Abrading – Machine – Immersion
Reexamination Certificate
2001-06-14
2001-10-30
Hail, III, Joseph J. (Department: 3723)
Abrading
Machine
Immersion
C451S036000, C451S103000, C451S104000
Reexamination Certificate
active
06309285
ABSTRACT:
The present invention relates to apparatus for wiping a fluid from a surface, more particularly to apparatus for removing and capturing a liquid being carried on a moving surface, and most particularly to apparatus for removing and capturing a ribbon of magnetorheological fluid from a fluid-conveying surface in a magnetorheological finishing apparatus.
It is known to use abrasive fluids having magnetorheological properties to shape, finish, and polish objects, especially optical elements such as lenses and mirrors. See, for example, U.S. Pat. No. 5,616,066, “Magnetorheological Finishing of Edges of Optical Elements,” issued Apr. 1, 1997 to Jacobs et al., U.S. Pat. No. 5,795,212, “Deterministic Magnetorheological Finishing,” issued Aug. 18, 1998 to Jacobs et al., and U.S. Pat. No. 5,951,369, “System for Magnetorheological Finishing of Substrates,” issued Sep. 14, 1999 to Kordonsky et al. The relevant disclosures of these three patents are hereby incorporated by reference. As used herein, all ablative processes wherein abrasive particles are impinged onto a surface to be ablatively shaped are referred to collectively as “finishing.”
A magnetorheological finishing machine, as disclosed in the incorporated references, includes a carrier surface on a rotatable element referred to as a carrier wheel. The carrier surface may reside on an axial face of the carrier wheel, or more commonly, on the peripheral radial surface of the wheel.. which typically is a cylindrical section or a spherical section disposed symmetrically about an equatorial plane. The carrier surface presents magnetorheological fluid to a work zone and carries spent fluid away. A magnetorheological finishing machine may further include a fluid handling system for regenerating spent fluid and for metering regenerated fluid to the work zone; a nozzle for dispensing fluid from the fluid handling system onto the carrier surface; and a mechanical scraper in contact with the carrier surface for removing spent fluid from the carrier surface and returning it to the fluid handling system to be regenerated.
In the known art, the contact scraper includes a chamber connected to a fluid return tube and open on the side facing the carrier surface. The sides of the chamber adjacent to the carrier surface are formed to conform generally to the surface, whether planar, cylindrical, or spherical, and are provided with an elastomeric lip which bears resiliently on the carrier surface passing by the chamber and which mechanically scrapes the magnetorheological fluid from the surface into the chamber.
A known art scraper has several serious shortcomings. First, the rubber lip can become worn and reduced in size by the abrasiveness of the magnetorheological fluid. Thus, the lip may need to be replaced frequently, requiring suspension of operations, such replacement being costly in operating time and replacement lips. Second, as the lip wears, the scraper must be advanced toward the carrier surface to maintain necessary contact with the surface and to compensate for lip wear. Such adjustment can be difficult to perform properly during operation of the finishing machine. Thus, the scraper is necessarily complicated in being both adjustable and advanceable. Third, the mechanical scraping action can wear, and thereby deform, the carrier surface, the correct shape of which is highly important to controlling the rate of finishing and the shape of the finishing zone. Particles of elastomer worn from the lip can contaminate the magnetorheological working fluid. Thus, unavoidable wear by the scraper can endanger the quality of finishing and shorten undesirably the working life of the carrier surface.
What is needed is a non-contact means for removing magnetorheological fluid from a carrier surface without mechanically scraping the carrier surface.
It is a principal object of the invention to provide an improved wiper for removing magnetorheological fluid from a carrier surface without mechanical contact between the wiper and the carrier surface.
It is a further object of the invention to provide an improved carrier surface wiper wherein the magnetorheological properties of the fluid are used to assist in removing the fluid from the surface.
It is a further object of the invention to provide an improved carrier surfaced wiper wherein the performance of the wiper is unaffected by the duration of use.
Briefly described, a magnetic wiper for removing magnetorheological fluid from a carrier surface includes a distorted horseshoe magnet having north and south polepieces elongated in width in a first direction orthogonal to a second direction of magnetic flux in the gap between the polepieces. The polepieces are generally parallel at their free ends in the first direction, the first gap therebetween containing a magnetic field, are preferably divergent inwardly of the wiper in the second direction to maximize the field strength at the free ends, and are preferably arcuate such that the concave inner polepiece forms a trough for receiving magnetorheological fluid removed from the carrier surface and conveying it to an exit tube. The free ends are shaped to conform closely to the shape of the carrier surface, forming a second gap between the free ends and the carrier surface, the second gap containing a magnetic fringing field extending beyond the free ends. The first amount of magnetorheological fluid conveyed into proximity with the free ends by the carrier surface is magnetically stiffened to a very stiff paste which is retained in the first and second gaps by the magnetic fields and is thereby prevented from continuing onward with the carrier surface. The stiffened fluid forms a dynamic liquid seal in the gaps such that additional magnetorheological fluid carried towards the magnetic gaps by the carrier surface is wiped and diverted away from the surface and into the trough formed by the inner polepiece. Thus, the magnet forms an effective remover of magnetorheological fluid from the carrier surface without any mechanical scraping contact with the surface. Further, there is no wear of the wiper with use, so that performance of the wiper is unaffected by duration of use.
REFERENCES:
patent: 5577948 (1996-11-01), Kordonsky et al.
patent: 5616066 (1997-04-01), Jacobs et al.
patent: 5775976 (1998-07-01), Kremen et al.
patent: 5795212 (1998-08-01), Jacobs et al.
patent: 5839944 (1998-11-01), Jacobs et al.
patent: 5951369 (1999-09-01), Kordonski et al.
patent: 6036580 (2000-03-01), Igelshteyn et al.
Gorodkin Gennadi
Hogan Stephen
Kordonski William
Sekeres Arpad
Hail III Joseph J.
Harris Beach LLP
Ojini Anthony
LandOfFree
Magnetic wiper does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic wiper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic wiper will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2561113