JP4806838B2 - Method and apparatus for controlling welding arc - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welding arc control method and a welding arc control apparatus for carrying out the method.
[0002]
[Prior art]
As shown in FIGS. 6 and 7, the conventional welding apparatus includes an electrode 2 to which electric power is supplied from a welding power source 1 and a welding wire 3, and an arc is formed between the electrode 2 and the base material 4. 5 is generated, and the welding wire 3 is melted by the arc to form a bead in the groove 4a of the base material 4, so that welding is performed following the groove 4a. The electrode 2 is attached to a torch body (not shown) that moves along the groove 4a.
During welding, the distance of the electrode 2 relative to the base material 4 is automatically adjusted by moving the torch body up and down based on the detected arc voltage in order to adjust the arc length generated between the electrode 2 and the base material 4. A so-called arc length control (AVC) is performed.
[0003]
[Problems to be solved by the invention]
However, in the conventional welding apparatus, as shown in FIG. 7, when the groove 4 a of the base material 4 is narrow, when the electrode 2 (for example, made of tungsten) is energized, a magnetic field is formed between the electrode 2 and the base material 4, The magnetic field causes a so-called magnetic blow in which the arc 5 is deflected forward in the welding direction W as shown in FIG. 8A or deflected backward in the welding direction W as shown in FIG. 8B. There is.
[0004]
When magnetic blowing occurs in this way, the arc voltage usually increases. Therefore, the conventional welding apparatus has a problem that the electrode 2 and the base material 4 are likely to be short-circuited as a result of bringing the electrode 2 closer to the base material 4 by controlling the arc length in order to lower the voltage.
[0005]
Such a problem is particularly likely to occur at the end of the base material 4 having a large thickness and provided with the narrow groove 4a. Conventionally, when a magnetic blow occurs, it has been dealt with by changing the mounting position of the ground, but the effect is often low.
[0006]
In view of the above circumstances, an object of the present invention is to provide a welding arc control method capable of reliably performing welding regardless of magnetic blowing, and a welding arc control device capable of accurately carrying out the method. Is to provide.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs the following means.
The present invention relates to a welding method in which an arc is generated between an electrode and a base material, and a bead is formed at the groove of the base material by the arc, and an arc voltage and a front position disposed at a front position and a rear position of the electrode. The wire voltage of the wire and the back wire is controlled to control the deflection direction of the arc.
[0008]
In this way, during welding, the arc voltage (including polarity) and the wire voltage (including polarity) of the front wire and the rear wire arranged at the front and rear positions of the electrode are controlled, respectively, to deflect the arc. By controlling the direction, it is possible to reliably perform welding regardless of magnetic blowing.
[0009]
In the welding apparatus in which an arc is generated between an electrode and a base material, and a bead is formed in the groove of the base material by the arc, in order to control the deflection direction of the arc, an arc voltage, It has an arc direction adjustment control part which controls the wire voltage of the front wire and back wire which are arranged at the front position and the back position, respectively.
[0010]
In this way, the arc direction adjustment control unit controls the arc voltage and the wire voltage of the front wire and the back wire arranged at the front position and the back position of the electrode, respectively, thereby controlling the deflection direction of the arc, The method of claim 1 can be performed accurately.
[0011]
The present invention is characterized in that the arc direction adjustment control unit has comparison determination means for determining an arc deflection direction when the arc voltage is higher than a set value and the wire voltage deviates from the set voltage.
[0012]
Thus, when the arc voltage is higher than the set value and the wire voltage deviates from the set voltage by the comparison / determination means, the arc deflection direction by the magnetic blow is determined, so that the arc deflection direction can be specified reliably. Can do.
[0013]
The present invention is characterized in that the arc direction adjustment control unit has switching means for inverting the polarity of the wire voltage supplied to the front wire and the rear wire.
[0014]
Thus, since the polarity of the wire voltage supplied to the front wire and the rear wire is reversed by the switching means, the arc direction can be forcibly returned.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4 show an embodiment of a welding apparatus to which the method of the present invention is applied.
As shown in FIG. 1, a welding apparatus to which the method of the present invention is applied is arranged at an electrode 11, a front wire 12 disposed at a front position of the electrode 11 along the welding direction W, and a rear position of the electrode 11. And a rear wire 13. Although not shown in detail, the electrode 11 is formed in a round bar shape or a band plate shape with a sharp tip, and is attached to a torch body that moves along the groove of the base material 20. The torch body is omitted in FIG.
[0016]
Further, a welding power source 14 for supplying welding power is connected to the electrode 11 and the base material 20, and a wire overheating power source 15 for overheating them is connected to the front wire 12 and the rear wire 13. The electrode 11 is connected to the negative electrode of the welding power source 14 and the base material 20 is connected to the positive electrode. In this example, the wire overheating power supply 15 has the rear wire 13 connected to the negative electrode and the front wire 12 connected to the positive electrode.
[0017]
Further, a switch 16 for switching the polarity to be connected to the front wire 12 and the rear wire 13 is connected to the wire overheating power source 15, and the switch 16 and the welding power source 14 are connected to the welding arc control device 17. Has been.
[0018]
As shown in FIG. 2A, the control device 17 controls the current supplied to the electrode 11, the current supplied to the front wire 12 and the rear wire 13, and also controls the supply amount of each of the wires 12 and 13. In addition, the traveling of the carriage on which the torch body is mounted is controlled via a drive unit (not shown). FIG. 2B shows another example of control by the control device 17, and a DC pulse is supplied as a welding current as in the case of FIG. The welding current is not limited to a direct current pulse, and may be a constant direct current.
[0019]
Further, the control device 17 detects a change in the voltage supplied to the electrode 11 using the characteristic that the arc voltage increases when the distance between the base material 20 and the electrode 11 is increased during welding, and the voltage is set. It has an arc length controller 18 for controlling (AVC) so as to keep the distance of the electrode 11 with respect to the base material 20 constant so as to be a voltage.
[0020]
Furthermore, when a magnetic blow occurs due to a current flowing through the electrode 11 during welding, the arc is deflected due to the influence of the magnetic blow. This control device 17 determines the arc deflection direction, thereby switching the switch. An arc direction adjustment control unit 19 that switches and connects the polarity of the wire overheating power source 15 with respect to the front wire 12 and the rear wire 13 via 16 is provided.
[0021]
That is, when the front wire 12 is connected with the positive electrode and the rear wire 13 is connected with the negative electrode with respect to the wire overheating power source 15, the arc direction adjustment control unit 19 causes the arc 22 to be affected by the magnetic blow, for example, as shown in FIG. When the arc voltage is higher than the set voltage and the wire voltage deviates from the set voltage, the switch 16 is instructed to switch the front wire 12 and the rear wire 13 by the switch 16. 1, the polarity is switched to the opposite polarity, and both the electrode 11 and the front wire 12 are set to the negative electrode on the positive electrode base material 20, thereby pulling the arc 22 forward, and forcibly causing the arc 22 to be forced. The original normal position is restored.
[0022]
On the other hand, for example, as shown in FIG. 3, when the front wire 12 and the rear wire 13 are connected to the wire overheating power source 15 with opposite polarities, the arc 22 is biased forward in the welding direction W due to the influence of magnetic blowing. When turned, the arc direction adjustment control unit 19 switches the polarity as shown in the figure by the switch 16, makes the front wire 12 a positive electrode, makes the rear wire 13 a negative electrode, pulls the arc 22 rearward, Return to normal position.
[0023]
That is, the arc direction adjustment control unit 19 detects changes in the arc voltage and the wire voltage, respectively, and compares the determination unit 19a that determines that the arc is deflected by the influence of the magnetic blow based on the detection, and the front wire 12 And a switch 16 that reverses the polarity of the wire voltage (or wire current) supplied to the rear wire 13.
[0024]
Next, the contents of control by the control device 17 will be described with reference to FIG.
At the time of welding, as shown in FIG. 1, the electrode 11 is connected to the negative electrode of the welding power source 14 and the base material 20 is connected to the positive electrode, and the rear wire 13 is connected to the negative electrode of the wire overheating power source 15. Welding is started by connecting the front wires 12 and supplying the necessary power to each of them in this state.
[0025]
At the time of welding, the arc direction adjustment control unit 19 in the control device 17 monitors the arc voltage in FIG. 4 (S41), and whether the arc voltage is a preset voltage or higher or lower. Is checked (S42).
As a result of this check, if the set voltage is reached, welding is continued, and if the set voltage is lower than the set voltage, the torch body is raised via a drive unit (not shown) (S43), and the processing after S41 is executed.
[0026]
On the other hand, if the arc voltage is higher than the set voltage, since there is a possibility that the magnetic blow occurs, and detecting the wire voltage of the front wire 12, a wire voltage of the rear wire 13, respectively, Compared with a preset voltage, the difference is checked (S44). As a result of the check, for example, when the voltage of the front wire 12 is high (S45), the arc direction adjustment control unit 19 determines that the arc 22 is deflected backward (S46) and operates the switch 16 to overheat the wire. The polarity of the power supply 15 is reversed (S47). Thereby, while the polarity with respect to the front wire 12 becomes a negative electrode, the polarity with respect to the rear wire 13 becomes a positive electrode (S48). Thus, when the polarity is reversed, the arc 22 deflected backward due to the influence of the magnetic blow is forcibly pulled forward as shown by the solid line in FIG. 1, and as a result, the arc is returned to the normal position. It is.
[0027]
Thereafter, it is checked whether or not the wire voltages of the front wire 12 and the rear wire 13 are set voltages (S49). If the set voltages are set, welding is continued as it is (S56). The processing from S44 onward is repeatedly executed until it becomes.
[0028]
On the other hand, when the voltage of the rear wire 13 is high in S44 (S50), it is determined that the arc 22 is deflected forward (S51). Then, by inverting the wire polarity via the switcher 16 (S52), the front wire 12 becomes the positive electrode and the rear wire 13 becomes the negative electrode (S53). As a result, the arc is pulled backward as shown in FIG. 3, and as a result, the arc is returned to the normal position. Thereafter, the process proceeds to the process 49 as described above.
[0029]
In S44, for example, when the wire voltage of the front wire 12 is low (S54), the processing after S51 is repeatedly executed as in the case where the wire voltage of the rear wire 13 is high. That is, also in this case, it is determined that the arc 22 is deflected forward, and the wire polarity reversal processing makes the front wire 12 the positive electrode and the rear wire 13 the negative electrode.
[0030]
Further, in S44, when the voltage of the rear wire 13 is low (S55), the processing after S46 is executed as in the case where the wire voltage of the front wire 12 is high.
Thus, when the arc voltage is high and the wire voltage between the front wire 12 and the rear wire 13 deviates from the set voltage, it is determined that the magnetic blow has occurred, and based on that, the front wire 12 and the rear wire 13 are determined. The wire voltage returns to the set voltage by changing the polarity of the wire voltage (the polarity of the wire current) and deflecting the arc 22 in the reverse direction to deal with the influence of the magnetic blow.
And in S49, if the wire voltage of both the front wire 12 and the back wire 13 becomes a setting voltage, welding will be continued.
[0031]
In the method of the present invention, as described above, the arc voltage and the wire voltages of the front wire 12 and the rear wire 13 are detected (referred to as a detection process), and the deflection direction of the arc is determined based on the fluctuation of the arc voltage and the wire voltage. However, since the arc is deflected in the reverse direction in accordance with the deflection direction of the arc and the arc 22 is returned to the original normal position (referred to as the return process), when the magnetic blow occurs, the arc 22 Can be deflected in the opposite direction and returned to its original position. Therefore, even if a magnetic blow occurs, welding can be continuously performed regardless of this, and even a thick base metal having a narrow groove can be welded.
[0032]
Moreover, in the determination step, when the arc voltage is higher than the set voltage and the wire voltage between the front wire 12 and the rear wire 13 deviates from the set voltage, the wire voltage of the front wire 12 and the rear wire 13 are compared by the comparison / determination unit 19a. The arc deflection direction can be reliably determined based on the wire voltage and the difference.
In the return step, the switch 16 instructed by the arc direction adjustment control unit 19 reverses the polarity of the wire power supplied to the front wire 12 and the rear wire 13, so that the direction of the arc 22 is forcibly set. Can be returned.
[0033]
In addition, the arc direction adjustment control unit 19 includes a comparison / determination unit 19a that determines the deflection direction of the arc due to magnetic blowing when the arc voltage is higher than a set value and the wire voltage deviates from the set voltage. Since the configuration is such that the polarity of the wire voltage supplied to the front wire 12 and the rear wire 13 by the device 16 is reversed, the determination step and the return step can also be performed accurately.
[0034]
FIG. 5 shows another embodiment.
The welding arc control device shown in FIG. 5 has two wire overheating power supplies 15A and 15B that supply wire power independently to the front wire 12 and the rear wire 13, respectively. 12 and the rear wire 13 are connected with the same polarity as in the case shown in FIG.
[0035]
When the arc voltage is higher than the set voltage and the wire voltage between the front wire 12 and the rear wire 13 is larger or smaller than the set voltage, the control device 17 causes the arc direction adjustment control unit 19 to The polarities of the wire overheating power supplies 15A and 14B are reversed. In addition, since it is the structure similar to embodiment mentioned above other than that, description is abbreviate | omitted.
Therefore, according to this embodiment, since the polarities of the wire overheating power supplies 15A and 15B are reversed by the control device 17, the same operational effects as those of the above-described embodiment can be obtained with certainty.
[0036]
【The invention's effect】
As described above, according to the present invention , the arc deflection direction of the arc can be controlled by controlling the arc voltage and the wire voltages of the front wire and the rear wire disposed at the front position and the rear position of the electrode, respectively, during welding. By controlling, welding can be reliably performed regardless of magnetic blowing. Therefore, there is an effect that stable quality welding can be obtained even with a base material having a thick narrow groove.
[0037]
According to the present invention , the arc direction adjustment control unit controls the arc voltage and the wire voltage of the front wire and the rear wire arranged at the front position and the back position of the electrode, respectively, thereby controlling the deflection direction of the arc. And there exists an effect which can implement the control method of the welding arc of this invention exactly.
[0038]
According to the present invention , the comparison / determination means determines the deflection direction of the arc based on the difference between the wire voltage of the front wire and the wire voltage of the rear wire. is there.
[0039]
According to the present invention , since the polarity of the wire voltage supplied to the front wire and the rear wire is reversed by the switching means, there is an effect that the direction of the arc can be forcibly returned.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a welding apparatus to which a control device for carrying out the method of the present invention is applied.
FIG. 2 is an explanatory diagram showing each control content in the control device.
FIG. 3 is an explanatory diagram showing a case where connection is performed with a reverse polarity to the connection example of FIG. 1;
FIG. 4 is a flowchart showing the control contents of the control device when magnetic blow occurs.
FIG. 5 is an explanatory view showing another welding apparatus to which a control device for carrying out the method of the present invention is applied.
FIG. 6 is an explanatory view showing a conventional welding apparatus.
FIG. 7 is an explanatory diagram in the case of welding to a thick and narrow groove base metal.
FIG. 8 is an explanatory diagram in which an arc is deflected in a welding direction or deflected in a direction opposite to the welding direction due to the influence of magnetic blowing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Electrode, 12 ... Front wire, 13 ... Back wire, 14 ... Welding power supply, 15, 15A, 15B ... Wire overheating power source, 16 ... Switch (switching means), 17 ... Control apparatus, 19 ... Arc direction adjustment control part , 19a ... Comparison determination unit (comparison determination means)

Claims (2)

In the welding method in which an arc is generated between the electrode and the base material and a bead is formed in the groove of the base material by the arc,
When the arc voltage is higher than the set value and the wire voltage of the front wire and the rear wire arranged at the front position and the back position of the electrode deviates from the set voltage, the deflection direction of the arc is determined, and based on the determination A method for controlling a welding arc, comprising: controlling a deflection direction of an arc by inverting a polarity of a wire voltage supplied to the front wire and a polarity of a wire voltage supplied to the rear wire . In a welding apparatus that generates an arc between an electrode and a base material, and forms a bead at the groove of the base material by the arc,
In order to control the deflection direction of the arc, it has an arc direction adjustment control unit for controlling the arc voltage, the front wire disposed at the front position of the electrode, the wire voltage of the rear wire, respectively,
The arc direction adjustment control unit,
Switching means for inverting the polarity of the wire voltage supplied to the front wire and the rear wire;
When the arc voltage is higher than the set value and the wire voltage deviates from the set voltage, it has a comparison determination means for determining the deflection direction of the arc,
Based on the determination of the deflection direction of the arc , the arc deflection direction is controlled by inverting the polarity of the wire voltage supplied to the front wire and the polarity of the wire voltage supplied to the rear wire. Welding arc control device.

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