JPS6347019A - Electric-discharge machine - Google Patents

Abstract

PURPOSE:To aim at refinement in surface roughness and reduction in electrode consumption, by impressing output of a second power unit overlappingly on that of a first power unit after the elapse of the specified time, while increasing the said overlappingly impressed output voltage with time elapsing, and preventing an electric charge of more than necessity from being charged to suspension contents existing in an erosion gap. CONSTITUTION:When discharge is not performed to an erosion gap 1b within the specified time, auxiliary switching elements 10a-10d is turning on while shifting 10a 10b 10c 10d in consecutive order till the discharge is started by a discharge detector 15 and an auxiliary control circuit 200. Therefore, DC voltage is overlapped to the gap 1b in order of E+Ea E+Ea+Eb E+Ea+ Eb+Ec E+Ea+Eb+Ec+Ed, thus the discharge is started to the gap 1b with impressed voltage corresponding to a state of the gap 1b. In consequence, an electric current to be discharged to the gap 1b from suspension contents 1a existing in the gap 1b can be minimized, so that surface roughness on a workpiece is made into fineness and, what is more, electrode consumption is minimizable.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention applies electrical discharge machining by applying a pulse voltage between a tongue machining electrode and a workpiece that are disposed opposite to each other through a minute gap. The present invention particularly relates to a power supply device of an electric discharge machining apparatus.

[Conventional technology]

FIG. 4 is a circuit diagram showing a conventional device of this kind. In the figure, (1) is a machining electrode, and (2) is a machining electrode (1) that faces the machining electrode (1) across a machining gap (lb). y, = workpiece, (3) is the main DC stabilized power supply used for processing workpiece (2), (4) is a diode, (5) is the first current limiting resistor, (6) is The main switching element (7) is the main control circuit that controls the main switching element (6), (
8) is an auxiliary DC stabilized power supply for superimposing an impulse voltage on the output voltage of the main DC stabilized power supply (3) applied to the processing gap (1 hJ), and (9) is a second current limiting resistor. , αO is an auxiliary switch/'J switching element, and (6) is a pulse pause determination circuit (2) that outputs a pulse start signal 7, and by that signal, the pulse output Q of FRI, rib flow = l block α3.
I...

When a certain period of time (hereinafter referred to as Tc) has elapsed since the first moment of discharge, the auxiliary switching element QG is set to 0, and the discharge detection circuit OQ detects the discharge current, and at 1r, the auxiliary switching element QG is set to 0. This is an auxiliary control circuit that turns off the switching element. In addition, 0aO) The pulse stop determination circuit determines the application time (referred to as pulse width) of the pulse voltage to be applied (referred to as pulse width) and the non-applying time (referred to as t*stop width).
The free circuit 03 stores the output signal of the pulse pause determination circuit 02;
0) The discharge detection circuit is a discharge detection circuit for operating the above-mentioned auxiliary control circuit α1) when the discharge VL current is not flowing in the machining gap (1,b).

Further, (2) is a first power supply device, and symbols (3) to (7)
).

az, o: i yorinari, (300) ha second tlllti
Genso fi! Consisting of 'Dot symbol (8) ~ 01) and Q5. (1aJ is the machining m pole (1) and the workpiece (
2) is the stray capacitance of the machining gap that is naturally formed at 2r- in the physical arrangement.

Next, I will explain the operation. Now pulse pause decision circuit O2
A pulse start signal is output from
When the pulse output Q of the rib (2) is set,
・The main control circuit (7) operates according to the
- The switching element (6) is turned on. Subsequently, a DC voltage E is applied from the main DC stabilized power supply (3) to the processing gap (lb) via the diode (4) and the first current limiting resistor (5), and after applying the current voltage E Within Tc seconds [machining gap (
When the insulation of IIIJ is broken down, a discharge current flows and discharge machining begins. The main switch at this time... CHIg element (6
) and auxiliary switch...The operation timing of the J-ching element 00 is set to 1 in (I) and (h) of Fig. 5(a), and the machining gap (
Figure 5 shows the relationship between the heavy pressure waveform (hereinafter referred to as the voltage waveform between electrodes) and the current waveform (referred to as the D small electrode distance t and the original waveform) of 111).
At this time shown in (II) of C) and (11) of (d), the impulse-like υf pressure output from the auxiliary DC stabilized power supply (8) is caused by the discharge detection circuit 0υ, as will be described later. The above-mentioned machining gap (11) detects the discharge flow flowing through the gap and sends this detection signal to the auxiliary control circuit 0)).
Inactive, that is, auxiliary switch... Ching element 00 is 0F
Fiζ so that the impulse voltage is not superimposed on the pulse voltage of the main DC stabilized power source (3), and is applied to the pulse chamber of the main DC stabilized power source (3) via the current limiting resistor (5). Electric discharge machining using only pressure must continue.

However, if the discharge due to the pulse heavy pressure E of the main DC stabilized power supply (3) starts for the above Tc seconds in the machining gap (lh month ζ >'x f), fC, the discharge detection circuit surface Since the discharge current is not detected, the auxiliary control circuit (1
υ becomes operational, and after the lapse of Tc seconds, an activation signal for the auxiliary switching element OO is output from the auxiliary control fault 1 path 01).

Next, the auxiliary switch element 00 (JN17y2,
Via the second current limiting resistor (9) (, 7), an impulse-like ?ff pressure is superimposed from the auxiliary countercurrent stabilized power supply (8) to the pulsed fly E of the main DC stabilized power supply (3). ], the machining gap +71 insulation is broken and the current begins to flow in the winter and the discharge current.Subsequently, the discharge detection circuit 09 detects the discharge current, and this detection signal causes the Ijrh of the auxiliary control circuit 0]) Stop the work Korokoku auxiliary switch switch element 00
Also becomes OFF. Then, the pulse voltage E of the main DC stable low current ann (3) is passed through the current limiting resistor (5).
, 7*i7. Staggering lightning processing continues.

Next, when the pulse rest determination circuit (2) outputs a rest signal (signal to stop the pulse), the free-turn flow...
30) The pulse output Q is reset and read, and at the same time the main control circuit (7) becomes inactive due to the reset signal, the main switching element (6) also goes to zero. Ii"F6. As a result, the pulse chamber pressure E applied for 11J!tlb months during machining becomes zero, and the machining gap (1h) recovers insulation (
・Discharge for one pulse ends. The dried sui at this time...
・Chinging element (6) Auxiliary switch Ching element (10
The operation timing is shown in Figure 5 (a3 (+1) and (b) (1)), and the relationship between the electrode current waveforms is shown in Figure 5 (c), f) (1) and (d) 01 (11). This is shown.

The auxiliary control circuit 0υ is activated after the above-mentioned Tc seconds have elapsed, with a pulse width sufficiently narrow compared to the minimum pulse width used for electrical discharge machining, and a value high enough to destroy the insulation in the machining gap (1h). The impulse-like voltage is connected to the second current-limiting resistor (
9), the pulse chamber pressure E of the main DC stabilized power source (3) is applied in a superimposed manner from the auxiliary DC stabilized power source (8).

In addition, (II) in Figure 5 (a) and (+111
．． (e) (IUI, (di +n).

shows the operation timing of the main switch N7 switching element (6), the auxiliary switch, and the switching element 00 when the discharge WL current does not flow even if an impulse voltage is applied by the operation of the auxiliary switching element αO, and the vehicle pressure between poles. The waveform and inter-electrode current waveform (not flowing) are shown.

[Problems to be solved by the invention] Since the conventional device is constructed as described above, the pulse voltage E output from the power supply device (b) is not applied to the machining gap (1bJ + 7"). If the start-up does not occur even after applying the pulse voltage S, an impulse-like voltage is superimposed and applied from the second power supply device 1800 to the pulse voltage E at Tc seconds after the application of the pulse voltage S, and the machining gap (IbJ Therefore, the above-mentioned impulse-like voltage is superimposed on the pulse voltage E output from the first power supply device (b), and in this case, ,
The above-mentioned impulse-like voltage is charged in the floating capacitor k (laJ) before the discharge starts, and is supplied from the first m-type device t (b) to the machining gap (1b) at the same time as the dielectric breakdown of the machining gap (1b). Because the discharge current is discharged in the direction that the stray capacitance [1aJ is charged and 1 charge is added,
A discharge starting current with a large differential wave shape flows.As a result,
If the discharge energy is large, especially for the workpiece (2)
) If the surface roughness of the machined surface is finely machined, the desired fine machined surface cannot be obtained. 1 piece.

This invention was made in order to solve the problems mentioned above.
This allows for finer OI roughness on the machined surface of the workpiece, as well as electrical discharge machining that reduces the electrode wear rate pζ
The purpose is to obtain an electrical discharge machining device.

[Means for solving the problem] The electric discharge machining apparatus according to the present invention includes a 101st power supply device that supplies a pace pulse pressure to the machining gap, and a base pulse power source of the power supply device. A second power supply device is provided which applies a voltage after a certain period of time from the time of application, and the output of the second IN controller is connected to the first power supply device.
O) Superimpose on the output of the Roux device 7, the second ? After generating the output voltage of the IK output device Q1, the output type a: is set to 6, which increases with time, and T is also OI.

[Effect]

In this invention, since the output voltage of the second IIE source device applied in a superimposed manner to the output voltage of the first power source device increases with time, discharge starts at the minimum applied voltage suitable for the state of the machining gap. do.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the same reference numerals as in FIG. 4 indicate the same or corresponding parts, and the explanation will be omitted.

+887 to (8d) are the first to fourth auxiliary DC stabilized power supplies, (9a) to (9d) are the second to fifth current limiting resistors,
(10aJ to (10d) are the first to fourth auxiliary switching elements, and α→ is the pulse stop determination circuit (2) that outputs a pulse start signal, which causes the pulse of the free flow rib (to) From the moment when the output Q is set and set, Tc
After 1 second has elapsed, the one-shot multivibrator outputs logic 1, 00 is an AND gate that takes the logical product of the output of the discharge detection circuit (to) and the output of the one-shot multivibrator α, ( 16aJ is a NOR gate that performs the negation of the logical sum of the pause output of Furi Lipflo Tsubu 0 and the output of the AND gate αG, and 0η is the NOR gate that
09 is an oscillation circuit that starts oscillation by the output of the multivibrator 0, and (to) is a 2AND gate that inputs the output of the oscillation circuit aη to the counter 0LJ by the output of the multivibrator 0→. A counter that is controlled by an AND gate (to) and counts the output of the oscillation circuit αη, and a decoder that is counted by the counter 09 and converts the number of output pulses of the oscillation circuit θ′7) into a decimal number. Qυ is the output of the decoder (A) and the first to fourth auxiliary switching elements (10s to tl
This is a driver that controls ON and OFF of od). <2
00) is an auxiliary control circuit consisting of symbols 04 to Qυ.

Further, (300) is a second power supply device, and is denoted by code (8a).
~(8d), L9a) ~I9d), (1
0aJ ~flOd) (200).

Figure 2 is Wang Sui, Lichinku Motoko (6) &! The operation timings of the first to fourth auxiliary switching elements (10th to flOd, l are set to (a) to (e), and the main switch...
The switching element (6) and the first to fourth auxiliary switching elements (10aJ to (10dJ) are shown in FIG. , as shown in (g).

Next, the operation will be explained. After applying the base pulse voltage, the operation is the same as that of the conventional device until the insulation of the machining gap (1 h) is broken within 1 Tc seconds after application of the base pulse voltage and the electric discharge machining is started. . When the same operation as the conventional device described above is performed, the first to fourth auxiliary DC stabilized power supplies (8aJ to (8d ) through the second to fourth current limiting resistors (9a) to (9d), the main DC stabilized power supply (
The voltages Ea to Ed that are output from 3) and superimposed on the Z pulse voltage E are not output, and the main DC stabilized power supply (3)
The discharge by the pulse voltage EO+ continues.

However, if the discharge due to the pulse voltage E of the main DC stabilized power supply (3) is not started within 10 seconds with the machining gap N, h months, and the discharge current is not flowing, so the counter is 0 through the AND gate (1G, No Agate 16a) e.
1. In order to release the reset of the decoder (1), the counter 0I and the decoder (E) are in an operable state (in this state). Therefore, To seconds have elapsed since the pulse start command was output from the pulse stop decision circuit (A). Later, the output of the one-shot multivibrator α force becomes logic 11ζ, and the oscillation circuit αη
The AND gate (to) is opened and the pulses from the oscillation circuit Q7 are input to the counter 0.

Next, the output from counter 09 or the decoder wire is set to 1.
By operating the driver Qυ corresponding to the number of clock pulses from the oscillation circuit αη, the auxiliary switches +l chinking elements (1oa) to (10d
) is controlled ON and OFF. The above operation is performed using the machining gap (l)
After h months, the number of clock pulses input from the oscillation circuit αη to the counter ← is 1- until the discharge starts.
Since it increases from 2-8 to 4, the auxiliary switching element (10a) to t10dJ also (]Oa
J -ttoJ -tlOs, tlOdJ and ON l, shifting sequentially. Taking this state as an example of the undischarged state, (1) in Fig. 2(a) shows the operation of the main switch notching element (6), and in contrast to this operation, (b) (
I), (c) (1), (d) (1), (11
11 (1) shows how the first to fourth auxiliary switching elements (1 (11 to tlOdJ) are sequentially shifted after Tc seconds have elapsed, and then are switched, and the polarity at that time is shown. In this case, as shown in (1) of (g), no discharge current flows, so the current waveform between electrodes does not appear.

As explained above, in this case, the pulse voltage E of the main DC l electrification power source (3) applied to the machining gap (lh) is taken as the base voltage, and the auxiliary switching element ( ) is 0.
N17) when E+Ea, auxiliary switch auxiliary steng element (10
b) is ON, +> E+Eh+Eb, auxiliary switch =, auxiliary switch (10 switch is ON, E+Ea+Eh+Ec.

Auxiliary switch 11. Tengu element (E+E when 10dJ goes to O
The DC voltages a0Eh+Ec+Ed are superimposed.

As mentioned above, the main switch = L tink element (6) and the first to fourth
Since the auxiliary switch +/J switching element 110aJ ~ (10dJ operates, the above base voltage E
f commensurate with the state of the machining gap (1b), and the voltage Ea of the first to fourth auxiliary DC stabilized power supplies (8a) to (8d)
When -Ed is applied, the insulation of the machining gap 1]hJ is broken and electric discharge is started. Next, the discharge is started, and in this case, the discharge detection circuit α9 detects the machining gap (1h).
Detects the discharge current and resets the counter α decoder wire through AND gate αQ and NOR gate t16aJ.
Since the output from the driver Qυ is turned off, all auxiliary switching elements (10a) to (10d) are also turned off.
It becomes F. Then, only the pulse voltage E of the main DC stabilizing Wl source (3) is continuously applied to the machining gap 11hJ via the first current limiting resistor (5). Continue to supply the discharge current limited to a predetermined value by t.

Next, when the pulse pause determination circuit (2) receives the I'lt* stop signal or the ratio signal, the output of the free flow knob α3 is set to the pause side Q, and conversely, the pulse side Q is set to the recycle mode. At the same time, the main control circuit (7) turns off the switching element (6) according to the reset command (0), and at the same time turns off the counter O through N (JIL gate t16a).
1 and Tekota CA. Therefore, the machining gap (
The voltage applied during this period becomes zero and the insulation is restored.

The above operations are performed in (II) and (l) in Fig. 2 (a) to (e).
7) as shown in I).

As mentioned above, the voltage applied to the machining gap (1bJ) is the base pulse voltage applied to the first to fourth auxiliary DC stabilized power supplies superimposed on the pulse voltage E of the main surface current stabilized power supply (3). (8a1~(8dJ voltage Ea-Ed becomes a voltage waveform that increases with time. Therefore, the discharge is caused by the machining gap (
We will start with the minimum value of 1 that meets condition 1b).

As a result, the voltage applied to the stray capacitance (1a) will also be the minimum value mentioned above, so the electric charge charged to the stray capacitance (1a) will also be the minimum value. At the start of discharge, the machining gap (
The discharged current also becomes minimum in November. Therefore, the size of the machining gap (lh) or the machining gap (1h
Even if there is a difference in the ion concentration between Can be done.

In the above embodiment, the number of auxiliary DC stabilized power supplies is four, but it is obvious that this number needs to be particularly limited.

In addition, in the above embodiment, voltages from a plurality of auxiliary DC stabilized power supplies that increase stepwise with time are superimposed on the base pulse voltage applied to the machining gap. Even if it increases in the form of a straight line or in the form of another function, the same effect as in the above embodiment can be achieved.

- As an example, FIG. 8 shows an embodiment in which T increases continuously over time in the form of a straight line. In the figure, (a) is a circuit diagram of one example, (1) in (b) and (C) is when discharge is not performed, and (II) in (b) and (C) is when discharge starts at a low applied voltage. 1 at this time, and (h) and (0) (1
) shows the inter-electrode voltage waveform and inter-electrode current waveform at one time when discharge starts at a high applied voltage.

〔Effect of the invention〕

As described above, according to the present invention, the output of the second power supply device is superimposed on the output of the first power supply device, and the output of the power supply device is configured to increase with time. This eliminates the possibility of charging more charge than necessary to the stray capacitance existing in the gap. Therefore, since the current discharged from the stray capacitance into the machining gap can be minimized, the surface roughness of the machined surface of the workpiece can be made finer and the electrode consumption rate of the machining electrode can be minimized. It is effective if you get it.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a power supply device of an electric discharge machining apparatus showing an embodiment of the present invention, and Fig. 2 is a circuit diagram of an embodiment of the present invention (operation timing chart of the switching element, voltage between electrodes, and FIG. 8 is a circuit diagram of another embodiment of the present invention and a waveform diagram of inter-electrode voltage and inter-electrode current, FIG. 4 is a circuit diagram of a conventional device, and FIG. 5 is a switch diagram of a conventional device. , is an operation timing diagram of the soching element, and a waveform diagram of the inter-electrode voltage and inter-electrode current. In the figure, (1) is the processing electrode, (2) is the workpiece,
(b) is the first power supply device, (200) is the auxiliary control circuit,
(800) is a second power supply device. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A first power supply device that applies a base pulse voltage to a machining gap formed between a machining electrode and a workpiece;
a second power supply device that supplies a voltage after a certain period of time from the time when the base pulse voltage is applied to the power supply device, the output of the second power supply device being superimposed on the output of the first power supply device,
An electric discharge machining apparatus that performs machining while generating intermittent pulsed discharge, characterized in that the electric discharge machining apparatus is provided with a control means for increasing the output voltage over time after the output voltage of the second power supply device is generated. (2) The control means includes a plurality of DC stabilized power supplies, a plurality of switching elements that switch voltages of the plurality of DC stabilized power supplies via a plurality of resistors, and ON/OFF control of the plurality of switching elements. 2. The electric discharge machining apparatus according to claim 1, further comprising an auxiliary control circuit for controlling the electric discharge machining process.