JPS5919637A - Power source circuit employed in electrolytic discharge machining - Google Patents

Abstract

PURPOSE:To obtain high voltage necessary for discharge even from a low voltage power source, by providing an inductance in a conduction circuit in complex working such as electrolytic discharge mechanical grinding where a grindstone having conductive section and insulative section is employed. CONSTITUTION:A grindstone 1 has a conductive section 2 and an insulative grinding section 3 to perform complex machining of electrolytic discharge and mechanical grinding is performed by supplying power to the working section while feeding electrolyte. A current limit resistor R and an inductance L are provided in a conduction circuit from a power source PW. High voltage is produced in the working gap at the instance when the conductive section 2 and the workpiece 4 are separated through counter-electromotive force of the inductance L sufficient for starting discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit used for special electrolytic discharge machining.

First, an outline of a special electrolytic discharge machining method developed by the inventor of the present invention will be explained.

In FIG. 1, (1) is a non-conductive grindstone, and a conductive band (2) is formed on the circumferential surface of this non-conductive grindstone (1).

The part of the circumferential surface other than the conductive band (2) is alternately contacted with the non-conductive grinding wheel and the exposed polishing band (3), so that electrolytic action and mechanical polishing are possible. It was found that in addition to the action, an electric discharge action was also performed, and that difficult-to-cut materials could be efficiently ground.

The mechanism of each action is considered as follows.

<A> Electrolytic action Start.

1 substance (1) acts to produce a metal oxide.

<Exposure> Mechanical grinding action Immediately after this, the abrasive band (3) of the whetstone (1) passes through, so the abrasive grains scrape off the dissolved parts and oxide film. In this way, the processed surface is always activated because the oxide film and the like are removed immediately after they are generated.

Therefore, electrolysis is possible with a much smaller current than in conventional electrolytic grinding.

<No.> Discharge action Unlike conventional electrolytic grinding wheels, the conductive band (2) exists discontinuously.

Therefore, one conductive band (2) is >6710 T, f
9 (41) - only momentary contact.

As a result, a discharge phenomenon occurs due to the pulsed current, and sparks fly between the two at the moment of contact.

Melt one point and blow it away.

Electric discharge machining is performed in this manner.

For the electrolytic action in the processing method of the present invention, the machined surface of the workpiece is constantly activated by the abrasive band (3) of the grindstone as described above, and as a result, both current and voltage need to be smaller than in the conventional electrolytic grinding process. This phenomenon is advantageous.

However, from the viewpoint of discharge action, it is disadvantageous in that a large voltage cannot be obtained.

The present invention has been made to address these points, and provides an electrolytic discharge machining method that allows electrolytic grinding to be performed with a small current and low voltage by combining it with a mechanical grinding action, and at the same time enables discharge with a high voltage. The purpose is to provide.

Next, an example will be described.

<A> Basic circuit As explained above (Fig. 1), the rotating shaft (5
) is provided with a sliding electrode such as a slip ring brush (6), and this slip ring (6) is connected to the first terminal (P).
Connect to.

On the other hand, the base (7) on which the cane workpiece (4) is placed is connected to the second terminal (E).

And between the input power supply (pw) and the first terminal (P), there is an inductance (L) to generate a back electromotive voltage, and a current limiting resistor (a series circuit with a river is connected to appropriately limit the current). do.

On the other hand, the input power source (FW) and the second terminal (E) are directly connected.

In other words, all basic circuits can be used only for the power supply (FW).

Slip ring (6) and grinding wheel (1) conductive band (2)
and are electrically connected by a conductive path (8) buried in the side surface of the grindstone (1).

<Open> Action <Low 1> Electrically connect between the conductive band (2) of the grinding wheel (1) and the workpiece (4) from the discharge input power source (FW), and rotate the grinding wheel (1). When brought into contact with the workpiece (4), the rotation of the grindstone (1) intermittently creates a conductive band (
2) come into contact and electrical switching is repeated between the two.

Therefore, when the conductive band (2) and the workpiece (4) come into contact with each other, a current flows through the inductance (L). Then, at the moment of separation, that is, the moment when the circuit is closed, there is a power supply (FW) between them due to the back electromotive force caused by the inductance (L)! A high voltage several tens of times higher than the actual pressure is generated.

Spark discharge and glow discharge occur at the moment of separation due to this high voltage, and this flow of electrons with high current density melts one point of the workpiece, allowing electrical discharge machining with a good blow-off effect to be performed.

At this time, the current limiting resistor (FL) is connected in series with the inductance (L).
), it is possible to appropriately limit the current and obtain low current and high voltage with good discharge efficiency.

<Row 2> Grinding: The machined surface, which has been slightly melted by electrolytic discharge, comes into contact with the grinding band (3), which has high mechanical strength, at the next moment and scrapes off the melted portion.

Other effects are as described above.

(G) Other circuits and above circuits are those in which an inductance (L) and a resistance (R) are connected in series, but even if only the inductance (L) is connected in parallel with the input power supply (FW) (Second. (Figure 3) Similarly, high voltage discharge can be obtained.

In that case, a diode (D) is used to prevent backflow.

As described above, the present invention provides an inductance in the power supply circuit of the grinding wheel that electrically opens and closes with respect to the workpiece, generates a back electromotive force, and generates a high voltage at the moment the conductive band of the grindstone separates from the workpiece. This is a power supply circuit configured to generate electric discharge.

Therefore, work can be carried out under a normally low power supply voltage, with little danger, and it has become possible to process difficult-to-cut materials that could not be processed using conventional processing methods.

[Brief explanation of drawings]

Fig. 1 2 An explanatory diagram of one embodiment of a power supply circuit combined with the special processing method that is the premise of the present invention, Fig. 2.3: An explanatory diagram of another embodiment, 1: Grinding wheel, 2: Conductive band, 3 : Polishing band, L: Inductance, R: Current limiting resistance

Claims (1)

[Claims] An inductance is provided in the power supply circuit of the grinding wheel that electrically opens and closes with respect to the workpiece to generate a back electromotive force, and when the workpiece and the grindstone are electrically opened, a discharge due to high voltage is generated. A power supply circuit used for electrolytic discharge machining configured to generate