US Patent No. 9,233,429

WIRE-CUT ELECTRIC DISCHARGE MACHINE HAVING FUNCTION OF DETECTING UPPER SURFACE OF WORKPIECE


Patent No. 9,233,429
Issue Date January 12, 2016 
Title Wire-cut Electric Discharge Machine Having Function Of Detecting Upper Surface Of Workpiece
Inventorship Akiyoshi Kawahara, Yamanashi (JP)
Hiroyuki Furukawa, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,233,429

1. A wire-cut electric discharge machine having a function of detecting an upper surface of a workpiece, comprising:
a mechanism configured to relatively move a wire electrode that is stretched between upper and lower wire guides embedded
in upper and lower nozzles with respect to a workpiece that is placed on a workpiece placing table;

a contact detection unit configured to detect contact between the wire electrode and the workpiece;
a means for controlling relative movement of the wire electrode that is stretched between the upper and lower wire guides
with respect to the workpiece after positioning the upper and lower wire guides so that the wire electrode becomes orthogonal
to a horizontal surface, then stops the relative movement of the upper and lower wire guides with respect to the workpiece
at a first position where contact between the wire electrode and the workpiece is detected, subsequently, relatively moves
the upper and lower wire guides with respect to the workpiece, then stops the relative movement of the upper and lower wire
guides with respect to the workpiece at a second position that is away from an end surface of the workpiece by a predetermined
distance, subsequently, relatively moves the upper wire guide with respect to the workpiece in a state where the lower wire
guide is not relatively moved, and then stops the relative movement of the upper wire guide with respect to the workpiece
at a third position where the contact between the wire electrode and the workpiece is detected;

a storage unit configured to store positions of the upper and lower wire guides obtained when the relative movement is stopped
on the first position, the second position, and the third position;

a wire electrode inclination angle calculating unit configured to calculate an inclination angle of the wire electrode lying
at the third position from a relative distance in a horizontal direction of the upper wire guide obtained when the relative
position of the upper wire guide with respect to the workpiece is changed from the second position to the third position and
a distance in a vertical direction of the upper and lower wire guides; and

a workpiece upper surface position calculating unit configured to calculate a distance from the lower wire guide to the upper
surface of the workpiece based on the inclination angle of the wire electrode lying at the third position and a distance in
a horizontal direction between the lower wire guide and the end surface of the workpiece lying at the third position.