Welding apparatus for cylindrical battery having welding rod overlap measuring unit

Abstract

The present invention relates to a welding apparatus comprising: an upper welding unit including an upper welding rod; a first object to be bonded positioned below the upper welding rod; a second object to be bonded positioned below the first object to be bonded; and a lower welding unit including a lower welding rod positioned below the second object to be bonded, wherein the first object to be bonded and the second object to be bonded are welded by resistance welding of the upper welding rod and the lower welding rod, and the welding apparatus comprises a displacement measuring unit capable of measuring the displacement of a buffer unit provided on at least one of the upper end of the upper welding rod or the lower end of the lower welding rod by additional pressure while the upper welding rod, the first object to be bonded, the second object to be bonded, and the lower welding rod are in close contact with each other.

Description

Welding device for cylindrical batteries with added welding rod overlap measuring section

[0001] The present invention relates to a welding device for a cylindrical battery, equipped with a welding rod overlap measuring unit. Specifically, the invention relates to a welding device for a cylindrical battery, equipped with a welding rod overlap measuring unit, capable of determining the degree of contact between welding rods at the upper and lower surfaces of the bottom of a cylindrical can when resistance welding the cylindrical can and the negative tab of a cylindrical battery cell.

[0002] A lithium secondary battery includes an electrode assembly including a positive electrode coated with a positive electrode active material, a negative electrode coated with a negative electrode active material, a separator positioned between the positive electrode and the negative electrode to prevent short circuiting and enable movement of lithium ions (Li-ions), a battery case that accommodates the electrode assembly, and an electrolyte that is injected into the inside of the battery case to enable movement of lithium ions.

[0003] Lithium secondary batteries are classified into cylindrical or prismatic batteries, which house the electrode assembly in a cylindrical or prismatic metal can, and pouch batteries, which house the electrode assembly in a pouch-shaped case made of aluminum laminate sheet, depending on the shape of the battery case. Cylindrical batteries have the advantages of relatively large capacity and structural safety.

[0004] A cylindrical battery is manufactured by placing and sealing a jelly-roll electrode assembly in a coiled form with a separator sheet interposed between a positive electrode sheet and a negative electrode sheet in a cylindrical battery case. The jelly-roll electrode assembly is placed inside a cylindrical can, and the negative electrode tab located on the bottom of the cylindrical can and the lower part of the jelly-roll electrode assembly are welded.

[0005] Typically, the negative tab of a cylindrical battery is resistance-welded to the bottom of the cylindrical can. Because the negative tab is located on the inner bottom of the cylindrical battery, laser irradiation poses a risk of laser irradiation to other parts of the jelly-roll electrode assembly, so resistance welding is often used. The positive tab is often laser-welded to the top cap. Laser welding is also used to weld the electrode tab and electrode lead in pouch-type batteries.

[0006] Fig. 1 is an exploded cross-sectional view of a cylindrical battery and a resistance welding device according to the prior art, Fig. 2 is a cross-sectional view of a state in which a cylindrical battery and a resistance welding device according to the prior art are combined to perform welding, and Fig. 3 is a schematic diagram of the upper part of a resistance welding device according to the prior art.

[0007] Referring to FIGS. 1 to 3, a resistance welding device according to the prior art will be described. A cylindrical battery (100) has a jelly-roll electrode assembly (110) housed inside a cylindrical can (120). A negative electrode tab (130) protrudes from the lower portion of the jelly-roll electrode assembly (110). For reference, the positive electrode tab is omitted in FIGS. 1 to 3. The cylindrical battery (100) is fixed to a jig (200) for resistance welding.

[0008] A resistance welding device according to the prior art includes an upper welding part (300) including an upper welding rod (310), and a lower welding part (400) including a lower welding rod (410). Before performing resistance welding, a cylindrical battery (100) is placed in a jig (200) while the upper welding part (300) and the lower welding part (400) are spaced apart from each other vertically. Thereafter, the upper welding part (300) moves downward, and the lower welding part (400) moves upward, so that the upper welding rod (310), the negative tab (130), the cylindrical can (120), and the lower welding rod (410) are arranged in this order in the inner lower region of the cylindrical can (120).

[0009] For welding, the upper welding rod (310) and the lower welding rod (410) must be in close contact. For resistance welding, the upper welding rod (310) and the lower welding rod (410) must be pressurized. Physically, once the upper welding rod (310), the negative tab (130), the cylindrical can (120), and the lower welding rod (410) are in close contact, further movement is impossible. However, for resistance welding, the upper welding rod (310), the negative tab (130), the cylindrical can (120), and the lower welding rod (410) must be in close contact, and the welding quality varies depending on the degree of this close contact.

[0010] The upper welding rod (310) is fixed to the welding rod jig (320) and is fixed to the welding rod storage portion (330) provided at the lower portion of the upper welding portion (300). A buffer portion (340) exists between the welding portion body (350) provided at the upper portion and the welding rod storage portion (330) for fixing and moving the entire upper welding portion (300).

[0011] Since the upper welding rod (310) and the lower welding rod (410) must be in close contact, this degree of overlap is expressed using the expression "overlap." Since the upper welding rod (310) and the lower welding rod (410) cannot physically overlap, the overlap can be expressed as follows.

[0012] In the absence of a cylindrical can, the upper welding rod (310) is moved downwards to measure or set a position at which it can descend. A control unit is provided in the welding body (350) to remember the position of the welding rod. The upper welding rod (310) is moved upwards again, and the lower welding rod (410) is raised to measure or set a position at which it rises. At this time, the respective set positions of the upper welding rod (310) and the lower welding rod (410) are actually positions at which the ends of the upper welding rod (310) and the lower welding rod (410) overlap. Since the ends of the upper welding rod (410) and the lower welding rod (410) physically cannot overlap, the upper welding rod (310) is retracted to that extent by the buffer (340) for this purpose. The tension applied to the buffer (340) varies depending on the degree of retraction, and the greater the degree of retraction, the higher the tension. That is, by presetting the overlap section, the tension applied to the upper welding rod (310) and the lower welding rod (410) can be adjusted, and through this, the degree of adhesion between the upper welding rod (310), the negative tab (130), the cylindrical can (120), and the lower welding rod (410) can be adjusted.

[0013] The resistance welding device according to the prior art has a buffer section (340), but does not directly determine the degree of buffering. Before welding, the above process is performed to set an overlap section, and welding is performed accordingly.

[0014] Since the jelly-roll electrode assembly is not the same for each cylindrical battery, the shape and position of the negative tab (130) are different, and the degree to which the jelly-roll assembly is inserted into the cylindrical can is different, and furthermore, the degree to which the cylindrical battery (100) is fixed to the jig (200) may be different for each cylindrical battery (100). Therefore, if the overlap section is set by a single consistent standard and welding is performed accordingly, the welding quality of each cylindrical battery cannot be determined. In addition, since welding is performed multiple times with one welding rod, the length of the welding rod also changes as the welding progresses. Furthermore, since the tension of the spring, etc. provided inside the buffer section may change, the actual pressure applied may not be the same even if the overlap section is set by length according to the prior art.

[0015] Conventional technologies have relied on the observation of workers to address these issues, and have not provided specific means to clearly identify them.

[0016] Patent Document 1 discloses a method and device for joining dissimilar metals, which are equipped with upper and lower electrodes performing welding and distance sensors positioned on the sides of the upper electrode. Patent Document 1 directly measures the change in distance to the joined object while welding is in progress and determines the degree of this change to determine whether welding is complete. In the case of the present invention, the welding is performed in a very short time using resistance welding, and the degree of change in the numerical value of the joined object itself due to welding is almost non-existent. In the case of the present invention, the change in distance is not measured while welding is in progress, but the degree of overlap is determined in advance and welding is simply performed accordingly, so the configuration of D1, which detects changes in real time, cannot be applied.

[0017] Patent documents 2 to 4 also do not present a buffer portion corresponding to the main components of the present invention and a configuration for confirming displacement thereof.

[0018] In this way, the prior art lacks a means to determine or measure the degree of overlap, which is an important factor in resistance welding of cylindrical batteries.

[0019] Japanese Patent Publication No. 2008-284570 (Patent Document 1)

[0020] Japanese Patent Publication No. 2020-019060 (Patent Document 2)

[0021] Republic of Korea Utility Model Publication No. 0259892 ('Patent Document 3')

[0022] Chinese Patent Publication No. 115815769 (Patent Document 4)

[0023] The present invention is intended to solve the above-mentioned problem, and aims to provide a means for determining or measuring the degree of overlap, which is an important factor in resistance welding of cylindrical batteries.

[0024] In order to achieve the above object, the present invention provides a welding device including an upper welding part including an upper welding electrode, a first member positioned below the upper welding electrode, a second member positioned below the first member, and a lower welding part including a lower welding electrode positioned below the second member, wherein the first member and the second member are welded by resistance welding of the upper welding electrode and the lower welding electrode, and a displacement measuring part capable of measuring a displacement of a buffer provided at least in one of the upper end of the upper welding electrode or the lower end of the lower welding electrode by additional pressure in a state where the upper welding electrode, the first member, the second member, and the lower welding electrode are in close contact with each other is provided.

[0025] The upper welding part may include a welding part body located at the upper part and provided with a moving part for moving and fixing the entire upper welding part, and a buffer part located between the welding part body and the upper welding rod and having a length between the welding part body and the upper welding rod changed by pressure applied to the upper welding rod.

[0026] The upper welding part may include a welding part jig for fixing the upper welding part, a welding part storage part in which the welding part jig is stored and fixed, a welding part body located at the top and having a moving part for moving and fixing the entire upper welding part, and a buffer part located between the welding part body and the welding part storage part and having a length between the welding part body and the welding part storage part changed by pressure applied to the upper welding part.

[0027] The displacement measuring unit may include a measuring dog attached to the welding rod receiving portion, and a displacement measuring sensor attached to the welding body to measure the distance to the measuring dog. The measuring dog and the displacement measuring sensor may be arranged with their positions changed from each other.

[0028] The displacement measurement sensor can measure displacement using a physical tip or a laser. The displacement measurement sensor can be fixed to the welded body using a sensor fixing member. Additionally, the values ​​measured by the displacement measurement sensor can be converted into digital form and transmitted.

[0029] The present invention also provides a cylindrical battery negative tab resistance welding device including a cylindrical battery having a jelly-roll electrode assembly housed therein, a jig for fixing the lower portion of the cylindrical battery, and a welding device according to the present invention, wherein the first contact member is a negative tab, and the second contact member is the lower bottom of the cylindrical can.

[0030] The upper welding rod can perform welding by penetrating the central portion of the jelly-roll electrode assembly.

[0031] A visual device for observing the end of the upper welding rod may be added.

[0032] The present invention also provides a method for resistance welding a negative tab of a cylindrical battery using a negative tab resistance welding device for a cylindrical battery, the method comprising: a first step of fixing a cylindrical battery containing a jelly-roll electrode assembly to the jig; a second step of moving the upper welding rod and the lower welding rod respectively to bring the upper welding rod, the negative tab, the lower bottom of the cylindrical can, and the lower welding rod all into close contact; a third step of further pressurizing the upper welding rod and measuring the displacement of the buffer portion accordingly using the displacement measuring unit, while adjusting the degree of pressurization of the upper welding rod so that a desired displacement value is output from the displacement measuring unit; and a fourth step of performing resistance welding after adjusting the degree of pressurization of the upper welding rod in the third step.

[0033] The present invention also provides a cylindrical battery welded by a resistance welding device for a negative tab of a cylindrical battery.

[0034] The present invention can also provide a problem solving means by arbitrarily combining the above problem solving means.

[0035] The present invention provides a welding device comprising an upper welding portion including an upper welding electrode, a first member positioned below the upper welding electrode, a second member positioned below the first member, and a lower welding portion including a lower welding electrode positioned below the second member, wherein the first member and the second member are welded by resistance welding of the upper welding electrode and the lower welding electrode, and a displacement measuring portion capable of measuring a displacement of a buffer portion provided at least in one of the upper end of the upper welding electrode or the lower end of the lower welding electrode by additional pressure while the upper welding electrode, the first member, the second member, and the lower welding electrode are in close contact with each other is provided.

[0036] In addition, the present invention can determine or measure the degree of overlap, which is an important factor in resistance welding of cylindrical batteries, and thus can provide welding results of consistent quality.

[0037] Figure 1 is an exploded cross-sectional view of a cylindrical battery and a resistance welding device according to the prior art.

[0038] Figure 2 is a cross-sectional view showing a state in which a cylindrical battery and a resistance welding device according to the prior art are combined to perform welding.

[0039] Figure 3 is a schematic diagram of the upper part of a resistance welding device according to the prior art.

[0040] Figure 4 is an exploded cross-sectional view of a cylindrical battery and a resistance welding device according to the present invention.

[0041] Figure 5 is a cross-sectional view showing a state in which a cylindrical battery and a resistance welding device according to the present invention are combined to perform welding.

[0042] Figure 6 is a schematic diagram for measuring displacement of the upper part of a resistance welding device according to the present invention.

[0043] Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail, so that those with ordinary skill in the art can easily implement the present invention. However, when describing the operating principles of preferred embodiments of the present invention in detail, if a detailed description of a related known function or configuration is judged to unnecessarily obscure the gist of the present invention, such detailed description will be omitted.

[0044] Additionally, the same drawing reference numerals are used for parts with similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless specifically stated otherwise, but rather implies the inclusion of additional components.

[0045] Additionally, the description that concretizes or adds components may be applied to all inventions unless there are special limitations, and is not limited to the description of a specific invention.

[0046] Additionally, throughout the description and claims of the invention herein, the singular includes the plural unless otherwise stated.

[0047] Additionally, throughout the description and claims of the present invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases of including A, including B, or including A and B.

[0048] Additionally, all numerical ranges include the extreme values ​​and all intermediate values ​​between them, unless explicitly stated otherwise.

[0049] The present invention is described in detail with examples according to the drawings.

[0050] Fig. 4 is an exploded cross-sectional view of a cylindrical battery and a resistance welding device according to the present invention, Fig. 5 is a cross-sectional view of a state in which a cylindrical battery and a resistance welding device according to the present invention are combined to perform welding, and Fig. 6 is a schematic diagram of displacement measurement of the upper portion of a resistance welding device according to the present invention.

[0051] Referring to FIGS. 4 to 6, the present invention comprises a welding device including an upper welding part (300) including an upper welding rod (310), a first joining body (130) located below the upper welding rod (310), a second joining body (125) located below the first joining body (130), and a lower welding part (400) including a lower welding rod (410) located below the second joining body (125), wherein the first joining body (130) and the second joining body (125) are welded by resistance welding of the upper welding rod (310) and the lower welding rod (410), and the upper welding rod (310), the first joining body (130), the second joining body (125), and the lower welding rod (410) are in close contact with each other, and the upper part of the upper welding rod (310) or the lower welding rod (410) is welded by additional pressure. It relates to a welding device having a displacement measuring unit (600) capable of measuring the displacement of a buffer unit (340) provided at least on one of the lower ends.

[0052] The upper welding part (300) includes a welding part jig (320) that fixes the upper welding part (310), a welding part storage part (330) in which the welding part jig (320) is stored and fixed, a welding part body (350) located at the top and having a moving part (not shown in the drawing) for moving and fixing the entire upper welding part (300), and a buffer part (340) located between the welding part body (350) and the welding part storage part (330) and in which the length between the welding part body (350) and the welding part storage part (330) changes according to the pressure applied to the upper welding part (310).

[0053] The welding rod jig (320) allows the upper welding rod (310) of a constant length to be inserted and fixed at a constant depth. The welding rod jig (320) can be fixed to the welding rod storage section (330) in a form that is bitten by a clamp.

[0054] The displacement measuring unit (600) includes a measuring dog (335) attached to a welding rod receiving unit (330) and a displacement measuring sensor (500) attached to a welding body (350) to measure the distance to the measuring dog (335). The measuring dog (335) and the displacement measuring sensor (500) may be arranged with their positions changed relative to each other.

[0055] The displacement measuring sensor (500) can measure displacement using a physical tip or a laser. The displacement measuring sensor (500) is fixed to the welded body (350) by a sensor fixing member (550). In addition, the value measured by the displacement measuring sensor (500) is converted into digital form and transmitted.

[0056] Also, the present invention relates to a cylindrical battery negative tab resistance welding device including a cylindrical battery (100) in which a jelly-roll electrode assembly (110) is accommodated, a jig (200) for fixing the lower portion of the cylindrical battery (100), and a welding device according to the present invention, wherein the first contact member is a negative tab (130) and the second contact member is a lower bottom (125) of a cylindrical can.

[0057] The upper welding rod (310) passes through the center of the jelly-roll electrode assembly (110) to perform welding.

[0058] A visual device (not shown in the drawing) for observing the end of the upper welding rod (310) may be added. Since the upper welding rod (310) is typically resistance welded, its length decreases as welding progresses. However, in the present invention, if the end of the upper welding rod (310) becomes uneven from a uniform state before the length decreases, it is replaced. Therefore, it is safe to assume that one upper welding rod (310) has a constant length during actual welding. The end surface of the upper welding rod (310) can be observed or the welding condition can be checked and the welding rod can be replaced. The end of the upper welding rod (310) should be continuously observed with a visual device such as a camera, and it is preferable to replace it before the end surface becomes rough, as welding will not proceed properly.

[0059] The present invention also provides a method for resistance welding a negative tab (130) of a cylindrical battery (100) using a negative tab resistance welding device of a cylindrical battery, comprising: a first step of fixing a cylindrical battery (100) containing a jelly-roll electrode assembly (110) to a jig (200); a second step of moving the upper welding rod (310) and the lower welding rod (410) respectively to bring the upper welding rod (310), the negative tab (130), the lower bottom (125) of the cylindrical can, and the lower welding rod (410) all into close contact; a third step of further pressing the upper welding rod (410) and measuring the displacement of the buffer portion (340) accordingly at the displacement measuring portion (600) while adjusting the degree of pressing of the upper welding rod (310) so that a desired displacement value is output from the displacement measuring portion (600); and after adjusting the degree of pressing of the upper welding rod (310) in the third step, A method for resistance welding a negative tab of a cylindrical battery, including a fourth step of performing welding.

[0060] The change in the buffer section D1-D2 is equal to the change in displacement value H1-H2. Therefore, the actual change in the buffer section can be known through the displacement value.

[0061] Anyone with ordinary knowledge in the field to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

[0062] (Explanation of symbols)

[0063] 100: Cylindrical battery

[0064] 110: Jelly-roll electrode assembly

[0065] 120: Cylindrical can

[0066] 125: Lower part of cylindrical can, second joint

[0067] 130: Negative tab, first contact

[0068] 200: Jig

[0069] 300: Upper weld

[0070] 310: Upper welding rod

[0071] 320: Welding rod jig

[0072] 330: Welding rod storage compartment

[0073] 335: Measuring dog

[0074] 340: Buffer

[0075] 350: Welded body

[0076] 550: Sensor fixture

[0077] 400: Lower weld

[0078] 410: Lower welding rod

[0079] 500: Displacement measurement sensor

[0080] 600: Displacement measurement unit (335, 500)

[0081] D, D1, D2: Buffer length

[0082] H1, H2: displacement values

Claims

1. Upper weld including upper welding rod; A first welded member positioned below the upper welding rod; A second adhesive agent positioned below the first adhesive agent; A lower weld portion including a lower welding rod positioned at the lower portion of the second joint; In a welding device including: The first joint and the second joint are welded by resistance welding of the upper welding rod and the lower welding rod. A welding device having a displacement measuring unit capable of measuring the displacement of a buffer provided at least on one of the upper end of the upper welding rod or the lower end of the lower welding rod by additional pressure while the upper welding rod, the first joining body, the second joining body, and the lower welding rod are in close contact with each other.

2. In paragraph 1, The upper welded portion above, A welded body positioned at the top and having a movable part for moving and fixing the entire upper welded part; A welding device including a buffer portion positioned between the welding body and the upper welding electrode, the length between the welding body and the upper welding electrode changing according to the pressure applied to the upper welding electrode.

3. In paragraph 1, The upper welded portion above, A welding rod jig for fixing the upper welding rod; A welding rod storage section in which the above welding rod jig is stored and fixed; A welded body positioned at the top and having a movable part for moving and fixing the entire upper welded part; A welding device including a buffer portion positioned between the welding body and the welding rod storage portion, the length between the welding body and the welding rod storage portion being changed by pressure applied to the upper welding rod.

4. In paragraph 3, The above displacement measuring unit, A measuring dog attached to the above welding rod storage section; A displacement measuring sensor attached to the above welded body and measuring the distance to the measuring dog; A welding device including:

5. In paragraph 4, The above displacement measuring sensor is a welding device that measures displacement by a physical tip or laser.

6. Cylindrical battery containing a jelly-roll electrode assembly; A jig for fixing the lower part of the above cylindrical battery; And a welding device according to any one of claims 1 to 4; In a negative tab resistance welding device of a cylindrical battery including: The above first contact is a negative tab, The above second bonding agent is a resistance welding device for the negative tab of a cylindrical battery, which is the lower bottom of a cylindrical can.

7. In paragraph 6, The above upper welding rod is a resistance welding device for the negative tab of a cylindrical battery that performs welding by penetrating the central part of the jelly-roll electrode assembly.

8. In paragraph 6, A resistance welding device for the negative tab of a cylindrical battery, having a visual device for observing the end of the upper welding rod.

9. A method for resistance welding a negative tab of a cylindrical battery using a negative tab resistance welding device according to Article 6, A first step of fixing a cylindrical battery containing a jelly-roll electrode assembly to the jig; A second step of moving the upper welding rod and the lower welding rod respectively to bring the upper welding rod, the negative tab, the lower bottom of the cylindrical can, and the lower welding rod into close contact; A third step of further pressurizing the upper welding rod and measuring the displacement of the buffer section accordingly at the displacement measuring section, while adjusting the degree of pressurization of the upper welding rod so that a desired displacement value is output at the displacement measuring section; A fourth step of performing resistance welding after adjusting the pressure level of the upper welding rod in the third step; A method for resistance welding a negative tab of a cylindrical battery including a .

10. A cylindrical battery welded by a resistance welding device for the negative tab of a cylindrical battery according to Article 6.

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