JP3642278B2 - Wire electric discharge machining method and apparatus - Google Patents

Description

【Technical field】
[0001]
The present invention relates to an improvement in a wire electric discharge machining method and apparatus capable of predicting and displaying a processed shape of a workpiece.
[Background]
[0002]
FIG. 8 shows a conventional wire electrical discharge machining apparatus, in which 1 is a workpiece, 2 is a wire electrode, 3 is a surface plate, 6 is an X table, 7 is a Y table, and 8 is an X-axis servo. Amplifier, 9 is Y-axis servo amplifier, 11 is machining fluid nozzle, 12 is machining fluid, 13 is a numerical control device, 14 is program analysis means, 15 is locus movement control means, 16 is program locus drawing means, and 17 is a display device. , 18 are drawing trajectories.
[0003]
Next, the operation will be described.
In FIG. 8, machining power is supplied between the wire electrode 2 and the workpiece 1 by a machining power source (not shown), and machining proceeds by generating electric discharge between the two. At this time, the X table 6 and the Y table 7 are driven based on a program given in advance to the numerical control device 13, so that a desired shape can be processed.
That is, a servo motor (not shown) is driven by the speed signal from the numerical control device 13 via the X-axis servo amplifier 8 and the Y-axis servo amplifier 9 to move the X table 6 and the Y table 7, and the constant on the X table 6 is determined. The workpiece 1 fixed to the board 3 is moved and the machining proceeds.
[0004]
FIG. 9 shows the positional relationship between the wire electrode 2 and the workpiece 1 during the first cut (first machining, 1st machining), and the center of the wire electrode 2 was obtained by the program analysis means 14. Follow the machining position.
The wire electrode center path is separated from the time when the given program is analyzed with the offset value 0 by the offset value commanded in the program.
In addition, the gap formed between the wire electrode and the workpiece by removing the workpiece due to the occurrence of electric discharge is called a discharge gap, and the amount varies depending on the machining conditions.
[0005]
Further, a second cutting (second processing, second processing) method capable of processing with the same program while changing the offset value and finishing with high accuracy is disclosed as a general processing technique.
FIG. 10 shows the positional relationship between the wire electrode and the workpiece in the 2nd machining. As machining conditions used for the 2nd machining, the discharge gap and the offset value are set to values smaller than the 1st machining, and the 2nd machining is performed. Secure the amount taken in.
The difference between the offset value of the n-th machining and the offset value of the (n-1) -th machining is referred to as the n-th offset amount, but if an appropriate value is not selected as the offset amount, no discharge is performed, Conversely, a situation occurs where a short circuit occurs and machining does not proceed.
[0006]
The distance between the surface of the wire electrode and the workpiece before processing is L, the discharge gap at that time is G, and the minimum gap between the workpiece and the wire electrode that can avoid a short circuit is Gmax.
FIG. 11 shows a case where the processing is normally performed.
In FIG. 11, the relationship among L, G, and Gmax is as follows.
In the following, the number n in parentheses indicates the n-th processing.
Gmax (2) <L <G (2)
[0007]
On the other hand, FIG. 12 shows a case where the distance L between the surface of the wire electrode and the workpiece before processing is too large to discharge.
The relationship between L and G in this case is as follows.
G (2) <L
[0008]
FIG. 13 shows a case where the distance L between the surface of the wire electrode and the workpiece before processing is too small to cause a short circuit and discharge is not performed.
In this case, the relationship between L and Gmax is as follows.
L <Gmax (2)
[0009]
Here, a method of obtaining the wire electrode center path by the program analysis means 14 and displaying it on the display device 17 before actual processing will be described.
FIG. 14 is a flowchart showing a program check drawing method provided in the numerical controller 13 of the conventional wire electric discharge machining apparatus, 21 is an analysis means for reading command contents from designated program contents, and 22 is read. Discriminating means for discriminating whether or not the command content is an end command, 23 is a program analyzing device for calculating the machining position from the program content, and 24 is a drawing for drawing the position analyzed by the program analyzing device 23 on the display device. Means.
[0010]
Next, the operation will be described.
First, the commands in the program designated by the analysis means 21 in FIG. If the determination unit 22 determines that the read command is an end command, the drawing process ends.
If the determining means 22 determines that the read command is not an end command, the program analysis means 23 calculates the machining position followed by the center of the wire electrode, and the drawing means 24 displays a fixed line on the display device. The trajectory is drawn with thickness.
[0011]
An example of drawing by this method is shown in FIGS.
FIG. 15 shows a wire electrode center path when processing is performed once, and FIG. 16 shows a wire electrode center path when processing is performed three times.
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0012]
The conventional wire electric discharge machining method and apparatus are configured as described above, and there is a problem that the finished surface cannot be predicted because only drawing is performed by the wire electrode center path.
In addition, when machining is performed a plurality of times while changing the offset value with the same program, there is a problem in that it cannot be determined whether or not sufficient discharge can be performed in each machining according to the set shift amount.
[0013]
The present invention has been made to solve the above-described problems, and it is possible to visually determine whether or not the finished shape after processing is as intended. It is to obtain a processing method and apparatus.
[Means for Solving the Problems]
[0014]
The wire electric discharge machining method according to the first invention is to add an expected discharge gap to the machining conditions, read the amount at the time of program check, and draw the expected discharge gap on the display device together with the wire electrode center path. .
A wire electric discharge machining apparatus according to a second aspect of the present invention adds an expected discharge gap to a machining condition and reads out the amount when the program is checked, and displays the expected discharge gap on the display device together with the wire electrode center path. And a drawing means.
A wire electric discharge machining apparatus according to a third invention is the wire electric discharge machining apparatus according to the second invention, wherein the expected electric discharge gap displayed together with the wire electrode center path is displayed on the display device as a different display color for each machining frequency. The drawing means is provided.
In the wire electric discharge machining method according to the fourth aspect of the invention, an expected discharge gap is added to the machining conditions, and the amount is read at the time of program check, and is obtained from the expected discharge gap g and the wire electrode diameter d (d + 2 × g) × The wire electrode center path is displayed on the display device as the thickness of the line for drawing the drawing scale.
The wire electric discharge machining apparatus according to the fifth aspect of the present invention is obtained from the calculation means for adding the expected discharge gap to the machining conditions and reading the amount during the program check, the expected discharge gap g and the wire electrode diameter d (d + 2 × g) × Drawing means for displaying the wire electrode center path on the display device as the thickness of the line for drawing the drawing scale.
The wire electric discharge machining apparatus according to a sixth aspect of the invention is the wire electric discharge machining apparatus according to the fifth aspect of the invention, wherein the line displaying the wire electrode center path is displayed on the display device as a different display color for each machining count. It is equipped with.
【The invention's effect】
[0015]
In the wire electric discharge machining method according to the first invention, since the expected electric discharge gap is displayed on the display device together with the wire electrode center path, it is determined whether or not the finished shape after machining is as intended. You can do it visually.
Since the wire electric discharge machining apparatus according to the second invention is provided with the drawing means for displaying the expected discharge gap on the display device together with the wire electrode center path, each of the judgments as to whether or not the finished shape after machining is as intended. It becomes possible to perform visually every processing.
A wire electric discharge machining apparatus according to a third aspect of the present invention is the wire electric discharge machining apparatus according to the second aspect of the present invention, in which the expected electric discharge gap displayed together with the wire electrode center path is displayed on the display device as a different display color for each machining number. This makes it easier to visually determine whether the finished shape after processing is as intended.
In the wire electric discharge machining method according to the fourth invention, the wire electrode central path is defined on the display device as (d + 2 × g) × thickness of a line for drawing drawn scale obtained from the expected discharge gap g and the wire electrode diameter d. Because of the display, the same effect as the first invention is obtained.
A wire electric discharge machining apparatus according to a fifth aspect of the present invention provides a wire electrode central path on a display device, where (d + 2 × g) × drawing scale is obtained from an expected discharge gap g and a wire electrode diameter d, Since the drawing means for displaying is provided, the same effects as those of the second invention can be obtained.
The wire electric discharge machining apparatus according to a sixth aspect of the invention is the wire electric discharge machining apparatus according to the fifth aspect of the invention, wherein the line displaying the wire electrode center path is displayed on the display device as a different display color for each machining count. Therefore, the same effect as the third invention can be obtained.
BEST MODE FOR CARRYING OUT THE INVENTION
[0016]
Embodiment 1 FIG.
FIG. 1 is a flowchart showing a drawing method in the wire electric discharge machining apparatus according to Embodiment 1 of the present invention.
In the figure, reference numerals 21 to 23 are the same as those in FIG. 14, which is the prior art, 21 is an analyzing means for reading command contents from the designated program contents, and 22 is a command for ending the command contents read from the designated program. Determining means 23 for determining whether or not, a program analyzing means 23 for calculating a machining position from a movement command in the program.
Further, 25 is a discriminating means for discriminating whether or not the command content read from the designated program is a machining condition command, 26 is a computing means for reading the expected discharge gap g added to the machining conditions designated by the program, and 27 is Calculating means for obtaining the thickness of the line used for drawing from the expected discharge gap g read out in 26 and the wire electrode diameter d in use; 28, the thickness of the line obtained by the computing means 27 in the machining position obtained by the program analyzing means 23; This is a drawing means for drawing.
[0017]
Here, a method for determining the expected discharge gap g to be added to the processing conditions will be described.
Under the same machining conditions, the discharge gap is determined by the machining speed, and in wire electric discharge machining, the machining speed is controlled so that the average machining voltage between the wire electrode being processed and the workpiece is constant. Although the processing speed varies due to the unevenness of the processing surface shape, the target processing speed is determined in advance for each processing condition.
Therefore, in each machining condition, abandoning is performed using the respective target machining speeds in the state shown in FIG. 9 in the first machining condition and in the state shown in FIG. Is measured to obtain the discharge gap G, and this value may be used as the expected discharge gap g for each processing condition.
[0018]
Next, the operation will be described.
In FIG. 1, instructions in the program are sequentially read one by one by the analysis means 21.
If the read command is an end command by the determination means 22, the drawing process ends.
When the read command is not an end command, it is determined by the determining means 25 whether or not it is a machining condition command, and when it is determined that it is a machining condition command, the calculation means 26 is calculated from the corresponding processing condition data. To read the expected discharge gap.
The calculating means 27 calculates the thickness of the line used for drawing from the expected discharge gap g read by the calculating means 26 and the wire electrode diameter d used, based on the following equation.
(Thickness of line used for drawing) = (d + 2 × g) × drawing scale
Next, returning to the analysis means 21, the next command is read.
If the command read by the analysis unit 21 is not determined by the determination unit 25 as a machining condition command, the program analysis unit 23 calculates the machining position according to the command content, and the drawing unit 28 The processing position is drawn on the display device using the line thickness obtained by the computing means 27.
[0020]
FIGS. 2 and 3 show examples of drawing by this method. FIG. 2 shows an example in which processing is performed once, and FIG. 3 shows an example in which processing is performed three times.
[0021]
Embodiment 2. FIG.
FIG. 4 is a flowchart showing a drawing method in the wire electric discharge machining apparatus according to the embodiment of the present invention. In the figure, 31 is added to the machining conditions from the machining conditions used in the machining program for n times machining. Calculating means for reading out the expected discharge gap g (n) and the expected minimum gap gmax (n) between the workpiece and the wire electrode capable of avoiding a short circuit; 32, calculating means for displaying the amount taken in the first machining; Is a computing means for displaying the amount taken in the second machining, and 34 is a computing means for displaying the amount taken in the n-th machining.
[0022]
Here, a method of determining the expected discharge gap g added to the machining conditions and the expected minimum gap gmax between the workpiece and the wire electrode capable of avoiding a short circuit will be described.
The expected discharge gap g added to the processing conditions is determined in the same manner as in the first embodiment.
Further, the expected minimum gap gmax between the workpiece and the wire electrode that can avoid a short circuit added to the machining conditions is determined when the discharge gap G is obtained by performing the abandonment machining using the target machining speed as in the first embodiment. Processing is performed while gradually reducing the offset value of the discharge gap G, the distance between the workpiece and the wire electrode when the short circuit occurs for the first time is obtained, and this value may be set as gmax.
[0023]
Next, the operation will be described.
First, the calculation means 31 reads the expected discharge gap g (n) and the expected minimum gap gmax (n) between the workpiece and the wire electrode that can avoid a short circuit from the machining conditions used in the machining program for the n-th machining.
In the calculation means 32, among the data obtained by the calculation means 31, the expected discharge gap g (1) at the first machining is used, and the expected amount m (1) at the first machining is obtained by the following equation.
m (1) = d + 2 × g (1)
[0024]
The color when displaying the estimated amount on the display device is displayed in a different color c (n) by changing the color of the band for each estimated amount of processing of n times so that it can be distinguished for each number of times of processing. Shall be performed.
Since the expected amount taken in 1st machining is equal to the expected discharge location in 1st machining, the band indicating the expected discharge location in 1st machining is m (1) × drawn in red assuming that c (1) is red. What is necessary is just to display by the width | variety of a reduced scale (X1 of FIGS. 5-7).
Here, as a reference for obtaining the position of the band indicating the estimated amount after the 2nd machining, for example, as shown in FIGS. 5 to 7, if the origin (o) of the width of the band depicting the estimated amount of the first machining is used. Good.
[0025]
Next, in the calculation means 33 in FIG. 4, among the data read by the calculation means 31, the expected discharge gap g (2) at the time of 2nd machining is used, and the expected amount m (2) at 2nd machining is It can be obtained by an expression.
m (2) = {g (2) + d + y (2) + g (1)}-m (1)
= {G (2) + d + y (2) + g (1)}-{d + 2 × g (1)}
= {G (2) + y (2) -g (1)}
Here, y (n) indicates the nth shift amount.
[0026]
The discharge location in 2nd machining is estimated from the expected amount m (2) in 2nd machining obtained above.
In the case of m (2) ≦ 0, it indicates that the expected amount of 2nd machining overlaps with the expected amount of 1st machining, and the 2nd machining does not have a sufficient amount of offset to the workpiece. This indicates that no discharge is performed.
In this case, the relationship between the wire electrode and the workpiece in the 2nd machining corresponds to the state shown in FIG.
When m (2)> 0, the expected minimum gap gmax (2) between the workpiece and the wire electrode capable of avoiding a short circuit during 2nd processing and m (2) are compared, and m (2)> In the case of gmax (2), it is indicated that the amount of contact of the wire electrode with respect to the workpiece is too large and a short circuit occurs.
In this case, the relationship between the wire electrode and the workpiece in the 2nd machining corresponds to the state shown in FIG.
On the other hand, in the case of 0 <m (2) ≦ gmax (2), the amount of shifting with respect to the workpiece is appropriate, and even if the wire electrode is excessively moved to the workpiece by gmax (2) −m (2), a short circuit is caused. It can be avoided.
In this case, the relationship between the wire electrode and the workpiece in the 2nd machining corresponds to the state shown in FIG.
[0027]
In order to distinguish these three states, band display is performed on the display device as follows.
When displaying the estimated amount of 2nd processing on the display device, gmax (2) from the starting point (o) to the starting point from the position of {g (1) + y (2) + d + g (2)} × drawing scale. ) X Band display at the drawing scale width.
The portion that does not overlap with X1 is X2, and the display color is c (2) (for example, blue).
The part overlapping X1 is X2 ', and the part X2' is originally removed by the 1st processing, so the display color wants to give priority to the color X1, but in order to distinguish it from X1, the combined color of X1 and X2 (for example, Reddish purple).
The width of X2 ′ is an allowance for the amount of 2nd processing shift, and the width is {gmax (2) −m (2)} × drawing scale. The region X2 ′ is included in the region X1.
[0028]
Similarly, the expected amount m (n) of the n-th machining is calculated by the following equation using the predicted discharge gap g (n) of the n-th machining among the data read out 31 in the calculation means 34. Desired.
m (n) = {g (1) + y (2) + y (3) +
... + y (n) + d + g (n)}-m (n-1)
[0029]
The band display on the display device is from the starting point (o) to {g (1) + y (2) + y (3) +... Y (n) + d + g (n)} × the drawing scale position toward the starting point (o). gmax (n) × width of drawing scale.
The portion that does not overlap with X1 to Xn-1 is Xn, and the display color is c (n).
A portion overlapping X1 to Xn-1 has a display color changed to c (n).
[0030]
Examples of band display on the display device as described above are shown in FIGS.
FIG. 5 corresponds to the relationship between the wire electrode and the workpiece in FIG. 12 in 2nd processing, and is a table in the case where discharge is not performed due to the shortage of the wire electrode with respect to the workpiece in 2nd processing. It is an example.
FIG. 6 corresponds to the relationship between the wire electrode and workpiece in FIG. 11 in 2nd processing, and is a display example when the amount of wire electrode approaching the workpiece in 2nd processing is appropriate.
X2 in FIG. 6 represents an expected discharge location.
Further, FIG. 7 corresponds to the relationship between the wire electrode and workpiece in FIG. 13 in 2nd processing, and the short-circuit occurs because the amount of wire electrode approaching the workpiece in 2nd processing is too large. It is a display example.
In FIG. 7, it can be identified that there is an interval between X2 and X1, and the amount of shift is too large.
[Industrial applicability]
[0031]
As described above, the wire electrical discharge machining apparatus according to the present invention is suitable for use in wire electrical discharge machining work for determining whether the finished shape after machining is as intended and determining the amount of shift.

Claims (6)

In the wire electric discharge machining method for machining while applying a voltage to the machining gap between the wire electrode and the workpiece,
The expected discharge gap is added to the machining conditions and the amount is read out during the program check.
A wire electric discharge machining method, wherein the predicted electric discharge gap is drawn on a display device together with a wire electrode central path. In a wire electrical discharge machining apparatus that performs machining while applying a voltage to the machining gap between the wire electrode and the workpiece,
An arithmetic means for adding the expected discharge gap to the machining conditions and reading the amount at the time of program check;
A wire electric discharge machining apparatus comprising: a drawing means for displaying the predicted electric discharge gap on a display device together with a wire electrode central path. The wire electric discharge machining apparatus according to claim 2, further comprising a drawing unit that displays the expected electric discharge gap displayed together with the wire electrode center path on a display device as a different display color for each machining frequency. In the wire electric discharge machining method for machining while applying a voltage to the machining gap between the wire electrode and the workpiece,
The expected discharge gap is added to the machining conditions and the amount is read out during the program check.
A wire electric discharge machining method, wherein a wire electrode center path is displayed on a display device as (d + 2 × g) × thickness of a line for drawing drawn from the expected electric discharge gap g and the wire electrode diameter d. . In a wire electrical discharge machining apparatus that performs machining while applying a voltage to the machining gap between the wire electrode and the workpiece,
An arithmetic means for adding the expected discharge gap to the machining conditions and reading the amount at the time of program check;
And (d + 2 × g) × drawing scale obtained from the expected electrode gap g and the wire electrode diameter d, and a drawing means for displaying the wire electrode center path on a display device as a thickness of a drawing line. Wire electrical discharge machining equipment. 6. The wire electric discharge machining apparatus according to claim 5, further comprising drawing means for displaying a line for displaying the wire electrode center path on a display device as a different display color for each machining count.

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