JPH10202433A - Electric discharge machining control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid an unnecessary increase in machining time by keeping a machining condition unchanged, when an index to measure machining stability simply gives an unstable status temporarily, regarding an electric discharge machining control device. SOLUTION: A machining stability memory part 12 sequentially stores machining stability values about a plurality of zones. In addition, a machining stability maximum value selection part 13 selects the largest value from a plurality of stored machining stability values and, then, extracts the value as a representative value. Furthermore, a machining condition determination part 8 decides an instruction value about a machining condition to be outputted on the basis of the extracted representative value of the machining stability and an execution machining condition stored in an execution machining condition buffer 5 at the time of the extraction of the representative value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining control device for controlling an electric discharge machine.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing an example of the configuration of a conventional electric discharge machining control device. A conventional electric discharge machining control device includes a CPU 1 for performing overall control, a machining program storage unit 2 for storing machining programs, a machining program interpreting unit 3 for interpreting machining programs, and machining conditions for storing data such as machining conditions. Record storage unit 4 and execution processing condition buffer 5 for temporarily storing the processing conditions being executed
A processing state monitoring unit 6 for monitoring the processing state; a processing state determination unit 7 for determining the quality of the processing state at each time point to determine the processing stability; and determining and outputting the processing conditions based on the processing stability. A machining condition determining unit 8, a machine control unit 9 for controlling the movement of the axis, etc., and a machining power control unit 10 for controlling a machining power supply
And a user interface 11 including a data input unit and a display device for a user to directly input processing conditions and the like.

A conventional electric discharge machining control device detects an index for measuring machining stability, such as a discharge voltage, a discharge current, the number of short-circuit pulses, or the like at a certain point in time, at regular intervals, and based on the machining stability calculated from them. Determine the command value of the processing condition to be output. For example, if the amplitude of the discharge voltage is large, the discharge voltage is low, the discharge current is too large, or the ratio of the number of short-circuit pulses to the total number of pulses (short-circuit rate) increases, the machining stability will increase. The degree is determined to be low, and in the opposite case, the processing stability is determined to be high.

[0004] The processing state monitoring unit 6 monitors factors for determining the quality of the processing state, such as the short-circuit rate, the average voltage amplitude, and the movement of the shaft. The processing state determination unit 7 includes a processing state monitoring unit 6
Judge the quality of the machining state based on the data collected by, and determine the machining stability. The processing condition determination unit 8 outputs processing conditions such as a pause time and a jump distance from the processing stability determined by the processing state determination unit 7 and the execution processing conditions at that time stored in the execution processing condition buffer 5. Is determined. The machine control unit 9 and the machining power control unit 10 control the movement of the axis and the machining power according to the command value of the output machining condition.

[0005] Here, as an example, a case will be described in which the processing stability is determined based on the magnitude of the short-circuit rate and the pause time is changed. The correspondence between the short-circuit rate and the processing stability is determined as shown in FIG. 7, and an increase / decrease command value of the pause time as shown in FIG. 8 is issued according to the processing stability. However, the pause time finally output as the command value of the processing condition is MAX (CT
R + STR, RTR). this house,
CTR, STR, and RTR are a current pause time, a pause time increase / decrease command value, and a pause time reference value, respectively.
MAX (A, B) indicates that the larger one of A and B is selected.

For example, when the reference value RTR of the pause time is 30
(Notch), and consider the case where processing is started from this value. If the machining stability of the first section is 100,
Since the current pause time CTR is 30 (notch), and the pause time increase / decrease command value STR is -5 (notch) from FIG. 8, MAX (30-5, 30) is 30, and the pause time is 30. (Notch). Assuming that the machining stability in the next section is 70, the current pause time CTR
Is 30 (notch), and since the increase / decrease command value STR of the pause time is +10 (notch) from FIG.
+10, 30) becomes 40, and the downtime increases to 40 (notch). Thereafter, assuming that the machining stability continuously changes as shown in FIG. 9, the pause time finally output as the command value of the machining condition changes as shown in FIG.

[0007]

In the case where the machining stability is determined to be low in electric discharge machining, machining is unstable due to accumulation of machining debris between the electrode and the workpiece as shown in FIG. When the processing conditions need to be changed immediately, or when the index for measuring the processing stability becomes unstable due to, for example, the processing dust being accidentally caught in the gap between the electrode side surfaces as shown in FIG. In some cases, the same situation as described above may be temporarily indicated.
In the latter case, even if the index shows the same situation as when unstable machining was performed in a certain section, the next section immediately returns to a stable machining state, so there is no need to change the machining conditions. Absent. However, with the conventional EDM control system, if the index indicates an unstable state of machining, it is not possible to determine whether this is temporary or steady, so the machining conditions must be adjusted so that machining is stable. change. Here, "change the processing conditions so as to achieve stable processing" means, for example, to increase the pause time, increase the interval between the electrode and the workpiece, or increase the jump distance. Therefore, no matter which processing condition is changed, it is inevitable that the processing time becomes longer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method in which an index for measuring the processing stability only temporarily indicates an unstable state of processing. An object of the present invention is to provide an electric discharge machining control device which can prevent an unnecessary increase in machining time by preventing a command value of a machining condition from being changed.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an electric discharge machining control apparatus for controlling an electric discharge machine by determining a machining condition to be instructed in accordance with a detected machining state. Means for sequentially storing the processing stability for a plurality of sections, means for extracting a representative value of the processing stability by selecting or calculating from the stored plurality of processing stability,
Means for obtaining a command value of a processing condition using a representative value of the processing stability obtained by extraction. Further, the object of the present invention is to select a highest value from among the stored plurality of machining stability as a means for selecting or calculating a representative value of the machining stability from the plurality of stored machining stability. Or at least one of a means for calculating an average value of a plurality of stored machining stability values, or a means for calculating a value having a highest frequency of appearance in a frequency distribution of the stored plurality of machining stability values. Achieved effectively.

[0010]

FIG. 4 is a flowchart showing the flow of processing by the electric discharge machining control device of the present invention. The electric discharge machining control device of the present invention detects a machining state, calculates and stores machining stability (step S1), and determines whether or not the number of stored machining stability has reached a predetermined number (step S2). If a predetermined number is reached, a representative value of the machining stability is extracted from the stored plurality of machining stability by selection or calculation (step S3), and machining is performed using the extracted representative value of the machining stability. The command value of the condition is determined (step S4). If the number of machining stability stored in step S2 has not reached the predetermined number, step S1 is repeated until the number reaches the predetermined number.

FIG. 1 shows a first embodiment of an electric discharge machining control apparatus according to the present invention.
FIG. 3 is a block diagram illustrating a configuration example of FIG. The same components as those of the conventional electric discharge machining control device are denoted by the same reference numerals, and description thereof is omitted. The first configuration example of the electric discharge machining control device of the present invention includes a machining stability storage unit 12 that stores machining stability for a plurality of sections, and a highest value among the stored machining stability. A machining stability maximum value selecting unit 13 for selecting and extracting as a representative value.

Next, a specific operation of the first configuration example of the present invention will be described. As in the description of the conventional device example,
It is assumed that the pause time is a command value of the machining condition that changes, and the correspondence between the machining stability and the command value of increase / decrease of the pause time is determined as shown in FIG. 8, and the pause that is finally output as the command value of the machining condition is determined. Time is MAX (CTR + STR, RTR)
Is determined in accordance with Also, the number of machining stability to be stored is 3, and the reference value RTR of the downtime is 30 (notch).
It is assumed that the processing stability changes as shown in FIG.
First, the processing stability storage unit 12 stores the processing stability 100 of the first section. Further, the processing stability storage unit 12 stores the processing stability 7 in the next section until the predetermined storage number 3 is reached.
0, the machining stability 100 of the next section is sequentially stored. When the processing stability storage unit 12 stores the processing stability for three sections, the processing stability maximum value selection unit 13 sets the highest value 100 from the stored processing stability (100, 70, 100). Select and extract as representative value. The processing condition determination unit 8 determines a command value of the processing condition to be output based on the extracted representative value of the processing stability and the currently-executed processing condition stored in the execution processing condition buffer 5. From FIG. 8, the increase / decrease command value STR of the pause time corresponding to the representative value 100 of the machining stability is −5 (notch).
The pause time is determined by MAX (30-5, 30) and remains at 30 (notch).

Subsequently, the machining stability storage unit 12 clears the machining stability for the three sections stored so far, and stores the machining stability for the next three sections again. Here, the stored machining stability for three sections is (90, 90, 60).
And the highest machining stability value selection unit 13 selects the highest value 90 from among them and extracts it as a representative value. From FIG. 8, 0 (notch) is obtained as the increase / decrease command value STR of the pause time corresponding to the representative value 90 of the machining stability. Therefore, the pause time is obtained by MAX (30 + 0, 30), and 3 is returned again.
It remains at 0 (notch). The transition after the pause time finally output as the command value of the processing condition is as shown in FIG.

FIG. 2 shows a second embodiment of the electric discharge machining controller according to the present invention.
FIG. 3 is a block diagram illustrating a configuration example of FIG. The second configuration example includes a processing stability storage unit 12 and a processing stability average value calculation unit 14 that calculates an average value of a plurality of stored processing stability values and extracts the average value as a representative value. Similarly to the description of the first configuration example, the number of machining stability to be stored is 3, and the machining stability storage unit 12 stores the machining stability (100, 70, 100). Since the processing stability average value calculating unit 14 calculates the stored processing stability average value 90 and extracts it as a representative value, the pause time increase / decrease command value STR corresponding to this value 90 is 0 (notch) from FIG. ), And the pause time is MAX
Calculated by (30 + 0,30), 30 (notch)
Will remain. Subsequently, similarly to the first configuration example, the machining stability storage unit 12 clears the stored machining stability for the three sections, and renews the machining stability for the next three sections (9).
0, 90, 60). The processing stability average value calculation unit 14 calculates the processing stability average value 80 stored again.
Is calculated and extracted as a representative value.
The pause time increase / decrease command value STR corresponding to 0 is +10 (notch), and the pause time obtained by MAX (30 + 10, 30) is 40 (notch). The transition after the pause time finally output as the command value of the processing condition is as shown in FIG.

FIG. 3 shows a third embodiment of the electric discharge machining controller according to the present invention.
FIG. 3 is a block diagram illustrating a configuration example of FIG. In the third configuration example, a processing stability storage unit 12 and a processing stability mode value calculating unit 15 that determines a value having the highest frequency of appearance in a plurality of stored frequency distributions of the processing stability and extracts the value as a representative value. And Similarly to the description of the first and second configuration examples, the number of machining stability to be stored is 3, and the machining stability storage unit 12
It is assumed that the machining stability (100, 70, 100) for three sections is stored according to the transition of the machining stability shown in FIG. Since the processing stability mode value calculation unit 15 obtains the value 100 having the highest appearance frequency in the stored frequency distribution of the processing stability and extracts it as a representative value, the increase or decrease of the pause time corresponding to this value 100 is shown in FIG. The command value STR becomes -5 (notch),
Since MAX (30-5, 30) is determined to be 30, the pause time remains at 30 (notch). Subsequently, similarly to the first and second configuration examples, the processing stability storage unit 12 clears the stored processing stability for the three sections, and renews the processing stability (for the next three sections). 90, 90, 60) are stored. Since the processing stability mode value calculating unit 15 finds the value 90 having the highest appearance frequency in the frequency distribution of the processing stability stored again and extracts it as a representative value, the pause time corresponding to the value 90 from FIG. Increase / decrease command value STR is 0
(Notch), and the pause time obtained by MAX (30 + 0, 30) remains at 30 (notch). The transition after the pause time finally output as the command value of the processing condition is as shown in FIG. 5, and in this example, the same result as in the first configuration example is obtained. In addition, in preparation for the case where the most frequently occurring machining stability cannot be identified as one, a secondary representative value extraction method such as selecting the highest value or using an average value may be determined in advance.

As can be seen by comparing FIGS. 5 and 6 with FIG. 11, the first, second, and second embodiments of the electric discharge machining control device of the present invention are shown.
In each of the third and third configuration examples, the output pause time changes with a value smaller than that of the conventional electric discharge machining control device. As a result, when it is not necessary to change the machining conditions immediately, the machining time is shorter than that of the conventional electric discharge machining control device, which is advantageous. Further, when the machining condition needs to be changed, all of the stored machining stability values become low values. Therefore, even in the electric discharge machining control device of the present invention, a command value for changing the machining condition is output, and the Damage to the workpiece due to electric discharge or the like can be prevented. In this way, in the electric discharge machining control device of the present invention, it is possible to change machining conditions only when necessary.

In the description given above, after a predetermined number (for three sections) of machining stability is stored and a command value of the machining condition is output, all of the stored machining stability are cleared. However, the command value of the processing condition may be determined by clearing from the storage unit for a certain section and storing the new processing stability only for the cleared section, together with the uncleared section. Further, in the above description, a simple example is used for the inference method for obtaining the command value of the processing stability and the processing condition for easy understanding, but there is no limitation on the method used for the inference.

[0018]

As described above, according to the electric discharge machining control apparatus of the present invention, when the index for measuring the machining stability only indicates the unstable state of machining temporarily, the machining condition must be changed. Since it is not performed, an unnecessary increase in the processing time can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first configuration example of an electric discharge machining control device according to the present invention.

FIG. 2 is a block diagram showing a second configuration example of the electric discharge machining control device of the present invention.

FIG. 3 is a block diagram showing a third configuration example of the electric discharge machining control device of the present invention.

FIG. 4 is a flowchart showing a flow of processing by the electric discharge machining control device of the present invention.

FIG. 5 is a diagram showing a transition of a pause time output as a command value of a machining condition by the first and third configuration examples of the electric discharge machining control device of the present invention.

FIG. 6 is a diagram showing a transition of a pause time outputted as a command value of a machining condition by a second configuration example of the electric discharge machining control device of the present invention.

FIG. 7 is a diagram illustrating an example of a correspondence relationship between a short-circuit rate and processing stability.

FIG. 8 is a diagram illustrating an example of a correspondence relationship between a machining stability and an increase / decrease command value of a pause time.

FIG. 9 is a diagram illustrating an example of a state of transition of the processing stability.

FIG. 10 is a block diagram showing an example of a conventional electric discharge machining control device.

FIG. 11 is a diagram showing a transition of a pause time outputted as a command value of a machining condition by a conventional electric discharge machining control device.

FIG. 12 is a diagram showing an example of a state in which machining waste is deposited between an electrode and a workpiece in the sinking electrical discharge machining.

FIG. 13 is a diagram showing an example of a state where machining waste is sandwiched in a gap on a side surface of an electrode in the sinking electric discharge machining.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Processing program storage part 3 Processing program interpretation part 4 Processing condition record storage part 5 Execution processing condition buffer 6 Processing state monitoring part 7 Processing state judgment part 8 Processing condition determination part 9 Machine control part 10 Processing power control part 11 User interface 12 Machining stability storage unit 13 Machining stability maximum value selecting unit 14 Machining stability average value computing unit 15 Machining stability mode value computing unit

Claims (2)

[Claims] 1. An electric discharge machining control device for controlling an electric discharge machine by determining a machining condition to be instructed in accordance with a detected machining state, means for sequentially storing machining stability for a plurality of sections, Means for extracting a representative value of the processing stability by selection or calculation from the processing stability, and means for obtaining a command value of the processing condition using the representative value of the processing stability obtained by extraction. EDM control device. 2. A means for selecting the highest value from among the stored plurality of machining stability, as means for selecting or calculating a representative value of the machining stability from the stored plurality of machining stability, or storing 2. The apparatus according to claim 1, further comprising at least one of a unit for calculating an average value of the plurality of processing stability values, and a unit for calculating a value having the highest frequency of appearance in the frequency distribution of the stored processing stability values.
An electrical discharge machining control device according to claim 1.