JP2998486B2 - Electric discharge machine - Google Patents

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 apparatus, and more particularly, to performing an electric discharge machining, a more accurate estimated machining time can be calculated, and when the machining condition is inappropriate, the machining condition is changed. The present invention relates to an electric discharge machining apparatus capable of predicting and displaying the processing time and, when the processing speed is significantly reduced during processing, changing the processing conditions and calculating and displaying the predicted processing time.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the basic structure of a conventional electric discharge machine. FIG. 5 is a schematic configuration diagram showing a basic configuration of a conventional electric discharge machining apparatus. In FIG. 5, reference numeral 1 denotes an electrode for electric discharge machining, 2 denotes an object to be processed, 3 denotes a power supply which is a pulse current generator for supplying a pulse current for electric discharge, 4
Is a spindle which is a head of an electric discharge machine, 5 is a machining fluid which is an insulating oil, 6 is a numerical controller (NC device) for appropriately controlling the movement of the spindle 4, and 7 is a machining tank in which the machining fluid 5 is stored. is there.

[0003] A conventional electric discharge machining apparatus is configured as described above, and performs electric discharge machining on a workpiece 2 using an electrode 1. The electrode 1 and the workpiece 2 are opposed to each other while being immersed in the processing liquid 5 in the processing tank 7, and a predetermined pulse current is supplied from the power supply 3 to the electrode 1 and the workpiece 2. Due to this energization, an intermittent discharge occurs in the machining gap between the electrode 1 and the workpiece 2, and the workpiece 2 is subjected to machining by the discharge.

[0004] Conventionally, it has been difficult to predict the machining time of electric discharge machining, and many have relied on the intuition and experience of the machining operator. this is,
This is because the state between the electrode 1 and the workpiece 2, which is a workpiece, changes as the processing progresses and is not constant. As one of the reasons, it is conceivable that the processing waste which stagnates between the electrode 1 and the workpiece 2 which is the workpiece. According to an experiment performed by the inventors, when the discharge state is good under a single processing condition, the processing speed is substantially constant.

FIG. 6 is a table showing the variation of the processing speed when processing is performed a plurality of times under the same processing conditions. Here, the processing speed is a processing amount per unit time. Further, a good discharge state means that (1) generation of discharge, (2) ionization, (3) evaporation / melting, and (4) generation of impact pressure between the workpiece 2 and the electrode 1. A state in which a series of phenomena, such as removal of a scattered molten portion and (5) formation of discharge traces and return of a machining fluid, occur smoothly and continuously. If the processing speed is constant as described above, the processing time can be predicted by dividing the total processing amount by the processing speed. Many conventional methods for calculating the expected machining time are performed in this manner. But,
In actual machining, not only when the machining speed is constant as described above, but also depending on the machining content, the machining speed greatly changes as the machining progresses.

One example is a simple shape (the bottom is 10 m).
FIG. 7 shows the dependence of the processing speed on the processing depth when processing is performed using an electrode having a square prism having a square shape of m. FIG. 7 is a characteristic diagram showing the dependence of the processing speed on the processing depth when processing is performed with a simple shape electrode, in which a change in the processing speed when processing is performed under a single condition is plotted for each processing depth. is there. As shown in the figure, a large change is seen in the processing speed even when the electrode shape is simple. When the shape of the electrode is complicated, machining chips tend to stagnate between the electrode 1 and the workpiece 2, and furthermore, it is a common experience that the machining speed changes greatly. However, the error in the prediction result becomes very large. In order to improve this, conventionally, there is a case where an empirically known correction coefficient is used for the purpose of calculating an estimated machining time closer to the actual machining time. This is intended to correct the machining speed by multiplying the machining speed when the discharge state is good by the correction coefficient, and in many cases, multiply the estimated machining time by a single correction coefficient.

FIG. 8 shows the relationship between the processing time and the processing depth when a certain processing is performed. FIG. 8 is a characteristic diagram showing the relationship between the machining depth and the machining time in an ideal state, when a correction coefficient is used, and in actual machining. As shown in the drawing, in actual machining, the machining speed decreases with depth, and the slope of the graph gradually decreases. On the other hand, when the processing depth is shallow, the processing state is very stable, the inclination of the graph is large, and the graph in the ideal state is an extension of this. Here, considering the case where the correction coefficient is set to 0.7, as can be seen from FIG. 8, when the machining depth is 30 mm, the expected machining time accurately matches the actual machining time. However, when the machining depth changes, the difference between the expected machining time and the actual machining time increases.

[0008]

In a conventional EDM apparatus using a single correction coefficient as described above, when the machining speed greatly changes depending on the machining depth, the expected machining depth is reduced. However, there was a problem that it was not possible to cope if they were different.

Further, as shown in FIG. 7, when the working becomes unstable as the working depth increases, it is necessary to change the working conditions during the working. In such a case, there is a problem that the difference between the estimated machining time and the actual machining time is further increased unless the change in the machining condition is taken into account when calculating the estimated machining time.

Therefore, the present invention can calculate a more accurate estimated machining time, change the machining condition to an appropriate machining condition when the machining condition is inappropriate, correctly estimate the machining time at that time, and perform machining while machining is in progress. It is an object of the present invention to provide an electric discharge machining apparatus capable of appropriately changing machining conditions and accurately calculating an estimated machining time even when the speed is significantly reduced.

[0011]

According to a first aspect of the present invention, there is provided an electric discharge machining apparatus which changes in accordance with an input section for inputting a plurality of machining contents and machining conditions, and a machining speed and machining contents for each machining condition. A storage unit for storing a change in the processing speed, and a change in the processing speed when processing is performed based on the processing content and processing conditions input to the input unit, sequentially predicting the change in the processing speed based on the content of the storage unit, and correcting the processing speed. And an operation unit for calculating the expected processing time, and a display unit for displaying the expected processing time.

The electric discharge machining apparatus according to the second aspect of the present invention
An input unit into which a plurality of processing contents and processing conditions are input, a storage unit that stores a processing speed for each processing condition and a change in processing speed that changes according to the processing contents, and a processing condition input to the input unit. If inappropriate in light of the contents of the storage unit,
An arithmetic unit for calculating an expected machining time when machining is performed under the changed machining conditions by changing the machining conditions, and a display unit for displaying the estimated machining time.

According to a third aspect of the present invention, there is provided an electric discharge machine,
An input unit for inputting a plurality of processing contents and processing conditions; a storage unit for storing a processing speed for each processing condition and a change in processing speed that changes according to the processing contents; A monitoring unit that monitors, if the processing speed is significantly reduced during the processing by the detection unit, a change unit that changes the processing condition; and a calculation unit that calculates an expected processing time after the processing time is changed, A display unit for displaying the estimated processing time.

[0014]

In the electric discharge machine according to the first aspect of the present invention, the processing contents, the processing type, and the processing conditions desired by the processor are input to the input section. The basic machining speed of the input machining condition is stored in the storage unit in advance, and the change of the machining speed in the machining content and the machining type used in the machining condition,
And the method of correction thereof are also stored. And
The calculation unit performs the correction calculation of the processing speed, calculates an expected processing time based on the calculated series of processing speeds, and displays it on the display unit, so that even when the processing speed is not constant, , Accurate machining time can be predicted.

In the electric discharge machining apparatus according to the second aspect of the present invention, if the machining condition input to the input unit is inappropriate in light of the contents of the storage unit, the machining condition is changed and the changed machining condition is changed. It calculates the expected machining time when machining with and displays the expected machining time on the display unit.If there is a more appropriate condition in the storage unit than the input machining condition,
The processing conditions are changed to appropriate processing conditions, and an accurate processing time based on the changed processing conditions can be predicted.

In the electric discharge machining apparatus according to the third aspect of the present invention, the change in the machining speed during the machining is sequentially monitored by the detecting unit. While changing the processing conditions,
The calculation unit calculates the expected machining time after the machining time change,
Since the expected processing time is displayed on the display unit, when the processing speed is significantly reduced during the processing, the processing conditions are automatically changed, and the processing speed equal to or higher than a predetermined value is maintained.

[0017]

Embodiments of the present invention will be described below.
FIG. 1 is a block diagram showing the overall configuration of an electric discharge machine according to one embodiment of the present invention. In the figure, 8 is an input unit such as a keyboard for inputting processing conditions (set current value, discharge time, pause time, etc.) and processing details (electrode area, processing depth, etc.), and 9 is a basic processing speed under each processing condition. And a storage unit that stores a change in processing speed for each processing content, and for each processing content,
The relationship between the processing time and the processing depth obtained by the experiment is stored in the form of an equation. Reference numeral 10 denotes a CPU (Central Processing Unit) that calculates an expected machining time from the contents input by the input unit 8 and the machining speed change data stored in the storage unit 9 and further searches and changes machining conditions. is there. Reference numeral 11 denotes a detection unit that detects the movement of the spindle 22 by detecting a pulse signal or the like of the encoder 21. Reference numeral 12 denotes an estimated processing time calculated by the CPU 10, a changed condition, and the like.
A display unit 13 for displaying on a T monitor or the like is a power supply for supplying a pulse current between the electrodes. Reference numeral 21 denotes an encoder, and reference numeral 22 denotes a main shaft of the electric discharge machine.

Next, the operation of the electric discharge machining apparatus of the present embodiment having the above-described configuration will be described with reference to FIGS. FIG. 2 is a characteristic diagram showing a change in machining speed when machining is performed under three machining conditions with different machining speeds by the electric discharge machine according to one embodiment of the present invention, and FIG. 3 shows a change in machining speed with respect to machining depth. FIG. 4 is a characteristic diagram showing the transition data of the machining speed stored in the storage unit and the transition data of the machining speed when the actual machining is performed. Now, it is assumed that the processor performs processing with a depth of 50 mm using a 10 mm square copper electrode.
The processing conditions used by the processor are as shown in FIG. The processor first inputs the processing contents (electrode material,
Input the electrode area, machining depth, etc.) and machining conditions (set current value, discharge time, pause time, etc.). With respect to the input machining conditions, the machining speed when the discharge state is good and the data of its transition are stored in the storage unit 9 in advance. The data stored in this case is as shown in FIG. Here, v represents the processing speed, and h represents the processing depth. Further, it is assumed that the relationship between v and h is given by equation (1). v = g (h) (1) Assuming that W is the amount of processing, the minute processing time dT is as shown in equation (2). dT = dW / v = dW / g (h) = S · dh / g (h) (2) where S is the electrode cross-sectional area, and this time processing using a 10 mm square copper electrode. Therefore, equation (3) holds. dW = S · dh (3) Accordingly, the processing time T is represented by the following equation (4). T = S∫ (dh / g (h)) (4) Formula The calculation of this formula and the calculation of the machining time using the formula are as follows.
This is performed in the CPU 10. The processing time T is a function of the processing depth h. In this case, the processing time can be calculated by substituting h = 50 mm. The calculated expected processing time is displayed on the display unit 12 to the processor.

Next, a case in which a processor performs processing to a depth of 100 mm using a copper electrode of a 10 mm square column will be described. In this case as well, as in the case of performing the above-described processing with a depth of 50 mm, the processor inputs the processing contents and processing conditions through the input unit 8. FIG. 2A shows the change of the processing speed according to the input processing conditions and processing contents. Among the processing conditions stored in the storage unit 9, parameters such as a set current value and a discharge time are the same as the input processing conditions,
Machining conditions having different parameters that affect only the machining speed, such as the electrode rising amount, the descent time, and the jump speed, are simultaneously searched. Here, the processing conditions (b) and (c) shown in FIG.
Is stored. Next, in the CPU 10, the depth 1
The processing condition sequence is selected so that the total processing time of 00 mm is minimized. That is, the processing conditions are selected so that the processing speed at the depth h is always maximized. in this case,
When 0 <h <h1, condition (a) is selected, when h1 <h <h2, condition (b) is selected, and when h2 <h <100, condition (c) is selected. Based on the selected condition, the estimated machining time is calculated in the same manner as described above, and the display unit 12 displays the estimated machining time along with the condition column to the processor.

Thus, in the electric discharge machining apparatus of the present embodiment,
Appropriate processing conditions and expected processing times are displayed, but even when processing is performed using these conditions, the processing state may be unstable. If the unstable machining state continues, concentrated arc discharge occurs, and there is a possibility that the workpiece may be damaged. In such a case, it is necessary to change the electrode rising amount and the pause time to change to appropriate conditions. It has been experimentally confirmed that the machining speed immediately before the occurrence of the concentrated arc discharge is about 50% of the ideal machining speed. When the reduction in the processing speed reaches that value, the processing does not suddenly progress thereafter. This is due to the occurrence of concentrated arc discharge. Therefore, when the processing speed is reduced to 50% of the ideal processing speed and the processing conditions are changed, concentrated arc discharge can be avoided.

For example, it is assumed that a processor performs processing to a depth of 50 mm using a copper electrode of a 10 mm prism, and processing under processing conditions (e) shown in FIG. 4 is in progress. The movement of the main shaft at this time is detected by detecting the encoder pulse by the detection unit 11. There is a relationship of the formula (5) between the machining speed v and the speed dl / dT of the main spindle. v = Sρ · dl / dT (5) where S represents the cross-sectional area, and ρ represents the density of the workpiece.

As shown in the above equation (5), the machining speed can be measured indirectly from the movement of the spindle. Therefore, the main shaft 2 is detected by the detection unit 11 via the encoder 21.
By detecting the movement of No. 2, the processing speed can be constantly measured. The change of the processing speed when processing is performed under the processing condition (d) shown in FIG. 4 is stored in the storage unit 9 and is shown by a solid line in FIG. The expected machining time is calculated based on this, but the change in the actual machining speed may be different from this. For example, suppose that the transition is made as shown by a broken line graph shown in FIG. That is, the machining depth h is h
Assume that the processing speed has decreased to v0 / 2 when the number reaches 3. At this time, the CPU 10 functioning as a changing unit
The processing conditions are switched from (d) to (e). Then, after the switching, the remaining machining speed is predicted from the machining speed of the stored machining condition (e), and the remaining machining speed is calculated.
Is shown to the processor.

As described above, the electric discharge machining apparatus of the present embodiment
An input unit 8 such as a keyboard for inputting a plurality of processing contents (electrode material, electrode area, processing depth, etc.) and processing conditions (set current value, discharge time, pause time, etc.), a processing speed for each processing condition, A storage unit 9 that stores a change in the processing speed that changes according to the processing content, and a change in the processing speed when processing is performed based on the processing content and processing conditions input to the input unit 8 in the storage content of the storage unit 9. A CPU 10 (arithmetic unit) for sequentially estimating and correcting the processing speed to calculate an expected processing time;
A display unit 12 for displaying the estimated processing time. This configuration corresponds to an embodiment of the first aspect of the present invention.

That is, in this embodiment, the processing contents, processing type, and processing conditions desired by the processor are input to the input unit 8. The basic machining speed of the input machining condition is stored in the storage unit 9 in advance, and the change of the machining speed in the machining content and machining type used in the machining condition and the method of correction thereof are also stored. Have been. And the CPU 10
(Calculation unit) calculates the correction of the processing speed, calculates an expected processing time based on the calculated series of processing speeds, and displays it on a display unit 12 such as a CRT.

Therefore, even when the machining state changes on the way and the machining speed is not constant, it is easy to accurately estimate the machining time, so that the exact estimated machining time can be known. In particular, if the correction data stored in the storage unit 9 is enhanced, a more accurate processing time can be predicted.

The electric discharge machining apparatus according to this embodiment has a CPU
At 10 (arithmetic unit), if the processing conditions input to the input unit 8 are inappropriate in light of the contents stored in the storage unit 9, the processing conditions are changed to change the processing conditions. The expected processing time is calculated, and the display unit 12 displays the expected processing time. This configuration corresponds to an embodiment of the second aspect of the present invention.

Therefore, the processing conditions are appropriately selected such that the processing speed is always maximized according to the processing state and the like. If the processing conditions more suitable than the input processing conditions are present in the storage unit 9, The processing conditions are changed to appropriate processing conditions, and an accurate processing time based on the changed processing conditions can be predicted. As a result, if there is a processing condition more appropriate than the condition selected by the processor, the processing condition is recommended, efficient processing can be performed, and an accurate expected processing time can be known.

Moreover, in the electric discharge machining apparatus of this embodiment, the detection unit 11 monitors the change of the machining speed during the machining by the encoder 21 one by one. The CPU 10 (arithmetic unit) changes the processing conditions by the (changing unit).
Calculates the expected machining time after the change of the machining time, and displays the expected machining time on the display unit 12. This configuration is described in claim 3
Corresponds to an embodiment of the present invention.

That is, in the process of starting and evolving the processing, a change in the processing speed is constantly monitored by the detection unit 11,
If the reduction rate of the processing speed exceeds a predetermined value set in advance, the processing conditions are changed, and the estimated processing time after the change is calculated and displayed.

Therefore, when the processing speed is significantly reduced during the processing, the processing conditions are automatically changed and the processing speed can always be maintained at a predetermined speed or more, so that the processing time can be reduced and the concentrated arc discharge can be reduced. Can be avoided.

[0031]

As described above, the electric discharge machining apparatus according to the first aspect of the present invention includes the input unit, the storage unit, the calculation unit, and the display unit, and the processing content and the processing input to the input unit. Conditions, the basic processing speed of the processing conditions stored in advance in the storage unit, sequentially predict the change in the processing speed in light of the processing speed change data that changes according to the processing content, to correct the processing speed By calculating the estimated machining time and displaying the estimated machining time, the accurate machining time can be estimated even when the machining speed is not constant, so that the exact estimated machining time can be easily known.

[0032] The electric discharge machining apparatus according to the second aspect of the present invention includes an input unit, a storage unit, a calculation unit, and a display unit, and the processing contents and processing conditions input to the input unit are stored in the storage unit in advance. If it is inappropriate in light of the stored contents, the processing conditions are changed, an expected processing time when processing is performed under the changed processing conditions is calculated, and the estimated processing time is displayed, whereby the input is performed. If the storage unit has more suitable conditions than the changed processing conditions, the processing conditions are changed to the appropriate processing conditions, and the processing time can be accurately predicted according to the changed processing conditions. The expected processing time can be easily known.

An electric discharge machining apparatus according to a third aspect of the present invention includes an input unit, a storage unit, a detection unit, a change unit, a calculation unit, and a display unit, and sequentially changes the machining speed during machining. Monitor,
When the machining speed is significantly reduced during the machining, the machining conditions are changed, and the estimated machining time after the machining time is changed is calculated, and the estimated machining time is displayed. When the condition is notable, the machining conditions are automatically changed and the machining speed can be maintained at a predetermined speed or more, so that the machining time can be shortened and concentrated arc discharge can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an electric discharge machine according to one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a change in machining speed when machining is performed under three machining conditions having different machining speeds by an electric discharge machine according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a change in a machining speed with respect to a machining depth by an electric discharge machine according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing machining speed transition data stored in a storage unit of an electric discharge machine according to an embodiment of the present invention and machining speed transition data when actual machining is performed. .

FIG. 5 is a schematic configuration diagram showing a basic configuration of a conventional electric discharge machine.

FIG. 6 is a diagram showing variations in processing speed when processing is performed a plurality of times under the same processing conditions.

FIG. 7 is a characteristic diagram showing the dependence of the processing speed on the processing depth when processing is performed with a simple-shaped electrode.

FIG. 8 is a characteristic diagram showing a relationship between a machining depth and a machining time in an ideal state, when a correction coefficient is used, and in actual machining.

[Explanation of symbols]

 Reference Signs List 8 input unit 9 storage unit 10 CPU 11 detection unit 12 display unit 13 power supply 21 encoder 22 main shaft

Claims (3)

(57) [Claims] 1. A machining gap formed between an electrode and a workpiece.
A power supply is connected to generate a discharge in the machining gap to
The discharge machining apparatus for machining a workpiece, a storage unit for storing an input unit in which a plurality of processing contents and processing conditions are inputted, the displacement of the machining speed to be changed more processing contents and processing speed for each processing condition An operation for sequentially estimating a change in machining speed when machining is performed with the machining content and machining conditions input to the input unit by referring to the contents of the storage unit, correcting the machining speed, and calculating an estimated machining time. And a display unit for displaying the expected machining time. 2. A machining gap formed between an electrode and a workpiece.
A power supply is connected to generate a discharge in the machining gap to
The discharge machining apparatus for machining a workpiece, a storage unit for storing an input unit in which a plurality of processing contents and processing conditions are inputted, the displacement of the machining speed to be changed more processing contents and processing speed for each processing condition when machining conditions inputted to the input unit is inappropriate to light of the contents of the storage unit is configured to change the processing condition, and calculates the expected processing time when processed at the changed machining condition computing unit And a display unit for displaying the estimated machining time. 3. A machining gap formed between an electrode and a workpiece.
A power supply is connected to generate a discharge in the machining gap to
The discharge machining apparatus for machining a workpiece, a storage unit for storing an input unit in which a plurality of processing contents and processing conditions are inputted, the displacement of the machining speed to be changed more processing contents and processing speed for each processing condition A detection unit that sequentially monitors a change in the processing speed during the processing, and a reduction in the processing speed during the processing by the detection unit is remarkable.
When the discharge of a changing unit for changing the processing conditions, and a calculator for calculating the estimated processing time after changing the processing time, characterized by including a display unit for displaying the expected machining time Processing equipment.