Method of manufacturing polar anisotropic magnet, method of manufacturing magnet assembly, polar anisotropic magnet, magnet assembly, and composite magnet assembly

A method of manufacturing a magnet assembly having a cylindrical shape, the method of manufacturing a magnet assembly comprising, in a following order:

• a powder material preparation step where a powder material for a magnet is prepared;
• an in-field molding step where a “magnet base material” having a first main surface and a second main surface disposed on a side opposite to the first main surface is molded, wherein the powder material is charged into the inside of a mold that corresponds to a shape of the magnet base material, and a magnetic field having lines of magnetic force in a single direction and in parallel is applied to an outer side of the mold from a side that corresponds to the first main surface to a side that corresponds to the second main surface, thus molding the magnet base material;
• a cutting step where, a surface that forms an outer diameter surface of the magnet assembly when assembled as the magnet assembly is defined as a “scheduled outer diameter surface” and a surface that forms an inner diameter surface when assembled as the magnet assembly is defined a “scheduled inner diameter surface”, a cutting line of the scheduled outer diameter surface is set to have inclination of an angle θ1 with respect to the first main surface, the magnet base material is cut along the cutting line of the scheduled outer diameter surface, a cutting line of the scheduled inner diameter surface is set to have inclination of an angle θ2 with respect to the first main surface, the magnet base material is cut along the cutting line of the scheduled inner diameter surface, thus cutting out a magnet base material piece having at least the scheduled outer diameter surface and the scheduled inner diameter surface on an outer surface;
• an assembly step where a plurality of the magnet base material pieces are combined with each other so as to assemble a magnet base material assembly;
• and
• a magnetization step where a predetermined magnetic field is applied to the magnet base material assembly from an outside of the magnet base material assembly at a predetermined position, thus magnetizing the magnet base material assembly.

A method of manufacturing a polar anisotropic magnet having four surfaces as viewed in cross section:

• the method of manufacturing a polar anisotropic magnet comprising, in a following order:
• a powder material preparation step in which a powder material for a magnet is prepared;
• an in-field molding step in which a “magnet base material” having a first main surface and a second main surface on a side opposite to the first main surface is molded in such a manner that the powder material is charged into the inside of the mold that corresponds to a shape of the magnet base material, and a magnetic field having lines of magnetic force in a single direction and in parallel is applied to an outer side of the mold from a side that corresponds to the first main surface to a side that corresponds to the second main surface, thus molding the magnet base material;
• a cutting step in which, when the polar anisotropic magnet is assembled as a magnet assembly, a surface of the polar anisotropic magnet that is scheduled to form an outer diameter surface of the magnet assembly is defined as a “scheduled outer diameter surface” and a surface of the polar anisotropic magnet that is scheduled to form an inner diameter surface of the magnet assembly is defined as a “scheduled inner diameter surface”, a cutting line of the scheduled outer diameter surface is set so as to have an inclination of an angle θ1 with respect to the first main surface and the magnet base material is cut along the cutting line of the scheduled outer diameter surface, a cutting line of the scheduled inner diameter surface is set so as to have an inclination of an angle θ2 with respect to the first main surface and the magnet base material is cut along the cutting line of the scheduled inner diameter surface, thus cutting out a magnet base material piece having at least the scheduled outer diameter surface and the scheduled inner diameter surface on an outer surface;
• a sub assembly step in which a magnet base material sub assembly having four surfaces is assembled by combining at least four magnet base material pieces in such a manner that, wherein, in the sub assembly step, assuming the surface on which a magnetic flux is to be generated in a concentrated manner among the four surfaces as an effective surface, on a side of the magnet base material sub assembly that forms the effective surface, the magnet base material piece of a horizontal system is disposed in a state where cutting is performed such that the angle θ1 and the angle θ2 in the cutting step are each set to a value that falls within a range from more than 45 degrees to less than 90 degrees, and on a side of the magnet base material sub assembly opposite to the side on which the effective surface is formed, the magnet base material piece of a vertical system is disposed in a state where cutting is performed such that the angle θ1 and the angle θ2 in the cutting step are each set to a value that falls within a range from 0 degrees or more to less than 45 degrees, thus assembling the magnet base material sub assembly;
• and
• a four-way magnetization step where a magnetic field in a first direction is applied to the effective surface of the magnet base material sub assembly, and a magnetic field in a second direction is applied to the remaining three surfaces in a state where the magnetic field in the first direction and the magnetic field in the second direction surround the magnet base material sub assembly, thus magnetizing the magnet base material sub assembly.