A thin-walled cavity battery pack structure, welding tooling and welding process

Abstract

The present invention belongs to the technical field of new energy vehicles, and relates to a thin-walled cavity battery pack structure, welding tooling and welding process. The cooperation of the L-shaped baffles on the left and right sides of the battery pack and the corresponding lateral clamps can make the welds between the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate, the lower right bottom plate, the left upper side beam, the left lower side beam, the right upper side beam and the right lower side beam meet the production requirements; the longitudinal clamps on the upper and lower sides of the battery pack can longitudinally clamp the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate; the bottom plate clamp can clamp the middle long bottom plate onto the bottom plate. Through the cooperation of the lateral clamps, the longitudinal clamps and the bottom plate clamps, it can be ensured that the dimensional tolerances of the thin-walled cavity battery after welding meet the requirements of the drawings, reducing the man-hours used for the battery pack assembly point fixing, ensuring the assembly accuracy, and improving the dimensional consistency of the battery pack assembly after welding.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicles and relates to a thin-walled cavity battery pack structure, welding tooling and welding process. Background Art

[0002] At present, as "energy saving and environmental protection" has become a topic of widespread concern, lightweighting has also been widely used in automobiles. However, the development of electric vehicles has received more widespread attention, and how to make electric vehicles lightweight requires an effective method. For electric vehicles, the weight of the battery accounts for a large part of the entire vehicle, so how to reduce the weight of the battery part has a significant effect on the lightweighting of the entire electric vehicle.

[0003] As an important component of new energy vehicles, the battery box of electric vehicles is mainly used to install modular batteries. The battery pack bottom plate is used as the mounting surface of the battery module, which has high requirements on overall flatness, weld strength, and weld quality. For welds without support on the back, traditional MIG welding can only be used. Using traditional MIG welding methods for welding, the welding speed is slow, the product deformation is large, and it is difficult to adjust after welding. The welds are prone to welding defects such as cracks, pores, and lack of fusion, which increases the risk of weld rework. The tensile strength of the joints is low, and the tensile strength of the fusion welding joints is only 60% of the parent material. Delayed cracks are likely to occur during product use, reducing the product life. Summary of the invention

[0004] In view of this, in order to solve the above-mentioned problems existing in the welding process of the battery box of an electric vehicle, the present invention provides a thin-walled cavity battery pack structure, welding tooling and welding process.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a thin-walled cavity battery pack structure, including a middle long bottom plate, an upper left bottom plate and an upper right bottom plate are fixedly installed on both sides above the middle long bottom plate, and a lower left bottom plate and a lower right bottom plate are fixedly installed on both sides below the middle long bottom plate; a left upper side beam is fixedly installed on the upper left bottom plate, a left lower side beam is fixedly installed on the lower left bottom plate, a right upper side beam is fixedly installed on the upper right bottom plate, and a right lower side beam is fixedly installed on the lower right bottom plate; the upper left bottom plate is fixedly installed on the side opposite to the lower left bottom plate The ends of the upper right bottom plate and the lower right bottom plate are fixedly installed with a left middle end cross beam, which is fixedly connected to the left upper side beam and the left lower side beam respectively; the ends of the upper right bottom plate and the lower right bottom plate on the opposite side are fixedly installed with a right middle end cross beam, which is fixedly connected to the right upper side beam and the right lower side beam respectively; the left middle end cross beams are connected by a middle left short longitudinal beam, and the right middle end cross beams are connected by a middle right short longitudinal beam; the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate are hollow and are evenly provided with a number of plugging strips inside.

[0006] A welding tool for a thin-walled cavity battery pack comprises a base plate and limit blocks installed around the base plate, wherein a plurality of L-shaped baffles are evenly fixedly installed on the limit block on the right side of the battery pack; a lateral clamp corresponding to the baffle and used for clamping the battery pack is evenly fixedly installed on the limit block on the left side of the battery pack; lateral clamps are also installed on the limit blocks on the outside of the left short longitudinal beam and the right short longitudinal beam; longitudinal clamps for clamping the middle long base plate, the upper left base plate, the upper right base plate, the lower left base plate and the end of the lower right base plate are evenly fixedly installed on the limit blocks on the upper and lower sides of the battery pack; two groups of base plate clamps are fixedly installed on the limit blocks on the left and right sides of the battery pack.

[0007] Furthermore, the lateral clamping device includes a first base fixedly mounted on a limit block and a first pressure rod laterally spirally mounted on the first base. A pressure block is fixedly mounted on the end of the first pressure rod near the left upper side beam and the left lower side beam. An external thread is arranged on the outer side of the first pressure rod, and an internal thread is arranged on the inner side of a through hole of the first base. The first pressure rod is inserted into the through hole of the first base. The first pressure rod spirally rotates relative to the first base to clamp the left upper side beam and the left lower side beam in a horizontal direction.

[0008] Furthermore, the longitudinal clamp includes a second base fixedly mounted on the surface of the limit block, a clamping arm hinged on the second base, and a second clamping rod longitudinally spirally mounted on the clamping arm; a clamping plate is fixedly mounted on the lower end of the second clamping rod, a rotating handle is fixedly mounted on the upper end of the second clamping rod, an external thread is arranged on the outer side of the second clamping rod, an internal thread is arranged on the inner side of the through hole of the clamping arm, the second clamping rod is inserted into the through hole of the clamping arm, and the second clamping rod spirally rotates relative to the clamping arm to clamp the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate in the vertical direction.

[0009] Furthermore, the bottom plate clamp includes a third base fixedly mounted on the surface of the limit block, a rotating arm hinged on the third base, and a third pressure rod longitudinally spirally mounted on the rotating arm. A through hole with an internal thread is provided at the end of each pair of rotating arms, an external thread is provided on the outer side of the third pressure rod and passes through the through holes of each group of rotating arms in sequence, a pressure plate is fixedly mounted on the lower end of the third pressure rod, and a rotating handle is fixedly mounted on the upper end of the third pressure rod. The third pressure rod spirally rotates relative to the pressure arm to press the middle long bottom plate downward.

[0010] Furthermore, a buffer pad is installed on the pressing block or the pressing plate.

[0011] A welding process for a thin-walled cavity battery pack comprises the following steps:

[0012] A. Assemble the upper left floor plate and the upper right floor plate on both sides of the upper middle long floor plate in sequence, and assemble the lower left floor plate and the lower right floor plate on both sides of the lower middle long floor plate in sequence. Assemble the right upper side beam and the right lower side beam on the outer sides of the upper right floor plate and the lower right floor plate respectively and fix them with L-shaped baffles. Assemble the left upper side beam and the left lower side beam on the outer sides of the upper left floor plate and the lower left floor plate respectively and press them with lateral clamps.

[0013] B. Use the lateral clamps on the outside of the left short longitudinal beam and the right short longitudinal beam to press the left short longitudinal beam and the right short longitudinal beam onto the middle long bottom plate respectively, and the gap between the left short longitudinal beam and the left middle end cross beam on both sides, and the misalignment between the right short longitudinal beam and the right middle end cross beam on both sides is less than 0.2mm;

[0014] C. Press the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate onto the bottom plate through the longitudinal pressers on the upper and lower sides of the battery pack;

[0015] D. Press the middle long bottom plate down onto the bottom plate through two sets of bottom plate pressers;

[0016] E. First weld the first weld between the middle long bottom plate and the upper left bottom plate, the upper right bottom plate, the lower left bottom plate, and the lower right bottom plate, then weld the second weld between the upper left bottom plate and the left upper side beam, the upper right bottom plate and the right upper side beam, and finally weld the third weld between the lower left bottom plate and the left lower side beam, the lower right bottom plate and the right lower side beam, rotate the bottom plate 180°, and weld the welds on the back of each component of the battery pack. The welding parameters are: rotation speed of 1300rpm, welding speed of 500mm / min, stirring head forward angle of 2.5mm, and stirring head forward angle of 1.5mm. The angle of friction stir welding is 2.5°, the downward pressure of the stirring head is 2.0-2.1mm, and after the welding of the friction stir welding welds on both sides is completed, the left middle end cross beam, the right middle end cross beam and the left short longitudinal beam, the right short longitudinal beam, and the left and right short longitudinal beams and the corresponding bottom plate are grooved with a pneumatic rotary file, and the first butt weld, fillet weld, and second butt weld between the middle end cross beam and the bottom plate are welded by non-melting inert gas shielded welding. The welding parameters are: current 100A-110A, welding speed 2-3mm / s;

[0017] F. After the front and back sides are welded, the bottom plate is adjusted by FSW. The needleless stirring head is used for adjustment. The welds with small deformation are adjusted first, and then the welds with large deformation are adjusted. The welding parameters are: rotation speed is 1100rpm, welding speed is 700mm / min, the forward tilt angle of the stirring head is 2.5°, and the downward pressure of the stirring head is 0.1-0.2mm;

[0018] G. After the base plate is adjusted, turn to machining and machine off 20mm at each end of the base plate. First, remove the arc starting position and arc ending keyhole position by machining, and then machine the corresponding assembly features. After machining is completed, weld other parts.

[0019] The beneficial effects of the present invention are:

[0020] 1. The thin-walled hollow battery pack structure disclosed in the present invention. Currently, most battery packs use hollow profiles as main components, and the wall thickness of the profiles is mostly 2mm or 3mm. Compared with this type of battery pack, the battery pack involved in the present invention has a wall thickness of 1.5mm, which can further reduce the weight of the battery pack, thereby reducing the total weight of the vehicle, and can effectively reduce the energy consumption of the vehicle.

[0021] 2. The thin-walled cavity battery pack welding tool disclosed in the present invention can make the welds between the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate, the lower right bottom plate, the left upper side beam, the left lower side beam, the right upper side beam and the right lower side beam meet the production requirements through the cooperation of the L-shaped baffles on the left and right sides of the battery pack and the corresponding lateral clamps; the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate can be longitudinally compressed by the longitudinal clamps on the upper and lower sides of the battery pack; the middle long bottom plate can be compressed on the bottom plate by the bottom plate clamp. The cooperation of the lateral clamps, the longitudinal clamps and the bottom plate clamps can ensure that the dimensional tolerances of the thin-walled cavity battery after welding meet the requirements of the drawings, reduce the man-hours used for the battery pack assembly point fixation, ensure the assembly accuracy, and improve the dimensional consistency of the battery pack assembly after welding.

[0022] 3. The thin-walled cavity battery pack welding process disclosed in the present invention increases the length dimension of the bottom plate and removes the arc starting position and the keyhole position by machining after welding, which can reduce the keyhole repair welding process and reduce the risk of weld defects. By adding a plug strip, the original fusion welding weld is changed to a friction welding weld, which effectively reduces welding deformation, reduces the weld grinding process, and avoids welding defects.

[0023] Increase the length dimension and plugging strip, compared with the original MIG welding, reduce the product welding time and improve the welding efficiency; stir friction welding has small welding deformation and is easy to adjust. Compared with the original fusion welding, it saves welding time, weld repair time, adjustment time, etc. Reduce product production hours, improve weld quality, and ensure product life. After welding, the overall machining is adopted, so that the length dimension of the product can meet the requirements of the drawing and ensure the assembly accuracy of the later product.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 It is a schematic structural diagram of a thin-walled cavity battery pack structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the thin-walled cavity battery package of the present invention being assembled on a welding tool;

[0028] Figure 3 Schematic diagram of a weld in a thin-walled hollow battery pack structure of the present invention;

[0029] Figure 4 It is a schematic diagram of the welds between the front and rear end beams and the bottom plate in the thin-walled cavity battery pack structure of the present invention;

[0030] Figure 5 It is a schematic diagram of the welding seams between the front and rear end beams and the bottom plate in the thin-walled cavity battery pack structure of the present invention.

[0031] Figure numerals: middle long bottom plate 1, upper left bottom plate 2, upper right bottom plate 3, lower left bottom plate 4, lower right bottom plate 5, left upper side beam 6, left lower side beam 7, right upper side beam 8, right lower side beam 9, left middle end cross beam 10, right middle end cross beam 11, left short longitudinal beam 12, right short longitudinal beam 13, bottom plate 14, limit block 15, baffle 16, lateral clamp 17, longitudinal clamp 18, bottom plate clamp 19, first weld 20, second weld 21, third weld 22, first butt weld 23, fillet weld 24, second butt weld 25, third butt weld 26, fillet weld 27, front and rear side thrusters 28, left and right side longitudinal clamps 29, left and right side thrusters 30. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0034] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] like Figure 1The thin-walled cavity battery pack structure shown includes a middle long bottom plate 1, and the upper left bottom plate 2 and the upper right bottom plate 3 are fixedly installed on both sides above the middle long bottom plate 1, and the lower left bottom plate 4 and the lower right bottom plate 5 are fixedly installed on both sides below the middle long bottom plate 1. The left upper side beam 6 is fixedly installed on the upper left bottom plate 2, the left lower side beam 7 is fixedly installed on the lower left bottom plate 4, the right upper side beam 8 is fixedly installed on the upper right bottom plate 3, and the right lower side beam 9 is fixedly installed on the lower right bottom plate 5. The end portions of the upper left bottom plate 2 and the lower left bottom plate 4 on the opposite side are fixedly installed with a left middle end cross beam 10, and the left middle end cross beam 10 is fixedly connected to the left upper side beam 6 and the left lower side beam 7 respectively. The end portions of the upper right bottom plate 3 and the lower right bottom plate 5 on the opposite side are fixedly installed with a right middle end cross beam 11, and the right middle end cross beam 11 is fixedly connected to the right upper side beam 8 and the right lower side beam 9 respectively. The left middle end cross beams 10 are connected by the middle left short longitudinal beams 12, and the right middle end cross beams 11 are connected by the middle right short longitudinal beams 13. The upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4 and the lower right bottom plate 5 are hollow and have a plurality of plug strips evenly arranged inside. The hollow bottom plate is convenient for reducing the weight of the battery pack.

[0036] like Figures 2-3 The welding tooling of the thin-walled cavity battery pack shown includes a bottom plate 14 whose length and width dimensions are larger than the battery pack structure. Long strip limit blocks 15 are fixedly installed on all four sides of the bottom plate 14 for easy installation of the welding tooling. Four L-shaped baffles 16 are evenly fixedly installed on the limit blocks 15 on the right side of the battery pack. The L-shaped baffles 16 are used to limit the movement of the right upper side beam 8 and the right lower side beam 9, so that the gap between the right upper side beam 8, the right lower side beam 9 and the corresponding upper right bottom plate 3 and the lower right bottom plate 5 is less than 0.5 mm.

[0037] A lateral clamp 17 is evenly fixedly installed on the limit block 15 on the left side of the battery pack, which is used to clamp the battery pack opposite to the baffle 16. The lateral clamp 17 is used to limit the movement of the left upper side beam 6 and the left lower side beam 7, so that the gap between the left upper side beam 6, the left lower side beam 7 and the corresponding upper left bottom plate 2 and lower left bottom plate 4 is less than 0.5 mm.

[0038] The lateral clamp 17 includes a first base fixedly mounted on the limit block 15 and a first pressure rod laterally spirally mounted on the first base, and a circular pressure block with a buffer pad is fixedly mounted on the end of the first pressure rod near the left upper side beam 6 and the left lower side beam 7. The first pressure rod is penetrated on the first base, an external thread is arranged on the outer side of the first pressure rod, and an internal thread is arranged on the inner side of the through hole of the first base. The first pressure rod spirally rotates relative to the first base to press the left upper side beam 6 and the left lower side beam 7 in the horizontal direction.

[0039] A lateral clamp 17 is also installed on the limit block 15 outside the left short longitudinal beam 12 and the right short longitudinal beam 13, which is used to clamp the left short longitudinal beam 12 and the right short longitudinal beam 13 on the middle long bottom plate 1, and the gap between the left short longitudinal beam 12 and the left middle end cross beam 10 on both sides is less than 0.2mm, and the misalignment between the right short longitudinal beam 13 and the right middle end cross beam 11 on both sides is also less than 0.2mm.

[0040] The limit blocks 15 on the upper and lower sides of the battery pack are evenly fixedly installed with longitudinal clamps 18 for clamping the ends of the middle long bottom plate 1, the upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4 and the lower right bottom plate 5. The longitudinal clamp 18 includes a second base fixedly installed on the surface of the limit block 15, a clamping arm hinged on the second base, and a second clamping rod longitudinally spirally installed on the clamping arm. A clamping plate with a buffer pad is fixedly installed on the lower end of the second clamping rod, and a rotating handle is fixedly installed through the upper end of the second clamping rod. The second clamping rod is inserted into the clamping arm, and an external thread is set on the outer side of the second clamping rod, and an internal thread is set on the inner side of the through hole of the clamping arm. The second clamping rod spirally rotates relative to the clamping arm to clamp the middle long bottom plate 1, the upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4 and the lower right bottom plate 5 in the vertical direction.

[0041] Two groups of bottom plate tighteners 19 are fixedly installed on the limit blocks 15 on the left and right sides of the battery pack. The bottom plate tighteners 19 include a third base fixedly installed on the surface of the limit block 15, a rotating arm hinged on the third base, and a third pressure rod longitudinally spirally installed on the rotating arm. The ends of each pair of rotating arms are provided with through holes with internal threads. The outer side of the third pressure rod is provided with external threads and passes through the through holes of each group of rotating arms in sequence. The lower end of the third pressure rod is fixedly installed with a circular pressure plate with a buffer pad, and the upper end of the third pressure rod is penetrated and fixedly installed with a rotating handle. The third pressure rod spirally rotates relative to the pressure arm to press the middle long bottom plate 1 downward.

[0042] The components of the battery pack are compressed by the cooperation of the lateral pressers 17 , the longitudinal pressers 18 and the bottom plate pressers 19 .

[0043] The welding method of the thin-walled cavity battery pack comprises the following steps:

[0044] A. The upper left bottom plate 2 and the upper right bottom plate 3 are sequentially assembled on both sides of the upper part of the middle long bottom plate 1, and the lower left bottom plate 4 and the lower right bottom plate 5 are sequentially assembled on both sides of the lower part of the middle long bottom plate 1, and the right upper side beam 8 and the right lower side beam 9 are respectively assembled on the outer sides of the upper right bottom plate 3 and the lower right bottom plate 5 and fixed by an L-shaped baffle 16, and the left upper side beam 6 and the left lower side beam 7 are respectively assembled on the outer sides of the upper left bottom plate 2 and the lower left bottom plate 4 and compressed by a lateral clamp 17, that is, the first compression rod is rotated so that the circular compression block at the end of the first compression rod is pressed on the left upper side beam 6 and the left lower side beam 7;

[0045] B. The left short longitudinal beam 12 and the right short longitudinal beam 13 are respectively pressed against the middle long bottom plate 1 by the lateral clamps 17 on the outside of the left short longitudinal beam 12 and the right short longitudinal beam 13, and the gap between the left short longitudinal beam 12 and the left middle end cross beam 10 on both sides, and the misalignment between the right short longitudinal beam 13 and the right middle end cross beam 11 on both sides is less than 0.2mm, that is, the first pressure rod is rotated so that the circular pressure block at the end of the first pressure rod is pressed on the outside of the left short longitudinal beam 12 and the right short longitudinal beam 13;

[0046] C. The middle long bottom plate 1, the upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4 and the lower right bottom plate 5 are pressed on the bottom plate by the longitudinal clamps 18 on the upper and lower sides of the battery pack, that is, the second pressure rod is rotated so that the pressure plate at the end of the second pressure rod is pressed on the ends of the middle long bottom plate 1, the upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4 and the lower right bottom plate 5;

[0047] D. Press the middle long bottom plate 1 downward onto the bottom plate by two sets of bottom plate pressers 19, that is, rotate the third pressing rod so that the pressing plate at the end of the third pressing rod presses onto the middle long bottom plate 1;

[0048] E. First, weld the first weld 20 between the middle long bottom plate 1 and the upper left bottom plate 2, the upper right bottom plate 3, the lower left bottom plate 4, and the lower right bottom plate 5, then weld the second weld 21 between the upper left bottom plate 2 and the left upper side beam 6, the upper right bottom plate 3 and the right upper side beam 8, and finally weld the third weld 22 between the lower left bottom plate 4 and the left lower side beam 7, the lower right bottom plate 5 and the right lower side beam 9, rotate the bottom plate 180°, and weld the welds on the back of each component of the battery pack. The welding parameters are: rotation speed of 1300rpm, welding speed of 500mm / min, stirring head forward tilt angle of 2.5°, and stirring head downward pressure of 2.0-2.1mm; After the friction stir welding welds on both sides are completed, use a pneumatic rotary file to grind the grooves of the welds between the left middle end cross beam 10, the right middle end cross beam 11 and the left short longitudinal beam 12, the right short longitudinal beam 13, and the left and right short longitudinal beams and the corresponding bottom plates, and then as shown in Figure 4As shown, non-melting inert gas shielded welding (TIG) is used to weld the first butt weld 23 between the middle end cross beam and the bottom plate, the fillet weld 24, and the second butt weld 25 between the middle end cross beam and the short longitudinal beam. The welding parameters are: current 100A~110A, welding speed 2~3mm / s.

[0049] F. After the front and back sides are welded, the bottom plate is adjusted by FSW. The needleless stirring head is used for adjustment. The welds with small deformation are adjusted first, and then the welds with large deformation are adjusted. The welding parameters are: rotation speed is 1100rpm, welding speed is 700mm / min, the forward tilt angle of the stirring head is 2.5°, and the downward pressure of the stirring head is 0.1-0.2mm;

[0050] G. After the adjustment of the bottom plate is completed, it is turned to machining. 20mm is machined off at both ends of the bottom plate. The arc starting position and arc closing keyhole position are first machined off, and then the corresponding assembly features are machined. After machining is completed, the front and rear end beams are assembled on the second-order tooling. The assembly gap is less than 0.5mm, and the misalignment is less than 0.2mm. After the assembly is completed, stir friction welding is used to weld the third butt weld 26 between the front and rear end beams and the bottom plate (there are 4 third butt welds 26 on the front and back sides). The welding parameters are: rotation speed is 1300rpm, welding speed is 500mm / min, stirring head forward tilt angle is 2.5°, and stirring head downward pressure is 2.0~2.1mm. The tooling clamping method is as follows Figure 5 As shown, the workpiece is moved close to the lower and right side limiters, the front and rear pushers 28 and the left and right pushers 30 are rotated sideways, and the left and right longitudinal clamps 29 are pressed tightly, so that the various components of the product can be fixed.

[0051] After the front and rear end beams are welded, the fillet welds 27 (a total of 8 welds 27) between all the longitudinal beams are welded using non-melting inert gas shielded welding (TIG). After all the welds are welded, they are turned to machining to process features such as rivet holes and bolt holes, and the overall process of the battery pack is completed.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A welding tool for processing a thin-walled cavity battery pack structure, characterized in that: The thin-walled cavity battery pack structure includes a middle long bottom plate, an upper left bottom plate and an upper right bottom plate are fixedly installed on both sides above the middle long bottom plate, and a lower left bottom plate and a lower right bottom plate are fixedly installed on both sides below the middle long bottom plate; a left upper side beam is fixedly installed on the upper left bottom plate, a left lower side beam is fixedly installed on the lower left bottom plate, a right upper side beam is fixedly installed on the upper right bottom plate, and a right lower side beam is fixedly installed on the lower right bottom plate; a left middle end cross beam is fixedly installed on the ends of the upper left bottom plate and the lower left bottom plate on the opposite side, and the left middle end cross beam is fixedly connected to the left upper side beam and the left lower side beam respectively; a right middle end cross beam is fixedly installed on the ends of the upper right bottom plate and the lower right bottom plate on the opposite side, and the right middle end cross beam is fixedly connected to the right upper side beam and the right lower side beam respectively; the left middle end cross beams are connected by the middle left short longitudinal beam, and the right middle end cross beams are connected by the middle right short longitudinal beam; the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate are hollow and a number of plugging strips are evenly arranged inside; The welding structure includes a bottom plate and limit blocks installed around the bottom plate. A plurality of L-shaped baffles are evenly fixedly installed on the limit block on the right side of the battery pack; a lateral clamp corresponding to the baffle and used to clamp the battery pack is evenly fixedly installed on the limit block on the left side of the battery pack; lateral clamps are also installed on the limit blocks on the outside of the left short longitudinal beam and the right short longitudinal beam; longitudinal clamps for clamping the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate end are evenly fixedly installed on the limit blocks on the upper and lower sides of the battery pack; two sets of bottom plate clamps are fixedly installed on the limit blocks on the left and right sides of the battery pack; The lateral clamping device comprises a first base fixedly mounted on the limit block and a first pressure rod laterally spirally mounted on the first base, a pressure block is fixedly mounted on the end of the first pressure rod close to the left upper side beam and the left lower side beam, an external thread is arranged on the outer side of the first pressure rod, an internal thread is arranged on the inner side of the through hole of the first base, the first pressure rod is inserted into the through hole of the first base, and the first pressure rod spirally rotates relative to the first base to clamp the left upper side beam and the left lower side beam in the horizontal direction; The longitudinal clamping device includes a second base fixedly installed on the surface of the limit block, a clamping arm hinged on the second base, and a second clamping rod longitudinally spirally installed on the clamping arm. A clamping plate is fixedly installed on the lower end of the second clamping rod, and a rotating handle is fixedly installed on the upper end of the second clamping rod. An external thread is arranged on the outer side of the second clamping rod, and an internal thread is arranged on the inner side of the through hole of the clamping arm. The second clamping rod is inserted into the through hole of the clamping arm, and the second clamping rod spirally rotates relative to the clamping arm to clamp the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate in the vertical direction.

2. The welding tool for processing a thin-walled cavity battery pack structure according to claim 1, characterized in that: The bottom plate clamp includes a third base fixedly mounted on the surface of the limit block, a rotating arm hinged on the third base, and a third pressure rod longitudinally spirally mounted on the rotating arm. A through hole with an internal thread is provided at the end of each pair of rotating arms, and an external thread is arranged on the outer side of the third pressure rod and passes through the through holes of each group of rotating arms in sequence. A pressure plate is fixedly mounted on the lower end of the third pressure rod, and a rotating handle is fixedly mounted on the upper end of the third pressure rod. The third pressure rod spirally rotates relative to the pressure arm to press the middle long bottom plate downward.

3. The welding tool for the thin-walled cavity battery pack according to claim 2, characterized in that: The pressing block or the pressing plate is provided with a buffer pad.

4. A welding process for processing a thin-walled cavity battery pack structure, characterized in that: The thin-walled cavity battery pack structure includes a middle long bottom plate, an upper left bottom plate and an upper right bottom plate are fixedly installed on both sides above the middle long bottom plate, and a lower left bottom plate and a lower right bottom plate are fixedly installed on both sides below the middle long bottom plate; a left upper side beam is fixedly installed on the upper left bottom plate, a left lower side beam is fixedly installed on the lower left bottom plate, a right upper side beam is fixedly installed on the upper right bottom plate, and a right lower side beam is fixedly installed on the lower right bottom plate; a left middle end cross beam is fixedly installed on the ends of the upper left bottom plate and the lower left bottom plate on the opposite side, and the left middle end cross beam is fixedly connected to the left upper side beam and the left lower side beam respectively; a right middle end cross beam is fixedly installed on the ends of the upper right bottom plate and the lower right bottom plate on the opposite side, and the right middle end cross beam is fixedly connected to the right upper side beam and the right lower side beam respectively; the left middle end cross beams are connected by the middle left short longitudinal beam, and the right middle end cross beams are connected by the middle right short longitudinal beam; the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate are hollow and a number of plugging strips are evenly arranged inside; The welding process includes the following steps: A. Assemble the upper left floor plate and the upper right floor plate on both sides of the upper middle long floor plate in sequence, and assemble the lower left floor plate and the lower right floor plate on both sides of the lower middle long floor plate in sequence. Assemble the right upper side beam and the right lower side beam on the outer sides of the upper right floor plate and the lower right floor plate respectively and fix them with L-shaped baffles. Assemble the left upper side beam and the left lower side beam on the outer sides of the upper left floor plate and the lower left floor plate respectively and press them with lateral clamps. B. Use the lateral clamps on the outside of the left short longitudinal beam and the right short longitudinal beam to press the left short longitudinal beam and the right short longitudinal beam onto the middle long bottom plate respectively, and the gap between the left short longitudinal beam and the left middle end cross beam on both sides, and the misalignment between the right short longitudinal beam and the right middle end cross beam on both sides is less than 0.2mm; C. Press the middle long bottom plate, the upper left bottom plate, the upper right bottom plate, the lower left bottom plate and the lower right bottom plate onto the bottom plate through the longitudinal pressers on the upper and lower sides of the battery pack; D. Press the middle long bottom plate down onto the bottom plate through two sets of bottom plate pressers; E. First weld the first weld between the middle long bottom plate and the upper left bottom plate, the upper right bottom plate, the lower left bottom plate, and the lower right bottom plate, then weld the second weld between the upper left bottom plate and the left upper side beam, the upper right bottom plate and the right upper side beam, and finally weld the third weld between the lower left bottom plate and the left lower side beam, the lower right bottom plate and the right lower side beam, rotate the bottom plate 180°, and weld the welds on the back of each component of the battery pack. The welding parameters are: rotation speed of 1300rpm, welding speed of 500mm / min, stirring head forward angle of 2.5mm, and stirring head forward angle of 1.5mm. The angle of friction stir welding is 2.5°, the downward pressure of the stirring head is 2.0~2.1mm, and after the welding of the friction stir welding welds on both sides is completed, the left middle end cross beam, the right middle end cross beam and the left short longitudinal beam, the right short longitudinal beam, and the left and right short longitudinal beams and the corresponding bottom plate are grooved with a pneumatic rotary file. The first butt weld, fillet weld, and second butt weld between the middle end cross beam and the bottom plate are welded by non-melting inert gas shielded welding. The welding parameters are: current 100A~110A, welding speed 2~3mm / s; F. After the front and back sides are welded, the bottom plate is adjusted by FSW. The needleless stirring head is used for adjustment. The welds with small deformation are adjusted first, and then the welds with large deformation are adjusted. The welding parameters are: rotation speed is 1100rpm, welding speed is 700mm / min, the forward tilt angle of the stirring head is 2.5°, and the downward pressure of the stirring head is 0.1~0.2mm; G. After the base plate is adjusted, turn to machining and machine off 20mm at each end of the base plate. First, remove the arc starting position and arc ending keyhole position by machining, and then machine the corresponding assembly features. After machining is completed, weld other parts.

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