| The large-scale and heavy burden hydrostat ic turntable is the core component for precisio n and ultra-precisio n heavy vert ical machine commonly. It has many significant advantages such as high bearing capacit y, high rigidit y, high precisio n, lo ng life,et al. There is a wide range of applicat ions in large core parts processing such as large scale aluminum allo y parts of satellites, high pressure nuclear pump bodies, cores of large valve, wind power’s turbine bases and so on. Compared with the small hydrostat ic turntable, the diameter of the large-scale and heavy burden hydrostat ic turntable is usually up to 8-12 m, while the oil film’s thickness is only about 0.15 mm. The rat io of the deformation caused by heat and force to the oil film thickness is increased significant ly because of the size effect, which influence bearing characterist ics obviously and the coupling effect of fluid and solid which has a serious influence on the stabilit y and precisio n of the operat ion. Compared wit h the developed countries, the large-scale and heavy burden hydrostat ic turntable has different kinds of problems, such as poor operat ional stabilit y, low machining accuracy and scratch accident of hydrostat ic guide way. In order to solve the above problems, the bearing characterist ics and the fluid-solid-thermal coupling law of the large-scale and heavy burden hydrostat ic turntable are researched in this paper. The main research cont ents are as follows:(1) The analyt ical calculat ion method of the bearing characterist ics o f the large-scale and heavy burden hydrostat ic turntable with invariable boundary oil film is derived and established. For uniform load condit io ns, a new mathemat ical model for calculat ing bearing characterist ics of oil film is presented in this paper. Comparing with traditional calculat ion method, the new method has taken the influence o f centrifugal force into account. For invariable part ial load condit io ns, an analyt ical method of equivalent oil film thickness for calculat ing bearing characterist ics of oil film is presented. Based on the method for calculat ing bearing characterist ics of oil film with invariable boundary, the influence of the working parameters on bearing characterist ics of the invariable boundary oil film is studied, under the condit ions o f both uniform load and fixed part ial load.(2) Aiming at the running condit ion of the clamping part ial load, a new method for calculating the bearing characterist ics of the large-scale and heavy burden hydrostatic turntable’s moving boundary oil film is put forward. The method uses UDF custom program to simulate the oil film shape’s changing process of the part ial load hydrostat ic turntable during operat ion and loads the rotat ing speed to each mo ving unit. Moving boundary of oil film is converted into a stat ic boundary to avoid the oil film grid ’s distort ion caused by rotat ion of the turntable. The spring smoot h model is used to update the oil film grid ’s extrusion due to the change of the t ilt direct ion of the turntable. Based on the method, the moving boundary oil film of the part ial load hydrostat ic turntable is simulated and t he influence of working parameters on the bearing characterist ics is studied.(3) By establishing the fluid-solid-thermal coupling model of the large-scale and heavy burden hydrostat ic turntable, the results of oil film pressure field and temperature field calculated in Fluent software are uploaded to the solid structure model in Workbench, which realize the calculat ion of fluid-solid- thermal coupling deformat ion of the large-scale and heavy burden hydrostat ic turntable. The influence of the deformat ion field on the oil film thickness about two hydrostat ic guide ways was studied. Based on the method of fluid-solid-thermal coupling deformat ion, the coupled model is simplified and the influence of main working parameters on the deformat ion of the guide way and the minimum oil film thickness under the condit io n is studied.(4) The running stabilit y and the processing precisio n of the large-scale and heavy burden hydrostat ic turntable are reduced by the fluid-solid- thermal coupling deformat ion and sometimes there even be a scratch accident. To slove this problem, the control strateg ies of fluid-solid-thermal coupling deformat ion is proposed. The strategies including: improving the contour accuracy and surface finish of the frict io n pair ’s surface, pre-deformat ion compensat ion for the mo ving surface of the hydrostat ic guide way, opt imizing the structural parameters of the turntable, enhancing the st iffness and reducing the thermal deformation, the mo nitoring and compensat ion system of oil film thickness. By comparing and analyzing the guide way deformat ion using the control strategies or not, the effect iveness of the control strategies of fluid-solid-thermal deformat ion for large overload hydrostat ic turntable is confirmed.(5) The experimental system of the large-scale and heavy burden hydrostatic turntable is designed and established. The bearing capacit y of the invariable boundar y oil film and the moving boundary oil film are conducted respect ively. The effect iveness of oil film thickness monitoring and control is verified by test ing the o il film thickness on-line monitoring and compensation syste m. By comparing the experimental data with the theoret ical calculatio n results, the correctness and validit y are verified that the analyt ical method for bearing characterist ics under invariable boundary oil film bearing and the dynamic grid calculat ion met hod for bearing characterist ics under moving boundary oil film, which provide the theoret ical basis for the design of the large-scale and heavy burden hydrostat ic turntable. |
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