Design And Simulation Of Mechanical System For K/Y Pipe Joint Welding Robot

With the constant reinforcement of developing offshore petroleum resources,demand of ocean drilling and production platform is increased dramatically.There are lots of jacket joints from tubes to tubes in the ocean platform.At present,the welding efficiency of manual welding for this kind of pipe joint is inefficient.So high-efficient automatic welding of jacket joints has the important significance on pipeline assembly.This paper is based on the key project "K/Y jacket joints welding robot" of Tianjin science and technology support program,The existing conduit joint welding robots aim at orthogonal and small-sized tubular T-type joint weld assembly,so intersecting welding line with large-size and heterotropic type K/Y joints can’t be welding validly.In order to realize automatic welding of type K/Y intersecting welding line,to reduce labor strength in pipeline welding dramatically,to improve working environment,and to enhance welding quality and efficiency,a robot with type K/Y intersecting welding line was studied in the paper.On the basis of folly investigating research status of automatic welding robots in domestic and overseas pipelines,the author had the in-depth analysis of features in type K/Y intersecting welding line,established the mathematical model of heterotropic intersecting line for pipelines and feature coordinate system of intersecting welding line,proposed the robot structure design scheme combining cylindrical coordinate operating mechanism and two-degree-of-freedom differential wrist mechanism.The robot has five degrees of freedom,namely it not only can satisfy operating requirements for degree of freedom,but also can realize flexible obstacle avoidance.In order to ensure the strength of the robot structure,under the dangerous occasion,the mechanical property of the designed robot was analyzed.The author used Ansys Workbench FEM simulative analysis software to do static and modal analysis for the designed robot,verified structural strength and stability of vibration,optimized structural size,and completed design development for robot prototype on the precondition of ensuring that structural strength meets operational requirements.According to the linkage dimension of the robot prototype,the author applied D-H method to establish linkage coordinate system of the robot,solved positive and athwart kinematics of the robot,applied dichotomy to do trajectory planning on the curvilinear path of the intersecting welding line according to its welding technology,and used MATLAB Robotics Toolbox to do simulation verification on trajectory planning results.