JPH01316131A - Electric discharge machining - Google Patents

Abstract

PURPOSE:To carry out the working with high precision at a high speed by servodriving an electrode in the swing radial direction through a circular movement at a certain angular speed and moving the electrode in reciprocation in the working depth direction through the swing movement, keeping the gap from a workpiece constant. CONSTITUTION:A between-electrode voltage evaluation part 40 calculates the expansion quantity of the swing radius R represented by a primary function from the between-electrode voltage Vg between a workpiece 10 and an electrode 16, and the actual swing radius R is obtained by a swing radius calculation part 42, and the electrode 16 is moved in circular form at a certain angular speed by the X and Y-axis driving motors 24 and 26 through an output part 43, and servooperated in the swing radial direction. Further, an output part 41 in the depth direction outputs a certain speed output quantity for the vertical movement of the electrode 16 into a Z-axis driving motor 28, and moves the electrode 16 in reciprocation at a certain speed in the working depth direction. Therefore, the gap between the electrode is kept always constant, and the smooth and stable working can be carried out, and the working with high precision can be carried out at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electric discharge machining method, and particularly to a side surface finishing method.

[Prior Art] FIG. 7 is an overall configuration diagram of a machining system that implements a conventional electrical discharge machining method.

In the figure, 10 is a workpiece immersed in an insulating machining liquid 14 stored in a machining tank 12, and this workpiece 10 faces an electrode 16 with the machining liquid 14 in between.

The machining fluid 14 is circulated between the machining tank 12 and an external tank 18, and returns from the machining tank 12 to the tank 18, and the machining fluid 14 stored in the tank 18 is transferred from the nozzle 20 to the machining tank 12 by the pump P. The liquid is sprayed into the gap between the workpiece 10 and the electrode 16 inside. Further, the relative movement between the workpiece 10 and the processing electrode 16 is achieved by moving the table 22 on which the workpiece 10 is placed within a plane including the table 22 using an X-axis drive motor 24 and a Y-axis drive motor 26. or electrode 1
6 in the vertical direction using the X-axis drive motor 28, or by rotating the electrode 16 to an arbitrary angle using the C-axis drive motor 30. 32 is a processing power supply that supplies electrical energy between the electrode 16 and the workpiece 10, such as a DC power supply E and an l-transistor Tr.

It is composed of a control circuit 34 that switches a capacitor C1, a resistor R, and a transistor Tr.

36 is the X-axis drive motor 24. Y-axis drive motor 26°X-axis drive motor 28. This is a numerical control device such as a numerical control copying device or a computer that drives the C-axis drive motor 30 according to a predetermined program.

Next, the operation will be explained. Now, as shown in FIG. 8(a), when attempting to finish the machined surface of the workpiece 10 in side processing when the plate thickness d of the electrode 16 is smaller than the plate thickness of the workpiece 10, - Swing processing is used for C. As shown in FIG. 5(b), the machining is performed by repeatedly lowering the electrode 16 stepwise in the Z-axis direction and then moving it in a circular motion with a radius R on the XY plane. Here, R is called the swing radius. However, when electrical discharge machining is performed, the electrode 16 itself is also worn out, so streaks 50 are likely to occur on the machined surface regardless of the value of the step distance ΔZ that is lowered to - times.

[Problem to be solved by the invention] Since the conventional electrical discharge machining method is performed as described above,
There was a problem in that streaks 50 were formed on the machined surface of the workpiece 10.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electric discharge machining method that does not generate streaks on the machined surface of a workpiece.

[Means for Solving the Problems] The electric discharge machining method according to the present invention includes servoing the electrode in a radial direction of swing by circularly moving the electrode at a constant angular velocity, and maintaining a constant gap between the workpiece and the electrode. It is designed to repeat reciprocating motion at a constant speed in the direction of the machining depth while making an oscillating motion.

The electric discharge machining method according to another aspect of the present invention evaluates the machining state from the voltage between the electrode and the workpiece, and rotates the electrode a certain number of times while the voltage between the electrodes and the workpiece is the same as the set voltage based on the evaluation result. While there is a difference between the inter-electrode voltage and the set voltage based on the above evaluation results, the oscillation radius is increased or decreased to keep the gap between the workpiece and the electrode constant according to the voltage difference. After that, it is made to oscillate at a constant rotational speed.

[Function] In this invention, by servo-operating the electrode that moves circularly at a constant angular velocity in the oscillating radial direction, the electrode moves at a constant distance in the machining depth direction while making an oscillating movement that keeps the gap with the workpiece constant. Since it is reciprocated at high speed, uniform electrical discharge machining is possible without creating streaks on the machined surface.

In addition, in this invention, in order to keep the gap between the electrode and the workpiece constant, the electrode is servoed in the radial direction of the oscillation, and then the electrode is rotated at a constant angular velocity. The evaluation of the voltage between the electrodes is now accurate, the gap between the electrodes is always kept constant, smoother and more stable corners can be obtained, and high-speed, uniform precision machining is possible.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a discharge application system according to the method of the present invention.

In the figure, 40 is a machining voltage evaluation section, and the workpiece 1
0 and the electrode 16, and calculate the amount of expansion of the swing radius R using a linear function as shown in the characteristic diagram of FIG. 2, for example.

The swing radius calculating section 42 calculates the actual swing radius R based on the amount of expansion of the swing radius. This is the previous swing radius R
This is done by adding the current enlargement amount of the swing radius R to the above. The swing direction output section 43 outputs the X-axis drive motor 24 based on the swing radius R determined by the swing radius calculation section 42 . Each drive amount is output to the Y-axis drive morph 26.

The depth direction output unit 41 outputs a constant speed output amount for the vertical movement of the electrode 16 to the X-axis drive motor 28. In the same figure, the electrode-to-electrode voltage evaluation section 40. Depth direction output section 41. The calculations by the swing radius calculation section 42 and the swing direction output section 43 are constantly executed during processing, and control regarding not only the vertical movement of the electrode 16 but also the change in the swing radius R is performed continuously.

The movement of the X and Y axes in the swing plane will be explained based on FIG. 3. Now, in the process in which the electrode 16 is oscillating at the final target radius R2 angular velocity ω centered on point P, the oscillation radius is Ri + 1 = Ri h l based on Fig. 2.
It is determined by +ΔR1. In FIG. 3, when there is an electrode at P and the interelectrode voltage Vg is close to a short circuit and the expansion amount ΔR5 becomes a negative value, the swing radius R2 becomes smaller than R9 when moving from P to R2.

In addition, in actual movement calculation, the swing center P is set to the coordinate value (
x, y) = (0, O), θ,. From 1=θ8+ω, the coordinate value of P1+1 is PL, +(X, y)=(R
+, +cosθi+l+ Rt, +stnθ1+1)
The output to the X and Y axis drive motors 24 and 25 is (x, y) = Pt, + (x, y) - P = (χ, y
).

Further, the electrode 16 performs vertical movement in the Z-axis direction at a constant speed and a predetermined distance in addition to the above-mentioned X- and Y-axis movements, and the amount of movement output in the Z-axis direction is determined by the depth direction output section 4. It is output from the machine to the X-axis drive motor 28.

Here, the depth direction output section 41 and the swing direction output section 43 are controlled independently from each other, and each control is always performed.

In the above embodiment, the processing axis is the Z axis, and the swing plane is the X axis.
Although the Y plane is shown, the processing axis is the X axis.

The oscillating plane may be the YZ plane, or the processing axis may be the Y axis and the oscillating plane may be the ZX plane.

Further, in the above embodiment, a through-hole machining is taken as an example, but a bottom-finishing machining may also be used.

In this embodiment as described above, while the electrode is reciprocated with respect to the workpiece at a constant speed, it is also moved by ↑8 motions in a direction perpendicular to the direction of the reciprocating motion.
There are no streaks on the side finishing surface, and highly accurate machining can be achieved.

FIG. 4 is a block diagram showing an embodiment of a discharge heating system according to another method of the present invention.

In this figure, the same reference numerals as in FIG. 1 represent the same parts. In addition, in the radial direction output section 44, the swing radius calculation section 4
Based on the swing radius obtained in step 2, the X-axis drive motor 24
．． Each drive amount is outputted to the Y-axis drive motor 26.

The circumferential direction output section 45 outputs the X-axis drive motor 24. based on the new swing radius obtained by the swing radius calculation section 42. The drive amount in each circumferential direction is outputted to the Y-axis drive motor 26.

Also, the inter-electrode voltage evaluation section 40. Calculations by the depth direction output section 41, the oscillation radius calculation section 42, the radial direction output section 44, and the circumferential direction output section 45 are constantly executed during machining.
Control regarding not only the vertical movement of 6 but also the change in the swing radius is performed continuously.

Next, the movement of the X and Y axes in the oscillating plane by the discharge heating system having the above configuration will be explained with reference to FIGS. 5 and 6.

FIG. 6 is a flowchart showing the procedure for controlling the movement of the electrode in this embodiment. When starting the oscillating machining, first, in step 51, the electrode 16 is moved with an initial oscillating radius R8 around point P. is set, and in the next step, circular motion is started using this swing radius RI and angular velocity ω.

During this oscillating process, the oscillation radius is determined by the oscillation radius calculation unit 42 from Ri + l + R3 + ΔRi based on FIG.

Figure 5 shows the movement path of the electrode during swing machining.
Now, the electrode 16 is at P I+, and the voltage between the electrodes at this time is Vg
Suppose we want to evaluate. That is, first, in step 53, it is determined from the machining voltage whether the machining is normal or not. Here, when it is determined that the voltage between the electrodes is normal, that is, the voltage between the electrodes is the same as the set voltage, the process returns to step 52 and the X and Y axis motors 24 and 25 are controlled so as to swing at a constant rotation speed. Further, if it is determined that it is not normal, the process moves to step 54, and it is determined whether or not to process it.

Here, when rNo, that is, when the gap between the electrodes becomes small due to processing powder etc. staying in the voltage between the electrodes and discharge is performed at a low voltage between the electrodes, the process proceeds to step 57, and rYEs
When the radius is JO, the process moves to step S55 and it is determined whether the radius is the target radius R or not. When it is determined that the radius is the target radius, the process proceeds to step 59 and the swing machining is completed. , When rNo, the process moves to step 56 and the X- and Y-axis drive motors 2 are operated in the direction of enlarging the swing radius R, that is, so that the gap between the poles reaches the set value.
4.degree. 26 is servo-controlled to increase the electrode in the radial direction of oscillation, and the process returns to step 52 to evaluate the voltage between the electrodes.

Further, when it is determined in step 57 that the inter-electrode voltage Vg is low and almost short-circuited, and that the expansion amount ΔR8 has become a negative value, the process proceeds to step 58, and the swing radius R2 is changed in the movement from R1+ to P2I. By servo-controlling the X and Y axes so that R9 is smaller, the short circuit between the electrode 16 and the workpiece 10 is eliminated. And step 5
Returning to step 3, it is determined again whether the machining state is normal, and when the short circuit is resolved, that is, when it is normal, the circular movement is started again at R2.

In addition, in actual movement calculation, the swing center P is set to the coordinate value (
As X, Y) = (0, O), θ3. From I=θ, +ω, P. 11. The coordinate value of 1 is expressed as P I+++jl(
X, y) = (R,, cosθi+l+ Rj+1s
ln Oi++), and the output to the X and Y axis drive motors during radial servo control is (x, y) = Pt, J, + (x, y) - Pi + j (X +
y), and when moving in the circumferential direction, (x,
y) =Pi+l+j(X+y) P+,,
Perform with (X, y).

In this embodiment as described above, the machining state (steps 53, 5
4, 55, 57), and as long as the inter-electrode voltage according to the evaluation result is the same as the set voltage, the oscillating motion is performed at a constant orbiting speed,
While there is a difference between the inter-electrode voltage and the set voltage, the swing radius is increased or decreased according to the voltage difference, and then the circular motion is performed.
The evaluation of the voltage between the electrodes is performed correctly, the gap between the electrodes is always kept constant, and smoother and more stable machining can be achieved, resulting in faster and more accurate machining.

In the above embodiment, the machining axis is the Z axis and the swing plane is XY thousand planes, but the machining axis may be the X axis and the swing plane may be the YZ plane, or the machining axis may be the Y axis. , the swing plane may be the ZX plane.

Further, the electrode may be reciprocated at a constant speed in the Z-axis direction while making a constant circular motion, and furthermore, a machining method of another invention may be executed after machining in the Z-axis direction is completed. .

[Effects of the Invention] As described above, according to the present invention, the electrode is reciprocated with respect to the workpiece at a constant speed, while being oscillated in a direction perpendicular to the direction of the reciprocating movement. Therefore, there is an effect that streaks are not generated on the machined surface and a workpiece with high machining accuracy can be obtained.

In addition, in order to keep the voltage between the poles constant, a servo is applied in the radial direction of the swing so that the result is reflected at the position where the voltage between the poles is evaluated, and then a constant circular motion is applied. This has the effect that the gap between the poles is always kept constant, resulting in smoother and more stable machining, and also enables high-speed, high-precision machining.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing an embodiment of the electrical discharge machining method according to the method of the present invention, Fig. 2 is an explanatory diagram showing the content of interspecies voltage evaluation in this embodiment, and Fig. 3 is an illustration of the electrode in this embodiment. FIG. 4 is a diagram showing the overall configuration of an embodiment of the electric discharge machining method according to another invention method of the present invention, and FIG. 5 is a diagram showing how the amount of movement is determined. An explanatory diagram showing the movement path, FIG. 6 is a flowchart showing the machining procedure for controlling the movement of the electrode in this embodiment, FIG. 7 is a diagram showing the movement of the electrode by the conventional electric discharge machining method, and FIG. 8 (a) , (b) is a schematic configuration diagram showing a conventional electrical discharge machining device. DESCRIPTION OF SYMBOLS 10... Workpiece, 16... Electrode, 24... X-axis drive motor, 26... Y-axis drive motor, 28... Z
! lll drive motor, 40... electrode voltage evaluation section, 41
... Depth direction output section, 42 ... Oscillation radius calculation section, 4
3... Swinging direction output part, 44... Radial direction output part,
45...Revolving direction output section. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In an electric discharge machining method in which a workpiece and an electrode are moved relative to each other, electrical energy is generated between the workpiece and the electrode, and the workpiece is machined into a desired shape. is moved circularly at a constant angular velocity and servo operated in the oscillating radial direction, and while the gap between the workpiece and the electrode is kept constant and the oscillating motion is made, the reciprocating motion is repeated at a constant speed in the machining depth direction. An electric discharge machining method characterized by: (2) In an electrical discharge machining method in which a workpiece and an electrode are moved relative to each other, electrical energy is supplied between the workpiece and the electrode to generate an electric discharge, and the workpiece is machined into a desired shape. The machining condition is evaluated from the voltage between the electrodes and the workpiece, and while the voltage between the electrodes and the workpiece is the same as the set voltage, the electrode is oscillated at a constant rotational speed, and While there is a difference between the voltage and the set voltage, the oscillation radius is increased or decreased in accordance with the voltage difference so as to keep the gap between the workpiece and the electrode constant, and then the oscillation movement is performed at a constant rotation speed. electrical discharge machining method.