Welding method, method for manufacturing cooling device, and cooling device

Abstract

The invention relates to a welding method, a method for manufacturing a cooling device, and a cooling device. The present invention addresses the problem of suppressing the influence of gas present inside a metal member on welding. As a means for solving the problem, provided is a welding method in which a first member (11) and a second member (12) are overlapped and laser-welded, the welding method including: a pretreatment in which the first member (11) and the second member (12) are welded before being overlapped, and a welding treatment in which the first member (11) and the second member (12) are welded to each other before being overlapped; and a welding process for welding the first member (11) and the second member (12) by overlapping the first member (11) and the second member (12) and by irradiating the laser light (20) to a portion of the first member (11) in the welding region after the pre-process, the laser light (20) being irradiated to an irradiation target region (126), which is a welding region, in the second member (12).

Description

Technical Field

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

[0002] In so-called lap welding, in which two overlapping metal members are joined by irradiating them with laser light, a technique is known in which gas generated from the metal members during welding is released to the outside to suppress the formation of pores (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-6376 Summary of the Invention

[0006] Die-cast materials formed by pouring molten nonferrous metal into a mold are suitable for materials used in products with high dimensional accuracy and complex shapes. In addition, since they can be mass-produced, manufacturing costs can be suppressed. However, in die-cast materials, compressed gas sometimes remains inside during casting. Therefore, if lap welding is performed, the gas inside the die-cast material sometimes becomes bubbles and appears in the molten pool, or the gas accumulation part explodes. In this case, the gas that is not discharged to the outside during welding sometimes forms pores, resulting in a hole defect called a void. If a void is generated, the appearance and / or interior of the weld will be affected, i.e., poor welding, a reduction in the strength of the weld, a reduction in the airtightness of the weld, etc.

[0007] An object of the present invention is to suppress the influence of gas existing inside a metal member on welding.

[0008] The present invention, which was completed with such an object in mind, is a welding method for overlapping a first member and a second member and performing laser welding, the welding method comprising a pre-processing and a welding process.

[0009] The pre-processing is a process of irradiating a laser beam to a welding region of the second member where welding is to be performed before the first member and the second member are superimposed.

[0010] The welding process is a process of welding the first member and the second member together after the pre-process and irradiating a portion of the first member in the welding region with laser light to weld the first member and the second member together.

[0011] Here, the second member may be formed by casting.

[0012] In addition, the second member may be formed by die casting.

[0013] Furthermore, the depth to which the second member is melted in the pre-process may be deeper than the depth to which the second member is melted in the welding process.

[0014] In addition, the output power of the laser irradiation in the pre-process may be lower than the output power of the laser irradiation in the welding process.

[0015] In addition, the output power of the laser irradiation in the pre-process may be set to be the same as the output power of the laser irradiation in the welding process.

[0016] Furthermore, the present invention, which has been completed with such an object, is a method for manufacturing a cooling device comprising a main body formed by casting and containing a liquid, and a cover overlapping the main body so as to cover an opening of the main body, the manufacturing method comprising a pre-processing and a welding process.

[0017] The pre-processing is a process of irradiating the periphery of the opening of the main body with laser light before the cover is superposed.

[0018] The welding process is a process of laminating the cover after the pre-process and irradiating a portion of the cover overlapping the peripheral portion with a laser beam to perform laser welding.

[0019] In addition, the present invention completed with such a purpose is a cooling device, which 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. Before the main body is overlapped with the cover, the welding area around the opening where laser welding is performed is irradiated with laser, and after the cover overlaps with the main body, the cover is irradiated with laser at a portion on the opposite side of the main body in the welding area to thereby be joined to the main body.

[0020] According to the present invention, it is possible to suppress the influence of gas existing inside the metal member on welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 (A) is a perspective view showing an example of the external appearance structure of the cooling device according to the present embodiment, and (B) is a bottom view showing an example of the external appearance structure of the cooling device.

[0022] Figure 2 (A) is a diagram showing a state of pre-processing in the manufacturing process of the cooling device, and (B) is a diagram showing a state after the pre-processing is performed.

[0023] Figure 3(A) is a diagram showing a state of welding during the manufacturing process of the cooling device, and (B) is a diagram showing a state after the welding process is performed.

[0024] Figure 4 (A) is a top view showing a portion of the surface of the weld portion of the cooling device manufactured by overlap welding the first component and the second component after pretreatment, and (B) is an X-ray CT image of the interior of the weld portion of the cooling device manufactured by overlap welding the first component and the second component after pretreatment, near the joining interface.

[0025] Figure 5 (A) is a top view showing a portion of the surface of the weld when two metal components are overlap-welded without pretreatment, and (B) is an X-ray CT image of the interior of the weld and near the joint interface when two metal components are overlap-welded without pretreatment.

[0026] Description of Reference Numerals

[0027] 1 ...cooling device; 11 ...first member; 12 ...second member; 113 , 126 ...irradiation target area; 20 ...laser. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0029] (Structure of cooling device)

[0030] Figure 1 (A) is a perspective view showing an example of the external appearance structure of the cooling device 1 according to the present embodiment. Figure 1 (B) is a bottom view showing an example of the external appearance structure of the cooling device 1 .

[0031] like Figure 1 As shown in (A), the cooling device 1 is manufactured by overlapping 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 portion 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 the main body of the cooling device 1. In this embodiment, the first member 11 and the second member 12 are both die-cast materials.

[0032] In addition, if Figure 1As shown in (A) and (B), holes 123 and 124 are formed on the bottom surface of cooling device 1 (the lower surface 122 of second member 12). Furthermore, a space region 125, indicated by a dotted line, is formed within cooling device 1. Either hole 123 or hole 124 functions as a hole for supplying a fluid (liquid or gas) serving as the cooling medium for cooling device 1 to space region 125. The other hole functions as a hole for discharging the cooling medium that has passed through space region 125 to the outside.

[0033] For example, to enable hole 123 to function as a hole for supplying a cooling medium to space region 125, a first pipe (not shown) for supplying a cooling medium to cooling device 1 is connected to hole 123. Furthermore, to enable hole 124 to function as a hole for discharging the cooling medium that has passed through space region 125 to the outside, a second pipe (not shown) for discharging the cooling medium from cooling device 1 is connected to hole 124. In this case, the cooling medium supplied to cooling device 1 via the first pipe cools first component 11 and second component 12 while passing through space region 125, and is then discharged to the outside of cooling device 1 via the second pipe. Thus, by arranging an object to be cooled (e.g., a semiconductor device) above first component 11, the object to be cooled is cooled.

[0034] (Method for manufacturing cooling device)

[0035] Figure 2 (A) is a diagram showing a state of pre-processing in the manufacturing process of the cooling device 1 .

[0036] exist Figure 2 (A) shows a portion of the cross section of the second component 12. The manufacturing process of the cooling device 1 includes pretreatment and welding treatment. The so-called "pretreatment" is a so-called degassing treatment performed before the first component 11 and the second component 12 are overlapped. In the pretreatment, the laser head is moved while the laser 20 is irradiated toward the irradiation target area 126, which is the area on the surface of the upper surface 121 of the second component 12 that becomes the target of the irradiation laser 20. As a result, the metal on the surface of the irradiation target area 126 is melted, and the gas compressed inside the molten metal is discharged to the outside. Furthermore, the extent to which the metal on the surface of the irradiation target area 126 is melted in the pretreatment will be described later.

[0037] Figure 2 (B) is a diagram showing the state after pre-processing.

[0038] exist Figure 2(B) shows the situation when the second component 12 that has been pre-treated is viewed from the top. A recessed area 127, a hole 123, and a hole 124 indicated by oblique lines are formed on the second component 12. Furthermore, the method of forming the recessed area 127, the hole 123, and the hole 124 is not particularly limited. For example, they can be formed simultaneously when the second component 12 is formed by molding, or they can be formed by cutting after the second component 12 is formed by molding. In addition, on the second component 12, an irradiation target area 126 that has been irradiated by the laser 20 in the pre-treatment is formed in a manner surrounding the outside of the recessed area 127. The recessed area 127 forms a space area 125 together with the lower surface 112 of the first component 11 overlapping the second component 12 (see Figure 1 (B)).

[0039] Figure 3 (A) is a diagram showing a state of welding processing in the manufacturing process of the cooling device 1 .

[0040] exist Figure 3 (A) shows a partial cross-section of the overlapping first and second members 11, 12. The so-called "welding process" is a welding process performed after the aforementioned pretreatment, in which the first and second members 11, 12 are overlapped and welded. During the welding process, the first and second members 11, 12 are overlapped, and the laser head is moved while irradiating the irradiation target area 113 from above. The irradiation target area 113 is the area of ​​the first member 11 that faces the irradiation target area 126 of the pretreated second member 12. This welds the first and second members 11, 12 together.

[0041] Specifically, the laser light 20 irradiated from above toward the first member 11 is irradiated in such a manner that it enters from the upper surface 111 of the irradiation target region 113 of the first member 11 and exits from the lower surface 112, thereby penetrating the irradiation target region 126 of the second member 12, which is opposite the irradiation target region 113. This forms a molten pool of metal melted in the irradiation target region 113 of the first member 11 and in a portion of the irradiation target region 126 of the second member 12. When this molten pool solidifies, the welding process is completed.

[0042] Here, the depth of melting the second member 12 in the above-mentioned pre-processing is deeper than the depth of melting the second member 12 in the welding process. Figure 3As shown in FIG. 1A , during the welding process, 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 irradiation with the laser light 20 is shallower than the depth d1 of the molten pool formed in the irradiation target region 126 of the second member 12 by irradiation with the laser light 20 in the pre-process. This can prevent the metal in the portion that has not melted in the pre-process (i.e., the portion deeper than the depth d1) from being initially melted during the welding process and gas emission therefrom.

[0043] 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 can be controlled by adjusting the output power of the irradiation of the laser 20 in each of the pre-treatment and the welding process, for example. In this case, in the welding process, the irradiation conditions are set so that the output power of the laser 20 is such that the irradiation target region 113 of the first member 11 is penetrated and the irradiation target region 126 of the second member 12 is melted to the depth d2.

[0044] Alternatively, for example, the relationship between depth d1 and depth d2 can be controlled by adjusting the irradiation time of laser light 20 during both the pre-treatment and welding process. In this case, during the welding process, the irradiation conditions are set so that the irradiation time of laser light 20 penetrates irradiation region 113 of first member 11 and melts irradiation region 126 of second member 12 to depth d2. In this case, the irradiation conditions may include, for example, the speed of the laser head moving while irradiating laser light 20.

[0045] Alternatively, the irradiation conditions may be set so that the output power of the irradiation with the laser light 20 during the pre-process is lower than the output power of the irradiation with the laser light 20 during the welding process. In this case, for example, the output power of the irradiation with the laser light 20 during the pre-process may be set to a low output power sufficient to degas the irradiation target region 126 of the second member 12, while the output power of the irradiation with the laser light 20 during the welding process may be set to a high output power sufficient to penetrate the irradiation target region 113 of the first member 11 and weld a portion of the irradiation target region 126 of the second member 12. Alternatively, the irradiation conditions may be set so that the output power of the irradiation with the laser light 20 during the pre-process and the output power of the irradiation with the laser light 20 during the welding process are the same.

[0046] Figure 3 (B) is a diagram showing the state after the welding process has been performed.

[0047] like Figure 3As shown in FIG. 1B , a weld bead is formed in the irradiation target area 113 (shown by a solid line) on the upper surface 111 of the cooling device 1 manufactured by welding. Furthermore, the thick dashed line indicates the position of the irradiation target area 126, which forms a welded portion together with the irradiation target area 113 during the welding process. The welded portion formed by the irradiation target area 113 and the irradiation target area 126 is arranged so as to surround the space 125, holes 123, and holes 124 formed within the cooling device 1.

[0048] (Comparison results between cases with and without pre-processing)

[0049] Figure 4 (A) is a plan view showing a portion of the surface of a weld portion of a cooling device 1 manufactured by lap welding a first member and a second member after pretreatment.

[0050] exist Figure 4 (A) shows the structure of the above Figure 3 (B) shows the surface of the irradiation target area 113 of the first member 11 of the cooling device 1. Figure 4 As shown in (A), no conspicuous voids are observed in the weld bead formed on the surface of the irradiation target region 113 .

[0051] Figure 4 (B) is an X-ray CT image of the interior of the welded portion and the vicinity of the joint interface of the cooling device 1 manufactured by lap welding the first member and the second member after pretreatment.

[0052] exist Figure 4 (B) shows the above Figure 3 (B) shows the situation inside the irradiation target area 126 of the second member 12 of the cooling device 1. Figure 4 As shown in (B), no conspicuous cavity is observed inside the irradiation target region 126 .

[0053] Figure 5 (A) is a plan view showing a portion of the surface of a weld portion when two metal members are lap-welded without pretreatment.

[0054] exist Figure 5 (A) shows the surface of the welded portion of the metal member located on the front side of the laser irradiation direction among two metal members that were overlap-welded without pretreatment. Figure 5 As shown in (A), it can be confirmed that the weld bead formed on the surface of the weld portion has irregularities.

[0055] Figure 5(B) is an X-ray CT image of the interior of the weld and the vicinity of the joint interface when two metal members are lap-welded without pretreatment.

[0056] exist Figure 5 (B) shows the situation inside the welded portion of the metal member arranged on the deep side in the irradiation direction of the laser, among two metal members that were overlap-welded without pre-treatment. Figure 5 As shown in (B), it can be confirmed that a plurality of voids are generated inside the welded portion.

[0057] Thus, when the first member and the second member are overlap-welded using the welding method according to this embodiment, the welding process is performed after the pre-processing. Therefore, the generation of gas compressed inside the second member during welding can be suppressed. As a result, Figure 4 As shown in (A) and (B), the generation of voids can be suppressed. In contrast, if the first and second components are overlap-welded without pre-treatment, the generation of gas compressed inside the second component during welding cannot be suppressed. As a result, as shown in Figure 5 As shown in (A) and (B), voids are easily formed on the surface and inside of the weld.

[0058] In summary, the welding method, the method for manufacturing a cooling device, and the cooling device according to the present invention can be applied by adopting the following configurations, and various embodiments can be adopted.

[0059] That is, the welding method applied to the present invention is a welding method for overlapping the first component 11 and the second component 12 and performing laser welding, which includes a pretreatment and a welding treatment, the pretreatment being a treatment for irradiating the irradiation target area 126 with a laser 20 before overlapping the first component 11 and the second component 12, the irradiation target area 126 being the welding area in the second component 12 to be welded, and the welding treatment being a treatment for overlapping the first component 11 and the second component 12 after the pretreatment, and irradiating the irradiation target area 113 of the first component 11 in the welding area with a laser 20 to weld the first component 11 and the second component 12.

[0060] Thus, when the first and second members 11, 12 are overlapped and laser welded, a pre-treatment is performed by irradiating the irradiation target area 126 of the second member 12 with laser light 20 before the first and second members 11, 12 are overlapped. Then, the first and second members 11, 12 are overlapped, and the irradiation target area 113 of the first member 11, which is within the weld area, is irradiated with laser light 20, thereby welding the first and second members 11, 12. During the pre-treatment, the irradiation of the irradiation target area 126 of the second member 12 with laser light 20 melts the metal and releases the gas trapped within, thereby suppressing the generation of gas during the welding process. As a result, the formation of pores, which can cause voids during lap welding, can be suppressed, ensuring the airtightness of the space surrounded by the weld area.

[0061] Here, the second member 12 can be formed by casting.

[0062] Thus, since the second member is formed by casting, a high-strength product can be manufactured using inexpensive materials.

[0063] In addition, the second member 12 can be formed by die casting.

[0064] Thus, the second component 12 is formed by die casting. As a result, a high-strength product can be manufactured using a die-cast material with low manufacturing cost. In addition, die-cast materials are materials used in many fields, so the fields of application are wide. Moreover, the appearance and quality of the die-cast product can be improved. In addition, compared with FSW (friction stir welding), which is more commonly used for joining die-cast materials that are considered difficult to weld, joining based on inexpensive welding can be achieved, so the equipment cost can be suppressed. Moreover, it is also possible to seek to reduce the workload for so-called deburring.

[0065] In addition, the depth of melting the second member 12 in the pre-processing (for example, Figure 3 The depth d1) in (A) may be greater than the depth at which the second member 12 is melted during the welding process (for example, Figure 3 The depth d2) in (A) is deep.

[0066] Thus, the depth d1 at which the second member 12 is melted in the pre-process is deeper than the depth d2 at which the second member 12 is melted in the welding process of welding the first member 11 and the second member 12. Therefore, during the welding process, the laser 20 is less likely to reach a deep region that has not been degassed in the pre-process, thereby suppressing explosions.

[0067] In addition, the output power of the irradiation with the laser light 20 in the pre-process may be lower than the output power of the irradiation with the laser light 20 in the welding process.

[0068] Thus, the output power of the irradiation of the laser light 20 required in the pre-process is lower than the output power of the irradiation of the laser light 20 required in the welding process, and thus energy saving can be achieved.

[0069] In addition, the output power of the irradiation with the laser light 20 in the pre-process may be set to be the same as the output power of the irradiation with the laser light 20 in the welding process.

[0070] Thus, for example, by setting the output power of the laser irradiation during the pre-process and the output power of the laser irradiation during the welding process to be the same and adjusting the irradiation time of the laser 20, the depth of the molten pool formed by the irradiation of the laser 20 can be controlled. As a result, it is no longer necessary to change the setting of the output power of the laser 20 irradiation during the pre-process and the welding process, thereby saving the operator's labor and time.

[0071] In addition, the present invention completed under the aforementioned purpose is a manufacturing method of a cooling device 1, wherein the cooling device 1 has a main body (second component 12) formed by casting and containing liquid, and a cover (first component 11) overlapping with the main body in a manner covering the opening portion of the main body (recessed area 127), and the manufacturing method includes a pretreatment and a welding treatment, wherein the pretreatment is a treatment of irradiating the surrounding area of ​​the opening portion of the main body, i.e., the peripheral portion (irradiation target area 126), with a laser 20 before overlapping the cover, and the welding treatment is a treatment of overlapping the cover after the pretreatment and irradiating the portion of the cover overlapping with the peripheral portion (irradiation target area 113) with a laser 20 to perform laser welding.

[0072] Thus, during the pre-processing, the laser beam 20 is irradiated onto the weld area of ​​the main body, melting the metal and releasing the gas trapped inside. This suppresses the generation of gas during the welding process. As a result, during lap welding, the formation of pores that can cause voids can be suppressed, ensuring the airtightness of the space surrounded by the weld area.

[0073] In addition, the present invention completed under the aforementioned purpose 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. Before the main body is overlapped with the cover, the laser 20 is irradiated to the welding area around the opening where laser welding is performed. After the cover overlaps with the main body, the laser 20 is irradiated to the part on the opposite side of the main body in the welding area to join with the main body.

[0074] Thus, laser irradiation of the main body melts the metal and releases the gas compressed inside, thereby suppressing the generation of gas during the welding process. As a result, the formation of pores that can cause voids during lap welding can be suppressed, ensuring the airtightness of the space surrounded by the weld area.

[0075] (Other Embodiments)

[0076] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, Figure 1 The structure of the cooling device 1 shown in Figure 2 and Figure 3 The welding methods shown in the drawings are merely examples for achieving the purpose of the present invention and are not particularly limited. In addition, the effects achieved by the present invention are not limited to the following: Figure 4 The effects described in the above-mentioned embodiments including the specific examples shown.

[0077] For example, Figure 1 The structure of the cooling device 1 shown in (A) and (B) is only an example. In addition, the shape of the welded portion formed by the welding method involved in this embodiment is not limited to the above-mentioned example. Figure 3 The shape of the weld region shown in (B) is elliptical, but is not limited to this. It can be rectangular, circular, straight, or curved, depending on the shape of the space through which the cooling medium passes. Furthermore, since the welding method according to the present invention can be applied to devices and structures other than cooling devices, as long as the first and second members are overlapped and laser welded, the welding method can be applied to devices and structures other than cooling devices.

[0078] Furthermore, in the above-described embodiment, the first member 11 and the second member 12 constituting the cooling device 1 are made of die-cast materials, but the present invention is not limited thereto and any member may be used as long as it is made of metal.

Claims

1. A welding method, comprising overlapping a first member and a second member and performing laser welding, comprising a pre-processing and a welding process, The pre-processing is a process of irradiating a laser beam to a welding region in the second member where welding is to be performed before the first member and the second member are superimposed. The welding process is a process of overlapping the first member and the second member after the pre-process and irradiating a portion of the first member in the welding region with laser light to weld the first member and the second member.

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

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

4. The welding method according to any one of claims 1 to 3, The depth to which the second member is melted in the pre-process is deeper than the depth to which the second member is melted in the welding process.

5. The welding method according to claim 4, The output power of the laser irradiation in the pre-process is lower than the output power of the laser irradiation in the welding process.

6. The welding method according to claim 4, The output power of the laser beam irradiation in the pre-process is set to be the same as the output power of the laser beam irradiation in the welding process.

7. A method for manufacturing a cooling device, The cooling device comprises: A body formed by casting and containing a liquid; and a cover overlapping the main body so as to cover the opening of the main body; The manufacturing method comprises pre-treatment and welding treatment, The pre-processing is a process of irradiating the periphery of the opening of the main body with laser light before the cover is overlapped. The welding process is a process of overlapping the cover cap after the pre-process and irradiating a laser beam to a portion of the cover cap overlapping the peripheral portion to perform laser welding.

8. A cooling device, wherein a main body for containing a 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 overlapped on the main body, a laser beam is irradiated to a welding area around the opening where laser welding is performed. After the cover is overlapped with the main body, the cover is irradiated with laser light at a portion of the welding region on the opposite side of the main body to be joined to the main body.

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