Magnetic block of the permanent magnets type comprising an on-off control mechanism.

摘要

A magnetic chuck or holder for workpieces adapted to be mounted on a worktable of a machine tool comprises a stack of alternating permanent magnets and magnetically conducting plates having a central passage through the stack in which a second stack of magnets and magnetically conductive plates is received for longitudinal movement, e.g. by a crank or an eccentric drive cooperating with one end of the second step. The two stacks are so arranged that they magnetically cancel the magnetic field lines on the upper, lateral and bottom surfaces of the chuck in one position of the second stack but create such field lines in a second position that all surfaces of the upper, lower and lateral surfaces are magnetically effective. This allows switching of the chuck to an effective state so that a workpiece is affixed magnetically to the upper surface of either or both lateral surfaces, and at the same time the chuck is magnetically fixed on the worktable of the machine tool.