JP2021045782A - Weld zone monitoring device, welding equipment and welding method - Google Patents

Abstract

To highly sensitively detect occurrence of defect or the like including a crack occurring upon welding.SOLUTION: A weld zone monitoring device includes: a first AE sensor provided in a first measurement portion of a welding target and having a first frequency characteristic; a second AE sensor provided in a second measurement portion apart from the first measurement portion of the welding target and having a second frequency characteristic different from the first frequency characteristic; a reception unit receiving signals from the first AE sensor and the second AE sensor; a difference processing unit obtaining the difference between the signals from the first AE sensor and the second AE sensor received by the reception unit; a differential processing unit obtaining a time differential value for the difference signal obtained by the difference processing unit; and a signal detection unit detecting that the time differential value of the difference signal obtained by the differential processing unit exceeds a predetermined threshold value.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a weld monitoring device, a welding device, and a welding method.

When fractures such as defects including cracks occur in the structure during welding, unsteady elastic waves, so-called acoustic emissions (hereinafter, simply referred to as "AE"), are generated on the welded object due to rapid energy release. Events that occur may occur. A technique is known in which an elastic wave generated by such an event, a so-called AE wave, is detected by an AE sensor and the waveform is analyzed to detect the occurrence of defects including cracks in the structure.

JP 2011-64549

An electric signal indicating an elastic wave detected by an AE sensor (hereinafter referred to as an AE signal) is amplified by an amplifier circuit, for example, and frequency analysis is performed by a processing device or the like to obtain a frequency spectrum. Unsteady elastic waves generated from defects including minute cracks are weak, and the intensity of the signal signal appearing in the frequency spectrum may be smaller than the intensity of the noise signal. In such a case, it is difficult to select and detect the frequency of the frequency spectrum of the elastic wave caused by a defect including a crack. That is, when the intensity of the signal signal included in the AE signal is not sufficiently larger than the intensity of the noise signal, it is difficult to discriminate elastic waves caused by defects including cracks.

In particular, in the case of TIG welding, in shield gas ejection, automatic welding, etc., the noise signal increases in the frequency spectrum due to the influence of the drive system, and the ratio S / N of the signal signal intensity to the noise signal intensity decreases. As described above, it is a problem to detect with high sensitivity a signal signal indicating an elastic wave generated from a defect including a minute crack in a welded portion from the AE wave detected by the AE sensor.

An embodiment of the present invention has been made in view of the above circumstances, and is a welded portion monitoring device, a welding device, and a welding method capable of detecting the occurrence of defects including cracks during welding with high sensitivity. The purpose is to provide.

The welding monitoring device of the embodiment includes a first AE sensor provided for a first measurement point to be welded and having a first frequency characteristic, and a second measurement point to be separated from the first measurement point to be welded. Receives signals from a second AE sensor provided for the measurement location and having a second frequency characteristic different from the first frequency characteristic, the first AE sensor, and the second AE sensor. The time between the receiving unit, the difference processing unit for obtaining the difference between the signals of the first AE sensor and the second AE sensor received by the receiving unit, and the difference signal obtained by the difference processing unit. It has a differential processing unit for obtaining a differential processing value, and a signal detection unit for detecting that the time differential value of the difference signal obtained by the differential processing unit exceeds a predetermined threshold value.

Further, in the welding method of the embodiment, the elasticity generated at the time of welding by the first AE sensor having the first frequency characteristic and the second AE sensor having the second frequency characteristic different from the first frequency characteristic. Receive the wave,
The signal received by the first AE sensor and the signal received by the second AE sensor are subjected to differential processing, the signal obtained by the difference processing is time-differentiated, and the time differential value exceeds a predetermined threshold value. In this case, it is a method of controlling the welding conditions related to the welding work.

It is a schematic block diagram which shows the welding monitoring apparatus which concerns on this embodiment. It is a graph which shows an example of the waveform of the elastic wave detected by two different receiving parts in the welding monitoring apparatus of this embodiment. It is a graph which showed an example of the signal strength after the difference processing of two elastic waves. It is a graph which shows an example of the signal strength after the time differential processing of the signal obtained by the difference processing part. It is a graph which shows an example of the signal strength after performing the spike detection processing with respect to the measurement time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between the parts, and the like are not necessarily the same as the actual ones. Even if the same part is represented, the dimensions and ratios of each may be represented differently depending on the drawing.

In addition, in the present specification and each figure, the same elements as those described in the above-mentioned drawings are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

(Constitution)
FIG. 1 is a schematic configuration diagram showing a welding monitoring device according to the present embodiment.

The welded portion monitoring device 1 of the present embodiment detects a non-stationary elastic wave (AE wave) generated from a defect including a crack in the welded portion in the welded object 10 of a structure or the like, thereby detecting the welded object 10 It is a system that detects the occurrence of defects including cracks in the welded part. The welding device 5 that welds to the welding target 10 has a welding electrode 2, a welding rod 3, a welding machine 6, a drive unit 7, and a position sensor 8.

For the welding electrode 2, for example, tungsten or the like is used as the material. For the welding rod 3, the same material as the welding target 10, such as steel or stainless steel, is used as the material.

The welding machine 6 is connected to a welding electrode 2, a welding rod 3, a driving unit 7, a position sensor 8, and a control unit 60.

The welding machine 6 includes two electrodes, one electrode is connected to the welding electrode 2, and the other electrode is connected to the welding rod 3. The welding electrode 2 is connected to the welding target 10, and electrically conducts the welding machine 6 and the welding target 10. The welding rod 3 is held by a drive unit 7 described later and is arranged in the vicinity of the welding line of the welding target 10 so as not to come into contact with the welding target 10.

The drive unit 7 includes a drive device such as a motor that drives the position of the welding rod 3 along the direction of a predetermined welding line of the welding target 10, and is configured to be able to control the position of the welding rod 3.

The position sensor 8 is configured to be able to detect the relative position of the welding rod 3 with respect to the welding target 10. The position sensor 8 is, for example, an acceleration sensor provided in the drive device of the drive unit 7 and detects the acceleration acting on the drive unit 7 or the welding rod 3, and is a welding target by integrating the detected acceleration information. It may be configured so that the relative position of the welding rod 3 with respect to 10 can be detected. Alternatively, the position sensor 8 may be provided on the welding rod 3, for example, and may be configured so that the relative position of the welding rod 3 with respect to the welding target 10 can be detected by an encoder or the like, or the position sensor 8 includes a camera. The structure may be provided on the drive unit 7 or the welding target 10.

The welding target 10 is, for example, a structure made of a metal material. In this embodiment, the welding target 10 is made of a metal material, for example, steel or stainless steel in this embodiment, but is not limited thereto.

The control unit 60 uses the welding conditions of welding by the welding device 5, for example, the voltage applied between the welding rod 3 and the welding target 10, the relative position of the welding rod 3 with respect to the welding target 10, and / or the driving device of the driving unit 7. A signal is transmitted to the welding machine 6 to control the speed of the welding machine 6. The control unit 60 includes storage means such as a memory (not shown) and processing devices such as an IC, a microcomputer, and a CPU.

The welded portion monitoring device 1 receives an elastic wave from the welding target 10 and converts the elastic wave into an electric signal, that is, the first AE sensor 20, the second AE sensor 21, the receiving portions 20A, and 21A, respectively. It has an amplification unit 40, a signal processing unit 50, and a control unit 60. The signal processing unit 50 includes a difference processing unit 56, a differential processing unit 57, and a signal detection unit 59. The welding monitoring device 1 of the present embodiment is exemplified as a configuration including a control unit 60 that transmits a signal to the welding machine 6 so as to control welding construction conditions by the welding device 5 based on the monitoring result. It is not necessary to control the welding conditions of the welding apparatus 5 based on the monitor result as a configuration that is not provided.

The first AE sensor 20 is provided for the first measurement point 20B of the welding target 10. The second AE sensor 21 is provided for the second measurement point 21B of the welding target 10, which is different from the first measurement point 20B. In the present embodiment, the first measurement point 20B and the second measurement point 21B are provided apart from each other in the direction along the welding line on which welding is performed. The first AE sensor 20 and the second AE sensor 21 are provided directly on the welding target 10, and if the distance is such that elastic waves can be detected (for example, several millimeters), the first AE sensor 20 and the second AE sensor 21 are brought into direct contact with the welding target 10. It may be provided close to or separated from the welding target 10 without being provided.

The first AE sensor 20 and the second AE sensor 21 each have a piezoelectric element as a conversion element. The piezoelectric element is composed of PZT (lead zirconate titanate), LiNbO3 (lithium niobate single crystal), GaPO4 (gallium phosphate), AlN (aluminum nitride), La3Ga5SiO14 (langasite), Ga2Al2SiO7 and the like. In particular, a piezoelectric element composed of LiNbO3, AlN, Ga2Al2SiO7, or the like is suitable for use in a harsh environment of high temperature and high radiation.

Further, as a converting element of the first AE sensor 20 and the second AE sensor 21, an electromagnetic ultrasonic probe (EMAT) that converts acoustic energy into an electric signal (electrical vibration) by the interaction between the electromagnetic induction effect and the magnetic field. : Electro-magnetic acoustic transducer) may be used.

The first AE sensor 20 and the second AE sensor 21 have different frequency characteristics. For example, the first AE sensor 20 is selected from the waveform spectrum of the elastic wave generated by the welding phenomenon and has a higher sensitive frequency characteristic in a low band, and the second AE sensor 21 is selected as the first AE sensor 21. Unlike the frequency characteristics of the AE sensor 20, the waveform spectrum of the elastic wave generated by the welding phenomenon has a higher frequency characteristic in a high band and is selected.

The receiving unit 20A is electrically connected to the first AE sensor 20, and the receiving unit 21A is electrically connected to the second AE sensor 21. The receiving units 20A and 21A are electrically connected to the amplification unit 40, and are configured to be able to receive the signal of the first AE sensor 20 and the signal of the second AE sensor 21, respectively.

The amplification unit 40 is electrically connected to the reception units 20A and 21A and the signal processing unit 50.

In the present embodiment, the receiving units 20A and 21A are illustrated to be connected to the common amplification unit 40, but the amplification unit 40 connected to the receiving unit 20A and the amplification unit connected to the receiving unit 21A are illustrated. 40 may be configured as a separate body.

The amplification unit 40 of the present embodiment includes a circuit that electrically amplifies a weak electric signal from the piezoelectric element of the first AE sensor 20 and performs frequency filtering as needed. The circuit can be composed of an analog circuit or a digital circuit. Further, the circuit may include a programmable logic device (hereinafter referred to as PLD). For the PLD, for example, a programmable gate array, a so-called FPGA (field-programmable gate array), can be used.

The frequency of elastic waves generated by defects including cracks in welds is generally several kHz to several MHz. Therefore, the amplification band in the amplification unit 40 is preferably a wide band of about several kHz to several tens of MHz. The frequency filtering process for amplifying this band can be realized by using a high-pass filter, a low-pass filter, and a band-pass filter.

In the present embodiment, the electrical signals from the first AE sensor 20 and the second AE sensor 21 are subjected to frequency filtering processing in the amplification unit 40, but the signal detection unit 59 is also subjected to frequency filtering processing. You may do it.

The signal processing unit 50 is electrically connected to the amplification unit 40 and the control unit 60, and has a difference processing unit 56, a differential processing unit 57, and a signal detection unit 59.

In the present embodiment, the signal processing unit 50 has a processor (not shown) capable of executing various operations and a memory (not shown) capable of storing various constants. The signal processing unit 50 can be realized by a general computer. The signal processing unit 50 may be configured by using a plurality of electric circuits (processing circuits) and a plurality of computers for each of various functions.

The difference processing unit 56 is electrically connected to the amplification unit 40 and the differentiation processing unit 57, respectively. The differential processing unit 57 is electrically connected to the difference processing unit 56 and the signal processing unit 59. The signal detection unit 59 is electrically connected to the differential processing unit 57 and further electrically connected to the control unit 60. The control unit 60 is electrically connected to the signal detection unit 59 and the welding machine 6, and is configured to be able to transmit a control signal to the welding machine 6 based on the detection result of the signal detector 59.

(Action)
The construction of welding to the welded portion of the welding target 10 by the welding device 5 will be described below.

The welder 6 applies a voltage between the two electrodes. When a voltage is applied between the two electrodes of the welding machine 6, one electrode of the welding machine 6 is conducting to the welding target 10 via the welding electrode 2 and is connected to the other electrode of the welding machine 6. Since the welding rod 3 is arranged near the welding line of the welding target 10 so as not to come into contact with the welding target, the welding rod 3 is generated by the heat of the discharge generated by the voltage applied between the welding rod 3 and the welding target 10. Melts. When the drive unit 7 drives the welding rod 3 in the direction along the welding line where the welding target 10 is welded, the welding target 10 is welded along the welding line.

The drive unit 7 including the drive device can control the welding rod 3 with an arbitrary speed vector (speed) along the direction of the welding line of the welding target 10 based on a command of the control unit 60 described later. Is. Although it is described that the drive unit 7 controls the position of the welding rod 3, it suffices if the relative position of the welding rod 3 with respect to the welding target 10 can be controlled, and the welding target 10 and the welding rod 3 can be controlled by controlling the position of the welding target 10. The relative position of may be controlled.

As an example, the position sensor 8 is an acceleration sensor provided in the drive unit 7, monitors the speed of the drive unit 7, and detects the relative position of the welding rod 3 with respect to the welding target 10. In this example, the moving distance of the welding rod 3 can be obtained by integrating the time-series acceleration information detected by the position sensor 8 to obtain the speed, and further integrating the obtained speed over time. The obtained speed and travel distance information is stored in time series in a storage means (not shown) provided in the control unit 60.

The welding machine 6 changes the voltage and current applied between the welding rod 3 and the welding target 10 based on the information of the control unit 60. The storage means of the control unit 60 stores the voltage and current applied between the welding rod 3 and the welding target 10, the distance between the welding rod 3 and the welding target 10, and the position of the welding rod 3 at that time in association with each other. To do.

If a defect including a crack occurs in the welded portion when welding is performed on the welding target 10, an unsteady elastic wave (AE wave) is generated. The generated unsteady elastic wave propagates inside the welding target 10, and the first position 20B corresponding to the position where the first AE sensor 20 is provided and the position where the second AE sensor 21 is installed are installed. Each reaches the second position 21B corresponding to. A conversion element such as a piezoelectric element provided in each of the first AE sensor 20 and the second AE sensor 21 electrically signals the acoustic energy of the elastic wave that has reached the first position 20B and the second position 21B, respectively. That is, it is converted into a voltage. As a result, the first AE sensor 20 and the second AE sensor 21 generate electric signals representing elastic waves, respectively. The electric signals representing the elastic waves generated by the first AE sensor 20 and the second AE sensor 21 are transmitted to the amplification unit 40 via the reception units 20A and 20B, respectively. The amplification unit 40 amplifies an electric signal indicating an elastic wave received from the reception units 20A and 21A and transmits it to the signal processing unit 50.

The elastic waves generated inside the object 10 to be welded include only non-stationary elastic waves directly caused by the generation of defects including cracks in the welded portion, such as elastic waves generated by defects including cracks. It also includes elastic waves caused by welding, such as elastic waves generated by peripheral equipment. The conversion elements provided in each of the first AE sensor 20 and the second AE sensor 21 are used not only for non-stationary elastic waves directly caused by the occurrence of defects including cracks in the welded portion but also for welding work. The resulting elastic wave is also output as a signal. Therefore, in order to detect defects during welding, the elastic wave signal caused by the welding work itself becomes a noise signal, which is directly caused by welding such as the occurrence of defects including cracks in the welded portion. It is desirable to efficiently generate the signal of the elastic wave to be detected as a signal signal to be detected.

Here, since the speed at which the elastic wave in the material travels is sufficiently faster than the resolution of the AE sensor, the elastic wave signal generated by each of the first AE sensor 20 and the second AE sensor 21 is an elastic wave. Corresponds to the distance of the first position 20B of the welding target 10 corresponding to the position where the first AE sensor 20 is installed from the point of occurrence and the position where the second AE sensor 21 is installed from the point where the elastic wave is generated. It does not depend on the difference in the distance between the second positions 21B of the welding target 10 to be welded. That is, the time difference between the elastic wave signals generated by each of the first AE sensor 20 and the second AE sensor 21 can be ignored. Therefore, when the electric signals obtained by the first AE sensor 20 and the second AE sensor 21 are different, the cause is that the frequency characteristics of the first AE sensor 20 and the second AE sensor 21 are different. Can be regarded.

That is, since the frequency of the elastic wave signal (noise signal) caused by the welding work itself is detected over a wide band, the electric signals generated by the first AE sensor 20 and the second AE sensor 21 having different frequency characteristics are different. In this case, these electric signals shall be regarded as signals caused by unsteady elastic waves due to the generation of defects including cracks in the welded portion.

Utilizing this, the signal processing unit 50 uses this for each of the electric signals detected by the first AE sensor 20 and the second AE sensor 21 and amplified by the amplification unit 40 via the reception units 20 and 21. Signal processing is performed. Hereinafter, the content of signal processing in the signal processing unit 50 will be described.

The difference processing unit 56 of the signal processing unit 50 performs the difference processing for calculating the difference between the electric signals transmitted by the first AE sensor 20 and the second AE sensor 21 transmitted from the amplification unit 40, and performs the difference processing. The electric signal is output to the differential processing unit 57.

The differential processing unit 57 performs differential processing for calculating the differential value (time differential value) of the electric signal output by the difference processing unit 56 with respect to time, and outputs the differentially processed electric signal to the signal processing unit 59.

The signal detection unit 59 detects an electric signal (spike Sp) that momentarily rises and falls among the electric signals obtained by the differential processing unit 57, and the amplitude of the spike Sp exceeds a predetermined threshold value. Is detected, and the detected electric signal is output to the control unit 60.

2 to 5 are graphs showing elastic wave signals in the welding monitoring device 1 of the present embodiment.

FIG. 2 is a graph showing an example of waveforms of elastic waves detected by two different receiving units 20A and 21A in the welding monitoring device 1 of the present embodiment. The waveform of FIG. 2 shows the signal strengths I and I'with respect to the measurement time t.

FIG. 3 is a graph showing an example of the signal intensity with respect to the measurement time t after the difference processing of the two elastic waves in the welding monitoring device 1 of the present embodiment. The difference processing unit 56 calculates the difference in the amplitude of the electric signal of the elastic wave at the same measurement time of the first AE sensor 20 and the second AE sensor 21, and outputs it as the difference ΔI of the signal strength with respect to the measurement time t. The signal waveform output by the difference processing unit 56 is shown in FIG. 3, and is wider than the graph of the signal strength with respect to the measurement time t of the elastic waves detected by the two receiving units 20A and 21A shown in FIG. It can be seen that the noise signal of the welding work itself detected over the frequency of is removed, and the signal signal is extracted and clarified.

FIG. 4 shows the signal strength with respect to the minute time dt at a predetermined measurement time after the difference signals of the AE sensors 20 and 21 obtained by the difference processing unit 56 are differentiated in the welding monitoring device 1 of the present embodiment. It is a graph which shows an example. That is, the differential processing unit 57 performs differential processing of the signal obtained by the difference processing unit 56, and outputs the time derivative d (ΔI) / dt of the signal intensity difference. FIG. 4 shows an example of the signal waveform output by the differential processing unit 57, and the signal signal and the noise signal are further distinguished by calculating the time differential value with respect to the difference in signal strength obtained in FIG. can do.

FIG. 5 is a graph showing an example of the spike signal intensity obtained by performing the spike Sp detection process with respect to the measurement time in the welding monitoring device 1 of the present embodiment. The signal detection unit 59 detects as spike Sp a signal exceeding a predetermined threshold value (shown by a solid line) among the signals output by the differentiation processing unit 57, and outputs the spike signal intensity with respect to the measurement time.

When the signal detection unit 59 detects the spike Sp, the control unit 60 determines that an abnormality has occurred in the welded portion. FIG. 5 shows an example of the signal waveform output by the signal detection unit 59, and the shape of the spike Sp is not limited to this.

The control unit 60 controls the welding machine 6 based on the electric signal obtained by the signal detection unit 59. For example, the control unit 60 is electrically connected from the welding machine 6 via the welding electrode 2 when the control unit 60 detects an abnormality in the welding portion based on the signal obtained by the signal detection unit 59. The voltage and current applied between the welding target 10 and the welding rod 3 are controlled. Alternatively, the drive unit 7 of the welding machine 6 is driven based on the position information detected by the position sensor 8 to control the relative position between the welding rod 3 and the welding target 10. Alternatively, when the control unit 60 detects an abnormality in the welded portion based on the electric signal obtained by the signal detection unit 59, the control unit 60 adjusts the moving speed of the welding rod 3 by the drive unit 7. By doing so, it is possible to promptly correct the welding conditions that cause an abnormality in the welded portion.

Alternatively, when the control unit 60 detects an abnormality in the welded portion (that is, the signal output by the differential processing unit 57 exceeds a predetermined threshold value), the welding rod 3 is used to re-weld the abnormal portion. The drive unit 7 of the welding machine 6 may be controlled so as to move along the welding line. In this case, the voltage or current applied to the welding electrode 2 and the welding rod 3 when the welding machine 6 re-welds the abnormal welded portion of the welding target 10 is different from the voltage or current initially applied. It is preferable to do so. At this time, the control unit 60 reads out the position of the welding rod 3 when an abnormality occurs in the welding portion and the current / voltage applied by the welding machine 6 when the abnormality occurs from the storage means, and drives the welding device 5. By controlling the part 7, the welding rod 3 is moved to a position where an abnormality such as a defect including a crack in the weld has occurred, and a command for a new current / voltage value is transmitted or driven to the welding machine 6, for example. A new command value of the relative position and distance between the welding rod 3 and the welding target 10 and the welding speed is transmitted to the portion 7 to control the welding to be performed again. In this case, at least one of the current and voltage applied between the welding rod 3 and the welding target 10 by the welding machine 6, the relative position and distance between the welding rod 3 and the welding target 10, or the welding speed is changed. ..

Alternatively, when the control unit 60 detects an abnormality, the voltage applied to the welding electrode 2 may be temporarily stopped, or the drive unit 7 may be controlled so as to stop the movement of the welding rod 3.

(effect)
As described above, the welding monitoring device 1 of the present embodiment has the signal processing unit 50 for defects including cracks included in the signals showing unsteady elastic waves obtained from the receiving units 20A and 21A. The resulting signal can be detected with high sensitivity. Thereby, according to the embodiment, the occurrence of defects including cracks during welding can be detected with high sensitivity.

By performing the difference processing of the signals obtained by the first AE sensor 20 and the second AE sensor 21, the ratio of the noise signal to the signal signal can be reduced and the accuracy of detecting the signal signal can be improved. Furthermore, by performing differential processing after difference processing, spike Sp, which is an electrical signal that rises and falls momentarily, which is peculiar to defects including cracks in welds, is clarified among the signal signals from which noise signals have been removed. Can be detected.

The difference processing unit 56, the differential processing unit 57, and the signal detection unit 59 included in the signal processing unit 50 can detect a signal signal from the combined wave of the signal signal and the noise signal, and efficiently detect an abnormality in the welded portion. And said. The signal processing unit 59 detects a value whose signal strength exceeds a predetermined threshold value as a spike Sp, so that the difference between the signal signal and the noise signal can be clarified and the signal signal can be detected.

Further, from the detected abnormality of the welded portion, it is possible to control to correct the abnormality of the welded portion by identifying the position of the abnormality and controlling the position of the welding rod 3.

Although the present embodiment has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Welding part monitoring device 2 ... Welding electrode 3 ... Welding rod 5 ... Welding device 6 ... Welding machine 7 ... Drive part 8 ... Position sensor 10 ... Welding target 20 ... First AE sensor 20A ... Receiver part 20B ... First Measurement point 21 ... Second AE sensor 21A ... Reception unit 21B ... Second measurement point 40 ... Reception unit 50 ... Signal processing unit 56 ... Difference processing unit 57 ... Differential processing unit 59 ... Signal detection unit 60 ... Control unit Sp ... spike

Claims (7)

A first AE sensor provided for the first measurement point to be welded and having a first frequency characteristic,
A second AE sensor provided for a second measurement point separated from the first measurement point to be welded and having a second frequency characteristic different from the first frequency characteristic,
The first AE sensor, a receiving unit that receives a signal from the second AE sensor, and the like.
A difference processing unit for obtaining the difference between the signals of the first AE sensor and the second AE sensor received by the receiving unit, and a difference processing unit.
A differential processing unit that obtains a time derivative value for the difference signal obtained by the difference processing unit, and a differential processing unit.
A signal detection unit that detects that the time derivative value of the difference signal obtained by the differentiation processing unit exceeds a predetermined threshold value, and a signal detection unit.
Welding part monitoring device with. The first AE sensor has a more sensitive frequency characteristic in a lower band of the elastic waveform spectrum generated during welding, and the second AE sensor 21 has a higher frequency band in the elastic waveform spectrum generated during welding. The weld monitoring device according to claim 1, which has a more sensitive frequency characteristic. The welding monitoring device according to claim 2 and
Welding means for welding the object to be welded and
A welding device including a control unit that controls the welding means based on the detection result of the signal detection unit. The welding means includes a drive unit for moving a welding position for welding the object to be welded.
The control unit controls the moving speed of the welding position by the driving unit at a position where the signal processing unit detects that the threshold value has been exceeded.
The welding apparatus according to claim 3. The welding means includes a welding electrode electrically connected to the welding target and a welding rod for welding the welding target.
The control unit changes the voltage applied between the welding electrode and the welding rod when the signal processing unit detects that the threshold value has been exceeded.
The welding apparatus according to claim 3 or 4. The welding apparatus according to claim 5, wherein when the signal treatment unit detects that the threshold value has been exceeded, the welding means temporarily stops the voltage applied between the welding electrode and the welding rod. .. The first AE sensor having the first frequency characteristic and the second AE sensor having the second frequency characteristic different from the first frequency characteristic receive elastic waves generated during welding.
The signal received by the first AE sensor and the signal received by the second AE sensor are subjected to difference processing.
The time derivative value of the signal obtained by the difference processing is calculated.
When the time derivative value exceeds a predetermined threshold value, the welding conditions related to the welding work are controlled.
Welding method.

Images