JP3455044B2 - Laser welding method, secondary battery manufacturing method, and laser welding apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method particularly suitable for parts made of aluminum or aluminum alloy and a method of manufacturing a secondary battery container using the welding method.

[0002]

2. Description of the Related Art There are various types of batteries, and it is known that there are secondary batteries such as lithium ion batteries which can be repeatedly charged. As a general structure of such a secondary battery, as shown in FIG. 4, an outer can 2 in which a container body 1 contains an electrode material, an electrolytic solution, and the like, and a cap body for closing an opening of the outer can 2. 3 and 3 form a closed structure. A liquid injection port 4 is formed in the cap body 3, and the liquid injection port 4 is closed by a closing member 5 having a thinner plate thickness than other parts.

In the container body 1 having the above structure, the cap body 3 is joined to the outer can 2, and the joined portion is butt-welded by pulse laser light. Further, the closing member 5 is superposed on the cap body 3, and these superposed portions are superposed and welded by a pulse laser beam.

Aluminum and aluminum alloys have been used as materials for the outer can 2, the cap body 3 and the closing member 5 of the container body 1 in order to reduce the weight. Pulsed aluminum and its alloy materials
When welding with laser light, the thermal diffusion rate is about 10 times as high as that of iron-based materials, so the material is efficiently melted by using pulsed laser light with a high peak output within a pulse width of 1 ms. That is done.

However, aluminum and its alloy materials are likely to be cracked by rapid cooling. Therefore, if pulse laser light with a high peak output is used with a small pulse width of 1 ms in order to melt efficiently, the material may be rapidly cooled after melting, which may cause cracking of the material.

[0006]

As described above, in the case of welding aluminum or its alloy material using pulsed laser light, the pulsed laser has a small pulse width and a high peak output for efficient melting. Since light is used, even if it is possible to improve the melting efficiency, there are cases where the member to be welded is cracked due to rapid cooling after melting.

The present invention has been made in view of the above circumstances, and an object thereof is a laser welding method and a laser welding method capable of efficiently melting a member to be welded and cooling without rapid cooling after the melting. It is to provide a method for manufacturing a secondary battery container using a laser welding method.

[0008]

The present invention provides an aluminum alloy
In the laser welding method of welding a member to be welded, which is made of aluminum, with pulsed laser light, the pulsed laser light has an output of 1
The time t ₁ required to reach the peak value P of × 10 ¹⁰ W / m ² or more is (t1 ≦ 0.8 ms), and the time t ₂ until the output is reduced to half the peak value P ( t ₂ ≦
1.0 ms), the pulse width T is (T ≧ 2.0 ms),
In addition, the laser welding method is characterized in that the output is gradually reduced after the peak value P is reduced to half.

According to the present invention, the secondary battery container is constructed of
Multiple parts made of minium or aluminum alloy
Smell of manufacturing method of secondary battery container welded by pulsed laser light
And the plurality of parts are arranged according to any one of claims 1 to 9.
Specially, the laser welding method described in
It is described in the manufacturing method of the secondary battery container.

The present invention is for welding aluminum or an aluminum alloy provided with a laser oscillator and a control device capable of setting and controlling the pulse waveform of pulsed laser light oscillated and output from this laser oscillator and the peak value P of the output.
In the laser welding apparatus, the peak value P of the output of the pulse laser light set by the controller is 1 × 10.
^{It is 10} W / m ² or more, the time t ₁ until reaching the peak value P is (t ₁ ≦ 0.8 ms), and the time t ₂ until the output is reduced to half of the peak value P is (t ₂ ≤
1.0 ms), the pulse width T is (T ≧ 2.0 ms),
In addition, the laser welding apparatus is characterized in that the output is reduced from the peak value P to 1/2 and then gradually reduced.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the plurality of components block a cap body that closes an opening of an outer can of the secondary battery container and a liquid injection port formed in the cap body. And a welded overlapping portion of these parts.

According to the present invention , by setting the peak value P of the output of the pulsed laser light to 1 × 10 ¹⁰ W / m ² or more, the member to be welded can be melted and welded at a sufficient welding depth , and by output to shorten the time to reach the peak value, it is possible to weld the weld members effectively, is gradually decreased output from the output is reduced to a value of one-half of the peak value, and Pulse width T, pulse width T, T ≧ 2.0 ms
By doing so, it is possible to avoid quenching the member to be welded without increasing the heat input to the member to be welded.

According to the present invention , aluminum or its alloy component of the secondary battery container can be welded while improving the melting efficiency and preventing cracking due to rapid cooling.

[0014]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a laser welding apparatus 11 for carrying out the laser welding method of the present invention.
The laser welding device 11 includes a laser oscillator 12 such as a YAG laser for oscillating and outputting the pulse laser light L.
A control device 13 is connected to the laser oscillator 12 so that the pulse waveform of the pulse laser light L oscillated and output by the control device 13 and the peak value P of the output can be set and controlled. There is.

The pulse laser light L oscillated and output from the laser oscillator 12 is introduced into the optical fiber 14. The pulsed laser light L emitted from the optical fiber 14 enters a condenser lens 15, is focused by the condenser lens 15 and irradiates the container body 1 of the secondary battery container as a member to be welded and scans not shown. The mechanism allows welding at a feed rate of 10 mm / s.

Shield gas is supplied from a nozzle (not shown) to the welded portion of the member to be welded which is irradiated with the pulsed laser light L. An inert gas such as nitrogen, argon or helium is used as the shield gas. This prevents bubbles from being generated by oxygen in the welded portion of the member to be welded.

As shown in FIG. 4, the secondary battery container has a container body 1, which is composed of an outer can 2 and a cap body 3, and a liquid injection port 4 formed in the cap body 3. It is closed by the closing member 5. These parts 2, 3,
4 is formed of aluminum or an aluminum alloy. These aluminum alloys are aluminum alloys containing manganese and magnesium as defined by JIS standards A3001 and A5001.

The outer can 2 and the cap body 3 are butt-welded by the pulse laser beam L as shown in FIG. 5, and the cap body 3 and the closing member 5 are connected to each other as shown in FIG.
As shown in (a) and (b), they are superposed and welded. In this example, the plate thickness of the outer can 2 was 0.3 to 0.5 mm, and the plate thickness at the abutting portion of the cap body 3 was also 0.3 to 0.5 mm. The plate thickness of the cap body 3 itself is 0.1 mm, and the closing member 5
The plate thickness was 0.2 mm.

When welding the respective parts of the container body 1, the pulse laser light L oscillated and output from the laser oscillator 12 at a frequency of 50 Hz is the peak value P and the pulse waveform of the output by the controller 13. And are set to predetermined states.

That is, the output pulse of the pulse laser light L
The black value P is set to a value of 1 × 10 ¹⁰ W / m ² or more, and in this embodiment is set to 2 × 10 ¹⁰ W / m ² . The pulse waveform is set to any one of the shapes shown in FIGS. The input energy of the pulse laser light L was 3 to 4 J per pulse, and the spot diameter was 0.45 mm. Further, the pulse interval is assumed to be equal to or larger than the pulse width.

The peak value P of the output of the pulse laser light L is set to 2
By setting to × 10 ¹⁰ W / m ² , each component of the container body 1 can be melted at a sufficient depth during welding. Here, the melt diameter was 0.8 mm. In FIG. 2, when welding a material made of aluminum or its alloy with the pulse laser beam L, the output pulse of the pulse laser beam L is shown.
The results of experiments on the relationship between the slab value and the melting depth are shown.

As can be seen from FIG. 2, the pulse laser light L
It was confirmed that when the peak value P of 1 becomes ¹⁰ × 10 ¹⁰ W / m ² or more, the energy absorption rate increases and the melting depth rapidly increases. Therefore, as described above, by setting the peak value P of the output of the pulse laser light L to 2 × 10 ¹⁰ W / m ² , the welded portion has a sufficient melting depth to obtain a predetermined welding strength. It can be melted.

The pulse waveform of the pulse laser light L is shown in FIG.
Of (a) to (e), for example, the first waveform A ₁ shown in (a) is set. In this first waveform A ₁ , the time t ₁ from the oscillation until the output reaches the peak value P
Is t ₁ ≦ 0.8 ms, and is set to 0.7 ms in the first waveform A ₁ . The time t ₂ from when the pulse laser light L is output to when it passes the peak value P and decreases to half the peak value P is set to t ₂ ≦ 1.0 ms. .

Further, the output of the pulse laser light L is set to gradually decrease, that is, to gradually decrease until the output of the half value of the peak value P becomes 0. Further, the pulse width T is set to T ≧ 2.0 ms or more, and 2.6 ms in the first waveform A _{1 of} this embodiment.

When the portion to be welded of the container body 1 is irradiated with the pulsed laser light L having the first waveform A ₁ , the time required to reach the peak value P is as short as 0.8 ms or less. Therefore, even if the material of the container body 1 is aluminum or its alloy and the thermal diffusion rate is high, it can be relatively efficiently melted.
That is, when the time t ₁ is set to t ₁ ≦ 0.8 ms, the peak value P of the output of the pulse laser light L is 2 × 10 ¹⁰ W / m ²
In addition to the above setting, the member to be welded can be locally and efficiently welded with a sufficient melting depth.

The time t ₂ from the oscillation of the pulse laser light L until its output reaches the peak value P and then to the output of half the peak value P is set to 1.0 ms or less. By that,
Since (t ₂ -t ₁₎ the relatively short, it is possible to reduce the heat input to the container body 1. As a result, the temperature rise of the container body 1 can be suppressed, so that the PF inside the container body 1
A resin member having a low melting point, such as T, polypropylene, or polyethylene, can be put in as a separator between the positive and negative electrodes wound. Therefore, even when applied to the welding of a container of a secondary battery such as a lithium ion battery, the resin member is not damaged by heat.

The output is gradually decreased from the half of the peak value P until it reaches zero.
Moreover, by setting the pulse width T to 2.6 ms, it is time t ₁ from when the output of the pulse laser light L reaches the peak value P, that is, from the peak value P to the heating time. since 0 time to decrease until the cooling time is (T-t ₁₎ can be increased, it can be moderated in comparison with the cooling rate of the welded member on the heating rate.

Therefore, since the welded portion of the member to be welded of the container body 1 is not rapidly cooled after welding, it is possible to prevent the occurrence of weld cracks at the welded portion. Next, the second to fifth pulse waveforms A _{2 to} A ₅ shown in FIGS. 3B to 3E will be described. First, the second waveform A ₂ has a time t ₁ until the output reaches the peak value P.
It is set to 0.5ms and the peak value P continues to 0.8ms. The time t ₂ required for the output to drop to half the peak value P is 1.0 ms, and the pulse width T is set to 2.0 ms.

In the third waveform A ₃ , the time t ₁ required for the output to reach the peak value P is set to 0.8 ms and the time t ₁ for the peak value P to fall to half the peak value P. ₂ is set to 1.0ms.

The pulse width T is set to 3.0 ms,
1. The process in which the output gradually decreases from half of the peak value P to 0.
From the first taper D ₁ from 0ms to 2.0ms and from 2.0ms
It is divided into a _second tapering portion D ₂ up to 3.0 ms. The first declining portion D ₁ has a slower output reduction rate than the _second gradual reducing portion D ₂ . Therefore, the cooling rate of the welded portion of the member to be welded can be further reduced.

In the fourth waveform A _4, the time t ₁ until the output reaches the peak value P is 0.8 ms, but before that, the output is rapidly increased to about 3/4 of the peak value P. Raise, then 2
The peak value P is raised to a value slightly lower than one-half.

The time t ₂ required for the output to decrease from the peak value P to one half thereof is 1.0 ms, and the cooling process after that is the same as the third waveform A ₃ and the first declining portion D. It is divided into ₁ and a second tapering portion D ₂ . The first tapering portion D ₁ is 1.0 ms
From 1.0 to 2.0 ms, the second taper D ₂ is 2.0 ms
From 4.0ms to 2.0ms. Further, the pulse width T is set to 4.0 ms.

In the fifth waveform A ₅ , the time t ₁ required for the output to reach the peak value P is set to 0.8 ms, and the time t ₂ required for the output value to fall to half the peak value P _2. Is set to 1.0 ms. The process until the output decreases from ½ of the peak value P to 0 is the first declining portion D ₁ and the second declining portion D _2, and the first declining portion D ₁ is From 1.0 ms to 2.0 ms, the second tapering portion D ₂ is up to 3.0 ms. Therefore, the pulse width T is set to 3.0 ms. In addition,
In the fifth waveform A ₅ , the rising curve until the output reaches the peak value P is not a straight line, but is bent in the middle.

The present invention is not limited to the above embodiment and can be variously modified. For example, the pulse waveform used in the present invention is not limited to the above-mentioned first to fifth pulse waveforms, but the time t ₁ until the peak value is reached and the output is halved of the peak value P. Any shape can be applied as long as the time t ₂ until it decreases to 1 and the pulse width T satisfy certain conditions, and the output gradually decreases from the peak value P to 1/2 and then gradually decreases. .

Further, the outer can 2 and the cap body 3 are shown in FIG.
As shown in, the cap body 3 may be fitted in the opening of the outer can 2 and the joining portion may be irradiated with the pulse laser light L and welded.

Further, the member to be welded is not limited to the secondary battery container, but may be any other member. In short, it is required that the member to be welded is efficiently melted and cracks of the member to be welded due to rapid cooling are prevented. Can be applied to welding.

[0038] This invention is to a peak value of the output of the pulse laser beam to 1 × ^{10 10} W / ^{m 2} or more, the time _{t 1} until the output reaches the peak value P t1 ≦ 0.8
ms, and the time t ₂ required for the output to drop to ½ of the peak value is t ₂ ≦ 1.0 ms, and the output is ½.
After decreasing to below, the output was gradually decreased and the pulse width T was set to T ≧ 2.0 ms.

Therefore, not only can the member to be welded be melted and welded at a depth sufficient to secure a predetermined welding strength,
Even if the member to be welded is a material with a high thermal diffusion rate, it can be melted efficiently and its output is a peak value of 2
It is possible to prevent the heat input to the member to be welded from increasing by setting the time until it decreases to one-half of the value. It is possible to prevent the member from being rapidly cooled and cracking.

According to the present invention , a part made of aluminum or its alloy having a high thermal diffusion rate in a secondary battery container is improved in thermal melting efficiency and cracked by rapid cooling.
It is possible to prevent welding from occurring and perform welding. Moreover, since the heat input to the secondary battery container can be reduced, even if a material having low heat resistance is housed inside the transfer container, it is possible to prevent the parts from being damaged.

According to the present invention, the outer can of the secondary battery container and the cap body can be welded with a pulsed laser beam with a sufficient melting depth and without causing cracking. From this
According to the description, the cap body of the secondary battery container and the closing member of the liquid injection port can be welded with a pulse laser beam with a sufficient melting depth and without causing cracking.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a laser welding apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the output of pulsed laser light and the melting depth.

3A to 3E are explanatory diagrams of pulse waveforms having different shapes.

FIG. 4 is a perspective view illustrating a secondary battery container.

FIG. 5 is a sectional view of a welded portion between an outer can and a cap body.

6A is a plan view of a welded portion between a cap body and a closing member, and FIG. 6B is a sectional view of the same.

FIG. 7 is a cross-sectional view of a welded portion when the cap body is fitted in the outer can and then they are welded.

[Explanation of symbols]

1 ... Container body 2… Outer can 3 ... Cap body

Continuation of the front page (56) Reference JP-A-6-210472 (JP, A) JP-A-50-110950 (JP, A) JP-A-3-5090 (JP, A) JP-A-56-138231 (JP , A) JP-A-8-77983 (JP, A) JP-A-6-53579 (JP, A) Actual Kaihei 5--11164 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) B23K 26/00-26/42 H01M 2/02

Claims (17)

(57) [Claims] 1. A laser welding method for welding a member to be welded made of aluminum with pulsed laser light, wherein the pulsed laser light has a time until the output reaches a peak value P of 1 × 10 ¹⁰ W / m ² or more. When t ₁ is (t ₁ ≦ 0.8 ms), the time t until the output drops to half the peak value P
₂ is (t ₂ ≦ 1.0 ms), the pulse width T is (T ≧ 2.0 ms), and the output is gradually reduced from the peak value P to half and then gradually reduced. Method. 2. A laser welding method for welding a member to be welded made of an aluminum alloy with pulsed laser light, wherein the pulsed laser light reaches a peak value P at which the output is 1 × 10 ¹⁰ W / m ² or more. Time t ₁ is (t1 ≦ 0.8 ms), and time t until the output drops to half the peak value P
₂ is (t ₂ ≦ 1.0 ms), the pulse width T is (T ≧ 2.0 ms), and the output is gradually reduced from the peak value P to half and then gradually reduced. Method. 3. The laser welding method according to claim 2 , wherein the member to be welded is an aluminum alloy containing manganese. Wherein said member to be welded is claim, characterized in that an aluminum alloy containing magnesium 2
The described laser welding method. Wherein said time t1 is claim 1 or claim 2 laser welding method wherein a is 0.7 ms. 6. The peak value P is 2 × 10 ¹⁰ W / m
^2. The laser welding method according to claim 1, wherein the laser welding method is 2 . Wherein said pulse width T is claim 1 or claim 2 laser welding method wherein a is 2.6 ms. 8. The time t ₁ is 0.5 ms, and after the peak value P is continued at 0.8 ms, the time t ₁ is
₂ is 1.0 ms, according to claim 1 or claim 2 laser welding method, wherein said pulse width T is 2.0 ms. 9. A method for manufacturing a secondary battery container, comprising welding a plurality of parts made of aluminum or aluminum alloy, which form the secondary battery container, with a pulsed laser beam, wherein each of the plurality of parts is defined by any one of claims 1 to 8 . A method for manufacturing a secondary battery container, which comprises welding using the laser welding method described in 1. 10. The plurality of parts and the outer can of a secondary battery container, and the cap member and for closing the opening of the outer can, claim, characterized in that welding the butted portions of these components 9 A method for producing the described secondary battery container. 11. The plurality of parts are a cap body for closing an opening of an outer can of a secondary battery container and a closing member for closing a liquid injection port formed in the cap body. claim 9, characterized in that welding the
A method for producing the described secondary battery container. 12. An aluminum comprising a laser oscillator and a control device capable of setting and controlling a pulse waveform of pulsed laser light oscillated and output from the laser oscillator and a peak value P of the output.
In a laser welding apparatus for welding a nickel or aluminum alloy, the pulse laser light set by the controller has an output peak value P of 1 × 10 ¹⁰ W / m ² or more and reaches the peak value P. Until the time t ₁ reaches (t ₁ ≦ 0.
8 ms), the time t until the output drops to half of the peak value P
₂ is (t ₂ ≦ 1.0 ms), the pulse width T is (T ≧ 2.0 ms), and the output is gradually reduced from the peak value P to half and then gradually reduced. apparatus. 13. An optical fiber into which the pulsed laser light is introduced, and a condenser lens that focuses the pulsed laser light emitted from the optical fiber.
12. The laser welding device according to item 12 . 14. The laser welding apparatus according to claim 12 , wherein the time t ₁ is 0.7 ms. 15. The peak value P is 2 × 10 ¹⁰ W / m.
Laser welding device according to claim 12, characterized in that the ^2. 16. The laser welding apparatus according to claim 12 , wherein the pulse width T is 2.6 ms. 17. The time t ₁ is 0.5 ms,
The laser welding apparatus according to claim 12 , wherein the time t ₂ is 1.0 ms and the pulse width T is 2.0 ms after the peak value P is continued at 0.8 ms.