Dynamics of magnetic fluid support grinding of Si3N4 ceramic balls for ultraprecision bearings and its importance in spherical surface generation

Ceramic balls have become an important component in advanced bearings, and the sphericity of balls is a key qualification focused in lapping process. An investigation on the effect of dynamic behavior of ball support system on the performance of ball lapping in rotated dual-plates lapping method is carried out. Sinusoidal waveform in terms of Fourier analysis is employed to express the shape error of the ball surface, and a dynamic model for support is setup. It is found with numerical calculation that the variation of lapping load lags behind the variation of the shape error for the damping of support. A lower natural frequency of the support system, higher spin speed of balls and a larger value of spin angle in RDP lapping are better to rectify the shape error of balls and reduce the lagged effect. It is concluded that dynamics of lapping system must be taken into consideration in order to understand comprehensively the spherical surface generation mechanism.

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Spherical surface generation mechanism in the grinding of balls for ultraprecision ball bearings

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/1350650001543241 ◽

2000 ◽

Vol 214 (4) ◽

pp. 351-357 ◽

Cited By ~ 9

Author(s):

B Zhang ◽

A Nakajima

Keyword(s):

Kinematic Analysis ◽

High Speed ◽

Spherical Surface ◽

Generation Mechanism ◽

Surface Generation ◽

Ball Bearings ◽

Contact Points ◽

Ball Surface ◽

Precision Machines ◽

Good Agreement

Ultraprecision ball bearings are necessary for high-precision machines and/or high-speed machines since the vibration caused by ball bearings determines the precision of machines as a whole and may make high-speed machines fail to work. To produce ultraprecision ball bearings, it is necessary to clarify spherical surface generation mechanism in the grinding of balls. This paper is the first attempt to investigate the contact trace distribution on the ball surface, which is crucial to spherical surface generation. The kinematic analysis of the contact trace shows that the contact trace is a fixed circle on the ball surface and the contact points are not uniformly distributed on the ball surface. Experimental observation of the contact trace was also carried out. The observation is in good agreement with the analysis. Suggestions on how to distribute the contact trace over the whole ball surface and therefore to improve the precision of balls are given.

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A Study on Mathematical Modeling Technology for Magnetic-Fluid Grinding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.335-336.406 ◽

2011 ◽

Vol 335-336 ◽

pp. 406-410

Author(s):

Shu Qin Wu ◽

Yao Ming Li

Keyword(s):

Mathematical Modeling ◽

Magnetic Field ◽

Magnetic Fluid ◽

Work Piece ◽

Technological Parameters ◽

Si3n4 Ceramic ◽

Working Mechanism ◽

Modeling Technology ◽

Magnetic Center ◽

Grinding Time

The paper introduces the precision processing technology of grinding using magnetic fluid and presents the working mechanism of magnetic-fluid grinding. Based on Preston Equation, it also establishes a mathematical modeling for magnetic-fluid grinding, which is used to study the relationships between the effects of grinding and the variation of such technological parameters as the revolving speed of work-piece, the intensity of magnetic field, the distance between work-piece surface and magnetic center, the size of the magnetic fluid and grinding time, etc. Analysis on the grinding of Si3N4 ceramic-balls proves that the model has been well established.

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High Efficiency and Precision Grinding of Si3N4 Ceramic Balls Aided by Magnetic Fluid Support Using Diamond Wheels.

JSME International Journal Series C ◽

10.1299/jsmec.41.499 ◽

1998 ◽

Vol 41 (3) ◽

pp. 499-505 ◽

Cited By ~ 13

Author(s):

ZHANG Bo ◽

Tetsutaro UEMATSU ◽

Akira NAKAJIMA

Keyword(s):

Magnetic Fluid ◽

High Efficiency ◽

Precision Grinding ◽

Si3n4 Ceramic

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Precision Grinding of Concave Spherical Surface of High-Alumina

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.368-372.726 ◽

2008 ◽

Vol 368-372 ◽

pp. 726-728 ◽

Cited By ~ 1

Author(s):

Xiao Feng Zhang ◽

Bin Lin ◽

Fang Yang Zhang

Keyword(s):

Spherical Surface ◽

Alumina Ceramic ◽

Surface Generation ◽

High Alumina ◽

Grinding Wheel ◽

Machining Parameters ◽

Precision Grinding ◽

Cutting Depth ◽

Critical Cutting Depth ◽

Single Grain

The performances of high-alumina ceramic are analyzed such as physical and mechanical property. In consideration of its brittleness-ductility change, the critical cutting depth agc of high-alumina ceramic is 3μm. When the cutting depth of single grain is less than the critical cutting depth of alumina ceramic in precision manufacturing, the material is wiped off with ductility. So the cutting depth of single grain agm should be selected within 0.1~2.5μm.Grinding wheel sharp edge is utilized for the spherical surface generation cutting. The ceramic-bonded fine grain diamond wheel is selected after considering manufacturing technology, machining parameters, its making and mending. The granularity of grinding wheel is M1~M5 and the consistence is 125%. The method of spherical surface generation cutting and the effect of high-alumina ceramic ductile machining were verified by the experiment of high-alumina ceramic precision grinding using precision grinding machine MGK1420. The result shows that the surface quality is very high and achieves the requirements.

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A magnetic super lattice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126597 ◽

1987 ◽

Vol 45 ◽

pp. 360-361 ◽

Cited By ~ 1

Author(s):

M.D. Bentzon ◽

J. v. Wonterghem ◽

A. Thölén

Keyword(s):

Thermal Decomposition ◽

Oleic Acid ◽

Magnetic Fluid ◽

Magnetic Particles ◽

Carbon Film ◽

Thick Layer ◽

Amorphous Iron ◽

Super Lattice ◽

Carrier Liquid ◽

Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

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