| 摘要 |
PURPOSE:To obtain a resin bond type rare earth radial anisotropic cylindrical permanent magnet which has a small internal diameter and is long and thin by providing a core at the center of a compression molding metal mold. CONSTITUTION:Definite quantity of a mixture of heat curing resin and rare earth magnetic powder is filled in a ring 14 from a hopper 13, the ring 14 is placed under a space between a lower core 15 and a die 16, an upper punch 17 is lowered and the filling operation is finished. In this case, an upper core 22 consisting of magnetic material and an upper magnetic circuit 21 are also lowered. Then, a direct current is let flow in an upper magnetic field coil 19 and a lower magnetic field coil 20 and the magnetic powder in the mixture is orientated radially. Under these conditions, the upper punch 17 is further lowered, a required pressure is applied, a bottom lid 24 is removed, the pressed mixture passes through the tapered part of the lower core and the die, squeezed to required dimensions, pushed out from a metal mold being demagnetized by a reverse magnetic line of force from the orientation generated at the thin straight parts of the lower edge of a lower magnetic circuit 23 and the lower core 15 and is made a radial anisotropic cylindrical permanent magnet. |
