JPS6377609A - Electric discharge device - Google Patents

Abstract

PURPOSE:To maintain proper processing in stable discharge processing by controlling the upper limit of the processing current from a processing current control device according to a signal from an abnormal processing avoidance frequency detection device and a stable processing duration time detection device being added. CONSTITUTION:In addition to a processing current control device 30, a processing condition detection device 26 and an abnormal processing control program 28 which constitute an abnormal processing avoidance device 320, an abnormal processing avoidance frequency detection device 31 and a stable processing duration time detection device 33 are added. And processing current appropriate for the current processing is supplied from the processing current control device 30 by detecting an omen of abnormal processing with both devices 31, 33 being added. Accordingly, in addition to that stable discharge in accordance with the processing condition can be obtained, a suspension time which determines current value to be supplied to electric discharge can be set automatically and it becomes possible to shift to the electric control which enables stable discharge processing after expanding the suspension time of electric discharge condition being set from the minimum current value step by step when starting the electric discharge.

Description

Detailed Description of the Invention (Industrial Application Field) This invention consists of an electrode that is formed into a predetermined shape and moves up and down in two directions, and an electrode that is movable in eight directions in the X-Y direction and placed on a loss table. Heat generation due to conductor resistance caused by repeatedly generating pulsed arc discharge using, for example, a DC RC discharge circuit in the machining gap formed between the workpiece, heat generation due to double bombardment, and pressure due to steam generation, etc. The present invention relates to an electric discharge machining device that melts a workpiece and performs a predetermined machining on the workpiece.In particular, the present invention allows easy setting of a machining medium during electric discharge machining, and moreover, For example, it is possible to prevent abnormal electrical discharge machining caused by excessive power supply, and to automatically return the electric crab to the range where stable electrical discharge machining is possible without returning to the power supply range where abnormal machining occurs. The present invention relates to an electric discharge machining apparatus having an abnormal machining avoidance device that can continue stable electric discharge machining.

[Conventional technology]

Figures 10 to 14 show conventional electrical discharge machining equipment of this type, with Figure 10 being a schematic configuration diagram of a general electrical discharge machining equipment, Figure 11 being a block diagram of an abnormal machining avoidance device, and Figure 12 ~FIG. 14 is an explanatory diagram of abnormal machining avoidance operation. First of all
In figure 0, 00 is the electrical discharge machine main body or machining tank, α
4) is the machining electrode, (16) is the workpiece, (1) is the machining control power supply, and (a) is the NC (numerical) control device, which is inside the machining tank installed in the head of the electrical discharge machine. The machining electrode Q4) facing the workpiece (16) with a predetermined gap therebetween performs electrical discharge machining on the workpiece (1B) into a predetermined shape using the machining control power source (1 day) and the NC control device. is being done.

Next, in Figure 11, ``Company'' is a voltmeter between electrodes, 翺 is a servo voltmeter, 翰 is a machining state detection device, (a) is an abnormal machining control program, country is a machining current control device, and □□□ is an abnormality. The machining avoidance device controls the abnormal machining control program (a) of the NC control device (2) based on signals from the machining voltage meter and the machining state detection device, and this control program controls the machining current control device (2). ) to further control the workpiece (1B
) and machining electrode α4) to maintain appropriate machining currents.

Next, FIGS. 12 to 14 show the occurrence points of unstable electrical discharge machining states due to input of unstable signals from the machining state detection device (A) from stable electrical discharge machining states during predetermined electrical discharge machining.
This is an operation explanatory diagram showing the process of limiting the machining current from 'Po' to avoid unstable machining and gradually returning to a stable electrical discharge machining state. Figure 12 shows the process by which the unstable machining state is smoothly avoided. Fig. 13 shows the process in which the unstable machining state temporarily traverses during the step-by-step recovery, and furthermore, Fig.
FIG. 4 shows a process in which an unstable signal causes an avoidance operation to be performed again during the stepwise return.

The conventional electric discharge machining apparatus is configured as described above, and the machining electrode α4) facing the workpiece (16) with a predetermined gap in the machining bath 0 is connected to the machining control power source (1 day), The workpiece is electrically discharge-machined into a predetermined shape using a predetermined electrical discharge machining medium set by the NCfJIJ control equipment, but if the predetermined electrical discharge machining medium set as described above is inappropriate, etc. In this case, the discharge phenomenon becomes unstable and an abnormal machining state occurs.

If this abnormal electric discharge machining condition continues as it is,
A continuous arc state occurs, which not only damages the workpiece (16) or the processing electrode Q4) and makes it easy to produce defective products, but also this continuous arc state has the risk of causing a fire due to overheating. As one of the means to prevent abnormal electrical discharge machining,
- However, there is a method to avoid unstable electrical discharge machining.

That is, during electrical discharge machining, the values of the gap voltage meter □□□ and the servo snow pressure meter are judged by the machining state detection device (to),
When an unstable machining state occurs, a predetermined signal is sent to the control program (a) to reduce the amount of current supplied to the machining current control device to avoid unstable electrical discharge machining. An abnormal machining avoidance device (support) consisting of a control device (7), a machining state detection device □□□, and a control program (a) is built into the NC control device together with a machining control power source (18).

Note that FIG. 12, which is an explanatory diagram of the abnormal machining avoidance operation, shows that an unstable machining state is generated from a point "Po" due to the input of an unstable signal from the machining state detection device (3) from a stable electrical discharge machining state, and The machining condition and condition detection device (a) allows
An abnormality signal is transmitted, and a command to reduce the electric discharge machining current is input from the control program (to) to the machining current control device (2), whereby the machining current is reduced by a predetermined amount to avoid abnormal machining, but this avoidance operation continues until the abnormal machining resolution detection signal is sent from the machining state detection device (5). Then, when "P" is reached and an abnormality elimination signal is sent, the machining current value is returned to the original machining current value in stages from "P2" to "P5", and the normal stable electrical discharge machining state is returned.

Furthermore, Fig. 13 and Fig. 14 show the process of gradually returning to the original stable electrical discharge machining state after the avoidance operation shown in Fig. 12 mentioned above, and Fig. 13 shows the gradual recovery of electrical discharge machining. Figure 14 shows the process in which when the stage β of the "P4" point is reached, the state temporarily becomes unstable, and the transition to the next stage is extended. In the process of recovering to the machining state, an unstable electrical discharge machining state occurs at the stage of point "P," and abnormal electrical discharge machining that has worsened is detected and the process shifts to avoidance operation again. In both cases, abnormal machining is avoided. This is to maintain stability of electrical discharge machining.

[Problem that the invention seeks to solve]

As mentioned above, the abnormal machining avoidance device in conventional electrical discharge machining equipment is configured to perform an avoidance operation when abnormal electrical discharge machining occurs, and then return to the original electrical discharge machining medium (supplied electricity amount). Because it is configured as
In the case of temporary abnormal electrical discharge machining, it is possible to take action to avoid this, but if abnormal electrical discharge machining occurs frequently or if the abnormal electrical discharge machining progresses further, this problem will occur!
Not only is the third operation difficult, but the electric discharge machining is performed using a supplied electric power that exceeds the appropriate current value at the time of occurrence of abnormal electric discharge machining, which inevitably leads to problems such as an increase in abnormal electric discharge machining.

This invention has been made with attention to this point, and it is possible to accurately detect a precursor phenomenon of abnormal electrical discharge machining, and to select a machining current suitable for stable electrical discharge machining based on the detected value. The present invention provides an electric discharge machining apparatus that continuously maintains the following during stable electric discharge machining.

[Means for Solving the Problems] The electric discharge machining apparatus according to the present invention includes a machining current control device, a machining state detection device, and a control program that constitute a conventional abnormal machining avoidance device, as well as a control program for detecting abnormal machining avoidance frequency. This is a device in which a device and a device for detecting the duration of stable machining fi$' are added.

[Effect]

The abnormal machining avoidance device according to the electric discharge machining apparatus of the present invention includes:
The abnormal machining avoidance frequency detection device and the stable machining continuation time detection bag J are used to detect precursor phenomena of abnormal machining, and the machining current controller supplies a machining current suitable for the current machining. Not only can you obtain stable electrical discharge machining that corresponds to the situation, but also the pause time that determines the current value supplied to electrical discharge machining can be set automatically, so the electrical discharge machining medium that has been set at the start of electrical discharge machining can be set automatically. (
After the rest time of Ip (peak current) is expanded stepwise from the minimum current value, it is possible to shift to the current control described above.

(Embodiment of the Invention) FIGS. 1 to 9 show an embodiment of the present invention, and FIG. 1 shows a block diagram of an abnormal machining avoidance device according to the present invention.
Figures 2 to 7 are explanatory diagrams of abnormal machining avoidance operations, Figure 8 is a control program flowchart of the machining current control device, and Figure 9 is a control program flowchart of the machining current control device.
The figure is a control program flowchart of the abnormal machining avoidance device. First, the abnormal machining avoidance device (320) shown in Fig. 1
, ■ is a gap voltmeter, and its value is detected by the machining state detection device (A) to detect an abnormality in electrical discharge machining, and the value is detected by the NC control device shown in the schematic configuration diagram of a general electrical discharge machining device in Fig. 10. Through the abnormal machining control program (incorporated), the machining current control device controls the electrical discharge machining current to perform abnormal machining avoidance operations. Then, the machining status is monitored by the abnormal machining avoidance frequency detection device (31) that detects the frequency of the abnormal machining avoidance operation and the machining current during the avoidance operation, thereby determining the progress status of the abnormal electric discharge machining. The machining current control device ((1)) limits the machining current corresponding to the level.In other words, the frequency of the above-mentioned abnormal machining avoidance operation and the stable machining continuation time are determined by the stable machining continuation time detection device. The progress of abnormal machining is determined by monitoring the level, and the machining current is limited by the machining current control device (machining) in accordance with the level.

Therefore, for the reasons mentioned above, the machining start current of each machining medium is determined by the machining current control device (the IP peak current of each machining medium according to (1)) based on a command from an external signal (the operator sets the medium before electric discharge machining). electrical discharge machining is performed at the minimum current value (output notch) of that Ip, and the machining current is increased within a range where a stable machining state can be maintained.

Next, Fig. 2 shows the machining start state for each Ip (peak current) specified at each stage of electric discharge machining, and electric discharge machining is started at the minimum current value (output notch) of the specified Ip. Unless the abnormal machining avoidance signal described above is sent, the machining current is increased in stages (the output notch is changed) to maintain stable electric discharge machining.

Next, FIG. 3 shows a state in which the machining current increases until the frequency of avoiding abnormal machining reaches a certain level.

Next, FIGS. 4 to 7 are operation explanations showing states in which the abnormal machining avoidance and recovery states explained using the operation explanatory diagrams of FIGS. 12 to 14 are monitored by the abnormal machining avoidance frequency detection device 0υ. In the figure, "A cycle" in Figure 4
From the stable machining state, "B cycle" and "C cycle"
The amount of recovery to the maximum machining current and the cycle time of one cycle during stable electrical discharge machining are monitored to determine if the state cannot be recovered to the stable machining state. The maximum stable machining current during pre-machining is limited by the machining current control device (1) to the amount that can be sold continuously for stable machining, thereby making it possible to maintain a stable machining state.

Next, the above-mentioned abnormal machining avoidance/return stable machining state is monitored by the stable machining continuation time detection device (to), and from the stable machining state of "A cycle" to "B cycle" shown in FIG. The short-term stable machining state of "C cycle" is compared by the duration of stable machining, and the next abnormal machining avoidance signal from the abnormal machining avoidance signal is regarded as one cycle, and the frequency of the unit time is determined to be below the set level (duration time ) or more (number of avoidances), and as shown in Fig. 7, the maximum stable machining current (switching notch) during pre-machining is reduced and limited by the machining current control device ((4) to a point where stable machining can be continued. This enables stable machining.

Next, FIG. 8 shows a flowchart for automatically controlling the machining current in the electric discharge machining apparatus according to the present invention. , pulse width (ON TI~(E
) notch and when the machining medium for each machining stage is commanded, electrical discharge machining is started with the minimum machining current value (output notch) of the commanded Ip, and the maximum machining current value that is possible for stable machining is set. This figure shows each step in which automatic switching is performed step by step up to (output notch) and stable machining is continued.

Next, FIG. 9 shows the above-mentioned abnormal machining avoidance frequency detection device (3
1) and the detection contents of the abnormal machining opening a operation by the stable machining continuation time detection device (to). When the signal is transmitted, the frequency of abnormal machining is checked by counting the signal, and the machining current is controlled by detecting whether the machining current has returned to the machining current value during the previous stable machining. When guiding machining to the stable machining side, the continuation time of stable machining is detected, the continuation time below a certain level is counted, and the machining current is controlled according to the frequency and frequency of abnormal machining avoidance at that time. This figure shows each step of the process.

In short, the electric discharge machining apparatus of the present invention adds an abnormal machining avoidance frequency detection device 0υ to the conventional apparatus, and performs machining recovery stages as shown in the "B cycle" and "C cycle" shown in the operation explanatory diagram of FIG. During the process, an abnormal machining signal is transmitted before the machining current value reaches a certain stable machining current value (it may be a switching notch that can output that current value), and the process shifts to the abnormal machining avoidance operation. The frequency of sending abnormal machining signals increases without reaching the machining current of the machining state,
Count the number of abnormal machining avoidance operations without reaching the machining current value during stable machining, and when it reaches the unit time level or higher, the machining current $ + J In addition, this invention adds a stable machining duration detection device (to) to the conventional device to perform the "B cycle" and "C cycle" shown in the operation explanatory diagram of FIG. After the abnormal machining avoidance operation, check the machining current level (stable machining current value or output notch) as shown in the flowchart in Figure 9.
If the continuous machining time is below a certain level due to the current value or output notch, one
No. 8 is transmitted, the number of signals is measured at the unit time level, and if the number of signals is greater than the set value, the machining current control device (
1), the amount of current supplied is reduced and limited, and even when the number of cycles is counted and exceeds the unit time level, the amount of current supplied is reduced and limited to continue stable electrical discharge machining. I'm in the middle of the day.

In addition, in the operation explanatory diagram of Figure %7 mentioned above, the amount of supplied current is reduced and limited, and stable machining is 1! In particular, this invention is designed to detect abnormal machining at an early stage in order to maintain stable electrical discharge machining for a long time. Machining that corresponds to stable electrical discharge machining? Since the lI flow can be automatically determined, the machining medium can be set to match the Ip (peak current) and pulse width (θN-TIME) to the machining status of each stage, thereby achieving the minimum machining of Ip at each stage. Electric discharge machining is started from the current, and stable machining is achieved at that Ip71
It becomes possible to perform stable electrical discharge machining by increasing the current value (output notch) in stages up to the current value.

[Effects of the Invention] As described above, according to the present invention, stable machining continuation time detection iA positioning is added to the conventional abnormal machining avoidance device (support), thereby achieving 1! When the duration time decreases and the frequency of abnormal machining avoidance operations, the amount of machining supply current is reduced and limited via the machining current control device (1) to prevent abnormal electrical discharge machining caused by excessive current supply, There is an effect that continuous stable electrical discharge machining can be continued without returning to the borrowed power supply amount range of 7n where abnormal machining occurs, and by increasing the profit to the stable machining possible range. Further, according to the present invention, an abnormal machining avoidance frequency detection device 00 is added to the conventional abnormal machining avoidance device (support) to reduce and limit the amount of current supplied by the machining current control device. Not only can abnormal electrical discharge machining due to the supplied current be prevented, but also the current value at which abnormal machining occurs can be restored at the time of machining recovery. ,
Another effect is that stable electrical discharge machining can be continued continuously. Furthermore, according to the present invention, since stable electrical discharge machining can be made to function for each designated Ip, each of the above-mentioned Ip
At the same time as the machining of each Ip starts, the machining current value (OFF-74ME) is processed using the minimum current value (output notch) of each IP, and the machining current value (output Since the maximum machining speed of stable electric discharge machining of 1 p each can be obtained, the setting of the electric discharge machining attachment is greatly improved, and it greatly contributes to the automation of electric discharge machining.

[Brief explanation of the drawing]

FIGS. 1 to 9 are diagrams of one embodiment of the present invention, FIGS. 2 to 7 are illustrations of U-normal machining avoidance operation, and FIG. 8 is a control program flowchart of the machining current control device. FIG. 9 is a control program flowchart of the abnormal machining avoidance device. Figures 10 to 14 show the conventional electrical discharge machining equipment Δ for this f-mount, where Figure 10 is a schematic configuration diagram of a general electrical discharge machining installation, and Figure 11 is a conventional abnormal machining cycle: u! The block diagram of A5 and FIGS. 12 to 14 are explanatory diagrams of the abnormal machining avoidance operation. In the figure, n is a voltmeter between poles, (to) is a servo voltmeter,
Kan is a machining state detection device, the country is an abnormal machining control program,
(4) is a control device in the processing room, 0υ is an abnormal machining avoidance frequency detection device, Kuni is a stable machining continuation time detection device, and (320) is an abnormal machining avoidance device. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Patent Attorney Tadashi Sato Year 7 Figure 26 - Power a Engineering a' Asahi W: &'J2i28:
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Claims (5)

[Claims] (1) An abnormal machining avoidance device consisting of a machining state detection device that detects an electric discharge phenomenon between a machining electrode and a workpiece, an abnormal machining control program, and a machining current control device, and an abnormal machining avoidance frequency detection device. An electric discharge machining apparatus characterized in that a stable machining continuation time detection device is added, and the upper limit of the machining current output from the machining current control device is controlled by signals from both of the additional devices. (2) The abnormal machining avoidance frequency detection device is configured to determine when the number of abnormal machining operations occurring within a certain period of time has reached a certain frequency. Electrical discharge machining equipment. (3) The above-mentioned stable machining continuation time detection device detects the time to maintain stable machining, transmits a signal when a certain maintenance time is reached, and determines the stable state of machining based on the frequency of the transmission. An electric discharge machining apparatus according to claim 1. (4) The machining current control device limits the decrease in the maximum machining current based on the signals from the stable machining continuation time detection device and the abnormal machining avoidance frequency detection device. Electrical discharge machining equipment. (5) The machining current control device advances step by step to the maximum machining current of the specified peak current and continues machining unless a signal is sent from the abnormal machining avoidance frequency detection device and the stable machining continuation time detection device at the beginning of machining. An electric discharge machining apparatus according to claim 1 or 4, characterized in that the electric discharge machining apparatus is used for: