Walker Magnetics Group, Inc.

Other

Dominic F Pignataro

Donald C McDonald

Roger B Ela

In the switchable magnet system disclosed herein, a central pole piece is backed by at least two permanent magnets having substantially different energies (H,) so that one of the magnets is relatively switchable or reversible and the other is not. A magnetically permeable frame provides a peripheral pole face at least on either side of the central pole face and a backing plate bridging the central pole piece over the permanent magnets. A coil surrounds the first and second permanent magnets insde of the peripheral pole face. According, energization of the coil in one direction can reverse the polarization of the first magnet, thereby effectively short circuiting flux produced by the second magnet and terminating holding, while energization of the coil in the opposite direction can polarize the first magnet in parallel with the second magnet, thereby to effect holding.

Electrically switchable magnet system

In the switchable magnet system disclosed herein, a central pole piece is backed by at least two permanent magnets having substantially different energies (H.sub.c) so that one of the magnets is relatively switchable or reversible and the other is not. A magnetically permeable frame provides a peripheral pole face at least on either side of the central pole face and a backing plate bridging the central pole piece over the permanent magnets. A coil surrounds the first and second permanent magnets inside of the peripheral pole face. According, energization of the coil in one direction can reverse the polarization of the first magnet, thereby effectively short circuiting flux produced by the second magnet and terminating holding, while energization of the coil in the opposite direction can polarize the first magnet in parallel with the second magnet, thereby to effect holding.

The magnetic chuck disclosed herein is of the permanent magnet type in which both a top plate and a shiftable pack comprise alternating major pole pieces and magnets, the pack being shiftable so that its magnets either aid or oppose the magnets in the top plate, thereby to change between holding and release states. Improved holding for thin workpieces is obtained by providing a central region in the top plate in which the major pole pieces are thinner than the magnets and in which a plurality of floating minor pole pieces are positioned in the gaps between the major poles. While less flux is available through the thinner major pole pieces, the floating pole pieces provide an increased number of transitions for flux between top plate and workpiece so the total holding force for thin workpieces is improved. Increased flux available at the outer regions to either side of the central region provides good holding force for larger workpieces so that the chuck is well-adapted for a wide range of applications such as may be found in machine shop tool rooms.

Magnetic chuck

An electromagnet control apparatus having a remote control switch assembly switchable between a number of positions representing full, variable, residual and zero levels of magnetization. Means are provided for causing the electromagnet to be fully energized for several seconds before being dropped to the residual level of magnetization whenever the switch assembly is switched to a residual setting.

Chuck control for a workpiece holding electromagnet

In the electromagnet control apparatus described herein, demagnetization of the electromagnet and a workpiece held thereby, following a period of holding, is effected by stepwise adjustment of the phase setting of a power control means such as a triggerable, semi-conductor switching device, thereby controlling the average AC voltage applied to a full wave bridge through which the electromagnet is energized. Reversing switch means are interposed between the bridge and the electromagnet for reversing the direction of the energizing current at each successive step.

Demagnetizing apparatus for a workpiece holding electromagnet

The magnetic chuck disclosed herein is of the interlocking finger type and substantial components thereof are fabricated by making parallel oblique cuts in conventional bar stock thereby to generate a succession of parallelogram-shaped pieces. A series of the parallelogram pieces are assembled with alternate pieces being reversed so that they overlap only over a common triangular area with adjacent parallelogram pieces being separated by interleaved triangular spacers. The projecting fingers provided by such an assembly may be then mated with other similar or half-similar pole-piece units to form an interlock magnetic chuck top plate.

Growing community of inventors

Shrewsbury, MA, United States of America

Dominic F Pignataro