Study On Thermal Spraying Remanufacturing Process And Coating Performance Of Used Machine Tool Shaft Parts

Machine tool remanufacturing, as a new manufacturing model of machine toolbased on the used resources, is not only the best solution to reuse the large wide of usedmachine tools all over our country, energy resources conservation, but forming a newremanufacturing and service industries, which has an important role in economic, socialand environment. With the development of machine tool remanufacturing industry, therewill be more and more remanufactured products going into service cycle, and the keypoint of these remanufactured products to win the customers and market recognition isthe their quality and service reliability. With the support of the12th Five-Year NationalKey Technology R&D Program (No.2011BAF11B09) and the Specialized ResearchFund of University Doctoral Program (20110191110005), thermal sprayingremanufacturing technologies and coatings service performance of retired machine toolshaft parts were studied, which may provide guidance for the remanufacturing practiceand service performance evaluation of machine tool shaft parts, the main research workis as follows:Firstly, the failure behavior characteristics of machine tool shaft parts, such asdeformation, fatigue, wear and fracture, and then corresponding damage detectionmethods are analyzed. Based on the failure characteristics analysis, the thermal sprayingremanufacturing process plan of shaft parts is designed, including the spraying processselection, coating system design and coating preparing.Secondly, the sources and formation mechanism of residual stresses of thermalspraying coatings are analyzed. Through the simplified model of shaft parts as thecylindrical, the stress field of coating in plane strain state is expressed by mathematicalformulas. Based on the finite element simulation software, the numerical simulationmodel of residual stresses for coating and shaft system was established, and the derivedequations and boundary conditions of temperature and stress field were deducted, thenthe residual stress detection technology was introduced.Finally, two spindles of the gear hobbing machines are chosen as the case study,plasma spraying and oxyacetylene flame spraying are used to remanufacture thespindles respectively based on the failure behavior characteristics analysis. The coatingsperformance of the two remanufacturing technologies are detected and analyzed. Theresidual stresses of thermal spraying coating systems are simulated by the finite element software ANSYS, and X-ray stress analyzer is used to measure and verify the numericalsimulation results.