Rotary pole piece cutter assembly and pole piece cutting mechanism

Abstract

A rotary pole piece cutter assembly and a pole piece cutting mechanism, the rotary pole piece cutter assembly comprises: a cutter roller shaft that can rotate around its own axis, the surface of the cutter roller shaft is provided with a blade portion, the blade portion protrudes from the surface of the cutter roller shaft along the radial direction of the cutter roller shaft, and the blade portion extends in a direction parallel to the axis of the cutter roller shaft; a cutter back roller arranged in parallel with the cutter roller shaft, the distance between the blade portion and the cutter back roller is less than the total thickness of the diaphragm in the pole piece; a rotary drive unit that drives the cutter back roller to rotate. The present invention adopts a rotary cutter and a cutter back roller extrusion method to cut the lithium strip by extrusion force. Compared with the traditional flat cutter that cuts the lithium strip by shearing, the cutter assembly of the present invention will not cut the diaphragm of the outer layer of the lithium strip, and can cut the lithium strip without cutting the diaphragm, so that the winding station does not need to pause and wait, the action is closely coordinated, the efficiency is improved, and the structure is compact, which is suitable for the refined requirements of the equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium battery manufacturing equipment, and in particular relates to a cutting mechanism and a cutter assembly for a cylindrical lithium primary battery pole piece. Background Art

[0002] Lithium primary batteries generally use metallic lithium as the negative electrode material. The negative electrode structure includes two layers of separators and a layer of lithium ribbon. The lithium ribbon is arranged between the two layers of separators. Metal oxides or other solid or liquid oxidants are used as positive electrode active materials, and solid salts or salts dissolved in organic solvents are used as electrolytes. When preparing lithium primary batteries, the lithium ribbon is placed between the two layers of separators, and then the separator drives the lithium ribbon to be wound to form a winding core. Since the lithium ribbon is located between the two layers of separators, the existing automated winding equipment needs to pause and wait in order to cut the lithium ribbon without cutting the separator, which brings difficulties to the fully automated winding production of lithium primary batteries and affects production efficiency. Summary of the invention

[0003] The object of the present invention is to provide a rotary pole piece cutter assembly and a pole piece cutting mechanism which can cut lithium strips without cutting the diaphragm during continuous winding, thereby improving the production efficiency of the equipment.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A rotary pole piece cutter assembly comprises: a cutter roller shaft rotatable around its own axis, a cutting edge portion being arranged on the surface of the cutter roller shaft, the cutting edge portion protruding from the surface of the cutter roller shaft in a radial direction of the cutter roller shaft, and the cutting edge portion extending in a direction parallel to the axis of the cutter roller shaft; a cutter back roller arranged parallel to the cutter roller shaft, the distance between the cutting edge portion and the cutter back roller being less than the total thickness of the diaphragm in the pole piece; and a rotary drive unit driving the cutter back roller to rotate.

[0006] Furthermore, the distance D between the blade portion and the cutter back roller is d-Δ, d is the total thickness of the diaphragm in the pole piece, and Δ is 18-40 μm.

[0007] Furthermore, the cutter back roller can rotate around its own axis.

[0008] Furthermore, the cutter back roller rotates synchronously with the cutter roller shaft.

[0009] It can be seen from the above technical scheme that due to the characteristics of metallic lithium, it is relatively brittle and has no ductility, and cannot withstand large tension cutting. For the negative electrode composed of two layers of diaphragms and a lithium ribbon sandwiched between the diaphragms, the rotary electrode cutter assembly and the electrode cutting mechanism of the present invention adopt a rotary cutter and a cutter back roller to extrude the lithium ribbon through the extrusion force. Compared with the traditional flat cutter that cuts the lithium ribbon in a shearing manner, the cutter assembly of the present invention will not cut the diaphragm of the outer layer of the lithium ribbon, and can cut the lithium ribbon without cutting the diaphragm, so that the winding station does not need to pause and wait, the movements are closely coordinated, the efficiency is improved, and the structure is compact, which is suitable for the refined requirements of the equipment.

[0010] The present invention also provides a pole piece cutting mechanism, comprising: a mounting frame, a winding pressure wheel, a cutting knife assembly, a pole piece pressure wheel assembly and a film feeding clamp, wherein the cutting knife assembly is the aforementioned rotary pole piece cutting knife assembly; the winding pressure wheel, the cutting knife assembly and the pole piece pressure wheel assembly are sequentially arranged on the mounting frame, the pole piece pressure wheel assembly comprises a fixed pressure wheel and a movable pressure wheel arranged relatively to each other, the movable pressure wheel can be periodically pressed on or away from the fixed pressure wheel, the film feeding clamp can be movably arranged behind the pole piece pressure wheel assembly in a direction approaching or away from the pole piece pressure wheel assembly, and when the film feeding clamp approaches the pole piece pressure wheel assembly, the pole piece is fed between the fixed pressure wheel and the movable pressure wheel.

[0011] Furthermore, the pole piece pressure wheel assembly also includes a fixed bracket arranged on the mounting frame, a movable bracket arranged on the fixed bracket through a rotating shaft, and an elastic member arranged between the fixed bracket and the movable bracket, the movable bracket can rotate around the rotating shaft relative to the fixed bracket, the movable pressure wheel is arranged on the movable bracket, the elastic member makes the rotating bracket always have a tendency to press the movable pressure wheel thereon onto the fixed pressure wheel, and the movable bracket can drive the movable pressure wheel to leave the fixed pressure wheel under the action of external force.

[0012] Furthermore, it also includes a cam that rotates synchronously with the cutter roller shaft, and the cam can directly or indirectly contact the movable bracket, so that the movable bracket drives the movable pressure wheel to leave the fixed pressure wheel.

[0013] Furthermore, it also includes a linkage rod arranged on the mounting frame through a rotating shaft, one end of the linkage rod is connected to the movable bracket, and the free end is arranged beside the cam, and the cam can touch the free end of the linkage rod during rotation.

[0014] Furthermore, the cam is arranged on the rotating shaft of the cutter back roller, a first synchronous wheel is also arranged on the rotating shaft of the cutter back roller, a second synchronous wheel is arranged on the rotating shaft of the cutter roller shaft, and the first synchronous wheel and the second synchronous wheel are meshed with each other.

[0015] Furthermore, the rotation driving unit is a motor, and the motor directly or indirectly drives the first synchronous wheel to rotate.

[0016] It can be seen from the above technical solutions that the electrode sheet cutting mechanism of the present invention adopts a combined cutter of a rotary cutter and a cutter backing roller, and adopts an extrusion cutting method, which can cut the lithium strip without cutting the diaphragm, so that the winding station of the winding equipment does not need to pause and wait, and can be wound continuously, thereby improving production efficiency. In a more specific technical solution, the opening / closing of the pressure wheel, the precise synchronization of feeding and cutting are realized by a cam structure that rotates synchronously with the rotary knife, which is conducive to ensuring the winding quality of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic diagram of the positions of the pole piece cutting mechanism and the winding head according to an embodiment of the present invention;

[0019] Figure 2 It is a structural schematic diagram of a pole piece cutting mechanism according to an embodiment of the present invention;

[0020] Figure 3 It is a structural schematic diagram of the pole piece cutting mechanism from another angle according to an embodiment of the present invention;

[0021] Figure 4 It is a transmission schematic diagram of a rotation drive unit according to an embodiment of the present invention;

[0022] Figure 5 It is a structural schematic diagram of a cam according to an embodiment of the present invention;

[0023] Figure 6 It is a schematic diagram of the stroke design of the cam according to an embodiment of the present invention.

[0024] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] The present invention is described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present invention in detail, for the convenience of explanation, the drawings representing the device structure will not be partially enlarged according to the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present invention. It should be noted that the drawings are simplified in form and use non-precise proportions, which are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention. At the same time, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated; the terms "positive", "negative", "bottom", "upper", "lower", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0026] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 The pole piece cutting mechanism of this embodiment includes a rotary pole piece cutter assembly 1, a rotary drive unit 2, a winding pressure wheel 3, a pole piece pressure wheel assembly 4, a cam 5, a film feeding clamp 6 and a mounting frame 7. The pole piece cutting mechanism is used to cut the negative pole piece structure composed of a double-layer diaphragm and a layer of lithium ribbon. The lithium ribbon is clamped between the two layers of diaphragms. The pole piece cutting mechanism is arranged beside the winding head of the winding equipment. The winding head winds the stacked diaphragms and lithium ribbons to form a battery cell. The pole piece cutting mechanism is used to cut the lithium ribbon between the two layers of diaphragms without cutting the diaphragms. The rotary pole piece cutter assembly 1, the winding pressure wheel 3, the pole piece pressure wheel assembly 4, and the cam 5 are all arranged on the mounting frame 7. The film feeding clamp 6 is movably arranged behind the pole piece pressure wheel assembly 4 (the moving direction of the film feeding clamp 6 is Figure 1 The rotation drive unit 2 can be directly or indirectly arranged on the mounting frame 7. The mounting frame 7 is also provided with one or more diaphragm passing wheels (not numbered), and the diaphragm is firstly wound on the diaphragm passing wheels and then sent into the pole piece pressing wheel assembly 4.

[0027] The rotary pole piece cutter assembly 1 comprises a cutter roller shaft 1-1 and a cutter back roller 1-2. The cutter roller shaft 1-1 and the cutter back roller 1-2 are both rotatably arranged on a mounting frame 7 around their own axes via bearings. The cutter roller shaft 1-1 and the cutter back roller 1-2 are arranged opposite to each other and a fixed interval is maintained between them. A blade portion 1-3 extending in a direction parallel to the axis of the cutter roller shaft 1-1 is arranged on the surface of the cutter roller shaft 1-1. The blade portion 1-3 protrudes from the surface of the cutter roller shaft 1-1 in the radial direction of the cutter roller shaft 1-1, and the blade portion 1-3 may be the same length as the cutter roller shaft 1-1. As the cutter roller shaft 1-1 rotates, the blade portion 1-3 will periodically face the cutter back roller 1-2. The distance D between the blade portion 1-3 and the cutter back roller 1-2 is set accordingly according to the thickness of the two layers of diaphragms in the lithium negative electrode sheet. For example, when the total thickness d of the two layers of diaphragms in the lithium negative electrode sheet is 0.02 mm, the distance D between the blade portion 1-3 and the surface of the cutter back roller 1-2 is slightly less than 0.02 mm, D = d-Δ, Δ = 18 to 40 μm. The blade portion 1-3 and the cutter back roller 1-2 of the present invention are both made of rigid materials and have high hardness.

[0028] Compared with the lithium belt, the diaphragm material has higher ductility and toughness, while the lithium belt is not ductile and is relatively brittle. The present invention utilizes the different characteristics of the two materials and adopts an extrusion cutting method for cutting the lithium belt. Since the blade portion 1-3 radially protrudes from the surface of the cutter roller shaft 1-1, the distance between the blade portion 1-3 and the cutter back roller 1-2 is smaller than the distance between other positions on the surface of the cutter roller shaft 1-1 and the cutter back roller 1-2. When the blade portion 1-3 rotates to be opposite to the cutter back roller 1-2, the tiny gap between the blade portion 1-3 and the cutter back roller 1-2 will squeeze the electrode material. The diaphragm is ductile and will not be broken by extrusion. The lithium belt is not ductile and will be broken by extrusion between the blade portion 1-3 and the cutter back roller 1-2, thereby cutting the lithium belt while keeping the diaphragm continuous. This rotary extrusion cutting method solves the problem of not cutting the diaphragm on the outside of the lithium belt but only cutting the lithium belt, which cannot be achieved by the transmission cutter cutting.

[0029] Continue to refer to Figure 1As shown, the winding roller 3, the rotary pole piece cutter assembly 1, and the pole piece roller assembly 4 are sequentially arranged on the mounting frame 7, the winding roller 3 is arranged adjacent to the winding head 100, and the pole piece roller assembly 4 is used to press the diaphragm and the lithium strip when cutting the lithium strip. The pole piece roller assembly 4 includes a fixed roller 4-1 and a movable roller 4-2, the fixed roller 4-1 and the movable roller 4-2 are arranged opposite to each other, and the diaphragm and the lithium strip pass through the two. The fixed pressure wheel 4-1 of this embodiment is located above the movable pressure wheel 4-2. The fixed pressure wheel 4-1 is fixedly arranged on the mounting frame 7. The movable pressure wheel 4-2 can be arranged on the mounting frame 7 to move relative to the fixed pressure wheel 4-1. The movable pressure wheel 4-2 of this embodiment is arranged on the mounting frame 7 through the rotating bracket 4-3 and the fixed bracket 4-4. The rotating bracket 4-3 is connected to the fixed bracket 4-4 through a rotating shaft. The movable pressure wheel 4-2 is arranged on the rotating bracket 4-3. When the rotating bracket 4-3 rotates around the rotating shaft, it can drive the movable pressure wheel 4-2 to move, so that the movable pressure wheel 4-2 approaches and presses on the fixed pressure wheel 4-1 or leaves the fixed pressure wheel 4-1. An elastic member 4-5 is arranged between the rotating bracket 4-3 and the fixed bracket 4-4. The elastic member 4-5 provides a supporting force for the rotating bracket 4-3, so that the movable pressure wheel 4-2 on the rotating bracket 4-3 always has a tendency to press on the fixed pressure wheel 4-1. The cam 5 rotates synchronously with the cutter roller shaft 1-1. The function of the cam 5 is to periodically drive the movable pressure wheel 4-2 away from the fixed pressure wheel 4-1 according to the set stroke, so that the fixed pressure wheel 4-1 and the movable pressure wheel 4-2 are opened, so that the film feeding clamp 6 can insert the lithium ribbon between the two layers of diaphragms. The film feeding clamp 6 can be controlled to move by a conventional drive unit such as a cylinder, a motor, and an electric push rod. The cam 5 of this embodiment is coaxially arranged with the cutter back roller 1-2, that is, the cam 5 is set on the rotating shaft of the cutter back roller 1-2.

[0030] Combination Figure 4As shown, the rotary drive unit 2 of this embodiment adopts a motor, and the motor drives the first synchronous wheel 2-1 to rotate through a synchronous chain. The first synchronous wheel 2-1 is arranged on the rotating shaft of the cutter back roller 1-2. The first synchronous wheel 2-1 and the second synchronous wheel 2-2 are meshed, and the second synchronous wheel 2-2 is arranged on the rotating shaft of the cutter roller shaft 1-1. When the motor is started, the cutter roller shaft 1-1 and the cutter back roller 1-2 can be driven to rotate through the synchronous chain and the two synchronous wheels. The cam 5 of this embodiment is arranged on the rotating shaft of the cutter back roller 1-2, so the cam 5 will also rotate synchronously with the cutter back roller 1-2. A linkage rod 8 is arranged on the mounting frame 7, and the linkage rod 8 is arranged on the mounting frame 7 through a rotating shaft and can rotate with the rotating shaft. One end of the linkage rod 8 is connected to the rotating bracket 4-3, and the other end (free end) is located beside the cam 5. During the rotation process, the protrusion of the cam 5 will periodically contact the free end of the linkage rod 8. When the cam 5 contacts the linkage rod 8, it will drive the linkage rod 8 to rotate around the rotating shaft. When the linkage rod 8 rotates, it will drive the movable bracket 4-3 to rotate around the fixed bracket 4-4, thereby driving the movable pressure wheel 4-2 away from the fixed pressure wheel 4-1, so that the feeding clamp 6 can insert the lithium ribbon between the two layers of diaphragms. According to the contour design and installation position of the cam 5, the movable pressure wheel 4-2 will first press the pole piece, and the cam 5 will continue to rotate. The cutting roller shaft 1-1 will also rotate, and then the blade 1-3 on it will cut the lithium ribbon. The movable pressure wheel 4-2 presses the pole piece in advance to prevent the pole piece from being brought back due to tension after cutting. Figure 5 and Figure 6 For the structure and stroke design of the cam in this embodiment, when the cam rotates to different stages, the movable pressure wheel will be in the corresponding position, cooperating with the fixed pressure wheel to open or press the electrode piece, and the cutter will also cut the lithium ribbon at the corresponding stage. Figure 6 At the middle point a angle, the movable pressing wheel and the fixed pressing wheel are closed, at the point b angle, the movable pressing wheel is opened, at the point c angle, the film feeding clamp 6 feeds the lithium belt, at the point d angle, the movable pressing wheel and the fixed pressing wheel are closed, and at the point e angle, the lithium belt is cut off.

[0031] Combine the following Figure 1 , the action process of the pole piece cutting mechanism of this embodiment is described:

[0032] In the initial state, the winding head has completed the reversal, the upper diaphragm 101 and the lower diaphragm 102 have completed the cutting, the rotary pole piece cutter assembly 1 is in place, and the movable pressing wheel 4-2 is opened;

[0033] The film feeding clamp 6 feeds the lithium ribbon 103 to the winding needle of the winding head 100 under the control of the film feeding driving mechanism (not shown);

[0034] The rotary drive unit 2 drives the cam 5 to rotate, and the cutter roller shaft 1-1 and the cutter back roller 1-2 also rotate synchronously;

[0035] Cam 5 runs in the base circle segment;

[0036] The rolling pressure wheel 3 is closed, and the winding needle starts rolling;

[0037] The cam 5 continues to rotate, and then the movable pressure wheel 4-2 and the fixed pressure wheel 4-1 are closed, and then the cutter roller shaft 1-1 rotates until the blade portion 1-3 and the cutter back roller 1-2 are opposite, the blade portion 1-3 and the cutter back roller 1-2 squeeze the lithium belt 103, cut off the lithium belt 103, and the rotation drive unit 2 stops.

[0038] The present invention can be applied to cylindrical lithium primary battery winding equipment to achieve cutting of pole pieces without cutting the diaphragm during continuous winding.

[0039] Of course, the technical concept of the present invention is not limited to the above-mentioned embodiments, and many different specific schemes can be obtained based on the concept of the present invention. For example, the motor can use other transmission structures to drive the cutter roller shaft and the cutter back roller, and the upper and lower positions of the movable pressure wheel and the fixed pressure wheel can be interchanged. The setting position of the cam can also be adjusted according to the equipment space. It is not limited to being set on the rotating shaft of the cutter back roller. As long as it can rotate synchronously with the cutter roller shaft, it can control the opening / closing of the pressure wheel and achieve coordination with the cutting action; or other external force mechanisms can be set on the mounting frame to synchronously open the movable pressure wheel with the rotation of the rotating knife. The use of a synchronously rotating cam is not only compact in structure, but also can ensure a higher synchronization rate, which is beneficial to ensuring the winding quality; such changes and equivalent transformations should be included in the scope of the present invention.

Claims

1. The pole piece cutting mechanism is characterized by: include: Mounting frame, winding pressure wheel, cutter assembly, pole piece pressure wheel assembly and film feeding clamp, the cutter assembly includes: A cutter roller shaft rotatable around its own axis, wherein a blade portion is provided on the surface of the cutter roller shaft, the blade portion protrudes from the surface of the cutter roller shaft in a radial direction of the cutter roller shaft, and the blade portion extends in a direction parallel to the axis of the cutter roller shaft; A cutter back roller is arranged parallel to the cutter roller shaft, and the distance between the blade portion and the cutter back roller is less than the total thickness of the diaphragm in the pole piece; A rotary drive unit for driving the cutter back roller to rotate; The winding pressure wheel, the cutting knife assembly, and the pole piece pressure wheel assembly are sequentially arranged on the mounting frame, the pole piece pressure wheel assembly comprises a fixed pressure wheel and a movable pressure wheel arranged relatively to each other, the movable pressure wheel can be periodically pressed on or away from the fixed pressure wheel, the sheet feeding clamp can be movably arranged behind the pole piece pressure wheel assembly in a direction close to or away from the pole piece pressure wheel assembly, and when the sheet feeding clamp approaches the pole piece pressure wheel assembly, the pole piece is fed between the fixed pressure wheel and the movable pressure wheel; The movable pressure wheel is arranged on the mounting frame via a rotating bracket and a fixed bracket, the rotating bracket is connected to the fixed bracket via a rotating shaft, and the movable pressure wheel is arranged on the rotating bracket; A cam is arranged on the rotating shaft of the cutter back roller, and a linkage rod is arranged on the mounting frame through a rotating shaft and can rotate around the rotating shaft. One end of the linkage rod is connected to the rotating bracket, and the other end is located beside the cam. When the cam rotates, its protrusion will periodically contact with the free end of the linkage rod, thereby driving the linkage rod to rotate, so that the rotating bracket rotates around the fixed bracket; The cutter back roller rotates synchronously with the cutter roller shaft.

2. The electrode cutting mechanism according to claim 1, characterized in that: The distance D between the blade portion and the cutter back roller is d-Δ, d is the total thickness of the diaphragm in the pole piece, and Δ is 18-40 μm.

3. The electrode cutting mechanism according to claim 1, characterized in that: The cutter back roller can rotate around its own axis.

4. The electrode cutting mechanism according to claim 1, characterized in that: The pole piece pressure wheel assembly also includes an elastic member arranged between the fixed bracket and the rotating bracket, and the elastic member enables the rotating bracket to always have a tendency to press the movable pressure wheel thereon onto the fixed pressure wheel. The rotating bracket can drive the movable pressure wheel to leave the fixed pressure wheel under the action of external force.

5. The electrode cutting mechanism according to claim 1, characterized in that: A first synchronous wheel is also arranged on the rotating shaft of the cutter back roller, and a second synchronous wheel is arranged on the rotating shaft of the cutter roller shaft, and the first synchronous wheel and the second synchronous wheel are meshed with each other.

6. The pole piece cutting mechanism according to claim 5, characterized in that: The rotation driving unit is a motor, and the motor directly or indirectly drives the first synchronous wheel to rotate.

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