Electrolysis: processes – compositions used therein – and methods – Electrolytic erosion of a workpiece for shape or surface... – Gap maintenance or defined tool-workpiece gap
Reexamination Certificate
1999-07-06
2001-01-23
Valentine, Donald R. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic erosion of a workpiece for shape or surface...
Gap maintenance or defined tool-workpiece gap
C205S654000, C205S672000, C205S686000
Reexamination Certificate
active
06176998
ABSTRACT:
The present invention relates to a method of manufacturing a bearing ring for a bearing, whereby a groove to be serving as a raceway is formed which is subsequently electrochemically machined by passing a current across a narrow gap between said bearing ring and an electrode means, supplying electrolyte to the gap in a direction substantially tangential to the groove of the bearing ring, while rotating the bearing ring around an axis and removing material from the groove of said bearing ring facing said electrode.
Such a method is known from the Dutch patent application 91.01379. In this publication a method is described of electrochemical machining of a raceway of a bearing ring using a ball or slice thereof as the electrode.
This method has the disadvantage that during electrochemical machining not just the groove depth increases, but also the groove radius. Thus it is more difficult to match bearing rings and rotating bodies, resulting in a shorter operational life of the bearing.
The object of the present invention is to provide a simple and cost-effective method to electrochemically machine the raceway of a bearing ring, allowing more precise control over the shape and in particular maintaining the radius of curvature of the groove of the bearing ring, resulting in bearings having an increased operational life and better noise characteristics.
To this end the method according to the invention is characterized in that the groove is composed of a plurality of narrow circumferentially extending coaxial areas, and using as the electrode an electrode with a width tangential relative to the axis of rotation adapted to each particular circumferentially extending area such that during electrochemical machining the radius of curvature of the groove is kept constant.
Thus by using an electrode with a carefully chosen convex cross-section the rate of removal of material from each area rotating under the electrode is such that the radius of curvature of the groove remains constant.
According to a preferred embodiment the groove of the bearing ring is formed by honing and subsequently electrochemically machined using an electrode with a width tangential relative to the axis of rotation adapted to each particular circumferentially extending area such that the radius of curvature of the groove is kept constant.
This results in a bearing ring with superior characteristics with respect to waviness, smoothness and radius of curvature, allowing the manufacture of bearings of unprecedented quality.
Thus, the present invention also relates to a bearing comprising a bearing ring wherein the bearing ring is electrochemically machined according to the invention.
REFERENCES:
patent: 3766029 (1973-10-01), Haggerty
patent: 3900374 (1975-08-01), Haggerty
patent: 4772368 (1988-09-01), Rabian
patent: 2032262 (1971-04-01), None
patent: 9101379 (1993-03-01), None
Girardin Hervé
Wardle Frank Peter
Myers Jeffrey D.
SKF Engineering and Research Centre B.V.
Valentine Donald R.
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