Patent attributes
A radially anisotropic magnet is prepared by furnishing a cylindrical magnet-compacting mold comprising a die, a core, and top and bottom punches, packing a magnet powder in the mold cavity, applying a magnetic field across the magnet powder, and forcing the top and bottom punches to compress the magnet powder for compacting the magnet powder by a horizontal magnetic field vertical compacting process. The top punch is divided into segments so that the magnet powder may be partially compressed; in the step of compacting the magnet powder packed in the mold cavity by a horizontal magnetic field vertical compacting process, the magnet powder is partially compressed by the segments of the top punch cooperating with the bottom punch for thereby consolidating the partially compressed zones of magnet powder to a density from 1.1 times the packing density to less than the compact ultimate density; and thereafter, the entire magnet powder in the cavity is compressed under a pressure equal to or greater than that of partial compression by the entire top and bottom punches for finally compacting the magnet powder.
