JPH0790424B2 - Method of releasing short circuit at the machining start hole of wire electric discharge machine - Google Patents

Description

The present invention relates to a method for releasing a short circuit at a machining start hole of a wire electric discharge machine.

[Prior Art] FIG. 14 is a block diagram schematically showing a conventional wire electric discharge machine, and FIG. 15 is a plan view showing a workpiece set in the wire electric discharge machine. In FIG. Is a wire electrode,
(2) is a supply bobbin for the wire electrode (1), (3a), (3
b), (3c) and (3d) are idlers for changing the direction of the wire electrode (1), (4) is a brake roller connected to a brake (not shown) for applying tension to the wire electrode (1), (5) is an upper guide for guiding the wire electrode (1),
(6) is a lower guide, (7) is a workpiece, (8) is a processing start hole formed in the workpiece (7), (9) is a collecting roller for winding the wire electrode (1), ( 10) and (11) are upper nozzles and lower nozzles that supply the machining liquid to the machining gap, (12) is a power supply device, (12a) is its control circuit, (12b) is a switching element, and (13), ( 14) is an upper power supply and a lower power supply that supply energy from the power supply device (12) to the wire electrode (1), (15) is a control device, (16) and (17) are X, Y tables, ( 18) is another machining start hole formed in the workpiece (7), (19) is a wire electrode automatic feeder for stretching and cutting the wire electrode (1), and (20) is, for example, JP-A- As disclosed in Japanese Patent No. 59-152021, short circuit between the wire electrode (1) and the workpiece (7),
A short circuit detection circuit for detecting non-short circuit, (20a) is a diode, (20b), (20c) and (20d) are resistors, (20e) is a comparator, and (21) is a taper control mechanism.

Next, the operation of the conventional wire electric discharge machine having the above configuration will be described. As shown in FIG. 14, the wire electrode (1) has idlers (3a), (3b), (3c) and (3d) for changing the direction from the supply bobbin (2), and a brake roller (4) for applying tension. , The upper guide (5) serving as a supporting point in the processing portion, the lower guide (6), the processing start hole (8) of the workpiece (7), and the like, and is wound up by the collecting roller (9).

The machining liquid is supplied to the machining gap from the upper nozzle (10) and the lower nozzle (11), and is supplied to the wire electrode (1) from the power supply device (12) through the upper power supply (13) and the lower power supply (14). Processing is performed by the energy of the discharge generated by the voltage applied to the work (7). Power control circuit (12a)
Controls the discharge energy by changing the opening / closing cycle of the switching element (12b) according to the state of the machining gap and the set machining conditions.

The machining shape is given by an NC program such as paper tape, and the controller (15) mounts the X and Y tables (16) and (17) on which the workpiece (7) is placed on the fixed wire electrode (1). It is generated by driving and moving the workpiece (7) relatively. Further, as shown in FIG. 15, the machining shape is accurate in the distances l ₁ and l ₂ from the reference planes P ₁ and P _{2 of the} workpiece (7) and the pitches l ₃ and l ₄ between the machining shapes. In many cases, the machining start holes (8) and (18) are opened by setting a distance from the reference planes P ₁ and P ₂ . Processing start hole (8),
(18) is usually set at the center of the processed shapes A and B.

The taper control mechanism (21) consists of a U-axis that moves parallel to the X-axis and a V-axis that moves parallel to the Y-axis. By moving the upper guide (5) in the UV direction, the wire electrode (1) is processed. It can be tilted with respect to the object (7).

In the processing procedure, first, the wire electrode (1) is brought into contact with the reference planes P ₁ and P ₂ of the workpiece (7) to perform positioning. Next, after correcting the radius of the wire electrode (1), the wire electrode (1) is cut, and the work piece (7) is cut by the X, Y tables (16) and (17).
By a distance of l ₁ , l _{2 to} automatically feed the wire electrode (1
The wire electrode (1) is stretched through the processing start hole (8) by means of 9), and the wire electrode (1) is made to travel while ejecting the processing liquid from the upper and lower nozzles (10) and (11), and the power supply device ( Apply the voltage from 12) to start the NC program of the machining shape.

When the machining of the machining shape A is completed, the ejection of the machining liquid, the traveling of the wire electrode (1), the application of the machining voltage are stopped, the wire electrode (1) is cut, and the machining start hole (1
Move to pitch 8) by distance l ₃ and l ₄ . After that, the wire electrode (1) is stretched, and the same operation as in the above-described processing of the shape A is performed.

By the way, when the wire electrode automatic supply device (19) is not used for stretching the wire electrode (1) or cutting the wire electrode (1) through the processing start holes (8), (18), However, recently, there is a tendency that the automatic wire electrode feeder (19) is often used.
The wire electrode (1) running, machining power input, etc. are also coded in the NC program. Positioning is performed on the reference planes P ₁ and P ₂ , and after moving to the program start point, fully automatic movement has become possible.

The wire electrode automatic feeder (19) returns to the processing start holes (8) and (18) and re-stretches the wire electrode (1) even if the wire electrode (1) is broken or short-circuited during processing. Then
The machining can be continued by restarting the program from the beginning. For example, as disclosed in Japanese Patent Laid-Open No. 61-293724, the processing for the disconnection and the short circuit is performed at a position slightly reverse to the position where the disconnection and the short circuit occur, and the machining start hole (8), Go back to (18) and re-hang the wire electrode (1) and restart the program.
It has been proposed to restart the discharge at that position to eliminate the cause of disconnection and short circuit and prevent re-disconnection and re-short circuit.

For positioning on the reference planes P ₁ and P ₂ , a short circuit detection circuit (2
0) is used. As shown in FIG. 16, the short-circuit detection circuit (20) has a comparator (20e) with a low voltage −V ₁ at one end through a resistor R ₁ (20b) and a voltage −V ₂ at the other end with a resistor R ₁ (20b). ₂ (20
c), the reference voltage divided by the resistor R ₃ (20d) is applied, and when the wire electrode (1) and the workpiece (7) come into contact with each other, one end of the comparator (20e) is passed through the diode (20a). The short-circuit voltage is applied, becomes higher than the reference voltage, and the output can be output from the comparator (20e), so that the short-circuit can be detected.

The positioning operation is generally performed automatically by the control device (15). That is, as shown in FIG. 17, the wire electrode (1) and the workpiece (7) are in the non-short-circuited state S ₁ to the reference plane P ₁
When the positioning is commanded in the direction (X-direction), tension is applied to the wire electrode (1), and the wire electrode (1) gradually moves relatively to the reference plane P ₁ of the workpiece (7), and the short circuit detection circuit (20). The position at which the short-circuit signal is output from is set as the short-circuit position S ₂ (this may be repeated several times and the average thereof may be used). Normal,
The position of the wire electrode (1) confirmed by the control device (15) is the position of the upper guide (5) and the lower guide (6).
The short-circuit position S ₂ is displaced by the radius of the wire electrode (1) and needs to be corrected.

[Problems to be Solved by the Invention] A conventional wire electric discharge machining apparatus is configured as described above,
To perform EDM, wire electrode (1) and work piece (7)
A gap is required between the two and they cannot be processed if they are short-circuited. Therefore, the machining start hole (8) is displaced from the reference planes P ₁ and P ₂ (see FIG. 18 (a),
(B)), burr appears on the inner surface (Fig. 18 (c)),
The hole is bent with respect to the vertical (Fig. 18 (d)) or inclined, and the wire electrode (1) and the workpiece (7) are short-circuited due to the fact that they are inclined (Fig. 18 (e), (f)). However, there was a problem that even if automatic wire processing was possible due to the wire electrode automatic supply device (19), it could not be processed because it could not be processed. This can be said even when the worker is working, and it is troublesome to release the short circuit, and even if it can be released, there is a problem that the position from the reference planes P ₁ and P ₂ is displaced. It was Note that the wire electrode has rigidity, the inlet of the lower guide has a tapered shape, and the wire electrode automatic feeder restrains the wire electrode by jet water flow.
Stretching is possible even in the case of (e).

Further, the one disclosed in JP-A-61-293724 mentioned above, or an interpolator for moving the short-circuit detection circuit and the wire electrode from the short-circuit point to the unnecessary side of the work piece so as to cancel the short-circuit. (JP-A-56-39830), etc.,
Although various methods have been proposed for canceling short circuits during processing,
These are applicable only when it is known to which direction the wire electrode should be moved to clear the short circuit, and in the case of a machining start hole in which it is not known in which direction the short circuit will be cleared. There was a drawback that I could not.

In view of the above points, the present invention is a wire capable of automatically canceling the short circuit even if the wire electrode and the workpiece are short-circuited at the machining start hole and continuing the machining without impairing the accuracy. It is intended to provide a method for canceling a short circuit at a machining start hole of an electric discharge machine.

[Means for Solving the Problem] A method for canceling a short circuit in a machining start hole of a wire electric discharge machine according to a first invention of the present invention is to start machining according to a machining program and to perform machining in a machining start hole at the time of machining start. A first step of detecting a short circuit between the wire electrode and the workpiece, a second step of storing the relevant portion of the machining program at that time in a memory when the short circuit is detected, and a short circuit. With the position of the wire electrode at the start of processing as the origin, the wire electrode and the workpiece can be moved in multiple directions within a predetermined range.
A third step of dimensional relative movement, and a fourth step of advancing processing from that position to the origin position when the short circuit between the wire electrode and the workpiece is released during the relative movement,
After the fourth step, a fifth step of advancing the machining from the corresponding portion of the machining program stored in the second step is provided.

A method of releasing a short circuit in a machining start hole of a wire electric discharge machine according to a second aspect of the present invention starts machining according to a machining program, and a wire electrode and a workpiece in the machining start hole at the time of machining start. First step of detecting a short circuit of the wire, a second step of storing the relevant part of the machining program at that time in the memory when the short circuit is detected, and a wire at the time of starting the machining when the short circuit is detected. A third step in which the wire electrode and the workpiece are two-dimensionally moved relative to each other within a predetermined range in multiple directions with the position of the electrode as an origin, and a short circuit between the wire electrode and the workpiece is generated during the relative movement. Once released,
A fourth step of rewriting the machining start position of the machining program, which is the origin, with the position where the short circuit has been released, and, after the fourth step, advance the machining from the relevant part of the machining program stored in the second step. It is characterized by having 5 steps.

Further, in the first and second inventions, the wire electrode is tilted with respect to the work piece or moved on the locus set with respect to the origin instead of performing the two-dimensional relative movement in the third step. It is designed to be tilted for circular motion.

[Operation] In the present invention, even if the wire electrode and the workpiece are short-circuited at the machining start hole, they are two-dimensionally moved relative to each other in multiple directions, or the wire electrode is inclined with respect to the workpiece. Alternatively, since the short circuit can be automatically released by inclining and making a circular motion, it becomes possible to continue machining without impairing accuracy.

[Examples] Hereinafter, the present invention will be described with reference to illustrated examples.

1 to 5 are views for explaining a method of releasing a short circuit in a machining start hole of a wire electric discharge machine according to an embodiment of the first invention of the present invention, and FIG. 1 is a method of the present embodiment. 2 is a block diagram showing a configuration of a wire electric discharge machine for realizing the above, FIGS. 2 (a) and 2 (b) are explanatory views showing one form of a wire electrode short-circuit release operation according to the present embodiment, and FIG. FIG. 4 is a flowchart of a short-circuit release operation according to this embodiment, FIG. 4 is a diagram showing an example of a machining program according to this embodiment, and FIG. 5 is a diagram showing an example of a correction program after release of a short-circuit. The same reference numerals are given to the parts. As shown in FIG. 1, the wire electric discharge machine according to the present embodiment includes a wire position detecting means (31) for reading the position of the wire electrode (1) and sequentially storing it in a memory (30), and a workpiece (7). ) On which X, Y tables (16), (17) and wire electrodes (1) are placed
Drive control means (33) for controlling a drive unit for driving a taper control mechanism (21) for inclining the workpiece with respect to a workpiece (7) based on a machining program (32), and a wire electrode (1)
Short circuit detection circuit (20) that detects a short circuit between the workpiece and the workpiece (7) and outputs a short circuit signal, and cancels the short circuit when a short circuit signal is input from the short circuit detection circuit (20) at the start of processing. Drive control means (3
Machining start hole short circuit release means (34) that gives instructions to 3)
It consists of and.

That is, when the short circuit detection circuit (20) detects a short circuit between the wire electrode (1) and the workpiece (7) at the start of machining, the machining start hole short circuit canceling means (34) performs the machining program at that time ( 32) memory to be executed part (30)
And to control the driving unit so that the wire electrode (1) moves two-dimensionally within a predetermined range with respect to the workpiece (7) with the position at the start of processing as the origin O ₁ When an instruction is given to the drive control means (33) and the short circuit signal from the short circuit detection circuit (20) disappears during this relative movement, this relative movement is stopped and the wire position O _{2 at} that time is changed to the origin O. _The drive control means (33) is instructed to perform machining up to _one position and then proceed with machining from the portion of the machining program (32) to be executed stored in the memory (30).

Next, a method of canceling a short circuit at the machining start hole using the wire electric discharge machine having the above-described configuration will be described.
In the machining start hole (8) shown in FIG. 2 (a), when the machining is started by the machining program (32) shown in FIG. 4, the wire electrode (1) and the workpiece (7) are short-circuited. In the state, since the voltage does not appear in the machining gap at sequence number N006, the short circuit detection circuit (20) detects a short circuit and outputs a short circuit signal to the machining start hole short circuit canceling means (34). The machining start hole short circuit canceling means (34) recognizes the short circuit by the short circuit signal input from the short circuit detecting circuit (20) and issues a command to the drive control means (33) to interrupt the machining, and the short circuit canceling routine (35). To start. The short circuit release routine (35) is the processing start hole short circuit release means (34).
Incorporated as software within.

This will be described in more detail with reference to the flowchart of FIG. 3. When the machining is started at the machining start hole (8) and the short circuit detection circuit (20) detects the short circuit between the wire electrode (1) and the workpiece (7). Is determined (step 1), if there is no short circuit, the machining is continued (step 2), and if there is a short circuit, the process proceeds to the short circuit release routine. In the short-circuit release routine, first, the current position (origin O ₁ (X ₀₁ , Y ₀₁ ) detected by the wire position detection means (31)
Machining the X and Y coordinates of
It is stored in the variables X ₁ and Y ₁ of the memory (30) by 4) (step 3). This origin O ₁ (X ₀₁ , Y ₀₁ ) is an accurate position from the reference planes P ₁ and P ₂ , and programs are often written as absolute value commands, so the coordinates here are absolute value coordinates. .

Next, the drive control means (33) applies tension to the wire electrode (1) according to an instruction from the processing start hole short circuit releasing means (34) (step 4), and the processing start hole short circuit releasing means (34) causes the short circuit detection circuit. (20) is operated (step 5), and in this state, the machining start hole short circuit releasing means (34) moves the wire electrode (1) to the workpiece (7) in the X + direction by the set distance L.
The drive control means (33) is instructed to move at a certain speed F, whereby the drive control means (33) drives and controls the X, Y tables (16) and (17) so that the above-mentioned relative movement is performed. (Step 6). The speed F is not particularly limited as long as it is not too high.

When the short circuit between the wire electrode (1) and the workpiece (7) is not released during the movement (step 7) and the movement amount reaches the distance L (step 8), the machining start hole short circuit releasing means (3)
According to the instruction of 4), the drive control means (33) returns the wire electrode (1) to the origin O ₁ (step 9), and further carries out the same short circuit release processing in the X-direction.

Hereinafter, the processing start hole short circuit releasing means (34) attaches the wire electrode (1) to the workpiece (7) as shown in FIG. 2 (b).
Against Y + direction, Y- direction, θ = 45 ° direction, θ = 225 °
Direction, θ = 135 ° direction, θ = 315 ° direction, if the short circuit is not released, the drive control means (33) is finally instructed to move radially about the origin O ₁ , and the broken line The same process as the enclosed part A ₁ is repeated (step 10). If the short circuit is still not released, the machining start hole short circuit canceling means (34) instructs the drive control means (33) to stop the short circuit canceling operation, or instructs to move to the next machining starting hole, and The processing of the processing shape is started (step 11).

FIG. 2A shows a case where the short circuit is released while moving in the Y + direction. That is, if the short circuit is released in step 7, the drive control means (33) stops the movement of the machining start hole short circuit releasing means (34) at that position (O ₂ (X ₀₂ , Y ₀₂ )). (Step 12), the operation of the short-circuit detection circuit (20) is stopped (step 13), and the X and Y coordinates of O ₂ (X ₀₂ , Y ₀₂ ) which is the short-circuit release position are stored in the memory (30). Read into variables X ₂ and Y ₂ (step 14).

Machining is possible from the short circuit release position O ₂ , but when machining is performed from the short circuit release position O _{2 with the} original program (32), the reference plane
Since the distances from P ₁ and P ₂ are incorrect, the machining start hole short circuit releasing means (34) causes the drive control means (33) to correct this. That is, the portion to be executed by the original program (32) (usually the head portion if there is one machining shape, the head portion of the shape to be machined if there are multiple machining shapes) is stored in the memory (30). (Step 15), temporarily save it from the original program (32), and store it in the memory (30) in advance.
The correction program (36) that has been stylized and stored in a specific portion of is executed (step 16).

Variables X ₁ , Y ₁ , X ₂ , Y _{2 of the} correction program (36) shown in FIG.
Since the memorized X and Y coordinates of O ₁ and O ₂ are set,
By causing the drive control means (33) to execute the correction program (36), processing is performed from the point O ₂ where the short circuit has been released to the origin O ₁ , and the wire electrode (1) returns to the normal position.

After that, the machining start hole short circuit releasing means (34) causes the drive control means (33) to read the portion of the original program (32) to be executed from the memory (30) and continue from this portion to be executed (step 17). ). As a result, the short circuit release operation at the machining start hole is completed.

Although the same code is duplicated in FIG. 5, there is no problem.

In addition, the set distance L is a value that does not break even if the wire electrode (1) is brought into contact with the workpiece (7) by the applied tension.
It can be determined experimentally.

Further, if the drive control means (33) is provided with a condition table and the operator inputs the wire electrode diameter or material or codes it in the program, the optimum value can be switched and set according to the wire electrode diameter or material. Will also be possible.

By the way, the cause of the case where the short circuit is not released even if the circuit moves radially in all directions in the process of step 10 of FIG.
The machining start hole shape shown in FIG. That is, when the plate thickness of the workpiece (7) is h, the diameter of the processing start hole (8) is d, and the inclination of the processing start hole (8) is θ, h = tan θd.

6 to 8 show the first invention of the present invention in which the circular movement of the upper guide (5) is further added to the above radial movement so that the short circuit can be released even in such a case. It shows another embodiment. This will be described in more detail with reference to FIGS. 1 and 2 as well. In the machining start hole (8) shown in FIG. 2 (a), the machining program (32) shown in FIG. 7 is used for machining. When the wire electrode (1) and the workpiece (7) are short-circuited at the start, the short-circuit detection circuit (20) detects a short-circuit because no voltage appears in the machining gap at sequence number N006. A short circuit signal is output to the machining start hole short circuit canceling means (34). The machining start hole short circuit release means (34) confirms the short circuit by the short circuit signal input from the short circuit detection circuit (20) and confirms the drive control means (3).
It issues a command to 3) to interrupt machining, and activates the short-circuit release routine (35). The short circuit release routine (35) is incorporated as software in the machining start hole short circuit release means (34).

This will be described in more detail with reference to the flowcharts of FIGS. 6 (a) and 6 (b). In FIG. 6 (a), the machining is started at the machining start hole (8), and the short circuit detection circuit (20) causes the wire electrode to move. It is judged whether or not there is a short circuit between (1) and the workpiece (7) (step 101). If there is no short circuit, the machining is continued (step 102), and if there is a short circuit, the short circuit release routine (35) is executed. In the short circuit release routine (35), first, the current position detected by the wire position detection means (31) (origin O ₁ (X ₀₁ , Y ₀₁ , U
₀₁ , U ₀₁ )) X, Y, U, V coordinates are processed by the start hole short-circuit releasing means (34) to variables X ₁ , Y ₁ , U ₁ , V ₁ of the memory (30).
(Step 103). This origin O ₁ (X ₀₁ , Y ₀₁ ,
U ₀₁ , V ₀₁ ) is an accurate position from the reference planes P ₁ , P ₂ , and since the program is often written by an absolute value command, the coordinates here are absolute value coordinates.

Next, the drive control means (33) applies tension to the wire electrode (1) according to an instruction from the processing start hole short circuit releasing means (34) (step 104), and the processing start hole short circuit releasing means (34).
Activates the short circuit detection circuit (20) (step 105), and in this state, the machining start hole short circuit release means (34) moves the wire electrode (1) to the workpiece (7) by the set distance L in the X + direction. The drive control means (33) is instructed to move the work piece (7) at a certain speed F, whereby the drive control means (3
3) is the X, Y table (1
6) and (17) are drive-controlled (step 106).

When the short circuit between the wire electrode (1) and the workpiece (7) is not released during the movement (step 107) and the movement amount reaches the distance L (step 108), the machining start hole short circuit releasing means (34). ), The drive control means (33) returns the wire electrode (1) to the origin O ₁ (step 109), and further carries out a similar short circuit release process in the X-direction.

Hereinafter, the processing start hole short circuit releasing means (34) attaches the wire electrode (1) to the workpiece (7) as shown in FIG. 2 (b).
Against Y + direction, Y- direction, θ = 45 ° direction, θ = 225 °
Direction, θ = 135 ° direction, θ = 315 ° direction, if the short circuit is not released, the drive control means (33) is finally instructed to move radially about the origin O ₁ , and the broken line The same processing as in the enclosed portion A ₂ is repeated (step 110).
If the short circuit is still not released, the machining start hole short circuit releasing means (34) gives an instruction to the drive control means (33) to operate the taper control mechanism (21) according to the subroutine B shown in FIG. 6 (b) ( Step 111).

If the short circuit is released in step 107, the machining start hole short circuit release means (34) is moved to the position (O ₂ (X ₀₂ , Y ₀₂ , U ₀₂ ,
V ₀₂ )) to instruct the drive control means (33) to stop the movement (step 112), and further to detect the short circuit (2).
0) operation is stopped (step 113), and the X, Y, U, V coordinates of O ₂ (X ₀₂ , Y ₀₂ , U ₀₂ , V ₀₂ ) at this short circuit release position are stored in the memory (3
0) variables X ₂ , Y ₂ , U ₂ , V ₂ are read (step 114).

Machining is possible from the short circuit release position O ₂ , but when machining is performed from the short circuit release position O _{2 with the} original program (32), the reference plane
Since the distances from P ₁ and P ₂ are incorrect, the machining start hole short circuit releasing means (34) causes the drive control means (33) to correct this. That is, the part of the original program (32) to be executed is stored in the memory (30) (step 115), temporarily saved from the original program (32), and previously stored in the memory (30).
The correction program (36) that has been stylized and stored in a specific part of the is executed (step 116).

Variables X ₁ , Y ₁ , U ₁ , V ₁ , of the correction program (36) shown in FIG.
The stored X ₁ , Y, U, V coordinates of O ₁ , O ₂ are set in X ₂ , Y ₂ , U ₂ , V ₂ , so the short circuit was released by executing the correction program (36). Processing is performed from the point O ₂ to the origin O ₁ , and the wire electrode (1) returns to the normal position.

After that, the processing start hole short circuit releasing means (34) causes the drive control means (33) to read the portion of the original program (32) to be executed from the memory (30) and continue from this portion to be executed (program 117). ). As a result, the short circuit release operation at the machining start hole is completed.

Although the same code is duplicated in FIG. 8, there is no problem.

In subroutine B, processing start hole short circuit release means (3
4) resets the counter R that counts the number of movements (setting number N) from the origin O _{1 in a} certain direction (R = 0) (step
120), and then the number obtained by dividing the distance L (set number n)
After setting the counter M for counting M to 1 (step 121), first, with respect to the drive control means (33) at the origin O ₁ ,
It is instructed to operate the taper control mechanism (21) so that the upper guide (5) draws a circle with a radius ML / n (= 1 L / n) and a speed F. In response to this instruction, the drive control means (33) drives the U and V axes to tilt the wire electrode (1) (step 122).

If the short circuit between the wire electrode (1) and the workpiece (7) is not released during the circular movement of the upper guide (5) (step 123) and the upper guide (5) rotates once (step 124), The machining start hole short circuit releasing means (34) updates the counter M (M = M + 1) (step 125), and if the counter M does not reach the divided number (M ≦ n) (step 126),
Returning to step 122, the drive control means (33) is again instructed to set the radius to 2 L / n and perform the similar short circuit cancellation processing by the circular motion.

If the short circuit is not released even if the radius is increased to L (M = n), the machining start hole short circuit release means (34) uses the U and V axes of the taper control mechanism (21) as the origin with respect to the drive control means (33). O ₁
Instruct to return to (U ₀₁ , V ₀₁ ) (step 127). Next, if the counter R has not reached the number of movements N (R ≦
N) (step 128), processing start hole short circuit release means (3
4) updates the counter R (R = R + 1) (step 12
9), further RL / N in the X + direction with respect to the drive control means (33)
It is instructed to move the wire electrode (1) and the workpiece (7) relative to each other at a speed F (= 1 L / N) (step 130).
As a result, the drive control means (33) drive-controls the X, Y tables (16), (17) so that this relative movement is performed. When this relative movement is completed, the machining start hole short circuit release means (34) then sends the step 122 to the drive control means (33).
Then, the instruction is made to cause the taper control mechanism (21) to perform the short circuit release processing operation by the circular motion similar to that described above. According to this instruction, the drive control means (33) drive-controls the U and V axes.

When the counter R reaches the number of movements N in step 128 (R = N), the drive control means (33) sets the X and Y axes to the origin O ₁ (X ₀₁ by the instruction of the machining start hole short circuit releasing means (34). , Y ₀₁ )
(Step 131), and the same short circuit releasing process is performed by the X, Y tables (16) and (17) in the X-direction and the taper control mechanism (21). Hereinafter, the processing start hole short circuit releasing means (34) is, as shown in FIG. 2 (b), Y + direction, Y- direction, θ = 45 ° direction, θ = 225 ° direction, θ = 135 ° direction, θ.
In the order of the = 315 ° direction, if the short circuit is not released, the drive control means (33) is instructed to perform a circular motion while moving radially about the origin O ₁ , and the same as the part B surrounded by the broken line. The processing is repeated, and finally the short-circuit release processing operation is tried (8 directions × (N + 1) times × the inclination of the wire electrode (n ways)) = 8n (N + 1) times (step 132). Here, the above-mentioned values of n and N can be arbitrarily selected, but if they are set to be large, it takes too much time, so it is preferable to set them to about 10 and it is practical.

If the short circuit is not released even in step 132, the machining start hole short circuit releasing means (34) will cause X to the drive control means (33).
Instruct the Y tables (16) and (17) and the taper control mechanism (21) to stop the short circuit release operation, or to move to the next machining start hole, and start machining the next machining shape ( Step 133).

If the short circuit is released in step 123, the processing start hole short circuit release means (34) causes the drive control means (33) to perform the same processing as steps 112 to 117 in FIG. 6 (a) described above. The operation is performed in steps 134 to 139, and the short circuit releasing operation at the processing start hole is completed.

If the wire electrode (1) is broken during processing, consider the automatic wire electrode feeder (19) (Fig. 14) that returns to the processing start hole (8) and re-hangs the wire electrode (1). It is preferable to leave the correction program until the processing of the shape is completed.

By the way, since the first machining (origin O ₁ → point P in FIG. 2 (a)) from the machining start hole (8) is generally run-up machining, the origin O from the point O ₂ where the short circuit is released. _The point P may be directly processed without returning to ₁ .

FIG. 9 is an explanatory diagram showing an operation after the short circuit is released and a program example thereof according to an embodiment of the second invention of the present invention in which the point O ₂ from which the short circuit is released is directly processed to the point P. In this embodiment, similarly to the one embodiment of the first invention described above (FIGS. 2 to 5), the machining catat hole short circuit releasing means (34) detects a short circuit at the start of machining. Circuit (2
When the short circuit signal is input from (0), the relevant part of the machining program at this point is stored in the memory (30) and
The position of the wire electrode (1) at the start of processing is the origin O ₁ (X ₀₁ , Y
₀₁ ) X, Y coordinates of origin O ₁ as variables X ₁ , Y _{1 in} memory (30)
Further, the drive control means (33) is instructed to radially move the wire electrode (1) and the workpiece (7) relative to the origin O ₁ . If the short circuit is released during this relative movement,
Processing start hole Short circuit release means (34) is the position where the short circuit is released.
The X, Y coordinates of O ₂ (X ₀₂ , Y ₀₂ ) are read into the variables X ₂ , Y ₂ of the memory (30), and the machining start position of the machining program, that is, the origin O ₁ (X ₀₁ , Y ₀₁ ) is released. Position O ₂ (X ₀₂ ,
It is rewritten by Y ₀₂ ), and the drive control means (33) is instructed to proceed with the machining from the relevant portion of the rewritten machining program.

In the case of this embodiment, the program is changed, but since the first part of the program is standard, it can be automatically changed.

FIG. 10 is an explanatory diagram showing an operation after a short circuit is released and a program example thereof according to another embodiment of the second aspect of the present invention in which the point O ₂ from which the short circuit is released is directly processed to the point P. This embodiment is similar to the other embodiment of the first invention described above (FIGS. 6 to 8) in that the machining start hole short circuit releasing means (34) is short-circuited at the start of machining. When a short circuit signal is input from the detection circuit (20), the relevant part of the machining program at this point is stored in the memory (30) and the position of the wire electrode (1) at the start of machining is set to the origin O ₁ (X
₀₁ , Y ₀₁ , U ₀₁ , V ₀₁ ) X, Y coordinates of origin O ₁ are stored in memory (3
0) variables X ₁ , Y ₁ , U ₁ , V ₁ and further stored in the drive control means (3
Instruct 3) to move the wire electrode (1) and the work piece (7) relative to each other in a radial manner about the origin O ₁ . If the short circuit is not canceled even during the radial relative movement, the machining start hole short circuit canceling means (34) is the taper control mechanism (21).
The drive control means (33) is instructed to operate, and circular movement is performed while moving radially about the origin O ₁ .
If the short circuit is released during this radial relative motion and circular motion, the machining start hole short circuit release means (34) will cause X, Y, and X at the position O ₂ (X ₀₂ , Y ₀₂ , U ₀₂ , V ₀₂ ) where the short circuit has been released. U and V coordinates are stored in memory (3
Reads in the variable _{X 2, Y 2, U 2} , V 2 0), processing of the machining program start position, ie the origin _{O 1 (X 01, Y 01} , U 01,
V ₀₁ ) is rewritten by the position O ₂ (X ₀₂ , Y ₀₂ , U ₀₂ , V ₀₂ ) where the short circuit has been released, and the drive control means (33) is made to proceed with machining from the relevant portion of the rewritten machining program. Order.

In this embodiment as well, the program is changed, but the first part of the program is standard and can be automatically changed.

In each of the above-described embodiments, the present invention is shown in which the program is written by the absolute value command, but it is also applicable to the program written by the relative value command. Is. Example program in this case
It is shown in FIG. 11 and FIG. FIG. 11 shows a program example when the program of FIG. 5 is written by a relative value command, and FIG. 12 is a program example when the program of FIG. 8 is written by a relative value command. However, in the case of such a program example, an absolute value command / relative value command recognition unit and a relative value command correction program storage unit are required.

Further, in each of the above-described embodiments, the operation of releasing the short circuit is radial with the origin O ₁ as the center, but this may be spiral, circular or angular as shown in FIG. 13, for example. Even in such a case, the same effect as that of each of the above-described embodiments can be obtained.

In addition, instead of constantly moving the distance L in such radial or spiral movement, for example, a tension gauge such as a strain gauge is set on the shaft of the idler (3c) (Fig. 14) to short-circuit. The tension at the time of machining may be stored in the processing start hole short-circuit releasing means (34) memory (30), and if the tension at the time of movement becomes larger than this, the movement in that direction may be stopped there.

Furthermore, when a short circuit detection circuit (20) as shown in FIG. 16 is used to detect the release of the short circuit, when a working fluid with a low applied voltage and a low specific resistance value exists in the machining start hole (8). , It may not be detected although the short circuit is actually released due to the leakage current. Power supply in this case (12)
To the power supply control circuit (12a) (1st
It is also possible to detect the release of the short circuit by performing the detection in Fig. 4).

Furthermore, in addition to the above-described processing, the present invention can be applied to, for example, a function that cannot operate unless the short circuit is released (positioning of the hole center by detecting a short circuit, etc.). can do.

[Effects of the Invention] As described above, according to the present invention, even if the wire electrode and the workpiece are short-circuited in the machining start hole, they are relatively two-dimensionally moved in multiple directions, or the wire electrode Since the short circuit can be automatically released by tilting or tilting the object to be circularly moved, it is possible to continue the processing without impairing the accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wire electric discharge machine for realizing a method of releasing a short circuit at a machining start hole of a wire electric discharge machine according to an embodiment of the first invention of the present invention.
(A) and (b) are explanatory views showing one form of the short-circuit release operation of the wire electrode according to the present embodiment, FIG. 3 is a flowchart of the short-circuit release operation according to the present embodiment, and FIG. 4 is the present embodiment. FIG. 5 is a diagram showing an example of a machining program according to FIG. 5, FIG. 5 is a diagram showing an example of a correction program after releasing a short circuit, and FIGS. 6 (a) and 6 (b) are all other examples of the first invention of the present invention. FIG. 7 is a flowchart showing a method of releasing a short circuit at a machining start hole of the wire electric discharge machine, FIG. 7 is a diagram showing an example of a machining program according to the embodiment of FIG. 6, and FIG. FIGS. 9 and 10 are explanatory views showing an operation and a program example thereof after releasing a short circuit according to an embodiment of the second invention of the present invention, and FIG. 10 shows another embodiment of the second invention of the present invention. Equivalent to Fig. 9 and Fig. 11 are the relative value commands for the program of Fig. 5. FIG. 12 is a diagram showing an example of a program when written in FIG. 12, FIG. 12 is a diagram showing an example of a program when the program of FIG. 8 is written as a relative value command, and FIG. Fig. 14 is an explanatory view showing the form of Fig. 14, Fig. 14 is a configuration diagram showing a conventional wire electric discharge machine,
Fig. 15 is a plan view showing a work piece set in a conventional wire electric discharge machine, Fig. 16 is an explanatory view showing a short circuit detection circuit used in the conventional wire electric discharge machine, and Fig. 17 is a work piece reference. Explanatory diagram for explaining the wire electrode positioning operation on the plane,
18 (a), (b), (c), (d), (e),
(F) shows the relationship between the wire electrode and the machining start hole, and FIG. 18 (a) is a sectional view showing one mode thereof, and FIG. 18 (b) is the plane of FIG. 18 (a). FIGS. 18 (c), (d), (e), and (f) are cross-sectional views showing other embodiments. In the figure, (1) is a wire electrode, (7) is a workpiece,
(8) is a machining start hole, (16) and (17) are X and Y tables, (20) short circuit detection circuit, (21) is a taper control mechanism,
(30) is a memory, (31) is a wire position detecting means, (32)
Is a machining program, (33) is drive control means, (34) is a machining start hole short circuit canceling means, O ₁ is an origin, and O ₂ is a short circuit canceling position. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] 1. Starting machining according to a machining program,
A first step of detecting a short circuit between a wire electrode and a workpiece at a machining start hole at the time of machining start, and a second step of storing a relevant part of a machining program at that time in a memory when a short circuit is detected And a third step in which, when a short circuit is detected, the wire electrode and the workpiece are two-dimensionally moved within a predetermined range in multiple directions with the position of the wire electrode at the start of processing as an origin. When the short circuit between the wire electrode and the work piece is released during the relative movement, the fourth step of advancing the processing from that position to the origin position and the second step after the fourth step And a fifth step of advancing the machining from the corresponding portion of the machining program that has been performed. A method of releasing a short circuit in a machining start hole of a wire electric discharge machine. 2. In the third step, the wire electrode is tilted with respect to the workpiece or tilted on a locus set with respect to the origin so as to be circularly moved, instead of being two-dimensionally moved relative to each other. The method for canceling a short circuit in a machining start hole of a wire electric discharge machine according to claim 1. 3. Starting machining according to a machining program,
A first step of detecting a short circuit between a wire electrode and a workpiece at a machining start hole at the time of machining start, and a second step of storing a relevant part of a machining program at that time in a memory when a short circuit is detected And a third step in which, when a short circuit is detected, the wire electrode and the workpiece are two-dimensionally moved within a predetermined range in multiple directions with the position of the wire electrode at the start of processing as an origin. When the short circuit between the wire electrode and the workpiece is released during the relative movement, a fourth step of rewriting the machining start position of the machining program, which is the origin, by the position where the short circuit is released, and a fourth step And a fifth step of advancing the machining from a corresponding portion of the machining program stored in the second step, the method for canceling a short circuit in a machining start hole of a wire electric discharge machine. 4. In the third step, the wire electrode is tilted relative to the workpiece or tilted on a locus set with respect to the origin to perform a circular motion instead of the two-dimensional relative movement. The method for canceling a short circuit at a machining start hole of a wire electric discharge machine according to claim (3).