JP6428887B1 - Welding state detection method and welding state detection device - Google Patents

Abstract

The present invention provides a welding state detection method that makes it easy to grasp the welding state of a sheet member.
A welding state detection method includes a plurality of conductive lead portions 103 overlapped with each other, and the overlapped portion is welded in a strip shape extending in a predetermined X-axis direction. A welding state detection method for detecting a state, wherein (a) a plurality of pairs of probes Pu and Pd are respectively arranged at a plurality of positions aligned in a line along the X-axis direction in a welding region 105 which is a belt-shaped region. Contacting one side of the tab terminal 104 and contacting the other side of the pair of probes Pu and Pd to the other side of the tab terminal 104; and (b) both sides of the tab terminal 104 at the plurality of locations. And measuring a resistance value between the pair of probes Pu and Pd in contact with each other.
[Selection] Figure 2

Description

The present invention relates to a welding state detection method and a welding state detection device for detecting a welding state of a sheet member.

  Conventionally, pressure is applied by sandwiching two materials to be bonded between a horn and an anvil that give ultrasonic vibrations, and applying ultrasonic vibration parallel to the contact surface of these materials to be solid-phase bonded, An ultrasonic bonding apparatus is known in which a voltage is applied between a horn and an anvil, a current flowing between the horn and the anvil is measured, a contact resistance is calculated from a measured value of the applied voltage and the current, and a bonding state is determined ( For example, see Patent Document 1.)

JP 2008-142739 A

  Incidentally, in recent years, for example, an electrode plate of a battery such as a lithium secondary battery is welded at its end portion to form a tab terminal. In such a case, it is welded in a strip shape so as to cross the tab terminal. Therefore, the area of the region to be welded is increased. When the contact resistance of a member welded in a wide area is measured using the above-described technique, even if a part of the weld area is not welded, the contact resistance as a whole is low, There was a problem that a partial defect in the welded area could not be detected.

  An object of the present invention is to provide a welding state detection method that makes it easy to grasp the welding state of a sheet member.

  The welding state detection method according to the present invention detects the state of welding in a sheet member in which a plurality of conductive sheets are overlapped with each other and the overlapped portions are welded in a belt shape extending in a predetermined first direction. In the welding state detecting method, (a) in the welding region which is the belt-welded region, one of a pair of probes is respectively connected to the sheet member at a plurality of positions aligned in a row along the first direction. Contacting the other surface of the sheet member and contacting the other surface of the sheet member with the other surface of the sheet member; and (b) a pair of probes in contact with both surfaces of the sheet member at the plurality of locations, respectively. And measuring a resistance value between.

  According to this method, the resistance value in the thickness direction of the sheet member can be measured at a plurality of locations arranged in a line in the welding region of the sheet member to which the sheet is welded. Since the resistance value in the thickness direction of the sheet member reflects the welded state of the sheet member, the user can easily grasp the welded state of the sheet member from the resistance values obtained in a plurality of places. It becomes.

  (C) In a plurality of locations arranged along one or a plurality of rows substantially parallel to the one row in the welding region, respectively, one of the pair of probes is brought into contact with one surface of the sheet member, and the pair of pairs A step of bringing the other of the probes into contact with the other surface of the sheet member, and (d) between a pair of probes in contact with both surfaces of the sheet member, respectively, at a plurality of locations arranged along the one or more rows. It is preferable to further include a step of measuring a resistance value.

  According to this method, it becomes easy to grasp the welded state of the sheet member with respect to the region extending in a two-dimensional plane.

  In addition, it is preferable that each probe includes two contacts, and in the step (b), the resistance value is measured by a four-terminal measurement method using four contacts included in the pair of probes.

  According to this method, since the resistance value can be measured by the four-terminal measurement method, the accuracy of measurement of the resistance value measured at a plurality of locations arranged in a line in the welding region of the sheet member is improved. As a result, it becomes easy to accurately grasp the welded state of the sheet member.

  Each probe includes two contacts, and in the step (b) and the step (d), the resistance value is measured by a four-terminal measurement method using four contacts included in the pair of probes. It is preferable to do.

  According to this method, the measurement accuracy of the resistance value of the welded region in the region expanded in a planar shape by the four-terminal measurement method is improved. As a result, it becomes easy to accurately grasp the welding state of the sheet member in a planar shape.

  Preferably, a plurality of pairs of probes are provided, and in the step (a), a plurality of pairs of probes corresponding to the plurality of locations are brought into contact with the sheet member, respectively.

  According to this method, since a plurality of pairs of probes can be simultaneously brought into contact with a plurality of locations on the measurement target, it is not necessary to sequentially move the probes to the measurement target location. Therefore, it becomes easy to shorten the time for measuring the resistance values at a plurality of locations.

  In addition, it is preferable that a plurality of pairs of probes are provided, and in the steps (a) and (c), a plurality of pairs of probes corresponding to the plurality of locations are brought into contact with the sheet member, respectively.

  According to this method, a plurality of pairs of probes can be simultaneously brought into contact with a plurality of locations extending in a planar shape of the measurement target, so that it is not necessary to sequentially move the probes to the measurement target location. Therefore, it becomes easy to shorten the time for measuring resistance values at a plurality of locations distributed in a planar shape.

  It is preferable that the method further includes (e) determining whether the welded state is good or not based on a resistance value measured between the pair of probes.

  According to this method, since the quality of the welded state is determined based on the resistance values of a plurality of locations distributed in the welded region in the sheet member, partial welding failure compared to the case based on the resistance value of the entire welded region Easy to find.

  The step (e) calculates an average value and a standard deviation of the measured resistance values, determines whether each measured resistance value is good or bad based on the average value and the standard deviation, If there is a resistance value determined to be, it is preferable to determine that a welding failure has occurred at a location where the resistance value determined to be defective is measured.

  According to this method, since it is determined whether or not the welding is defective based on the average value and the standard deviation of the resistance values, it is not necessary to set a reference value for determination in advance. Therefore, convenience for the user is improved.

  And (f) further including a step of displaying the resistance value measured between the pair of probes by a graph in which one axis corresponds to the plurality of locations and the other axis corresponds to the resistance value. preferable.

  According to this method, the user can grasp a portion where the resistance has an abnormal value at a glance, that is, a portion where welding is insufficient.

  Moreover, it is preferable that a some sheet | seat is a part of electrode plate of a battery, and the said sheet | seat member is a tab terminal of the said battery.

  According to this method, it becomes easy to grasp the welding state of the tab terminal of the battery.

  The welding state detection method having such a configuration makes it easy to grasp the welding state of the sheet member.

It is a conceptual diagram which shows roughly the structure of the welding state detection apparatus using the welding state detection method which concerns on one Embodiment of this invention. It is a block diagram which shows notionally the electrical structure of the welding state detection apparatus shown in FIG. It is a flowchart which shows an example of operation | movement of the welding state detection apparatus based on the welding state detection method which concerns on one Embodiment of this invention. It is a flowchart which shows an example of operation | movement of the welding state detection apparatus based on the welding state detection method which concerns on one Embodiment of this invention. It is explanatory drawing which shows an example of the graph displayed by the alerting | reporting part shown in FIG.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. FIG. 1 is a conceptual diagram schematically showing a configuration of a welding state detection apparatus 1 using a welding state detection method according to an embodiment of the present invention. A welding state detection device 1 shown in FIG. 1 is a device that detects a welding state of a tab terminal of a lithium ion secondary battery, which is an example of an inspection object.

  A lithium ion secondary battery 100 shown in FIG. 1 includes a plurality of positive plates 101 (electrode plates) and a plurality of negative plates 111 (electrode plates) stacked alternately with a not-shown separator interposed therebetween. It is configured. The positive electrode plate 101 is configured by applying a positive electrode active material (not shown) to the surface of a positive electrode current collector 102 made of a metal foil such as an aluminum foil. The negative electrode plate 111 is configured by applying a negative electrode active material (not shown) to the surface of a negative electrode current collector 112 made of a metal foil such as an aluminum foil.

  A part of each positive electrode current collector 102 is drawn out as a lead portion 103 (a part of a sheet or an electrode plate) to one end side of the lithium ion secondary battery 100, and a part of each negative electrode current collector 112 is a lead. It is drawn out as a part 113 (a sheet, a part of the electrode plate). Each lead portion 103 is pulled out toward one side of the one end, and each lead portion 113 is pulled out toward the opposite side to the lead portion 103. This prevents the lead portion 103 and the lead portion 113 from overlapping.

  The respective lead portions 103 are laminated and adhered, and are welded to each other in a welding region 105 indicated by a strip-shaped netting to form a positive tab terminal 104. The lead portions 113 are laminated and adhered to each other, and are welded to each other at a welding region 115 indicated by a strip-shaped netting to form a negative tab terminal 114 (sheet member, tab terminal). Various welding methods can be applied as the welding method of the welding regions 105 and 115, and for example, ultrasonic welding is used. In FIG. 1, the state before each lead part 103 and 113 is welded is shown.

  The welding state detection apparatus 1 shown in FIG. 1 has detection units 4U and 4D, a detection processing unit 5, a notification unit 6, and a lithium ion secondary battery 100 to be inspected at a predetermined position between the detection units 4U and 4D. And a battery holding part (not shown) for holding. The detection units 4U and 4D include detection jigs 3U and 3D. The detection units 4U and 4D can move the detection jigs 3U and 3D in the three axis directions X, Y, and Z orthogonal to each other by a drive mechanism (not shown). It can be rotated around an axis.

  The notification unit 6 is a notification device that visually notifies the user of the information obtained by the detection processing unit 5. As the notification unit 6, for example, a display device such as a liquid crystal display device or a printer can be used.

  The detection unit 4U is located above the lithium ion secondary battery 100 fixed to a battery holding unit (not shown). The detection unit 4D is located below the lithium ion secondary battery 100 fixed to a battery holding unit (not shown). The detection units 4U and 4D are configured to be detachable from detection jigs 3U and 3D for sequentially bringing the probes Pu and Pd into contact with the tab terminals 104 and 114 of the lithium ion secondary battery 100, respectively. The detection jigs 3U and 3D may be able to simultaneously contact the probes Pu and Pd with the two tab terminals 104 and 114 at the same time. A probe attached to the detection jig 3U located above is referred to as a probe Pu, and a probe attached to the detection jig 3D located below is referred to as a probe Pd. Hereinafter, the detection units 4U and 4D are collectively referred to as the detection unit 4, and the probes Pu and Pd are collectively referred to as the probe P.

  Each of the detection jigs 3U and 3D includes a support member 31 that holds the tips of the plurality of probes Pu and Pd toward the welding regions 105 and 115 of the tab terminals 104 and 114, and a base plate 321. The base plate 321 is provided with unillustrated electrodes that are in contact with the rear end portions of the probes Pu and Pd to be conductive. The detection units 4U and 4D electrically connect the rear ends of the probes Pu and Pd to the detection processing unit 5 through the respective electrodes of the base plate 321 and connection circuits 41U and 41D described later, or connect the connections. Switch.

  The probes Pu and Pd have a substantially rod-like shape as a whole. The support member 31 is formed with a plurality of through holes that support the probes Pu and Pd. The support member 31 has a shape and a size corresponding to the welding regions 105 and 115. The support member 31 supports the probes Pu and Pd so that the plurality of probes Pu and Pd are brought into contact with the welding region 105 or substantially the entire region in the welding region 115 with a substantially uniform distribution. The plurality of probes Pu and Pd are arranged so as to correspond to the intersection position of the lattice, for example.

  The detection jigs 3U and 3D are configured in the same manner except that the attachment directions to the detection units 4U and 4D are upside down. Hereinafter, the detection jigs 3U and 3D are collectively referred to as a detection jig 3. The detection jig 3 can be replaced in accordance with the lithium ion secondary battery 100 to be inspected.

  FIG. 2 is a block diagram conceptually showing the electrical configuration of the welding state detection apparatus 1 shown in FIG. The welding state detection apparatus 1 illustrated in FIG. 2 includes, for example, N probes Pu1 to PuN, N probes Pd1 to PdN, connection circuits 41U and 41D, and a detection processing unit 5. The detection processing unit 5 includes, for example, a power supply circuit 51, a voltage detection unit 52, a control unit 53, and the like. FIG. 2 shows a state in which the probes Pu1 to PuN and Pd1 to PdN are brought into contact with the tab terminal 104.

  The tab terminal 104 shown in FIG. 2 is shown in a cross section obtained by cutting the tab terminal 104 shown in FIG. 1 along the X-axis direction. Probes Pu1 to PuN and Pd1 to PdN are obtained by assigning probe numbers to each row of probes Pu and Pd arranged along the X-axis direction. The probe numbers given to the probes Pu and Pd correspond to the X coordinate in the X-axis direction indicating the position of the welding region 105 in contact with each probe P.

  In addition to the probe P shown in FIG. 2, the probes Pu and Pd are provided in a plurality of rows adjacent to and parallel to the Y-axis direction, but are not shown. By assigning a number to each column of the probe P, the number of the column corresponds to the Y coordinate in the Y-axis direction that indicates the position of the welding region 105 in contact with each probe P. Each row of the probes P does not necessarily have to be a straight row, and may be a row that is zigzag, bent, or scattered.

  Each probe P includes two contacts for a four-terminal measurement method. That is, each probe P includes a contact Ti for supplying current and a contact Tv for measuring voltage. As described above, as a probe having two contacts, for example, a probe in which two needle pins (contacts) are paired as described in JP-A-2006-329998, for example, A coaxial probe composed of a cylindrical first contact and a second contact inserted into the first contact, as described in Japanese Unexamined Patent Publication No. 2012-154670, can be used. Alternatively, each of the rod-shaped probes arranged in a lattice shape may be used as a contact, and two probes (contacts) may be used as a set and used as one probe.

  The connection circuit 41U is connected to each electrode of the base plate 321 in the detection jig 3U, the positive terminal of the power supply circuit 51, and the positive terminal of the voltage detection unit 52. The connection circuit 41D is connected to each electrode of the base plate 321 in the detection jig 3D, the negative terminal of the power supply circuit 51, and the negative terminal of the voltage detection unit 52. The connection circuits 41U and 41D are configured using, for example, a plurality of switching elements.

  Then, the connection circuits 41U and 41D select a pair of probes Pu and Pd facing each other with the tab terminal 104 interposed therebetween in accordance with a control signal from the control unit 53, and the contact circuits Ti of the selected probe Pu are selected. The positive electrode of the power supply circuit 51 is connected to the contactor Tv of the probe Pu, the positive electrode of the voltage detector 52 is connected to the contactor Ti of the probe Pd, the negative electrode of the power supply circuit 51 is connected to the contactor Tv of the probe Pd. Connecting.

  The power supply circuit 51 is a constant current power supply circuit such as a switching power supply circuit. The power supply circuit 51 outputs a constant DC current I set in advance according to a control signal from the control unit 53. The voltage detection unit 52 is a voltage measurement circuit configured using, for example, a voltage dividing resistor or an analog / digital converter. The voltage detector 52 measures the voltage V between the contact Tv of the probe Pu and the contact Tv of the probe Pd in the pair of probes Pu and Pd selected by the connection circuits 41U and 41D, and the measured value Is transmitted to the control unit 53.

  The control unit 53 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a RAM (Random Access Memory) that temporarily stores data, a storage device that stores a predetermined control program, and peripheral circuits thereof And so on. The control unit 53 functions as the detection control unit 531, the measurement unit 532, the determination unit 533, and the graphing unit 534, for example, by executing the above-described control program.

  The detection control unit 531 controls the drive mechanism (not shown) to move and position the detection units 4U and 4D, and sequentially contacts the tips of the probes Pu and Pd to the welding regions 105 and 115 of the lithium ion secondary battery 100. (Steps (a) and (c)). Note that the detection jigs 3U and 3D may include the number of probes Pu and Pd that can simultaneously contact the welding regions 105 and 115, and the probes Pu and Pd may be simultaneously contacted with the welding regions 105 and 115.

  In this state, the measurement unit 532 is for inspection in a direction penetrating the welding regions 105 and 115 at the contact positions of the probes Pu and Pd in the welding regions 105 and 115 via the probes Pu and Pd of the detection jig 3. Current I is supplied, and based on the voltage V obtained from the pair of front and back probes Pu and Pd, the resistance R = V / I in the thickness direction of the welding regions 105 and 115 at each contact position is calculated. Thereby, the measurement part 532 can measure the resistance value between a pair of probe P in each contact position (process (b), (d)).

  In this case, each probe P includes the contacts Ti and Tv, and the current supply and the voltage measurement are performed by different contacts. Therefore, resistance measurement by the four-terminal measurement method is possible. As a result, resistance measurement accuracy is improved.

  The welding state detection apparatus 1 may include a current measurement circuit that measures the current I output from the power supply circuit 51, and may calculate the resistance R based on the current I measured by the current measurement circuit. Further, when the current I is a fixed value, the voltage V may be used as information indicating the resistance value as it is.

  The determination unit 533 determines the quality of the welded state of the tab terminals 104 and 114 based on the resistance R measured between each pair of probes P by the measurement unit 532 (step (e)). The graphing unit 534 graphs the resistance R measured between each pair of probes P so that one axis corresponds to a plurality of measurement locations and the other axis corresponds to the resistance R, and the graph is notified. Displayed by the unit 6.

  Next, operation | movement of the welding state detection apparatus 1 comprised as mentioned above is demonstrated. 3 and 4 are flowcharts showing an example of the operation of the welding state detection apparatus 1 based on the welding state detection method according to the embodiment of the present invention.

  First, the detection control unit 531 controls the drive mechanism (not shown) to move and position the detection units 4U and 4D, and brings the tips of the probes Pu into contact with the upper surface of the welding region 105 in the lithium ion secondary battery 100, The tip of each probe Pd is brought into contact with the lower surface of the welding region 105 (step S1: steps (a) and (c)).

  Next, the detection control unit 531 initializes variables j and k to 1 (step S2). The variable j is a variable indicating the number of the probes P arranged in the X-axis direction, that is, the X coordinate. The variable k is a variable indicating the column number of the probe P, that is, the Y coordinate. Hereinafter, the probes Pu and Pd that are in contact with the tab terminal 104 at the coordinates (j, k) of the welding region 105 are referred to as probes Pu (j, k) and probes Pd (j, k), respectively. Further, the number of probes Pu and Pd aligned along the X axis is N, and the number of probes Pu and Pd aligned along the Y axis is M.

  In FIG. 2, for example, the probes Pu (1,1) to Pu (N, 1) and the probes Pd (1,1) to Pd (N, 1) in the first row are replaced with the probes Pu1 to PuN and the probes Pd1 to Pd1. It is written as PdN, and the description of the probe P in other columns is omitted.

  Next, the detection control unit 531 connects the contacts Ti of the probes Pu (j, k) and Pd (j, k) to the power supply circuit 51 using the connection circuits 41U and 41D, and the probes Pu (j, k), The contact Tv of Pd (j, k) is connected to the voltage detection unit 52.

  Then, the measurement unit 532 uses the power supply circuit 51 to penetrate the welding region 105 in the thickness direction between the contact Ti of the probe Pu (j, k) and the contact Ti of the probe Pd (j, k). Current I, and the voltage between the contact Tv of the probe Pu (j, k) and the contact Tv of the probe Pd (j, k), that is, the voltage V (j at the coordinate (j, k). , K) is measured by the voltage detector 52 (step S3).

Next, the measurement unit 532 calculates the resistance R (j, k) in the thickness direction of the welded region 105 at the coordinates (j, k) based on the following equation (1) (step S4).
Resistance R (j, k) = V (j, k) / I (1)

  Next, the measurement unit 532 compares the variable j with the number of probes N in the X-axis direction (step S5). If the variable j does not satisfy the number of probes N (YES in step S5), the resistance R is still measured. Since the remaining coordinate position remains, 1 is added to the variable j to measure the resistance R at the new coordinate position (step S6), and the processing from step S3 is repeated again.

  On the other hand, if the variable j is not less than the number of probes N (NO in step S5), the resistance R has been measured for the column whose Y coordinate is k, and therefore the measurement unit 532 sets the variable k in the Y-axis direction. Is compared with the number M of probe rows (step S7). If the variable k is not less than the number M of probe rows (YES in step S7), the Y coordinate row for which the resistance R has not yet been measured remains, so the measurement unit 532 uses the new Y coordinate (probe row). 1) is added to the variable k to measure the resistance R (step S8), and the processing from step S3 onward is repeated again.

  On the other hand, if the variable k is not less than the number M of probe rows (NO in step S7), resistors R (1,1) to R (N, M) corresponding to all coordinates (1,1) to (N, M). ), The process proceeds to step S9.

  As described above, steps S2 to S8 correspond to an example of the steps (b) and (d).

  When a plurality of lead portions 103 are normally welded in the welding region 105, the current I supplied from the power supply circuit 51 is approximately in the thickness direction of the welding region 105 as shown by a current path A in FIG. 2. It flows in the shortest distance. On the other hand, when there is a defect in the welding of the lead portion 103 at coordinates (j, k) and there is a welding defect F that is not normally welded, the current I supplied from the power supply circuit 51 is as shown in FIG. As indicated by the current paths B and C, the current flows so as to bypass the welding defect F, and the path through which the current flows becomes longer than the current path A.

  Therefore, the resistance R tends to be smaller as the welded state is better, and larger as the welded state is worsened. Therefore, by acquiring the resistances R (1,1) to R (N, M) at the coordinates (1,1) to (N, M) in the welding region 105, the welding state of each part of the welding region 105 is changed to the resistance R. It is possible to estimate from (1,1) to R (N, M).

  Therefore, according to steps S1 to S8, resistances R (1,1) to R (N, M) are based on a plurality of probes Pu and Pd that are in contact with substantially the entire region of the welding region 105 in a substantially uniform distribution. And the welding state of each part of the welding region 105 is reflected in the resistances R (1, 1) to R (N, M). Therefore, the user can easily grasp the welding state of the tab terminal 104 over substantially the entire welding region 105 from the resistances R (1, 1) to R (N, M) obtained in steps S1 to S8. It becomes.

  Next, the graphing unit 534 sets the resistances R (1, 1) to R (N, M) to the X coordinate on the horizontal axis, that is, the number j in the X axis direction of the probe P, and the resistance R (1) on the vertical axis. , 1) to R (N, M) are displayed by the notification unit 6 (step S9: step (f)).

  FIG. 5 is an explanatory diagram illustrating an example of a graph displayed by the notification unit 6 illustrated in FIG. 1. In the graph shown in FIG. 5, the horizontal axis represents the X coordinate of 1 to N, and the vertical axis represents the resistance R. Further, the Y coordinate corresponding to the column number of the probe P is indicated by a plurality of broken lines Y1, Y2, Y3 to YM. According to the graph shown in FIG. 5, the user can grasp the coordinates of the portion where the resistance R has an abnormal value at first glance, that is, the portion where the welding is insufficient.

  Next, the determination unit 533 calculates the average value Av and the standard deviation σ of the resistors R (1, 1) to R (N, M) (step S11). Next, the determination unit 533 initializes variables j and k to 1 (step S12).

  Next, the determination unit 533 compares the resistance R (j, k) and (Av + 3σ) (step S13). If the resistance R (j, k) is larger than (Av + 3σ) (YES in step S13), that is, If the difference between the resistance R (j, k) and the average value Av is larger than 3σ, it is determined that a welding failure has occurred at the position of the coordinate (j, k) (step S14), and the determination result is notified to the notification unit 6. And the process proceeds to step S15. On the other hand, if the resistance R (j, k) is equal to or less than (Av + 3σ) (NO in step S13), the process proceeds to step S15 without executing step S14.

  Next, the determination unit 533 compares the variable j with the number of probes N in the X-axis direction (step S15). If the variable j does not satisfy the number of probes N (YES in step S5), the determination is still good. Since no resistor R remains, 1 is added to the variable j to determine whether the new resistor R is good or bad (step S16), and the processing after step S13 is repeated again.

  On the other hand, if the variable j is not less than the number of probes N (NO in step S15), since the resistance R has been evaluated for the column whose Y coordinate is k, the determination unit 533 sets the variable k in the Y-axis direction. Comparison is made with the number M of probe rows (step S17). If the variable k is not less than the number M of probe rows (YES in step S17), the Y coordinate row for which the resistance R has not yet been evaluated remains, and therefore the determination unit 533 determines a new Y coordinate (probe row). 1) is added to the variable k in order to evaluate the resistance R (step S18), and the processing after step S13 is repeated again.

  On the other hand, if the variable k is not less than the number M of probe rows (NO in step S17), resistors R (1,1) to R (N, M) corresponding to all coordinates (1,1) to (N, M). ), The process proceeds to step S19.

  As described above, according to steps S11 to S18, it is possible to detect a welding failure and specify the coordinates of the failure occurrence location. In step S13, the determination unit 533 has shown an example in which a welding failure is determined when the difference between the resistance R (j, k) and the average value Av is greater than 3σ. For example, the resistance R (j, k) If the difference between the average value Av and the average value Av is greater than 2σ or greater than 2.5σ, it may be determined that the welding is defective, and a multiple of σ may be set as appropriate.

  Since the determination unit 533 determines whether or not the welding is defective based on the average value Av and the standard deviation σ, it is not necessary to set a reference value for determination in advance. Therefore, convenience for the user is improved. Note that a determination reference value for determining whether or not the welding is defective is stored in the storage device in advance, and the determination unit 533 determines in step S13 that the resistance R (j, k) is greater than the determination reference value. It is good also as a structure which transfers to step S14.

  In step S19, the determination unit 533 checks whether or not there is a coordinate determined to be a welding failure in step S14. If there is no welding failure (YES in step S19), the welding state of the tab terminal 104 is determined. It determines with it being favorable (step S20), the determination result is displayed by the alerting | reporting part 6, and a process is complete | finished.

  On the other hand, if there is even one welding failure (NO in step S19), it is determined that the welding state of the tab terminal 104 is defective (step S21), the determination result is displayed by the notification unit 6, and the process is terminated. .

  As described above, according to steps S <b> 19 to S <b> 21, it is possible to determine whether or not the entire tab terminal 104 is welded, and the tab terminal 104 can be inspected. Hereinafter, by performing Steps S1 to S21 for the tab terminal 114 instead of the tab terminal 104, the welding state of the tab terminal 114 can be detected and inspected. When the probes Pu and Pd are simultaneously brought into contact with the welding regions 105 and 115 by the detection jigs 3U and 3D, the welding state of the tab terminals 104 and 114 can be detected and inspected at a time.

  Note that the determination unit 533 does not necessarily have to execute Steps S19 to S21. Moreover, the welding state detection apparatus 1 does not include the determination unit 533 and does not need to execute steps S11 to S21. Further, the graphing unit 534 is not provided, and step S9 may not be executed.

  Further, the support member 31 is not limited to an example of holding a plurality of rows of probes Pu and Pd, and may be configured to hold a row of probes Pu and Pd. The support member 31 may be configured such that one row of the probes Pu and Pd is brought into contact with the welding regions 105 and 115 with a substantially uniform distribution over the entire length in the longitudinal direction. In this case, Steps S7, S8, S17, and S18 may not be executed, and the variable k may be fixed to 1.

  Moreover, although each probe P was provided with the contacts Ti and Tv and the resistance R was measured by the four-terminal measurement method, each probe P was used as a single contact (probe) and the four-terminal measurement method was not performed. Each probe P may serve as both current supply and voltage measurement.

  In addition, the detection jigs 3U and 3D are each provided with a plurality of probes Pu and Pd in a multi-needle shape, and the plurality of probes Pu and Pd are simultaneously brought into contact with the tab terminals 104 and 114. 3U and 3D may include a pair of movable so-called flying probes Pu and Pd, and measure the resistance R at each coordinate position by sequentially contacting the pair of probes Pu and Pd to the above-described coordinate points. .

  The tab terminals 104 and 114 are not limited to the tab terminals of the lithium ion secondary battery, but may be tab terminals of other batteries. Further, the sheet member is not limited to the tab terminal of the battery, and any sheet member may be used as long as a plurality of sheets are overlapped and welded to each other.

DESCRIPTION OF SYMBOLS 1 Welding state detection apparatus 3, 3U, 3D Detection jig | tool 4, 4U, 4D Detection part 5 Detection processing part 6 Notification part 31 Support member 41U, 41D Connection circuit 51 Power supply circuit 52 Voltage detection part 53 Control part 100 Lithium ion secondary Battery (battery)
101 Positive electrode plate (electrode plate)
102 Positive electrode current collector 103, 113 Lead part (sheet, part of electrode plate)
104,114 Tab terminal (sheet member)
105, 115 welding region 111 negative electrode plate (electrode plate)
112 Negative electrode current collector 321 Base plate 531 Detection control unit 532 Measurement unit 533 Determination unit 534 Graphing units A, B, C Current path Av Average value F Welding defect I Current M Probe row number N Probe number P, Pu, Pd Probe R Resistance (resistance value)
Ti, Tv Contactor V Voltage σ Standard deviation

Claims (9)

A welding state detection method for detecting the welding state in a sheet member in which a plurality of conductive sheets are overlapped with each other and the overlapped portion is welded in a strip shape extending in a predetermined first direction,
(A) In the welding region, which is a region welded in a belt shape, each of a plurality of probes arranged in a line along the first direction is in contact with one surface of the sheet member, Bringing the other of the pair of probes into contact with the other surface of the sheet member;
(B) measuring the resistance value between the pair of probes in contact with both surfaces of the sheet member, respectively, at the plurality of locations;
(E) said at a plurality of locations, respectively, the quality of the welding conditions at the location where the resistance value is measured, see contains a determining step on the basis of the resistance value,
The step (e) calculates an average value and a standard deviation of the measured resistance values, determines whether each measured resistance value is good or bad based on the average value and the standard deviation, and determines that it is defective. If there is a resistance value determined, a welding state detection method for determining that a welding failure has occurred at a location where the resistance value determined to be defective is measured .   In the step (e), the quality of the welded state at each of the plurality of locations where the resistance value is measured is determined based on the resistance value measured between the pair of probes. 2. The welding state detection method according to 1. (C) In a plurality of locations arranged along one or more rows substantially parallel to the one row in the welding region, respectively, one of the pair of probes is brought into contact with one surface of the sheet member, Bringing the other into contact with the other surface of the sheet member;
(D) The method further includes a step of measuring a resistance value between a pair of probes in contact with both surfaces of the sheet member at a plurality of locations arranged along the one or more rows. Welding state detection method. Each probe includes two contacts;
The welding state detection method according to claim 1, wherein in the step (b), the resistance value is measured by a four-terminal measurement method using four contacts included in the pair of probes. A plurality of pairs of the probes are provided,
The welding state detection method according to any one of claims 1 to 4, wherein in the step (a), a plurality of pairs of probes corresponding to the plurality of locations are brought into contact with the sheet member, respectively. A plurality of pairs of the probes are provided,
The welding state detection method according to claim 3, wherein in the step (a) and the step (c), a plurality of pairs of probes corresponding to the plurality of locations are brought into contact with the sheet member, respectively. (F) The method further includes a step of indicating the resistance value measured between the pair of probes by a graph in which one axis corresponds to the plurality of locations and the other axis corresponds to the resistance value. The welding state detection method according to any one of 6 . The plurality of sheets are part of the battery electrode plate,
The sheet member is welded state detecting method according to any one of claims 1 to 7 which is a tab terminal of the battery. The welding state detection apparatus using the welding state detection method of any one of Claims 1-8 .

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