| 摘要 |
1,196,228. Permanent magnets; magnetic compositions. R. L. ROWE, and D. PECCERILL. 19 Nov., 1968 [21 Nov., 1967], No. 54871/68. Headings H1P and H1H. [Also in Division B3] Anisotropic magnetic particles distributed in a binder formed into a tubular member are aligned by means of a core or magnet lying within the tube co-operating with magnets arranged outside the tube. As shown, Fig. 2, the tubular magnet is extruded by means of a die 9 and immediately passes between the poles 12, 13 of a D.C. energized electromagnet to align the particles within the binder which is still soft. A soft-iron core 10 is arranged within the tube to concentrate the magnetic field and is supported on the central member of the die. The poles of the electromagnet are shaped to the outside of the tube, Figs. 1 and 3 (not shown). In a modification, Figs. 3 to 5 (not shown), the poles of the electromagnet are in the form of grooved wheels arranged so that they rotate as the tube is moved between them. A groove may be provided in the wall of the tube by means of a cutting wheel, Figs. 6 and 7 (not shown), to aid in orientating the resulting magnet when used in a small D.C. motor. In a further modification. Figs. 8 and 9 (not shown), a slit is cut in the wall of the tube so that the centre core may be supported by members extending through the slit. The orientation groove or slit may be formed by a triangular plate attached to the extruding die, Figs. 10 and 11 (not shown). The core supported within the tube may itself be a magnet and may comprise the polepieces of an electromagnet the coil of which is located outside the tube and coupled to the polepieces by flat magnetic limbs which pass through a slit cut in the tube. The magnetic particles may comprise Ba, Pb, Sr or Mn-Bi ferrite and may be combined with Fe. The binder may be a polymer elastomer or rubber such as PVC, methylmethacrylate, urea formaldehyde, vinylacetate, vinylformaldehyde, buna N, or polyethylene or a silicone or a non-magnetic metallic material.
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