KR20230021474A - Welding inspection deviec of battery and welding inspection method of battery - Google Patents

Abstract

According to the present invention, a welding inspection device for a battery comprises: a first probe and a second probe which touch a welded portion of a battery can and a battery tab from the inside and outside of the battery can, with the welded portion between the first probe and the second probe, during inspection; and a measuring unit connected to the first probe and the second probe to measure the resistance of the welded portion. The first probe and the second probe each include: a cylindrical first contact; and a second contact coaxially installed in the inner space of the first contact. The diameter of the first contact of the second probe is larger than that of the first contact of the first probe. The area of the tip of the second contact of the second probe is more than 90 % of the area of the welded portion. The total area of the tip of the first contact and the second contact of the second probe is larger than the area of the welded portion. Therefore, the welding inspection device can reliably evaluate the welding strength of the welded portion by using microresistance.

Description

Battery welding inspection device and welding inspection method {WELDING INSPECTION DEVIEC OF BATTERY AND WELDING INSPECTION METHOD OF BATTERY}

The present invention relates to a welding inspection device and a welding inspection method of a battery capable of nondestructively measuring the welding strength of a battery tab.

Secondary batteries are also classified according to the structure of the positive electrode, the negative electrode, and the electrode assembly of the separator structure interposed between the positive electrode and the negative electrode. Typically, long sheet-type positive electrodes and negative electrodes are wound with a separator interposed therebetween. A jelly-roll (wound type) electrode assembly in one structure, a stack type (laminated type) electrode assembly in which a plurality of cathodes and anodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, anodes and cathodes in a predetermined unit and a stack-folding type electrode assembly having a structure in which unit cells such as a bi-cell or a full cell are stacked with a separator interposed therebetween.

Among them, the jelly-roll type electrode assembly has advantages of being easy to manufacture and having a high energy density per weight. In particular, the jelly roll-type electrode assembly having a high energy density may be embedded in a cylindrical metal can to configure a cylindrical secondary battery or button cell.

1 is a view showing the structure of a subminiature button cell and a welding state of a battery can of the button cell.

As shown in FIGS. 1 (a) and 1 (b), a conventional subminiature button cell (1) or a cylindrical battery (not shown) has a jelly-roll electrode assembly (2) and a battery tab derived from the electrode assembly (2). (3) and a battery can 4 accommodating the electrode assembly 2. The battery tab 3 is welded to one side of the battery can 4, the protruding end of the battery tab 3 is bent and placed on the electrode assembly 2, and then the upper battery can (not shown) ) to produce a button cell. Reference numeral 3a denotes the inner surface 3a of the welded portion of the battery tab 3.

1(c) shows the outer surface of the battery can 4, and on the outer surface, the welding mark A1 of the welding part where the battery can 4 is welded to the battery tab 3 by spot welding appear

Conventionally, in order to check the welding quality of the welded part, after disassembling the button cell 1 to remove the electrode assembly 2 as shown in FIG. After installation, the battery tab 3 was torn off and the amount of force (tensile force) applied at the time of tearing off was measured to determine the quality/failure of the welding quality.

However, since this method destroys the product battery, there is a problem in that the actually tested battery must be discarded even if it is judged to be pass after the test. Because of this, it is difficult to perform a 100% inspection, so there is no choice but to proceed with a sampling inspection.

Therefore, there is a need for an inspection method capable of non-destructively inspecting a battery such as a button cell or a cylindrical battery.

In order to inspect the welding strength of a battery in a destructive manner, a welding inspection device for inspecting the welding strength of a battery by measuring the minute resistance flowing through the welding portion has been proposed.

Figure 2 is a schematic diagram showing the probes of such a welding inspection device.

As shown in FIG. 2 , two probes 10 and 20 are brought into contact with the inside and outside of the battery can with the welding portion A of the battery can 1 interposed therebetween to measure the microresistance.

The probes 10 and 20 include tubular first contacts 11 and 21 and second contacts 12 and 22 coaxially installed in the inner space of the first contacts 11 and 21, respectively. there is. The first contactor 11 and the second contactor 12 of the first probe 10 are coupled to the first probe body 13, respectively, and the first contactor 21 and the second contactor 21 of the second probe 20 The two contacts 22 are coupled to the second probe body 23, respectively.

By the way, as shown in FIG. 2 (a), conventionally, in order to measure the welding resistance of the battery can 4 and the battery tab of the cylindrical battery or button cell 1, the inside and outside of the battery can 4 have the same size and diameter. A first probe 10 and a second probe 20 having contacts of In this case, since the area of the tip of the second contactor 22 (contact for voltage measurement) protruding from the tip of the second probe 20 was very small, as shown in FIG. 2(b), there are welding marks on the outer surface of the battery can 4. The second contactor 22 randomly contacted on (A1). P represents the area of the front end where the second contactor 22 contacts the welded portion. The normal battery can 4 is spot-welded with respect to the battery tab to form a welding portion including a circular welding mark A1 having one side opened as shown in FIG. 2(b). Therefore, there may be places where welding is successful and places where welding is not successful along the welding marks A1. When the second contactor 21 randomly contacts the welding marks A1 as shown in FIG. 2(b), the voltage is measured. value fluctuates. In this case, the microresistance value calculated based on the voltage measurement value was inevitably changed at every measurement.

Therefore, there was a problem that the resistance could not be measured reliably and stably with such a battery welding inspection device.

Republic of Korea Patent Publication No. 10-2016-0059789

The present invention has been made to solve the above problems, and provides a battery welding inspection device that can reliably evaluate the welding strength of the welding part by reducing the measurement deviation of the resistance of the welding part of the battery can and the battery tab and measuring the resistance stably. aims to do

Another object of the present invention is to provide a welding inspection method for a battery using the battery welding inspection device.

In order to solve the above problems, a welding inspection device for a battery of the present invention includes a first probe and a second probe respectively contacting the welding part inside and outside the battery can with the welding part of the battery can and the battery tab interposed therebetween during the inspection. A probe and a measurement unit connected to the first probe and the second probe to measure resistance of the welded portion, wherein the first probe and the second probe include a tubular first contactor and an inside of the first contactor. Each second contactor is provided coaxially in the space, the diameter of the first contactor of the second probe is greater than the diameter of the first contactor of the first probe, and the area of the front end of the second contactor of the second probe is 90% or more of the area of the welded part, and the total area of the front end of the first contact and the second contact of the second probe is larger than the area of the welded part.

As a specific example, the area of the front end of the second contact of the second probe may be 90 to 150% of the area of the welded part.

As a specific example, the diameter of the second contact of the second probe may be 0.95 to 1.60 times the diameter of the welded part.

As an example, a diameter of the second contact of the second probe may be larger than that of the second contact of the first probe.

The first contactor may be a contactor for supplying current, and the second contactor may be a contactor for measuring voltage.

As one example, the measuring unit may include a constant current power supply and a voltage detecting means. As a specific example, the first contactor is a contactor for supplying current connected to the constant current power source of the measuring unit, and the second contactor is a contactor for measuring voltage connected to the voltage detecting means of the measuring unit.

As an example, the first contactor or the second contactor may be installed to be relatively movable with respect to each other in the axial direction.

As a specific example, the second contactor is positioned to protrude from the first contactor, and the protruding front end of the second contactor comes into contact with the welded portion and is pressed, so that the front end of the second contactor retreats toward the front end of the first contactor. can do.

As another example, the first contactor is positioned to protrude from the second contactor, and the protruding front end of the first contactor comes into contact with the welded portion and is pressed, so that the front end of the first contactor retreats toward the front end of the second contactor. can do.

As an example, at least one of the first contactor and the second contactor may include an expansion and contraction unit that elastically expands and contracts in an axial direction.

As one example, the battery may be a button cell or a cylindrical battery.

As one aspect of the present invention, there is provided a welding inspection method of the battery by the welding inspection device of the battery, wherein the inspection method uses the first probe and the second probe inside and outside the battery cap to connect the battery can and the battery tab. Contacting the welding part, respectively; A current is applied to the first contact of the first probe and the first contact of the second probe, and the voltage generated at both ends of the weld is measured with the second contact of the first probe and the second contact of the second probe. doing; and measuring the resistance of the welded portion based on the current and voltage.

As a specific example, the welding inspection method of the battery may further include determining whether welding strength of the welding portion is good based on the measured resistance.

According to the present invention, it is possible to reduce the measurement deviation of the weld resistance of the battery can and the battery tab and to measure the weld resistance very stably, so that the weld strength of the weld can be evaluated reliably by micro resistance.

1 is a view showing the structure of a subminiature button cell and a welding state of a battery can of the button cell.
2 is a schematic diagram showing probes of a welding inspection device for inspecting the welding strength of a battery by measuring microresistance flowing through a welded portion.
3 and 4 are schematic diagrams showing a welding inspection device for a battery according to an embodiment of the present invention.
5 is a schematic view showing a positional relationship between a second contactor and a welding mark when a welding part contacts.
Figure 6 is a detailed view of the first probe and the second probe of the welding inspection device of the embodiment of Figure 3;
7 is a schematic diagram showing another example of a first probe and a second probe of the present invention.

Hereinafter, detailed configurations of the present invention will be described in detail with reference to the accompanying drawings and various embodiments. The embodiments described below are shown by way of example to help understanding of the present invention, and the accompanying drawings are not drawn to scale and the dimensions of some components may be exaggerated to help understanding of the present invention. .

Since the present invention may have various changes and various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, it should be understood that this is not intended to limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the battery of a cylindrical battery or button cell, a battery tab derived from an electrode assembly of the battery is welded to the battery can. Usually, since one-way spot welding is performed from the outside of the battery can to weld the battery can and the battery tab, welding marks are not prominent inside the battery can, and welding is performed on the outside of the battery can as shown in FIGS. 1(c) and 2(b) marks are clearly visible. However, when the resistance is measured along the weld marks as shown in FIG. 2 (b), the resistance value varies widely, making it impossible to accurately evaluate the welding strength of the welded portion.

According to the present invention, the welding strength can be reliably evaluated by reducing the measurement deviation of the above-described resistance value by completely covering the welding marks with the probe.

Hereinafter, the present invention will be described in detail.

(First Embodiment)

3 and 4 are schematic diagrams showing a welding inspection device for a battery according to an embodiment of the present invention.

In the battery welding inspection apparatus 1000 of the present invention, the welding portion A of the battery can 4 and the battery tab is sandwiched between the battery can 4 and the welding portion A at the time of inspection, respectively. The contacting first probe 100 and the second probe 200 and the measuring unit 300 connected to the first probe 100 and the second probe 200 to measure the resistance of the welded portion A The first probe 100 and the second probe 200 include the tubular first contacts 110 and 210 and the second contacts 120 and 220 coaxially installed in the inner space of the first contacts 110 and 210. ), the diameter of the first contactor 210 of the second probe 200 is greater than the diameter of the first contactor 110 of the first probe 100, and the diameter of the first contactor 110 of the second probe 200 is The area of the tip of the second contact 220 is 90% or more of the area of the welded portion A, and the total area of the tip of the first contact 210 and the second contact 220 of the second probe 200 is the area of the welded portion A. ) is larger than the area.

In the present invention, in order to measure the resistance of the welded portion A of the battery can and the battery tab, a first probe 100 and a second probe ( 200) is provided. In order to measure the electrical characteristics as described above, the probes 100 and 200 come into contact with the welding portion A at the inside and outside of the battery can, respectively. For convenience of description, a probe contacting the welding portion from the inside of the battery can 4 is referred to as the first probe 100, and a probe contacting the welding portion from the outside of the battery can is referred to as the second probe 200. FIG. 3 shows a state before the first and second probes 100 and 200 come into contact with the welding part A, and FIG. 4 shows a state in which the first and second probes 100 and 200 contact the welding part A to measure resistance. are showing

The first probe 100 and the second probe 200 are connected to the measuring unit 300 that measures the resistance of the weld zone. The first and second probes 100 and 200 do not directly measure resistance, but obtain current and voltage values through contact between the probe and the welded portion, and the measuring unit 300 measures resistance from these current and voltage values. is to do

On the other hand, the resistance measured at the welded portion (A) is a low resistance in milliohm (mΩ) units, and a 4-terminal resistance measurement method is usually used to measure such a low or minute resistance without error. The 4-terminal resistance measurement method is a method of measuring resistance with two current terminals supplying constant current and two voltage terminals connected to a voltage detecting means (voltmeter). The 4-terminal resistance measurement method is designed to have a high impedance of the voltmeter, so no current flows through the voltmeter. Therefore, it is not affected by the measurement probe and cable, so measurement errors can be reduced compared to the so-called 2-terminal resistance measurement method.

The present invention is based on such a four-terminal resistance measurement method, and the first and second probes 100 and 200 of the present invention have first contacts 110 and 210 corresponding to current terminals and second contacts 120 and 220 corresponding to voltage terminals, respectively. are equipped As shown in FIG. 3, the first probe 100 and the second probe 200 are coaxially installed in the inner space of the cylindrical first contacts 110 and 210 and the first contacts 110 and 210, respectively. Two contacts 120 and 220 are respectively provided. That is, each probe has a configuration in which two contacts installed coaxially are integrally integrated. Since the first and second contacts of the first and second probes 100 and 200 are coupled to the probe body 130 and 230, respectively, when the probe body 130 and 230 is moved, the first and second contacts move together and move to the welding portion A. It can be (see Figure 4).

Therefore, compared to the case where the first contact and the second contact are separately separated, it is possible to facilitate the probe's access to the welding part. If the first and second contacts are installed separately, a total of four probes must be operated to bring them into contact with the welding portion, which increases the number of moving mechanisms and complicates the arrangement, which is very inconvenient when automating welding inspection. As in the present invention, when the second contacts 120 and 220 are coaxially installed in the inner space of the first contacts 110 and 210 and installed on the probe main body 130 and 230, the movement of the probe becomes easy. In addition, since the first and second contacts 110 and 210 and 120 and 220 are installed coaxially, the contact space between the probe and the welded portion A is also compact. Therefore, the configuration in which the second contacts 120 and 220 are accommodated in the inner space of the first contacts 110 and 210 and installed coaxially as in the present invention is advantageous in terms of automating welding inspection and contacting the welded part.

As will be described later, the first contacts 110 and 210 and the second contacts 120 and 220 are installed to be relatively movable relative to each other in the axial direction. Therefore, even when the second contact portions 120 and 220 protrude as shown in FIG. 3, when the first and second probes are moved and their front ends come into contact with the welded portion as shown in FIG. 4, the second contact portions 120 and 220 retreat and the first contact portion The front ends of the second contact parts 120 and 220 are positioned on the same plane as the front ends of the 110 and 210 . As a result, both the first and second contact portions come into contact with the welded portion, so that the voltage and the like of the welded portion can be measured. A detailed description of the relative movement configuration of the first and second contact parts will be described later.

Unlike the conventional battery welding inspection apparatus in which the contacts of the first and second probes 100 and 200 have the same size and diameter, the present invention is the diameter of the first contact 210 of the second probe 200 located outside the battery can. is made larger than the diameter of the first contactor 110 of the first probe 100. If the diameter of the first contactor 210 of the second probe 200 is increased, the size (diameter) of the second contactor 220 coaxially installed in the first contactor 210 can be designed to be increased. An object of the present invention is to measure a stable voltage by having the second contact portion 220 of the second probe 200 for voltage measurement mostly or completely cover the welding mark. Therefore, when the diameters of the first contacts 110 and 210 of the first and second probes 100 and 200 are the same as in the prior art, it is difficult to enlarge the size of the second contactor, and accordingly, the second contactor of the second probe 200 ( 220) and the welding portion (A) cannot secure a sufficient contact area. As described above, the influence of the welding marks A1 is more pronounced on the outside of the battery can than on the inside of the battery can. In addition, since the jelly roll electrode assembly 2 is located inside the battery can, increasing the size of the contacts of the first probe 100 has limitations on installation space.

Accordingly, the present invention seeks stable voltage measurement and current supply by increasing the diameter of the contacts of the second probe 200 .

A more characteristic feature of the present invention is that the front end area of the second contactor 220 of the second probe 200 is 90% or more of the area of the welded portion A, and the first, That is, the total area of the tips of the two contacts 210 and 220 is larger than the area of the welded portion A.

5 is a schematic view showing a positional relationship between a second contactor and a welding mark when a welding part contacts.

5(a) shows a state in which the second contact portion 210 of the second probe 200 for voltage measurement is in contact with the weld portion A in the welding mark A1. Here, P represents the area P of the front end of the second contact part. In this case, since the second contact portion 210 is located within the welding mark A1 and is not affected by the welding mark, even if the voltage is measured several times, the measurement error is not so large. On the other hand, as shown in FIG. 5(b) (same view as FIG. 2(b) ), when the second contact part 210 contacts the welding mark A1, the voltage value measured according to the part of the welding mark contacted by the second contact part this will fluctuate Accordingly, the measured resistance value of the welded part is inevitably fluctuated. However, as shown in FIG. 5( a ), it is very difficult from a mechanical/equipment point of view to accurately position the second contact portion having a small area P within the welding mark. For example, considering inspection automation that inspects welding strength by mechanically aligning the first and second probes with the weld A interposed therebetween, detailed adjustment as shown in FIG. 5 (a) is impossible, and most of FIG. It is likely to be in the same contact state as b).

However, as shown in FIG. 5(c), if the second contact part contacts the welding part to almost or completely cover the welding mark A1, the influence of the welding mark can be excluded and more stable voltage data can be obtained. can That is, more specifically, as shown in FIG. 5(c), if the second contact 220 of the second probe 200 completely covers the welding mark A1, the welded part is relatively welded according to the welding mark. It is possible to detect a voltage value corresponding to the average of the portion where this does not work well. Therefore, in the case of FIG. 5(c), it can be seen that all deviations like FIG. 5(b) are absorbed. In the present invention, in order to realize contact with the welded portion as shown in FIG. 5(c), the front end area P of the second contactor 220 of the second probe 200 is at least 90% or more of the welded portion area. Here, the area of the welded portion A refers to the total area of the welding mark A1 of FIG. 5 and the area inside the welding mark A1. When the front end area P of the second contact 220 is 90% or more of the welded portion, as shown in FIG. Since most of them are covered, measurement deviations due to welding scars can be reduced. In addition, if the front end area P of the second contactor 220 is increased, the large area of the second contactor 220 contacts the welding part A while covering most or completely, so as in the case of FIG. There is no need to adjust the position of the second contact 220. In this respect, the degree of freedom in the design of the aligning device for aligning and positioning the first and second probes 100 and 200 with the weld A increases, and there are advantages in manufacturing instruments and equipment for automating inspection.

Specifically, it is preferable that the front end area P of the second contactor 220 of the second probe 200 is 90 to 150% of the area of the welded part. When the area P of the front end is less than 90%, the portion spanning the weld mark A1 increases, and thus, the measurement value deviation as described above may occur. In addition, when the front end area P exceeds 150%, the area of the welding mark or the non-welding part increases, so the measured microresistance rather increases. If the measurement resistance increases, the measurement deviation according to the number of measurements increases, so that the voltage value measured by the second measuring unit does not accurately reflect the resistance value related to the welding strength. Therefore, the area P of the front end of the second contact 220 is set to 150% or less.

On the other hand, the welding mark A1 of the welding portion A has a shape close to a circular shape by spot welding. Therefore, the relationship between the front end area P of the second contact 220 and the area of the welded portion can be replaced or expressed as a diameter relationship. That is, when the area P of the tip of the second contact 220 is 90 to 150% of the area of the welded part, the diameter of the second contact 220 is approximately 0.95 to 1.60 times the diameter of the welded part.

In the present invention, the total area of the tips of the first contact 210 and the second contact 220 of the second probe 200 is greater than the area of the welded portion. If the area of the first contactor 210 does not increase when the area of the second contactor 220 of the second probe 200 increases, the first contactor 210 may not stably supply current. If the first contactor does not secure a sufficient contact area, a deviation may occur in current supply, and in this case, a potential applied before and after the weld may indirectly change. Therefore, in the present invention, by making the total area of the tips of the first and second contacts 210 and 220 of the second probe 200 larger than the area of the welding portion A, both current supply and voltage measurement can be stably performed.

The diameter of the first contactor 210 of the second probe 200 is larger than the diameter of the first contactor 110 of the first probe 100, and the front end of the second contactor 220 occupies 90% or more of the weld area. As the area increases, it is possible to enlarge more and more than the weld area. For example, the diameter of the first contact 210 of the second probe 200 may be 300 to 500% of the diameter of the welded part. As the first and second contacts 210 and 220 of the second probe 200 are enlarged as described above, the reliability of current supply and voltage measurement increases. However, if the first contactor 210 is also too large, a current component unrelated to the welding portion may intervene or leakage current may occur. Therefore, it is preferable to have a diameter of 500% or less of the diameter of the welded part as described above. Also, the diameter of the first contactor 210 may be appropriately adjusted in consideration of the diameter and area of the second contactor 220.

As described above, the first probe 100 inside the battery can has restrictions on installation space due to the jelly roll electrode assembly 2 as described above. Therefore, in the case of the cylindrical battery or button cell 1, the diameters of the first contact 110 and the second contact 120 of the first probe 100 are 210) and the diameter of the second contactor 220 are relatively smaller. However, since the first probe 100 is located inside the battery can 4, which is less affected by welding marks, it is possible to reliably measure the weld resistance even when the diameters of the contacts are relatively small as shown in FIGS. 3 and 4. There is no big crowd.

The measurement unit 300 includes a constant current power supply and a voltage detection means (not shown). That is, in order to detect the 4-terminal resistance, a constant current power supply for current supply is provided, and the first contacts 110 and 210 of the first and second probes 100 and 200 are connected to the constant current power source to generate current through the welding part. supply Accordingly, the second contacts 120 and 220 of the first and second probes 100 and 200 may measure the voltage at both ends of the welded portion. The second contacts 120 and 220 are connected to the voltage detecting means, and the voltage detecting means can measure a voltage value therefrom. From the current value and the voltage value, the measuring unit 300 may calculate the microresistance of the welded part. To this end, the measuring unit 300 may include a predetermined calculation unit and may have a database for storing data as needed. Alternatively, the measuring unit 300 may include a CPU for executing predetermined calculation processing, memory such as RAM for data storage, a memory device for storing predetermined control programs, and other peripheral circuits. The measurement unit 300 may be, for example, or include a microcomputer.

The first and second contacts 110 and 210 and 120 and 220 of the first and second probes 100 and 200 may be installed to be relatively movable with respect to each other in the axial direction.

6 is a detailed view of a first probe and a second probe of the welding inspection device of the embodiment of FIGS. 3 and 4 .

3 and 6, the second contacts 120 and 220 of the first and second probes 100 and 200 are positioned to protrude from the first contacts 110 and 210, and the protruding ends of the second contacts 120 and 220 are connected to the welded portion. By contacting and being pressed, the front ends of the second contacts 120 and 220 retreat toward the front ends of the first contacts 110 and 210 . Since the second contacts 120 and 220 protrude, the second contacts 120 and 220 first come into contact with the welded portion to be pressurized, and then the first contactors 110 and 210 come into contact with the welded portion to supply current. Since the second contacts 120 and 220 are pressed and maintained at the welded portion, when the first contactors 110 and 210 contact the welded portion to supply current, the voltage applied to the welded portion can be more stably measured. For relative movement of the first and second contacts 110, 210, 120, 220, at least one of the first and second contacts 110, 210 and the second contacts 120, 220 may include an expansion and contraction portion that elastically expands and contracts in the axial direction. FIG. 6 shows that elastic members 121 and 221 are installed as the elastic members on parts of the second contacts 120 and 220 coaxially installed inside the first contacts 110 and 210. Accordingly, the front ends of the second contacts 120 and 220 can be retracted toward the first contacts 110 and 210 when pressurized, and finally, both the first and second contacts 110 and 210 (120 and 220) are in contact with the welded portion on the same plane in contact with the welded portion. come into contact

(Second Embodiment)

7 is a schematic diagram showing another example of a first probe and a second probe of the present invention.

This embodiment is different from the first embodiment in the configuration of the first probe and the second probe. However, since other configurations such as the measurement unit are the same as those of the first embodiment, descriptions of components identical to those of the first embodiment will be omitted.

As shown in FIG. 7 , in the present embodiment, the first contacts 310 and 410 of the first and second probes 300 and 400 are positioned to protrude from the second contacts 320 and 420, and the protruding ends of the first contacts 310 and 410 are positioned to protrude from the second contacts 320 and 420. By contacting and pressurizing the welding portion, the front ends of the first contacts 310 and 410 retreat toward the front ends of the second contacts 320 and 420.

For relative movement of the first contacts 310 and 410, in the present embodiment, elastic members 311 and 411 are installed at one end of the first contacts 310 and 410 as an elastic member. In this case, the elastic members 311 and 411 are inserted and mounted into the first and second probe bodies 330 and 430 to which the first and second contacts 310 and 410 and the second contacts 320 and 420 are coupled. The protruding first contacts 310 and 410 first come into contact with the welding part, and in this state, the first contacts 310 and 410 are retracted by continuous pressure, so that the front ends of the first contacts 310 and 410 and the front ends of the second contacts 320 and 420 are It comes into contact with the welded portion on the same plane.

A welding inspection method for a battery using the battery welding inspection apparatus of the present invention will be described in detail.

First, the first probe and the second probe are respectively brought into contact with the welding portion of the battery can and the battery tab on the inside and outside of the battery cap. In this case, one of the first and second contactors installed coaxially with the first and second probes protrudes and contacts the welding part first, and the other contactor sequentially contacts the welding part by pressing the probe.

Next, a current is applied to the first contact of the first probe and the first contact of the second probe, and the second contact of the first probe and the second contact of the second probe generate current at both ends of the welded part. Measure the voltage.

To this end, the first contactors may be connected to a constant current power source of the measuring unit to receive current. In addition, the second contacts may be connected to a voltage detecting means provided in the measurement unit to detect a voltage value from a potential difference between both ends of the welded portion detected by the second contacts. In this case, since the second contact of the second probe of the present invention has a tip area of 90% or more of the area of the welded portion and the total area of the tip of the first and second contacts of the second probe is greater than the area of the welded portion, the current at the welded portion is stable. and voltage values can be obtained.

Thereafter, resistance of the welded portion is measured based on the current and voltage. To this end, the measuring unit may include a predetermined arithmetic unit for calculating resistance.

On the other hand, the welding strength of the welding part can be evaluated from the resistance value. If the welding of the weld is well done, since the two plates constituting the weld are in close contact, the value of current passing through the two plates increases and the value of resistance decreases. On the other hand, in the case of welding failure, since a gap or defect occurs between the two plates, the value of current passing through the two plates is reduced and the resistance value is increased. Therefore, the welding strength of the welded portion can be evaluated by measuring the resistance of the welded portion according to the battery welding inspection apparatus or welding inspection method of the present invention.

In addition, the method for inspecting welding of a battery according to the present invention may further include determining whether welding strength of the welded part is good or bad based on the measured resistance. For example, if the resistance value corresponding to the welding strength of a non-defective product is known, the quality of the welding strength can be determined by comparing it with the measured resistance value of the welded part of the battery to be measured. To this end, the measurement unit may include a predetermined determination unit or determination program.

Example

In order to compare resistance measurement variation according to the area or diameter of the welded part of the second probe, resistance measurement was repeated for a predetermined button cell.

The conditions for the diameter of the welded part and the diameter of the first and second contact parts of the first probe were fixed as follows.

<Welded part diameter: 1.3Φ (1.3mm)>

<Diameter of the first contact part of the first probe: 1.8 mm, diameter of the second contact part: 0.6 mm>

On the other hand, the diameter of the first contact part of the second probe was set to 2.7 mm, and the resistance measurement of the battery can and the battery tab welding part of the button cell was repeated with the tip area and diameter of the second contact part being different as shown in Table 1 below.

tip area
(contact diameter (mm)) measurement
product quantity per product
repeat measurement
collect gun
number of measurements average
Standard Deviation
(mΩ) Example 1 90% (0.95) 20 5 100 0.08 Example 2 95% (1.27) 20 5 100 0.07 Example 3 100% (1.30) 20 5 100 0.05 Example 4 120% (1.42) 20 5 100 0.08 Example 5 150% (1.60) 20 5 100 0.10 Comparative Example 1 21% (0.60) 20 5 100 0.14 Comparative Example 2 70% (1.10) 20 5 100 0.13 Comparative Example 3 200% (1.84) 20 5 100 0.20 reference example 21% (0.60) 20 5 100 0.08

Referring to Table 1, it can be seen that the standard deviation when microresistance is measured 100 times with the front end area of the second contact of the second probe being 90 to 150% of the area of the welded part is 0.10 mΩ or less, which is excellent.

In Comparative Example 1, the area of the tip of the second contact of the second probe is less than 90% of the area of the welded part, the same as that of the first contact of the first probe, and the area of the tip of the second contact is much smaller than the area of the welded part, so resistance is measured. It can be seen that the standard deviation is large.

In Comparative Example 2, the area of the tip of the second contact of the second probe was 70% of the area of the welded part, and the area of the tip of the second contact was smaller than the area of the welded part, so that the standard deviation during resistance measurement was greater than 0.10 mΩ.

In Comparative Example 3, the area of the front end of the second contact of the second probe exceeded 200%, so the standard deviation was very large during resistance measurement. This is because the portion where the second contactor contacts the area other than the welded portion becomes too large, so the measured microresistance itself increases, and accordingly, the standard deviation during measurement also increases.

As a reference example, as shown in FIG. 5(a), the second contact part of the second probe is located at the center of the welding mark, and the measurement standard deviation is as small as 0.08 mΩ. However, it is difficult to finely adjust the position of the small area second contact portion and contact the welded portion as in the reference example due to limitations in equipment and equipment, and does not conform to inspection automation, so it was used as a reference example.

On the other hand, in the case of Examples 1 to 5, when compared with the tensile force measured by the tensile strength tester, it was confirmed that they had a correlation (correlation) of 0.6 or more.

In the above, the present invention has been described in more detail through drawings and examples. However, since the configurations described in the drawings or embodiments described in this specification are only one embodiment of the present invention and do not represent all of the technical spirit of the present invention, various equivalents and equivalents that can replace them at the time of this application It should be understood that variations may exist.

1: battery (button cell)
2: electrode assembly
3: battery tab
4: battery can
A: Weld
A1: (outer surface of battery can) welding mark
100,300: first probe
110,310: first contact
120,320: second contact
121,221: elastic member
130,330: first probe body
P: Area of the front end of the second contact part
200,400: second probe
210,410: first contact
220,420: second contact
230,430: first probe body
311,411: elastic member

Claims (14)

During inspection, a first probe and a second probe contacting the welding portion from the inside and outside of the battery can, respectively, with the welding portion of the battery can and the battery tab interposed therebetween; Including a measuring unit for measuring resistance,
The first probe and the second probe each include a tubular first contact and a second contact coaxially installed in an inner space of the first contact,
The first contactor diameter of the second probe is greater than the first contactor diameter of the first probe;
The area of the tip of the second contact of the second probe is 90% or more of the area of the weld, and the total area of the tip of the first and second contacts of the second probe is larger than the area of the weld.
According to claim 1,
The welding inspection device of the battery, wherein the area of the front end of the second contact of the second probe is 90 to 150% of the area of the welding part.
According to claim 1,
The welding inspection device of the battery, wherein the diameter of the second contact of the second probe is 0.95 to 1.60 times the diameter of the welded part.
According to claim 1,
A welding inspection device for a battery in which a diameter of the second contact of the second probe is formed larger than a diameter of the second contact of the first probe.
According to claim 1,
The first contactor is a contactor for supplying current, and the second contactor is a contactor for measuring voltage.
According to claim 1,
The measuring unit is a welding inspection device for a battery having a constant current power source and a voltage detection means.
According to claim 6,
The first contactor is a contactor for supplying current connected to the constant current power source of the measuring unit, and the second contactor is a contactor for measuring voltage connected to the voltage detecting means of the measuring unit.
According to claim 1,
The first contactor and the second contactor are installed to be relatively movable with respect to each other in the axial direction.
According to claim 8,
The second contactor is positioned to protrude from the first contactor, and the protruding front end of the second contactor comes into contact with the welding portion and is pressed, so that the front end of the second contactor retreats toward the front end of the first contactor. inspection device.
According to claim 8,
The first contactor is positioned to protrude from the second contactor, and the protruding front end of the first contactor comes into contact with the welding part and is pressed, so that the front end of the first contactor retreats toward the front end of the second contactor. inspection device.
According to claim 8,
At least one of the first contactor and the second contactor has an extension and contraction portion that elastically expands and contracts in an axial direction.
According to claim 1,
The battery is a button cell or cylindrical battery welding inspection device.
A welding inspection method of a battery by the welding inspection device of claim 1,
contacting the first probe and the second probe to the welding portion of the battery can and the battery tab, respectively, on the inside and outside of the battery cap;
A current is applied to the first contact of the first probe and the first contact of the second probe, and the voltage generated at both ends of the weld is measured with the second contact of the first probe and the second contact of the second probe. doing; and
Welding inspection method of a battery comprising the step of measuring the resistance of the welded portion based on the current and voltage.
According to claim 13,
The welding inspection method of the battery further comprising the step of determining whether the welding strength of the welded portion is good or bad based on the measured resistance.

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