JPH10296441A - Method for detecting degree of consumption of welding tip in short-circuit transfer arc welding and detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively grasp the degree of consumption of a welding tip by detecting the value of welding current and value of welding load voltage at the time of short-circuit while maintaining the interval between the welding tip and a material to be welded constant, determining the value of wire resistance and notifying that the life of the welding tip is ended when the value of wire resistance becomes a predetermined value. SOLUTION: In the short-circuit transfer arc welding, welding is executed while maintaining the interval between the welding tip 2 and the material W to be welded constant. The values of welding current and welding load voltage at the time of short-circuit are detected over the prescribed number of times and wire resistance equivalent average value R is determined. During the welding tip 2 is new, the power feeding position to an electrode wire 7 is in the vicinity of the tip of the welding tip 2. As the welding work is executed, the bore diameter of the welding tip 2 is enlarged, the power feeding position from the, welding tip 2 to the electrode wire 7 is elevated than that of a new tip and becomes unstable. By the change of the wire resistance equivalent average value R, the degree of the consumption of the welding tip 2 is grasped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting the degree of wear of a welding tip in short-circuit transfer arc welding in which droplet transfer is performed by repeating arc generation and short-circuit generation.

[0002]

2. Description of the Related Art In short-circuit transfer arc welding in which a droplet is transferred by repeating arc generation and short-circuit generation, an arc is generated between the electrode wire and a workpiece while an electrode wire is fed to a welding torch. Welding has been performed. In this case, electricity is supplied to the electrode wire via the welding tip of the welding torch. By the way, since the welding tip comes into contact with the supplied electrode wire, the welding tip is consumed as the welding time elapses. As the welding tip is consumed, the power supply position is not constant, the arc during welding becomes unstable, and the welding result gradually deteriorates. Therefore, it is necessary to appropriately replace the welding tip.

[0003]

However, at present, no method or apparatus for judging the time to replace the welding tip has been proposed yet. Of course, if the welding tip is replaced after the welding result has deteriorated, a post-process for correcting the defective welding is required, which is not preferable.

[0004] For this reason, by the time a defective welding portion occurs,
Replacement of the welding tip has been performed based on the experience of the worker, based on the welding time and observation of the welded portion.

[0005] As described above, even a welding tip that can still be used tends to be replaced with a new welding tip as soon as possible, which is uneconomical in using the welding tip.

Of course, if the replacement time is missed by mistake, a process of correcting a defective welding portion is required, which has been a problem in welding work.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a detection method capable of quantitatively grasping the degree of wear of a welding tip in short-circuit transfer arc welding such as so-called MAG welding or CO ₂ welding. It is to provide a method and a detection device.

[0008]

In order to achieve the above object, the first invention is applied to a method for detecting the degree of wear of a welding tip in short-circuit transfer arc welding. And has as its features, the welding tip and while maintaining a constant distance between the object to be welded, the welding and the welding current value I _o at short load voltage value V _o
Are detected for a predetermined number of short circuits, and a wire resistance equivalent average value _Ro is determined from the plurality of values, and after a predetermined time,
The welding current value I _j and the welding load voltage value V _j at the time of short circuit are detected for a predetermined number of times of short circuit, and a wire resistance equivalent average value R _j is obtained from the plurality of values. When _Rj becomes a predetermined value with respect to the average value _Ro corresponding to the wire resistance, the notification means notifies that the life of the welding tip is reached.

Further, the second invention is characterized in that, in the first invention, the detection of the welding current value and the welding load voltage value at the time of the short circuit is detected after a predetermined short time from the time of the short circuit. I have.

Further, according to the third aspect of the present invention, in the first or second aspect, the notifying means is arranged such that R _j = (1.2 to 1.3) R _o
It is characterized by being activated when it becomes.

Further, the fourth invention is characterized in that, in any of the first to third inventions, the wire resistance equivalent average value _Rj is obtained and recorded at predetermined time intervals. I have.

Further, the fifth invention is applied to a welding tip wear degree detecting device in short-circuit transfer arc welding. And has as its features, while maintaining the distance between the welding tip and the object to be welded constant, detected across the welding current value I _o of short circuits and the welding load voltage value V _o a predetermined short number of times detector and a computing unit from the plurality of detected values for calculating the wire resistance equivalent mean value R _o, storage means for storing the wire resistance equivalent mean value R _o, after a predetermined time, during a short-circuit by said detector Welding current value I _j and welding load voltage value V
_j over a predetermined number of short circuits, and based on the plurality of detected values, the arithmetic unit calculates a wire resistance equivalent average value _Rj, and calculates the wire resistance equivalent average value _Rj and the wire resistance. A comparator for comparing the equivalent average value _Ro with a notifying means for notifying that the life of the welding tip is reached when the comparison value reaches a predetermined value.

In a sixth aspect based on the fifth aspect, the detection of the welding current value and the welding load voltage value at the time of the short circuit by the detector is detected after a predetermined short time from the point of the short circuit. It is characterized by:

Further, according to a seventh aspect of the present invention, in the fifth or sixth aspect, the notifying means is arranged such that R _j = (1.2 to 1.3) R _o
It is characterized by being activated when it becomes.

According to an eighth aspect of the present invention, in any one of the fifth to seventh aspects of the present invention, the wire resistance equivalent average value _Rj is obtained at predetermined time intervals by the arithmetic unit.
The wire resistance equivalent average value _Rj is stored in the storage means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. For example, an arc welding robot provided with a welding tip wear degree detecting device for performing short-circuit transfer arc welding will be described. 1 to 4, reference numeral 1 denotes a welding torch for a consumable electrode having a welding tip 2 and a nozzle 3 at a tip end, 4 denotes a robot body supporting a welding torch 1 at a free end, and 5 denotes a short-circuit transfer arc welding. Is a wire feeder for feeding the electrode wire 7 to the workpiece W through the axis of the welding tip 2;
Is a first detector using a Hall element, for example, for detecting a welding current value I, 9 is a second detector using a Hall element, for example, for detecting a welding load voltage value V,
Reference numeral 10 denotes an A / D converter for A / D converting the detection values of the detectors 8 and 9, and reference numeral 11 denotes a terminal connected to the A / D converter 10. The above 1 to 11 constitute an arc welding robot for performing short-circuit transfer arc welding.

In the above, the position and orientation of the welding torch 1 are taught so that the distance between the tip of the nozzle 2 and the workpiece W is constant, and the arc welding robot is appropriately reproduced based on the teaching data. The desired short-circuit transfer arc welding is performed.

In this short-circuit transfer arc welding, FIG.
And arcing condition represented by T ₁ of the (A), and a short circuit condition represented by T ₂ are repeated. That is, FIG.
In the arc generation state represented by C ₁ and C _2, the molten ball is formed at the tip of the electrode wire 7, the molten ball is transferred to the welding subject W side. Thereafter, as indicated by C _3, a melt ball and the object to be welded W of the electrode wire 7 is short-circuited in a section of T _3. In the second half of this short circuit,
That is the section of the T ₄ as represented by C _4, a large current is going to be eliminated short circuit state flows.

By the way, while the welding tip 1 is new, the power supply position to the electrode wire 7 is stable near the tip of the welding tip 1. But as we perform the welding operation,
The welding tip 2 is consumed from the tip by contact with the wire and the hole diameter increases. For this reason, the power supply position from the welding tip 2 to the wire is higher than that of a new welding tip 2, and the state where the wire intermittently contacts between the raised power supply position and the tip end occurs. To do
As a result, the power supply position tends to vary, and the arc becomes increasingly unstable.

When the unstable state of the arc was investigated, it was found that the change in the equivalent value of the wire resistance in the short-circuit state in the section T ₄ in FIG. 3B was related to the degree of wear of the welding tip 2. .

[0021] That is, the welding current value I and the welding load voltage value V during a short-circuit condition of the section of the T ₄ is detected by the first and second detectors 8,9, the wire resistance equivalent value than this value R ( = V / I).

Of course, due to the complexity of the arc phenomenon, the above values I, V, R are not uniquely determined. However, in short-circuit arc welding, a short-circuit state of about several tens of times to about 100 times / second is repeated. Therefore, the above-described detection is performed for a predetermined number of times of short-circuiting. When R was obtained, it was found that the value was almost stable.

Of course, one short-circuit time T ₂ = T ₃ + T
_4, for example, 3ms about a short, after a predetermined short time from the short time, after a lapse i.e. T ₃ hours, performs the detection in the section T _4, repeated several times over the detection to a predetermined short number of times As a result, when the average value R corresponding to the wire resistance is obtained, the value becomes almost stable. In the above description, the interval between the welding tip 2 and the workpiece W is, of course, kept constant.

[0024] Now, in short circuiting transfer arc welding, when welding tip 2 is new, the welding current value I _o and the welding load voltage value V _o and a predetermined number of times short short-circuit state corresponding to the interval of T ₄ in FIG. 3 Then, the average value R _o (= V _o / I _o ) corresponding to the wire resistance is determined from the plurality of values.

[0025] After a predetermined weld has progressed time, to detect over the welding current value I _j and the welding load voltage value V _j of the short-circuit state corresponding to the section of the T ₄ to a predetermined short number of times, the plurality From the value of _Rj (= _Vj / I)
seeking _j), when the wire resistance equivalent average R _j becomes a predetermined value with respect to the wire resistance equivalent mean value R _o, informed by notification means that the life of the welding tip. For example, the terminal 11 notifies by an alarm buzzer or a warning screen.

[0026] Of course, the value of the wire resistance-equivalent average value R _j for wire resistance equivalent mean value R _o is not possible to determine uniquely the electrode wire diameter and welding conditions and the like, high-quality short-circuiting transfer arc work, For example, in a so-called MAG welding operation, for example, when R _o = 6.3 mΩ, it is preferable that R _j = 7.4 to 8.4 mΩ, and therefore R _j = (1.2 to 1.3). be selected with a predetermined value becomes R _o values are preferred. (A) and (B) of FIG.
In addition, the above-mentioned average value R equivalent to wire resistance in a new welding tip
_o and the number of calculations for obtaining
Relationship between the number of calculations for finding the wire resistance equivalent mean value R _j in the welding tip state quality welding results in AG welding is obtained is shown.

By the way, in the section of T ₄ in FIG. 3, the molten metal actually becomes thinner gradually with the passage of time.
The welding current value I and the welding load voltage value V slightly change microscopically due to the change in the power supply position. Therefore, the detection value I _o at the interval of _{T 4, I j, V o} , as the V _j, T ₄
Carried over detection at intervals in a predetermined short number of times, by adopting an average value detected this multiple times, more accurate wire resistance equivalent mean value R _o, so that the R _j are determined.

In the so-called CO ₂ welding, a relatively low-grade welding result is often acceptable, so that a value satisfying R _j ≦ 1.6R _o can be selected as a predetermined value. Of course, if higher quality welding results are obtained even with CO ₂ welding, the above values can of course be selected appropriately smaller.

In the above description, the calculation and notification means of R _o and R _j are executed by the terminal 11.
Is R _o, calculator for calculating R _j, storage means for storing the R _o and the set reference value R _jk, comparators and R _j for comparing the R _j and R _jk is the R _jk In this case, it is possible to separately provide notification means for notifying that the life of the welding tip is reached, for example, a display on a display or a control device and a notification sound.

Of course, as the notifying means, besides an alarm or a buzzer for recognizing that the life of the welding tip is over, it is also possible to employ an electric control means for preventing welding in combination with these. it can.

Further, the average value R corresponding to the wire resistance
_j, if intended to be recorded is determined for each predetermined time, as well as confirm the change with time of the wire resistance-equivalent average value R _j, it is possible to confirm the state of good welding has been performed. Of course, in this case, the R _j and recording the R _o at the first predetermined time has elapsed, but the R _j obtained corresponding to the at the next predetermined time may be recorded, at every predetermined time has elapsed if the obtained R _j and the R _o and the respective recording corresponding to the above, it can be reliably confirm the above.

Further, the average value R corresponding to the wire resistance
_j is obtained for each predetermined time by the arithmetic unit, if that the wire resistance equivalent mean value R _j is stored in the storage means, as well as confirm the change with time of the wire resistance-equivalent average value R _j, good It can be confirmed that a proper welding is being performed. Of course, in this case, it is the first predetermined time the R _j and the R _o during the storage can also store R _j obtained corresponding to the at elapsed next predetermined time, the predetermined time has elapsed If the obtained R _j and the above R _o corresponding to the above are stored, respectively, the above confirmation can be reliably performed.

Of course, according to the method and the device for detecting the degree of wear of a welding tip in short-circuit transfer arc welding according to the present invention, the degree of wear of the welding tip can be grasped quantitatively. Welding tips can be replaced in a timely manner before they occur.

[0034]

As is apparent from the above description, the first aspect of the present invention is a method for detecting the degree of wear of a welding tip in short-circuit transfer arc welding, in which the distance between the welding tip and the workpiece is maintained constant. Meanwhile, the welding current value I _o and the welding load voltage value V _o at the time of short circuit are detected for a predetermined number of short circuits, and a wire resistance equivalent average value R _o is obtained from the plurality of values. Short-circuit welding current value I _j and welding load voltage value V _j
Are detected over a predetermined number of short circuits, and a wire resistance equivalent average value _Rj is obtained from the plurality of values, and the wire resistance equivalent average value _Rj is previously determined with respect to the wire resistance equivalent average value _Ro . When the specified value is reached, the life of the welding tip is notified by the notification means, so that the degree of wear of the welding tip can be quantitatively grasped. Welding tip can be replaced at the same time.

According to the second invention, in the first invention,
Since the detection of the welding current value and the welding load voltage value at the time of the short circuit is detected after a predetermined short time from the time of the short circuit, an accurate detection value can be obtained, and as a result, an accurate average value corresponding to the wire resistance is obtained. be able to.

The present third invention, in the first or second invention, the notification means is the high-quality short-circuiting transfer arc work, and R _j = (1.2~1.3) R _o Since it is operated when it is no longer necessary, a high quality welding result can be reliably obtained.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the wire resistance equivalent average value R
_j is to be recorded is determined for each predetermined time, as well as confirm the change with time of the wire resistance-equivalent average value R _j, it is possible to confirm the state of good welding has been performed.

The second aspect of the present invention is a device for detecting the degree of wear of a welding tip in short-circuit transfer arc welding, in which a welding current value I _o at the time of a short-circuit is maintained while maintaining a constant distance between the welding tip and a workpiece. and welding the load voltage value V _o and a detector for detecting for a predetermined short number of times, the computing unit from the plurality of detected values for calculating the wire resistance equivalent mean value R _o, the wire resistance equivalent mean value storage means for storing the R _o, after a predetermined time, to detect over the welding current value I _j of short circuits and the welding load voltage value V _j to a predetermined short number of times by the detector,
A comparator detected based on the plurality of values calculates the wire resistance equivalent mean value R _j by said arithmetic unit, compared with the wire resistance equivalent mean value R _j and the wire resistance equivalent mean value R _o, the Notifying means for notifying that the life of the welding tip is reached when the comparison value reaches a predetermined value, so that it is possible to automatically know when to replace the welding tip before a defective welding portion occurs. Can be. Therefore, it is preferable to apply the fifth invention to a short-circuit transition arc automatic welding apparatus, particularly to a short-circuit transition arc welding robot.

According to the second invention, in the first invention,
Since the detection of the welding current value and the welding load voltage value at the time of the short circuit by the detector is detected after a predetermined short time from the time of the short circuit, an accurate detection value can be obtained,
As a result, an accurate average value corresponding to the wire resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an arc welding robot provided with a welding tip wear degree detecting device in short-circuit transfer arc welding according to the present invention.

FIG. 2 is an enlarged sectional view for explaining a power supply state to a welding wire at a distal end portion of the welding torch of FIG. 1;

FIG. 3 is a waveform diagram showing waveforms of the welding load voltage value and the welding current value over time during short-circuit transfer arc welding in FIG. 1, and a state explanatory diagram of the molten sphere growing at the tip of the wire corresponding thereto.

FIG. 4 is a diagram showing the number of operations for obtaining a wire resistance equivalent average value at the time of short circuit during short circuit transfer arc welding in FIG. 1 and a wire resistance equivalent average value. FIG. 4 (A) shows a new welding tip. And FIG. 4B is a diagram corresponding to a case of a worn welding tip after a predetermined time after welding has progressed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding torch 2 Welding tip 3 Welding nozzle 4 Robot main body 5 Welding power supply 6 Wire feeder 7 Electrode wire 8 First detector for detecting welding current value I 9 For detecting welding load voltage value V Second detector 10 A / D converter for A / D converting the detected value 11 Terminal

Claims (8)

[Claims] 1. A short circuiting transfer arc welding while maintaining the distance between the welding tip and the object to be welded constant, the welding current value I _o of short circuits and the welding load voltage value V _o a predetermined short number of times over and detected, from the plurality of values determined wire resistance equivalent mean value R _o, after a predetermined time, over the welding current value I _j of short circuits and the welding load voltage value V _j to a predetermined short number of times detecting and, from the plurality of values determined wire resistance equivalent mean value R _j, welding tip when the wire resistance equivalent mean value R _j becomes a predetermined value with respect to the wire resistance equivalent mean value R _o A method for detecting the wear degree of a welding tip in short-circuit transfer arc welding, wherein the life of the welding tip is notified by notification means. 2. The method according to claim 1, wherein the detection of the welding current value and the welding load voltage value at the time of the short circuit is detected a predetermined minute time after the short circuit. . Wherein said notification means is the high-quality short-circuiting transfer arc work, short of claim 1 or 2 is activated when it becomes the R _j = (1.2~1.3) R _o A method for detecting the degree of wear of a welding tip in transition arc welding. 4. The method according to claim 1, wherein the average value R _j corresponding to the wire resistance is obtained and recorded at predetermined time intervals. 5. In short-circuit transfer arc welding, a welding current value I _o and a welding load voltage value V _o at the time of short-circuiting are maintained for a predetermined number of short-circuits while maintaining a constant distance between a welding tip and a workpiece. A detector that calculates the average value _Ro corresponding to the wire resistance from the plurality of detected values; a storage unit that stores the average value _Ro corresponding to the wire resistance; A welding current value I _j and a welding load voltage value V _j at the time of short circuit are detected by a heater over a predetermined number of times of short circuits, and based on the detected plurality of values, the arithmetic unit calculates an average value R _j corresponding to wire resistance. calculates the inform a comparator for comparing the said wire resistance equivalent mean value R _j and the wire resistance equivalent mean value R _o, that the comparison value is the life of the welding tip upon a predetermined value Notifying means in short-circuit transfer arc welding Detector for wear level of welding tip. 6. The short-circuit transition arc welding according to claim 5, wherein the detection of the welding current value and the welding load voltage value at the time of the short-circuit by the detector is detected a predetermined short time after the point of the short-circuit. Device for detecting the degree of wear of the welding tip in the factory. Wherein said notification means is the high-quality short-circuiting transfer arc work, short according to R _j = (1.2~1.3) according to claim 5 or 6 is actuated when the a R _o A device for detecting the degree of wear of a welding tip in transition arc welding. 8. The wire resistance equivalent average value R _j is obtained by the arithmetic unit at predetermined intervals, and the wire resistance equivalent average value R _j is stored by the storage means.
8. The apparatus for detecting wear degree of a welding tip in short-circuit transfer arc welding according to any one of claims 1 to 7.