Welding quality evaluation apparatus, welding quality evaluation program, and welding quality evaluation method

Abstract

To provide a welding quality evaluation device enabling improvement of accuracy of determination of defect in resistance welding.SOLUTION: An aspect of the present disclosure is a welding quality evaluation device for use in a resistance welder that welds a workpiece by applying current between a first electrode and a second electrode while pressurizing the workpiece with the first electrode and the second electrode. The welding quality evaluation device comprises: a displacement amount acquisition unit acquiring a displacement amount of the first electrode relative to the second electrode; a current acquisition unit acquiring the magnitude of welding current flowing between the first electrode and the second electrode; and a determination unit determining the presence or absence of welding defect by comparing time-series data of the amount of displacement before the start of supply of the welding current or after the end of supply of the welding current with reference data prepared in advance.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present disclosure relates to a welding quality evaluation apparatus, a welding quality evaluation program, and a welding quality evaluation method.

Background Art

[0002] In resistance welding, where a workpiece (i.e., the material to be welded) is welded by applying pressure with two electrodes and supplying current, defects can occur in the welding due to various factors such as disturbances. Therefore, several methods for determining the welding quality by monitoring the displacement amount of the electrodes (i.e., distortion or pressing force) have been devised (see Patent Documents 1 - 4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

[0007] The welding quality evaluation device includes a displacement acquisition unit configured to acquire the amount of displacement of the first electrode relative to the second electrode, a current acquisition unit configured to acquire the magnitude of the welding current flowing between the first electrode and the second electrode, and a determination unit configured to determine whether or not there is a welding defect by comparing time-series data of the displacement amount before the start of welding current supply or after the end of welding current supply with pre-prepared reference data.

[0008] With this configuration, by comparing time-series data of displacement before and after energization with reference data, defects that cannot be determined from the displacement during energization (e.g., disturbances, welding defects, etc.) can be identified. As a result, the accuracy of defect detection in resistance welding can be improved.

[0009] In one aspect of this disclosure, the determination unit may be configured to determine the presence or absence of gaps in the workpiece based on the difference between the rate of increase of displacement before the start of welding current supply and a reference rate included in the reference data. With such a configuration, it is possible to detect the presence or absence of gaps between plates constituting the workpiece. As a result, defects caused by the workpiece can be detected.

[0010] In one aspect of this disclosure, the determination unit may be configured to determine the size of the gap in the workpiece based on the difference between the timing of the start of the increase in displacement before the start of welding current supply and the timing of the start of the increase in displacement included in the reference data. With such a configuration, in addition to detecting the gap in the workpiece, its size can be determined.

[0011] In one aspect of this disclosure, the determination unit may be configured to determine whether the applied pressure at the start of welding is appropriate based on a comparison between the change in displacement per unit time before the start of welding current supply and a first reference value included in the reference data, and a comparison between the displacement at the start of welding current supply and a second reference value included in the reference data. With such a configuration, insufficient and unstable applied pressure can be detected. As a result, malfunctions caused by the resistance welding machine can be detected.

[0012] In one aspect of this disclosure, the determination unit may be configured to determine whether or not the first electrode or the second electrode is sticking to the workpiece based on a comparison of the rebound amount of the displacement after the supply of welding current is stopped with a reference amount included in the reference data. With such a configuration, it is possible to detect over-welding due to overheating. As a result, it is possible to detect setting problems such as the amount of current supplied.

[0013] In one aspect of this disclosure, the determination unit may be configured to determine the presence and magnitude of spatter based on a comparison of time-series data of the load on the workpiece during the supply of welding current with reference data. With such a configuration, defects caused by spatter generation during welding can be detected. As a result, defects caused by welding conditions can be detected.

[0014] In one aspect of this disclosure, the determination unit may be configured to determine a faulty current supply based on a comparison of time-series data of the load on the workpiece during the supply of welding current with reference data. With such a configuration, it is possible to detect malfunctions caused by faulty current supply during welding. As a result, it is possible to detect malfunctions caused by the resistance welding machine.

[0015] Another aspect of this disclosure is a welding quality evaluation program used in resistance welding, in which a workpiece is welded by current flowing between a first electrode and a second electrode while the workpiece is pressurized by the first electrode and the second electrode.

[0016] The welding quality evaluation program causes a computer to obtain the amount of displacement of the first electrode with respect to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode, and to determine the presence or absence of welding defects by comparing the time-series data of the amount of displacement before the start of supply of the welding current or after the end of supply of the welding current with reference data prepared in advance.

[0017] Another aspect of the present disclosure is a welding quality evaluation method in resistance welding in which a work is welded by energization between a first electrode and a second electrode while pressing the work with the first electrode and the second electrode. The welding quality evaluation method includes a step of obtaining the amount of displacement of the first electrode with respect to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode, and a step of determining the presence or absence of welding defects by comparing the time-series data of the amount of displacement before the start of supply of the welding current or after the end of supply of the welding current with reference data prepared in advance.

[0018] According to such a configuration, the determination accuracy of defects in resistance welding can be improved.

Brief Description of the Drawings

[0019] [Figure 1] FIG. 1 is a block diagram schematically showing the configuration of a welding control device in an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a resistance welder in an embodiment. [Figure 3] FIG. 3 is a graph showing an example of time-series data of the amount of displacement and the welding current. [Figure 4] FIG. 4 is a graph showing an example of time-series data of the amount of displacement and the welding current. [Figure 5] FIG. 5 is a graph showing an example of time-series data of the amount of displacement and the welding current. [Figure 6] FIG. 6 is a flowchart of a welding quality evaluation method in an embodiment.

Modes for Carrying Out the Invention

[0020] Embodiments to which this disclosure applies will be described below with reference to the drawings. [1. First Embodiment] [1-1. Structure] The welding control device 1 shown in Figure 1 is used to control the resistance welding machine 10.

[0021] <Resistance welding machine> As shown in Figure 2, the resistance welding machine 10 resistance welds a first plate P1 and a second plate P2, which are arranged as a workpiece W, in the thickness direction. The workpiece W has a first plate P1 and a second plate P2 on which the first plate P1 is superimposed from above.

[0022] The resistance welding machine 10 comprises a first electrode 11, a second electrode 12, a support part 13, a motor 14, a transmission body 15, a strain sensor 16, and an encoder 17. The first electrode 11, the second electrode 12, and the support part 13 constitute a welding gun 18.

[0023] The first electrode 11 is positioned above the workpiece W. The second electrode 12 is positioned below the workpiece W, together with the first electrode 11, so as to sandwich the workpiece W in the thickness direction. The first electrode 11 and the second electrode 12 each come into contact with the workpiece W during welding.

[0024] A welding current supplied from the welding control device 1 flows through the workpiece W between the first electrode 11 and the second electrode 12. The resistance welding machine 10 pressurizes the workpiece W with the first electrode 11 and the second electrode 12, and welds the workpiece W by energizing the first electrode 11 and the second electrode 12.

[0025] The support portion 13 is a gun yoke that supports the second electrode 12. The second electrode 12 protrudes upward from the tip of the support portion 13. The support portion 13 holds the second electrode 12 in a fixed position (i.e., height).

[0026] The motor 14 rotates the transmission body 15, thereby moving the first electrode 11 vertically relative to the second electrode 12. In other words, the motor 14 changes the distance between the first electrode 11 and the second electrode 12 by moving the first electrode 11 vertically.

[0027] Furthermore, the motor 14 adjusts the pressure applied to the workpiece W by the first electrode 11 and the second electrode 12 (i.e., the welding pressure of the resistance welding machine 10) by changing the distance between the first electrode 11 and the second electrode 12.

[0028] The transmission element 15 converts the rotational motion of the motor 14 into vertical linear motion of the first electrode 11. For example, a ball screw can be used as the transmission element 15. The strain sensor 16 is attached to the support part 13. The strain sensor 16 is configured to measure the strain generated in the support part 13 when the welding gun 18 is pressurized. For example, a piezoelectric sensor, a strain gauge, etc., can be used as the strain sensor 16.

[0029] The encoder 17 outputs the amount of rotation of the motor 14. Specifically, the encoder 17 outputs the amount of rotation of the motor 14 as the number of pulses to the welding control device 1. The encoder 17 may output the amount of rotation of the motor 14 directly to the welding control device 1, or it may output the amount of rotation of the motor 14 to the welding control device 1 via a robot controller (not shown) provided in the resistance welding machine 10.

[0030] The amount of rotation of the motor 14 is correlated with the vertical position (i.e., height) of the first electrode 11. In particular, when the transmission body 15 is a ball screw, there is a linear relationship between the amount of rotation of the motor 14 and the displacement of the first electrode 11.

[0031] <Welding control device> The welding control device 1 shown in Figure 1 is electrically connected to the resistance welding machine 10 and is configured to control the resistance welding machine 10.

[0032] The welding control device 1 is composed of, for example, a computer that includes a processor, a storage medium such as RAM or ROM, and an input / output unit. The welding control device 1 also includes a control unit 2 and a welding quality evaluation device 3.

[0033] The computer constituting the welding control device 1 executes the functions of the welding quality evaluation device 3 using a welding quality evaluation program stored on a storage medium. In other words, the welding quality evaluation program causes the computer to acquire the displacement amount and the magnitude of the welding current, and to determine whether or not there are welding defects.

[0034] (Control Unit) The control unit 2 adjusts the current supplied to the welding gun 18 of the resistance welding machine 10. Specifically, the control unit 2 is a timer that controls the magnitude, start time, and end time of the welding current supplied between the first electrode 11 and the second electrode 12.

[0035] (Welding quality evaluation device) The welding quality evaluation device 3 includes a displacement acquisition unit 31, a current acquisition unit 32, a determination unit 33, and an output unit 34.

[0036] (Displacement amount acquisition unit) The displacement amount acquisition unit 31 is configured to acquire the displacement amount of the first electrode 11 relative to the second electrode 12.

[0037] Specifically, the displacement acquisition unit 31 detects the displacement of the distance between the first electrode 11 and the second electrode 12 based on the rotational position of the motor 14 and the strain of the support unit 13 output by the strain sensor 16.

[0038] The rotational position of the motor 14 is output directly from the encoder 17 of the resistance welding machine 10, or via the robot controller. When the first electrode 11 moves in the vertical direction, the motor 14 rotates via the transmission body 15. The displacement acquisition unit 31 acquires the rotational amount of the motor 14 from the encoder 17 and calculates the displacement of the position of the first electrode 11 by using a function between the rotational amount of the motor 14 and the position of the first electrode 11.

[0039] Furthermore, when the second electrode 12 is pushed down due to expansion of the workpiece W, strain occurs in the support portion 13. The displacement acquisition unit 31 acquires the strain of the support portion 13 from the strain sensor 16 and calculates the displacement of the second electrode 12 by using a function between the strain of the support portion 13 and the position of the second electrode 12.

[0040] Furthermore, as a means for detecting strain in the support portion 13, a mechanical displacement meter, a laser displacement meter, an AE (acoustic emission) sensor, an ultrasonic sensor, etc. may be used instead of the strain sensor 16, or in addition to the strain sensor 16.

[0041] The displacement acquisition unit 31 detects the distance between the first electrode 11 and the second electrode 12 by adding the displacement of the first electrode 11 and the displacement of the second electrode 12. The displacement acquisition unit 31 also continuously detects the distance between the electrodes from the start to the end of welding.

[0042] The displacement acquisition unit 31 acquires the displacement of the first electrode 11 relative to the second electrode 12 from before the start of welding (i.e., before the start of welding current supply) until after the end of welding (i.e., after the end of welding current supply). In this way, the displacement acquisition unit 31 acquires the displacement not only during welding but also when no welding current is flowing.

[0043] The displacement acquisition unit 31 records the displacement amount in 2-second intervals, for example, at a refresh rate of once per second. Simultaneously with the displacement amount, the displacement acquisition unit 31 also acquires the load applied by the first electrode 11 and the second electrode 12 to the workpiece W from the resistance welding machine 10.

[0044] (Current acquisition part) The current acquisition unit 32 is configured to acquire the magnitude of the welding current flowing between the first electrode 11 and the second electrode 12. The current acquisition unit 32 detects the welding current, for example, via a voltage detection line connected to the resistance welding machine 10.

[0045] (Judgment Department) The determination unit 33 is configured to determine whether or not there is a welding defect by comparing time-series data of the displacement amount (i.e., waveform data of the displacement amount) before the start of welding current supply or after the end of welding current supply with pre-prepared reference data.

[0046] The time-series data of the displacement amount is generated from the displacement amount acquired by the displacement amount acquisition unit 31. The periods "before the start of welding current supply" and "after the end of welding current supply" are determined from the magnitude of the welding current acquired by the current acquisition unit 32.

[0047] In other words, as shown in Figure 3, in the time-series data of displacement, the time period before the welding current I set by the control unit 2 flows is the pre-supply start period B, and the time period after the welding current I flows is the post-supply end period A.

[0048] The judgment unit 33 stores reference data for determining welding defects. The reference data includes time-series data of displacement and load when normal welding is performed, threshold values ​​(i.e., reference values) for various judgments, etc.

[0049] The determination unit 33 uses reference data to perform at least a gap determination process, a pressure determination process, and an adhesion determination process. These processes determine defects in the workpiece W before and after welding.

[0050] In the gap detection process, the determination unit 33 determines the presence or absence of a gap in the workpiece W based on the difference between the rate of increase of the displacement before the start of welding current supply and the reference rate included in the reference data S. This gap can cause delays in heat input and lead to poor joining of the welded joint.

[0051] Specifically, as shown in Figure 3, the determination unit 33 compares the rate of increase (i.e., slope) of the acquired displacement amount with the reference rate of the reference data S in the rising portion R of the displacement amount in the pre-supply start region B.

[0052] In the example shown in Figure 3, in addition to the reference data S, three other acquired data sets, the first data A1, the second data A2, and the third data A3, are illustrated. The reference data S is time-series data of the displacement amount when normal welding was performed under the same conditions as when the first data A1, etc., was acquired.

[0053] The slope of the rising portion R of the first data A1 is smaller than the slope of the reference data S. Therefore, the determination unit 33 determines that a gap existed between the first plate P1 and the second plate P2 that constitute the workpiece W in the welding in which the first data A1 was obtained.

[0054] Similarly, the determination unit 33 determines that a gap exists in the workpiece W for both the second data A2 and the third data A3. Furthermore, the timing of the rise in displacement amount for the second data A2 is earlier than that for the first data A1. Therefore, the determination unit 33 determines that the gap is larger for the second data A2 than for the first data A1.

[0055] In the gap determination process, the determination unit 33 further determines the size of the gap in the workpiece W based on the difference between the timing at which the increase in displacement amount begins before the start of welding current supply (i.e., the start time of the rise in displacement amount) and the timing at which the increase in displacement amount begins included in the reference data.

[0056] Specifically, the determination unit 33 determines the size of the gap using a table or determination formula. The table or determination formula used for the determination is a predetermined relationship between the time difference (for example, on the order of 10m) between the start of the increase in the displacement amount of the data to be determined relative to the reference data and the size of the gap in the workpiece W, and is constructed from past data.

[0057] In the pressure judgment process, the judgment unit 33 determines whether the pressure applied at the start of welding is appropriate based on a first comparison between the change in displacement per unit time before the start of welding current supply and a first reference value included in the reference data, and a second comparison between the displacement at the start of welding current supply and a second reference value included in the reference data. If this pressure is inappropriate, welding defects will occur.

[0058] Specifically, as shown in FIG. 4, in the first comparison, the determination unit 33 compares the maximum change amount C of the displacement amount in the region B before the start of supply with the first reference value as the threshold value. Further, in the second comparison, the determination unit 33 compares the displacement amount at the start time T of the supply of the welding current with the second reference value as the threshold value. In FIG. 4, time-series data of three displacement amounts of the fourth data A4, the fifth data A5, and the sixth data A6 are exemplified.

[0059] Based on the results of the first comparison and the second comparison, the determination unit 33 determines the appropriateness of the pressing force. For example, when the maximum change amount C of the fourth data A4 is larger than the first reference value, the determination unit 33 determines that the pressing was unstable in the welding at the time of acquisition of the fourth data A4.

[0060] The first reference value is, for example, a change amount of ±10% with respect to the displacement amount D1 at the time of stable pressing pre-registered in the reference data. That is, the determination unit 33 determines that the pressing is unstable when the maximum change amount C satisfies C > (D1×1.1 - D1×0.9).

[0061] Also, when the displacement amount at the start time T of the supply of the fourth data A4 is smaller than the second reference value by a certain value or more, the determination unit 33 determines that the pressing force was insufficient in the welding at the time of acquisition of the fourth data A4.

[0062] The second reference value is, for example, the displacement amount D1 at the time of stable pressing pre-registered in the reference data. The determination unit 33 determines that the pressing is insufficient when the displacement amount D2 at the start time T of the supply is smaller than 3% less than the second reference value, that is, when D2 < D×0.97 is satisfied.

[0063] Furthermore, when the displacement amount at the start time T of the supply of the fourth data A4 is larger than the second reference value by a certain value or more, the determination unit 33 determines that the pressing force was excessive in the welding at the time of acquisition of the fourth data A4. The determination unit 33 determines that the pressing is excessive when the displacement amount D2 at the start time T of the supply is larger than 3% more than the second reference value, that is, when D2 > D1×1.03 is satisfied.

[0064] Furthermore, when the determination unit 33 determines that there is insufficient or excessive pressure, it may also determine that a malfunction has occurred in the jig that holds the workpiece W.

[0065] In the adhesion determination process, the determination unit 33 determines whether or not the first electrode 11 or the second electrode 12 is stuck to the workpiece W based on a comparison between the rebound amount of the displacement after the supply of welding current is stopped and a reference amount included in the reference data.

[0066] Specifically, as shown in Figure 5, the determination unit 33 detects a rebound RB in the supply end region A, where the displacement rises again from zero after the falling portion F of the displacement. The determination unit 33 takes the maximum value of the displacement at the rebound RB as the rebound amount and compares this rebound amount with a reference amount used as a threshold.

[0067] If the rebound amount is greater than the standard amount, the determination unit 33 determines that the first electrode 11 or the second electrode 12 has stuck to the workpiece W. The reference amount is, for example, the displacement amount D3 in area A after supply has finished, when there is no sticking, which is recorded in advance, plus 3%. In other words, the determination unit 33 determines that sticking has occurred when the rebound amount D4 satisfies D4 > D3 × 1.03.

[0068] In addition to the judgment process described above, the judgment unit 33 performs a spatter judgment process and a current supply failure judgment process as processes to determine defects in the welding of the workpiece W.

[0069] In the spatter detection process, the detection unit 33 determines the presence and magnitude of spatter based on a comparison of time-series data of the load on the workpiece W during the supply of welding current with reference data. Specifically, the detection unit 33 determines that spatter has occurred if the difference between the load on the workpiece W and the reference data is ±3% or more. As shown in Figure 5, the locations where spatter has occurred are the depressions where the change in displacement C during welding (i.e., while current is flowing) is large.

[0070] Furthermore, the determination unit 33 determines the size of the spatter using a table or determination formula. The table or determination formula used for determination is a predetermined relationship between the load difference (for example, on the order of 100N) of the data to be determined relative to the reference data and the size of the spatter, and is constructed from past data.

[0071] In the power supply failure detection process, the determination unit 33 determines a power supply failure based on a comparison of time-series data of the load on the workpiece W during the supply of welding current with reference data. Specifically, the determination unit 33 determines that a power supply failure has occurred if the load on the workpiece W is 50% or less of the reference data.

[0072] Possible causes of poor electrical conduction include, for example, a faulty diode in the welding transformer, abnormal current distribution, improper setting of the workpiece W, overvoltage of the workpiece W, intrusion of foreign matter, and faulty electrodes (i.e., abnormal tip diameter).

[0073] (Output section) The output unit 34 shown in Figure 1 is configured to output the displacement amount acquired by the displacement amount acquisition unit 31, the magnitude of the welding current acquired by the current acquisition unit 32, and the result determined by the determination unit 33 (i.e., whether or not there is a welding defect).

[0074] The output unit 34 may be a display that shows the data mentioned above. Alternatively, the output unit 34 may be a transmitter that sends the data mentioned above to an external storage medium, control device, computer, etc., of the welding control device 1.

[0075] [1-2. Welding Quality Evaluation Methods] The welding quality evaluation method shown in Figure 6 is performed by the welding quality evaluation device 3. The welding quality evaluation method of this embodiment comprises an acquisition step S10 and a determination step S20.

[0076] (Acquisition process) In this process, the displacement of the first electrode 11 relative to the second electrode 12 and the magnitude of the welding current flowing between the first electrode 11 and the second electrode 12 are obtained.

[0077] (Judgment process) In this process, after the acquisition process S10, the presence or absence of welding defects is determined by comparing the time-series data of the displacement amount before the start of welding current supply or after the end of welding current supply with pre-prepared reference data.

[0078] [1-3. Effects] According to the embodiments described in detail above, the following effects can be obtained. (1a) By comparing time-series data of displacement before and after energization with reference data, defects that cannot be determined from the displacement during energization (e.g., disturbances, welding defects, etc.) can be identified. As a result, the accuracy of defect detection in resistance welding can be improved.

[0079] (1b) The gap detection process can detect whether or not there are gaps between the plates that make up the workpiece W. As a result, defects caused by the workpiece W can be detected. In addition to detecting gaps in the workpiece W, the size of those gaps can also be determined.

[0080] (1c) The pressure judgment process can detect insufficient and unstable pressure. As a result, malfunctions caused by the resistance welding machine 10 can be detected. (1d) The adhesion detection process can detect excessive welding due to overheating. As a result, it is possible to detect setting errors such as the amount of current supplied.

[0081] (1e) The spatter detection process makes it possible to detect defects caused by spatter generation during welding. As a result, defects caused by welding conditions can be detected. (1f) The power supply failure detection process makes it possible to detect malfunctions caused by power supply failures during welding. As a result, malfunctions caused by the resistance welding machine 10 can be detected.

[0082] [2. Other Embodiments] While embodiments of this disclosure have been described above, it goes without saying that this disclosure is not limited to the embodiments described above and can take various forms.

[0083] (2a) The welding quality evaluation device of the above embodiment does not necessarily have to be incorporated into the welding control device. For example, the welding quality evaluation device may be connected to the resistance welding machine independently of the welding control device.

[0084] (2b) The welding quality evaluation device of the above embodiment can also be used with resistance welding machines that apply pressure to the workpiece in the horizontal direction (i.e., welding is performed with the first plate and the second plate overlapping horizontally).

[0085] (2c) The functions of one component in the above embodiment may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Also, some parts of the configuration of the above embodiment may be omitted. Also, at least some parts of the configuration of the above embodiment may be added to, substituted for, or otherwise replaced with the configuration of other above embodiments. Any aspect of the technical concept specified by the wording of the claims is an embodiment of the present disclosure. [Explanation of Symbols]

[0086] 1...Welding control device, 2...Control unit, 3...Welding quality evaluation device, 10...Resistance welding machine, 11...First electrode, 12...Second electrode, 13...Support part, 14...Motor, 15...Transmitter 16... Strain sensor, 17... Encoder, 18... Welding gun, 31... Displacement amount acquisition unit, 32... Current acquisition section, 33... Judgment section, 34... Output section.

Claims

1. A welding quality evaluation device used in a resistance welding machine that pressurizes a workpiece with a first electrode and a second electrode and welds the workpiece by energizing the first electrode and the second electrode, A displacement amount acquisition unit configured to acquire the amount of displacement of the first electrode relative to the second electrode, A current acquisition unit configured to acquire the magnitude of the welding current flowing between the first electrode and the second electrode, A determination unit is configured to determine whether or not there is a welding defect by comparing time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Equipped with, A welding quality evaluation device wherein the determination unit is configured to determine whether there is a gap in the workpiece based on the difference between the rate of increase of the displacement before the start of supplying the welding current and the reference rate included in the reference data, and to determine the size of the gap in the workpiece based on the difference between the timing of the start of the increase of the displacement before the start of supplying the welding current and the timing of the start of the increase of the displacement included in the reference data.

2. A welding quality evaluation device used in a resistance welding machine that pressurizes a workpiece with a first electrode and a second electrode and welds the workpiece by energizing the first electrode and the second electrode, A displacement amount acquisition unit configured to acquire the amount of displacement of the first electrode relative to the second electrode, A current acquisition unit configured to acquire the magnitude of the welding current flowing between the first electrode and the second electrode, A determination unit is configured to determine whether or not there is a welding defect by comparing time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Equipped with, A welding quality evaluation device configured such that the determination unit determines whether the applied pressure at the start of welding is appropriate based on a comparison between the amount of change per unit time of the displacement before the start of supply of the welding current and a first reference value included in the reference data, and a comparison between the amount of displacement at the start of supply of the welding current and a second reference value included in the reference data.

3. A welding quality evaluation device used in a resistance welding machine that pressurizes a workpiece with a first electrode and a second electrode and welds the workpiece by energizing the first electrode and the second electrode, A displacement amount acquisition unit configured to acquire the amount of displacement of the first electrode relative to the second electrode, A current acquisition unit configured to acquire the magnitude of the welding current flowing between the first electrode and the second electrode, A determination unit is configured to determine whether or not there is a welding defect by comparing time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Equipped with, The welding quality evaluation device is configured such that the determination unit determines the presence and size of spatter based on a comparison of time-series data of the load on the workpiece during the supply of the welding current with the reference data.

4. A welding quality evaluation apparatus according to any one of claims 1 to 3, A welding quality evaluation device wherein the determination unit is configured to determine whether or not the first electrode or the second electrode is sticking to the workpiece based on a comparison between the rebound amount of the displacement after the supply of the welding current is stopped and a reference amount included in the reference data.

5. A welding quality evaluation apparatus according to any one of claims 1 to 3, The welding quality evaluation device is configured such that the determination unit determines a faulty current supply based on a comparison of time-series data of the load on the workpiece during the supply of the welding current with the reference data.

6. A welding quality evaluation program used in resistance welding, in which a workpiece is welded by applying pressure to the workpiece with a first electrode and a second electrode while current is passed between the first electrode and the second electrode, wherein the welding quality evaluation program is: The amount of displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode are obtained, The presence or absence of welding defects is determined by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Have the computer run it, A welding quality evaluation program that determines whether there is a gap in the workpiece based on the difference between the rate of increase of the displacement before the start of supplying the welding current and the reference rate included in the reference data, and determines the size of the gap in the workpiece based on the difference between the timing of the start of the increase of the displacement before the start of supplying the welding current and the timing of the start of the increase of the displacement included in the reference data.

7. A welding quality evaluation program used in resistance welding, in which a workpiece is welded by current flowing between the first electrode and the second electrode while the workpiece is pressurized by the first electrode and the second electrode, wherein the welding quality evaluation program is: The amount of displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode are obtained, The presence or absence of welding defects is determined by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Have the computer run it, A welding quality evaluation program that determines whether the applied pressure at the start of welding is appropriate, based on a comparison of the change in the amount of displacement per unit time before the start of supply of the welding current with a first reference value included in the reference data, and a comparison of the amount of displacement at the start of supply of the welding current with a second reference value included in the reference data.

8. A welding quality evaluation program used in resistance welding, in which a workpiece is welded by current flowing between the first electrode and the second electrode while the workpiece is pressurized by the first electrode and the second electrode, wherein the welding quality evaluation program is: The amount of displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode are obtained, The presence or absence of welding defects is determined by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data. Have the computer run it, A welding quality evaluation program that determines the presence and size of spatter based on a comparison of time-series data of the load on the workpiece during the supply of the welding current with reference data.

9. A welding quality evaluation method in resistance welding, in which a workpiece is welded by applying pressure to the workpiece with a first electrode and a second electrode and by passing an electric current between the first electrode and the second electrode, wherein the welding quality evaluation method is: A step of obtaining the displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode, A step of determining whether or not there is a welding defect by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data, Equipped with, A welding quality evaluation method comprising the determination step of determining whether there is a gap in the workpiece based on the difference between the rate of increase of the displacement before the start of supplying the welding current and the reference rate included in the reference data, and determining the size of the gap in the workpiece based on the difference between the timing of the start of the increase of the displacement before the start of supplying the welding current and the timing of the start of the increase of the displacement included in the reference data.

10. A method for evaluating welding quality in resistance welding, wherein the workpiece is pressed by a first electrode and a second electrode and the workpiece is welded by current flowing between the first electrode and the second electrode, the welding quality evaluation method being: A step of obtaining the displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode, A step of determining whether or not there is a welding defect by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data, Equipped with, A welding quality evaluation method comprising the step of determining whether the applied pressure at the start of welding is appropriate, based on a comparison of the amount of change per unit time of the displacement before the start of supply of the welding current with a first reference value included in the reference data, and a comparison of the amount of displacement at the start of supply of the welding current with a second reference value included in the reference data.

11. A method for evaluating welding quality in resistance welding, wherein the workpiece is pressed by a first electrode and a second electrode, and the workpiece is welded by current flowing between the first electrode and the second electrode, wherein the welding quality evaluation method is: A step of obtaining the displacement of the first electrode relative to the second electrode and the magnitude of the welding current flowing between the first electrode and the second electrode, A step of determining whether or not there is a welding defect by comparing the time-series data of the displacement amount before the start of supplying the welding current or after the end of supplying the welding current with pre-prepared reference data, Equipped with, A welding quality evaluation method comprising the step of determining the presence and size of spatter based on a comparison of time-series data of the load on the workpiece during the supply of the welding current with the reference data.

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