A reverse deformation control device and method for Al / SiC and dissimilar metal brazing

Abstract

The application discloses a kind of anti-deformation control method and device for Al / SiC and dissimilar metal brazing, belongs to dissimilar material brazing process technical field;The device includes profiling assembly and locking mechanism, profiling assembly contains the anti-deformation plate and backing plate of preset anti-deformation surface, locking mechanism contains bottom plate, support table, transfer pressure plate, profiling pressure plate and bolt locking structure, and is collectively constituted bridge-shaped pressure applying structure to concentrate locking force and act on the four corners of workpiece;Method is first determined by welding simulation workpiece deformation and temperature difference distribution, set profiling surface parameter and temperature balance scheme, assemble tooling pre-applied reverse deformation and then carry out brazing, so that welding thermal stress and pre-applied reverse deformation stress are mutually offset;The application can reduce the deformation of the four corners of Al / SiC dissimilar metal brazing workpiece by 80%, without subsequent straightening process after welding, significantly improve processing efficiency and product flatness accuracy.

Description

Technical Field

[0001] This invention belongs to the field of brazing technology and tooling technology for dissimilar materials, specifically relating to an anti-deformation control device and method for brazing aluminum silicon carbide (Al / SiC) and dissimilar metals, which is suitable for high-precision brazing manufacturing of heat dissipation cold plates for electronic equipment. Background Technology

[0002] In recent years, with the development of electronic equipment towards higher integration and higher power, heat dissipation has gradually become a key factor restricting the improvement of equipment performance. Especially in high-frequency electronic devices, the heat dissipation of components is constantly increasing, and their size is constantly shrinking, leading to a rapid increase in heat flux density (from 5 W / cm² to ≥80 W / cm²), which places higher demands on the efficiency of heat dissipation systems. Currently, aluminum silicon carbide (Al / SiC) is the representative packaging material for electronic devices, with a thermal conductivity of up to 150 W / (m·K). However, its high cost and low ductility limit its widespread application in the field of cold-plate applications. Therefore, using lower-cost metal materials to weld with aluminum silicon carbide has become a trend in the development of cold-plate systems.

[0003] However, metals and non-metals differ significantly in their physical and chemical properties, such as different coefficients of thermal expansion, large differences in melting points, and complex interfacial reactions, resulting in complex and difficult-to-adjust microstructures of dissimilar material brazed joints. In Al / SiC and dissimilar metal brazing, temperature control is particularly critical. Temperature not only affects the melting and spreading of the brazing filler metal but also directly determines the internal thermal stress distribution, phase transformation behavior, and interfacial bonding characteristics. Excessively high temperatures may lead to softening or oxidation of TC4, while excessively low temperatures may prevent the brazing filler metal from adequately wetting the substrate, resulting in decreased weld quality or even weld failure. Furthermore, the difficulty in matching the physical properties and lattice structure of the metal / non-metal interface makes post-weld deformation of the cold plate particularly prominent, with significant localized stress concentration, severely impacting the assembly of the cold plate with subsequent components.

[0004] The traditional solution is to correct the flatness of the thin-walled plate after welding, usually by combining hydraulic leveling and flame leveling. However, this method involves many complex processes and requires the cooperation of special trades such as crane operators, cold working, and flame working, resulting in long production cycles and high costs, making it difficult to meet the needs of efficient production.

[0005] Aluminum silicon carbide (ASC) has good heat dissipation performance and a low coefficient of thermal expansion, and is often used in packaging housings and heat sinks. However, due to its high cost, lower-cost metals are often chosen for welding with ASC. But different materials have significant differences in physical and chemical properties, such as different coefficients of thermal expansion, large differences in melting points, and complex interface reactions. The brazing connection between the two faces many challenges, especially temperature control and welding deformation, which affect subsequent component assembly.

[0006] Therefore, it is necessary to provide an effective method for controlling the anti-deformation of cold plates to avoid welding deformation, especially suitable for anti-deformation of Al / SiC and dissimilar metal brazing. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and apparatus for reverse deformation control in Al / SiC and dissimilar metal brazing. This invention solves the technical problems of large deformation of Al / SiC dissimilar metal brazed workpieces after welding, cumbersome subsequent correction processes, and low production efficiency. By pre-applying reverse deformation to offset welding thermal stress, the flatness of the workpiece after welding is achieved, eliminating the need for subsequent leveling processes.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: an anti-deformation control device for brazing Al / SiC and dissimilar metals, comprising a conforming component and a locking mechanism;

[0009] The contouring assembly includes a pad and a deformation-simulating plate, which are stacked from bottom to top. The upper surface of the deformation-simulating plate is a preset inverse deformation surface, which is used to support the workpiece to be brazed and provide a bottom reverse forming reference.

[0010] The locking mechanism includes a base plate, a support platform, a pressure plate, a rotating pressure plate, a contouring pressure plate, and bolt locking components. A pad is fixedly installed on the upper surface of the base plate; the support platform is vertically fixed to one side of the base plate, serving as a support fulcrum for the pressure plate; one end of the pressure plate is supported on the top of the support platform, and the other end is connected to the bolt locking components, amplifying the locking force through a lever structure. The rotating pressure plate is located below the pressure plate and engages with it in a transmission mechanism; the contouring pressure plate is located below the rotating pressure plate and directly presses against the upper surface of the workpiece. The rotating pressure plate and the contouring pressure plate together form a bridge-shaped pressure application structure, concentrating the locking force onto the four corner edges of the workpiece, precisely applying anti-deformation preload.

[0011] In a preferred embodiment of the present invention, a weight-reducing groove is provided in the middle of the lower surface of the pad, which reduces the amount of tooling material used, lowers the overall heat capacity of the tooling, and reduces the interference of the tooling's heat absorption on the welding temperature field.

[0012] As a preferred embodiment of the present invention, the upper surface of the simulated deformation plate has a structure that is high in the middle and low at the four corners. The height difference of the surface is determined by welding simulation calculation and is matched in reverse with the warping deformation of the workpiece after welding.

[0013] As a preferred embodiment of the present invention, the upper surface of the contouring pressure plate is provided with at least two guide grooves, which are used for center positioning when the workpiece is placed, and for providing installation guidance for the pressure plate to ensure accurate pressure application.

[0014] As a preferred embodiment of the present invention, a temperature balancing device is installed in the guide groove. The device is made of a high thermal conductivity material and can quickly conduct heat from the edge of the workpiece to the inside of the workpiece, balance the overall temperature field of the workpiece, reduce thermal stress, and suppress wave deformation.

[0015] In a preferred embodiment of the present invention, the lower surface of the rotating pressure plate covers the four corner edge areas of the contour pressure plate; the transverse center line of the rotating pressure plate coincides with the transverse center line of the pressure plate, and the longitudinal center line intersects perpendicularly with the longitudinal center line of the pressure plate, so that the concentrated force of the pressure plate is evenly distributed to the four corners of the workpiece.

[0016] In a preferred embodiment of the present invention, a washer is provided between the rotating pressure plate and the conforming pressure plate. The rotating pressure plate, the washer, and the conforming pressure plate together form a bridge-shaped support structure, which avoids direct pressure on the middle of the pressure plate and concentrates the pressure in the areas with the greatest deformation at the four corners.

[0017] In a preferred embodiment of the present invention, the bolt locking component includes a bolt and a wire threaded sleeve; the wire threaded sleeve is embedded in the threaded hole of the base plate, and the bolt is screwed into the wire threaded sleeve after passing through the pressure plate, thereby achieving precise adjustment of the locking force by controlling the bolt tightening torque.

[0018] The present invention also provides a method for controlling the anti-deformation of Al / SiC brazing with dissimilar metals based on the above-mentioned device, comprising the following steps:

[0019] S1: Through welding simulation calculations, a thermal-structural coupling model of the workpiece and tooling is established to determine the post-weld deformation distribution of the workpiece to be brazed and the temperature difference distribution during the welding process.

[0020] S2: Set the surface height difference between the simulated deformation plate and the simulated pressure plate based on the deformation amount obtained from the simulation, and set the heat conduction parameters and installation position of the temperature balancing device based on the temperature difference distribution.

[0021] S3: Assemble the base plate, pad plate, imitation deformation plate, workpiece to be brazed, imitation pressure plate, rotating pressure plate and pressure plate in sequence from bottom to top. Apply the set pre-tightening force through the bolt locking parts to make the workpiece produce a pre-deformation that is opposite in direction and matches the size of the deformation after welding.

[0022] S4: Send the assembled tooling and workpiece into the brazing equipment, set the brazing temperature, holding time and other process parameters, and complete the brazing process.

[0023] S5: After welding, the workpiece is cooled to room temperature in the furnace, the locking mechanism is released, the workpiece is removed, and the reverse deformation control is completed.

[0024] As a preferred embodiment of the present invention, in step S1, the simulation calculation includes at least thermal stress field simulation and deformation field simulation, and outputs the warping deformation at the four corners of the workpiece, the radial temperature difference distribution of the workpiece, and the stress concentration location data.

[0025] In a preferred embodiment of the present invention, in step S3, the preload is quantitatively controlled by the bolt torque so that the pre-deformation at the four corners of the workpiece is comparable in magnitude and opposite in direction to the post-weld deformation obtained from the simulation.

[0026] In a preferred embodiment of the present invention, during the brazing process, the temperature balancing device continuously conducts heat to balance the temperature difference between the inside and outside of the workpiece and suppress local wave deformation of the workpiece; the thermal stress generated by welding cancels out the pre-applied anti-deformation stress, so that the lower surface of the workpiece after welding remains flat and the flatness meets the assembly requirements.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention simulates a pre-set reverse curved surface and applies precise reverse deformation to the workpiece before brazing, so that the welding thermal stress and the pre-applied stress cancel each other out. This can reduce the warping deformation of the four corners of the TC4-Al / SiC brazed workpiece from 1mm to 0.2mm, a reduction of 80%, and the flatness requirement is directly met after welding.

[0029] 2. This invention eliminates the need for subsequent hydraulic leveling, heat treatment, and other correction processes, reducing the number of collaborative work steps among multiple trades, shortening the manufacturing cycle, lowering processing costs, and avoiding damage to the joint quality during the straightening process.

[0030] 3. This invention uses a temperature balancing device to equalize the temperature difference between the inside and outside of the workpiece, thereby reducing temperature stress. This not only suppresses warping at the four corners but also effectively prevents wavy deformation of the workpiece and improves the overall flatness.

[0031] 4. This invention adopts a bridge-shaped pressure application structure with bolt locking, which ensures precise pressure transmission, convenient operation, and adaptability to workpieces of different sizes and specifications, making it highly versatile; the weight-reducing groove design reduces the heat capacity of the tooling and minimizes the impact on the welding process. Attached Figure Description

[0032] Figure 1 This is a flowchart of the anti-deformation control method of the present invention;

[0033] Figure 2 This is a schematic diagram of the overall structure of the anti-deformation control device of the present invention;

[0034] Figure 3 This is a cross-sectional view of the anti-deformation control device of the present invention;

[0035] Figure 4 This is a bottom view of the anti-deformation control device of the present invention;

[0036] Figure 5 This is a cross-sectional view of the contouring component of the present invention;

[0037] Figure 6 This is a cross-sectional view of the locking mechanism of the present invention;

[0038] Figure 7 This is a comparison diagram showing the deformation of brazing dissimilar materials before and after the present invention.

[0039] Explanation of reference numerals in the attached drawings: 1-Contouring component, 101-Contouring plate, 102-Padded plate; 2-Locking mechanism, 201-Base plate, 202-Support platform, 203-Spinning pressure plate, 204-Contouring pressure plate, 205-Pressure plate, 206-Bolt, 207-Wire thread insert; 41-Workpiece, 42-Washer, 43-Weight reduction groove, 44-Guide groove, 45-Temperature balancing device. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0041] like Figure 2 , Figure 3 As shown, the anti-deformation control device for brazing Al / SiC and dissimilar metals described in this embodiment mainly consists of two parts: a contouring component 1 and a locking mechanism 2. The overall layout is symmetrical to ensure uniform force on the workpiece.

[0042] The contouring component 1 is located at the bottom of the device and includes a pad 102 and a contouring plate 101, which are stacked sequentially from bottom to top. The pad 102 is made of high-temperature resistant metal material and is fixedly installed in the middle of the upper surface of the base plate 201, serving as a load-bearing and height compensation component. Figure 4 , Figure 5 As shown, a long strip-shaped weight-reducing groove 43 is provided in the middle of the lower surface of the pad 102. On the one hand, it reduces the overall weight of the tooling, and on the other hand, it reduces the heat capacity of the tooling, reduces the heat absorbed by the tooling during the brazing process, and avoids significant impact on the welding temperature field of the workpiece.

[0043] The simulated deformation plate 101 is fixed to the upper surface of the pad 102. Its upper surface is a precision-machined reverse deformation curved surface, with an overall arched structure that is high in the middle and low at the four corners. The height difference of the curved surface is determined by finite element welding simulation calculation, and it is opposite in direction and matches the size of the warping deformation of the workpiece 41 after welding. When the workpiece 41 is placed on the simulated deformation plate 101, its bottom is completely in contact with the curved surface, and it forms a reverse pre-deformation under the action of pre-tightening force.

[0044] The locking mechanism 2 is located on the upper and side parts of the device, and includes a base plate 201, a support platform 202, a pressure plate 205, a rotating pressure plate 203, a contour pressure plate 204, and bolt locking components. The base plate 201 serves as the installation reference for the entire device and is made of high-strength alloy steel plate to ensure structural rigidity at high temperatures. The support platform 202 is vertically fixed to the top of one side of the base plate 201, serving as a support fulcrum for the pressure plate 205.

[0045] The pressure plate 205 is a long, rigid strip, with one end overlapping the top of the support platform 202 and the other end having a through hole for the bolt 206 to pass through. The rotating pressure plate 203 is positioned below the pressure plate 205 at its center, perpendicularly intersecting the pressure plate 205: the transverse centerline of the rotating pressure plate 203 coincides with the transverse centerline of the pressure plate 205, and its longitudinal centerline is perpendicular to the longitudinal centerline of the pressure plate 205. The lower surface of the rotating pressure plate 203 covers the four corner edges of the contoured pressure plate 204, evenly distributing the concentrated pressure of the pressure plate 205 to the four corners.

[0046] A contouring pressure plate 204 is positioned between the rotating pressure plate 203 and the workpiece 41. Its lower surface matches the shape of the upper surface of the workpiece 41, and its upper surface mates with the rotating pressure plate 203. For example... Figure 6 As shown, a washer 42 is also provided between the pressure plate 203 and the contouring pressure plate 204. The pressure plate 203, the washer 42 and the contouring pressure plate 204 together form a bridge-shaped support structure. The pressure is concentrated at the four corner edges of the contouring pressure plate 204, corresponding to the corner area where the workpiece 41 is most deformed, to avoid additional deformation caused by applying pressure in the middle.

[0047] like Figure 5 As shown, the upper surface of the contouring pressure plate 204 has two parallel guide grooves 44, which can be used for center positioning when placing the workpiece 41 to ensure that the workpiece and the tooling are coaxial, and also provide installation guidance for the pressure plate 203 to ensure accurate pressure application. A temperature balancing device 45, made of high thermal conductivity graphite or copper, is embedded inside the guide grooves 44. This device can quickly conduct heat from the edge of the workpiece to the inside, reducing the temperature difference between the inside and outside of the workpiece, reducing thermal stress, and suppressing wavy deformation of the workpiece.

[0048] The bolt locking component includes a bolt 206 and a wire thread insert 207. The wire thread insert 207 is fitted into the corresponding threaded hole in the base plate 201 to improve the wear resistance and connection strength of the threads. The bolt 206 passes through the through hole of the pressure plate 205 from top to bottom and is screwed into the wire thread insert 207. By tightening the bolt 206, the pressure plate 205 can be rotated around the support platform 202, applying downward pressure. The locking force is transmitted to the workpiece 41 through the rotating pressure plate 203 and the conforming pressure plate 204, realizing anti-deformation pre-compression; the locking force can be precisely adjusted by controlling the bolt torque.

[0049] like Figure 1As shown, the specific steps of the anti-deformation control method for Al / SiC brazing with dissimilar metals based on the above-mentioned device are as follows:

[0050] Step S1: Welding Simulation and Parameter Acquisition

[0051] A 3D model of the workpiece to be brazed (such as a TC4 titanium alloy and Al / SiC composite cold plate) is created and imported into finite element simulation software to establish a thermo-structural coupling analysis model. The brazing temperature profile, material thermophysical parameters, and boundary conditions are set, and simulation calculations of the thermal stress field and deformation field are performed. Data such as the warping deformation at the four corners of the workpiece after welding, the overall deformation distribution, the radial temperature difference during the welding process, and the location of stress concentration are output.

[0052] Step S2: Tooling parameter setting

[0053] Based on the post-weld deformation obtained from simulation, the curved surface profiles of the simulated deformation plate 101 and the simulated pressure plate 204 are designed and processed. The height difference between the curved surfaces is determined so that the pre-deformation direction is opposite to the post-weld deformation direction, and the deformation amounts are matched. Based on the temperature difference distribution obtained from simulation, the material, size, and installation position of the temperature balancing device 45 are determined to optimize the temperature equalization effect.

[0054] Step S3: Tooling assembly and pre-deformation application

[0055] Assemble the base plate 201, pad 102, and imitation deformation plate 101 sequentially from bottom to top; position the Al / SiC workpiece to be brazed and the dissimilar metal workpiece on the imitation deformation plate 101, aligning their centers; place the imitation pressure plate 204, washer 42, rotating pressure plate 203, and pressure plate 205 sequentially; screw the bolt 206 through the pressure plate 205 into the wire thread sleeve 207, and tighten the bolt according to the set torque, so that the workpiece undergoes elastic pre-deformation under the pressure of the four corners, conforming to the curved surface of the imitation deformation plate 101.

[0056] Step S4: Brazing

[0057] The assembled tooling, along with the workpiece, is fed into a vacuum brazing furnace or other brazing equipment. The temperature is increased and maintained according to the preset brazing process curve to complete the brazing process. During brazing, the temperature balancing device 45 continuously balances the internal and external temperatures of the workpiece, reducing thermal stress. As the temperature rises, the thermal expansion and welding thermal stress generated by the workpiece gradually offset the pre-applied anti-deformation stress.

[0058] Step S5: Cooling and demolding

[0059] After brazing, the workpiece is cooled to room temperature in the furnace to fully release residual stress. Then, bolt 206 is loosened, each layer of pressure plate is removed in sequence, and the brazed workpiece is taken out, thus completing the entire anti-deformation control process.

[0060] Effect verification

[0061] like Figure 7 As shown, a comparative verification is performed using a brazed workpiece made of TC4 titanium alloy and Al / SiC material with 65% SiC content as an example:

[0062] Figure 7 In the middle, 'a' refers to the traditional non-reverse deformation brazing process. After welding, the maximum warping deformation of the four corner edges of the workpiece is about 1mm, and the flatness does not meet the standard, requiring three subsequent correction processes.

[0063] b) Using the anti-deformation control device and method of the present invention, the maximum warping deformation of the four corner edges of the workpiece after welding is about 0.2mm, the deformation is reduced by 80%, the flatness of the lower surface directly meets the assembly requirements, no subsequent leveling process is required, and the production cycle is shortened by more than 40%.

[0064] In summary, this invention effectively solves the problem of large deformation in Al / SiC dissimilar metal brazing by adopting the technical path of "simulation preset - pre-pressure reverse deformation - welding stress offset". The tooling structure is simple, the operation is convenient, the deformation control effect is stable, and it is suitable for mass production applications.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for anti-deformation control in Al / SiC and dissimilar metal brazing, characterized in that: Includes contouring components and locking mechanisms; The contouring component includes a pad and a deformation plate stacked from bottom to top. The upper surface of the deformation plate is a preset anti-deformation curved surface, which is used to support the workpiece to be brazed. The locking mechanism includes a base plate, a support platform, a pressure plate, a rotating pressure plate, a contouring pressure plate, and bolt locking components. The pad is fixed to the upper surface of the base plate, the support platform is vertically fixed to one side of the base plate, one end of the pressure plate is supported on the top of the support platform, and the other end is connected to the bolt locking components. The rotating pressure plate is located below the pressure plate and drives the pressure plate. The contouring pressure plate is located below the rotating pressure plate and is used to press the workpiece to be brazed from above. The rotating pressure plate and the contouring pressure plate together form a bridge-shaped pressure structure, concentrating the locking force on the four corner edge areas of the workpiece.

2. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: The lower surface of the pad has a weight-reducing groove in the middle, which is used to reduce the overall heat capacity of the tooling and reduce the influence of the tooling on the welding temperature field.

3. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: The upper surface of the simulated deformation plate has a high center and low corner edges. The height difference of the surface is determined by welding simulation calculation and is matched in reverse with the deformation of the workpiece after welding.

4. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: The upper surface of the contouring pressure plate is provided with at least two guide grooves for workpiece center positioning and guide for the installation of the pressure plate; a temperature balancing device is installed in the guide groove to quickly conduct heat from the edge of the workpiece to the interior of the workpiece and balance the overall temperature field of the workpiece.

5. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: The lower surface of the rotating pressure plate covers the four corner edge areas of the contoured pressure plate; the transverse centerline of the rotating pressure plate coincides with the transverse centerline of the pressure plate, and the longitudinal centerline of the rotating pressure plate intersects the longitudinal centerline of the pressure plate perpendicularly.

6. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: A washer is provided between the pressure plate and the conforming pressure plate. The three together form a bridge-shaped support structure, and the pressure applied by the bolt locking component is concentrated and transmitted to the four corner edges of the workpiece.

7. The anti-deformation control device for brazing Al / SiC and dissimilar metals according to claim 1, characterized in that: The bolt locking component includes a bolt and a wire thread sleeve; the wire thread sleeve is embedded in the base plate, and the bolt passes through the pressure plate and is screwed into the wire thread sleeve. The locking force is adjusted by tightening the bolt.

8. A method for controlling anti-deformation brazing of Al / SiC and dissimilar metals based on the device according to any one of claims 1 to 7, characterized in that: Includes the following steps: S1: Through welding simulation calculations, determine the post-weld deformation of the workpiece to be brazed and the temperature difference distribution during the welding process; S2: Set the surface height difference between the simulated deformation plate and the simulated pressure plate based on the deformation amount obtained from the simulation, and set the parameters of the temperature balancing device based on the temperature difference distribution. S3: Assemble the base plate, pad plate, imitation deformation plate, workpiece, imitation pressure plate, rotating pressure plate and pressure plate in sequence from bottom to top. Apply pre-tightening force through bolt locking parts to make the workpiece produce pre-deformation in the opposite direction to the deformation after welding. S4: Set the brazing process parameters and perform brazing on the workpiece; S5: After welding is completed and cooled to room temperature, release the locking mechanism, remove the workpiece, and complete the reverse deformation control.

9. The method for controlling anti-deformation during brazing of Al / SiC with dissimilar metals according to claim 8, characterized in that: In step S1, the simulation calculation includes at least thermal stress field simulation and deformation field simulation, and outputs the warping deformation at the four corners of the workpiece and the radial temperature difference distribution data of the workpiece.

10. The method for controlling anti-deformation during brazing of Al / SiC with dissimilar metals according to claim 8, characterized in that: In step S3, the preload is controlled by the bolt torque so that the pre-deformation at the four corners of the workpiece is comparable in magnitude but opposite in direction to the post-weld deformation obtained from the simulation.

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