JPH05305520A - Wire electric discharge machine - Google Patents

Abstract

PURPOSE:To set exchanging timing of a feeder at optimum, prevent to continue an operation under unstable working condition, and previously prevent breaking of a wire electrode. CONSTITUTION:The same machining pulse voltage is respectively supplied to an upper feeder 17 and a lower feeder 19 by means of two independent voltage generating devices 21a, 21b so as to machine a workpiece 1, impedance between the upper feeder 17 and the lower feeder 19 through a wire electrode 3 is detected by means of a consumption detecting device 27, and the degree of consumption of the upper feeder 17 and the lower feeder 19 are detected from the detected value and a plurality of discriminating values which are previously set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machine for machining a work piece by repeatedly generating pulsed electric discharge between a wire electrode and the work piece.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a wire electric discharge machine of this type has a wire electrode 3 for processing a workpiece 1, a supply bobbin 5 for supplying the wire electrode 3, and a wire electrode 3. Rollers 7 and 9 for applying tension, a winding bobbin 11 for collecting the used wire electrode 3, a wire guide 13 for slidably holding the wire electrode 3 and guiding it to a predetermined position,
15, upper supply electron 17 and lower supply electron 1 that supply a processing pulse voltage to the wire electrode 3 by sliding contact with the wire electrode 3.
9. A machining power supply 21 for supplying the machining pulse voltage to the upper-feeding electron 17 and the lower-feeding electron 19 is provided, and the pulsed electric discharge is repeatedly generated between the wire electrode 3 and the workpiece 1 to be processed. It is configured to process the object 1.

[0003] Here, since the upper charge electron 17 and the lower charge electron 19 are consumed due to friction with the wire electrode 3 during processing of the workpiece 1, the wire electrode 3, the upper charge electron 17 and the lower charge electron 1 are consumed.
The contact with 9 deteriorates. As a result, the power supply efficiency of the machining pulse voltage to the wire electrode 3 is reduced, so that the machining becomes unstable, and the machining accuracy is deteriorated due to the variation of the machining conditions. Further, if this state continues, the wire electrode 3 vibrates, and when the wire electrode 3 separates from the upper charge electron 17 or the lower charge electron 19, abnormal discharge occurs at that portion, so that the wire electrode 3 may be disconnected.

Therefore, in order to solve this problem, for example, as disclosed in Japanese Patent Laid-Open No. 62-287935, that is, as shown by a broken line in FIG.
And mechanical proximity switches 23, 2 in the vicinity of
5 are provided respectively, and by the proximity switches 23 and 25,
It has been considered to detect a position shift of the wire electrode 3 due to consumption of the upper charge electron 17 and the lower charge electron 19 and to alert the worker to that effect.

[0005]

However, since the consumption of the power supply gradually progresses during the processing of the workpiece, and the stability and the processing accuracy of the processing gradually deteriorate, the life of the power supply is reduced. It is very difficult to judge with one point.

[0006] That is, if the judgment value of the life of the power supply is set so that the life is judged earlier, the worker must replace the power supply in a short cycle, and the operation rate of the wire electric discharge machine is lowered. To do. However, conversely, if the above-mentioned judgment value is set so as to judge the life of the power supply terminal late, the operation rate of the wire electric discharge machine will improve, but unstable machining may continue. The electrodes may be broken. In the conventional wire electric discharge machine, if the wire electrode is disconnected before the life of the power supply is detected, no detection can be performed thereafter.

Further, in the conventional wire electric discharge machine which detects the consumption of the power supply by utilizing the physical stress, several judgment values are set in order to optimize the replacement time of the power supply. It's also difficult to try. Therefore, in setting the judgment value of the life of the power supply terminal, a large margin must be set in advance, and the operating rate of the wire electric discharge machine itself is reduced.

The present invention has been made in view of the above problems. By accurately detecting the degree of consumption of the power supply, the replacement time of the power supply is optimized, and work is performed under unstable machining conditions. It is an object of the present invention to provide a wire electric discharge machine that can prevent continuation and prevent wire electrode breakage.

[0009]

In order to achieve the above object, a wire electric discharge machine according to the present invention is provided with a wire electrode for machining a work piece, and a wire electrode arranged above and below the work piece, respectively. The wire electrode and the workpiece are provided with: upper-feed electrons and lower-feed electrons for supplying a machining pulse voltage to the wire electrode; and voltage supply means for supplying the working pulse voltage to the upper-feed electron and the lower-feed electron. A wire electric discharge machine for machining a workpiece by repeatedly generating a pulsed electric discharge between the electric power supply device and the electric power supply device for supplying the same machining pulse voltage to the upper feed electron and the lower feed electron. An impedance detection unit that is composed of two independent voltage generation units that are supplied, further detects an impedance between the above-mentioned upper-feed electron and lower-feed electron, and is detected by the impedance detection unit. It is provided with abnormality detecting means and a value with a preset plurality of determination values of the impedance to detect the degree of power consumption of the upper feed element and the lower feed contact, the.

[0010]

In the wire electric discharge machine of the present invention configured as described above, the voltage supply means supplies the same machining pulse voltage to the upper feed electron and the lower feed electron by the two independent voltage generating means. , Process the work piece. Then, during the above-mentioned working operation, the impedance detecting means detects the impedance between the upper-feed electron and the lower-feed electron via the wire electrode. Next, the abnormality detecting means detects the degree of consumption of the upper feed electron and the lower feed electron from the impedance value detected as described above and a plurality of preset determination values. The result detected by the abnormality detecting means is used as a parameter for displaying the consumption state of the supercharged electron and the subcharged electron to the operator and for changing the processing condition to the voltage supply means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing the configuration of a wire electric discharge machine according to an embodiment of the present invention. In FIG.
The same components as those of the conventional wire electric discharge machine described with reference to FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, the wire electric discharge machine of the present embodiment detects the impedance between the upper feed electron 17 and the lower feed electron 19 via the wire electrode 3, and detects the detected impedance value and the impedance value in advance. A consumption detecting device 27 that detects the degree of consumption of the upper charge electron 17 and the lower charge electron 19 from the set plurality of determination values and outputs the result, an interface 29 that receives the above detection output of the wear detecting device 27, and an interface 29. A display device 31 for displaying to the operator the degree of wear of the upper charge electron 17 and the lower charge electron 19 in accordance with a signal from the device, and the same components as the conventional wire electric discharge machine described in FIG. It is composed of a processing condition setting device and the like.

Here, the output signal of the consumption detecting device 27 is
It is also configured to be distributed to the machining power source 21 via the interface 29, and when the consumption of the upper power supply electron 17 and the lower power supply electron 19 reaches the limit, the processing power supply 21 is stopped. Further, the wire electric discharge machine of this embodiment has two independent voltage generators 21 in the machining power source 21.
a and 21b, and the respective voltage generators 21a and 21b supply the same machining pulse voltage to the upper feed electron 17 and the lower feed electron 19, respectively.

That is, in the wire electric discharge machine of this embodiment, the wear detecting device 27 functions as both the impedance detecting means and the abnormality detecting means of the present invention. Next, details of the wear detecting device 27 shown in FIG.
Will be explained. As shown in FIG. 2, the wear detecting device 27 in the wire electric discharge machine according to the present embodiment includes the wire electrode 3
Resistors R1 and R2 for applying a DC voltage between the upper-feed electron 17 and the lower-feed electron 19 and detecting the impedance (hereinafter, referred to as impedance Z) as the detection voltage Vw through the Pulse voltage consumption detector 27
The diode D1 and the power supply voltage (12 V in this embodiment) for dividing the detection voltage Vw into
From the three determination reference voltages Vref1 and Vre used to determine the degree of wear of the upper charge electron 17 and the lower charge electron 19.
resistors R11, R12 for making f2, Vref3,
R21, R22, R31, R32, comparators CM1, CM2, CM3 for comparing the detection voltage Vw and the judgment reference voltages Vref1, Vref2, Vref3 to judge the degree of consumption of the upper charge electron 17 and the lower charge electron 19, respectively. Bowl CM
1, a photocoupler PC1, which is driven by the outputs of CM2 and CM3 and outputs the above judgment result to the interface 29.
It is equipped with PC2, PC3 and the like.

Here, the resistors R1 to R32 are set as in the following equation.

[0016]

[Equation 1]

Normally, the upper charge electron 17 and the lower charge electron 19 are short-circuited by the wire electrode 3, so that the impedance Z is substantially zero. Therefore, the upper and lower power supply electronics 17,
When 19 and the wire electrode 3 are normal, the relationship of the following equation is established. Vw <Vref1 <Vref2 <Vref3 However, when the upper charge electron 17 and the lower charge electron 19 are consumed, the impedance Z increases, and the detection voltage Vw also increases accordingly. Therefore, the comparator CM1 compares the detection voltage Vw with the determination reference voltage Vref1 to obtain Vr.
When ef1 <Vw, the photocoupler PC1 is driven. The comparator CM2 also detects the detection voltage Vw and the judgment reference voltage Vr.
ef2 is compared, and the photocoupler PC2 is driven when Vref2 <Vw. The comparator CM3 detects the detection voltage V
w and the determination reference voltage Vref3 are compared, and Vref3 <
At Vw, the photocoupler PC3 is driven.

Then, the photo couplers PC1, PC2,
The output of the PC 3 is distributed to the display device 31 and the processing power source 21 via the interface 29. Display device 31
Turns off all photo couplers PC1, PC2, PC3,
That is, when Vw ≦ Vref1, the upper and lower power supply devices 17, 1
9 is displayed in a normal state, and the photo coupler PC is displayed.
When only 1 is ON, that is, when Vref1 <Vw ≦ Vref2, a warning display indicating that the upper and lower power supply terminals 17 and 19 have begun to be consumed is displayed. Further, the display device 31 is a photo coupler PC.
Two of 1 and PC2 are ON, that is, Vref2 <Vw ≦ V
At the time of ref3, a warning display indicating that the upper and lower power supply terminals 17 and 19 are close to the limit is displayed. And photo coupler PC1, PC
2, when all of PC3 are ON, that is, when Vref3 <Vw, the processing power supply 21 stops supplying the processing pulse voltage to the upper and lower power supply terminals 17 and 19, and the display device 31
As described above, the display that the machining power supply 21 has stopped is displayed.

As described above, in the wire electric discharge machine according to the present embodiment, when the workpiece 1 is machined, the machining power source 21 uses the two independent voltage generators 21a and 21b to supply the upper feed electron 17 and the lower feed power. Since the same machining pulse voltage is supplied to each of the electrons 19, the machining power source 21 does not need to adopt the one-side power feeding method of low machining efficiency in which the machining pulse voltage is supplied to only one of the upper and lower power supply electrons 17 and 19. The consumption detecting device 27 can detect the impedance Z as a stable DC voltage without being affected by the power supply lines to the upper and lower power supply terminals 17 and 19.

Since the impedance Z can be detected stably as described above, a plurality of judgment reference voltages can be set accurately, and therefore, the degree of wear of the upper charge electron 17 and the lower charge electron 19 can be accurately determined. It can be detected in stages. Further, since the judgment reference voltage can be adjusted only by adjusting the resistors R11 to R32, the optimum setting can be easily realized.

Therefore, the wire electric discharge machine of this embodiment is
Informing the operator of the optimal time to replace the power supply, and stopping the machining power supply when the power supply reaches the limit,
It is possible to prevent the work from being continued under unstable processing conditions and further prevent the wire electrode from breaking.

Further, in the wire electric discharge machine of this embodiment,
Since the consumption of the power supply electron is detected by applying a DC voltage between the upper power supply electron 17 and the lower power supply electron 19, there is no mechanical detection delay such as in a proximity switch using physical stress, and There is no need for a high-frequency AC voltage generator as in the case of applying a high-frequency AC voltage between electrons to detect impedance. Then, when the wire electrode 3 is broken, the impedance Z becomes extremely large, so that this can be detected instantaneously for the above reason.

In the wire electric discharge machine of this embodiment, the degree of consumption of the power supply is classified into three levels and detected.
The number of steps may be changed as necessary.

[0024]

As described above, in the wire electric discharge machine of the present invention, when machining a workpiece, the voltage supply means uses two independent voltage generating means to supply the upper-feed electron and the lower-feed electron, respectively. Since the same processing pulse voltage is supplied, the impedance detection means does not affect the power supply line from the voltage supply means to the upper and lower power supply electrons, and does not reduce the processing efficiency. The impedance between the electron and the sub-charged electron can be stably detected.

Since stable impedance detection is possible as described above, a plurality of judgment values preset by the abnormality detecting means can be set accurately, and therefore the abnormality judging means can accurately determine the change in impedance. Moreover, it is possible to detect the degree of consumption of the upper and lower power supply terminals. Further, even when the impedance value becomes extremely large, it is possible to detect the disconnection of the wire electrode. Further, as described above, since the degree of consumption of the power supply can be accurately detected, it is possible to easily adjust the set value margin of the determination value for determining the final replacement time of the power supply to the minimum.

Therefore, the wire electric discharge machine of the present invention can prevent the continuation of work under unstable machining conditions and prevent the wire electrode from breaking while optimizing the time for exchanging the power supply. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a wire electric discharge machine according to an embodiment.

FIG. 2 is a circuit diagram showing details of a wear detecting device for detecting wear of the power supply in the wire electric discharge machine of the embodiment.

FIG. 3 is a schematic configuration diagram showing a configuration of a conventional wire electric discharge machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Workpiece 3 ... Wire electrode 17, 19 ... Electron supply 21 ... Machining power supply 21a, 21b ... Voltage generator 27 ... Consumption detection device 29 ... Interface 31 ... Display device

Claims (1)

[Claims] 1. A wire electrode for processing a work piece, and upper-feeding electrons and lower-feeding electrons, which are arranged above and below the work piece, and which supply a processing pulse voltage to the wire electrode, respectively. Voltage supply means for supplying the machining pulse voltage to the power supply and the bottom supply electron, and the workpiece is machined by repeatedly generating pulsed electric discharge between the wire electrode and the workpiece. In the wire electric discharge machine, the voltage supply means is composed of two independent voltage generation means for supplying the same machining pulse voltage to the upper feed electron and the lower feed electron, respectively. From the impedance detection means for detecting the impedance between the power supply terminal and the power supply terminal and the impedance value detected by the impedance detection means and a plurality of preset judgment values, A wire electric discharge machine, comprising: an abnormality detection unit that detects the degree of consumption of the sub-feeding electron.