Flattening device and battery assembly system

Abstract

A flattening device and a battery assembly system, which solve the problem in the prior art of an insulating protective film outside an electrode assembly being wrinkled. The flattening device comprises a frame, a driving mechanism, and a pair of rollers matching with each other. The rollers are rotationally connected to the frame and are configured to flatten a member to be flattened; and the driving mechanism is arranged on the frame, is connected to the rollers, and is configured to drive the pair of rollers to rotate synchronously. In this way, the driving mechanism drives the pair of rollers to rotate synchronously, such that the linear speeds of outer surfaces of the two rollers are the same, thereby solving the problem in the prior art of rotation speeds of a pair of rollers being different due to two driving sources being used to respectively drive the pair of rollers.

Description

Smoothing device and battery assembly system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 2023116215144, filed on November 28, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a smoothing device and a battery assembly system. Background Art

[0004] The battery consists of a casing and an electrode assembly, which is mounted within the casing. Because the electrode assembly is wrapped in an insulating protective film, wrinkles in the film can expose the electrode assembly. If the exposed portion of the electrode assembly comes into contact with the casing, it could cause a short circuit, explosion, or other safety hazards.

[0005] Summary of the Invention

[0006] The main technical problem solved by the present application is to provide a smoothing device and a battery assembly system to solve the problem of wrinkles in the insulating protective film outside the electrode assembly in the prior art.

[0007] To address the aforementioned technical issues, the first technical solution employed in this application is to provide a smoothing device comprising a frame, a drive mechanism, and a pair of cooperating rollers. The rollers are rotatably connected to the frame and are used to smooth the workpiece. The drive mechanism is mounted on the frame and connected to the rollers, driving the pair of rollers to rotate synchronously. This allows the drive mechanism to drive the pair of rollers to rotate synchronously, ensuring that the linear velocity of the outer surfaces of the two rollers is the same, thereby resolving the problem in related art where two drive sources are used to drive the rollers at different speeds.

[0008] In some embodiments, the drive mechanism includes a rack and a pair of gears; the gear is coaxially disposed with the roller, and both gears mesh with the rack; the rack extends in a first direction and is movable relative to the frame in the first direction; wherein, as the rack moves in the first direction, at least a portion of the rack drives the pair of gears to rotate synchronously. Thus, since the gear is coaxially disposed with the roller, as the rack moves in the first direction, at least a portion of the rack drives the pair of gears to rotate synchronously, resulting in the roller and the gear having the same rotational speed (i.e., angular velocity), and thus the two rollers having the same rotational speed (i.e., linear velocity of the outer surfaces of the rollers).

[0009] In some embodiments, the smoothing device further comprises: an elastic member and a pair of sliding members; the sliding member is slidably connected to the frame and slides relative to the frame in a second direction; the roller is rotatably connected to the sliding member; the elastic member is configured to drive the pair of sliding members toward or away from each other in the second direction; the second direction is perpendicular to the first direction and to the axis of the roller. As the rack moves in the first direction, the distance between the pair of rollers in the second direction gradually decreases to a predetermined distance and then gradually increases.

[0010] In this way, as the rack moves along the first direction, the pair of sliding members are driven by the elastic member to move closer to or away from each other in the second direction, so that the pair of rollers move closer to or away from each other in the second direction, and the pair of gears and the rack are always engaged. As the rack moves along the first direction, the distance between the pair of rollers along the second direction gradually decreases to a preset spacing and then gradually increases. As the distance between the two rollers gradually decreases, the two rollers gradually approach the electrode assembly. When the distance between the two rollers is a preset spacing, the two rollers clamp the electrode assembly so that the two rollers smooth the electrode assembly; and the outer surface linear velocity of the two rollers is the same as the speed at which the shell insertion device pushes the electrode assembly, so that the electrode assembly can be placed in the shell, reducing the occurrence of wrinkles in the insulating protective film outside the electrode assembly. As the distance between the two rollers gradually increases, the two rollers gradually separate from the electrode assembly.

[0011] In some embodiments, the rack has two opposing tooth surfaces along the second direction, and a pair of gears mesh with the two tooth surfaces of the rack. One of the two tooth surfaces can be concave, while the other can be parallel to the first direction; alternatively, both tooth surfaces can be concave. This allows a single rack to drive two gears, simplifying the structure.

[0012] In some embodiments, the concave tooth surface includes a first section of tooth surface, a second section of tooth surface and a third section of tooth surface connected in sequence; the second section of tooth surface is parallel to the first direction; along the first direction, the multiple tooth structure sizes of the first section of tooth surface first gradually decrease, and the multiple tooth structure sizes of the third section of tooth surface first gradually increase; wherein the tooth structure size is the size between a tooth structure and the center line of the rack along the second direction; the center line extends along the first direction.

[0013] This results in the first, second, and third tooth surfaces being all linear. The first and third tooth surfaces are connected at an angle to the ends of the second tooth surface. This allows the distance between the gear and the centerline to gradually decrease, then remain constant, and then increase when the gear meshes with the concave tooth surface. Furthermore, linear tooth surfaces are easy to manufacture and relatively inexpensive.

[0014] In some embodiments, the included angle between the first section tooth surface and the second section tooth surface is 120° to 150°; and / or the included angle between the third section tooth surface and the second section tooth surface is 120° to 150°.

[0015] Thus, when the included angle is less than 120°, the first section of the tooth surface is smaller along the first direction. A slight movement of the rack allows the gear to engage with the second section of the tooth surface, resulting in a higher speed for the gear meshing with the first section of the tooth surface. When the included angle is less than 150°, the first section of the tooth surface is larger along the first direction, resulting in a heavier rack. The effect of the included angle on the third section of the tooth surface can be compared to the effect of the included angle on the first section of the tooth surface.

[0016] In some embodiments, the racks are symmetrically arranged along a symmetry axis parallel to the first direction, and symmetrically arranged along a symmetry axis parallel to the second direction. This makes the rack structure simpler and easier to manufacture.

[0017] In some embodiments, the elastic member includes two compression elastic members connected between the frame and the sliding member, and the compression elastic members are located on the side where the two rollers are separated from each other; or the elastic member includes a tension elastic member connected between the pair of sliding members. In this way, when the rack moves in the first direction, the two gears engage with the rack, and the pair of rollers are moved closer to or farther away from each other due to the thrust generated by the two compression elastic members and / or the tension generated by the tension elastic member.

[0018] In some embodiments, the rack includes a first rack and a second rack arranged along the second direction; a pair of gears are located between the first rack and the second rack, and are respectively engaged with the tooth surfaces of the first rack and the second rack; wherein the tooth surface of the first rack is an outward convex tooth surface, and the tooth surface of the second rack is parallel to the first direction; or, the tooth surface of the first rack and the tooth surface of the second rack are both outward convex tooth surfaces.

[0019] In this way, the first and second racks respectively mesh with the two gears. When the first and second racks move synchronously in the first direction, they drive the two gears to rotate. By changing the mounting positions of the first and second racks without changing their combined weight, the distance between the two rollers can be varied, facilitating the pair of rollers to clamp electrode assemblies of different sizes.

[0020] In some embodiments, the smoothing device further comprises a slide rail disposed on the frame, and the sliding member is slidably disposed on the slide rail; or the frame has a slide groove, and the sliding member is slidably disposed on the slide groove. In this way, the provided slide rail and / or slide groove can enable the sliding member to slide relative to the frame.

[0021] In some embodiments, the sliding member has a mounting hole, and the drum is rotatably arranged in the mounting hole. In this way, no other components are needed to realize the rotational connection between the sliding member and the drum.

[0022] To solve the above technical problems, the second technical solution provided by this application is as follows: a battery assembly system is provided, comprising a conveying device, an assembly device, and the aforementioned smoothing device; the conveying device is used to convey the structure to be assembled to each workstation of the assembly device; the workstations of the assembly device include a shell insertion device; the shell insertion device is used to insert the electrode assembly into the shell from the open end; when the electrode assembly is inserted into the shell, a pair of rollers of the smoothing device are used to clamp and smooth the electrode assembly passing through the pair of rollers. Because the battery assembly system includes the aforementioned smoothing device, the battery assembly system has the effects of the aforementioned smoothing device, which will not be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] FIG1 is a front view of a smoothing device provided by the present application;

[0025] FIG2 is a top view of a smoothing device provided by the present application;

[0026] FIG3 is a schematic diagram of the structure of a rack and a pair of gears meshing with each other provided by the present application;

[0027] FIG4 is a front view of another smoothing device provided by the present application;

[0028] FIG5 is a top view of another smoothing device provided by the present application;

[0029] FIG6 is a top view of another smoothing device provided by the present application;

[0030] FIG7 is a schematic diagram of the structure of another rack and a pair of gears meshing provided by the present application;

[0031] FIG8 is a top view of another smoothing device provided by the present application;

[0032] FIG9 is a schematic diagram of the structure of the first rack and the second rack meshing with a pair of gears provided by the present application;

[0033] FIG10 is a front view of the battery assembly system provided by the present application;

[0034] FIG11 is a top view of the battery assembly system provided in the present application.

[0035] In the figure: 1. Smoothing device; 11. Frame; 12. Driving mechanism; 122. Rack; 1221. First rack; 1222. Second rack; 123. First section of tooth surface; 124. Second section of tooth surface; 125. Third section of tooth surface; 121. Gear; 132. Rotating shaft; 133. Roller; 14. Slide rail; 15. Elastic member; 16. Sliding member; 17. Driving member; 2. Shell; 3. Electrode assembly; 4. Conveying equipment; 5. Assembly equipment; 51. Shell insertion device. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present application in detail with reference to the accompanying drawings.

[0037] In the following description, for the purpose of explanation rather than limitation, specific details such as specific system structures, interfaces, and technologies are provided to facilitate a thorough understanding of the present application.

[0038] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] The terms "first," "second," and "third" in this application are used only for descriptive purposes and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional indications in the embodiments of this application (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship, movement, etc. between the components under a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications also change accordingly. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products, or devices.

[0040] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] In related technologies, a battery includes a housing and an electrode assembly (also called a cell), which is wrapped with an insulating protective film. The electrode assembly is installed within the housing using a housing insertion device and a smoothing device, which can reduce wrinkles in the insulating protective film surrounding the electrode assembly. The housing insertion device can be referred to as the housing insertion device described below.

[0042] The existing smoothing device includes two roller mechanisms, each of which includes a drive source and a roller, and the drive source drives the roller to rotate. The two rollers can be used to smooth the electrode assembly and then install it in the shell. However, if the drive sources of the two roller mechanisms have control problems (for example, there is a difference in the current received by the two drive motors), the two drive sources will drive the rollers at different speeds. The two rollers with different speeds will cause the insulating protective film of the electrode assembly located between the two rollers to wrinkle, thereby exposing the electrode assembly. The exposed part of the electrode assembly will contact the shell, causing safety accidents such as short circuit and explosion of the battery.

[0043] The present invention provides a smoothing device that can be used during the installation of an electrode assembly into a housing. The smoothing device can be used to smooth the electrode assembly before installing it into the housing. This solves the problem of wrinkles in the insulating protective film covering the electrode assembly, preventing the insulating protective film from exposing the electrode assembly and reducing battery accidents.

[0044] Of course, the smoothing device can also be used in other fields. For example, the smoothing device can be used to transport lithium strips, electrodes, etc. For example, the lithium strip is located between the two rollers of the smoothing device, and the two rollers transport the lithium strip when they rotate. For another example, the smoothing device can be used to stretch a plate. For example, the plate is placed between the two rollers, and the length or width of the plate is extended and the thickness is reduced by the extrusion of the two rotating rollers. The material of the plate can be a metal, and the metal can be a metal element (such as lithium, iron, aluminum, copper, silver, etc.), and the metal can also be an alloy of the above metal elements (such as aluminum alloy, lithium alloy, iron alloy, silver alloy, copper alloy, etc.). The following is an example of using a smoothing device to smooth an electrode assembly.

[0045] Referring to Figures 1 and 2 , the smoothing device 1 may include a frame 11, a pair of rollers 133, and a drive mechanism 12. The rollers 133 are rotatably connected to the frame 11 and are used to smooth the workpiece. The drive mechanism 12 is disposed on the frame 11 and connected to the rollers 133, and is used to drive the pair of rollers 133 to rotate synchronously. In this way, the drive mechanism 12 drives the pair of rollers 133 to rotate synchronously, ensuring that the linear velocity of the outer surfaces of the two rollers 133 is the same, thus resolving the problem of using two drive sources to drive the pair of rollers at different speeds in the related art.

[0046] During the process of installing the electrode assembly in the shell by the shell insertion device 51, the electrode assembly passes between the two rollers 133. The two rollers 133 have the same speed, which can smooth the electrode assembly so that the electrode assembly is facing the open end of the shell (that is, the gap between the two rollers 133 is facing the open end of the shell), and the electrode assembly can directly enter the shell; this solves the problem of the electrode assembly rubbing against the shell during the process of the electrode assembly entering the shell, causing wrinkles in the insulating protective film.

[0047] In some embodiments, the drive mechanism 12 may include a driving wheel and a pair of driven wheels, the driven wheels being coaxially arranged with the rollers 133. The driving wheel drives the pair of driven wheels to rotate synchronously via a belt or chain, thereby causing the pair of rollers 133 to rotate synchronously. In some examples, the drive mechanism 12 may include a driving member. The driving member is mounted on the frame 11 and connected to the driving wheel to drive the driving wheel to rotate. For example, the driving member may drive a motor.

[0048] In some embodiments, the drive mechanism 12 may include a driving gear and a pair of driven gears, the driven gears being coaxially arranged with the rollers 133. The driving gear and the pair of driven gears are meshed with each other. When the driving gear rotates, the driving gear drives the pair of driven gears to rotate synchronously, thereby causing the pair of rollers 133 to rotate synchronously. In some examples, the drive mechanism 12 may include a driving member. The driving member is mounted on the frame 11. The driving member is connected to the driving gear to drive the driving gear to rotate. For example, the driving member may drive a motor.

[0049] In some embodiments, the drive mechanism 12 may include a rack 122 and a pair of gears 121. The gear 121 is coaxially disposed with the roller 133, and both gears 121 mesh with the rack 122. The rack 122 extends in a first direction X and is movable relative to the frame 11 in the first direction X. During the movement of the rack 122 in the first direction X, at least a portion of the rack 122 drives the pair of gears 121 to rotate synchronously. In some examples, the drive mechanism 12 may include a drive member 17. The drive member 17 may be mounted on the frame. The drive member 17 is connected to the rack 122 and is configured to drive the rack 122 to move in the first direction X. For example, the drive member 17 may be a mechanism capable of extending and retracting in the first direction X (referred to as a telescopic mechanism), which drives the rack 122 to move in the first direction X. The telescopic mechanism may be a hydraulic telescopic mechanism, a pneumatic telescopic mechanism, an electric linear actuator, or the like.

[0050] In this way, since the gear 121 and the roller 133 are coaxially arranged, when the rack 122 moves along the first direction X, at least a portion of the rack 122 drives the pair of gears 121 to rotate synchronously, so that the rotational speed (i.e., angular velocity) of the roller 133 and the gear 121 is the same, and thus the rotational speed of the two rollers 133 (i.e., the linear velocity of the outer surface of the roller 133) is the same.

[0051] An embodiment of the present application provides a comparative solution, which may include a pair of coordinated belt roller mechanisms. The belt roller mechanism may include a mounting frame, a cylinder, a roller, a belt, and a drive motor. The cylinder, belt, and drive motor are all mounted on the mounting frame, and the drive motor drives the roller to rotate via the belt. The roller is slidably mounted on the mounting frame. The cylinder is connected to the roller and is used to push the roller to slide, thereby causing the rollers of the pair of belt roller mechanisms to move toward or away from each other. When the rollers of the pair of belt roller mechanisms move toward each other, they clamp the electrode assembly and smooth it. When the rollers of the pair of belt roller mechanisms move away from each other, they separate from the electrode assembly. In this manner, a shell insertion device is used to move the electrode assembly between the rollers of the pair of belt roller mechanisms and push the electrode assembly into the shell. During the process of pushing the electrode assembly into the shell using the shell insertion device, the cylinder is first controlled to move the rollers of the pair of belt roller mechanisms toward each other, clamping the electrode assembly and smoothing it. Then, as the shell insertion device pushes, the electrode assembly enters the open end of the shell. Finally, the cylinder is controlled to move the rollers in the pair of belt roller mechanisms away from each other, so that the rollers in the pair of belt roller mechanisms are separated from the electrode assembly.

[0052] However, in each belt-roller mechanism, a drive motor drives the rollers via a belt. If a control failure occurs in the drive motors of a pair of belt-roller mechanisms (for example, a difference in the current received by the two drive motors), the two drive motors will rotate at different speeds, resulting in different rotational speeds for the two rollers. These different rotational speeds can cause wrinkles in the insulating protective film of the electrode assembly located between the two rollers.

[0053] Compared to the belt-and-roller mechanism in the comparative solution, the embodiment of the present application utilizes a single power source (e.g., the aforementioned drive member 17 ). This drive member 17 drives the rack 122 in the first direction X, aligning the speeds of the two gears 121 meshing with the rack 122 and, consequently, the rotational speeds of the two rollers 133 . This eliminates the problem of different rotational speeds of the two rollers 133 due to power source issues and also reduces costs. This, in turn, increases stability, reduces failure rates, and improves product quality.

[0054] The rack 122 extends along the first direction X, that is, the length direction of the rack 122 is parallel to the first direction X. In some examples, the multiple tooth structures (also referred to as teeth) of the rack 122 can be arranged as multiple tooth structures on a straight rack. In other examples, the multiple tooth structures of the rack 122 can be arranged as multiple tooth structures on a helical rack.

[0055] The rack 122 can move along the first direction X relative to the frame 11 ; that is, the frame 11 is fixed and the rack 122 can move along the first direction X.

[0056] Gear 121 is coaxially arranged with roller 133. In some examples, gear 121 is mounted on roller 133 in a contacting manner. In other examples, gear 121 and roller 133 are connected by a connector; for example, the connector is a rotating shaft 132, on which both roller 133 and gear 121 are mounted, and the rotating shaft 132 is rotatably mounted on the frame 11. A pair of matched rollers can be understood as one in which the axes of the pair of rollers 133 are parallel and intersecting (e.g., perpendicular to) the first direction X.

[0057] Each pair of gears 121 meshes with a rack 122. That is, if one gear 121 meshes with the rack 122, the other gear 121 also meshes with the rack 122. In some examples, the ratio of the number of racks 122 to the number of gears 121 is 1:2. For example, there can be one rack 122 and two gears 121. Another example is two racks 122 and four gears 121. This way, the racks 122, gears 121, and racks 122 can more stably drive the pair of rollers.

[0058] The roller 133 is rotatably connected to the frame 11, which can be understood as both ends of the roller 133 being rotatably connected to the frame 11. For example, the frame 11 has a first through hole, and the roller 133 is rotatably arranged in the first through hole. For another example, the roller 133 is rotatably arranged with the sliding member 16, and the sliding member 16 is slidably connected to the frame 11. The frame 11 may include two mounting plates opposite to each other along the second direction Y, and the mounting plates may be installed on the preset workstations described below. For example, the mounting plate has a first through hole. For another example, the sliding member 16 is slidably connected to the mounting plate. The frame 11 may also include a connecting plate, which connects the two mountings into an integrated structure. The positions of the rack 122 and the frame 11 are not limited. For example, the rack 122 may be located inside the frame 11. For another example, the rack 122 may be located outside the frame 11.

[0059] At least a portion of the rack 122 drives the pair of gears 121 to rotate synchronously. It can be understood that when the pair of gears 121 are engaged with at least a portion of the rack 122, the pair of gears 121 rotate simultaneously and at the same speed, so that the surface linear speed of the pair of rollers 133 is the same; they also stop at the same time.

[0060] For example, referring to Figures 1 to 3, when the tooth surface of the rack 122 is parallel to the first direction X, the rack 122 can be called a straight rack; for example, the straight rack can have two tooth surfaces facing each other; for another example, the rack 122 can also include a first rack and a second rack, and the tooth surface of the first rack is opposite to the tooth surface of the second rack. Among them, the two tooth surfaces of the straight rack are different from the tooth surfaces of the rack 122 having two tooth surfaces facing each other below, and the other aspects are the same (such as installation position, connection relationship); similarly, the tooth surfaces of the straight rack including the first rack and the second rack are different from the tooth surfaces of the rack 122 including the first rack 1221 and the second rack 1222 below, and the other aspects are the same (such as installation position, connection relationship); no further details will be given.

[0061] When rack 122 is a spur rack, as rack 122 moves along first direction X, all parts of rack 122 drive the pair of gears 121 to rotate synchronously. At this time, roller 133 is rotationally connected to frame 11, and roller 133 is non-slidingly connected to frame 11, so that the distance between the two rollers 133 remains unchanged. Frame 11 is provided with a first through-hole; for example, roller 133 is positioned within the first through-hole, with a clearance fit between roller 133 and the first through-hole; or, for another example, roller 133 is disposed within the first through-hole via a bearing. In one possible implementation, shaft 132 is disposed within the first through-hole via a bearing.

[0062] In this way, when the rack 122 is a straight rack, the distance between the two rollers 133 is adjusted to be the same as the width or length of the electrode assembly, and the electrode assembly can be smoothed by using the two rollers 133.

[0063] As another example, referring to Figures 1 and 5 , as rack 122 moves along the first direction X, a portion of rack 122 drives the pair of gears 121 to rotate synchronously; this portion of rack 122 can be understood as a spur rack. When rack 122 is not a spur rack, the meshing of the pair of gears 121 with rack 122 causes the distance between the pair of gears 121 to change, thereby changing the distance between the pair of rollers 133 along the second direction Y. The rack 122 is described in detail below and is not further described here.

[0064] In some embodiments, referring to Figures 1 and 5 to 9 , the smoothing device 1 further includes: an elastic member 15 and a pair of sliding members 16 ; the sliding member 16 is slidably connected to the frame 11 and slides relative to the frame 11 in a second direction Y; a roller 133 is rotatably connected to the sliding member 16 ; the elastic member 15 is configured to drive the pair of sliding members toward or away from each other in the second direction Y; the second direction Y is perpendicular to the first direction X and to the axis of the roller 133 . As the rack 122 moves in the first direction X, the distance between the pair of rollers 133 in the second direction Y gradually decreases to a predetermined distance and then gradually increases.

[0065] In this way, as the rack 122 moves in the first direction X, the elastic member 15 drives the pair of sliders toward or away from each other in the second direction Y, causing the pair of rollers 133 to move toward or away from each other in the second direction Y. This also keeps the pair of gears 121 and the rack 122 in constant meshing. As the rack 122 moves in the first direction X, the distance between the pair of rollers 133 in the second direction Y gradually decreases to a predetermined distance and then gradually increases. As the distance between the two rollers 133 gradually decreases, they gradually approach the electrode assembly. When the distance between the two rollers 133 reaches the predetermined distance, the two rollers 133 clamp the electrode assembly, smoothing it. The outer surface linear velocity of the two rollers 133 is the same as the speed at which the shell insertion device pushes the electrode assembly, thereby positioning the electrode assembly within the shell and reducing wrinkles in the insulating protective film on the outer surface of the electrode assembly. As the distance between the two rollers 133 gradually increases, the two rollers 133 gradually separate from the electrode assembly.

[0066] The meshing of the rack 122 and the pair of gears 121 in this embodiment replaces the drive motor, belt, and cylinder in the pair of belt roller mechanisms of the related art. That is, the meshing of the rack 122 and the pair of gears 121 in this embodiment can perform the functions of the drive motor, belt, and cylinder in the related art while also simplifying the structure and reducing costs.

[0067] The term "preset spacing" means that rack 122 drives the pair of rollers 133 to rotate within a preset time, and during this preset time, the distance between the pair of rollers 133 along the second direction Y remains unchanged, and the pair of rollers 133 rotate synchronously. In other words, the preset spacing corresponds to the situation described below when gear 121 meshes with the second tooth surface. The preset time refers to the time it takes to insert the electrode assembly into the housing; for example, the time it takes to smooth the electrode assembly.

[0068] The elastic member 15 can be a structure capable of generating an elastic force; the elastic member 15 can be a spring and / or a spring. The elastic force of the elastic member 15 is used to drive the pair of rollers 133 toward or away from each other along the second direction Y. In some examples, the elastic force generated by the elastic member 15 is directed in the second direction Y. In other examples, the elastic force generated by the elastic member 15 is at an angle to the second direction Y, and the elastic force has a component in the second direction Y, which can drive the pair of rollers 133 toward or away from each other along the second direction.

[0069] When the pair of sliding members 16 move toward or away from each other along the second direction Y, it can be understood that one sliding member 16 does not move while the other slide 16 moves; it can also be understood that both sliding members 16 can move. When the pair of rollers 133 move toward or away from each other along the second direction Y, it can be understood that one roller 133 does not move while the other roller 133 moves; it can also be understood that both rollers 133 can move.

[0070] The sliding member 16 is slidably connected to the frame 11. It can be understood that one sliding member 16 (which can be called the first sliding member) is slidably connected to the frame 11, and the other sliding member 16 (which can be called the second sliding member) is slidably connected to the frame 11. The roller 133 is rotationally connected to the sliding member 16. It can be understood that one roller 133 (which can be called the first roller) is rotationally connected to the first sliding member, and the other roller 133 (which can be called the second roller) is rotationally connected to the second sliding member.

[0071] The number of the first sliding members may be at least two (e.g., two, or three). The number of the second sliding members may be at least two (e.g., two, or three). For example, the number of the first sliding members and the number of the second sliding members may be the same, or, for example, both may be two.

[0072] In other embodiments, as the rack 122 moves along the first direction X, the distance between the pair of rollers 133 along the second direction Y gradually decreases to a predetermined distance. In other embodiments, as the rack 122 moves along the first direction X, the distance between the pair of rollers 133 along the second direction Y is a predetermined distance and then gradually increases.

[0073] In some embodiments, referring to Figures 1 and 5-7 , the rack 122 has two opposing tooth surfaces along the second direction Y (in this case, the rack 122 can be referred to as a double-sided rack 122 or double-sided teeth), and a pair of gears 121 are respectively engaged with the two tooth surfaces of the rack 122; one of the two tooth surfaces is concave, and the other is parallel to the first direction X; alternatively, both tooth surfaces are concave. In this way, a single rack 122 can drive the rotation of two gears 121, simplifying the structure.

[0074] It can be understood that the concave tooth surface has a first portion of the tooth surface (i.e., the second portion of the tooth surface 124 hereinafter) parallel to the first direction X; the second portion of the tooth surface and the third portion of the tooth surface are located on the side of the first portion of the tooth surface away from the opposite tooth surface, and a first angle exists between the second portion of the tooth surface and the first portion of the tooth surface; the first angle is greater than 90° and less than 180° (for example, 91°, 95°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 179°, etc.); a second angle exists between the third portion of the tooth surface and the first portion of the tooth surface; the second angle is greater than 90° and less than 180° (for example, 91°, 95°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 179°, etc.). In some examples, the second portion of the tooth surface can be a curved tooth surface (e.g., a minor arc), in which case the first angle can be understood as the angle between the tangent of the curved tooth surface and the first portion of the tooth surface. In other examples, the second portion of the tooth surface can be a straight tooth surface. The number of the second portion of the tooth surface can be a segment of tooth surface, in which case the second portion of the tooth surface can be referred to as the first segment of tooth surface 123 below. The number of the second portion of the tooth surface can also be multiple segments of tooth surfaces connected in sequence; for example, the angle between the extension line of the multiple segments of tooth surface and the first portion of the tooth surface increases in sequence, or decreases in sequence, or first increases and then decreases, etc.

[0075] The shape of the third tooth surface can refer to the relevant description of the shape of the second tooth surface. The number of the third tooth surface can refer to the relevant description of the number of the second tooth surface. When the number of the third tooth surface is one section, the third tooth surface can be referred to as the third end tooth surface below.

[0076] For example, one of the two tooth surfaces is concave, and the other tooth surface is parallel to the first direction X. In this case, the gear 121 meshing with one tooth surface rotates and slides relative to the frame 11, while the gear 121 meshing with the other tooth surface rotates relative to the frame 11 and does not slide in the second direction Y. In other words, the elastic member 15 drives the gear 121 meshing with one tooth surface to move, while the gear 121 meshing with the other tooth surface does not move.

[0077] In another exemplary embodiment, both tooth surfaces are concave tooth surfaces. At this time, the two gears 121 with the two tooth surfaces meshing rotate relative to the frame 11 and also slide relative to the frame 11 along with the sliding member 16. That is, the elastic member 15 drives the two gears 121 with the two tooth surfaces meshing to move.

[0078] In some embodiments, the concave tooth surface includes a first tooth surface 123, a second tooth surface 124, and a third tooth surface 125 connected in sequence; the second tooth surface 124 is parallel to the first direction X; along the first direction X, the multiple tooth structure sizes of the first tooth surface 123 gradually decrease, and the multiple tooth structure sizes of the third tooth surface 125 gradually increase; wherein the tooth structure size is the size between a tooth structure and the center line of the rack 122 along the second direction Y; the center line extends along the first direction X.

[0079] This results in the first, second, and third tooth surfaces 123, 124, and 125 being all linear. These surfaces are connected at an angle to the ends of the second tooth surface 124. This ensures that when gear 121 engages this concave tooth surface, the distance between gear 121 and the centerline gradually decreases, then remains constant and then increases. Furthermore, linear tooth surfaces are easier to manufacture and less expensive. In this case, the first, second, and third tooth surfaces 123, 124, 125 can be configured as shown in Figure 7.

[0080] In some embodiments, the angle between the first tooth surface 123 and the second tooth surface 124 (i.e., the first angle) is 120°~150° (for example, 120°, 125°, 130°, 135°, 140°, 145°, 150°, etc.); and / or, the angle between the third tooth surface 125 and the second tooth surface 124 (i.e., the second angle) is 120°~150° (for example, 120°, 125°, 130°, 135°, 140°, 145°, 150°, etc.).

[0081] Thus, when the included angle is less than 120°, the dimension of the first tooth surface 123 along the first direction X is smaller, and the rack 122 moves slightly, allowing the gear 121 to engage with the second tooth surface 124. This results in a higher rotational speed for the gear 121 engaged by the first tooth surface 123. When the included angle is less than 150°, the dimension of the first tooth surface 123 along the first direction X is larger, resulting in a heavier rack 122. The effect of the included angle of the third tooth surface 125 can be compared to the effect of the included angle of the first tooth surface 123.

[0082] In some embodiments, the rack 122 is symmetrically arranged along a symmetry axis parallel to the first direction X, and is also symmetrically arranged along a symmetry axis parallel to the second direction Y. In this way, the structure of the rack 122 is relatively simple and easy to manufacture.

[0083] In some embodiments, as shown in FIG6 , the elastic member 15 includes two compression elastic members connected between the frame 11 and the sliding member 16 ; the compression elastic members are located on the side away from the two rollers 133 . Alternatively, as shown in FIG5 , the elastic member 15 includes a tension elastic member connected between the pair of sliding members 16 .

[0084] In this way, when the rack 122 moves along the first direction X, the two gears 121 engage with the rack 122 , and under the action of the thrust generated by the two compression elastic members and / or the tension generated by the tension elastic member, the pair of rollers 133 move closer to or farther away from each other.

[0085] Exemplarily, the elastic member 15 includes two compression elastic members connected between the frame 11 and the slider 16; the compression elastic members are located on the side away from each other of the two rollers 133. Another exemplary embodiment, the elastic member 15 includes a tension elastic member connected between the pair of sliders 16. Another exemplary embodiment, the elastic member 15 includes two compression elastic members connected between the frame 11 and the slider 16; the compression elastic members are located on the side away from each other of the two rollers 133. The elastic member 15 includes a tension elastic member connected between the pair of sliders 16.

[0086] The elastic member 15 can be fixedly connected to the frame 11, for example, by welding, gluing, etc.; or detachably connected, for example, the elastic member 15 is hung on a hook of the frame 11. The elastic member 15 can be fixedly connected to the sliding member 16, for example, by welding, gluing, etc.; or detachably connected, for example, the elastic member 15 is hung on a hook of the sliding member 16.

[0087] The compression elastic member is located on the side of the two rollers 133 away from each other; it can be understood that one compression elastic member is located on the side of the first roller away from the second roller; and the other compression elastic member is located on the side of the second roller away from the first roller.

[0088] The elastic member 15 includes two compression elastic members connected between the frame 11 and the sliding member 16. It can be understood that one compression elastic member (which may be referred to as the first compression elastic member) is connected between the frame 11 and the first sliding member, and the other compression elastic member (which may be referred to as the second compression elastic member) is connected between the frame 11 and the second sliding member. The number of each of the first and second compression elastic members can be at least one. For example, the number of the first and second compression elastic members can be equal, and each can be, for example, two.

[0089] The number of the tensile elastic member may be at least one, and the at least one tensile elastic member is connected between the pair of sliding members 16 .

[0090] In some embodiments, the elastic member 15 includes two tensile elastic members connected between the frame 11 and the sliding member 16, and located between the pair of rollers 133. Thus, when the rack 122 moves along the first direction X, the two gears 121 engage with the rack 122, and the tension generated by the two tensile elastic members causes the pair of rollers 133 to move closer to or farther from each other.

[0091] In some embodiments, referring to Figures 1, 8 and 9, the rack 122 includes a first rack 1221 and a second rack 1222 arranged along the second direction Y; a pair of gears 121 are located between the first rack 1221 and the second rack 1222, and are respectively engaged with the tooth surfaces of the first rack 1221 and the second rack 1222; wherein the tooth surface of the first rack 1221 is an outward convex tooth surface, and the tooth surface of the second rack 1222 is parallel to the first direction X; or, the tooth surface of the first rack 1221 and the tooth surface of the second rack 1222 are both outward convex tooth surfaces.

[0092] In this way, the first rack 1221 and the second rack 1222 respectively mesh with the two gears 121. When the first rack 1221 and the second rack 1222 move synchronously along the first direction X, the first rack 1221 and the second rack 1222 drive the two gears 121 to rotate. Without changing the total weight of the first rack 1221 and the second rack 1222, the distance between the two rollers 133 can be changed by changing the installation position of the first rack 1221 and the second rack 1222, thereby facilitating the pair of rollers 133 to clamp electrode assemblies of different sizes.

[0093] For example, in order to facilitate the synchronous movement of the first rack 1221 and the second rack 1222 along the first direction X; for example, the first rack 1221 and the second rack 1222 are connected into an integral structure through a connecting member; for another example, the first rack 1221 and the second rack 1222 are installed on the same component (for example, installed on the above-mentioned driving member 17).

[0094] The pair of gears 121 are located between the first rack 1221 and the second rack 1222 ; it can be understood that the first rack 1221 , the pair of gears 121 , and the second rack 1222 are arranged in sequence along the second direction Y. For example, the first rack 1221 and the second rack 1222 can be arranged opposite each other or staggered.

[0095] The convex tooth surface can be understood that the fourth part of the tooth surface of the tooth surface is parallel to the first direction X; the fifth part of the tooth surface and the sixth part of the tooth surface are located between the side surface opposite to the fourth part of the tooth surface and the tooth surface, and there is a third angle between the fifth part of the tooth surface and the fourth part of the tooth surface; the third angle is greater than 90° and less than 180° (for example, 91°, 95°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 179°, etc.); there is a fourth angle between the sixth part of the tooth surface and the fourth part of the tooth surface; the fourth angle is greater than 90° and less than 180° (for example, 91°, 95°, 100°, 110°, 120°, 130°, 140°, 150°, 160°, 170°, 179°, etc.). In some examples, the fifth tooth surface can be a curved tooth surface (e.g., a minor arc), in which case the third angle can be understood as the angle between the tangent of the curved tooth surface and the fourth tooth surface. In other examples, the fifth tooth surface can be a straight tooth surface. The number of the fifth tooth surface can be one segment. The number of the second tooth surface can be multiple segments connected in sequence; for example, the angle between the extension line of the multiple segments and the fourth tooth surface can increase, decrease, or first increase and then decrease.

[0096] The shape of the sixth tooth surface can refer to the relevant description of the shape of the fifth tooth surface, and the number of the sixth tooth surface can refer to the relevant description of the number of the fifth tooth surface.

[0097] Exemplarily, the tooth surface of the first rack 1221 is an outwardly convex tooth surface, while the tooth surface of the second rack 1222 is parallel to the first direction X. At this time, the gear 121 meshed with the tooth surface of the first rack 1221 rotates relative to the frame 11 and also slides; the gear 121 meshed with the tooth surface of the second rack 1222 rotates relative to the frame 11 and does not slide in the second direction Y. In other words, the elastic member 15 drives the gear 121 meshed with the tooth surface of the first rack 1221 to move, while the gear 121 meshed with the tooth surface of the second rack 1222 does not move.

[0098] As another example, the tooth surfaces of the first rack 1221 and the second rack 1222 are both outwardly convex. In this case, the two gears 121 meshing with the tooth surfaces of the first rack 1221 and the second rack 1222 rotate and slide relative to the frame 11. In other words, the elastic member 15 drives the two gears 121 meshing with the tooth surfaces of the first rack 1221 and the second rack 1222 to move.

[0099] Because the embodiment in which the rack 122 includes two opposing tooth surfaces and the embodiment in which the rack 122 includes a first rack 1221 and a second rack 1222 can both change the distance between the two rollers 133. Therefore, the description and explanation of the embodiment in which the rack 122 includes a first rack 1221 and a second rack 1222 can refer to the relevant description and explanation of the embodiment in which the rack 122 includes two opposing tooth surfaces. For example, the elastic member 15 includes a compression elastic member connected between a pair of sliding members 16. And / or, the elastic member 15 includes two tension elastic members connected between the frame 11 and the sliding member 16, and the tension elastic members are located on the side of the two rollers 133 that is away from each other.

[0100] In some embodiments, as shown in Figures 5 and 6 , the smoothing device further includes a slide rail 14 disposed on the frame 11, and a slider 16 slidably disposed on the slide rail 14; alternatively, the frame 11 includes a slide groove, and the slider 16 slidably disposed on the slide groove. In this manner, the slide rail 14 and / or the slide groove allow the slider 16 to slide relative to the frame 11.

[0101] Exemplarily, the smoothing device further includes a slide rail 14, which is provided on the frame 11, and a sliding member 16 is slidably provided on the slide rail 14. In some examples, the slide rail 14 is provided on the top of the frame 11. In another example, the frame 11 has a slide groove, and the sliding member 16 is slidably provided on the slide groove. In another example, the smoothing device further includes a slide rail 14, which is provided on the frame 11, and the sliding member 16 is slidably provided on the slide groove and the slide rail 14. In some examples, the sliding member slides simultaneously on the slide rail 14 and the slide groove. For example, the sliding member is located between the slide rail 14 and the slide groove, so that two opposite parts of the sliding member are slidably connected to the slide rail and the slide groove, respectively. For another example, the slide rail 14 and the slide groove are provided side by side, so that parts on the same side of the sliding member are both slidably connected to the slide rail and the slide groove. In other examples, the slide rail 14 and the slide groove are connected, and the extension directions of the two are the same.

[0102] In certain embodiments, the sliding member 16 has a mounting hole, and the roller 133 is rotatably arranged in the mounting hole. In this way, no other components are needed to realize the rotation connection of the sliding member 16 and the roller 133.

[0103] Exemplarily, the roller 133 is loosely fitted with the mounting hole, and the roller 133 is inserted into the mounting hole. In another exemplary embodiment, the roller 133 is rotatably disposed in the mounting hole via a bearing. In some examples, the rotating shaft 132 is rotatably disposed in the mounting hole via the roller 133.

[0104] In some embodiments, the sliding member 16 is provided with a bearing seat, and the roller 133 is rotatably disposed in the bearing seat.

[0105] In some embodiments, when at least a portion of the rack 122 drives the pair of gears 121 to rotate synchronously, the gears 121 rotate at a constant speed.

[0106] The embodiments of the present application also provide a battery assembly system. Referring to Figures 10 and 11, the battery assembly system is configured to install an electrode assembly 3 coated with an insulating protective film in a housing 2. In some examples, the battery assembly system is further configured to encapsulate the electrode assembly 3 in the housing 2 (i.e., snap the upper cover onto the housing 2) to form a battery. The embodiments of the present disclosure are described using an example in which the battery assembly system is configured to install an electrode assembly 3 coated with an insulating protective film in a housing 2.

[0107] The battery assembly system may include a conveying device 4, an assembly device 5, and a smoothing device 1. The conveying device 4 is used to transport the structure to be assembled to each workstation of the assembly device 5. The workstations of the assembly device 5 include a shell insertion device 51. The shell insertion device 51 is used to insert the electrode assembly 3 into the shell 2 from the open end. When the electrode assembly 3 is inserted into the shell 2, the pair of rollers 133 of the smoothing device 1 is used to clamp and smooth the electrode assembly 3 passing through the pair of rollers 133. In this way, the synchronous rotation of the shell insertion device 51 and the pair of rollers 133 allows the electrode assembly 3 to be smoothed and installed in the shell 2, which can reduce the problem of wrinkles in the insulating protective film wrapped around the electrode assembly 3.

[0108] The conveying equipment 4 includes a conveying line, which can be a conveying structure formed by a motor-driven conveying roller and a conveyor belt, or a conveying structure formed by a motor-driven conveying chain link, or an AGV conveying cart, which can realize conveying in at least one direction and support and ensure the stability of the structure to be assembled.

[0109] The shell insertion device 51 is a pushing mechanism or a clamping mechanism that can stably move the electrode assembly toward the open end of the shell and enter the accommodating cavity through the open end. The pushing mechanism can be a cylinder, an electric push rod, etc. The clamping mechanism can be a vacuum suction cup, a clamping claw mechanism, a fork mechanism, etc. In some embodiments, when a pair of gears 121 rotate synchronously, the linear velocity of the outer surface of the roller 133 is the same as the movement speed of the shell insertion device pushing the electrode assembly 3 between the pair of rollers 133. This is to reduce the problem of wrinkles on the insulating protective film of the electrode assembly 3 when the two speeds are different.

[0110] The electrode assembly 3 is an electrode assembly 3 wrapped with an insulating protective film. The insulating protective film can be made of a material having both insulating and protective functions, such as resin.

[0111] The battery may include an end cap, a shell 2 and an electrode assembly 3. The shell 2 has an open end, and the end cap is snapped onto the open end of the shell 2, together defining a receiving cavity for accommodating the electrode assembly 3. That is, the electrode assembly 3 is installed in the shell 2 through the open end and is snapped onto the shell 2 through the end cap; so that the electrode assembly 3 is located in the receiving cavity. For example, the end cap and the shell 2 are connected by screws, snaps, etc. In some examples, the battery may be referred to as a battery cell. The battery cell may include a lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc. The battery cell may be cylindrical, flat, or in other shapes. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells, and soft-pack battery cells.

[0112] In some embodiments, a pole is provided on the wall of the shell 2 opposite to the open end, and the pole has a through hole. The shell 2 and the end cover are connected to form a accommodating cavity connected to the through hole; the active material coating part of the electrode assembly 3 is provided in the shell 2, and the pole ear part of the electrode assembly 3 passes through the through hole and is connected to the side of the pole away from the accommodating cavity.

[0113] The workstations of the assembly equipment 5 may also include a tab welding device, a tab piercing device, a pole welding device, and an end cap welding device. The tab welding device is used to weld the multiple tab sheets of the electrode assembly to form the tab portion; the tab piercing device is used to clamp the tab portion through the through-hole when the electrode assembly is installed in the housing; and the pole welding device is used to weld the tab portion passing through the through-hole to the side of the pole facing away from the accommodating cavity.

[0114] The purpose of the tab welding device is to form the tab portion after pre-welding the tab sheet. It can be an ultrasonic welding device that can ensure that the tab is welded in a clamped and stable state. The tab piercing device can adopt a clamping structure or a guiding structure that can guide the tab portion to pass through the through-hole smoothly without interfering with the shell. The purpose of the pole welding device is to achieve welding of the tab portion and the pole. It can be a laser welding device. The purpose of the end cap welding device is to achieve circumferential edge welding of the end cap and the open end of the shell. It is also a laser welding device.

[0115] In some embodiments, when the number of electrode assemblies 3 is multiple, for example, two, the assembly equipment 5 also includes a matching device, which is used to stack multiple electrode assemblies so that the pole tabs of the two electrode assemblies are roughly opposite to each other, so that the conveying structure can convey the matched electrode assemblies to the pole tab welding device for welding the pole tabs to facilitate the formation of the pole tab portion.

[0116] In some embodiments, in order to ensure the reliability of the battery assembly process, a dust removal station, an NG detection station, etc. may be added between any two adjacent stations, which is not limited in this embodiment.

[0117] In some embodiments, as the rack 122 moves along the first direction X, the distance between the pair of rollers 133 along the second direction Y first gradually decreases to a preset spacing and then gradually increases. During the process of the shell insertion device 51 loading the electrode assembly 3 between the pair of rollers 133 into the shell 2, the rack 122 drives the pair of gears 121 to engage, and under the action of the elastic member 15, the pair of rollers 133 gradually approach to a preset spacing along the second direction Y. At the preset spacing, the pair of rollers 133 clamp the electrode assembly 3 and smooth the electrode assembly 3; then the pair of rollers 133 gradually move away from each other along the second direction Y and release the electrode assembly 3.

[0118] The gap between the two rollers 133 is aligned with the open end of the shell 2. Smoothing the electrode assembly 3 can be understood as making the inclined electrode assembly 3 aligned with the open end of the shell 2 when passing through the two rollers 133.

[0119] The above description is only an implementation method of the present application and does not limit the scope of patent protection of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the scope of patent protection of the present application.

Claims

1. A smoothing device, wherein: include: frame; A pair of matching rollers; The roller is rotatably connected to the frame and is used to smooth the workpiece to be smoothed; as well as, The driving mechanism is arranged on the frame and connected with the rollers, and is used for driving a pair of the rollers to rotate synchronously.

2. The smoothing device according to claim 1, wherein: The driving mechanism includes a rack and a pair of gears; the gear is coaxially arranged with the drum, and the pair of gears are meshed with the rack; the rack extends along a first direction and can move along the first direction relative to the frame; wherein, during the process of the rack moving along the first direction, at least part of the rack drives the pair of gears to rotate synchronously.

3. The smoothing device according to claim 2, wherein: The smoothing device further comprises: an elastic member and a pair of sliding members; the sliding member is slidably connected to the frame, and the sliding member slides relative to the frame along a second direction; the roller is rotatably connected to the sliding member; the elastic member is configured to drive the pair of sliding members to move closer to or away from each other along the second direction; the second direction is perpendicular to the first direction and perpendicular to the axis direction of the roller; As the rack moves along the first direction, the distance between a pair of rollers along the second direction first gradually decreases to a preset distance and then gradually increases.

4. The smoothing device according to claim 3, wherein: Along the second direction, the rack has two tooth surfaces facing each other, and a pair of gears are respectively meshed on the two tooth surfaces of the rack; Among them, one of the two tooth surfaces is a concave tooth surface, and the other tooth surface is parallel to the first direction; or, both of the two tooth surfaces are concave tooth surfaces.

5. The smoothing device according to claim 4, wherein: The concave tooth surface includes a first section of tooth surface, a second section of tooth surface and a third section of tooth surface which are connected in sequence; the second section of tooth surface is parallel to the first direction; along the first direction, the multiple tooth structure sizes of the first section of tooth surface first gradually decrease, and the multiple tooth structure sizes of the third section of tooth surface first gradually increase; wherein, the tooth structure size is the size between a tooth structure and the center line of the rack along the second direction; the center line extends along the first direction.

6. The smoothing device according to claim 5, wherein: The included angle between the first section tooth surface and the second section tooth surface is 120° to 150°; and / or, The included angle between the third section tooth surface and the second section tooth surface is 120° to 150°.

7. The smoothing device according to any one of claims 4 to 6, wherein: The racks are symmetrically arranged along a symmetry axis parallel to the first direction, and are symmetrically arranged along a symmetry axis parallel to the second direction.

8. The smoothing device according to any one of claims 4 to 7, wherein: The elastic member includes two compression elastic members, the compression elastic members are connected between the frame and the sliding member, and the compression elastic members are located on a side of the two rollers away from each other; or, The elastic member includes a tensile elastic member connected between a pair of the sliding members.

9. The smoothing device according to claim 3, wherein: The rack includes a first rack and a second rack arranged along the second direction; a pair of gears are located between the first rack and the second rack, and are respectively meshed with the tooth surfaces of the first rack and the second rack; wherein the tooth surface of the first rack is an outward convex tooth surface, and the tooth surface of the second rack is parallel to the first direction; or, the tooth surface of the first rack and the tooth surface of the second rack are both outward convex tooth surfaces.

10. The smoothing device according to any one of claims 3 to 9, wherein: The smoothing device further comprises a slide rail, the slide rail is arranged on the frame, and the sliding member is slidably arranged on the slide rail; or, The frame has a slide groove, and the sliding member is slidably arranged on the slide groove.

11. The smoothing device according to any one of claims 3 to 9, wherein: The sliding member has a mounting hole, and the roller is rotatably disposed in the mounting hole.

12. A battery assembly system, wherein: It comprises a conveying device, an assembling device and a smoothing device according to any one of claims 1 to 11; the conveying device is used to convey the structure to be assembled to each workstation of the assembling device; the workstation of the assembling device comprises a shell-entering device; the shell-entering device is used to load the electrode assembly into the shell from the open end of the shell; when the electrode assembly is loaded into the shell, a pair of rollers of the smoothing device are used to clamp and smooth the electrode assembly passing through the pair of rollers.

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