Investigation on Damping Characteristics of Hydrostatic Bearing Film by Using Scale Method

The resonant peaks can be suppressed by damping, those effects is dependent on damping ratio of system. In this paper, we propose a scaling method to evaluate the damping ratio of hydrostatic bearings for the data from model test. This method fits specifically for the overdamping of all hydrostatic bearing. This is direct and the easiest method to obtain the damping characteristics of oil film for the lowest band before the first resonant peak. The frequency responses of acceleration per force for a single-degree-of-freedom mass-spring-damper model is used to generate the evaluation scales for the damping ratios of the modal test results of worktable mounting on hydrostatic bearing. The case study for experimental results of the impact response are evaluated for damping ratio of the hydrostatic film by these method. Furthermore, using this scaling method, the influences of three types of compensations on the damping ratio of a hydrostatic bearing are compared. The results reveal that the constant flow has the largest damping ratio, and the capillary restrictor has the smallest one.

Study on oil starvation at the oil seal edge of the oil film of hydrostatic bearing with double rectangular cavity

Purpose When the clearance oil film of hydrostatic bearing friction pair is in critical lubrication state, the phenomenon of zero flow of local lubricating oil will aggravate the oil film temperature rise, which needs to be solved. Design/methodology/approach In this paper, the critical lubrication parameter equation and the oil film temperature rise mathematical model are derived for the new type q1-205 double rectangular cavity hydrostatic bearing. Based on a combination of theoretical analysis, simulation and experimental verification, this paper analyzes the flow characteristics and temperature rise characteristics of the lubricating oil when the hydrostatic bearing is in a critical lubrication state under different operating conditions and finally obtains the critical lubrication state of the oil film. Findings This study found that the numerical simulations and the derived formulas agree with the results. When the oil film is in critical lubrication, the cross-section side flow of the oil side is almost zero. The heat cannot be taken away in time, resulting in the local temperature rise of the oil film, which causes serious heat accumulation. Originality/value It is concluded that the operating condition parameters corresponding to the critical lubrication state provide a theoretical basis for the selection of actual hydrostatic bearing operating conditions, which is of great scientific significance.

Whiffletree based supports for self-adjustable hydrostatic bearings

Hydrostatic bearings are superior in terms of their friction and load carrying characteristics when compared to contact based bearings, but non-usable in applications with non-constant curvature counter surfaces. A possible solution to this limitation is the introduction of deformable hydrostatic bearings components that cope with these required deformations. To reduce the required deformation of a single bearing pad, multiple pads can be connected through a so-called whiffletree support system. In this work, a symmetric whiffletree based hydrostatic bearing embodiment is introduced. A 2D quasi-static model is introduced that allows for determining the kinetostatic and path following properties of such a type of bearing. Design considerations are given regarding the joint rotational-, normal-, and shear stiffness of each individual joint, as well as basic bearing layout. The potential of a whiffletree suspended bearing is presented through the use of a case study.

Hydrostatic Bearing Characteristics Investigation of a Spherical Piston Pair with an Annular Orifice Damper in Spherical Pump

The spherical pump is a totally new hydraulic concept, with spherical piston and hydrostatic bearing, in order to eliminate the direct contact between the piston and cylinder cover. In this paper, the governing Reynolds equation under spherical coordinates has been solved and the hydrostatic bearing characteristics are systematically investigated. The operating sensitivities of the proposed spherical hydrostatic bearing, with respect to the piston radius, film beginning angle, film ending angle, film thickness, and temperature, are studied. The load carrying capacity, pressure drop coefficient, stiffness variation of the lubricating films, leakage properties, and leakage flow rates are comprehensively discussed. The related findings provide a fundamental basis for designing the high-efficient spherical pump under multiple operating conditions. Besides, these related results and mechanisms can also be utilized to design and improve other kinds of annular orifice damper spherical hydraulic bearing systems.

A Review on Hydrostatic Bearing: Research and Analysis

Background: A kind of sliding bearing with liquid as a lubricant, hydrostatic journal bearing can be applied to tribology, mechanics, optimization method and structural design in engineering practice. Hydrostatic bearing characterized by high precision, high rigidity, and long life has drawn people's attention and been widely adopted. As progress has been made in science and technology, people now have a better understanding of the principles and characteristics of the hydrostatic journal bearing. Objective: The development of hydrostatic bearing in recent years has been studied and analyzed in this paper. Methods: More than 70 recently published patents, and journal and conference papers related to the developments in air traffic flow management have been reviewed, and the outcomes in temperature field, pressure field, deformation, lubrication, bearing capacity and friction are studied. Results: Through these research results, the current research status of hydrostatic bearings is summarized, and the three aspects of flow field characteristics, lubrication characteristics and tribology are explained, and solutions and feasibility measures for existing outstanding problems in each aspect are mentioned. Conclusion: Based on this article, the design and optimization of hydrostatic bearings are of significance. Finally, the current problems and challenges of hydrostatic bearings are analyzed, and future research directions and research priorities are proposed.

Flow-Heat-Solid Coupling Thermal Deformation Analysis of Hydrostatic Spindle under Viscosity Temperature Effect

The hydrostatic bearing oil film plays a key role in supporting and lubricating. As the speed increases, the temperature of the lubricating oil increases and the viscosity decreases. As a result, the bearing capacity of the oil film is reduced, which affects the motion accuracy of the hydrostatic bearing. In this paper, the simulation and analysis of the temperature rise of the hydrostatic bearing oil film under the constant viscosity and the viscosity-temperature effect are performed respectively. Then, based on the fluid-heat-solid coupling analysis theory, the temperature field of the hydrostatic bearing and the thermal deformation of the spindle shaft with and without the viscosity-temperature effect are analyzed separately. The temperature field of the shaft and the thermal deformation of the spindle shaft are analyzed separately. Finally, the bearing temperature and shaft deformation are compared with the experimental values for error analysis. It is found that the error rate is smaller when the viscosity-temperature effect is considered. Considering the viscosity-temperature effect, the maximum error rates of the temperature of the radial and thrust bearing bushes are 11.05% and 7.82%, and the maximum error rates of the thermal deformation of the spindle shaft in the axial and radial directions are 12.03% and 18.57%.

Research Status of Hydrostatic Bearing Technology in Machine Tool

Background: As the basis of mechanical manufacturing, large-scale machine tools are developing in the direction of improving processing accuracy, load-bearing capacity and rigidity. Hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are important components of large machine tools, with the continuous improvement of product accuracy requirements, the research on hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are more important. Objective: This paper introduces the current research on hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram to express the importance of hydrostatic ram in improving the machining accuracy of machine tools. The study aims to lay a foundation for research and development of hydrostatic ram in the future. Methods: Firstly, the hydrostatic bearing technology is introduced. Secondly, the research status of hydrostatic thrust bearing, hydrostatic guide and hydrostatic ram are introduced to provide theoretical basis for improving the processing performance of rest ram. Result: Deformation compensation and thermal deformation compensation of hydrostatic ram have been studied more. Most of study focus on the accuracy of hydrostatic ram, but less on the bearing performance of hydrostatic ram. Conclusion: Breakthroughs have been made in the research on precision control and structural form of the hydrostatic bearing at home and abroad. Most scholars take the ram of Computer Numerically Control (CNC) boring and milling machines as the research object, but there are less research on the ram of vertical lathes. Therefore, the academic circle should pay more attention to the bearing performance of the hydrostatic ram of vertical lathes.