Research On Longitudinal Seam Leaser Welder For Reactor Coolant Pump Can

Reactor coolant pump can is a key component of the canned reactor coolant pump, which is very difficult to process and assemble, due to its thinness, large aspect ratio and high accuracy. During the research of "the precision manufacturing of super-thinness and large aspect ratio shielded parts" which is one of 973 Projects, longitudinal seam laser welding is used to seal the rectangular nickel-base alloy sheet after its reeling for the manufacturing of the pump can. As assembly precision of the weld joint for laser welding is very high and the special shape of the workpiece is super-thinness and large aspect ratio, it is very hard to guarantee the assembly precision of the weld joint. In order to make the 973 Project research go smoothly, in this paper, an special purpose laser beam welder was designed for the experiment of longitudinal seam laser welding for the reactor coolant pump can.At first, technical difficulty of the workpiece's installation and clamping was analyzed when welding the reactor coolant pump can's longitudinal seam. The result was that how to assure the thickness direction dislocation error of the weld joint in the range of full length to the permitted extent. Then, according to the difficulty, "local deformation seam closing" method was proposed, through which the installation error was compensated using the elastic deformation of the weld joint. So, the installation accuracy of the joint was assured. Afterward, this method was investigated by numerical simulation using ANSYS, which was proved feasibility and three parameters was confirmed.Secondly, based on "local deformation seam closing" method, overall plan of the welder was designed using the method of systematical analysis. According to the functional analysis of the welder, it was divided into three subsystems which were fixture subsystem, weld-feed subsystem and rack subsystem, and 13 overall plans were obtained after design. Finally, the last plan was assured by comparing the 13 plans using grouping comparison analysis method.Lastly, the structure of three subsystems was designed separately in detail, in which the innovative techniques were in full application. The press head mechanism and suspended clamping structure were obtained which were new structures and assured the realization of the functions. Simultaneously, the key components of the structure were investigated by finite element analysis using CAD/CAE method to guarantee the reliability of the design. Eventually, a longitudinal seam laser welder for reactor coolant pump can was successfully designed.