JPH071131A - Consumable electrode type pulse arc welding machine - Google Patents

Abstract

PURPOSE:To provide a high welding efficiency and to suppress generation of spatter and blow holes in the arc welding of galvanized sheet iron. CONSTITUTION:A welding output voltage is detected and compared with a reference voltage; when an increased welding output voltage, which is generated in the case where a droplet is not released from the wire tip at the time of impressing a pulsed current, is in excess of the reference voltage, the pulsed peak current of a succeeding pulsed current is increased by a means 5 for increasing a pulsed peak current value; the pulse width of the succeeding pulsed current is expanded by a pulse expanding means 6; and the rising gradient of the succeeding pulse is steepened by a means 7 for steepening a pulse rising gradient. Consequently, the release of the droplet and the moving of the droplet to a base material are surely performed in the succeeding pulsed current, and the generation of spatter and blow holes due to the short circuit are suppressed by a droplet contact short circuiting.

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 coated with zinc or a zinc alloy on its surface (hereinafter referred to as a galvanized steel sheet) has corrosion resistance,
Due to its excellent weather resistance, it is used for automobile parts, steel members for construction, etc., and its demand is increasing year by year.

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

[0004]

According to such conventional welding means, by means of arc welding, zinc having a melting point lower than that of iron plated on the surface of the steel sheet is vaporized and steam zinc is generated. This steam zinc disturbs the transfer of droplets by disturbing the gas shield and the arc, which causes a large amount of spatter. Also, steam zinc tries to diffuse to the outside through the molten pool and molten metal, but when the solidification rate of the molten metal is high, it cannot be diffused sufficiently to the outside, and as bubbles inside 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).

Further, although the amount of spatters and pores generated by pulse arc welding is smaller than that in the case of short-circuit transfer welding, the amount of spatters and pores is extremely large. This is because turbulence in the gas shield or arc caused by the generation of zinc vapor prevents the droplets from separating from the wire tip each time a pulse current is applied. The occurrence of spatter was caused by contact and short circuit with the base material during application.

The generation of such spatters and pores not only deteriorates the welding quality, but also requires repair of the welded part if the frequency of occurrence of these spoils is unacceptable. If the repair is impossible, the member is discarded. However, the work efficiency was lowered and the economy was seriously lost.

[0007] In response to such problems, at present, it is necessary to use low-speed welding, which has a relatively low speed in order to prevent generation of spatter and porosity, welding with a gap between steel plates, etc. It corresponded.

[0008] However, in such a measure, since the work speed is low, the work efficiency is low, it is difficult to prevent the generation of spatter, and the welding efficiency is lowered to further lower the work efficiency.

The present invention solves the above problems, and provides a consumable electrode type pulse arc welding machine which has a high welding efficiency and can suppress generation of spatter and pores in arc welding of galvanized steel sheet. It is an object.

[0010]

In order to achieve the above-mentioned object, the present invention provides a consumable electrode type pulse arc for welding by superimposing a pulse current with a mixed gas of argon gas and carbon dioxide as a main component of a shield gas. In a welding machine, a welding output voltage detection unit for detecting a welding output voltage and the welding output voltage are compared with a preset reference voltage, and a signal is output when the welding output voltage exceeds the reference voltage. A comparator, a pulse peak current value increasing means for increasing a pulse peak current value and a pulse portion voltage, a pulse width expanding means for expanding a pulse width, and a steep rising gradient of a pulse, which are operated by a signal from the comparator. And a pulse current adjuster including at least one of the pulse rising gradient steepening means.

[0011]

In the above structure, when the welding output voltage is detected and 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,
By increasing the pulse peak current value of the next pulse current and the pulse part voltage, or expanding the next pulse width, or making the rising slope of the next pulse steep,
The transfer of droplets to the base material becomes reliable when the next pulse current is applied.

[0012]

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

In FIG. 1, reference numeral 1 is a reference voltage setting section for setting a reference voltage, and 2 is a welding output voltage detecting section for detecting a welding output voltage, each connected to a comparator 3. 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 a pulse peak current value increasing means 5 for increasing the pulse peak current value and the pulse portion voltage, a pulse width expanding means 6 for expanding the pulse width, and a pulse rising for sharpening the rising slope of the pulse. At least one means of the gradient steepening means 7 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 is normally separated, and corresponds to a preset reference voltage. 12 is a pulse voltage waveform when the droplet at the wire tip does not separate as shown at time t,
The arc length increases temporarily and the welding output voltage increases.
Then, when the welding output voltage 12 exceeds the reference voltage 11, the comparator 3 outputs a signal to the pulse current regulator 4. With this signal, either the pulse peak current value increasing means 5 included in the pulse current regulator 4, the pulse width expanding means 6, the pulse rising slope steepening means 7, or a plurality of them operate to increase the pulse peak current value. Means 5
Indicates that the pulse peak current of the next pulse current is increased as indicated by A, the pulse extension means 6 extends the pulse width of the next pulse current as indicated by L, and the pulse rising gradient steepening means 7 is θ. As shown in, the rising gradient of the next pulse is made steep. The pulse waveform of the next pulse current becomes a waveform as shown by P by one or a plurality of operations of each of the means 5, 6, 7 as described above, and the droplet is separated from the wire and the droplet on the base material is separated. Make sure the transition happens.

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 being separated does not come into contact with the base material and short-circuit when the pulse current is applied. At the same time, there is an effect that it is possible to suppress generation of a large amount of spatter due to contact short circuit.

Incidentally, as a means for preventing the generation of spatter, for example, a structure as shown in Japanese Patent Laid-Open No. 61-262469 has been proposed. This configuration compares the welding output voltage with the reference voltage, and when the pulse current rises and is in a short circuit state, waits for the arc to start and then starts up the pulse current. In order to prevent spatter, which is likely to occur during arc regeneration due to a short circuit, the spatter is suppressed.

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

Further, in Japanese Patent Laid-Open No. 61-3672,
There is shown a configuration in which it is detected whether the welding voltage is a certain value or more and less than a certain value, and when the welding voltage is more than the certain value, the set pulse peak current is output, and when the welding voltage is less than the certain value, a pulse current more than the set value is output. This structure is intended for smooth arc start and wire short-circuit release.

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

[0020]

As apparent from the above description of the embodiments, according to the present invention, the welding output voltage is detected, and the increased welding output voltage generated when the droplet does not separate from the wire tip at the time of applying the pulse current. When the voltage exceeds the reference voltage, the pulse peak current value of the next pulse current is increased, the pulse width of the next pulse is expanded, or the rising gradient of the next pulse is made steep, so that the wire tip ends It is possible to prevent a droplet that grows large without contact from causing short circuit with the base material when a pulse current is applied, suppress generation of a large amount of spatter due to contact short, and eliminate welding defects such as pores. In this way, it is possible to provide a consumable electrode type pulse arc welding machine which can suppress the generation of spatters and pores with high welding efficiency in arc welding of galvanized steel sheets.

[Brief description of drawings]

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

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

[Explanation of symbols]

 1 Reference voltage setting unit 2 Welding output voltage detection unit 3 Comparator 4 Pulse current regulator 5 Pulse peak current value increasing means 6 Pulse width expanding means 7 Pulse rising slope steepening means

Claims (1)

[Claims] 1. A welding output voltage detector for detecting a welding output voltage in a consumable electrode type pulse arc welding machine for welding by superimposing a pulse current using a mixed gas of argon gas and carbon dioxide as a main component of a shield gas. And a comparator that compares the welding output voltage with a preset reference voltage, and outputs a signal when the welding output voltage exceeds the reference voltage, and operates by a signal from the comparator, and a pulse A pulse current including at least one of a pulse peak current value increasing means for increasing the peak current value and the pulse portion voltage, a pulse width expanding means for expanding the pulse width, and a pulse rising slope sharpening means for sharpening the rising slope of the pulse. A consumable electrode type pulse arc welder characterized by having a regulator.