Stretching method, stretching device and production line

Abstract

This invention belongs to the field of battery technology and discloses a stretching method, a stretching device, and a production line. The stretching method includes: S10: confirming the extension amount w of the material area in the width direction; S20: an adjustment layer is wrapped around the tension roller and set corresponding to two empty foil areas, the thickness of the adjustment layer is h, h = w / 2; S30: after adjusting the tension F of the tension roller, the electrode sheet is stretched. The stretching device and the production line adopt this stretching method. This stretching method, stretching device, and production line can intuitively, conveniently, and quickly confirm the thickness of the adjustment layer. Subsequent debugging does not require changing the thickness of the adjustment layer, improving the wrinkling phenomenon caused by the transverse compression of the empty foil area by the material area and the wrinkling or even breakage phenomenon caused by the longitudinal extension of the empty foil area being much smaller than the longitudinal extension of the material area (thus the tension on the empty foil area is greater than that on the material area).

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a stretching method, stretching apparatus, and production line. Background Technology

[0002] Electrode stretching is a crucial step in electrode production. Stretched electrodes should have a smooth, flat surface, free of particles, and without warping or wrinkles. However, in continuous coating, the stretching process often results in the material area extending beyond the edge empty foil area (due to the roller gap during stretching, the empty foil area experiences less stress). This leads to greater longitudinal stress on the empty foil area compared to the material area, potentially causing strip breakage, or the lateral extension of the material area compressing the edge empty foil area, causing wrinkles. The industry typically adds an adjustment layer at the position of the tension roller corresponding to the empty foil area, then adjusts the tension to stretch the empty foil area, making its extension close to or even identical to that of the material area after stretching, thus reducing the risk of wrinkles and strip breakage in the empty foil area. However, there is currently no clear and quantitative method for confirming the thickness of the adjustment layer. After setting the adjustment layer, its thickness needs to be adjusted. During adjustment, the electrode needs to be marked longitudinally, and the extension amounts of the material area and the empty foil area in the longitudinal direction need to be measured separately until the extension amount of the material area is less than or equal to the extension amount of the empty foil area. The process requires multiple adjustments to the thickness of the adjustment layer, and the method of calculating the longitudinal extension is quite cumbersome. In addition, the existing technology only considers the longitudinal extension, and the wrinkling phenomenon caused by the transverse extension of the material area squeezing the empty foil area has not been improved.

[0003] Therefore, there is an urgent need to design a stretching method, a stretching device, and a production line to solve the above problems. Summary of the Invention

[0004] The first objective of this invention is to provide a stretching method that can intuitively, conveniently and quickly confirm the thickness of the adjustment layer, and subsequent debugging does not require changing the thickness of the adjustment layer. This method improves the wrinkling phenomenon caused by the lateral extension of the material area squeezing the empty foil area, as well as the wrinkling or even breakage phenomenon caused by the longitudinal extension of the empty foil area being much smaller than the longitudinal extension of the material area (so the tension on the empty foil area is greater than that on the material area).

[0005] The second objective of this invention is to provide a stretching device that eliminates the need to adjust the thickness of the adjustment layer in the early stage of electrode stretching, thereby saving time and improving efficiency.

[0006] The third objective of this invention is to provide a production line that can reduce setup time and accommodate the stretching of electrodes with wider widths.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] The stretching method involves an electrode sheet to be stretched comprising a material area and two empty foil areas located within the material area. The empty foil areas of the electrode sheet are stretched at a tension roller. The stretching method includes:

[0009] S10: Confirm the extension amount w of the above material area in the width direction;

[0010] S20: An adjustment layer is wrapped around the tension roller and is provided corresponding to the two empty foil areas. The thickness of the adjustment layer is h, where h = w / 2.

[0011] S30: After adjusting the tension F of the tension roller, the electrode sheet is stretched.

[0012] As an alternative, w = w1 - w2, where w1 is the initial width of the material zone and w2 is the width of the material zone after stretching; or

[0013] w = w1 * θ, where w1 is the initial width of the material zone and θ is the elongation of the material zone.

[0014] As an alternative, the adjustment layer consists of only N layers of adhesive tape, each layer of which has a thickness of n, where N = [h / n] + 1, and [h / n] is an integer representation of h / n.

[0015] As an alternative, the aforementioned adjustment layer includes an adjustable layer and an adhesive layer. The adjustable layer surrounds the aforementioned tension roller. The thickness of the adjustable layer is a. The adhesive layer includes M layers of adhesive, each layer of adhesive having a thickness of m, where M = [(ha) / m] + 1, and [(ha) / m] is an integer representing (ha) / m.

[0016] As an alternative, F ≤ F1 * 0.8, where F1 is the tensile strength of the empty foil region.

[0017] As an optional solution, the above stretching method also includes S09, which is a step before S10. S09 is to pull the electrode sheet to be stretched to the tension roller to the winding point to ensure that the electrode sheet completes the correction and alignment.

[0018] The stretching device stretches the electrode sheet using the stretching method described above. The stretching device includes an adjustment layer and a tension roller. The adjustment layer is wrapped around the tension roller and is provided corresponding to the two empty foil areas.

[0019] As an optional solution, the aforementioned adjustment layer includes:

[0020] An adjustable layer is sleeved on the outer periphery of the tension roller, and the position of the adjustable layer relative to the axial direction of the tension roller is adjustable;

[0021] An adhesive tape layer is disposed around the outer periphery of the adjustable layer, and the adhesive tape layer is tightly abutted against the empty foil area.

[0022] As an optional solution, the aforementioned adjustable layer includes:

[0023] A clamp is fitted onto the tension roller, and locking protrusions are provided at both ends of the clamp;

[0024] The locking component has two locking protrusions that are threaded into the nut.

[0025] The production line includes the aforementioned stretching device.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention provides a stretching method. In the extension direction, the radius of the tension roller is set to r. The calculation is based on one revolution of the tension roller. For the material area, the elongation rate is set to θ. Due to the stretching effect of the adjustment layer, the length of one revolution of the empty foil area is 2π(r+h). The original length of the empty foil area is 2πr, so the elongation of the empty foil area in the extension direction is 2πh, and the elongation rate is h / r. Therefore, it is necessary to ensure that h / r ≥ θ. However, h = w1*θ / 2, i.e., (w1*θ) / 2r ≥ θ, then w1 ≥ 2r. This is problematic for existing material area widths and tension roller diameters. This invention satisfies the requirements. In summary, the present invention provides the thickness of the adjustment layer through intuitive data measured in the width direction, eliminating the need for the cumbersome steps of marking and measuring on the electrode sheet. It also ensures that the elongation rate of the empty foil area is greater than or equal to the elongation rate of the material area in the length direction. Then, the tension of the tension roller is adjusted to stretch the foil, thereby ensuring that the tension on the empty foil area in the length direction is less than the tension on the material area during subsequent roller passes (when no adjustment layer is set). This makes it easier for the empty foil area to flatten and offset the force generated by the transverse compression of the foil material in the material area. By addressing the issue from two directions, the risk of wrinkles or even breakage in the empty foil area is reduced more comprehensively.

[0028] The present invention also provides a stretching device. By adopting the above-described stretching method, it is not necessary to adjust the thickness of the adjustment layer in the early stage of electrode stretching, which saves time and improves efficiency.

[0029] The present invention also provides a production line that, by employing the above-mentioned stretching device, can reduce debugging time and accommodate the stretching of electrode sheets with wider widths. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method provided in the embodiments of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the electrode sheet and stretching device provided in the embodiment of the present invention. Figure 1 ;

[0032] Figure 3 This is a schematic diagram of the changes in the material distribution area during electrode stretching provided in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the electrode stretching reflecting the change of the empty foil region provided in the embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the structure of the electrode sheet and stretching device provided in the embodiment of the present invention. Figure 2 .

[0035] In the picture:

[0036] 10. Electrode; 11. Material area; 12. Empty foil area;

[0037] 20. Tension roller;

[0038] 30. Adjustable layer; 31. Adjustable layer; 311. Clamp; 3111. Locking protrusion; 312. Locking element; 32. Adhesive paper layer. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0040] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0043] like Figure 2 The diagram shows the electrode 10 on the tension roller 20. The material area 11 of the electrode 10 is set away from the tension roller 20. For ease of explanation, the extension direction of the electrode 10, which is also the coating direction, is the X direction in the diagram. In reality, the extension direction of the electrode 10 coincides with part of the circumference of the tension roller 20, and the width direction of the electrode 10, which is also the axial extension direction of the tension roller 20, is the Y direction. As coating progresses, empty foil areas 12 are formed on both sides of the material area 11. During stretching, it is necessary to ensure that the elongation of the empty foil area 12 is greater than or equal to the elongation of the material area 11. Usually, an adjustment layer 30 is added to the tension roller 20 to balance the elongation difference between the material area 11 and the empty foil area 12. However, there is currently no clear and quantitative method for confirming the thickness of the adjustment layer 30. After the adjustment layer 30 is set, its thickness needs to be adjusted and changed. During the adjustment process, the electrode 10 needs to be marked in the longitudinal direction, and the elongation of the material area 11 and the empty foil area 12 in the longitudinal direction needs to be measured separately until the elongation of the material area 11 is less than or equal to the elongation of the empty foil area 12. This process requires multiple adjustments to the thickness of the adjustment layer 30, and the method of calculating the elongation in the longitudinal direction is relatively cumbersome. At the same time, the existing technology only considers the longitudinal elongation, and the wrinkling phenomenon caused by the transverse elongation of the material area compressing the empty foil area is not improved.

[0044] To address the aforementioned issues, this embodiment provides a stretching method that allows for intuitive, convenient, and quick confirmation of the thickness of the adjustment layer 30. Subsequent adjustments do not require changing the thickness of the adjustment layer 30. Furthermore, it simultaneously improves the wrinkling phenomenon caused by the lateral extension of the material area 11 compressing the empty foil area 12, and the wrinkling or even breakage phenomenon caused by the longitudinal extension of the empty foil area 12 being much smaller than the longitudinal extension of the material area 11 (resulting in greater tension on the empty foil area compared to the material area). Figure 1 and Figure 3 ( Figure 3 The dashed line represents the stretched material area 11) and Figure 4 As shown, the stretching methods include:

[0045] S10: Confirm the extension amount w of material area 11 in the width direction (not marked, actually w2-w1 in the figure);

[0046] S20: The adjustment layer 30 is wrapped around the tension roller 20 and is set corresponding to the two empty foil areas 12. The thickness of the adjustment layer 30 is h, where h = w / 2.

[0047] S30: After adjusting the tension F of the tension roller 20, the electrode 10 is stretched.

[0048] The above settings ensure that, in the stretching direction, the elongation rate of the empty foil area 12 is greater than that of the material area 11 (the ratio of the elongation to the original length). In the extension direction, the radius of the tension roller 20 is set to r. Calculations are performed based on one revolution of the tension roller 20. For the material area 11, the elongation rate is set to θ. Due to the stretching effect of the adjustment layer 30, the length of one revolution of the empty foil area 12 is 2π(r+h). The original length of the empty foil area 12 is 2πr, so the elongation of the empty foil area 12 in the extension direction is 2πh, and the elongation rate is h / r. Therefore, it is sufficient to ensure that h / r ≥ θ. However, h = w1*θ / 2, which means (w1*θ) / 2r ≥ θ, w1 ≥ 2r. This is problematic for the existing width of the material area 11 and the tension roller 20. For the diameter of 0, all requirements can be met; in summary, this embodiment provides the thickness of the adjustment layer 30 through intuitive data measured in the width direction, eliminating the need for the cumbersome step of marking and measuring on the electrode 10, and ensuring that the elongation rate of the empty foil area 12 is greater than or equal to the elongation rate of the material area 11 in the length direction. This ensures that the tension on the empty foil area 12 in the length direction during subsequent roll passing (without setting the adjustment layer during subsequent roll passing) is less than the tension on the material area 11, making the empty foil area 12 easier to flatten in order to offset the force generated by the transverse extrusion of the foil by the material area 11, and more comprehensively reducing the risk of wrinkling and breakage of the empty foil area 12.

[0049] It is understandable that after being stretched by the tension roller 20 with the adjustment layer 30 in the length direction, the length of the empty foil area 12 is longer than the length of the material area 11. At this time, the empty foil area 12 is in a relatively relaxed state. In the subsequent roller passing process, there is a certain amount of margin for the extension of the material area 11 in both the length and width directions, so as to avoid cracking or wrinkling of the empty foil area 12 due to stretching in the length and width directions.

[0050] Preferably, F ≤ F1 * 0.8, where F1 is the tensile strength of the empty foil area 12. After the above settings are made, normal stretching operations can be performed, and the tensile breakage of the empty foil area 12 can be avoided. This makes the adjustment speed before stretching the electrode 10 faster and reduces the occurrence of wrinkling or even breakage of the empty foil area 12.

[0051] Optionally, such as Figure 1As shown, the stretching method also includes step S09, which precedes S10. S09 involves pulling the electrode sheet 10 to be stretched to the tension roller 20 at the winding point to ensure that the electrode sheet 10 completes the correction and alignment. It should be noted that when the elongation of the material area 11 is unknown, after stretching a certain distance, w2 needs to be measured to obtain the value of w2-w1 to get w. If θ is known, then w=w1*θ, and the electrode sheet 10 can be adjusted until it is aligned.

[0052] In an optional embodiment, the adjustment layer 30 comprises only N layers of adhesive tape, each layer having a thickness of n, where N = [h / n] + 1, and [h / n] is an integer representation of h / n. It is understood that the tension roller 20 is only wrapped with adhesive tape, the thickness of which is known. The required number of adhesive tape layers can be calculated based on the thickness of the aforementioned adjustment layer 30. If there is a decimal that cannot be divided evenly, such as 3.68, round it down to 3 and add one to get four layers.

[0053] This embodiment also provides a stretching device, which uses the above-described stretching method to stretch the electrode 10, such as... Figure 2 As shown, the stretching device includes an adjusting layer 30 and a tension roller 20. The adjusting layer 30 wraps around the tension roller 20 and is positioned corresponding to the two empty foil areas 12. The above-described stretching device eliminates the need to adjust the thickness of the adjusting layer 30 during the initial stretching phase of the electrode 10, saving time and improving efficiency.

[0054] Preferably, the adjustable layer 31 is sleeved around the outer periphery of the tension roller 20, and the position of the adjustable layer 31 relative to the axial direction of the tension roller 20 is adjustable; the adhesive layer 32 surrounds the outer periphery of the adjustable layer 31, and the adhesive layer 32 is tightly abutted against the empty foil area 12. This arrangement allows the axial position of the adhesive layer 32 to be adjusted within the tension roller 20, avoiding the possibility of damaging the empty foil area 12 by tearing off the adhesive layer 32, thus preventing material waste; simultaneously, it allows the stretching device to accommodate the stretching of electrode sheets 10 with greater widths.

[0055] In this embodiment, the thickness of the adjustable layer 31 is 'a', and the adhesive layer 32 includes M layers of adhesive tape, each with a thickness of 'm', where M = [(ha) / m] + 1, and [(ha) / m] is the integer part of (ha) / m. If there is a decimal that cannot be divided evenly, such as 3.68, take 3 and add one to get four layers. The adhesive tape can be, but is not limited to, Teflon material. If the thickness of the adjustable layer 31, a, is greater than or equal to h, then the adhesive layer 32 is not required.

[0056] Optionally, the adjustable layer 31 includes a clamp 311 and a locking member 312. The clamp 311 is sleeved on the tension roller 20, and locking protrusions 3111 protrude from both ends of the clamp 311. The locking member 312 passes through two locking protrusions 3111 and is threadedly connected to a nut. With the above arrangement, by appropriately loosening the nut and locking member 312, the clamping force of the clamp 311 decreases, and the position of the adjustable layer 30 can be adjusted. After locking the nut and locking member 312, the nut abuts against one of the locking protrusions 3111, ensuring that the clamp 311 clamps the tension roller 20, and the position of the adjustable layer 30 is fixed. It should be noted that the adhesive layer 32 has a slight elasticity, allowing the clamp 311 to switch between clamping and loosening states.

[0057] The materials used for clamp 311 include, but are not limited to, stainless steel, plastic, and Teflon.

[0058] In other words, after determining the number of layers of adhesive tape, the adhesive tape can be wrapped around the clamp 311 first, then the clamp 311 can be moved to insert the adhesive tape into the lower part of the empty foil area 12, and then the nut can be tightened to fix it, without removing the electrode 10 or damaging the empty foil area 12.

[0059] This embodiment also provides a production line including the stretching device described above. By using the stretching device, the debugging time can be reduced, and it can accommodate the stretching of electrode sheets 10 with wider widths.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A stretching method, wherein the electrode sheet (10) to be stretched includes a material area (11) and two empty foil areas (12) located in the material area (11), the empty foil areas (12) of the electrode sheet (10) are stretched at a tension roller (20), characterized in that, Stretching methods include: S10: Confirm the extension amount w of the material area (11) in the width direction; S20: The adjustment layer (30) is wrapped around the tension roller (20) and is set corresponding to the two empty foil areas (12). The thickness of the adjustment layer (30) is h, where h = w / 2. S30: After adjusting the tension F of the tension roller (20), the electrode (10) is stretched.

2. The stretching method according to claim 1, characterized in that, w = w1 - w2, where w1 is the initial width of the material area (11) and w2 is the width of the material area (11) after stretching; or w = w1 * θ, where w1 is the initial width of the material area (11) and θ is the elongation of the material area (11).

3. The stretching method according to claim 1, characterized in that, The adjustment layer (30) consists of only N layers of adhesive paper, each layer of which has a thickness of n, where N = [h / n] + 1, and [h / n] is an integer representing h / n.

4. The stretching method according to claim 1, characterized in that, The adjustment layer (30) includes an adjustable layer (31) and an adhesive layer (32). The adjustable layer (31) surrounds the tension roller (20). The thickness of the adjustable layer (31) is a. The adhesive layer (32) includes M layers of adhesive, each layer of adhesive having a thickness of m, where M = [(ha) / m] + 1, and [(ha) / m] is an integer representing (ha) / m.

5. The stretching method according to any one of claims 1-4, characterized in that, The value is F≤F1*0.8, where F1 is the tensile strength of the empty foil region (12).

6. The stretching method according to claim 5, characterized in that, The stretching method further includes S09, which is located one step before S10. S09 is to pull the electrode sheet (10) to be stretched to the tension roller (20) to the winding point to ensure that the electrode sheet (10) completes the correction and alignment.

7. A tensioning device, characterized in that, The electrode sheet (10) is stretched using the stretching method as described in claim 5 or 6. The stretching device includes an adjustment layer (30) and a tension roller (20). The adjustment layer (30) is wrapped around the tension roller (20) and is disposed corresponding to the two empty foil areas (12).

8. The stretching device according to claim 7, characterized in that, The adjustment layer (30) includes: An adjustable layer (31) is sleeved on the outer periphery of the tension roller (20), and the position of the adjustable layer (31) relative to the axial direction of the tension roller (20) is adjustable; An adhesive tape layer (32) is disposed around the outer periphery of the adjustable layer (31), and the adhesive tape layer (32) is abutted against the empty foil area (12).

9. The stretching device according to claim 8, characterized in that, The adjustable layer (31) includes: A clamp (311) is fitted onto the tension roller (20), and the clamp (311) has locking protrusions (3111) at both ends; The locking member (312) has two locking protrusions (3111) threaded through it and connected to the nut by threads.

10. A production line, characterized in that, Includes the tensioning device as described in any one of claims 7-9.

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