Magnetic fluid grinding mechanics

Childs, T.H.C.; Jones, D. A.; Mahmood, Sheikh T.; Zhang, B.; Kato, Koji; Umehara, Noritsugu

doi:10.1016/0043-1648(94)90182-1

Cited by 32 publications

(18 citation statements)

References 5 publications

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“…To ensure that the lapping pressure is evenly distributed without bending moment, the spring load is applied through a spherical element to the cone surface of a blind countersink on the top centre of the backing plate (13). A digital time counter (14) is connected to the voltage input of the a.c. motor, and the actual lapping time is counted.…”

Section: Design Of a Novel Eccentric Lapping Machinementioning

confidence: 99%

A novel eccentric lapping machine for finishing advanced ceramic balls

Kang

Hadfield

2001

Proceedings of the Institution of Mechanical Engineers, Part B:

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Advanced ceramic balls are used extensively in hybrid precision ball bearings and show advantages in high speed, high temperature, high load and hostile environment. Finishing these balls with high quality, good eYciency and low cost is critical to their widespread application. A brief review of the methods for ® nishing ceramic balls is presented. The design of a novel eccentric lapping machine for ® nishing advanced ceramic balls is described. The kinematics of eccentric lapping is analysed and discussed, the symbolic expressions for the ball spin angular speed, ! b , ball spin angle, , and ball circulation angular speed, ! c , are derived and numerical solutions are plotted. Two kinds of hot isostatically pressed (HIPed) silicon nitride ball blanks (13.25± 13.50 mm in diameter) were lapped and polished to 12.700 mm using this machine. A maximum material removal rate of 68 mm/h was achieved at the lapping step, which is much higher than by the traditional concentric lapping method. The polished ball surface roughness, R a , value is 0.003 mm, and the ball roundness is 0.08± 0.09 mm, which is above grade 5 and close to grade 3 of the precision bearing ball speci® cation. This machine can be used as a prototype to develop a larger-scale machine for production.Keywords: lapping machine, ® nishing method, eccentric lapping, ceramic ball ® nishing, silicon nitride, hybrid bearings, ball lapping mechanism NOTATION E eccentricity (the distance between the rotating axis and the centre of the circular V-groove) r i radius from the rotating axis of the lower lapping plate to the ball± V-groove inner contact point r o radius from the rotating axis of the lower lapping plate to the ball± V-groove outer contact point R b ball radius R g circular V-groove radius R i radius from the centre of the circular V-groove to the ball± V-groove inner contact point R o radius from the centre of the circular V-groove to the ball± V-groove outer contact point V ip lower plate linear speed at the ball± V-groove inner contact point perpendicular to the radial plane through the centre of the circular V-groove V op lower plate linear speed at the ball± V-groove outer contact point perpendicular to the radial plane through the centre of the circular V-groove ball spin angle V-groove half-angle ! b ball spin angular speed ! c angular speed of ball circulation around the circular V-groove « p lower lapping plate angular speed INTRODUCTION

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Section: Design Of a Novel Eccentric Lapping Machinementioning

confidence: 99%

A novel eccentric lapping machine for finishing advanced ceramic balls

Kang

Hadfield

2001

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…However, the machining cycle usually requires a long considerable time (6-16 weeks) because of the low material removal rate [3,[9][10][11]. To improve the machining efficiency, MFP was then proposed, which is based on the magneto-hydrodynamic behaviour of a magnetic fluid, and can lower the grinding force and improve the final ball accuracy; nonetheless it is environment-unfriendly and the cycle time also lasts for 20-30 hours [1,12,13].…”

Section: Introductionmentioning

confidence: 99%

Sphere forming mechanisms in vibration-assisted ball centreless grinding

Cui

2016

International Journal of Machine Tools and Manufacture

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This paper aims to clarify the sphere forming mechanisms in vibration-assisted ball centreless grinding, a new technique for effectively processing balls using ultrasonic vibrations. Based on a comprehensive analysis of the ball rotation motion, geometrical arrangement and stiffness of the whole grinding system, a reliable mechanics model was successfully developed for predicting the sphere forming process. Relevant experiments conducted showed that the model had captured the mechanics and the major sphere forming mechanisms in ball centreless grinding. It was found that the ball whole surface can be well ground with a high accuracy, while efficiency is much enhanced compared with that in the traditional methods.The ball rotational speed which is controlled by the ultrasonic regulator has a great impact on final sphericity, and the speed controlled by the ultrasonic shoe dominates the whole processing time. To achieve a stable and high precision grinding, the ball needs to rotate rhythmically, and the wheel feed per step and the ball location angle should be controlled in a critical range.

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“…Since, the float is made of a nonmagnetic material, the balls are pressed against the rotating drive shaft by the magnetic force and are polished by the abrasive action under low-load and high-speed condition. A series papers have been published on this method [9][10][11][12]. To understand the spherical surface generation mechanism, Zhang and Nakajima [13] are the first attempt to analyze the lapping tracks in terms of the kinematics of the ball lapping process.…”

Section: Introductionmentioning

confidence: 99%