Welding method, manufacturing method of cooling device, and cooling device

Abstract

To suppress influence of a gas existing in a metal member on welding.SOLUTION: In a welding method, laser welding is performed with a first member 11 and a second member 12 being overlapped. The welding method includes: pre-processing in which a laser beam 20 is radiated to a radiation target area 126 which is a welding area of the second member 12 before the first member 11 and the second member 12 are overlapped; and welding processing in which the first member 11 and the second member 12 are overlapped after the pre-processing and the laser beam 20 is radiated to the first member 11 in the welding area to weld the first member 11 and the second member 12 to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a welding method, a method for manufacturing a cooling device, and a cooling device. [Background technology]

[0002] In so-called lap joint welding, in which two overlapping metal members are joined by irradiating them with laser light, a technique is known that prevents the formation of blowholes by allowing gas generated from the metal members during welding to escape to the outside (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-6376 Summary of the Invention [Problem to be solved by the invention]

[0004] Die-cast materials, which are formed by pouring molten non-ferrous metals into a mold, are suitable for products with high dimensional accuracy and complex shapes, and can be mass-produced, reducing manufacturing costs. However, gas compressed during casting can remain inside die-cast materials, so when attempting to weld a lap joint, the gas inside the die-cast material may appear as bubbles in the molten pool or the gas pool may explode. In this case, the gas that was not released to the outside during welding may form blowholes, causing hole defects called voids. The occurrence of voids can lead to poor welding, which is a defect that appears in the appearance and inside of the weld, a decrease in the strength of the weld, and a decrease in the airtightness of the weld. An object of the present invention is to suppress the influence of gas present inside a metal member on welding. [Means for solving the problem]

[0005] The present invention, which was completed with respect to this object, is a welding method for overlapping a first member and a second member and laser welding them, the welding method including: a pretreatment step of irradiating a welding area, which is an area of ​​the second member where welding is to be performed, with laser light before overlapping the first member and the second member; and a welding process step of overlapping the first member and the second member after the pretreatment step, and irradiating the first member in the welding area with laser light to weld the first member and the second member. Here, the second member may be formed by casting. The second member may be formed by a die casting method. Furthermore, a depth to which the second member is melted in the pretreatment may be deeper than a depth to which the second member is melted in the welding treatment. Moreover, the output of the laser light irradiation in the pretreatment may be smaller than the output of the laser light irradiation in the welding treatment. Moreover, the output of the laser light irradiation in the pretreatment may be set to the same value as the output of the laser light irradiation in the welding treatment. In addition, the present invention, which was completed with the above-mentioned objective in mind, is a manufacturing method for a cooling device that includes a main body formed by casting and that contains a liquid, and a cover that is overlaid on the main body so as to cover an opening of the main body, the manufacturing method for a cooling device including a pretreatment process in which laser light is irradiated to a peripheral portion of the main body that surrounds the opening before overlaying the cover, and a welding process in which, after the pretreatment, the cover is overlaid and laser light is irradiated to the portion of the cover that overlaps with the peripheral portion to perform laser welding. Furthermore, the present invention, which was completed with the above objective in mind, is a cooling device in which a main body for containing liquid and a cover covering an opening of the main body are joined by laser welding in an overlapping state, in which, before the cover is overlapped with the main body, a laser beam is irradiated to a welding area around the opening where laser welding is performed, and after the cover is overlapped with the main body, a laser beam is irradiated to a portion of the welding area opposite the main body to the main body, thereby joining the cover to the main body. Effect of the Invention

[0006] According to the present invention, the influence of gas present inside the metal member on welding can be suppressed. [Brief description of the drawings]

[0007] [Figure 1] Fig. 1(A) is a perspective view showing an example of the external configuration of a cooling device according to the present embodiment, and Fig. 1(B) is a bottom view showing an example of the external configuration of a cooling device. [Diagram 2] 1A is a diagram showing a pretreatment process in the manufacturing process of a cooling device, and FIG. 1B is a diagram showing a state after the pretreatment process. [Diagram 3] FIG. 1A is a diagram showing a welding process in the manufacturing process of the cooling device 1. FIG. 1B is a diagram showing the state after the welding process has been performed. [Figure 4] (A) is a plan view showing a part of the surface of a welded part of a cooling device manufactured by lap-welding a first member and a second member after pretreatment, and (B) is an X-ray CT image of the inside of the welded part of a cooling device manufactured by lap-welding a first member and a second member after pretreatment, near the joint interface. [Diagram 5] (A) is a plan view showing a part of the surface of a weld when two metal members are lap-welded without pretreatment, and (B) is an X-ray CT image of the inside of the weld near the joint interface when two metal members are lap-welded without pretreatment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0009] (Cooling system configuration) Fig. 1(A) is a perspective view showing an example of the external configuration of a cooling device 1 according to the present embodiment, and Fig. 1(B) is a bottom view showing an example of the external configuration of the cooling device 1. As shown in FIG. 1(A), the cooling device 1 is manufactured by stacking a first member 11 arranged on the upper side in the vertical direction and a second member 12 arranged on the lower side in the vertical direction and laser welding these members. The first member 11 is a metal member having an upper surface 111 and a lower surface 112, and functions as a cover part of the cooling device 1. The second member 12 is a metal member having an upper surface 121 and a lower surface 122, and functions as a main body of the cooling device 1. In this embodiment, both the first member 11 and the second member 12 are die-cast materials.

[0010] 1(A) and (B), holes 123 and 124 are formed in the bottom surface of the cooling device 1 (the lower surface 122 of the second member 12). A spatial region 125 indicated by a dashed line is formed inside the cooling device 1. One of the holes 123 and 124 functions as a hole used when supplying a fluid (liquid or gas) that serves as a refrigerant for the cooling device 1 to the spatial region 125. The other hole functions as a hole used when discharging the refrigerant passing through the spatial region 125 to the outside.

[0011] For example, when hole 123 is made to function as a hole for supplying a refrigerant to spatial region 125, a first pipe (not shown) for supplying a refrigerant to cooling device 1 is connected to hole 123. Then, when hole 124 is made to function as a hole for discharging the refrigerant passing through spatial region 125 to the outside, a second pipe (not shown) for discharging the refrigerant from cooling device 1 is connected to hole 124. In this case, the refrigerant supplied to the inside of cooling device 1 through the first pipe cools first member 11 and second member 12 while passing through spatial region 125, and is discharged to the outside of cooling device 1 through the second pipe. Thereby, by arranging an object to be cooled (for example, a heat sink, etc.) on the upper side of first member 11, the object to be cooled is cooled.

[0012] (Manufacturing method of cooling device) FIG. 2A is a diagram showing a pretreatment process in the manufacturing process of the cooling device 1. As shown in FIG. FIG. 2(A) shows a part of the cross section of the second member 12. The manufacturing process of the cooling device 1 includes a pretreatment and a welding process. The "pretreatment" is a so-called degassing process that is performed before the first member 11 and the second member 12 are superimposed. In the pretreatment, the laser head is moved while irradiating the laser light 20 toward the irradiation target region 126, which is the region to be irradiated with the laser light 20, on the surface of the upper surface 121 of the second member 12. As a result, the metal on the surface of the irradiation target region 126 is melted, and the gas compressed inside the molten metal is discharged to the outside. The extent to which the metal on the surface of the irradiation target region 126 is melted in the pretreatment will be described later.

[0013] FIG. 2B shows the state after pre-processing has been performed. FIG. 2B shows the second member 12 after the pretreatment as seen from above. The second member 12 has a recessed region 127 indicated by hatching, a hole 123, and a hole 124. The method for forming the recessed region 127, the hole 123, and the hole 124 is not particularly limited. For example, the recessed region 127, the hole 123, and the hole 124 may be formed simultaneously when the second member 12 is molded, or may be formed by performing a cutting process after the second member 12 is molded. In addition, the second member 12 has an irradiation target region 126 irradiated with the laser light 20 in the pretreatment, which is formed so as to surround the outside of the recessed region 127. The recessed region 127 forms a space region 125 (see FIG. 1B) together with the lower surface 112 of the first member 11 superimposed on the second member 12.

[0014] FIG. 3(A) is a diagram showing a welding process in the manufacturing process of the cooling device 1. As shown in FIG. FIG. 3(A) shows a part of a cross section of the overlapped first member 11 and second member 12. The "welding process" is a welding process performed after the above-mentioned pretreatment, and is a process of lap-joint welding the first member 11 and the second member 12. In the welding process, the first member 11 and the second member 12 are overlapped, and a laser head is moved while irradiating the laser light 20 from above toward the irradiation target region 113, which is a region of the first member 11 facing the irradiation target region 126 of the second member 12 that has been pretreated. This causes the first member 11 and the second member 12 to be welded.

[0015] Specifically, the laser beam 20 irradiated from above toward the first member 11 enters the upper surface 111 of the irradiation target region 113 of the first member 11, penetrates through the lower surface 112, and is irradiated so as to melt a part of the irradiation target region 126 of the second member 12 facing the lower surface 112. As a result, a molten pool is formed in which the metal molten in the irradiation target region 113 of the first member 11 and the metal molten in the part of the irradiation target region 126 of the second member 12 are mixed together. Then, when the molten pool solidifies, the welding process is completed.

[0016] Here, the depth to which the second member 12 is melted in the above-mentioned pretreatment is deeper than the depth to which the second member 12 is melted in the welding treatment. That is, as shown in Fig. 3(A), in the welding treatment, the irradiation conditions are set so that the depth d2 of the molten pool formed in the irradiation target region 126 of the second member 12 by the irradiation of the laser beam 20 is shallower than the depth d1 of the molten pool formed in the irradiation target region 126 of the second member 12 by the irradiation of the laser beam 20 in the pretreatment. This prevents the metal of the portion that was not melted in the pretreatment stage (i.e., the portion deeper than the depth d1) from melting for the first time in the welding treatment stage and emitting gas from there.

[0017] In order to make the depth d2 at which the irradiation target region 126 of the second member 12 is melted shallower than the depth d1, the relationship between the depth d1 and the depth d2 may be controlled, for example, by adjusting the output of the laser light 20 in each of the pretreatment and the welding treatment. In this case, the irradiation conditions are set in the welding treatment so that the output of the laser light 20 penetrates the irradiation target region 113 of the first member 11 and melts the irradiation target region 126 of the second member 12 to the depth d2.

[0018] Also, for example, the relationship between the depth d1 and the depth d2 may be controlled by adjusting the irradiation time of the laser beam 20 in each of the pretreatment and the welding treatment. In this case, the irradiation conditions are set in the welding treatment so that the irradiation time of the laser beam 20 is long enough to penetrate the irradiation target region 113 of the first member 11 and melt the irradiation target region 126 of the second member 12 to a depth d2. At this time, for example, the moving speed of the laser head moving while irradiating the laser beam 20 may be set as the irradiation condition.

[0019] In addition, the irradiation conditions may be set so that the output of the laser light 20 in the pretreatment is smaller than the output of the laser light 20 in the welding process. In this case, for example, the output of the laser light 20 in the pretreatment may be set to a low output that can degas the irradiation target area 126 of the second member 12, and the output of the laser light 20 in the welding process may be set to a high output that can penetrate the irradiation target area 113 of the first member 11 and weld a part of the irradiation target area 126 of the second member 12. In addition, the irradiation conditions may be set so that the output of the laser light 20 in the pretreatment is the same as the output of the laser light 20 in the welding process.

[0020] FIG. 3B is a diagram showing the state after the welding process has been performed. 3(B), a weld bead is formed in irradiation target area 113 indicated by a solid line on upper surface 111 of cooling device 1 manufactured by completing the welding process. Note that a bold dashed line indicates the position of irradiation target area 126 which formed a molten part together with irradiation target area 113 in the welding process. The weld part formed by irradiation target area 113 and irradiation target area 126 is disposed so as to surround space area 125, hole 123, and hole 124 formed inside cooling device 1.

[0021] (Comparison results with and without pre-processing) FIG. 4(A) is a plan view showing a part of the surface of a welded portion of a cooling device 1 manufactured by lap-joint welding a first member and a second member after pretreatment. Fig. 4(A) shows the state of the surface of the irradiation target area 113 of the first member 11 constituting the cooling device 1 shown in Fig. 3(B) above. As shown in Fig. 4(A), no noticeable voids are observed in the weld bead formed on the surface of the irradiation target area 113.

[0022] FIG. 4(B) is an X-ray CT image of the inside of the welded part, near the joint interface, of the cooling device 1 manufactured by lap-welding a first member and a second member after pretreatment. Fig. 4(B) shows the state inside the irradiation target area 126 of the second member 12 constituting the cooling device 1 shown in Fig. 3(B) above. As shown in Fig. 4(B), no noticeable voids are found inside the irradiation target area 126.

[0023] FIG. 5(A) is a plan view showing a part of the surface of a weld when two metal members are lap-welded without pretreatment. Figure 5(A) shows the surface of the weld of the metal member located on the front side in the direction of laser light irradiation, out of two metal members that were lap-joint-welded without pretreatment. As shown in Figure 5(A), it can be seen that the weld bead formed on the surface of the weld has irregularities.

[0024] Figure 5(B) is an X-ray CT image of the inside of a weld, near the joint interface, when two metal components are lap-welded without pretreatment. Figure 5(B) shows the inside of the weld of the metal member located at the back side in the direction of laser light irradiation, out of two metal members that were lap-joint-welded without pretreatment. As shown in Figure 5(B), it can be confirmed that multiple voids have occurred inside the weld.

[0025] In this way, when the first member and the second member are lap-joint-welded using the welding method according to the present embodiment, the welding process is performed after the pretreatment. Therefore, the generation of gas compressed inside the second member during welding is suppressed. As a result, the generation of voids is suppressed, as shown in Figs. 4(A) and (B). In contrast, when the first member and the second member are lap-joint-welded without the pretreatment, the generation of gas compressed inside the second member during welding is not suppressed. As a result, voids are likely to be formed on the surface and inside the weld, as shown in Figs. 5(A) and (B).

[0026] In summary, the welding method, the manufacturing method for a cooling device, and the cooling device to which the present invention is applied are sufficient if they have the following configurations, and can take on a variety of different embodiments. In other words, the welding method to which the present invention is applicable is a welding method in which a first member 11 and a second member 12 are overlapped and laser-welded, and includes a pretreatment step of irradiating laser light 20 to an irradiation target region 126, which is the welding region of the second member 12 where welding is to be performed, before overlapping the first member 11 and the second member 12, and a welding process step of overlapping the first member 11 and the second member 12 after the pretreatment, and irradiating the irradiation target region 113 of the first member 11 in the welding region with laser light 20 to weld the first member 11 and the second member 12.

[0027] As a result, when the first member 11 and the second member 12 are overlapped and laser-welded, a pretreatment is performed in which the laser light 20 is irradiated to the irradiation target area 126, which is the welding area of ​​the second member 12, before the first member 11 and the second member 12 are overlapped. Then, the first member 11 and the second member 12 are overlapped, and the laser light 20 is irradiated to the irradiation target area 113 of the first member 11 in the welding area, and the first member 11 and the second member 12 are welded. In the pretreatment, the metal is melted by irradiating the irradiation target area 126, which is the welding area of ​​the second member 12, with the laser light 20, and the gas compressed inside is discharged, so that the generation of gas during the welding process is suppressed. As a result, when performing lap joint welding, the formation of blowholes that cause voids is suppressed, and the airtightness of the space surrounded by the welding area is ensured.

[0028] Here, the second member 12 may be formed by casting. As a result, the second member is formed by casting, making it possible to manufacture a high-strength product using inexpensive materials.

[0029] The second member 12 may also be formed by a die casting method. This allows the second member 12 to be formed by the die casting method. As a result, a high-strength product can be manufactured using die-cast material, which has low manufacturing costs. In addition, die-cast material is a material used in many fields, so the range of applicable fields is wide. Furthermore, the beauty and quality of the appearance of the die-cast product can be improved. In addition, compared with FSW (friction stir welding), which is often used to join die-cast material, which is considered to be a difficult material to weld, joining by inexpensive welding is possible, so equipment costs can be reduced. Furthermore, the workload for so-called deburring can be reduced.

[0030] Furthermore, the depth to which the second member 12 is melted in the pretreatment (for example, depth d1 in FIG. 3(A)) may be deeper than the depth to which the second member 12 is melted in the welding treatment (for example, depth d2 in FIG. 3(A)). As a result, the depth d1 to which the second member 12 is melted in the pretreatment is deeper than the depth d2 to which the second member 12 is melted in the welding treatment for welding the first member 11 and the second member 12. As a result, in the welding treatment, the laser light 20 is less likely to reach deep regions where degassing was not performed in the pretreatment, so that explosions can be suppressed.

[0031] Moreover, the output of the laser beam 20 emitted in the pretreatment may be smaller than the output of the laser beam 20 emitted in the welding treatment. As a result, the output of the laser beam 20 required for the pretreatment can be smaller than the output of the laser beam 20 required for the welding treatment, thereby achieving energy savings.

[0032] Moreover, the output of the laser beam 20 in the pretreatment may be set to the same value as the output of the laser beam 20 in the welding treatment. This makes it possible to control the depth of the molten pool formed by irradiation of the laser beam 20 by, for example, setting the output of the laser beam irradiation in the pretreatment and the output of the laser beam irradiation in the welding process to the same value and adjusting the irradiation time of the laser beam 20. As a result, it becomes unnecessary to change the setting of the output magnitude of the laser beam 20 irradiation between the pretreatment and the welding process, thereby reducing the labor of the worker.

[0033] Furthermore, the present invention, which has been completed with the above object in mind, is a manufacturing method for a cooling device 1 which is formed by casting and includes a main body (second member 12) for containing liquid, and a cover (first member 11) which is overlapped on the main body so as to cover an opening (recessed region 127) of the main body, and includes a pretreatment step of irradiating a peripheral portion (irradiation target region 126) around the opening of the main body with laser light 20 before overlapping the cover, and a welding step of overlapping the cover after the pretreatment step, and irradiating a portion (irradiation target region 113) of the cover which overlaps with the peripheral portion with laser light 20 to perform laser welding.

[0034] In this way, in the pretreatment, the metal is melted by irradiating the welding area of ​​the main body with the laser beam 20, and the gas compressed inside is discharged, so that the generation of gas during the welding process is suppressed. As a result, when performing lap joint welding, the formation of blowholes that cause voids is suppressed, and the airtightness of the space surrounded by the welding area is ensured.

[0035] Furthermore, the present invention, which was completed with this objective in mind, is a cooling device 1 in which a main body for containing liquid and a cover covering an opening of the main body are joined by laser welding in an overlapping state, and before the cover is overlapped with the main body, laser light 20 is irradiated to the welding area around the opening where laser welding is performed, and after the cover is overlapped with the main body, laser light 20 is irradiated to the portion of the welding area opposite the main body to the main body, and the cover is joined to the main body.

[0036] This prevents the generation of gas during the welding process because the metal melts when the laser beam is irradiated onto the body and the gas compressed inside is discharged. As a result, the formation of blowholes that cause voids during lap joint welding is prevented, and the airtightness of the space surrounded by the welded area is ensured.

[0037] (Other embodiments) Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment. For example, the configuration of the cooling device 1 shown in Fig. 1 and the welding method shown in Fig. 2 and Fig. 3 are merely examples for achieving the object of the present invention, and are not particularly limited. Furthermore, the effects of the present invention are not limited to those described in the above-mentioned embodiment, including the specific example shown in Fig. 4.

[0038] For example, the configuration of the cooling device 1 shown in Figs. 1(A) and (B) is merely an example. The shape of the welded portion by the welding method according to the present embodiment is not limited to the above example. That is, the shape of the welded area shown in Fig. 3(B) is elliptical, but is not limited to this. It may be rectangular or circular, or may be straight or curved, depending on the shape of the spatial area through which the refrigerant passes. In addition, the welding method according to the present invention may be applied to devices and structures other than cooling devices, as long as they are manufactured by overlapping a first member and a second member and laser welding them.

[0039] In addition, in the above embodiment, the first member 11 and the second member 12 constituting the cooling device 1 are made of die-cast material, but the present invention is not limited to this and may be made of any metal member. [Explanation of symbols]

[0040] 1...cooling device, 11...first member, 12...second member, 113, 126...irradiation target area, 20...laser light

Claims

1. A welding method for overlapping a first member and a second member and laser welding them, comprising the steps of: a pretreatment step of irradiating a welding area of ​​the second member with a laser beam before the first member and the second member are overlapped with each other; a welding process in which, after the pretreatment, the first member and the second member are overlapped and a laser beam is irradiated onto the first member in the welding region to weld the first member and the second member; Including, Welding method.

2. The second member is formed by casting. The welding method according to claim 1.

3. The second member is formed by a die casting method. The welding method according to claim 2.

4. a depth to which the second member is melted in the pretreatment is greater than a depth to which the second member is melted in the welding treatment; The welding method according to any one of claims 1 to 3.

5. The output of the laser light irradiation in the pretreatment is smaller than the output of the laser light irradiation in the welding treatment. The welding method according to claim 4.

6. The output of the laser light irradiation in the pretreatment is set to the same value as the output of the laser light irradiation in the welding treatment. The welding method according to claim 4.

7. a body formed by casting and configured to contain a liquid; A cover that is superimposed on the main body so as to cover the opening of the main body; A method for manufacturing a cooling device comprising: a pre-treatment of irradiating a peripheral portion of the main body around the opening with a laser beam before the cover is superimposed; a welding process in which, after the pretreatment, the covers are overlapped and a laser beam is irradiated onto the overlapping portions of the covers that overlap the peripheral portions to perform laser welding; Including, A method for manufacturing a cooling device.

8. A cooling device in which a main body for accommodating liquid and a cover for covering an opening of the main body are joined by laser welding in an overlapping state, Before the cover is superimposed on the main body, a laser beam is irradiated onto a welding area around the opening where laser welding is to be performed; The cover is superimposed on the main body, and then a laser beam is irradiated onto a portion of the welding region opposite to the main body to be joined to the main body. Cooling device.

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