Theoretical research on sector oil-pads’ mechanical property in hydrostatic thrust bearing based on constant flow

Abstract

Purpose The purpose of this study with the rapid development of the heavy/large mechanical equipment, the heavy computer numerical control (CNC) vertical lathe has become the ideal processing equipment for the parts of those mechanical equipments. The main factor which affects the machining quality and efficiency of heavy CNC vertical lathe is the mechanical properties of the hydrostatic thrust bearing. Design/methodology/approach This paper did the research based on the large size sector oil pad’s lubrication performance of the hydrostatic thrust bearing in the heavy/large equipments, establishing the lubrication performance distribution mathematical model of the velocity field, flow field, pressure field and so on, analyzing the bearing behavior of the large size sector oil pad. Findings The results show that the oil flow generated by the plate relative motion will be greater than that generated by the pressure difference in area B, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. The oil flow generated by the centrifugal force will be greater than that generated by the pressure difference in area C, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. When the rotational speed of the hydrostatic thrust bearing is too high, the friction heat will be not easy to be sent out. The bearing rotating speed should be lower than the comparatively smaller one of ω1 and ω2, which can help avoid the rise of too high temperature. Originality/value The research provides powerful theoretical foundation for practical application of the large size sector oil pad hydrostatic thrust bearing, its structure design and operating reliability, realizing the lubrication performance prediction of the large size hydrostatic thrust bearing.

Design and performance analysis on heat pipe hydrostatic thrust bearings based on rectangular oil pad

“…The total flow of the lubricating oil flowing through a single rectangular oil pad is the sum of the flow of oil into eight areas (A-H) from the oil chamber and the flow that goes back to the returning oil slot. As such, the total flow Q of oil, which flows from a single oil chamber into the returning oil slot through the sealing side, may be derived as per the following formula according to the N–S equation (Li et al , 2016, 2017): …”

“…The bearing capacity reflects the weight of components and parts that can be fabricated by the equipment. The bearing capacity of a single oil pad W is specified as the sum of the bearing capacities on the sealing side and in the oil chamber (Li et al , 2016, 2017), which could be expressed as the following formula: …”

“…In this setting, the oil chamber pressure will be changed along with the viscosity and density of oil, the thickness of oil film and the rotation speed of the thrust bearing. So according to formula (1) and formula (2), the relationship between the bearing capacity of a single rectangle oil pad W and the thickness of the oil film δ on the constant-flow hydrostatic thrust bearing is shown in formula (3) (Li et al , 2016, 2017): …”

“…Therefore, it is the better if the stiffness is greater. The stiffness of the oil film could be derived by partial differential on oil film thickness, which is indicated in formula (4) (Li et al , 2016, 2017): …”

Analysis of oil film flow characteristics and lubrication performance of thrust bearing of 1000MW Hydraulic Turbine Unit

“…With the increase of load variation, the temperature rise also increased, and the oil film thickness decreased further. Li et al [19] proposed that the oil film thickness and working temperature of thrust bearings were important factors affecting their lubrication performance and bearing capacity, and observed the formation, change and rupture process of the oil film through experiments, and studied the flow type within the oil tank. Subsequently, Lu et al [20] numerically calculated the internal flow field of the oil tank, and analysed the influence of the support method of the pads and the cooling structure of the lubricant on the stability of the bearing.…”