Multi-roll system, battery can forming device and forming method

Abstract

This specification relates to a multi-roller system comprising two or more pairs of rollers, a battery can forming apparatus, and a forming method. The two or more pairs of rollers rotate around independent axes of rotation, each controlling its height variation. The two or more pairs of rollers have different cross-sectional shapes, and each of the two or more pairs of rollers applies pressure close to the battery can at equal intervals.

Description

Technical Field

[0001] This application claims the benefit of Korean Patent Application No. 10-2021-0030312, filed with the Korean Patent Office on March 8, 2021, all of which is disclosed in the documents of that Korean patent application and is included in this specification.

[0002] This invention relates to a multi-roller system, a battery can forming apparatus, and a forming method. Background Technology

[0003] Compared to previous models (1865 / 2170), the cylindrical secondary battery models developed in recent years have battery canisters with larger inner diameters and are constructed from thicker materials. Therefore, molding such cylindrical secondary battery canisters requires a greater load and longer processing time.

[0004] Cylindrical rechargeable battery cans are typically formed sequentially through various processes such as CBD (Cylindrical beading), CCR1-2-3 (Cylindrical crimping 1-2-3), and CSZ (Cylindrical sizing), which requires a considerable amount of processing time. Therefore, to achieve the target production volume for battery cans, multiple forming machines must be connected in parallel.

[0005] Currently, multiple molding machines are connected in parallel to mold battery cans, aiming to produce the maximum number of cans within a specified time. However, this method requires time for equipment transfer compared to parallel setups. Furthermore, the movement of the equipment necessitates the re-fixation of the battery cans, which can introduce deviations from the set values. This can also lead to variations in molding quality. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] To address the aforementioned problems, one object of the present invention is to provide a multi-roller system, a battery can forming apparatus, and a forming method according to an embodiment of the present invention, thereby reducing the time required for equipment transfer and preventing deviations in set values ​​that occur during re-fixation as the equipment is transferred.

[0008] However, the problems to be solved by the present invention are not limited to those described above. Those skilled in the art can clearly understand other problems not mentioned in this specification from the following description of the invention.

[0009] Methods for solving problems

[0010] To achieve the above objectives, the present invention provides a multi-roller system, a battery can forming apparatus, and a forming method for the following sides.

[0011] According to one aspect of the present invention, a multi-roller system comprising two or more pairs of rollers is provided, wherein,

[0012] The two or more pairs of rollers mentioned above rotate with each other as a reference, each controlling the height change.

[0013] At least one cross-section of the two or more pairs of rollers mentioned above has a different shape.

[0014] The spacing between each pair of rollers and the battery canister is different.

[0015] According to one aspect of the present invention, a battery can forming apparatus is provided, comprising:

[0016] The fixing unit, which fixes the battery canister; and

[0017] The aforementioned multi-roller system.

[0018] According to one aspect of the present invention, a method for molding a battery can is provided, comprising:

[0019] The first step is to set an electrode assembly in the battery can and inject electrolyte, and then form it with a rolled edge portion, and stack a pad and a cover assembly on the rolled edge portion. The electrode assembly has a structure formed by sequentially stacking and rolling a first electrode, a separation membrane and a second electrode. The rolled edge portion is formed at the side end of the battery can adjacent to the open portion and is pressed inward.

[0020] The second step is to secure the aforementioned battery container;

[0021] The third step is to apply pressure to the end of the open portion located above the rolled edge, forming an inclined section in which the end of the open portion of the battery can is inclined toward the central axis of the battery can.

[0022] The fourth step involves applying pressure to the end of the open portion of the battery can with the aforementioned inclined section to form a sealed section parallel to the side of the battery can; and

[0023] The fifth step involves applying pressure to the end of the open portion of the battery can, which has the aforementioned inclined and sealed sections, to form a flat section parallel to the lower surface of the battery can.

[0024] At least two of the above-mentioned steps three through five utilize the above-mentioned multi-roller system.

[0025] Invention Effects

[0026] According to one aspect of the present invention, it is possible to unify the conventional battery can molding processes that are arranged in parallel.

[0027] Alternatively, according to one aspect of the invention, pressure is applied to various pressurized parts of the battery canister, which is advantageous from the perspective of force transmission, thereby minimizing the load applied to the rollers respectively.

[0028] Alternatively, according to one aspect of the invention, composite molding processes can be performed effectively by unifying the processes.

[0029] Alternatively, according to one aspect of the invention, through continuous operation, molding can be performed rapidly with relatively little force, thus significantly reducing process time.

[0030] Alternatively, according to one aspect of the invention, equipment transfer is unnecessary, thus reducing the time required for transfer. Furthermore, deviations in set values ​​caused by re-fixing the equipment due to transfer can be minimized. Therefore, it is possible to achieve both increased speed and minimized deviations between processes.

[0031] Alternatively, according to one aspect of the invention, it is possible to improve the molding quality of the battery can.

[0032] However, the effects obtained by the present invention are not limited to those described above, and those skilled in the art can clearly understand other technical effects not mentioned in this specification from the following description of the invention. Attached Figure Description

[0033] Figure 1 A three-dimensional view of a conventional roller system is shown.

[0034] Figure 2 A perspective view of a multi-roller system according to an embodiment of the present invention is shown.

[0035] Figure 3 The front view shows the inclined section formed by the A' roller.

[0036] Figure 4 A front view showing the sealing zone formed by the B' roller.

[0037] Figure 5 The front view shows the flat section formed by the C' roller.

[0038] (Symbol Explanation)

[0039] 1: Battery can

[0040] 2: Fixed Unit

[0041] 3: Cylindrical secondary battery

[0042] 10: (The end of the open section of the battery can)

[0043] 11: Pad

[0044] 12: Side of the battery can

[0045] 13: Cover component

[0046] 14: Inclined Range

[0047] 15: Sealed area

[0048] 16: Flat area

[0049] 100: Rolled edge

[0050] 200: Crimping part

[0051] A: First roller

[0052] B: Second roller

[0053] C: Third roller

[0054] A': Cross-section of the first roller

[0055] B': Cross-section of the second roller

[0056] C': Cross-section of the third roller Detailed Implementation

[0057] This invention can be modified in various ways, including various embodiments, but specific embodiments are illustrated in the accompanying drawings, and detailed description is based on these drawings. However, this is not intended to limit the invention to a specific embodiment; the invention includes all modifications, equivalents, or substitutions that fall within the technical concept and scope of the invention.

[0058] In this specification, terms such as "first" and "second" are used to describe various constituent elements, but the constituent elements are not limited to these terms. These terms are only used to distinguish one constituent element from others. For example, without departing from the scope of the invention, a first constituent element may be named a second constituent element, and similarly, a second constituent element may be named a first constituent element.

[0059] In this specification, the term "and / or" includes a combination of multiple related items or a portion of multiple related items.

[0060] In this specification, when a constituent element is described as singular, it includes multiple elements unless otherwise defined in this specification.

[0061] In this specification, the terms "including" and "possessing" are used to indicate the presence of features, numbers, steps, actions, processes, constituent elements, components, or combinations thereof as described in this specification, unless otherwise expressly stated in this specification, and do not exclude other features, numbers, etc.

[0062] Unless otherwise defined, all terms used in this specification, including technical or scientific terms, have the same meaning as would be understood by one of ordinary skill in the art in general.

[0063] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the prior art and the present invention will be described in detail.

[0064] Figure 1 This is a perspective view of a conventional roller system, showing a pair of first rollers A that press (or shape) the end of the open portion of the battery can 1. Here, the first rollers are used only for one process, for example, a first pressing process. For subsequent processes, the battery can, pressurized by the first rollers, needs to be transferred to another roller system. For example, a second roller is provided in the other roller system. Here, process deviations occur due to this transfer.

[0065] According to one embodiment of the present invention, a multi-roller system comprising two or more pairs of rollers is provided.

[0066] The two or more pairs of rollers mentioned above rotate with each other as a reference, and each controls the height change.

[0067] At least one cross-section of the two or more pairs of rollers mentioned above has a different shape.

[0068] The spacing between each pair of rollers and the battery canister is different.

[0069] Specifically, refer to Figure 2 The device comprises two or more pairs of rollers, such as a first roller A, a second roller B, and a third roller C, and includes a fixing unit 2 for fixing the battery can 1. These first to third rollers (A to C) rotate relative to independent or different axes of rotation, controlling the height variation accordingly. Furthermore, at least one cross-section of each of the aforementioned two or more pairs of rollers has a different shape. Here, "at least one cross-section of the roller has a different shape" means that the shape of the cross-section differs depending on the region near the battery can or when cut along the width direction of the roller.

[0070] In addition, the first to third rollers are pressurized by being close to the battery tank 1 with a time difference.

[0071] In addition, the pressure applied to the battery tank 1 in the first to third rollers may be the same or different from each other.

[0072] According to the above embodiment, by fixing the battery can once and ensuring that the intervals between the first to third pairs of rollers and the battery can are different, a process is performed first by moving the roller closest to the battery can, and then subsequent processes are performed sequentially. Therefore, unlike conventional technology, it is unnecessary to transfer the battery can, which has been pressurized by the first roller, to another roller system. This prevents process deviations caused by transfer.

[0073] According to one embodiment of the present invention, a multi-roller system is provided, wherein the two or more pairs of rolls include at least two pairs of rolls selected from the following:

[0074] A pair of first rollers apply pressure to the end of the open portion of the battery can to form an inclined section in which the end of the open portion of the battery can is inclined toward the central axis of the battery can;

[0075] A pair of second rollers apply pressure to the end of the open portion of the battery can, where the aforementioned inclined section is formed, to form a sealed section perpendicular to the side portion of the battery can; and

[0076] A pair of third rollers apply pressure to the sides of the open portion of the battery can, which has the aforementioned inclined and sealed sections, to form a flat section parallel to the lower surface of the battery can.

[0077] Specifically, refer to Figure 2 and Figure 3 The illustration shows that in a cylindrical secondary battery 3, the end 10 of the open portion of the battery can 1 passes through the first roller A (in... Figure 3 The diagram shows the inclined section 14 of the first roller (section A') being pressed and tilted towards the central axis of the battery can. Depending on the situation, the pad 11 is also tilted towards the central axis of the battery can via the first roller A.

[0078] Additionally, refer to Figure 2 and Figure 4 The end 10 of the open portion of the battery can with the inclined section 14 is shown passing through the second roller B (in Figure 4 The diagram shows the sealing section 15 of the second roller (section B') being pressurized and perpendicular to the side 12 of the battery can. This sealing section 15 serves to seal the battery can 1 by the subsequent passage of the third roller.

[0079] Additionally, refer to Figure 2 and Figure 5 The battery can, which has an inclined section 14 and a sealed section 15, passes between the rolled edge 100 and the open end 10 via a third roller C (in Figure 5 The diagram shows that the cross section C' of the third roller is pressed to form a flat section 16. As a result, a pressing part 200 is formed.

[0080] The process of forming the inclined section 14, the sealed section 15, and the flat section 16 described above is called the pressing process, which is the process of injecting electrolyte into the battery can, attaching the upper end cap, and sealing it. Furthermore, the cross-sectional shapes of the first to third rollers are different. Additionally, those skilled in the art can change the pressure applied to the first to third rollers, the pressing position, the pressing area, etc., as needed. Furthermore, those skilled in the art can control the height variation, rotation direction, rpm, and moving speed of the first to third rollers to achieve the desired pressure forming (e.g., the pressing process).

[0081] The cylindrical secondary battery 3 includes a battery canister 1, a gel roll type electrode assembly (a structure formed by stacking and rolling a first electrode, a separation membrane, and a second electrode) housed inside the battery canister 1 (not shown), a rolled edge portion 100 for mounting a cover assembly 13 attached to the upper part of the battery canister 1, and a crimping portion 200 for sealing the battery.

[0082] Here, the cover assembly 13 comprises a structure consisting of an upper cover forming the cathode terminal, a PTC element (Positive Temperature Coefficient element) that greatly increases the battery resistance and blocks current when the temperature inside the battery rises, a safety vent that blocks current and / or releases gas when the pressure inside the battery rises, an insulating component that electrically separates the safety vent from the cover plate in a certain portion, and a cover plate connected to the cathode tab, stacked in sequence. Furthermore, the upper end of the battery can 1 is crimped with the pad 11 installed, thereby mounting it onto the crimped portion 100 pressed inwards.

[0083] The multi-roller system described above includes at least two pairs of rollers from the first roller A to the third roller C.

[0084] The pressing process described above, performed by the first roller A to the third roller C, specifically consists of 1 to 3 steps, and the pressing process is performed sequentially by the first to the third rollers.

[0085] Additionally, refer to Figures 3 to 5 The cross-sections of the first to third rollers are formed into different shapes according to the target molding, and their heights are controlled separately. The rotation axes are also independent.

[0086] According to one embodiment of the present invention, a multi-roller system is provided, wherein, with the central axis of the battery can as a reference, the inclined interval of the end of the open portion of the battery can forms an angle greater than 0 degrees and less than 90 degrees.

[0087] According to the additional embodiment, with the central axis of the battery can as a reference, the inclined range of the end of the open portion of the battery can forms an angle greater than 0 degrees, greater than 10 degrees, greater than 20 degrees, greater than 30 degrees, or greater than 40 degrees.

[0088] According to the additional embodiment, with the central axis of the battery can as a reference, the inclined range of the end of the open portion of the battery can forms an angle of less than 90 degrees, less than 80 degrees, less than 70 degrees, less than 60 degrees, or less than 50 degrees.

[0089] Specifically, refer to Figure 3 With the central axis of the battery can as a reference, the inclined section 14 of the end 10 of the open portion of the battery can 1 forms an angle of approximately 30 degrees.

[0090] According to one embodiment of the present invention, a multi-roller system is provided, wherein, based on the diameter of the aforementioned battery can, the length of the aforementioned flat section is more than 5% and less than 30%.

[0091] According to the additional embodiment, based on the diameter of the aforementioned battery can, the length of the aforementioned flat section is 5% or more, 10% or more, or 15% or more.

[0092] According to the additional embodiment, based on the diameter of the aforementioned battery can, the length of the aforementioned flat section is less than 30%, less than 25%, or less than 20%.

[0093] Specifically, refer to Figure 5 When the length of the flat section 16 meets the above-mentioned range, the length of the flat section 16 provides sufficient space for subsequent welding processes, thereby reducing the defect rate and ensuring structural stability. However, when the length of the flat section 16 is less than 5%, the length of the flat section is too small and cannot provide sufficient space for subsequent welding processes, thereby increasing the defect rate during the welding process or preventing stable bonding at the welding points, thus reducing structural stability. In addition, if the length of the flat section 16 is greater than 30%, the end 10 of the open portion of the battery can will contact the electrode terminal formed at the upper center of the cover assembly 13, resulting in a short circuit and reducing the performance of the secondary battery.

[0094] According to one embodiment of the present invention, a multi-roller system is provided, wherein the pressure applied by the second roller is 101% or more and 300% or less relative to the pressure applied by the first roller.

[0095] According to the additional embodiment, the pressure applied by the second roller is 101% or more, 110% or more, 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, 170% or more, 180% or more, or 190% or more relative to the pressure applied by the first roller.

[0096] According to the additional embodiment, the pressure applied by the second roller is 300% or less, 290% or less, 280% or less, 270% or less, 260% or less, 250% or less, 240% or less, 230% or less, 220% or less, or 210% or less relative to the pressure applied by the first roller.

[0097] Specifically, refer to Figure 5 When the pressure applied by the second roller is less than 101% of the pressure applied by the first roller, it is not easy to further bend the end 10 of the open portion of the battery can in order to form a flat section 16 in the crimping portion 200. Furthermore, when the pressure applied by the second roller is greater than 300% of the pressure applied by the first roller, the excessive pressure makes it difficult to adjust the deformation of the end 10 of the open portion of the battery can. Consequently, excessive deformation during the formation of a flat section in the crimping portion increases the product defect rate.

[0098] According to one embodiment of the present invention, a battery can forming apparatus is provided, comprising:

[0099] The fixing unit, which fixes the battery canister; and

[0100] The multi-roller system described in any of the above embodiments.

[0101] Specifically, refer to Figure 2 The fixing unit 2 surrounds the middle or lower part of the battery can 1 to fix the battery can 1. As an example of the fixing unit 2, a chuck or jaw can be used. In addition, the number of fixing units varies depending on the molding state of the battery can or the size of the applicable model.

[0102] According to an embodiment of the present invention, a method for molding a battery can is provided, comprising:

[0103] The first step involves placing an electrode assembly with a structure consisting of a first electrode, a separation membrane, and a second electrode stacked and rolled in sequence in the battery can and injecting electrolyte. Then, the battery can is formed by pressing an edge portion formed inward toward the adjacent side end of the open portion of the battery can. A pad and a cover assembly are stacked on the edge portion.

[0104] The second step is to secure the aforementioned battery container;

[0105] The third step is to apply pressure to the end of the open portion located above the rolled edge, forming an inclined section in which the end of the open portion of the battery can is inclined toward the central axis of the battery can.

[0106] The fourth step involves applying pressure to the end of the open portion of the battery can with the aforementioned inclined section to form a sealed section parallel to the side of the battery can; and

[0107] The fifth step involves applying pressure to the end of the open portion of the battery can, which has the aforementioned inclined and sealed sections, to form a flat section parallel to the lower surface of the battery can.

[0108] At least two of the above-mentioned steps three through five utilize any one of the multi-roller systems described above.

[0109] In the above embodiments, the term "first electrode" refers to the anode and the term "second electrode" refers to the cathode, but the opposite is also possible.

[0110] The cathode described above includes a cathode current collector and a cathode active material coated onto at least one side of the cathode current collector. Examples of cathode current collectors include aluminum or alloys, but are not limited to these. Examples of cathode active materials include lithium-containing transition metal oxides, but are not limited to these.

[0111] The aforementioned anode includes an anode current collector and an anode active material coated on at least one side of the anode current collector. Examples of the anode current collector may be copper or an alloy, but are not limited thereto. Examples of the anode active material may be carbon materials, but are not limited thereto.

[0112] The aforementioned separation membrane, acting as a membrane between the cathode and the anode, separates the cathode and anode, facilitating the movement of ions required to interrupt the circuit. Examples of separation membranes include, but are not limited to, microporous films made of polyolefin membranes.

[0113] Furthermore, the aforementioned battery can, being a generally cylindrical housing with an opening on one side, is made of a conductive metal material. The side of the battery can and the opposite side of the opening are typically formed as one piece. That is, the battery can has a shape where the upper end is open based on its height direction, and the remaining area at the lower end, except for the central portion, is closed. The lower surface of the battery can is generally flat. The battery can houses the electrode assembly through the opening formed on one side in its height direction. The battery can also houses the electrolyte through the opening.

[0114] First, an electrode assembly with a structure consisting of a first electrode, a separation membrane, and a second electrode stacked and wound sequentially is placed in the battery can, and an electrolyte is injected. Then, a rolled edge portion is formed by pressing inwards at the side end adjacent to the open portion of the battery can, thus preparing a battery can with a rolled edge portion. Next, a gasket and a cover assembly are stacked on the rolled edge portion. These steps correspond to the steps prior to the pressing process.

[0115] Then, refer to Figures 2 to 5 The diagram illustrates the pressing process performed by the first to the third rollers.

[0116] Reference Figure 2 and Figure 3 By the first roller A ( Figure 3 The diagram shows that the cross section A' of the first roller applies pressure to the end 10 of the open portion of the battery can 1, thereby forming an inclined section 14 that is inclined toward the central axis of the battery can.

[0117] Additionally, refer to Figure 2 and Figure 4 The second roller B ( Figure 4 The diagram shows that the cross-section B' of the second roller applies pressure to the end 10 of the open portion of the battery can with the inclined section 14 formed, thereby forming a sealing section 15 perpendicular to the side portion 12 of the battery can. This sealing section 15 serves to seal the battery can 1 by the subsequent third roller.

[0118] Additionally, refer to Figure 2 and Figure 5 The third roller C ( Figure 5 The diagram shows that the cross-section C' of the third roller applies pressure between the rolled edge 100 and the open end 10 of the battery can, which has the inclined section 14 and the sealed section 15, thereby forming the flat section 16. The process of forming the inclined section 14, the sealed section 15 and the flat section 16 described above is called the crimping process, which is the process of joining the upper end cap and sealing the battery can after the electrolyte is injected.

[0119] The above-described process is a specific crimping process, which is executed sequentially in the first to third specific steps.

[0120] Additionally, refer to Figures 3 to 5 The cross-sections of the first to third rollers are formed into different shapes according to the target molding, and the height of each roller can be controlled. The rotation axes are also independent.

[0121] According to one embodiment of the present invention, a method for forming a battery can is provided, wherein, with the central axis of the battery can as a reference, the inclined interval of the end of the open portion of the battery can forms an angle greater than 0 degrees and less than 90 degrees.

[0122] According to the additional embodiment, with the central axis of the battery can as a reference, the inclined range of the end of the open portion of the battery can forms an angle greater than 0 degrees, greater than 10 degrees, greater than 20 degrees, greater than 30 degrees, or greater than 40 degrees.

[0123] According to the additional embodiment, with the central axis of the battery can as a reference, the inclined range of the end of the open portion of the battery can forms an angle of less than 90 degrees, less than 80 degrees, less than 70 degrees, less than 60 degrees, or less than 50 degrees.

[0124] Specifically, refer to Figure 3 With the central axis of the battery can as a reference, the inclined section 14 of the end 10 of the open portion of the battery can 1 forms an angle of approximately 30 degrees.

[0125] According to one embodiment of the present invention, a method for forming a battery can is provided, wherein, based on the diameter of the battery can, the length of the flat section is more than 5% and less than 30%.

[0126] According to the additional embodiment, based on the diameter of the aforementioned battery can, the length of the aforementioned flat section is 5% or more, 10% or more, or 15% or more.

[0127] According to the additional embodiment, based on the diameter of the aforementioned battery can, the length of the aforementioned flat section is less than 30%, less than 25%, or less than 20%.

[0128] Specifically, refer to Figure 5 When the length of the flat section 16 meets the aforementioned range, the length of the flat section 16 provides sufficient space for subsequent welding processes, thereby reducing the defect rate and ensuring structural stability. However, if the length of the flat section 16 is less than 5%, the length of the flat section is too small to provide sufficient space for subsequent welding processes, thereby increasing the defect rate that may occur during the welding process or preventing the formation of stable bonding forces at the welding points, thus leading to a decrease in structural stability. In addition, if the length of the flat section 16 is greater than 30%, the end 10 of the open portion of the battery can will contact the electrode terminal formed at the upper center of the cover assembly 13, resulting in a short circuit and a decrease in the performance of the secondary battery.

[0129] According to one embodiment of the present invention, a method for forming a battery can is provided, wherein the pressure applied to form the sealed section is 101% or more and 300% or less relative to the pressure applied to form the inclined section.

[0130] According to the additional embodiment, the pressure applied by the second roller is 101% or more, 110% or more, 120% or more, 130% or more, 140% or more, 150% or more, 160% or more, 170% or more, 180% or more, or 190% or more relative to the pressure applied by the first roller.

[0131] According to the additional embodiment, the pressure applied by the second roller is 300% or less, 290% or less, 280% or less, 270% or less, 260% or less, 250% or less, 240% or less, 230% or less, 220% or less, or 210% or less relative to the pressure applied by the first roller.

[0132] Specifically, refer to Figure 5 When the pressure applied by the second roller is less than 101% of the pressure applied by the first roller, it is not easy to further bend the end 10 of the open portion of the battery can to form a flat section 16 in the crimping portion 200.

[0133] Furthermore, if the pressure applied by the second roller is greater than 300% relative to the pressure applied by the first roller, the pressure is too high and it is difficult to adjust the deformation of the end 10 of the open portion of the battery can. As a result, the product defect rate increases due to excessive deformation during the formation of the flat section 16 in the crimping portion 200.

[0134] The preferred embodiments of the present invention have been described above, but the present invention is not limited thereto. Various modifications can be made within the scope of the claims and the detailed description of the invention, which also fall within the scope of the invention.

Claims

1. A multi-roller system comprising two or more pairs of rollers, wherein the two or more pairs of rollers are rotated with respect to independent rotation axes, and the height variation is controlled independently, at least one cross section of the two or more pairs of rollers has a different shape, the distance between the rollers of each pair and the battery can is different, and wherein the two or more pairs of rollers include: a first pair of rollers that presses the end of the open portion of the battery can to form a tilt section in which the end of the open portion of the battery can is inclined toward the central axis of the battery can; a second pair of rollers that presses the end of the open portion of the battery can in which the tilt section is formed to form a seal section that is perpendicular to the side of the battery can; and a third pair of rollers that presses the side of the open portion of the battery can in which the tilt section and the seal section are formed to form a flat section that is parallel to the lower surface of the battery can.

2. The multi-roller system according to claim 1, wherein the tilt section forms an angle of greater than 0 degrees and less than 90 degrees with respect to the central axis of the battery can.

3. The multi-roller system according to claim 1, wherein the length of the flat section is 5% or more and 30% or less with respect to the diameter of the battery can.

4. The multi-roller system according to claim 1, wherein the pressure applied by the second rollers is 101% or more and 300% or less with respect to the pressure applied by the first rollers.

5. A molding device that is a molding device for a battery can for a secondary battery, comprising: a fixing unit that fixes the battery can; and the multi-roller system according to any one of claims 1 to 4.

6. A molding method for a battery can, comprising: a first step of providing an electrode assembly to a battery can, injecting an electrolyte, and then forming a crimped portion, and laminating a pad and a cover assembly to the crimped portion, wherein the electrode assembly has a structure in which a first electrode, a separator, and a second electrode are sequentially laminated and wound, the crimped portion is formed at the side end portion of the battery can adjacent to the open portion, and is pressed inward; a second step of fixing the battery can; a third step of pressing the end of the open portion that is located higher than the crimped portion to form a tilt section in which the end of the open portion of the battery can is inclined toward the central axis of the battery can; a fourth step of pressing the end of the open portion of the battery can in which the tilt section is formed to form a seal section in which the end of the open portion of the battery can is perpendicular to the side of the battery can; and a fifth step of pressing the end of the open portion of the battery can in which the tilt section and the seal section are formed to form a flat section that is parallel to the lower surface of the battery can, the third step to the fifth step utilize the multi-roller system according to any one of claims 1 to 4.

7. The molding method for a battery can according to claim 6, wherein the tilt section of the end of the open portion of the battery can forms an angle of greater than 0 degrees and less than 90 degrees with respect to the central axis of the battery can.

8. The molding method for a battery can according to claim 6, wherein the length of the flat section is 5% or more and 30% or less with respect to the diameter of the battery can. The length of the flat section is 5% or more and 30% or less of the diameter of the battery can.

9. The battery can forming method according to claim 6, wherein The pressure applied to form the sealing section is 101% or more and 300% or less of the pressure applied to form the inclined section.

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