Electric heating – Metal heating – Cutting or disintegrating
Reexamination Certificate
1999-03-16
2001-02-06
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
Cutting or disintegrating
Reexamination Certificate
active
06184485
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of measuring flexure value of a wire electrode, and more particularly, to a method of measuring flexure value of a wire electrode to solve the problem that a reduced machining accuracy is caused by a wire flexure during a wire-cut electric discharge machine cutting in a corner part or in a circular arc.
DESCRIPTION OF THE PRIOR ART
In a operation of wire-cut electric discharge machining, a wire flexure in a corner part or a circular arc would reduce a machining accuracy. As shown in
FIG. 1
, symbol
1
denotes a wire electrode (diameter &phgr;), numeral
2
denotes a workpiece, numeral
3
denotes a groove, phantom line
4
denotes a curve path caused by the wire flexure and formed in the corner part which is cut at a junction with two straight lines intersecting with each other during the wire-cut electric discharge machine operation, and gd which is a distance between the wire electrode and the workpiece is the discharge gap. The normal way for improving the wire flexure is to use a three-dimensional measuring machine, a tracer, or a projector to measure a cutting error value and to store the cutting error value into a controller as a machining parameter. But not all users have good measuring instruments, and then, would have problems in measuring products with complicated shape. Besides expensive instruments problem or the cutting error value problem, it is a complicated way to store measuring values into the controller as machining parameters for a next machining after the error value has been measured.
SUMMARY OF THIS INVENTION
It is therefore a primary objective of the present invention to provide a method of quickly measuring the error value after the wire-cut electric discharge machining to establish machining parameters data of the wire-cut electric discharge machine for automatically compensating the flexure of the wire-cut electric discharge machine through the controller in the next machining.
Another object of the present invention is to provide a method of measuring the wire flexure of the machined workpiece through functions of the controller to reduce cost of investment for measuring the flexure of the wire-cut electric discharge machine.
In the present invention, the measurement of the flexure of the wire-cut electric discharge machine comprises the following steps of
(a) making the wire electrode
1
which is in the machining path come into contact with a dection edge of the workpiece
2
in a straight machining groove, after the course of machining (without wasted materials), to get the electric discharge gap gd which is the distance between a margin of wire electrode without contacting with the workpiece
2
along the straight machining path and a point where the wire electrode contacts with the workpiece;
(b) using the detection voltage of the machine to detect the machined groove, and an original programmed path minus the discharge gap gd as a new programmed path to trigger the detection voltage for dry-run and re-machining the workpiece;
(c) measuring and recording the position in the corner part where the wire electrode and the workpiece are short-circuited for an angle in the corner part less than 180°;
(d) increasing a compensation value for the angle in the corner part less than 180°, and decreasing a compensation value for the angle in the corner part greater than 180°, to advance the machine in the machined groove for detecting and recording that the short-circuited would happen in the corner part or not, in accordance with the re-machining process (dry-run);
(e) finding a present compensation value which is the compensation value of the flexure value in that corner part, for the angle in the corner part less than 180°, while the contact between the wire electrode and the workpiece is just released, and finding a last compensation value which is previous to a present compensation value and used as the compensation value for the corner part to find out the flexure value of that corner part, for the angle in the corner part greater than 180°, while the wire electrode and the workpiece are short-circuited; and
(f) storing the compensation value of the flexure value and the flexure value in different corner part in a memory built in an numerical control device for adjusting the discharge parameters at machining.
The wire flexure value in the step (e) is obtained from the compensation value of the flexure value divided by the sine function of one half of an angle in the corner part. For the angle in the corner part less than 180°, the compensation direction is in the direction of deviating from the short-circuited curve path. But for the angle in the corner part greater than 180°, the compensation direction is in the direction of approaching the short-circuited curve path.
The compensation value of this method chosen by users for the re-machining can be increased or decreased.
In the present invention, the measurement for the flexure of the wire-cut electric discharge machine comprises the following steps of
(a) making the wire electrode
1
which is in the machining path come into contact with the detection edge of the workpiece
2
in a straight machining groove, after the course of machining (without wasted materials), to get the electric discharge gap gd which is the distance between the margin of wire electrode without contacting with the workpiece
2
along the straight machining path and the point where the wire electrode contacts with the workpiece;
(b) using the detection voltage of the machine to detect the machined groove, and using the original programmed path minus the discharge gap gd as the new programmed path to trigger the detection voltage, for dry-run and re-machining the workpiece;
(c) measuring the line flexure value to find out the compensation value for the angle in different corners, for an angle in a corner part less than 180°, while the wire electrode advances in a groove along the machining path to the center line position of the angle, and then, the wire electrode would contact with the short-circuited curve path, and thereafter, the wire electrode is retracted relative to the short-circuited path along the center line of the angle, and when the short-circuited contact between the wire electrode and the workpiece has been just released by the foregoing retraction, the displacement is the wire flexure in that corner part, taking the wire flexure value times the sine function of one half of the angle in the corner part as the compensation value of the flexure in the corner part, and, for an angle in a corner part greater than 180°, while the wire electrode advances in the groove along the machining path to the center line position of the angle, and then, the wire electrode would keep a distance from the short-circuited curve path, and thereafter, the wire electrode is advanced relative to the short-circuited path along the center line of the angle, and when the wire electrode has come into contact with the short-circuited curve path, and the short-circuited contact between the wire electrode and the short-circuited curve path has been just released by the foregoing advance, the displacement is the wire flexure in that corner part, and taking the wire flexure value times the sine function of one half of the angle in the corner part as the compensation value of the flexure in the corner part; and
(d) storing the flexure value and the compensation value of the flexure value in different angles in a memory built in a numerical control device for adjusting the discharge parameters in the course of machining in the next time.
The method for measuring the flexure value and the compensation value in the circular arc during the course of working comprises the following steps of:
(a) making the wire electrode
1
which is in the machining path come into contact with the detection edge of the workpiece
2
, after the course of machining (without wasted materials), to get the electric discharge gap gd which is the distance between the margin of wire electrode without contac
Day Yea-June
Li Hsi-Pin
Liang Jui-Fang
Tsai Cheng-Fu
Yan Mu-Tian
Evans Geoffrey S.
Industrial Technology Research Institute
Smith , Gambrell & Russell, LLP
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