JPS61206571A - Method and device for abnormality detection of welding line automatic correction mechanism - Google Patents

Abstract

PURPOSE:To detect surely an abnormality and to prevent the generation of the welding defect of a work in advance by outputting an abnormality detection signal in case of the integral value of the corrected movement of a welding position becoming more than the prescribed value. CONSTITUTION:The correction signal I10 outputted from a correction quantity generator 64 as being necessary for correction due to the slippage width being larger than the allowable value is inputted in an integrator 70 by a welding line automatic correction mechanism 46. The integrator 70 calculates the integrated correction movement quantity of the arc welding position by integrating the correction signal I10. The integral value I11 of the integrator 70 is outputted to discriminating circuit 74 and the preset threshold level and the output I11 of the integrator 70 are compared by a correction boundary setter 72 in the discriminating circuit 74. An abnormality signal is then outputted in case of the discriminating circuit 74 discriminating that integrated correction movement quantity > shreshold level.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method and device for detecting abnormalities in an automatic welding line correction mechanism;
In particular, the present invention relates to an abnormality detection method and apparatus for automatic arc welding that performs a welding position deviation correction operation.

[Prior Art] In recent years, automatic arc welding has been widely practiced in order to save labor and improve the efficiency of welding operations, and is widely used, for example, in automobile welding processes and repetitive welding in other mass production lines.

As such an automatic arc welding method, for example, a method in which a predetermined welding line is taught to a computer in advance using a teaching playback method is well known. According to this welding method, the torch is moved along the set teaching welding line. It can move and automatically perform arc welding on workpieces.

FIG. 9 shows an example of such an automatic arc welding device. It is attached to an arm 16 and moves three-dimensionally to perform arc welding on a workpiece 18.

That is, the workpiece 18 is positioned along a predetermined welding line using a jig (not shown), and a welding power source 2 is connected between the workpiece 18 and the welding wire 10.
2, a predetermined welding voltage is applied, and the welding wire 10 is moved together with the torch 12 along a predetermined welding line.

Here, since the tip of the welding wire 10 is consumed as welding progresses, it is necessary to sequentially replenish the welding wire 10 with a length corresponding to the amount of wear.

For this reason, in the illustrated device, the welding wire 10 is wound around a predetermined base drum 24 in advance, and the wound wire is sequentially and continuously wound by the wire feeding motor 26 according to the wear of the tip of the welding wire 10. will be sent to

Further, in the illustrated apparatus, the shielding gas sealed in the gas shielding cylinder 28 is blown out toward the tip of the welding wire 10 through the torch 12, and the workpiece 1 is
The welding of No. 8 is made better.

Here, the control of the device in this illustrated example is performed by a robot Ill'l
The welding line of the workpiece 18 is previously taught in the memory in the robot control board 30 prior to the arc welding. Then, the robot control board 30 causes the welding robot 14 and the like to weld the workpiece 18 along the teaching welding line every time the workpiece 18 is installed by the jig.

Therefore, according to such an automatic arc welding apparatus, it is possible to accurately weld workpieces 181, such as automobile parts that are sequentially transported, along preset teaching welding lines.

FIG. 10 shows a state in which one basic workpiece 18a and the other workpiece 18b are positioned along a predetermined teaching welding line A-8 using a jig (not shown). By performing arc welding along the teaching welding line A-8 using the automatic arc welding apparatus shown in FIG. 9, one workpiece 18a is reliably arc-welded to the other workpiece 18b.

However, as shown by the two-dot chain line in the figure, when the other workpiece 18b is positioned uniformly shifted by the width d from the teaching welding line A-8 on the basic workpiece 18a, the preset Teaching welding line A-
8 deviates from the planned welding line A ``-8'' of the workpieces, and it becomes impossible to weld both the workpieces 18a and 18b.

For this reason, an automatic welding line correction mechanism has been proposed that detects the positional deviation between the planned welding line and the teaching welding line of the workpiece and automatically corrects the positional deviation.
When performing arc welding of 8a and 18b, the deviation width d between the teaching welding A-8 and the actual planned welding line A"-B of the workpiece is detected. Then, the detected deviation width d is used as the corrected deviation width. used as teaching welding line A-8
is corrected to match the welding schedule of the workpiece, 11/M-8=.

Therefore, according to the illustrated automatic arc welding apparatus, the workpiece 18a is
Even if the teaching welding line A-B is positioned with a predetermined deviation width d, the teaching welding line
--It becomes possible to weld the works 18a and 18b in accordance with B'.

[Problems to be Solved by the Invention] Problems with the Prior Art However, the conventional automatic arc welding welding line automatic correction mechanism simply detects the deviation width between the planned welding line of the workpiece and the teaching welding line. However, it has not been determined whether the deviation width is greater than or equal to the allowable limit for the workpiece to become a product.

For this reason, with conventional welding line automatic correction mechanisms, arc welding is performed with positional deviation correction even on workpieces that have been positioned with a deviation width that exceeds the allowable value limit, resulting in the production of defective products. There was a problem with this.

Further, in the conventional automatic welding line correction mechanism, the positional deviation correction operation of the workpiece is performed without determining whether the hoe mechanism is malfunctioning or malfunctioning. Therefore, if the automatic welding line correction mechanism malfunctions or the device malfunctions due to external noise, especially noise generated due to rapid changes in arc current and arc voltage, the teaching welding line may There is also the problem that the planned welding line is corrected in a completely wrong direction and amount, and welding is performed at a position completely different from the planned welding line of the workpiece, resulting in welding defects.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to detect the positional deviation of the workpiece that exceeds the allowable limit or the malfunction of the automatic welding line correction mechanism itself, and correct the workpiece. An object of the present invention is to provide a method and device for detecting an abnormality in a welding line automatic correction mechanism that can prevent the occurrence of welding defects.

[Means for solving the problem] In order to achieve the above object, the method according to the first invention of the present application detects the deviation width between the planned welding line of the workpiece and the actual welding position, and detects the deviation width if the deviation width is allowable. In the welding line automatic correction mechanism that corrects the movement of the welding position in the direction of the planned welding line of the workpiece when the value exceeds the value, the correction movement amount of the welding position C is integrated.

Then, when the deviation width is within the tolerance value, the integral correction shift of the welding position #llf! i is reset, and when the integral correction movement amount exceeds a predetermined value, an abnormality detection signal is output.

Further, the device according to the second invention of the present application detects the deviation width between the planned welding line and the actual welding position based on changes in the arc of the torch, and corrects the position deviation of automatic arc welding when the deviation width is greater than an allowable value. The welding line automatic correction mechanism that performs this is equipped with an integration circuit that integrates the correction movement amount of the welding position.

The integral circuit is reset when the deviation width between the planned welding line of the workpiece and the actual welding position falls within the allowable value, and when the integral correction movement amount exceeds a preset value. It is characterized in that an abnormality detection signal is output when the determination circuit makes a determination.

[Function] According to the automatic correction mechanism according to the present invention, the welding position is changed to the workpiece when the deviation width between the planned welding line of the workpiece and the actual welding position exceeds the allowable value. Since the movement is corrected in the direction of the planned welding line of the workpiece, the arc welding line will not deviate from the planned welding line of the workpiece by more than the allowable value.

In addition, the correction movement amount of the welding position is integrated, and if the integral correction movement amount exceeds a predetermined value, an abnormality detection signal is output. The welding position will not deviate greatly from the planned welding line of the workpiece, and incorrect correction will not proceed.

Furthermore, although the welding line automatic correction mechanism itself is operating normally, if the installation position of the workpiece to be welded deviates beyond the allowable value, an abnormality detection signal will be output as well, resulting in the production of defective products. This can also be prevented.

Note that the integrated value of the correction movement amount is reset when the deviation width between the planned welding line of the workpiece and the actual welding position falls within the tolerance range, so the deviation between the planned welding line of the workpiece and the actual welding line is is always regulated within certain tolerance values.

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

11 and 1 FIG. 1 is a block diagram showing an example of the abnormality detection method according to the present invention.

In the figure, automatic arc welding starts when the switch of the automatic arc welding device is turned on, for example, when a workpiece is placed in a predetermined position.

At the start of arc welding, the deviation between the planned welding line of the workpiece and the actual welding position is detected (step 100).
.

Then, it is determined whether the deviation width f is 1 or more than the allowable value (step 102), and if the deviation width f is 1 or less than the allowable value, arc welding proceeds according to the predetermined teaching welding line. do.

Here, the torch position at the start of arc welding is at the starting position of the teaching welding line, and the deviation width d between the teaching welding line A-8 and the planned workpiece welding line A--B'' in FIG. This corresponds to the detected deviation width f.Therefore, it is determined at the start of welding whether the deviation width between the teaching welding line and the planned welding line of the workpiece is within the allowable value.

When the initial deviation width f, that is, d in Fig. 10, is within the allowable value, automatic arc welding continues along the teaching planned line, but the deviation width f between the workpiece welding plan line and the actual welding position is within the allowable value. When the value is 1 or more, the welding position of the arc is moved by the unit correction movement amount ΔX in the direction of the planned welding line of the workpiece (step 1o4). This operation is continued as long as the deviation width f is equal to or greater than the allowable value, and the amount of movement of the arc welding position is integrated during this period (step 106). The integral value X of the correction shift @ flat ΔX is the integral value X
Each time the movement amount ΔX is adjusted, a preset threshold level is compared with 2 (step 108);
When the integral value X reaches the threshold level of 2 or more, an abnormality detection signal is generated (step 11o).

Note that if the deviation width f becomes less than or equal to the allowable value by 1 before the integral value X exceeds the threshold level of 2, the integral value X is reset (step 112), and the welding position at that time is reset. Welding progresses in the direction corresponding to the teaching welding line based on the teaching welding line.

As outlined above, according to the abnormality detection method according to the present invention, the abnormality detection operation is performed prior to arc welding of the workpiece, so that the planned welding line of the workpiece with respect to the teaching welding line is If the allowable value is greater than 2, this is reliably detected and arc welding of the workpiece is stopped in advance to prevent the occurrence of defective products due to such positional deviation. becomes possible.

In addition, by continuously performing the above abnormality detection operation during automatic arc welding of the workpiece, it is possible to detect, for example, that the deviation width f between the planned welding line and the actual welding position of the workpiece will reach a threshold due to a failure or malfunction of the correction mechanism itself. Even when the level exceeds level 2, it is possible to reliably detect malfunction of the system and prevent welding defects on the workpiece due to failure or malfunction of the automatic welding line correction mechanism.

Welding wire motion correction structure An automatic welding line correction mechanism to which the present invention is applied will be explained based on FIGS. 2 and 3.

FIG. 2 shows a preferred embodiment of the automatic welding device, and FIG. 3 shows a timing chart showing its operation.

The apparatus of this embodiment includes a teaching welding line output circuit 32 in which a teaching welding line is set in advance, and from this circuit 32, for example, the teaching welding line A-8 shown in FIG.
A position signal r1 is output to the position control system 34.

In addition, such a welding torch 12 place Ni111 system 3
Usually, a welding robot is provided with a plurality of numerals 4, but in order to simplify the explanation, only one of them is illustrated and explained in the embodiment.

This position control system 34 receives the supplied signal from a subtracter 36,
Amplifier 38 and matching r! The actuator 42 includes an actuator 42 inputted via an 11 recognition circuit 40.
controls the position of the welding torch 12 based on the input signal.

Here, the output of the actuator 42 is fed back to the subtracter 36 via a feedback circuit 44. Therefore, the actuator 42 is configured such that the output signal of the subtracter 36 becomes O, that is, the device signal constituted by the teaching welding line output circuit 32 and the actuator 42
The position of the welding torch 12 is controlled so that the position of the welding torch 12 controlled by

As a result, in the device of this 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 A-8.

Simultaneously with the start of movement control of the torch 12 along the teaching welding line A-8, the welding power source 22 applies a predetermined welding voltage between the welding wire 10 and the workpiece 18, and the welding wire 10
An arc is generated between the workpiece 18 and the workpiece 18.

Therefore, the workpieces 18a and 18bG are reliably arc welded along the teaching welding line A-B shown in FIG.

In this embodiment, the deviation width f between the planned welding line and the actual welding position of the workpiece 18b positioned on the workpiece 18a is detected by an arc sensing method, which will be described in detail later, and the actual welding position is determined based on the deviation width f. Work 18a,
An automatic welding line correction mechanism 46 is provided that corrects the welding line so that it matches the planned welding line 18b.

In this embodiment, the automatic welding line correction mechanism 46 includes a deviation width measuring section 46a that detects the deviation width between the planned welding line and the actual planned welding position based on changes in the arc current or voltage of the welding torch 12; It also includes a welding position correction section 46b that corrects the movement of the workpiece a predetermined distance in the direction of the welding line when the width is equal to or greater than the allowable value.

Further, in this embodiment, the automatic correction mechanism 46 includes a weaving command generator 48, which outputs a weaving command I2 to the adder 50 based on the command from the welding line output circuit 32. In the adder 50, the weaving command (2) is superimposed on the teaching welding line command (2) output from the welding line output circuit 32, and the torch 12 is operated to weave.

Here, the torch 12 performs arc scanning intersecting the planned welding line of the workpiece 18, and the arc ffi! generated during the arc scanning! Alternatively, the deviation width f between the actual welding position and the planned welding line of the workpiece is detected based on changes in arc voltage.

In this embodiment, the deviation width measurement section 46a includes a current detection circuit 52, a peak memory 54, and a comparison circuit 58.

Changes in the arc state accompanying the weaving operation of the welding torch 12 are detected by the current detection circuit 52 according to the moving direction of the torch.
The changes in the current values (4) are stored in the peak memories 54L and 54R.

Note that sampling of the current value from the current detection circuit 52 is performed based on the tanoming signal (3) output from the timing command generator 56 linked to the weave command generator 48.

The peak memory value 1.16 stored in both peak memories 54L and 54R is input to the comparison circuit 58, and the difference (7) between the two memory values is output to the welding position corrector 46b.

In this embodiment, the welding position correction section 46b is the determination circuit 6.
0, a limit setter 62, and a correction amount generator 64.

The output I7 of the comparator circuit 58 is input to the discrimination circuit 60, and the threshold level set in advance by the limit setter 62 is set to 1. 11, and if the current difference value ■7 exceeds the threshold level by 1, corrects the Nq signal ■8 and generates F11.
? ! 164.

The correction 1 generator 64 determines the appropriate response depending on the input NO low signal extreme pressure (which detected current value of R and D is large, that is, in which direction the welding position is deviated from the planned welding line of the workpiece). A correction signal 110 having a directionality of
is output to the adder 60, and the correction signal [10 is superimposed on the output 11 from the teaching welding line output circuit 32.

As a result, the no-arc welding position moves in the direction of the planned welding line of the workpiece by one correction amount corresponding to the correction signal @T1o.

In this embodiment, the above-mentioned correction unit m is usually a very small amount of about 0.5-, and by continuously performing the above correction operations, the actual welding position is made to match the planned welding line of the workpiece. It is.

The correction signal '3' 1o may be a pulse method in which the arc welding position is moved by one correction distance each time a pulse is applied, or a slap method in which the correction signal is continued to be applied until the next correction is made. A method that continues to maintain the corrected state may also be used.

In this embodiment, an arc sensing method is employed to detect positional deviation during automatic arc welding, and an outline thereof will be described below.

In this embodiment, arc welding is performed by the weaving method, in which the welding wire 10 is vibrated at a predetermined amplitude in the direction crossing the welding line (weaving), and the workpiece is arc welded by weaving the welding line. . Here, the arc sensing method detects the positional shift of the workpieces from changes in the welding voltage and welding ffi flow that occur when an arc runs between the workpieces 18a and 18b to be welded.

That is, for example, at the start of arc welding, the arc scan for detecting positional deviation is performed on the detection line 5-Ek, which is orthogonal to the teaching welding line A-B at the starting point A in FIG. 10:
The scanning direction may be either from S to E or from E to S.

In this embodiment, this arc scanning is performed from S to E.

FIG. 4 shows an arc scan for detecting positional deviation at the start of arc welding, and 1'! Figure 5 shows changes in the arc current waveform.

First, arc scanning for positional deviation detection is performed from S to E. At this time, the workpiece 18b is connected to the teaching welding line A-
If the workpiece 18b is accurately positioned, the scanning line changes from S→A→C→E, but the workpiece 18b
is positioned with a deviation radius d with respect to teaching welding mA-8, the scanning line is S-+A
"→C'→E. At this time, as shown in FIG. 5, the change in arc current is constant in the S→A' section, increases sharply in the A'→C' section, and changes from C'→E. It becomes a constant value again in the interval.

This is because when arc scanning the S→A' section, the feed m of the welding wire 10 is balanced with the amount of wear and the quality of the tip of the wire 10 is almost constant, but A''-
When arc scanning the C-section, the wire tip suddenly approaches the A''-C' plane (w1 wall) of the workpiece, and the wire 1
The arc length is instantaneously shortened before the 0 melts excessively.

Since the arc portion has a much higher resistance value than the wire itself, at this moment, the total resistance value of the wire 10 and the arc column decreases significantly, and the arc current increases rapidly. This rapid increase in current causes the wire 10 to unravel and eventually return to its original arc length.

Further, when arc welding the section C'→E, the feed m and consumption l of the welding wire are balanced, and the length becomes a constant value with a reduced value.

As described above, the resistance value in the arc current circuit is constant in the S-+A' interval, rapidly decreases in the A'→C' interval, and remains constant at a reduced value again in the C'→E interval. Become.

As a result, when performing arc scanning for detecting positional deviation from point 8 to point E, this arc current increases rapidly in the <A''-C' section, as shown in Figure 5. , if the point at which the arc current starts to increase is detected, the workpiece 18b
The installation position relative to the workpiece 18a, that is, the welding line of the workpiece --E' can be detected.

In addition, in the explanation of the accensing method above, the detection of the positional deviation between the welding line of the workpiece and the teaching welding line using the arc sensing method at the start of arc welding was explained, but in the present invention, the arc sensing method continues even during welding. is being carried out.

As a result, during arc welding, the positional deviation between the actual arc welding position and the planned welding line of the workpiece is always detected and corrected.

Note that the so-called arc sensing method, which is a method of detecting a weld line on a workpiece based on changes in arc characteristic values, uses current as in the embodiment, but also methods that use voltage changes, and these methods can be applied in exactly the same way in the present invention.

In addition to the above-mentioned arc sensing method, various methods using laser light, TV cameras, etc. have been developed and put into practical use as the positional deviation correction method of the present invention.

In other words, according to a method using a laser beam, a TV camera, etc., the workpiece is aligned with the teaching welding line by scanning the laser beam or recognizing the image pattern obtained by the TV camera, etc. prior to arc welding. This system detects a positional deviation or a positional deviation between an actual welding position and a planned welding line on a workpiece, automatically corrects a predetermined teaching welding line based on the detected data, and performs arc welding on the workpiece.

Abnormality Detection Mechanism The welding line automatic correction mechanism according to the present invention not only detects the positional deviation between the teaching welding line and the planned welding line of the workpiece at the start of automatic welding as described above, but also detects the actual welding position during welding. The deviation width of the planned welding line of the workpiece is continuously measured.

The characteristic feature of the present invention is that the correction movement m of the welding position performed as described above is integrated, and when the deviation width between the welding planned line and the welding position is within the tolerance value, the welding position is integrated. The purpose is to reset the correction shift fIIfl<, and to output an abnormality detection signal when the integral correction movement amount exceeds a predetermined value.

For this purpose, the abnormality detection device 68 according to the present embodiment is an integrator that inputs the output from the correction amount generator P164 and integrates the correction movement m of the welding position until the OK signal 9 is input from the discrimination circuit 60. 70, and determines whether the integral correction movement amount output from the integrator 70 is equal to or greater than a predetermined value set in advance by the correction limit setting device 72, and detects an abnormality only when the integral correction movement amount is greater than the predetermined value. Discrimination circuit 7 that generates a signal
4.

Hereinafter, the operation of the abnormality detection device will be explained based on the timing charts shown in FIGS. 2 and 6.

First, at the start of automatic arc welding, scanning of the arc for detecting deviation is performed as described above.

Then, when the welding line automatic correction mechanism 46 determines that the deviation width is larger than the allowable value and that correction is necessary, the correction amount generator 6
The correction signal 1G outputted from the integrator 70 is inputted to the integrator 70.

The integrator 70 integrates the correction signal 110 to calculate an integral correction shift 1jJ m x of the arc welding position.

Here, when the discrimination circuit 60 determines that the workpiece deviation width f is less than or equal to the allowable value, an OK signal is sent to the integrator 70.
A signal I9 is input, and the integral value X of the integrator 70 is reset.

Therefore, in integration 15i70, the following integration is performed.

Here, ΔX is one correction signal '1 from the correction amount generator 64
This is a 1 unit correction distance by which the welding position moves in the direction of the 1 tangent line based on 0. Also, set to 0 -OK. +1 represents the interval at which the signal ■9 is output as 0 from the discrimination circuit 60.

The integral value 111 of the integrator 70 obtained as described above is output to the discrimination circuit 74, and in the discrimination circuit 74, the threshold level set in advance by the correction limit setter 72 is set to 2 and the output [11 of the integrator 70]. be compared.

If the determination circuit 74 determines that x > K 2 , an abnormality signal is output.

The control state of automatic arc welding by the automatic correction mechanism equipped with the abnormality detection device according to the present embodiment is shown in a fraudulent manner in FIGS. 7 and 8.

In FIG. 7(a), the broken line indicates the teaching welding line taught in advance to the welding line output circuit 32, and the actual 1! JE
indicates the planned welding line of the workpiece.

As is clear from the figure, the teaching welding line and the welding line E of the workpiece match the welding start point O, but there is a shift after that, and the workpiece is installed slightly diagonally from the predetermined position. is understood.

When welding starts on the workpiece, first welding start point 0
Welding is performed from to El along the teaching welding line.

At these 11 points, the determination circuit 60 of the correction mechanism 46 determines that the deviation width f between the welding position and the planned welding line of the workpiece is greater than or equal to the allowable value by 1, and a correction signal 1o is generated from the correction amount generation P164.

According to the correction signal '10, the welding position moves by one unit correction distance ΔX in the direction of the planned welding line E of the workpiece, and the integrator 70
Integrate ΔX.

In the illustrated example, one correction operation, that is, movement of ΔX, causes the welding position G to match the planned welding line E, and the discrimination circuit 6
0, the deviation width is determined to be less than the allowable value by 1, the correction operation is canceled, and the integral lia× of the integrator 70 is also reset by the OK signal 19 from the determination circuit 60.

From the correction amount IG1, automatic welding proceeds again in parallel to the teaching welding line according to the output of the teaching welding line output circuit 32.

As a result, the welding position progresses from G1 to F2, and at the point F, it is assumed that the deviation width exceeds the allowable value by 1 again, and the discrimination circuit 6
0 to the correction amount generator 64, and the correction amount generator 64 again moves the welding position in the direction of the planned welding line E by one unit correction value ΔX.

According to the automatic arc welding according to the present embodiment, by repeating the correction operation as described above, welding can be performed with a welding error within the tolerance range from the welding planned line E of the workpiece.

Here, if the welding start point O deviates from the allowable value by within 2, the subsequent progress of welding is always at the welding planned line E of the workpiece.
Welding is performed at a position along the teaching welding line, and even if the workpiece is placed at a slight angle to the teaching welding line, welding will proceed as long as there is no defect in the workpiece itself.

On the other hand, FIG. 7(b) shows a welding line automatic correction mechanism 46.
This shows a state in which the welding start point O to F is malfunctioning.
Welding is performed along the teaching welding line up to 1, and as a result of the determination circuit 60 determining that the deviation between the welding position at these 11 points and the planned welding line E of the workpiece is 1 or more, the welding position is , correction is started in the direction of the welding schedule 11E.

Here, if the automatic correction mechanism 46 is operating normally, the correction operation should be stopped at a position where the welding position is G, that is, corrected by ΔX from the 11 points, but the correction mechanism 46
Correction is continued due to the abnormal operation, and welding progresses in the Ga+ direction.

Here, if the correction amount has been integrated by the integrator 70 in the abnormality detection device of the present invention, and the integral correction shift vJIlix is 2 or more than the threshold level, the discrimination circuit 74
An abnormal signal is generated when this is determined.

In this embodiment, the threshold level 2 is set to 3 correction amounts ff1 (3ΔX), and an abnormal signal is generated when the point Qe in the figure is reached. Note that if the planned welding line of the workpiece is significantly deviated from the welding start point of the teaching welding line from the beginning, and the workpiece is arranged as shown by E' in FIG. The operation is performed and an abnormality detection signal is issued.

Then, in response to the abnormality detection signal, the automatic arc welding immediately stops a series of arc welding operations, outputs an alarm to notify the operator of the existence of an abnormality, and, if necessary, prevents the workpiece in which the abnormality has been detected. Spray paint for detecting non-defective products.

As explained above, the abnormality detection method and device according to the present invention can detect a positional shift of a workpiece that exceeds the allowable limit or a malfunction of the automatic welding line correction mechanism, and prevent the occurrence of welding defects in the workpiece. becomes possible.

[Effects of the Invention] As explained above, according to the present invention, in the automatic correction mechanism that corrects the positional deviation of a positioned workpiece, when the integral value of the correction movement amount of the welding position exceeds a predetermined value, Since the abnormality detection signal is output, it is possible to reliably detect abnormalities that impede the welding operation and prevent the occurrence of welding defects on the workpiece.

[Brief explanation of the drawing]

Fig. 1 is a flowchart diagram showing a preferred embodiment of the present invention, Fig. 2 is a circuit diagram showing a preferred embodiment of an automatic arc welding device to which the present invention is applied, and Fig. 3 is a correction shown in Fig. 2. 4 and 5 are explanatory diagrams of the mechanism for detecting a positional deviation between the welding position and the planned welding line of the workpiece. FIG. 6 is a timing diagram of the abnormality detection device according to the present invention. Figure 7 and Figure 8 are operation explanatory diagrams of the abnormality detection device according to the present invention. Figure 9 is an explanatory diagram of the external appearance of a conventional general automatic arc welding device. Figure 10 is a conventional automatic arc welding device. FIG. 2 is an explanatory diagram of problems with the device. 46... Automatic welding line correction mechanism 46a... Deviation width measurement section 46b... Welding position correction section 68... Abnormality detection device 70... Integrator 74... Discrimination circuit

Claims (3)

[Claims] (1) A deviation width measurement step of measuring the deviation width between the planned welding line of the workpiece and the actual welding position, and a correction by moving the welding position a predetermined distance in the direction of the planned welding line of the workpiece when the deviation width is greater than an allowable value. and a welding line automatic correction mechanism for correcting positional deviation in automatic arc welding, integrating the correction movement amount of the welding position, and when the deviation width is within a tolerance value, An abnormality detection method for an automatic welding line correction mechanism, comprising: resetting an integral correction movement amount of a welding position, and outputting an abnormality detection signal when the integral correction movement amount exceeds a predetermined value. (2) Deviation width measurement that has a torch that scans an arc along a detection line that intersects the planned welding line of the workpiece, and measures the deviation width between the planned welding line and the actual welding position based on changes in the arc of the torch. and a welding position correction section, which has a comparator that compares the deviation width with a preset tolerance value, and moves the welding position a predetermined distance in the direction of the welding line of the workpiece when the deviation width is equal to or greater than the tolerance value. In the welding line automatic correction mechanism for correcting positional deviation in automatic arc welding, the integrating circuit integrates the correction movement amount and resets the integral correction movement amount when the deviation width becomes less than or equal to an allowable value. and a comparison circuit that compares the integral corrected movement amount of the integrating circuit with a predetermined value set in advance, and outputs an abnormality detection signal when the integral corrected movement amount is equal to or greater than a predetermined value. Abnormality detection device for automatic welding line correction mechanism. (3) An abnormality detection device for an automatic welding line correction mechanism according to claim (2), characterized in that automatic arc welding is controlled to stop by outputting an abnormality detection signal.