Theoretical And Applied Research Of Mechanical Parts Thermal Deformation In Uneven Temperature Field

With the development of manufacturing and testing techniques, especially with the development of Nanometer technique, the thermal deformation of mechanical part has become a pivotal research problem in these fields for improving accuracy. The paper summarizes domestic and abroad achievements in this area. On the basis of now available achievement, Under the subsidization of several projects, We systematically study theories of heat conduction, elasticity and thermal stresses. Temperature field, thermal stresses and thermal deformation of mechanical parts are obtained in working and manufacturing conduction. Some new achievements and innovatory ideas are presented.The main contents of the thesis includes as following:On the basis of synthetically analysis about domestic and abroad achievements, the thermal deformation in uneven temperature field is discussed. A new method that is dissimilar to the method in even temperature field. has been adopted. Machinery in working is situated in uneven but steady temperature field frequently, so, the research of uneven fields is provided with more significance than it has in even fields. The results and the results in even temperature fields will lay a more comprehensive and intact foundation about the research of thermal deformation.The paper provides some temperature fields, which are common used in machine. Three dimensional temperature fields about driving shaft is deduced, at the same time, thermal deformations theory analysis about three dimensional temperature field has been accomplished, the conclusion are proved by experiments, there is a lack of reports about an identical or similar achievement in domestic and abroad.The paper selects two components (the fit of hole and shaft, rolling bearing) as breakthrough and studies their rule Of thermal deformation. The influence of thermal deformation on clearance fit and interference fit are discussed. A new tolerance design method that compensates thermal deformation is presented. The conclusions lay a foundation about bringing forward thermal fit theory; The paper analyses the influence of temperature variation, assembling stresses and rotating velocity on the windage variation, The conclusion will provide suitable original widage from working temperature and borne, so as to make bearing work in optimal working windage. secondly.prestressing is another characteristic in bearing application, after comprehending thermal deformation of bearing and shafting ,the preliminary stress can be determined. The thermalNIvdeformation acts as an unfavorable factor in driving shaft prestressing customarily, but now the thermal deformation becomes beneficial factor in prestressing and makes shafting system work in optimal prestressing conduction. The paper gives out equation to calculate preliminary stress; it can be applied in high accuracy shafting design and assembly.The main factors influencing thermal deformation are summarized, the paper studies the residual stress, which brings about deformation and destroys accuracy primarily. The paper analyses the universality of residual stresses in metal mechanical part and the influence of several typical manufacturing technics on the generation, distribution, and magnitude of the residual. Because of temperature ratio of Young抯 Modulus of metal material, residual stresses becomes a new factor that affects the thermal deformation of mechanical parts. After the theory of influence of residual stresses on thermal deformation of metal parts has been analyzed, the paper calculates the influence of superficial residual stresses on thermal deformation in several simple geometrical bodies, and deduces the calculation formulae correspondingly. Partial conclusion has been verified by experiments.After accomplishing the research of thermal deformation situated in uneven steady temperature field, the paper sets about the research of electromotor shaft thermal deformation in cutting for the Sanxia water conservancy project. The deformati...