Influence of Supporting Characteristics on Sphericity of Ceramic Balls in Rotated Dual-Plates Lapping Process

2009 ◽  
Vol 69-70 ◽  
pp. 69-73 ◽  
Author(s):  
Bing Hai Lv ◽  
Ju Long Yuan ◽  
F. Cheng ◽  
Fan Yang
Keyword(s):  
Numerical Calculation ◽  
Fourier Analysis ◽  
Support System ◽  
Spherical Surface ◽  
Surface Generation ◽  
Shape Error ◽  
Lower Natural Frequency ◽  
Sinusoidal Waveform ◽  
Higher Spin ◽  
Ball Surface

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.

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

2000 ◽  
Vol 214 (4) ◽  
pp. 351-357 ◽  
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.

New Method of Spherical Surface Defect Detection Based on Machine Vision

2011 ◽  
Vol 295-297 ◽  
pp. 1274-1278 ◽  
Author(s):  
Jian Xi Yang ◽  
Fa Yu Zhang ◽  
Xiao Xia Song ◽  
Hong Zhe Xu
Keyword(s):  
Surface Defect ◽  
Spherical Surface ◽  
Steel Ball ◽  
Defect Inspection ◽  
Surface Reflection ◽  
Video Cameras ◽  
Quality Classification ◽  
Red Led ◽  
Ball Surface ◽  
Surface Defect Detection

According to requirements of online steel ball surface defect inspection, the automatic detection method of spherical surface defect on the track has been posed. To ensure photographing of the whole steel ball surface, the six CCD video cameras are used in this system. To overcome steel ball surface reflection, the red LED light source is used, and then the real and clear images are got. The steel ball surface defect is recognized accurately by means of image recognition technology and image reconstruction technology etc. This method provides theoretical basis and technical support for ball defection and quality classification.

Precision Grinding of Concave Spherical Surface of High-Alumina

2008 ◽  
Vol 368-372 ◽  
pp. 726-728 ◽  
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.

Controlling Profile Error for Spherical Surface Micro-Lens in Precision Grinding

2011 ◽  
Vol 215 ◽  
pp. 361-365
Author(s):  
Wei Ren ◽  
Zhi Hui Xia ◽  
C.Q. Han
Keyword(s):  
Mathematical Model ◽  
Measurement Error ◽  
Spherical Surface ◽  
Alignment Error ◽  
Shape Error ◽  
Profile Error ◽  
Machined Surface ◽  
Ultra Precision ◽  
Profile Accuracy ◽  
Micro Lens

As the consumer market in the optics, electronics and aerospace industries grows, the profile accuracy demand for ultra-precision flat, spherical and aspheric optical surface micro-lens increases. Previous studies have found that machine system accuracy, tool alignment error and tool radius measurement error impact greatly on the profile accuracy of the machined surface. In this paper, we developed a grinding system based on the ultra-precision diamond lathe, presented a unified mathematical model of effects of all the geometric errors to the shape error by using the multi-body system theory. Aiming at the main source of profile error, the practical mathematical model is derived, and their propagation coefficients to profile error are calculated. By means of simulation analysis and grinding experiments of spherical part of tugnsten carbide, we conclude that the radial tool alignment error is the main influencing factor for the profile error of spherical surface; while tool radius measurement error influence the radius of sphere only.

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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