Active heat dissipation device and method for dissimilar metal tube sheet welding

Abstract

The application provides an active heat dissipation device and method for dissimilar metal tube plate welding, and relates to the technical field of heat exchanger manufacturing. The active heat dissipation device for dissimilar metal tube plate welding comprises a support body and a heat conduction gasket; the heat conduction gasket is connected to the support body, is made of a high-heat-conduction metal material, and has an arc-shaped contact surface that matches the inner wall curvature radius of a heat exchange tube to be welded; the arc-shaped contact surface is used for closely adhering to the inner wall of the heat exchange tube during welding to establish a heat conduction path from the heat exchange tube to the support body through the heat conduction gasket. The device closely adheres to the tube wall without gaps through the high-heat-conduction metal gasket with a specific curvature to establish an efficient physical heat conduction path, thereby overcoming the welding overheating defects in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchanger manufacturing, and in particular to an active heat dissipation device and method for dissimilar metal tube plate welding. BACKGROUND

[0002] In the manufacturing of cold water units, seawater desalination and chemical heat exchange equipment, in order to reduce costs and take into account the corrosion resistance, dissimilar metal connection is often used between carbon steel (such as Q345R) tube plate and stainless steel heat exchange tube. However, there is a significant difference in physical properties between stainless steel (thermal conductivity about 16 W / m·K) and carbon steel (thermal conductivity about 48 W / m·K) during batch welding.

[0003] In related technologies, when such tube plate welding is performed, due to the fact that the thermal conductivity of stainless steel is much lower than that of carbon steel, the heat generated by the welding arc is extremely easy to accumulate sharply on the side of the stainless steel heat exchange tube and cannot be timely conducted and dissipated to the surroundings. This heat accumulation effect can cause the local temperature of the weld to be too high, resulting in serious oxidation discoloration, grain coarsening and a decrease in corrosion resistance. Although the existing technology often uses the method of filling protective gas in the tube to prevent back oxidation, the gas itself has small heat capacity and poor thermal conductivity, and cannot effectively dissipate heat;

[0004] or a general copper rod is inserted into the tube to assist cooling, but such copper rods usually have a large fitting gap (air channel) between the tube wall, resulting in a huge contact thermal resistance, which cannot establish an efficient heat conduction path in the welding moment, and it is difficult to fundamentally solve the heat accumulation and overheating problem in dissimilar metal welding.

[0005] Therefore, it is necessary to improve the existing dissimilar metal tube plate welding technology to overcome the defects of the existing technology. SUMMARY

[0006] To overcome the problems in the related art, the purpose of the present application is to provide an active heat dissipation device for dissimilar metal tube plate welding, which realizes close fitting with the tube wall without gap by a high thermal conductivity metal gasket with a specific curvature, to establish an efficient physical heat conduction path, thereby overcoming the welding overheating defect in the prior art.

[0007] An active heat dissipation device for dissimilar metal tube plate welding, comprising:

[0008] a support body;

[0009] a heat conduction gasket connected to the support body, the heat conduction gasket is made of high thermal conductivity metal material and has an arc contact surface matching the curvature radius of the inner wall of the heat exchange tube to be welded;

[0010] The arc-shaped contact surface is used to tightly fit with the inner wall of the heat exchange pipe during welding, so as to establish a heat conduction path from the heat exchange pipe to the support body through the heat conduction pad.

[0011] Further, the heat capacity of the support body is greater than that of the heat conduction pad.

[0012] In the prior art, if the overall heat capacity of the heat dissipation device is uniform or the heat capacity of the rear end is insufficient, the contact end is easily saturated quickly, the temperature difference is reduced, and the heat conduction driving force is weakened. The present application clearly defines the support body as a "secondary heat dissipation heat sink", and its heat capacity is greater than that of the front end heat conduction pad. During welding, the heat conduction pad will quickly heat up due to its small size and close proximity to the heat source; at this time, the support body with large heat capacity can continuously and stably absorb heat from the pad like a "heat sink", preventing the heat conduction pad from being overheated and reducing the heat conduction efficiency. This heat capacity difference design maintains the temperature gradient between the heat source and the internal part of the heat dissipation device, ensuring the continuity and efficiency of heat flow.

[0013] Further, the material of the heat conduction pad is red copper, and the material of the support body is brass.

[0014] A single material device is either too soft to deform (all red copper) or has a slow heat conduction rate (all brass or steel). The present application uses red copper (pure copper) for the heat conduction end and brass for the support end. Red copper has a very high thermal conductivity coefficient (about 386 W / m·K), which can instantly absorb the heat of the welding area and maximize the reduction of contact thermal resistance; while brass has good mechanical strength and processing performance, and its cost is lower than that of red copper. This combination not only takes advantage of the "fast heat absorption" feature of red copper to establish a heat flow priority channel, but also takes advantage of the "high strength" feature of brass to bear the support and positioning functions, solving the problem of softness and easy deformation of red copper, and improving the durability and economy of the device.

[0015] Further, the surface roughness of the arc-shaped contact surface is less than or equal to 3.2 μm.

[0016] The roughness of a common machined surface is high (such as Ra 6.3 or above), and there are a large number of peaks and valleys on a microscopic scale, resulting in only point contact on the actual contact surface, and a micron-level air gap exists in most areas. The present application precisely processes the contact surface to a smoothness of Ra≤3.2 μm. The high smoothness surface greatly reduces the micro gaps at the contact interface, making the physical contact between the heat conduction pad and the inner wall of the heat exchange pipe more close and continuous. Since the thermal conductivity of air is extremely low, eliminating air gaps can significantly reduce the interface contact thermal resistance, ensuring efficient transfer of heat conduction, thereby greatly improving the heat dissipation efficiency.

[0017] Further, the arc-shaped contact surface of the heat conduction pad is provided with a high-temperature-resistant anti-adhesion coating, and the material of the high-temperature-resistant anti-adhesion coating includes boron nitride.

[0018] Red copper and stainless steel are prone to atomic diffusion at high temperature and high pressure, which causes the device to be difficult to pull out in the pipe, and the bare copper surface is easy to oxidize. The scheme sets a boron nitride coating on the surface of red copper. Boron nitride has excellent high-temperature chemical stability and lubricity. The coating forms an extremely thin isolation protection barrier between the heat-conducting gasket and the heat exchange pipe, which not only prevents the copper and steel from being connected by metal diffusion after welding, preventing the device from being difficult to pull out, but also protects the precise and smooth surface of the red copper gasket from being oxidized or scratched, while ensuring the heat-conducting performance and significantly improving the reusability of the device.

[0019] Further, the curvature radius of the arc-shaped contact surface is preset based on the inner hole size of the heat exchange pipe after the expansion process;

[0020] The outer diameter size of the heat-conducting gasket is matched with the size of the inner wall of the heat exchange pipe, so that when the heat-conducting gasket cooperates with the heat exchange pipe, a transition fit or interference fit is formed between the heat-conducting gasket and the inner wall of the heat exchange pipe.

[0021] The traditional design usually designs the tooling based on the standard inner diameter of the pipe material, ignoring the fact that the expansion process will cause the pipe diameter to expand slightly, resulting in a gap after the tooling is inserted. The size chain design of the inner hole size after the expansion is adopted in this scheme, and a transition or interference fit is adopted. Since the expansion deformation amount is considered, the device generates a radial contact pressure between the gasket and the pipe wall by using the slight elastic deformation of the red copper material after insertion. This active contact pressure can squeeze out the air at the interface, and even during the welding thermal expansion process, it can also maintain a close-fitting state, so as to ensure that the heat conduction path is always unobstructed, and avoid the generation of gaps due to the difference in thermal expansion coefficient.

[0022] Further, the heat-conducting gasket has a top end face;

[0023] The heat exchange pipe and the tube plate form a groove root at the to-be-welded position;

[0024] When the active heat dissipation device for dissimilar metal tube plate welding is installed in place, the top end face and the groove root are arranged in axial spacing;

[0025] The axial spacing between the top end face and the groove root is 1mm to 2mm.

[0026] If the distance is too close, the red copper is easy to be melted by the electric arc, resulting in copper crack in the weld; if the distance is too far, the low thermal conductivity of the stainless steel will cause the heat to be unable to be conducted to the gasket in time, resulting in heat dissipation failure. The axial avoiding distance is accurately controlled to be 1mm-2mm. The distance setting ensures that the gasket is close enough to the heat source core and can effectively capture and absorb heat within the heat conduction range, thereby inhibiting the overheating of the molten pool; and a small safety margin is reserved to avoid direct ablation of the heat conduction gasket by the electric arc or interference with the flow of the liquid molten pool, so that the heat dissipation effect is maximized under the premise of ensuring welding safety.

[0027] Further, the connection mode between the heat conduction gasket and the support body includes interference fit connection, threaded connection or clamping groove locking connection.

[0028] The heat dissipation device manufactured in one piece needs to be scrapped as a whole once the surface is worn or damaged. The heat conduction gasket is used as a direct contact part and belongs to a consumable part, and the support body is used as a structural part and has a long service life. The split design allows only the worn red copper gasket to be replaced while the brass support body is retained, which not only reduces the material cost of long-term use, but also facilitates quick replacement of gaskets of corresponding sizes for different pipe diameter specifications, thereby improving the universality and flexibility of the tool.

[0029] Further, the support body includes a cylindrical rod body and a stabilizing block arranged at one end of the rod body.

[0030] The heat conduction gasket is a hollow cylindrical sleeve.

[0031] The heat conduction gasket is coaxially sleeved on the rod body, the inner cylindrical surface of the heat conduction gasket is tightly fitted with the outer cylindrical surface of the rod body, and the outer cylindrical surface of the heat conduction gasket constitutes the arc-shaped contact surface.

[0032] The outer peripheral radius of the stabilizing block is the same as the inner peripheral radius of the heat exchange pipe.

[0033] Ordinary cantilever type insertion tool is easy to be inclined due to gravity or operation error, resulting in that one side of the gasket is in close contact while the other side is empty, and heat dissipation is uneven. The stabilizing block is arranged on the support body, and the outer peripheral radius of the stabilizing block is the same as the inner peripheral radius of the heat exchange pipe (i.e. cooperates with the inner wall of the pipe to position). The stabilizing block plays the role of self-centering, and forcibly supports the rod body of the support body to remain on the central axis of the heat exchange pipe. This directly ensures that the heat conduction gasket sleeved on the rod body can uniformly adhere to the pipe wall in all directions, avoids local heat dissipation dead angle caused by eccentricity, ensures the consistency of temperature distribution in the heat affected zone of the whole circle weld, and thus obtains uniform weld structure.

[0034] The second object of the present application is to provide a dissimilar metal pipe plate welding method using the active heat dissipation device for dissimilar metal pipe plate welding as described above, comprising the following steps:

[0035] Step S1, the heat exchange pipe is inserted into the pipe hole of the tube plate, and the expansion process is carried out, so that the heat exchange pipe is plastically deformed to fit the tube plate;

[0036] Step S2, the active heat dissipation device for dissimilar metal tube plate welding is inserted into the inside of the heat exchange pipe, and the cooperation tolerance between the outer diameter of the heat conduction pad and the inner diameter of the heat exchange pipe after expansion is used to make the heat conduction pad and the inner wall of the heat exchange pipe form a gapless close fit; at the same time, the axial depth of the active heat dissipation device for dissimilar metal tube plate welding is adjusted, so that the top end face is located at a distance of 1mm to 2mm from the root of the weld groove;

[0037] Step S3, arc ignition welding is carried out on the connection between the heat exchange pipe and the tube plate; in the welding process, the closely fitted heat conduction pad is used as a heat flow priority channel, the heat generated in the weld area is rapidly conducted to the heat conduction pad through the inner wall of the heat exchange pipe, and then to the support body for dissipation, so as to inhibit the heat accumulation on the heat exchange pipe side;

[0038] Step S4, after welding and cooling, the active heat dissipation device for dissimilar metal tube plate welding is taken out from the heat exchange pipe.

[0039] The existing process lacks active intervention for the welding process, and often relies on after-treatment (heat treatment) or passive protection (back inflation). The present scheme integrates expansion fitting, interference insertion, physical heat conduction, post-weld removal and other steps. By using the physical heat dissipation channel established in step S2 in the real-time stage of welding (step S3), the accumulation path of heat on the stainless steel side is actively cut off. The problem of dissimilar metal heat conduction mismatch is solved, so that high-quality welds without oxidation and golden yellow can be obtained continuously and stably without changing the welding parameters, which greatly improves the production efficiency and product qualification rate.

[0040] The beneficial effects of the present application are:

[0041] The application provides a kind of active heat dissipation device for dissimilar metal tube plate welding, the active heat dissipation device for dissimilar metal tube plate welding is connected to the heat-conducting gasket on the support body, the heat-conducting gasket is made of high thermal conductivity metal material, and has arc contact surface matched with the curvature radius of the inner wall of the heat exchange pipe to be welded.Compared with the existing technology, the arc contact surface of the present application is closely attached to the inner wall of the heat exchange pipe during welding.The arc contact surface with curvature matching realizes the close attachment of high thermal conductivity solid material and heat source (inner wall of heat exchange pipe).This close attachment eliminates the micro air insulation layer, and directly establishes the heat conduction path from the heat exchange pipe to the support body through the heat-conducting gasket.The heat accumulated on the low thermal conductivity heat exchange pipe during welding can be instantly transferred to the support body through the heat conduction path and dissipated, thereby realizing the heat dissipation of the welding heat source area, and the weld temperature is forcedly controlled in the ideal range, which effectively prevents overheating oxidation and ensures the welding quality. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the active heat dissipation device for dissimilar metal tube plate welding provided in the embodiments of the present application;

[0043] Figure 2 is a schematic diagram of the dissimilar metal tube plate welding method provided in the present application.

[0044] REFERENCE NUMERALS:

[0045] 1, heat-conducting gasket; 2, support body; 3, welding torch; 4, heat exchange pipe. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present application are shown in the drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0047] Example 1

[0048] As shown in Figure 1 , the present embodiment provides an active heat dissipation device for dissimilar metal tube plate welding, which comprises:

[0049] a support body 2;

[0050] a heat-conducting gasket 1 connected to the support body 2, the heat-conducting gasket 1 is made of high thermal conductivity metal material, and has arc contact surface matched with the curvature radius of the inner wall of the heat exchange pipe 4 to be welded;

[0051] The arc-shaped contact surface is used to tightly adhere to the inner wall of the heat exchange pipe 4 during welding to establish a heat conduction path from the heat exchange pipe 4 to the support body 2 through the heat-conducting gasket 1.

[0052] More specifically, the active heat dissipation device described in the embodiment mainly consists of two parts: a support body 2 and a heat-conducting gasket 1.

[0053] Among them, the heat-conducting gasket 1 is the core heat-absorbing component directly in contact with the high-temperature area, which is connected to the support body 2. The support body 2 is the base of the entire device, which not only plays the role of bearing and fixing the heat-conducting gasket 1, but also serves as a subsequent heat transfer medium or heat dissipation terminal to further guide the heat absorbed by the heat-conducting gasket 1 out.

[0054] The heat-conducting gasket 1 has a specific arc-shaped contact surface. The shape of this arc-shaped contact surface is not randomly designed, but is specially designed according to the geometric shape of the inner wall of the heat exchange pipe 4 to be welded. Specifically, the radius of curvature of the arc-shaped contact surface is consistent (or very close) to the radius of curvature of the inner wall of the heat exchange pipe 4.

[0055] The inner wall of the heat exchange pipe 4 is a cylindrical surface. If the contact surface of the heat dissipation device is flat or has a mismatched curvature, only "line contact" or "point contact" can be formed between the two, and there will be an air gap in the remaining large area. Air is a poor conductor of heat, which will hinder heat transfer. By designing the heat-conducting gasket 1 as a curvature-matched arc surface, it can be ensured that a large-area "surface contact" between the gasket and the pipe wall is formed during welding, thereby eliminating or minimizing the interfacial thermal resistance.

[0056] The heat-conducting gasket 1 is made of high-thermal-conductivity metal material.

[0057] In the embodiment, the high-thermal-conductivity metal material can include red copper, silver, aluminum, beryllium copper, chromium-zirconium copper, or other copper alloys, or even metal matrix composites containing high-thermal-conductivity reinforcing phases (such as graphene, carbon nanotubes). As long as its thermal conductivity coefficient is significantly higher than that of the stainless steel heat exchange pipe 4 to be welded, it can meet the demand for rapid heat absorption and can be used as the material of the embodiment.

[0058] The embodiment requires the arc-shaped contact surface to "tightly adhere" to the inner wall of the heat exchange pipe 4 during welding. This can be achieved in various ways, for example:

[0059] The outer diameter of the heat-conducting gasket 1 is made slightly larger than or equal to the inner diameter of the pipe (considering the tolerance), and the adhesion is achieved through the slight extrusion during mechanical insertion.

[0060] The heat-conducting gasket 1 is made slightly larger than or equal to the inner diameter of the pipe (considering the tolerance), and the adhesion is achieved through the slight extrusion during mechanical insertion.

[0061] The heat-conducting pad 1 itself can be designed as a C-shaped structure or a split structure with openings, and expands outward by its own elastic tension to fit the pipe wall.

[0062] The main role of the support body 2 is to act as a relay station for heat conduction and a mechanical skeleton. It needs to have sufficient strength to support the heat-conducting pad 1 so that it can accurately extend into a specific position in the pipe; at the same time, it also needs to have a certain heat capacity or heat conduction capacity to receive heat from the pad.

[0063] The support body 2 can be a solid metal rod, a hollow tubular structure, or a complex structure with heat dissipation fins, or even a handle-shaped holding tool.

[0064] The support body 2 is usually also made of metal materials such as brass, steel, aluminum alloy, etc. Although its heat conduction requirement is not as demanding as that of the heat-conducting pad 1, good heat conduction helps to improve the overall heat dissipation efficiency.

[0065] The heat-conducting pad 1 is connected to the support body 2. This connection can be detachable, such as through threaded rotation, interference fit insertion, buckle fixation or pin fixation. The advantage of this way is that when the heat-conducting pad 1 is worn out as a consumable, it can be replaced alone, while the support body 2 can be reused.

[0066] It can also be a non-detachable connection, such as through brazing, diffusion welding or integrated casting / processing molding (i.e. although the materials may be different, they are structurally integrated as a whole).

[0067] In actual welding operations, the operator inserts the active heat dissipation device into the inside of the heat exchange pipe 4 to be welded.

[0068] Since the heat-conducting pad 1 has an arc-shaped contact surface that matches the inner wall of the pipe, and the two are tightly fitted, a low-thermal-resistance interface is established between the inner wall of the heat exchange pipe 4 and the outer wall of the heat-conducting pad 1.

[0069] When the external welding arc generates high-temperature heat, the heat is transferred to the wall of the stainless steel heat exchange pipe 4. Since the stainless steel itself conducts heat slowly, the heat should accumulate here. At this time, the high-thermal-conductivity pad 1 tightly attached to the inside acts as a "heat flow priority channel". Heat will quickly pass through the pipe wall interface and conduct into the heat-conducting pad 1 in accordance with the principle of minimum thermal resistance.

[0070] Subsequently, the heat continues to conduct from the heat-conducting pad 1 to the support body 2 connected to it. The support body 2 absorbs heat by its own volume heat capacity, or dissipates heat to the surrounding environment through its surface exposed to the air.

[0071] This process achieves the purpose of "extracting" and "dissipating" the welding heat from the source (welding zone), effectively suppressing the temperature peak on the side of the stainless steel pipe, and preventing overheating oxidation.

[0072] Through specific structural design (curvature-matched arc surface) and material application (high-thermal-conductivity metal), the traditional "heat insulation" or "gas cooling" idea is transformed into an active "contact solid heat conduction" idea, which utilizes the device itself as a good conductor of heat to establish an efficient heat dissipation channel of "heat exchange pipe 4, heat conduction gasket 1, support body 2" in the welding moment, thereby solving the heat management problem in dissimilar metal welding.

[0073] Embodiment 2

[0074] As shown in Figure 1 the present embodiment provides an active heat dissipation device for dissimilar metal pipe plate welding, which is further described on the basis of embodiment 1, and the material selection, thermodynamic design and surface treatment process of the active heat dissipation device are optimized. The present embodiment is particularly suitable for batch welding scenarios with extremely high requirements on weld quality (such as nuclear power and high-pressure vessels).

[0075] Further, the heat capacity of the support body 2 of the active heat dissipation device for dissimilar metal pipe plate welding in the present embodiment is greater than that of the heat conduction gasket 1.

[0076] The material of the heat conduction gasket 1 is red copper, and the material of the support body 2 is brass.

[0077] The surface roughness of the arc contact surface is less than or equal to 3.2 μm.

[0078] The arc contact surface of the heat conduction gasket 1 is provided with a high-temperature-resistant anti-adhesion coating, and the material of the high-temperature-resistant anti-adhesion coating includes boron nitride.

[0079] More specifically, in the present embodiment, the two core components of the device are specifically limited in material, and a "red copper heat absorption-brass heat storage" hierarchical heat dissipation architecture is constructed.

[0080] The heat conduction gasket 1 (heat absorption end) is made of red copper (T2 pure copper). Red copper has a very high thermal conductivity (about 386 W / m·K), which is much higher than that of stainless steel and carbon steel. Red copper is selected to ensure that the gasket can respond to temperature changes at the fastest speed and "suck" heat from the pipe wall in the moment when the welding arc is ignited.

[0081] The support body 2 (heat storage / dissipation end) is made of brass (H62). Although the thermal conductivity of brass is lower than that of red copper (about 100 W / m·K), it has higher hardness and better wear resistance. More importantly, in the design of the present embodiment, the volume of the support body 2 is designed to be much larger than that of the heat-conducting gasket 1, so that the support body 2 has a larger heat capacity than the heat-conducting gasket 1.

[0082] During the welding process, the red copper gasket will rapidly rise in temperature due to its small volume and fast heat conduction. At this time, the large-volume brass support body 2, which is in close contact with it, acts as a secondary heat dissipation reservoir. It absorbs heat from the red copper gasket continuously and stably, like a huge reservoir, preventing the red copper gasket from reducing its heat absorption efficiency due to thermal saturation. This combination of material and volume design ensures both agile heat absorption at the front end and stable temperature control at the rear end.

[0083] In order to further eliminate the contact thermal resistance in physical heat conduction, the present embodiment performs precision machining on the arc-shaped contact surface of the heat-conducting gasket 1.

[0084] Through precision turning and grinding processes, the surface roughness of the arc-shaped contact surface is controlled to be Ra ≤ 3.2 μm (even up to the quasi-mirror level of Ra 0.8-1.6 μm).

[0085] The ordinary machined surface is uneven at the microscopic level, and actual contact only occurs at the peak points, with most areas still filled with air. Reducing the roughness to within Ra 3.2 significantly increases the effective contact area between the heat-conducting gasket 1 and the inner wall of the heat exchange tube 4, maximally eliminates microscopic air gaps, and ensures that heat can flow freely between metal interfaces in the form of phonon conduction.

[0086] Considering that red copper is easily oxidized at high temperatures and is prone to atomic diffusion with stainless steel, causing adhesion (commonly known as sticking), the present embodiment introduces a high-temperature-resistant anti-adhesion coating on the precision-machined arc surface of the heat-conducting gasket 1.

[0087] The high-temperature-resistant anti-adhesion coating is made of boron nitride. Boron nitride has a layered structure similar to graphite, with extremely low friction coefficient and inert chemical properties, effectively blocking the diffusion of copper atoms to the stainless steel side and preventing the device from being difficult to pull out after welding. The high-temperature-resistant anti-adhesion coating has excellent high-temperature resistance, protecting the red copper surface from high-temperature oxidation and blackening, thereby maintaining the long-term smoothness and heat conduction performance of the contact surface. Although the high-temperature-resistant anti-adhesion coating itself is an electrical insulator, thin-layer boron nitride has good thermal conductivity and will not become a bottleneck for heat conduction.

[0088] In this embodiment, the combination of red copper and brass materials achieves soft and hard combination and thermal capacity matching, the precise machining with Ra≤3.2 μm eliminates micro thermal resistance, and the boron nitride coating solves the problems of high-temperature adhesion and oxidation. The combination of the three makes the device of this embodiment not only have extremely transient heat dissipation capacity, but also have the durability and reliability required for industrial production.

[0089] In addition to the above-mentioned embodiments, the present embodiment can also be implemented in the following ways:

[0090] In addition to red copper, silver copper alloy (such as AgCu) or silver mixed in the red copper matrix can be used in the heat conduction pad 1 in the extremely high heat input scene to further improve the heat absorption response speed by using the higher thermal conductivity of silver (~429 W / m·K). If the welding temperature is extremely high and accompanied by mechanical impact, chromium zirconium copper (CuCrZr) or beryllium copper (QBe2) can be selected. Although its thermal conductivity is slightly lower than that of pure copper, its softening temperature is high (>450℃), and it is not easy to deform due to overheating, and is suitable for continuous high-intensity operation. Copper graphene composite material or copper-diamond composite material can also be used. By using the ultra-high in-plane thermal conductivity of graphene or diamond, heat is quickly transferred along the axial direction. The heat conduction pad 1 can also be designed as a hollow cavity and filled with liquid metal (such as gallium indium tin alloy) or phase change material (such as paraffin) to absorb the instantaneous heat shock by using the latent heat of phase change.

[0091] In addition to brass, aluminum alloy (such as 6061) can also be used to make the support body 2. The thermal conductivity of aluminum is better than that of brass and it is light in weight, suitable for manual long-time holding operation, and reduces fatigue. The support body 2 can also not be solid metal, but be composed of an array of super heat pipes, or have heat pipes embedded in the solid rod body. By using the evaporation and condensation cycle of the working medium, heat is conducted to the rear end heat dissipation fins at a speed much higher than that of pure copper. In the case of small current welding (small heat input), carbon steel or stainless steel can be used to make the support body 2, only using its mechanical support function, to reduce the manufacturing cost.

[0092] In addition to the boron nitride coating, silver or gold can also be electroplated on the arc-shaped contact surface. By using the oxidation resistance and excellent thermal contact performance of noble metals, the boron nitride coating is replaced, especially suitable for welding environments with extremely high vacuum requirements (no risk of falling). Molybdenum disulfide coating can also be used as a low-cost substitute for boron nitride, providing high-temperature lubrication to prevent copper and steel from adhering. Colloidal graphite can also be sprayed on the surface of the heat conduction pad 1, which has good thermal conductivity and lubricity, and is low in cost. A thin layer of indium or tin foil can also be pre-installed on the contact surface. By using the rheological property of soft metal after heating, micro cracks are filled to realize liquid-solid coupled heat transfer.

[0093] Embodiment 3

[0094] AsFigure 1 The embodiment shown provides an active heat dissipation device for dissimilar metal tube plate welding. The embodiment is further described based on the above embodiment, and focuses on the size change caused by the expansion process of the heat exchange tube 4 and the precise control of the welding heat source to optimize the structure.

[0095] Further, the curvature radius of the arc-shaped contact surface of the active heat dissipation device for dissimilar metal tube plate welding in the embodiment is preset based on the inner hole size of the heat exchange tube 4 after the expansion process;

[0096] The outer diameter size of the heat-conducting gasket 1 is matched with the size of the inner wall of the heat exchange tube 4, so that when the heat-conducting gasket 1 cooperates with the heat exchange tube 4, a transition fit or interference fit is formed between the heat-conducting gasket 1 and the inner wall of the heat exchange tube 4.

[0097] The heat-conducting gasket 1 has a top end face;

[0098] The heat exchange tube 4 and the tube plate form a bevel root at the welding position;

[0099] When the active heat dissipation device for dissimilar metal tube plate welding is installed in place, the top end face and the bevel root are arranged axially spaced apart;

[0100] The axial spacing between the top end face and the bevel root is 1mm to 2mm.

[0101] More specifically, in the actual tube plate welding process, the heat exchange tube 4 is usually first inserted into the tube plate hole for "expansion", so that the tube is plastically deformed to be preliminarily fixed. Therefore, the inner diameter of the heat exchange tube 4 will increase slightly after expansion compared to the nominal inner diameter. If the active heat dissipation device is designed according to the standard tube diameter, there will inevitably be a gap after insertion.

[0102] Therefore, in the embodiment, the curvature radius of the arc-shaped contact surface of the heat-conducting gasket 1 and the outer diameter size are not based on the original nominal size of the heat exchange tube 4, but are preset based on the actual measured inner hole size after the expansion process.

[0103] In order to achieve absolute close fitting, the heat-conducting gasket 1 and the inner wall of the heat exchange tube 4 are designed as a transition fit or a slight interference fit in the embodiment.

[0104] When the operator inserts the device into the expanded heat exchange tube 4, the heat-conducting gasket 1 is squeezed into the tube by using the relatively low modulus and slight elastic compression ability of red copper material. The radial pressure generated by this interference can actively expel the residual air between the interfaces. Even if the tube wall expands due to heat during welding, the internal gasket can maintain close fitting by relying on its own elastic restoring force. This active fitting mechanism fundamentally eliminates the heat dissipation dead angle caused by process deviation.

[0105] In addition to the radial close fit, the axial insertion depth of the heat-conducting gasket 1 directly determines the success or failure of heat dissipation. The present embodiment strictly limits this key parameter.

[0106] When the active heat dissipation device is installed in place, the axial distance between the top end face of the heat-conducting gasket 1 (i.e. the end closest to the weld) and the root of the bevel of the heat exchange tube 4 and the tube sheet to be welded is kept at 1-2 mm.

[0107] If the distance is less than 1 mm, the heat-conducting gasket 1 is too close to the high-temperature molten pool, which can easily interfere with the stability of the welding arc, and even cause the red copper gasket to be melted by the arc, resulting in copper liquid seeping into the stainless steel weld, which can cause serious copper brittle crack defects.

[0108] If the distance is greater than 2 mm, since the thermal conductivity of stainless steel is extremely low (only 1 / 3 of that of carbon steel), the conduction distance of heat in the stainless steel tube wall is very limited. If the gasket is too far away, the heat has not yet been conducted to the gasket before it has accumulated in the weld area, causing overheating oxidation and causing the heat dissipation device to fail.

[0109] Controlling the distance to be within the critical range of 1-2 mm ensures that the heat-conducting gasket 1 is within the efficient heat absorption range of the heat-affected zone, which can suppress temperature peaks, while also retaining a very small safety margin to ensure the safety of the welding operation and the purity of the weld.

[0110] In the present embodiment, the contact gap problem caused by deformation of the pipe material is solved by interference fit based on the size after expansion, and the optimal energy efficiency interval for heat management is established by the axial distance of 1-2 mm. This ensures that the active heat dissipation device can exert the maximum heat dissipation efficiency without interfering with the welding process.

[0111] In addition to the above-mentioned embodiments, the present embodiment can also be implemented in the following ways:

[0112] The heat-conducting gasket 1 can also be designed as a split structure (similar to a swelling sleeve) with a conical core rod inside. After being inserted into the pipe, the conical core rod is pulled by tightening the nut, forcing the split gasket to expand outward, thereby actively fitting the inner wall of the heat exchange tube 4 with different tolerance ranges. It can also take advantage of the high thermal expansion coefficient of red copper to cool and shrink the active heat dissipation device in liquid nitrogen or dry ice before installation, and then expand naturally at room temperature after being inserted into the pipe, achieving an interference fit with extremely high fastening force (suitable for automatic assembly lines). Non-integral solid heat-conducting gaskets 1 can also be used, which can be in the form of a C-shaped split ring structure or have wave-shaped spring steel sheets embedded inside, which always push the pipe wall outward using the elastic restoring force of the material. The heat-conducting gasket 1 can also be designed as a double-layer hollow structure with high-pressure hydraulic oil or compressed air inside, causing the outer wall to elastically bulge and fit the pipe wall.

[0113] To achieve axial positioning (controlling the gap by 1-2mm), a limiting flange (boss) with an outer diameter larger than the inner diameter of the heat exchanger tube 4 can be installed at the rear end (non-insertion end) of the support body 2 or the thermally conductive pad 1. The position of this flange is precisely calculated so that when the flange end face abuts against the tube opening of the heat exchanger tube 4 or the surface of the tube sheet, the front pad is exactly 1-2mm from the root of the weld. This method requires no measurement and achieves foolproof positioning. Alternatively, an external thread can be provided on the support body 2 rod, along with a knurled adjusting nut. The operator can steplessly adjust the insertion depth by rotating the nut to accommodate the protrusion of heat exchanger tubes 4 of different lengths. Alternatively, graduation lines or color rings can be laser-etched on the surface of the support body 2 rod, allowing the operator to visually align the tube opening during insertion.

[0114] Example 4

[0115] like Figure 1 As shown, this embodiment provides an active heat dissipation device for welding dissimilar metal tube sheets. This embodiment further elaborates on the above embodiments, focusing on the modular and functional design of the mechanical structure of the active heat dissipation device, aiming to solve the maintenance cost problem in long-term use of the device, as well as the eccentric contact problem caused by gravity or operational errors.

[0116] Furthermore, in this embodiment, the connection method between the thermally conductive pad 1 and the support body 2 of the active heat dissipation device for welding dissimilar metal tube sheets includes: interference fit connection, threaded connection, or slot locking connection.

[0117] The support 2 includes a cylindrical rod and a stabilizing block located at one end of the rod;

[0118] The thermally conductive pad 1 is a hollow cylindrical sleeve;

[0119] The thermally conductive pad 1 is coaxially sleeved on the rod body, and the inner cylindrical surface of the thermally conductive pad 1 is in close contact with the outer cylindrical surface of the rod body. The outer cylindrical surface of the thermally conductive pad 1 forms the arc-shaped contact surface.

[0120] The outer radius of the stabilizing block is the same as the inner radius of the heat exchange tube 4.

[0121] More specifically, in order to balance structural strength and thermal conductivity requirements, and to reduce consumable costs, this embodiment designs the device as a detachable component.

[0122] Support 2 is constructed as a solid cylindrical rod (usually made of brass or steel) with high mechanical strength. As the skeleton of the entire device, it is responsible for bearing the mechanical forces during insertion and removal operations.

[0123] The heat-conducting liner 1 is configured as a hollow cylindrical sleeve (made of red copper). It serves as the skin of the device and is directly responsible for contact with the high-temperature pipe wall.

[0124] The heat-conducting liner 1 is coaxially sleeved on the front end of the rod of the support body 2. When designing, it is ensured that the inner hole of the heat-conducting liner 1 has a high-precision fit with the outer circle of the support body 2. This close inner interface contact ensures that heat can be smoothly conducted from the skin (heat-conducting liner 1) to the framework (support body 2) without forming a thermal block inside the assembly.

[0125] Since the red copper heat-conducting liner 1 is a consumable part under high-temperature and high-friction working conditions, the embodiment adopts a flexible connection mode.

[0126] The heat-conducting liner 1 and the support body 2 are fixed by thread connection, interference pressure or quick-change clamping groove structure.

[0127] When the surface of the heat-conducting liner 1 is worn, scratched or severely oxidized due to long-term use, causing a decrease in heat conduction, the entire tool does not need to be scrapped. Instead, the old sleeve can be unscrewed or pulled out, and a new red copper sleeve can be replaced, greatly reducing the use cost throughout the life cycle.

[0128] For heat exchange pipes 4 of different wall thicknesses (such as slight changes in inner diameter), the same standardized support body 2 rod can be used, and only the heat-conducting liner 1 sleeve with different outer diameters needs to be replaced to adapt, improving the versatility and flexibility of the tool.

[0129] Since the active heat dissipation device is usually inserted into the heat exchange pipe 4 in a cantilevered manner, it is prone to sagging under the influence of gravity, causing the upper part of the heat-conducting liner 1 to be separated from the pipe wall and the lower part to be in tight contact, resulting in uneven heat dissipation. Therefore, the embodiment introduces an auxiliary positioning structure.

[0130] A stabilizing block (or positioning ring) is arranged at the rear end (the end away from the weld) of the rod of the support body 2.

[0131] The outer peripheral radius of the stabilizing block is designed to be the same as the inner peripheral radius of the heat exchange pipe 4 (considering the sliding fit clearance).

[0132] When the device is inserted into the pipe, the front end is supported by the heat-conducting liner 1, and the rear end is supported by the stabilizing block. The stabilizing block plays the role of self-centering and righting, forcing the support body 2 rod to always remain on the central axis of the heat exchange pipe 4.

[0133] This double-point support design effectively overcomes the cantilever sagging caused by gravity, ensuring that the front-end heat-conducting liner 1 can uniformly adhere to the pipe wall along the circumference of 360 degrees, avoiding uneven weld structure caused by local heat dissipation dead angles.

[0134] The embodiment realizes low-cost maintenance and multi-specification adaptation through the split design of the rod sleeve, and guarantees the coaxiality and uniformity of contact through the design of the rear end stabilizing block. The active heat dissipation device not only has excellent thermal performance, but also has the economy and stability required for large-scale application in industrial sites.

[0135] In addition to the above-mentioned embodiments, the present embodiment can also be implemented in the following ways:

[0136] In addition to the rod sleeve connection method, a Morse taper can also be machined on the front end of the support body 2 and the inner hole of the heat conduction gasket 1, and the connection is realized by using the self-locking characteristics of the taper surface, which not only guarantees extremely high coaxiality, but also greatly increases the contact surface pressure, and the heat conduction effect is better than that of threaded connection. After the heat conduction gasket 1 is sleeved, it can be fixed by laterally punching elastic pins or jacks. It can also be quickly locked by using a C-shaped spring or a ball locking mechanism (similar to a sleeve wrench joint).

[0137] The structure of the support body 2 can also be designed as hollow, and the tail is connected to a compressed air pipe or a circulating water pipe to form a cooling flow channel inside. Although the structure is complex, it can realize forced cooling under continuous operation. Further, heat dissipation fins can be machined on the part of the support body 2 exposed outside the pipe to increase the heat exchange area with the air and improve the natural convection heat dissipation efficiency. For occasions where the space of the pipe box is small and the straight rod cannot be inserted, the support body 2 can be designed as a metal flexible shaft or a universal joint structure, and only the front end heat conduction gasket 1 remains rigid.

[0138] In addition to the stabilizing block at the tail, a second or third support ring can be added to the middle of the support body 2 to further improve the rigidity and stability of the slender rod body. The sliding friction stabilizing block can also be replaced with a micro ball bearing or universal ball bearing to reduce the friction resistance during insertion and removal, and the positioning is more accurate. A micro support rod mechanism similar to a three-jaw chuck can also be designed at the tail to expand and support the pipe wall after insertion, and the centering effect is the best, which is suitable for large-diameter heat exchange pipes 4.

[0139] Embodiment 5

[0140] As shown in Figure 1 , Figure 2 , the present embodiment provides a dissimilar metal tube plate welding method. The active heat dissipation device for dissimilar metal tube plate welding as described in the foregoing embodiments is used. The present embodiment aims to solve the problem that the existing process lacks real-time intervention on the welding heat source, and through standardized operation steps, it is ensured that each weld can be completed within the ideal temperature range.

[0141] The method comprises:

[0142] Step S1, inserting the heat exchange pipe 4 into the pipe hole of the tube plate and performing expansion process to make the heat exchange pipe 4 plastically deform to fit the tube plate;

[0143] Step S2, insert the active heat dissipation device for dissimilar metal tube sheet welding into the inside of the heat exchange tube 4, and make the heat conduction liner 1 and the inner wall of the heat exchange tube 4 form a gapless close fit by using the cooperation tolerance between the outer diameter of the heat conduction liner 1 and the inner diameter of the heat exchange tube 4 after expansion; at the same time, adjust the axial depth of the active heat dissipation device for dissimilar metal tube sheet welding, so that the top end face is located at a distance of 1mm to 2mm from the root of the weld groove;

[0144] Step S3, arc ignition welding is performed on the connection between the heat exchange tube 4 and the tube sheet; during the welding process, the heat conduction liner 1 in close fit is used as a heat flow preferential channel, the heat generated in the weld area is quickly conducted to the heat conduction liner 1 through the inner wall of the heat exchange tube 4, and then to the support body 2 for dissipation, so as to inhibit the heat accumulation on the side of the heat exchange tube 4;

[0145] Step S4, after the welding is completed and cooled, the active heat dissipation device for dissimilar metal tube sheet welding is taken out from the heat exchange tube 4.

[0146] More specifically, the dissimilar metal tube sheet welding method in the embodiment includes the following specific steps:

[0147] Step S1.1, cleaning and assembly:

[0148] First, mechanically clean the tube holes of the Q345R carbon steel tube sheet and the end of the stainless steel heat exchange tube 4, remove oil stains, rust and oxide skin, and expose the metal luster. Insert the heat exchange tube 4 into the tube sheet hole, and adjust the tube end extension length (usually flush or slightly extended), to ensure that the assembly gap meets the welding process evaluation requirements.

[0149] Step S1.2, expansion:

[0150] Use a hydraulic pipe expander or a mechanical pipe expander to expand the heat exchange tube 4 within the thickness range of the tube sheet.

[0151] This step not only fixes the tube, but more importantly, causes plastic deformation of the heat exchange tube 4, which slightly expands the inner diameter and is fixed. The inner diameter after expansion is the reference size for selecting the active heat dissipation device later.

[0152] Step S2.1, device selection and inspection:

[0153] According to the actual measured inner diameter after expansion in step S1.2, select an active heat dissipation device with an outer diameter size matching the inner diameter (usually with a +0.01mm to +0.05mm interference amount). Check whether the boron nitride coating on the surface of the heat conduction liner 1 is complete, to ensure that there are no scratches or foreign matters.

[0154] Step S2.2, interference insertion:

[0155] Align the active heat sink device with the tube opening of the heat exchange tube 4, and apply an axial pushing force to push it in. Due to the interference fit, a noticeable damping sensation will be felt during insertion. At this time, the red copper heat conduction pad 1 undergoes a small amount of elastic deformation under the action of extrusion, is forced to tightly adhere to the tube wall, expels the interfacial air, and forms a physical contact state without gaps.

[0156] Step S2.3, axial precise positioning:

[0157] Use a depth vernier caliper or the limiting fixture provided with the device to fine-tune the insertion depth of the device. Make sure that the top end face of the heat conduction pad 1 stops at a position 1.5mm ± 0.5mm axially away from the root of the weld bevel. This position can both ensure that the welding arc does not directly ablate the red copper pad and ensure that the pad is in the core heat absorption range of the heat affected zone.

[0158] Step S3.1, igniting the arc:

[0159] Use the tungsten argon arc welding process to ignite the arc at the junction of the tube plate and the tube opening.

[0160] Step S3.2, dynamic heat absorption process:

[0161] As the welding torch 3 moves along the ring, the high temperature generated by the arc is instantly transferred to the stainless steel tube wall. At this time, the red copper pad tightly adhering to the inside of the tube wall plays the role of a heat flow preferential channel, and before the heat has accumulated deep into the stainless steel tube, it is quickly absorbed into the pad interior via the contact surface and further conducted to the brass support body 2 with large heat capacity. During welding, it can be observed that the weld pool has good fluidity, and the weld after welding appears silver or golden, indicating that the heat input has been effectively controlled and overheating oxidation has not occurred.

[0162] Step S4.1, cooling and pulling out:

[0163] After the welding arc is extinguished, the device is kept in the tube for about 30-60 seconds, and the temperature of the weld area is reduced to a safe range (e.g. below 200℃). Then, using the handle at the back end of the support body 2 or a special tool, the device is smoothly pulled out against the interference friction force.

[0164] Step S4.2, cleaning and reuse:

[0165] After removing the device, immediately wipe the surface of the heat conduction pad 1 with a clean cloth to remove the soot, and check the surface finish and coating condition. After confirming that there is no damage, it can be used for welding of the next weld, achieving efficient cyclic operation.

[0166] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and practice described. Accordingly, all such variations are intended to be included within the scope of the present application as defined in the following claims, along with full equivalents thereof.

[0167] In addition, it should be noted that the use of "first", "second", etc., to describe a number of steps or components in the examples illustrated herein are used only to easily relate one step or component to another, and is not intended to limit the scope of the application unless otherwise specifically stated. Thus, the use of "first", "second", etc., is not intended to limit the scope of the application.

[0168] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An active heat sink device for dissipation of heat from a dissimilar metal tube-to-plate weld, comprising: The utility model relates to a kind of active heat dissipation devices for dissimilar metal tube plate welding, comprising: Support body (2); Thermal pad (1) connected with the support body (2), the thermal pad (1) is made of high thermal conductivity metal material, and has arc contact surface matched with the inner wall curvature radius of heat exchange pipe (4) to be welded; The arc contact surface is used to tightly adhere to the inner wall of the heat exchange pipe (4) during welding, to establish the heat conduction path from the heat exchange pipe (4) to the support body (2) through the thermal pad (1).

2. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The heat capacity of the support body (2) is greater than that of the thermal pad (1).

3. The active heat dissipation device for dissimilar metal tube plate welding according to claim 2, wherein: The material of the thermal pad (1) is red copper, and the material of the support body (2) is brass.

4. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The surface roughness of the arc contact surface is less than or equal to 3.2 μm.

5. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The arc contact surface of the thermal pad (1) is provided with a high-temperature-resistant anti-adhesion coating, and the material of the high-temperature-resistant anti-adhesion coating comprises boron nitride.

6. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The curvature radius of the arc contact surface is preset based on the inner hole size of the heat exchange pipe (4) after expansion process; The outer diameter size of the thermal pad (1) is matched with the size of the inner wall of the heat exchange pipe (4), so that when the thermal pad (1) cooperates with the heat exchange pipe (4), a transition fit or an interference fit is formed between the thermal pad (1) and the inner wall of the heat exchange pipe (4).

7. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The thermal pad (1) has a top end surface; The heat exchange pipe (4) and the tube plate form a bevel root at the position to be welded; When the active heat dissipation device for dissimilar metal tube plate welding is installed in place, the top end surface and the bevel root are arranged in axial spacing; The axial spacing between the top end surface and the bevel root is 1 mm to 2 mm.

8. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The connection mode between the thermal pad (1) and the support body (2) comprises interference fit connection, threaded connection or clamping groove locking connection.

9. The active heat dissipation device for dissimilar metal tube plate welding according to claim 1, wherein: The support body (2) comprises a cylindrical rod body and a stabilizing block arranged at one end of the rod body; The thermal pad (1) is a hollow cylindrical sleeve; The thermal pad (1) is coaxially sleeved on the rod body, the inner cylindrical surface of the thermal pad (1) tightly adheres to the outer cylindrical surface of the rod body, and the outer cylindrical surface of the thermal pad (1) constitutes the arc contact surface. The outer peripheral radius of the stabilizing block is the same as the inner peripheral radius of the heat exchange tube (4).

10. A method of welding a dissimilar metal tube sheet, the method comprising: The application discloses a heat dissipation device for dissimilar metal tube plate welding. Step S1, the heat exchange tube (4) is inserted into the tube hole of the tube plate, and an expansion process is performed to make the heat exchange tube (4) plastically deform to fit the tube plate; Step S2, the heat dissipation device for dissimilar metal tube plate welding is inserted into the inside of the heat exchange tube (4), the cooperation tolerance between the outer diameter of the heat conduction gasket (1) and the inner diameter of the heat exchange tube (4) after expansion is utilized to make the heat conduction gasket (1) and the inner wall of the heat exchange tube (4) tightly fit without gap; meanwhile, the axial depth of the heat dissipation device for dissimilar metal tube plate welding is adjusted, so that the top end face is located at a distance of 1mm to 2mm from the root of the weld bevel; Step S3, arc ignition welding is performed on the connection part of the heat exchange tube (4) and the tube plate; in the welding process, the tightly fitted heat conduction gasket (1) is used as a heat flow channel, heat generated in the weld area is rapidly conducted to the heat conduction gasket (1) through the inner wall of the heat exchange tube (4), and then is conducted to the support body (2) for dissipation, so that heat accumulation on the heat exchange tube (4) side is inhibited; Step S4, after the welding is completed and cooled, the heat dissipation device for dissimilar metal tube plate welding is taken out from the heat exchange tube (4).

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