Dynamic characteristics of an aerostatic bearing spindle and its influence on surface topography in ultra-precision diamond turning

Dynamic vibrations of air bearing motor spindles have significant influence on the surface quality in ultra-precision machining. In this article, the influence of the vibration caused by the unbalanced magnetic force on the diamond turning is investigated on the basis of the theoretical and experimental method. A permanent magnet motor model (10 poles and 12 slots) is built and then simulated to gain a periodic unbalanced magnetic force. The effects of unbalanced magnetic force on the inclination of the spindle shaft is analyzed, which would affect the surface quality of the workpiece, and the surface topography of the workpiece is predicted during an unbalanced magnetic force acting on air bearing motor spindle. The theoretical analysis and experimental turning results validate that the angle between the direction of unbalanced magnetic force and the feed direction has a certain relationship with the profile of the machined surface. Also, under different turning speeds and directions, the surface topography of the machined workpiece shows a 10-cycle-per-revolution pattern, which has good agreement with the simulations of periodic unbalanced magnetic force. This research work provides a theoretical foundation for the fault diagnosis of air bearing motor spindle caused by motor rotor eccentricity and its effect on surface generation in turning.

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A Study of Factors Affecting Surface Quality in Ultra-Precision Raster Milling

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.339.400 ◽

2007 ◽

Vol 339 ◽

pp. 400-406 ◽

Cited By ~ 6

Author(s):

M.N. Cheng ◽

Chi Fai Cheung ◽

Wing Bun Lee ◽

Sandy To

Keyword(s):

Surface Roughness ◽

Surface Quality ◽

Dynamic Characteristics ◽

Diamond Turning ◽

Factors Affecting ◽

Cutting Geometry ◽

Milled Surface ◽

Ultra Precision ◽

Process Factors

Ultra-precision raster milling is an emerging manufacturing technology for the fabrication of high precision and high quality components with a surface roughness of less than 10 nm and a form error of less than 0.2 μm without the need for any subsequent post polishing. Surface quality of a raster milled surface is affected by process factors and material factors, respectively. The process factors involve cutting conditions, cutting strategies, and relative vibration between the tool and the workpiece which are related to the cutting geometry and the dynamic characteristics of the cutting process. The material factors considered are material property and swelling of the work materials. Due to different cutting mechanics, the process factors affecting the surface quality are more complicated, as compared with ultra-precision diamond turning, such as swing distance and step distance. This paper presents an experimental investigation of the distinctive process factors affecting the surface roughness in ultra-precision multi-axis raster milling. Experimental results indicate that the influence due to the process factors can be minimized through a proper selection of operational settings and better control of dynamic characteristics of the machine.

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Dynamic Quality of an Aerostatic Thrust Bearing with a Microgroove and Support Center on Elastic Suspension

Mathematics ◽

10.3390/math9131492 ◽

2021 ◽

Vol 9 (13) ◽

pp. 1492

Author(s):

Vladimir Kodnyanko ◽

Stanislav Shatokhin ◽

Andrey Kurzakov ◽

Lilia Strok ◽

Yuri Pikalov ◽

...

Keyword(s):

Dynamic Characteristics ◽

Negative Impact ◽

Aerostatic Bearing ◽

Elastic Suspension ◽

Variable Parameters ◽

Aerostatic Bearings ◽

Improved Design ◽

Dynamic Quality ◽

Bearing Layer

The disadvantage of aerostatic bearings is their low dynamic quality. The negative impact on the dynamic characteristics of the bearing is exerted by the volume of air contained in the bearing gap, pockets, and microgrooves located at the outlet of the feeding diaphragms. Reducing the volume of air in the flow path is a resource for increasing the dynamic quality of the aerostatic bearing. This article presents an improved design of an axial aerostatic bearing with simple diaphragms, an annular microgroove, and an elastic suspension of the movable center of the supporting disk. A mathematical model is presented and a methodology for calculating the static characteristics of a bearing and dynamic quality indicators is described. The calculations were carried out using dimensionless quantities, which made it possible to reduce the number of variable parameters. A new method for solving linearized and Laplace-transformed boundary value problems for transformants of air pressure dynamic functions in the bearing layer was applied, which made it possible to obtain a numerical solution of problems sufficient for practice accuracy. The optimization of the criteria for the dynamic quality of the bearing was carried out. It is shown that the use of an elastic suspension of the support center improves its dynamic characteristics by reducing the volume of compressed air in the bearing layer and choosing the optimal volume of the microgroove.

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Diffractive optical characteristics of nanometric surface topography generated by diamond turning

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2021.04.012 ◽

2021 ◽

Vol 67 ◽

pp. 23-34

Author(s):

Dongxu Wu ◽

Chengwei Kang ◽

Fusheng Liang ◽

Guangpeng Yan ◽

Fengzhou Fang

Keyword(s):

Surface Topography ◽

Diamond Turning ◽

Optical Characteristics

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