JP7754751B2 - Plate material, joined body, plate material joining method, and plate material manufacturing method - Google Patents

Description

The present invention relates to plate materials, joined bodies, methods for joining plate materials, and methods for manufacturing plate materials.

For example, when joining copper alloy sheets together to produce heat dissipation components such as vapor chambers or electronic components, the sheets are joined by brazing or caulking. However, these joining methods have low productivity and require high equipment costs. In contrast, a joining method that involves laser welding copper alloy sheets together can achieve high productivity while keeping costs down.

Patent Document 1 shows a vapor chamber constructed by welding one plate-shaped member to another. In this vapor chamber, the thickness of the molten portion of one plate-shaped member is thinner than the thickness of the molten portion of the other plate-shaped member.

Patent Document 2 also shows that a surface layer made of a metal material that has a high laser light absorption rate and a higher breaking strength than the metal material is formed on one surface of overlapping metal components, and that laser light is irradiated from above the surface layer to form a re-solidified portion from the surface of the surface layer to the interior of the metal component, thereby joining the two metal components.

International Publication No. 2018/147283 International Publication No. 2012/124255

Laser welding is highly productive because it can be done at high speeds, and is gaining attention as a joining method for sealing gaps between plates.
In order to reduce the size and weight of copper or copper alloy sheets used in heat dissipation components, for example, thinning to a total thickness of 0.3 mm or less is required. Copper has a known characteristic of low laser absorption in the solid state, but a sharp increase in laser absorption in the molten state. Therefore, when joining copper or copper alloy sheets by laser welding, the molten pool is unstable, and defects such as blowholes are likely to occur. In particular, defects such as burn-through may occur in extremely thin sheets.

When laser welding thin copper or copper alloy sheets together, as in Patent Document 1, simply increasing the thickness of a portion of the sheet or forming a surface layer on the surface irradiated with laser light, as in Patent Document 2, does not adequately prevent defects such as blowholes and burn-through. Furthermore, the technology in Patent Document 1 increases the thickness of the fused portion of one of the plate-shaped members, resulting in increased weight. Furthermore, the technology in Patent Document 2 makes it difficult to join members whose surface cannot be plated.

The present invention therefore aims to provide plate materials that can be smoothly laser welded together while sufficiently minimizing the occurrence of defects such as blowholes and burn-through, a joined body in which this plate material is joined to a plate material to be joined, a method for joining plate materials, and a method for manufacturing plate materials.

The present invention comprises the following configurations.
(1) A plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded,
a surface to be irradiated with the laser beam has a plurality of grooves intersecting the scanning direction of the laser beam and spaced apart along the scanning direction of the laser beam;
Board material.
(2) The plate material according to (1) is joined to the joined side plate material by a bead formed in a direction intersecting the groove portion.
zygote.
(3) The plate material described in (1) is superimposed on the plate material to be joined,
a laser beam is irradiated along a direction intersecting the plurality of grooves formed in the plate material, thereby laser welding the plate material to the joined side plate material;
How to join boards.
(4) A method for manufacturing a plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded, comprising:
a plurality of grooves intersecting the scanning direction of the laser light are provided at intervals along the scanning direction of the laser light on an irradiated portion to be irradiated with the laser light during laser welding by laser processing, rolling processing, or press processing;
Manufacturing method of boards.

The present invention enables smooth laser welding to join plate materials while sufficiently minimizing the occurrence of defects such as blowholes and burn-through.

FIG. 2 is a perspective view schematically showing a state in which a plate material and a plate material to be joined are laser-welded together. FIG. 2 is a plan view showing a groove formed in a plate material. FIG. 4 is an enlarged plan view of a portion of the plate showing grooves formed in the plate. FIG. 10 is a plan view showing a state in which a plate material and a plate material to be joined are laser-welded together. FIG. 2 is a plan view of a joined body in which a plate material and a plate material to be joined are laser-welded. FIG. 10 is a plan view of a portion of a joined body in which grooves of other shapes are formed and laser welded. 10 is an image of a plate material with grooves formed therein. 10 is an image of the laser light irradiated side of a joined body in which a plate material and a plate material to be joined are joined. 10 is an image of the side opposite to the laser light irradiation side in a joined body in which a plate material and a plate material to be joined are joined. 10 is an image of a cross section of a joint portion in a joined body in which a plate material and a plate material to be joined are joined. This is an image of the rear side of a plate material in a state where the plate material has not been sufficiently melted by the laser light and has not been penetrated. This is an image of the back side of a plate material in a state where melt-through has occurred due to laser light. 1 is a graph showing appropriate output ranges of laser light in examples and comparative examples. 10 is an image of the irradiated side of a plate material irradiated with laser light at the lower limit output in an example. 10 is an image of the side opposite to the irradiated side of a plate material irradiated with laser light at the lower limit output in an example. 10 is an image of the irradiated side of a plate material irradiated with laser light at the lower limit output in a comparative example. 10 is an image of the side opposite to the irradiated side of a plate material irradiated with laser light at the lower limit output in a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view that schematically shows how a plate material 11 and a plate material 13 to be joined are laser-welded together.

In this embodiment, the plate material 11 is joined to another plate material, the plate material to be joined (joined-side plate material) 13, by laser welding. The plate materials 11 and 13 are partially overlapped with each other, and this overlapping portion becomes the irradiated portion 15. The irradiated portion 15 is then irradiated with laser light L by the laser irradiation device 100, thereby laser welding the plate material 11 and the plate material to be joined 13. The laser light L is irradiated onto at least a portion of the irradiated portion 15, and does not extend beyond the irradiated portion 15.

The plates 11 and 13 are made of copper or a copper alloy. In the case of a copper alloy, the components contained in copper (Cu) include tin (Sn), nickel (Ni), zinc (Zn), magnesium (Mg), or phosphorus (P). Thin plates with a thickness of 0.10 mm to 1.0 mm are used as the plates 11 and 13. The thicknesses of the plates 11 and 13 may be the same, or one may be thicker than the other.

Fig. 2 is a plan view showing the grooves 21 formed in the plate material 11. Fig. 3 is an enlarged plan view of a portion of the plate material 11 showing the grooves 21 formed in the plate material 11.
As shown in FIGS. 2 and 3, a plurality of grooves 21 are arranged at intervals along the scanning direction A of the laser light L on the surface of the irradiated portion 15 of the plate material 11 that is irradiated with the laser light L.

Each groove 21 has a width dimension W that is 1 to 2 times the thickness of the plate material 11, a depth dimension D that is 1/3 or less the thickness of the plate material 11, and a pitch P that is 2 to 4 times the thickness of the plate material 11.

An example of a laser irradiation device 100 that irradiates the irradiated portion 15 with laser light L for laser welding is one equipped with a galvanometer scanner unit. In a laser irradiation device 100 equipped with a galvanometer scanner unit, a laser from a fiber laser oscillator is reflected by a galvanometer mirror, focused by a lens, and irradiated onto the irradiated portion 15. With this laser irradiation device 100, the laser light L can be scanned at high speed and with high precision by controlling the angle of the galvanometer mirror attached to the rotating shaft. However, the laser irradiation device 100 is not limited to this and may be an irradiation device of another type.

Next, a joining method for laser welding the plate material 11 and the plate material 13 to be joined according to this embodiment will be described.
(Formation of grooves)
A plurality of grooves 21 are formed in the plate material 11. The grooves 21 are formed by laser processing. Specifically, the laser beam L is wobbled while the laser irradiation device 100 is moved along the scanning direction A in the irradiated portion 15. As a result, the laser beam L is irradiated intermittently onto the irradiated portion 15 while periodically rotating, and a plurality of grooves 21 are formed at intervals along the scanning direction A. By forming the grooves 21 in the plate material 11 by laser processing in this way, laser welding to the plate material 13 on the joining side, which is performed after processing the grooves 21, can be performed in one go, simplifying the manufacturing process.

The grooves 21 can be formed not only by laser processing using the laser irradiation device 100, but also by rolling or pressing. When the grooves 21 are formed by rolling or pressing, a general manufacturing line can be used, which helps prevent increases in manufacturing costs.

(Laser welding)
Next, the plate material 11 with the grooves 21 formed therein is placed on the plate material 13 to be joined. Then, the laser beam L from the laser irradiation device 100 is scanned over the irradiated portion 15 of the plate material 11 placed on the plate material 13, from one end 15a to the other end 15b of the irradiated portion 15. As a result, as shown in FIG. 4 , the laser beam L is irradiated along the scanning direction A that intersects with the plurality of grooves 21 of the plate material 11, and a bead 23 is formed by laser welding the plate material 11 and the plate material 13 together.

When laser welding is performed using laser light L from the laser irradiation device 100, the irradiated portion of the joint (irradiated portion 15) between the plate material 11 and the plate material 13 to be joined is melted at the irradiated portion, from the irradiated surface to the back surface of the plate material 13 to be joined, opposite the side irradiated with the laser light L. This melted portion cools, solidifies, and hardens, forming a continuous bead 23 in a direction intersecting the groove portion 21, as shown in Figure 5. This results in a joined body 25 in which the plate material 11 and the plate material 13 to be joined are well joined.

As explained above, with the plate material 11 configured as described above, by irradiating the laser light L so that it intersects with the multiple grooves 21, heat input is promoted from the thinner portions of the plate where the grooves 21 are located. This allows a molten pool to be formed with low output, and laser welding to the plate material 13 to be joined can be performed smoothly while sufficiently suppressing the occurrence of defects such as blowholes and burn-through. Furthermore, when laser welding to the plate material 13 to be joined, the output range of the laser light L that can be welded is expanded, allowing for high-quality and easy joining of the plate material 11 and the plate material 13 to be joined.

In particular, copper and copper alloys have a low laser light absorption rate of 5% or less in the solid state, but this rate rapidly increases to several tens of percent or more once molten. Therefore, once melted, the molten pool becomes unstable, prone to defects such as spatter and blowholes, and burn-through occurs more easily in thin-walled plates. However, by forming multiple grooves 21 in the plate material 11 in advance and irradiating the laser light so that it intersects with the grooves 21 as described above, rapid melting is suppressed. In other words, in this configuration, appropriately thin sections are interspersed along the scanning direction A of the laser light L. As a result, melting begins in the thin sections of the grooves 21 due to thermal conduction, and heat is conducted toward the periphery of the formed molten pool, resulting in heating of an area wider than the laser irradiation zone. While increased laser light energy absorption occurs in the molten area, this, combined with thermal diffusion to the surrounding area, suppresses rapid melting. Therefore, melting begins even at low laser beam power, and even at high power, excessive heat input is suppressed due to thermal diffusion from the areas that began to melt earlier. This expands the range of laser beam power that can be welded.

The above effects are most pronounced when the width of the grooves 21 is optimized to be 1 to 2 times the plate thickness, the depth D of the grooves 21 to be 1/3 or less of the plate thickness, and the pitch of the grooves 21 to be 2 to 4 times the plate thickness.

By laser welding the plate material 11 and the plate material 13 to be joined in this manner, a high-quality joined body 25 is obtained in which the plate material 11 and the plate material 13 to be joined are joined with a bead 23 formed in a direction intersecting the groove 21.

Furthermore, with this method of joining plate materials, the plate material 11 is overlapped with the plate material 13 to be joined, and laser light L is irradiated along a direction intersecting the multiple grooves 21, thereby enabling the plate material 11 and the plate material 13 to be joined to be joined well while suppressing burn-through.

Furthermore, when manufacturing a plate material 11 with multiple grooves 21, the formation of the grooves 21 by laser processing and laser welding to the plate material 13 to be joined can be performed in one step, simplifying the manufacturing process. Furthermore, when forming the grooves 21 by rolling or pressing, a general rolling or pressing production line can be used, thereby reducing manufacturing costs for manufacturing plate material 11 made of copper or copper alloy and having grooves 21.

In the above configuration example, the laser irradiation device 100 is moved along the scanning direction A while the laser beam L is wobbled to form multiple curved grooves 21. However, the scanning pattern of the laser beam L is arbitrary. For example, as shown in FIG. 6, the grooves 21 may be linear. When joining the plate material 11 to the plate material 13 to be joined, the laser beam L may be irradiated along the scanning direction A, which intersects with the multiple linear grooves 21, to laser weld the plate material 11 and the plate material 13 to be joined. In this case, too, laser welding between the plate material 11 and the plate material 13 to be joined can be performed smoothly while sufficiently suppressing the occurrence of defects such as blowholes and burn-through. Furthermore, when laser welding to the plate material 13 to be joined, the output range of the laser beam L that can be used for welding is expanded, making it easier to weld both materials.

The plate material 11, to which the grooves 21 had been created by laser processing, was placed on the plate material 13 to be joined and laser welded to produce a joined body 25. The front, back, and cross section of the welded portion of the joined body 25 were observed and evaluated. The plate material 11 and the plate material 13 to be joined were copper alloy plates with a thickness of 0.15 mm.

(Formation of grooves)
FIG. 7 is an image of the plate material 11 in which the grooves 21 are formed.
7, a plurality of grooves 21 were formed in the plate material 11. The laser processing of the grooves 21 was performed under the conditions of a laser beam scanning pattern of circular wobbling with a diameter of 1.6 mm and a frequency of 100 Hz, an output of 3 kW, and a welding speed of 7 m/min.

(Laser welding)
The plate material 11 provided with the grooves 21 was placed on the plate material 13 to be welded, and laser welding was carried out under the conditions of an output of 3 kW and a welding speed of 10 m/min.

(Evaluation results)
Figures 8A to 8C are images of a bonded body 25 formed by bonding plate material 11 and plate material 13, where Figure 8A is an image of the side irradiated with laser light, Figure 8B is an image of the side opposite to the side irradiated with laser light, and Figure 8C is an image of a cross section at the bonded location.

As shown in Figure 8A, a linear bead 23 was formed by laser welding on the surface of the plate material 11 on the side irradiated with the laser beam L, in a direction intersecting the groove portion 21. Furthermore, as shown in Figure 8B, a linear bead 23 was also formed on the surface of the plate material 13 on the side to be joined, opposite the side irradiated with the laser beam L, with the bead width being substantially uniform with minimal variation in the longitudinal direction, and no signs of burn-through. Furthermore, as shown in Figure 8C, a bead 23 was formed at the joint between the plate material 11 and the plate material 13 on the side to be joined, penetrating evenly throughout the thickness direction. In this way, a joined body 25 was obtained, with a weld that was stable in both appearance and cross-section.

A laser beam was irradiated linearly onto copper alloy plate materials P1 and P2. The front and back surfaces of the laser beam irradiated areas were then observed to investigate the laser beam output range that could be welded.

Figures 9A and 9B are images of the back side of bare plate material Pb irradiated with laser light. Figure 9A is an image of the plate material Pb in a non-penetrating state where the laser light has not sufficiently melted it, and Figure 9B is an image of the plate material Pb in a state where burn-through has occurred.

To investigate the appropriate laser beam output range, we checked for non-penetration (see Figure 9A) and burn-through (see Figure 9B) on the backside of the laser beam irradiated area, and determined the output power range in which non-penetration and burn-through did not occur.

<Plate material>
(Example)
Plate material P1: A copper alloy plate having a thickness of 0.2 mm and provided with a plurality of linear grooves N with a groove width of 190 μm and a pitch of 420 μm (comparative example)
Plate material P2: A copper alloy plate having a thickness of 0.2 mm and made of bare material without grooves

<Laser light irradiation conditions>
(Example)
The laser beam was irradiated linearly along the scanning direction intersecting the plurality of grooves N at a scanning speed of 10 m/min.
(Comparative Example)
The laser beam was irradiated linearly at a scanning speed of 10 m/min.

<Evaluation Results>

Figure 10 is a graph showing the laser light output ranges for the examples and comparative examples.

(Example)
As shown in FIG. 10, in the example, when laser light was irradiated at an output in the range of 2.0 kW to 2.6 kW, non-penetration and burn-through did not occur.

Figures 11A and 11B are images of the appearance of the irradiated area when laser light is irradiated at the minimum output in this example. Figure 11A is an image of the side irradiated with the laser light, and Figure 11B is an image of the side opposite to the side irradiated with the laser light.

In the example, at a laser output of 2.0 kW, a linear bead B intersecting multiple grooves N was formed on the side irradiated with the laser light, as shown in Figure 11A, and a linear bead B free of defects such as blowholes and burn-through was formed on the side opposite to the side irradiated with the laser light, as shown in Figure 11B.

(Comparative Example)
As shown in FIG. 10, in the comparative example, when laser light was irradiated at an output in the range of 2.2 kW to 2.6 kW, non-penetration and burn-through did not occur.

Figures 12A and 12B are images of the appearance of the irradiated area when laser light was irradiated at the lowest output in the comparative example. Figure 12A is an image of the side irradiated with the laser light, and Figure 12B is an image of the side opposite to the side irradiated with the laser light.

In the comparative example, at a laser output of 2.2 kW, a linear bead B was formed on the side irradiated with the laser light, as shown in Figure 12A. Furthermore, a linear bead B without defects such as blowholes or burn-through was formed on the side opposite to the side irradiated with the laser light, as shown in Figure 12B.

In this way, by forming multiple grooves on the surface of the plate material to be irradiated with laser light and irradiating the laser light so that it intersects these grooves, it was found that the weldable output range of the laser light during laser welding is expanded compared to when no grooves are added, making it easier to join.

As such, the present invention is not limited to the above-described embodiments, and the invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the disclosures in the specification and well-known technology, and these modifications and applications are within the scope of the protection sought.

As described above, the present specification discloses the following:
(1) A plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded,
A plate material having a surface to be irradiated with laser light, on which a plurality of grooves intersecting the scanning direction of the laser light are provided at intervals along the scanning direction of the laser light.
With this plate material, by irradiating the laser beam so that it intersects with the multiple grooves, heat input is promoted from the thinner portions of the plate where the grooves are located. This allows for the formation of a molten pool at low power, and allows smooth laser welding to the plate material to be joined while sufficiently suppressing the occurrence of defects such as blowholes and burn-through. In addition, the weldable output range of the laser beam when laser welding to the plate material to be joined can be expanded, making joining easier.

(2) The plate material according to (1), wherein the grooves have a width dimension of 1 to 2 times the plate thickness, a depth dimension of 1/3 or less of the plate thickness, and a pitch of 2 to 4 times the plate thickness.
With this plate material, by optimizing the width, depth, and pitch of the grooves, portions with a moderate thickness are arranged along the scanning direction of the laser light, which prevents excessive heat input to the thin-walled portions having the grooves due to thermal conduction and suppresses burn-through when welding the plate material to the plate material to be joined.

(3) A joined body in which the plate material according to (1) or (2) is joined to the plate material to be joined by a bead formed in a direction intersecting the groove portion.
According to this bonded body, the plate material and the plate material to be bonded are bonded well by the beads formed in a direction intersecting the grooves.

(4) The plate material according to (1) or (2) is superimposed on the plate material to be joined,
A method for joining plate materials, comprising: irradiating the plate material with laser light in a direction intersecting with a plurality of grooves formed in the plate material, thereby laser welding the plate material to the plate material to be joined.
According to this method for joining plate materials, the plate material is overlapped on the plate material to be joined, and laser light is irradiated along a direction that intersects with the multiple grooves, thereby enabling the plate material and the plate material to be joined to be joined well while suppressing burn-through.

(5) A method for manufacturing a plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded, comprising:
A method for manufacturing a plate material, comprising providing a plurality of grooves intersecting a scanning direction of the laser light at intervals along the scanning direction of the laser light in an irradiated portion that is irradiated with the laser light during laser welding by laser processing, rolling processing, or press processing.
According to this method for manufacturing a plate material, when the grooves are formed by laser processing, processing of the grooves and laser welding to the plate material to be joined can be performed in one step, simplifying the manufacturing process. Furthermore, when the grooves are formed by rolling or pressing, a general manufacturing line can be used, so that a plate material made of copper or a copper alloy and having grooves can be manufactured at low manufacturing costs.

11 Plate material 13 Plate material (side plate material to be joined)
21 Groove portion 23 Bead 25 Bonded body A Scanning direction L Laser light P Pitch W Width dimension

Claims (4)

A plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded,
a plurality of grooves intersecting a scanning direction of the laser light are provided at intervals along the scanning direction of the laser light on a surface to be irradiated with the laser light;
The grooves have a width dimension that is 1 to 2 times the plate thickness, a depth dimension that is 1/3 or less of the plate thickness, and a pitch that is 2 to 4 times the plate thickness.
Board material. A welding method comprising the plate material according to claim 1 and the side plate material to be joined,
The plate material has a joining portion overlapping the joined side plate material, and a bead formed along the joining portion in a direction intersecting the groove portion.
zygote. The plate material according to claim 1 is placed on the plate material to be joined ,
a laser beam is irradiated along a direction intersecting the plurality of grooves formed in the plate material, thereby laser welding the plate material to the joined side plate material;
How to join boards. A method for manufacturing a plate material made of copper or a copper alloy that is overlapped with a joined side plate material made of copper or a copper alloy and laser welded, comprising:
a plurality of grooves intersecting a scanning direction of the laser light are provided at intervals along the scanning direction of the laser light by laser processing, rolling processing, or press processing in an irradiated portion to be irradiated with the laser light during laser welding;
The grooves have a width dimension that is 1 to 2 times the plate thickness, a depth dimension that is 1/3 or less of the plate thickness, and a pitch that is 2 to 4 times the plate thickness.
Manufacturing method of boards.