The Research Of The Dynamic Error And Thermal Deformation Analysis On Heavy Duty Hydrostatic Rotary Table

Heavy duty machine tool, which is mainly used for the processing of large andheavy parts, is the important foundation and key equipment of the equipmentmanufacturing industry. The hydrostatic technology is widely used between themoving parts because of the heavy machine tool structure and super key functionalcomponent characteristics. Hydrostatic bearing are well known for their high carryingcapacity, high stiffness, low friction and virtually no wear, good vibration resistance,overcoming the crawling phenomenon and stable operation and so on. Heavy dutyhydrostatic rotary table is one of the key functions of heavy machine tool parts,mainly used for carrying large workpiece, rotary processing and can be matched withother shafting movement to realize five axis machining. Therefore, the characteristicsanalysis of heavy hydrostatic rotary table plays a vital role on the machining accuracyof heavy machine tool.Supported by the National Science and Technology Major Project: The keytechnology and the digital design of high-grade CNC machine tools specializing in R&D and typical applications (Project No.2012ZX04010-011), this paper mainlystudies the influence of the profile error of the guide way on the motion errors,analyzes the dynamic characteristic and thermal properties of the hydrostatic rotarytable. Finally a set of static, dynamic, and thermal characteristic analysis system isformed.In order to explore the influence factors on the accuracy and carrying capacity ofhydrostatic rotary table, this paper separately analyzed the static error, dynamic andthermal characteristics of the table. First of all, according to the structurecharacteristics and working conditions of heavy hydrostatic rotary table, a newmethod to analyze the motion error was proposed considering guide way profile errorbased on the hydrostatic theory and finite element method. The equilibrium isobtained in different positions using this method and the axial motion error, the pitchangle and tilt angle error are achieved. The impacts of the profile error component ofinner and outer guide way on the motion error are analyzed and the value of themotion error was achieved by analyzing the experimental profile errors using themethod. Theoretical support is provided for improving the actual motion error of thetable. Then using the finite element method with linear spring equivalent to the hydrostatic oil film, the natural mode of vibration with constraints and harmonicresponse characteristics are analyzed, and the change of natural frequency iscomparatively analyzed under different working conditions, and the influences ofcarrying capacity, the support style and stiffness on dynamic characteristics of thetable was analyzed. Then the temperature rise in each hydrostatic bearing is calculatedusing the hydrostatic theory and the temperature distribution is obtained using theANSYS software. The influence of rotational speed and carrying capacity on thetemperature rise and the viscosity is analyzed and the thermal deformation of the tableis achieved. Finally, the secondary development of the static, dynamic and thermalcharacteristic analysis system is carried out and the analysis efficiency of the partssimilar to the table is improved greatly.