Structual Design Of A Type Of Intersecting Line Welding Robot With Four-DOF Paralleling Transmission

Industrial robots have been increasingly used in various fields of industry. Welding robots replace the workers to complete welding tasks frequently in the production. As a connection form, pipe inserting is very common in the chemical and boiler industry. It is difficult that the existing welding robot can meet the condition of large pipe inserting well for the complex structure of the weld seam. And the tasks are still accomplished manually in some case. So a robot specially designed for welding intersecting line is needed.By analyzing current status of the research on welding equipment for pipe inserting in domestic and foreign market, as well as the characteristics of the intersecting welding seam. The shapes and structures of robots that commonly used are being compared in coordinates type and the structure of machinery. The structure scheme of the robot is established with cylindrical coordinate and four-DOF paralleling transmission. Mathematical model of intersecting line, the model of weld seam posture and the torch pose are established.A structure of four-DOF parallel transmission-type welding robot for intersecting line welding is designed in this paper, which can achieve location adjustment and pose adjustment. The motion of rotation and lifting decoupled for independent and unrelated control in location adjustment. Differential wrist mechanism is designed by applying bevel gear differential, which has a simple control algorithm for pose adjustment. Each drive motor located in the rack, not to follow the trajectory of intersecting line, which optimizes the dynamic performance of the system and avoids the cable winding. The load of each degree of freedom is calculated and the type of motors are selected.The three-dimensional model of the robot is virtually assembled and simulated by Inventor software. It verifies the design of each part whether satisfies the assembly process, the motion space is whether enough and the movement whether occurs interference. The exactitude of the equation elicited is also verified by simulating. And the further ideas about the updated structure of the robot is proposed.