JPS6171184A - Automatic arc welding method - Google Patents

Abstract

PURPOSE:To detect a dislocation width in a short time, and to execute arc welding at a high speed by setting plural teaching points at a desired position of a teaching welding line, detecting a dislocation width against an actual weld ing line by an arc scan, and correcting the teaching welding line, based on the detected dislocation width. CONSTITUTION:Dislocation detecting teaching points m1, m2 and m3 are set at a desired position of a teaching welding line 200. In this case, the teaching points are set at a part where a dislocation of works 20a, 20b on the welding line 200 is apt to be generated. Subsequently, whenever an arc welding reaches the teaching points m1, m2 and m3, a dislocation detecting arc scan by a welding wire 16 is executed along a detecting line SE. In case when a dislocation of a dislocation width (d) has been detected, the teaching welding line 100 based in the dislocation width (d), in a section to the next teaching point, and an arc welding is executed to the works 20a, 20b along the corrected teaching welding line.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic arc welding method, particularly an automatic arc welding method in which a welding wire is moved along a predetermined teaching welding line programmed in advance to perform arc welding on a workpiece. Regarding improvements.

[Prior Art J] Conventionally, an automatic arc welding method is well known in which, for example, a teaching playback method is adopted and a predetermined welding line is taught to a computer, etc. According to this welding method, the set teaching welding line Because it is possible to automatically weld workpieces by moving the torch according to the instructions, it is widely used, for example, in automobile welding processes and other mass production lines.

By the way, in order to perform arc welding satisfactorily on such a teaching welding line, it is necessary to accurately position the workpiece to be welded along a predetermined welding line.

However, in practice, it is unavoidable that misalignment of the workpiece occurs due to dimensional errors in the workpiece itself, thermal distortion during arc welding, errors in the jig used to position the workpiece, etc. Welding defects such as poor welding occur due to positional misalignment.

Conventionally, various positional deviation detection operations have been performed to detect such positional deviations of the workpiece. For example, when using the weaving method, the welding wire is alternately vibrated ( Arc welding is performed on the workpiece by sewing along the welding line while weaving. According to this method, the positional deviation of the workpiece can be detected from the positional deviation of the welding voltage and welding current during weaving.

[Problem to be solved by the invention 1
Since the positional deviation detection operation is performed continuously over the entire welding line from the start position to the end position, the welding speed is significantly reduced. For example, when performing weaving arc welding as the positional deviation detection operation, The welding speed is 1) 2 compared to when welding without
There was a drawback that arc welding of workpieces could not be performed efficiently.

In particular, according to such conventional methods, when the welding line of the workpiece is extremely long, arc welding of the workpiece requires an extremely long time, and an effective countermeasure for this problem has been desired.

Purpose of the Invention The present invention has been made in view of such conventional problems, and its purpose is to correct the positional deviation between the teaching welding line and the actual welding line, and to correct the positional deviation between the teaching welding line and the actual welding line, and to correct the positional deviation of the workpiece along the welding line. An object of the present invention is to provide an automatic arc welding method capable of performing arc welding at high speed.

[Means for Solving the Problems] In order to achieve the above object, in the method of the present invention, first, a plurality of positional deviation detection teaching points are set in advance at desired positions on the teaching welding line.

Then, when moving the welding wire along the teaching welding line to perform arc welding on the workpiece, the welding wire performs a predetermined positional deviation detection arc scan to detect the positional deviation of the workpiece every time the welding line reaches each teaching point. At this time, the deviation width of the teaching welding line from the actual welding line is detected based on the change in the arc that occurs. .

As a result of this positional deviation detection arc scanning, if a positional deviation of the workpiece is detected, the teaching welding line is corrected to match the actual welding line based on the detected deviation width, and the area up to the next teaching point is adjusted. Change the welding conditions to misalignment welding and perform arc welding that accommodates the misalignment of the workpiece.

[Operation] Therefore, according to the method of the present invention, positional deviation detection arc scanning is performed only at each teaching point, and normal arc welding is performed along the welding line between each teaching point. Arc welding can be performed at high speed, and arc welding can be performed in a short time even on long-distance welding lines.

Further, according to the method of the present invention, by setting each positional deviation detection teaching point corresponding to the location where the positional deviation of the workpiece is expected to occur, the positional deviation of the workpiece can be reliably detected. If this positional deviation is detected, the teaching welding line is corrected to the next teaching point to match the actual welding line and arc welding is performed, so arc welding of the workpiece is performed regardless of whether or not there is any positional deviation of the workpiece. This can be done reliably.

[Example] Next, preferred embodiments of the present invention will be described based on the drawings.

Principle of the present invention FIG. 2 shows an automatic arc welding device used in this embodiment.
A torch 14 is attached and fixed to the tip of an arm 12 provided at 0, and the torch 14 is configured to be movable three-dimensionally by the operation of the arm 12.

The welding torch 14 is configured such that a welding wire 16 can be fed from its tip, and the workpiece 2 can be fed from the welding power source 18.
By applying a predetermined welding voltage between the welding wire 16 and the welding wire 16, an arc is generated between the two, and the workpiece 20 is arc welded.

When such 7-way welding is performed, the tip of the welding wire 16 is gradually consumed, so it is necessary to sequentially replenish the welding wire 16 with a length corresponding to the consumption m. For this reason, in the apparatus of the embodiment, the welding wire 16 is wound around a predetermined machine drum 22 in advance, and the welding wire 16 wound in this way is sequentially and continuously fed by the feed motor 24 according to the amount of wear. We are supplying

Further, in the apparatus of the embodiment, the shielding gas sealed in the gas shielding cylinder 26 is ejected in the direction toward the tip of the welding wire 16 through the torch 14, so that the workpiece 20 can be welded well.

Furthermore, in the apparatus of the embodiment, the welding line of the workpiece 20 is taught in advance prior to the arc welding, and the teaching welding line is programmed into the memory in the robot control (1!28).

The robot control board 28 controls the welding robot 10 to weld the workpiece 20 along the teaching welding line every time the workpiece 20 is installed using a jig (not shown).

FIG. 1 shows a case where one basic workpiece 20a and the other workpiece 20b are positioned along a predetermined teaching welding line 200, and the automatic arc shown in FIG. By performing arc welding along the teaching weld 200 using the welding device, one work 20a is reliably arc welded to the other work 20b.

By the way, as shown by the chain line in the figure, the basic work 2O
a, if the other workpiece 20b is positioned with a predetermined deviation width d from the teaching welding line 200, the preset teaching welding line 200 will be misaligned with the actual welding line 100, and both Work 20a.

There is a problem that arc welding of 20b cannot be performed.

A characteristic feature of the present invention is the teaching welding line 2001. : Arc welding of cured workpieces 20a and 20b is performed at high speed, and teaching welding line 20
0 and the actual welding line 100 of the workpiece 20, this is reliably detected and the welding line is corrected to prevent welding defects on the workpieces 20a and 20b. The reason lies in the fact that it has become possible to do so.

Therefore, the method of the present invention is suitable for teaching welding line 2.
A plurality of positional deviation detection teaching points ml, m2, m3, . . . are set in advance at the desired position of 00. Here, these positional deviation detection teaching points m
l*m2rmj... is the workpiece 20a on the teaching welding line 200.

The settings are made in accordance with the locations where misalignment of 20b is likely to occur.

Then, each time the arc welding performed along the teaching welding line 200 reaches each positional deviation detection teaching point m,, m2, m3..., the welding wire 1
6, a predetermined positional deviation detection arc scan is performed to detect a positional deviation between the teaching welding line 200 and the actual welding line 100.

As a result of performing this positional deviation detection arc scanning, if the positional deviation is not detected at the teaching point J3, the workpieces 20a, 20 are moved along the teaching welding line 200 to the next teaching point.
Perform arc welding in b.

In addition, if a positional deviation with a predetermined deviation width d is detected at the teaching point as a result of the above-mentioned positional deviation detection arc scanning, the area up to the next teaching point is calculated based on the detected deviation width d. Matching the teaching welding line 200 with the actual welding line 100i
The arc welding of the works 20a and 20b is performed along the corrected teaching welding line.

In this manner, according to the method of the present invention, positional deviation detection teaching points m, , m2 are arbitrarily set on the teaching welding line 200.

m3...Only a predetermined positional deviation detection arc scan is performed, and normal arc welding is performed at other locations, so the positional deviation between the teaching welding line 200 and the actual welding line 100 is detected. By minimizing the time delay that occurs due to
It becomes possible to perform 0b arc welding at high speed. Moreover, each position misalignment detection teaching point m + +
m 2 i m! Teaching welding line 2
00, the teaching welding line 2 can be
00 and the actual welding line 100 and correct the teaching welding line 200 to match the actual welding line 100.
, 20b can be reliably arc welded along the actual welding line 100 to prevent welding defects from occurring.

Further, according to the present invention, by simply performing positional deviation detection arc scanning, the teaching welding line 200 and the actual welding line 100 can be separated without using any special detection device.
It is possible to reliably detect the positional deviation between the arc welding device and the arc welding device, and the structure of the device used for arc welding can be made simple and inexpensive.

1. Here, each of the teaching points m, , m2
Various detection operations can be adopted as the positional deviation detection arc scanning performed in , m..., and in this embodiment, automatic arc welding is performed using the positional deviation detection arc scanning described below. Is going.

FIGS. 1 and 3 show positional deviation detection arc scanning performed in this embodiment. Positional deviation detection arc scanning is performed, and the deviation width d of the teaching welding line 200 with respect to the actual welding line 100 is detected based on the arc current or voltage change generated at this time.

In the embodiment, this arc scanning for positional deviation detection is performed on a detection line SE perpendicular to the teaching welding line 200.
The arc scanning direction may be from S to E or from E to S.

In the embodiment, this arc scanning for positional deviation detection is performed from S to E, and at this time, it is expected that the positional deviation of the workpiece 20b will occur only on the 8 point side with respect to the teaching welding line 200. In this case, it is sufficient to perform arc scanning for detecting positional deviation from 8 points to point A.
In addition, if it is expected that the positional deviation of the workpiece 2ob will occur on both the 8 point side and the E point side of the teaching welding line 200, it may be set to perform arc scanning for positional deviation detection from S to E. .

Here, the scanning distance of the arc scan for positional deviation detection can be arbitrarily set according to the type of workpiece 20b and the deviation width d that is expected to occur. The total distance to point 8 and point E is set to 3 to 5 mm, respectively.

FIG. 3 shows the positional deviation detection arc scan performed in this manner, and FIG. 4 shows the arc current waveform at this time.

First, arc scanning for positional deviation detection is performed from S to E. At this time, the workpiece 20b is on the teaching welding line 20.
If the workpiece 20 is accurately positioned with respect to 0, this scanning line changes from S→A-+C-+E, but
When point b is positioned with a predetermined deviation width d from the teaching welding line 200, the scanning line changes from S→A--ζC'→E.

As shown in FIG. 4, the change in arc current at this time is constant in the S-+A' section, rapidly increases in the A'→C- section, and becomes constant again in the C-→E section.

This is because when arc scanning is performed in the section A'→C', the tip of the welding wire 16 is consumed along A'C-, and the length of the welding wire 16 is shortened, resulting in an arc current circuit. This is due to a decrease in the resistance value of .

That is, when arc scanning the S-+A' section,
The feeding amount of the welding wire 16 is balanced with the amount of wear and its length becomes almost constant, but when scanning the section A-→C', the tip of the wire suddenly reaches A''C of the workpiece. - face (
t11 wall), and the arc length is momentarily shortened before the wire 16 melts excessively. Since the arc part has a much higher resistance value than the wire itself, at this moment wire 1
6 and the total resistance of the arc column decreases significantly, resulting in a rapid increase in arc current. This sudden increase in current causes wire 1 to
6 melts in excess and eventually returns to its original arc length. In addition, when arc welding is performed in the C-→E section, the feeding amount and consumption amount of the welding wire 16 are balanced, and the length becomes a constant value in a state where the length is decreased. Therefore, the resistance value in the arc current circuit is constant in the section S → A', and A'
->C' section, it decreases rapidly, and then C'->E section, it decreases again and becomes constant.

As a result, when performing positional deviation detection arc scanning from point 8 to point E, the arc current is as shown in Fig. 4.
Since the arc current increases rapidly in the section A'→C', if this point where the arc current starts to increase is detected, the workpiece 2 of the workpiece 20b
The installation position relative to 0a, that is, the actual welding line 100 of the works 20a, 20b can be detected. Note that the method of detecting the welding point of the workpiece based on changes in arc characteristic values, the so-called arc sensing method, can be performed in the same manner as using current, as in this embodiment, or by using voltage changes.

And in this way each teaching point ml
, m2, m3... If it is determined that there is no positional deviation, normal arc welding is started along the teaching welding line 200 and the teaching point is moved to the next teaching point. When this point is reached, similar positional deviation detection arc scanning is repeated.

Further, as a result of performing the positional deviation detection arc scanning, if a positional deviation having a deviation width d is detected at the teaching point, the teaching welding line 200 is adjusted based on the detected deviation width d, as described above. The work is corrected to match the actual welding line 100, and the workpiece is arc welded along the corrected teaching welding line up to the next teaching point.

In this way, according to the present invention, the time delay that occurs for detecting the deviation width between the teaching welding line 200 and the actual welding line 100 is suppressed to a minimum, and the workpiece 2
0a and 20b can be arc welded at high speed along the actual welding line 100. In addition, by setting the positional deviation detection teaching points m, m2, mj, etc. corresponding to locations on the teaching welding line 200 where positional deviation is likely to occur, the teaching welding line 200 can be used for actual welding. By correcting the arcs 20a and 2ob so as to match the line 100, it is possible to reliably arc weld the arcs 20a and 2ob along the actual welding line and prevent welding defects from occurring.

Note that the positional deviation detection teaching points m, , m
2, m, . . . , it is preferable to set the first teaching point m1 to the welding start point of the teaching welding line 200, and by doing so, the workpiece 20a.

It becomes possible to reliably perform arc welding 20b along the actual welding line 100 from the welding start position.

Figure 5 shows a specific electric circuit for carrying out the automatic arc welding method of this embodiment described above, and Figure 6 shows its signal waveform. .

The device of the embodiment includes a teaching welding line 200 and positional deviation detection teaching points m, m2, mj, arbitrarily set on the teaching welding line 200.
... is preprogrammed in the memory in the line output circuit 40, and the line output circuit 40 outputs a welding start command signal to the welding power source 18, and also outputs a position signal of the teaching welding line 200 to the position control system 42. Output.

The welding power source 18 applies a predetermined welding pulse voltage between the torch 14 and the workpiece 20 at the same time that the welding start command signal is outputted in this way to generate an arc.

The position control system 42 includes a sieve reducer 44, an amplifier 46, an actuator 48, and a feedback circuit 50, and controls the movement of the torch 14 in accordance with the teaching welding line signal output from the line output circuit 40,
0a and 20b are reliably arc welded along a teaching welding line 200.

Although a robot is normally provided with a plurality of position control systems 42, only one of them is shown and described in the embodiment for the sake of simplicity.

In the apparatus of the embodiment, when performing arc welding along such a teaching welding line 200, arc welding is carried out at each teaching bond point m, , m2 , mj .
In order to detect that . . .
is provided at the output stage of the amplifier 46, and this coincidence confirmation circuit 52 outputs a point detection signal W immediately before the torch 14 reaches each teaching point m, m2, mj, . . . based on the output of the amplifier 46. , the point 1-detection signal W is supplied to the welding line output circuit 40 and delayed by a delay circuit 54 to a simulated detection command circuit 56.
Direction is supplied.

The line output circuit 40 outputs each teaching point ml each time the point 1 to detection signal W is supplied in this way.
, m2. A point signal X representing mj . . . is supplied to the detection command circuit 56.

The detection command circuit 56 is thus triggered by the AND input (logical product) of the signals W and Outputs command pulse Y.

In this manner, in the apparatus of the embodiment, arc welding along the teaching welding line 200 is performed from the detection command circuit 56 to each teaching point ml, m7, m.
A positional deviation detection command pulse Y is output every time j... is reached, and while this pulse Y is being output, the teaching welding line signal output from the welding line output circuit 40 is held.

In addition, the device of the embodiment has each teaching point 1 to m1.
, m2, mj . A selection switch 60 for selectively supplying the positional deviation detection command pulse Y to the position control system 42 is provided, and every time the positional deviation detection command pulse Y is output, the switch 6° is set to the detection line output circuit 58 side only at the time of that pulse. , each teaching point ml, mi, m3 output from the detection line output circuit 58
. . , the detection line SE is inputted to the position control system 42.

In this way, in the apparatus of the embodiment, each time the arc welding along the teaching welding line 200 reaches each teaching point ml, m2, m3...
As shown in FIG. 3 of IO, the torch 14
Positional deviation detection arc scanning is started along E.

Furthermore, when the positional deviation detection command pulse Y is output,
The welding power source 18 is controlled by the pulse Y, and the arc current is controlled for positional deviation detection arc scanning during the pulse time t.

Therefore, by detecting the change in arc current 1 (t) or arc voltage V (t) that occurs during the time t during which this positional deviation detection arc scan is performed, each teaching point m, m2, m3,... It becomes possible to detect the deviation width d between the teaching welding line 200 and the actual welding line 100 at .

For this reason, the apparatus of the embodiment includes a position detection circuit 62 that detects the actual position of the welding line 100 at the teaching point based on the arc current 1 (t) during this 1-position deviation detection 7-way scanning, and a position detection circuit 62 that detects the actual position of the welding line 100 at the teaching point. a deviation width detection circuit 64 that detects the deviation width d between the teaching point at the teaching point by calculating the difference between the position of the actual welding line 100 detected by the method and the position of the teaching welding line 200 set in advance. .

Here, the position detection circuit 62 includes a current detection circuit 66, a gate circuit 68 . Integrating circuit 70° delay memory 72
．． It consists of a subtracter 741, a discrimination circuit 76, and a gate circuit 80.

Then, the welding pulse current 1 (
The clay of d) is detected and the detection signal is inputted to the integrating circuit 70 via the gate circuit 68. Here, the gate circuit 68 receives the positional deviation detection command pulse Y and the welding power source 18.
Current signal 1 (
d) is sampled and supplied to the integrating circuit 70 as a sampling current I n (I).

The integration circuit 70 integrates the sampling current I n(f) thus inputted at the time interval of the welding pulse period, and inputs the integrated value I nl+) as it is to the subtractor 74 and also inputs it via the delay memory 72. The signal is input to the subtracter 74 with a delay of one welding pulse. Therefore, the subtracter 74 subtracts the current sampling current In(o) and the previous revolving current In-n-1() each time the welding pulse period 1 word C is output, and the difference current r (h
) is input to the discrimination circuit 76.

The determination circuit 76 sets a predetermined threshold level in advance, determines the point in time when the input difference current 1 (h) exceeds this threshold level as the installation position of the workpiece 20b, and sends the determination signal i to the gate circuit 80. supply to. The gate circuit 8o receives the output signal of the feedback circuit 50 at the time of outputting the judgment signal i, that is, the workpiece 20b.
, and supplies the sampled signal k to the deviation width detection circuit 64.

In the embodiment, the deviation width detection circuit 64 includes the deviation width calculation circuit 82 . The workpiece 20 consists of a memory 84 and a switch 86, and is supplied from the gate circuit 80 as described above.
The position signal Q of the teaching welding run 200 at a predetermined teaching point outputted from the welding line output circuit 40 is input to the deviation width calculation circuit 82.

The deviation width calculation circuit 82 calculates the difference Q between each signal input in this way, calculates the deviation width d between the actual welding line 100 and the teaching welding line 200 at a predetermined teaching point, and calculates the deviation width d between the actual welding line 100 and the teaching welding line 200 at a predetermined teaching point. The calculation result is input to the memory 84 via a switch 86 that is turned on only during the output time t of the positional deviation detection command pulse Y.

The memory 84 has its stored contents reset in advance by the point detection signal W output from the delay circuit 54h, and writes and stores the shift width d calculated and output from the shift width calculation circuit 82 as described above. .

In this manner, the apparatus of the embodiment is able to perform arc welding along the teaching welding line 200 with each teaching welding point ml.

Every time m2, m3, etc. are reached, the output of the positional deviation detection command pulse Y causes the third
The positional deviation detection arc scan shown in the figure is performed to detect the deviation width d of the teaching welding line 200 from the actual welding line 100 at the teaching point.

When such a series of positional deviation detection operations are completed, the positional deviation detection command pulse Y is turned off, and at the same time, the selection switch 60 is switched to select the signal output from the welding line output circuit 40, and the teaching is performed. Arc welding along weld line 200 is resumed. In the device of the embodiment, in order to correct the teaching welding line 200 to match the actual welding line 100 based on the detection deviation width d, the contact portion is turned on when the positional deviation detection command pulse Y is turned off. switch 88 and an adder 90 that is provided at the input stage of the position control system 42 and adds the output of the welding line output circuit 40 inputted via the switch 60 and the output d of the memory 84 inputted via the switch 88; and are provided.

Therefore, in the device of the embodiment, when the positional deviation detection command pulse Y is turned off, the selection switch 60 selects the welding line output circuit 40 in synchronization with this, and the switch 88 is turned on, and as a result, the position control system The detected deviation width d output from the memory 40 is added to the teaching welding line signal output from the welding line output circuit 40, and a signal corrected to match the teaching welding line 200 with the actual welding line 100 is supplied to 42. will be done.

In this way, according to the apparatus of the embodiment, when a predetermined deviation width d is detected at each teaching point m, m2, m3, etc., the teaching welding line 200 is actually adjusted based on the deviation width d. The workpieces 20a and 20b can be reliably arc welded along the actual welding line 100 based on the corrected No. 13.

Other Embodiments Also, in the embodiment, the positional deviation detection arc scanning for detecting the positional deviation between the teaching welding line 200 and the actual welding line 100 at each teaching point m+, m2, m, . As shown in FIG. 3, the case where arc scanning is performed along the detection line SE has been described as an example, but the present invention is not limited to this, and it is also possible to perform other detection operations. For example, it is possible to perform general weaving welding at the teaching point, and it is also possible to perform follow-up weaving welding, which will be described later.

In other words, as such a positional deviation detection arc scan,
When performing normal weaving welding, welding wire 1
6 is alternately photographed at a predetermined amplitude in a direction perpendicular to the welding line 200 (weaving), and the workpiece 20a is sewn along the welding line 200.

20b is welded. Then, the positional shift of the workpiece is detected from the phase shift of the welding voltage and welding current during this weaving, and the shift width between the teaching welding line 200 and the actual welding line 100 can be detected based on this detected data.

According to this normal weaving welding, the heat generated per unit distance is extremely large, so if the thickness of the workpiece is extremely thin, there is a problem that the generated heat will melt the workpiece to the back side. be.

Therefore, as the positional deviation detection arc scan, it is also possible to perform follow-up weaving welding, which improves the drawbacks of such normal weaving welding.

Figure 7 shows this type of weaving welding at 117.
It is shown that misfit detection is performed as an arc scan.
The welding wire 16 is reciprocated in a direction parallel to the surface of one of the positioned workpieces 20a and intersecting the teaching welding line 200, and the reciprocating scanning is performed in accordance with the arrows ■■■■.
..., the drive weaving welding is performed repeatedly from one workpiece 20a side to the other workpiece 20t) side in order to approach the workpiece side.

Then, it is possible to detect the deviation width between the teaching welding line 200 and the actual welding line 100 based on the change in the arc that occurs during this follow-up weaving welding.

Therefore, by employing such follow-up weaving as the positional deviation detection arc scanning of the present invention,
Even if one workpiece 20b lfi is a thick plate, the follow-up welding is performed on the workpiece 20a on the thick plate side.
If the arc heat is applied from the side toward the thin plate side 20b, the effect of the arc heat on the thin plate side 20b can be reduced, and the problem of the thin plate work 20b melting to its back surface due to the generated heat can be solved.

[Effects of the Invention] As explained above, according to the present invention, a plurality of positional deviation detection points are set on the teaching welding line and positional deviation detection arc scanning is performed. By arbitrarily setting it at a location where it is expected to occur, it becomes possible to reliably detect positional deviation and reliably arc weld the workpiece along the actual welding line. Moreover, according to the present invention, since the positional deviation detection arc scanning is performed only at each teaching point, the time delay in arc welding that occurs due to positional deviation detection is suppressed to a minimum, and the arc welding of the workpiece can be performed at high speed. It is possible to do this at high speed.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a preferred embodiment of the automatic arc welding method according to the present invention, Fig. 2 is an explanatory diagram of an automatic arc welding device used in the method of the present invention, and Fig. 3 is an explanatory diagram showing a preferred embodiment of the automatic arc welding method according to the present invention. An explanatory diagram showing a preferred embodiment of the positional deviation detection arc scan used for execution, FIG. 4 is a current waveform diagram of the positional deviation detection arc scan shown in FIG. 3, and FIG. 5 is a diagram to which the method of the present invention is applied. A circuit block diagram showing a specific example of an automatic arc welding device, FIG.
FIG. 7 is an explanatory diagram showing another embodiment of positional deviation detection 7-based scanning used in the present invention. 16... Welding wire, 20a, 20b... Workpiece, 100... Actual welding line, 200...
・Teaching welding line.

Claims (4)

[Claims] (1) In an automatic arc welding method in which a welding wire is moved along a predetermined teaching welding line programmed in advance to perform arc welding on a workpiece, a plurality of positional deviation detection teaching points are set in advance at desired positions on the teaching welding line. Then, at each teaching point, a predetermined positional deviation detection arc scan is performed to detect the deviation width between the actual welding line of the workpiece and the teaching welding line, and teaching welding is performed based on the detected deviation width in the area up to the next teaching point. An automatic arc welding method characterized in that a line is corrected to match an actual welding line and a workpiece is arc welded along the corrected teaching welding line. (2) In the method described in claim (1), arc scanning is performed along a detection line that intersects the teaching welding line as the positional deviation detection arc scanning, and the teaching welding line is detected based on the change in the arc that occurs at this time. An automatic arc welding method characterized by detecting the deviation width between the actual welding line and the actual welding line. (3) In the method described in claim (1), weaving welding that intersects the teaching welding line is performed as positional deviation detection arc scanning, and the teaching welding line is detected based on the phase shift of the arc voltage and arc current that occurs at this time. An automatic arc welding method characterized by detecting the deviation width between the actual welding line and the actual welding line. (4) In the method described in claim (1), reciprocating scanning of the welding wire in a direction parallel to one workpiece surface and intersecting the teaching welding line is performed on one workpiece side as the positional deviation detection arc scan. The automatic welding method is characterized in that it performs follow-up welding repeatedly so as to approach the other workpiece side in sequence, and detects the deviation width between the teaching welding line and the actual welding line based on changes in the arc generated during this weaving welding. Arc welding method.