Forming Process Control And Path Planning Of Truss Structures Based On Cold Metal Transition Technology

With the development of aerospace,aviation and other fields,strict requirements are put forward for the structure and function of aircraft,satellites and other parts.The truss structure has shown great potential in the application of structural function integration technology.It can be used as a multi-functional excellent design carrier to realize the organic integration of various functions such as load bearing,heat protection,stealth,and variants.Cold metal transfer technology(CMT)has the advantages of small heat input,small deformation,no spatter,good bridging ability,uniform welding seam,high welding speed,and low operating cost.Combining the CMT welding process with the arc welding robot technology,the truss structure is piled up using a point-by-point additive manufacturing technology based on cold metal transition.This subject is mainly researched from two aspects of the truss structure forming process and forming path.First of all,the process parameters of the truss column are formed to obtain the optimal process parameter range of the truss structure forming.On this basis,the welding torch piled up the columns with different inclination angles in the direction perpendicular to the substrate,and the columns collapsed obviously.Aiming at the collapse of the truss column,a force analysis and mathematical model is established.The model can accurately calculate the welding torch posture corresponding to the column with different tilt angles,and then control the force of the truss column.Aiming at the forming problem of complex truss structures,a truss structure intersection forming strategy is proposed.This forming strategy can reasonably plan the welding torch posture and forming path sequence,and ensure the forming size and forming quality of complex components.Facing the problem of welding torch stacking sequence when the multi-branch structure converges to one point,a multi-branch structure forming strategy is proposed,which can make the convergent point of the structure firmly connected without gaps and other defects.Then,aiming at the collision phenomenon between the welding torch profile and the truss structure,the cylindrical bounding box method is used to simplify the welding torch and the truss column,and a cylindrical collision model is established.The model can effectively detect whether the cylinders intersect,and then determine whether the welding torch and the column collide.If a collision occurs,the welding torch is abstracted as a rectangular parallelepiped composed of nine straight line segments intersecting the cylinder,and the interference size of the welding torch and the column is calculated by the method of intersecting the straight line segment and the cylinder,and the obstacle avoidance strategy angle Δβ of the robot is obtained using the law of cosines.The three-dimensional space ant colony algorithm is used to optimize the forming path of the truss structure.The pheromone update principle,heuristic function and search mode of the spatial ant colony algorithm are designed and improved.The algorithm has strong search ability and improves the efficiency of path planning.Finally,through the accumulation of typical truss structures,the test results show that the force analysis of the truss structure and the mathematical model and the truss intersection forming strategy can effectively control the shape and size of the molded parts,and the size error is within 2mm.The collision model of the welding torch and the truss structure and the spatial ant colony algorithm can avoid the collision of the welding torch and the column,improve the efficiency of forming path planning,and ensure the forming quality of the formed part.