive testing chains in the same rate. And the speed-changing cam can achieve the required movement, meanwhile has good performance of kinematics and dynamics. Success of the study of adaptive manipulator can improve the testing precision and decrease the intensity of labor dramatically, also have great significance in realize of automatic ultrasonic testing of the mooring chain.