Influences of the geometrical and material parameters on the static characteristics of metallic and polymer aerostatic thrust bearings

• Main Authors: Chi-Heng Yu, 余其衡
• Other Authors: Sy-Wei Lo
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/79354021167300607231

碩士 === 國立雲林科技大學 === 機械工程系 === 103 === A flexible bearing surface is combined with the concept of polymer restrictor to enhance the load capacity of aerostatic bearing in this thesis: Firstly a flexible disk, which is circularly supported near its rim, is adopted as the bearing component so that it can create a concave geometry and keep the air pressure to increase the load capacity. On the other hand, a polymer restrictor with capillary is set in the central outlet of air. The inner diameter of the capillary can expand with respect to the increase in load for compensating the air flux. Finally, the whole bearing is made of polymer body covered with metallic membrane. The polymer body can be fabricated conveniently by injection or molding and generates a damping effect under dynamic forces; while the metallic membrane possesses the ready-to-use roughness and prevents the polymer bulk from wear in case of over-thin air gap. The research proceeds from understanding the influences of the geometries, metallic materials and the supporting position on the characteristics of bearing. Then change the metals into polymer, which is combined with metallic membrane, and carry out a series of numerical simulations. Lastly use the Taguchi method to optimize the key factors that affect the load capacity and static stiffness. The experiments show that the circularly supported aerostatic bearing with polymer restrictor can tremendously improve the load ability. A thinner disk together with circular support at the position of approximately 5/6 of the disk radius can generate better results. The numerical analysis indicates that the Young’s modulus of the membrane has great impact on the bearing performance. The bearing with PU body and stainless steel membrane exhibits both the greatest loading capability and stiffness. Taking the bearings of radius 30 mm as examples, at elevation 9.5µm the stiffness soars from 16 N/µm of typical bearing to 350 N/µm under supply pressure 5 bar; meanwhile the load capacity also enhances from 346 N to 704N.