Abstract: An improved system for magnetorheological finishing of a substrate comprising a vertically oriented bowl-shaped carrier wheel having a horizontal axis. The carrier wheel is preferably an equatorial section of a sphere, such that the carrier surface is spherical. The wheel includes a radial circular plate connected to rotary drive means and supporting the spherical surface which extends laterally from the plate. An electromagnet having planar north and south pole pieces is disposed within the wheel, within the envelope of the sphere and preferably within the envelope of the spherical section defined by the wheel. The magnets extend over a central wheel angle of about 120° such that magnetorheological fluid is maintained in a partially stiffened state ahead of and beyond the work zone. A magnetic scraper removes the MRF from the wheel as the stiffening is relaxed and returns it to a conventional fluid delivery system for conditioning and re-extrusion onto the wheel.

Abstract: A magnetorheological fluid delivery system includes a mixing and tempering vessel. Fluid is admitted to the vessel via a plurality of tangential ports, creating a mixing of the fluid in the vessel and promoting homogeneity. Fluid may be reconstituted in the vessel by metered addition of carrier fluid. A fixed-speed centrifugal pump disposed in the vessel pressurizes the system. Fluid is pumped through a magnetic-induction flowmeter and a magnetic flow control valve having solenoid windings whereby MR fluid is magnetically stiffened to restrict flow. A closed-loop feedback control system connects the output of the flowmeter to performance of the valve. A nozzle having a slot-shaped bore dispenses MR fluid for re-use in the work zone.

Abstract: Jet-induced finishing of a substrate surface includes means for covering the surface with an abrasive liquid slurry and means for impinging a jet of fluid, either a gas or a liquid, against the slurry to create a high-shear work zone on the substrate surface whereby portions of the substrate are lifted and removed to alter the shape of the surface towards a predetermined shape and/or smoothness. The surface may be covered as by cascading a flowing layer of slurry over it or by impinging slurry onto the work zone or by immersing the substrate in a pool of the slurry. A nozzle for dispensing the jet fluid is precisely located at a predetermined distance and angle from the surface to be finished. A coarse removal function is provided by disposing the nozzle tip at a first distance from the substrate surface, and a fine removal function is provided by disposing the nozzle closer to the substrate surface.

Abstract: An improved system for magnetorheological finishing of a substrate comprising a vertically oriented bowl-shaped carrier wheel having a horizontal axis. The carrier wheel is preferably an equatorial section of a sphere, such that the carrier surface is spherical. The wheel includes a radial circular plate connected to rotary drive means and supporting the spherical surface which extends laterally from the plate. An electromagnet having planar north and south pole pieces is disposed within the wheel, within the envelope of the sphere and preferably within the envelope of the spherical section defined by the wheel. The magnets extend over a central wheel angle of about 120° such that magnetorheological fluid is maintained in a partially stiffened state ahead of and beyond the work zone. A magnetic scraper removes the MRF from the wheel as the stiffening is relaxed and returns it to a conventional fluid delivery system for conditioning and re-extrusion onto the wheel.

Abstract: A magnetic wiper for removing magnetorheological fluid from a carrier surface includes a horseshoe magnet having north and south polepieces elongated in a first direction orthogonal to a second direction of magnetic flux in the magnet. The polepieces are generally parallel at their free ends in the first direction and are preferably arcuate such that the 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 narrow gap therebetween containing a magnetic fringing field extending beyond the free ends.

Abstract: A magnetic wiper for removing magnetorheological fluid from a carrier surface includes a horseshoe magnet having north and south polepieces elongated in a first direction orthogonal to a second direction of magnetic flux in the magnet. The polepieces are generally parallel at their free ends in the first direction and are preferably arcuate such that the 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 narrow gap therebetween containing a magnetic fringing field extending beyond the free ends.

Abstract: A magnetic wiper for removing magnetorheological fluid from a carrier surface includes a horseshoe magnet having north and south polepieces elongated in a first direction orthogonal to a second direction of magnetic flux in the magnet. The polepieces are generally parallel at their free ends in the first direction and are preferably arcuate such that the 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 narrow gap therebetween containing a magnetic fringing field extending beyond the free ends.

Abstract: A method and apparatus for finishing a workpiece surface using MR fluid is provided wherein the workpiece is positioned near a carrier surface such that a converging gap is defined between a portion of the workpiece surface and the carrier surface; a magnetic field is applied substantially at said gap; a flow of stiffened MR fluid is introduced into said converging gap such that a work zone is created in the MR fluid to form a sub-aperture transient finishing tool for engaging and causing material removal at the portion of the workpiece surface; and the workpiece or the work zone is moved relative to the other to expose different portions of the workpiece surface to the work zone for predetermined time periods to selectively finish said portions of said workpiece surface to predetermined degrees.

Abstract: A method and apparatus for finishing a workpiece surface using MR fluid is provided wherein the workpiece is positioned near a carrier surface such that a converging gap is defined between a portion of the workpiece surface and the carrier surface; a magnetic field is applied substantially at said gap; a flow of stiffened MR fluid is introduced into said converging gap such that a work zone is created in the MR fluid to form a sub-aperture transient finishing tool for engaging and causing material removal at the portion of the workpiece surface; and the workpiece or the work zone is moved relative to the other to expose different portions of the workpiece surface to the work zone for predetermined time periods to selectively finish said portions of said workpiece surface to predetermined degrees.

Abstract: A magnetorheological fluid comprises non-colloidal magnetic particles, an abrasive, water, glycerol, and an alkaline buffer. The abrasive may be CeO.sub.2, the non-colloidal magnetic particles may be carbonyl iron, and the alkaline buffer may be Na.sub.2 CO.sub.3. The fluid is useful for magnetorheological finishing.

Abstract: A method and apparatus for finishing a workpiece surface using MR fluid is provided wherein the workpiece is positioned near a carrier surface such that a converging gap is defined between a portion of the workpiece surface and the carrier surface; a magnetic field is applied substantially at said gap; a flow of stiffened MR fluid is introduced into said converging gap such that a work zone is created in the MR fluid to form a sub-aperture transient finishing tool for engaging and causing material removal at the portion of the workpiece surface; and the workpiece or the work zone is moved relative to the other to expose different portions of the workpiece surface to the work zone for predetermined time periods to selectively finish said portions of said workpiece surface to predetermined degrees.