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

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

doi:10.3390/lubricants9050047

Federico Colombo, Andrea Trivella + Show 3 more

Open Access

https://doi.org/10.3390/lubricants9050047

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Abstract

Because of their distinctive characteristics, aerostatic bearings are particularly suitable for high-precision applications. However, because of the compressibility of the lubricant, this kind of bearing is characterized by low relative stiffness and poor damping. Compensation methods represent a valuable solution to these limitations. This paper presents a design procedure for passively compensated bearings controlled by diaphragm valves. Given a desired air gap height at which the system should work, the procedure makes it possible to maximize the stiffness of the bearing around this value. The designed bearings exhibit a quasi-static infinite stiffness for load variation ranging from 20% to almost 50% of the maximum load capacity of the bearing. Moreover, the influence of different parameters on the performance of the compensated pad is evaluated through a sensitivity analysis.

Highlights

Because of their distinctive characteristics, aerostatic bearings are suitable for high-precision applications
This paper presents a design procedure for passively compensated bearings controlled by diaphragm valves
This paper presents a design procedure for a circular and centrally fed aerostatic pad controlled by a diaphragm valve

Summary

Introduction

Because of their distinctive characteristics, aerostatic bearings are suitable for high-precision applications Their zero friction, cleanness and long life make aerostatic bearings successful in applications such as machine tools, measuring machines and power board testing [1]. The first attempts that were made to increase aerostatic bearing stiffness consisted of many sensitivity analyses concerning the type, location and size of the supply hole [5] This type of investigation was further enhanced with the aid of more accurate numerical models. Boffey et al [6] and Colombo et al [7] performed numerical and experimental studies to assess the effect of the supply pressure and orifice size and location on the performance of rectangular aerostatic pads In these works, it was found that choosing a lower nominal air gap height led to slightly higher stiffness

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