A method of manufacturing a battery pack housing

Abstract

The application relates to a preparation method of a battery pack shell and belongs to the technical field of composite materials; the method comprises the following steps: cutting a fiber matrix, then connecting a reinforcing sheet to the fiber matrix to obtain a reinforcing matrix; adopting a clamping piece mechanism to tensionally fix the reinforcing matrix; attaching a thermosetting resin to the reinforcing matrix; installing the clamping piece mechanism with the reinforcing matrix fixed thereto in a mold; and performing mold pressing forming on the reinforcing matrix with the thermosetting resin attached thereto to obtain the battery pack shell; wherein the reinforcing sheet is connected to the fiber matrix through a fixing piece, and the melting point of the fixing piece is not higher than the heat preservation and pressure maintaining temperature of the mold pressing forming; the fixing piece with a melting point lower than the heat preservation and pressure maintaining temperature of the mold pressing forming is adopted to realize the connection of the reinforcing sheet and the fiber matrix; in the mold pressing forming process, the fixing piece will melt, and the molten fixing piece will not generate pulling force or other force on the reinforcing sheet and the fiber matrix, so that the probability of the reinforcing sheet or the fiber matrix being pulled and cracked is effectively reduced, and the probability of fiber fracture is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, in particular to a preparation method of a battery pack shell. BACKGROUND

[0002] The power battery pack is the core energy equipment with the largest mass (≥30%) and the highest cost (40%-60%) in the new energy vehicle, and needs to be continuously lightened to improve the power performance and endurance of the vehicle. However, the primary core problem of the power battery pack is still the vehicle thermal runaway protection and personal safety problem. With the rapid development of new energy vehicles and the increasing market share, safety accidents such as new energy vehicle battery spontaneous combustion and collision fire occur frequently, which causes the public's concern about the safety of new energy vehicles. At the same time, under the current situation of slow development of power battery cell technology, effectively realizing the weight reduction of the power battery pack shell has become the focus of new energy vehicle lightweight.

[0003] The application of fiber composite materials, especially continuous fiber composite materials, in power battery shells has attracted attention at home and abroad. Compared with aluminum structures, fiber composite materials have a weight reduction of more than 40%, and also have the advantages of strong designability, good dimensional stability, corrosion resistance, wear resistance, shock absorption, etc., and have significant advantages in the application of power battery shells. However, at present, continuous fiber reinforced resin matrix composite materials in the automotive field have the problems of fiber breakage, wrinkling and other obvious defects due to the small breaking strain of the fiber and the difficulty in breaking through the forming technology of complex structures. Some people have proposed using reinforcing sheets to improve the defects, but even after using reinforcing sheets to improve, the probability of fiber breakage is still high. SUMMARY

[0004] The present application provides a preparation method of a battery pack shell, which can further improve the probability of fiber breakage.

[0005] The present application provides a preparation method of a battery pack shell, which can further improve the probability of fiber breakage.

[0006] Obtaining a fiber matrix;

[0007] Cutting the fiber matrix at a predetermined position to form a cutting area on the fiber matrix, and then connecting a reinforcing sheet to the fiber matrix to cover the cutting area to obtain a reinforcing matrix;

[0008] Tensioning and fixing the reinforcing matrix by using a clamping piece mechanism;

[0009] Attaching a thermosetting resin to the reinforcing matrix;

[0010] Installing the clamping piece mechanism with the fixed reinforcing matrix in a mold to realize the transfer of the reinforcing matrix with the attached thermosetting resin into the mold;

[0011] The reinforcing substrate with the thermosetting resin attached is subjected to mold pressing to obtain the battery pack shell;

[0012] The reinforcing sheet is connected to the fiber substrate by the fixing member, and the melting point of the fixing member is not higher than the holding temperature of the mold pressing.

[0013] In the above implementation process, the fixing member with a melting point lower than the holding temperature of the mold pressing is used to connect the reinforcing sheet and the fiber substrate. During the mold pressing process, the fixing member melts, and the melted fixing member does not exert pulling force on the reinforcing sheet and the fiber substrate, effectively reducing the probability of the reinforcing sheet or the fiber substrate being pulled apart, and further improving the probability of fiber breakage.

[0014] As an optional implementation, the fixing member includes a thermoplastic fixing nail.

[0015] In the above implementation process, the thermoplastic fixing nail can quickly and effectively connect the reinforcing sheet and the fiber substrate. At the same time, the use of the entire thermoplastic fixing nail is less, which can reduce its influence on the performance of the entire battery pack shell.

[0016] As an optional implementation, the width of the overlapping area of the reinforcing sheet and the fiber substrate is not less than 20 mm.

[0017] In the above implementation process, during the mold pressing process, the mold will exert pressure on the reinforcing substrate, which will cause the reinforcing sheet and the fiber substrate to move relatively. To reduce the displacement of the reinforcing sheet and the fiber substrate, the overlapping area of the reinforcing sheet and the fiber substrate needs to have a certain width, and the width of not less than 20 mm can greatly reduce the occurrence of the gap.

[0018] As an optional implementation, the reinforcing sheet includes a glass fiber fabric, and the glass fibers in the glass fiber fabric are orthogonally distributed.

[0019] In the above implementation process, the orthogonally distributed glass fibers in the reinforcing sheet can produce a better reinforcing effect.

[0020] As an optional implementation, the fiber substrate includes a short-cut fiber felt and a continuous fiber cloth arranged in layers.

[0021] As an optional implementation, the preset position of the fiber substrate is determined according to simulation software simulation; and / or

[0022] The simulation software includes Fibersim.

[0023] In the above implementation process, the complex deformation area of the battery pack shell prone to fiber breakage, wrinkles and other defects can be determined in advance by three-dimensional simulation software during design.

[0024] As an optional implementation, the clamping mechanism comprises a first clamping piece and a second clamping piece; the first clamping piece and / or the second clamping piece is provided with a limiting pin; the first clamping piece is provided with a pressure pad ball mechanism, the pressure pad ball mechanism comprises a pressure pad ball body and a mounting seat, the mounting seat is connected to the first clamping piece, and the pressure pad ball body is rotatably mounted on the mounting seat.

[0025] As an optional implementation, the thermosetting resin comprises polyurethane.

[0026] In the above implementation process, the polyurethane has excellent flame retardant performance, and when it is applied to the battery pack shell, the thermal runaway protection capability of the battery pack can be improved.

[0027] As an optional implementation, a silica gel layer is laid in the mold; and / or

[0028] The thickness of the silica gel layer is 0.2-2mm.

[0029] In the above implementation process, the setting of the silica gel layer is conducive to improving the forming capability of the reinforcing matrix in the mold, and at the same time is conducive to improving the surface quality of the finally prepared battery pack shell.

[0030] As an optional implementation, the way of attaching the thermosetting resin to the reinforcing matrix comprises spraying; and / or

[0031] The mold pressing is performed in a vacuum-assisted progressive mold pressing manner; and / or

[0032] The holding pressure temperature of the holding and pressure maintaining is 100-140℃; and / or

[0033] The time of the holding and pressure maintaining is 200-400s.

[0034] In the above implementation process, the thermosetting resin is attached to the reinforcing matrix in the form of spraying, and the mold pressing is performed in a vacuum-assisted progressive mold pressing manner, which can effectively improve the infiltration of the thermosetting resin to the reinforcing matrix, and in turn reduce the probability of defects of the battery pack shell. BRIEF DESCRIPTION OF DRAWINGS

[0035] The drawings incorporated into the specification and constituting a part of the specification, show embodiments consistent with the present application, and together with the specification serve to explain the principles of the present application.

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without creative labor.

[0037] Figure 1 Flow chart of the method provided by the embodiment of the present application;

[0038] Figure 2 Structure diagram of the clamping piece mechanism provided by the embodiment of the present application Figure 1 ;

[0039] Figure 3 Structure diagram of the clamping piece mechanism provided by the embodiment of the present application Figure 2 .

[0040] Icon: 1-first edge pressing ball hole; 2-second edge pressing ball hole; 3-edge pressing ball body; 4-limiting needle; 5-first clamping piece; 6-second clamping piece. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0042] Unless otherwise specifically indicated, all the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by the existing method.

[0043] The various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present text, it refers to any cited number (fraction or integer) within the indicated range.

[0044] In the present application, the orientation words such as "upper" and "lower" are the directions of the drawing surface in the drawings unless otherwise stated. In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but not limited to". In the present text, the relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the present text, the "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A and B can be singular or plural. In the present text, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including single item or any combination of multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0045] At present, there are two core technical problems in the application of continuous fiber reinforced resin matrix composites in the automotive field. On the one hand, the cost problem caused by manufacturing efficiency is the primary factor limiting its application. The low-cost manufacturing of continuous fiber composites is mainly realized through high-pressure resin transfer molding (HPRTM), prepreg molding (PCM) and other processes. However, the HPRTM process has high mold cost, and the process cycle required for resin injection and infiltration curing is too long to further meet the requirements of short cycle and high efficiency production; the PCM process uses prepreg to improve the performance stability of the component, but is limited by the high material cost of the prepreg and the high time and labor cost of the laying process, limiting its application range. On the other hand, due to the small damage strain of the fiber, the forming technology of complex structure cannot be broken through, and obvious defects such as fiber fracture and wrinkling often occur. In addition, if focusing on the application of power battery shell, the flame retardant ability of traditional epoxy resin and polypropylene resin is challenged, and the thermal runaway protection ability of the power battery pack cannot be effectively guaranteed.

[0046] The inventors intend to provide a brand new preparation path for the battery pack shell, which adopts the method of thermosetting resin spraying + vacuum assisted incremental molding forming, realizes the rapid compounding of fiber and resin and the overall forming of the component; through the close cooperation of methods such as fabric cutting-reinforcement design, vacuum assisted incremental molding, introduction of silicone soft mold, and multi-scale edge control, the forming ability of continuous fiber reinforced resin matrix composites is effectively improved, and the forming technical problem of complex shape components of power battery pack is solved.

[0047] In one aspect, the application provides a new technical path for using continuous fiber reinforced resin-based composite materials for the shell of a new energy vehicle power battery pack, effectively solving the complex component forming technical problem of having fire resistance and flame retardation performance; at the same time, the application provides a new idea for rapid and low-cost manufacturing of continuous fiber composites, which will effectively promote its application in civil fields such as automobiles and rail transit.

[0048] As shown in Figure 1 The application provides a preparation method of a battery pack shell, which comprises the following steps:

[0049] S1. obtaining a fiber substrate;

[0050] In some embodiments, the fiber substrate comprises a chopped fiber felt and a continuous fiber cloth arranged in a stack.

[0051] Specifically, in this embodiment, the chopped fiber felt, continuous fiber cloth and other hybrid fabrics are cut to the target size of the product and are laid in sequence. The laying sequence can be a hybrid fabric structure of central symmetrically laid plaid, warp-knitted fabric, twill, axial fabric, etc., and the surface is a glass fiber hybrid fabric surface layer, such as a chopped glass fiber surface felt.

[0052] S2. cutting a preset position of the fiber substrate to form a cutting area on the fiber substrate, and then connecting a reinforcing sheet to the fiber substrate to cover the cutting area to obtain a reinforcing substrate; wherein the reinforcing sheet is connected to the fiber substrate by a fixing member, and the melting point of the fixing member is not higher than the holding temperature of the mold pressing forming.

[0053] In some embodiments, the fixing member comprises a thermoplastic fixing pin. The thermoplastic fixing pin mainly comprises a conical pin body which is simultaneously provided in the reinforcing sheet and the fiber substrate to realize the connection of the two. A limiting block can also be provided at the end of the pin body to prevent the thermoplastic fixing pin from easily penetrating and separating from the reinforcing sheet and the fiber substrate, causing the failure of the connection of the two. The thermoplastic fixing pin can quickly and well connect the reinforcing sheet and the fiber substrate. At the same time, the use of the entire thermoplastic fixing pin is less, which can reduce its influence on the performance of the entire battery pack shell.

[0054] In some embodiments, the overlap area width of the reinforcing sheet and the fiber substrate is not less than 20mm. During the mold pressing forming process, the mold will extrude the reinforcing substrate, which will cause the relative displacement of the reinforcing sheet and the fiber substrate. In order to reduce the displacement to cause the vacancy of the entire battery pack shell, a certain width of the overlap area of the reinforcing sheet and the fiber substrate is required, and the width not less than 20mm can greatly reduce the generation of the vacancy.

[0055] In some embodiments, the reinforcing sheet comprises a glass fiber fabric, and the glass fibers in the glass fiber fabric are arranged in an orthogonal manner. It should be noted that the orthogonal manner here does not mean an absolute 90° perpendicular, but refers to the fact that the glass fibers are staggered, for example, the glass fiber fabric comprises a first fiber group and a second fiber group, the fibers in the first fiber group and the fibers in the second fiber group are arranged in parallel, and the fibers in the first fiber group and the fibers in the second fiber group are arranged at an angle. The glass fibers in the reinforcing sheet arranged in an orthogonal manner can produce a better reinforcing effect.

[0056] In some embodiments, the preset position of the fiber substrate is determined according to simulation software; optionally, the simulation software comprises Fibersim. The complex deformation region of the battery pack shell prone to defects such as fiber breakage and wrinkling can be determined in advance during design by using a three-dimensional simulation software.

[0057] Specifically, in this embodiment, the complex deformation region is automatically cut, and the cut reinforcing sheet is fixed in the cutting region by using a binding machine, wherein the reinforcing sheet is generally a continuous glass fiber fabric tending to be orthotropic, and the reinforcing sheet is fixed by using a thermoplastic fixing nail.

[0058] S3. The reinforcing substrate is tensioned and fixed by using a clamping mechanism;

[0059] Please refer to Figure 2 and Figure 3 In some embodiments, the clamping mechanism comprises a first clamping piece 5 and a second clamping piece 6; the first clamping piece 5 and / or the second clamping piece 6 is / are provided with a limiting pin 4; the first clamping piece 5 is provided with a pressure edge ball mechanism, and the pressure edge ball mechanism comprises a pressure edge ball body 3 and a mounting seat (not shown in the figure), the mounting seat is connected to the first clamping piece 5, and the pressure edge ball body 3 is rotatably mounted on the mounting seat.

[0060] The mounting seat can be mounted on the side of the first clamping piece 5 away from the second clamping piece 6, and the mounting seat is provided with a receiving cavity, which can be slightly larger than the pressure edge ball body 3, or the size and shape of the receiving cavity can match those of the pressure edge ball body 3, so as to realize the rolling of the pressure edge ball body 3, and at the same time, the first clamping piece 5 is provided with a first pressure edge ball hole 1, and part of the pressure edge ball body 3 can pass out of the first pressure edge ball hole 1 to realize the compression of the reinforcing substrate.

[0061] The second clamping piece 6 can be provided with a second pressure edge ball hole 2 to cooperate with the pressure edge ball body 3 to realize the compression of the reinforcing substrate.

[0062] The first clamping piece 5 and the second clamping piece 6 realize the clamping of the reinforcing substrate by using a locking mechanism, and the locking mechanism can be a bolt structure, a buckling structure, a clamping structure, a bolt structure, etc.

[0063] Specifically, in this embodiment, the fabric containing the reinforcing sheet (i.e., the reinforcing substrate) is transported by a conveying roller and fixed by a clamping mechanism with positioning and multi-scale tensioning functions. The clamping mechanism is composed of an upper and lower frame-shaped clamping piece. Multi-scale and planar four-directional edge pressing is performed by the limiting needle 4 and the edge pressing ball mechanism. The diameter of the edge pressing ball body 3 is 5-30 mm, the spacing is 30-60 mm, the ratio of the diameter of the edge pressing ball body 3 to the diameter of the first edge pressing ball hole 1 is 6:5 to 3:2, and the ratio of the diameter of the edge pressing ball body 3 to the diameter of the second edge pressing ball hole 2 is 3:2 to 3:1. The limiting needle 4 and the edge pressing ball mechanism are located on the upper clamping piece, and the corresponding area of the lower clamping piece is hollowed out. The limiting needle 4 and the edge pressing ball mechanism have a polyurethane spray and blockage protection device outside, which is attached to the shape of the upper and lower molds, and the edge pressing ball body 3 has the ability to rotate in any direction, improving the multi-directional edge pressing performance. At the same time, since the edge pressing ball body 3 can rotate, the probability of tearing the reinforcing substrate during pressing can be reduced. To further reduce the probability of tearing the reinforcing substrate, the number of limiting needles 4 needs to be designed as small as possible. Generally, the limiting needles 4 are concentrated in the corner part of the clamping mechanism, and 1-2 limiting needles are arranged on the edge of the clamping structure.

[0064] S4. Attaching the thermosetting resin to the reinforcing substrate;

[0065] In some embodiments, the thermosetting resin comprises polyurethane. Polyurethane has excellent flame retardant performance, and when applied to the battery pack shell, it can improve the thermal runaway protection capability of the battery pack.

[0066] In some embodiments, the way the thermosetting resin is attached to the reinforcing substrate includes spraying. Using the spraying method to achieve the attachment of the thermosetting resin to the reinforcing substrate, and then using the vacuum-assisted progressive molding method in the subsequent mold pressing, can effectively improve the infiltration of the thermosetting resin into the reinforcing substrate, thereby reducing the probability of defects in the battery pack shell.

[0067] Specifically, in this embodiment, the mechanical hand clamps the clamping piece to the polyurethane spraying area, and through the planar reciprocating motion and overturning of the mechanical hand, the polyurethane spraying of the front and back of the fabric is realized.

[0068] S5. Installing the clamping mechanism with the fixed reinforcing substrate into the mold to realize the transfer of the reinforcing substrate with the attached thermosetting resin into the mold;

[0069] In some embodiments, a silica gel layer is laid in the mold; the thickness of the silica gel layer is 0.2-2 mm. The silica gel layer is beneficial to improve the forming ability of the reinforcing substrate in the mold, and is also beneficial to improve the surface quality of the finally prepared battery pack shell. It should be noted that the silica gel layer can be placed in the mold before placing the reinforcing substrate, or it can be pre-set on the mold.

[0070] Specifically, in this embodiment, the reinforcing substrate after spraying is transferred into the mold by the mechanical hand clamping the clamping piece, and the precise and rapid mold entry is realized by the guide column on the mold.

[0071] S6. The reinforcing substrate with the thermosetting resin attached is subjected to mold pressing forming to obtain the battery pack shell;

[0072] In some embodiments, the mold pressing forming is performed in a vacuum-assisted progressive mold pressing manner; the holding temperature of the heat preservation and pressure retention is 100-140℃; and the time of the heat preservation and pressure retention is 200-400s. The vacuum-assisted progressive mold pressing manner can effectively improve the infiltration of the thermosetting resin into the reinforcing substrate, thereby reducing the probability of defects in the battery pack shell.

[0073] Specifically, in this embodiment, the double-action hydraulic forming equipment is adopted, after the fast edge pressing by the edge pressing die with controllable edge pressure, the forming die realizes the downward movement, overall deformation and precise progressive mold pressing at fast-medium-slow speed, realizes the mold sticking of the reinforcing substrate, and the vacuumizing treatment is respectively performed before and after the mold closing, the glass fiber reinforced foamed polyurethane composite material is subjected to the heat preservation and pressure retention in the mold, the upper mold is rapidly moved upward, the ejection mechanism acts on the clamping piece to eject, the glass fiber reinforced foamed polyurethane composite material is moved out of the mold by the mechanical hand, and the cutting and punching are performed to the target component geometric size to obtain the battery pack shell. The vacuumizing treatment specifically includes that the vacuumizing treatment is performed twice at the upper and lower mold edge portions before and after the complete mold closing of the progressive mold pressing forming, and the time of the two vacuumizing treatments is 2-10s, and the interval is 5-20s.

[0074] The method realizes the optimization and cooperation of the fabric cutting-reinforcing design, the vacuum-assisted progressive mold pressing, the introduction of the silica gel soft mold and the multi-scale edge pressing control, effectively prevents the defects such as fiber breakage and wrinkling in the fiber fabric deformation process, and makes it possible to integrally form the continuous fiber reinforced resin matrix composite material complex component. Meanwhile, the spraying type impregnation method based on the robot traction is adopted, the impregnation of the fiber and the resin is realized based on the spraying+vacuum-assisted mold pressing means, the progressive mold pressing forming and the multiple vacuumizing are cooperated based on the optimization of the fabric structure, the polyurethane resin is effectively impregnated and integrally foamed and solidified in the fabric along the thickness direction, the product density is further reduced, the process beat is reduced to 120s / piece, and the manufacturing efficiency of the continuous fiber reinforced resin matrix composite material is significantly improved.

[0075] The application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the international standard, the conventional condition or the condition suggested by the manufacturer is adopted.

[0076] Example 1

[0077] A method for preparing a battery pack casing, the method comprising:

[0078] Step 1: For complex continuous fiber reinforced polyurethane structures, first select two 150g / m² sheets. 2 Short-cut glass fiber surface mat and 2 sheets of 600g / m 2 Cut the fiberglass woven fabric to 2000mm*1500mm and lay it symmetrically with the chopped fiberglass surface mat on the outside and the fiberglass woven fabric on the inside.

[0079] Step 2: Automated cutting is performed on complex deformation areas, and the cut continuous glass fiber fabric reinforcement sheet is fixed to the cutting area using thermoplastic fixing nails with a melting point of 90℃ in the binding machine. The binding overlap area is no less than 20mm.

[0080] Step 3: The fabric containing the reinforcing strip is transported by conveyor rollers and fixed by multi-scale, four-directional planar edge pressing through a clamping mechanism containing limiting pins and grouped edge pressing balls (the diameter of the grouped edge pressing balls is 5mm, the spacing is 30mm, the ratio of the edge pressing ball holes to the upper clamping ball holes is 3:2, and the ratio of the edge pressing ball holes to the lower clamping ball holes is 3:1).

[0081] Step 4: The robotic arm grips the clamping piece and moves it to the polyurethane spraying area. Through the reciprocating motion and flipping of the robotic arm, polyurethane spraying is achieved on both sides of the fabric.

[0082] Step 5: The coated fabric is transferred into the mold by a robotic arm holding the clamps, and the mold is precisely and quickly inserted by eight guide pillars.

[0083] Step 6: Using a double-action hydraulic forming equipment, the surfaces of the upper and lower molds contain a 0.2mm thick silicone layer. After the edge is quickly pressed by the edge-pressing die with controllable pressing force, the forming mold moves downward, deforms as a whole, and is precisely and progressively molded by changing the speed from fast to medium to slow. Before and after the progressive molding is fully closed, the edges of the upper and lower molds are vacuumed twice, with a vacuuming time of 2 seconds and an interval of 20 seconds, to achieve fabric bonding.

[0084] Step 7: In the mold, the glass fiber reinforced polyurethane foam composite material is kept at a temperature of 100℃ for 200s and then kept under heat and pressure.

[0085] Step 8: The upper mold moves upward quickly, and the ejection mechanism pushes out the clamping piece. The robot removes the glass fiber reinforced polyurethane foam composite material from the mold, cuts and punches holes to the target component geometry, and obtains the battery pack shell.

[0086] Example 2

[0087] A method for preparing a battery pack casing, the method comprising:

[0088] Step 1: For complex continuous fiber reinforced polyurethane structures, first select two 150g / m² sheets. 2 Short-cut glass fiber surface mat and 2 sheets of 600g / m 2 The fiberglass twill fabric is cut to 2000mm*1500mm and laid symmetrically with the chopped fiberglass surface mat on the outside and the fiberglass woven fabric on the inside.

[0089] Step 2: Automated cutting is performed on complex deformation areas, and the cut continuous glass fiber fabric reinforcement sheet is fixed to the cutting area using thermoplastic fixing nails with a melting point of 120℃ in the binding machine. The binding overlap area is no less than 20mm.

[0090] Step 3: The fabric containing the reinforcing strip is transported by conveyor rollers and fixed by multi-scale, four-directional planar edge pressing through a clamping mechanism containing limiting pins and grouped edge pressing balls (the diameter of the grouped edge pressing balls is 30mm, the spacing is 60mm, the ratio of the edge pressing ball holes to the upper clamping edge pressing ball holes is 6:5, and the ratio of the edge pressing ball holes to the lower clamping edge pressing ball holes is 3:2).

[0091] Step 4: The robotic arm grips the clamping piece and moves it to the polyurethane spraying area. Through the reciprocating motion and flipping of the robotic arm, polyurethane spraying is achieved on both sides of the fabric.

[0092] Step 5: The coated fabric is transferred into the mold by a robotic arm holding the clamps, and precise and rapid mold entry is achieved through 16 guide pillars on the mold.

[0093] Step 6: Using a dual-action hydraulic forming equipment, the upper and lower mold surfaces contain a 2mm thick silicone layer. After the edge is quickly pressed by the edge-pressing die with controllable pressing force, the forming mold moves downward, deforms as a whole, and is precisely and progressively molded by changing the speed from fast to medium to slow. Before and after the progressive molding is fully closed, the edges of the upper and lower molds are vacuumed twice, with a vacuuming time of 10 seconds and an interval of 5 seconds, to achieve fabric bonding.

[0094] Step 7: In the mold, heat and pressure are maintained at a temperature of 140℃ for 400s for the glass fiber reinforced polyurethane foam composite material.

[0095] Step 8: The upper mold moves upward quickly, and the ejection mechanism pushes out the clamping piece. The robot removes the glass fiber reinforced polyurethane foam composite material from the mold, cuts and punches holes to the target component geometry, and obtains the battery pack shell.

[0096] Example 3

[0097] A method for preparing a battery pack casing, the method comprising:

[0098] Step 1: For complex continuous fiber reinforced polyurethane structures, first select two 150g / m² sheets. 2 Short-cut glass fiber surface mat and 2 sheets of 600g / m 2 The fiberglass axial fabric is cut to 2000mm*1500mm and laid symmetrically with the chopped fiberglass surface mat on the outside and the fiberglass woven fabric on the inside.

[0099] Step 2: Automated cutting is performed on complex deformation areas, and the cut continuous glass fiber fabric reinforcement sheet is fixed to the cutting area using thermoplastic fixing nails with a melting point of 100℃ in the binding machine. The binding overlap area is no less than 20mm.

[0100] Step 3: The fabric containing the reinforcing strip is transported by conveyor rollers and fixed by multi-scale, four-directional planar edge pressing through a clamping mechanism containing limiting pins and grouped edge pressing balls (the diameter of the grouped edge pressing balls is 15mm, the spacing is 45mm, the ratio of the edge pressing ball holes to the upper clamping ball holes is 5:4, and the ratio of the edge pressing ball holes to the lower clamping ball holes is 2:1).

[0101] Step 4: The robotic arm grips the clamping piece and moves it to the polyurethane spraying area. Through the reciprocating motion and flipping of the robotic arm, polyurethane spraying is achieved on both sides of the fabric.

[0102] Step 5: The coated fabric is transferred into the mold by a robotic arm holding the clamps, and precise and rapid mold entry is achieved through 12 guide pillars on the mold.

[0103] Step 6: Using a dual-action hydraulic forming equipment, the upper and lower mold surfaces contain a 1mm thick silicone layer. After the edge is quickly pressed by the edge-pressing die with controllable pressing force, the forming mold moves down, deforms as a whole, and is precisely and progressively molded by changing the speed from fast to medium to slow. Before and after the progressive molding is fully closed, the edges of the upper and lower molds are vacuumed twice, with a vacuuming time of 6 seconds and an interval of 15 seconds, to achieve fabric bonding.

[0104] Step 7: In the mold, heat and pressure are maintained at a temperature of 120℃ for 300s for the glass fiber reinforced polyurethane foam composite material.

[0105] Step 8: The upper mold moves upward quickly, and the ejection mechanism pushes out the clamping piece. The robot removes the glass fiber reinforced polyurethane foam composite material from the mold, and cuts and punches it to the target component geometry.

[0106] Comparative Example 1

[0107] A method for preparing a battery pack casing, the method comprising:

[0108] Step 1: For complex continuous fiber reinforced polyurethane structures, first select two 150g / m² sheets.2 Short-cut glass fiber surface mat and 2 sheets of 600g / m 2 The fiberglass axial fabric is cut to 2000mm*1500mm and laid symmetrically with the chopped fiberglass surface mat on the outside and the fiberglass woven fabric on the inside.

[0109] Step 2: Automated cutting is performed on complex deformation areas, and the cut continuous glass fiber fabric reinforcement sheet is fixed to the cutting area using thermoplastic fixing nails with a melting point of 130℃ in the binding machine. The binding overlap area is no less than 20mm.

[0110] Step 3: The fabric containing the reinforcing strip is transported by conveyor rollers and fixed by multi-scale, four-directional planar edge pressing through a clamping mechanism containing limiting pins and grouped edge pressing balls (the diameter of the grouped edge pressing balls is 15mm, the spacing is 45mm, the ratio of the edge pressing ball holes to the upper clamping ball holes is 5:4, and the ratio of the edge pressing ball holes to the lower clamping ball holes is 2:1).

[0111] Step 4: The robotic arm grips the clamping piece and moves it to the polyurethane spraying area. Through the reciprocating motion and flipping of the robotic arm, polyurethane spraying is achieved on both sides of the fabric.

[0112] Step 5: The coated fabric is transferred into the mold by a robotic arm holding the clamps, and precise and rapid mold entry is achieved through 12 guide pillars on the mold.

[0113] Step 6: Using a dual-action hydraulic forming equipment, the upper and lower mold surfaces contain a 1mm thick silicone layer. After the edge is quickly pressed by the edge-pressing die with controllable pressing force, the forming mold moves down, deforms as a whole, and is precisely and progressively molded by changing the speed from fast to medium to slow. Before and after the progressive molding is fully closed, the edges of the upper and lower molds are vacuumed twice, with a vacuuming time of 6 seconds and an interval of 15 seconds, to achieve fabric bonding.

[0114] Step 7: In the mold, heat and pressure are maintained at a temperature of 120℃ for 300s for the glass fiber reinforced polyurethane foam composite material.

[0115] Step 8: The upper mold moves upward quickly, and the ejection mechanism pushes out the clamping piece. The robot removes the glass fiber reinforced polyurethane foam composite material from the mold, and cuts and punches it to the target component geometry.

[0116] Comparative Example 2

[0117] A method for preparing a battery pack casing, the method comprising:

[0118] Step 1: For complex continuous fiber reinforced polyurethane structures, first select two 150g / m² sheets. 2 Short-cut glass fiber surface mat and 2 sheets of 600g / m 2The fiberglass axial fabric is cut to 2000mm*1500mm and laid symmetrically with the chopped fiberglass surface mat on the outside and the fiberglass woven fabric on the inside.

[0119] Step 2: Automated cutting is performed on complex deformation areas, and the cut continuous glass fiber fabric reinforcement sheet is fixed to the cutting area using stainless steel fixing nails in the binding machine, with a binding overlap of no less than 20mm.

[0120] Step 3: The fabric containing the reinforcing strip is transported by conveyor rollers and fixed by multi-scale, four-directional planar edge pressing through a clamping mechanism containing limiting pins and grouped edge pressing balls (the diameter of the grouped edge pressing balls is 15mm, the spacing is 45mm, the ratio of the edge pressing ball holes to the upper clamping ball holes is 5:4, and the ratio of the edge pressing ball holes to the lower clamping ball holes is 2:1).

[0121] Step 4: The robotic arm grips the clamping piece and moves it to the polyurethane spraying area. Through the reciprocating motion and flipping of the robotic arm, polyurethane spraying is achieved on both sides of the fabric.

[0122] Step 5: The coated fabric is transferred into the mold by a robotic arm holding the clamps, and precise and rapid mold entry is achieved through 12 guide pillars on the mold.

[0123] Step 6: Using a dual-action hydraulic forming equipment, the upper and lower mold surfaces contain a 1mm thick silicone layer. After the edge is quickly pressed by the edge-pressing die with controllable pressing force, the forming mold moves down, deforms as a whole, and is precisely and progressively molded by changing the speed from fast to medium to slow. Before and after the progressive molding is fully closed, the edges of the upper and lower molds are vacuumed twice, with a vacuuming time of 6 seconds and an interval of 15 seconds, to achieve fabric bonding.

[0124] Step 7: In the mold, heat and pressure are maintained at a temperature of 120℃ for 300s for the glass fiber reinforced polyurethane foam composite material.

[0125] Step 8: The upper mold moves upward quickly, and the ejection mechanism pushes out the clamping piece. The robot removes the glass fiber reinforced polyurethane foam composite material from the mold, and cuts and punches it to the target component geometry.

[0126] Using the methods provided in Examples 1 to 3 and Comparative Examples 1 to 2, 1000 battery pack casings were produced. The probability of fiber breakage defects in the battery pack casings is shown in the table below:

[0127]

[0128]

[0129] As can be seen from the table above, the probability of fiber breakage defects in the battery pack casing prepared by the method provided in the embodiments of this application is significantly lower, indicating that the method provided in the embodiments of this application can improve the problem of fiber breakage in the battery pack casing.

[0130] The above are merely specific embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a battery pack casing, characterized in that, The method includes: A fiber matrix is ​​obtained; The fiber matrix is ​​cut at a predetermined position to form a cut area on the fiber matrix, and then a reinforcing sheet is connected to the fiber matrix to cover the cut area to obtain a reinforcing matrix; The reinforcing substrate is tensioned and fixed using a clamping mechanism; Thermosetting resin is attached to the reinforcing matrix; The clamping mechanism with the reinforcing substrate fixed thereon is installed in the mold to transfer the reinforcing substrate with the thermosetting resin attached into the mold. The reinforcing matrix with the attached thermosetting resin is molded to obtain the battery pack housing; The reinforcing sheet is connected to the fiber matrix by a fastener, the melting point of which is not higher than the heat preservation and pressure holding temperature of the molding process, and the fastener includes a thermoplastic fixing nail.

2. The method for preparing the battery pack casing according to claim 1, characterized in that, The overlap area between the reinforcing sheet and the fiber matrix is ​​not less than 20 mm.

3. The method for preparing the battery pack casing according to claim 1, characterized in that, The reinforcing sheet comprises a glass fiber fabric in which the glass fibers are orthogonally distributed.

4. The method for preparing the battery pack casing according to claim 1, characterized in that, The fiber matrix comprises stacked chopped fiber mats and continuous fiber cloths.

5. The method for preparing the battery pack casing according to claim 1, characterized in that, The preset position of the fiber matrix is ​​determined by simulation software; and / or The simulation software includes Fibersim.

6. The method for preparing the battery pack casing according to claim 1, characterized in that, The clamping mechanism includes a first clamping piece and a second clamping piece; the first clamping piece and / or the second clamping piece are provided with limiting pins; the first clamping piece is provided with a pressing ball mechanism, the pressing ball mechanism includes a pressing ball body and a mounting base, the mounting base is connected to the first clamping piece, and the pressing ball body is rotatably mounted on the mounting base.

7. The method for preparing the battery pack casing according to claim 1, characterized in that, The thermosetting resin includes polyurethane.

8. The method for preparing the battery pack casing according to claim 1, characterized in that, The mold is lined with a silicone layer; and / or The thickness of the silicone layer is 0.2~2mm.

9. The method for preparing the battery pack casing according to claim 1, characterized in that, The thermosetting resin is adhered to the reinforcing substrate by means of spraying; and / or The compression molding is performed using a vacuum-assisted progressive compression molding method; and / or The pressure holding temperature for the heat preservation and pressure holding is 100~140℃; and / or The heat preservation and pressure holding time is 200~400s.

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