Yan Qin Zhang

Simulation and Experiment Study of Heat Dissipation of Heavy-Duty Vertical Lathe Faceplate

In order to obtain the heat dissipation regularity of heavy-duty vertical lathe workbench with a large radius, mathematical model of convection heat transfer is established. According to the model, convection heat transfer process of the workbench is analysed at the velocity of 10~80rpm. The results show that velocity increasing not only impacts a greater influence on the temperature rising of hydrostatic bearing than the temperature rising of workbench, but also drives the heat increased the heat dissipation, degenerated the heat concentration phenomenon. Experimental results shows consistent to the workbench temperature numerical simulation results, the maximum error is 5%, which indicating that the numerical results conform physical regularities, the heat transfer mathematical model extends the range of applications of rotation convection heat transfer, so that vertical lathe heat dissipation situation analysis can be easier and more accurate.

Simulation on Multi-Oil-Cavity and Multi-Oil-Pad Hydrostatic Bearings

Taking multi-oil-cavity and multi-oil-pad hydrostatic bearings as studied projects, firstly make brief instructions for structure characteristics and working principal of hydraulic system; Then, build three-dimensional models of multi-oil-cavity and multi-oil-pad hydrostatic bearings respectively. Adopting finite volume method, oil film mesh is generated by universal finite analysis software CFD; then, carry on numerical simulations for pressure distribution and temperature distribution of the two studied hydrostatic thrust bearing under various viscosity, and make comparative analysis for difference between the two studied hydrostatic thrust bearing. Based on the analysis of numerical simulation results, the conclusions whether oil-return groove is set for hydrostatic bearing could be received. Simulation results reveal truly the influence of setting oil-return groove or not on hydrostatic thrust bearing, and improve structure design for hydrostatic thrust bearing.

Viscosity Influence Research on Load Capacity of Heavy Hydrostatic Bearing

Lubricant viscosity is one of the key parameters in hydrostatic bearing research. In order to solve the load capacity of hydrostatic bearing in the heavy equipment, viscosity-temperature equation of lubricant film is established, and the viscosity-temperature curve is fitted by B-Spline curve. Finite volume method is used on numerical simulation of pressure field of heavy hydrostatic bearing in constant and variable viscosity respectively and in different rotational velocity, whereafter, viscosity influence on load capacity of heavy hydrostatic bearing is discussed. The results show that, viscosity impose a minor influence on cavity pressure of hydrostatic bearing when rational velocity is low; whereas, when rational velocity is high, especially to the heavy hydrostatic bearing which with high liner velocity influence of viscosity changing must be taken into account in calculation. Numerical simulation results reflect the pressure distributing state of bearing veritably; furthermore, these provide theoretical basis for hydrostatic bearing design and lectotype in practical application.

Research on Influence of Cavity Depth on Load Capacity of Heavy Hydrostatic Bearing in Variable Viscosity Condition

Owing to setting viscosity of lubrication oil as a constant value will lead errors in hydrostatic bearing calculation, the influence of cavity depth on load capacity of heavy static bearing is analyzed in variable viscosity condition. Firstly, viscosity-temperature equations of oil film are established; secondly, viscosity-temperature curve is fitted by B-Spline; finally, using finite volume method, hydrostatic pressure field and dynamic pressure field of heavy hydrostatic bearing is calculated with different cavity depth at the same velocity, and influence of cavity depth on load capacity is revealed. The results show that, were the cavity depth shallow enough(≤2mm), hydrostatic pressure and dynamic pressure of cavity would decline rapidly with the cavity depth increasing; whereas, were cavity deep enough(≥2mm), hydrostatic pressure and dynamic pressure of cavity would change little with the cavity depth extending. This numerical simulation reflects real distribution of bearing pressure appropriately, and provides a theoretical basis for hydrostatic bearing design and lectotype.

Oil Film Carrying Property Research of Hydrostatic Vertical Guideway of CNC Vertical Lathe

Hydrostatic vertical guideway is the key component of modern CNC equipments which is a common lubrication form of turret. In order to improve the cutting stiffness during processing, the hydrostatic vertical guideway in sliding seat during westbank ram processing. Take count different cutting force to analysis the thickness changing of hydrostatic oil film, and then the relation between cutting force and the thickness of oil film is obtained. Based on FVM, relation model between them is established and the limited condition including cutting force is T=100KN, flow flux of each inlet is 0.52L/min, pump of constant delivery type is applied, film thickness is 0.023mm and oil cavity depth is 2mm is numerical simulated. The Hydrostatic pressure field and film thickness under different condition of hydrostatic vertical guideway is obtained. The relation model between film thickness and custom forces is validated. Whats more, the regularity of cutting force influence that impacted on film thickness is revealed. The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machine and the entire CNC equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice.

Temperature Field of Hydrostatic Supporting Disk in Different Viscosity and Rotational Speed

With heavy hydrostatic bearing as the research object, establish oil film viscosity-temperature equation. Adopt finite volume method, respectively calculates the oil film temperature field under different rotate velocity in Invariant viscosity and variable viscosity, revealing the oil film temperature arise influence rule of hydrostatic bearing on the viscosity and rotate velocity. The results show that the viscosity and rotate velocity have a great influence on the hydrostatic bearing oil film temperature rise, but the effect regularity varied. The calculated results that provide a theoretical basis for the hydrostatic bearing structure design and bearing deformation calculation, and have very important significance on improve the reliability and precision of the whole machine tools.

Research on Hydrostatic Supporting Temperature-Rise of Heavy NC Machine Tool

With heavy NC machine tool is widely used in many oil pad round guide hydrostatic bearing as the research object, in the under condition of variable viscosity, establish oil film viscosity-temperature equation. Adopt finite volume method, simulation the hydrostatic bearing internal fluid temperature field under different flow rates on the speed of 6R / min. Numerical simulation hydrostatic thrust bearing oil film temperature field, can find a general high temperature region, and then take effective control temperature. It can achieve the hydrostatic thrust bearing oil film temperature field prediction for engineering practical oil chamber structure, offer the theoretical foundation for optimization design.

Influence Research of Recess Shape on Dynamic Effect of Hydrostatic Thrust Bearing

This work describes a simulation research concerning dynamic effect of multi-pad hydrostatic thrust bearing having rectangular recess, sector recess, ellipse recess and I-shaped recess in order to solve the loading capacity of the hydrostatic thrust bearing. Three-dimensional pressure field of gap fluid between the rotation worktable and the base has been computed by using the Finite Volume Method. This study theoretically analyzes the influence of recess shape on dynamic effect of the bearing according to computational fluid dynamics and lubricating theory, and the simulation results indicate that an improved characteristic will be affected by recess shape easily. Through this method, the safety of a multi-pad hydrostatic thrust bearing having different cavities can be forecasted, and the optimal loading capacity of such products can be achieved, so it can provide reasonable data for design, lubrication, experience and thermal deformation computation for hydrostatic thrust bearing.

Research on Pressure Field of Hydrostatic Center Rest

In order to solve the mechanical deformation of the hydrostatic center rest, a numerical simulation concerning pressure field of hydrostatic center rest is studied. CFX of ANSYS has been used to compute three-dimensional pressure field of gap fluid between workpiece and bearing pillow. This research analyzes the influence of rotation speed on the bearing pressure performance according to lubricating theory and computational fluid dynamics, and it has revealed its pressure distribution law of gap oil film. Results indicate that an improved characteristic will be affected by rotation speed easily, and oil cavity pressure increases by gradually with rotation speed enhancing. The reliability of a hydrostatic center rest can be predicted through this method.

Simulation on Supporting Characteristics of Heavy Hydrostatic Thrust Bearing

The pressure field of the clearance oil film of the hydrostatic bearing in varies velocities was simulated based on Finite Volume Method (FVM) by the software of Computational Fluid Dynamics. In this article, a conclusion could be drawn that the viscosity has great influences on the pressure in the heavy hydrostatic bearing and it cannot be neglected especially in high rotating speed. The results of numerical calculations provide internal flow status inside the bearing, which would help the design of the oil cavity structure of the bearing in engineering practice.