Method and apparatus for welding case-cap assembly

Abstract

The present invention provides a method for welding a case-cap assembly. The method for welding a case-cap assembly comprises the steps of: welding a first section (S1) of a cap assembly, disposed at an opening of a case, at a first speed; welding a second section (S2) of the cap assembly while changing the welding speed from the first speed to a second speed different from the first speed; and welding a third section (S3) of the cap assembly at the second speed, wherein the cap assembly includes a long side and a short side extending in a direction intersecting the long side, the first section (S1) is located on the long side, and at least a portion of the third section (S3) is located on the short side.

Description

Method and apparatus for welding a case-cap assembly

[0001] The present disclosure relates to a method and apparatus for welding a case-cap assembly.

[0002] Secondary batteries, unlike non-rechargeable primary batteries, are rechargeable and dischargeable. Low-capacity secondary batteries are used in small, portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while large-capacity secondary batteries are widely used as power sources for motor drives and power storage in hybrid and electric vehicles. These secondary batteries include an electrode assembly comprising a positive and negative electrode, a case housing the electrode assembly, and electrode terminals connected to the electrode assembly.

[0003] Secondary batteries are manufactured by inserting an electrode assembly into a case and sealing the cap assembly. A welding device welds the case and cap assembly together by irradiating a laser along the shape of the cap assembly positioned over the case's opening. While increasing the welding speed of the welding device can improve battery cell productivity, uniformly increasing the welding speed regardless of the welding section location makes it difficult to ensure uniformity in the weld.

[0004] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present invention, and therefore may include information that does not constitute prior art.

[0005] The problem to be solved by the present disclosure is to provide a method and device for welding a case-cap assembly to solve the above-mentioned problems.

[0006] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0007] According to some embodiments of the present disclosure for solving the above technical problem, for a cap assembly disposed on an opening of a case, the method includes the steps of: welding a first section (S1) of the cap assembly at a first speed; welding a second section (S2) of the cap assembly while changing the welding speed from the first speed to a second speed different from the first speed; and welding a third section (S3) of the cap assembly at the second speed, wherein the cap assembly includes a long side and a short side extending in a direction intersecting the long side, the first section (S1) is located on the long side, and at least a portion of the third section (S3) is located on the short side.

[0008] According to some embodiments of the present disclosure, the step of welding the second section (S2) of the cap assembly while changing from the first speed to a second speed different from the first speed includes the step of welding while constantly decelerating from the first speed to the second speed.

[0009] According to some embodiments of the present disclosure, the step of welding the first section (S1) of the cap assembly at the first speed includes the step of welding the output of the welding in the first section (S1) of the cap assembly at the first output, and the step of welding the third section (S3) of the cap assembly at the second speed includes the step of welding the output of the welding in the third section (S3) of the cap assembly at the second output, which is lower than the first output.

[0010] According to some embodiments of the present disclosure, the step of welding the second section (S2) of the cap assembly while changing the first speed to a second speed different from the first speed includes the step of welding while changing the welding output from the first output to the second output in the second section (S2) of the cap assembly.

[0011] According to some embodiments of the present disclosure, the step of welding while changing the output of the welding from the first output to the second output includes the step of welding while constantly decreasing the output of the welding from the first output to the second output.

[0012] According to some embodiments of the present disclosure, the second section (S2) is positioned between the first section (S1) and the third section (S3).

[0013] According to some embodiments of the present disclosure, the cap assembly further includes a corner portion connecting one end of the long side and one end of the short side, wherein the corner portion includes a section where the welding direction is changed.

[0014] According to some embodiments of the present disclosure, the corner portion is in the form of a curve, and the welding direction is changed over the entire section of the corner portion.

[0015] According to some embodiments of the present disclosure, the welding direction is switched in at least some sections of the corner portion.

[0016] According to some embodiments of the present disclosure, the second section (S2) is located on one end of the long side, and the third section (S3) is located on the short side and the corner.

[0017] According to some embodiments of the present disclosure, the second section (S2) is located on one end and a corner of the long side.

[0018] According to some embodiments of the present disclosure, the second section (S2) is located on a corner portion.

[0019] According to some embodiments of the present disclosure, each of the first speed and the second speed is between 120 mm / s and 250 mm / s.

[0020] According to some embodiments of the present disclosure, the method further comprises the step of welding a fourth section (S4) of the cap assembly while changing the speed from the second speed to the first speed, wherein the fourth section (S4) is connected to the third section (S3).

[0021] According to some embodiments of the present disclosure, the step of welding the fourth section (S4) of the cap assembly while changing from the second speed to the first speed includes the step of welding while constantly accelerating from the second speed to the first speed.

[0022] According to some embodiments of the present disclosure, the step of welding the fourth section (S4) of the cap assembly while changing the speed from the second speed to the first speed includes the step of welding the fourth section (S4) of the cap assembly while changing the output of the welding from the second output to the first output.

[0023] According to some embodiments of the present disclosure for solving the above technical problem, a cap assembly is provided, including a fixing member for supporting a case, a laser head member for irradiating a laser onto a cap assembly disposed on an opening of the case, and a control member for controlling at least one of a welding speed or a laser output of the laser head member, wherein the laser head member is controlled to weld a first section (S1) of the cap assembly at a first speed, weld a second section (S2) of the cap assembly while changing the welding speed from the first speed to a second speed different from the first speed, and weld a third section (S3) of the cap assembly at the second speed, wherein the cap assembly includes a long side and a short side extending in a direction intersecting the long side, the first section (S1) is located on the long side, and at least a portion of the third section (S3) is located on the short side.

[0024] According to some embodiments of the present disclosure, the laser head unit is controlled to weld a first section (S1) of the cap assembly with a first output, weld a second section (S2) of the cap assembly while changing from the first output to a second output different from the first output, and weld a third section (S3) of the cap assembly with the second output.

[0025] According to some embodiments of the present disclosure, the laser head portion is controlled to weld the second section (S2) of the cap assembly while constantly decelerating from the first speed to the second speed.

[0026] According to some embodiments of the present disclosure, the laser head portion is controlled to weld the second section (S2) of the cap assembly while constantly decreasing the laser output from the first output to the second output.

[0027] According to some embodiments of the present invention, the laser output is controlled in response to the welding speed, so that the heat input per unit length of the welding section is maintained constant, thereby ensuring the homogeneity of the welding and preventing overwelding.

[0028] According to some embodiments of the present invention, the welding speed in the section where the welding direction is changed and the short-side section of the cap assembly is controlled to be lower than the welding speed in the long-side section of the cap assembly, thereby reducing the mechanical shock generated in the welding device due to the change in the moving direction of the laser head.

[0029] However, the effects that can be obtained through the present invention are not limited to the effects described above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0030] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0031] FIG. 1 is a perspective view illustrating an example of a battery cell according to one embodiment of the present disclosure.

[0032] FIG. 2 is a block diagram showing the configuration of a welding device according to one embodiment of the present disclosure.

[0033] FIG. 3 is an exemplary drawing showing a method of welding a case and a cap assembly using a welding device according to one embodiment of the present disclosure.

[0034] Fig. 4 is a drawing showing a comparative example of a case-cap assembly welding method.

[0035] FIG. 5 is a drawing showing an example of a shape of a cap assembly according to one embodiment of the present disclosure.

[0036] FIG. 6 is a drawing showing an example of the shape of a cap assembly according to another embodiment of the present disclosure.

[0037] FIG. 7 is an exemplary drawing for explaining a case-cap assembly welding method according to the position of the welding section according to one embodiment of the present disclosure.

[0038] FIG. 8 is an exemplary drawing for explaining a case-cap assembly welding method according to the position of the welding section according to another embodiment of the present disclosure.

[0039] FIG. 9 is an exemplary drawing for explaining a case-cap assembly welding method according to the position of the welding section according to another embodiment of the present disclosure.

[0040] FIG. 10 is a drawing showing an example of a graph of the movement speed of a laser head portion of a welding device according to time change according to one embodiment of the present disclosure.

[0041] FIG. 11 is a diagram showing an example of a graph of laser output intensity of a welding device over time according to one embodiment of the present disclosure.

[0042] FIG. 12 is a flowchart illustrating a case-cap assembly welding method according to one embodiment of the present disclosure.

[0043] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms or words used in this specification and claims should not be interpreted as limited to their typical or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her own invention. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only some of the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as substitutes for them at the time of filing this application.

[0044] Additionally, when used herein, the terms "comprise", "include" and / or "comprising", "including" specify the presence of stated features, numbers, steps, operations, elements, elements and / or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and / or groups thereof.

[0045] Additionally, to facilitate understanding of the invention, the attached drawings are not drawn to scale and some components may be exaggerated in size. Furthermore, identical components may be assigned the same reference numbers in different embodiments.

[0046] The statement that two compared objects are "identical" means "substantially identical." Therefore, "substantially identical" may include deviations considered low in the art, such as deviations of less than 5%. Furthermore, uniformity of a parameter over a given region may imply uniformity on average.

[0047] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0048] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0049] Any configuration being placed "on (or under)" or "above (or below)" a component may mean not only that any configuration is placed in contact with the upper surface (or lower surface) of said component, but also that other configurations may intervene between said component and any configuration placed on (or below) said component.

[0050] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component. Furthermore, when it is said that a part is electrically coupled to another part, this includes not only cases where they are directly connected, but also cases where they are connected with another element in between.

[0051] When reference is made throughout the specification to "A and / or B," this means A, B, or A and B, unless otherwise stated. In other words, "and / or" includes all or any combination of the listed items. When reference is made to "C through D," this means C or more and D or less, unless otherwise stated.

[0052] The terminology used herein is for the purpose of describing embodiments of the invention and is not intended to limit the invention.

[0053] FIG. 1 is a perspective view illustrating an example of a battery cell (100) according to one embodiment of the present disclosure. Referring to FIG. 1, the battery cell (100) may include at least one electrode assembly wound or laminated with a separator, which is an insulator, interposed between a positive electrode and a negative electrode, a case (110) in which the electrode assembly is housed, and a cap assembly (120) coupled to an open end of the case (110). The battery cell (100) illustrated in FIG. 1 may be a type of secondary battery.

[0054] The positive and negative electrodes may include a coated portion, which is an area where an active material is applied to a current collector formed of a thin metal foil, and a non-coated portion, which is an area where the active material is not coated.

[0055] The positive and negative electrodes are wound with a separator, which is an insulator, interposed between them. However, the present invention is not limited thereto, and the electrode assembly described above may be formed by a structure in which a plurality of sheets of positive and negative electrodes are alternately laminated with a separator interposed between them.

[0056] The case (110) forms the overall appearance of the battery cell (100) and may be formed of a conductive metal such as aluminum, an aluminum alloy, or nickel-plated steel. In addition, the case (110) may provide a space in which an electrode assembly is accommodated. In FIG. 1, the case (110) is a square case, and the battery cell (100) is illustrated as a square battery cell, but the scope of the present disclosure is not limited thereto. The battery cell (100) may be a battery cell of any shape, such as a square, cylindrical, or pouch-shaped shape.

[0057] The cap assembly (120) can be coupled to an open end of the case (110) to seal the case (110). The case (110) and the cap assembly (120) can be made of a conductive material. In one embodiment, the top of the case (110) can be opened, and the cap assembly (120) can seal the open top of the case (110).

[0058] A positive terminal (130_1) electrically connected to the positive electrode and a negative terminal (130_2) electrically connected to the negative electrode can be coupled to the cap assembly (120). For example, the positive and negative terminals (130_1, 130_2) can be installed to protrude outwardly through the cap assembly (120).

[0059] According to one embodiment, a vent portion (140) may be formed on at least one surface of the battery cell (100) (e.g., in the illustrated example, the upper surface of the battery cell (100), i.e., the cap assembly (120)). The vent portion (140) may be configured to open when an internal pressure higher than a predetermined threshold pressure is detected in the battery cell (100). The vent portion (140) may serve as an exhaust passage for vent gas generated inside the battery cell (100).

[0060] According to one embodiment, the cap assembly (120) may include an electrolyte injection port (150). For example, the electrolyte injection port (150) may be a through hole formed in the cap assembly (120) and may be formed to inject electrolyte into the interior of the case (110) after the cap assembly (120) is coupled to and sealed with the opening of the case (110). The electrolyte injection port (150) may be sealed with a sealing member after the electrolyte is injected.

[0061] In FIG. 1, the cap assembly (120) is illustrated as including an anode, a cathode, a vent portion, and an electrolyte inlet, but the present disclosure is not limited thereto. The cap assembly (120) may include at least one of the anode, the cathode, the vent portion, and the electrolyte inlet, or may correspond to a cap itself that does not include any of the above.

[0062] The battery cell (100) may be a lithium battery cell, a sodium battery cell, etc. However, the scope of the present disclosure is not limited thereto, and the battery cell (100) includes all cells that can repeatedly provide electricity by charging and discharging.

[0063] FIG. 2 is a block diagram illustrating a configuration of a welding device (200) according to one embodiment of the present disclosure. According to one embodiment, the welding device (200) may include a fixing unit (210), a laser head unit (220), and a control unit (230).

[0064] The fixing member (210) can secure the battery cell to be welded. The fixing member (210) can align the position of the case so that the position of the cap assembly positioned on the opening of the case corresponds to the movement path of the laser head member (220). In addition, the fixing member (210) can support the battery cell to be welded in a fixed state while the welding operation is performed.

[0065] The laser head (220) can irradiate a laser to the cap assembly. The laser head (220) can move along the perimeter of the cap assembly positioned on the opening of the case and weld the case and the cap assembly.

[0066] The control unit (230) can control the movement of the laser head unit (220). For example, the control unit (230) can control the movement speed of the laser head unit (220). Accordingly, the control unit (230) can control the welding speed by the laser irradiated from the laser head unit (220). In addition, the control unit (230) can control the movement direction of the laser head unit (220). Accordingly, the control unit (230) can control the welding path by the laser irradiated from the laser head unit (220).

[0067] The control unit (230) can control the output of the laser head unit (220). The control unit (230) can control the intensity of the laser output output through the laser head unit (220).

[0068] The configuration of the welding device (200) illustrated in FIG. 2 is merely an example, and in some embodiments, other configurations may be additionally included in addition to the illustrated configuration, and some configurations may be omitted. If some of the above configurations are omitted, the functions of the omitted configurations may be performed by other configurations in addition to the illustrated configuration.

[0069] FIG. 3 is an exemplary drawing showing a method of welding a case (310) and a cap assembly (320) using a welding device according to one embodiment of the present disclosure, and FIG. 4 is a drawing showing a comparative example (400) of a case-cap assembly welding method. Referring to FIG. 3, a battery cell (300) may include a case (310) and a cap assembly (320). The case (310) may have an open top to form an opening. The cap assembly (320) may be placed on the opening of the case (310). The cap assembly (320) may be welded to the case (310) by a laser irradiated through a laser head (330) of the welding device.

[0070] In one embodiment, the battery cell (300) may be a square battery cell. In this case, the cap assembly (320) may have a substantially rectangular shape. For example, the cap assembly (320) may include a pair of long sides extending in the longitudinal direction of the battery cell (300), a pair of short sides extending in the width direction of the battery cell (300), and four corner portions extending from one end of the long sides and one end of the short sides to connect the long sides and the short sides.

[0071] In one embodiment, the long side may correspond to a straight line, which is a section without a change in direction. The short side may correspond to a straight line shorter than the long side, which is a section without a change in direction. The corner portion may include a section where a change in direction occurs. For example, the corner portion may include a region where the short side and the long side intersect. The short side and the long side may intersect in various ways. For example, the short side and the long side may intersect in the form of a curve while the intersection angle changes, or may intersect at a constant intersection angle (e.g., an obtuse angle, a right angle, an acute angle).

[0072] The laser head (330) can move along the periphery of the cap assembly (320) and weld the case (310) and the cap assembly (320). For example, the laser head (330) of the welding device can move (M1) while irradiating a laser along the long side of the cap assembly (320). Thereafter, the laser head (330) can move (M2) while irradiating a laser along a corner portion extended from one end of the long side of the cap assembly (320). At this time, the laser head (330) can change the movement direction from the long side direction to the short side direction at the corner portion. Thereafter, the laser head (330) can move (M3) while irradiating a laser along the short side of the cap assembly (320). Thereafter, the laser head (330) can move (M4) while irradiating a laser along a corner portion extended from one end of the short side of the cap assembly. At this time, the laser head unit (330) can change its direction of movement from the short side direction to the long side direction at the corner. Then, the laser head unit (330) can move again while irradiating the laser along the long side of the cap assembly (320). The welding sequence and welding direction illustrated in FIG. 3 are merely examples and are not limited thereto. For example, the welding device can start welding at the short side or corner of the cap assembly (320).

[0073] According to one embodiment, the welding device can control the welding speed by the laser irradiated from the laser head unit (330) by controlling the moving speed of the laser head unit (330). The welding device can reduce the takt time of battery cell (300) production by increasing the welding speed of the laser head unit (330), thereby improving the productivity of the battery cell (300). However, if the welding speed is uniformly increased regardless of the position of the welding section, there is a problem in that it is difficult to secure the homogeneity of the welding. For example, a phenomenon in which the bead flows down or overwelding occurs in a section in which the moving direction of the laser head unit (330) changes (e.g., the moving sections of M2 and M4) or the short section of the cap assembly (320).

[0074] Fig. 4 is a comparative example in which the speed and / or output of the laser head (330) is not controlled. Referring to Fig. 4, it can be confirmed that each corner (410) of the welding section is overwelded.

[0075] FIG. 5 is a drawing showing an example of the shape of a cap assembly (520) according to one embodiment of the present disclosure, and FIG. 6 is a drawing showing an example of the shape of a cap assembly (620) according to another embodiment of the present disclosure.

[0076] FIG. 5 may be a top view of a battery cell (e.g., 100 of FIG. 1) according to one embodiment of the present disclosure. A case (510) of the battery cell may have an open top to form an opening, and a cap assembly (520) may be welded onto the opening of the case (510).

[0077] Referring to FIG. 5, the cap assembly (520) may have a roughly rectangular shape including a curve at a corner portion. The cap assembly (520) may include a long side (522) extending in a first direction (X-axis), a short side (524) extending in a second direction (Y-axis), and a corner portion (526) connecting the long side (522) and the short side (524). The length of the long side (522) may be formed longer than the length of the short side (524). The corner portion (526) may extend from one end of the long side (522) and one end of the short side (524) to connect the long side (522) and the short side (524). The first direction (X-axis) may be a longitudinal direction of the battery cell. Here, the first direction (X-axis) may be perpendicular to the second direction (Y-axis). Additionally, the first direction (X-axis) may be the length direction of the battery cell, and the second direction (Y-axis) may be the width direction of the battery cell.

[0078] The laser head of the welding device can move along the perimeter of the cap assembly (520) and weld the case (510) and the cap assembly (520). For example, the laser head can move along the long side (522), the corner side (526), ​​and the short side (524) of the cap assembly (520) and irradiate the laser onto the cap assembly (520).

[0079] According to one embodiment, the long side (522) and the short side (524) of the cap assembly (520) may be straight, and the corner portion (526) may be curved. Accordingly, the laser head portion may change its direction of movement while irradiating the laser along the corner portion (526). For example, the laser head portion may change its direction of movement from the long side (522) toward the short side (524) or from the short side (524) toward the long side (522) at the corner portion (526).

[0080] In one embodiment, the entire section of the corner portion (526) may be in the shape of a curve. In this case, the laser head portion may irradiate the laser while changing the direction of movement throughout the entire section of the corner portion (526). The corner portion (526) may be formed to have a constant curvature, but is not limited thereto.

[0081] FIG. 6 may be a top view of a battery cell (e.g., 100 of FIG. 1) according to another embodiment of the present disclosure. In FIG. 6, components described or duplicated in FIG. 5 are omitted.

[0082] Referring to FIG. 6, the cap assembly (620) may have a rectangular shape. The cap assembly (620) may include a long side (622) extending in a first direction (X-axis), a short side (624) extending in a second direction (Y-axis), and a corner portion (626) connecting the long side (622) and the short side (624). The corner portion (626) may extend from one end of the long side (622) and one end of the short side (624), thereby connecting the long side (622) and the short side (624).

[0083] In one embodiment, the corner portion (626) may be in the form of a straight line intersecting with a straight line. For example, the corner portion (626) may be in the form of a straight line extending from one end of the long side (622) and a straight line extending from one end of the short side (624) intersecting perpendicularly. Accordingly, the laser head portion may change its direction of movement at the point where one end of the long side (622) and one end of the short side (624) intersect along the corner portion (626).

[0084] FIG. 5 illustrates an example in which the corner portion (526) is in the form of a curve over the entire section, and FIG. 6 illustrates an example in which the corner portion (626) is in the form of a straight line intersecting two straight lines. However, the shape of the corner portion is not limited thereto. For example, the shape of the corner portion may be formed such that it extends in the form of a straight line from one end of the long side and one end of the short side, and then connects in the form of a curve in at least a portion of the corner portion. In this case, the laser head portion may irradiate the laser while changing the direction of movement in at least a portion of the corner portion.

[0085] In one embodiment, the control unit of the welding device can control the welding speed by varying the moving speed of the laser head depending on the position of the welding section. Furthermore, the control unit of the welding device can vary the output of the laser beam output from the laser head depending on the position of the welding section. Examples of controlling the welding speed and / or laser output depending on the position of the welding section are described in detail in FIGS. 7 to 9 .

[0086] FIG. 7 is an exemplary drawing illustrating a case-cap assembly welding method according to the position of the welding section according to one embodiment of the present disclosure. As illustrated, the welding section of the cap assembly may include a first section (S1), a second section (S2), a third section (S3), and a fourth section (S4).

[0087] According to one embodiment, the first section (S1) may be located on a long side of the cap assembly. The second section (S2) connected to the first section (S1) may be located at one end of the long side of the cap assembly. The third section (S3) connected to the second section (S2) may be located on a short side and a corner of the cap assembly. The fourth section (S4) connected to the third section (S3) may be located at the other end of the long side of the cap assembly. Here, the other end of the long side may mean an end opposite to the end of the long side where the second section (S2) is located. The fourth section (S4) may again be connected to the first section (S1).

[0088] In one embodiment, the first section (S1) may be welded at a first speed, and the third section (S3) may be welded at a second speed. The first and second speeds may be different from each other. Here, the first and second speeds may be selected differently from each other within a range of 120 mm / s to 250 mm / s.

[0089] In one embodiment, the first speed may be greater than the second speed. Accordingly, welding may be performed while decelerating from the first speed to the second speed in the second section (S2) positioned between the first section (S1) and the third section (S3). Furthermore, welding may be performed while accelerating from the second speed to the first speed in the fourth section (S4) positioned between the third section (S3) and the first section (S1).

[0090] In one embodiment, the welding speed in the second section (S2) may be constantly reduced. For example, welding may be performed in the second section (S2) while the welding speed is constantly reduced from the first speed to the second speed. Additionally, the welding speed in the fourth section (S4) may be constantly accelerated. For example, welding may be performed in the fourth section (S4) while the welding speed is constantly accelerated from the second speed to the first speed.

[0091] In one embodiment, the first section (S1) may be welded with a first output. The third section (S3) may be welded with a second output. Here, the first output and the second output may be different from each other.

[0092] In one embodiment, the first output may be greater than the second output. Accordingly, the second section (S2) positioned between the first section (S1) and the third section (S3) may be welded while the laser output decreases from the first output to the second output. In addition, the fourth section (S4) positioned between the third section (S3) and the first section (S1) may be welded while the laser output increases from the second output to the first output.

[0093] In one embodiment, the laser output in the second section (S2) may be constantly reduced. For example, the second section (S2) may be welded while the laser output is constantly reduced from the first output to the second output. Additionally, the laser output in the fourth section (S4) may be constantly increased. For example, the fourth section (S4) may be welded while the laser output is constantly increased from the second output to the first output.

[0094] In one embodiment, the laser output can be controlled to correspond to the welding speed. For example, the first section (S1) can be welded at a first speed and a first output, and the third section (S3) can be welded at a second speed and a second output. In addition, the second section (S2) can be welded while the welding speed is decelerated from the first speed to the second speed and the laser output is reduced from the first output to the second output. In addition, the fourth section (S4) can be welded while the welding speed is accelerated from the second speed to the first speed and the laser output is increased from the second output to the third output. In other words, the welding speed can be controlled so that a high-output laser is irradiated in a section with a fast welding speed and a low-output laser is irradiated in a section with a slow welding speed.

[0095] According to one embodiment, the length of the second section (S2) and the fourth section (S4) may be determined according to the acceleration and / or deceleration time of the laser head. The time for which the laser head is accelerated in the second section (S2) and the time for which the laser head is decelerated in the fourth section (S4) may correspond to, but is not limited to, 40 ms to 100 ms. As a specific example, the first speed at which the laser head welds the first section (S1) may be 240 mm / s, the second speed at which the laser head welds the third section (S3) may be 120 mm / s, and the deceleration time of the laser head may be set to 40 ms. In this case, the acceleration force of the laser head may be 3,000 mm / s. 2And, the length of the second section (S2) can be determined to be approximately 7.2 mm.

[0096] According to one embodiment, the length of the second section (S2) and the fourth section (S4) can be determined according to the movement acceleration of the laser head. For example, the movement acceleration of the laser head is 2,000 mm / s. 2 Up to 4,000 mm / s 2 This may include, but is not limited to.

[0097] In one embodiment, the lengths of the second section (S2) and the fourth section (S4) may be determined based on the lengths of the long sides and / or the short sides of the cap assembly. For example, the lengths of the second section (S2) and the fourth section (S4) may be determined as a certain ratio of the lengths of the long sides and / or the short sides of the cap assembly.

[0098] By this configuration, the laser output is controlled in response to the welding speed, so that the heat input per unit length of the welding section is maintained constant, thereby ensuring the homogeneity of the welding and preventing overwelding.

[0099] In addition, since the welding speed is controlled according to the position of the welding section, the mechanical shock generated on the welding device can be reduced. For example, since the welding speed in the section where the welding direction changes (e.g., the second section (S2) and the fourth section (S4)) and the short section of the cap assembly (e.g., the third section (S3)) is controlled to be lower than the welding speed in the long section of the cap assembly (e.g., the first section (S1)), the mechanical shock generated on the welding device due to the change in the moving direction of the laser head can be reduced.

[0100] FIG. 8 is an exemplary drawing illustrating a case-cap assembly welding method according to the position of the welding section according to another embodiment of the present disclosure. Referring to FIG. 8, the welding section of the cap assembly may include a first section (S1), a second section (S2), a third section (S3), and a fourth section (S4). In FIG. 8, components described or duplicated in FIG. 7 are omitted.

[0101] According to one embodiment, the first section (S1) may be positioned on the long side of the cap assembly. The second section (S2) connected to the first section (S1) may be positioned on one end and a corner of the long side of the cap assembly. The third section (S3) connected to the second section (S2) may be positioned on the short side of the cap assembly. The fourth section (S4) connected to the third section (S3) may be positioned on the other end and a corner of the long side of the cap assembly. The fourth section (S4) may again be connected to the first section (S1).

[0102] In this case, compared to the example shown in Fig. 7, the length of the third section (S3) welded at the second speed is shortened, and the length of the first section (S1) welded at the first speed is extended, so that the overall welding time can be shortened.

[0103] FIG. 9 is an exemplary drawing illustrating a case-cap assembly welding method according to the position of the welding section according to another embodiment of the present disclosure. Referring to FIG. 9, the welding section of the cap assembly may include a first section (S1), a second section (S2), a third section (S3), and a fourth section (S4). In FIG. 9, components described or duplicated in FIG. 7 are omitted.

[0104] According to one embodiment, the first section (S1) may be positioned on a long side of the cap assembly. The second section (S2) connected to the first section (S1) may be positioned on a corner portion of the cap assembly. The third section (S3) connected to the second section (S2) may be positioned on a short side of the cap assembly. The fourth section (S4) connected to the third section (S3) may be positioned on a corner portion of the cap assembly. The fourth section (S4) may again be connected to the first section (S1).

[0105] In this case, compared to the example shown in Fig. 8, the length of the second section (S2) welded at the first or second speed is reduced, and the length of the first section (S1) welded at the first speed is extended, so that the overall welding time can be shortened.

[0106] FIG. 10 is a drawing showing an example of a graph (1000) of the movement speed of a laser head portion of a welding device according to time change according to one embodiment of the present disclosure, and FIG. 11 is a drawing showing an example of a graph (1100) of the laser output intensity of a welding device according to time change according to one embodiment of the present disclosure.

[0107] According to one embodiment, the welding device can control the welding speed by the laser irradiated from the laser head by controlling the moving speed of the laser head. In addition, the welding device can control the intensity of the laser output output through the laser head.

[0108] In one embodiment, at time t0, the welding device may receive a welding start signal. The control unit of the welding device may receive the welding start signal and secure the battery cell to be welded. For example, the position of the case may be aligned so that the position of the cap assembly of the battery cell to be welded corresponds to the movement path of the laser head, and the case may be supported in a fixed state.

[0109] In Fig. 10, the moving speed of the laser head is illustrated as being the second speed between t0 and t1, but this is not limited thereto. For example, when the laser head moves to a position corresponding to the welding path, it may move at a speed different from the second speed. In addition, in Fig. 11, the output of the laser output from the laser head is illustrated as being the second output between t0 and t1, but this is not limited thereto, and the laser may not be output between t0 and t1.

[0110] According to one embodiment, a fourth section (S4) of the cap assembly may be welded between t1 and t2. At the time point t1, the laser head may move to a position corresponding to a starting point of the fourth section (S4) of the cap assembly (e.g., a point where the third section (S3) and the fourth section (S4) are connected). Thereafter, between t1 and t2, the laser head may irradiate a laser while moving along the fourth section (S4). At this time, the moving speed of the laser head may be constantly accelerated from a second speed to a first speed. In addition, the output of the laser output from the laser head may constantly increase from a second output to a first output.

[0111] Then, at times t2 to t3, the first section (S1) of the cap assembly can be welded. At times t2 to t3, the laser head can irradiate the laser while moving along the first section (S1). At this time, the moving speed of the laser head can be the first speed, and the output of the laser output from the laser head can be the first output.

[0112] Then, at times t3 to t4, the second section (S2) of the cap assembly can be welded. At times t3 to t4, the laser head can irradiate the laser while moving along the second section (S2). At this time, the moving speed of the laser head can be constantly reduced from the first speed to the second speed. In addition, the laser output from the laser head can be constantly reduced from the first output to the second output.

[0113] Then, at times t4 to t5, the third section (S3) of the cap assembly can be welded. At times t4 to t5, the laser head can irradiate the laser while moving along the third section (S3). At this time, the moving speed of the laser head can be the second speed, and the output of the laser output from the laser head can be the second output.

[0114] Then, at times t5 to t6, the fourth section (S4) of the cap assembly can be welded. At times t5 to t6, the laser head can irradiate the laser while moving along the fourth section (S4). At this time, the moving speed of the laser head can be constantly accelerated from the second speed to the first speed. In addition, the output of the laser output from the laser head can constantly increase from the second output to the first output.

[0115] Then, similarly to what was described above, from t6 to t7, the first section (S1) of the cap assembly can be welded at the first speed and the first output. In addition, from t7 to t8, the second section (S2) of the cap assembly can be welded while the moving speed of the laser head is constantly reduced from the first speed to the second speed and the output of the laser output from the laser head is constantly reduced from the first output to the second output. In addition, from t8 to t9, the third section (S3) of the cap assembly can be welded at the second speed and the second output.

[0116] Then, at time t9, welding of the cap assembly is completed, and the welding device may receive a welding completion signal. In one embodiment, the welding device may be controlled to prepare for welding of a subsequent target battery cell upon receiving the welding completion signal. Alternatively, the welding device may be controlled to terminate the welding operation.

[0117] In one embodiment, the first speed and the second speed may be 120 mm / s to 250 mm / s. In addition, t1 to t2, t3 to t 4, The time intervals of t5 to t6 and t7 to t8 can be set to 40 ms to 100 ms, but are not limited thereto.

[0118] In FIGS. 10 and 11, it is described that the fourth section (S4) of the cap assembly is welded first, followed by the first section (S1), the second section (S2), and the third section (S3) in that order, but this is not limited thereto, and the section where welding begins and the welding order may be appropriately changed depending on the settings of the welding device.

[0119] FIG. 12 is a flowchart illustrating a case-cap assembly welding method (1200) according to one embodiment of the present disclosure. According to one embodiment, the case-cap assembly welding method (1200) may be initiated by welding a first section (S1) of a cap assembly disposed on an opening of a case at a first speed (S1210). Here, the first section (S1) of the cap assembly may be welded at a first output.

[0120] Then, the second section (S2) of the cap assembly can be welded while the welding speed changes from the first speed to a second speed different from the first speed (S1220). According to one embodiment, each of the first speed and the second speed can be selected in the range of 120 mm / s to 250 mm / s. At this time, the second section (S2) of the cap assembly can be welded while the welding speed is constantly reduced from the first speed to the second speed. In addition, the second section (S2) of the cap assembly can be welded while the welding output changes from the first output to the second output. At this time, the second section (S2) of the cap assembly can be welded while the welding output is constantly reduced from the first output to the second output.

[0121] Then, the third section (S3) of the cap assembly can be welded at a second speed (S1230). Here, the third section (S3) of the cap assembly can be welded at a second output that is lower than the first output.

[0122] Then, the fourth section (S4) of the cap assembly can be welded while the welding speed changes from the second speed to the first speed. Here, the fourth section (S4) of the cap assembly can be welded while the welding speed is constantly accelerated from the second speed to the first speed. In addition, the fourth section (S4) of the cap assembly can be welded while the welding output changes from the second output to the first output.

[0123] In one embodiment, the cap assembly may include a long side and a short side extending in a direction intersecting the long side. In one embodiment, the cap assembly further includes a corner portion connecting one end of the long side and one end of the short side, and the corner portion may include a section where the welding direction changes. As a specific example, the corner portion may have a curved shape, and the welding direction may change over the entire section of the corner portion. In another example, the welding direction may change over at least a portion of the corner portion.

[0124] In one embodiment, the first section (S1) may be positioned on the long side, and at least a portion of the third section (S3) may be positioned on the short side. In addition, the second section (S2) may be positioned between the first section (S1) and the third section (S3). Additionally, the fourth section (S4) may be connected to the third section (S3). As a specific example, the second section (S2) may be positioned on one end of the long side, and the third section (S3) may be positioned on the short side and the corner portion. In another example, the second section (S2) may be positioned on one end of the long side and the corner portion. In yet another example, the second section (S2) may be positioned on the corner portion.

[0125] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. For a cap assembly placed on an opening of a case, a step of welding a first section (S1) of the cap assembly at a first speed; A step of welding the second section (S2) of the cap assembly while changing the welding speed from the first speed to a second speed different from the first speed; and A step of welding the third section (S3) of the above cap assembly at the second speed. Including, The cap assembly includes a long side and a short side extending in a direction intersecting the long side, The above first section (S1) is located on the long side, A case-cap assembly welding method, wherein at least a portion of the third section (S3) is located on the short side.

2. In paragraph 1, The step of welding the second section (S2) of the cap assembly while changing from the first speed to a second speed different from the first speed is, A case-cap assembly welding method, comprising a step of welding while constantly decelerating from the first speed to the second speed.

3. In paragraph 1, The step of welding the first section (S1) of the above cap assembly at the first speed is: In the first section (S1) of the above cap assembly, a step of welding the output of the welding as the first output is included, The step of welding the third section (S3) of the above cap assembly at the second speed is: A case-cap assembly welding method, comprising a step of welding the output of the welding at a second output lower than the first output in the third section (S3) of the cap assembly.

4. In paragraph 3, The step of welding the second section (S2) of the cap assembly while changing from the first speed to a second speed different from the first speed is, A case-cap assembly welding method, comprising a step of welding while changing the output of the welding from the first output to the second output in the second section (S2) of the cap assembly.

5. In paragraph 4, The step of welding by changing the output of the above welding from the first output to the second output is as follows: A case-cap assembly welding method, comprising a step of welding while constantly reducing the output of the welding from the first output to the second output.

6. In paragraph 1, A case-can welding method, wherein the second section (S2) is positioned between the first section (S1) and the third section (S3).

7. In paragraph 1, The above cap assembly, A corner portion connecting one end of the above long side and one end of the above short side Including more, A case-cap assembly welding method, wherein the corner section includes a section where the welding direction changes.

8. In paragraph 7, The above corner part is in the shape of a curve, A case-cap assembly welding method in which the welding direction is changed over the entire section of the above corner portion.

9. In paragraph 7, A case-cap assembly welding method in which the welding direction is changed in at least a portion of the above corner portion.

10. In paragraph 7, The above second section (S2) is located at one end of the long side, A case-cap assembly welding method, wherein the third section (S3) is located on the short side and the corner portion.

11. In paragraph 7, A case-cap assembly welding method, wherein the second section (S2) is located on one end of the long side and the corner portion.

12. In paragraph 7, The second section (S2) is a case-cap assembly welding method located on the corner portion.

13. In paragraph 1, A case-cap assembly welding method, wherein each of the first speed and the second speed is 120 mm / s to 250 mm / s.

14. In paragraph 1, Further comprising a step of welding the fourth section (S4) of the cap assembly while changing from the second speed to the first speed, A case-cap assembly welding method in which the fourth section (S4) is connected to the third section (S3).

15. In paragraph 14, The step of welding the fourth section (S4) of the above cap assembly while changing from the second speed to the first speed is, A case-cap assembly welding method, comprising a step of welding by constantly accelerating from the second speed to the first speed.

16. In paragraph 14, The step of welding the fourth section (S4) of the above cap assembly while changing from the second speed to the first speed is, A case-cap assembly welding method, comprising a step of welding while changing the output of the welding from the second output to the first output in the fourth section (S4) of the cap assembly.

17. Fixed part supporting the case; A laser head unit that irradiates a laser to a cap assembly placed on the opening of the case; and A control unit that controls at least one of the welding speed or laser output of the above laser head unit. Including, The above laser head part, Welding the first section (S1) of the above cap assembly at the first speed, The second section (S2) of the above cap assembly is welded while changing the welding speed from the first speed to a second speed different from the first speed, The third section (S3) of the above cap assembly is controlled to be welded at the second speed, The cap assembly includes a long side and a short side extending in a direction intersecting the long side, The above first section (S1) is located on the long side, A welding device, wherein at least a portion of the third section (S3) is located on the short side.

18. In paragraph 17, The above laser head part, Welding the first section (S1) of the above cap assembly to the first output, The second section (S2) of the cap assembly is welded while changing from the first output to a second output different from the first output, A welding device controlled to weld the third section (S3) of the cap assembly with the second output.

19. In paragraph 17, The above laser head part, A welding device controlled to weld the second section (S2) of the cap assembly while constantly decelerating from the first speed to the second speed.

20. In paragraph 18, The above laser head part, A welding device controlled to weld the second section (S2) of the cap assembly while constantly reducing the laser output from the first output to the second output.

Images