# US 2013/0240486 A1 · Wire electrical discharge machining device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0240486 A1 - Document ID: US20130240486A1 - Status: Published application - Kind: A1 - Application number: 13/880,053 - Filed: 2011-10-19 - Published: 2013-09-19 - Earliest claimed: 2010-10-19 - Assignees: Sodick Co., Ltd. - Inventors: Kuniharu Yamada; Masaki Kougo; Tomoyuki Yanagisawa - Web page: https://patentgrep.com/patent/US20130240486A1 ## CPC - B23H 7/104: {Wire tension control} - B23H 1/02: Electric circuits specially adapted therefor, e.g. power supply, control, preventing short circuits or other abnormal discharges - 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) ## Abstract Provided is a wire electrical discharge machining device which has a tension controller for maintaining the tension of a traveling wire electrode at a tension. The tension controller includes: an allowed tension calculation module for determining an allowed tension that is less than a wire breaking tension at which the wire electrode breaks; and a set tension generation module for generating the set tension in accordance with the allowed tension. When the set tension is greater than the allowed tension, the set tension generation module reduces the set tension. When the set tension is less than the allowed tension, the set tension generation module increases the set tension in such a way that the set tension does not exceed the allowed tension. ## Claims ### Claim 1 A wire electrical discharge machining device, having a tension controller for maintaining a tension of a travelling wire electrode at a set tension and machining a work by repeatedly supplying a current pulse to a machining gap formed between the wire electrode and the work, the tension controller comprising: an allowed tension calculation module for calculating an allowed tension that is less than a wire breaking tension at which the wire electrode breaks; and a set tension generation module for generating the set tension according to the allowed tension. ### Claim 2 (depends on 1) The wire electrical discharge machining device according to claim 1, when the set tension is less than the allowed tension, the set tension generation module increases the set tension. ### Claim 3 (depends on 2) The wire electrical discharge machining device according to claim 2, when the set tension is less than the allowed tension, the set tension generation module increases the set tension in such a way that the set tension does not exceed the allowed tension. ### Claim 4 (depends on 1) The wire electrical discharge machining device according to claim 1, when the set tension is greater than the allowed tension, the set tension generation module reduces the set tension. ### Claim 5 (depends on 4) The wire electrical discharge machining device according to claim 4, when the set tension is greater than the allowed tension, the set tension generation module reduces the set tension in such a way that the set tension does not go below a predetermined lower limit ### Claim 6 (depends on 1) The wire electrical discharge machining device according to claim 1, when the set tension is less than the allowed tension, the set tension generation module increases the set tension by a first predetermined increment, and when the set tension is greater than the allowed tension, the set tension generation module reduces the set tension by a second predetermined decrement which is greater than the first predetermined increment. ### Claim 7 (depends on 1) The wire electrical discharge machining device according to claim 1, further comprising a current detector for detecting a gap current flowing through the machining gap, wherein the allowed tension calculation module calculates the wire breaking tension based on the gap current. ### Claim 8 (depends on 1) The wire electrical discharge machining device according to claim 1, further comprising a discharge number detector for detecting a number of electrical discharges generated in the machining gap at a predetermined time interval, wherein the allowed tension calculation module calculates the wire breaking tension based on the number of electrical discharges. ### Claim 9 (depends on 1) The wire electrical discharge machining device according to claim 1, wherein the allowed tension calculation module calculates the wire breaking tension based on a cross-sectional area of a used wire electrode. ### Claim 10 (depends on 9) The wire electrical discharge machining device according to claim 9, wherein the allowed tension calculation module calculates the cross-sectional area of the used wire electrode by subtracting consumption by electrical discharge machining from a cross-sectional area of an unused wire electrode. ### Claim 11 (depends on 10) The wire electrical discharge machining device according to claim 10, wherein the allowed tension calculation module calculates the consumption based on a travelling speed of the wire electrode and the gap current. ### Claim 12 (depends on 1) The wire electrical discharge machining device according to claim 1, wherein the allowed tension calculation module calculates the allowed tension by subtracting a margin from the wire breaking tension. ### Claim 13 (depends on 12) The wire electrical discharge machining device according to claim 12, further comprising a wire breaking risk determination module for determining a wire breaking risk, and a margin generation module for generating the margin based on the wire breaking risk. ### Claim 14 (depends on 13) The wire electrical discharge machining device according to claim 13, wherein the wire breaking risk determination module classifies the wire breaking risk into at least a “low” level and a “high” level, and the margin generation module generates a first margin when the wire breaking risk is at the “low” level and the margin generation module generates a second margin which is greater than the first margin when the wire breaking risk is at the “high” level. ### Claim 15 (depends on 13) The wire electrical discharge machining device according to claim 13, further comprising an injection nozzle for supplying a machining fluid to the machining gap and a fluid pressure detector for detecting a pressure of the machining fluid, wherein the wire breaking risk determination module determines the wire breaking risk according to the pressure. ### Claim 16 (depends on 15) The wire electrical discharge machining device according to claim 15, wherein the wire breaking risk determination module classifies the wire breaking risk into a “low” level when the pressure is greater than or equal to a first threshold value, and the wire breaking risk determination module classifies the wire breaking risk into a “high” level when the pressure is less than the first threshold value. ### Claim 17 (depends on 16) The wire electrical discharge machining device according to claim 16, wherein the margin generation module generates a first margin when the wire breaking risk is at the “low” level and the margin generation module generates a second margin which is greater than the first margin when the wire breaking risk is at the “high” level. ### Claim 18 (depends on 16) The wire electrical discharge machining device according to claim 16, wherein the wire breaking risk determination module classifies the wire breaking risk into a “very high” level when the pressure is less than a second threshold value which is less than the first threshold value. ### Claim 19 (depends on 18) The wire electrical discharge machining device according to claim 18, wherein the margin generation module generates a first margin when the wire breaking risk is at the “low” level, the margin generation module generates a second margin which is greater than the first margin when the wire breaking risk is at the “high” level, and the margin generation module generates a third margin which is greater than the second margin when the wire breaking risk is at the “very high” level.