JPS5993233A - Electric discharge machining device - Google Patents

Abstract

PURPOSE:To prevent oxided sludge from sticking to an electrode or a work, by making the polarity of machining voltage into a reversion temporarily at a time when the shifting speed of the electrode drops below the specified value, in case of an electric discharge machining device using a dielectric fluid containing water as the main component. CONSTITUTION:A noncombustible dielectric fluid containing water as the main component is fed to a space between an electrode 14 and a work 12 from a nozzle 32, while pulse voltage out of a power source 16 is impressed on the electrode and the work and electric discharge machining is taking place, during which the electrode is made to shift relatively into horizontal movement by a numerical control system whereby the work 12 is formed into the desired machining contours. A conversion controller 22 detects the electrode's relative shifting speed and when the speed comes below the specified value, controller 22 gives a command to a polarity conversion device 20 so as to reverse the polarity of machining voltage as long as for a fixed time. Simultaneously with this, it gives an up-and-down jump motion to the electrode 14, intensifying the feeding pressure of the dielectric fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining apparatus, particularly an electric discharge machining apparatus that uses a nonflammable machining fluid containing water as a main component.

In the past, flammable liquids such as kerosene oil (BDF) were generally used as machining fluids in this type of electrical discharge machining equipment, but recently non-flammable machining fluids containing water as a main component have also been used. It's starting to look like this.

That is, as shown in a conventional example in FIG. 1, a workpiece 12 and an electrode 14 are opposed to each other with a gap in between in a machining liquid tank 10 to which a nonflammable machining liquid is supplied, and the machining process is carried out in the gap. It is configured to supply a high-frequency DC Nockles current from a power source 16 to cause a discharge phenomenon, thereby performing a predetermined machining.

The processing position for the workpiece 12 is moved in the horizontal direction by, for example, a numerical control device (No device). Thereby, a desired processed shape can be formed on the workpiece 12.

By the way, in the conventional electric discharge machining apparatus as described above, since a non-flammable machining fluid containing water as a main component is used, as shown in FIG. An electrolytic phenomenon occurs at, for example, the electrode 14.
If the side has positive polarity, the workpiece 12 with negative polarity
Impurities such as sludge containing oxides are electrodeposited on the side, and deposits 18 are generated on the processed surface of the workpiece 12. When such deposits 18 occur, it becomes difficult to maintain a normal discharge phenomenon, but the deposits 18 also narrow the machining gap, making it difficult to discharge sludge, etc. from the gap. A problem arises.

This invention has been made in view of the above-mentioned conventional problem, and its purpose is to reliably prevent the formation of the above-mentioned deposits by using relatively simple additional means, and thereby to prevent the formation of the above-mentioned deposits. It is an object of the present invention to provide an electric discharge machining device that can smoothly discharge and remove sludge and the like in a threshold machining gap between an electrode and maintain a normal electric discharge phenomenon to perform good electric discharge machining.

In order to achieve the above-mentioned object, the present invention aims to improve the workpiece by causing an electric discharge phenomenon in the gap between the workpiece and the electrode while a nonflammable machining fluid containing water as a main component is supplied. An electrical discharge machining device that performs machining is equipped with a polarity conversion device that temporarily reverses the electrical polarity between the workpiece and the electrode during machining, and the electrical polarity reversal operation by this polarity conversion device is performed on the workpiece. It is characterized in that the processing is performed when the horizontal movement speed of the processing position relative to the object falls below a predetermined value.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows an embodiment of the electrical discharge machining apparatus according to the present invention. The apparatus shown in the figure includes a machining power source 16 that supplies a high-frequency DC pulse current between a workpiece 12 and an electrode 14 facing each other with a gap in a machining liquid tank 10;
6, a polarity conversion control device 22 that controls the operation of this conversion device 20, and an electrode jumping device that drives the electrode 14 in a vertical jumping manner by a motor 26. 24,
A No. device 28 having a function of horizontally controlling the movement of the machining position relative to the workpiece 12, a machining fluid pressure regulating valve 30, a machining fluid jet nozzle 32, a machining fluid no.pass valve 34, a machining fluid supply pipe 36, etc. It is configured.

Here, the polarity conversion control device 22 detects the horizontal movement speed of the workpiece 12, and when the speed is decelerated to a preset constant value or less, operates the polarity conversion device 20 to maintain the horizontal movement speed. It is configured to reverse the electrical polarity of time-based machining.

In this case, it is desirable that the polarity be reversed when the movement of the workpiece stops for 30 seconds or more, and that the duration of the reversal can be variably controlled between 1 second and 1 minute. It is. Further, the electrode/jumping device 24 operates together with the polarity converting device 20, and when the polarity is reversed, jumps the electrode 4 up and down to perform processing in the gap between the electrode 14 and the workpiece 12. Configured to promote liquid convection. The machining fluid pinose ξ valve 34 is also closed together with the polarity converter 20, and the pressure of the machining fluid injected from the machining fluid jet nozzle 32 at the time of polarity reversal is reduced to 0.2 by 9/CI! It is configured to further promote convection of the machining fluid in the machining gap by increasing it to a value greater than L.

Now, according to the apparatus configured as described above, the horizontal movement speed of the processing position with respect to the workpiece 12 decreases or the movement stops, and if this state continues for a predetermined time or more, deposits are generated. When this occurs, the polarity conversion control device 22 operates the polarity conversion device 20, thereby inverting the electrical polarity between the workpiece 12 and the electrode 14 for a predetermined period of time. Then, an electrolysis phenomenon occurs in the opposite direction, and the deposits that have begun to form on the processing surface of the workpiece 12 are released and removed, and at the same time, the electrode 14 undergoes a vertical jumping movement. In addition, the supply pressure of the machining fluid is increased to promote convection of the electrolytic solution in the machining gap, and as a result, impurities such as sludge in the machining gap are quickly removed. Therefore, the normal discharge phenomenon can be restarted subsequently, and good discharge machining can be performed.

Here, if the timing of polarity conversion and the duration of the conversion are set in advance in the polarity conversion control device 22 and variably controlled according to machining conditions such as machining speed, various machining operations can be performed. Under these conditions, it is possible to reliably prevent the formation of deposits and perform good electrical discharge machining.

In this case, it is sufficient that the duration of polarity reversal can be variably controlled between 1 second and 1 minute.

As described above, the electric discharge machining apparatus according to the present invention can use a nonflammable machining fluid mainly composed of water by simply providing a relatively simple additional configuration, and can also prevent deposits from forming on the electrode or the surface. It is possible to reliably prevent abnormal discharge caused by generation on either side of the workpiece, and perform good electrical discharge machining.

[Brief explanation of drawings]

Figure 1 is a configuration diagram showing an example of a conventional electrical discharge machining device, Figure 2
The figure is a cross-sectional view showing an example of a machining state by a conventional device, and FIG. 3 is a configuration diagram showing an embodiment of an electric discharge machining device according to the present invention. Identical members in each figure are given the same reference numerals, and 10 is a machining liquid tank;
12 is a workpiece, 14 is an electrode, 16 is a processing power source, 18 is a deposit, 20 is a polarity conversion device, 22 is a polarity conversion control device, 24 is an electrode jumping device, 26 is a motor for driving the electrode up and down, 28 is NO. (numerical control) device, 30 is a machining fluid pressure regulating valve, 32 is a machining fluid jet nozzle, 34 is a machining fluid nozzle/spout valve, and 36 is a machining fluid supply pipe. Agent Patent attorney Shin Kuzuno - (1 other person) Figure 1 6 Figure 2

Claims (1)

[Claims] (1) Machining of the workpiece is performed by causing a discharge phenomenon in the gap between the workpiece and the electrode while a nonflammable machining fluid containing water as a main component is supplied. In the electrical discharge machining apparatus, a polarity conversion device is provided to temporarily reverse the electrical polarity between the workpiece and the electrode during machining, and
An electric discharge machining apparatus characterized in that the electric polarity reversal operation by the polarity converter is performed when the horizontal movement speed of the machining position with respect to the workpiece falls below a predetermined value. (2. In the device according to claim (1), the polarity conversion is performed when the horizontal movement of the processing position stops for 30 seconds or more, and the polarity conversion time is between 1 second and 1 minute. An electric discharge machining apparatus characterized in that the electric discharge machining apparatus is variably controlled. (3) In the apparatus according to any one of claims (1) and (2), at the same time as the polarity conversion, An electric discharge machining apparatus characterized in that the supply pressure of the machining fluid to be supplied is increased to 0.2 to 9/cr?r or more. (4) Claims (1), (2), and (3). An electrical discharge machining device characterized in that the electrode is moved up and down simultaneously with polarity conversion.