Papers by Author: Xiao Dong Yang

Abstract: In order to obtain the heat dissipation regularity of heavy-duty vertical lathe faceplate with a large radius, mathematical model of convection heat transfer is established. According to the model, convection heat transfer process of the faceplate is analyzed 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 faceplate, but also drives the heat increased the heat dissipation, degenerated the heat concentration phenomenon. Experimental results shows consistent to the faceplate 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.

Abstract: 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.

Abstract: In order to achieve the switching function of the force and position, the force control is executed when the hydraulic cylinder contacts with the mechanical objects, the position control is executed when the hydraulic cylinder is far away from the mechanical objects. This paper respectively established force control model and position control model. The position control adopts the PID algorithm and the force control adopts the fuzzy algorithm. In order to solve the jump and jitter of the parameters when force-position switching, this paper puts forward a fuzzy switching adaptive control strategy. Fuzzy switching ensures the smooth transition of the two control models, the results of simulations show that fuzzy switching not only ensures the system’s rapidity but also shows excellent robustness against variations of system parameters and external disturbances.

Abstract: 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.

Abstract: Based on heat transfer theory, thermodynamics steady state equation of hydrostatic bearing, thermal mathematical model of hydrostatic bearing and boundary condition of numerical simulation is established. Temperature field distribution of hydrostatic bearing at different velocity is numerical simulated. Regularity of the influence of velocity on temperature field of heavy hydrostatic thrust bearing is revealed. The results show that, velocity impacted a significant influence on heat transfer and temperature field distribution of hydrostatic bearing. Average temperature of workbench steadily declined as velocity increasing, while average temperature of base gradually increased; both of them emerged serious heat concentration, but the cooling situation of workbench is better than base. The numerical simulation results could provide theoretical basis for temperature control scheme design which will improve the stability and reliability during hydrostatic bearing operation.

Abstract: 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.

Abstract: In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distribution, based on fluid and solid interaction theory, this paper adopted ADINA to analyze the pressure field distribution of sealed cavity in certain radial and axial gap, the computed model of the motor was established, and the pressure change of sealed cavity under the given dimension of the buffer groove was analyzed. The result shows that the pressure changes stably and buffer groove’s dimension is reasonable, which lays foundation for the structure design and experimental research of large displacement servo motor and improve the low speed performance of continuous rotary electro-hydraulic servo motor.

Abstract: 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.

Abstract: According to the structure of workbench and base of heavy hydrostatic bearing which is applied in heavy equipment, thermal deformation equations of the structure are deduced and boundary conditions for numerical simulation are established based on thermal elasticity theory. Then thermal deformation of hydrostatic bearing without load is calculated at different velocity. The results indicate that: temperature and velocity impacts a significant influence on thermal deformation of hydrostatic bearing. Thermal deformation increases as the velocity increases; workbench up-warps severely, oil-pad inclines towards outside to a certain extent, which results in the lubrication clearance emerges as wedge-shape deformation. The conclusions from thermal deformation calculation could provide theoretical basis for structure design of hydrostatic bearing and ravel out the thermal deformation problem.