Large-area thin-wall phase change cold plate friction welding tool and method of using same

Abstract

The application provides a large-area thin-wall phase change cold plate friction welding tool, which comprises a clamping frame assembly, a detachable first positioning frame and a detachable second positioning frame arranged on the two sides respectively, the clamping frame assembly, the first positioning frame and the second positioning frame are annular frame structures to be sleeved outside the phase change cold plate, and a bottom seat is further arranged, the bottom seat is connected with the first positioning frame or the second positioning frame, and a plurality of pressing plates for pressing the phase change cold plate are arranged along the outer edge of the bottom seat, so that the problem of repeated positioning and multiple disassembly and assembly of the tool during friction welding of the large-area phase change cold plate is solved.

Description

Technical Field

[0001] This invention relates to the field of friction welding of phase change cold plates, and in particular to a friction welding fixture for large-area thin-walled phase change cold plates and its application method. Background Technology

[0002] Phase change heat sinks have a greater advantage than traditional metal heat sinks in heat storage, increasing heat storage density by 4-6 times. This high heat storage density characteristic makes heat sinks play an important role in heat dissipation of high-power, short-duration missile-borne electronic devices, such as in the thermal management of some high-power density electronic devices.

[0003] In practical applications, a large amount of phase change material is filled in order to improve heat storage, so the cold plate is generally designed as a thin-walled structure. At present, the processing of small phase change cold plates is not a big problem, but the processing of large-walled phase change cold plates is very difficult. (1) Cold plates filled with solid phase change material are not suitable for vacuum brazing, so friction stir welding is chosen. However, the high temperature during friction stir welding will cause a large amount of phase change material to overflow, resulting in unqualified welds; (2) Thin-walled cold plates must ensure that the phase change material is in close contact with the metal shell. If there is contact thermal resistance, it will affect the heat storage performance of the cold plate; (3) Large-area phase change cold plates have poor flatness after processing, which does not meet the assembly requirements.

[0004] Currently, large-area thin-walled phase change cold plates mainly employ friction stir welding. However, due to welding deformation, to ensure final forming accuracy, the phase change cold plate needs to have a thickness allowance and requires multiple welding operations on both sides. Since the external structure of the phase change cold plate itself lacks convenient positioning features for connection, it involves multiple tooling disassembly, reassembly, and repositioning. Furthermore, since the phase change material inside the cold plate can be either solid-solid or solid-liquid, the welding processes for the two are slightly different, and the requirements for auxiliary tooling also differ. Therefore, if multiple auxiliary tooling is still used, the repeated tooling disassembly, reassembly, repositioning, and posture changes not only result in high labor intensity and low welding efficiency but also easily lead to reduced accuracy. Summary of the Invention

[0005] This invention provides a friction welding fixture for large-area thin-walled phase change cold plates and its application method, which solves the problem of needing to disassemble and assemble the fixture multiple times and repeatedly position it during friction welding of large-area phase change cold plates.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a friction welding fixture for large-area thin-walled phase change cold plates, including a clamping frame assembly, and detachable first positioning frames and second positioning frames respectively on both sides. The clamping frame assembly, the first positioning frames and the second positioning frames are annular frame structures to be fitted on the outside of the phase change cold plate. A bottom seat is also provided, which is connected to the first positioning frame or the second positioning frame. The bottom seat has multiple pressure plates along its outer edge for pressing the phase change cold plate.

[0007] In a preferred embodiment, a first sinking trough is provided on the upper side of the bottom seat, and a support plate is provided inside the first sinking trough. The upper end of the support plate abuts against the phase change cold plate. A second sinking trough is provided on the lower side of the bottom seat, and a folded liquid guiding channel is provided inside the second sinking trough. Liquid guiding ports are provided at both ends of the liquid guiding channel on the side wall of the second sinking trough. A lower cover is also provided to seal the second sinking trough. A heat-conducting liquid is provided in the first sinking trough, and the heat-conducting liquid is in contact with the phase change cold plate.

[0008] In a preferred embodiment, a porous filling layer is provided between the sidewall of the first sinking trough and the support plate, and the porous filling layer is in contact with the phase change cold plate.

[0009] In a preferred embodiment, the bottom surface of the first settling tank is provided with multiple horizontally and vertically intersecting liquid guiding channels.

[0010] In a preferred embodiment, the clamping frame assembly is provided with a positioning protrusion and a connecting screw hole, the first positioning frame and the second positioning frame are provided with positioning holes and screw through holes, the positioning protrusion is aligned with the positioning hole, and the bolt passes through the screw through hole to be threadedly connected with the connecting screw hole.

[0011] In a preferred embodiment, the first positioning frame and the second positioning frame are provided with clearance grooves at both ends to avoid the gas-liquid passage of the phase change cold plate.

[0012] In the preferred embodiment, a stand is also provided, the stand is provided with a positioning protrusion, the positioning protrusion is engaged with the clearance groove, the first positioning frame and the second positioning frame are also provided with locking screw holes, the stand is provided with a side ear, the side ear is provided with a locking screw, and the locking screw is threadedly connected to the locking screw hole.

[0013] In a preferred embodiment, the clamping frame assembly includes four right-angled blocks, with positioning protrusions and connecting screw holes on the right-angled blocks. The two ends of the right-angled blocks are provided with adjusting screw holes with opposite thread directions. Adjacent right-angled blocks are provided with threaded double-ended screws to form a rectangular frame structure. The threads at both ends of the double-ended screws are opposite in direction. Friction plates are provided on the inner side of the right-angled blocks.

[0014] In the preferred embodiment, the outer edge of the bottom seat is provided with multiple screw holes, and the screw holes are provided with threaded adjustment sleeves. The adjustment sleeves are provided with locking screws, and the pressure plate is provided with a strip groove. One end of the locking screw passes through the strip groove to be threadedly connected to the adjustment sleeve.

[0015] In the preferred scheme, Rough machining of the box and lid, and preparation of phase change materials; Based on the specifications of the box, the clamping frame assembly, the first positioning frame, the second positioning frame, the bottom seat, and the upright seat are customized. Fit the clamping frame assembly onto the box body, install the first positioning frame and the second positioning frame on both sides of the clamping frame assembly, and then place the whole assembly on the bottom seat to lock the clamping frame assembly onto the box body; Attach the lid to the box body, install the pressure plates on the bottom seat and press the lid tightly; Remove the phase change cold plate from the bottom seat and transfer it to the friction welding equipment. Coolant is introduced into the bottom seat, and the front side of the phase change cold plate is subjected to stir friction welding. Flip the clamping frame assembly and the phase change cold plate over and put them back on the bottom seat. Stress is removed by stirring and rubbing the surface corresponding to the protruding edge on the reverse side of the phase change cold plate. Transfer the phase change cold plate to the milling machining center, remove the first positioning frame, and perform fine machining on the reverse side of the phase change cold plate; Reinstall the first positioning frame, flip the phase change cold plate back to the front, remove the second positioning frame, and perform precision machining on the front of the phase change cold plate. The phase change cold plate is transferred to the heating chamber for high-temperature exhaust. After taking it out, the phase change cold plate, namely the clamping frame assembly, the first positioning frame and the second positioning frame, are placed vertically on the stand. Liquid phase change material in liquid state is injected into the interior through the gas-liquid passage and then the gas-liquid passage is sealed. Surface treatment is performed on the phase change cold plate.

[0016] The beneficial effects of this invention are as follows: The spliced ​​tooling structure, consisting of a clamping frame and two double positioning frames on both sides, ensures that during welding and processing of the phase change cold plate on both sides, a positioning and clamping structure is always integrally connected to the cold plate, providing a repositioning reference for the removed positioning frame; it also provides a point of force and a positioning reference for the outside of the cold plate, facilitating rapid, accurate, and stable connection with other equipment; the bottom seat uses double-sided liquid heat conduction, resulting in a large contact area with the cold plate, eliminating air from the contact surface, achieving high heat conduction efficiency, removing heat accumulated during welding, reducing thermal deformation, and protecting the internal phase change material; the integrated positioning and clamping structure can be matched with a vertical stand to achieve vertical installation of the cold plate, meeting the requirements for phase change material filling. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of a large-area phase change cold plate.

[0019] Figure 2 This is a schematic diagram of the internal edge distribution of a phase change cold plate.

[0020] Figure 3 It is a diagram of the cold plate and tooling installation.

[0021] Figure 4 This is a structural diagram of the cold-rolled steel plate tooling.

[0022] Figure 5 This is an exploded view of the cold-rolled steel plate tooling.

[0023] Figure 6 This is a schematic diagram of the bottom seat.

[0024] Figure 7 This is a schematic diagram of the base of the base.

[0025] Figure 8 This is a schematic diagram of the first sinking channel.

[0026] Figure 9 It is a side sectional view of the tooling. Figure 1 .

[0027] Figure 10 It is a side sectional view of the tooling. Figure 2 .

[0028] Figure 11 This is a schematic diagram of the installation of the stand and the cold plate tooling.

[0029] Figure 12 This is a structural diagram of the clamping frame assembly.

[0030] Figure 13 This is a diagram of the standing structure.

[0031] In the figure: Clamping frame assembly 1; Positioning protrusion 101; Connecting screw hole 102; Right angle block 103; Adjusting screw hole 104; Double-ended screw 105; Friction plate 106; First positioning frame 2; Second positioning frame 3; Positioning hole 301; Screw through hole 302; Clearance groove 303; Locking screw hole 304; Bottom seat 4; First sinking groove 401; Support plate 402; Porous filling layer 403; Second sinking groove 404; Liquid guiding channel 405; Liquid guiding port 406; Liquid guiding groove 407; Lower cover 408; Screw hole ear 409; Pressure plate 5; Height adjustment sleeve 501; Locking screw 502; Strip groove 503; Stand 6; Positioning protrusion 601; Side ear 602; Locking screw 603; Phase change cold plate 7; Box body 701; Cover body 702; Protruding ridge 703; Gas-liquid through hole 704. Detailed Implementation

[0032] Example 1: like Figure 1-13 In the present invention, a friction welding fixture for a large-area thin-walled phase change cold plate includes a clamping frame assembly 1, and a detachable first positioning frame 2 and a second positioning frame 3 on both sides. The clamping frame assembly 1, the first positioning frame 2 and the second positioning frame 3 are annular frame structures to be fitted on the outside of the phase change cold plate 7. A bottom seat 4 is also provided, which is connected to the first positioning frame 2 or the second positioning frame 3. The bottom seat 4 has multiple pressure plates 5 along its outer edge for pressing the phase change cold plate 7.

[0033] Clamp the clamping frame assembly 1 in the middle region of the phase change cold plate 7 in the thickness direction, fasten the first positioning frame 2 and the second positioning frame 3 to the clamping frame assembly 1 from both sides, place the bottom seat 4 on the horizontal workbench, and place the integrated structure of the clamping frame assembly 1, the first positioning frame 2 and the second positioning frame 3 on the bottom seat 4.

[0034] The phase change cold plate 7 includes a housing 701, inside which is a settling groove. The settling groove has crisscrossing raised ridges 703 that divide the internal space into multiple small areas for filling solid-liquid or solid-solid phase change materials. The raised ridges 703 between adjacent small areas have connecting holes. Gas-liquid passages 704 are provided on the sides of the housing 701 to communicate with the internal small areas.

[0035] The cover 702 is fastened onto the recess of the box 701. The seam between the cover 702 and the box 701, as well as the contact point between the cover 702 and the raised ridge 703, are welded by friction welding. Due to the stress generated during welding, the phase change cold plate 7 bends slightly. Therefore, the phase change cold plate 7 is flipped over and placed back on the bottom seat 4. The corresponding position of the raised ridge 703 on the bottom side of the box 701 is then contacted and friction-welded using a friction welding head with the same process parameters as the front side to remove the internal stress of the phase change cold plate 7. Since the box 701 and the cover 702 are rough-machined and have a thickness allowance, this needs to be removed. However, the surface of the box 701 is already lower than the surface of the first positioning frame 2 at the final design thickness. At this point, the first positioning frame 2 must be removed, and then the bottom surface of the box 701 is finished to the design thickness using a milling cutter. Then, the first positioning frame 2 is reinstalled, the phase change cold plate 7 is flipped back to the front, and the second positioning frame 3 is removed. The cover 702 and the box 701 are then milled and precision machined to the designed thickness.

[0036] In a preferred embodiment, a first sinking groove 401 is provided on the upper side of the bottom seat 4, and a support plate 402 is provided in the first sinking groove 401. The upper end of the support plate 402 abuts against the phase change cold plate 7. A second sinking groove 404 is provided on the lower side of the bottom seat 4, and a folded liquid guiding channel 405 is provided in the second sinking groove 404. Liquid guiding ports 406 are provided at both ends of the liquid guiding channel 405 on the side wall of the second sinking groove 404. A lower cover 408 is also provided to close the second sinking groove 404. A heat-conducting liquid is provided in the first sinking groove 401, and the heat-conducting liquid is in contact with the phase change cold plate 7.

[0037] The support plate 402 can be an H-shaped or frame-shaped structure, supporting the bottom of the phase change cold plate 7. A liquid with high thermal conductivity is poured into the first sink 401, and the phase change cold plate 7 is placed in the first sink 401 so that the heat-conducting liquid contacts the bottom surface of the phase change cold plate 7.

[0038] For the cold plate of solid-solid phase change material, the material is cut into pieces in the solid phase and placed into the phase change cold plate 7.

[0039] When welding the phase change cold plate 7, heat is transferred to the heat transfer fluid in the first sink 401 and then circulated into the coolant channel 405. Since the boundary wall between the bottom surface of the second sink 404 and the bottom surface of the first sink 401 is thin and has high thermal conductivity, the coolant can carry away the liquid in the heat transfer fluid in the first sink 401 to maintain a relatively constant temperature of the phase change cold plate 7. At the same time, it prevents the phase change material from exceeding the design limit due to excessive temperature and vaporization, which would cause material loss, or reduces the structural stability and cause some material to enter the joint at the welding position.

[0040] In a preferred embodiment, a porous filling layer 403 is provided between the side wall of the first sinking trough 401 and the support plate 402, and the porous filling layer 403 is in contact with the phase change cold plate 7.

[0041] The porous filling layer 403 can be made of sponge material, which can absorb the heat-conducting liquid in the first settling tank 401 and prevent it from being shaken out of the first settling tank 401 due to vibration. Even if the heat-conducting liquid in the first settling tank 401 evaporates and the liquid level drops, the porous filling layer 403 can still guide the liquid to contact the bottom surface of the phase change cold plate 7 because the heat-conducting liquid wets the porous filling layer 403 through capillary action, thus still enabling efficient heat exchange.

[0042] In a preferred embodiment, the bottom surface of the first settling tank 401 is provided with multiple horizontally and vertically intersecting liquid guiding channels 407.

[0043] Processing a liquid guiding groove 407 on the bottom surface of the first sink 401 can increase the contact area between the bottom surface and the heat transfer liquid, improve the heat transfer efficiency, and also allow the heat transfer liquid to enter the inner side of the support plate 402 from below even if the support plate 402 is a closed shape, so that the heat of the heat transfer liquid is evenly distributed.

[0044] In a preferred embodiment, the clamping frame assembly 1 is provided with a positioning protrusion 101 and a connecting screw hole 102, the first positioning frame 2 and the second positioning frame 3 are provided with a positioning hole 301 and a screw through hole 302, the positioning protrusion 101 is connected to the positioning hole 301, and the bolt passes through the screw through hole 302 to be threadedly connected to the connecting screw hole 102.

[0045] In a preferred embodiment, the first positioning frame 2 and the second positioning frame 3 are provided with clearance grooves 303 at both ends to avoid the gas-liquid passage holes 704 of the phase change cold plate 7.

[0046] If the phase change cold plate 7 contains a solid-liquid phase change material, after the phase change cold plate 7 is welded and formed, it must be stood upright with the gas-liquid passage 704 facing upwards. The phase change material is heated into a liquid phase and then poured into one gas-liquid passage 704. When the other gas-liquid passage 704 overflows, it indicates that the plate is full, and it can be sealed with a plug. Therefore, the first positioning frame 2 and the second positioning frame 3 cannot block the gas-liquid passage 704, and a clearance groove 303 needs to be machined.

[0047] In the preferred embodiment, a stand 6 is also provided, the stand 6 is provided with a positioning protrusion 601, the positioning protrusion 601 is engaged in the relief groove 303, the first positioning frame 2 and the second positioning frame 3 are also provided with locking screw holes 304, the stand 6 is provided with a side ear 602, the side ear 602 is provided with a locking screw 603, and the locking screw 603 is threadedly connected to the locking screw hole 304.

[0048] Once the integrated structure of clamping frame assembly 1, first positioning frame 2, second positioning frame 3 and phase change cold plate 7 is erected, it can be temporarily fixed on the stand 6 to facilitate the filling of solid-liquid phase change material.

[0049] In a preferred embodiment, the clamping frame assembly 1 includes four right-angle blocks 103, with positioning protrusions 101 and connecting screw holes 102 provided on the right-angle blocks 103. The two ends of the right-angle blocks 103 are provided with adjusting screw holes 104 with opposite thread directions. Adjacent right-angle blocks 103 are provided with threaded double-ended screws 105 to form a rectangular frame structure. The two ends of the double-ended screws 105 have opposite thread directions. Friction plates 106 are provided on the inner side of the right-angle blocks 103.

[0050] The distance between adjacent right-angle blocks 103 can be adjusted by rotating the wrench in the middle of the double-ended screw 105. Since the phase change cold plate 7 has a rectangular structure, a rectangular frame structure can be installed on the outside of the phase change cold plate 7, and rotating each double-ended screw 105 will make the friction plate 106 fit tightly against the side wall of the phase change cold plate 7.

[0051] In a preferred embodiment, the outer edge of the bottom seat 4 is provided with a plurality of screw holes 409, and the screw holes 409 are provided with threaded height adjustment sleeves 501. The height adjustment sleeves 501 are provided with locking screws 502, and the pressure plate 5 is provided with a strip groove 503. One end of the locking screw 502 passes through the strip groove 503 to be threadedly connected to the height adjustment sleeves 501.

[0052] The extension length of the strip groove 503 is adjustable, and the end of the locking screw 502 presses against the phase change cold plate 7.

[0053] In the preferred scheme, Rough machining is performed on the box body 701 and the cover body 702, and phase change materials are prepared; Based on the specifications of box 701, the clamping frame assembly 1, the first positioning frame 2, the second positioning frame 3, the bottom seat 4, and the upright seat 6 are customized. The clamping frame assembly 1 is fitted onto the box body 701. The first positioning frame 2 and the second positioning frame 3 are installed on both sides of the clamping frame assembly 1 and then placed on the bottom seat 4. The clamping frame assembly 1 is then locked onto the box body 701. Fasten the cover 702 onto the box 701, install each pressure plate 5 on the bottom seat 4 and press the cover 702 tightly; Remove the phase change cold plate 7 from the bottom seat 4 and transfer it to the friction welding equipment. Coolant is introduced into the bottom seat 4, and the front side of the phase change cold plate 7 is subjected to stir friction welding. Flip the clamping frame assembly 1 and the phase change cold plate 7 and put them back on the bottom seat 4. Stress is removed by stirring and rubbing the surface corresponding to the protruding edge 703 on the reverse side of the phase change cold plate 7. Transfer the phase change cold plate 7 to the milling machining center, remove the first positioning frame 2, and perform fine machining on the reverse side of the phase change cold plate 7. Reinstall the first positioning frame 2, flip the phase change cold plate 7 back to the front, remove the second positioning frame 3, and perform precision machining on the front of the phase change cold plate 7. The phase change cold plate 7 is transferred to the heating box for high-temperature exhaust. After taking it out, the overall structure of the phase change cold plate 7, namely the clamping frame assembly 1, the first positioning frame 2 and the second positioning frame 3, is placed vertically on the stand 6. After filling the solid-liquid phase change material in liquid state into the interior through the gas-liquid through hole 704, the gas-liquid through hole 704 is sealed. The phase change cold plate 7 is subjected to surface treatment.

[0054] Example 2: A method and welding fixture for friction stir welding of large-area thin-walled phase change cold plates are disclosed. The phase change cold plate consists of a cavity, a cover plate, and a phase change material. The cavity and cover plate are welded into a sealed cavity using friction stir welding, and the cavity is filled with the phase change material. Due to the small total thickness and large area of ​​the cold plate in the application scenario, the cold plate is a thin-walled cold plate filled with composite solid-solid phase change material in order to improve heat storage and overall thermal conductivity. However, the phase change material overflows at high temperatures during welding, affecting the weld quality, and the small total thickness and large area make it difficult to meet the flatness requirements of the cold plate. Therefore, this patent adopts a novel process method: rough machining of the metal shell → phase change material processing → assembly → front welding → high-temperature venting → second rough machining → reverse welding → fine machining → surface treatment, combined with the welding fixture of this invention, which can solve the problems of poor weld quality and poor flatness of large-area thin-walled phase change cold plates.

[0055] The large-area thin-walled phase change cold plate consists of a cavity, a cover plate, and a phase change material. The cavity and cover plate are welded into a sealed cavity using friction stir welding. The cavity is filled with a composite solid-solid phase change material. To solve the above-mentioned technical problems, the process method and steps of the phase change cold plate in this invention are as follows: 1. Rough machining of metal casing: Based on the rough machining design drawings, use CNC equipment or other metal processing equipment to machine the metal workpiece.

[0056] The cavity and cover shell are made of aluminum alloy, copper, etc., with the thinnest part of the shell being between 0.8-1.5mm thick, which is a thin-walled structure. Due to the thin walls, auxiliary equipment such as chucks (e.g., electro-permanent magnet chucks / electromagnetic chucks) are needed during machining to ensure that the workpiece is efficiently and stably fixed on the machining equipment, ensuring machining accuracy and safety.

[0057] Corresponding matching slots are set inside the cavity / cover plate and on the surface of the phase change material. The slots are H-shaped, X-shaped, or Z-shaped, which allows the phase change material to be in close contact with the metal shell, reduces air thermal resistance, and enhances the overall thermal conductivity of the phase change cold plate.

[0058] 2. Phase change material processing: According to the design drawings, the material is processed by molding, extrusion, CNC machining, 3D printing and other forming methods.

[0059] The processed composite solid-solid phase change material is separated from the weld by a 1mm gap to prevent the phase change material from being stirred into the weld and affecting the welding quality.

[0060] The assembly tolerance with the cavity / cover plate is positive to ensure close contact between the phase change material and the metal parts, thereby reducing thermal resistance.

[0061] 3. Assembly: After cleaning the surfaces of the cavity, cover plate, and phase change material, assemble them to ensure that there are no other impurities at the weld overlap between the cavity and the cover plate that could interfere with the weld quality.

[0062] 4. Front welding: First, tap multiple points at the welding point to initially fix the cover plate and the cavity. Then, using the friction stir welding fixture designed in this invention, welding begins after confirming that the welding path and welding parameters are correct.

[0063] Welding parameters: The depth of cut is generally 0.1-0.2mm deeper than the cutter head, the cutter head speed is 2500-3000rpm, and the running speed is 80-120mmpm.

[0064] Welding path: First, weld the middle seam of the cover plate symmetrically, then weld the outer ring seam of the cover plate.

[0065] Inserting an air gun 20-30mm from the bottom of the welding tool allows for rapid purging of the high-temperature vaporized phase change material, preventing it from entering the weld and affecting welding quality.

[0066] 5. High-temperature exhaust: According to Charles's Law, under constant volume, the gas pressure in a closed space is directly proportional to the thermodynamic temperature. Therefore, heating will increase the internal pressure and molecular thermal motion of the cavity, prompting the gas inside the cavity to be expelled.

[0067] After holding at high temperature for 2-3 hours, the cavity is sealed under the high temperature of the cold plate, allowing for closer contact between the phase change material and the metal shell. The high temperature is determined by considering both the phase change temperature of the phase change material and the overall temperature; generally, it should be 30-50°C higher than the phase change temperature.

[0068] 6. Second roughing: Based on the second roughing design drawings, the metal workpiece is machined using CNC equipment or other metal processing equipment. Due to the thin wall surface, auxiliary equipment such as chucks (e.g., electro-permanent magnet chucks / electromagnetic chucks) is used during machining to ensure that the workpiece is efficiently and stably fixed on the processing equipment, ensuring machining accuracy and safety.

[0069] 7. Reverse Welding: During the first front-side welding, uneven heating and cooling in certain areas causes workpiece deformation. A second welding operation on the reverse side redistributes residual welding stress due to the newly generated welding heat input. Therefore, by properly controlling welding parameters and the reverse welding path, the newly generated deformation can be offset by the original deformation, ensuring the workpiece's flatness meets requirements when inspecting the bending condition of the cold-rolled workpiece.

[0070] Welding parameters: The depth of cut is generally 0.1-0.2mm deeper than the cutter head, the cutter head speed is 2500-3000rpm, and the running speed is 80-120mmpm.

[0071] Welding path: Segmented welding, symmetrical welding, and other methods can be selected to make the deformation of the welds on both sides cancel each other out.

[0072] 8. Precision Machining: Based on the precision machining design drawings, the metal workpiece is machined using CNC equipment or other metal processing equipment. Due to the thin wall surface, auxiliary equipment such as chucks (e.g., electro-permanent magnet chucks / electromagnetic chucks) is used during machining to ensure that the workpiece is efficiently and stably fixed on the machining equipment, ensuring machining accuracy and safety.

[0073] Surface treatment: According to design requirements, the metal parts are surface treated, commonly including natural conductive oxidation, anodizing, nickel plating, etc.

[0074] To achieve the above welding process and ensure that the welding quality of phase change cold plates meets the standards, this invention designs a tooling for friction stir welding of large-area thin-walled cold plates, including: inlet, outlet, sliding pressure block, fixed pressure block, vertical pressure plate, vertical pressure block, water flow channel, etc.

[0075] 1. The inlet is externally connected to a water pump, which can control the inlet flow rate, with a flow rate range of 0.8-1.5 m / s. The outlet is located diagonally above the inlet.

[0076] Because a large amount of heat is generated during friction stir welding, causing the phase change material to heat up and undergo a phase change, the tooling is equipped with staggered inlet and outlet ports to cool the cold plate in time during processing, reduce the loss of phase change material during welding, and prevent phase change material from entering the weld and affecting the welding quality.

[0077] 2. The sliding pressure block and the fixed pressure block are used to fix the horizontal direction of the workpiece, ensuring that the workpiece does not shift during the welding process and ensuring the correctness of the welding path.

[0078] 3. The vertical clamping plate is used to fix the vertical clamping block, ensuring the workpiece is under vertical force during welding. This clamping plate is easy to assemble and disassemble and can be used to fix the workpiece at any position on the fixture. Friction stir welding is a thermo-mechanical continuous process; uneven distribution of residual stress and uneven welding heat input directly lead to workpiece deformation. Therefore, a vertical clamping device is used to subject the workpiece to vertical force to resist the deformation forces produced during welding.

[0079] 4. The water flow channel also serves as the moving path of the sliding pressure block. The addition of the water flow channel increases the contact area between the flowing water and the cold plate, thereby enhancing the heat exchange capacity.

[0080] Compared with conventional tooling, the tooling for friction stir welding of the present invention has the following characteristics: 1. The tooling incorporates a flowing water design and is used in conjunction with an air gun to accelerate the cooling of the cold plate during the welding process. This solves the problem of liquefied / vaporized material entering the weld during friction stir welding of phase change cold plates, which can cause defects such as incomplete welds and missed welds, seriously affecting the weld quality.

[0081] 2. Horizontal and vertical fixing blocks work together to secure the workpiece, ensuring its stability during the welding process.

[0082] The vertical pressure plate is easy to assemble and disassemble, and can be used to fix the workpiece in any position on the tooling. It is convenient to adjust the position of the vertical pressure block in a timely manner according to the welding path during the welding process.

[0083] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A friction welding fixture for large-area thin-walled phase transformation cold plates, characterized in that: It includes a clamping frame assembly (1), and a detachable first positioning frame (2) and a second positioning frame (3) on both sides. The clamping frame assembly (1), the first positioning frame (2) and the second positioning frame (3) are ring-shaped structures to fit on the outside of the phase change cold plate (7). It also has a bottom seat (4), which is connected to the first positioning frame (2) or the second positioning frame (3). The bottom seat (4) has multiple pressure plates (5) along its outer edge for pressing the phase change cold plate (7).

2. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 1, characterized in that: The bottom seat (4) is provided with a first sinking groove (401) on the upper side, and a support plate (402) is provided in the first sinking groove (401). The upper end of the support plate (402) abuts against the phase change cold plate (7). The bottom seat (4) is provided with a second sinking groove (404) on the lower side, and a folded liquid guiding channel (405) is provided in the second sinking groove (404). The side wall of the second sinking groove (404) is provided with liquid guiding ports (406) at both ends of the liquid guiding channel (405). A lower cover (408) is also provided to close the second sinking groove (404). The first sinking groove (401) is provided with heat-conducting liquid, and the heat-conducting liquid is in contact with the phase change cold plate (7).

3. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 2, characterized in that: A porous filling layer (403) is provided between the side wall of the first sinking tank (401) and the support plate (402), and the porous filling layer (403) is in contact with the phase change cold plate (7).

4. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 2, characterized in that: The bottom surface of the first settling tank (401) is provided with multiple horizontal and vertical intersecting liquid guiding tanks (407).

5. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 1 or 2, characterized in that: The clamping frame assembly (1) is provided with a positioning protrusion (101) and a connecting screw hole (102). The first positioning frame (2) and the second positioning frame (3) are provided with a positioning hole (301) and a screw through hole (302). The positioning protrusion (101) is connected to the positioning hole (301), and the bolt passes through the screw through hole (302) to be threadedly connected to the connecting screw hole (102).

6. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 5, characterized in that: The first positioning frame (2) and the second positioning frame (3) are provided with clearance grooves (303) at both ends to avoid the gas-liquid passage (704) of the phase change cold plate (7).

7. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 6, characterized in that: It is also provided with a stand (6), the stand (6) is provided with a positioning protrusion (601), the positioning protrusion (601) is inserted into the relief groove (303), the first positioning frame (2) and the second positioning frame (3) are also provided with locking screw holes (304), the stand (6) is provided with a side ear (602), the side ear (602) is provided with a locking screw (603), and the locking screw (603) is threadedly connected to the locking screw hole (304).

8. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 5, characterized in that: The clamping frame assembly (1) includes four right-angle blocks (103), a positioning protrusion (101) and a connecting screw hole (102) are provided on the right-angle blocks (103), and the two ends of the right-angle blocks (103) are provided with adjusting screw holes (104) with opposite thread directions. Adjacent right-angle blocks (103) are provided with threaded double-ended screws (105) to form a rectangular frame structure. The two ends of the double-ended screws (105) have opposite thread directions. Friction plates (106) are provided on the inner side of the right-angle blocks (103).

9. The friction welding fixture for large-area thin-walled phase change cold plates according to claim 1, characterized in that: The bottom seat (4) has multiple screw holes (409) on its outer edge. The screw holes (409) are provided with threaded height adjustment sleeves (501). The height adjustment sleeves (501) are provided with locking screws (502). The pressure plate (5) is provided with a strip groove (503). One end of the locking screw (502) passes through the strip groove (503) to be threadedly connected to the height adjustment sleeves (501).

10. The method of using the friction welding fixture for large-area thin-walled phase transformation cold plates according to claim 7, characterized in that: The box body (701) and the cover body (702) are rough machined, and the phase change material is prepared; According to the specifications of the box body (701), the clamping frame assembly (1), the first positioning frame (2), the second positioning frame (3), the bottom seat (4) and the upright seat (6) are customized. The clamping frame assembly (1) is fitted onto the box body (701), and the first positioning frame (2) and the second positioning frame (3) are installed on both sides of the clamping frame assembly (1) and then placed on the bottom seat (4) to lock the clamping frame assembly (1) onto the box body (701). The cover (702) is fastened onto the box (701), and each pressure plate (5) is installed on the bottom seat (4) and the cover (702) is pressed tightly. Remove the phase change cold plate (7) from the bottom seat (4) and transfer it to the friction welding equipment. Coolant is introduced into the bottom seat (4) and the front side of the phase change cold plate (7) is subjected to stir friction welding. Flip the clamping frame assembly (1) and the phase change cold plate (7) and put them back on the bottom seat (4). Stress is removed by stirring and rubbing the corresponding surface position of the raised edge (703) on the reverse side of the phase change cold plate (7). The phase change cold plate (7) is transferred to the milling machining center, the first positioning frame (2) is removed, and the reverse side of the phase change cold plate (7) is precision machined. Reinstall the first positioning frame (2), flip the phase change cold plate (7) back to the front, remove the second positioning frame (3), and perform fine machining on the front of the phase change cold plate (7); The phase change cold plate (7) is transferred to the heating box for high-temperature exhaust. After taking it out, the overall structure of the phase change cold plate (7), namely the clamping frame assembly (1), the first positioning frame (2), and the second positioning frame (3), is placed vertically on the stand (6). Liquid phase change material in liquid state is injected into the interior through the gas-liquid through hole (704), and then the gas-liquid through hole (704) is sealed. The phase change cold plate (7) is subjected to surface treatment.

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