JP2018164928A - Welding quality determination method and device in lap seam welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding quality determination method and a device in lap seam welding, by which quality of a welding state in the lap seam welding can be correctly determined .SOLUTION: According to this method, a surface temperature of a weld zone, a welding voltage between a pair of electrode rings, and an applied pressure by the pair of electrode rings are measured (S1). It is determined that poor welding occurs (S6) in the case that a change rate of a temperature calculated from a measured value of the surface temperature is out of a predetermined temperature change rate threshold range (S2), or in the case that a change rate of the welding voltage calculated from a measured value of the welding voltage is out of a predetermined voltage change rate threshold range (S3), or in the case that a change rate of the applied pressure calculated from a measured value of the applied pressure is out of a predetermined applied pressure change rate threshold range (S4), and it is determined that good welding occurs (S5) in the case that all of the change rate of the surface temperature, the change rate of the welding voltage, and the change rate of the applied pressure fall within the predetermined change rate threshold ranges (S2, S3, S4).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a welding quality determination method and apparatus for lap seam welding, and in particular, a method and apparatus for determining the quality of a welding state when lap seam welding is performed while pressing an overlapping portion of a metal band with a pair of electrode wheels. About.

Conventionally, for example, in a continuous line such as a continuous annealing line, a continuous plating line, a continuous coating line, and a rewinding line, the rear end of the metal band that is the preceding material in order to continuously process the metal band such as a steel strip. Welding is performed on the overlapping portion of the portion and the leading end portion of the metal band to be the following material.
As a welding method, the metal band overlapped portion is pressed between a pair of electrode wheels, and in a state where the pair of electrode wheels is energized, welding is performed by moving these electrode wheels in the width direction of the metal band. So-called lap seam welding is mainly employed.

In this lap seam welding, if a welding failure occurs for some reason and the welded part breaks in the continuous line, there is a possibility that the operation is stopped for a long time. If the welding state can be determined at the time of welding, the continuous line can be stopped at an arbitrary timing, and the operation stop period can be minimized.
Therefore, for example, in Patent Document 1, the temperature after welding near the electrode ring and the voltage between the electrode rings are measured, and when these measured values are within a predetermined range, the welding state is normal. Is determined as a quality determination method for lap seam welding.

Japanese Patent Laid-Open No. 9-253866

  However, the temperature after welding in the vicinity of the electrode ring is affected by the ambient temperature and the heat input from the place where the welding is performed, so the welding state is different even if the measured temperature value is the same. There is a case. Therefore, even if the measured value of the temperature after welding in the vicinity of the electrode ring is within a predetermined range, the welding state may not be good.

  In particular, when thin metal bands are overlapped and welded, wrinkles may occur in the metal bands due to shape defects or the like. When this wrinkle is located at the overlapping portion of the metal band, the contact state between the two metal bands at the overlapping portion is locally deteriorated, and between the front and back surfaces of the overlapping portion sandwiched between the pair of electrode rings. In some cases, the electric resistance value of the electrode ring becomes high, and the temperature after welding near the electrode ring and the voltage between the electrode rings change rapidly. However, since these temperature and voltage changes are local, if the measured values of temperature and voltage are within predetermined ranges, the welding state is not determined to be abnormal, There is a risk.

  The present invention has been made to solve the above-described conventional problems, and provides a welding quality determination method and apparatus for lap seam welding that can accurately determine the quality of a welding state in lap seam welding. For the purpose.

  In the method for determining whether or not the lap seam is welded according to the present invention, the overlapping portion of the metal band is pressed between the pair of electrode wheels, and the pair of electrode wheels are applied to the overlapping portion while the pair of electrode wheels are energized. A welding quality determination method for lap seam welding in which the overlapping portion is welded by relatively moving the surface, the surface temperature of the overlapping portion at the time of welding or the vicinity thereof, the voltage between the pair of electrode rings, and a pair of Measure the pressure applied by the electrode wheel, and if the rate of change of the surface temperature calculated from the measured value of the surface temperature is outside the predetermined temperature change rate threshold range or calculated from the measured value of the voltage When the voltage change rate is outside the predetermined voltage change rate threshold range, or the pressure change rate calculated from the measured value of the applied pressure is a predetermined pressure change rate threshold value. range If it is, a method of determining a defective weld.

  The rate of change of the surface temperature is within the temperature change rate threshold range, the rate of change of the voltage is within the voltage change rate threshold range, and the rate of change of the applied pressure is within the applied pressure change rate threshold range. Even if the measured value of the surface temperature is out of the predetermined temperature threshold range, or the measured value of the voltage is out of the predetermined voltage threshold range, or the pressurizing force When the measured value is outside the predetermined pressure threshold range, it is preferable to determine that the welding is defective.

  A welding quality determination device for lap seam welding according to the present invention presses a metal band overlapping portion sandwiched between a pair of electrode wheels and energizes the pair of electrode wheels with respect to the overlapping portion. A weld quality determination device for lap seam welding that welds the overlapped portion by relative movement and a pair of a temperature sensor that measures the surface temperature at or near the welded portion of the overlapped portion at the time of welding, and a pair at the time of welding The rate of change of the surface temperature calculated from the measured value of the surface temperature by the temperature sensor, the voltmeter for measuring the voltage between the electrode wheels, the pressure sensor for measuring the pressure applied by the pair of electrode wheels during welding When the temperature change rate is outside the predetermined threshold range, or the voltage change rate calculated from the voltage measured by the voltmeter is a predetermined voltage change rate threshold range. , Or when the rate of change in the force calculated from the measured value of the force applied by the force sensor is outside the predetermined pressure change rate threshold range And a determination unit.

  In addition, the welding pass / fail judgment unit determines that the rate of change in surface temperature is within the temperature change rate threshold range, the rate of change in voltage is within the voltage change rate threshold range, and the rate of change in applied pressure is the change in applied pressure. Even if it is within the rate threshold range, the measured value of the surface temperature by the temperature sensor is outside the predetermined temperature threshold range, or the measured value of the voltage by the voltmeter is a predetermined voltage. It is preferable to determine that the welding is defective when it is outside the threshold value range or when the measured value of the applied pressure by the applied pressure sensor is outside the predetermined applied pressure threshold range.

  According to the present invention, when the rate of change of the surface temperature calculated from the measured value of the surface temperature at or near the welded portion of the overlapping portion is outside the predetermined temperature change rate threshold range, When the voltage change rate calculated from the measured value of the voltage between the electrode wheels is outside the predetermined voltage change rate threshold range, or calculated from the measured pressure value of the pair of electrode wheels Since the welding failure is determined when the change rate of the applied pressure is outside the predetermined applied pressure change rate threshold range, it is possible to accurately determine the quality of the welding state in the lap seam welding.

It is a figure for demonstrating the lap seam welding in a continuous line. It is a figure which shows the lap seam welding machine provided with the welding quality determination apparatus of the lap seam welding which concerns on Embodiment 1 of this invention. 3 is a flowchart showing a weld quality determination in the first embodiment. It is a graph which shows the example of a measurement of the surface temperature and welding voltage of a welding location. It is a graph which shows the average value of the metal band width direction of a welding voltage in the many lap seam welding examples, and the generation number. It is a graph which shows the change rate of the welding voltage and the generation number in many lap seam welding examples. 6 is a flowchart showing a weld quality determination in the second embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
With reference to FIG. 1, the lap seam welding of the steel strip in a continuous line is demonstrated. The rear end portion 1A of the metal band 1 as the preceding material and the front end portion 2A of the metal band 2 as the succeeding material, which are located downstream of the metal band 1 with respect to the traveling direction D1 of the continuous line, are overlapped. Thus, the overlapping portion 3 is formed.

The electrode ring 4 is disposed on the surface of the overlapping portion 3 and the electrode wheel 5 is disposed on the back surface of the overlapping portion 3, and the overlapping portion 3 is sandwiched from above and below by the pair of electrode wheels 4 and 5. ing. The electrode wheels 4 and 5 have the same shape and size as each other, and are held so as to be rotatable around a rotation axis along the traveling direction D1 of the continuous line.
In such a state that the electrode ring 4 and 5 are energized while the electrode ring 4 and 5 are energized by pressing the overlapping portion 3 between the pair of electrode wheels 4 and 5, the width direction D 2 of the metal bands 1 and 2 is set. The lap seam welding is performed on the overlapping portion 3 by traveling in the traveling direction D3 along the direction.

FIG. 2 shows the configuration of a lap seam welder provided with a welding quality determination device 20 for lap seam welding according to the first embodiment.
An upper arm portion 7 and a lower arm portion 8 of the carriage frame 6 extend along the metal band width direction D2 and are attached to the lower portion of the upper arm portion 7 via a pressurizing device 9. The electrode wheel 4 is rotatably held, and the electrode wheel 5 is rotatably held by an electrode wheel holding member 11 fixed to the upper part of the lower arm portion 8. The pressurizing device 9 is used to press the overlapping portion 3 of the metal bands 1 and 2 between the pair of electrode wheels 4 and 5 by, for example, pressing the electrode wheel holding member 10 downward using compressed air. Is.

A welding power source 12 is connected to the pair of electrode wheels 4 and 5. The welding power source 12 is a power source for performing constant current control for supplying a constant welding current to the overlapping portion 3 of the metal bands 1 and 2 via the pair of electrode wheels 4 and 5.
The carriage frame 6 is arranged so as to be movable along the rail 14 extending in the metal band width direction D2 by the moving device 13.

  Furthermore, a temperature sensor 15 that measures the surface temperature of the welded portion of the overlapping portion 3 is attached to the electrode wheel holding member 10 that holds the electrode wheel 4. As the temperature sensor 15, for example, an infrared temperature sensor that performs temperature measurement in a non-contact manner using infrared rays can be used. In order to measure the surface temperature immediately after welding, the electrode wheel 4 is moved in the traveling direction D 3. On the other hand, a temperature sensor 15 is arranged from the rear of the electrode wheel 4 so as to face the contact point between the electrode wheel 4 and the overlapping portion 3.

A voltmeter 16 is connected to the welding power source 12. The voltmeter 16 is used to measure a voltage generated between the pair of electrode wheels 4 and 5 by the power supply from the welding power source 12, that is, a welding voltage applied between the front surface and the back surface of the overlapping portion 3. Is.
A pressure sensor 17 for measuring the pressure applied by the pair of electrode wheels 4 and 5 is attached to the pressure device 9. The pressurizing sensor 17 can be composed of, for example, a pressure gauge that detects the pressure of compressed air.

A welding quality determination unit 18 is connected to the temperature sensor 15, the voltmeter 16, and the pressure sensor 17. The welding pass / fail judgment unit 18 is obtained by the surface temperature of the welding portion of the overlapping portion 3 obtained by the temperature sensor 15, the welding voltage between the pair of electrode wheels 4 and 5 obtained by the voltmeter 16, and the pressure sensor 17. By monitoring the pressure applied by the pair of electrode wheels 4 and 5 respectively, the welding state at the welding location is estimated and the quality of the welding is determined.
The temperature sensor 15, the voltmeter 16, the pressure sensor 17, and the welding quality determination unit 18 constitute a welding quality determination device 20 according to the first embodiment.

When welding the metal bands 1 and 2, as shown in FIG. 1, the rear end portion 1A of the metal band 1 as the preceding material and the front end portion 2A of the metal band 2 as the following material are overlapped. Thus, the overlapping portion 3 is formed, and the metal bands 1 and 2 are clamped by an unillustrated exit side clamp device and an entrance side clamp device, respectively, and their positions are fixed.
Further, power is supplied from the welding power source 12 to the pair of electrode wheels 4 and 5, and the pressurizing device 9 is driven to pressurize the overlapping portion 3 of the metal bands 1 and 2 with the pair of electrode wheels 4 and 5. By moving the carriage frame 6 along the rail 14 by the moving device 13 and causing the pair of electrode wheels 4 and 5 to travel at a constant speed in the traveling direction D3 along the metal band width direction D2, The mating portion 3 is lap seam welded.

Here, the quality determination of welding by the quality determination part 18 of welding is demonstrated with reference to the flowchart of FIG.
Note that the welding pass / fail judgment unit 18 includes a temperature change rate threshold range that represents a positional change rate in the metal band width direction D2 of the surface temperature of the welded portion of the overlapping portion 3 when normal welding is performed. A voltage change rate threshold range representing a positional change rate of the welding voltage between the pair of electrode wheels 4 and 5 in the metal band width direction D2, and a metal band width of the pressure applied by the pair of electrode wheels 4 and 5 It is assumed that a pressure change rate threshold range indicating a positional change rate in the direction D2 is predetermined and stored. These temperature change rate threshold range, voltage change rate threshold range, and applied pressure change rate threshold range can be obtained based on past results.
Since the pair of electrode wheels 4 and 5 travels at a constant speed in the traveling direction D3, the positional change rate in the metal band width direction D2 of the surface temperature predetermined in the welding quality determination unit 18, the welding voltage The positional change rate in the metal band width direction D2 and the positional change rate in the metal band width direction D2 of the metal band width direction D2 are respectively the temporal change rate of the surface temperature, the temporal change rate of the welding voltage, and the applied pressure. It corresponds to the rate of change over time.

  First, in step S <b> 1, the surface temperature of the welded portion of the overlapping portion 3 is measured by the temperature sensor 15, the welding voltage between the pair of electrode wheels 4 and 5 is measured by the voltmeter 16, and the pair of pressure sensors 17 The pressure applied by the electrode wheels 4 and 5 is measured.

In the subsequent step S2, the positional change rate of the surface temperature in the metal band width direction D2 is calculated from the measured value of the surface temperature of the welded portion of the overlapping portion 3 by the temperature sensor 15, and the calculated change rate of the surface temperature is calculated. Are compared with a predetermined temperature change rate threshold range.
When the calculated change rate of the surface temperature is within a predetermined temperature change rate threshold range, the process proceeds to step S3, and this time, the pair of electrode wheels 4 and 5 by the voltmeter 16 is advanced. The positional change rate of the welding voltage in the metal band width direction D2 is calculated from the measured value of the welding voltage between the welding voltage, and the calculated change rate of the welding voltage is compared with a predetermined voltage change rate threshold range. Is done.

When the calculated change rate of the welding voltage is within a predetermined voltage change rate threshold range, the process proceeds to step S4, and from the measured value of the applied pressure by the applied pressure sensor 17, the applied pressure is calculated. The positional change rate in the metal band width direction D2 is calculated, and the calculated change rate of the applied pressure is compared with a predetermined applied pressure change rate threshold range.
In step S4, when the calculated change rate of the applied pressure is within a predetermined applied force change rate threshold range, the change rate of the surface temperature of the welded portion, the change rate of the welding voltage, Since the change rate of the applied pressure is within the predetermined change rate threshold range, it is determined in step S5 that the welding currently being performed is good.

On the other hand, if the calculated change rate of the surface temperature is outside the predetermined temperature change rate threshold range as a result of the comparison in step S2, it is determined that an abnormality has occurred for some reason. In S6, it is determined that the current welding is defective.
Similarly, as a result of the comparison in step S3, even when the calculated change rate of the welding voltage is outside the predetermined voltage change rate threshold range, it is determined that an abnormality has occurred for some reason, In step S6, it is determined that the current welding is defective.
Further, as a result of the comparison in step S4, it is determined that an abnormality has occurred for some reason even when the calculated rate of change in the applied pressure is outside the predetermined pressure change rate threshold range, In step S6, it is determined that the current welding is defective.
That is, if any one of the rate of change of the surface temperature of the welded portion, the rate of change of the welding voltage, and the rate of change of the applied pressure is outside the predetermined change rate threshold range, welding is performed. It is determined to be defective.

  FIG. 4 shows an example of measurement of the surface temperature and welding voltage of the welded part when lap seam welding is actually performed using the lap seam welder shown in FIG. In FIG. 4, the horizontal axis indicates the position in the width direction of the metal strips 1 and 2, the waveform Wt indicates the measured surface temperature, and the waveform Wv indicates the measured welding voltage. FIG. 4 also shows a temperature threshold range Rtm representing the surface temperature of the welded portion and a voltage threshold range Rvm representing the welding voltage when normal welding is performed. These temperature threshold range Rtm and voltage threshold range Rvm can be obtained based on past results.

  As can be seen from FIG. 4, at the width direction position P1, the waveform Wt falls below the temperature threshold range Rtm, and the measured value of the surface temperature is outside the temperature threshold range Rtm. That is, normal welding cannot be performed, and there is a high possibility that defective welding has occurred. However, the waveform Wv of the welding voltage is within the voltage threshold range Rvm, and the occurrence of welding failure at the width direction position P1 cannot be recognized from the measured value of the welding voltage.

  However, when the waveform Wv of the welding voltage at the position in the width direction is observed, the measured value of the welding voltage changes abruptly in the vicinity of the position P1 in the width direction, and the absolute value of the rate of change of the welding voltage in the metal band width direction is extremely large. It can be seen that it has increased. Therefore, as in the first embodiment described above, the change rate of the welding voltage calculated from the measured value of the welding voltage by the voltmeter 16 in step S3 of FIG. 3 is set to a predetermined voltage change rate threshold. By comparing with the value range, it is possible to determine from the measured value of the welding voltage that a welding failure has occurred in the vicinity of the position P1 in the width direction.

  As can be seen from the surface temperature waveform Wt, the measured value of the surface temperature also changes abruptly in the vicinity of the position P1 in the width direction. For this reason, in step S2 of FIG. 3, the surface temperature change rate calculated from the measured value of the surface temperature by the temperature sensor 15 is compared with a predetermined temperature change rate threshold range to obtain the surface temperature. From the measured values, it can be determined that a welding failure has occurred in the vicinity of the position P1 in the width direction.

  Further, the average value of the welding voltage in the metal band width direction D2 and the number of occurrences in a number of lap seam welding examples are shown in the graph of FIG. In this graph, the welding example E1 in which a welding failure has occurred is included in one of about 80 degrees representing the average value [−0.68 V]. However, the welding example E1 with poor welding cannot be identified from the graph of FIG.

  On the other hand, in the graph of FIG. 6 showing the rate of change of the welding voltage and the number of occurrences in the same number of lap seam welding examples as in FIG. 5, the welding example E1 in which the welding failure has occurred has an extremely large absolute value. It is included in one of the frequencies representing the voltage change rate [−32 V / s]. Moreover, it was confirmed that any welding failure occurred in any of the welding examples in which the absolute value of the voltage change rate was 30 V / s or more. Therefore, a voltage change rate threshold range Rvr in which the absolute value of the voltage change rate is smaller than 30 V / s is determined in advance, and the welding voltage is compared with the voltage change rate threshold range Rvr to obtain a welding voltage. It can be seen that the quality of the welding can be determined from the rate of change of. That is, when the change rate of the welding voltage is within the voltage change rate threshold range Rvr, it is determined that welding is good, and when it is outside the voltage change rate threshold range Rvr, it is determined that welding is poor. .

In addition, when the contact state between the two metal bands 1 and 2 in the overlapping portion 3 is locally deteriorated due to generation of wrinkles in the metal band, the electrical resistance between the front surface and the back surface of the overlapping portion 3 is reduced. The value increases and the surface temperature and welding voltage of the welded portion change abruptly. At this time, depending on the contact state between the two metal bands 1 and 2, the distance between the front surface and the back surface of the overlapping portion 3 is increased. The distance, that is, the thickness of the overlapping portion 3 changes locally, and the pressure device 9 is affected by the change in thickness, whereby the measured value of the pressure sensor 17 changes.
For this reason, in step S4 of FIG. 3, by comparing the rate of change of the applied pressure calculated from the measured value of the applied pressure by the applied pressure sensor 17, it is compared with a predetermined applied force change rate threshold range. It is possible to determine the occurrence of poor welding also from the measured value of the applied pressure.

In the first embodiment, the surface temperature of the welded portion of the overlapping portion 3 was measured by the temperature sensor 15, but from the rear of the electrode wheel 4 with respect to the traveling direction D3 of the electrode wheel 4, that is, in the vicinity of the welded portion. Even if the surface temperature in the vicinity of the contact portion between the electrode wheel 4 and the overlapping portion 3 is measured, the quality of the welding can be similarly determined.
Further, the surface temperature of the contact portion between the electrode wheel 4 and the overlapping portion 3 was measured by the temperature sensor 15 attached to the electrode wheel holding member 10 holding the electrode wheel 4, but the electrode wheel 5 was held. A temperature sensor 15 may be attached to the electrode wheel holding member 11 and the surface temperature at or near the contact point between the electrode wheel 5 and the overlapping portion 3 may be measured.

Embodiment 2
In the first embodiment described above, as shown in FIG. 3, the change rate of the surface temperature of the welded portion, the change rate of the welding voltage, and the change rate of the applied pressure are all predetermined changes. If the welding temperature is within the threshold range, it is determined that the welding is good. In addition, the measured values of the surface temperature, welding voltage, and applied pressure are set to the predetermined temperature threshold range and voltage threshold, respectively. The quality of welding can also be determined by taking into account the result of comparison with the value range and the pressure threshold range.

FIG. 7 is a flowchart showing the quality determination of welding in the welding quality determination apparatus according to the second embodiment. In addition, the welding quality determination apparatus according to the second embodiment has the same configuration as the welding quality determination apparatus 20 according to the first embodiment shown in FIG.
In the second embodiment, the welding quality determination unit 18 performs normal welding together with the temperature change rate threshold range, the voltage change rate threshold range, and the pressure change rate threshold range described above. In this case, the temperature threshold range representing the surface temperature of the welded portion of the overlapping portion 3, the voltage threshold range representing the welding voltage between the pair of electrode wheels 4 and 5, and the pair of electrode wheels 4 and 5 A pressure threshold value range representing the pressure is predetermined and stored. These temperature threshold value range, voltage threshold value range, and applied pressure threshold value range can be obtained based on past results.

Since steps S1 to S6 in FIG. 7 are the same as steps S1 to S6 in FIG. 3 in the first embodiment, detailed description thereof is omitted.
In step S1, the surface temperature of the welded portion of the overlapping portion 3, the welding voltage between the pair of electrode wheels 4 and 5, and the pressure applied by the pair of electrode wheels 4 and 5 are measured. In steps S2 to S4, welding is performed. The change rate of the surface temperature of the location is within a predetermined temperature change rate threshold range, the change rate of the welding voltage is within a predetermined voltage change rate threshold range, and the pressurizing force When the change rate is within the predetermined pressure change rate threshold range, the process further proceeds to step S7, and the measured value of the surface temperature of the welded portion of the overlapping portion 3 by the temperature sensor 15 is determined in advance. Compared to a defined temperature threshold range.

In step S7, when the measured value of the surface temperature of the welded portion is within a predetermined temperature threshold range, the process proceeds to step S8, and welding between the pair of electrode wheels 4 and 5 by the voltmeter 16 is performed. The voltage measurement is compared to a predetermined voltage threshold range.
In step S8, when the measured value of the welding voltage is within a predetermined voltage threshold range, the process further proceeds to step S9, and the measured value of the applied pressure by the applied pressure sensor 17 is determined in advance. It is compared with the applied pressure threshold range.
In step S9, when the measured value of the applied pressure is within a predetermined applied pressure threshold range, the surface temperature of the welding location, the welding voltage, and the applied pressure are all determined in advance. Since it is within the determined range, it is determined in step S5 that the current welding is good.

  On the other hand, when any one of the rate of change of the surface temperature of the welded portion, the rate of change of the welding voltage, and the rate of change of the applied pressure is outside the predetermined change rate threshold range in steps S2 to S4, Alternatively, in Steps S7 to S9, if any of the surface temperature, the welding voltage, and the applied pressure is outside the predetermined threshold range, it is determined that an abnormality has occurred for some reason, and Step In S6, it is determined that the current welding is defective.

That is, in the second embodiment, the rate of change in the surface temperature of the welding location, the rate of change in the welding voltage, the rate of change in the applied pressure, the measured value of the surface temperature of the welded location, the measured value of the welding voltage, and the measured value of the applied pressure Only when all of these are within the predetermined threshold range, it is determined that the welding is good, and if any one of them is out of the threshold range, it is determined that the welding is defective. The
Thus, not only the rate of change of the surface temperature of the welded portion, the rate of change of the welding voltage, and the rate of change of the applied pressure are compared with the predetermined change rate threshold range, but also the surface temperature, the welding voltage, By taking into account the result of comparing the measured pressure value with a predetermined threshold range, it is possible to more accurately determine the quality of welding in lap seam welding.

  1, 2 Metal strip, 1A Rear end, 2A Front end, 3 Overlap, 4, 5 Electrode wheel, 6 Carriage frame, 7 Upper arm, 8 Lower arm, 9 Pressure device, 10, 11 Electrode Wheel holding member, 12 welding power source, 13 moving device, 14 rail, 15 temperature sensor, 16 voltmeter, 17 pressure sensor, 18 welding quality judgment unit, 20 welding quality judgment device, D1 traveling direction of continuous line, D2 metal strip Width direction, D3 travel direction, Wt surface temperature waveform, Wv welding voltage waveform, Rtm temperature threshold range, Rvm voltage threshold range, Rvr voltage change rate threshold range, P1 width direction position, E1 welding Example.

Claims (4)

The overlapping portion of the metal band is pressed between a pair of electrode wheels, and the pair of electrode wheels are moved relative to the overlapping portion in a state where the pair of electrode wheels are energized. A method for determining whether or not a lap seam weld is welded.
Measure the surface temperature of the welded portion of the overlapping portion at the time of welding or the vicinity thereof, the voltage between the pair of electrode wheels, and the applied pressure by the pair of electrode wheels
When the change rate of the surface temperature calculated from the measured value of the surface temperature is outside a predetermined temperature change rate threshold range, or the change rate of the voltage calculated from the measured value of the voltage is determined in advance. When the voltage change rate threshold value is out of the range, or when the pressure change rate calculated from the measurement value of the pressure force is outside the predetermined pressure change rate threshold range, A method for determining the quality of welding in lap seam welding, characterized in that it is determined that welding is poor.   The rate of change of the surface temperature is within the temperature change rate threshold range, the rate of change of the voltage is within the voltage change rate threshold range, and the rate of change of the applied pressure is the rate of change of the applied pressure. Even if it is within the threshold range, the measured value of the surface temperature is outside the predetermined temperature threshold range, or the measured value of the voltage is outside the predetermined voltage threshold range. 2. The lap seam welding quality determination method according to claim 1, wherein the welding failure is determined when the measured value of the pressing force is outside a predetermined pressing force threshold range. The overlapping portion of the metal band is pressed between a pair of electrode wheels, and the pair of electrode wheels are moved relative to the overlapping portion in a state where the pair of electrode wheels are energized. A welding quality determination device for lap seam welding for welding,
A temperature sensor for measuring the surface temperature of the welded portion of the overlapped portion or its vicinity during welding; and
A voltmeter for measuring the voltage between the pair of electrode wheels during welding;
A pressure sensor for measuring the pressure applied by the pair of electrode wheels during welding;
When the change rate of the surface temperature calculated from the measured value of the surface temperature by the temperature sensor is outside a predetermined temperature change rate threshold range, or calculated from the measured value of the voltage by the voltmeter The rate of change of the applied voltage is outside a predetermined voltage change rate threshold range, or the rate of change of the applied pressure calculated from the measured value of the applied pressure by the applied pressure sensor is determined in advance. A welding quality judgment device for lap seam welding, comprising: a welding quality judgment unit that judges that welding is defective when the pressure change rate is out of a threshold range.   The welding pass / fail judgment unit has a rate of change of the surface temperature within the temperature change rate threshold range, a rate of change of the voltage within the voltage change rate threshold range, and a rate of change of the applied pressure. Is within the pressure change rate threshold range, but the measured value of the surface temperature by the temperature sensor is outside a predetermined temperature threshold range, or the voltage of the voltmeter When the measured value is outside the predetermined voltage threshold range, or when the measured value of the applied pressure by the applied pressure sensor is outside the predetermined applied pressure threshold range, The weld quality determination device for lap seam welding according to claim 3 for determination.