GB950278A - Improvements in or relating to holding magnets - Google Patents

Abstract

950,278. Laminates. DARWINS Ltd. Dec. 1, 1960 [Dec. 2, 1959], No. 40871/59. Drawings to Specification. Heading B5N. [Also in Division H1] A holding magnet comprises a peripheral portion consisting of alternating layers of sheets of plastic material in which has been compounded powdered permanent magnet material of high coercive force, and sheets of flexible material of relatively high magnetic permeability, the sheets with the material of high coercive force being magnetized perpendicularly to their surfaces, and the polarity being reversed between one such sheet and the next such sheet separated from it by a sheet containing the material of high permeability, the edges of the whole assembly of sheets being flush with each other at at least one end of the peripheral portion. The plastic material may be rubber, synthetic rubber, polyethylene or polyvinyl chloride. The material of high coercive force may be barium ferrite. The sheet of high permeability may be formed of plastic material with which a powdered material of high permeability, e.g. soft iron, has been compounded, or may be a thin metallic sheet, e.g. of soft iron. The sheets may be stuck together by adhesive, or by bonding. Each magnetized sheet may have one surface wholly of one polarity, and the opposite surface wholly of the other, or the polarity of each sheet may be reversed alternately in bands or areas over the face of the sheet, provided that fairly closely corresponding reversal takes place in the alternate sheets. Magnets may be formed by winding a sheet material of four layers, two magnetized in opposite senses, the other two of high permeability interleaved therewith, around the inside or outside of a former of regular or irregular shape, and may then serve to hold the former in place on a ferromagnetic surface. Specifications 950,273 and 950,277 are referred to.