| 摘要 |
973,331. Moulding magnetic material. MAGNETFABRIK GEWERKSCHAFT WINDHORST. Feb. 22, 1963 [April 26, 1962], No. 7225/63. Heading B5A. [Also in Division H1] A method of producing an anisotropic permanent magnet with a desired preferred direction of magnetization from a coherent mass of magnetic material, comprises producing a different preferred direction of magnetization in the mass and subsequently so permanently deforming the mass as to change the preferred direction to the desired preferred direction. As shown, magnetic particles with or without a binder are subjected to an extrusion process through a nozzle such that on passing through the first part I which has a cross-section as shown at 3 the particles are subjected to a transverse magnetic field producing a magnetization as shown in dashed lines. On passing further through the nozzle the mass is " unbent " producing magnetization as shown in the cross-section 4. The mass may be barium ferrite suspended in water, and after extrusion it may be dried and sintered. In another embodiment the mass is compressed in a first die under a magnetic field and is then placed in a second die where the shape and hence the direction of magnetization are changed. In further disclosures rollers are used to effect the shaping, the change of shape and the magnetic orientation. The magnetic material may be barium ferrite, alnico, manganese-bismuth alloy and manganese-aluminium alloy. The binder if used may be a thermoplastic material. |
