Multi-Physics Fields Based Nonlinear Dynamic Behavior Analysis of Air Bearing Motorized Spindle

Chen, Guoda; Chen, Yijie; Lu, Qi; Wu, Quanhui; Wang, Minghuan

doi:10.3390/mi11080723

Cited by 10 publications

(11 citation statements)

References 34 publications

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“…Figure 6 shows the schematic structure of motor with eccentric rotor [ 4 ], and the 2-D magnetic force in cartesian coordinates can be expressed as

…”

Section: Mathematical Modeling Of Aerostatic Spindlementioning

confidence: 99%

“…The model selects the same motor parameter as that in reference [ 4 ], and the variation trend of UMF has been given as follows.

…”

Section: Numerical Simulationmentioning

confidence: 99%

“…Compared to the aerodynamic bearing, the aerostatic bearing provides higher capacity and steady force, while it contains more complex mechanism contributes to the dynamic behavior of aerostatic spindle. During the operation of the aerostatic spindle, it shows the multi-physics field coupling characteristics, in which the coupling effect of air bearing, the shaft and the motor should be considered for fully understanding its dynamics behavior [ 4 ]. However, the previous literatures commonly focused on single factor or two factors while investigating the dynamic characteristics of the aerostatic spindle [ 5 , 6 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

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Multi-Field Coupling Dynamics Modeling of Aerostatic Spindle

Chen

2021

Micromachines

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The aerostatic spindle in the ultra-precision machine tool shows the complex multi-field coupling dynamics behavior under working condition. The numerical investigation helps to better understand the dynamic characteristics of the aerostatic spindle and improve its structure and performance with low cost. A multi-field coupling 5-DOF dynamics model for the aerostatic spindle is proposed in this paper, which considers the interaction between the air film, spindle shaft and the motor. The restoring force method is employed to deal with the times varying air film force, the transient Reynolds equation of the aerostatic journal bearing and the aerostatic thrust bearing is solved using ADI method and Thomas method. The transient air film pressure of aerostatic bearings is obtained which clearly presents the influence induced by the tilt motion of the spindle shaft. The motion trajectory of the spindle shaft is obtained which shows different stability of the shaft under different external forces. The dynamics model shows good performance on simulating the multi-field coupling behavior of the aerostatic spindle under external force. which is quite meaningful and useful for the further research on the dynamic characteristics of the aerostatic spindle.

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“…Figure 6 shows the schematic structure of motor with eccentric rotor [ 4 ], and the 2-D magnetic force in cartesian coordinates can be expressed as

…”

Section: Mathematical Modeling Of Aerostatic Spindlementioning

confidence: 99%

“…The model selects the same motor parameter as that in reference [ 4 ], and the variation trend of UMF has been given as follows.

…”

Section: Numerical Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-Field Coupling Dynamics Modeling of Aerostatic Spindle

Chen

2021

Micromachines

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“…Due to the vanishingly low friction in the air, high wear resistance, and environmental friendliness, aerostatic bearings are used in machines, in particular, in machine tools, which are devices that require high accuracy of micro-movement and positioning [1][2][3][4][5][6][7][8]. In mechanical engineering, aerostatic bearings are used in the spindle assemblies of metalcutting machine tools [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Efficiency Study of Output Lubricant Flow Rate Regulating Principle on the Example of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves and a System of External Combined Throttling

et al. 2021

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Due to their vanishingly low air friction, high wear resistance, and environmental friendliness, aerostatic bearings are used in machines, machine tools, and devices that require high accuracy of micro-movement and positioning. The characteristic disadvantages of aerostatic bearings are low load capacity, high compliance and an increased tendency for instability. In radial bearings, it is possible to use longitudinal microgrooves, which practically exclude circumferential air leakage, and contributes to a significant increase in load-bearing capacity. To reduce compliance to zero and negative values, inlet diaphragm and elastic airflow regulators are used. Active flow compensation is inextricably linked to the problem of ensuring the stability of bearings due to the presence of relatively large volumes of gas in the regulator, which have a destabilizing effect. This problem was solved by using an external combined throttling system. Bearings with input flow regulators have a number of disadvantages-they are very energy-intensive and have an insufficiently stable load capacity. A more promising way to reduce compliance is the use of displacement compensators for the movable element. Such bearings also allow for a decrease in compliance to zero and negative values, which makes it possible to use them not only as supports, but also as active deformation compensators of the technological system of machine tools in order to reduce the time and increase the accuracy of metalworking. The new idea of using active flow compensators is to regulate the flow rate not at the inlet, but at the outlet of the air flow. This design has the energy efficiency that is inherent to a conventional bearing, but the regulation of the lubricant output flow allows the compliance to be reduced to zero and negative values. This article discusses the results of a theoretical study of the static and dynamic characteristics of a two-row radial aerostatic bearing with longitudinal microgrooves and an output flow regulator. Mathematical modeling and theoretical study of stationary modes have been carried out. Formulas for determining static compliance and load capacity are obtained. Iterative finite-difference methods for determining the dynamic characteristics of a structure are proposed. The calculation of dynamic quality criteria was carried out on the basis of the method of rational interpolation of the bearing transfer function, as a system with distributed parameters, developed by the authors. It was found that the volumes of the microgrooves do not have a noticeable effect on the bearing dynamics. It is shown that, in this design, the external combined throttling system is an effective means of maintaining stability and high dynamic quality of the design operating in the modes of low, zero and negative compliance.

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“…A large number of theoretical and experimental works have been published on various aspects of gas lubrication [1][2][3][4][5][6][7][8]. The greatest demand for aerostatic bearings is observed in machine-tool construction when using aerostatic bearings in the spindle units of metalworking machines [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling on the Compliance and Load Capacity of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves in the Inter-Row Zone

et al. 2021

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Aerostatic bearings are attractive, with minimal friction losses, high durability, and environmental friendliness. However, such designs have a number of disadvantages, including low load-bearing capacity and high compliance due to high air compressibility and limited injection pressure. The article proposes a double-row aerostatic journal bearing with an external combined throttling system and longitudinal microgrooves in the inter-row zone. It is hypothesized that the use of microgrooves will reduce the circumferential flows of compressed air, as a result of which the compliance should decrease and the bearing capacity should increase. To test the hypothesis, we carried out the mathematical modeling, calculations, and theoretical study of stationary operation modes of the bearing for small shaft eccentricities in the vicinity of the central equilibrium position of the shaft and bearing capacity for arbitrary eccentricities. Formulas were obtained for the numerical evaluation of compliance for bearings with a smooth bushing surface and with longitudinal microgrooves. Iterative finite-difference methods for evaluating the fields of the squared pressure are proposed, on the basis of which the load capacity of the bearings is calculated. Experimental verification of the bearing’s theoretical characteristics was carried out, which showed satisfactory agreement between the compared data. The study of the compliance and load capacity of a microgroove bearing yielded impressive results. We show that the positive effect from the application of the improvement begins to manifest itself already at four microgrooves; the effect becomes significant at six microgrooves, and at twelve or more microgrooves, the circumferential flows in the bearing gap practically disappear; therefore, the bearing characteristics can be calculated on the basis of one-dimensional models of air lubrication longitudinal flow. Calculations have shown that for a length of L = 1, the maximum load capacity of a bearing with microgrooves is 1.5 times higher than that of a conventional bearing; for L ≥ 1.5, the bearing capacity increases twice or more. The result obtained allows us to recommend the proposed improvement for practical use in order to increase the load capacity of aerostatic journal bearings significantly.

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Multi-Physics Fields Based Nonlinear Dynamic Behavior Analysis of Air Bearing Motorized Spindle

Cited by 10 publications

References 34 publications

Multi-Field Coupling Dynamics Modeling of Aerostatic Spindle

Multi-Field Coupling Dynamics Modeling of Aerostatic Spindle

Theoretical Efficiency Study of Output Lubricant Flow Rate Regulating Principle on the Example of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves and a System of External Combined Throttling

Numerical Modeling on the Compliance and Load Capacity of a Two-Row Aerostatic Journal Bearing with Longitudinal Microgrooves in the Inter-Row Zone

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