Research On Bearing Performance Of Hydrostatic Ram Of Vertical Lathe Under High Speed And Heavy Load Conditions

Vertical lathe,with high precision,strong stability,convenient clamping and small occupation area,is suitable for processing heavy-duty parts with small ratio of length to diameter,and it is an indispensable mechanical equipment in Chinese manufacturing industry.The rest of vertical lathe is vertically installed on the beam,and the hydrostatic ram component in the rest is one of the most important components of vertical lathe.In the cutting process,turning tool fixed at the end of hydrostatic ram directly touch the workpiece,and the cutting load under machining process is applied to the end of hydrostatic ram,which leads to the deformation of hydrostatic ram and gap oil film.Oil film deformation,ram deformation and vibration directly affect machining accuracy and surface quality of workpiece.Therefore,the research on bearing performance of hydrostatic ram is particularly important.In this paper,the system of hydrostatic ram is analyzed based on elastic-plastic deformation,fluid mechanics and other related theories,and the oil film pressure,oil film thickness and oil film stiffness are calculated,which lays a theoretical foundation for the following simulation.The static characteristics of hydrostatic ram are studied by finite element volume method and static analysis.Fluent software is used to simulate pressure field of oil film in each oil camber when main cutting force is 63 k N and overhanging length is 1200 mm and 2000 mm,the oil film pressure distributions are observed and the oil film pressures at different positions are compared.Workbench is used to simulate deformations of hydrostatic ram under different overhanging lengths and cutting forces,deformation laws of hydrostatic ram under different working conditions are observed.The deformation of friction pair with two working conditions is simulated to predict the change of gap oil film.The dynamic characteristics of hydrostatic ram are studied by modal analysis and harmonious response analysis,and the natural frequency and resonance frequency of ram are determined to provide corresponding measures to avoid the resonance of hydrostatic ram.A rib structure is added to the outside of hydrostatic ram to improve the bending stiffness of hydrostatic ram.Experimental verification is carried out.The stress deformation and natural frequency of hydrostatic ram of vertical lathe are measured,and the experimental values are compared with the simulation values to verify the accuracy of simulation.