Patent Application
20240326169
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-050491, filed on Mar. 27, 2023; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a laser welding method.
There is a laser welding method that welds multiple members by irradiating a laser beam. In the laser welding method, for example, the multiple members are welded by irradiating a laser beam after temporarily fixing the multiple members.
In such a laser welding method, there is a risk that bubbles included in the members may become large if the heat amount input in the temporary fixation and/or laser beam irradiation is high. If the bubbles included in the member become large, there is a risk that spatter from the members may occur in the laser beam irradiation; and joining defects may occur. Also, if the bubbles included in the members become large, there is a risk that leakage defects due to the bubbles may occur.
A laser welding method according to an embodiment welds a second member to a first member by irradiating a laser beam. The laser welding method according to the embodiment includes a preparation process and a welding process. The preparation process includes preparing a joining member in which the second member is joined to the first member. The welding process includes welding the second member to the first member by irradiating a laser beam on the joining member. The first member includes a first base member, and a first oxide film formed at a surface of the first base member. The second member includes a second base member, and a second oxide film formed at a surface of the second base member. The preparation process includes removing the first and second oxide films and joining the second base member to the first base member by ultrasonically vibrating the first and second members in a state in which the second member overlaps the first member so that the first oxide film and the second oxide film are in contact. The welding process includes welding the second base member to the first base member by irradiating the laser beam on a portion at which the second base member is joined to the first base member.
Exemplary embodiments will now be described with reference to the drawings.
The drawings are schematic or conceptual; and the relationships between the thickness and width of portions, the proportional coefficients of sizes among portions, etc., are not necessarily the same as the actual values thereof. Furthermore, the dimensions and proportional coefficients may be illustrated differently among drawings, even for identical portions.
In the specification of the application and the drawings, components similar to those described in regard to a drawing thereinabove are marked with like reference numerals; and a detailed description is omitted as appropriate.
As illustrated in
In the laser welding method according to the embodiment, first, the preparation process is performed. In the preparation process, first, as illustrated in
The first member 10 and the second member 20 include, for example, at least one of aluminum, magnesium, or copper. For example, it is favorable for the first and second members 10 and 20 to include aluminum. The material of the second member 20 may be the same as or different from the material of the first member 10.
The first member 10 is, for example, a housing that has an opening part 16. For example, the first member 10 has a substantially rectangular box-shaped structure that is open upward. The first member 10 includes, for example, a first side surface part 11, a second side surface part 12, a third side surface part 13, a fourth side surface part 14, and a bottom surface part 15. The bottom surface part 15 is positioned at the bottom part of the first member 10. The first side surface part 11, the second side surface part 12, the third side surface part 13, and the fourth side surface part 14 each are upright parts that rise upward from the bottom surface part 15. The first side surface part 11 and the third side surface part 13 face each other. The second side surface part 12 and the fourth side surface part 14 face each other. For example, the first member 10 has the opening part 16 formed of the upper end of the first side surface part 11, the upper end of the second side surface part 12, the upper end of the third side surface part 13, and the upper end of the fourth side surface part 14.
The second member 20 is, for example, a lid that covers the opening part 16 of the first member 10. For example, the second member 20 has a flat-plate structure. As illustrated in
Although the first member 10 is a housing and the second member 20 is a lid in the example described herein, the shapes of the first and second members 10 and 20 are not limited to such shapes. It is sufficient that the shapes of the first and second members 10 and 20 can be welded by laser irradiation. For example, the first member 10 and the second member 20 each may have flat plate shapes.
Then, in the preparation process as illustrated in
In the example as illustrated in
Then, in the laser welding method according to the embodiment, the welding process is performed. The welding process is performed after the preparation process. As illustrated in
The laser device that irradiates the laser beam 300 used in the welding process may be, for example, a pulsed laser that produces a pulsed output at a certain repetition frequency (pulse width), or may be a CW (Continuous Wave) laser that continuously produces a certain output. In the case of a pulsed laser, the pulse width is, for example, several femtoseconds or several picoseconds. The wavelength of the laser beam 300 is, for example, not less than 300 nm and not more than 1070 nm.
The preparation process and the welding process will now be described in more detail.
As illustrated in
For example, when the first member 10 and the second member 20 include aluminum, the first base member 10a and the second base member 20a are made of mainly aluminum. For example, when the first member 10 and the second member 20 include aluminum, the first oxide film 10b and the second oxide film 20b are made of mainly aluminum oxide.
The melting point of aluminum oxide (2072° C.) is higher than the melting point of aluminum (660° C.), and so it is necessary to heat to about 2000° C., which is near the melting point of aluminum oxide, in the laser beam irradiation to weld the second member 20 to the first member 10 when oxide films (the first oxide film 10b and/or the second oxide film 20b) are formed at the surfaces of the base members (the first base member 10a and/or the second base member 20a).
In the laser welding method, for example, the multiple members are welded by irradiating a laser beam after the multiple members are temporarily fixed. Conventionally, the temporary fixation is performed by a technique such as temporary welding by irradiating a laser beam, etc.
If, however, the heat amount input in the temporary fixation and/or laser beam irradiation is high, there is a risk that bubbles included in the members may become large. If the bubbles included in the members become large, there is a risk that spatter from the members in the laser beam irradiation may occur, and joining defects may occur. Also, if the bubbles included in the members become large, there is a risk that leakage defects due to the bubbles may occur.
Therefore, according to the embodiment as illustrated in
Thus, in the preparation process, the second base member 20a can be directly joined to the first base member 10a by removing the first oxide film 10b and the second oxide film 20b by ultrasonic vibration. As a result, the joining member 50 in which the second member 20 is joined to the first member 10 can be prepared even when temporary welding by irradiating a laser beam is not performed. Accordingly, compared to when temporary welding is performed by irradiating a laser beam, the heat input amount of the preparation process can be low. As a result, large bubbles included in the first and second members 10 and 20 can be suppressed, and joining defects and leakage defects can be suppressed.
By removing the first oxide film 10b and the second oxide film 20b in the preparation process, the welding process can weld the second member 20 to the first member 10 even without heating to a temperature near the melting point of the first and second oxide films 10b and 20b (by heating only to a temperature near the melting point of the first and second base members 10a and 20a). More specifically, for example, when the first member 10 and the second member 20 include aluminum, the preparation process can weld the second member 20 to the first member 10 even without heating to about 2000° C., which is near the melting point of aluminum oxide (by heating only to about 600° C., which is near the melting point of aluminum). Accordingly, compared to when temporary welding is performed by irradiating a laser beam without joining by ultrasonic vibration, the heat input amount of the welding process can be low. As a result, large bubbles included in the first and second members 10 and 20 can be suppressed, and joining defects and leakage defects can be suppressed.
In the welding method according to the embodiment, the welding process includes irradiating the laser beam 300 on the portion at which the second base member 20a is joined to the first base member 10a. That is, ultrasonic vibration in the preparation process is performed on at least a portion where the laser beam 300 will be irradiated in the welding process. In other words, the portion that is ultrasonically vibrated in the preparation process overlaps at least a portion where the laser beam 300 is irradiated in the welding process. As a result, for example, compared to when the portion ultrasonically vibrated in the preparation process and the portion irradiated by the laser beam 300 in the welding process are different (do not overlap), large bubbles included in the first and second members 10 and 20 can be suppressed, and joining defects and leakage defects can be suppressed.
An ultrasonic vibration device is used as a device that ultrasonically vibrates the first member 10 and the second member 20. For example, the ultrasonic vibration device ultrasonically vibrates the first member 10 and the second member 20 by vibrating an anvil 200 mounted in contact with the second member 20 at a high speed. For example, the anvil 200 of the ultrasonic vibration device may be mounted in contact with the first member 10, or may be mounted in contact with both the first and second members 10 and 20.
Before performing the ultrasonic vibration as illustrated in
When starting the ultrasonic vibration as illustrated in
After performing the ultrasonic vibration as illustrated in
In the laser welding method according to the first embodiment, the preparation process may include temporary welding by irradiating a laser beam in addition to the ultrasonic vibration described above. By temporarily welding by irradiating a laser beam, for example, the joining member 50 in which the second member 20 is more securely joined to the first member 10 can be prepared.
In such a case, it is favorable to perform the joining by ultrasonic vibration before the temporary welding. By performing the joining by ultrasonic vibration before the temporary welding, the heat input amount when temporarily welding can be reduced; therefore, compared to when temporary welding is performed by irradiating a laser beam without joining by ultrasonic vibration, the heat input amount of the preparation process can be reduced. Accordingly, large bubbles included in the first and second members 10 and 20 can be suppressed, and joining defects and leakage defects can be suppressed.
In the laser welding method according to the second embodiment as illustrated in
That is, in the example, the connection portions 30 are provided to be discontinuous at multiple spots over the entire perimeter of the weld portion 25. In other words, the lid (the second member 20) and the opening part 16 of the housing (the first member 10) are discontinuously joined over the entire perimeter. In the example, the connection portions 30 are arranged at uniform spacing around the entire perimeter of the weld portion 25. The spacing between the multiple connection portions 30 may not be uniform spacing.
In the example as well, by performing ultrasonic vibration in the preparation process, the first oxide film 10b and the second oxide film 20b can be removed, and the second base member 20a can be directly joined to the first base member 10a. As a result, the joining member 50 in which the second member 20 is joined to the first member 10 can be prepared even without performing temporary welding by irradiating a laser beam. Accordingly, compared to when temporary welding is performed by irradiating a laser beam, the heat input amount of the preparation process can be reduced. As a result, large bubbles included in the first and second members 10 and 20 can be suppressed, and joining defects and leakage defects can be suppressed.
Embodiments may include the following configurations.
A laser welding method of welding a second member to a first member by irradiating a laser beam, the method comprising:
The method according to configuration 1, wherein
The method according to configuration 2, wherein
The method according to configuration 2, wherein
The method according to any one of configurations 1 to 4, wherein
Thus, according to embodiments, a laser welding method is provided in which joining defects and leakage defects can be suppressed.
For example, the laser welding methods according to embodiments are favorably used to manufacture devices such as secondary batteries, heat exchangers such as heat sinks or the like, gas generators used in airbags or the like, air conditioner rotors, etc.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. Embodiments described above can be implemented in combination with each other.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-050491 | Mar 2023 | JP | national |
