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Magnetic workholding device

  • US 6,489,871 B1
  • Filed: 12/08/2000
  • Issued: 12/03/2002
  • Est. Priority Date: 12/11/1999
  • Status: Expired due to Term
First Claim
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1. A magnetic device, comprising:

  • a cylindrical outer pole having a central axis and formed of a ferromagnetic material, said outer pole including a circular base and a cylindrical sleeve defining a cylindrical cavity opening outwardly from said base;

    a reversible magnetic unit located in said cavity including a cylindrical core having a magnetic axis aligned with said central axis and a normal magnetic polarity in an inactive state;

    a cylindrical inner pole formed of a ferromagnetic material operatively coupled to said core and inwardly radially spaced from said sleeve;

    an annular band between said sleeve and said inner pole, said band formed of a permanent magnetic material having a magnetic polarity transverse to said central axis and magnetically aligned with said normal magnetic polarity of the core whereby an internal magnetic circuit is established in the inactive state through said poles, said core and said permanent magnet to the exclusion of said workpiece, said reversible magnetic unit being operative to reverse the polarity of said core whereby an external circuit is established between said poles and said workpiece.

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