Electron beam welding-brazing composite welding method

Abstract

The invention provides an electron beam welding-brazing composite welding method, which relates to the technical field of welding, and is used for carrying out electron beam welding on the upper part area of the butt joint surface of a cover plate and a bottom plate to realize the welding of the upper part area of the butt joint surface of a lock bottom structure. The welding method comprises the following steps: welding a butt joint gap between a cover plate and a bottom plate, melting a brazing filler metal with a lower melting point (180-350 DEG C) by using heat generated in the electron beam welding process, and wetting and filling the molten brazing filler metal at the bottom of the butt joint gap, so that brazing of the lower area of the butt joint surface of the cover plate and the bottom plate is realized, and the sealing performance of a welding sample is ensured; due to the fact that the energy of electron beams used in the electron beam welding process is small, and the brazing filler metal is arranged between the electron beams and the lock bottom step, the risk of penetration of the lock bottom step does not exist, and the problems of surface collapse, back face splashing and the like of weld joints are effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to an electron beam welding-brazing composite welding method. Background Art

[0002] The cooling panel is a fluid heat exchanger. As an ideal heat dissipation element for high-power electronic equipment, it has a wide range of applications. The lock bottom structure is a special welding structure used when a rigid backing plate cannot be applied to the back of the weld. The lock bottom structure is currently widely used in the welding of cooling panels. Aluminum alloy is an ideal material for heat dissipation components. In order to improve the heat dissipation effect of the cooling panel, the material of the lock bottom structure is generally selected from aluminum alloy.

[0003] The cooling panel is usually welded by electron beam welding. However, as a high-energy beam welding method, electron beam welding has a typical pinhole effect. In addition, the surface tension of aluminum alloy materials is relatively small during the melting welding process, and the supporting and lifting effect on the molten pool is relatively poor. Therefore, due to the small thickness of the lock bottom step, it is easy to melt through the lock bottom step while ensuring that the weld is fully melted through, which may cause the weld surface to collapse and back splash. The back weld nodules caused by such welding defects cannot form an effective metallurgical bond with the parent material, and the connection is not firm. In addition, welding spatter is easy to enter the flow channel from the gap of the lock bottom structure, and fall due to the vibration and flushing of the liquid during the later cleaning process, resulting in excess material inside the flow channel, affecting the cleanliness test results or causing the product to be scrapped. If the energy during electron beam welding is too small, the weld root will not be fully welded, and the sealing cannot be guaranteed. Therefore, when electron beam welding is used for welding the lock bottom structure, when the thickness of the lock bottom step is thin and the width is narrow, how to avoid surface collapse and back splashing of the weld while ensuring the sealing of the product has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The problem solved by the present invention is: when the electron beam welding method is used to weld the lock bottom structure, when the thickness of the lock bottom step is thin and the width is narrow, how to avoid surface collapse and back splashing of the weld while ensuring the sealing of the product.

[0005] In order to solve the above problems, the present invention provides an electron beam welding-brazing composite welding method, comprising:

[0006] Step S1, obtaining a bottom plate and a cover plate of a bottom lock structure; one side of the bottom plate has a bottom lock step;

[0007] Step S2, overlapping the cover plate on the bottom lock step, leaving a butt gap and an overlap gap between the cover plate and the bottom plate;

[0008] Step S3, filling the bottom of the butt gap with solder; the solder has a melting point of 180-350°C;

[0009] Step S4, electron beam welding is performed on the upper area of ​​the butt joint surface between the cover plate and the base plate, and the heat generated during the electron beam welding process is used to melt the solder, and the melted solder is filled in the bottom of the butt joint gap, thereby achieving brazing of the lower area of ​​the butt joint surface between the cover plate and the base plate; wherein the upper area is an area located above the solder, and during the electron beam welding process, the acceleration voltage is 55-65KV, the focusing current is 690-692mA, and the welding beam current is 15.5-16.5mA.

[0010] Optionally, the total thickness of the bottom plate is H, the thickness of the bottom locking step is h, and the filling height of the solder is h1; the difference between H and h is h2, and the ratio of h2 to h1 is (2.5-3.5):1.

[0011] Optionally, H is 5 mm and h is 1-2.5 mm.

[0012] Optionally, the width L of the bottom locking step is 1.5-2 mm.

[0013] Optionally, the gap size of the butt joint gap is 0.15-0.25 mm.

[0014] Optionally, the gap size of the overlapping gap is less than 0.1 mm.

[0015] Optionally, the solder is selected from one of Sn63Pb37 solder and Sn95Sb5 solder.

[0016] Optionally, the solder is a sheet solder.

[0017] Optionally, in the step S4, during the electron beam welding process, the welding speed is 9-10 mm / min.

[0018] Optionally, the base plate is made of 6061T6 aluminum alloy, and the cover plate is made of 5A06 aluminum alloy.

[0019] Compared with the prior art, the present invention performs electron beam welding on the upper area of ​​the butt joint surface between the cover plate and the base plate, realizes the welding of the upper area of ​​the butt joint surface of the lock bottom structure, and utilizes the heat generated in the electron beam welding process to melt the solder with a lower melting point (180-350°C), and the melted solder is wetted and filled in the bottom of the butt joint gap, thereby realizing the brazing of the lower area of ​​the butt joint surface between the cover plate and the base plate, thereby preventing the weld from not being fully penetrated, so as to ensure the sealing of the welded sample; because the electron beam energy used in the electron beam welding process is relatively small, and there is solder between the electron beam and the lock bottom step, there is no risk of the lock bottom step being fully melted during the electron beam welding process, effectively avoiding the problems of surface collapse and back splashing in the weld, and also effectively solving the problem of excess material in the flow channel after electron beam welding. In summary, the present invention uses a combination of electron beam welding and brazing to achieve the welding of a thin and narrow lock bottom structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of welding in an embodiment of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the bottom plate in the embodiment of the invention;

[0022] Figure 3 It is a structural schematic diagram of the cover plate overlapped on the bottom lock step and filled with solder in an embodiment of the present invention;

[0023] Figure 4 for Figure 3 A partial enlarged view of point I in the middle.

[0024] Description of reference numerals:

[0025] 1. Bottom plate; 11. Bottom locking step; 2. Cover plate; 3. Butt joint gap; 4. Overlap gap; 5. Brazing material. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0028] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more. It should be noted that, Figure 1 A represents the electron beam in the electron beam welding process.

[0029] An electron beam welding-brazing composite welding method provided by an embodiment of the present invention comprises:

[0030] Step S1, obtaining the bottom plate 1 and cover plate 2 of the bottom lock structure; Figure 2 As shown, one side of the bottom plate 1 has a bottom locking step 11; specifically, as Figure 2 As shown, the bottom plate 1 includes a bottom plate body and a bottom locking step 11 located on the right side of the bottom plate body;

[0031] Step S2: Figure 3 and Figure 4 As shown, the cover plate 2 is overlapped on the lock bottom step 11, and a butt gap 3 and an overlap gap 4 are left between the cover plate 2 and the bottom plate 1;

[0032] Step S3: Figure 3 and Figure 4 As shown, the solder 5 is filled into the bottom of the butt gap 3; the melting point of the solder 5 is 180-350°C;

[0033] Step S4: Figure 1As shown, electron beam welding is performed on the upper area of ​​the butt joint surface between the cover plate 2 and the base plate 1, and the heat generated during the electron beam welding process is used to melt the solder 5, and the melted solder 5 is filled in the bottom of the butt joint gap 3, thereby achieving brazing of the lower area of ​​the butt joint surface between the cover plate 2 and the base plate 1; wherein the upper area is the area located above the solder 5, and during the electron beam welding process, the acceleration voltage is 55-65KV, the focusing current is 690-692mA, and the welding beam current is 15.5-16.5mA.

[0034] The embodiment of the present invention performs electron beam welding on the upper area of ​​the butt joint surface of the cover plate 2 and the base plate 1 to achieve welding of the upper area of ​​the butt joint surface of the lock bottom structure, and utilizes the heat generated during the electron beam welding process to melt the solder with a relatively low melting point (180-350°C), and the melted solder is wetted and filled in the bottom of the butt joint gap 3, thereby achieving brazing of the lower area of ​​the butt joint surface of the cover plate 2 and the base plate 1, thereby preventing the occurrence of incomplete penetration of the weld to ensure the sealing of the welded sample; since the electron beam energy used in the electron beam welding process is relatively small, and there is a solder 5 between the electron beam and the lock bottom step 11, there is no risk of the lock bottom step 11 being melted through, effectively avoiding problems such as surface collapse and back splashing in the weld, and also effectively solving the problem of excess material in the flow channel after electron beam welding. In summary, the embodiment of the present invention uses a combination of electron beam welding and brazing to achieve welding of a thin and narrow lock bottom structure.

[0035] It should be noted that the butt joint surface between the cover plate 2 and the bottom plate 1 in the present invention refers to the vertically opposite surface between the cover plate 2 and the bottom plate 1 after the cover plate 2 is overlapped on the bottom locking step 11, and its position corresponds to the position of the butt joint gap 3. Figure 3 and Figure 4 As shown, the butt gap 3 is the gap between the right end surface of the cover plate body and the left end surface of the bottom plate 1 , and the overlap gap 4 is the gap between the upper end surface of the bottom locking step 11 and the lower end surface of the bottom plate 1 .

[0036] In some embodiments of the present invention, the total thickness of the base plate 1 is H, the thickness of the bottom locking step 11 is h, and the filling height of the solder 5 is h1; the difference between H and h is h2, and the ratio of h2 to h1 is (2.5-3.5):1.

[0037] In some embodiments of the present invention, illustratively, the H is 5 mm and the h is 1-2.5 mm.

[0038] In some embodiments of the present invention, the width L of the bottom locking step 11 is 1.5-2 mm.

[0039] In some embodiments of the present invention, the gap size of the butt joint gap 3 is 0.15-0.25 mm.

[0040] In some embodiments of the present invention, the overlap gap 4 has a gap size less than 0.1 mm.

[0041] In some embodiments of the present invention, the solder 5 is selected from one of Sn63Pb37 solder and Sn95Sb5 solder. The melting point of Sn63Pb37 solder is 183°C, and the melting point of Sn95Sb5 solder is 245°C.

[0042] In some embodiments of the present invention, the solder 5 is a sheet solder.

[0043] In some embodiments of the present invention, in step S4, during the electron beam welding process, the welding speed is 9-10 mm / min.

[0044] In some embodiments of the present invention, the base plate 1 is made of 6061T6 aluminum alloy, and the cover plate 2 is made of 5A06 aluminum alloy.

[0045] The present invention is further described below in conjunction with specific embodiments.

[0046] Example 1

[0047] A1. Obtain a bottom plate and a cover plate of a bottom lock structure; one side of the bottom plate has a bottom lock step; wherein the bottom plate is made of 6061T6 aluminum alloy, and the cover plate is made of 5A06 aluminum alloy; the total thickness H of the bottom plate is 5 mm, the thickness h of the bottom lock step is 1 mm, and the width is 2 mm; the thickness of the cover plate is 4 mm.

[0048] A2. Overlap the cover plate on the lock bottom step, leaving a butt joint gap and an overlap gap between the cover plate and the bottom plate; wherein the gap size of the butt joint gap is 0.2 mm, and the gap size of the overlap gap is 0.05 mm.

[0049] A3. Fill the solder at the bottom of the joint gap; the solder is a sheet Sn95Sb5 solder, the thickness of the sheet Sn95Sb5 solder is 0.18 mm, and the filling height of the solder is h1, which is 1.5 mm.

[0050] A4. Electron beam welding is performed on the upper area of ​​the butt joint surface between the cover plate and the bottom plate, and the heat generated during the electron beam welding process is used to melt the brazing material. The molten brazing material is filled in the bottom of the butt joint gap, thereby achieving brazing of the lower area of ​​the butt joint surface between the cover plate and the bottom plate to obtain a welded sample; wherein, during the electron beam welding process, the acceleration voltage is 60 KV, the focusing current is 691 mA, the welding beam current is 16.0 mA, and the welding speed is 10 mm / min.

[0051] The welding sample obtained in Example 1 was tested to have good sealing properties, and the weld did not have problems such as surface collapse and back splash.

[0052] Example 2

[0053] The difference from Example 1 is that in step A3, the solder is a sheet Sn63Pb37 solder. The welding sample obtained in Example 2 has good sealing performance after testing, and the weld seam has no problems such as surface collapse and back splash.

[0054] Comparative Example 1

[0055] B1. Obtain a bottom plate and a cover plate of a bottom lock structure; one side of the bottom plate has a bottom lock step; wherein the bottom plate is made of 6061T6 aluminum alloy, and the cover plate is made of 5A06 aluminum alloy; the total thickness H of the bottom plate is 5 mm, the thickness h of the bottom lock step is 1 mm, and the width is 2 mm; the thickness of the cover plate is 4 mm.

[0056] B2. Overlap the cover plate on the lock bottom step, leaving a butt gap and an overlap gap between the cover plate and the bottom plate; wherein the butt gap is 0.2 mm, and the overlap gap is 0.05 mm.

[0057] B3. Electron beam welding is performed on the entire butt joint surface of the cover plate and the bottom plate to obtain a welding sample; wherein, during the electron beam welding process, the acceleration voltage is 60 KV, the focusing current is 691 mA, the welding beam current is 19.0 mA, and the welding speed is 10 mm / min.

[0058] It can be seen that compared with Example 1, no solder is used in Comparative Example 1, and the welding beam is larger. The weld seam of the welding sample obtained in Comparative Example 1 was tested to have surface collapse and back splash problems.

[0059] Comparative Example 2

[0060] The difference from comparative example 1 is that in step B3, the welding beam current is 16 mA. The weld seam of the welding sample obtained in comparative example 2 has a problem of incomplete penetration after testing, and the sealing performance of the sample is poor.

[0061] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. An electron beam welding-brazing hybrid welding method, characterized in that: include: Step S1, obtaining a bottom plate (1) and a cover plate (2) of a bottom locking structure; one side of the bottom plate (1) is provided with a bottom locking step (11); Step S2, overlapping the cover plate (2) on the bottom locking step (11), leaving a butt joint gap (3) and an overlap gap (4) between the cover plate (2) and the bottom plate (1); Step S3, filling the solder (5) at the bottom of the butt joint gap (3); the solder (5) has a melting point of 180-350°C; Step S4, electron beam welding is performed on the upper area of ​​the butt joint surface between the cover plate (2) and the base plate (1), and the heat generated during the electron beam welding process is used to melt the solder (5), and the melted solder is filled in the bottom of the butt joint gap (3), thereby achieving brazing of the lower area of ​​the butt joint surface between the cover plate (2) and the base plate (1); wherein the upper area is an area located above the solder (5), and during the electron beam welding process, the acceleration voltage is 55-65KV, the focusing current is 690-692mA, and the welding beam current is 15.5-16.5mA.

2. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The total thickness of the bottom plate (1) is H, the thickness of the bottom locking step (11) is h, and the filling height of the solder (5) is h1; the difference between H and h is h2, and the ratio of h2 to h1 is (2.5-3.5):

1.

3. The electron beam welding-brazing hybrid welding method according to claim 2, characterized in that: The H is 5 mm, and the h is 1-2.5 mm.

4. The electron beam welding-brazing hybrid welding method according to claim 3, characterized in that: The width L of the bottom locking step (11) is 1.5-2 mm.

5. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The gap size of the butt joint gap (3) is 0.15-0.25 mm.

6. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The gap size of the overlapping gap (4) is less than 0.1 mm.

7. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The solder (5) is selected from one of Sn63Pb37 solder and Sn95Sb5 solder.

8. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The solder (5) is a sheet solder.

9. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: In step S4, the welding speed is 9-10 mm / min.

10. The electron beam welding-brazing hybrid welding method according to claim 1, characterized in that: The base plate (1) is made of 6061T6 aluminum alloy, and the cover plate (2) is made of 5A06 aluminum alloy.

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