System for magnetorheological finishing of substrates

摘要

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. The system is useful in finishing large concave substrates, which must extend beyond the edges of the wheel, as well as for finishing very large substrates in a work zone at the bottom dead center position of the wheel.