KR20200111987A - Manufacturing method of battery module case for electric vehicle - Google Patents

Abstract

Disclosed is a manufacturing method of a battery module case for an electric vehicle which increases watertightness and has an excellent heat radiation property. According to an embodiment of the present invention, the manufacturing method of a battery module case for an electric vehicle to manufacture a battery module case of a box shape to store a plurality of battery modules therein comprises: a sheet preparing step of preparing a sheet for forming an upper plate by cutting an aluminum alloy plate; a press forming step of forming an upper plate having a forming shape to cut both ends on the sheet; a friction stir welding step of performing friction stir welding on both side plates with a mounting bracket protruding to a prescribed height in the longitudinal direction of a cross section while bringing both side plates into contact with both ends of the upper plate; a trim forming step of forming a trim line along with a hole on the upper plate joined to both side plates in the friction stir welding step; a bending step of bending both side plates along both forming shapes on the upper plate by 90 degrees with respect to the upper plate; and a plate joining step of joining a front plate, a rear plate, and a lower plate along the edges of both side plates and the upper plate.

Description

Manufacturing method of battery module case for electric vehicle {Manufacturing method of battery module case for electric vehicle}

An embodiment of the present invention relates to a method of manufacturing a battery module case for an electric vehicle, and more particularly, a battery module case for an electric vehicle excellent in watertightness and heat dissipation by bonding both side plates made of an aluminum extruded material to an upper plate made of an aluminum alloy plate material. It relates to a method of manufacturing.

In recent years, interest in hybrid and electric vehicles is increasing due to high oil prices and environmental regulations, and starting in 2025, many automakers are announcing business plans focusing on electric vehicles.

While such an electric vehicle has advantages such as eco-friendliness and low maintenance costs, there are disadvantages of a short driving distance and a long charging time in relation to the battery, and research and development to overcome this has been continuously conducted.

1 is a projection view of a state in which a battery module mounted in a general electric vehicle is accommodated in a battery housing.

Referring to FIG. 1, a plurality of battery modules of an electric vehicle are embedded in the battery module case 100, and a battery module is provided in the battery housing 110 fixed to the lower part of the vehicle body follower panel (not shown). It is stored in a double row through a case.

On the other hand, the battery module case has excellent heat dissipation and watertightness so as to effectively dissipate heat generated when charging and discharging the battery module in a state in which a plurality of battery modules are housed, and it is lightweight and firmly protects the battery module. It is important to be able to do it.

Accordingly, research and development for minimizing the manufacturing cost while satisfying all the conditions of the battery module case as described above are continuously conducted.

In recent years, in order to reduce the high strength and weight of the battery module case, a 6000 series heat treatment alloy containing Mg and Si as the main components of aluminum (Al), or Zn as the main additive component of aluminum, but 7000 series high strength with Mg added thereto. There is a trend of manufacturing by applying heat-treated alloys.

These 6000 series and 7000 series heat treated alloys have good weldability and corrosion resistance, and have advantages such as having a tensile strength of 250 MPa or more due to heat treatment, but the elongation is within the range of 10% to 16%, so it is applied for molding and processing. The technology is very limited, which affects productivity and manufacturing cost.

Therefore, research and development for the production of an optimized battery module case using such an ultra-high strength aluminum alloy plate is required at the present moment when the popularization of electric vehicles is accelerated.

The matters described as the background art are only for enhancing an understanding of the background of the present invention, and should not be taken as acknowledging that they correspond to the prior art already known to those of ordinary skill in the art.

An embodiment of the present invention is to increase watertightness by minimizing the welding part by friction stir welding both side plates on which mounting brackets are integrally formed using an extruded material on an upper plate formed by press-molding an aluminum alloy plate, and then integrally forming through bending molding. It is intended to provide a method of manufacturing a battery module case for an electric vehicle with excellent heat dissipation.

In addition, it is intended to provide a method of manufacturing a battery module case for an electric vehicle that improves productivity by bonding the lower plate, the front plate, and the rear plate to the upper plate and both side plates by minimizing molding.

In one or more embodiments of the present invention, in a method of manufacturing a battery module case for an electric vehicle for manufacturing a box-shaped battery module case for accommodating a plurality of battery modules therein, the upper plate is cut by cutting an aluminum alloy plate. Sheet preparation step of preparing a sheet to be molded; A press forming step of forming an upper plate having a forming shape for bending both ends on the sheet; A friction stir welding step of friction stir welding of both side plates with mounting brackets protruding to a predetermined height along the longitudinal direction of the cross-section in a state of contacting both side ends of the upper plate; In the friction stir welding step, a trim forming step of forming a trim line together with a hole on an upper plate joined to both side plates; A bending molding step of bending the side plates at 90 degrees with respect to the upper plate according to the forming shape of both sides of the upper plate; And there may be provided a method of manufacturing a battery module case for an electric vehicle including a plate bonding step of bonding each of the front plate, the rear plate, and the lower plate along respective edges of the upper plate and both side plates.

Between the press forming step and the friction stir welding step, the upper plate heat treatment step of heat-treating the upper plate at a set temperature to remove residual stress caused by the forming molding may be further included.

In addition, between the bending forming step and the plate bonding step, when welding the upper plate and both side plates, a washing step of washing the attached welding foreign matter may be further included.

Here, the aluminum alloy plate may be made of a 6000-based alloy plate having a tensile strength of 170 MPa to 200 MPa.

In addition, the aluminum alloy plate may be made of a 6000-based alloy plate having a thickness of 3.0 mm to 4.0 mm.

Both side plates may be integrally formed with mounting brackets by processing an aluminum extrusion material.

In the heat treatment of the upper plate, a set temperature may be set in the range of 250°C to 270°C.

In addition, in the friction stir welding step, each side plate is abutted to both side ends of the upper plate, and may be joined by friction stir welding along the abutting surface using a friction stir welding tool.

In addition, the plate material bonding step may be bonded by laser welding each edge of the front plate, the rear plate, and the lower plate to each edge of the upper plate and both side plates.

In an embodiment of the present invention, after friction stir welding both side plates with mounting brackets integrally formed using an extruded material on both sides of the upper plate made by press-molding aluminum alloy plate, the upper plate and both side plates are integrally formed through bending molding. By doing so, it is possible to manufacture a battery module case for an electric vehicle with excellent heat dissipation while increasing water tightness by minimizing the welding part on the case.

In addition, the lower plate, the front plate, and the rear plate can be joined to the upper plate and both side plates through laser welding by minimizing molding to improve productivity.

1 is a projection view of a state in which a battery module mounted in a general electric vehicle is accommodated in a battery housing.
2 is a block diagram of a process according to a method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention.
3 is a process diagram of each step according to a method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention.
4 is a perspective view of a process for explaining the friction stir welding step (S30) of FIG. 3.
5 is a perspective view of a process for explaining the plate material bonding step (S60) of FIG. 3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various forms and is not limited to the embodiments described herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same or similar components are described by applying the same reference numerals throughout the specification.

Since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to what is shown in the drawings, and the thickness is enlarged to clearly express various parts and regions.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

2 is a block diagram illustrating a process according to a method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention, and FIG. 3 is a process diagram of each step according to a method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention. to be.

2 and 3, first, a battery module case 1 applied to a method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention accommodates a plurality of battery modules (not shown) therein. It may be formed in a box shape of a rectangular parallelepiped for, and includes an upper plate (F1) and a lower plate (F2), a front plate (F3) and a rear plate (F4), and both side plates (F5) (F6).

That is, the manufacturing method of the battery module case for an electric vehicle according to an embodiment of the present invention includes a sheet preparation step (S10), a press forming step (S20), a friction stir welding step (S30), a trim forming step (S40), and bending molding. Step (S50), and a plate material bonding step (S60).

The material applied to the method of manufacturing a battery module case for an electric vehicle according to an embodiment of the present invention is described by applying a 6000 series aluminum alloy plate having a thickness of 3.5 mm and a tensile strength of 170 MPa to 250 MPa, but is limited thereto. It is not, and the thickness can be set in the range of 3.0mm ~ 4.0mm, and if necessary, a 7000 series aluminum alloy plate having a tensile strength of 250MPa or more can be applied.

First, in the sheet preparation step (S10), an aluminum alloy plate is cut into a predetermined size of a rectangle to prepare a sheet 10 to form an upper plate F1.

At this time, the sheet 10 is cut and molded in the calculated dimensions so that the frame does not need to be trimmed separately in consideration of the width of the upper plate F1.

In the press-forming step (S20), a forming shape (FM) for partitioning both ends of the upper plate F1 in the front and rear direction so as to have a forming shape for bending both ends on the sheet 10 is performed.

That is, in the press forming step (S20), the forming shape formed along both ends of the upper plate (F1) is formed to be stepped with respect to the upper plate (F1).

Following the press forming step (S20), the upper plate heat treatment step (S21) of removing residual stress due to the forming molding may be performed through heat treatment (HT) with respect to the upper plate F1 at a set temperature.

In this case, the heat treatment set temperature may be set in the range of 250°C to 270°C.

In the friction stir welding step (S30), the mounting brackets (B) protrude to a certain height along the longitudinal direction of the cross-section. do.

4 is a perspective view of a process for explaining the friction stir welding step (S30) of FIG. 3.

Referring to FIG. 4, the side plates F5 and F6 are made of an aluminum extruded material, and the mounting brackets B are integrally formed by processing them.

In this friction stir welding step (S30), each side plate (F5) (F6) is abutted to both sides of the top plate (F1), along the abutting surface, by friction stir welding using a friction stir welding tool (5). However, it is not necessarily limited thereto, and may be joined through laser welding in consideration of thermal deformation of the joint.

In the trim forming step (S40), in the friction stir welding step (S30), along with a hole (H) for connecting the cooling line on the upper plate (F1) bonded to both side plates (F5) (F6), cables, etc. Trim molding is carried out to simultaneously mold the trim line (T) for connection of

In the bending forming step (S50), both ends of the upper plate F1 are bent downward by 90 degrees along the forming shapes FM on both sides of the upper plate F1 to form both side plates F5 and F6 with respect to the upper plate F1. Bending and molding.

Following the bending forming step (S50), when welding both side plates (F5) and (F6) to the upper plate (F1), a washing step (S51) of washing the attached welding foreign material using washing water may be performed.

In the plate joining step (S60), the front plate F3, the rear plate F4, and the lower plate F2 are respectively joined along the respective edges of the upper plate F1 and both side plates F5 and F6.

5 is a perspective view of a process for explaining the plate material bonding step (S60) of FIG. 3.

Referring to Figure 5, the plate material bonding step (S60) is the front plate (F3), the rear plate (F4) and each edge of the lower plate (F2) on each rim of the upper plate (F1) and both side plates (F5) (F6). Bonding is performed by laser welding using a laser beam in the focal section irradiated from the laser scanner 3.

Usually, TIG welding with good weldability is applied to the bonding of the aluminum alloy plate, but in an embodiment of the present invention, it is ideal to proceed with the bonding through laser welding in consideration of thermal deformation.

Therefore, the manufacturing method of the battery module case for an electric vehicle according to an embodiment of the present invention is a mounting bracket (B) integrally formed on both sides of the top plate (F1) formed by press-molding an aluminum alloy plate using an aluminum extrusion material. (F5) After friction stir welding of (F6), the upper plate (F1), both side plates (F5) (F6) and mounting brackets (B) are integrally formed before bending molding through bending molding. It minimizes, increases watertightness, and makes it possible to manufacture battery module cases for electric vehicles with excellent heat dissipation.

In addition, the mounting bracket (B) can be manufactured integrally with both side plates (F5) (F6) made of extruded material without a separate welding operation, thereby minimizing thermal deformation of the case due to welding.

In addition, the lower plate (F2), the front plate (F3) and the rear plate (F4) are joined through laser welding, which can be welded at high speed along each edge of the upper plate (F1) and both side plates (F5) (F6) by minimizing molding. It can improve productivity.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to implement various modifications within the scope of the claims, the detailed description of the invention, and the accompanying drawings. It is natural to fall within the scope of the invention.

1: battery module case
3: laser scanner
5: friction stir welding tool
10: sheet
F1: top
F2: lower plate
F3: Front
F4: back plate
F5, F6: shroud
H: Hall
FM: Forming shape
T: Dreamline
B: Mounting bracket

Claims (9)

In the method of manufacturing a battery module case for an electric vehicle for manufacturing a box-shaped battery module case for accommodating a plurality of battery modules therein,
Sheet preparation step of preparing a sheet to form an upper plate by cutting the aluminum alloy plate;
A press forming step of forming an upper plate having a forming shape for bending both ends on the sheet;
A friction stir welding step of friction stir welding of both side plates with mounting brackets protruding to a predetermined height along the longitudinal direction of the cross-section in a state of contacting both side ends of the upper plate; And
In the friction stir welding step, a trim forming step of forming a trim line together with a hole on an upper plate joined to both side plates;
A bending molding step of bending the side plates at 90 degrees with respect to the upper plate according to the forming shape of both sides of the upper plate;
A plate joining step of joining the front plate, the rear plate, and the lower plate along respective edges of the upper plate and both side plates;
Method of manufacturing a battery module case for an electric vehicle comprising a. The method of claim 1,
Between the press forming step and the friction stir welding step
The method of manufacturing a battery module case for an electric vehicle further comprising the step of heat-treating the upper plate to remove residual stress due to foaming by heat-treating the upper plate at a set temperature. The method of claim 1,
Between the bending forming step and the plate joining step
A method of manufacturing a battery module case for an electric vehicle further comprising a washing step of washing the attached welding foreign matter when welding the upper plate and both side plates. The method of claim 1,
The aluminum alloy plate is
A method of manufacturing a battery module case for an electric vehicle made of a 6000 series alloy plate having a tensile strength of 170 MPa to 200 MPa. The method of claim 1,
The aluminum alloy plate is
A method of manufacturing a battery module case for an electric vehicle made of a 6000 series alloy plate with a thickness ranging from 3.0mm to 4.0mm. The method of claim 1,
The side plates are
A method of manufacturing a battery module case for an electric vehicle in which a mounting bracket is integrally formed by processing an extruded aluminum material. The method of claim 1,
The upper plate heat treatment step
A method of manufacturing a battery module case for an electric vehicle in which the set temperature is set in the range of 250℃ to 270℃. The method of claim 1,
The friction stir welding step
A method of manufacturing a battery module case for an electric vehicle in which each side plate is abutted to both side ends of the upper plate by friction stir welding using a friction stir welding tool along the abutted surface. The method of claim 1,
The plate joining step
A method of manufacturing a battery module case for an electric vehicle in which the front plate, the rear plate, and each edge of the lower plate are laser-welded to each edge of the upper plate and both side plates.

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