JP3156033B2 - 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 pulse arc welding in which a pulse current is supplied between a welding wire and a welding base material (hereinafter simply referred to as "wire and base material") to generate an arc and perform welding.

[0002]

2. Description of the Related Art A large amount of spatter is generated when a galvanized steel sheet is welded by a pulse arc welding machine which supplies a pulse current between a wire and a base material to generate an arc and perform welding. This is because zinc, which has a lower melting point than iron, which is plated on the surface of the steel plate, evaporates, and this steam zinc tries to separate from the wire tip when trying to diffuse outside through the molten pool and molten metal. Push up the droplets or disturb the arc atmosphere. For this reason, the vapor zinc prevents the droplet from detaching from the tip of the wire at each pulse (hereinafter referred to as one pulse and one droplet), and when the droplet grows at the tip of the wire and short-circuits to the base material, a large amount of spatter is generated. appear. As a short-circuit clearing method of the conventional pulse arc welding machine, there is known a method of limiting the gradient of the short-circuit current only by the effect of the reactor or controlling the gradient at a predetermined constant gradient. However, as shown in FIG. 4 , the short-circuit current rises steeply and the short-circuit current value becomes 300 A or more only by the effect of the reactor, and a large amount of spatter is generated. In addition, when the short-circuit current is controlled at a predetermined constant gradient as shown in FIG. 5 , the short-circuit period becomes long, and the wire is forced into the molten pool or the pulse frequency is disturbed, so that the arc becomes unstable or spatter occurs. I do.

As described above, the arc becomes unstable,
If a large amount of spatter adheres to the base material, not only does the welding quality deteriorate, but if the frequency of occurrence of spatter becomes unacceptable, it is necessary to rework the welded part. It is sometimes discarded, resulting in reduced work efficiency and significant uneconomics.

[0004] At present, therefore, the instability of the arc and the generation of a large amount of spatter are dealt with mainly by devise based on experience, such as low-speed welding at a relatively low speed and welding with a gap between steel plates. However, there is no fundamental solution.

[0005]

Further, when a mild steel plate is welded with a conventional consumable electrode type pulse arc welding machine, one pulse and one droplet are formed as shown in FIG. If a short circuit occurs, it is released in a short time. However, when a galvanized steel sheet is welded, droplets grow at the tip of the wire without becoming one droplet per pulse as shown in FIG. 4, and the tip of the wire becomes large. When the increased wire tip short-circuits to the base material, a steep short-circuit current gradient causes a large amount of spatter. Conversely, if the short-circuit current gradient is a predetermined constant gradient as shown in FIG. 5, the short-circuit time becomes longer, the tip of the wire penetrates into the molten pool, and the pulse period is disturbed, which causes welding instability. . SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problem. In welding of a galvanized steel sheet or the like, when a droplet that has grown largely at a wire tip is short-circuited between the wire and a base material, spatter is generated. The present invention provides a consumable electrode type pulse arc welding machine which suppresses the pressure and stabilizes pulse arc welding.

[0006]

According to a first aspect of the present invention, there is provided a consumable electrode type pulse arc welding machine comprising: a welding wire; a welding base material;
Supply welding current plus base current and pulse current during
And to, in the which performs welding by generating arc, a welding voltage detection circuit unit for detecting the welding voltage, the welding voltage short arc judging circuit judges short or arcing by the output of the detection circuit unit, It includes a welding current detection circuit for detecting a welding current, and a short-circuit current control circuit unit for controlling the short-circuit current during short circuits, based conductive circuit current during short circuits
It has a function of outputting at a predetermined first current gradient from a current, and outputting at a predetermined second current gradient different from the first current gradient when the short-circuit current exceeds a predetermined current value.

According to a second aspect of the present invention, in the consumable electrode type pulse arc welding machine, the short-circuit current control circuit unit sets a short-circuit current to a first current gradient, and a short-circuit current to a second gradient current circuit. A second gradient setting circuit for setting the current gradient of
A bending point determining circuit for determining a bending point at which the short-circuit current is switched from the first current gradient to the second current gradient in response to an output of the welding current detecting circuit; and a first gradient based on an output of the bending point determining circuit. A first switching circuit unit for selecting an output of the setting circuit unit or an output of the second gradient setting circuit unit, an amplifying element for error-amplifying an output of the first switching circuit and an output of the welding current detection circuit unit, A second switching circuit for turning on or off the output of the amplifying element based on the output of the short-circuit arc determination circuit.

[0008]

In the consumable electrode type pulse arc welding machine according to the present invention, if the predetermined second current gradient is smaller than the first current gradient, the droplet that has grown largely at the tip of the wire will not be able to reach the wire and the base metal. When a short circuit occurs during the period, the occurrence of a large amount of spatter is suppressed by preventing the short circuit current value from increasing, and the welding can be stabilized by shortening the short circuit release time.

[0009]

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

Reference numeral 1 denotes a welding voltage detection circuit unit. Based on the detected value, a short-circuit arc determination circuit unit 2 determines whether a short-circuit or an arc has occurred. And the output signal of the amplifying element 4 is transmitted to the power element 5. That is, the short-circuit current control circuit unit 6 operates when a short circuit occurs, and does not operate when an arc occurs. The inflection point determination circuit section 7 receives the detection signal from the welding current detection circuit section 8 and determines whether the short-circuit current when a short circuit occurs is higher or lower than a predetermined set current value, and the second switching circuit This determination signal is output to the unit 9. The second switching circuit section 9 outputs the output from the first gradient setting circuit section 10 when the short-circuit current is lower than the predetermined set current value, and outputs the second output when the short-circuit current exceeds the predetermined set current value. The output from the gradient setting circuit section 11 is given to the amplification element 4. The amplification element 4 amplifies an error between the detection signal from the welding current detection circuit unit 8 and a setting signal having a predetermined gradient from the first gradient setting circuit unit 10 or the second gradient setting circuit unit 11, and performs the first amplification. A signal is given to the switching circuit unit 3.

In FIG. 1, reference numeral 12 denotes a three-phase AC input,
13 is a diode rectifier circuit, 14 is a transformer, 15 is a diode rectifier circuit, 16 is a reactor, 17 is a chip, 1
Reference numeral 8 denotes a wire, 19 denotes a base material, and 20 denotes CT.

FIG. 2 shows the output waveform of the present invention. This waveform shows a welding current waveform. Reference numeral 21 denotes a short-circuit period. When the short-circuit current is lower than the set current value 22, a short-circuit current is output at the first short-circuit current gradient 23, and when the short-circuit current is higher than the set current value 22, the second short-circuit current gradient At 24, a short-circuit current is output.

[0013]

As described above, by suppressing a large amount of spatter generated when a galvanized steel plate or the like is welded by the consumable electrode type pulse arc welding machine of the present invention, the welding quality is improved and the bead appearance is reduced. Elimination, and a reduction in work efficiency such as repair of a welded portion can be eliminated, and good welding workability can be maintained.

Further, by releasing the short-circuit when a short-circuit occurs, stable pulse arc welding can be performed.

[Brief description of the drawings]

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

FIG. 2 is a welding current waveform diagram at the time of welding a galvanized steel sheet according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a process of forming and transferring droplets and welding current waveforms during welding of mild steel according to a conventional example.

FIG. 4 is a diagram showing a relationship between a process of forming and transferring droplets and a welding current waveform during welding of a galvanized steel sheet of a conventional example.

FIG. 5 is a welding current waveform diagram when welding a galvanized steel sheet of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 welding voltage detection circuit section 2 short-circuit arc determination circuit section 3 first switching circuit section 4 amplifying element 5 power element 6 short-circuit current control circuit section 7 inflection point determination circuit section 8 welding current detection circuit section 9 second switching circuit section 10 first gradient setting circuit section 11 second gradient setting circuit section

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-94977 (JP, A) JP-A-2-290674 (JP, A) JP-A-57-19165 (JP, A) JP-A-61-1986 293672 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B23K 9/09

Claims (2)

(57) [Claims] A base electrode is provided between a welding wire and a welding base material.
In a consumable electrode type pulse arc welding machine that supplies a welding current obtained by adding a current and a pulse current to generate an arc and perform welding, a welding voltage detection circuit unit that detects a welding voltage, and a welding voltage detection circuit unit A short-circuit arc determination circuit for determining a short-circuit or arc by an output; a welding current detection circuit for detecting a welding current; and a short-circuit current control circuit for controlling the short-circuit current when a short-circuit occurs. A consumable electrode type pulse arc welding machine that outputs at a predetermined first current gradient from a base current and outputs at a predetermined second current gradient different from the first current gradient when the short-circuit current exceeds a predetermined current value. 2. A short-circuit current control circuit section according to claim 1, wherein
A first gradient setting circuit for setting the current gradient to a second gradient, a second gradient setting circuit for setting the short-circuit current to the second current gradient, and receiving the output of the welding current detecting circuit to reduce the short-circuit current to the first current. A bending point determination circuit for determining a bending point at which the gradient is switched from the gradient to the second current gradient, and an output of the first gradient setting circuit or an output of the second gradient setting circuit is selected based on an output of the bending point determination circuit. A first switching circuit;
An amplification element for error-amplifying an output of the switching circuit section and an output of the welding current detection circuit section, and a second switching circuit section for turning on or off the output of the amplification element based on an output of the short-circuit arc determination circuit section. Item 6. A consumable electrode type pulse arc welding machine according to item 1.