US Patent No. 9,729,039

LINEAR DRIVE UNIT WITH A MAGNETIC GAP CHANGING MECHANISM


Patent No. 9,729,039
Issue Date August 08, 2017
Title Linear Drive Unit With A Magnetic Gap Changing Mechanism
Inventorship Yonpyo Hon, Yamanashi (JP)
Kenzo Ebihara, Yamashi (JP)
Assignee Fanuc Corporation, Yamanashi (JP)

Claim of US Patent No. 9,729,039

1. A machine tool comprising a linear drive unit having a linear motor provided with a magnet and a coil having a coil core,
wherein a movable part is configured to linearly move relative to a fixed part via a bearing,
wherein the linear drive unit comprises a magnetic gap changing mechanism which is configured to change a magnitude of a magnetic
gap between the coil and the magnet, by displacing the coil so that the coil and the magnet approach or are separated from
each other,

wherein the coil is positioned within a coil bearing, and the coil bearing guides a movement direction of the coil in a direction
of the magnetic gap,

and wherein the machine tool has a plurality of processing modes in which the magnitudes of the magnetic gaps are different
from each other, and the processing modes includes a crude processing mode and a finish processing mode, in which the magnetic
gap in the finish processing mode is larger than the magnetic gap in the crude processing mode.