JP3705057B2 - Spot welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spot welding apparatus for joining, by spot welding, steel plates having a surface coating layer having a melting point lower than that of a base material, such as hot-dip galvanized steel plates and electrogalvanized steel plates.
[0002]
[Prior art]
At present, spot welding is widely used for welding steel sheets in various products using steel sheets. In these products, since mild steel sheets have been generally used as welded materials, there are few welding defects, and it has been possible to maintain the welding quality relatively stable by managing predetermined welding conditions. . However, in recent years, welded materials such as hot-dip galvanized steel sheets with improved rust prevention performance have been mainly used, and welding quality control is caused by the occurrence of poor welding due to wear of welding electrode tips. Has become a problem. Therefore, in spot welding, it is necessary not only to manage welding conditions uniformly, but also to manage the quality of the nugget generated in the welded portion, which changes for each hit point, with high accuracy.
[0003]
In response to these problems, various methods have been devised, particularly for managing the quality of the nugget. For example, in the method disclosed in Japanese Patent Laid-Open No. 56-158286, the welding current and welding voltage between welding electrode tips are measured to obtain the resistance between the tips, and the quality of the welding result is judged from the pattern of the change. Japanese Patent Laid-Open No. 54-21938 discloses a method for comparing the welding current or welding voltage with a temporal change of a reference voltage set in advance and judging whether the difference between the two is within an allowable value. Has been. Furthermore, Japanese Patent Laid-Open No. 9-206958 discloses a method for predicting a nugget formation state from a change in resistance value by passing a measurement current between welding electrode tips separately from the welding current and measuring the resistance between the electrodes. .
[0004]
In these conventional methods, it is necessary to conduct a preliminary experiment for each welding material to obtain the relationship between the nugget quality and the judgment criterion in advance, and not only the type of welding material but also the state of the welding surface such as rust and dirt. In addition, a change in resistance between electrode tips due to wear and deformation of the welding electrode tips must be taken into consideration. However, in preliminary experiments at actual welding sites, it is difficult to estimate uncertain events such as resistance changes between welding electrode tips, so there are many preliminary tests to use these uncertainties as criteria. It is necessary to conduct an experiment. Moreover, the criterion obtained from the result of the preliminary experiment has a problem that basically, one criterion can be applied only to one kind of material to be welded. Therefore, in order to avoid welding defects, excessive welding conditions must be set, and welding power is reduced, welding electrode wear is reduced, and the metal melted at the welding point, which is called “scattering,” is scattered. It is difficult to prevent such a phenomenon.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to propose a spot welding apparatus that solves the above-mentioned problems and can easily and accurately determine the quality of the welding state, thereby enabling appropriate management of the nugget quality. is there.
[0006]
[Means for Solving the Problems]
The present invention has a surface coating layer having a melting point lower than that of the base material on at least one of the overlapping surfaces of the steel plates. While pressing the stacked steel plates with the opposing electrode tips, the electrode tips are energized for resistance heating. In a spot welding apparatus that performs welding by means of, the electrode vibration detection means for detecting the vibration of the electrode tip that occurs during welding, and the vibration generated at the initial stage of welding detected by the electrode vibration detection means are generated at the welding location. Welding quality judgment means for judging quality of welding by judging quality of nuggets is provided.
[0007]
The inventor of the present application pays attention to vibration generated in the electrode tip at the initial stage of welding in spot welding of a steel material having a surface coating layer having a melting point lower than that of the base material, such as a hot dip galvanized steel sheet. From the relationship, the present invention has been found.
[0008]
The spot welding apparatus according to the present invention detects vibration generated in the electrode tip in the initial stage of welding, and thereby determines the quality of the nugget generated at the welding location. That is, since the quality of welding can be determined at the initial stage of welding start, not only the quality of the nugget is judged, but even if the nugget formation is bad at that time, this nugget is finally made good It becomes possible to control welding.
[0009]
In the spot welding apparatus according to the present invention, when determining the quality of welding, the amplitude of vibration or the time of occurrence of vibration is detected, and when the amplitude of vibration is equal to or greater than a predetermined threshold, or the time of occurrence of vibration. Is determined to be that good welding has been performed when it is before a predetermined time from the start of energization of the electrode tip. In any case, it is possible to determine whether the welding is in the initial stage.
[0010]
The spot welding apparatus according to the present invention determines whether or not the vibration occurrence time is before a predetermined scattering occurrence limit time, and the vibration occurrence time is before the scattering occurrence limit time. In this case, it is further characterized by further comprising a scatter occurrence prediction means for determining that scatter occurs at the welded portion, that is, scatter of the molten metal material, and outputs a warning signal for occurrence of scatter. Thereby, it is possible to predict in advance the occurrence of scattering at the welded portion, and this can be effectively suppressed.
[0011]
Further, the spot welding apparatus according to the present invention promotes welding when the amplitude of the vibration does not reach a predetermined pass / fail judgment threshold value or when the occurrence time of the vibration occurs later than the predetermined pass / fail judgment time. It further comprises compensation control command output means for outputting a command and outputting a welding stop command when the occurrence of the scattering is detected. As a result, even if the nugget formation is poor, it is possible to perform welding control for improving the quality of the nugget, and to secure desired welding quality while suppressing the occurrence of scattering that leads to deterioration of the rust prevention performance. It becomes possible.
[0012]
Furthermore, the spot welding apparatus according to the present invention is characterized by further comprising welding adjustment command output means for judging whether or not welding is good from the time of occurrence of the vibration and suppressing the occurrence of scattering. Thereby, it becomes possible to determine the excess or deficiency of the welding in the initial stage of the welding operation, and it becomes possible to ensure the desired welding quality with a small amount of electric power.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a block diagram showing a configuration of a spot welding apparatus according to the present invention. The spot welding apparatus 10 amplifies the primary current controlled by the welding control circuit 11 and the welding control circuit 11 for controlling the welding current, energization time and energization timing to a secondary current (welding current) value necessary for welding. Welding transformer 12, welding current detection transformer 13 for detecting the current for controlling the welding current, welding electrodes 14a and 14b are superposed on each other, welding electrodes 14a and 14b are superposed, sandwiched between them, and a welding current is passed while pressing Tips 15 and 16, welding gun arms 17 and 18 to which these welding electrode tips are attached, and air cylinders for driving the welding gun arms 17 and 18 so as to sandwich and pressurize the workpieces 14a and 14b with the welding electrode tips 15 and 16 With 19
[0015]
The spot welding apparatus 10 further inputs a vibration sensor 20 for detecting vibration generated in the welding electrode tip attached to the welding gun arm during welding and a signal (voltage value) detected by the vibration sensor 20 for welding. A welding pass / fail judgment circuit 21 for judging pass / fail of the state is provided. A command signal based on the input signal from the vibration sensor 20 is fed back to the welding control circuit 11 from the welding pass / fail judgment circuit 21. Thereby, control of welding current or energization time (welding in-process control) is performed.
[0016]
FIG. 2 shows a waveform of vibration generated in the welding electrode tip during welding, which is detected here during welding of the galvannealed steel sheets. As shown in the figure, a burst-like vibration waveform is seen in each of the early and late stages of welding. Here, the burst wave generated at the initial stage of welding is referred to as a first wave, and the burst wave generated at the latter stage is referred to as a second wave. In the present invention, the first wave is used as a signal for determining the quality of the nugget, and the second wave is used as a signal for detecting the occurrence of scattering. Such burst vibration is lower than that of the base metal such as electrogalvanized steel sheet, hot dip galvanized steel sheet, lead-tin alloy plated steel sheet, zinc powder plated steel sheet, and aluminum plated steel sheet in addition to the galvannealed steel sheet. It is found in various steel sheets having a surface coating layer with a melting point.
[0017]
In spot welding of a steel sheet having a surface coating layer having a melting point lower than that of the base material, the burst vibration as described above is considered to occur due to the following reasons. That is, since the melting point of the plating material is generally lower than that of the base material (for example, about 420 ° C. with zinc), when the dissolution of the plating layer starts during welding, the dissolved plating material is welded by the pressure from the electrode tip. Extruded to the outer periphery of the nugget formed in step (b), the plating layer becomes thinner by the amount of the extruded plating material. Therefore, the electrode tips move in the pressurizing direction, that is, the electrode tips on both sides of the material to be welded approach each other. When the dissolution / outflow of the plating material further proceeds, the base material is exposed at the nugget forming portion and comes into contact with each other. However, since the base material temperature at this time has not yet reached its melting point, the rate of change in the plate thickness of the steel sheet is rapidly reduced. As a result, the movement of the electrode tip stops, and the burst-like vibration waveform (first wave) as described above is generated.
[0018]
Next, the relationship between the second wave and the occurrence of scattering is considered as follows. Here, scattering refers to a phenomenon in which melted metal scatters because welding conditions are excessive due to dirt or irregularities on the surface of the material to be welded during welding, lack of pressurization by electrode tips, and the like. More specifically, in the initial stage of nugget growth, the internal pressure of the molten pool is not so large, so the molten metal stays in the molten pool, but when the internal pressure of the molten pool increases as the nugget grows, the molten metal Are scattered between the materials to be welded. The occurrence of this scattering, i.e., the scattering of the molten metal, causes the thickness of the welded portion to rapidly decrease. As a result, a burst-like vibration waveform is generated.
[0019]
FIG. 3 is a block diagram showing details of a welding pass / fail judgment circuit of the spot welding apparatus according to the first embodiment of the present invention. The illustrated welding quality determination circuit 21 determines the quality of welding by measuring the amplitude of the first wave described above. A welding pass / fail judgment circuit 21 sets a pressure electrode vibration detection unit 201 that converts a detection signal from a vibration sensor 20 (see FIG. 1) attached to a welding gun arm into a voltage signal for judgment, and a pass / fail judgment threshold value. A pass / fail judgment threshold setting unit 202, a comparison unit (voltage comparator) 203 that compares the detected vibration amplitude with the pass / fail judgment threshold, and a first wave when a nugget that passes the pass / fail judgment result is formed. The timer 204 that gives the detected time range as the timing for comparison, the timing for comparison is obtained from the timer 204, and based on the comparison result between the vibration amplitude and the pass / fail judgment threshold value from the comparison unit 203 described above. Compensation for outputting a welding acceleration command or a welding stop command to the welding control circuit 11 (see FIG. 1) based on the quality determination result output from the quality determination unit 205 and the quality determination unit 205 for determining the quality of the welding state It comprises a control command output section 206.
[0020]
In the pass / fail judgment circuit 21 of FIG. 3, the vibration waveform detected by the vibration sensor 20 is compared with a predetermined threshold value (set value) in the comparison unit 203, and as a result, the pass / fail judgment unit 205 exceeds the set value. In this case, it is determined that the welding is acceptable, and when it is less than the set value, it is determined as unacceptable. Therefore, in the spot welding apparatus 10 according to the present invention, the quality determination of the welding state is performed before the nugget formation, and even if a welding failure occurs, an in-process for immediately compensating for this as described later Control can be done.
[0021]
Next, compensation control when a welding failure occurs in the spot welding apparatus including the above-described pass / fail judgment circuit 21 will be described. First, when the quality determination unit 205 that has received a signal from the comparison unit 203 determines a welding failure, the quality determination unit 205 transmits a signal for instructing welding promotion to the compensation control command output unit 206. Upon receiving the welding promotion signal, the compensation control command output unit 206 outputs the welding promotion command signal to the welding control circuit 11 (see FIG. 1). The welding control circuit 11 performs welding control based on the welding conditions for promoting nugget formation such as increasing the welding current in accordance with the welding acceleration command signal.
[0022]
However, since the energy for welding becomes excessive in this state, there is a possibility that scattering occurs with nugget formation under the above-described conditions. Therefore, the sensor 20 detects the second wave indicating the occurrence of scattering, and the compensation control command output unit 206 outputs a welding stop command signal to the welding control circuit 11 based on this detection signal. Upon receiving the welding stop command signal, the welding control circuit 11 immediately stops the energization of the welding current to the electrode tip.
[0023]
Based on the above results, the nugget that was initially determined to be defective can be finally given a quality of acceptable level. In the welding pass / fail judgment circuit 21 of FIG. 3, the vibration that occurs when the welding electrode arms 19 and 18 are moved and the workpiece 14 is pressed and sandwiched in the pressure electrode vibration detector 201 is a vibration during welding ( That is, a filter circuit is provided to prevent erroneous detection as the first wave or the second wave, or, as shown in FIG. By performing a mask process for removing vibrations that occur outside of the generated time (approximately 0.2 seconds from the start of energization), it is possible to detect burst-like vibrations during welding with higher accuracy.
[0024]
FIG. 4 shows the relationship between the nugget diameter formed at the weld location and the maximum amplitude of the first wave. In this figure, a galvannealed steel sheet is taken as an example. In the example shown in the figure, the nugget when the maximum amplitude of the first wave is 0.2 V or more (indicated by the voltage value of the vibration sensor 20) leads to a plug fracture indicating that all have sufficient welding strength, and the acceptable diameter. It is shown that it is 4 mm or more. Accordingly, when welding a galvannealed steel sheet with a spot welding apparatus having the pass / fail judgment circuit 21 shown in FIG. 3, the pass / fail judgment threshold may be set to 0.2V. Needless to say, this threshold value is obtained in advance for various types of steel plates by preliminary experiments or the like.
[0025]
Next, FIG. 5 is a block diagram showing details of a welding pass / fail judgment circuit of the spot welding apparatus according to the second embodiment of the present invention. The illustrated welding quality determination circuit 21 determines the quality of welding by measuring the generation time of the first wave described above. The welding pass / fail judgment circuit 21 sets the pressure electrode vibration detector 211 for converting the detection signal from the vibration sensor 20 (see FIG. 1) attached to the welding gun arm into a voltage signal for judgment, and a pass / fail judgment threshold value. In response to the energization start signal from the pass / fail judgment threshold setting unit 212, the comparison unit 213 that compares the detected vibration amplitude with the pass / fail judgment threshold, and the control circuit 11 (see FIG. 1), welding from the start of energization is performed. It includes a time counter 214 for accumulating time, a pass / fail judgment unit 215 for judging pass / fail of the welding state, and a pass / fail judgment time setting unit 216 for setting a time range in which the first wave is generated when an acceptable nugget is formed.
[0026]
The pass / fail judgment unit 215 obtains the first wave detection signal from the comparison unit 213, and compares the value in the time counter 214 at that time with the set value in the pass / fail judgment time setting unit 216, thereby determining the welding state. Judge the quality. That is, the time of occurrence of the first wave is measured from the vibration detected by the vibration sensor 20, and when the time is at the pass / fail judgment time, it is determined as pass, and the other is determined as fail. As a result, whether the welding state is good or bad is determined at the initial stage of welding in which the first wave is generated.
[0027]
In the welding pass / fail judgment circuit 21 in FIG. 5, similarly to the circuit in FIG. 3, a compensation control command output unit that outputs a welding acceleration command and a welding stop command based on the output from the pass / fail judgment unit 215 may be provided. It goes without saying that it is good.
[0028]
FIG. 6 shows the relationship between the first wave generation time and the nugget diameter. This figure also takes a galvannealed steel sheet as an example. In the example shown in the drawing, it can be seen that the nugget formed when the first wave is generated within 0.08 sec from the start of energization has reached the acceptable diameter of 4 mm or more. Thus, when welding a galvannealed steel sheet with a spot welding apparatus having the pass / fail judgment circuit 21 shown in FIG. 5, the pass / fail judgment time range may be set to 0.08 sec from the start of energization. . In this case as well, the pass / fail judgment set time is obtained in advance for various steel plates through preliminary experiments or the like. In order to obtain the first wave generation time here, as shown in FIG. 4, the first wave generation is performed at the time when the vibration amplitude first reaches a threshold value (0.2 V) from the time of energization of the welding current. If the first wave generation time is determined when a predetermined voltage value that has passed through the filter circuit is obtained using a filter circuit (not shown), both the vibration amplitude and the generation time of the first wave can be determined. As a result, a better judgment can be made.
[0029]
FIG. 7 is a block diagram showing details of a welding pass / fail judgment circuit of the spot welding apparatus according to the third embodiment of the present invention. The welding pass / fail judgment circuit 21 shown in the drawing determines whether or not the occurrence time of burst-like vibration is earlier than a predetermined scattering occurrence limit time, and the occurrence time of the burst-like vibration is more than the scattering occurrence limit time. If it is before, it is determined that scattering occurs at the welded portion. Similar to the embodiment shown in FIG. 5, the welding pass / fail judgment circuit 21 is a pressure electrode vibration detector 221 that converts a detection signal from the vibration sensor 20 attached to the welding gun arm into a voltage signal for judgment. The pass / fail judgment threshold setting unit 222 for setting the judgment threshold, the comparison unit 223 for comparing the detected vibration amplitude with the pass / fail judgment threshold, and the energization start signal from the control circuit 11, It includes a time counter 224 for integrating the welding time, a pass / fail judgment unit 225 for judging pass / fail of the welding state, and a pass / fail judgment time setting unit 226 for setting a time range in which the first wave is generated when the acceptable nugget is formed. Further, the welding quality determination circuit 21 further includes a scattering prediction unit 227, a scattering occurrence limit time setting unit 228, and a welding adjustment command unit 229.
[0030]
The scatter prediction unit 227 compares the scatter occurrence limit time set in advance by the scatter occurrence limit time setting unit 228 with the occurrence time of the first wave input from the time counter 224. At this time, if the occurrence time of the first wave is before the scatter occurrence limit time, it is determined that scatter occurs at the current welding location, and if it is after the scatter occurrence limit time, the current welding location is determined. Then, it is determined that no scattering occurs. This makes it possible to predict the occurrence of scattering before the scattering actually occurs. Note that this determination result can be fed back to the welding control circuit 11, for example, to contribute to control for preventing the occurrence of scattering such as an increase in the pressure applied to the electrode tip, a decrease in the welding current, and an energization stop.
[0031]
On the other hand, the welding adjustment command unit 229 includes a determination result of the quality of welding based on the generation time of the first wave in the quality determination unit 225, a result of scattering prediction based on the time of occurrence of the first wave in the scattering prediction unit 227, and a time counter. It is determined whether or not welding is sufficient from the generation time of the first wave from 224, and a command (welding adjustment command) for adjusting the welding control amount is output to correct this. Here, when it is determined that the welding is defective in the determination result of the welding quality, the welding adjustment command unit 229 refers to the value from the time counter 224 and measures the degree of welding failure. As a result, if the formation of the acceptable nugget can be realized within a range where the welding control can be adjusted, the adjustment amount is output to the welding control circuit 11 as a welding adjustment command output signal.
[0032]
Even if the nugget formed at the weld location is determined to be acceptable, the value from the time counter 224 is used to determine whether the welding is sufficient, and more appropriate welding conditions according to the result. Such an adjustment amount may be output to the welding control circuit 11 as a welding adjustment command output signal.
[0033]
Further, when it is determined that the occurrence of scattering is predicted by the scattering prediction unit 227, a welding adjustment command output signal for suppressing scattering is welded while securing the welding energy necessary for forming a passing nugget. Output to the control circuit 11.
[0034]
FIG. 8 shows the relationship between the generation time of the first wave and the second wave and the scattering generated on the overlapped surfaces of the workpieces. This figure also takes a galvannealed steel sheet as an example. In the example shown in the figure, it is shown that the second wave is generated, that is, scattered when the first wave is generated earlier than 0.045 sec from the start of energization. Here, when the generation of the first wave occurs earlier than 0.045 sec from the start of energization, the point where the scattering occurs will be described in detail. For example, when the molten alloyed galvanized steel sheet has irregularities or the like, Since the contact area becomes small (when viewed microscopically), the current density flowing through these steel plates per unit pressing area becomes high. Then, the temperature becomes higher than the temperature necessary for nugget formation, so-called boiling state occurs, and the molten metal scatters. In addition, in the case where dust or the like is attached, in addition to the increase in the current density, the resistance value due to the electric insulation effect due to the dust becomes excessive, and this also promotes a high temperature. In particular, in the case of a surface coating layer having a melting point lower than that of the base material (for example, zinc and a melting point of about 420 ° C.), it becomes boiled as soon as the temperature rises (faster than 0.045 sec from the start of energization) and starts to scatter. The occurrence of scattering during the subsequent nugget formation can be determined from the first burst wave due to the melting of the surface coating layer. As a result, when welding a galvannealed steel sheet with a spot welding apparatus having the pass / fail judgment circuit 21 shown in FIG. 7, the scatter occurrence limit time may be set to 0.045 sec from the start of energization. . In this case as well, it is needless to say that the scattering occurrence limit time is obtained in advance for various steel plates by a preliminary experiment or the like.
[0035]
As described above, according to the spot welding apparatus according to the present invention, attention is paid to burst-like vibration generated in the electrode tip in the initial stage of welding, and based on the relationship between the vibration and the occurrence of the nugget diameter and scattering, It is possible to perform welding control that suppresses formation and scattering and obtains good welding quality.
[0036]
The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications within the scope of the present invention are possible. In particular, the present invention is also applicable to welding of various steel plates having a surface coating layer having a melting point lower than that of the base material, or steel plates having a surface coating layer having a low melting point and a steel plate not having the surface coating layer. Is possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a spot welding apparatus according to the present invention.
FIG. 2 is a diagram showing a vibration waveform generated in an electrode tip during welding.
FIG. 3 is a block diagram showing details of a welding pass / fail judgment circuit of the spot welding apparatus according to the first embodiment of the present invention.
FIG. 4 is a graph showing the relationship between the nugget diameter formed at the weld location and the maximum amplitude of the first wave.
FIG. 5 is a block diagram showing details of a welding pass / fail judgment circuit of the spot welding apparatus according to the second embodiment of the present invention.
FIG. 6 is a graph showing the relationship between the first wave generation time and the nugget diameter.
FIG. 7 is a block diagram showing details of a welding pass / fail judgment circuit of a spot welding apparatus according to a third embodiment of the present invention.
FIG. 8 is a graph showing the relationship between the generation time of the first wave and the second wave and the scattering generated on the overlapping surfaces of the workpieces.
[Explanation of symbols]
10 Spot welding equipment
11 Welding control circuit
12 Welding transformer
13 Welding current detection transformer
14 Welded materials
15, 16 electrode tip
17, 18 Welding gun arm
19 Air cylinder
20 Vibration sensor
21 Welding pass / fail judgment circuit
201, 211, 221 Pressurized electrode vibration detector
202, 212, 222 Pass / fail judgment threshold setting section
203, 213, 223 comparison part
204 timer
205, 215, 225 Pass / fail judgment part
206 Compensation control output section
214, 224 time counter
216,226 Pass / fail judgment time setting part
227 Splash prediction section
228 Splash generation limit time setting section
229 Welding adjustment command section

Claims (5)

At least one of the overlapping surfaces of the steel plates has a surface coating layer having a melting point lower than that of the base material. While pressing these stacked steel plates with the opposing electrode tips, the electrode tips are energized and resistance heating is performed. In spot welding equipment,
Electrode vibration detecting means for detecting vibration of the electrode tip generated during welding;
Welding pass / fail judgment means for judging pass / fail of welding by judging pass / fail of the nugget generated at the weld location from the vibration generated in the initial stage of welding detected by the electrode vibration detecting means,
The equipped,
The welding quality determination means determines the quality of welding based on the amplitude of the vibration or the generation time of the vibration,
Determining that good welding has been performed when the amplitude of the vibration is equal to or greater than a predetermined threshold value, or when the generation time of the vibration is before a predetermined time has elapsed from the start of energization of the electrode tip. Spot welding equipment characterized by. The apparatus of claim 1.
It is determined whether or not the vibration occurrence time is before a predetermined scattering occurrence limit time, and if the vibration occurrence time is before the scattering occurrence limit time, the vibration is scattered at the welding location. A spot welding apparatus, further comprising a scattering occurrence predicting unit that determines that the occurrence of scattering occurs and outputs a warning signal of occurrence of scattering. The apparatus according to claim 1 or 2,
Compensation control command output means for outputting a welding promotion command when the amplitude of the vibration does not reach a predetermined pass / fail judgment threshold and outputting a welding stop command when the occurrence of scattering is detected is further provided. A spot welding apparatus characterized by that. The device according to any one of claims 1 to 3,
Compensation control command output means for outputting a welding promotion command when the vibration occurrence time occurs later than a predetermined pass / fail judgment time, and outputting a welding stop command when the occurrence of scattering is detected A spot welding apparatus characterized by comprising. The device according to any one of claims 1 to 4,
A spot welding apparatus, further comprising welding adjustment command output means for determining whether or not welding is good from the vibration occurrence time and suppressing the occurrence of scattering.

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