JPS64156B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for detecting positional deviation in automatic arc welding, particularly an improved method for detecting positional deviation between a preset teaching welding line and an actual welding line. Regarding.

[Prior art and problems to be solved by the invention]

Conventionally, an automatic arm 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., and this welding method moves a torch along a set teaching welding line. Since it is possible to automatically weld workpieces, it is widely used, for example, in repeat welding in automobile welding processes and other mass production lines.

By the way, when performing arc welding along such a teaching welding line, if there is a positional shift between the actual welding line of the workpiece to be welded and the teaching welding line, the welding itself to the workpiece may become misaligned. , welding defects such as poor welding occur.

Therefore, in such automatic arc welding, it is necessary to accurately detect whether the workpiece is accurately positioned along the teaching welding line prior to welding, and to change the welding conditions or welding based on the detection results. It will be necessary to cancel the event.

Further, in the automatic arc welding process, after arc welding is completed, a product inspection is performed to determine whether the product is acceptable or not.

Such product inspection is performed by detecting positional deviations to determine whether the workpiece is accurately welded along a predetermined teaching welding line.

Conventionally, as a method for detecting the positional deviation between the teaching welding line and the actual installation position of the workpiece, a method using, for example, a laser beam, a television camera, etc. is well known. By scanning a laser beam or pattern recognition of an image obtained by a television camera, it is possible to detect the positional deviation of the workpiece with respect to the teaching welding line online.

Therefore, using such a positional deviation detection method,
Prior to arc welding, the positional deviation of the workpiece installation position with respect to the teaching welding line is detected, and the positional deviation of the workpiece with respect to the teaching welding line is corrected based on the detected deviation width,
Furthermore, it is possible to change the welding conditions and, if the positional deviation exceeds a predetermined limit, take appropriate measures such as stopping arc welding.

Moreover, by using such a positional deviation detection method, it becomes possible to quickly and accurately perform online product inspection after completion of arc welding.

However, on the other hand, with this conventional method, in addition to the original arc welding equipment, it is necessary to install a special positional deviation detection device such as a laser beam transmitter/receiver or a television camera, which increases the number of parts of the arc welding equipment. However, the disadvantage was that the entire device was expensive.

Furthermore, in such conventional methods, it is necessary to install the positional deviation detection device near the welding torch where the welding wire is installed, so that these detection devices can detect strong light peculiar to the arc generated during arc welding, They have the disadvantage that they are susceptible to measurement errors due to exposure to high heat and metal-containing fumes, and moreover, the lifespan of these detection and correction devices is extremely short.

In addition to this conventional method, there is also a well-known method of physically detecting the positional shift of a workpiece using a welding wire. This method scans the welding wire in a direction perpendicular to the welding line and Misalignment of the workpiece is detected through physical contact between the wire and the workpiece.

Therefore, according to this method, the laser beam,
Compared to a method using a television camera, this method does not require special equipment such as a laser beam transmitter/receiver or a television camera, so the entire device can be made inexpensive.

However, on the other hand, according to this conventional method, the welding wire used for arc welding is extremely thin.
The welding wire must be scanned slowly to prevent physical deformation of the welding wire when it comes into contact with the workpiece, and therefore the workpiece installation position cannot be detected quickly. It was hot.

Furthermore, according to this method, it is necessary to always accurately set the distance between the tip of the welding wire and its scanning surface, and if the workpiece to be detected for positional deviation is extremely thin, the welding wire There is a drawback that the tip scans the surface of the detection workpiece without coming into contact with the detection workpiece, making it impossible to detect the position of the workpiece.

[Purpose of the invention]

The present invention has been made in view of such conventional problems, and its purpose is to detect positional deviations in automatic arc welding that can accurately detect positional deviations of the arc without using any special equipment. The object of the present invention is to provide a detection method.

[Means for solving problems]

In order to achieve the above object, the method of the present invention provides a consumable electrode type automatic arc welding method in which a welding wire is moved along a preset teaching welding line to perform arc welding on a workpiece. a positional deviation detection arc scanning step of scanning an arc along a detection line intersecting the teaching welding line at a selected arbitrary point, and detecting and measuring changes in arc current during the positional deviation detection arc scanning; A step of calculating the actual welding line based on the start point of a sudden change in arc current due to the shape of the workpiece at the welded part, and a process of calculating the actual welding line based on the detected position information of the actual welding line and teaching that is set and stored in advance. The process of comparing the position information of the welding line and calculating the deviation width between the two, and if the calculated deviation width of the welding line is less than a predetermined tolerance value, the teaching line is made to match the actual welding line. The method is characterized in that it includes a step of correcting the deviation width and stopping the welding operation if the deviation width exceeds a predetermined tolerance range.

[Effect]

The present invention detects the positional deviation of the workpiece at any point by performing positional deviation detection arc scanning along a detection line set to intersect the teaching welding line at any point where the positional deviation of the workpiece is to be detected. Can be detected accurately.

Therefore, by performing the positional deviation detection according to the present invention prior to arc welding the workpiece, it is possible to correct the teaching welding line, change the welding conditions, or in the worst case, correct the welding condition based on the detected deviation width. This makes it possible to prevent welding defects on the workpiece.

Furthermore, by performing the positional deviation detection according to the present invention after arc welding the work, it is possible to automatically and reliably perform a product inspection to determine whether or not the work has been accurately arc welded along the desired teaching welding line. becomes possible.

In particular, according to the present invention, the positional shift of the workpiece can be detected simply by scanning the welding wire without using any special equipment, so the entire device can be made simple and inexpensive. In addition, it is possible to accurately detect the positional shift of the workpiece regardless of the strong light, high temperature, or fume containing metal that is unique to the arc that occurs during arc welding.
Furthermore, the durability and reliability of the entire device can be improved.

In addition, the method of the present invention enables positional deviation detection to be performed more quickly and reliably than the conventional physical positional deviation detection method using a welding wire.

〔Example〕

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

Automatic arc welding device of the first embodiment Fig. 2 shows the automatic arc welding device used in this embodiment.
A torch 12 into which a welding wire 10 is fed from the tip
The torch 12 is attached to the arm 16 of the welding robot 14 and moves three-dimensionally to weld the workpiece 18.
Performing arc welding.

In this arc welding, the workpiece 18 is positioned along a predetermined welding wire using a jig 20, and then a predetermined welding voltage is applied between the workpiece 18 and the welding wire 10 from the welding power source 22,
The welding is performed by moving the welding wire 10 together with the torch 12 along a predetermined welding line.

When arc welding is performed in this manner, the tip of the welding wire 10 is gradually consumed, so it is necessary to sequentially replenish the welding wire 10 with a length corresponding to the amount of wear. Therefore, in the device of the embodiment,
A predetermined amount of welding wire 20 is wound around the drum 24 in advance, and the welding wire 10 wound in this manner is sequentially and continuously fed by a wire feeding motor 26 according to the amount of wear.

Furthermore, in the apparatus of this embodiment, the shielding gas sealed in the gas shielding cylinder 28 is blown out toward the tip of the welding wire 10 via the torch 12, thereby making it possible to weld the workpiece 12 well. .

Further, in the apparatus of this embodiment, the welding line of the workpiece 18 is taught in advance in the memory in the robot control panel 30 prior to the arc welding. The robot control panel 30 controls the welding robot 14 and the like to weld the work 18 along the teaching welding line every time the work 18 is installed by the jig 20.

Therefore, according to this device, it is possible to accurately weld workpieces 18, such as automobile parts that are sequentially transported, along the teaching welding line.

Principle of the Invention FIG. 1 shows the positional deviation detection method of the present invention, which is carried out using such an automatic arc welding device. The workpiece 18b indicated by a solid line in the figure is shown when the workpiece 18b is accurately positioned along a predetermined teaching welding line AB, and the workpiece 18b indicated by a chain line in the figure is
In b, workpiece 18b is on the teaching welding line.
A case is shown in which the positions are uniformly shifted with respect to AB with a predetermined shift width d.

A characteristic feature of the present invention is that arc scanning for detecting positional deviation is performed by scanning an arc along a detection line SE that intersects the teaching welding line AB, and the teaching welding line is detected based on the arc current or arc voltage change that occurs at this time. Work AB 18b
The purpose is to detect the deviation width d from the installation position.

That is, when the arc scanning for positional deviation detection is performed, changes in the arc voltage and arc current occur at the installation position of the workpiece 18b, and based on such changes in the arc current or arc voltage, the workpiece 1
8b can be detected. In the embodiment, the workpiece 1 is
8b is detected.

Further, in the embodiment, this arc scanning for positional deviation detection is performed along a detection line SE that is orthogonal to the teaching welding line AB at an arbitrary point N.

The arc scanning direction may be from S to E or may be from E to S. In the embodiment, the workpiece is scanned from S to E, and at this time, the positional deviation of the workpiece 18b is caused by S with respect to the teaching welding line AB.
If it is expected to occur only on the point side,
It is sufficient to perform arc scanning for detecting positional deviation from point S to point N, and if positional deviation of the workpiece 18b is expected to occur on the side of point S of teaching welding line AB, it is sufficient to perform arc scanning from point S to point E. It is sufficient to set the positional deviation detection arc scan to the point.

Here, the scanning distance of the arc scan for positional deviation detection can be arbitrarily set depending on the type of workpiece 18b and the deviation width d that is expected to occur, and in the embodiment, it is The total distance to point S and point E is about 3 to 5, respectively.
It is set to mm.

FIG. 3 shows the arc scanning for positional deviation detection of the present invention performed in this way, and the fourth
The figure shows the arc current waveform at this time.

First, arc scanning for positional deviation detection is performed from S to E. At this time, if the workpiece 18b is accurately positioned with respect to the teaching welding line AB, the scanning line is S→N→C→E.
However, if the workpiece 18b is positioned with a predetermined deviation width d from the teaching welding line AB, the scanning line changes from S→
It changes as N′→C′→E.

At this time, the change in arc current in the scanning line S→N'→C'→E is as shown in Figure 4.
It is constant in the N' interval, sharply increases in the N'→C' interval, and becomes constant again in the C'→E interval.

This is because when arc scanning is performed in the N'→C' section, the tip of the welding wire 10 is consumed along N'C' and the length of the welding wire 10 is shortened, and as a result, the arc current circuit This is caused by a decrease in resistance value.

In other words, when arc scanning the S→N' section, the feed amount of the welding wire 10 is balanced with the consumption amount and the length is almost constant, but when arc scanning the N'C' section, , the amount of consumption of the welding wire 10 greatly exceeds the feed rate and its length decreases rapidly, and when arc welding the section C'→E, the feed rate and the amount of consumption of the welding wire 10 are not balanced. It becomes a constant value as the length decreases. Therefore, the resistance value in the arc current circuit is constant in the S→N' section, rapidly decreases in the N'→C' section, and becomes constant after decreasing again in the C'→E section.

As a result, when performing arc scanning for positional deviation detection from point S to point E, the arc current increases rapidly in the N'C' section as shown in Figure 4, so this arc current starts to increase. By detecting the time, it is possible to detect the set position of the work 18b with respect to the work 18a, that is, the actual welding line A'B' of the works 18a, 18b.

Then, the workpiece 18 detected in this way
By comparing the actual welding lines A'B' of a and 18b with the teaching welding line AB stored in advance, the deviation width d between the two can be determined.

As explained above, according to the method of the present invention,
It becomes possible to accurately detect the deviation width d of the workpiece 18b from the teaching welding line AB at any point N by simply performing arc scanning for positional deviation detection.

Therefore, by performing the positional deviation detection according to the present invention prior to arc welding the workpieces 18a and 18b, it is possible to detect the deviation width d between the workpiece setting position A'B' and the teaching welding line AB. Based on the detected deviation width d, the welding conditions of the workpieces 18a and 18b are changed, or the teaching welding line AB is corrected to match the actual welding line A'B' based on the detected deviation width d,
It is also possible to start arc welding. Further, if the deviation width d detected in this manner exceeds a predetermined range, welding of the works 18a and 18b can be interrupted.

In this way, by performing the positional deviation detection according to the present invention, it is possible to prevent the occurrence of welding defects due to the positional deviation of the workpiece 18b, and to perform reliable arc welding of the workpieces 18a and 18b. .

Furthermore, by using the positional deviation detection according to the present invention for product inspection after completion of arc welding, it is possible to automatically determine whether or not the workpiece after welding has been accurately arc welded along a predetermined teaching welding line. This makes it possible to quickly perform an online product inspection of a workpiece after welding in automatic arc welding and make a pass/fail judgment.

According to the present invention, when detecting the positional deviation as described above, the workpiece 1 is detected simply based on the change in the arc without using any special detection device.
Since the deviation width d from the teaching welding line AB of 8b can be detected, it is possible to detect the deviation width d from the teaching welding line AB of 8b.
The reliability and durability of the detection device will not be lowered due to heat generated during arc welding, and detection errors will not occur, and the structure of the entire device can be made simple and inexpensive.

Further, according to the present invention, as shown in FIG.
When performing arc scanning for positional deviation detection from point to point E, the tip of the welding wire 10 is sequentially melted by arc generation, and the surface of each workpiece 18a, 18b,
In particular, there is no collision with the end face NC or N'C' of the workpiece 18b. Therefore, according to the present invention, the arc scanning for detecting positional deviation from point S to point E can be performed by ±5, for example.
If the accuracy level is mm, it can be performed at a high speed of 1 to 2 seconds, making it possible to quickly detect positional deviations on the teaching welding line. Further, as a result, the amount of heat generated per unit distance is reduced, so that even a positional shift of the thin plate work 18b of 2 mm or less can be accurately detected without damaging the work 18b.

In addition, in the present invention, since the distance of the detection line SE of the arc scan for positional deviation detection can be set arbitrarily, it is possible to reliably detect large deviation widths of 2 to 3 mm or more, and the detection capability is high. It becomes possible to demonstrate.

In addition, in the present invention, it is sufficient that the arc current used when performing arc scanning for positional deviation detection has a value that can obtain the current change shown in FIG.
It is set to about.

Second Embodiment In addition, in the above embodiment, when performing arc scanning for positional deviation detection, the current change is detected in an analog manner to detect the deviation width d of the workpiece 18b. The invention is not limited to this, but it is also possible to digitally detect the deviation width d of the workpiece 18b by sampling such an arc current.

FIG. 5 shows a method of detecting the deviation width d of the workpiece 18b by sampling the arc current, and according to the method of the embodiment,
Pulse welding for positional deviation detection is performed along the positional deviation detection line SE as shown in FIG. 5a.

Then, in synchronization with each pulse of this pulse welding, each pulsed arc current is sampled, and each sampling current In (n is an integer) is integrated over one pulse period as shown in Figure 5b, and the current corresponding to the pulsed arc current is Find the value ∫Indt.

The current values obtained in this way ∫I ₁ dt, ∫I ₂ dt,...
shows the same current change as shown in FIG. 4, and therefore, by detecting the change in the current value obtained in this way, the deviation width d of the workpiece 18b can be detected.

In other words, when arc-scanning the SA' section or C'E section of the detection line SE, the value of the sampling current is as follows: ∫ (I _o − I _o-1 ) dt≦O (1) , when the A′C′ section of the detection line SE is being arc scanned, the welding current changes suddenly and shows the current change as shown in the following equation.

∫(I _o −I _o-1 ) dt>O (2) Therefore, in this embodiment, the sampling currents I ₁ , I ₂ , etc. detected in this way are
When the current change shown in the equation is shown, this is determined to be the installation position of the workpiece 18b, and the deviation width d is detected.

In addition, in the first and second embodiments, the teaching welding line AB is determined based on the change in arc current that occurs when performing arc scanning for detecting positional deviation.
The explanation has been given using an example of detecting the deviation width between the actual welding line A′B′, but the present invention is not limited to kneading. It is also possible to detect.

Embodiment of an apparatus using the method of the present invention FIG. 6 shows a preferred embodiment of an automatic arc welding apparatus for detecting positional deviation according to the present invention, and FIG. 7 shows its operation. A timing diagram is shown.

The apparatus of the embodiment includes a welding line output circuit 32 in which a teaching welding line is set in advance, and from this welding line output circuit 32, for example, a position signal of the teaching welding line AB shown in FIG. 1 is directed to a position control system 34. Supplied.

This position control system 34 includes an actuator 40 to which a supplied signal is input via a subtracter 36 and an amplifier 38, and the actuator 40 controls the position of the welding torch 12 based on the input signal. Here, the output of the actuator 40 is fed to the subtracter 36 via a feedback circuit 42.
Therefore, the actuator 40 adjusts the output signal of the subtractor 36 to O, that is, the position signal output from the welding line output circuit 32 and the position of the welding torch 12 controlled by the actuator 40. The position of the welding torch 12 is controlled so that the values match.

Therefore, in the apparatus of the embodiment, the welding torch 12 is controlled to move along the signal output from the welding line output circuit 32, that is, along the teaching welding line AB.

Although a plurality of such position control systems 34 for the welding torch 12 are usually provided in a welding robot, in the embodiment, for the sake of simplicity,
Only one of them is illustrated and explained.

Also, such teaching welding line AB
Simultaneously with the start of controlling the movement of the torch 12 along the welding wire 10, the welding power source 22 applies a predetermined welding voltage between the welding wire 10 and the workpiece 18, and generates an arc between the welding wire 10 and the teaching welding line.

Therefore, the works 18a and 18b are reliably arc welded along the teaching welding line AB shown in FIG.

By the way, as mentioned above, simply performing arc welding along such teaching welding line AB does not ensure that when the workpiece 18b is positioned with a predetermined deviation width d from the teaching welding line AB. There is a problem that arc welding cannot be applied to

The characteristic feature of this embodiment is that the deviation width d of the workpiece 18b positioned on the workpiece 18a with respect to the teaching welding line AB is detected in advance, and based on the deviation width d, the teaching welding line AB is adjusted to the actual welding of the workpieces 18a and 18b. The reason is that a positional deviation correction circuit 44 is provided for correcting the line A'B' to coincide with the line A'B'.

In the embodiment, this positional deviation correction circuit 44
is the detection line output circuit 4 in which the detection line SE of the arc scan for positional deviation detection described above is set in advance.
6, a position detection circuit 48 that detects the installation position of the workpiece 18b based on arc scanning for positional deviation detection along this detection line SE, and a position detection circuit 48 that detects the installation position of the workpiece 18b and the teaching welding line AB.
a deviation width detection circuit 50 that calculates a deviation width d between the
including.

An adder 52 is provided at the input stage of the position control system 34 to add the position information of the welding line AB outputted from the welding line output circuit 32 and the deviation width d outputted from the deviation width detection circuit 50. The teaching welding line AB output from the line output circuit 32 is corrected to match the actual welding line A'B' of the workpieces 18a and 18b, and arc welding is performed based on this corrected welding line A'B'. This makes it possible.

In the apparatus of the embodiment, a selection switch 54 selectively inputs the output of the welding line output circuit 32 and the output of the detection line output circuit 46 to the adder 52, and a selection switch 54 inputs the output of the welding line output circuit 32 and the output of the detection line output circuit 46 to the adder 52, and a switch 56 that turns on and off the supplied signal;
is provided, and performs a predetermined switching operation based on a signal from a correction command section 58, which will be described later.

Next, a detailed configuration of the deviation correction circuit 44 of the embodiment will be explained.

(1) Start of arc scanning for positional deviation detection First, when the positional deviation detection command signal b is output from the correction command section 58, the switch 56 is turned off, and the selection switch 54 is turned off to the detection line output circuit 46 side. Change.

As a result, a signal representing the detection line SE of the arc scan for positional deviation detection is supplied from the detection line output circuit 46 to the position control system 34, and the torch 12 starts moving along the detection line SE. Also,
At the same time that the positional deviation detection command signal b is output, the welding power source 22 is also driven, and pulse welding of the workpiece 18 is started.

In this manner, according to the apparatus of the embodiment, arc scanning for positional deviation detection along the predetermined detection line SE is started simultaneously with the output of the positional deviation detection command b.

(2) Calculation of deviation width When the arc scanning for positional deviation detection is started in this way, the position of the workpiece 18b placed on the workpiece 18a is detected based on the change in the arc current I(d) flowing at this time. can do.

Therefore, in the device of the embodiment, the current detection circuit 60
The value of the welding pulse current I(d) is detected and the detected signal is supplied to the position detection circuit 48.

The position detection circuit 48 is driven by a welding pulse periodic signal c output from the welding power source 22 in synchronization with the welding pulse current I(d), and receives the current signal I(d) supplied from the current detection circuit 60 through a gate circuit. 62, and this sampling current In(f) is supplied to an integrating circuit 64.

The integrating circuit 64 integrates the sampling current In(f) thus inputted at the time interval of the welding pulse period, inputs the integrated value In(g) as it is to the subtracter 68, and also inputs the integrated value In(g) via the delay memory 66. The signal is input to the subtracter 68 with a delay of one welding pulse.

Therefore, the subtracter 68 converts the welding pulse period signal c
The current sampling current In(g)
and the sampling current In- ₁ (g), and the difference current I(h) is input to the discrimination circuit 70.

The determination circuit 70 has a predetermined threshold level set in advance, determines the point in time when the input difference current I(h) exceeds this threshold level as the set position of the workpiece 18b, and issues a determination signal. i is supplied to the gate circuit 72. The gate circuit 72 provides feedback to the feedback circuit 42 when this judgment signal i is output.
The output signal k, that is, the installation position of the workpiece 18b is sampled, and the sampling signal k is supplied to the deviation width detection circuit 50.

The deviation width detection circuit 50 inputs the position signal k of the workpiece 18b supplied from the gate circuit 72 and the position signal l of the teaching welding line output from the welding line output circuit 32 to the deviation width calculation circuit 74 as described above. are doing.

This deviation width calculation circuit 72 calculates the difference between the signals k and l inputted in this way, and calculates the difference between the workpiece 18b and the teaching welding line at an arbitrary point N.
Calculate the deviation width d from AB. The deviation width d calculated in this manner is input to the pass/fail determination circuit 76.

Further, a reference level q representing the allowable deviation width limit of the workpiece 18b is inputted to the pass/fail determination circuit 76 from a reference level setter 78.

In this way, the pass/fail judgment circuit 72 calculates the reference level q inputted from the reference level setter 78 and the absolute value of the deviation width inputted from the deviation width calculation circuit 74 |d
｜Compare with.

If |d|>q, the pass/fail determination circuit 76 determines that the workpiece 18 is a rejected product whose deviation width exceeds the allowable range, and outputs a rejection signal r to a control circuit (not shown). . When the rejection signal r is output in this way, the welding robot stops its operation or returns each part of the robot to its original position to stop arc welding, and at the same time, a message indicating that the workpiece 18b is a rejected product is sent. Outputs a warning.

Further, in the case of |d|≦q, the pass/fail judgment circuit 7
6 determines that the workpiece 18 is an acceptable product, and writes and stores the deviation width d outputted from the deviation width calculation circuit 74 into the memory 82 via the switch 80.

In the embodiment, the switch 80 is turned on only when arc scanning for signal deviation detection is being performed.

In addition, in the apparatus of this embodiment, the deviation width d of the workpiece 18b calculated by the deviation width calculation circuit 74 is
An external terminal 84 is provided to which the deviation width d of the workpiece 18b is output, and each time the deviation width d of the workpiece 18b is outputted from this external terminal 84, it is stored in an external storage device to manage the deviation width of the workpiece 18b that occurs. It becomes possible to store data sequentially.

(3) Start of arc welding When the series of positional deviation detection operations are completed in this way, the positional deviation detection command b output from the correction command section 58 is turned off, and then the workpiece 18a along the teaching welding line, Arc welding of 18b is started.

That is, when the positional deviation detection command b output from the correction command unit 58 is turned off, the switch 54 selects the output of the welding line output circuit 32 and supplies it to the adder 52 in synchronization with this, and also is turned off, the switch 56 is turned on, and the deviation width d stored in the memory 82 is input to the adder 52.

Therefore, in the adder 52, the teaching welding line output from the welding line output circuit 32
The AB position signal and the deviation width d output from the memory 82 are added, and the teaching welding line AB
is corrected to match the actual welding line A'B' of the workpiece 18b and is supplied to the position control system 34.

Therefore, according to the apparatus of the embodiment, the work 18a,
18b can be welded, and the workpieces 18a, 1 can be welded regardless of whether or not the workpiece 18b is misaligned.
It becomes possible to perform the arc welding of 8b reliably.

Note that in the apparatus of this embodiment, the workpiece 18
Although the case where the detection of the deviation width d of b is performed before arc welding of the workpieces 18a and 18 is started has been described as an example, this embodiment is not limited to this. It is also possible to detect the deviation width d between the arc welding position A'B' and the teaching welding line AB.

〔Effect of the invention〕

As explained above, according to the present invention, in automatic arc welding in which a welding wire is moved along a preset teaching welding line to perform arc welding on a workpiece, teaching welding can be performed without using any special equipment. It becomes possible to accurately and quickly detect the deviation width from the line.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a preferred embodiment of the positional deviation detection method in automatic arc welding according to the present invention,
Fig. 2 is an explanatory diagram of the arc welding device used in this embodiment, Fig. 3 is an explanatory diagram of the operation of arc scanning for detecting positional deviation along the detection line shown in Fig. 1, and Fig. 4 is an explanatory diagram of the arc welding device used in this embodiment.
The figure is a current characteristic diagram showing the arc current at each part of the detection line shown in Figure 3, Figure 5 is a current characteristic diagram when pulse welding is performed, and Figure 6 is a positional deviation detection circuit to which the method of the present invention is applied. FIG. 7 is a timing chart showing the operation of the circuit shown in FIG. 6. AB...Teaching welding line, SE...Detection line, 10...Welding wire, 18a, 18b...
…work.

Claims (1)

[Claims] 1. In a consumable electrode automatic arc welding method in which a welding wire is moved along a preset teaching welding line to perform arc welding on a workpiece, an arbitrary point selected in advance on the teaching welding line is provided. a positional deviation detection arc scanning step in which an arc is scanned along a detection line intersecting the teaching welding line, and a change in arc current during the positional deviation detection arc scanning is detected and measured, A process of calculating the actual welding line based on the start point of a rapid change in arc current due to the shape of the workpiece, and calculating the positional information of the detected actual welding line and the positional information of the teaching welding line that is set and stored in advance. and calculating the deviation width between the two, and if the calculated deviation width of the welding line is less than a predetermined tolerance value, correcting the teaching line to match the actual welding line, A method for detecting positional deviation in automatic arc welding, comprising the step of controlling a welding operation to stop if the deviation exceeds a predetermined tolerance range.