# US 8,822,871 B2 · Wire electric discharge machine having positioning accuracy compensation function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,822,871 B2 - Document ID: US8822871B2 - Status: Granted - Kind: B2 - Application number: 13/494,074 - Filed: 2012-06-12 - Published: 2013-02-21 - Granted: 2014-09-02 - Earliest claimed: 2011-08-17 - Assignees: Fanuc Corporation - Applicants: Hisanori Kouda - Inventors: Hisanori Kouda - Web page: https://patentgrep.com/patent/US8822871B2 ## CPC - B23H 7/065: {Electric circuits specially adapted therefor} - B23H 7/18: for maintaining or controlling the desired spacing between electrode and workpiece - B23H 7/20: for program control, e.g. adaptive - G05B 19/404: characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia (G05B19/19, G05B19/41 take precedence) - B23H 2500/20: Methods or devices for detecting wire or workpiece position - G05B 2219/41036: Position error in memory, lookup table for correction actual position - G05B 2219/45221: Edm, electrical discharge machining, electroerosion, ecm, chemical - B23H: WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL (processes for the electrolytic or electrophoretic production of coatings, electroforming, or apparatus therefor C25D; processes for the electrolytic removal of material from objects C25F; manufacturing printed circuits using precipitation techniques to apply the conductive material to form the desired conductive pattern H05K3/18) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract Two contact detection jigs are spaced apart and attached on a table on which a workpiece to be machined by a wire electric discharge machine is placed, and first, under a state serving as a reference, a distance between these two contact detection jigs (a reference distance) is measured by bringing the wire electrode into contact with these contact detection jigs. Subsequently, in a state of actual use, the wire electrode is brought into contact with these contact detection jigs in the same manner, so that a distance between these two contact detection jigs (an actual distance) is measured. Then, based on the difference between the reference distance and the actual distance, the amount of compensation is obtained to compensate an instruction for moving the wire electrode with respect to the table. ## Claims ### Claim 1 A wire electric discharge machine having a machining tank for storing a machining liquid, wherein an object to be machined is placed on a table provided in the machining tank, and the object is machined by relatively moving a wire electrode with respect to the table on the basis of an instruction output from a controller, the wire electric discharge machine comprising: a combination of contact detection jigs including a first contact detection jig having a first contact detection unit and a second contact detection jig having a second contact detection unit, wherein the first and second contact detection jigs are arranged at a predetermined distance from each other on a same axial line on the table such that the first and second contact detection units face each other; a contact detection unit for detecting contact between the wire electrode and the first and second contact detection jigs; a coordinate value memory unit for respectively storing coordinate values of axes moved when the wire electrode comes into contact with the first and second contact detection jigs; a reference distance memory unit for causing the wire electrode to come into contact with the first and second contact detection jigs under a first state in which a desired positioning accuracy can be obtained, and obtaining and storing, as a reference distance, a distance between the first contact detection jig and the second contact detection jig from the coordinate values when the wire electrode comes into contact with the first and second contact detection jigs, which are stored in the coordinate value memory unit; an actual distance memory unit for causing the wire electrode to come into contact with the first and second contact detection jigs under a second state which is different from the first state, and storing, as an actual distance, a distance between the first contact detection jig and the second contact detection jig from the coordinate values when the wire electrode comes into contact with the first and second contact detection jigs, which are stored in the coordinate value memory unit; and a compensation unit for calculating a difference between the reference distance stored in the reference distance memory unit and the actual distance stored in the actual distance memory unit, and compensating the instruction according to the distance from the contact position coordinate so as to cancel the difference during actual machining. ### Claim 2 (depends on 1) The wire electric discharge machine according to claim 1, wherein in the first state, the wire electric discharge machine is installed on a first floor with a first rigidity at which a desired positioning accuracy is obtainable, and in the second state, the wire electric discharge machine is installed on a second floor with a second rigidity different from the first rigidity. ### Claim 3 (depends on 1) The wire electric discharge machine according to claim 1, wherein the combination of the contact detection jigs is a plurality of contact detection jigs arranged in parallel. ### Claim 4 (depends on 1) The wire electric discharge machine according to claim 1, wherein the contact detection jig is made by making a through-hole in a plate-like member, and a coordinate of a center of the hole is obtained by bringing the wire electrode into contact with at least three locations on an inner surface of the through-hole, and the coordinate value is adopted as a coordinate value of an axis moved when the contact detection jig and the wire electrode come into contact with each other. ### Claim 5 (depends on 1) The wire electric discharge machine according to claim 1, wherein the pair of contact detection jigs is constituted as a single contact detection jig having at least two contact units with the wire electrode. ### Claim 6 (depends on 1) The wire electric discharge machine according to claim 1, wherein in the first state, the object is not placed on the table, and the machining liquid is not accumulated in the machining tank, and in the second state, the object is placed on the table, and the machining liquid is accumulated to a predetermined machining liquid height in the machining tank. ### Claim 7 (depends on 6) The wire electric discharge machine according to claim 6, wherein the second state is achieved by accumulating the machining liquid equivalent to a weight of the object placed on the table, in addition to the machining liquid height during the actual machining. ### Claim 8 A wire electric discharge machine having a machining tank for storing a machining liquid, wherein an object to be machined is placed on a table provided in the machining tank, and the object is machined by relatively moving a wire electrode with respect to the table on the basis of an instruction output from a controller, the wire electric discharge machine comprising: a combination of contact detection jigs including a first contact detection jig having a first contact detection unit and a second contact detection jig having a second contact detection unit, wherein the first and second contact detection jigs are arranged at a predetermined distance from each other on axial lines different from each other on the table such that the first and second contact detection units face each other; a contact detection unit for detecting contact between the wire electrode and the first and second contact detection jigs; a coordinate value memory unit for respectively storing coordinate values of axes moved when the wire electrode comes into contact with the first and second contact detection jigs; a reference distance memory unit for causing the wire electrode to come into contact with the first and second contact detection jigs under a first state in which a desired positioning accuracy can be obtained, and obtaining and storing, as a reference distance, a distance in each moving axial direction between the first contact detection jig and the second contact detection jig from the coordinate values when the wire electrode comes into contact with the first and second contact detection jigs, which are stored in the coordinate value memory unit; an actual distance memory unit for causing the wire electrode to come into contact with the first and second contact detection jigs under a second state which is different from the first state, and storing, as an actual distance, a distance in each moving axial direction between the first contact detection jig and the second contact detection jig from the coordinate values when the wire electrode comes into contact with the first and second contact detection jigs, which are stored in the coordinate value memory unit; and a compensation unit for calculating a difference between the reference distance stored in the reference distance memory unit and the actual distance stored in the actual distance memory unit, and compensating the instruction according to the distance from the contact position coordinate so as to cancel the difference during actual machining.