Design and Analysis of an Aerostatic Pad Controlled by a Diaphragm Valve

Colombo, Federico; Lentini, Luigi; Raparelli, Terenziano; Trivella, Andrea; Viktorov, Vladimir

doi:10.3390/lubricants9050047

Cited by 7 publications

(6 citation statements)

References 38 publications

(45 reference statements)

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“…The repeatability was assessed by the fact that, conversely to the previous prototype, the initial position of the nozzle does not change after many experimental test repetitions. Moreover, the novel valve prototypes was built by exploiting a design algorithm (similar to those presented in [15]) based on the equation of the lumped parameter model of the system [14]. The static characterization of the prototype makes it possible to verify the accuracy of the lumped model and the proposed design algorithm.…”

Section: Discussionmentioning

confidence: 99%

“…This paper presents a novel prototype of passively compensated pad. This passive compensation solution consists in the integration of commercial pad and a custom-built diaphragm valve whose design is an improved version of that described in [14,15]. The novel prototype is modelled through the same lumped parameter model that was used for the previous prototype.…”

Section: Introductionmentioning

confidence: 99%

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A novel prototype of diaphragm valve for passively compensated aerostatic pads

Colombo

2023

Theoretical and Applied Mechanics - AIMETA 2022

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Abstract. Thanks to their low friction, aerostatic pads are currently used in many high precision applications. However, due to the air compressibility, aerostatic bearings suffer from relatively low stiffness and damping. Active and passive compensation methods represent a valuable solution to reduce these limitations. This paper presents a novel prototype of a diaphragm valve for passively compensated aerostatic pads. The proposed valve was obtained through the improvements of a previous prototype. The main goal of this new design of the valve was to improve the reliability, repeatability and accuracy of regulation. The novel prototype is modelled through the same lumped parameter model that was used for the previous prototype. The preliminary experimental results demonstrate the efficiency and effectiveness of the proposed valve.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A novel prototype of diaphragm valve for passively compensated aerostatic pads

Colombo

2023

Theoretical and Applied Mechanics - AIMETA 2022

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“…To improve the static characteristics of radial bearings, two-row feeding systems and longitudinal microgrooves made in the inter-row zone are used, which practically exclude circumferential air leakage, and contributes to a significant increase in the load capacity [15][16][17]. To reduce compliance, aerostatic bearings with active air flow compensation are used, where inlet flow compensators; membrane regulators of the nozzle-damper type with throttles in the form of diaphragms with sharp edges and in the form of flat slots [18][19][20][21][22] or Laub elastic orifices, are used [23][24][25]. The use of inlet membrane or elastic regulators makes it possible to reduce the static compliance to zero and even negative values (in the latter case, the increments of the load and the bearing gap have the same signs).…”

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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“…Solving the issues appearing during operation of all of these bearings in complex drive trains requires innovative approaches based on the experience and the physical understanding of the particular phenomena by tribology engineers. This Special Issue (SI) contributes to the latest steps in understanding bearing operating behavior [1][2][3][4][5][6], its interaction with lubricants [7,8], and its role as a component in the drive train [9][10][11][12].…”

mentioning

confidence: 99%

“…In their theoretical study, the authors apply three types of heterogeneous/smooth sliding surface arrangements to a journal bearing in a CFD analysis and gain an improvement of load-carrying capacity and average acoustic power level compared to the conventional plain surface design. Colombo et al [5] derive a design procedure for passively compensated bearings controlled by diaphragm valves applied in aerostatic bearings. Numerical investigations for a single pad show that significant improvements of stiffness can be achieved by the valve design.…”

mentioning

confidence: 99%