| AFA3G fuel assembly is the most advanced pressurized water reactor fuel assembly in the world.At present,mechanical expansion is widely used to connect the guide pipe and annular tube.The expansion tool is an important part in the manufacture of fuel assemblies,the central unit of which is the expansion joint.But the expansion tool is easy to break,and the destruction mainly occurred on the round hole and the expansion joint.It is now mainly imported from abroad,and costs highly.To resolve this problem and reduce the manufacturing cost of fuel assembly,this paper studied a manufacture technology of the expansion tool,which is used to connect the M5 guide pipe and annular tube in t he fuel assembly manufacturing process.In this work,based on the analysis of the performance and structural characteristics of the expanding tool,the design of the material,the analysis of the structural characteristics and the design of the preparatio n process of the expanding tool are carried out.The preliminary material heat treatment and performance test were carried out.Combined with the structural characteristics,material performance characteristics and use requirements of the expanding tool,t he three-dimensional modeling analysis of the expanding tool was carried out,and the preparation technical difficulties of the expanding tool were determined.The specific preparation process scheme of the expanding tool was established based on the material performance characteristics and processing technology.The processing tools and parameters were determined through the preparation test.The tools are processed and prepared,and the corresponding surface chrome plating is carried out.The expanding test fixture and method are designed and established,and the simulation expanding test is carried out.Finally,the validity of the preparation method and the applicability of the expanding tools are proved by the preparation test and expanding test of small batch expanding tools.The test results show that the material properties of the expanding tool can meet the requirements after the 90MV8 steel is heated in vacuum,quenched in solution oil at 950 °C / 20 min,and tempered at 360 °C / 1 h.The processing route and special cutting tools designed an d manufactured by combining the heat treatment process and machining process are suitable for the batch processing and manufacturing of the expanding tool The position tolerance,dimension tolerance and surface qu ality meet the requirements of the design drawings;the chromium plating layer can be prepared on the surface of the expanding tool after the hard chromium plating process and parameters optimization;at present,the first batch of products have been devel oped and delivered for use,and the test results are good after the expansion process test verification.The self-developed preparation process of the expansion tool can realize the self-directed production.The study not only lead to reduce costs but also solve the problem of dependence on import effectively. |
