JPH04127967A - Electric source apparatus for electric discharge weld-sticking stud - Google Patents

Abstract

PURPOSE:To make transposition and weld-sticking of electric discharging point melted part under keeping melting condition without vaporizing and splashing by arranging a control circuit for executing slow-up or slow-down control in timing to rising or falling characteristic of the wave form in the pulse-state electric discharging current in order. CONSTITUTION:The pulse of on-pulse width and off-pulse width set with alternate operation of on-time counter and off-time counter, is outputted and in the on-pulse, switching current is overlapped by successive operation shifting the time of each parallel switch 4a-4n to form current pulse wave form rising in slow-up step and the current pulse is supplied to working gap 9 through an inverter transformer 7. That is, the output pulse in the inverter transformer is transformed to the prescribed value and rectified with a rectifier 8 and supplied to the working gas 9 as simple direction pulse.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is for an apparatus that welds and coats an electrode material or a powder material on a base material by utilizing electric discharge between an electrode and a base material, or performs overlay processing. This invention relates to improvements in a power supply device for supplying discharge pulse current.

[Conventional technology]

Conventionally, a chip-shaped or rod-shaped electrode is moved back and forth minutely along the surface of a substrate to be processed, or rotated, and then brought into contact with and released from the substrate, and at the same time a pulse discharge is generated between the electrode and the substrate. A deposit operation is performed in which the molten part of the electrode material is transferred and welded onto the base material using the discharge heat, and this electrode is slowly and continuously moved over the base material surface to form a uniform coating over the entire surface of the base material. A known electrical discharge coating method has been proposed in which the thickness is approximately 10 μm to 50 μm.

[The problem that the invention attempts to solve]

The reason why the thickness of the coating layer cannot be increased in such welded coating or stud processing is that the discharge point of the electrode, which has a small heat capacity relative to the base material, melts due to the impact of the discharge heat, and the melted portion Either it scatters with some evaporation, or because a sine wave or square wave is used as the waveform of the conventional discharge pulse current, the amount of welding decreases because more of the melted part scatters, and when welding repeatedly, This method has the disadvantage that it is difficult and inefficient to increase the thickness of the coating layer or the height of the protrusions, since even previously welded materials are scattered.

[Means for solving problems]

The present invention was invented in view of the above points, and the present invention is based on a method of sequentially slowing down the rise or fall characteristics of the generated discharge pulse current in a discharge power source that generates a pulse discharge between an electrode and a base material. - It is characterized by the provision of a control circuit that performs knob or slowdown control.

The control circuit includes an inverter transformer that transforms the pulse current generated by the on/off switching operation of the high-frequency high-speed switch, and a rectifier circuit that rectifies and stores the output of the transformer and applies it between the electrode and the base material. It is recommended that a plurality of the high-frequency high-speed switches are provided in parallel, and control pulses for operating the plurality of high-speed switches are sequentially supplied at staggered times.

[For production]

In the present invention, the rise or fall characteristics of a pulsed discharge current are sequentially slowed down or slowed down in time, so that the discharge current can be controlled by the heat conduction characteristics of the melted part of the electrode material at the discharge point. The flow can be controlled to correspond to the flow rate, and as a result, the molten portion at the discharge point can be transferred and welded to the base material while maintaining the molten state without being evaporated. Therefore, the efficiency of welding coating and welding build-up is improved, and thick coatings and tall protrusions can be easily formed.

In other words, in electrical discharge coating and stud processing, the discharge point of the electrode material is melted and transfer-welded to the base material, so it is necessary to efficiently melt the electrode material at the discharge point by electric discharge. There is no point in letting what you have evaporate or scatter.

Generally, the melting of the discharge point occurs when the current density reaches a certain value, and the movement of the melted part is expressed as a function of t1'',
Moreover, since it is known that it is proportional to the thermal diffusion coefficient, it is necessary to control the discharge current so that it does not exceed this value. If this is suddenly applied with a large current in a short period of time, the molten part will be further heated, causing evaporation and scattering, before the heat has diffused.

For example, in the case of iron material, if the current density is 360 A/mm2, it will melt (1530°C) and 490 A/mm2 will evaporate (L).
2700°C).

Therefore, the present invention attempts to control the temporal characteristics of the discharge current so that the discharge point is sufficiently melted or is still in a strongly welded state and does not evaporate and scatter. In the present invention, the welding efficiency can be significantly improved by transferring and welding the molten portion that does not scatter to the base material by contact separation. According to the present invention, it is possible to create a sharpness of 100 μm or more, 500 to 1000 μm, and it is also possible to coat carbide abrasive grains such as DIA or CBN.

〔Example〕

Hereinafter, the configuration of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing an embodiment of a power supply device for discharge welding overlay according to the present invention, and FIG. 2 shows an embodiment of a control circuit portion forming a part of the circuit shown in FIG. 1. Circuit diagram, (a) (bl (c) of FIG. 3 is an explanatory diagram showing a typical example of the waveform of the discharge pulse current obtained by the power supply device for discharge welding and overlay according to the present invention, and FIG. 4 is the same as that of FIG. 1. A circuit diagram showing another embodiment of a control circuit portion forming a part of the circuit shown in FIG.
FIG. 5(a) (bl fc) is an explanatory diagram showing a typical example of the waveform of the discharge pulse current obtained by the control circuit shown in FIG. 4.

Therefore, in the circuit diagram shown in Fig. 1, 1 is an input switch,
2 is a filter, 3 is a power rectifier, 4a, 4b.

=, 4n are FET high-frequency high-speed switches that turn on and off the DC power supply at high speeds of 500 KHz to IMKH.
, ..., 5n connected in series are connected in parallel to control current on/off switching. Reference numeral 6 denotes a control circuit that sequentially supplies control pulses with time differences to each switch 4a, 4b, . . . 4n, and has a circuit configuration as shown in FIG. 2 in detail. Reference numeral 7 denotes an inverter transformer that transforms switching pulses and outputs them to the machining gap. A high-frequency transformer is used, the output of which is rectified by a rectifier circuit 8, stored, and the voltage pulses are transmitted to the machining gap 9 between the electrode and the base material. Apply. 10 is a motor that rotates the electrode, 11 is a torque sensor for the rotating electrode support shaft, and 12 is a current detection resistor for the discharge circuit.

FIG. 2 shows a concrete example of the control circuit 6. For example, 61 is an n-ary counter, a shift register, a ring counter, etc., which counts clock pulses sent from a clock pulse oscillator 62 and sequentially outputs signals to output terminals. do. Each output signal passes through a selection circuit 63 and a flip-flop 64a,
The signal is held by inverting 64b, . . . , 64n. The output of each flip-flop is supplied to each switch 4a, 4b, . . . , 4n in FIG. The clock pulse from the oscillator 62 is input to the n-ary counter 61 through the gate 65, and the pulse width setting signal from the flip-flop 68 is input to the other input terminal of the ant gate 65. 66 is an on-time setting counter, and 67 is an off-time setting counter, both of which count clock pulses from the oscillator 62 and output a count selection value by a switch.

68 is a flip-flop which is inverted by the outputs of both counters 66 and 67, and supplies this Q output to the AND gate 65. Inverted Q output of flip-flop 68.

The one-shot multi 69 is activated by the force to output a reset signal, thereby resetting the n-ary counter 61 and each of the flip-flops 64a to 64n. Reference numeral 71 denotes a discrimination circuit for discriminating the detection signal of the torque sensor [J], which issues a reset signal when the torque signal increases above a predetermined value.
1 and flip-flops 64a-64n.

In the above circuit configuration, first, the count numbers of the on-time counter 66 and the off-time counter 67 are set in accordance with the machining conditions. Now, if an off-time signal is output from the off-time counter 67, the flip-flop 68 is inverted to set Q to "I", and the AND gate 65 is opened to input a clock pulse to the n-ary counter 61. The n-ary counter 61 sequentially outputs a step signal to the selection circuit 63 by counting clock pulses, and the selection of this step signal sequentially inverts each of the flip-flops 64a to 64n and is held in each flip-flop. Signal or each power switch 4a to 4n
It joins and drives. Since the switches 4a to 4n are sequentially turned on and then maintained in the on state, the switching currents are sequentially superimposed at different times, and the current value has a stepped waveform.
is supplied to the machining gap 9 through the rectifier circuit 8. On the other hand, simultaneously with the operation of the n-ary counter 61, the clock pulse of the oscillator 62 is also applied to the on-time setting counter 66,
The counter 66 counts this value, and when it counts up to the set value selected by the switch, it sends a signal to the flip-flop 68 to invert it and output a Q output of "1" or a one-shot mark.

The circuit 9 is activated to output a reset signal, and the n-ary counter 6I and flip-flops 64a to 64n are reset to complete the on-pulse. Also, flip-flop 68
The Q output resets the off-time counter 67, so from this point on, the counter 67 counts up to the set value and then sets the off-time until the flip-flop 68 is inverted again. During this off time, flip-flop 6
Since the Q output of No. 8 is "0" and closes the AND gate 65, the n-ary counter 61 maintains a resting state without counting. In this way, by alternately operating the on-time counter 66 and the off-time counter 67, pulses with the set on-pulse width and off-pulse width are output, and the on-pulse is used to control the switching current by sequentially operating the parallel switches 4a to 4n at different times. A current pulse waveform that is superimposed and slows up stepwise is formed, and this current pulse is supplied to the machining gap 9 via the inverter transformer 7. That is, the output pulse of the inverter transformer is transformed to a required value, rectified by the rectifier 8, and supplied to the machining gap 9 as a unidirectional pulse.

FIG. 3 is a waveform diagram of the pulse current subjected to slow-up control as described above, and (a) shows the sequential output of the n-ary counter 61, which is outputted at equal intervals by the selection circuit 63, and is outputted at equal intervals by the parallel high-speed switch 4a. 4n sequentially driven at equal time intervals, (b) shows the discharge pulse current waveform when the signal supplied to the third high-speed switch is selected and set to delay by two steps, (C ) The figure shows the discharge pulse current waveform when the signal supplied to the fourth high-speed switch is selected and set to be delayed by two steps. In this way, the slow-up control of the pulse current can be arbitrarily controlled by selecting the signal of the selection circuit. Moreover, it can be easily controlled, and these pulse current waveforms are adjusted according to the thermal characteristics of the electrode material and other processing conditions. or,
The on-pulse width can be arbitrarily controlled by adjusting the on-time setting counter 66. When the on-time is completed, the flip-flop 68 is inverted and a reset signal is output from the one-shot multi 69. Counter 61 and each flip-flop 64a
-64n and turn off each high-speed switch 4a-4n.

Note that when the torque sensor 11 detects that the rotational torque of the electrode is within a predetermined value or less, the output of the discrimination circuit 71 is "0", and the alternating operation of on-pulse and off-pulse continues, or the electrode is connected to the base material. Torque increases as it comes into pressure contact with
When the value increases from a predetermined value preset in the discrimination circuit 71, the output of the discrimination circuit 71 changes to "1", and this signal is sent to the OR gate 70, which resets the n-ary counter 61 and the flip-flops 64a to 64n. From then on, the pulse current to the machining gap is stopped. In this way, it is possible to control the machining to continue only within the range of stable rotational torque conditions, and when the electrode is in an unreasonable pressure contact with the base material, energization is carried out and excessive electrode material is removed. Can prevent dissolution, evaporation, and scattering.

FIG. 4 shows another embodiment of the control circuit 6 in FIG. 1, in which 72 is a preset counter for setting the on-pulse up time, 73 is a preset counter for setting the down time, and 74 is for setting the off time. The preset counter 75 is a ternary counter that counts the output of each preset counter 72, 73, and 74.
, has an OFF output terminal, and sequentially UP - DOWN -
It circulates to +OFF and outputs a signal. 76 is n-ary UP/
DOWN counter, when signal “1” is applied to S terminal, U
It counts P, and switches to DOWN counting when the signal is "0". This signal output is applied to the flip-flops 64a to 64n through the selection circuit 80 and controls the on/off switching of the high speed switches 4a to 4n shown in FIG. 1 to generate machining pulses.

Now, each preset counter 72 is set by the initial value setter 85.
．． 73.74 is reset and counter 75.76 is reset, this causes the output of counter 75 to become U.
Outputs the signal “1” to the P terminal and the n-ary counter 76 goes up.
It becomes a counter and counts up the clock pulses of the clock pulse oscillator 62. The n-ary counter 76 sequentially outputs step signals to the selection circuit 80 by counting clock pulses, and the selection of the step signals causes each flip-flop to be changed from 64a to 64b to .
64n, and the signal protected by each flip-flop sequentially drives each high-speed switch 4a to 4n (FIG. 1). Each switching current is superimposed with a sequential time shift, and a stepwise slow-up current is supplied to the machining gap. On the other hand, the clock pulse oscillator 6
The clock pulse from 2 is the preset counter 72°7
3 and 74, the AND gate 82 is opened by the initial value setter 85 to drive the preset counter 72 for setting up time, and when the count reaches the set value, the signal is added to the ternary counter 75 through the OR gate 81. The ternary counter 75 advances l steps and outputs a signal “l” to the DOWN terminal.
" is output and the tJP terminal is set to "0", so the n-ary counter 76 is switched to a DOWN counter, and the selection circuit 80
can also be switched to DOWN. As the n-ary counter 76 counts down, a step signal is sequentially outputted to the selection circuit 80, and by selection of this step signal, each flip-flop is reset in the order of 64n→...→64b→64a. At this time, the signal "1" from the DOWN terminal of the ternary counter 75 is input to the (B) terminal of the AND gate 83 to open the gate 83, and the clock pulse from the oscillator 62 is input to the downtime setting preset counter 73. and will be counted.

When counting up to the set value, the signal issued from the preset counter 73 passes through the OR gate 81 and is applied to the ternary counter 75, which outputs "1" to its OFF terminal by step counting. This signal passes through the OR gate 79 and enters the negative logic input terminal of the ant gate 77, so at this time the gate 77 is closed and the clock pulse from the oscillator 62 is not input to the n-ary counter 76, which remains reset. All switches 4a to 4n maintain an off state.

Therefore, at this time, the supply of pulse current to the machining gap 9 is stopped and the off state is maintained. This pause time width is determined by the count time of the off-time setting preset counter 74, and the preset counter 74 outputs a signal "l".
When the signal is outputted, it is added to the ternary counter 75 via the OR gate 81, and the ternary counter 75 performs a step-up reset and outputs the signal "l" to its UP terminal, and switches the n-ary counter 76 to the UP counter again to generate a clock pulse. It counts and performs slow-up control of the pulses supplied to the machining gap. Preset counter 72 for uptime setting
When the count reaches the set value, the n-ary counter 76 is switched to the DOWN counter by switching the ternary counter 75 to perform slowdown control, and when the down time setting preset counter 73 counts up to the set value, the preset counter 74 The pause time width is set to a predetermined value by control. Thereafter, the same operation is repeated, and the on-pulse of slow-up and slow-down and the off-pulse of a predetermined pause width are repeated alternately, and the high-speed switches 4a to 4n activated thereby produce the predetermined slow-up and slow-down characteristics and pause. A pulse current having a width is supplied to the inverter transformer 7, and its output is rectified by the rectifier circuit 8 and then supplied to the machining gap 9, generating a pulse discharge between the rotating and moving electrode and the base material, and causing the base material to On the other hand, welding and coating of electrode materials, overlay processing, etc. can be carried out efficiently.

FIG. 5 is a waveform diagram of pulse currents subjected to slow-up control and slow-down control, and (a) shows the selection circuit 80.
Discharge pulse current waveform when on-pulse slow-up and slow-down are equally controlled by selection control of
(b) Figure shows the discharge pulse current waveform when controlling the slow-up to be very rapid and the slow-down to be slow.
) The figure shows a discharge pulse current waveform when only the slowdown is controlled, and by selective adjustment of the selection circuit 80, the slowup and slowdown of the on-pulse can be arbitrarily controlled.

Further, the on-pulse width and off-pulse width can be controlled by each preset counter 72, 73 and 74. Such slow-up and slow-down control is adjusted according to processing conditions such as the material and type of the covering electrode material. control to efficiently melt. The molten part at the discharge point is kept in a welded state so that evaporation and scattering does not occur, and the molten material is removed efficiently (
The pulse current waveform is controlled to transfer and weld to the base material.

For example, using an electrode material of WC balance B8% Fe fiber 6%, pulse discharge is performed while lightly touching the steel base material while rotating at 11000 RP, and the electrode material melted by the discharge heat is projected at a predetermined positioning point. When machining studs to build up the shape, the discharge pulse to be supplied is controlled at t1'' so that the pulse current is 35A during the period from 0 to 25 μs, and at t1'' during the period from 25 to 4511 seconds.
Keep constant at 5A, 45-55. During the period m, when processing was repeated to cut off pulses from 35A to 0, it was possible to raise the protrusion to a height of about 0.8 mm.

In addition, when continuously welding and coating the surface of the base material with electrode material, the discharge pulse is controlled at 11'2 to 15A during the period from 0 to 20μs, and at 15A during the period from 20 to 25IIs. When held constant and then immediately cut off, a coating layer with a thickness of about 33 μm and a surface phase of about 13 Rmax was obtained.

Note that any control circuit other than the illustrated embodiment can be used as the control circuit that sequentially temporally slows up or slows down the rise or fall time characteristics of the discharge current. In addition to digital control, continuous analog control is also possible.

In addition, it is desirable that the slow-up and slow-down characteristics be controlled depending on the type of electrode material used and the type of workpiece.
In the BN system, both UP and DOWN are controlled with respect to the area of the workpiece.

〔Effect of the invention〕

As described above, the present invention has a chip-shaped or rod-shaped electrode and a base material facing each other, and the electrodes are not moved along the surface of the base material, but the two are kept in contact with each other or kept at a constant distance. A power supply device for pulse discharge used in a device that transfers and welds an electrode material or a powder material separately supplied to the tip thereof onto the surface of a base material little by little by means of the discharge heat and overlays the surface of the base material by generating a pulse discharge. In the
Since a control circuit is provided that sequentially slows up or slows down the waveform rise or fall characteristics of the pulsed discharge current that causes the discharge, it can be slowed down or slowed down depending on the material of the covering electrode material. The discharge current can be controlled to correspond to the heat transfer characteristics of the molten part at the electrode discharge point, thereby preventing the molten part from evaporating and scattering. It can be transfer-welded to a base material that remains molten. For this reason, the efficiency of welding coating and welding build-up is greatly improved, and it becomes possible to easily form thick coatings and high protrusions.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a power supply device for discharge welding overlay according to the present invention, and FIG. Circuit diagram shown, 3rd
Figures (a), fb, and (c) are explanatory diagrams showing typical examples of the waveform of the discharge nozzle current obtained by the power supply device for discharge welding and overlay according to the present invention, and Figure 4 is the same as that shown in Figure 1. A circuit diagram showing another embodiment of the control circuit portion forming a part of the circuit, and (a), (b), and (C) in FIG. 5 are the waveforms of the discharge Noculus current obtained by the control circuit shown in FIG. 4. It is an explanatory diagram showing a representative example. 1...-----------------
Input switch 2-・−・−・−・・−・・−−
1-...- Filter 3----------------
・−・・・・−・−・Power rectifier 4a, 4b,
~4n・-・・・・・−・・・・High frequency high speed switch 5a, 5b, ~5n・−・−・−・・−・−・・
・Current limiting resistor 6−・・−・・−・−・・・・・・・−・
・・−・・−・・Control circuit 7−・−・・−・・−
・・−・・−・−・−Inverter transformer 8−1 ・・−
−−−−−・・−・・−・Rectifier circuit 9−・−・・
−・−１１−−−−−−−・−・・−・Machining gap IO−
・−・−−−−−m−−−・−・−・・−・Rotating motor 11−−1・−−−−1・−・−−1−−−−・−
Lux sensor 61...------...--1------
−−−−・・−・・N-ary counter 62・・・・−・・
・−・−・−・・−・−−−−−・・Clock pulse oscillator 63 −・・・・−・・・−・・−・−・−・Selection circuit 64a, 64b, ~64n− −Flip-flop 65−・・・・−・−・・−・−・−・
AND GATE 66-・-・・−・−−−m−−・−・
-...-On time setting counter 67-...-
−1−−・・・−・・・−・・・−・−・Off time setting counter 68・・・・−・・・〜・−・・−−−−
−−1−・−・Flip-flop 69・・・・−−
−1−・・−・−・−・・・One shot multi 70−・・−・−・−・・・−・・
・・−・・Or Gate 71−・−・・−・・・
・・・・・・−・・Discrimination circuit 72 −・・・・−・−
・・−・・−・・−・−・−・Preset counter 73 for uptime setting・−・−・・・−・・−・・−・・
−・・・・Preset counter 74 for setting down time −・−・−・・・−・・−・−・・・Breset for setting off time 77.78 −−−−・82.83.84-... 86.87.88...--Counter Ternary counter N-ary UP/DOWN counter ---And gate OR gate Selection circuit OR gate...AND Gate initial value setter - - - - - ORGATE Patent applicant: Representative of INR Research Institute Co., Ltd. (7524) Mogami Shotabu Time Time Time Time

Claims (1)

[Claims] 1) A chip-shaped or rod-shaped electrode and a base material are made to face each other, and while the electrode is moved along the surface of the base material, the two are kept in contact with each other or kept at a constant distance between them. By generating a pulse discharge, the electrode material or the powder material separately supplied to the tip thereof is transfer-welded and deposited on the surface of the base material little by little by the discharge heat. The above-mentioned discharge welding overlay is provided with a control circuit that sequentially slows up or slows down the rise or fall characteristics of the waveform of the pulsed discharge current that causes the discharge. power supply. 2) An inverter transformer (7) that transforms the pulse current generated by the on/off switching operation of the high-frequency high-speed switches (4a to 4n), and a rectifier circuit that rectifies and stores the output and applies it between the electrodes and the base material. (8), a plurality of the high-frequency high-speed switches (4a to 4n) are provided in parallel, and a control circuit (6) is provided that sequentially supplies control pulses for operating the plurality of high-speed switches at staggered times.
) The electric discharge welding overlay power supply device according to claim 1, further comprising: a.