CNC Boring And Milling Machine Spindle System Static And Dynamic And Thermal Properties Research

Large floor type boring and milling machine is widely used in a variety of specialheavy-duty processing including aviation, metallurgy, power equipment, shipbuilding,railway vehicles, Strengthen develop such tools in product and technical research is alsohave a important implication for manufacturing industry. Machine tool spindle system isdirectly involved in the cutting process,the performance of the spindle system will directlyaffect the precision machine parts and cutting ability,Through the method of combiningtheoretical calculation with finite element analysis, Analysis of spindle system static anddynamic and thermal properties and verify whether the various performance parametersmeets requirement.Besides, provide a theoretical reference for the machine tool spindlesystem performance optimization.Static analysis for the spindle system by the method of the finite element simulationand obtain the distribution of radial deformation, through calculate static stiffness is878.3N/μm meets the design requirements of the machine. By changing the value of thebearing preload, analysis the influence of preload on the static stiffness, obtain the spindlesystem static stiffness affect by front bearing stiffness is most significant, modal analysisand harmonic response analysis for spindle system, modal analysis obtained spindle systemnatural frequency, On this basis, each of the critical speeds are obtained, the first criticalspeed is3540r/min, greater than the highest speed2000r/min of spindle system, so thespindle avoid resonance in the actual work effectively. Harmonic analysis obtain the frontradial displacement for frequency response curve of the spindle system, Acquire within theexcitation frequency range of milling force, in the first natural frequencies, dynamicstiffness is1617.2N/μm, in the second natural frequencies the dynamic stiffness is596.4N/μm. And analyze the influence of the bearing preload to dynamics of spindlesystem, increased preload can improve the natural frequencies of the spindle system andincrease the dynamic stiffness of the spindle system. Themral analysis for the spindle system, Bearing friction heat, Oil convective heattransfer coefficient, Convective heat transfer coefficient of spindle and air as load andboundary conditions, Through the method of finite element analysis obtain thermal steadystate temperature field at2000r/min, the maximum temperature obtained in the front ofspindle bearings and the temperature is57.203℃, And get the thermal-structuraldeformation distribution of spindle system, the thermal deformation in The end of thespindle is greater than the preceding. The paper also considers the heat-induced preload ofbearings cause the influence on the spindle system static and dynamic properties, due tothermal deformation of the spindle system static stiffness is403.2N/μm, the heat-inducedpreload increase the radial stiffness of the bearing so the natural frequencies are improved,spindle system dynamic stiffness in the frequency range of exciting force also increased.