Magnetic gripping apparatus having circuit for eliminating residual flux

A magnetically gripping device for gripping ferromagnetic workpieces, comprising a base plate, peripheral walls and at least a first and second pole unit, each pole unit comprising a main pole piece having an outer face defining a gripping surface, and main permanent magnet arranged between said main pole piece and the base plate;

• an intermediate pole member being disposed between the main pole pieces of said pole units, said intermediate pole member extending from the base plate to the gripping surface;
• secondary magnets disposed between said pole member and said pole pieces and between said pole pieces and said peripheral walls the device further comprising first electrical windings encicling said main magnets and operatively connected to a control unit to activate and deactivate the device, in which a demagnetizing circuit for eliminating residual flux or remanence in the workpieces, said demagnetizing circuit comprising a demagnetizing winding encircling the above-mentioned intermediate pole member and a demagnetizing control unit to generate a progressively decreasing demagnetizing cyclical field in said intermediate pole member and between the workpiece to be demagnetized and said base plate.