Measurement device, measurement system, and measurement method

Abstract

To shorten the time required to measure the state of a plurality of welded portions.SOLUTION: A measurement device 1 measures the state of a plurality of welded portions 23a to 23d formed when a weldment 21 is welded at a plurality of positions to an object to be welded. The measurement device 1 includes a plurality of application circuits 40a to 40d for applying currents exclusively to each of the one or the plurality of welded portions, and a detection circuit 50 for detecting a voltage that is the combination of voltages indicating the magnitude of the voltage drop produced on each welded portion by the application of the currents. Further, the measurement device 1 includes a processing unit for outputting information indicating the state of a plurality of welded portions 23a through 23d on the basis of the voltage detected by the detection circuit 50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a measuring device, a measuring system, and a measuring method for measuring the state of a weld. [Background technology]

[0002] Patent Document 1 discloses a device for measuring the resistance of a welded portion of a secondary battery, where a group of tabs is welded to a conductive member. This device applies a current to the welded portion from one first probe and measures the condition of the welded portion by detecting an output signal from a pair of second probes that are in contact with different positions around the welded portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-60769 Summary of the Invention [Problem to be solved by the invention]

[0004] In the measurement device described above, to measure a weld, a pair of probes for detecting voltage must be arranged at intervals around the weld. Therefore, if there are multiple welds, after measuring one weld, when measuring a weld formed in another location, a pair of probes must be arranged around the other weld.

[0005] As described above, it is necessary to change the contact position of the pair of probes for each weld to be measured, which poses the problem that it takes a long time to measure all the welds.

[0006] The present invention has been made in view of such problems, and has as its object to shorten the time required to measure the states of a plurality of welds. [Means for solving the problem]

[0007] According to one aspect of the present invention, a measurement device measures the state of multiple welds formed when a workpiece is welded to a workpiece at multiple locations, and includes multiple application circuits that apply current exclusively to one or more of the welds, a detection circuit that detects a combined voltage of voltages that indicate the magnitude of voltage drops that occur at each of the welds due to the application of the current, and a processing unit that outputs information indicating the state of the multiple welds based on the combined voltage. [Effects of the Invention]

[0008] According to this aspect, a current is applied exclusively to each of one or more welds, and the voltage generated at each of the welds is combined to produce a voltage that varies depending on the state of each of the welds. Therefore, by detecting the value of this combined voltage, it is possible to determine whether the state of the multiple welds to which current is applied is poor.

[0009] Therefore, the time required to measure the state of a plurality of welds can be shortened compared to when a current is applied to each weld and the voltage generated at each weld is detected. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of a measurement device according to a first embodiment of the present invention. [Figure 2A] FIG. 2A is a diagram showing the connection relationship between the measurement device and the object to be measured. [Figure 2B] FIG. 2B is an external view showing a plurality of welds in the measurement object. [Figure 3] FIG. 3 is a diagram showing an example of a potential distribution formed on the measurement object when a current is applied to each of the welds. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between defective locations of a plurality of welds and the voltage value of the composite voltage detected by the detection circuit. [Figure 5] FIG. 5 is a flowchart showing an example of a processing procedure of a measurement method for measuring the state of a group of welds in the first embodiment. [Figure 6] FIG. 6 is a diagram showing the connection relationship between the measurement device and the measurement object in the second embodiment. [Figure 7] FIG. 7 is a block diagram showing the configuration of the measurement device. [Figure 8] FIG. 8 is a diagram showing an example of the relationship between defective locations in a group of welds and the voltage value of the composite voltage. [Figure 9] FIG. 9 is a diagram showing the configuration of a measurement system in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this specification, the same elements are designated by the same reference numerals throughout.

[0012] (First embodiment) FIG. 1 is a block diagram showing the configuration of a measurement device for measuring a welded portion in the first embodiment.

[0013] Measuring device 1 is a condition measuring device for measuring the condition of a plurality of welds formed on a measurement object 2. The plurality of welds to be measured will hereinafter also be referred to as a group of welds.

[0014] The object to be measured 2 is a joined body in which a workpiece to be welded is welded at a plurality of locations. In the first embodiment, the object to be measured 2 is an electrode part of a cylindrical secondary battery, and the workpiece to be welded is an electrode 22 that constitutes the electrode part.

[0015] The electrode part described above has four welds 23a to 23d formed when a weldment 21 disposed on the outside of a secondary battery is welded to an electrode 22 of the secondary battery at four locations. A part of the back surface of the weldment 21 is welded to the outer surface of the electrode 22, and the front surface of the weldment 21 is connected to an external load device, such as an electric motor or an inverter, via a power line or the like.

[0016] The object to be measured 2 in the first embodiment is an electrode component used in an electric vehicle, and a current of several hundred amperes (A) may flow through the welded portions 23a to 23d. In such a case, if at least one of the welded portions 23a to 23d is not reliably welded, there is a concern that excessive heat may be generated or the welded object 21 may come off the electrode 22.

[0017] To address this issue, the measuring device 1 measures the states of the welds 23a to 23d in order to determine whether or not the welding state of the measurement object 2 is poor. The measuring device 1 is made up of one or more measuring devices.

[0018] The measuring device 1 applies (supplies) current exclusively to one or more welds among a group of the welds 23a to 23d. In this state, the measuring device 1 detects a voltage obtained by combining voltages that indicate the magnitude of voltage drops that occur at each of the welds 23a to 23d, thereby making it possible to determine the state of the multiple welds 23a to 23d. Hereinafter, the voltage obtained by combining the voltages that are applied to the voltage drops that occur at each of the welds will be referred to as the combined voltage.

[0019] In the first embodiment, the measurement device 1 includes a probe group P, an operation unit 10, a control unit 20, a measurement unit 30, an application unit 40 having a plurality of application circuits 40a to 40d, a detection circuit 50, a memory unit 60, a display unit 70, and a communication unit 80.

[0020] The probe group P has a plurality of pairs of application probes Pa1 to Pa4 and another pair of detection probes Pd.

[0021] The plurality of pairs of application probes Pa1 to Pa4 are each made up of a plurality of conducting wires, one end of which is electrically connected to both ends of each of the application circuits 40 a to 40 d, and a plurality of pairs of conductive contacts (first contacts), the other ends of which are electrically connected to the respective conducting wires. The plurality of pairs of application probes Pa1 to Pa4 come into contact with portions of both the workpiece 21 and the electrode 22 near the plurality of welds 23 a to 23 d, respectively.

[0022] In the first embodiment, four pairs of application probes Pa1 to Pa4 are used to apply current to the welds 23a to 23d, respectively. For example, the pair of application probes Pa1 is positioned so that a line connecting the contact portion of one application probe and the contact portion of the other application probe passes through the weld 23a. The same applies to the other pairs of application probes Pa2 to Pa4.

[0023] The pair of detection probes Pd is another pair of conductive contacts (second contacts) connected to both ends of the detection circuit 50. The pair of detection probes Pd is used to detect a composite voltage obtained by combining voltages indicating the magnitude of the voltage drop occurring at each of the welds 23a to 23d.

[0024] The pair of detection probes Pd contacts the portions of the welding work 21 and the electrode 22 that are farther from the plurality of welds 23a to 23d than the portions of the welding work 21 and the electrode 22 that the pair of application probes Pa1 to Pa4 contact, respectively.

[0025] For example, a pair of detection probes Pd contacts portions of both the welded part 21 and the electrode 22 that are located on any of the lines that pass from the center of gravity of the polygon formed by the multiple welds 23a to 23d to the midpoints of each side of the polygon.

[0026] 1, the pair of detection probes Pd in ​​the first embodiment contact portions D1 and D2 of both the weldment 21 and the electrode 22, respectively, which are located at approximately the same distance from each of the welds 23a to 23d. Specifically, one of the pair of detection probes Pd contacts a portion located at the center of the surface of the weldment 21, and the other detection probe contacts a portion of the surface of the electrode 22 exposed from the weldment 21 that is located near the portion of the weldment 21.

[0027] The operation unit 10 is composed of a plurality of push buttons provided around the display screen that constitutes the display unit 70, a touch sensor arranged within the display screen, a keyboard, a mouse, etc. The operation unit 10 accepts input operations from the user who uses the measuring device 1, and generates an operation signal that indicates the content of the accepted input operation.

[0028] Examples of input operations by the user include an operation of pressing the power button, an operation of setting measurement conditions, an operation of instructing the execution of measurement processing, an operation of instructing the stop of measurement processing, and the like.

[0029] When the operation unit 10 receives an input operation for setting measurement conditions, it outputs an operation signal indicating the measurement conditions to the control unit 20 to record the operation signal in the storage unit 60. Furthermore, when the operation unit 10 receives an input operation for instructing the execution of a measurement process, it outputs an operation signal indicating the execution of the measurement process to the control unit 20.

[0030] The control unit 20 is configured with one or more processors, such as a CPU (Central Processing Unit) or an MPU (Micro Processor Unit).

[0031] The control unit 20 executes a measurement process for measuring the welding state of the measurement object 2. The control unit 20 in the first embodiment issues an application command to the measurement unit 30 to apply a current to each of the welded portions 23a to 23d.

[0032] The measurement unit 30 controls the operation of the application unit 40 and the detection circuit 50 so that currents are simultaneously applied from the application circuits 40a to 40d to the welding parts 23a to 23d, respectively, and the voltages generated at the parts of the workpiece 21 or the electrode 22 are measured.

[0033] The portion of the workpiece 21 is located in a region where the voltage gradient is gentler than that near the welds 23a to 23d. Similarly, the portion of the electrode 22 is also located in a region where the voltage gradient is gentler than that near the welds 23a to 23d.

[0034] The spacing between the equipotential lines in the object to be measured 2 when all the current is applied from the weldment 21 to the electrode 22 is the same as the spacing between the equipotential lines in the object to be measured 2 when all the current is applied from the electrode 22 to the weldment 21. Therefore, even if the direction of the current changes, the locations of the weldment 21 and the electrode 22 are determined to be in the same region, i.e., the region where the voltage gradient is gentle.

[0035] A composite voltage, which is a composite of voltages that indicate the magnitude of the voltage drop occurring at each of the welds 23a to 23d, occurs between the workpiece 21 and the electrode 22. For example, if some of the welds 23a to 23d are defective, when current is applied to each of the welds 23a to 23d in the same direction, the voltage drop occurring at the defective welds will be large, and the composite voltage between the workpiece 21 and the electrode 22 will be large.

[0036] The measuring unit 30 measures a composite voltage indicating the potential difference between the part of the work 21 and the part of the electrode 22. The measuring unit 30 then generates measurement information indicating the state of the plurality of welds 23a to 23d based on the measured composite voltage. The measuring unit 30 outputs the measurement result indicating the measured composite voltage to the control unit 20 so that the measurement result can be recorded in the memory unit 60.

[0037] For example, the measurement unit 30 determines whether the welding state of a group of the welded portions 23a to 23d is poor based on the measured composite voltage. As a specific example, a threshold value indicating the magnitude of the composite voltage when the welding state of all of the welded portions 23a to 23d is good is stored in advance in the memory unit 60, and the measurement unit 30 determines whether the measured value of the composite voltage exceeds the threshold value.

[0038] If the measured value of the composite voltage exceeds the threshold, measurement unit 30 determines that some of all welds 23a to 23d are defective and generates status information indicating that. On the other hand, if the measured value of the composite voltage does not exceed the threshold, measurement unit 30 determines that all welds 23a to 23d are good and generates status information indicating that. Measurement unit 30 outputs the generated status information to control unit 20 as the above-mentioned measurement information.

[0039] In the first embodiment, the measurement unit 30 generates voltage information indicating the magnitude of the measured composite voltage as measurement information. By notifying the user of this voltage information, the user can determine that the welding condition is good if the measured value of the composite voltage indicated in the voltage information does not exceed a known threshold value.

[0040] Furthermore, the measuring unit 30 issues an application command to the applying unit 40 to apply current to the group of welding points 23a to 23d simultaneously, and issues a detection command to the detecting circuit 50 to detect the composite voltage.

[0041] The application unit 40 is configured with a plurality of application circuits 40a to 40d. The application unit 40 in the first embodiment has four application circuits 40a to 40d, and applies current simultaneously from the application circuits 40a to 40d to a group of welds 23a to 23d, respectively, via pairs of application probes Pa1 to Pa4.

[0042] For example, each of the currents applied to the welding zones 23a to 23d from the application unit 40 may be a constant DC current or a constant AC current. However, when a constant AC current is used as the applied current, it is desirable to output currents of the same phase from each of the application circuits 40a to 40d.

[0043] The magnitudes of the currents applied to the welded parts 23a to 23d may be set to the same current value or different current values. The applied current may flow in two directions: from the work 21 to the electrode 22, and from the electrode 22 to the work 21. All the applied currents may flow in the same direction, or at least one of the applied currents may flow in a different direction.

[0044] The plurality of application circuits 40a to 40d apply current exclusively to one or more of the welds 23a to 23d formed on the weldment 21.

[0045] In the first embodiment, the application circuits 40a to 40d correspond one-to-one to the welds 23a to 23d, and apply equal constant currents in the same direction to different regions.

[0046] For example, application circuit 40a applies a DC current equivalent to the other applied currents from work 21 to welded portion 23a, and application circuit 40b applies a DC current equivalent to the other applied currents from work 21 to welded portion 23b. Furthermore, application circuit 40c applies a DC current equivalent to the other applied currents from work 21 to welded portion 23c, and application circuit 40d applies a DC current similar to the other applied currents from work 21 to welded portion 23d.

[0047] The detection circuit 50 detects a composite voltage obtained by combining voltages that indicate the magnitude of the voltage drop that occurs at each of the welded portions 23a to 23d due to the application of current.

[0048] In the first embodiment, the detection circuit 50 detects a composite voltage between a portion of the welding work 21 and a portion of the electrode 22 via a pair of detection probes Pd. The detection circuit 50 outputs a detection signal indicating the magnitude of the detected composite voltage to the measurement unit 30. The measurement unit 30 generates measurement information based on the detection signal from the detection circuit 50 as described above.

[0049] The storage unit 60 is configured with RAM and ROM. The storage unit 60 stores measurement information written by the control unit 20. The storage unit 60 may be used as a storage unit that stores threshold values ​​for determining the states of the plurality of welds 23a to 23d.

[0050] The storage unit 60 also stores a program for the control unit 20 to execute the measurement process in the first embodiment. That is, the storage unit 60 is a computer-readable storage medium on which programs for controlling each part of the measurement device 1 are recorded.

[0051] The display unit 70 is configured by an LED (Light Emitting Diode) display for displaying images, a liquid crystal panel, a touch panel, etc. The display unit 70 displays, for example, measurement information or measurement conditions received from the control unit 20.

[0052] The communication unit 80 is configured by a communication circuit that communicates with an external device different from the measurement device 1. For example, the communication unit 80 can receive measurement conditions from the external device wirelessly or via a network such as the Internet or a telephone network, and transmit measurement results to the external device.

[0053] Next, a method for measuring the welding conditions of a group of welds 23a to 23d formed on measurement object 2 will be described with reference to FIGS.

[0054] Fig. 2A is a diagram showing an example of a connection configuration between the measurement device 1 and the measurement object 2 in the first embodiment. Fig. 2B is a perspective view showing the appearance of the measurement object 2. As shown in Figs. 2A and 2B, a group of welds 23a to 23d are formed when the back surface of the welded object 21 is welded to the outer surface of the electrode 22 at four locations.

[0055] 2A, the application circuits 40a to 40d are configured as constant current circuits that output the same DC current. The four application circuits 40a to 40d apply constant currents in the same direction exclusively to the welds 23a to 23d from portions of the electrode 22 located near the welds 23a to 23d, respectively, via pairs of application probes Pa1 to Pa4 shown in FIG.

[0056] With respect to the weld 23a, one of the pair of application probes Pa1 is in contact with a portion of the exposed surface of the electrode 22 that is near the weld 23a. The other application probe Pa1 is in contact with a portion of the surface of the workpiece 21 that is determined to straddle the weld 23a from the portion of the electrode 22. Similarly, with respect to the other welds 23b to 23d, portions of both the workpiece 21 and the electrode 22 are determined to straddle the respective welds.

[0057] In this state, the detection circuit 50 detects, via the pair of detection probes Pd shown in FIG. 1, a composite voltage obtained by combining voltages that indicate the magnitude of the voltage drop occurring at each of the welds 23a to 23d.

[0058] Both of the pair of detection probes Pd are in contact with portions D1 and D2, respectively, which are located at approximately the same distance from the four welds 23 a to 23 d. Specifically, one of the pair of detection probes Pd is in contact with portion D1 of weldment 21, which is located at approximately the same distance from the four welds 23 a to 23 d. The other of the pair of detection probes Pd is in contact with portion D2 of electrode 22, which is located at approximately the same distance from the four welds 23 a to 23 d.

[0059] Next, the parts D1 and D2 of the workpiece 21 and the electrode 22 will be described with reference to FIG.

[0060] FIG. 3 is a diagram showing the simulation results of the potential distribution in the measurement object 2 when constant currents in the same direction are applied from the application circuits 40a to 40d shown in FIG. 2A to the vicinity of the welds 23a to 23d of the weldment 21, respectively.

[0061] 3, the equipotential lines are closely spaced and the potential gradient is steep near the welds 23a to 23d in the weldment 21. Therefore, in this region, the detection error of the composite voltage increases due to a positional shift of the contact point of one of the detection probes Pd (see FIG. 2A).

[0062] On the other hand, along or near each imaginary line that starts from the center of gravity of a rectangle formed by the centers of the welds 23a to 23d and passes through the midpoints of each side of the rectangle, the equipotential lines are sparsely spaced and the potential gradient is gentle. Therefore, even if the contact point of the detection probe Pd on the welded workpiece 21 is slightly shifted from the desired location D1, fluctuations in the detected value of the composite voltage are suppressed. This allows the detection circuit 50 to accurately detect the value of the composite voltage.

[0063] 3, the current path of electrode 22 is wider than that of workpiece 21, and DC current is applied from the surface of workpiece 21, so the spacing between equipotential lines is wider than that of the potential distribution of workpiece 21. However, similar to the potential distribution of workpiece 21, the potential gradient is steep near welds 23a to 23d, and the potential gradient is gentle on or near each of the above-mentioned imaginary lines.

[0064] Therefore, when current is applied from the welded object 21 to each of the welds 23a to 23d, it is preferable to bring at least one of the detection probes Pd into contact with a portion D1 of the welded object 21 that is located approximately equidistant from each of the welds 23a to 23d.

[0065] Furthermore, although the spacing between the equipotential lines is sparser in the electrode 22 than in the potential distribution of the welded object 21, it is desirable to similarly bring the other end of the detection probe Pd into contact with the portion D2 of the electrode 22 that is located at approximately the same distance from each of the welds 23a to 23d.

[0066] In the first embodiment, as shown by the dotted and dashed lines in FIG. 2A, both of the pair of detection probes Pd contact portions D1 and D2 of the workpiece 21 and electrode 22, respectively, which are positioned approximately equidistant from each of the welds 23a to 23d.

[0067] In the first embodiment, current is applied from the welding object 21 to each of the welding points 23a to 23d using the application circuits 40a to 40d, but instead, current may be applied from the electrode 22 to each of the welding points 23a to 23d.

[0068] Even in such a case, the spacing between the equipotential lines remains unchanged on both the welded work 21 and the electrode 22. Therefore, from the viewpoint of improving the detection accuracy of the composite voltage, it is preferable to bring at least the other end of the detection probe Pd into contact with a portion D2 of the electrode 22 that is located on or near one of the above-mentioned imaginary lines. In particular, it is preferable to bring the other end of the detection probe Pd into contact with a portion D2 of the electrode 22 that is located approximately equidistant from each of the welds 23a to 23d.

[0069] Next, the relationship between the welding state of the group of welded portions 23a to 23d and the voltage value of the composite voltage detected by the detection circuit 50 will be described with reference to FIG.

[0070] Fig. 4 is a diagram for explaining how the composite voltage changes depending on the welding state of a group of welds 23a to 23d. As an example, Fig. 4 shows the measurement results of the composite voltage when a direct current of 1.0 [A] is applied to a portion of workpiece 21 from each of application circuits 40a to 40d.

[0071] As shown in Figure 4, when the welding condition of all welds 23a to 23d is good, the composite voltage is 6.7 [μV], and when any one of welds 23a to 23d is poor, the composite voltage is approximately 10 [μV].

[0072] Furthermore, if two welds 23a and 23d are defective, the composite voltage is 14.4 [μV], and if three welds 23a, 23b, and 23c are defective, the composite voltage is 20.8 [μV].

[0073] Therefore, when measuring unit 30 determines whether the welding conditions of all of welds 23a to 23d are good, the first threshold value for determining whether the welding conditions are good or bad is set to a value within the range of, for example, 7 μV to 9 μV, taking into account measurement errors, etc. By setting the first threshold value in this manner, control unit 20 can determine that all of welds 23a to 23d are good when the measured value of the combined voltage exceeds the first threshold value.

[0074] Similarly, the second threshold for determining whether two welds are defective is set to a value within a range of, for example, 13 μV to 19 μV. Then, when the measured value of the combined voltage exceeds the second threshold, control unit 20 can determine that any two of welds 23 a to 23 d are defective. Furthermore, a third threshold for determining whether three welds are defective can be set in a similar manner.

[0075] In the first embodiment, the control unit 20 displays the measurement value of the composite voltage on the display unit 70. This allows the user to check the measurement value of the composite voltage displayed on the display unit 70 and determine the number of welds 23a to 23d that are in a poor welding state based on the measurement value.

[0076] In the example shown in FIG. 4, the application circuits 40a to 40d output equal currents in the same direction, but the first embodiment is not limited to this.

[0077] For example, application circuits 40a to 40d may output currents of different magnitudes. As a specific example, the output currents of application circuits 40b to 40d are set to current values ​​that are two times, three times, and four times the output current of application circuit 40a, respectively. As a result, the voltage value of the composite voltage when only welded portion 23a is defective and the voltage value of the composite voltage when only welded portion 23b is defective are different from each other, making it possible to identify welded portions 23a to 23d that have poor welding conditions based on the value of the composite voltage.

[0078] Furthermore, the probe group P may be arranged so that the direction of the output power of at least one of the application circuits 40a to 40d is opposite to the direction of the output current of the others. For example, the output current of the application circuits 40a to 40c may be caused to flow from the work to be welded 21 to the electrode 22, and the output current of the application circuit 40d may be caused to flow from the electrode 22 to the work to be welded 21. Even in this case, if at least one of the welds 23a to 23d is defective, the voltage value of the composite voltage will change, making it possible to determine whether the welding condition of the group is good or bad.

[0079] Furthermore, the thinner the welded object 21, the higher the voltage value of the composite voltage. Therefore, the thinner the welded object 21, the greater the difference between the voltage value of the composite voltage when the welded state is poor and the voltage value of the composite voltage when the welded state is good, which makes it possible to improve the accuracy of the pass / fail judgment. Similarly, the narrower the current path of the welded object 21, the higher the voltage value of the composite voltage, which makes it possible to improve the judgment accuracy.

[0080] Next, the operation of the measurement device 1 in the first embodiment will be described with reference to FIG.

[0081] FIG. 5 is a flowchart showing an example of the procedure of a measurement method for measuring the welding conditions of a group of welds 23a to 23d.

[0082] In step S1, the measuring device 1 applies a current exclusively to each of predetermined welds 23a to 23d, which are different from one another.

[0083] In the first embodiment, the application circuits 40a to 40d correspond one-to-one to the welds 23a to 23d, and therefore the measuring device 1 applies current to different regions for each weld so that imaginary lines connecting the parts of the workpiece 21 and the electrode 22 located near the weld do not intersect with each other.

[0084] In step S2, the measuring device 1 detects a composite voltage obtained by combining the voltages generated at the welded portions 23a to 23d.

[0085] 2A, the measuring device 1 comes into contact with portions of the work piece 21 and the electrode 22 that are positioned approximately equidistant from each of the welds 23a to 23d. The measuring device 1 then detects the voltage between the work piece 21 and the electrode 22 as a composite voltage, and obtains the value of the detected composite voltage.

[0086] In step S3, the measuring device 1 generates measurement information indicating the welding state of the group of welds 23a to 23d based on the obtained detection value of the composite voltage.

[0087] In the first embodiment, the measurement device 1 calculates a measurement value of the composite voltage based on the output signal of the detection circuit 50, and generates measurement information indicating the calculated measurement value. The measurement device 1 then outputs the generated measurement information to the display unit 70 or the communication unit 80. This notifies the user of the measurement information, allowing the user to understand or estimate the quality of the welding state of a group of welds based on the voltage value of the composite voltage indicated in the measurement information.

[0088] When the process of step S3 is completed, the series of processes of the measurement method shown in FIG. 5 is completed.

[0089] Next, the effects of the first embodiment will be described.

[0090] In the first embodiment, measuring device 1 measures the state of multiple welds 23a to 23d formed when workpiece 21 is welded at multiple locations to electrode 22, which corresponds to the workpiece to be welded. This measuring device 1 includes multiple application circuits 40a to 40d that apply current exclusively to each of welds 23a to 23d. Measuring device 1 also includes a detection circuit 50 that detects a composite voltage obtained by combining voltages that indicate the magnitude of voltage drops that occur at each weld due to the application of current by application circuits 40a to 40d, and a control unit 20 that outputs information indicating the state of multiple welds 23a to 23d based on the composite voltage detected by detection circuit 50.

[0091] The measurement method for measuring the states of the plurality of welds 23 a to 23 d in the first embodiment includes a plurality of application steps (S1) for applying currents exclusively to each weld, and a detection step (S2) for detecting the composite voltage described above by applying the currents in the plurality of application steps. This measurement method further includes a processing step (S3) for outputting information indicating the states of the plurality of welds 23 a to 23 d based on the composite voltage detected in the detection step.

[0092] With these configurations, current is applied exclusively to each welded portion, and the composite voltage generated by the voltage drop at each of the welded portions 23 a to 23 d exhibits different values ​​depending on the state of each of the welded portions 23 a to 23 d. Therefore, by detecting the composite voltage, it is possible to determine whether or not the multiple welded portions 23 a to 23 d are defective.

[0093] Therefore, the time required to measure the states of the plurality of welded portions 23a to 23d can be shortened compared to when the voltages generated at the welded portions 23a to 23d are detected at different times.

[0094] In addition, the measurement device 1 in the first embodiment includes application probes Pa1 to Pa4 that constitute multiple pairs of contacts connected to both ends of each of the application circuits 40a to 40d, and a detection probe Pd that constitutes another pair of contacts connected to both ends of the detection circuit 50.

[0095] The above-described pairs of application probes Pa1 to Pa4 each come into contact with a portion of the welded workpiece 21 near the plurality of welds 23a to 23d or a portion of the electrode 22. The other pair of detection probes Pd comes into contact with a portion D1 of the welded workpiece 21 or a portion D2 of the electrode 22 that is farther from the plurality of welds 23a to 23d than the portions of the welded workpiece 21 or the portions of the electrode 22 that the plurality of pairs of application probes Pa1 to Pa4 each come into contact with.

[0096] Specifically, one of the pair of detection probes Pd may contact a portion D1 of the weldment 21 that is farther from the plurality of welds 23a to 23d than the portions of the weldment 21 provided for each weld, or the other may contact a portion D2 of the electrode 22 that is farther from the plurality of welds 23a to 23d than the portions of the weldment 21 provided for each weld.

[0097] In the welded work 21 and the electrode 22, the potential gradient in the vicinity of a portion becomes gentler as the portion is farther away from the plurality of welds 23a to 23d. Therefore, with the above configuration, when at least one of the pair of detection probes Pd is brought into contact with the portion D1 or D2 of the welded work 21 or the electrode 22 where the potential gradient is gentle, it is possible to suppress measurement errors in the composite voltage caused by misalignment of the detection probe Pd.

[0098] In addition, the pair of detection probes Pd in ​​the first embodiment contact a portion D1 of the welded workpiece 21 or a portion D2 of the electrode 22 that is located on or near one of the lines that start from the center of gravity of the polygon formed by the multiple welds 23a to 23d and pass through the midpoints of each side of the polygon.

[0099] 3, the potential gradient on the line passing from the center of gravity of the rectangle formed by welds 23a to 23d through the midpoints of each side is gentler than in the vicinity of welds 23a to 23d. For example, the same is thought to be true for measurement object 2 having welds that form polygons such as triangles and pentagons.

[0100] Therefore, according to the above configuration, a pair of detection probes Pd is positioned on or near one of the lines passing from the center of gravity of the polygon through the midpoints of each side, thereby suppressing a decrease in measurement accuracy due to positional misalignment of the pair of detection probes Pd.

[0101] 2A, the pair of detection probes Pd in ​​the first embodiment contact portions D1 and D2 of the workpiece 21 and electrode 22 that are positioned approximately equidistant from each of the welds 23a to 23d. Specifically, one of the detection probes Pd contacts portion D1 of the workpiece 21 that is positioned approximately equidistant from each of the welds 23a to 23d, and the other of the detection probes Pd contacts portion D2 of the electrode 22 that is positioned approximately equidistant from each of the welds 23a to 23d.

[0102] 3, the potential gradient is gentle at portions D1 and D2 of the workpiece 21 and electrode 22, which are positioned at approximately the same distance from each of the welds 23a to 23d. Therefore, with the above configuration, the composite voltage between the workpiece 21 and electrode 22 can be measured with high accuracy.

[0103] Furthermore, measurement device 1 may include memory unit 60 as a storage unit that stores a threshold value for determining the state of multiple welds 23 a to 23 d. In this case, when the composite voltage detected by detection circuit 50 exceeds the threshold value, control unit 20 generates status information indicating that the state of multiple welds 23 a to 23 d is good, as information indicating the state of multiple welds 23 a to 23 d.

[0104] According to this configuration, in the measuring device 1, the control unit 20 determines whether the condition of the plurality of welds 23a to 23d is good or not based on the composite voltage detected by the detection circuit 50. This eliminates the need for the user to determine whether the welding condition is good or bad, and allows the user to easily understand the welding condition.

[0105] Furthermore, the plurality of application circuits 40a to 40d in the first embodiment apply current in the same direction to different welding points, specifically to welding points corresponding to the application circuits.

[0106] With this configuration, the composite voltage increases monotonically as the number of poorly welded welds among welds 23a to 23d increases, making it easy to determine the number of poorly welded welds.

[0107] In the above embodiment, an example has been described in which each of the application circuits 40a to 40d applies a current to a single different welding point, but each of the application circuits 40a to 40d may apply a current to a plurality of different welding points. Therefore, hereinafter, an embodiment will be described in which a current is applied from the application unit 40 to each of a plurality of welding points.

[0108] Second Embodiment 6 is a diagram for explaining a method for measuring the states of the welded portions 23a to 23d in the second embodiment. The number of application circuits for applying current to the four welded portions 23a to 23d in the first embodiment is different from that in the first embodiment.

[0109] The measurement device 1A in the first embodiment has two application circuits 40a and 40b instead of the four application circuits 40a to 40d that constitute the measurement device 1 shown in Fig. 1. The detection circuit 50 has the same configuration as in the first embodiment, so it is denoted by the same reference numeral and a duplicated description will be omitted.

[0110] The two application circuits 40a and 40b apply current to the same number of different welds. In the first embodiment, the application circuit 40a applies current to the two welds 23a and 23b, and the application circuit 40b applies current to the two welds 23c and 23d that are different from the welds 23a and 23b.

[0111] With respect to a pair of application probes Pa1 connected to both ends of the application circuit 40a, one application probe contacts a portion of the welded workpiece 21 located near the weld 23b, and the other application probe contacts a portion of the electrode 22 located near the other weld 23a.

[0112] With respect to the pair of application probes Pa2 connected to both ends of the application circuit 40b, one application probe contacts a portion of the welded workpiece 21 located near the weld 23c, and the other application probe contacts a portion of the electrode 22 located near the other weld 23d.

[0113] In this way, one of the pair of application probes Pa1 or Pa2 comes into contact with a portion located near any one of welded portions 23b or 23c that is exclusively selected from the first N of the 2N welded portions 23a to 23d (N=2 in the first embodiment). The other of the pair of application probes Pa1 or Pa2 comes into contact with a portion located near any one of welded portions 23a or 23d that is exclusively selected from the remaining N of the 2N welded portions. Note that, although N=2 in the first embodiment, N may be a natural number of 3 or greater.

[0114] FIG. 7 is a block diagram showing the functional configuration of a measurement device 1A in the first embodiment.

[0115] The measurement device 1A includes a measurement device 110 and a measurement device 120. The measurement device 110 and the measurement device 120 are configured by, for example, a tester or a resistance meter.

[0116] Measuring device 110 includes measuring unit 30A and main body 100A in addition to application circuit 40a shown in Fig. 6. Measuring device 120 includes measuring unit 30B, temperature sensor 90, and main body 100B in addition to application circuit 40b and detection circuit 50 shown in Fig. 6.

[0117] Measurement units 30A and 30B have the same functions as measurement unit 30 shown in Fig. 1. In the first embodiment, each of main body units 100A and 100B is configured with operation unit 10, control unit 20, storage unit 60, display unit 70, and communication unit 80 shown in Fig. 1.

[0118] Temperature sensor 90 detects the temperature of at least one of welds 23a to 23d or the ambient temperature of the weld. Temperature sensor 90 generates a temperature signal indicating the magnitude of the detected temperature and outputs it to measurement unit 30B.

[0119] As in the first embodiment, the measurement unit 30B measures a composite voltage of the voltages indicating the voltage drops occurring at the welding zones 23a to 23d based on the detection signals output from the detection circuit 50. Furthermore, in the first embodiment, the measurement unit 30B executes a correction process to correct the measurement value of the composite voltage in accordance with the temperature signal from the temperature sensor 90.

[0120] Specifically, a correction table showing the relationship between the temperature of the welded portion and the correction amount of the composite voltage is stored in advance in storage unit 60 of main body 100B. In the correction table, for example, the correction amount is set to zero when the temperature of the welded portion is 25°C. Furthermore, as the temperature of the welded portion rises above 25°C, the correction amount becomes smaller than zero, and as the temperature of the welded portion falls below 25°C, the correction amount becomes larger than zero.

[0121] Then, when measurement unit 30B acquires a temperature signal from temperature sensor 90, it refers to the correction table stored in memory unit 60 and acquires a correction amount corresponding to the temperature indicated by the temperature signal. Measurement unit 30B calculates the measurement value of the composite voltage by adding the acquired correction amount to the voltage value of the composite voltage indicated by the detection signal.

[0122] In this way, measurement unit 30B corrects the measurement value of the composite voltage according to the temperature signal from temperature sensor 90. Measurement unit 30B outputs the corrected measurement value of the composite voltage to control unit 20 of main body 100B.

[0123] If the temperature fluctuation of the welded portions 23a to 23d is small, the above-described correction process may be omitted. Also, this correction process may be performed by the measurement unit 30 in the first embodiment.

[0124] Next, the relationship between the welding state of the welded portions 23a to 23d and the voltage value of the composite voltage in the first embodiment will be described with reference to FIG.

[0125] Fig. 8 is a diagram for explaining that the composite voltage changes depending on the welding state of the welds 23a to 23d. Fig. 8 illustrates the measurement results of the composite voltage when a direct current of 2.0 [A] is applied to the work 21 from each of the application circuits 40a and 40b.

[0126] 8, when the welding conditions of all four welds 23a to 23d are good, the composite voltage is 10.1 μV. When only weld 23a is defective, the composite voltage is 11.3 μV. When only weld 23b is defective, the composite voltage is 16.6 μV. When both welds 23b and 23d are defective, the composite voltage is 18.3 μV.

[0127] Therefore, when measuring unit 30B determines whether the welding conditions of all of welds 23a to 23d are good, the first threshold value used for the determination is set to, for example, 10.5 μV, taking into consideration measurement errors, etc. By setting the first threshold value in this manner, control unit 20 can determine that all of welds 23a to 23d are good when the measured value of the combined voltage exceeds the first threshold value.

[0128] Similarly, the second threshold for determining whether the two welds 23b and 23d are defective is set to, for example, 17 μV. Then, when the measured value of the combined voltage exceeds the second threshold, the control unit 20 can determine that the welds 23b and 23d are defective.

[0129] In this way, by obtaining the voltage values ​​of the composite voltage in all possible defective states that can occur in the welded portions 23a to 23d through experiments or simulations and determining each threshold value, it becomes possible to determine whether the welding state of each of the welded portions 23a to 23d is good or bad.

[0130] In the second embodiment, an example has been described in which current is applied exclusively to two welds from each of the application circuits 40a and 40b, but the second embodiment is not limited to this. For example, it is sufficient if the output current of one application circuit causes a voltage drop at each weld and the composite voltage changes when any of the welds is defective, so as long as this condition is met, a configuration in which current is applied to three or more welds from one application circuit may be used.

[0131] Next, the effects of the second embodiment will be described.

[0132] The measuring device 1A in the second embodiment measures the state of multiple welds 23a to 23d formed when a workpiece 21 is welded at multiple locations to an electrode 22 corresponding to the workpiece. The measuring device 1 includes multiple application circuits 40a and 40b that apply current exclusively to each of a plurality (e.g., two) of the welds 23a to 23d, the number of which is less than the total number of the welds 23a to 23d. The measuring device 1A also includes a detection circuit 50 that detects a composite voltage obtained by combining voltages that indicate the magnitude of voltage drops that occur at each of the multiple welds due to the application of current by the application circuits 40a and 40b, and a control unit 20 that outputs information indicating the state of the multiple welds 23a to 23d based on the composite voltage detected by the detection circuit.

[0133] In addition, a measurement method for measuring the states of the plurality of welds 23 a to 23 d in the second embodiment includes a plurality of application steps (S1) for applying current exclusively to each of the plurality of (e.g., two) welds, and a detection step (S2) for detecting the composite voltage described above by applying the current in the plurality of application steps. This measurement method further includes a processing step (S3) for outputting information indicating the states of the plurality of welds 23 a to 23 d based on the composite voltage detected in the detection step.

[0134] With these configurations, current is applied exclusively to each of the multiple welds, so the composite voltage generated by the voltage drop at each weld exhibits different values ​​depending on the state of the welds 23 a to 23 d. Therefore, by detecting the composite voltage, it is possible to determine whether the multiple welds 23 a to 23 d are defective.

[0135] Therefore, the measurement time for the plurality of welded portions 23a to 23d can be shortened compared to when the voltages generated at the welded portions 23a to 23d are detected at different times.

[0136] In addition, the measurement device 1A in the second embodiment includes application probes Pa1 and Pa2 that constitute multiple pairs of contacts connected to both ends of each of the application circuits 40a and 40b, and a detection probe Pd that constitutes another pair of contacts connected to both ends of the detection circuit 50.

[0137] One of the multiple pairs of application probes Pa1 and Pa2 comes into contact with a portion located near any one of the 2N welds (N is a natural number of 2 or more) exclusively selected from the first N welds among the multiple welds 23a to 23d. The other of the multiple pairs of application probes Pa1 and Pa2 comes into contact with a portion located near any one of the 2N welds exclusively selected from the remaining N welds.

[0138] It is desirable that the portion that comes into contact with one of the plurality of pairs of application probes Pa1 and Pa2 is one portion of the workpiece 21 and the electrode 22, and the portion that comes into contact with the other of the plurality of pairs of application probes Pa1 and Pa2 is the other portion of the workpiece 21 and the electrode 22. This configuration can improve measurement accuracy.

[0139] Specifically, one application probe of the pair of application probes Pa1 comes into contact with a portion of the welded workpiece 21 located near any one weld 23b that is exclusively selected from the first two welds 23b and 23c of the four welds 23a to 23d. One application probe of the pair of application probes Pa2 comes into contact with a portion of the welded workpiece 21 located near any one weld 23c that is exclusively selected from the first two welds 23b and 23c.

[0140] In addition, the other application probe of the pair of application probes Pa1 contacts a portion of the electrode 22 located near any one of the two remaining welds 23a and 23d that is exclusively selected from the remaining two welds 23a and 23d, and the other application probe of the pair of application probes Pa2 contacts a portion of the electrode 22 located near any one of the two remaining welds 23d that is exclusively selected from the remaining two welds 23a and 23d.

[0141] According to this configuration, as in the first embodiment, current flows through each of the welds 23a to 23d, and the voltage value of the composite voltage changes depending on the welding state of each of the multiple welds 23a to 23d, as shown in Fig. 8. Therefore, the quality of the welding state of the welds 23a to 23d can be determined depending on the magnitude of the composite voltage detected by the detection circuit 50.

[0142] In addition, in the second embodiment, the same configuration as in the first embodiment can achieve the same effects as in the first embodiment.

[0143] (Third embodiment) FIG. 9 is a diagram showing the configuration of a measurement system 1B for measuring the welded portions 23a to 23d of the measurement object 2 in the third embodiment.

[0144] Measurement system 1B includes probe group P, a plurality of current application devices 11a to 11d, voltage detection device 12, and information processing device 13. As with the first embodiment, probe group P of the third embodiment has four pairs of application probes Pa1 to Pa4 arranged to straddle four welds 23a to 23d, respectively. A pair of detection probes Pd is arranged to contact portions D1 and D2 of welded workpiece 21 and electrode 22, respectively, which are approximately equidistant between welds 23a to 23d.

[0145] The current application devices 11a to 11d are devices that apply current exclusively to one or more welding portions, and function as the application circuits 40a to 40d in the first embodiment, respectively.

[0146] In the third embodiment, current application device 11a applies a current to welded portion 23a through a pair of application probes Pa1, and current application device 11b applies a current to welded portion 23b through a pair of application probes Pa2. Furthermore, current application device 11c applies a current to welded portion 23c through a pair of application probes Pa3, and current application device 11d applies a current to welded portion 23d through a pair of application probes Pa4.

[0147] In this manner, the four current application devices 11a to 11d apply current exclusively to the welded portions 23a to 23d via the four pairs of application probes Pa1 to Pa4, respectively.

[0148] The voltage detection device 12 is a device that detects a combined voltage that indicates the magnitude of the voltage drop that occurs at each of the welds 23a to 23d due to the application of current by the current application devices 11a to 11d, and functions as the detection circuit 50 in the first embodiment. The voltage detection device 12 in the third embodiment detects a combined voltage that occurs between the pair of detection probes Pd due to the current applied to each of the welds 23a to 23d.

[0149] Information processing device 13 is a device that outputs information indicating the state of the plurality of welded zones based on the composite voltage detected by voltage detection device 12, and functions as measurement unit 30 in the first embodiment. Similar to the first embodiment, information processing device 13 in the third embodiment generates measurement information indicating the state of the plurality of welded zones 23a to 23d based on the detected composite voltage. Information processing device 13 then displays the measurement information, transmits it to an external device, and stores it.

[0150] In the third embodiment, an example has been described in which the four current application devices 11a to 11d exclusively apply current to the four welding portions 23a to 23d, but the present invention is not limited to this. For example, a configuration may be adopted in which at least one of the current application devices 11a to 11d exclusively applies current to the plurality of welding portions 23a to 23d.

[0151] In the third embodiment, the current application devices 11a to 11d apply a current exclusively to each of the four welds 23a to 23d, thereby generating measurement information indicating the states of the welds 23a to 23d. However, the present invention is not limited to this. For example, as in the second embodiment, measurement information indicating the states of the welds 23a to 23d may be generated by applying a current exclusively to each of the multiple welds.

[0152] Next, the effects of the third embodiment will be described.

[0153] Measurement system 1B in the third embodiment measures the state of multiple welds 23a to 23d formed when workpiece 21 is welded at multiple locations to electrode 22, which corresponds to the workpiece to be welded. Measurement system 1B includes one or more current application devices 11a to 11d that apply current exclusively to one or more of the four welds 23a to 23d, and voltage detection device 12 that detects a combined voltage that indicates the magnitude of voltage drops that occur at each weld due to the application of current by one or more current application devices 11a to 11d. Measurement system 1B also includes information processing device 13 that outputs information indicating the state of multiple welds 23a to 23d based on a combined voltage of the voltages that occur at each weld.

[0154] According to this configuration, as in the first and second embodiments, current is applied exclusively to one or more welds, and the composite voltage generated due to the voltage drop at each of the welds 23 a to 23 d exhibits a different value depending on the state of the welds 23 a to 23 d. Therefore, by detecting the composite voltage, it is possible to determine whether the multiple welds 23 a to 23 d are defective.

[0155] Therefore, the time required to measure the states of the plurality of welded portions 23a to 23d can be shortened compared to when the voltages generated at the welded portions 23a to 23d are detected at different times.

[0156] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0157] For example, in the above embodiment, four welds 23a to 23d are measured, but the number of welds to be measured may be two, three, five or more.

[0158] For example, in the above embodiment, the shape of the weldment 21 is a cross, but it may be a circle, an ellipse, or a rectangle.

[0159] Furthermore, although the measuring devices 1 and 1A in the above embodiments are provided with an operation unit 10, a display unit 70, and a communication unit 80, at least one of the functions of the operation unit 10, the display unit 70, and the communication unit 80 may be omitted from the measuring devices 1 and 1A. [Explanation of symbols]

[0160] 1. 1A measuring device 1B Measurement System 11a~11d Current application device 12 Voltage detection device 13 Information processing equipment 30, 30A, 30B Measuring section (processing section) 40a~40d Application circuit 50 Detection circuit Pa1 to Pa4: A pair of application probes (a pair of contacts in the application circuit) Pd Pair of detection probes (pair of contacts in the detection circuit)

Claims

1. A measuring device for measuring the state of a plurality of welds formed when a workpiece is welded to a workpiece at a plurality of locations, a plurality of application circuits that apply current to each of the one or more exclusively selected welded portions; a detection circuit for detecting a combined voltage representing the magnitude of a voltage drop occurring at each of the welded portions due to the application of the current; a processing unit that outputs information indicating the states of the plurality of welded portions based on the synthesized voltage; A measuring device comprising:

2. 2. The measuring device according to claim 1, a plurality of pairs of contacts connected to both ends of each of the application circuits; another pair of contacts connected to both ends of the detection circuit; the plurality of pairs of contacts contact portions of the welded material or the welded material in the vicinity of the plurality of welds, the other pair of contacts contacts a portion of the welded material or the workpiece that is farther from the plurality of welds than the portions that the plurality of pairs of contacts contact, respectively; Measuring device.

3. 3. The measuring device according to claim 2, the other pair of contacts contacts a portion of the welded material or the welded material located on or near any one of the lines passing through the center of gravity of a polygon formed by the plurality of welds to the midpoints of each side of the polygon; Measuring device.

4. The measuring device according to claim 2 or 3, the other pair of contacts contacts portions of the weldment and the workpiece that are positioned approximately equidistant from each of the welds; Measuring device.

5. The measuring device according to claim 2 or 3, one of the plurality of pairs of contacts contacts a portion located near any one of the welds that is exclusively selected from the first N of 2N welds (N is a natural number of 2 or more) among the plurality of welds, and the other of the plurality of pairs of contacts contacts a portion located near any one of the welds that is exclusively selected from the remaining N of the 2N welds. Measuring device.

6. The measuring device according to any one of claims 1 to 3, a storage unit that stores a threshold value for determining the state; When the voltage detected by the detection circuit exceeds the threshold value, the processing unit generates, as the information, status information indicating that the plurality of welds are in a good state. Measuring device.

7. The measuring device according to any one of claims 1 to 3, The plurality of application circuits respectively apply the current to different one or more welding portions in the same direction. Measuring device.

8. A measurement method for measuring the state of a plurality of welds formed when a workpiece is welded to a workpiece at a plurality of locations, comprising: a plurality of applying steps of applying a current to each of the one or more exclusively selected welds; a detection step of detecting a combined voltage of voltages indicating the magnitude of a voltage drop occurring at each of the one or more welded portions due to the application of the current; a processing step of outputting information indicating the states of the plurality of welds based on the synthesized voltage; Measurement methods including:

9. A measurement system for measuring the states of a plurality of welds formed when a workpiece is welded to a plurality of locations, one or more current application devices that apply current to each of the one or more exclusively selected welded portions; a voltage detection device that detects a combined voltage indicating the magnitude of a voltage drop that occurs at each of the welded portions due to the application of the current; an information processing device that outputs information indicating the states of the plurality of welded portions based on the synthesized voltage; A measurement system comprising:

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