A method for manufacturing high-precision air-cooled lithium battery aluminum pipe and high-precision air-cooled lithium battery aluminum pipe

Abstract

The application discloses a method for manufacturing high-precision air-cooled aluminum pipe of lithium battery and the high-precision air-cooled aluminum pipe of lithium battery. The air-cooled aluminum pipe comprises a flat long-circular air passage surrounded by a pipe wall, and a plurality of circular-arc support diameters are arranged in the long-circular air passage, which separates the long-circular air passage into a plurality of air cavities. The air-cooled aluminum pipe can be coiled by a coiling machine arranged at the tail of the extruding machine slide-out table while being extruded, and then is subjected to finish rolling. Since the precision of hot working is low, only ±0.15 mm can be reached, and the precision of cold working is high, so that the thickness tolerance of the air-cooled aluminum pipe after finish rolling can reach within ±0.05 mm, and the flatness of the outer surface can reach within 0.05 mm.

Description

Technical Field

[0001] This invention relates to the field of lithium battery cooling technology, specifically to a method for manufacturing a high-precision lithium battery air-cooled aluminum tube and the high-precision lithium battery air-cooled aluminum tube. Background Technology

[0002] A lithium battery module typically consists of a frame and multiple battery cells, which are stacked side-by-side within the frame along their thickness. To dissipate the significant heat generated during rapid charging and high-power discharging, a cooling pipe is placed between every two cells. To allow the cooling pipe to be compressed and its thickness reduced when the lithium battery expands due to heat, it is usually designed with an angled diameter. Figure 1 As shown, the existing air-cooled aluminum tube 10 includes a flat elongated oval ventilation channel. Several inclined diameters 11, which are inclined from top to bottom and from bottom to top, are interspersed in the elongated oval ventilation channel. A small triangular ventilation channel 101 is formed between two adjacent inclined diameters 11. A support diameter 12 is provided at the bottom center of the triangular ventilation channel 101.

[0003] However, traditional air-cooled tubing has the following two fatal flaws: 1. Each lithium battery module typically consists of 8 battery cells and 7 stacked air-cooling tubes. Each air-cooling tube has a thickness tolerance, and when these tolerances accumulate, the total error increases by a factor of 7. For example, the thickness tolerance of all currently hot-extruded air-cooling tubes is generally ±0.20 mm, with the strictest being ±0.15 mm. When the thickness tolerance is ±0.15 mm, the total error of the seven air-cooling tubes will reach ±1.05 mm, with an error range of 2.10 mm. Such a large error can lead to the lithium battery module being either too loose or too tight during assembly. Too loose, and the tooling cannot be tightened; too tight, and it cannot be installed in the tooling.

[0004] Second, because the air-cooled tube has an slanted diameter, the maximum distance between two adjacent slanted diameters will reach more than 30 mm. Therefore, after hot extrusion, the surface unevenness of the entire air-cooled tube will reach more than 0.5 mm. This will result in the contact area between the air-cooled tube and the lithium battery not reaching 100%, and may even be less than 60%. Furthermore, such a high surface unevenness cannot be eliminated by precision rolling. Existing air-cooled tubes cannot be coiled or precision rolled because the unsupported portion of the tube wall of the slanted diameter air-cooled tube is too wide, exceeding 30 mm as mentioned above. During coiling, this portion of the tube wall will concave inward, exacerbating the surface unevenness of the entire air-cooled tube. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a high-precision lithium battery air-cooled aluminum tube and its manufacturing method.

[0006] The technical solution adopted in this invention is: A method for manufacturing high-precision lithium battery air-cooled aluminum tubes includes the following steps: (1) Extrusion molding of air-cooled aluminum tubes is obtained by hot extrusion using an extruder; The hot-extruded air-cooled aluminum tube includes a flat, elongated oval ventilation channel surrounded by the tube wall. The elongated oval ventilation channel is provided with several arc-shaped support diameters, which divide the elongated oval ventilation channel into several ventilation chambers. (2) While extruding, the extruded air-cooled aluminum tube is coiled up using a coiling machine; (3) The coiled air-cooled aluminum tube is sent to the rolling mill for precision rolling to obtain high-precision lithium battery air-cooled aluminum tube.

[0007] Furthermore, the plurality of arc-shaped support diameters are evenly distributed in the elongated oval ventilation duct with their opening ends facing away from each other, dividing the elongated oval ventilation duct into a plurality of first ventilation cavities with equal cross-sections and a plurality of second ventilation cavities with equal cross-sections. The first ventilation cavities and the second ventilation cavities are alternately arranged along the height direction of the lithium battery air-cooled aluminum tube; the cross-sectional shape of the first ventilation cavity is elongated oval.

[0008] The above design scheme can make the air-cooled aluminum tube structure symmetrical, and the two side walls deform evenly after being stressed, always sticking to the surface of the battery cell to ensure the cooling effect; and the cross-sectional area of ​​the air tube is not increased at all compared with the existing technology, and the weight per meter of the air-cooled tube is not increased at all, and no cost is increased.

[0009] Furthermore, the arc of the arc-shaped support diameter is equal to the arc of the arc-shaped walls at both ends of the elongated oval ventilation duct, and its thickness is equal to the wall thickness of the high-precision lithium battery air-cooled aluminum tube.

[0010] By adopting the above design scheme, the deformation of the entire aluminum tube can be uniform, which allows it to better fit with the surface of the lithium battery and ensure the cooling effect.

[0011] Furthermore, the radius of the arc-shaped support diameter is not less than 0.3 mm. If the radius of the arc is too small, it will produce large bending deformation under stress, resulting in insufficient support strength.

[0012] Furthermore, the wall thickness of the lithium battery air-cooled aluminum tube is 0.7–0.9 mm. If the wall thickness is too thick, the heat exchange effect is poor; if the wall thickness is too thin, the tube strength is poor.

[0013] Furthermore, the maximum height of the first ventilation cavity is 14-16 mm, and the minimum height of the second ventilation cavity is 9-11 mm. This allows the maximum width of the pipe wall without support diameter to be controlled at around 10 mm. During extrusion, the extruded air-cooled pipe can be coiled up and then precision rolled.

[0014] Furthermore, the thickness tolerance of the extruded air-cooled aluminum tube is within ±0.15 mm, and the thickness tolerance of the precision-rolled air-cooled aluminum tube is within ±0.05 mm. This allows for 100% adhesion between the air-cooled aluminum tube and the lithium battery surface.

[0015] The high-precision lithium battery air-cooled aluminum tube is obtained according to any of the above methods for manufacturing high-precision lithium battery air-cooled aluminum tubes.

[0016] The beneficial effects of this invention are: 1. Compared to existing oblique-diameter air-cooled aluminum tube technology, the maximum distance between the arc-shaped support diameters of the air-cooled aluminum tube in this application is reduced from over 30 mm to approximately 10 mm. Therefore, during hot extrusion, a coiling machine can be installed at the tail end of the extrusion press slide to coil the extruded air-cooled tube for precision rolling. Hot working has low precision, reaching only ±0.15 mm, while cold working has high precision. After precision rolling, the thickness tolerance of the air-cooled aluminum tube can reach within ±0.05 mm, and the flatness of the outer surface can reach within 0.05 mm. With such tolerances, the cumulative error during module assembly is only ±0.35 mm, three times lower than that of oblique-diameter tubes, thus reducing the difficulty of assembly.

[0017] 2. Existing inclined diameter air-cooled aluminum tubes have very weak support strength. To prevent excessive deformation of the air-cooled aluminum tube due to the excessive expansion force of the lithium battery, which could lead to plastic deformation, a support diameter is needed in the middle of the inclined diameter to prevent excessive deformation. This application changes the inclined diameter to a circular arc diameter, greatly increasing the support strength; therefore, the support diameter is no longer needed. Because the inclined diameter is longer and the circular arc diameter is shorter, and the support diameter is eliminated, although the number of diameters increases from 8 to 14, the cross-sectional area remains unchanged, and the weight per meter of the air-cooled tube is not increased at all, thus not increasing any cost. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the cross-sectional structure of an existing lithium battery air-cooled aluminum tube.

[0019] Figure 2 This is a schematic diagram of the cross-sectional structure of the air-cooled aluminum tube obtained by hot extrusion according to the present invention.

[0020] Figure 3This is a process flow diagram of the manufacturing process of high-precision lithium battery air-cooled aluminum tubes according to the present invention. Detailed Implementation

[0021] The present invention will be further illustrated below with specific examples to facilitate understanding of the invention, but this does not limit the invention.

[0022] See Figure 3 A method for manufacturing high-precision lithium battery air-cooled aluminum tubes includes the following steps: (1) Extrusion molding of air-cooled aluminum tubes is obtained by hot extrusion using an extruder; (2) A coiling machine is set at the tail end of the extrusion press slide table. While extruding, the extruded air-cooled aluminum tube is coiled up by the coiling machine. (3) The coiled air-cooled aluminum tube is sent to the rolling mill for precision rolling to obtain high-precision lithium battery air-cooled aluminum tube.

[0023] Because hot working has low precision, it can only reach ±0.15 mm, while cold working has high precision. After precision rolling, the thickness tolerance of the air-cooled aluminum tube can reach within ±0.05 mm, and the flatness of the outer surface can reach within 0.05 mm.

[0024] See Figure 2 The hot-extruded air-cooled aluminum tube 20 of the present invention includes a flat elongated oval ventilation channel surrounded by a tube wall 21. The elongated oval ventilation channel is provided with a plurality of arc-shaped support diameters A22 and B23 with the same structure and opposite opening directions. The opening ends of the arc-shaped support diameters A22 and B23 are evenly distributed in the elongated oval ventilation channel, and the elongated oval ventilation channel is divided into a plurality of first ventilation cavities 201 with equal cross-sections and a plurality of second ventilation cavities 202 with equal cross-sections. The first ventilation cavities 201 and the second ventilation cavities 202 are alternately arranged along the height direction of the lithium battery air-cooled aluminum tube.

[0025] The inner cavity of the air-cooled aluminum tube forms a flat, elongated oval ventilation channel, which facilitates the contact between the air-cooled aluminum tube and the surface of the battery cell and conducts heat for cooling. In actual use, the front and back sides of the air-cooled aluminum tube, i.e., the two sidewalls of the elongated oval ventilation channel, are in contact with and cover the surfaces of the left and right battery cells. Cold air enters from one end of the aluminum tube, passes through the elongated oval ventilation channel, exchanges heat with the battery cell, and then exits from the other end of the aluminum tube, cooling the battery cell. The expansion force generated by the heat generated by the battery cell is transferred from the sidewall 21 of the elongated oval ventilation channel to the arc-shaped support diameters A22 and B23. The arc-shaped support diameters bend and deform to absorb the expansion force of the battery cell, protecting the battery cell. The arc-shaped support diameters divide the elongated oval ventilation channel into several first and second ventilation chambers with equal cross-sections. The first and second ventilation chambers are alternately arranged along the height direction of the lithium battery air-cooled aluminum tube, which makes the air-cooled aluminum tube structure symmetrical. After being stressed, the two sidewalls deform evenly, always contacting the surface of the battery cell, ensuring the cooling effect.

[0026] In this embodiment, taking a wind-cooled aluminum tube 20 with a height of 197 mm and a width (i.e., thickness) of 8 mm as an example, with its width, height, and shape being completely identical, the original slant diameter (see...) is... Figure 1 The design was changed to use 14 arc-shaped diameters, specifically 8 oblique diameters (A22 and B23), and the central half-length support diameter of the oblique diameters was removed. These 14 arc-shaped diameters divide the elongated oval ventilation duct into 8 alternating first ventilation chambers 201 and 7 second ventilation chambers 202. The first ventilation chambers 201 are elongated oval, with the two first ventilation chambers located at either end of the air-cooled aluminum tube enclosed by the arc-shaped support diameters B23 and the tube wall.

[0027] The arc of the arc-shaped support diameter is equal to the arc of the arc-shaped walls 211 at both ends of the elongated oval ventilation duct, and its thickness is equal to the thickness of the tube wall 21 of the lithium battery air-cooled aluminum tube. That is, in this embodiment, the arc-shaped support diameter is a semicircle with an outer diameter of 8 mm, and the thickness of both the tube wall 21 and the arc-shaped support diameter is 0.7 mm. The maximum height of the first ventilation cavity 201 is 15 mm, and the minimum height of the second ventilation cavity 202 is 9.4 mm, so that the maximum width of the part of the tube wall 21 without the support diameter is about 12 mm.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also within the protection scope of the present invention.

Claims

1. A method for manufacturing high-precision air-cooled aluminum tubes for lithium batteries, characterized in that, Includes the following steps: (1) Extrusion molding of air-cooled aluminum tubes is obtained by hot extrusion using an extruder; The hot-extruded air-cooled aluminum tube includes a flat, elongated oval ventilation channel surrounded by the tube wall. The elongated oval ventilation channel is provided with several arc-shaped support diameters, which divide the elongated oval ventilation channel into several ventilation chambers. (2) While extruding, the extruded air-cooled aluminum tube is coiled up using a coiling machine; (3) The coiled air-cooled aluminum tube is sent to the rolling mill for precision rolling to obtain high-precision lithium battery air-cooled aluminum tube; The several arc-shaped support diameters are evenly distributed in pairs with their opening ends facing away from each other within the elongated oval ventilation duct, dividing the elongated oval ventilation duct into several first ventilation cavities and several second ventilation cavities with equal cross-sections. The first ventilation cavities and second ventilation cavities are alternately arranged along the height direction of the lithium battery air-cooled aluminum tube; the cross-sectional shape of the first ventilation cavity is elongated oval.

2. The method for manufacturing a high-precision lithium battery air-cooled aluminum tube according to claim 1, characterized in that, The arc of the circular support diameter is equal to the arc of the arc walls at both ends of the elongated oval ventilation duct, and its thickness is equal to the wall thickness of the high-precision lithium battery air-cooled aluminum tube.

3. The method for manufacturing a high-precision lithium battery air-cooled aluminum tube according to claim 1, characterized in that, The radius of the arc-shaped support diameter is not less than 0.3 mm.

4. The method for manufacturing a high-precision lithium battery air-cooled aluminum tube according to claim 3, characterized in that, The wall thickness of the high-precision lithium battery air-cooled aluminum tube is 0.7 to 0.9 mm.

5. The method for manufacturing a high-precision lithium battery air-cooled aluminum tube according to claim 4, characterized in that, The maximum height of the first ventilation cavity is 14-16 mm, and the minimum height of the second ventilation cavity is 9-11 mm.

6. The method for manufacturing a high-precision lithium battery air-cooled aluminum tube according to claim 1, characterized in that, The thickness tolerance of extruded air-cooled aluminum tubes is within ±0.15 mm, and the thickness tolerance of precision-rolled air-cooled aluminum tubes is within ±0.05 mm.

7. The high-precision lithium battery air-cooled aluminum tube obtained by the method according to any one of claims 1 to 6.

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