Multiple brazing method

Abstract

The present disclosure relates to the field of brazing technology, and specifically, to a multiple brazing method for vacuum brazing of aluminum alloy workpieces to be welded, comprising: a first pre-welding assembly, clamping the workpiece to be welded in a brazing device, the brazing device comprising a pad and a tooling bottom plate, the workpiece to be welded is clamped between the pad and the tooling bottom plate, and the first cover plate is pressed against the first surface by the pad; the first brazing; a second pre-welding assembly, clamping the workpiece to be welded in the brazing device, the workpiece to be welded is clamped between the pad and the tooling bottom plate, the second cover plate is pressed against the second surface by the pad, and the first cover plate that has been welded is pressed against the first surface by a clamp; the second brazing; wherein, the first brazing step uses a first brazing material, and the second brazing step uses a second brazing material, and both the first brazing material and the second brazing material are aluminum-silicon-magnesium brazing materials. The multiple brazing method disclosed in the present disclosure can reduce the risk of brazing material loss and improve the yield rate of three-dimensional microwave components.

Description

Technical Field

[0001] The present disclosure relates to the technical field of brazing, and in particular to a multiple brazing method. Background Art

[0002] Aluminum alloys are widely used in aerospace due to their light weight, good corrosion resistance, excellent thermal and electrical conductivity, and have long been considered the main structural material for making waveguides and many other complex components. Aluminum alloy three-dimensional microwave components can be formed by vacuum brazing of multiple parts. However, due to the complex structure of three-dimensional microwave components, there may be multiple welding planes, and the welds on each plane may be perpendicular to each other, so multiple welding is required.

[0003] In multiple welding steps, the solder in the previous weld may remelt during the next welding process. The remelted liquid solder flows due to gravity, which may create the risk of solder loss, resulting in loose solder joints and ultimately low yield of three-dimensional microwave components after welding.

[0004] In order to reduce the risk of remelting of the brazing filler metal in the previous weld during the next welding process, multiple types of brazing fillers with different melting points can be used in descending order according to the specific number of welding times, and the welding temperature can be lowered in sequence. For example, although the various types of brazing fillers for vacuum brazing are basically based on Al-Si brazing fillers, multiple different components can be added to change the melting point of each brazing filler metal.

[0005] For example, the Cu element can effectively reduce the melting point of Al-Si solder. However, excessive addition of the Cu element can easily lead to excessive brittle Al2Cu phases in the structure, thereby reducing the strength of the solder alloy. In addition, the matrix is ​​prone to introduce Cu impurities during the welding process, which does not meet the processing requirements of microwave components.

[0006] For example, Zn can reduce the melting point of Al-Si solder. However, excessive addition of Zn will occupy a large number of solid solution positions, resulting in the accumulation of brittle phases in the structure, affecting the strength of the solder alloy. Moreover, due to the low boiling point of Zn, it is possible to cause great pollution to the vacuum brazing furnace during the welding process.

[0007] For example, Ge can also reduce the melting point of Al-Si solder, and the solder has good fluidity and spreadability. However, the addition of Ge will greatly increase the brittleness of the solder, and the corrosion resistance will deteriorate, which does not meet the processing requirements of microwave components.

[0008] The inventors found that Al-Si-Mg solder is very suitable for vacuum brazing of microwave components. However, the melting temperature range of Al-Si-Mg solder is relatively wide. If Al-Si-Mg solder is used for multiple welding at different welding points, it is easy to cause the solder in the previous weld to remelt during the next welding process.

[0009] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those skilled in the art. Summary of the invention

[0010] The purpose of the present invention is to provide a multiple brazing method, which overcomes the traditional technical prejudice that different melting point brazing materials must be used when multiple brazings are performed on aluminum alloy workpieces using a vacuum brazing furnace. The technical problem that the brazing material in the previous weld is prone to remelting during the next welding process when multiple vacuum brazings are performed using a single Al-Si-Mg brazing material is solved. The risk of brazing material loss can be reduced, and the yield rate of three-dimensional microwave components can be improved.

[0011] According to one aspect of the present disclosure, a multiple brazing method is provided for vacuum brazing of aluminum alloy workpieces to be welded, the workpieces to be welded comprising a cavity, a first cover plate and a second cover plate, the cavity having a first surface and a second surface that are not parallel, the first cover plate being used for welding to the first surface, and the second cover plate being used for welding to the second surface, the multiple brazing method comprising:

[0012] The first pre-welding assembly is to clamp the workpiece to be welded in a brazing device, the brazing device includes a pad and a tooling bottom plate, the workpiece to be welded is clamped between the pad and the tooling bottom plate, and the pad is used to press the first cover plate against the first surface;

[0013] First brazing;

[0014] The second pre-welding assembly is to clamp the workpiece to be welded on the brazing device, clamp the workpiece to be welded between the pad and the tooling bottom plate, use the pad to press the second cover plate to the second surface, and use the clamp to press the welded first cover plate to the first surface;

[0015] Second brazing;

[0016] The first brazing step uses the first brazing filler metal, and the second brazing step uses the second brazing filler metal. Both the first brazing filler metal and the second brazing filler metal are aluminum-silicon-magnesium brazing fillers.

[0017] In an exemplary embodiment of the present disclosure, the second pre-welding assembly step further includes: clamping a gasket between the clamping plate and the welded first cover plate.

[0018] In an exemplary embodiment of the present disclosure, the gasket includes at least graphite material.

[0019] In an exemplary embodiment of the present disclosure, the thickness of the solder used in the first soldering step is greater than the thickness of the solder used in the second soldering step.

[0020] In an exemplary embodiment of the present disclosure, the first solder is the same as the second solder.

[0021] In an exemplary embodiment of the present disclosure, the welding temperature of the first brazing step is T1, and the welding temperature of the second brazing step is T2, wherein 0°C<T1-T2<10°C.

[0022] In an exemplary embodiment of the present disclosure, the welding temperature of the first brazing step is 610°C, and the welding temperature of the second brazing step is 605°C.

[0023] In an exemplary embodiment of the present disclosure, the clamping plates are arranged in pairs on opposite sides of the workpiece to be welded; the clamping plates include a fixed clamping plate and a movable clamping plate; the fixed clamping plate is fixed to the tooling bottom plate, and the movable clamping plate is arranged on one side of the fixed clamping plate close to the workpiece to be welded; the movable clamping plate is movably connected to the fixed clamping plate through a first compression spring, and the first compression spring is compressed between the movable clamping plate and the fixed clamping plate;

[0024] Using a clamping plate to press the welded first cover plate onto the first surface includes:

[0025] Move the movable clamping plates on both sides of the workpiece to be welded toward the corresponding fixed clamping plates to further compress the first compression spring;

[0026] Clamp the workpiece to be welded between the movable clamping plates on both sides;

[0027] The external force on the movable clamp is released, so that the movable clamp presses the welded first cover plate against the first surface under the action of the first compression spring.

[0028] In an exemplary embodiment of the present disclosure, the multiple brazing method includes an i-th brazing (i≥2), the welding temperature is Ti, T(i-1)-Ti>0.

[0029] In an exemplary embodiment of the present disclosure, 3°C ≤ T(i-1)-Ti ≤ 5°C.

[0030] The multiple brazing method disclosed in the present invention can use a clamp to press the welded first cover plate to increase the weld thickness between the first cover plate and the cavity, reduce heat conduction, reduce the risk of remelting, and improve the yield rate of three-dimensional microwave components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for those skilled in the art, other accompanying drawings can also be obtained based on these accompanying drawings without paying creative work.

[0032] In order to better understand the present disclosure, reference may be made to the embodiments shown in the following drawings. The components in the drawings are not necessarily to scale, and related elements may be omitted in order to emphasize and clearly illustrate the technical features of the present disclosure. In addition, related elements or components may have different arrangements as known in the art. In addition, in the drawings, the same reference numerals represent the same or similar components in each drawing. Among them:

[0033] Figure 1 It is a structural schematic diagram of a workpiece to be welded.

[0034] Figure 2 It is a schematic diagram of the process of the multiple brazing method disclosed in the present invention.

[0035] Figure 3 FIG. 1 is a schematic diagram of the assembly before the first welding in an exemplary embodiment of the multiple brazing method disclosed herein.

[0036] Figure 4 FIG. 1 is a schematic diagram of assembly before the second welding in an exemplary embodiment of the multiple brazing method disclosed herein.

[0037] Figure 5 FIG. 1 is a temperature curve of the first brazing process in an exemplary embodiment of the multiple brazing method disclosed in the present invention.

[0038] Figure 6 FIG. 1 is a temperature curve of the second brazing process in an exemplary embodiment of the multiple brazing method disclosed in the present invention.

[0039] Figure 7 It is a schematic diagram of the first welding weld position and the second welding weld position on another workpiece to be welded.

[0040] Figure 8 FIG. 1 is a schematic diagram of the assembly before the first welding in an exemplary embodiment of the multiple brazing method disclosed herein.

[0041] Fig. 9 FIG. 1 is a schematic diagram of assembly before the second welding in an exemplary embodiment of the multiple brazing method disclosed herein.

[0042] The following are the descriptions of the reference numerals:

[0043] 1. Tooling bottom plate; 11. Cavity; 12. First cover plate; 13. Second cover plate; 2. Pad; 3. Clamp; 31. Fixed clamp; 32. Movable clamp; 321. First movable clamp; 322. Second movable clamp; 33. First compression spring; 4. Upper fixed plate; 51. Push rod; 52. Second compression spring; 53. Fixing nut; a. First weld; b. Second weld. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the exemplary embodiments of the present disclosure to clearly and completely describe the technical solutions in the exemplary embodiments of the present disclosure. The exemplary embodiments described herein are only for illustrative purposes and are not intended to limit the scope of protection of the present disclosure. Therefore, it should be understood that various modifications and changes can be made to the exemplary embodiments without departing from the scope of protection of the present disclosure.

[0045] Unless otherwise specified or explained, the technical terms or scientific terms used in the present disclosure shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The present disclosure uses "first" and "second" etc. only as labels, and does not limit the quantity, importance or order of its objects. The words "include" or "comprise" mean that the elements appearing before the word include the elements listed after the word and their equivalents, without excluding other elements. The terms "connected", "fixed" etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection, and can be directly connected or indirectly connected through an intermediate medium.

[0046] In addition, in the present disclosure, directional terms such as "upper" and "lower" are only used to indicate relative positional relationships. For example, for convenience, the description is based on the placement of the brazing device in actual operation and the angles shown in the drawings, which should not be understood as limiting the exemplary embodiments of the present disclosure. It should be understood that these directional terms are relative concepts, which can change accordingly according to the changes in the orientation of the components in the drawings.

[0047] The experiment found that Al-Si-Mg solder is very suitable for vacuum brazing of microwave components. However, the melting temperature range of Al-Si-Mg solder is relatively wide. If Al-Si-Mg solder is used for multiple welding at different welding points, it is easy to cause the solder in the previous weld to remelt during the next welding process.

[0048] Based on the above problems, the present disclosure provides a multiple brazing method for vacuum brazing of aluminum alloy workpieces to be welded. There are multiple non-parallel welding planes on the workpieces to be welded. For example, please refer to Figure 1 The structure of a workpiece to be welded is shown. Through process decomposition, the structure must be realized through welding process. The workpiece to be welded includes a cavity 11, a first cover plate 12 and a second cover plate 13. The cavity 11 has a first surface and a second surface that are not parallel. The first cover plate 12 is used to weld to the first surface, and the second cover plate 13 is used to weld to the second surface. It can be seen that two weld forms in different directions are distributed on the workpiece to be welded, and the two welds are not parallel. Exemplarily, the first surface and the second surface can be two surfaces that are perpendicular and adjacent to each other on the cavity 11, and the two welds on the workpiece to be welded are perpendicular to each other.

[0049] The multiple brazing method provided by the present disclosure performs vacuum brazing on the workpiece to be welded at least twice, that is, at least comprises welding the first side and the second side of the workpiece to be welded which are not parallel to each other respectively. The multiple brazing method comprises:

[0050] Step S100: assembling before the first welding, clamping the workpiece to be welded in the brazing device, the brazing device includes a pad 2 and a tooling base plate 1, the workpiece to be welded is clamped between the pad 2 and the tooling base plate 1, and the pad 2 is used to press the first cover plate 12 against the first surface.

[0051] Step S200: first brazing.

[0052] Step S300: Second pre-welding assembly, clamp the workpiece to be welded in the brazing device, clamp the workpiece to be welded between the pad 2 and the tooling base plate 1, use the pad 2 to press the second cover plate 13 to the second surface, and use the clamping plate 3 to press the welded first cover plate 12 to the first surface.

[0053] Step S400: second brazing.

[0054] The first brazing step uses the first brazing filler metal, and the second brazing step uses the second brazing filler metal. Both the first brazing filler metal and the second brazing filler metal are aluminum-silicon-magnesium brazing fillers.

[0055] Schematic diagram of the steps of the multiple brazing method Figure 2 As shown, before the two brazings in step S200 and step S400, pre-welding assembly is performed on the brazing device. Among them, in the first pre-welding assembly in step S100, the position of the first cover plate 12 relative to the cavity 11 can be fixed by the pad 2, so that the first cover plate 12 can be accurately and firmly welded to the first surface in the first brazing in step S200. In the second pre-welding assembly in step S300, the position of the second cover plate 13 relative to the cavity 11 can be fixed by the pad 2, so that the second cover plate 13 can be accurately and firmly welded to the second surface in the second brazing in step S400. In the second pre-welding assembly in step S300, the first cover plate 12 that has been welded is pressed by the clamp 3, which can increase the weld thickness between the first cover plate 12 and the cavity 11, reduce heat conduction, reduce the risk of remelting, and improve the yield rate of three-dimensional microwave components.

[0056] In addition, in the multiple brazing methods provided by the present disclosure, aluminum-silicon-magnesium brazing filler metals are used for both the first brazing and the second brazing. Since the clamping plate 3 increases the thickness of the weld where the first welding is completed, the brazing filler metal in the previous weld (the weld between the first cover plate 12 and the first surface after welding) is not easy to heat up to the temperature at which remelting occurs in the subsequent welding process (the process of welding the second cover plate 13 and the second surface). Both the first brazing filler metal and the second brazing filler metal are aluminum-silicon-magnesium brazing filler metals, and the aforementioned various components such as Cu element, Zn element, Ge element, etc. for changing the melting point of the brazing filler metal do not need to be introduced, which reduces the introduction of impurities, is conducive to ensuring the overall strength and corrosion resistance of microwave components, increasing the service life of the vacuum brazing furnace, improving production quality, and reducing production costs.

[0057] For example, the mass fraction of Mg in the first solder is 1.3%-1.7%. For example, the mass fraction of Si in the first solder is 10.2%-11.8%, and the solder specification is 0.05 mm.

[0058] In an exemplary embodiment of the present disclosure, the first solder is the same as the second solder. The mass fractions of Mg and Si in the second solder are the same as those in the first solder, which can reduce the risk of loss of the solder in the first soldering in step S200 in the second soldering in step S400, simplify the process, and reduce procurement costs.

[0059] refer to Figure 3 to Figure 4 A schematic diagram of a brazing device is shown. Figure 3 The schematic diagram of step S100 is a first pre-welding assembly, where the workpiece to be welded is clamped in the brazing device. Figure 4 The schematic diagram of step S300 is a second pre-welding assembly, where the workpiece to be welded is clamped in the brazing device.

[0060] The brazing device comprises: a tooling base plate 1 for placing the workpiece to be welded; a pad 2, which is arranged on opposite sides of the tooling base plate 1 to the workpiece to be welded. The tooling base plate 1 may include a work surface, such as Figure 3 , Figure 4 The top of the tooling base plate 1 is a work surface. When the workpiece to be welded is clamped and fixed, the bottom surface of the workpiece to be welded that does not need to be welded can be placed on the work surface. The work surface can be a horizontal plane to accurately position the workpiece.

[0061] refer to Figure 1 , Figure 3 as well as Figure 4 As shown, since the two welds are vertically distributed, the components cannot be welded at one time, and the vacuum brazing process needs to be performed twice in steps, which increases the difficulty of welding. Specifically, in the first brazing, the cavity 11 and the first cover plate 12 are welded first; after welding, it is processed and then welded to the second cover plate 13 for the second time.

[0062] It can be understood by those skilled in the art that the present disclosure only uses the first cover plate 12 and the first surface, and the second cover plate 13 and the second surface as a way to distinguish the two welding locations. That is, the welding in step S200 is called the first cover plate 12 and the first surface, and the welding in step S400 is called the second cover plate 13 and the second surface. Even if the first cover plate 12 and the second cover plate 13, the first surface and the second surface are swapped, it does not affect the implementation of the technical solution of the present disclosure. In some exemplary embodiments, the multiple brazing method can also weld more non-parallel surfaces of the workpiece to be welded. For example, the multiple brazing method can also include the i-th welding clamp assembly step and the i-th welding step, and the welded parts and welding locations can be represented by the i-th cover plate and the i-th surface, respectively. It can be seen that the technical solution provided by the present disclosure has nothing to do with the naming of the components.

[0063] In an exemplary embodiment of the present disclosure, step S300 of the second pre-welding assembly further includes: sandwiching a gasket between the clamping plate 3 and the first cover plate 12 after welding. The gasket can reduce the heat conduction at the weld seam after the first welding, reduce the risk of remelting, and prevent the clamping plate 3 from adhering to the first cover plate 12 or the first surface with a higher temperature after welding.

[0064] Exemplarily, the gasket includes at least graphite material. Graphite has the advantages of good high temperature resistance and stable properties, and is not easy to react with the clamping plate 3 or the workpiece to be welded at high temperature. In an exemplary embodiment of the present disclosure, the gasket is a graphite sheet. In an exemplary embodiment of the present disclosure, the thickness of the gasket is 0.15mm~0.25mm. For example, the thickness of the gasket is 0.18-0.2mm, which can play a heat insulation role and prevent the clamping plate 3 from adhering to the workpiece.

[0065] In an exemplary embodiment of the present disclosure, during the welding of multiple groups of workpieces to be welded, the gasket needs to be replaced each time the second pre-welding assembly of step S300 is performed to prevent the gasket from being worn out during the previous round of welding, which may result in the gasket being unable to provide sufficient insulation during the next round of welding.

[0066] In an exemplary embodiment of the present disclosure, the thickness of the solder used in the first brazing in step S200 is greater than the thickness of the solder used in the second brazing in step S400, so that the weld is not easily remelted and lost during the second brazing.

[0067] In an exemplary embodiment of the present disclosure, the welding temperature of the first brazing step is T1, and the welding temperature of the second brazing step is T2, wherein T1-T2>0, that is, the welding temperature of the second brazing step is lower than that of the first brazing step.

[0068] For example, the first brazing in step S200 includes: gradient heating and heat preservation, brazing after heating to the welding temperature, and cooling with the furnace after heat preservation.

[0069] In an exemplary embodiment, Figure 5 The first brazing process temperature curve is shown for brazing.

[0070] Among them, the first brazing process includes:

[0071] Section A: heating from room temperature to 400°C for 30-60 minutes; Section B: keeping warm for 30-60 minutes;

[0072] Section C: heating for 15-30 minutes, from 400°C to 550°C; Section D: heat preservation for 60-90 minutes;

[0073] Section E: heating for 40-60 minutes, from 550°C to 575°C; Section F: keeping warm for 20-30 minutes;

[0074] Section G: heating for 15-30 minutes, from 575℃ to 610℃; Section H: heat preservation for 5-15 minutes;

[0075] Stage I: Cooling with the furnace.

[0076] The welding temperature of the first brazing is 610°C. After the welding is completed, the furnace is cooled and the furnace is taken out at 70°C.

[0077] Step S400 is the second brazing, including: gradient heating and heat preservation, brazing after heating to the welding temperature, and cooling with the furnace after heat preservation.

[0078] In an exemplary embodiment, Figure 6 Brazing is performed using the temperature curve of the second brazing process shown.

[0079] Among them, the second brazing process includes:

[0080] Section A: heating from room temperature to 400°C for 30-60 minutes; Section B: keeping warm for 30-60 minutes;

[0081] Section C: heating for 15-30 minutes, from 400°C to 550°C; Section D: heat preservation for 60-90 minutes;

[0082] Section E: heating for 40-60 minutes, from 550°C to 575°C; Section F: keeping warm for 20-30 minutes;

[0083] Section G: heating for 15-30 minutes, from 575℃ to 605℃; Section H: heat preservation for 5-15 minutes;

[0084] Stage I: Cooling with the furnace.

[0085] The second brazing temperature is 605°C. After the welding is completed, the furnace is cooled and the furnace is taken out at 70°C.

[0086] In an exemplary embodiment, by controlling the parameters of the second brazing process so that the welding temperature of the second brazing is lower than that of the first brazing, the risk of remelting of the weld of the first brazing during the second brazing can be reduced, thereby improving the yield of three-dimensional microwave components.

[0087] Exemplarily, T1-T2<10°C, for example, T1-T2=5°C.

[0088] In an exemplary embodiment of the present disclosure, the multiple brazing method includes the i-th brazing (i≥2), the welding temperature is Ti, T(i-1)-Ti>0. That is, in the multiple welding, when the i-th cover plate is welded to the i-th surface, the welding temperature is lower than the previous (i-1th) welding temperature. In the multiple welding, by controlling the parameters of each welding process to reduce the welding temperature gradient, the risk of remelting of the weld of the previous welding in the subsequent welding can be reduced.

[0089] For example, parameter control of the welding process in multiple welding processes includes: 3℃≤T(i-1)-Ti≤5℃. On the one hand, it can reduce the risk of remelting of the weld of the previous welding process in the next welding process. On the other hand, it can also ensure that the welding temperature of each welding process meets the process requirements and prevent the quality of brazing from decreasing.

[0090] In some exemplary embodiments of the present disclosure, on the one hand, the thickness of the weld where the first welding is completed is increased by the clamping plate 3, so that the temperature rise of the previous weld is lower than that of the next weld, and on the other hand, by strictly controlling the temperature curve of the welding process, the solder in the previous weld is not easy to remelt during the next welding process. Further, in some exemplary embodiments, the gasket made of graphite is sandwiched between the clamping plate 3 and the first cover plate 12 after welding by the clamping plate 3. The clamping plate 3 and the gasket jointly reduce the heat conduction of the previous weld, making it difficult to heat up. At the same time, in conjunction with the control of the temperature curve of the welding process, the effect of preventing the solder from being lost during multiple brazing can be achieved, and the three-dimensional microwave components after welding have a high yield rate.

[0091] In an exemplary embodiment of the present disclosure, before step S100, a first cleaning before welding is also included. The first cleaning before welding may include:

[0092] Step S410: etching the cavity 11 and the first cover plate 12 to remove surface oil stains;

[0093] Step S420: flushing the cavity 11 and the first cover plate 12;

[0094] Step S430: the cavity 11 and the first cover plate 12 are immersed in a nitric acid solution;

[0095] Step S440: flushing the cavity 11 and the first cover plate 12;

[0096] Step S450: drying the chamber 11 and the first cover plate 12;

[0097] Step S460 : inspecting the cavity 11 and the first cover plate 12 for any excess matter.

[0098] Exemplarily, step S410 may include: etching the cavity 11 and the first cover plate 12 in a 5%-10% sodium hydroxide aqueous solution at 60-80° C. for 1-3 minutes until all oil stains on the surface of the workpiece are visually removed.

[0099] Step S420 may include: flushing the cavity 11 and the first cover plate 12 with circulating water, and first flushing with hot water at 40-60° C., which is conducive to cleaning the alkaline substances on the surface of the workpiece.

[0100] Step S430 may include: immersing the cavity 11 and the first cover plate 12 in a 15%-20% nitric acid solution at room temperature for 1-2 minutes until the black film is visually removed.

[0101] Step S440 may include: repeatedly cleaning the cavity 11 and the first cover plate 12 in a flowing cold water tank and a hot water tank.

[0102] Step S450 may include: placing the cleaned cavity 11 and the first cover plate 12 in a 50 degree oven for drying for 30 minutes.

[0103] Step S460 may include: inspecting the dried parts for excess matter under a 20x microscope.

[0104] After step S460, in an exemplary embodiment, the multiple brazing method may further include: performing the first pre-welding assembly in step S100 and the first brazing in step S200 on the parts dried in step S450 within 24 hours.

[0105] It should be noted that the above embodiment only illustrates the process parameters of the first pre-welding cleaning, and those skilled in the art may also adjust them according to actual needs, such as increasing the number of cleaning times or changing the immersion time for removing oil stains.

[0106] In an exemplary embodiment of the present disclosure, before step S300, a second pre-welding cleaning is also included. The second pre-welding cleaning may include:

[0107] Step S510: etching the welded cavity 11 and the second cover plate 13 to be welded to remove surface oil stains;

[0108] Step S520: flushing the cavity 11 and the second cover plate 13;

[0109] Step S530: the cavity 11 and the second cover plate 13 are immersed in a nitric acid solution;

[0110] Step S540: flushing the cavity 11 and the second cover plate 13;

[0111] Step S550: drying the chamber 11 and the second cover plate 13;

[0112] Step S560 : inspecting the cavity 11 and the second cover plate 13 for any excess matter.

[0113] Exemplarily, step S510 may include: etching the cavity 11 and the second cover plate 13 in a 5%-10% sodium hydroxide aqueous solution at 60-80° C. for 1-3 minutes until all oil stains on the workpiece surface are visually removed.

[0114] Step S520 may include: flushing the cavity 11 and the second cover plate 13 with circulating water, and first flushing with hot water at 40-60° C., which is conducive to cleaning the alkaline substances on the surface of the workpiece.

[0115] Step S530 may include: immersing the cavity 11 and the second cover plate 13 in a 15%-20% nitric acid solution at room temperature for 1-2 minutes until the black film is visually removed.

[0116] Step S540 may include: repeatedly cleaning the cavity 11 and the second cover plate 13 in a flowing cold water tank and a hot water tank.

[0117] Step S550 may include: placing the cleaned cavity 11 and the second cover plate 13 in a 50 degree oven for drying for 40 minutes.

[0118] Step S560 may include: inspecting the dried parts for excess matter under a 20x microscope.

[0119] After step S560, in an exemplary embodiment, the multiple brazing method may further include: performing a first pre-welding assembly in step S300 and a second brazing in step S400 on the parts dried in step S550 within 24 hours.

[0120] In an exemplary embodiment of the present disclosure, the clamping plates 3 are arranged in pairs on opposite sides of the workpieces to be welded; Figure 3As shown, the clamping plate 3 includes a fixed clamping plate 31 and a movable clamping plate 32; the fixed clamping plate 31 is fixed to the tooling bottom plate 1, and the movable clamping plate 32 is arranged on the side of the fixed clamping plate 31 close to the workpiece to be welded. The movable clamping plate 32 is arranged at an adjustable distance relative to the fixed clamping plate 31, and the movable clamping plate 32 is used to move in a direction away from the fixed clamping plate 31 to press the welded first cover plate 12 against the first surface.

[0121] For example, the movable clamping plate 32 is movably connected to the fixed clamping plate 31 through the first compression spring 33, and the first compression spring 33 is compressed when the movable clamping plate 32 is pressed against the welded first cover plate 12. Figure 3 As shown, the first compression spring 33 can provide a stable and uniform thrust to the movable clamp 32, which causes the movable clamp 32 to press the first cover plate 12, for example, clamping the gasket between the movable clamp 32 and the first cover plate 12, so that the gasket is tightly attached to the first cover plate 12, reducing heat conduction at the weld and preventing adhesion, thereby preventing the gasket from falling off.

[0122] For example, using the clamping plate 3 to press the welded first cover plate 12 onto the first surface includes:

[0123] Move the movable clamping plates 32 on both sides of the workpiece to be welded toward the corresponding fixed clamping plates 31 to further compress the first compression spring 33;

[0124] Clamp the workpiece to be welded between the movable clamping plates 32 on both sides;

[0125] The external force on the movable clamping plate 32 is released, so that the movable clamping plate 32 presses the welded first cover plate 12 against the first surface under the action of the first compression spring 33 .

[0126] Exemplarily, the thickness of the movable splint 32 is not less than 8 mm, for example, the thickness of the movable splint 32 may be 8 to 10 mm. Exemplarily, the thickness of the fixed splint 31 is not less than 8 mm, for example, the thickness of the fixed splint 31 may be 8 to 10 mm. In an exemplary embodiment of the present disclosure, the thickness of the movable splint 32 is equal to the thickness of the fixed splint 31. In an exemplary embodiment of the present disclosure, the thickness of the fixed splint 31 is greater than the thickness of the movable splint 32, for example, the fixed splint 31 is 2 to 3 mm thicker than the thickness of the movable splint 32.

[0127] In an exemplary embodiment of the present disclosure, reference Figure 4 As shown, the clamping plates 3 are arranged in pairs on two sides of the workpiece to be welded that are perpendicular to the tooling base plate 1 (the left and right sides in the figure). Figure 4 The clamping plate 3 on the left side is used to press the welded first cover plate 12 against the first surface when welding the second cover plate 13; the other clamping plate 3 ( Figure 4The clamping plate 3 on the middle right side is used to press the cavity 11 against the clamping plate 3 on the opposite side when the second cover plate 13 is welded.

[0128] In an exemplary embodiment of the present disclosure, the brazing device includes an upper fixing plate 4 and a push rod 51. The upper fixing plate 4 and the tooling bottom plate 1 are arranged on opposite sides of the workpiece to be welded, the push rod 51 is movably connected relative to the upper fixing plate 4, the cushion block 2 is arranged on a side of the push rod 51 close to the workpiece to be welded, and the push rod 51 is used to move toward the tooling bottom plate 1 to press the cushion block 2 against the workpiece to be welded.

[0129] refer to Figure 3 , Figure 4 As shown, the multiple brazing method includes: the first pre-welding assembly in step S100 and the second pre-welding assembly in step S300, both of which include: placing the workpiece to be welded on the work surface of the tooling base plate 1, and pressing the cushion block 2 to the top of the workpiece to be welded by the push rod 51.

[0130] The upper fixed plate 4 is arranged above the workpiece to be welded. The push rod 51 can pass through the through hole of the upper fixed plate 4 and press the cushion block 2 against the top of the workpiece to be welded. Exemplarily, the push rod 51 can be a stud, and the head of the push rod 51 is connected to the cushion block 2, which is used to make the cushion block 2 relatively close to or away from the workpiece to be welded. The tail threaded section of the push rod 51 passes through the through hole of the upper fixed plate 4 from bottom to top, and the top is tightened by the fixing nut 53 and fixed on the upper fixed plate 4. By adjusting the position of the fixing nut 53 on the push rod 51, the distance between the head of the push rod 51 and the upper fixed plate 4 can be changed, so that the cushion block 2 is pressed against the workpiece to be welded, and can adapt to the workpiece to be welded whose size varies within a certain range.

[0131] In an exemplary embodiment of the present disclosure, a second compression spring 52 is sleeved on the portion of the push rod 51 between the upper fixing plate 4 and the tooling bottom plate 1. When the push rod 51 presses the cushion block 2 against the workpiece to be welded, the second compression spring 52 is compressed. Figure 3 , Figure 4 As shown, the second compression spring 52 can be sleeved between the head of the push rod 51 and the lower surface of the upper fixing plate 4. The second compression spring 52 cooperates with the push rod 51 to fix the workpiece to be welded, ensuring that during the welding process, the first cover plate 12 and the first surface are always kept in close contact, or the second cover plate 13 and the second surface are always kept in close contact, relying on the elasticity of the spring, and the thermal expansion and contraction deformation of the workpiece to be welded due to temperature changes is not affected. Under the condition of ensuring close contact between the workpiece and the solder, by applying a certain force to the weld, the workpiece can always maintain close contact under heating and cooling conditions, which is conducive to the wetting of the solder and the formation of the weld.

[0132] Exemplarily, a plurality of push rods 51 may be provided on the upper fixed plate 4, each push rod 51 is movably connected relative to the upper fixed plate 4, a cushion block 2 is provided on the side of the push rod 51 close to the workpiece to be welded, and a second compression spring 52 is sleeved on the portion of each push rod 51 located between the upper fixed plate 4 and the tooling bottom plate 1. For example, multiple rows and columns of through holes are arranged on the upper fixed plate 4 along the length and width direction of the upper fixed plate 4, and multiple push rods 51 are penetrated in the through holes in a one-to-one correspondence. The push rods 51 may be equidistantly distributed in the length direction, or equidistantly distributed in the width direction, or the push rods 51 may be unequally spaced in the length direction, and the spacing in the width direction may also be unequal. Exemplarily, the specific positions of each push rod 51 may be arranged according to the structure of the workpiece to be welded, so that during the welding process, the cushion block 2 exerts a consistent pressing force on each part of the workpiece to be welded, thereby ensuring the consistency of the weld.

[0133] Exemplarily, the second compression spring 52 can be made of GH4145 material, which can be used at an ambient temperature of 600°C, meeting the vacuum brazing temperature conditions. In other exemplary embodiments, the second compression spring 52 can also be made of other high-temperature alloy materials. Exemplarily, during multiple welding processes, it is necessary to replace the second compression spring 52 in a timely manner according to the state change of the second compression spring 52, or replace the second compression spring 52 regularly to ensure that the elasticity of the second compression spring 52 does not significantly decrease or plastically deform, and can continue to provide a suitable clamping force. Exemplarily, the first compression spring 33 can also be made of GH4145 material, or other high-temperature alloy materials. The first compression spring 33 and the second compression spring 52 can be made of the same material.

[0134] In an exemplary embodiment of the present disclosure, the second compression spring 52 cooperates with the ejector rod 51, and the first compression spring 33 cooperates with the movable clamping plate 32, so as to apply elastic force to the workpiece to be welded, effectively solve the difference in thermal expansion size caused by different materials between the product and the tooling, and prevent welding deformation. Exemplarily, the clamping force can be 20-50 kPa.

[0135] In an exemplary embodiment of the present disclosure, the multiple brazing method and the provided brazing device of the present disclosure can be used for batch welding of multiple workpieces to be welded. The "multiple" mentioned in the present disclosure can refer to greater than or equal to 2. The workpiece to be welded may include multiple cavities 11, multiple first cover plates 12, and a pair of connecting flanges (equivalent to the second cover plate 13). Through process separation, the first cover plates 12 need to be welded to the cavities 11 one by one, and then the multiple cavities 11 need to be welded between the connecting flanges (second cover plates 13) at both ends. For example, Figure 7 The position a of the first welding seam and the position b of the second welding seam are shown. It can be seen that two weld seam forms in different directions are distributed on the workpiece to be welded, and the two weld seams are not parallel. For example, the first surface is perpendicular to the second surface, and the two weld seams on the workpiece to be welded are perpendicular to each other.

[0136] Specifically, Figure 8 A schematic diagram of the assembly before the first welding is shown. Fig. 9 The schematic diagram of the second pre-welding assembly is shown. The implementation of the tooling base plate 1, the cushion block 2 and the clamping plate 3 can refer to the aforementioned exemplary implementation, which will not be repeated here. The implementation of the first pre-welding assembly of step S100 and the second pre-welding assembly of step S300 can also refer to the aforementioned exemplary implementation, which will not be repeated here.

[0137] For example, in step S200, the first brazing is performed to weld the cavity 11 and the first cover plate 12. A plurality of ejector pins 51 may be provided on the upper fixed plate 4, each ejector pin 51 is movably connected to the upper fixed plate 4, a cushion block 2 is provided on the side of the ejector pin 51 close to the workpiece to be welded, and a second compression spring 52 is sleeved on the part of each ejector pin 51 located between the upper fixed plate 4 and the tooling bottom plate 1. During the welding process, the cushion block 2 exerts a consistent pressing force on each part of the first cover plate 12 to ensure the consistency of the weld.

[0138] Exemplarily, step S400 is a second brazing process, in which the cavity 11 and the second cover plate 13 (connecting flange) are welded. The second cover plate 13 is provided with a positioning groove matching the cavity 11 for positioning the cavity 11. Fig. 9 As shown, in an exemplary embodiment, a clamping plate 3 may be provided between two adjacent cavities 11, and the clamping plate 3 includes a first movable clamping plate 321 and a second movable clamping plate 322 connected to each other by a first compression spring 33, and the first compression spring 33 is compressed between the first movable clamping plate 321 and the second movable clamping plate 322 to provide a pushing force for the first movable clamping plate 321 and the second movable clamping plate 322 to move away from each other. Fig. 9 As shown, the workpiece to be welded may include at least two cavities 11, and the clamps 3 are arranged in pairs outside the two outermost cavities 11. For example, the fixed clamps 31 are respectively fixed to the outer sides of the two outermost cavities 11 on the tooling base plate 1, and the movable clamps 32 are arranged on the side of the fixed clamps 31 close to the workpiece to be welded. A first movable clamp 321 and a second movable clamp 322 connected to each other by a first compression spring 33 are arranged between adjacent cavities 11. The first movable clamp 321 is used to press the cavity 11 on one side to the first cover plate 12 corresponding to the cavity 11, and the second movable clamp 322 is used to press the first cover plate 12 on the other side to the cavity 11 corresponding to the first cover plate 12.

[0139] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. The present disclosure is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The description and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A multiple brazing method, characterized in that: Used for vacuum brazing of aluminum alloy workpieces to be welded, the workpieces to be welded comprising a cavity (11), a first cover plate (12) and a second cover plate (13), the cavity (11) having a first surface and a second surface that are not parallel, the first cover plate (12) being used to be welded to the first surface, and the second cover plate (13) being used to be welded to the second surface, the multiple brazing method comprising: The first pre-welding assembly comprises clamping the workpiece to be welded on a brazing device, wherein the brazing device comprises a cushion block (2) and a tooling base plate (1), the workpiece to be welded is clamped between the cushion block (2) and the tooling base plate (1), and the first cover plate (12) is pressed against the first surface by using the cushion block (2); A first brazing process is performed to weld the first cover plate (12) to the first surface; The second pre-welding assembly comprises clamping the workpiece to be welded in the brazing device, clamping the workpiece to be welded between the cushion block (2) and the tooling bottom plate (1), using the cushion block (2) to press the second cover plate (13) against the second surface, and using the clamping plate (3) to press the welded first cover plate (12) against the first surface; A second brazing process is performed to weld the second cover plate (13) to the second surface; The first brazing step uses a first brazing filler metal, and the second brazing step uses a second brazing filler metal. Both the first brazing filler metal and the second brazing filler metal are aluminum-silicon-magnesium brazing fillers.

2. The multiple brazing method according to claim 1, characterized in that: The second pre-welding assembly step further comprises: clamping a gasket between the clamping plate (3) and the welded first cover plate (12).

3. The multiple brazing method according to claim 2, characterized in that: The gasket at least comprises graphite material.

4. The multiple brazing method according to claim 1, characterized in that: The thickness of the solder used in the first soldering step is greater than the thickness of the solder used in the second soldering step.

5. The multiple brazing method according to claim 1, characterized in that: The first solder is the same as the second solder.

6. The multiple brazing method according to claim 1, characterized in that: The welding temperature of the first brazing step is T1, and the welding temperature of the second brazing step is T2, wherein 0°C<T1-T2<10°C.

7. The multiple brazing method according to claim 6, characterized in that: The welding temperature of the first brazing step is 610°C, and the welding temperature of the second brazing step is 605°C.

8. The multiple brazing method according to any one of claims 1 to 7, characterized in that: The clamping plates (3) are arranged in pairs on opposite sides of the workpiece to be welded; the clamping plates (3) include a fixed clamping plate (31) and a movable clamping plate (32); the fixed clamping plate (31) is fixed to the tooling base plate (1), and the movable clamping plate (32) is arranged on a side of the fixed clamping plate (31) close to the workpiece to be welded; the movable clamping plate (32) is movably connected to the fixed clamping plate (31) via a first compression spring (33), and the first compression spring (33) is compressed between the movable clamping plate (32) and the fixed clamping plate (31); Using the clamping plate (3) to press the welded first cover plate (12) onto the first surface, comprising: Moving the movable clamping plates (32) on both sides of the workpiece to be welded toward the corresponding fixed clamping plates (31) to further compress the first compression spring (33); Clamping the workpiece to be welded between the movable clamping plates (32) on both sides; The external force on the movable clamping plate (32) is released, so that the movable clamping plate (32) presses the welded first cover plate (12) against the first surface under the action of the first compression spring (33).

9. The multiple brazing method according to any one of claims 1 to 7, characterized in that: The multiple brazing method includes an i-th brazing (i≥2), a welding temperature Ti, T(i-1)-Ti>0.

10. The multiple brazing method according to claim 9, characterized in that: 3℃≤T(i-1)-Ti≤5℃.

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