Method and apparatus for inspecting welding rod, and method for manufacturing secondary battery comprising same

Abstract

The present invention relates to a method and an apparatus for inspecting a welding rod, and a method for manufacturing a secondary battery comprising same, the method and the apparatus enabling: a damaged state of a welding rod used during secondary battery manufacturing to be detected at an early stage such that continuous production without quality defects is possible; human error to be removed by changing a conventional qualitative evaluation method to a quantitative method such that management standards are improved; and a production amount to be increased according to a reduction in equipment downtime and quality costs to be reduced according to quality improvement.

Description

Welding rod inspection method and inspection device, and secondary battery manufacturing method including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0187682, filed December 20, 2023, and Korean Patent Application No. 10-2024-0163235, filed November 15, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a welding rod inspection method and an inspection device, and a secondary battery manufacturing method including the same, and has the feature of enabling continuous production without quality defects by early identification of the damage status of a welding rod used in a secondary battery manufacturing process, and has the effect of improving the management level by eliminating human error by changing an existing qualitative evaluation method to a quantitative method, and can increase production volume by reducing equipment downtime and reduce quality costs by improving quality. The present invention relates to a welding rod inspection method and an inspection device, and a secondary battery manufacturing method including the same.

[0005] In recent years, rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution have made the demand for eco-friendly alternative energy sources essential for future living. Research is continuing into various power generation technologies, such as solar, wind, and tidal power. Furthermore, significant interest is being focused on power storage devices, such as batteries, to more efficiently utilize the generated electricity.

[0006] Moreover, with the technological development and increasing demand for battery-powered electronic mobile devices and electric vehicles, the demand for batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on batteries that can meet various needs.

[0007] In particular, in terms of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries, which have advantages such as high energy density, discharge voltage, and output stability.

[0008] Secondary batteries can be classified into cylindrical and square batteries, in which the electrode assembly is built into a cylindrical or square metal can, and pouch-type batteries, in which the electrode assembly is built into a pouch-type case made of aluminum laminate sheet, depending on the shape of the battery case.

[0009] Resistance welding and ultrasonic welding are used to connect the can bottom and electrode connectors (e.g., electrode tabs) during the assembly stage of conventional cylindrical secondary batteries. Because resistance welding and ultrasonic welding perform welding through energy transferred through physical contact, the quality of the contact surface is crucial. As the contact surface expands, energy density decreases, resulting in insufficient welding energy per unit area, resulting in weak welding. Furthermore, wear or misalignment can cause excessive energy density to be concentrated on one side, resulting in over-welding.

[0010] Conventional management for checking the contact surface and pressure of resistance welding rods or ultrasonic welding tools used in welding has relied solely on visual qualitative assessments, resulting in a lack of standards for quality assessment. Therefore, a method capable of quantitatively assessing and inspecting the contact surface of resistance welding rods and ultrasonic welding tools is needed.

[0011] In particular, conventional qualitative quality assessments could be subject to errors between engineers or human error, and there was a problem in that they could not be inspected efficiently because they could not be confirmed while the welding equipment was in operation.

[0012] The present invention has been made to solve the above problems, and the object of the present invention is to provide a welding rod inspection method and inspection device, and a secondary battery manufacturing method including the same, which have the feature of enabling continuous production without quality defects by early identification of the damage status of a welding rod used in a secondary battery manufacturing process, and the effect of improving the management level by eliminating human error by changing the existing qualitative evaluation method to a quantitative method, and which can increase production volume by reducing equipment downtime and reduce quality costs by improving quality.

[0013] The present invention relates to a welding rod inspection method for inspecting a welding rod used in a welding process of a secondary battery can, which includes an initial standby step in which the welding rod is in a standby state before the secondary battery can is inserted for welding, a pre-welding standby step in which the can is inserted and the welding rod is in a standby state, a welding step in which the welding rod pressurizes and welds the can and the electrode tab to be welded to the can, a post-welding standby step in which the welding rod returns to a standby state after the welding step, and a transfer step in which the can is moved to the next process, and the method includes an electronic pressure sensitive paper insertion step in which electronic pressure sensitive paper is inserted instead of the can in the pre-welding standby step, a pressurization step in which the welding rod pressurizes the electronic pressure sensitive paper inserted instead of the can and the electrode tab in the welding step, an inspection step in which at least one of the pressure and the surface condition of the welding rod is inspected through the pressurization of the electronic pressure sensitive paper, and a recovery step in which the electronic pressure sensitive paper is recovered in the transfer step.

[0014] The welding process of the can for the secondary battery is performed by a rotary welding equipment that rotates in a circular manner, and the electronic pressure sensitive paper can perform the necessary steps while moving in a curved manner along a curved guide rail.

[0015] Based on the angle measurement reference point of the rotary welding equipment, the pre-welding waiting step is performed at a position of 90 degrees (3 o'clock position), the welding step is performed at a position of 180 degrees (6 o'clock position), and the transfer step is performed at a position of 270 degrees (9 o'clock position). Accordingly, the electronic pressure sensitive paper feeding step can be performed at a position of 90 degrees, the pressurization step can be performed at a position of 180 degrees, and the recovery step can be performed at a position of 270 degrees.

[0016] The electronic pressure plate can move along the curved guide rail to a 90 degree position (3 o'clock position), a 180 degree position (6 o'clock position), and a 270 degree position (9 o'clock position).

[0017] The welding rod includes an upper welding rod and a lower welding rod, and in the pressurizing step, the electronic pressure reducing device can be pressurized from above and below by the upper welding rod and the lower welding rod.

[0018] The above welding may be resistance welding or ultrasonic welding.

[0019] The electronic pressure sensor may include multiple measurement nodes.

[0020] The measurement node can have a width of 0.01 mm to 0.1 mm.

[0021] The pitch between the measuring nodes can have a value of 0.01 mm to 0.2 mm.

[0022] The inspection step may include a measurement step for measuring the surface pressure state of the electronic pressure sensitive paper, an area setting step for setting a pressure measurement range within the measured pressure distribution, a pressure calculation step for calculating a pressure value by adding up the pressures of multiple measurement nodes within the set area, and a judgment step for determining whether the pressure value calculated within the set area satisfies the set standard pressure and determining whether it is good or bad based on the result.

[0023] The inspection step may include a measurement step for measuring the surface pressure state of the electronic pressure sensitive paper, a region setting step for setting a pressure measurement range within the measured pressure distribution, a pressure shape analysis step for analyzing a pressure shape formed by the electronic pressure sensitive paper within the range, and a judgment step for determining whether the pressure shape satisfies a standard pressure shape and determining pass or fail based on the result.

[0024] The inspection step may include a measurement step for measuring the surface pressure state of an electronic pressure sensitive paper, an area setting step for setting a pressure measurement range within the measured pressure distribution, a pressure calculation step for calculating a pressure value by adding up the pressure of multiple measurement nodes within the set area, a pressure shape analysis step for analyzing a pressure shape formed by the electronic pressure sensitive paper, and a judgment step for determining whether the pressure value calculated within the set area satisfies a set reference pressure and whether the pressure shape satisfies the reference pressure shape, and determining pass or fail based on the results.

[0025] The device may further include a device alarm step that transmits the determined pass / fail judgment data from the judgment step to the device to determine whether to stop or start the device.

[0026] Before the pressurizing step, the welding step further includes a pre-pressurizing step in which the welding rod presses the electronic pressure sensitive paper with a lower pressure than the pressing force for welding in the welding step, and in the pressurizing step, the welding rod can press the electronic pressure sensitive paper with the pressing force for welding in the welding step.

[0027] The present invention relates to a welding rod inspection device for inspecting a welding rod used in a welding process of a secondary battery can, which includes an initial standby stage in which a welding rod is in a standby state before a secondary battery can is put in for welding, a pre-welding standby stage in which the can is put in and the welding rod is in a standby state, a welding stage in which the welding rod pressurizes and welds an electrode tab to be welded to the can, a post-welding standby stage in which the welding rod returns to a standby state again after the welding stage, and a transfer stage in which the can is moved to a next process, and includes an electronic pressure-sensitive paper for inspecting a welding rod by receiving pressure from the welding rod, a bracket on which the electronic pressure-sensitive paper is fixedly installed, and a curved guide rail for guiding the bracket on which the electronic pressure-sensitive paper is installed to move in a curved shape.

[0028] The welding process of the can for the secondary battery is performed by a rotary welding equipment that rotates in a circular manner, and based on the angle measurement reference point of the rotary welding equipment, the bracket can move to a 90 degree position, a 180 degree position, and a 270 degree position along a curved guide rail.

[0029] The bracket may include a bracket body into which an electronic pressure sensor is inserted, and a fixing member coupled to the bracket body and for fixing and installing the electronic pressure sensor.

[0030] The guide rail may be equipped with a stopper to limit the movement of the bracket.

[0031] The secondary battery manufacturing method according to the present invention is:

[0032] A welding process of a secondary battery can, comprising: an initial waiting step in which a welding rod is in a waiting state before a secondary battery can is put in for welding; a pre-welding waiting step in which the can is put in and the welding rod is in a waiting state; a welding step in which the welding rod pressurizes and welds the can and the electrode tab to be welded to the can; a post-welding waiting step in which the welding rod returns to a waiting state again after the welding step; and a transfer step in which the can is moved to the next process; and a welding rod inspection method according to claim 1 for inspecting a welding rod used in the welding process of a secondary battery can, characterized in that the welding rod inspection method is performed once every n times the welding process of the secondary battery can is performed (wherein n is a natural number equal to or greater than 2).

[0033] The welding rod inspection method and inspection device according to the present invention, and the secondary battery manufacturing method including the same, have the characteristics of enabling continuous production without quality defects by early identification of the damage status of the welding rod used in the secondary battery manufacturing process, and the existing qualitative evaluation method can be changed to a quantitative method to eliminate human error, thereby improving the management level, and the production volume can be increased due to a reduction in equipment downtime, and the quality cost can be reduced due to improved quality.

[0034] FIG. 1 is a perspective view illustrating a rotary welding equipment and a welding rod inspection device used in a welding rod inspection method according to an embodiment of the present invention.

[0035] FIG. 2 is a perspective view illustrating a welding rod inspection device according to an embodiment of the present invention.

[0036] FIG. 3 is a perspective view showing an electronic pressure sensor and a bracket among the welding rod inspection devices according to an embodiment of the present invention.

[0037] FIG. 4 is a drawing showing an electronic pressure gauge measuring the state of a welding rod in a welding rod inspection device according to an embodiment of the present invention. (a) is a drawing showing a normal state (no wear), and (b) is a drawing showing an abnormal state (with wear).

[0038] FIG. 5 is a diagram illustrating each step of a welding rod inspection method according to an embodiment of the present invention.

[0039] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0040] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0041] In addition, terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0042]

[0043] Example 1 - Welding rod inspection method

[0044] FIG. 1 is a perspective view illustrating a rotary welding equipment and a welding rod inspection device used in a welding rod inspection method according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a welding rod inspection device according to an embodiment of the present invention. FIG. 3 is a perspective view illustrating an electronic pressure-sensitive paper and a bracket among the welding rod inspection devices according to an embodiment of the present invention. FIG. 4 is a drawing illustrating a state of a welding rod measured by an electronic pressure-sensitive paper in a welding rod inspection device according to an embodiment of the present invention, where (a) is a drawing illustrating a normal state (no wear) and (b) is a drawing illustrating an abnormal state (with wear). FIG. 5 is a diagram illustrating each step of a welding rod inspection method according to an embodiment of the present invention.

[0045] Referring to FIGS. 1 to 3, a method for inspecting a welding rod (10, 20) according to Example 1 of the present invention relates to a method for inspecting a welding rod (10, 20) used in a welding process of a secondary battery can (not shown). At this time, the welding process may be, for example, resistance welding or ultrasonic welding.

[0046] In order to explain the inspection method of the welding rod (10, 20) according to the first embodiment of the present invention, the welding process of a secondary battery can will first be explained with reference to FIG. 1. FIG. 1 illustrates equipment for welding a secondary battery. The welding equipment may be a device that welds a secondary battery can and an electrode tab connected to an electrode assembly inserted into the secondary battery can. This welding process of the can can be performed by a rotary welding equipment (1) that rotates circularly.

[0047] The welding process of a secondary battery can may include an initial waiting stage, a pre-welding waiting stage, a welding stage, a post-welding waiting stage, and a transport stage. The method for inspecting a welding rod (10, 20) of the present invention may be a method for inspecting a welding rod (10, 20) used in the welding process of a secondary battery can, which includes the above welding stages.

[0048] The welding process of a secondary battery can will first be described. The initial standby stage may be a stage in which the welding rods (10, 20) are in a standby state before the secondary battery can is put in for welding. The welding rods (10, 20) may include an upper welding rod (10) and a lower welding rod (20). In the subsequent welding stage, the upper welding rod (10) and the lower welding rod (20) may approach the welding target from the upper and lower sides to perform welding. That is, the upper welding rod (10) may descend from the upper side to perform welding, and the lower welding rod (20) may rise from the lower side to perform welding. To this end, in the initial standby stage, the upper welding rod (10) may be in a standby state at the upper side, and the lower welding rod (20) may be in a standby state at the lower side.

[0049] The pre-welding waiting stage may be a stage where the can is inserted and the welding rod (10, 20) is in a waiting state. That is, the can may be inserted into the welding position while the welding rod (10, 20) is in a waiting state similar to the initial waiting stage. In this stage, the upper welding rod (10) may still be in a waiting state at the upper side of the can, and the lower welding rod (20) may be in a waiting state at the lower side of the can.

[0050] Referring to Fig. 1, since the rotary welding equipment (1) for welding is formed in a circular shape, a reference point for angle measurement can be set in the circular rotary welding equipment (1). For example, in the rotary equipment illustrated in Fig. 1, the reference point for angle measurement can be an invisible part at the rear of the equipment. This reference point can be set as a point where the angle is 0 degrees. And the angle can be determined in a clockwise direction. When determined in this way, the part visible on the right side of the equipment in Fig. 1 can be a 90 degree position (①). This can be conveniently referred to as the 3 o'clock position (①). And the part visible on the front of the equipment can be a 180 degree position (②). This can be conveniently referred to as the 6 o'clock position (②). The part visible on the right side of the equipment can be a 270 degree position (③). This can be conveniently referred to as the 9 o'clock position (③).

[0051] Based on this criterion, that is, based on the angle measurement reference point of the rotary welding equipment (1), the previously described pre-welding waiting step can be performed at a 90 degree position (= 3 o'clock position) (①). At this 3 o'clock position (①), a can (not shown) can be introduced into the welding position between the upper welding electrode (10) and the lower welding electrode (20).

[0052] The welding step may be a step in which the welding rod (10, 20) pressurizes and welds the can and the electrode tab, which is the object to be welded to the can. Here, the electrode tab may be an electrode connector connected to the electrode of the electrode assembly inserted inside the can. Any such electrode connector may be considered as the electrode tab in the present invention without being limited by the name. In addition, based on the angle measurement reference point of the rotary welding equipment (1) described above, the welding step may be performed at a position of 180 degrees (= 6 o'clock position) (②). That is, when the welding rod (10, 20), which was in the standby step before the 3 o'clock welding, rotates about 90 degrees and moves to a position of 180 degrees (= 6 o'clock position) (②), the can may also rotate with the welding rod and move to a position of 180 degrees (= 6 o'clock position) (②). In addition, welding may be performed at the 6 o'clock position.

[0053] In the welding step, the upper welding rod (10) can be lowered from the upper side of the welding object (e.g., an object in which a can and an electrode tab are overlapped) toward the welding object and pressurize the upper side of the welding object to perform welding. In addition, the lower welding rod (20) can be raised from the lower side of the welding object toward the welding object and pressurize the lower side of the welding object to perform welding.

[0054] The post-welding waiting stage may be a stage in which the welding electrodes (10, 20) return to a waiting state after the welding stage. The upper welding electrode (10) may be raised again to the upper side of the welding object (e.g., a can), and the lower welding electrode (20) may be lowered again to the lower side of the welding object.

[0055] The transfer step may be the step where the welded can is transferred to the next process. This transfer step may be performed at a 270-degree angle (9 o'clock position) (③). During the transfer step, the can may be ejected outward from the welding position between the upper welding rod (10) and the lower welding rod (20). In Fig. 1, the outward direction may be the direction toward the left of the rotary welding equipment (1).

[0056] The welding rod (10, 20) inspection method according to Embodiment 1 of the present invention is a method of inspecting a welding rod (10, 20) used in a welding process of a secondary battery can, which includes an initial waiting step, a pre-welding waiting step, a welding step, a post-welding waiting step, and a transport step, and includes an electronic pressure-sensitive paper insertion step (S1), a pressurization step (S2), an inspection step (S3), and a recovery step (S4) (see FIG. 5). The welding rod (10, 20) inspection method according to Embodiment 1 of the present invention may have a differentiated feature in that an electronic pressure-sensitive paper (110) is inserted into a position where a secondary battery can is inserted in the welding process, and the electronic pressure-sensitive paper (110) inspects the welding rod (10, 20) while following the process in which the secondary battery can is welded.

[0057]

[0058] First, in order to perform the welding rod (10, 20) inspection method according to Example 1 of the present invention, appropriate inspection equipment may be required. This welding rod inspection device (100) will be briefly described below with reference to FIGS. 2 and 3.

[0059] The welding rod inspection device (100) may largely include an electronic pressure sensitive paper (110), a bracket (120), and a guide rail (130). The electronic pressure sensitive paper (110) may be configured to inspect the welding rod (10, 20) by receiving pressure from the welding rod (10, 20). The bracket (120) may be configured to have the electronic pressure sensitive paper (110) fixedly installed. In addition, the guide rail (130) may be configured to guide the bracket (120) on which the electronic pressure sensitive paper (110) is installed to move in a curved shape. The electronic pressure sensitive paper (110) may perform necessary steps while moving in a curved shape along the curved guide rail (130).

[0060] The electronic pressure sensor (110) may include a plurality of measurement nodes (111). The measurement nodes (111) may be the minimum unit configurations that perform measurements, as illustrated in FIG. 4. The plurality of measurement nodes (111) may be arranged in a grid pattern to perform measurements. The measurements taken by each measurement node (111) may be combined to obtain an overall result value.

[0061] For this purpose, the width (d) of the measurement node (111) may have a value of 0.01 mm to 0.1 mm. And the pitch (p) between the measurement nodes (111) may have a value of 0.01 mm to 0.2 mm. Here, the pitch (p) between the measurement nodes (111) and the measurement nodes (111) may mean the gap between the measurement nodes (111) and the measurement nodes (111). The smaller the width (d) and pitch (p) of the measurement nodes (111), the more precise the inspection results can be obtained.

[0062] And the bracket (120) may include a bracket body (121) and a fixing member (122). Here, the bracket body (121) may be configured to have an electronic pressure sensitive device (110) inserted therein. The bracket (120) may include an upper block (121-1) and a lower block (121-2), and the electronic pressure sensitive device (110) may be inserted into and installed in the upper block (121-1) and the lower block (121-2).

[0063] And the fixing member (122) is coupled to the bracket body (121) and may be configured to fixally install the electronic pressure sensitive paper (110). The fixing member (122) may penetrate the upper block (121-1) and pressurize the electronic pressure sensitive paper (110) and fix it so that it does not move forward or backward. For example, the fixing member (122) may be a screw member.

[0064] The guide rail (130) can guide the bracket (120) to move in a curved shape, more specifically, to move in a circular shape. Accordingly, the bracket (120) can move along the guide rail (130) to a 90 degree position (=3 o'clock position) (①), a 180 degree position (=6 o'clock position) (②), and a 270 degree position (=9 o'clock position) (③) based on the angle measurement reference point of the rotary welding equipment (1).

[0065] And a stopper (131) may be installed on the guide rail (130) to limit the movement of the bracket (120). The position where the bracket (120) is stopped by this stopper (131) may be the origin of the rotational movement of the bracket (120).

[0066] The welding rod (10, 20) inspection method according to Example 1 of the present invention can be performed using such a welding rod inspection device (100).

[0067]

[0068] Referring to FIG. 5, the method for inspecting a welding rod (10, 20) according to Example 1 of the present invention includes an electronic pressure-sensitive paper insertion step (S1), a pressurization step (S2), an inspection step (S3), and a recovery step (S4). In addition, the electronic pressure-sensitive paper (110) can perform the necessary steps while moving in a curved manner along a curved guide rail (130).

[0069] In the welding electrode (10, 20) inspection method according to Embodiment 1 of the present invention, first, the electronic pressure-sensitive paper insertion step (S1) may be a step of inserting the electronic pressure-sensitive paper (110) instead of the can in the pre-welding standby step. This electronic pressure-sensitive paper insertion step (S1) may be performed at a position of 90 degrees (=3 o'clock position) (①) based on the angle measurement reference point of the rotary welding equipment (1). In the electronic pressure-sensitive paper insertion step (S1) corresponding to the pre-welding standby step, the upper welding electrode (10) may be in a state of waiting above the electronic pressure-sensitive paper (110), and the lower welding electrode (20) may be in a state of waiting below the electronic pressure-sensitive paper (110).

[0070] The pressurizing step (S2) may be a step in which the welding rod (10, 20) pressurizes the electronic pressure sensitive paper (110) (input instead of the can and electrode tab) in the welding step. The pressurizing step (S2) may be performed at a 180 degree position (= 6 o'clock position) (②). In the pressurizing step (S2), the electronic pressure sensitive paper (110) may be pressurized from above and below by the upper welding rod (10) and the lower welding rod (20). When the process of moving from the electronic pressure sensitive paper insertion step (S1) to the pressurizing step (S2) is performed, the electronic pressure sensitive paper (110) may move from a 90 degree position (3 o'clock position) to a 180 degree position (6 o'clock position) along a curved guide rail (130).

[0071] In addition, the inspection step (S3) may be a step of inspecting at least one of the pressure and surface condition of the welding rod (10, 20) by applying pressure to the electronic pressure-sensitive paper (110). Here, the pressure inspection may be an inspection of whether the pressure applied to the welding rod (10, 20) to weld the can is an appropriate pressure. Therefore, if the welding rod is made to pressurize the electronic pressure-sensitive paper (110) with the same pressure as the can, it is easy to determine whether the pressure applied to the welding rod (10, 20) during welding is within a normal range.

[0072] And inspecting the surface condition of the welding rod (10, 20) may mean inspecting the degree of surface wear. For example, it may mean inspecting the horizontality of the welding rod (10, 20). The surface condition can be inspected by measuring the condition in advance in the initial normal state before using the welding rod (10, 20) and comparing it with a reference value. When the welding rod (10, 20) in the normal state that is not worn is pressed against the electronic pressure-sensitive paper (110) at a set pressure, the shape detected by the electronic pressure-sensitive paper (110) can be set as the reference shape. Then, the shape detected when the used welding rod (10, 20) that is the inspection target is pressed against the electronic pressure-sensitive paper (110) at the set pressure is measured and compared to see whether it is the same as or different from the reference shape, and if different, how different it is, thereby judging whether the surface condition (horizontalness) of the welding rod (10, 20) that is the inspection target is good or bad.

[0073] Here, the inspection step (S3) may specifically include a measurement step, an area setting step, a pressure calculation step, a pressure shape analysis step, and a judgment step.

[0074] The measurement step may be a step of measuring the surface pressure state of the electronic pressure sensitive paper (110). FIG. 4 illustrates a screen in which the result of the electronic pressure sensitive paper (110) measuring the welding rod (10, 20) to be inspected is displayed on a monitor or the like. As illustrated in FIG. 4, when the welding rod (10, 20) presses the electronic pressure sensitive paper (110) with a set pressure (the pressure applied when the welding rod welds the can), the measurement result may appear as in FIG. 4. The electronic pressure sensitive paper (110) includes a plurality of measurement nodes (111), and in FIG. 4, the measurement value may appear in a state in which squares corresponding to the plurality of measurement nodes (111) are arranged in a grid shape.

[0075] The region setting step may be to set the pressure measurement range within the measured pressure distribution. For example, it may be to determine which range (area) among the multiple squares corresponding to the measurement node (111) illustrated in FIG. 4 will be set as the analysis target. For example, squares including the differently colored portions in FIG. 4 may be set as the analysis target range.

[0076] The pressure calculation step may be a step of calculating a pressure value by adding up the pressures of multiple measurement nodes (111) within a set area. That is, there will be a pressure measured by each measurement node (111), and by adding up these pressure values, the pressure applied by the welding rod can be obtained.

[0077] The pressurized shape analysis step may be a step of analyzing the pressurized shape formed by the electronic pressure-sensitive paper (110). That is, as described above, when the welding rod in a normal, unworn state presses the electronic pressure-sensitive paper (110) at a set pressure, the shape detected by the electronic pressure-sensitive paper (110) can be set as the reference pressurized shape. Then, the pressurized shape can be obtained by measuring the shape detected when the welding rod as the inspection target presses the electronic pressure-sensitive paper (110) at the set pressure. Then, it can be compared and analyzed whether this pressurized shape and the reference pressurized shape are the same or different, and if different, how different they are.

[0078] And, the judgment step may be a step of judging whether the pressure value produced within the set area satisfies the set standard pressure and whether the pressure shape satisfies the standard pressure shape, and judging whether it is acceptable or not based on the result.

[0079] The inspection step (S3) described above may be performed by performing both the pressure calculation step and the pressure shape analysis step, and determining the product as good if both results are satisfactory. However, the present invention is not limited thereto.

[0080] That is, it can be applied in a way that it determines whether a product is good or bad by performing only one of the pressing force calculation step and the pressing shape analysis step. In other words, the present invention can be applied in a way that only the pressing force calculation step is performed after the area setting step, and in the judgment step, it is determined whether the pressing force value calculated within the set area satisfies the set standard pressing force, and the result is used to determine whether the product is good or bad and end the process.

[0081] In addition, the present invention can be applied in a manner in which only the pressure shape analysis step is performed after the area setting step, and in the judgment step, it is determined whether the pressure shape satisfies the standard pressure shape, and then the result is used to determine whether the product is acceptable or not.

[0082] The present invention utilizes an electronic pressure sensitive paper (110) to inspect a welding rod (10, 20) using the conventional welding process, thereby enabling early identification of damage to the welding rod (10, 20) used in the secondary battery manufacturing process, thereby enabling continuous production without quality defects. In addition, the existing qualitative evaluation method can be changed to a quantitative method, thereby eliminating human error, thereby improving the management level. In addition, since inspection can be performed while the welding process is in progress, production can be increased due to a reduction in equipment downtime, and quality costs can be reduced due to improved quality.

[0083] Meanwhile, a recovery step (S4) may be performed after the inspection step (S3). The recovery step (S4) is performed in the transport step where the can is transferred to the next process, and may be a step where the electronic pressure sensitive paper (110) is recovered instead of the can. Referring to Fig. 1, this recovery step (S4) may be performed at a position of 270 degrees (9 o'clock position) (③) based on the angle measurement reference point of the rotary welding equipment (1). The electronic pressure sensitive paper (110) may be moved to a position of 270 degrees (9 o'clock position) along the guide rail (130) and then moved again to a position at a different angle after the recovery step (S4).

[0084] Meanwhile, the welding electrode (10, 20) inspection method according to Embodiment 1 of the present invention may further include an equipment alarm step that transmits the pass / fail judgment data determined in the judgment step to the equipment to determine whether to stop or operate the equipment. If the product is determined to be pass / fail, welding can proceed, but if it is determined to be defective, the equipment can be stopped. Of course, the equipment can be stopped, the welding electrode (10, 20) replaced, and the welding process can be resumed.

[0085] And in the welding electrode (10, 20) inspection method of the present invention, as another embodiment, prior to the pressurizing step (S2), a pre-pressurizing step may be further included in which the welding electrode (10, 20) presses the electronic pressure-sensitive paper (110) with a lower pressure than the pressing force for welding in the welding step. In the pre-pressurizing step, the welding electrode (10, 20) may press the electronic pressure-sensitive paper (110) with a pressure lower than the main pressure, and then in the pressurizing step (S2), the welding electrode (10, 20) may press the electronic pressure-sensitive paper (110) with the main pressure (i.e., the pressing force for welding in the welding step). In this case, it is possible to prevent a temporary large impact from being applied to the electronic pressure-sensitive paper (110) by applying the main pressure all at once.

[0086]

[0087] Example 2 - Welding rod inspection device

[0088] Fig. 2 is a perspective view illustrating a welding rod inspection device (100) according to an embodiment of the present invention. Fig. 3 is a perspective view illustrating an electronic pressure-sensitive paper (110) and a bracket (120) in a welding rod inspection device (100) according to an embodiment of the present invention. Fig. 4 is a drawing illustrating a state of a welding rod (10, 20) measured by an electronic pressure-sensitive paper (110) in a welding rod inspection device (100) according to an embodiment of the present invention, where (a) is a drawing illustrating a normal state (no wear), and (b) is a drawing illustrating an abnormal state (with wear).

[0089] Embodiment 2 of the present invention differs from Embodiment 1 in that it relates to a welding rod inspection device (100) used in a method for inspecting a welding rod (10, 20).

[0090] We will explain Example 2 focusing on the differences, omitting as much of the common content as possible with Example 1. In other words, it is self-evident that if content not explained in Example 2 is required, it can be considered as the content of Example 1.

[0091] Referring to FIGS. 2 and 3, a welding electrode inspection device (100) according to Embodiment 2 of the present invention may largely include an electronic pressure sensitive paper (110), a bracket (120), and a guide rail (130). The electronic pressure sensitive paper (110) may be configured to inspect the welding electrode (10, 20) by receiving pressure from the welding electrode (10, 20). The bracket (120) may be configured to have the electronic pressure sensitive paper (110) fixedly installed. In addition, the guide rail (130) may be configured to guide the bracket (120) on which the electronic pressure sensitive paper (110) is installed to move in a curved shape.

[0092] The electronic pressure sensor (110) may include a plurality of measurement nodes (111). The measurement nodes (111) may be the minimum unit configurations that perform measurements, as illustrated in FIG. 4. The plurality of measurement nodes (111) may be arranged in a grid pattern to perform measurements. The measurements taken by each measurement node (111) may be combined to obtain an overall result value.

[0093] For this purpose, the width (d) of the measurement node (111) may have a value of 0.01 mm to 0.1 mm. And the pitch (p) between the measurement nodes (111) may have a value of 0.01 mm to 0.2 mm. Here, the pitch (p) between the measurement nodes (111) and the measurement nodes (111) may mean the gap between the measurement nodes (111) and the measurement nodes (111). The smaller the width (d) and pitch (p) of the measurement nodes (111), the more precise the inspection results can be obtained.

[0094] FIG. 4 is a drawing showing an electronic pressure sensor (110) measuring the state of a welding rod (10, 20) in a welding rod inspection device (100) according to an embodiment of the present invention. (a) is a drawing showing a normal state (no wear), and (b) is a drawing showing an abnormal state (with wear).

[0095] Referring to Fig. 4, in the drawing (a), the pressured portion appears as a wide circle on the plan view, so it can be determined that the entire surface of the welding rod (10, 20) is in horizontal contact with the electronic pressure-sensitive paper (110) and pressure is applied. In addition, since the difference between the part with the highest pressure in the center and the part with the lowest pressure on the outer edge is not large, it can be determined that the pressure distribution is even (refer to the pressure contour line shown on the plan view).

[0096] In contrast, in the drawing (b), the pressured portion appears as a narrow oval on the plan view, so it can be determined that only a local portion, not the entire surface of the welding rod (10, 20), contacted the electronic pressure-sensitive paper (110) and applied pressure. In addition, it can be determined that the pressure distribution is uneven (biased pressure distribution) because the difference between the part with the highest pressure in the center and the part with the lowest pressure on the outer edge is large (see the pressure contour line shown on the plan view).

[0097] And the bracket (120) may include a bracket body (121) and a fixing member (122). Here, the bracket body (121) may be configured to have an electronic pressure sensitive device (110) inserted therein. The bracket (120) may include an upper block (121-1) and a lower block (121-2), and the electronic pressure sensitive device (110) may be inserted into and installed in the upper block (121-1) and the lower block (121-2).

[0098] And the fixing member (122) is coupled to the bracket body (121) and may be configured to fixally install the electronic pressure sensitive paper (110). The fixing member (122) may penetrate the upper block (121-1) and pressurize the electronic pressure sensitive paper (110) and fix it so that it does not move forward or backward. For example, the fixing member (122) may be a screw member.

[0099] The guide rail (130) can guide the bracket (120) to move in a curved shape, more specifically, to move in a circular shape. Accordingly, the bracket (120) can move along the guide rail (130) to a 90 degree position (=3 o'clock position) (①), a 180 degree position (=6 o'clock position) (②), and a 270 degree position (=9 o'clock position) (③) based on the angle measurement reference point of the rotary welding equipment (1).

[0100] And a stopper (131) may be installed on the guide rail (130) to limit the movement of the bracket (120). The position where the bracket (120) is stopped by this stopper (131) may be the origin of the rotational movement of the bracket (120).

[0101]

[0102] Example 3 - Secondary battery manufacturing method

[0103] Example 3 of the present invention relates to a method for manufacturing a secondary battery.

[0104] We will omit as much of the common content as possible with Examples 1 and 2 and explain Example 3 focusing on the differences. In other words, it is self-evident that if content not explained in Example 3 is required, it can be considered as the content of Examples 1 and 2.

[0105] Embodiment 3 of the present invention includes a method for manufacturing a secondary battery, a welding process for a secondary battery can, and a welding rod inspection method for inspecting a welding rod used in the welding process for a secondary battery can.

[0106] Here, the welding process of the secondary battery can may be the welding process of the secondary battery can described in the description of Embodiment 1 above. That is, the welding process of the secondary battery can includes an initial waiting stage in which the welding rod is in a waiting state before the secondary battery can is put in for welding, a pre-welding waiting stage in which the can is put in and the welding rod is in a waiting state, a welding stage in which the welding rod pressurizes and welds the electrode tabs to be welded to the can, a post-welding waiting stage in which the welding rod returns to a waiting state again after the welding stage, and a transfer stage in which the can is moved to the next process.

[0107] And, the welding rod inspection method may be the welding rod inspection method according to the previously described embodiment 1. This is a welding rod inspection method for inspecting a welding rod used in the welding process of a secondary battery can, as described above.

[0108] And, Example 3 of the present invention is characterized in that the secondary battery manufacturing method performs the welding rod inspection method once every n times the welding process of the secondary battery can is performed. Here, n means a natural number greater than or equal to 2. For example, n can be a number such as 10, 100, 1000, or 10000. When the welding process of the secondary battery can is performed n times, the welding rod may be worn to some extent or a problem may have occurred, so by inspecting the welding rod using the welding rod inspection method once, it is possible to determine whether the welding rod is good or defective.

[0109] If a defect is determined through this process, an alarm such as a warning may be issued, and the welding rod may be replaced. After the electrode is replaced, the secondary battery can welding process may resume.

[0110]

[0111] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope equivalent to the technical idea of ​​the present invention and the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0112] [Explanation of symbols]

[0113] 1: Rotary welding equipment

[0114] 10: Upper welding rod

[0115] 20: Lower welding rod

[0116] 100: Welding rod inspection device

[0117] 110: Electronic pressure sensitive paper

[0118] 111: Measurement Node

[0119] 120: Bracket

[0120] 121: Bracket body

[0121] 122: Fixed member

[0122] 130: Guide rail

[0123] 131: Stopper

[0124] d: width of the measurement node

[0125] p: pitch (spacing of measurement nodes)

[0126] ①: 90 degree position (=3 o'clock position)

[0127] ②: 180 degree position (=6 o'clock position)

[0128] ③: 270 degree position (=9 o'clock position)

Claims

1. A welding rod inspection method for inspecting a welding rod used in a welding process of a secondary battery can, comprising: an initial waiting stage in which a welding rod is in a waiting state before a secondary battery can is put in for welding; a pre-welding waiting stage in which the can is put in and the welding rod is in a waiting state; a welding stage in which the welding rod pressurizes and welds the can and an electrode tab to be welded to the can; a post-welding waiting stage in which the welding rod returns to a waiting state again after the welding stage; and a transfer stage in which the can is moved to a next process. An electronic pressure sensitive paper insertion step for inserting an electronic pressure sensitive paper instead of the can in the above pre-welding waiting step; A pressurizing step in which the welding rod pressurizes the electronic pressure sensitive paper inserted instead of the can and the electrode tab in the welding step; An inspection step for inspecting at least one of the pressure and surface condition of the welding rod through the pressurization of the electronic pressure sensitive paper; and A welding electrode inspection method comprising a recovery step in which the electronic pressure sensitive paper is recovered in the above-described transfer step.

2. In claim 1, The welding process of the above secondary battery can is performed by a rotary welding equipment that rotates circularly. A welding electrode inspection method characterized in that the above electronic pressure sensor performs the necessary steps while moving in a curved shape along a curved guide rail.

3. In claim 2, Based on the angle measurement reference point of the above rotary welding equipment, the pre-welding standby step is performed at a position of 90 degrees (3 o'clock position), the welding step is performed at a position of 180 degrees (6 o'clock position), and the transfer step is performed at a position of 270 degrees (9 o'clock position). Accordingly, a welding rod inspection method characterized in that the electronic pressure-sensitive paper insertion step is performed at the 90 degree position, the pressurizing step is performed at the 180 degree position, and the recovery step is performed at the 270 degree position.

4. In claim 3, A method for inspecting a welding electrode, characterized in that the electronic pressure gauge moves along the curved guide rail to the 90 degree position (3 o'clock position), the 180 degree position (6 o'clock position), and the 270 degree position (9 o'clock position).

5. In claim 1, The above welding rod includes an upper welding rod and a lower welding rod, A welding electrode inspection method, characterized in that, in the pressurizing step, the electronic pressure sensor is pressurized from above and below by the upper welding electrode and the lower welding electrode.

6. In claim 1, A method for inspecting a welding rod, characterized in that the above welding is resistance welding or ultrasonic welding.

7. In claim 1, A method for inspecting a welding electrode, characterized in that the electronic pressure sensor includes a plurality of measuring nodes.

8. In claim 7, A method for inspecting a welding rod, characterized in that the above measuring node has a width of 0.01 mm to 0.1 mm.

9. In claim 7 or claim 8, A method for inspecting a welding rod, characterized in that the pitch between the above measuring nodes has a value of 0.01 mm to 0.2 mm.

10. In claim 7, The above inspection steps are: A measuring step for measuring the surface pressure state of an electronic pressure sensitive device; Area setting step for setting the pressure measurement range within the measured pressure distribution; A pressure calculation step for calculating a pressure value by adding up the pressure of multiple measurement nodes within a set area; and A method for inspecting a welding electrode, characterized in that it includes a judgment step of judging whether a pressure value produced within a set area satisfies a set standard pressure and judging pass or fail based on the result.

11. In claim 7, The above inspection steps are: A measuring step for measuring the surface pressure state of an electronic pressure sensitive device; Area setting step for setting the pressure measurement range within the measured pressure distribution; A pressurized shape analysis step for analyzing a pressurized shape formed by the electronic pressure sensor within the above range; and A method for inspecting a welding electrode, characterized in that it includes a judgment step of judging whether the above-mentioned pressurized shape satisfies a standard pressurized shape and judging pass or fail based on the result.

12. In claim 7, The above inspection steps are: A measuring step for measuring the surface pressure state of an electronic pressure sensitive device; Area setting step for setting the pressure measurement range within the measured pressure distribution; A pressure calculation step for calculating a pressure value by adding up the pressure of multiple measurement nodes within a set area; A pressurized shape analysis step for analyzing a pressurized shape formed by an electronic pressure sensor; and A method for inspecting a welding electrode, characterized in that it includes a judgment step of judging whether a pressure value calculated within a set area satisfies a set standard pressure and whether the pressure shape satisfies a standard pressure shape, and judging pass or fail based on the result.

13. In any one of claims 10 to 12, A method for inspecting a welding rod, characterized in that it further includes a facility alarm step for transmitting the pass / fail judgment data determined in the above judgment step to the facility to determine whether to stop or start the facility.

14. In claim 1, Prior to the pressurizing step, the welding step further includes a pre-pressurizing step in which the welding rod pressurizes the electronic pressure sensitive paper with a lower pressing force than the pressing force for welding, A method for inspecting a welding rod, characterized in that in the pressurizing step, the welding rod presses the electronic pressure sensitive paper with a pressurizing force for performing the welding in the welding step.

15. A welding rod inspection device for inspecting a welding rod used in a welding process of a secondary battery can, comprising: an initial waiting step in which a welding rod is in a waiting state before a secondary battery can is put in for welding; a pre-welding waiting step in which the can is put in and the welding rod is in a waiting state; a welding step in which the welding rod pressurizes and welds the can and an electrode tab to be welded to the can; a post-welding waiting step in which the welding rod returns to a waiting state again after the welding step; and a transfer step in which the can is moved to a next process. An electronic pressure sensor for inspecting the welding electrode by receiving pressure from the welding electrode; A bracket on which the above electronic pressure sensor is fixedly installed; and A welding electrode inspection device including a curved guide rail for guiding the bracket on which the electronic pressure sensor is installed to move in a curved shape.

16. In claim 15, The welding process of the above secondary battery can is performed by a rotary welding equipment that rotates circularly. Based on the angle measurement reference point of the above rotary welding equipment, A welding electrode inspection device characterized in that the bracket moves along the curved guide rail to positions of 90 degrees, 180 degrees, and 270 degrees.

17. In claim 15, The above brackets are, A bracket body into which the above electronic pressure sensor is inserted; and A welding rod inspection device characterized by comprising a fixing member coupled to the bracket body and for fixing and installing the electronic pressure sensor.

18. In claim 15, A welding rod inspection device characterized in that a stopper is installed on the above guide rail to limit the movement of the bracket.

19. A welding process for a secondary battery can, comprising: an initial standby step in which a welding rod is in a standby state before a secondary battery can is put in for welding; a pre-welding standby step in which the can is put in and the welding rod is in a standby state; a welding step in which the welding rod pressurizes and welds the can and an electrode tab to be welded to the can; a post-welding standby step in which the welding rod returns to a standby state again after the welding step; and a transfer step in which the can is transferred to a next process; and A welding rod inspection method according to claim 1 for inspecting a welding rod used in a welding process of the above secondary battery can, A method for manufacturing a secondary battery, characterized in that the above welding rod inspection method is performed once every n times the welding process of the secondary battery can is performed. (where n is a natural number greater than or equal to 2)

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