A novel restrictor combining membrane withpolyfoam for aerostatic bearings

• Main Authors: Feng-yang Xie, 謝豐仰
• Other Authors: Sy-Wei Lo
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/62725917998886777972

碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 101 === Among various types of restrictor, the membrane one can offer better adjusting ability and higher stability, however, the traditional design is only suitable for the hydraulic systems. To be applied to the low viscous air medium, a membrane jointed with polyfoam is used as the impedance element, together with three types of throttle bolt, to generate various pressures above and beneath the membrane for various effects of compensation. The solid bolt halts the air flow so that the pressure above the membrane is equal to zero; the bolt with a hole of diameter 2 mm can equalize the pressures on both sides of the membrane; while the bolt containing a capillary of diameter 0.2 mm can make the pressure above the membrane slightly smaller than the other one. In this study, the restrictor is integrated with nozzle to form a thrust bearing and a series of static stiffness experiments is conducted. The experimental results showed that: The restrictor with bolt having 0.2mm diameter capillary (length 0.8mm) shows the best performance of the compensation effect for load ranging from 16 kgf to 26 kgf, where the air film thickness is nearly unaffected by the loading and is maintained between 20μm to 18μm, the maximum stiffness can be up to 35.71 kgf/μm; The next one is the restrictor with solid throttle bolt, for which from 16 kgf to 26 kgf, the air gap can be maintained between 16μm and 13μm. As for the restrictor using membrane with no polyfoam, the gap is found changing from 16μm to 14μm and its stiffness lies between 23.81 kgf/μm and 17.24 kgf/μm. In conclusion, the study verifies that a superior performance of aerostatic thrust bearing can be achieved when a polyfoam is added to the membrane type restrictor.