JPS6255954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a short-circuit transitional arc welding machine that performs welding by frequently repeating short-circuiting and arc generation between a wire electrode (hereinafter simply referred to as "wire") and a base material. It is.

A prior art arc welding machine of this type is shown in FIG. In the figure, 1
is a wire, 2 is a base material that is the object to be welded, 3 is a wire feeding motor for feeding the wire 1 in the direction of the base material 2, 4 is a torch through which the wire 1 passes, and 5 is a rectifier of three-phase alternating current. A DC power supply circuit, 6 a switching element such as a transistor for turning on and off the output voltage of the DC power supply circuit 5, 7 a reactor, 8
1 is a flywheel diode for circulating the energy stored in the reactor 7 immediately after the switching element 6 is turned off; 9 is a voltage detector for detecting the voltage between the wire 1 and the base material 2;
0 and 11 are first and second comparators for comparing the arc voltage detected by the voltage detector 9 with a predetermined voltage value, and 12 is for giving a delay time T to the signal from the comparator 11. A timer 13 receives an ON command from the comparator 10 and an OFF command from the timer 12, and a switch command circuit for instructing the switching element 6 to turn ON or OFF; 14 ensures the operation of the voltage detector 9; It is an auxiliary power source for

Next, the operation of this short-circuit transitional arc welding machine will be explained. First, the wire feeding motor 3 is driven to feed the wire 1 toward the base material 2 . A minute voltage is applied between the wire 1 and the base material 2 by the auxiliary power supply 14, and the voltage detector 9 detects a short circuit between the wire 1 and the base material 2 based on the voltage change.
The detected voltage V is compared with a predetermined voltage V ₀ corresponding to the short circuit voltage between the wire 1 and the base material 2 by the comparator 10, and if V≦V ₀ , the switching element is activated from the switch command circuit 13. An ON signal is issued to the switching element 6, and the switching element 6 becomes conductive. Similarly, the detected voltage V is compared with a predetermined voltage Va that is regarded as an arc voltage by a comparator 11, and if V≧Va, after a predetermined delay time T has elapsed as necessary, the switch command circuit 13 sends an OFF signal to the switching element 6, the switching element 6 is cut off, and after that, the reactor 7
The energy stored in is released via the wire 1, the base material 2, and the flywheel diode 8.
Figures 2a and 2b are current and voltage waveform diagrams during welding, and Figure 2c is a diagram showing the short circuit and arc generation between wire 1 and base metal 2.As shown in the figure, the current waveform is approximately It becomes a triangular wave.

This short-circuit transitional arc welding machine was constructed as described above, and the electrical polarity was mainly connected in reverse polarity such that the wire 1 was used as an anode and the base material 2 was used as a cathode. In the case of reverse polarity, the amount of heat input to the base material 2 is large;
Particularly in welding thin plates, phenomena of excessive heat input, such as the base metal 2 melting down, were observed. It is also possible to connect the wire 1 with positive polarity, such as using the wire 1 as a cathode and the base material 2 as an anode, but in this case, the amount of melting of the wire 1 becomes large and the bead becomes convex.
There is also a conventional method of welding by applying sine wave alternating current, but this method does not synchronize the repeated welding phenomenon of short circuit and arc generation with the applied voltage waveform. We had no choice but to try to make arc regeneration easier by making it easier.

This invention was made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a short-circuit transition arc welding machine in which the amount of penetration and the amount of excess welding can be arbitrarily varied over a wide range according to the shape of the base material. It is said that

An embodiment of this invention will be described below.

FIG. 3 is a diagram showing a circuit configuration of an embodiment of the present invention. In FIG. 3, 15 is an inverter circuit composed of power transistors 61, 62, 63, and 64, 16 is a delay time, 20 is an operation box, and 2
01 is an arc length setting dial, 202 is a wire feed rate setting dial, 203 is a polarity ratio setting dial, 21 is a pulse width setting circuit, and 22 is an output voltage signal τ of the pulse width setting circuit 21, which is converted to the average voltage converter 1.
A pulse width adjustment circuit 23 performs correction based on the output voltage signal from 9 and generates an output voltage signal τ ₀ .
1, 232 is a pulse generation circuit, 24 is a setting circuit for setting the peak current I _P0 during the arc period, 2
5 is an arc current detector, 26 is an amplifier for amplifying the output of the arc current detector 25, and 27 is for comparing the output of the amplifier 26 with the output signal I _P0 from the setting circuit 24 for setting the peak current I _P0 . , I≧I
Comparators 301 and 302 that emit an L level signal if _P0 and an H level signal if I<I _P0
is an AND circuit, and the output signal of the comparator 27, the output signal of the pulse generation circuit 231, and the output signals i and j of the polarity switch 17 are input to this AND circuit. The output signal of the AND circuit 301 is the power transistor 6 in the inverter circuit 15.
It is input to the base of 3.64. Also,
The output signal of the AND circuit 302 is the inverter circuit 1
It is inputted to the bases of power transistors 61 and 62 in 5. FIG. 4a shows the signal waveform of the output signal i of the polarity switch 17 of the present invention, and FIG. 4b shows the waveform of the arc current I. Incidentally, the output signal j of the polarity switch 17 is an inverted version of the signal waveform of the output signal i. In the figure, Q ₀ indicates the optimum amount of charge during the arc period, and the waveform of I ₀ indicated by a broken line indicates a predetermined reference pulse waveform current for obtaining the optimum amount of charge Q ₀ .

Next, the operation of the circuit shown in FIG. 3 will be explained. The output of the DC power supply circuit 5 is input to an inverter circuit 15, which switches the width of the pulse current during the arc period, the short circuit current, and the polarity of the welding arc between positive polarity and reverse polarity.

To operate the welding machine, first, the arc length setting dial 201, wire feed rate setting dial 202, and polarity ratio setting dial 203 are set to predetermined values. The pulse width setting circuit 21 inputs a target pulse width signal τ ₀ corresponding to the combination of the set arc length and wire feeding amount to the pulse width adjustment circuit 22 . At the same time, by inputting the welding average voltage signal from the average voltage generator 19 to the pulse width adjustment circuit 22, the target pulse width τ ₀ is corrected according to the average voltage signal, and the pulse width signal τ is output to the pulse generation circuit 22.
2 is input.

Correcting the target pulse width τ ₀ according to the average voltage signal is to prevent fluctuations in the arc length due to camera shake of the torch 4. That is, if the arc length attempts to lengthen due to camera shake, the average voltage signal will increase, so if this signal is used to correct the arc length so that it is slightly shorter than the target pulse width τ ₀ , the arc length will return to the original length. Furthermore, if the arc length becomes shorter, the pulse width τ may be corrected to be slightly longer than the target pulse width τ ₀ . Note that the output signal of the wire feed rate setting dial 202 is input to the motor 3,
A command is issued to feed the wire at a predetermined wire feeding speed v. The output of voltage detector 9 is sent to comparator 10
, the voltage V ₀ corresponding to the short circuit and the comparator 1
1, it is compared with the voltage Va equivalent to the arc voltage, and if |V|≦V ₀ , the comparator 10 outputs an H level output signal, and if |V|≧Va, the comparator 11 outputs an H level output signal. An output voltage is generated and input to the delay circuit 16. The delay circuit 16 takes a time delay T between input and output voltages and waveforms as necessary, and its output is input to the pulse generation circuit 231 as an L level signal and to the pulse generation circuit 232 as an H level signal. be done. FIG. 5 shows a time chart of each part I _P , i, j, k, l, m, and n when the current waveform shown in FIG. 4 was created.

In this way, the output of the pulse generation circuit 231 becomes H level when |V|≦V ₀ by the comparator 10, and becomes H level by the comparator 11 when |V|≧Va
When , it becomes L level and AND circuits 301, 30
2 respectively. On the other hand, the pulse generating circuit 232 outputs an L level when the output signal of the delay circuit 12 becomes an H level. Note that when the output signal of the delay circuit 12 reaches H level, the integration circuit built in the pulse generation circuit 132 operates, and the output voltage of this integration circuit becomes equal to the output voltage signal τ from the pulse width adjustment circuit 22. The pulse generation circuit ₂₃
The output signal of No. 2 is inverted to H level.

Therefore, during a period of τ _ns from the time when the output signal of the delay circuit 12 becomes H level, the comparator 27 compares the peak current I _P detected by the shunt with the output signal from the I _P0 setting circuit 22, If I _P0 > I _P , an H level signal is output, and if I _P0 < I _P , an L level signal is output.
Outputs a level signal. In addition, in other periods,
The output of the comparator 27 is at the L level because the H level signal from the pulse generating circuit 232 is input to the comparator 27.

In addition, the welder can set the polarity ratio setting dial 2 in the operation box 20 according to the welding conditions such as the shape of the base material and the plate thickness.
When 03 is set to the optimum value, the polarity switch 17 causes the i signal and the j signal to alternately repeat H level and L level according to the set polarity ratio.

Furthermore, a comparator 2 is added to the AND circuits 301 and 302.
7, the output signal of the pulse generation circuit 231, and the output signals i and j of the polarity switch 17 are input, and only when each input is at H level,
The output signals of the AND circuits 301 and 302 are ON signals for driving the transistors 61 to 64 of the inverter circuit 15. In other words, the time when the polarity switches is always a short-circuit period. AND circuit 30
The ON and OFF timings of transistors 61 and 62 and transistors 63 and 64 of the inverter circuit 15 are changed by the respective output signals of 1 and 302 so that the ratio of the positive polarity energization period to the reverse polarity energization period becomes the set value. controlled by.

In this way, since the polarity ratio can be adjusted to a desired value with a single touch, the amount of penetration and the amount of excess build-up can be arbitrarily changed over a wide range according to the shape of the base material. Furthermore, since the pulse width signal τ was controlled to be corrected according to the average value of the welding voltage, welding can be performed while always maintaining a stable arc length.

The present invention is configured to weld between a wire electrode to which a DC voltage is applied and a base material while repeating a short-circuit state and an arc generation state, and in which a DC power source is used to connect the wire electrode and the base material to a wire electrode to which a DC voltage is applied. an inverter circuit that applies a DC voltage with variable pulse width, frequency, and polarity, a voltage detector that detects the applied voltage between the wire electrode and the base metal, a welding current detector that detects the welding current, and settings. a means for setting a reference pulse current waveform from the arc length and wire feed rate, a means for setting the ratio of positive and reverse polarity of the welding current, and a means for starting the application of the welding current from when the voltage detector detects a short circuit state. Means for controlling the inverter circuit so that the welding current started and detected by the welding current detector is compared with the reference pulse current waveform so that the two match and a set energization ratio of positive and reverse polarity is achieved. The arc length, wire feed rate,
By simply setting the forward/reverse polarity ratio, it is possible to weld while stably maintaining the optimal beat shape.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the circuit configuration of a short-circuit transitional arc welding machine according to the prior art, FIG. 2 is a diagram showing an overview of its voltage, current waveforms, and welding phenomena, and FIG. 3 is a circuit diagram of an embodiment of the present invention. Diagram showing the configuration, Figure 4a,
b is a switching timing diagram and a current waveform diagram of the i signal in this embodiment, respectively. Figure 5 shows the various parts I _P , i, j, k, when creating the current waveform in Figure 4.
This shows a time chart of l, m, and n. In the figure, 1 is a wire electrode, 2 is a base material, 3 is a wire feeding motor, 5 and 51 are a DC power supply circuit,
6, 61, 161, 162, 181, 182 are switching elements, 7 is a reactor, 8, 81 is a flywheel diode, 9 is a voltage detector, 1
0, 11, 101, 111 are comparators, 13, 13
1 is a switch command circuit, 14 is an auxiliary power supply, 15 is an inverter circuit, 16 is a delay circuit, 17 is a polarity switch, 20 is an operation box, 201 is an arc length setting dial, 202 is a wire feed setting dial, 203
is the polarity ratio setting dial, 21 is the voltage function circuit,
231 and 232 are pulse generation circuits and 2
4 is a setting circuit for setting the peak current I _P0 , 25 is an arc current detector, 26 is an amplifier, 301, 30
2 is an AND circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a welding device configured to repeat a short-circuit state and an arc generation state between a wire electrode to which a DC voltage is applied and a base metal, the wire electrode and the base metal are connected to each other from a DC power source. an inverter circuit that varies the pulse width and polarity of the welding current supplied between the wire electrode and the base metal, a voltage detector that detects the voltage applied between the wire electrode and the base metal, and a welding current detector that detects the welding current. means for setting the reference pulse current waveform from the set arc length and wire feed amount, means for setting the ratio of positive/reverse polarity of the welding current, and a means for setting the welding current from the time when the voltage detector detects a short circuit state. energization is started, and the welding current detected by the welding current detector is compared with the reference pulse current waveform, and the inverter circuit is adjusted so that the two match and the energization ratio of positive and reverse polarity is set. A bipolar short-circuit transitional arc welding machine characterized by comprising driving means. 2. Bipolar short-circuit transition according to claim 1, characterized in that the means for driving the inverter circuit so as to have an energization ratio of forward and reverse polarities includes means for switching the polarity within the short-circuit period. arc welding machine.