JPS6082272A - Short-circuit transfer arc welding machine - Google Patents

Abstract

PURPOSE:To provide a titled welding machine which maintains the specified repetivie period between an arc and a short circuit and performs uniform welding with less spatters by comparing the instantaneous electric power in the stage of welding and a set target electric power program and controlling the welding current from a DC power source. CONSTITUTION:Instataneous electric power is detected from a current detector 24 and a voltage detector 26 on a weld zone side and the target electric power program in the stage TS of a short circuit and the target electric power program in the stage TA of an arc are compared by a computer 46 of a control circuit 28 in short-circuit transfer arc welding. The welding current is controlled by a control power transistor 64 of a DC power source 10 so as to attain the target value thereof. The period of the short circuit and the arc is thus made constant and the uniform welding with less spatters owing to satisfactory burn- through is accomplished.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a short-circuit transitional arc welding machine, particularly a welding machine that frequently repeats short-circuiting and arc generation between a wire electrode (hereinafter also simply referred to as a wire) and a base material. Related to welding.

[Prior art]

Conventionally, there has been a device of this type as shown in FIG.

The device shown in the figure includes a DC motor 10.3-phase transformer 68
, a thyristor rectifying element group 70, a DC reactor 12, a wire electrode 14, and a motor 1 that feeds the wire to the welding torch.
6. It is composed of a welding torch 18, a wire reel 22, etc. Further, 20 indicates the base material.

Next, its operation will be explained.

The welding machine described above performs welding while repeating short circuit and arc discharge. That is, welding is performed by melting the welded portion between the tip of the wire and the base metal during an arc, and transferring the melted tip of the wire to the base metal during a short circuit.

Here, the operating principle of welding by repeating short circuit and arc discharge will be explained.

While applying a voltage between the welding torch 18 and the base material 20 from the DC power supply 10 through the DC reactor 12t, the base material 20 is
The wire 14 is fed into the side at a constant speed. Then, the wire and the base metal are short-circuited, the welding current rises with a time constant determined by the DC reactor 12 and the short-circuit resistance, and arc discharge occurs. When arc discharge occurs, the welding current falls with a time constant determined by the DC reactor 12 and the arc resistance, causing a short circuit again.

As described above, depending on the balance between the amount of current supplied and the amount of wire fed, short circuits and arc discharges are periodically repeated as shown in FIG. 2.

By the way, since the conventional short-circuit transition arc welding machine is constructed as described above, the short-circuit period changes due to minute fluctuations in the welding torch position or the base metal position. Then, the amount of heat during the arc period changes and melts during the arc period! lit
, the size of the molten ball and the amount of droplet transfer during the short-circuit period each change greatly, resulting in an unstable welding phenomenon called the so-called 0-arc creep phenomenon or 1-stapping phenomenon. As a result, there were problems such as large spatters and defects in the weld bead.

[Summary of the Invention] This invention was made in view of the above-mentioned conventional problems, and its purpose is to solve problems such as large spatters or welding defects in the welding process. An object of the present invention is to provide a short-circuit transitional arc welding machine.

In order to achieve the above object, the present invention provides a transitional arc welding machine that repeatedly welds a wire electrode, a workpiece to be welded, and an arc discharge using a welding current supplied from a DC power source. means for detecting electrical power;
The welding current supplied from the DC power source is controlled in accordance with a comparison result between the instantaneous power and the target power.

[First Embodiment] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows an embodiment of a short-circuit transitional arc welding machine according to the present invention.

The welding machine shown in the figure has a DC power source of 10 and a welding current of 1 ON-
Power transistor 64 for OFF control, DC reactor 12, flywheel diode 66, current detector 2
4. The voltage detector 26 and the control circuit P328 that controls the welding current ON-OFF. First, the welding wire 14 is supplied from the wire reel 22 to the welding torch 18, and the current detector 24 and the voltage Welding current Ai and welding voltage Vi are detected by detector 26.

The detected welding current AI is input to the instantaneous power setting device 30.

Furthermore, the detected welding voltage Vi is determined by the instantaneous power setting device 30.
and target voltage setter 34 and control computer 46, l10 (input/output) interface l38t-
They are each input via the

The control computer 46 performs all short circuit and arc determinations. This computer 46 also has an X%Y signal 6I10.
Interface 140t--via short circuit time setter 42
and is applied to the arc time setting device 44. This provides an indication of faults, shorts, and arcs.

A short circuit time ts and an arc time ta are set in the short circuit time setter 42 and the arc time setter 44. This setting state is input to the computer 46 via the I10 interface 140.

The computer 46 calculates the short circuit waveform factor S and the peak arc power value Wp2 based on the short circuit time 1 s.

Further, an arc waveform factor a is calculated based on the arc time ta. The results of these calculations are output to the I/O-(interface 48).

The short-circuit waveform factor S and the wire feed speed signal A2, Vw, which is amplified 42 times by the amplifier 5B, are 41:, 0 and 43i.
The cross-multiply q results that are multiplied together by the circuit power W s setter 56 are the target short S power W s (W s =A2・V
w-s) to the target voltage setter 60.

Further, the arc waveform factor a and the peak arc power value Wp2 are subtracted from each other by an adder 50. This subtraction result (W
p2-a) is multiplied by the wire feed speed signal A1·Vw which is amplified by A1 times by the amplifier 54 in the target arc gravity Wa setting device.

Then, this multiplication result is the target arc power Wa (Wa
=AI・Vw(Wp2-a)) is input to the target power setter 60, and the target power Wo(
It is input to the comparator 62 as Wo=Wa-1-Ws).

Note that the target power Wo is finely adjusted by the difference voltage (Vo-Vi) between the average welding voltage Vi and the target voltage Vo.

The comparator 62 receives the instantaneous power Wi from the instantaneous power setting device 30.
and the target power Wo, and if W i )Wo, an OFF signal is sent to the power transistor 64. Conversely, if W i (W o), an ON signal is sent to the power transistor 64. This causes the welding current Ai to be
-OFF control" is performed.

FIG. 5 shows an overview of the control program executed by the computer 46 in the form of a flowchart.

In this control program, in step 101, welding F, Tri, and HE Vi are taken in from the I10 interface I, and in step 102, the welding voltage Vi is compared with the threshold voltage Vc to determine whether there is a short circuit or an arc. Let's do it. Depending on the result of this determination, short circuit current waveform setting routine 200 or arc power waveform setting routine 2
Execute all of 01.

The short path power waveform setting routine 200 and the arc power waveform setting routine 201 are performed in the droplet state modes 1 to 1 shown in FIG.
Follow mode 11. FIG. 4 is a conversion diagram created based on the analysis results of high-speed photographs, and shows the state equilibrium mode of droplet transfer and generation during the short-circuit period and the arc period.

First, the control of the short circuit current waveform setting routine 200ff111 will be explained.

In the first step 111, the arc waveform factor a'1lOJ is defined, and in step 112, the l10-f interface ■
output a=o'. Also, steps 113 and 114
Define X as rOJ, Y'ff:rlJ, and perform Step 1
At step 15, all X and Y signals are output to the I10 interface H.

Next, in step 116, the elapsed time since the wire was shorted, that is, the short circuit time tst-I10 interface ■
Import from. Then, in subsequent steps, a peak arc power value Wp2 and a short circuit waveform factor S corresponding to the short circuit time 1 s are calculated.

Here, the beak arc power value Wp2 determines the arc power value during arc regeneration, and the beak arc power value Wp2 is determined by analysis from the high-speed photograph shown in FIG.
It turns out that it is better to control it so that it depends on the short circuit time TS! It's JJL. The longer the short circuit time TS is, the thicker the melted wire will be when it migrates to the base metal side. Therefore, in the next arc period, melt the amount that migrated to the base metal side during the short circuit. The generated molten beads can be controlled to a constant level.

Therefore, in step 117, Wp according to the short circuit time 1 s.
2 (Wp 2= r 2 (is))ffi operation, and in step 11B, Wp is applied to the 110 interface ■.
Outputs 2. By doing so, the waveform of Wp2 in the time chart of the generation process of the zero-shuttle power waveform in FIG. 6 is outputted to the outside from the I10 interface 1.

Regarding the short-circuit waveform factor S, in the period from mode 6 to mode 7 in FIG.
! It turns out that it is better not to inject power into the wire. By the way, if a large amount of power is injected during the period ts<t1,
This causes an instantaneous short circuit that hardly causes droplet transfer, and in the next arc period, the molten ball becomes thicker, and the short circuit period is disturbed.

Also, from mode 7 to mode 8, that is, t 1 < t 5 (
It has been found that during period t2, it is desirable to rapidly inject power at t't, when the arc is not regenerated, to quickly form a constriction at the short-circuited wire tip.

Mode 8 to Mode 11. Tsumashi t 2 (t s<t
In period 3, when arc regeneration is performed by increasing the power injection with a gentle slope, the amount of spatter generated during arc regeneration becomes constant, and the amount of spatter as a whole becomes less than that of the previous one. Moreover, it has been found that the size of spatter becomes finer.

Furthermore, when the short circuit time ts becomes 13 or more, in order to prevent the unmelted wire from plunging into the base metal, arc regeneration is forcibly performed by suddenly injecting electric power, which prevents the system stamping phenomenon. control to prevent it from happening.

Therefore, for the short path waveform factor S, the computer 46
The following control program is executed.

That is, in step 119, the short circuit time t5 and the time t1
Compare with. If the comparison result is ts<tl, then in step 120 the /Al coupling waveform factor S is defined as rOJ, and in step 126 all s are output to the I10 interface (2) and the process returns to step 101.

Further, if the comparison result is not is<tl, then in step 121, the short circuit time is and time t2 are completely compared. If the comparison result is is<t2, the short-circuit waveform factor s f Ts=t3 (t, -tl) is defined in step 122, and a small sf is output to the I10 interface III in step 126, and the process returns to step 101.

Furthermore, if ts<12, tf, then in step 123, the short circuit time 's and time t3 are compared, and the result is ts<12.
If ta, then in step 124 the short path waveform factor sis =
Defined as f 4 (ts--t2) + f3 (t2),
In step 126, S is output to the I10 interface and the process returns to step 101.

Furthermore, if tS<ta, step 1
26, b Pi”r waveform factor sis = f5(ts t
a)+f4(ta)+f3(t2) is defined, and in step 126, si is output to the f10 interface III, and the process returns to step 101.

In the above manner, the short-path waveform factor S is shown in the time chart of the generation process of the target type of moon skin shape in Figure 6.
/ 04 I am sent outside from Interface Eighth HE.

Next, the control of the arc power waveform setting routine 2o1fIII will be explained.

In step 103, a short circuit waveform factor S'trOJ is defined,
In step 107, X, Y is sent to I10 interface II.
Outputs all signals. In step 108, the elapsed time since the arc was regenerated, or the arc time ta, is taken in from the I10 interface (2). In step 109, the arc time ta
A(a=fl(ta))' is calculated according to , and in step 110, ai high output is output to the I10 interface (2), and the process returns to step 101.

As described above, the arc waveform factor a in the time chart of the target power waveform generation process shown in FIG. 6 is outputted from the I10 interface (2) to the outside.

Here, FIG. 7 shows an embodiment of the control circuit portion of FIG. 3.

In the same figure, the welding current Ai detected by the current detector 24 is amplified by amplifiers G1 and 02, and then applied to the multiplier Mlr in the instantaneous power setting device 30, for example, at the XY input terminals of Analog Devices' AD-532J. is input.

Further, the welding voltage Vi detected by the voltage detector 26
is amplified by amplifier G3, and then input to the Y terminal of q filter M1 in instantaneous power setting device 30, average voltage setting device 32, and A/D converter 72. The four-hour power Wi is calculated by multiplying the welding current A+ and the welding voltage Vi by a multiplier M1. This old power Wi is input to the resistor Ri of the comparator 62 after being amplified by the amplifier G4.

In the average voltage setter 32, the amplifier G5 and the capacitor CI
, an averaged voltage Vc is created by the resistor 5. This voltage Vc is input to the resistor It 6 in the adder 36.

In addition, the target voltage ■0 is a variable resistor (volume) ■几1
and is input to the resistor lt7 in the adder 36 via the voltage follower circuit G6.

The adder 36 adds the average voltage -Vi and the target voltage ■. This added signal (Vo-Vi) is sent to the comparator 62
It is input to the resistor R2 inside.

In the short circuit time setting device 42, first, the X signal is sent to the buffer 84.
1 to the base of the transistor Tri. Then, when X-1, the transistor Tri is OF'
The F' state is entered, and while this state continues, an integration operation is performed by the amplifier G8 and the capacitor C2, and a voltage corresponding to the short circuit time ts is output. This voltage is converted into a digital signal by the A/D converter 80 and inputted to the I/Q interface TI.

Further, when Y=1, the transistor Tr2 is in the OFF state, and the time in the OFF state is divided by the amplifier G9 and the capacitor C3. As a result, a voltage corresponding to the arc time ta is output. This voltage is converted into a digital signal by the A/D converter 82 and input to the I10 interface H.

The arc waveform factor a and the peak arc power value Wp2 output from the I10 interface llI48 are sent to the adder 5.
The signal is converted into an analog signal by D/A converters 78 and 76 in the 0. The arc waveform factor a is inverted by the amplifier GIO and then input to the amplifier Gll. Amplifier Gll
Then, the arc waveform factor a and the peak arc power value Wp2 are added. This addition output (Wp2-a) signal is output to the Y terminal of the adder M2 in the target arc power Wa setting device 52.

On the other hand, the short-circuit waveform factor S output from the I10 interface [48] is converted into an analog signal by the D/A converter 74, and is input to Y of the adder M3 in the target short-circuit power Ws setting device 56.
Output to the terminal.

In the target arc power~a setting device 52, the wire feed speed signal AI·VW, ! which is multiplied by A1 by the Kakeiwazuto 12 is set. :
The (Wp 2-a ) signal is output at 7v, thereby outputting the target arc power Wa at 7-4. This target arc power Wa is amplified by an amplifier G12, and then a comparator 6
It is input to the resistor R3 of No. 2.

Further, in the target short circuit power Ws setting device 56, the wire feeding speed signal A is multiplied by the multiplier M3, and the wire feeding speed signal A is multiplied by 42 by the amplifier 58.
2.Vw is multiplied by the short circuit waveform factor S signal. Thereby, the target short-circuit power Ws is calculated. This calculated 0/1 short circuit power Ws is amplified by the amplifier G13 and then input to the resistor R4 in the comparator 62.

In the comparator 62, the instantaneous power W i input to the resistor R1
, the (Vo-Vi) signal input to resistance ratio 2, the target arc power Wa input to resistance ratio 3, and the target short circuit power Ws input to resistance ratio 4 are added. Then, the added potential and the earth (ground) potential are connected to the comparator G1.
4, and the comparison result is output to P. This P
The power transistor 64 shown in FIG. 3 is controlled ON-OFF by the signal outputted to .

Note that the resistors itb and Ra are provided to provide hysteresis when the comparator G14 is inverted from ON to OFF and when it is inverted from 01°F to ON.

〔Effect of the invention〕

As described above, the short-circuit transitional arc welding machine according to the present invention has means for detecting instantaneous power during welding and means for setting target power, and a comparison result between the instantaneous power and the target power is provided. By controlling the welding current supplied from the DC power supply according to the above-mentioned DC power supply, it is possible to keep the repetitive periodic sound of arc and short circuit constant, thereby reducing system irregularities (and making them finer). A uniform weld bead can be obtained.

[Brief explanation of drawings]

Fig. 1 shows a conventional short-circuit transitional arc welding machine, Fig. 2 shows welding current waveforms by the conventional welding machine, and Fig. 3 shows an embodiment of the short-circuit transitional arc welding machine according to the present invention. Figure 4 is a mode-based diagram of the droplet transfer and formation states during the short final period and the arc period, and Figure 5 is a
Fig. 6 is a flowchart showing the configuration of an execution program in the computer section of the welding machine according to the present invention, Fig. 6 is a time chart showing the generation process of the target power waveform of the invention, and Fig. 7 is the control circuit part of Fig. 3. It is a figure showing one example of this. The same reference numerals are given to the circuit parts in each figure, and 10 is a DC power supply;
12 is a DC reactor, 14 is a wire electrode, 18 is a welding torch, 20 is a base metal, 24 is a current detector, 26 is a voltage detector, 28 is a control circuit, 30 is an instantaneous power setting device, 32 is an average voltage setting device , 34 is the target voltage setter, 36 is the adder, 38, 40, 48 is the I10 interface ■, ■,
4244 is a short circuit and arc time setting device, 46 is a computer, 50 is an adder, 52 is a target arc power setting device, 56 is a target short m power setting device, 54.5Q is an amplifier,
60 is an eye@power WO setting device, 62 is a comparator, 64 is a power transistor for controlling the welding current Ai, and 66 is a flywheel diode. Agent: Patent attorney Masuo Oiwa (2 others) Figure 1 Figure 211!7I Figure 5 Figure 6 Procedural amendment (self-motivated) November 13, 1980 1, Indication of case Patent application 1982- No. 187827 2, Name of the invention Short-circuit transitional arc welding machine 3, Person making the amendment 5, Subject of the amendment I! l] Column for detailed explanation of Lien's invention. 6.7 rli positive content or more

Claims (1)

[Claims] (1) In a short-circuit transition arc welding machine that welds a wire electrode and a workpiece while repeating short-circuiting and arc discharge using a welding current supplied from a DC power source, there is a means for detecting the instantaneous power during welding and a means for detecting the target power. A short-circuit transfer arc welding machine, characterized in that the welding current supplied from the DC power source is controlled in accordance with a comparison result between the instantaneous power and the target power.