JP3138844B2 - Consumable electrode pulse arc welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode type pulse arc welding machine suitable for welding galvanized steel sheets.

[0002]

2. Description of the Related Art A steel sheet having a surface plated with zinc or a zinc alloy (hereinafter referred to as a galvanized steel sheet) has a corrosion resistance,
Because of its excellent weather resistance, it is used for automotive parts, steel frame members for buildings, and the like, and its demand is increasing year by year.

For welding galvanized steel sheets, short-circuit transfer welding (carbon dioxide welding, MAG welding) and pulse arc welding are generally widely used.

[0004]

In such conventional welding means, zinc having a lower melting point than iron plated on the surface of a steel sheet is vaporized by arc welding to generate steam zinc. The vapor zinc disturbs the inside of the gas shield and the arc to hinder the transfer of droplets, thus causing a large amount of spatter. In addition, steam zinc tends to diffuse outside through the molten pool and the molten metal, but when the solidification rate of the molten metal is high, it cannot diffuse sufficiently to the outside, resulting in bubbles in the weld metal and on the surface of the weld metal. It remained and caused welding defects such as blowholes and pits (hereinafter referred to as pores).

[0005] Further, according to the pulse arc welding, the amount of spatters and pores generated is reduced as compared with the case of short-circuit transfer welding, but the amount of generated spatters and pores is large. This is because the turbulence in the gas shield or arc caused by the generation of zinc vapor prevents the droplet from detaching from the wire tip each time the pulse current is applied. A short circuit in contact with the base material at the time of application has caused spatter.

The generation of such spatters and pores not only deteriorates the welding quality, but also requires reworking of the welded portion if the frequency of occurrence is unacceptable. If rework is impossible, the member is discarded. In some cases, this resulted in a decrease in work efficiency and significant uneconomics.

[0007] In order to solve such problems, at present, low-speed welding at a relatively low speed in order to prevent the generation of spatter and porosity, welding with a gap between steel plates, and the like, are mainly performed based on experience in devising construction work. Was compatible.

[0008] However, in such a measure, the work efficiency is low because of low-speed welding, it is difficult to prevent the generation of spatter, and the welding efficiency is reduced to further reduce the work efficiency.

An object of the present invention is to provide a consumable electrode type pulse arc welding machine which solves the above-mentioned problems and has a high welding efficiency and can suppress generation of spatters and pores in arc welding of galvanized steel sheets. It is an object.

[0010]

In order to achieve the above object, the present invention provides a consumable electrode type pulse arc for performing welding by superposing a pulse current and using a mixed gas of argon gas and carbon dioxide as a main component of a shielding gas. In the welding machine, a welding output voltage detecting unit that detects a peak voltage of a welding output pulse is compared with a peak voltage of the welding output pulse and a reference voltage that is set in advance and corresponds to a voltage at which a droplet is normally separated. A comparator that outputs a signal when the peak voltage of the welding output pulse exceeds the reference voltage; and a peak current value and a pulse portion voltage of the pulse of the next pulse current that are activated by a signal from the comparator. Of the droplet from the wire
Pulse peak current value increasing means to increase the removal and transfer of the droplet to the base material reliably, and the pulse width of the next pulse is separated from the wire and the transfer of the droplet to the base material is ensured
Pulse width expansion means to expand the droplet to the extent that it is performed and the rising gradient of the next pulse
A pulse current regulator including at least one of pulse rising gradient steepening means for steepening the drop to such an extent that the transfer of the droplet is ensured is provided.

[0011]

In the above construction, the peak voltage of the welding output pulse is detected, and when the increased welding output voltage generated when the droplet does not separate from the wire tip when the pulse current is applied exceeds the reference voltage, the droplet of the droplet is detected. From the material and dissolution into the base material
By increasing the peak current value of the pulse of the next pulse current and the pulse portion voltage, expanding the next pulse width, or steepening the rising gradient of the next pulse to such an extent that the transfer of the droplet is reliably performed , The transfer of the droplet to the base material during the application of the pulse current is assured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a reference voltage setting section for setting a reference voltage, and 2 denotes a welding output voltage detecting section for detecting a peak voltage of a welding output pulse as shown in FIG. Have been. The comparator 3 outputs a signal to the pulse current regulator 4 when the welding output voltage exceeds the reference voltage. The pulse current regulator 4 includes:
The peak current value of the pulse of the next pulse current and the pulse voltage are determined to ensure that the droplets separate from the wire and transfer to the base metal.
Pulse peak current value increasing means 5 for increasing the pulse width to the extent actually performed , and separating the pulse width of the next pulse from the wire of the droplet.
A pulse width extending means 6 for extending the droplet to the extent that removal of the droplet and transfer of the droplet to the base material are reliably performed , and melting of the rising gradient of the next pulse.
Drops are reliably removed from the wire and transferred to the base metal.
At least one of the pulse rising gradient steepening means 7 for steepening the pulse rising degree is included.

The operation of the above configuration will be described with reference to FIG. In the figure, reference numeral 11 denotes a pulse voltage waveform when the droplet at the tip of the wire normally separates, and corresponds to a preset reference voltage. Reference numeral 12 denotes a pulse voltage waveform when the droplet at the tip of the wire does not separate as indicated by time t. The arc length temporarily increases and the welding output voltage increases. The peak voltage 12 of the welding output pulse is equal to the reference voltage 1.
When the value exceeds 1, the comparator 3 outputs a signal to the pulse current regulator 4. By this signal, one or more of the pulse peak current value increasing means 5, the pulse width expanding means 6, and the pulse rising slope steepening means 7 included in the pulse current regulator 4 are operated to increase the pulse peak current value. Means 5, as indicated by A, determines the peak current of the pulse of the next pulse current to separate the droplet from the wire and to
The pulse width extending means 6 increases the pulse width of the next pulse current, as indicated by L, to the separation of the droplet from the wire and the transfer of the droplet to the base material, as indicated by L. Sure
Expanded to the extent actually performed, steepening pulse rising slope
It means 7 droplet rising slope of the next pulse as shown by θ
From the wire and transfer of droplets to the base metal
To be sharp to the extent that is. Each such means 5, 6, 7
By one or a plurality of operations described above, the pulse waveform in the next pulse current becomes a waveform as shown in P, and the separation of the droplet from the wire and the transfer of the droplet to the base material are reliably performed.

As described above, according to the consumable electrode type pulse arc welding machine of one embodiment of the present invention, a droplet that grows largely at the tip of the wire without detachment does not short-circuit with the base material when a pulse current is applied. In addition, there is an effect that generation of a large amount of spatter due to contact short-circuit can be suppressed.

Incidentally, as a means for preventing the occurrence of spatter, for example, one having a configuration as disclosed in Japanese Patent Application Laid-Open No. Sho 61-262469 has been proposed. In this configuration, the welding output voltage is compared with the reference voltage, and when the pulse current rises, when a short circuit occurs, the pulse current rises after an arc is generated, and the pulse current is cycled in the above cycle from the time the arc is generated. The spatter that is likely to occur during arc regeneration due to a short circuit is suppressed.

On the other hand, according to the present invention, the droplet does not short-circuit with the base material when the pulse current is applied, and the generation of spatter due to the short-circuit is suppressed.

Japanese Patent Application Laid-Open No. 61-3672 discloses that
A configuration is shown in which it is detected whether the welding voltage is equal to or greater than a certain value, and if the welding voltage is equal to or greater than the certain value, a set pulse peak current is output. This configuration is intended for smooth arc start and wire short circuit release.

On the other hand, according to the present invention, the separation of the droplet at the tip of the wire is promoted to ensure the transfer of the droplet to the base material.

[0020]

As is clear from the above description of the embodiment, according to the present invention, the peak voltage of the pulse of the welding output is detected, and the increase occurs when the droplet does not detach from the wire tip when the pulse current is applied. When the peak voltage of the welding output pulse exceeds the reference value, the peak current value of the pulse of the next pulse current is used to separate the droplet from the wire and transfer the droplet to the base metal.
Or increase the pulse width of the next pulse to ensure that the droplets separate from the wire and that the droplets
Extend to the extent that transfer is assured , or increase the rising slope of the next pulse by removing the droplet from the wire and dissolving it into the base metal.
By making the drop steep enough to ensure the transfer, even if a droplet that grows large without detaching at the wire tip occurs, the next pulse is immediately controlled and the droplet is detached, so the pulse Contact short-circuit with the base material during application of electric current is eliminated, and the generation of a large amount of spatter due to the contact short-circuit is suppressed, and welding defects such as pores can be eliminated. Thus, in arc welding of a galvanized steel sheet, it is possible to provide a consumable electrode type pulse arc welding machine capable of suppressing generation of spatters and pores with high welding efficiency.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a consumable electrode type pulse arc welding machine according to one embodiment of the present invention.

2A is a welding output voltage waveform diagram of the same, and FIG. 2B is a welding current waveform diagram of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference voltage setting part 2 Welding output voltage detection part 3 Comparator 4 Pulse current regulator 5 Pulse peak current value increasing means 6 Pulse width extending means 7 Pulse rising slope steepening means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-261537 (JP, A) JP-A 1-293976 (JP, A) JP-A-57-19184 (JP, A) JP-A-58-1983 141860 (JP, A) JP-A-57-19170 (JP, A) JP-A-57-36072 (JP, A) JP-A-1-118372 (JP, A) JP-A-62-267085 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/09 B23K 9/173 H02M 9/00 B23K 9/23

Claims (1)

(57) [Claims] 1. A consumable electrode type pulse arc welding machine which performs welding by superposing a pulse current using a mixed gas of an argon gas and a carbon dioxide gas as a main component of a shielding gas, and detects a peak voltage of a pulse of a welding output. The output voltage detection unit, the peak voltage of the welding output pulse is set in advance and compared with a reference voltage corresponding to the voltage at which the droplet is normally separated, the peak voltage of the welding output pulse is the reference voltage A comparator that outputs a signal when the signal exceeds the threshold voltage, and operates by a signal from the comparator, so that the peak current value and pulse voltage of the next pulse current are separated from the wire of the droplet.
Pulse peak current value increasing means to increase the removal and transfer of the droplet to the base material reliably, and the pulse width of the next pulse is separated from the wire and the transfer of the droplet to the base material is ensured
Pulse width expansion means to expand the droplet to the extent that it is performed and the rising gradient of the next pulse
A pulse current regulator including at least one of pulse rising gradient steepening means for steepening a droplet to such an extent that droplet transfer is reliably performed .