Wire electrode discharge machine and method

• US 5,744,775 A
• Filed: 03/06/1996
• Issued: 04/28/1998
• Est. Priority Date: 03/06/1995
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nakayama, Yoshiro, Yasuda, Osamu
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US08/611,810
• Time in Patent Office: 783 Days
• Field of Search: 219/69.12
• US Class Current: 219/69.12
• CPC Class Codes: B23H 2500/20 Methods or devices for detecting wire or workpiece position
• CPC Class Codes: B23H 7/04 Apparatus for supplying current to working gap; Electric circuits specially adapted therefor
• CPC Class Codes: B23H 7/06 Control of the travel curve of the relative movement between electrode and workpiece
• CPC Class Codes: B23H 7/065 Electric circuits specially adapted therefor

Abstract

To easily correct the slant of a wire electrode to a workpiece by using the workpiece which is machined into a product and the wire electrode without a special jig. Discharge is generated by approaching a wire electrode 1 to a workpiece fixed on a table. The slant of the wire electrode and correcting amount are calculated by measuring the discharge for a prescribed period of time or a prescribed number of times, while taking the discharge position as a width or a distribution. Then, correction is performed. Therefore, it is possible to correct the slant of the wire electrode relative to the workpiece directly by using the wire electrode. Accordingly, it is possible to drastically reduce the time necessary for getting accuracy in fixing the workpiece on the table and the time necessary for arrangements such as verticality check of the wire electrode by discharge.

Claims

1. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said workpiece by moving one of said wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting the discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

wire electrode slant determining means for determining a slant direction of said wire electrode relative to said workpiece based on a shift of said discharge position detected by said discharge position detecting means while approaching said wire electrode relative to said workpiece; and

a wire electrode slant correcting means for correcting the slant of said wire electrode relative to said workpiece based on the slant direction of said wire electrode determined by said wire electrode slant determining means.

2. A wire electrode discharge machine as claimed in claim 1, further comprising:

an irregular discharge detecting means for detecting a concentrated discharge as an irregular discharge if the concentrated discharge is generated in detecting the discharge position by said discharge position detecting means; and

a correcting amount excluding means for excluding the irregular discharge from a correcting amount calculated by a correction amount computing means when the irregular discharge is detected by said irregular discharge detecting means.

5. A wire electrode discharge machine as claimed in any one of claims 1, 3 and 4, further comprising:

discharge position storage means for moving said pair of wire electrode guides in the U-axis and V-axis directions to slant said wire electrode so as to generate the discharge between said wire electrode and said workpiece, and storing the discharge position detected by said discharge position detecting means; and

workpiece thickness computing means for calculating a thickness of said workpiece based on the discharge position stored in said discharge position storage means.

6. A wire electrode discharge machine as claimed in any one of claims 1, 3 and 4, further comprising:

a discharge position detecting power source, for contour machining, for supplying less power for a lesser amount of machining per unit time compared with said machining power source.

7. A wire electrode discharge machine as claimed in any one of claims 1, 3 and 4, further comprising:

working fluid supplying means for discharge position detection for supplying a working fluid for discharge position detection between said wire electrode and said workpiece in detecting the discharge position by said discharge position detecting means.

3. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said workpiece by moving one of said wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting the discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

means for measuring said discharge position, for a prescribed time period, detected by said discharge position detecting means while moving said wire electrode toward said workpiece;

discharge width computing means for calculating a distance between an upper end and a lower end of said discharge position as a discharge width in a thickness direction of said workpiece; and

correcting amount computing means for calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on said discharge width calculated by said discharge width computing means, a thickness of said workpiece and said discharge position detected by said discharge position detecting means.

8. A wire electrode discharge machine as claimed in any one of claims 3 and 4, further comprising:

an irregular discharge detecting means for detecting a concentrated discharge as an irregular discharge if the concentrated discharge is generated in detecting the discharge position by said discharge position detecting means; and

a correcting amount excluding means for excluding the irregular discharge from the correcting amount calculated by said correction amount computing means when the irregular discharge is detected by said irregular discharge detecting means.

4. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said workpiece by moving one of said wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting the discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

means for measuring said discharge position, for a prescribed time period, detected by said discharge position detecting means while moving said wire electrode toward said workpiece;

a counting means for equally dividing a thickness of said workpiece into a number specified in a predetermined program and counting a number of times of discharge at each of the divided parts of said workpiece; and

a correcting amount computing means for calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on the number of times of discharge at each of the divided parts of said workpiece counted by said counting means, the thickness of said workpiece and said discharge position detected by said discharge position detecting means.

9. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for holding said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

determining a slant direction of said wire electrode relative to said workpiece based on a shift of said discharge position while moving said wire electrode toward said workpiece; and

correcting the slant of said wire electrode relative to said workpiece based on the slant direction of said wire electrode.

10. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for holding said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

measuring said discharge position for a prescribed time period while moving said wire electrode toward said workpiece;

calculating a distance between an upper end and a lower end of said discharge position as a discharge width in a thickness direction of said workpiece; and

calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on said discharge width, a thickness of said workpiece and said discharge position.

12. A wire electrode discharge method as claimed in any one of claims 9, 10 and 11, further comprising the steps of:

moving said pair of wire electrode guides in the U-axis and V-axis directions to slant said wire electrode so as to generate the discharge between said wire electrode and said workpiece, and storing the discharge position; and

calculating a thickness of said workpiece based on the discharge position.

13. A wire electrode discharge method as claimed in any one of claims 9, 10 and 11, further comprising the steps of:

detecting a concentrated discharge as an irregular discharge if the concentrated discharge is generated while detecting the discharge position; and

excluding the irregular discharge from the correcting amount when the irregular discharge is detected.

11. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for holding said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

measuring said discharge position for a prescribed time period while moving said wire electrode toward said workpiece;

equally dividing a thickness of said workpiece into a number specified in a predetermined program and counting a number of times of discharge at each of the divided parts of said workpiece; and

calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on the number of times of discharge at each of the divided parts of said workpiece, the thickness of said workpiece and said discharge position.

14. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece to be machined;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for holding said workpiece to be machined;

controlling a slant of said wire electrode relative to said workpiece to be machined by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece to be machined;

detecting a discharge position between said wire electrode and said workpiece to be machined based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

calculating the slant of said wire electrode to each of a plurality of workpieces based on the discharge position;

calculating correcting amounts for correcting the slants of said wire electrode relative to each of said plurality of said workpieces based on the slants of said wire electrode to each of said plurality of workpieces;

storing the correcting amounts; and

continuing machining said workpiece to be machined by recalling one of the correcting amounts corresponding to said workpiece to be machined while executing a prescribed program.

15. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said workpiece by moving one of said pair of wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

discharge width computing means for calculating a discharge width based on an amount the discharge position shifts in the X-axis and Y-axis directions detected by said discharge position detecting means at fixed time intervals;

a discharge width storage means for storing said discharge width calculated by said discharge width computing means;

an amount of variation computing means for calculating an amount of variation of the discharge width calculated by said discharge width computing means; and

a wire electrode slant computing means for calculating the slant of said wire electrode based on the shifting amount of the discharge position in the X-axis and Y-axis directions detected by said discharge position detecting means until the amount of variation becomes zero after a first discharge is generated.

16. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for holding said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

calculating a discharge width based on an amount the discharge position shifts in the X-axis and Y-axis directions at fixed time intervals;

storing said discharge width;

calculating an amount of variation of the discharge width; and

calculating the slant of said wire electrode based on the shifting amount of the discharge position in the X-axis and Y-axis directions until the amount of variation becomes zero after a first discharge is generated.

17. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said workpiece by moving one of said pair of wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

discharge width computing means for moving said wire electrode guide in the U-axis and V-axis directions while carrying out a machining for contour of said workpiece by moving said table in the X-axis and Y-axis directions, and calculating with amount of variation of the discharge width based on the amount the discharge position shifts in the U-axis and V-axis directions detected by said discharge position detecting means at fixed time intervals; and

a wire electrode slant computing means for calculating the slant of said wire electrode where the amount of variation of the discharge width calculated by said discharge width computing means is minimum.

18. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for fixing said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

moving said wire electrode guide in the U-axis and V-axis directions while carrying out a machining for contour of said workpiece by moving said table in the X-axis and Y-axis directions, and calculating an amount of variation of a discharge width based on an amount the discharge position shifts in the U-axis and V-axis directions at fixed time intervals; and

calculating the slant of said wire electrode where the amount of variation of the discharge width is minimum.

19. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

taper control means for controlling a slant of said wire electrode relative to said pair of workpiece by moving one of said wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode; and

correcting amount computing means for calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on a shift of the discharge position, while performing approach machining, which is a shape machining for said workpiece, until said wire electrode reaches a product contour.

20. A wire electrode discharge method, comprising the steps of:

applying voltage, using a machining power source, to generate a discharge through working fluid supplied between a wire electrode and a workpiece;

controlling a movement, in an X-axis direction and a Y-axis direction, of a table for fixing said workpiece;

controlling a slant of said wire electrode relative to said workpiece by moving, in a U-axis direction and a V-axis direction, one of a pair of wire electrode guides respectively located at a top and a bottom of said workpiece;

detecting a discharge position between said wire electrode and said workpiece based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode; and

calculating a correcting amount for correcting the slant of said wire electrode relative to said workpiece based on a shift of the discharge position, while performing approach machining, which is a shape machining for said workpiece, until said wire electrode reaches a product contour.

21. A wire electrode discharge machine, comprising:

working fluid supplying means for supplying working fluid between a wire electrode and a workpiece to be machined;

a machining power source for applying a voltage to generate a discharge between said wire electrode and said workpiece to be machined through said working fluid supplied from said working fluid supplying means;

a table on which said workpiece to be machined is fixed;

table control means for controlling a movement of said table in X-axis and Y-axis directions;

a pair of wire electrode guides respectively located at a top and a bottom of said workpiece to be machined;

taper control means for controlling a slant of said wire electrode relative to said workpiece to be machined by moving one of said pair of wire electrode guides in U-axis and V-axis directions;

discharge position detecting means for detecting a discharge position between said wire electrode and said workpiece to be machined based on a current supplied through an upper power supplying line and a lower power supplying line from said machining power source to said wire electrode;

wire electrode slant computing means for calculating the slant of said wire electrode to each of a plurality of workpieces based on the discharge position detected by said discharge position detecting means;

correcting amount computing means for calculating correcting amounts for correcting the slants of said wire electrode relative to each of said plurality of workpieces based on the slant of said wire electrode to each of said plurality of said workpieces calculated by said wire electrode slant computing means;

correcting amount storage means for storing the correcting amounts calculated by said correcting amount computing means; and

machining continuing means for continuing machining of said workpiece to be machined by recalling one of the correcting amounts stored in said correcting amount storage means corresponding to said workpiece to be machined while executing a prescribed program.