WO2014204030A1

WO2014204030A1 - Laser welding apparatus for electrode terminal

Info

Publication number: WO2014204030A1
Application number: PCT/KR2013/005456
Authority: WO
Inventors: Kwan Yong Kim
Original assignee: Sk Innovation Co.,Ltd.
Priority date: 2013-06-20
Filing date: 2013-06-20
Publication date: 2014-12-24

Abstract

Provided is a laser welding apparatus for an electrode terminal for welding plate shaped electrode terminals of a battery cell or a battery module to each other or welding the plate shaped electrode terminals to an external circuit, and more specifically, a pair of pressure rollers formed at a lower side of a laser welding head and vertically movable are used to be moved in a state in which two electrodes are closely adhered, thereby performing continuous laser welding, such that laser welding is performed in a state that electrodes are closely adhered to thereby decrease the welding defect of the electrode terminal.

Description

LASER WELDING APPARATUS FOR ELECTRODE TERMINAL

The present invention relates to a laser welding apparatus for an electrode terminal capable of decreasing a welding defect of the electrode terminal.

In general, a secondary battery is capable of being charged and discharged to be applied to various fields such as a digital camera, a cellular phone, a notebook and a hybrid car, unlike a primary battery, and research thereof has been actively conducted. An example of the secondary battery may include a nickel-cadmium battery, a nickel-metal hydride battery, a nickel-hydrogen battery, and a lithium secondary battery.

Among the secondary batteries, research into a lithium secondary battery having high energy density and discharge voltage has been largely conducted and the lithium secondary battery has been commercialized to be widely used.

In addition, a medium or large-sized battery module in which a plurality of battery cells are stacked and the battery cells are electrically connected in series or in parallel is used for a medium or large-sized device such as an automobile, or the like, due to a need for high output and large capacitance.

In order to electrically connect the plurality of battery cells as described above, plate shaped electrode terminals formed at one side of the battery cell are bent and coupled to each other by laser welding in a state in which they are overlapped with each other.

In the existing laser welding apparatus for welding the electrode terminals, a lower portion of the overlapped electrode terminals is supported by a counter bar, and the open part is welded by laser-irradiation in a state in which an upper portion of thereof is pressed by a clamp bar having an open part for the laser welding, whereby the electrode terminals are welded in a state in which they are closely adhered.

However, since the counter bar and the clamp bar allowing the overlapped electrode terminals to be closely adhered have a long length, and only one side thereof each is fixed to a jig so as to be inserted into the upper portion and the lower portion of the overlapped electrode terminals, the overlapped electrode terminal has a decreased adhesion to cause a welding defect.

In addition, since a cathode terminal and an anode terminal of the battery cell are made of different materials, a welding adhesion between the electrode terminals tends to be deteriorated at the time of being welded to each other, such that a welding portion of the medium and large-sized battery module as manufactured above become separated by external force such as vibration, shock, or the like, which causes a short-circuit. Therefore, an adhered state between the welded electrode terminals is a significantly important factor controlling a welding adhesion.

As a related art document associated with the above-description, “Method for Welding Thin Plates of Different Metal” which is a European Patent No. 1779962 has been disclosed.

[Related Art Document]

[Patent Document]

EP 1779962 A1 (May 2, 2007)

An object of the present invention is to provide a laser welding apparatus for an electrode terminal capable of decreasing a welding defect of the electrode terminal.

In one general aspect, a laser welding apparatus for an electrode terminal includes: a laser welding head; a vertical moving part coupled to one side of the laser welding head to be vertically movable; a pair of tension bars formed at a lower side of the vertical moving part and spaced apart from each other by a predetermined distance; a pair of pressure rollers rotatably coupled to the tension bars; and a laser beam irradiation part formed in the laser welding head or the vertical moving part to irradiate a laser beam between the pair of pressure rollers.

The vertical moving part may include: an actuator coupled to one side of the laser welding head; a moving plate coupled to one side of the actuator and having the pair of tension bars formed at a lower side thereof; and a guide rod having a lower side coupled to the moving plate and an upper side inserted into a through-hole formed in the laser welding head to be vertically movable.

The laser welding apparatus for an electrode terminal may further include a lower supporter supporting a lower side of the electrode terminals.

The laser welding apparatus for an electrode terminal may further include a side supporter supporting outer side surfaces of the electrode terminals.

The pair of tension bars may have a shape in which a lower side thereof is bent so as to be inclined in a direction in which they face each other, a shape in which they are inclined so that the lower side thereof has a narrow width, or a curved shape.

The tension bar may be made of an elastic material.

The pressure roller may have a disk shape or a conical shape.

The laser welding apparatus for an electrode terminal according to the present invention may decrease the welding defect of the electrode terminal by laser welding in the state in which the electrode terminals are closely adhered.

FIG. 1 is a perspective view showing a general structure in which battery cells and electrode terminals are coupled to each other by welding;

FIGS. 2 and 3 are side views showing a laser welding apparatus of the electrode terminal and a welded state of the electrode terminal according to the present invention; and

FIGS. 4 and 5 are front views showing the laser welding apparatus of the electrode terminal and the welded state of the electrode terminal according to the present invention.

[Detailed Description of Main Elements]

1000: laser welding apparatus for electrode terminal

10: battery cell 20: electrode terminal

100: laser welding head 110: through-hole

200: vertical moving part

210: actuator (cylinder) 211: cylinder rod

220: moving plate 230: guide rod

300: tension bar

400: pressure roller

500: laser beam irradiation part

600: lower supporter

700: side supporter

Hereinafter, a laser welding apparatus of an electrode terminal of the present invention as described above will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily practice the present invention.

FIG. 1 is a perspective view showing a general structure in which battery cells and electrode terminals are coupled to each other by welding.

First, the plurality of battery cells 10 are stacked in parallel with each other and electrically connected in series or in parallel to be formed as a battery module. Here, as shown in the drawings, a plate shaped electrode terminal (or an electrode tab, 20) is formed at one side of each battery cell 10, is bent, and welded in a state in which the terminals are overlapped with each other to thereby be electrically connected to the battery cell.

FIGS. 2 and 5 are side views and front views showing the laser welding apparatus of the electrode terminal and the welded state of the electrode terminal according to the present invention.

As shown in the drawings, the laser welding apparatus for the electrode terminal 1000 of the present invention may include: a laser welding head 100; a vertical moving part 200 formed at one side of the laser welding head 100 to be vertically movable; a pair of tension bars 300 formed at a lower side of the vertical moving part 200 and spaced apart from each other by a predetermined distance; a pair of pressure rollers 400 rotatably coupled to the tension bars 300; and a laser beam irradiation part 500 formed in the laser welding head 100 or the vertical moving part 200 to irradiate a laser beam between the pair of pressure rollers 400.

First, the laser welding head 100 may be coupled to a main body (not shown) of the laser welding apparatus so as to be movable in a front and rear direction and a left and right direction, and may be formed so as to be movable to a position to be welded or a direction to be welded and fixing the position. That is, the laser welding head 100 may move to weld the electrode terminal 20 in a state in which the lower supporter 600 and the side supporter 700 support the stacked battery cells 10 and the electrode terminals 20. To the contrary, the lower supporter 600 and the side supporter 700 having the fixed laser welding head 100 and supporting the stacked battery cells 10 and the electrode terminals 20 move together, such that a plurality of welding parts may be sequentially welded.

The vertical moving part 200 may be coupled to one side of the laser welding head 100 and be vertically movable. Here, the vertical moving part 200 includes: an actuator 210 coupled to one side of the laser welding head 100; a moving plate 220 coupled to one side of the actuator 210 and having the pair of tension bars 300 formed at a lower side thereof; and a guide rod 230 having a lower side coupled to the moving plate 220 and an upper side inserted into a through-hole 110 formed in the laser welding head 110 to be vertically movable.

In this case, a general pneumatic cylinder may be used for the actuator 210, the pneumatic cylinder may be fixed to a side surface of a lower portion of the laser welding head 100, the moving plate 220 may be coupled to the cylinder rod 211, such that the moving plate 220 may be vertically moved by an operation of the pneumatic cylinder. Here, each of both sides of an upper surface of the moving plate 220 may be coupled to a lower side of the guide rod 230, and each of the upper side of the guide rod 230 may be inserted into the through-hole 110 formed at the lower side of the laser welding head 100, such that the moving plate 220 and the guide rod 230 may be vertically moved together. Accordingly, the moving plate 220 may be vertically moved by the pair of guide rods 230 in a state in which it is horizontally positioned.

The tension bar 300 may be formed at the lower side of the moving plate 220 of the vertical moving part 200, and the pair of tension bars may be formed at both sides of the moving plate while being spaced apart from each other by a predetermined distance.

In addition, the pressure roller 400 may be rotatably coupled to the pair of tension bars 300. That is, the pressure roller 400 may be coupled to the tension bar 300 by an axis of rotation or a hinge, such that when the laser welding apparatus for the electrode terminal moves while pressing the electrode terminals 20, the pressure roller is capable of being rotated.

Further, the lower side of the laser welding head 100 or the lower side of the moving plate 220 of the vertical moving part 200 is provided with the laser beam irradiation part 500, a laser beam may be irradiated between the pair of pressure rollers 400 to weld the electrode terminals 20.

Accordingly, as shown in FIGS. 2 and 4, when the actuator 210 of the vertical moving part 200 is operated at a height spaced apart by a predetermined distance from the upper side of the electrode terminal 20, the pressure roller 400 may be in contact with the upper side of the electrode terminal 20, such that the two electrode terminals 20 may be closely adhered as shown in FIGS. 3 and 5. Then, the laser beam is irradiated from the laser beam irradiation part 500 to the electrode terminal 20, the laser welding head 100 moves, such that the electrode terminals 20 may be sequentially welded.

Here, the pressure roller 400 is in contact with the electrode terminal 20 and moves while being rotated, and the laser beam is irradiated between the pair of pressure rollers 400 to weld the electrode terminal 20, such that pressure is locally applied to both sides of the welding part to weld the electrode terminals 20 while being closely adhered, thereby improving adhesion and preventing a welding defect of the electrode terminal.

In addition, the laser welding apparatus 1000 of the electrode terminal of the present invention may further include a lower supporter 600 supporting the lower side of the electrode terminals 20. That is, the pressure roller 400 moves to a lower side thereof in a state in which the lower supporter 600 is inserted so as to support the lower side of the electrode terminals 20, such that the electrode terminals 20 may be closely adhered from the upper side thereof.

Further, the laser welding apparatus 1000 of the electrode terminal of the present invention may further include a side supporter 700 supporting outer side surfaces of the electrode terminals 20. The reason is that when the pressure roller 400 rotatably moves in a state in which the electrode terminals 20 are closely adhered to the pressure roller 400, the electrode terminals 20 may be prevented from being pushed out, such that the welding process is accurately achieved.

In addition, the pair of tension bars 300 may have a shape in which a lower side thereof is bent so as to be inclined in a direction in which they face each other, a shape in which they are inclined so that the lower side thereof has a narrow width, or a curved shape. As shown in FIG. 3, since the tension bar 300 is formed and a width of the upper side of the pressure roller 400 is widely formed, an irradiation state of the laser beam and a welded state at the time of the welding process are easily and visibly confirmed, and the pressure roller 400 may be prevented from being pushed out, such that both sides which is the closest to the welding part of the electrode terminal 20 may be pressurized to be closely adhered.

Further, the tension bar 300 may be made of an elastic material. In the case in which each height at both sides of the bottom of the pressure roller 400 having the tension bar 300 fixed thereto is different from each other due to a tolerance at the time of manufacturing the apparatus or abrasion by the use thereof, the difference in the height may be supplemented by the tension bar 300 having elasticity at the time of pressing the electrode terminal 20, such that the case in which the pressure roller 400 positioned at one side is not closely adhered to the electrode terminal 20 may be prevented.

In addition, the pressure roller may have a disk shape or a conical shape. In the case in which the pressure roller 400 has a cylinder shape, when the electrode terminal 20 is pressed, a line-contact may be achieved to disperse the pressed power, and in the case in which the pressure roller 400 has a disk shape or a cone shape, the pressure may be locally applied, such that the electrode terminals 20 may be closely adhered even by low power.

Further, it is preferable that the guide rod 230 of the vertical moving part 200 has a diameter shorter than that of the through-hole 110 of the laser welding head 100, such that the guide rod 230 is smoothly and vertically moved along the through-hole 110. Further, it is preferable that the guide rod 230 and the through-hole 110 are configured of two pairs each, to be formed at an edge portion of a quadrangle based on the laser beam irradiation part 500, respectively, such that the moving plate 220 of the vertical moving part 200 vertically moves while being horizontal in a front and rear direction and in a left and right direction.

The present invention is not limited to the above-mentioned embodiments but may be variously applied. In addition, it will be appreciated by those skilled in the art that various modifications and changes may be made without departing from the appended claims of the present invention.

Claims

A laser welding apparatus for an electrode terminal comprising:

a laser welding head;

a vertical moving part coupled to one side of the laser welding head to be vertically movable;

a pair of tension bars formed at a lower side of the vertical moving part and spaced apart from each other by a predetermined distance;

a pair of pressure rollers rotatably coupled to the tension bars; and

a laser beam irradiation part formed in the laser welding head or the vertical moving part to irradiate a laser beam between the pair of pressure rollers.
The laser welding apparatus for an electrode terminal of claim 1, wherein the vertical moving part includes:

an actuator coupled to one side of the laser welding head;

a moving plate coupled to one side of the actuator and having the pair of tension bars formed at a lower side thereof; and

a guide rod having a lower side coupled to the moving plate and an upper side inserted into a through-hole formed in the laser welding head to be vertically movable.
The laser welding apparatus for an electrode terminal of claim 1, further comprising a lower supporter supporting a lower side of the electrode terminals.
The laser welding apparatus for an electrode terminal of claim 1, further comprising a side supporter supporting outer side surfaces of the electrode terminals.
The laser welding apparatus for an electrode terminal of claim 1, wherein the pair of tension bars have a shape in which a lower side thereof is bent so as to be inclined in a direction in which they face each other, a shape in which they are inclined so that the lower side thereof has a narrow width, or a curved shape.
The laser welding apparatus for an electrode terminal of claim 5, wherein the tension bar is made of an elastic material.
The laser welding apparatus for an electrode terminal of claim 1, wherein the pressure roller has a disk shape or a conical shape.