Vacuum brazing forming process and device for liquid cooling pipeline of AI server

Abstract

The invention relates to the technical field of vacuum brazing, in particular to an AI server liquid cooling pipeline vacuum brazing forming process and a device thereof.The liquid cooling pipeline is composed of a corrugated pipe and a connector and is made of 316 stainless steel, the liquid cooling pipeline comprises an assembly table, a plurality of positioning rods are arranged on one side of the assembly table, a brazing frame is arranged on one side of the assembly table, and a plurality of positioning rods are arranged on the other side of the assembly table. An upper pressing plate is arranged at the top of the brazing frame, a plurality of lower grooves are formed in the top of the brazing frame, and a plurality of upper grooves are formed in the top of the upper pressing plate. The vacuum brazing AI server liquid cooling pipeline is good in formability, free of surface defects and internal air holes and free of air leakage under helium leak detection, an electric push rod is started through the coaxial positioning assembly to drive a positioning rod to be inserted, a silica gel block is fixed in an expansion mode, accurate coaxial positioning of a corrugated pipe and a connector is achieved, and the production efficiency of the vacuum brazing AI server liquid cooling pipeline is improved. And uneven coating of soldering paste or segregation of a welding seam after brazing caused by assembly deviation is effectively avoided, and the uniformity and the mechanical property of the welding seam are ensured.

Description

Technical Field

[0001] The present invention relates to the field of vacuum brazing technology, and specifically to a vacuum brazing forming process and device for liquid cooling pipelines of an AI server. Background Art

[0002] Vacuum brazing technology is a kind of vacuum brazing technology. 5 The process of joining materials is accomplished by heating the brazing filler metal under pressure (~10-3 Pa) to melt the filler metal and fill the gap between the joints. Its core advantages are its non-oxidizing and pollution-free nature, making it suitable for components requiring high precision and high cleanliness, such as those in aerospace and semiconductor equipment. Furthermore, because vacuum brazing can simultaneously weld large numbers of workpieces, it is widely used in industrial stainless steel welding processes.

[0003] Patent application number "CN119772289A" proposes a brazing process for the stainless steel tube shell and Kovar alloy in a medical CT tube. This process comprehensively considers factors such as the surface treatment (nickel plating) of the Kovar alloy, brazing material selection, assembly gap control, and vacuum environment to ensure the quality and reliability of the welded joint, thus solving the problem of poor welding between the stainless steel tube shell and Kovar alloy in the prior art.

[0004] Yin Fan's article, "Vacuum Brazing of 1215 Free-Machining Steel and 302 Stainless Steel," points out that clamping with a clamp can make it difficult to control the gap between the weld seams due to burrs on the parts and the brazing material, as well as the thermal expansion coefficient of the materials. Utilizing a press on the diffusion welding equipment maintains constant pressure throughout the welding process, ensuring that the gap between the weld seams remains stable below 50 μm, thus maximizing brazing quality.

[0005] However, the boron (B) content in BNi-2 brazing filler metal is relatively high (2.75% to 3.5%). During the brazing process, B easily reacts with elements such as Cr and Fe in the base metal to form hard and brittle boride phases. For example, CrB is distributed along the grain boundaries, significantly reducing the toughness and corrosion resistance of the joint. There are also massive or plum-shaped compounds such as Ni3B and Fe2B that form in the middle of the brazing seam, leading to stress concentration and crack initiation. The above processes cannot effectively suppress these harmful phases.

[0006] In summary, the vacuum brazing process of stainless steel has been studied to some extent, but boron still forms some harmful boride phases in the weld and base metal areas. Therefore, it is necessary to explore a new vacuum brazing process method to improve the mechanical properties of the weld under vacuum brazing conditions. Summary of the Invention

[0007] The purpose of the present invention is to provide a vacuum brazing forming process and device for liquid cooling pipes of AI servers to solve the problems raised in the above background technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A vacuum brazing forming process for liquid cooling pipes of AI servers. Preferably, the liquid cooling pipes are composed of bellows and joints, and are made of 316 stainless steel. The solder used for vacuum brazing is BNi-2, and the raw material composition of the BNi-2 solder is 100% by total mass: Cr 6.0%-8.0%, Si 4.0%-5.0%, B 2.75%-3.50%, Fe 2.5%-3.5%, C <0.06%, P <0.02%, and the remainder is Ni.

[0010] The process includes the following steps:

[0011] S1. Ultrasonic cleaning of the bellows and joints: first, soaking in a degreasing tank at 50°C for 20 minutes, second, soaking in a normal temperature water tank for 10 minutes, and finally, soaking in a water tank at 70°C for 10 minutes. The ultrasonic cleaning frequency is 2.0-5.0 Hz.

[0012] S2. Blow dry the cleaned bellows and joints with an air gun at a pressure of 0.4 MPa, then place them in a drying oven at a temperature of 100°C / 1h.

[0013] S3. Assemble the bellows and the joint. First, evenly apply a paste containing nano-Ti powder (0.2-1.0% by mass) to the annular joint. Then, apply BNi-2 solder paste to obtain the pipe to be welded and place it in a brazing fixture. The nano-Ti powder has an average particle size of 100 nm. The Ti powder paste is prepared by ultrasonically stirring Ti nanoparticles, polyvinyl alcohol, polyamide wax, and stearic acid in a certain proportion.

[0014] S4. Place the brazing fixture loaded with the pipe to be welded into the vacuum brazing furnace for brazing. The process is as follows:

[0015] T1. Heat from room temperature to 550°C for 60 minutes and keep warm for 50 minutes to remove organic matter in the solder paste;

[0016] T2. Heat to 950°C for 60 minutes and keep warm for 30 minutes to pre-diffuse key elements and avoid uneven furnace temperature.

[0017] T3, heat at 950℃ for 20min to 1050℃, keep warm for 40-60min to fully combine the solder and the base material;

[0018] T4, cool from 1050℃ to 900℃ for 10 minutes, keep warm for 4 minutes to relieve thermal stress and prevent deformation;

[0019] T5. Cool from 900℃ for 150min to room temperature and then take out to avoid excessive diffusion of elements to form harmful second phase.

[0020] Preferably, in step S3, the mass percentage of Ti powder in the Ti powder paste is 0.5%.

[0021] Preferably, in step S4, the holding time of T3 is 50 min.

[0022] A vacuum brazing forming device for liquid cooling pipes of an AI server preferably comprises an assembly table, a plurality of positioning rods are provided on one side of the assembly table, and a brazing frame is provided on one side of the assembly table, an upper pressing plate is provided on the top of the brazing frame, a plurality of lower grooves are provided on the top of the brazing frame, a plurality of upper grooves are provided on the top of the upper pressing plate, a first sliding rod is symmetrically fixedly connected to the bottom of the upper pressing plate, one end of the first sliding rod passes through the brazing frame and is slidably connected to the brazing frame, a buckle tongue is symmetrically provided at one end of the brazing frame, a buckle seat adapted to the buckle tongue is symmetrically fixedly connected to one end of the upper pressing plate, the joint is inserted into the interior of the upper groove, and the top of the assembly table is inserted into the interior of the lower groove at the bottom of the brazing frame;

[0023] One end of the assembly table is provided with a coaxial positioning component for driving the positioning rod to insert into the joint and the bellows to ensure the coaxiality of the two. The top of the brazing frame is provided with a loading component for accurately coating solder paste on the periphery of the contact end of the driving joint and the bellows.

[0024] Preferably, the coaxial positioning assembly includes a second sliding rod symmetrically fixedly connected to one end of the brazing frame, and one end of the brazing frame is fixedly connected to an electric push rod, one end of two of the second sliding rods is slidably connected to a U-shaped pressing table, the output end of the electric push rod is fixedly connected to the U-shaped pressing table, and the top of the positioning rod passes through the U-shaped pressing table and is rotatably connected to the U-shaped pressing table.

[0025] Preferably, the coaxial positioning assembly also includes a piston chamber opened inside the positioning rod, the interior of the piston chamber is slidably connected to the piston rod, four expansion grooves are evenly opened on the inner side of the piston chamber, the interior of the expansion groove is fixedly connected to a silicone block, and the silicone block is used to resist the inner wall of the bellows and the joint under the push of the piston rod to enhance the positioning stability.

[0026] Preferably, the coaxial positioning assembly also includes a lever through slot symmetrically opened at one end of the U-shaped pressing platform, a rectangular handle with a slot is provided inside the lever through slot, the middle section of the rectangular handle with a slot is rotatably connected to the inner wall of the lever through slot, and a follower slot is symmetrically opened at one end of the rectangular handle with a slot, the top of the piston rod passes through the U-shaped pressing platform and is rotatably connected to the positioning rod, and a plurality of the tops of the piston rods are fixedly connected to a transmission pressure rod, and one end of the transmission pressure rod is symmetrically fixedly connected to a pair of follower sliders, the follower sliders are slidably connected to the inside of the follower slot, and the transmission pressure rod can be driven by the rotation of the rectangular handle with a slot to drive the piston rod to slide along the piston chamber.

[0027] Preferably, the loading assembly includes a synchronous wheel fixedly connected to the top of the positioning rod, a plurality of the synchronous wheels are sleeved on the periphery of a synchronous belt, one end of the U-shaped pressing table is rotatably connected to a driving wheel, the middle section of the synchronous belt passes around the periphery of the driving wheel, one end of the U-shaped pressing table is rotatably connected to a pair of limiting wheels, the two limiting wheels are arranged on the left and right sides of the driving wheel, and the limiting wheels roll in conflict with the outer side of the synchronous belt, the bottom of the U-shaped pressing table is fixedly connected to a motor, the output end of the motor is fixedly connected to the driving wheel, and the driving wheel is driven by the motor to drive the synchronous belt and the synchronous wheel to rotate, thereby causing the positioning rod to drive the bellows and the joint to rotate synchronously to cooperate with the solder paste coating.

[0028] Preferably, one end of the assembly table is symmetrically provided with a lifting slot, and the inside of the lifting slot is symmetrically fixedly connected with a third sliding rod, and one end of two adjacent third sliding rods is slidably connected to an inclined lifting rod, and the outer periphery of the third sliding rod is provided with a return spring, and the return spring is fixedly connected to the bottom of the inclined lifting rod, and the top of the brazing frame is symmetrically provided with a lifting groove adapted to the inclined lifting rod, and the bottom of the upper pressure plate is symmetrically rotatably connected with a pair of rollers, and the rollers roll in conflict with the inclined surfaces of the inclined lifting rods. When the brazing frame approaches the assembly table, the lifting rod rolls in conflict with the inclined surfaces of the rollers, and pushes the lifting rod to slide down the third sliding rod to compress the return spring, so that the lifting rod is inserted into the inside of the lifting groove, and the return spring is used to rebound and lift the upper pressure plate, so that the upper pressure plate is separated from the brazing frame, making it convenient to insert the bellows and the joint into the inside of the lower groove and the upper groove respectively.

[0029] Preferably, the loading assembly also includes a storage box symmetrically fixedly connected to the inside of the assembly table, the output end of the storage box is fixedly connected to a loading pump through a pipeline, the output end of the loading pump is fixedly connected to a multi-port distribution pipe through a pipeline, the output end of the multi-port distribution pipe is fixedly connected to a distribution pipe, the output end of the distribution pipe is fixedly connected to a paint nozzle, the paint nozzle is fixedly connected to one side of the assembly table, and the output end of the paint nozzle is aligned with the periphery of the contact end of the bellows and the joint, the two storage boxes are respectively used to store Ti powder paste and BNi-solder paste, and are output in turn to the periphery of the contact end of the bellows and the joint through the corresponding two paint nozzles, and the uniform coating of the solder paste is achieved by cooperating with the rotation of the positioning rod.

[0030] Beneficial effects of the present invention:

[0031] 1. After vacuum brazing, the AI ​​server liquid cooling pipeline produced by the present invention has good formability, no surface defects and internal pores, and no leakage under helium leak detection.

[0032] 2. The present invention pre-coats a layer of Ti powder paste when applying the solder paste, which will react with B in the solder to generate nano-TiB2 in the base material area during the brazing process. The generated nano-TiB2 can effectively improve the strength of the weld joint area without sacrificing the plasticity of the weld joint area. In addition, since the atomic radius of Ti is larger than that of Ni, a small amount of Ti dissolved into the Ni matrix is ​​beneficial to the increase of the lattice constant of the Ni-based solid solution and the increase of the crystal gap, so that more B elements can be dissolved into the gaps. The synergistic effect of the increase in the solid solubility of B and the generation of TiB2 results in less B elements and Cr and Fe elements in the base material to form brittle borides.

[0033] 3. The present invention can prevent the Fe / Ni ratio in the weld zone from increasing and reducing the plasticity of the weld while allowing the brazing filler metal and the base material to diffuse into each other and form a metallurgical bond by adjusting the holding time of the brazing temperature.

[0034] 4. The present invention activates the electric push rod through the coaxial positioning assembly to drive the positioning rod to be inserted, so that the silicone block expands and is fixed, thereby achieving precise coaxial positioning of the bellows and the joint, effectively avoiding uneven solder paste coating or weld segregation after brazing caused by assembly offset, providing a basis for the metallurgical bonding stability of subsequent vacuum brazing, and ensuring the uniformity and mechanical properties of the weld.

[0035] 5. The feeding assembly of the present invention drives the workpiece to rotate synchronously through a motor, and cooperates with the dual storage box and paint nozzle system to first evenly apply Ti powder paste and then apply BNi-2 solder paste. This ensures that Ti powder reacts with B to generate nano-TiB2 to strengthen the weld, and suppresses the formation of brittle borides through the solid solution effect of Ti, thereby synergistically improving the strength and toughness of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0037] Figure 1 This is a temperature flow chart of the brazing process of the present invention;

[0038] Figure 2 It is a schematic diagram of the overall structure of the molding device in the present invention;

[0039] Figure 3 It is a schematic diagram of the three-dimensional structure of the bellows and the joint in the present invention;

[0040] Figure 4 This is an exploded view of the connection relationship between the brazing frame and the upper pressing plate in the present invention;

[0041] Figure 5 It is a schematic diagram of the three-dimensional structure of the assembly platform of the present invention;

[0042] Figure 6 It is a schematic diagram of the back structure of the U-shaped pressing table in the present invention;

[0043] Figure 7 It is a front structural schematic diagram of the U-shaped pressing table in the present invention;

[0044] Figure 8 It is a schematic diagram of the internal structure of the piston chamber in the present invention;

[0045] Figure 9 It is a schematic diagram of the internal structure of the lifting tank in the present invention;

[0046] Figure 10 It is a schematic diagram of the three-dimensional structure of the multi-port distribution pipe in the present invention;

[0047] The reference numerals in the figures are as follows: 1, bellows; 2, joint; 3, assembly table; 4, positioning rod; 5, brazing frame; 6, upper pressure plate; 7, lower groove; 8, upper groove; 9, first slide bar; 10, buckle tongue; 11, buckle seat; 12, second slide bar; 13, electric push rod; 14, U-shaped pressing table; 15, piston chamber; 16, piston rod; 17, through groove; 18, silicone block; 19, lever through groove; 20, rectangular handle with groove; 21 , follow-up groove; 22, transmission pressure rod; 23, follow-up slider; 24, synchronous wheel; 25, synchronous belt; 26, driving wheel; 27, limiting wheel; 28, motor; 29, lifting groove; 30, third slide bar; 31, inclined lifting rod; 32, return spring; 33, lifting groove; 34, roller; 35, resistance rod; 36, storage box; 37, feeding pump; 38, multi-port feeding pipe; 39, distribution pipe; 40, paint nozzle. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] A vacuum brazing process for liquid cooling pipes of AI servers, such as Figure 1-Figure 3 As shown, the following steps are included:

[0050] Example 1: The liquid cooling pipeline consists of a bellows 1 and a joint 2, and is made of 316 stainless steel.

[0051] The specific steps of the vacuum brazing process for liquid cooling pipes of an AI server are as follows:

[0052] S1. The bellows and joints are ultrasonically cleaned by soaking them in a degreasing tank at 50°C for 20 minutes, then in a water tank at room temperature for 10 minutes, and finally in a water tank at 70°C for 10 minutes. The ultrasonic cleaning frequency is set to 2.0-5.0 Hz.

[0053] S2. Use an air gun to blow dry the cleaned bellows and joints with the air pressure set to 0.4 MPa, and finally put them into a drying oven for drying with the parameter set to 100℃ / 1h;

[0054] S3. Assemble the bellows and the joint, and evenly apply a paste containing 0.2-1.0% nano-Ti powder and a BNi-2 solder paste to the annular joint to obtain the AI ​​server liquid cooling pipe to be welded, and then place the pipe into a brazing fixture.

[0055] S4. Place the brazing tool loaded with the AI ​​server liquid cooling pipes into a vacuum brazing furnace for brazing. The vacuum brazing process is as follows: T1. Heat from room temperature to 550°C for 60 minutes and then hold for 50 minutes to remove organic matter from the solder paste. T2. Heat from room temperature to 950°C for 60 minutes and then hold for 30 minutes to avoid uneven brazing furnace temperature due to rapid heating and to pre-diffusion of key elements. T3. Heat from 950°C to 1050°C for 20 minutes and then hold for 50 minutes to fully bond the solder and base material. T4. Cool from 1050°C to 900°C for 10 minutes and then hold for 4 minutes to relieve thermal stress and prevent workpiece deformation. T5. Cool from 900°C to room temperature for 150 minutes and then remove from the workpiece to avoid slow cooling that can further diffuse elements and form harmful secondary phases.

[0056] Comparative Example 1:

[0057] Refer to Example 1, except that the Ti nanoparticle paste was not applied before brazing.

[0058] Comparative Example 2:

[0059] Refer to Example 1, except that the mass percentage of Ti nanoparticles is 0.2%.

[0060] Comparative Example 3:

[0061] Refer to Example 1, except that the mass percentage of Ti nanoparticles is 1.0%.

[0062] Comparative Example 4:

[0063] Refer to Example 1, except that T3 in the brazing process of step S3 is changed to heating at 950° C. for 20 min to 1050° C. and then keeping the temperature for 40 min.

[0064] Comparative Example 5:

[0065] Refer to Example 1, except that T3 in the brazing process of step S3 is changed to heating at 950° C. for 20 min to 1050° C. and then keeping the temperature for 60 min.

[0066] Table 1 Specific parameters of Example 1 and Comparative Examples 1-5

[0067]

[0068]

[0069] The welds of the AI ​​server liquid cooling pipes of Example 1 and Comparative Examples 1-5 were further subjected to ultimate tensile testing using a DZ-101-2T servo tensile testing machine. The test results are shown in Table 2 below.

[0070] Table 2 Tensile test results of Example 1 and Comparative Examples 1-5

[0071]

[0072] As shown in Table 2 for Example 1 and Comparative Example 15, pre-coating the Ti nanoparticle paste before brazing effectively improved the mechanical properties of the weld. Adjusting the holding time at 1050°C during brazing also improved the mechanical properties of the subsequent welds. The optimal ultimate tensile strength was achieved when the mass percentage of Ti nanoparticles was 1.0% and the brazing temperature was maintained at 1050°C for 50 minutes.

[0073] Compared with related technologies, the vacuum brazing forming process for AI server liquid cooling pipes provided by the present invention has the following beneficial effects:

[0074] By pre-coating a layer of Ti nanoparticle paste before applying the BNi-2 solder paste, it is possible to effectively inhibit the diffusion of B to the base material along the grain boundaries during brazing to form brittle borides, and B will form nano-TiB2 to strengthen the weld. In addition, a small amount of Ti will dissolve into the Ni matrix to increase the gaps in the Ni matrix, which is beneficial to the solid solution of B. The synergistic effect greatly improves the mechanical properties of the vacuum brazed 316 stainless steel AI server liquid cooling pipeline. The present invention further adjusts the holding time at the brazing temperature, and avoids the increase of the Fe / Ni ratio due to a long holding time and a decrease in the mechanical properties of the weld under the premise of sufficient metallurgical bonding between the solder and the base material, thereby obtaining the optimal holding time at the brazing temperature for the vacuum brazed 316 stainless steel AI server liquid cooling pipeline.

[0075] A vacuum brazing forming device for liquid cooling pipes of AI servers, such as Figure 2-Figure 7As shown, it includes an assembly table 3, a plurality of positioning rods 4 are provided on one side of the assembly table 3, and a brazing frame 5 is provided on one side of the assembly table 3, an upper pressing plate 6 is provided on the top of the brazing frame 5, a plurality of lower grooves 7 are opened on the top of the brazing frame 5, a plurality of upper grooves 8 are opened on the top of the upper pressing plate 6, and a first slide bar 9 is symmetrically fixedly connected to the bottom of the upper pressing plate 6, one end of the first slide bar 9 passes through the brazing frame 5 and is slidably connected to the brazing frame 5, a buckle tongue 10 is symmetrically provided at one end of the brazing frame 5, a buckle seat 11 adapted to the buckle tongue 10 is symmetrically fixedly connected at one end of the upper pressing plate 6, the joint 2 is inserted into the interior of the upper groove 8, and the top of the assembly table 3 is inserted into the interior of the lower groove 7 at the bottom of the brazing frame 5;

[0076] One end of the assembly table 3 is provided with a coaxial positioning assembly for driving the positioning rod 4 to insert into the connector 2 and the bellows 1 to ensure the coaxiality of the two. The top of the brazing frame 5 is provided with a feeding assembly for accurately coating the outer periphery of the contact end of the driving connector 2 and the bellows 1.

[0077] like Figure 2-Figure 9 As shown, the coaxial positioning assembly includes a second slide rod 12 symmetrically fixedly connected to one end of the brazing frame 5, and one end of the brazing frame 5 is fixedly connected to an electric push rod 13, one end of the two second slide rods 12 is slidably connected to a U-shaped pressing platform 14, the output end of the electric push rod 13 is fixedly connected to the U-shaped pressing platform 14, and the top of the positioning rod 4 passes through the U-shaped pressing platform 14 and is rotatably connected to the U-shaped pressing platform 14;

[0078] The coaxial positioning assembly further includes a piston chamber 15 provided inside the positioning rod 4, a piston rod 16 being slidably connected to the interior of the piston chamber 15, four expansion slots 17 being evenly provided on the inner side of the piston chamber 15, a silicone block 18 being fixedly connected to the interior of the expansion slots 17, and the silicone block 18 being used to contact the inner wall of the bellows 1 and the joint 2 under the push of the piston rod 16 to enhance positioning stability;

[0079] Moreover, the coaxial positioning assembly further includes a lever through slot 19 symmetrically provided at one end of the U-shaped pressing platform 14, a rectangular handle 20 with a groove is provided inside the lever through slot 19, the middle section of the rectangular handle 20 with a groove is rotatably connected to the inner wall of the lever through slot 19, and a follower slot 21 is symmetrically provided at one end of the rectangular handle 20 with a groove, the top of the piston rod 16 passes through the U-shaped pressing platform 14 and is rotatably connected to the positioning rod 4, and a transmission pressure rod 22 is fixedly connected to the top of the plurality of piston rods 16, and a pair of follower sliders 23 are symmetrically fixedly connected to one end of the transmission pressure rod 22, and the follower slider 23 is slidably connected to the inside of the follower slot 21, and the transmission pressure rod 22 can be driven by the rotation of the rectangular handle 20 to drive the piston rod 16 to slide along the piston chamber 15;

[0080] Moreover, a lifting groove 29 is symmetrically provided at one end of the assembly table 3, and a third slide bar 30 is symmetrically fixedly connected to the interior of the lifting groove 29, and one end of two adjacent third slide bars 30 is slidably connected to an inclined lifting rod 31, and a return spring 32 is provided on the outer periphery of the third slide bar 30, and the return spring 32 is fixedly connected to the bottom of the inclined lifting rod 31, and a lifting groove 33 adapted to the inclined lifting rod 31 is symmetrically provided on the top of the brazing frame 5, and a pair of rollers 34 are symmetrically connected to the bottom of the upper pressing plate 6. , the roller 34 rolls against the inclined surface of the inclined lifting rod 31. When the brazing rack 5 approaches the assembly table 3, the lifting rod 31 rolls against the inclined surface of the roller 34 and pushes the lifting rod 31 down along the third slide bar 30 to compress the return spring 32, so that the lifting rod 31 is inserted into the lifting groove 33, and the return spring 32 rebounds and lifts the upper pressing plate 6, so that the upper pressing plate 6 is separated from the brazing rack 5, making it convenient to insert the bellows 1 and the joint 2 into the lower groove 7 and the upper groove 8 respectively;

[0081] like Figure 2 and Figure 3 、 Figure 5-Figure 7 、 Figure 9 、 Figure 10 As shown, the feeding assembly includes a synchronous wheel 24 fixedly connected to the top of the positioning rod 4, and a synchronous belt 25 is sleeved on the outer periphery of the multiple synchronous wheels 24. One end of the U-shaped pressing platform 14 is rotatably connected to a driving wheel 26. The middle section of the synchronous belt 25 passes around the outer periphery of the driving wheel 26. One end of the U-shaped pressing platform 14 is rotatably connected to a pair of limiting wheels 27. The two limiting wheels 27 are arranged on the left and right sides of the driving wheel 26, and the limiting wheels 27 roll against the outer side of the synchronous belt 25. The bottom of the U-shaped pressing platform 14 is fixedly connected to a motor 28. The output end of the motor 28 is fixedly connected to the driving wheel 26. The driving wheel 26 is driven by the motor 28 to drive the synchronous belt 25 and the synchronous wheel 24 to rotate, thereby causing the positioning rod 4 to drive the bellows 1 and the joint 2 to rotate synchronously to cooperate with the solder paste coating;

[0082] Among them, the loading component also includes a storage box 36 symmetrically fixedly connected to the inside of the assembly table 3, the output end of the storage box 36 is fixedly connected to the loading pump 37 through a pipeline, the output end of the loading pump 37 is fixedly connected to a multi-port distribution pipe 38 through a pipeline, the output end of the multi-port distribution pipe 38 is fixedly connected to a distribution pipe 39, the output end of the distribution pipe 39 is fixedly connected to a paint nozzle 40, the paint nozzle 40 is fixedly connected to one side of the assembly table 3, and the output end of the paint nozzle 40 is aligned with the outer periphery of the contact end of the bellows 1 and the joint 2. The two storage boxes 36 are respectively used to store Ti powder paste and BNi-2 solder paste, and are output in turn to the outer periphery of the contact end of the bellows 1 and the joint 2 through the corresponding two paint nozzles 40, and the uniform coating of the solder paste is achieved by cooperating with the rotation of the positioning rod 4.

[0083] When in use, first, push the brazing frame 5 to one side of the upper pressing plate 6, and insert the inclined lifting rod 31 into the lifting groove 33 of the brazing frame 5, and at the same time, the inclined lifting rod 31 contacts the roller 34, and at the same time, under the action of the gravity of the upper pressing plate 6, the return spring 32 is squeezed, and then the return spring 32 is used to lift the upper pressing plate 6, so that the brazing frame 5 and the upper pressing plate 6 maintain a gap, which is convenient for the operator to load and unload the workpiece;

[0084] Then, the corrugated tube 1 dried in step S2 is placed into the lower groove 7 on the top of the brazing frame 5, and the joint 2 is placed into the upper groove 8 of the upper pressing plate 6 to ensure that the annular joints of the two are aligned. Then, the electric push rod 13 at one end of the brazing frame 5 is started, and its output end pushes the U-shaped pressing table 14 to slide along the second slide rod 12 toward the workpiece, so that the bottom of the positioning rod 4 passes through the inside of the joint 2 and the corrugated tube 1 in turn, and the axial alignment of the two is preliminarily achieved.

[0085] Next, the operator rotates the grooved rectangular handle 20 on the U-shaped pressing table 14, and the middle section rotates around the inner wall of the lever slot 19. Through the cooperation of the follower slot 21 and the follower slider 23, the transmission pressure rod 22 is driven to move downward, thereby pushing the piston rod 16 down along the piston chamber 15 inside the positioning rod 4. At this time, the silicone block 18 in the inner slot 17 of the piston chamber 15 expands outward under the pressure of the piston rod 16, tightly contacting the inner wall of the bellows 1 and the joint 2, firmly fixing the two and ensuring the coaxiality after assembly, providing a foundation for the subsequent solder paste coating and brazing quality.

[0086] At the same time, the motor 28 at the bottom of the U-shaped pressing table 14 is started, and its output end drives the driving wheel 26 to rotate. The driving wheel 26 drives the synchronous wheel 24 at the top of the positioning rod 4 to rotate through the synchronous belt 25. The limiting wheel 27 tensions and guides the synchronous belt 25 to prevent slipping. The positioning rod 4 rotates accordingly, and then drives the corrugated pipe 1 and the joint 2 fixed thereto to rotate synchronously. The speed can be adjusted by the motor 28 to ensure uniform coating.

[0087] Next, in the first step, the Ti powder paste is stored in the storage box 36 of the assembly table 3 and is delivered to the coating nozzle 40 through the multi-port feeding pipe 38 and the distribution pipe 39 by the feeding pump 37. The output end of the nozzle is aligned with the outer periphery of the annular contact end of the bellows 1 and the joint 2. The Ti powder paste is evenly coated during the rotation of the workpiece.

[0088] After the Ti powder paste coating is completed, the second step is: another storage box 36 storing BNi-2 solder paste is coated with BNi-2 solder paste on the outer periphery of the annular contact end through another set of feeding pumps 37, distribution pipes 38, distribution pipes 39, and coating nozzles 40 systems in the above manner;

[0089] After the coating is completed, the third step is to turn off the motor 28 and the feeding pump 37, the positioning rod 4 stops rotating, and the solder paste coating process is completed;

[0090] Finally, the grooved rectangular handle 20 is rotated in the opposite direction, and the transmission pressure rod 22 drives the piston rod 16 to move upward. The silicone block 18 loses its squeeze and shrinks, separating from the inner wall of the workpiece. The electric push rod 13 drives the U-shaped pressing table 14 to reset, and the positioning rod 4 is pulled out from the inside of the bellows 1 and the joint 2.

[0091] At this time, the operator fastens the buckle tongue 10 and the buckle seat 11 to make the contact ends of the corrugated pipe 1 and the joint 2 fit tightly together to form the overall structure of the pipeline to be welded. Then the brazing frame 5 is pushed away from the upper pressure plate 6, and the lifting rod 31 is disengaged from the inside of the lifting groove 33. At the same time, the reset spring 32 lifts the lifting rod 31 to reset it. Then the assembled brazing frame 5 and the upper pressure plate 6 are sent into the vacuum brazing furnace for vacuum brazing in step S4.

[0092] The working principle of the vacuum brazing forming process and device for AI server liquid cooling pipes provided by the present invention is as follows:

[0093] First, the 316 stainless steel bellows 1 and joint 2 were pretreated, namely process steps S1 and S2: ultrasonic cleaning (50°C degreasing bath, 20 minutes) → room temperature water bath, 10 minutes → 70°C water bath, 10 minutes, with a frequency of 2.0-5.0 Hz, to remove oil and impurities. The surfaces were then dried with a 0.4 MPa air gun and dried in a drying oven at 100°C / 1 hour to provide a clean surface for subsequent welding.

[0094] Then, the core process step S3 is entered, which is assembly and solder paste coating. This process is completed in collaboration with the molding device:

[0095] Workpiece positioning preparation: Place the dried bellows 1 into the lower groove 7 on the top of the brazing rack 5, and the joint 2 into the upper groove 8 of the upper pressing plate 6. Through the cooperation of the inclined lifting rod 31 and the return spring 32, the upper pressing plate 6 and the brazing rack 5 maintain a gap to facilitate the placement of the workpiece;

[0096] Coaxial positioning: Start the electric push rod 13, push the U-shaped pressing table 14 to move along the second slide rod 12, so that the positioning rod 4 is inserted into the bellows 1 and the joint 2, turn the grooved rectangular handle 20, and drive the piston rod 16 downward through the transmission pressure rod 22, squeezing the silicone block 18 in the piston chamber 15 to expand and tightly contact the inner wall of the workpiece, ensuring the coaxiality of the two and laying the foundation for uniform welding;

[0097] Solder paste coating: Start the motor 28, and drive the synchronous wheel 24 on the top of the positioning rod 4 to rotate through the driving wheel 26 and the synchronous belt 25, driving the workpiece to rotate synchronously. The Ti powder paste in the storage box 36 is first coated on the annular contact end by the coating nozzle 40 through the feeding pump 37, the multi-port feeding pipe 38, and the distribution pipe 39. Then, the BNi-2 solder paste in another storage box is coated for the second time through an independent system. The rotation of the workpiece is used to achieve uniform coverage of the solder paste. The mass percentage of Ti powder in the Ti powder paste is preferably 0.5%, and the average particle size is 100nm;

[0098] After coating is completed, the device is reset: the grooved rectangular handle 20 is rotated in the opposite direction to shrink the silicone block 18, the electric push rod 13 drives the U-shaped pressing table 14 to reset, the positioning rod 4 is pulled out, and the upper pressing plate 6 and the brazing frame 5 are fastened together by the buckle tongue 10 and the buckle seat 11, so that the contact ends of the corrugated pipe 1 and the joint 2 are tightly fitted to form the assembly to be welded;

[0099] Finally, the process enters step S4 vacuum brazing: the assembled components are sent into the vacuum brazing furnace along with the brazing frame 5 and the upper pressing plate 6, and the welding is completed according to the preset temperature curve:

[0100] T1, room temperature → 550℃, 60min heating + 50min insulation: remove organic matter in solder paste;

[0101] T2, 550℃→950℃, 60min heating + 30min holding: pre-diffusion of key elements to avoid uneven furnace temperature;

[0102] T3, 950℃→1050℃, 20min heating + 50min holding: With the help of the coaxiality guaranteed by the device, the BNi-2 solder, whose composition is Cr6.0%-8.0%, Si4.0%-5.0%, etc., is fully metallurgically bonded with the base material. At the same time, the Ti powder reacts with the B in the solder to form nano-TiB2 to strengthen the weld and suppress brittle boride;

[0103] T4, 1050℃→900℃, 10min cooling + 4min holding: relieve thermal stress and prevent workpiece deformation;

[0104] T5, 900℃→room temperature, 150min cooling: avoid excessive diffusion of elements to form harmful phases;

[0105] Ultimately, through the coordination of processes and equipment, a defect-free, high-strength AI server liquid cooling pipeline was obtained, meeting the high cleanliness and mechanical performance requirements of vacuum brazing.

[0106] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A vacuum brazing process for liquid cooling pipes of AI servers, characterized by: The liquid cooling pipeline is composed of a bellows (1) and a joint (2), and the material is 316 stainless steel. The solder used for vacuum brazing is BNi-2, and the raw material composition of the BNi-2 solder includes: Cr6.0%-8.0%, Si4.0%-5.0%, B2.75%-3.50%, Fe2.5%-3.5%, C<0.06%, P<0.02%, and the remainder is Ni; The process includes the following steps: S1. Ultrasonic cleaning of the bellows and joints: first, soaking in a degreasing tank at 50°C for 20 minutes, second, soaking in a normal temperature water tank for 10 minutes, and finally, soaking in a water tank at 70°C for 10 minutes. The ultrasonic cleaning frequency is 2.0-5.0 Hz. S2. Blow dry the cleaned bellows and joints with an air gun, and then put them into a drying oven for drying; S3. Assemble the bellows and the joint, first evenly apply a paste containing nano-Ti powder on the annular joint, then apply BNi-2 solder paste, obtain the pipe to be welded and place it in a brazing fixture; the Ti powder paste is prepared by ultrasonically stirring Ti nanoparticles, polyvinyl alcohol, polyamide wax and stearic acid in a certain proportion; S4. Place the brazing fixture loaded with the pipe to be welded into the vacuum brazing furnace for brazing. The process is as follows: T1, heating from room temperature to 550℃ for 60min, keeping warm for 50min; T2, heating to 950°C for 60 minutes, keeping warm for 30 minutes; T3, heat at 950℃ for 20min to 1050℃, keep warm for 40-60min; T4, cool from 1050℃ for 10min to 900℃, keep warm for 4min; T5. Cool from 900℃ for 150min to room temperature and then take out.

2. The vacuum brazing forming process for liquid cooling pipes of AI servers according to claim 1 is characterized in that: In step S3, the mass percentage of Ti powder in the Ti powder paste is 0.5%.

3. The vacuum brazing forming process for liquid cooling pipes of AI servers according to claim 1 is characterized in that: In step S4, the holding time of T3 is 50 minutes.

4. A vacuum brazing forming device for liquid cooling pipes of an AI server, used in the vacuum brazing forming process for liquid cooling pipes of an AI server as claimed in any one of claims 1 to 3, characterized in that: The invention comprises an assembly table (3), a plurality of positioning rods (4) are provided on one side of the assembly table (3), and a brazing frame (5) is provided on one side of the assembly table (3), an upper pressing plate (6) is provided on the top of the brazing frame (5), a plurality of lower grooves (7) are provided on the top of the brazing frame (5), a plurality of upper grooves (8) are provided on the top of the upper pressing plate (6), a first sliding rod (9) is symmetrically fixedly connected to the bottom of the upper pressing plate (6), one end of the first sliding rod (9) passes through the brazing frame (5) and is slidably connected to the brazing frame (5), a buckle tongue (10) is symmetrically provided on one end of the brazing frame (5), a buckle seat (11) adapted to the buckle tongue (10) is symmetrically fixedly connected to one end of the upper pressing plate (6), the joint (2) is inserted into the interior of the upper groove (8), and the top of the assembly table (3) is inserted into the interior of the lower groove (7) at the bottom of the brazing frame (5); One end of the assembly table (3) is provided with a coaxial positioning component for driving a positioning rod (4) to be inserted into the inside of the joint (2) and the bellows (1) to ensure the coaxiality of the two, and the top of the brazing frame (5) is provided with a feeding component for accurately coating the outer periphery of the contact end of the driving joint (2) and the bellows (1) with solder paste.

5. According to the AI ​​server liquid cooling pipeline vacuum brazing forming device according to claim 4, the coaxial positioning assembly includes a second slide rod (12) symmetrically fixedly connected to one end of the brazing frame (5), and one end of the brazing frame (5) is fixedly connected to an electric push rod (13), and one end of the two second slide rods (12) is slidably connected to a U-shaped pressing table (14), the output end of the electric push rod (13) is fixedly connected to the U-shaped pressing table (14), and the top of the positioning rod (4) passes through the U-shaped pressing table (14) and is rotatably connected to the U-shaped pressing table (14).

6. The vacuum brazing forming device for liquid cooling pipes of an AI server according to claim 5, characterized in that: The coaxial positioning assembly also includes a piston chamber (15) opened inside the positioning rod (4), the interior of the piston chamber (15) is slidably connected to a piston rod (16), four expansion grooves (17) are evenly opened on the inner side of the piston chamber (15), and a silicone block (18) is fixedly connected inside the expansion groove (17).

7. The vacuum brazing forming device for liquid cooling pipes of an AI server according to claim 6, characterized in that: The coaxial positioning assembly also includes a lever groove (19) symmetrically opened at one end of the U-shaped pressing platform (14), a rectangular handle (20) with a groove is provided inside the lever groove (19), the middle section of the rectangular handle (20) is rotatably connected to the inner wall of the lever groove (19), and a follower groove (21) is symmetrically opened at one end of the rectangular handle (20), the top of the piston rod (16) passes through the U-shaped pressing platform (14) and is rotatably connected to the positioning rod (4), and the tops of multiple piston rods (16) are fixedly connected to a transmission pressure rod (22), and one end of the transmission pressure rod (22) is symmetrically fixedly connected to a pair of follower sliders (23), and the follower slider (23) is slidably connected to the inside of the follower groove (21).

8. The vacuum brazing forming device for liquid cooling pipes of an AI server according to claim 7, characterized in that: The feeding assembly includes a synchronous wheel (24) fixedly connected to the top of the positioning rod (4), a plurality of synchronous wheels (24) are sleeved with a synchronous belt (25) on their outer peripheries, one end of the U-shaped pressing platform (14) is rotatably connected to a driving wheel (26), the middle section of the synchronous belt (25) passes around the outer periphery of the driving wheel (26), one end of the U-shaped pressing platform (14) is rotatably connected to a pair of limiting wheels (27), the two limiting wheels (27) are arranged on the left and right sides of the driving wheel (26), and the limiting wheels (27) roll against the outer side of the synchronous belt (25), the bottom of the U-shaped pressing platform (14) is fixedly connected to a motor (28), and the output end of the motor (28) is fixedly connected to the driving wheel (26).

9. The vacuum brazing forming device for liquid cooling pipes of an AI server according to claim 4, characterized in that: One end of the assembly table (3) is symmetrically provided with a lifting groove (29), the interior of the lifting groove (29) is symmetrically fixedly connected with a third slide bar (30), one end of two adjacent third slide bars (30) is slidably connected with an inclined lifting rod (31), the outer periphery of the third slide bar (30) is provided with a return spring (32), the return spring (32) is fixedly connected to the bottom of the inclined lifting rod (31), the top of the brazing frame (5) is symmetrically provided with a 31) is adapted to the lifting groove (33), and the bottom of the upper pressure plate (6) is symmetrically connected to a pair of rollers (34), and the rollers (34) roll against the inclined surface of the inclined lifting rod (31). Under the resistance of the rollers (34), the inclined lifting rod (31) can slide down along the third slide bar (30) and compress the reset spring (32), and when the reset spring (32) rebounds, it is inserted into the lifting groove (33) to drive the upper pressure plate (6) to separate from the brazing frame (5).

10. The vacuum brazing forming device for liquid cooling pipes of an AI server according to claim 8, characterized in that: The feeding assembly also includes a storage box (36) symmetrically fixedly connected to the inside of the assembly table (3), the output end of the storage box (36) is fixedly connected to a feeding pump (37) through a pipeline, the output end of the feeding pump (37) is fixedly connected to a multi-port distribution pipe (38) through a pipeline, the output end of the multi-port distribution pipe (38) is fixedly connected to a distribution pipe (39), the output end of the distribution pipe (39) is fixedly connected to a paint nozzle (40), the paint nozzle (40) is fixedly connected to one side of the assembly table (3), and the output end of the paint nozzle (40) is aligned with the outer periphery of the contact end of the bellows (1) and the joint (2), the inside of the two storage boxes (36) is used to store Ti powder paste and BNi-2 solder paste respectively, and outputs them in sequence to the outer periphery of the contact end of the bellows (1) and the joint (2) through the corresponding two paint nozzles (40).

Images