Research On Key Technology Of The Intersected Pipe Welding Robot

Robots have been widely applied to the welding field with the development of technology. In the petroleum, the chemical industry, the nuclear power, the boiler and the pipeline project, there are a large number of intersected pipes welding, the current robots cannot meet practical needs, and the nozzle welding tasks are basically completed by manual welding operation, which has characteristics of bad environment, high labor intensity, low efficiency, and poor quality. Aiming at the limitations of the manual welding and the robotic welding, an intersecting pipe robot with special structure was developed. Based on a comprehensive summary of the latest research, the related key technologies were researched, the main results outline as follows.According to the welding particularity on the intersection of intersected pipe, the multi-freedom robot with special structure was developed based on analyzing the technical features and application foundation of the current robots. By means of other positioning device, the welding operation can be carried out while laying the robot over the top of weldment. A swing mechanism of the gun drived by steel belt was developed according to actual needs.The control system of the nozzle welding robot is considered the CAN-bus as network, PC as the core of the open system, PC as data processing and single chip microcomputer as nodes control, the hardware platform of the welding robot control system was integrated, the relevant hardware and interface design were achieved, a more open system hardware and software platform were established.The motion model of the welding robot is a theoretical basis for welding automation, aiming to the joints relationship of the welding robot developed, the robot kinematics model was established according to the D-H coordinate, and the inverse kinematics model was solved by using analytic method; the Jacobian, the force Jacobian and dynamic model were established, all these work provide the foundation for design and development.The resistances against the wire feeding process show serious nonlinear characteristics, the state observer to observe the interference and feed-forward loop were adopt, which can improve the speed respond, the secure and reliable wire feeding was accomplished by using Fuzzy-PI control. The welding speed control model was established based on the mathematical intersection model, the motion control of each node were realized, and the human-machine interface for system control functions was developed.The welding experiments indicate the automatic welding of intersecting line can be achieved, the weld was formed well, and the system operates stably and reliably. The welding experiment shows that the practicability and feasibility of welding robot system are reasonable, and the welding robot has the character of high efficiency, good reliability, reducing the labor intensity of workers, and ensuring welding quality.