Heat treatment apparatus for notch part of vent cap of cylindrical secondary battery

Abstract

The heat treatment apparatus for a notch part of a vent cap of a cylindrical secondary battery according to an embodiment of the present invention relates to a heat treatment apparatus for a notch part of a vent cap of a cylindrical secondary battery in which the notch part is formed by press forming. The heat treatment device for a notch part of a vent cap of a cylindrical secondary battery includes: a transfer module for transporting the vent cap of the cylindrical secondary battery in one direction; and a laser heat treatment module for performing local heat treatment on the notch part after receiving the vent cap of the cylindrical secondary battery from the transfer module.

Description

Heat treatment device for the notch of a cylindrical secondary battery vent cap

[0001] The present invention relates to a heat treatment device for a notch portion of a cylindrical secondary battery vent cap, and more particularly, to a heat treatment device for performing local heat treatment of a notch portion after forming a cylindrical secondary battery vent cap.

[0002]

[0003] Secondary batteries capable of repeated charging and discharging can be classified into pouch-type, square-type, and cylindrical types depending on their structure. Among these, the battery can forming the body of a cylindrical secondary battery and the top cap attached to the top of the battery can are generally made of metal.

[0004] The top cap of a cylindrical secondary battery is manufactured by forming the basic shape through a pressing process, and then going through a plating process such as nickel to prevent corrosion, and an additional anti-corrosion process to prevent corrosion due to micro-cracks such as pin holes.

[0005] Meanwhile, in the case of secondary batteries, the internal temperature may rise rapidly due to short circuits or overcharging, and such rapid rise in temperature may cause the secondary battery to catch fire or explode.

[0006] In order to prevent ignition and explosion of the secondary battery, according to the prior art, the top cap is formed as a vent cap by welding a CID (current interrupt device) and a vent to provide the (+) terminal role and safety, and when the pressure inside the battery cell increases, the welding part of the CID is short-circuited first to cut off the current, and under higher pressure, the vent notch part is eventually broken to discharge the gas inside the secondary battery to the outside and lower the pressure.

[0007] Additionally, a top cap configuration using only vents, excluding the CID configuration, is also possible.

[0008] However, in the case of vent caps using this welding method, the manufacturing time is long and it is difficult to ensure uniform quality, so there are cases where the vent cap does not break properly even under high pressure inside the battery cell, and thus the safety of cylindrical secondary batteries is not guaranteed when the temperature rises rapidly.

[0009] In order to overcome the problems of the above-described welding method vent cap, a technology has been proposed in which a concentric notch (11) is formed in the vent cap (10) at a preset distance from the center, as shown in FIGS. 1 to 3, so that when the pressure inside the battery cell increases, the notch (11) breaks, cutting off the current and releasing the gas to lower the pressure.

[0010] In the case of this notch-type vent cap (10), a notch (11) is formed through press forming processing, and the notch (11) may be hardened due to plastic deformation, which may cause non-breakage at the target pressure.

[0011] In order to solve this problem, heat treatment (annealing) is performed on the area to soften the notch (11). However, when a vent cap formed of stainless steel is heat treated, Cr2O3 is generated due to surface oxidation during the heat treatment process, which causes yellowing (discoloration), and there is a problem in that surface hardening is strengthened.

[0012]

[0013] The notch heat treatment device of a cylindrical secondary battery vent cap according to one embodiment of the present invention aims to solve the above-described problems by achieving the following solutions.

[0014] The present invention provides a heat treatment device for a notch portion of a cylindrical secondary battery vent cap that can prevent yellowing of the vent cap due to heat treatment and simultaneously prevent rupture at a target pressure.

[0015] The problems solved by the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary knowledge in the relevant technical field from the description below.

[0016]

[0017] A heat treatment device for a notch portion of a cylindrical secondary battery vent cap according to one embodiment of the present invention relates to a heat treatment device for a notch portion of a cylindrical secondary battery vent cap in which a notch portion is formed by press molding, and includes: a transport module for transporting the cylindrical secondary battery vent cap in one direction; and a laser heat treatment module for receiving the cylindrical secondary battery vent cap from the transport module and then performing local heat treatment on the notch portion.

[0018] The laser heat treatment module preferably includes an enclosure having an inlet and an outlet for introducing and discharging a cylindrical secondary battery vent cap before and after heat treatment, respectively; a laser irradiation unit for irradiating a laser to a notch portion of the cylindrical secondary battery vent cap; and a gas injection unit for injecting at least one of an inert gas and a hydrogen mixed gas into the enclosure.

[0019] The laser irradiation unit is placed on the upper part of the enclosure, and a penetration part is formed in an area corresponding to the laser irradiation unit on the upper surface of the enclosure, and it is preferable that a quartz plate is placed in the penetration part.

[0020] It is preferable to further include a control module for controlling the laser heat treatment module; and an inspection module for performing inspection after receiving a cylindrical secondary battery vent cap whose notch has undergone heat treatment by the transport module.

[0021] It is preferable that the above inspection module include an appearance inspection unit for checking whether the notch portion has discolored; and a breaking pressure inspection unit for checking the breaking pressure of the notch portion.

[0022] It is preferable that the control module includes a transport module control unit that controls the operation of the transport module; a laser output control unit that controls the output of the laser irradiation unit; a gas injection amount control unit that controls the amount of gas injected by the gas injection unit; a storage unit that collects and stores big data on the results of the inspection module according to the laser output of the laser irradiation unit and the amount of gas injected by the gas injection unit; a learning unit that performs machine learning based on the data stored in the storage unit; and an optimal condition calculation unit that generates an optimal output condition of the laser irradiated to the notch portion and an optimal gas injection amount based on an algorithm determined by the learning unit.

[0023] The above algorithm is a deep learning algorithm in which a correlation between input factors and output factors is defined, and the input factor is preferably at least one of the output power of the laser irradiated from the laser irradiation unit, the output time of the laser, the irradiation path of the laser, the type of gas injected by the gas injection unit, the amount of gas injected, and the injection cycle of the gas, and the output factor is preferably at least one of the degree of discoloration of the notch portion and the breaking pressure of the notch portion.

[0024] It is desirable to install gas curtains at the above inlet and outlet.

[0025]

[0026] A heat treatment device for a notch portion of a cylindrical secondary battery vent cap according to one embodiment of the present invention is configured to perform heat treatment only on the notch portion of the vent cap, which is a locally hardened portion, using a laser, thereby reducing carbon emissions and reducing process costs.

[0027] In addition, the heat treatment process of the notch part can be established on the assembly line, which can be expected to result in easier management and operation.

[0028] The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary knowledge in the relevant technical field from the description below.

[0029]

[0030] Figure 1 is a front view of a cylindrical secondary battery vent cap.

[0031] Figure 2 is a cross-sectional view of AA` of Figure 1.

[0032] Figure 3 is a detailed view of the “X” portion of Figure 2.

[0033] Figure 4 is a graph showing the breaking pressure of a notch according to laser output when a laser is locally irradiated on the notch.

[0034] Figure 5 is a schematic diagram of a notch heat treatment device of a cylindrical secondary battery vent cap according to one embodiment of the present invention.

[0035] Figure 6 is a schematic diagram of a notch heat treatment device for a cylindrical secondary battery vent cap according to another embodiment of the present invention.

[0036] Figure 7 is a block diagram showing the detailed configuration of a control module among the notch heat treatment devices of a cylindrical secondary battery vent cap according to the present invention.

[0037] Figure 8 is a block diagram showing the detailed configuration of an inspection module among the notch heat treatment devices of a cylindrical secondary battery vent cap according to the present invention.

[0038]

[0039] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components will be given the same reference numbers and redundant descriptions thereof will be omitted.

[0040] Furthermore, when describing the present invention, detailed descriptions of related known technologies will be omitted if they are deemed to obscure the gist of the present invention. Furthermore, it should be noted that the attached drawings are intended solely to facilitate understanding of the spirit of the present invention and should not be construed as limiting the spirit of the present invention.

[0041]

[0042] Hereinafter, a notch heat treatment device of a cylindrical secondary battery vent cap according to the present invention will be described with reference to FIGS. 1 to 9.

[0043] The present invention relates to a heat treatment device for a notch portion (11) of a cylindrical secondary battery vent cap (10) manufactured by forming a notch portion by press forming on a stainless steel plate, and the cylindrical secondary battery vent cap (10) is formed in a circular shape to be placed on the upper portion of a cylindrical battery can as illustrated in FIGS. 1 to 3.

[0044] The secondary battery vent cap (10) is formed with concentric notches (11) spaced apart from the center by a preset distance, so that when the pressure inside the battery cell increases, the notches are ruptured by the pressure, thereby preventing an explosion of the battery cell by releasing the gas inside the secondary battery to the outside.

[0045] Meanwhile, the notch portion (11) is formed by press forming processing, and as a result, the notch portion (11) is hardened and may not break at the target pressure. Taking this into consideration, it is necessary to soften the notch portion (11) through heat treatment.

[0046] To this end, the notch heat treatment device of the cylindrical secondary battery vent cap according to the present invention is configured to perform heat treatment only on the notch portion (11), which is a locally hardened portion, using a laser.

[0047] Referring to Figure 4, if we check the change in fracture pressure according to the laser power or heat treatment temperature, the fracture pressure is 25 kgf / cm before laser heat treatment. 2 However, it was confirmed that the breaking pressure gradually decreased when heat treatment was performed on the notch portion (11) using a laser.

[0048] However, softening of the notch portion (11) is achieved through heat treatment in a temperature range of approximately 720°C or lower, but when this is exceeded, martensite is generated and it has been confirmed that the strength of the notch portion (11) actually increases. Therefore, an optimal laser output setting is required.

[0049] In order to implement the above-described function, the notch heat treatment device of the cylindrical secondary battery vent cap according to the present invention is configured to include a transport module (100), a laser heat treatment module (200), and a control module (300) as shown in FIGS. 5 to 7.

[0050] The transport module (100) performs the function of transporting the cylindrical secondary battery vent cap (10) in one direction, and it is preferable that a plurality of fixing portions (110) be formed on the transport module (100) so that the secondary battery vent cap (10) can be fixedly installed.

[0051] The laser heat treatment module (200) is configured to perform local heat treatment on the notch portion (11) after receiving the cylindrical secondary battery vent cap (10) from the transfer module (100). As shown in FIG. 5, the laser heat treatment module (200) may be configured to include an enclosure (210), a laser irradiation unit (220), a gas injection unit (230), and a quartz plate (240).

[0052] The enclosure (210) is configured to isolate the heat treatment area where laser heat treatment is performed from other areas, and an inlet (211) and an outlet (212) are formed on one side and the other side, so that a cylindrical secondary battery vent cap (10) before heat treatment is introduced into the heat treatment area through the inlet (211), and then, when laser heat treatment is completed, moves out of the heat treatment area through the outlet (212).

[0053] The laser irradiation unit (220) performs the function of irradiating a laser (20) to a notch portion (11) of a cylindrical secondary battery vent cap (10), and softens the notch portion (11) by the irradiated laser (20).

[0054] Meanwhile, in the process of performing local heat treatment on the notch portion (11) by the laser irradiation unit (220), Cr2O3 is generated due to surface oxidation of the notch portion (11), which causes discoloration due to yellowing to appear on the notch portion (11), and further, there is a problem that surface hardening is strengthened.

[0055] To solve the above-mentioned problem, a method of suppressing the production of Cr2O3 by creating a reducing atmosphere through hydrogen heat treatment can be considered, but this requires thorough management due to the explosive nature of hydrogen, and has the disadvantage of high production costs due to high-temperature furnace operation.

[0056] Therefore, in order to suppress the generation of Cr2O3 by laser heat treatment, it is necessary to use an inert gas such as Ar gas and a mixed gas of hydrogen, and stability can be secured, especially when hydrogen is excluded.

[0057] That is, the gas injection unit (230) performs the function of injecting Ar, N, Ar / H2, N / H2 inert gas and hydrogen mixed gas into the enclosure (210) to suppress the production of the above-described Cr2O3.

[0058] Meanwhile, the laser irradiation unit (220) is placed on the upper part of the enclosure (210) as shown in FIGS. 4 and 5, and a penetration portion (213) is formed in an area corresponding to the laser irradiation unit (220) on the upper surface of the enclosure (210) so that the laser (20) output from the laser irradiation unit (220) can be irradiated to the upper surface of the cylindrical secondary battery vent cap (10).

[0059] At this time, in order to suppress the generation of Cr2O3 by laser heat treatment, considering that it is necessary to prevent the gas injected into the enclosure (210) from leaking to the outside through the penetration portion (213) as much as possible, it is desirable to minimize the outflow of gas through the penetration portion (213) by placing a quartz plate (240) in the penetration portion (213).

[0060] In addition, it is desirable to minimize the inlet (211) and outlet (212) of the enclosure (210) by forming them to a minimum extent that movement of the secondary battery vent cap (10) by the transport module (100) is possible, thereby minimizing the leakage of gas injected into the enclosure (210) to the outside through the inlet (211) and outlet (212).

[0061] Furthermore, as illustrated in FIG. 6, the enclosure (210) is configured to further include a gas injection unit (250) that injects gas toward the inlet (211) and the outlet (212), and a gas curtain (30) can be formed on the inlet (211) and the outlet (212) sides by the gas injected from the gas injection unit (250), thereby minimizing the gas inside the enclosure (210) from leaking to the outside through the inlet (211) or the outlet (212).

[0062] At this time, it is preferable that the gas injected from the gas injection unit (250) is at least one of Ar, N, Ar / H2, N / H2 inert gas and hydrogen mixed gas injected by the gas injection unit (230).

[0063] The control module (300) performs a function of controlling the laser heat treatment module (200), and the inspection module (400) is configured to perform an inspection after receiving a cylindrical secondary battery vent cap (10) in which heat treatment of the notch portion (11) has been completed by the transfer module (100).

[0064] The inspection module (400) may be a configuration included in a notch heat treatment device of a cylindrical secondary battery vent cap according to one embodiment of the present invention, but may also be a separate, independent configuration separated from the notch heat treatment device.

[0065] This inspection module (400) may include an appearance inspection unit (410) and a fracture pressure inspection unit (420) as shown in FIG. 8.

[0066] The appearance inspection unit (410) is configured to acquire an image of the notch portion (11) using a camera or the like and to check the degree of discoloration of the notch portion (11) by utilizing the acquired image, and the breaking pressure inspection unit (420) performs the function of checking the breaking pressure of the notch portion (11) that has completed heat treatment. It is preferable that this breaking pressure be performed by sampling inspection rather than full inspection.

[0067] The control module (300) may be configured to include a transport module control unit (310), a laser output control unit (320), and a gas injection amount control unit (330) as illustrated in FIG. 7.

[0068] The transport module control unit (310) performs a function of controlling the operation of the transport module (100), the laser output control unit (320) performs a function of controlling the output of the laser irradiation unit (220), and the gas injection amount control unit (330) performs a function of controlling the amount of gas injected by the gas injection unit (230).

[0069] In particular, the notch heat treatment device of the cylindrical secondary battery vent cap according to the present invention can be configured to utilize the acquired big data to calculate an optimal process setting value for maintaining an appropriate breaking pressure of the notch portion (11) while minimizing discoloration of the notch portion (11), and for this purpose, the control module (300) is configured to further include a storage unit (340), a learning unit (350), and an optimal condition calculation unit (360).

[0070] The storage unit (340) performs the function of collecting and storing big data on the results of the inspection module (400) according to the laser output of the laser irradiation unit (220) and the amount of gas injected by the gas injection unit (230).

[0071] The learning unit (350) performs machine learning based on data stored in the storage unit (340), and the optimal condition generation unit (360) performs a function of generating the optimal output conditions of the laser (20) irradiated on the notch (11) and the optimal gas injection amount injected into the enclosure (210) based on the algorithm determined by the learning unit (350).

[0072] In particular, the algorithm determined in the learning unit (350) may be a deep learning algorithm in which the correlation between input factors and output factors is defined. In this case, the input factor is preferably at least one of the output power of the laser (20) irradiated by the laser irradiation unit (220), the output time of the laser (20), the irradiation path of the laser (20), the type of gas injected by the gas injection unit (230), the amount of gas injected, the cycle of gas injection, and the concentration of gas inside the enclosure (210), and the output factor is preferably at least one of the degree of discoloration of the notch portion (11) and the breaking pressure of the notch portion (11).

[0073] The laser output control unit (320) and the gas injection amount control unit (330) receive the optimal output conditions and optimal gas injection amount of the laser generated from the optimal condition calculation unit (360) and control the laser irradiation unit (220) and the gas injection unit (230), respectively, thereby enabling the provision of a cylindrical secondary battery vent cap with optimal quality.

[0074] In addition, the above-described gas injection unit (250) can also be controlled based on the results of the optimal condition calculation unit (360), and specifically, when the concentration inside the enclosure (210) is determined to be somewhat high, it may be possible to allow the outflow of gas through the inlet (211) or outlet (212) by stopping the formation of the gas curtain (30) by the gas injection unit (250).

[0075] Meanwhile, although the technical features of the present invention have been described with reference to a heat treatment device for a notch portion of a cylindrical secondary battery vent cap, the present invention is not limited thereto and may be applied to a plate-shaped member of a metal material having a fracture portion formed therein, such as a tin can, a beverage can, or a beer can.

[0076]

[0077] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

Claims

1. In a notch heat treatment device of a cylindrical secondary battery vent cap in which a notch is formed by press forming, A transport module for transporting the cylindrical secondary battery vent cap in one direction; and A laser heat treatment module that performs local heat treatment on the notch portion after receiving the cylindrical secondary battery vent cap from the transport module; A heat treatment device for a notch portion of a cylindrical secondary battery vent cap, characterized by including a .

2. In claim 1, the laser heat treatment module, An enclosure having an inlet and an outlet respectively formed for introducing and discharging a cylindrical secondary battery vent cap before and after heat treatment; A laser irradiation unit that irradiates a laser to the notch portion of the cylindrical secondary battery vent cap; and A gas injection unit for injecting at least one of an inert gas and a hydrogen mixed gas into the enclosure; A heat treatment device for a notch portion of a cylindrical secondary battery vent cap, characterized by including a .

3. In claim 2, The above laser irradiation unit is placed on the upper part of the enclosure, and a penetration part is formed in an area of ​​the upper surface of the enclosure corresponding to the laser irradiation unit. A notch heat treatment device for a cylindrical secondary battery vent cap, characterized in that a quartz plate is arranged in the above-mentioned penetration portion.

4. In claim 2, A control module for controlling the above laser heat treatment module; and An inspection module that performs inspection after receiving a cylindrical secondary battery vent cap whose notch has undergone heat treatment by the above-mentioned transfer module; A heat treatment device for a notch portion of a cylindrical secondary battery vent cap, characterized in that it further includes a.

5. In claim 4, the control module, A transport module control unit that controls the operation of the above transport module; A laser output control unit that controls the output of the above laser irradiation unit; A gas injection amount control unit that controls the amount of gas injected by the above gas injection unit; A storage unit that collects and stores big data on the results of the inspection module according to the laser output of the laser irradiation unit and the amount of gas injected by the gas injection unit; A learning unit that performs machine learning based on data stored in the above storage unit; and An optimal condition calculation unit that generates optimal output conditions and optimal gas injection amount of the laser irradiated to the notch portion based on the algorithm determined by the learning unit; A heat treatment device for a notch portion of a cylindrical secondary battery vent cap, characterized by including a .

6. In claim 5, The above algorithm is a deep learning algorithm in which the correlation between input and output factors is defined. The above input factor is at least one of the output power of the laser irradiated from the laser irradiation unit, the output time of the laser, the irradiation path of the laser, the type of gas injected by the gas injection unit, the amount of gas injected, and the injection cycle of the gas. A notch heat treatment device for a cylindrical secondary battery vent cap, wherein the output factor is at least one of the degree of discoloration of the notch and the breaking pressure of the notch.

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