The Thermal Characteristic Research Of Heavy-duty Gantry CNC Machine Tool’ Hydrostatic Guideway

Heavy and super-heavy duty machines are industry development needs in fieldsof large-scale electric power, aerospace, large ships in our country, traffic and largemetallurgical&mining special equipment etc. They are strategic goods and materialsrelated to national economic development and comprehensive strength. However thedesign and analysis technology for a heavy duty machine tool is still not perfect. Asimportant movement machining components, the hydrostatic guide rail performancefit or not directly is affecting the accuracy of machine tools directly. This paper gotthe oil film pressure field, velocity field and temperature field distribution, throughstudied the flow field of a single oil film. On this basis, it studied thermalcharacteristics of the static pressure guide rail from two aspects of theory andsimulation. Through comparing theory and simulation results, it also got thetemperature field and thermal deformation in the motion state of the static pressureguide rail, which are the basis for the study of machine tool thermal error compensation.First of all, based on fluid mechanics theory, it puts forward a method of thermalcharacteristics analysis. It can solve the oil film pressure field, velocity field andtemperature field through simplifying Reynolds equation, calculating equations ofenergy, using computational fluid dynamics method. Based on principles of heattransfer, it analyses the calculation method of the thermal stress and thermaldeformation. Through mechanical-modeling a simplified hydrostatic guide rail, thesolution of the guide rail stress bending line and the maximum deformation caused bythe thermal stress may describe clearly, and the calculation method of thermaldeformation may simplify.According to heavy-duty gantry machine tool structure, Buildingthree-dimensional models of static pressure guide rail, slide plates and static pressureoil film with UG. Based on the principle of static pressure, calculating the thicknessand the bearing capacity of static pressure oil film. Taking the simulation analysis ofstatic pressure oil film in rectangular and H-shaped oil chamber with FLUENT,compared to the same outside dimensions of the two kinds of film pressuredistribution and film supporting force. By comparing the theoretical calculation andsimulation results, verified the feasibility of analysis for static oil film properties by FLUENT. Get the temperature rising of static oil film through analysis of velocityfield and temperature field, provide the basic data for static oil film thermal analysis.Research the influence of apron slip velocity on static oil film characteristics, bycomparing pressure field, velocity field and the supporting force of the oil film underdifferent slip velocity, to get the oil film variation between the bearing force and theslip velocity.Using the basic principles of Heat Transfer, calculate thermal boundaryconditions of static pressure guide rail. To use finite element analysis softwareANSYS to take deep analysis of the rails the steady-state temperature field andthermal deformation in motion, by comparing the simulation results with theoreticalcalculations to verify the correctness of the analysis results. According to the analysisresults, proposing a method of changing thermal deformation of rail beam, providinga theoretical basis to study the influence that the thermal deformation of staticpressure guide rail on machining accuracy, and thus provides a reference value datafor the thermal error compensation for the machine study.