JPS59107774A - Non-consumable electrode type arc welding method - Google Patents

Abstract

PURPOSE:To obtain deeper penetration at the same average current value with the arc sound less offensive to the ear in arc welding using a non-consumable electrode by regulating the repetitive number of the peak and base of welding current in a prescribed frequency range. CONSTITUTION:The input voltage from a commercial AC power source 1 is rectified 12 to DC. The DC voltage is converted to a high frequency AC voltage in an inverter part 13 and after said voltage is transformed to a high voltage with a voltage transformer 14, the voltage is converted to DC in a rectifier part 15. The DC output is subjected ripple removal and is supplied through a current detecting part 15 to a TIG arc load 6. On the other hand, the set signal for the peak and base current in an amplifier part 17 which amplifies the current detection signal and feeds neatively the same back to an error amplifier 22, a peak current setting part 18 and a base current setting part 19 is changed over and is applied to the input on the positive side of the amplifier 22. A saw-tooth wave generator 22 sets the repetitive frequency of the peak and base in a 100-500Hz range so that pulse TIG welding is performed. As aresult, the non-consumable electrode type arc welding which permits high speed welding with good weldability is accomplished without spoiling the above-mentioned characteristics as well as the uniformity in penetration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a non-consumable electrode type arc welding method, so-called pulsed TIG welding method, in which the welding current is repeatedly changed into a peak current and a base current in a pulsed manner.

[Prior Art] TIG welding using a non-consumable electrode is suitable for obtaining high-quality welds because it does not generate spatter and the arc is stable. However, during on-site construction work at the plant, it is required to be able to weld various joints from thin plates to thick plates, and to be able to weld in all positions, including upward and vertical welding, and conventional TIG welding machines cannot meet this requirement. I couldn't find anything that was satisfying enough.

Pulse TIG welding methods developed in recent years include so-called low pulse TIG welding, which uses a low frequency band of about 0.5 to 20 Hz as the peak and base repetition frequency, and 1 to 1Q welding.
So-called bipulse TI using a high frequency band of about kHz
There is G welding. Next, these existing pulse TIG welding methods will be briefly explained and problems will be clarified.

FIG. 1 [ai is a block diagram of a low pulse TIG welding power source. 1 is a commercial AC power supply, 2 is a transformer, 3 is a current control SIRISK-14 is a smoothing reactor, the output of the transformer 2 is converted to DC by SIRISK 3, and a current detection section 5
It is supplied to the load 6 through the.

Load 6 is a TIG arc load using non-consumable electrodes.

The signal from the current measuring section 5 is negatively fed back to the ignition signal generating section 8 of Cyrisk, and is compared with the signal from the current setting section 7. Set the peak current and base current settings to 0 using the current setting section 7.
The thyristor 3 is phase-controlled by the ignition signal generator 8 so that the output current value becomes the set peak current value and base current value by switching at a predetermined cycle of 5 to 20 Hz. By using such a welding source, low pulse TIG welding can be performed in which the welding current (or peak current II) and base current I11 repeatedly change at a frequency of 05 to 20H2, as shown in the waveform in Figure 1(b). I can do it.

The peak and base repetition cycles of low-pulse TIG welding are selected based on the solidification time of the molten pool, and are effective in preventing drooping in Uranami welding and drooping in vertical heat welding. In addition, this low-pulse TIG welding can control the amount of heat and penetration by adjusting the peak and base current values, so the range of application to various joints is wider than that of normal DC TIG welding. However, when the penetration speed is increased in an attempt to improve welding efficiency, the low peak and base repetition frequencies result in a shallow area of penetration corresponding to the base current, making it impossible to obtain uniform penetration. . In addition, because the concentration of the arc is weak, the penetration depth is not sufficient, and in order to deepen the penetration, the average current value (L) must be increased, which increases the thermal influence on the surroundings due to excessive heat input. (
There was a drawback.

FIG. 12 [a] is a block diagram of a bi-pulse TIG welding haze source. -Transformer 2 connected to the next side or commercial AC power supply 1
The secondary output of is rectified by the rectifier 9 and applied to the trans/meta 10. The transistor 10 functions as a series regulator and supplies the load 6 with an output current corresponding to its base current. Base current control section 1 of transistor 10
1 compares the negative feedback signal from the current detection section 5 with the peak current setting value of the base and the signal from the current setting section 7 which switches at a cycle of ~10kHz, and determines that the output current value is the set peak current value. Transistor 1 so that the base current value
Controls the base current of 0. By using such a welding power source, as shown in the waveform shown in FIG.
01 (repeatedly changing at the frequency of H2)・Ipulse T
I can do IG welding.

Bi-pulse TIG welding uses arc vibration caused by repeated changes in peak and base current frequencies.
It is said to be effective in improving weld quality by making the structure of the weld zone finer and reducing flow pole defects. Ii, Ii9 during welding work with loud arc noise
．． It's harmful.

[Object of the Invention] The object of the present invention is to compensate for the drawbacks of the prior art described in 2 above, to achieve deeper penetration with the same average current value, and to improve the uniformity of penetration without making the arc sound unpleasant. It is an object of the present invention to provide a non-consumable electrode type arc welding method with good welding properties, which enables high-speed welding without sagging.

[Summary of the Invention] In order to achieve the above object, the present invention reduces the peak and base repetition frequencies of welding current from 100 to 500.
It is characterized by being selected in the Hz range.

According to the results of welding experiments conducted by the inventors, when pulsed TIG welding is performed by repeatedly changing the welding current between the peak current and the base current in such an intermediate frequency band, conventional low-pulsed TIG welding and bi-pulsed TIG welding It was found that a unique effect not found in other methods can be obtained. That is, 1
In pulsed TIG welding in the 00 to 500 Hz band, the arc column directly below the electrode is constricted due to the pinch effect of the peak current, and the phenomenon that the concentration of the arc becomes stronger appears, and compared to DC TIG welding and low pulse TIG welding, the average Deeper penetration can be achieved depending on the current value. In addition, because the peak and base repetition periods are relatively short, even if the welding speed is increased, the effect of shallow penetration at the base current is not noticeable (uniform penetration was obtained. or 500H
As long as the arc noise does not exceed z, arc noise will not be a hindrance to work.

[Embodiments of the invention] Hereinafter, pulsed TIG used in the present invention
An example of a welding power source and pulse TIG welding using the same will be described.

FIG. 3 fal is a pulse T suitable for carrying out the present invention.
An example of an IG welding power source is shown. In the figure, an input voltage from a commercial AC power supply 1 is converted into DC by a rectifier [2] and applied to an inverter [3]. The inverter section 13 is composed of bridge-connected transistors, and converts a DC voltage into a high-frequency AC voltage. Reference numeral 14 denotes a transformer to which a high frequency AC voltage is applied, so that it can be made smaller than the transformer 2 shown in FIGS. 1 and 2. Reference numeral 15 denotes a rectifier section composed of high-speed diodes, which converts the high-frequency AC voltage output from the transformer 4 into DC. The DC output of the rectifier 15 has ripples removed by a smoothing reactor 6, and is then sent to the current detector 56.
It is supplied to the T■G arc load 6 through. Reference numeral 17 is an amplifier section that amplifies the current detection signal and provides negative feedback to the error amplifier 22, 18 is a peak current setting section, and 19 is a base current setting section, and these peak and base current setting signals are switched by a peak and base switch 20. and is added to the positive input of the error amplifier 22. The peak/base switching FJ device 20 is a multiplexer circuit that switches the peak/base current setting signal according to the selection signal from the pulse frequency setting section 21.
The pulse frequency setting unit 21 is a circuit that generates a selection signal whose repetition frequency and duty cycle are variable in accordance with the set peak, base repetition frequency and peak, and base time ratio. The error amplifier 22 outputs a difference signal between the current detection signal and the current setting signal to the comparator 23. 24
is a sawtooth wave generator that oscillates at a constant frequency higher than the peak, base repetition frequency, for example 4Q kHz.

This sawtooth wave signal is input to the comparator 23 and the error amplifier 2
A comparator 23 generates a pulse width modulation signal in which the width of the output pulse becomes wider as the output of the error amplifier 22 becomes larger. 25 (j) In the base drive signal generation section that drives the bases of the transistors constituting the inverter section 13, when a Brynon-connected inverter is used, the pulse width modulation signal from the comparator 23 causes the two sets of transistors to be alternately supplies the base drive signal,
20 kHz pulse width modulated as impark output
A high frequency alternating current I'a pressure is generated. When this high frequency AC voltage is applied to the transformer 14, the output current supplied from the smoothing reactor] 6 to the load 6 is changed to the pulse frequency setting section 2.
1 set peak, base repetition frequency and peak,
When the pulse waveform repeatedly changes between the peak current and the base current in response to the base time ratio, and the peak and base repetition frequencies are set in the range of 100 to 500 Hz, pulsed TIG welding in the 100 to 500 Hz band is possible. can be done. Figure 3 (1) is a diagram schematically showing the impark output waveform when the peak and base repetition frequencies are 200 Hz, and Figure 3 (C) is a diagram schematically showing the welding current waveform in this case. The peak current IIJ is the base current, and 7. is the average current.

Since the current detection signal is negatively fed back to the error amplifier 22 from the current detection section 5 via the amplification section 17, when the peak and base current values decrease due to one-to-one load fluctuation, the error amplifier 2
The 1-δ force of 2 becomes larger, and therefore the output pulse width from the comparator 23 to the base drive signal generating section 25 becomes wider, and the inverter section 13 is arranged so as to increase the peak and base current values. When the peak and Hesum current values increase, the opposite is true, and constant current control is performed to maintain the peak and Hesum current values at their respective set values.゛The Konohals TIG welding power source repeatedly changes the welding current into a peak current and a base current by pulse width modulation at the impark section 13, so that Figures 1 and 2.
As shown in Figure 2, the transformer can be made smaller compared to the TIG welding power source, and as shown in Figure 2!・The conversion efficiency is better than that of using the Rannostar 10 as a series regulator, and it is connected in parallel.) ・The number of Rannostars can be reduced, so the entire power supply becomes smaller and lighter.
Suitable for on-site construction. Also, this pulse TIG
The welding power source has a peak frequency set by the pulse frequency setting section 21,
By changing the base repetition frequency, 0.5 to 20
It can also be applied to pulsed TIG welding in a low frequency band of Hz and a high frequency band of 1 to 10 kHz.

FIG. 4 fa+ is a pulse T suitable for carrying out the present invention.
Another example of the IG welding power source is shown. In this example, current control is performed by frequency modulation, and the current setting signals from the peak current setting section 18 and the base current setting section 19 are switched by the peak and base switching device 20, and are added to the positive side human power of the error amplifier 22. A difference signal between the current detection signal and the current setting signal that is negatively fed back from the detection section 5 via the amplification section 17 is output from the error amplifier 22 to the V'-F converter 26, and the frequency corresponding to the voltage level of the difference signal is outputted from the error amplifier 22 to the V'-F converter 26. signal. The output signal of the V-F converter 26 causes the base drive signal generator 25 to be connected to two sets of fringe-connected transistors 1. The base drive signal is alternately supplied, and as an inverter output, a high frequency alternating current voltage is generated which is frequency modulated to, for example, kHz in the section corresponding to the peak current of the welding current, and IQ kHz in the section corresponding to the base current. [Transformer] 4 is configured as a leakage transformer, and when a high frequency AC voltage is applied to this transformer 14, the area corresponding to the relatively high frequency base current is higher than the area corresponding to the relatively low frequency peak current. Since a large reactance voltage drop occurs, transformer 14
The output current obtained by rectifying and smoothing the output in a rectifying section 15 and a smoothing reactor 6 becomes a pulse waveform that repeatedly changes into a peak current and a base current, and a pulse frequency setting section 21 sets the peak and base repetition frequencies. 100-500
If set in the Hz range, pulse TIG welding can be performed in the 100 to 500 Hz band. FIG. 4 (1) is a diagram schematically showing the inverter output waveform when the peak and base IFA return frequencies are 200 Hz, and FIG. 4 fcl is a diagram schematically showing the welding current waveform in this case.

This pulse TIG welding power source can also be made smaller and lighter as in the example shown in FIG. 3, and is suitable for on-site construction.

The inventors used a pulsed TIG welding power source with the configuration shown in Figure 3, and set the peak and base repetition frequencies to 100 to 500.
A pulse TIG arc is generated by varying the frequency in the Hz range, and a conventional DC TIG arc and a low pulse TIG arc are generated.
We compared arc shape, weld beat width, and penetration depth with arc and bipulse TIG arc.

Figure 5 (al is electrode diameter 2.4 mmφ, arc length 4 mm
Arc photo of DC TIG arc (average current 100 A, positive polarity) (filter ND2+4+8, aperture speed T
22, ]/60, film, color film), Figure 5 tbl is a peak photographed under the same conditions, base repetition frequency 200 Hz, average current 100 A (Ip
: 20OA, ITJ: 60A, positive polarity) pulse T
This is a transcription of an IG arc photo. In the latter case, it can be seen that the arc column directly under the electrode is more focused than in the former case, and this tendency becomes noticeable from around a repetition frequency of 100 Hz. The reason for this is not clear, but it is presumed that when the repetition period is shortened to a certain extent, the arc pressure directly under the electrode increases due to the pinch effect of the peak current.

Figure 6 shows the heat width and penetration depth obtained by pulsed TIG welding of 1.00 to 500 Hrs using DC TIG arc, Oyohiro pulsed TIG arc, and bipulsed TIG welding.
According to the arc, it is shown in comparison with the width of the arc and the depth of penetration. Other welding conditions are as follows.

Average current: 100A (Ip: 20OA, In: 60
A) Electrode diameter: 3.2mmφ Arc length: 2.5mm A; J'L': x 7-7 Less steel (SUS
304) Plate thickness 3mm Welding speed: 250 mm/m
As is clear from this figure, the pulsed TIG arc of 100 to 5QQ Hz has a relatively narrow bead width compared to the DC TIG arc and low pulsed TIG arc with the same average current value.
Heat with deep penetration was obtained, indicating good arc concentration. Moreover, since there is a base current section with low heat input, excessive heat input does not occur, and the influence on the surroundings, which may cause cracks, can be suppressed. Also, 1.00
Since the pulsed TIG arc of ~500 Hz has a relatively short peak and base repetition period, even if the welding speed is increased, the effect of shallow (shallow) penetration at the base current is less likely to occur, and uniform penetration can be obtained.

The reason why we set the upper limit of the peak and base repetition frequency to 500 Hz is because the arc sound becomes high when it exceeds 500 Hz.
This is because manual TIG welding cannot withstand long hours of work.

Figure 6 shows the experimental results when the average current was 100 A, or almost the same tendency as in Figure 6 was observed in welding experiments conducted with different average currents. Moreover, the pulsed TIG according to the present invention
The welding method is applicable not only to stainless steel, but also to copper alloys (especially brass).
Good results were obtained even when applied to welding.

[Effects of the Invention] As explained above, the pulse TIG welding method of the present invention in which the peak and base repetition frequencies are in the range of 100 to 500 Hz has an increased concentration of bare arc compared to conventional DC TIG arc and low pulse TIG arc. It is suitable for achieving deeper penetration by suppressing the thermal effects on the surrounding area due to excessive heat input, and it is also possible to increase welding speed and improve work efficiency without impairing the uniformity of penetration. Arc noise can also be suppressed to a level that does not interfere with work.

Therefore, by using a variable frequency pulse TIG welding power source as shown in Figure 3 or Figure 4, and using it for low-pulse TIG welding or bi-pulse TIG welding as necessary, one welding machine can meet the requirements for on-site construction. It is possible to perform welding work that is better suited for welding various joints from thin plates to thick plates, and for welding in all positions, including horizontal and vertical welding.

Even when the present invention is applied to plasma welding using non-consumable electrodes, the same effects as described above can be expected.

[Brief explanation of drawings]

FIG. 13) is a block diagram showing a conventional low-pulse TIG welding power source, and FIG. 13) is a welding current waveform diagram thereof. Figure 2 tal is a block diagram showing a conventional bi-pulse TIG welding power source, the same figure (bl is its welding current waveform diagram, and Figure 3 (
al is a block diagram showing an example of a pulsed TIG welding power source for implementing the present invention, tb) in the same figure is an output waveform diagram of its inverter section, fcl is a welding current waveform diagram, and Figure 4 fa
1 is a block diagram showing another example of a pulsed TIG welding power source for carrying out the present invention, tb) in the same figure is a waveform diagram of the inverter section output, fc] is a welding current waveform diagram, ``Figure 5 (al) , [bl is a transcript of the arc photograph of the DC TIG arc and the pulsed TiG arc according to the present invention, and Figure 6 is the actual measurement of the peak of the pulsed TIG arc, the heat width obtained by changing the base repetition frequency, and the penetration depth. It is a graph showing the values. 1. Commercial AC power supply 5 Current detection section 6. TIG
Arc load 12, rectifier section 13...inverter section
14... Transformer 15... Rectifier section 16.
... Smoothing reactor] 7... Amplifying section 18... One peak current setting section... Base current setting section 20... Peak/base switch 21 Pulse frequency setting section 22...
・Error amplifier 23...Comparator 24...Sawtooth wave generator 25...Transistor base drive signal generation section 26...V-F converter Patent attorney Junnosuke Nakamura 1 Illustration 2 Figure 13 Figure (Q) Figure 4 (Q) Figure 5 Procedural amendment (method) April 5, 1983 6. Commissioner of the License Agency Indication of the case 1983 Patent Application No. 215.521, Title of invention Non-expendable Relationship with the case of the person amending the electrode arc welding method Date of the amendment order by the patent applicant's agent March 28, 1980 Subject of the amendment A column for a brief explanation of the drawings in the specification. Contents of the amendment (1) “(a)” on page 16, line 4 of the specification
, (b)" are deleted.

Claims (1)

[Claims] In arc welding, which uses a non-consumable electrode and repeatedly changes the welding current between a peak current and a base current, the peak and base repetition frequencies are 100 to 500 Hz.
A non-consumable electrode type arc welding method characterized by a range of .