JPS59134621A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To suppress wear of a processing electrode as well as increase the processing speed by furnishing the output circuit of the power source for processing with a circuit, which is to change and control at least either of the positive pulse current peak value and negative pulse current peak value included in the output pulse. CONSTITUTION:A wire electrode 1 on a reel 2 is wound through guides 4 on another reel 3, and a work to be processed 7 is placed as facing the wire electrode 1 between the guides 4. Here the power source for processing 8 is furnished in order to supply a negative and positive pulses alternately to the gap formed between the wire electrode 1 and the work to be processed 7. The output from this power source 8 shall go in series connection with a circuit 9, which is to increase and control the positive pulse peak valuee composed of a series circuitry consisting of a capacitor 10 and switching element 11 and a mono-polar trigger circuitry consisting of a diode 12. Thereby the positive pulse current can be enlarged and the negative lessened, that ensures reduction of wire electrode 1 wear as well as increase of processing speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical discharge machining device that processes a gap between an electrode and a workpiece by applying pulsed discharge to face each other, a wire-cut electrical discharge machining device, and an improved ICC grinding any device using electric discharge.

When pulse discharge is repeated in the machining gap between the electrode and the workpiece, carbide or machining debris may adhere to the electrode machining surface, deforming the shape and reducing machining accuracy, or arc discharge may occur through the deposits, causing machining. The knee did not progress. The wire breaks. In addition, the grinding process may deteriorate due to clogging due to deposits.

For this reason, conventionally, attempts have been made to use a power source for machining that supplies pulses having a positive polarity pulse with the workpiece side as an anode and a negative polarity pulse with the workpiece side as a cathode. However, if the current peak values of the positive polarity pulse and the negative polarity pulse are equal, the amount of electrode wear increases, and the amount of machining of the wave-processed object decreases, resulting in a decrease in machining speed.

In order to eliminate this drawback, the present invention is provided with a circuit that changes and controls one or both of the positive pulse current peak value and the negative pulse current peak value of the output pulse in the output of the processing power source. .

The present invention will be explained below with reference to an embodiment of the drawings.

In FIG. 1, 1 is a wire electrode, reel 2. and is wound onto the other reel 3. Reference numeral 4 denotes guides above and below the processing section, and the wire 1 supplied from the reel 2 runs between these guides 4 with a predetermined tension and speed to the reel 3.
It is wound up. 5 is a capstan, 6 is a brake, and 7 is a workpiece opposed to the wire electrode 1 between the guides 4, which is usually fixed to a table (not shown), and the table is controlled by an NC control device in the X-Y plane direction. The drive is controlled by a feed motor. 8 is a processing power source that alternately supplies positive and negative pulses to the opposing gap between the wire electrode 1 and the workpiece 7; 9 is a capacitor 10 and a switch element 11;
This is a circuit for controlling the increase in the peak value of the positive pulse current, which is made up of a series circuit of the diode 12 and a unipolar 1 to RIGA circuit of the diode 12, and is connected in parallel to the output of the processing type #i8. 1
3 is a capacitor connected in parallel to the machining gap.

The output j pulse of the machining power supply 8 is positive as shown in FIG.
Pulses are output alternately in reverse. The output pulse is applied between the wire 1 and the workpiece 7 to generate electrical discharge, thereby performing cutting in a relatively moving shape. However, when the pulse current flowing between the wire and the workpiece is outputted from the machining power supply 8 as a positive pulse with the workpiece 7 as the anode, a trigger voltage is applied to the switch 11 through the diode 12, and the switch is switched on. , 11 is turned on to charge the capacitor 10, and at the same time, the charged charge is discharged. This capacitor 10
Since the discharge current is superimposed on the discharge of the capacitor 13, which is constantly charged and discharged, the peak value of the discharge current of the positive pulse increases. Next, when the machining power supply 8 outputs a negative pulse with the workpiece 7 as the cathode, the switch 11 is not triggered, so the capacitor 10 is not charged and only the capacitor 13 is discharged, and the peak value of the negative pulse current is controlled low. The current peak value can be arbitrarily selected and controlled by selecting the capacitances of the capacitors 10 and 13, and the negative pulse current peak value can be controlled to change such as the positive pulse current peak value.

In general, when machining is performed using only positive pulses with the workpiece side as the anode, the amount of machining of the workpiece and the amount of electrode wear are different, for example, in machining where the average machining current is 150A/cm2, although it of course varies depending on various machining conditions. The ratio of l:
It is about 0.3. Therefore, the contribution rate to the machining speed is only about 60% of the total machining amount (workpiece machining time + electrode consumption amount). Therefore, if a reverse polarity pulse is applied, metal etc. will adhere to the electrode, but as the amount of the metal adheres increases, the processing speed will actually decrease.

Therefore, according to the present invention, the positive pulse current is controlled to be large and the negative pulse current is controlled to be small. That is, the capacitor 10 in the example diagram is 2 μm, and the capacitor 13 is 0.0 μm.
When it was set to 1 μF, the machining speed rate was about 85%.

In this way, the present invention eliminates electrode wear and also (=J
It is easy to reduce the amount of work required and increase the processing speed.

Figure 3 shows another embodiment of a circuit that changes and controls the peak value of the pulse discharge current. It is a circuit.Switch 1
Similarly to the switch 11 in FIG. 1, a gate circuit 11 is formed so as to become conductive when a positive pulse is applied. The figure (b) shows a circuit in which a capacitor 113 is further connected in parallel to the inductance 112, and the figures (C) and (d) show examples in which a unidirectional diode 114 is used in place of the switch 111.

Next, to explain a specific example, a copper wire with a wire diameter of 0.2 φ is used as a wire electrode, and a workpiece is made of 8550 material with a thickness of 2 mm.
．． When wire cutting a 5 mm plate material, the machining fluid has a resistivity of approximately 40 was approximately 3211 IIll/min.

In this case, the running speed of the wire electrode is 6m/n+t
It was n. Therefore, when using a machining power supply that applies 30% negative polarity pulses, we were able to reduce the wire running speed to 2 m/min, but the machining speed was approximately 23 mm/min.
It decreased to n.

According to the present invention, this is converted to the output of the processing power source as shown in Fig. 3 (a).
) Connect the circuit shown in the figure and connect the capacitor 101 to 1.4 μF.
Switch 1 using 3.6μH for 1 inductance 112
When a high-speed transistor switch was used for No. 11, the processing speed was approximately 311/1n. Further, when the circuit shown in FIG. 3(b) was used and 0.06 μF was used for the capacitor 113, the processing speed was almost the same. Also, no matter which circuit is used, the running speed of the wire is 2
Stable processing was performed at 111/min without any wire breakage.

As described above, the present invention has the effect of reducing electrode wear and increasing machining speed, and in wire cutting, it is possible to reduce the amount of wire used and perform highly efficient machining. In engraving, it has great practical effects, such as reducing the amount of electrodes used and allowing highly accurate machining.

Note that the processing power source is not limited to one that outputs rectangular wave pulses, and can be used in conjunction with a capacitor to change and control the peak value of a pulse current of a predetermined polarity.Switches, diodes, etc. may also use similar functional elements as appropriate. be able to.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2 is a diagram illustrating some of its functions, and FIG. 3 is a diagram illustrating a partial circuit of another embodiment. 1...Wire electrode 7...Workpiece 8...Machining power source 10...Capacitor 11 ......Switch 12...Diode 13...Capacitor 101...Capacitor 111... ...Switch 112...Inductance 113...
・・・・・・Capacitor 114・・・・・・Diode patent applicant Kiyoshi Inoue Representative of Inoue Japax Institute Co., Ltd. f2

Claims (1)

[Claims] In an electric discharge machining device that performs electrical discharge machining by applying a pulse to a machining gap where an electrode and a workpiece face each other, a positive pulse with the workpiece side as an anode and a negative pulse with the workpiece side as a cathode are applied to the machining gap. A processing power source that applies pulses having a certain amount is provided, and a circuit is provided at the output of the processing power source to change and control one or both of the positive pulse current peak value and the negative polarity pulse current peak value of the output pulse. electrical discharge machining equipment.