A small pipe diameter inner hole welding gun head integrated structure

Abstract

The application discloses a small-diameter inner hole welding gun head integrated structure, which comprises a metal core rod and a ceramic sleeve. The metal core rod is integrally processed from a single metal blank, an axial protection gas flow channel is formed in the metal core rod, and a continuous spiral water cooling groove is arranged on the outer circle of the metal core rod; the ceramic sleeve is coaxially arranged outside the metal core rod and is precisely matched with the metal core rod, the inner wall of the ceramic sleeve and the spiral water cooling groove jointly form a closed cooling water flow channel, the protection gas flow channel and the cooling water flow channel are separated from each other and are communicated with the same gas-water conversion joint, and two sets of independent medium circulation channels are formed. The metal core rod is integrated with the ceramic sleeve to form a composite rigid base body, the closed water cooling channel is combined with the built-in gas channel to realize double cooling, the ceramic sleeve restrains the high-temperature deformation of the metal core rod, the linear precision of the slender gun body is ensured, the surrounding water cooling increases the heat exchange area, the protection gas synchronously completes the welding seam protection and internal heat exchange, and the problems of the existing slender inner hole welding gun, such as high-temperature deformation, low cooling integration degree and difficulty in adapting to the welding of thin and deep pipes, are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of welding equipment technology, and more specifically relates to an integrated structure of a small-diameter inner hole welding torch head adapted for welding small-diameter deep-hole heat exchange tubes. Background Technology

[0002] Internal welding is a core process for solving the reliability problem of heat exchanger tube and tube sheet connection under high temperature and high pressure conditions. It is widely used in the manufacturing of high-end heat exchange equipment in nuclear power, chemical industry and other fields. However, the existing internal welding torch head structure has several technical defects that are difficult to resolve simultaneously, and cannot meet the stable welding requirements of slender heat exchanger tubes with an inner diameter of no more than 10 mm and an insertion depth of no less than 100 mm. The specific technical shortcomings are as follows:

[0003] First, existing welding torches are too large, limiting their compatibility with pipe diameters and insertion depths. The overall outer diameter of most commercially available internal welding torches is greater than 20mm, making them only suitable for welding pipes with an inner diameter of 20mm or more. Furthermore, the depth to which the torch can penetrate the workpiece is mostly no more than 50mm. For deep-hole heat exchange tubes with a depth of up to 100mm, existing welding torches cannot reach the weld seam, making it difficult to complete deep-hole internal wall welding operations.

[0004] Secondly, for welding scenarios involving small-diameter deep holes, the welding torch needs to be designed with a slender structure. However, existing slender welding torches mostly use a single metal integrated torch body. The welding arc continuously releases a large amount of heat, and the torch body is prone to thermal deformation after being heated, resulting in a significant decrease in overall straightness. The deformed torch head will scrape against the inner wall of the pipe, directly causing welding failure and making it impossible to achieve stable and high-precision welding.

[0005] Third, the cooling structure has low integration and insufficient heat dissipation capacity, making it difficult to perform continuous welding for extended periods. Existing solutions mostly use separate piping, single water cooling, or uniaxial structures without external reinforcement, resulting in limited heat exchange area. Over long periods of welding, the temperature of the welding torch increases sharply, further exacerbating thermal deformation.

[0006] A search revealed prior art documents related to this application, including: Reference document 1 (CN220388205U) discloses a TIG inner wall welding torch suitable for surfacing and welding the inner walls of small-diameter pipes, which uses a beryllium-zirconium copper heat-resistant torch body in conjunction with a circulating water cooling system; Reference document 2 (CN204449589U) discloses a spiral water-cooled welding torch head, which uses a copper torch head body, a ceramic protective cover, and a spiral refrigerant coil structure; Reference document 3 (CN113695718B) discloses a rotating TIG welding torch, whose long straight conductive shaft has a gas channel and a water cooling channel and a gas-water distribution structure; Reference document 4 (CN202963758U) discloses a water-cooled TIG small welding torch, with a copper long rod torch body and a water cooling ring; and Reference document 5 (CN103692069A) discloses a double water-cooled ultra-small diameter pipe inner wall TIG surfacing welding torch, with an annular water cooling groove at the torch head. While the aforementioned existing technologies have made improvements in their respective aspects, none of them have solved the comprehensive technical problem of achieving a high degree of integration between the spiral-shaped water-cooling channel and the built-in protective airflow channel within a limited radial dimension, while using the ceramic jacket to constrain the high-temperature deformation of the metal core rod. In particular, they lack a specific structural design for enclosing the spiral groove on the outer wall of the metal core rod with the inner wall of the ceramic jacket to form a closed cooling channel. Summary of the Invention

[0007] To address the problems of existing technologies, such as the slender welding torch being prone to deformation at high temperatures, low integration of the cooling system, and inability to adapt to welding small-diameter deep pipes, this invention aims to provide an integrated structure for a welding torch head with a small-diameter inner bore.

[0008] According to the integrated structure of the small-diameter inner bore welding torch head of the present invention, it includes a metal core rod and a ceramic jacket. The metal core rod is a single metal blank integrally machined component, with a protective airflow channel axially extending inside the metal core rod, and a continuous spiral water-cooling groove formed on the outer cylindrical surface of the metal core rod. The ceramic jacket is coaxially fitted onto the outside of the metal core rod and precisely fits with it. The inner wall of the ceramic jacket and the spiral water-cooling groove enclose a closed cooling water flow channel. The protective airflow channel and the cooling water flow channel are separated from each other by the solid material of the metal core rod. The protective airflow channel and the cooling water flow channel are respectively connected to the same gas-water conversion joint, forming two sets of non-interconnected medium circulation channels. Compared with the closest prior art (such as reference document 2), the distinguishing technical feature of the present invention is that: a continuous spiral water-cooling groove is directly machined on the outer cylindrical surface of the metal core rod, and a closed cooling water flow channel is formed by the inner wall of the ceramic jacket. At the same time, the protective airflow channel is axially extended inside the core rod, and the two are separated by the core rod and converge at the same gas-water conversion joint. Based on the above differences, the actual technical problem solved by this invention is how to achieve maximum heat exchange area coverage of the cooling water channel and highly integrated arrangement of air and water channels under extremely small radial dimension constraints, while utilizing the rigid constraint of the ceramic jacket to suppress high-temperature bending deformation of the slender mandrel. This invention uses a one-piece molded metal mandrel combined with a ceramic jacket to form a composite matrix. The outer wall of the mandrel is grooved, and the inner ceramic wall encloses and forms the cooling water flow channel. An independent protective airflow channel is set inside the mandrel to achieve dual-loop medium circulation. This significantly improves the high-temperature rigidity of the slender gun body, integrates the cooling and protective medium channels, and is suitable for welding small-diameter, deep-pipe applications.

[0009] In a preferred embodiment, the material used to prepare the metal core rod is selected from beryllium bronze alloy, aluminum alloy, and molybdenum alloy. This invention, by selecting a high thermal conductivity rigidity metal alloy to prepare the core rod substrate, can balance electrical conductivity and thermal conductivity efficiency, further suppressing high-temperature deformation.

[0010] In a preferred embodiment, the ceramic jacket is made of a material selected from zirconium oxide and silicon nitride. This invention, by employing a high-temperature resistant ceramic with a low coefficient of thermal expansion as the outer constraint structure, can provide radial support to the metal mandrel, limiting thermal bending and stabilizing the overall straightness accuracy of the welding torch.

[0011] In a preferred embodiment, the spiral water-cooling groove is continuously arranged along the entire working section of the metal mandrel, and the cooling water channel is completely arranged around the outer circumference of the metal mandrel. This invention, by covering the outer circumference of the mandrel with a spiral cooling water channel that surrounds the entire mandrel, can increase the heat exchange contact area of ​​the cooling water, comprehensively remove the heat generated during welding, and enhance the water cooling heat dissipation capacity.

[0012] In a preferred embodiment, the protective airflow channel is a through-hole structure with one or more through holes, and the medium transported by the protective airflow channel simultaneously completes the isolation of the molten pool and the internal heat exchange of the mandrel. This invention achieves air-cooled auxiliary heat dissipation by reusing the protective airflow channel as an internal heat dissipation channel, which can be combined with a water-cooling structure to form two independent cooling circuits for coordinated heat dissipation, reducing the operating temperature of the gun body.

[0013] In a preferred embodiment, the front end of the metal mandrel is provided with a protective gas ejection chamber, and the front end of the protective gas flow channel is connected to the protective gas ejection chamber. This invention, by providing an independent gas outlet chamber at the front end of the mandrel to buffer the airflow, can output a uniform and stable protective gas flow, avoiding localized airflow turbulence that could cause weld oxidation defects.

[0014] In a preferred embodiment, a protective gas nozzle is provided at the front end of the ceramic jacket, and the protective gas nozzle is coaxially arranged with the protective gas ejection chamber. This invention, through the coaxially matched nozzle structure at the front end of the ceramic jacket, regulates the airflow pattern, forming a laminar flow protective gas shield and improving the effect of isolating the molten pool from air.

[0015] In a preferred embodiment, the overall coaxial straightness of the assembled metal mandrel and ceramic jacket is no greater than 0.05 mm. This invention, by strictly controlling the coaxial precision of the assembly, avoids the slender torch body scraping against the inner wall when inserted into the pipe, thus continuously ensuring welding positioning accuracy.

[0016] In a preferred embodiment, the cooling water circulation flow rate inside the cooling water channel is not less than 2 L / min. This invention ensures that the spiral water-cooled structure continuously has sufficient heat exchange medium and maintains a stable heat dissipation effect by limiting the minimum cooling water flow rate.

[0017] This invention employs an integrated structure combining a one-piece molded metal mandrel and a ceramic jacket. A surrounding cooling water channel is formed by the spiral grooves on the outer wall of the mandrel and the inner wall of the ceramic jacket. Simultaneously, an independent protective airflow channel is set inside the mandrel, constructing a dual-medium circulation loop of water cooling and air cooling that does not interfere with each other. On one hand, the rigid constraint of the ceramic outer layer reduces the high-temperature deformation of the slender torch body, ensuring positioning accuracy when working in deep pipes with small inner diameters. On the other hand, the dual cooling mechanism of full-area surrounding water cooling and synchronous airflow heat exchange significantly improves heat dissipation efficiency, supporting long-term continuous welding operations. The integrated layout eliminates the need for external, distributed pipelines, reducing the overall outer diameter. With a three-way isolation medium adapter, the parameters of the protective gas and cooling water can be independently adjusted. Combined with a front-end buffer outlet chamber, coaxial ceramic nozzle, adjustable tungsten electrode locking structure, and a rear-end sealing plug, the airflow pattern is further stabilized, adapting to various welding conditions and ensuring the sealing of the medium loop. Through the aforementioned synergistic cooperation among the various components of this invention, a comprehensive technical effect of "radial constraint of ceramic jacket + comprehensive heat exchange of spiral water cooling + synchronous heat dissipation of built-in air path" is achieved. This effect is not a simple superposition of the individual effects of each component, but a synergistic gain generated by the integrated structural design under the constraint of small pipe diameter. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall shape of the integrated structure of the small-diameter inner hole welding torch head of the present invention.

[0019] Figure 2 for Figure 1 A schematic diagram of the overall cross-sectional structure.

[0020] Figure 3 for Figure 1 A schematic diagram of the first cross-sectional structure of a metal core rod.

[0021] Figure 4 for Figure 1 A second cross-sectional view of the metal core rod.

[0022] Figure 5 for Figure 1 A cross-sectional structural diagram of the gas-water conversion joint.

[0023] Figure 6 for Figure 1 An end view of the gas-water conversion connector.

[0024] Figure 7 for Figure 1 A schematic diagram of the individual structure of the ceramic jacket.

[0025] Figure 8 for Figure 1 A schematic diagram showing the complete flow direction of the protective gas.

[0026] Figure 9 for Figure 1 A three-dimensional schematic diagram showing the complete flow of cooling water. Detailed Implementation

[0027] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0028] like Figure 1 , Figure 2 As shown, the integrated structure of the small-diameter inner bore welding torch head according to the present invention includes a metal core rod 1, a ceramic jacket 2, a tungsten electrode 3, a tungsten electrode set screw 4, a gas-water conversion connector 5, and an end cap 6.

[0029] The metal core rod 1 is the core component of this welding torch head. The ceramic sleeve 2 is coaxially fitted onto the outside of the metal core rod 1, with a precise clearance fit between the two, together forming a double-layer composite torch body for the slender working section. The ceramic sleeve 2 is high-temperature resistant and rigid, which can limit the high-temperature expansion and bending of the metal core rod 1, thereby improving the straightness maintenance capability of the welding torch under high-temperature conditions through this composite structure. In a preferred embodiment, after the metal core rod 1 and the ceramic sleeve 2 are assembled, the overall coaxial straightness is no more than 0.05mm, ensuring that the slender torch body will not scrape against the pipe wall when inserted into a narrow pipe.

[0030] The tungsten electrode 3 is assembled inside the front end of the metal mandrel 1 and is the core component for arc initiation and conduction in TIG welding, relying on the metal mandrel 1 to conduct welding current. The diameter of the tungsten electrode 3 is 1.6mm to 2.4mm. A tungsten electrode set screw 4, used to lock the tungsten electrode 3, is horizontally inserted through the front side wall of the metal mandrel 1, firmly securing the tungsten electrode 3. The extension length of the tungsten electrode 3 can be adjusted to adapt to different welding conditions. Specifically, the tungsten electrode set screw 4 is threadedly fitted into a threaded hole on the front side wall of the metal mandrel 1, with the top of the screw pressing against the outer circle of the tungsten electrode 3, achieving a detachable and adjustable length fixation of the tungsten electrode 3. Loosening the screw allows the tungsten electrode 3 to be pushed and pulled back and forth, adjusting the extension length from 0.5mm to 3mm. After locking, the tungsten electrode does not move during welding, ensuring a stable welding arc.

[0031] The gas-water conversion connector 5 is a component that connects the external gas source, cooling water source, and the internal flow channel of the welding torch. It is fixedly assembled at the rear end of the metal mandrel 1. The end plug 6 and the gas-water conversion connector 5 are arranged adjacent to each other along the axial direction of the metal mandrel 1 to seal the rear end opening of the metal mandrel 1 and prevent the shielding gas from leaking from the rear end.

[0032] A protective gas flow channel 7 is axially integrated inside the metal mandrel 1. The front end of the protective gas flow channel 7 leads to the protective gas ejection chamber 8, and the tungsten electrode 3 extends coaxially from the protective gas ejection chamber 8. A continuous spiral water-cooling groove is formed on the outer cylindrical surface of the metal mandrel 1. The inner wall of the ceramic jacket 2 and the spiral water-cooling groove together form a closed cooling water flow channel 9. The protective gas flow channel 7 and the cooling water flow channel 9 are independent and not interconnected. The rear ends of both are individually connected to the corresponding channels of the gas-water conversion connector 5, forming an independent and controllable gas-cooled flow channel and water-cooled circuit. The two independently separated flow channels allow for independent adjustment of the protective gas flow rate and the cooling water circulation flow rate, preventing gas-water crossflow interference. This allows for matching different welding parameters and simultaneous dual-synchronous heat dissipation through gas and water cooling, significantly improving heat dissipation capacity.

[0033] like Figure 3 and Figure 4 As shown, the metal mandrel 1 is a single-piece metal blank machined into shape, with an overall slender cylindrical structure, serving as the main support for the conductive and gas / water channels of the entire welding torch. In a preferred embodiment, the metal mandrel 1 is machined from a single piece of metal raw material without any segmented splicing structure. The material used to prepare the metal mandrel 1 is selected from beryllium bronze alloy, aluminum alloy, and molybdenum alloy. All three materials possess high thermal conductivity and high electrical conductivity, suitable for the electrical conductivity and heat conduction requirements of long-term welding. The total length of the metal mandrel 1 is set to 100mm to 120mm, fully covering the requirements for deep hole welding up to 100mm in depth, and its overall outer diameter is suitable for pipes with an inner diameter not exceeding 10mm.

[0034] A threaded hole is opened on the front side wall of the metal core rod 1, and a tungsten electrode set screw 4 is fitted into the threaded hole.

[0035] The protective gas flow channel 7 is formed by drilling axially from the rear end along the axis of the metal mandrel 1. The protective gas flow channel 7 is a through-hole structure with one or more through holes, each with a diameter of not less than 2 mm. The protective gas ejection chamber 8 is radially positioned at the front end of the metal mandrel 1 and communicates with the front end of the protective gas flow channel 7. The diameter of the protective gas ejection chamber 8 is controlled within the range of 3 mm to 8 mm. The tungsten electrode 3 is coaxially inserted into the protective gas ejection chamber 8. The diameter of the tungsten electrode 3 is selected from 1.6 mm to 2.4 mm. Using the tungsten electrode set screw 4, the length of the tungsten electrode 3 extending beyond the front end of the protective gas ejection chamber 8 is adjustable, with an adjustment range of 0.5 mm to 3 mm, adapting to different welding currents and weld formation requirements. The protective gas delivered by the protective gas flow channel 7 simultaneously completes the isolation of the molten pool and heat exchange within the mandrel. For example, welding protective argon gas is delivered from the gas-water conversion joint 5 to the front end via the protective gas flow channel 7. During the gas flow, it continuously carries away heat from the inside of the metal mandrel 1, while argon gas is output from the protective gas ejection chamber 8 to isolate air and prevent weld oxidation.

[0036] A protective gas inlet channel 71 is radially opened at the rear end of the metal core rod 1, which is connected to the protective gas flow channel 7. For example... Figure 5As shown, the gas-water conversion connector 5 has a protective gas interface 51. The protective gas inlet channel 71 is connected to the protective gas interface 51, thereby realizing the introduction of protective gas.

[0037] A continuous spiral water-cooling groove is integrally machined on the outer cylindrical surface of the metal core rod 1. The spiral water-cooling groove has a width of at least 1 mm and a depth of at least 0.5 mm, with a unidirectional spiral pitch of 4 mm to 8 mm. The spiral water-cooling groove completely covers the entire slender working section of the metal core rod 1. When the ceramic jacket 2 is fitted onto the outside of the metal core rod 1, the inner wall of the ceramic jacket 2 seals the opening side of the spiral water-cooling groove, forming a complete, sealed, and encircling cooling water channel 9. This invention arranges the cooling water channel on the outer ring of the core rod, without occupying the axial space. The axial space can be completely set with a large-diameter protective airflow channel. At the same time, it completely wraps the metal core rod 1 360 degrees, maximizing the heat exchange contact area and significantly improving the water cooling efficiency.

[0038] The rear end of the metal core rod 1 has a cooling water inlet channel 91 and a cooling water outlet channel 92, respectively, which are connected to both ends of the spiral cooling water channel 9. Figure 5 As shown, the air-water conversion connector 5 has an independent cooling water inlet 52 and a cooling water outlet 53. The cooling water inlet channel 91 is connected to the cooling water inlet 52 of the air-water conversion connector 5, and the cooling water outlet channel 92 is connected to the cooling water outlet 53, thereby realizing the introduction and export of cooling water.

[0039] The protective airflow channel 7 is open to the rear end and sealed by the end plug 6 to prevent the protective gas from leaking from the tail gap and ensure stable airflow pressure.

[0040] like Figure 6 As shown, the ceramic jacket 2 is a hollow cylindrical part, coaxially and completely fitted onto the outside of the metal core rod 1, with the two fitting precisely together. The ceramic jacket 2 is made of either zirconium oxide or silicon nitride. Both types of ceramics are resistant to high temperatures, have low coefficients of thermal expansion, and are highly rigid, making them less prone to deformation under high-temperature welding conditions. They can provide radial rigidity to the inner metal core rod 1, inhibiting its high-temperature expansion and bending. The ceramic jacket 2 of this invention can significantly reduce the amount of thermal deformation after continuous welding with a welding torch; after welding ten joints consecutively, the high-temperature deformation can be controlled within 0.1 mm.

[0041] A protective gas nozzle 21 is provided at the front end of the ceramic jacket 2. The protective gas nozzle 21 is coaxially arranged with the protective gas ejection chamber 8. The nozzle position and diameter correspond one-to-one with the protective gas ejection chamber 8. After the protective gas is ejected, it can form a uniform laminar airflow, stably isolate air, and improve the weld formation quality. The inner wall of the ceramic jacket 2 completely fits the non-grooved area of ​​the outer circle of the metal core rod 1, seals the opening of the spiral water cooling groove, and forms a continuous and leak-free cooling water channel 9.

[0042] like Figures 5-6As shown, the protective gas interface 51, cooling water inlet 52 and cooling water outlet 53 inside the connector are three physically separated independent vertical channels, arranged in a circle, for connecting to the external protective gas source, cooling water tank outlet pipe and cooling water tank return pipe.

[0043] The cooling system of this invention includes two completely independent cooling channels, namely an air-cooled channel and a water-cooled circuit. The two work together to achieve dual high-efficiency heat dissipation. The internal cooling water circulation flow rate of the cooling water channel 9 is preferably not less than 2L / min.

[0044] air-cooled flow channel Figure 8 As shown, the external protective gas is introduced from the protective gas interface 51 of the gas-water conversion joint 5, and flows forward into the protective gas flow channel 7 at the axis of the metal mandrel 1 along the protective gas interface channel 71. The airflow passes through the interior of the metal mandrel 1 axially throughout the entire process, continuously carrying away the heat in the center of the mandrel and completing the gas cooling heat exchange. The gas is finally delivered to the front protective gas ejection chamber 8, passes through the front nozzle 21 of the ceramic jacket 2 and is ejected outward, wrapping the welding arc and the molten pool, isolating the air to prevent the weld from oxidizing, and simultaneously completing the welding protection.

[0045] Water cooling circuit such as Figure 9 As shown, the low-temperature cooling water in the cooling water tank is introduced from the cooling water inlet 52 of the air-water conversion joint 5, flows into the cooling water inlet channel 91 at the rear end of the metal core rod 1, and enters the spiral cooling water channel 9 formed by the metal core rod 1 and the ceramic jacket 2. The cooling water flows forward along the spiral groove, wrapping around the metal core rod 1 in a 360-degree circle, fully absorbing the large amount of heat generated by the welding of the metal core rod. Then, it flows back along the spiral groove to the cooling water outlet channel 92 at the rear end of the metal core rod, and then flows back to the external cooling water tank through the cooling water outlet 53 of the air-water conversion joint 5, completing the closed-loop water cooling cycle. The spiral-shaped cooling water channel has a large heat exchange area and uniform wrapping, which greatly improves the heat dissipation effect. Under continuous welding conditions, the surface temperature of the welding torch can be controlled below 200℃.

[0046] The assembly process of the welding torch of the present invention is as follows: First, insert the tungsten electrode 3 into the protective gas ejection chamber 8 at the front end of the metal mandrel 1. After adjusting the extension length, tighten the tungsten electrode set screw 4 to lock the tungsten electrode 3. Then, put the ceramic sleeve 2 from the rear end of the metal mandrel 1 forward, so that the inner wall of the ceramic sleeve 2 fits precisely with the outer cylindrical surface of the metal mandrel 1, ensuring that the spiral water cooling groove is completely sealed to form the cooling water flow channel 9. Next, fix the gas-water conversion connector 5 to the rear end of the metal mandrel 1, so that the protective gas interface 51, cooling water inlet 52 and cooling water outlet 53 are respectively connected and sealed with the corresponding protective gas inlet flow channel 71, cooling water inlet flow channel 91 and cooling water outlet flow channel 92. Finally, install the end cap 6 at the rear end opening of the metal mandrel 1 to complete the overall assembly.

[0047] All embodiments were carried out according to the assembly steps described above, and the following test conditions were used: ambient temperature 25±2℃, relative humidity ≤60%, welding current 80A, welding speed 120mm / min, shielding gas (argon) flow rate 8L / min, and cooling water temperature 20±2℃. The high-temperature deformation was measured using a laser displacement sensor to measure the radial runout value in the middle of the welding torch working section, and the surface temperature was monitored using an infrared thermal imager.

[0048] Example 1: Welding torch tip for GH3535 alloy heat exchange tube

[0049] The metal core rod 1 is made of beryllium bronze alloy, with a total length of 110mm and an outer diameter of 7mm; a protective airflow channel 7 with a diameter of 2mm is opened inside; a double spiral water-cooling groove with water inlet and outlet is opened on the outer circle, with a groove width of 1mm, a pitch of 2mm between the water inlet and outlet grooves (4mm pitch for unidirectional spiral), and a groove depth of 0.5mm.

[0050] The ceramic jacket 2 is made of zirconia ceramic with a wall thickness of 0.5mm.

[0051] The tungsten electrode 3 has a diameter of 2mm and an extension length that can be adjusted to 1.5mm; the protective gas ejection chamber 8 has a diameter of 5mm; and the cooling water circulation flow rate is set to 2L / min.

[0052] During welding, the welding torch head is installed at the end of the robot, and cooling water and shielding gas are connected. The welding torch is inserted into the φ10.5mm inner diameter pipe to a depth of 100mm. The welding program is started to perform welding. After welding 10 joints in sequence, the welding torch straightness is maintained well (the measured value of high temperature deformation is ≤0.08mm), the measured value of the welding torch surface temperature is 185℃, the weld formation is uniform, and the radiographic inspection is qualified at level I.

[0053] Example 2: Welding torch head for nickel-based alloy heat exchanger tubes

[0054] The metal core rod 1 is made of molybdenum alloy, with a total length of 120mm and an outer diameter of 8.5mm; an internal protective airflow channel 7 with a diameter of 2.4mm is opened; the outer spiral water-cooling groove has a groove width of 1.2mm, a pitch of 2.4mm between the inlet and outlet water grooves (4.8mm for unidirectional spiral), and a groove depth of 0.6mm.

[0055] The ceramic jacket 2 is made of silicon nitride ceramic with a wall thickness of 0.8 mm.

[0056] The tungsten electrode 3 has a diameter of 2.4 mm and an extension length that can be adjusted to 2 mm; the protective gas ejection chamber 8 has a diameter of 6 mm; and the cooling water circulation flow rate is set to 2.2 L / min.

[0057] During welding, cooling water and shielding gas are introduced. The welding torch is inserted into the φ12mm inner diameter pipe to a depth of 100mm. The welding program is started and welding is carried out. After welding 10 joints in sequence, the welding torch high temperature deformation is ≤0.06mm, the welding torch surface temperature is ≤190℃, the weld formation is uniform, and the radiographic inspection is qualified at level I.

[0058] In addition to being compatible with GH3535 and nickel-based alloys, this invention is also applicable to the welding of stainless steel and high-temperature alloy fine heat exchange tubes. Only minor adjustments to the tungsten electrode extension length and cooling water flow rate parameters are needed to match the welding process requirements of tubes with different materials and wall thicknesses.

[0059] The total length of the welding torch of this invention can be adjusted within the range of 100mm to 120mm, and the minimum pipe inner diameter is 10mm. The tungsten electrode extension length is adjustable within the range of 0.5mm to 3mm, and the diameter of the shielding gas ejection chamber is 3mm to 8mm. Through the composite rigid torch body and the integrated design of dual cooling, the high-temperature deformation after welding 10 joints continuously is ≤0.1mm, and it will not scratch the inner wall of the pipe. The dual cooling structure can control the surface temperature of the welding torch body below 200℃, which is more than 200℃ lower than the traditional single cooling structure. The equipment can work continuously and stably for 200 hours in accelerated life testing, while the traditional similar welding only lasts for 60 hours, increasing the service life by three times. It can stably complete high-precision inner hole welding of pipes with an inner diameter of 10mm and a depth of 100mm.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. An integrated structure for a welding torch head with a small-diameter inner bore, characterized in that, Includes a metal core rod (1) and a ceramic jacket (2); The metal core rod (1) is a component formed by integral processing of a single metal blank. A protective airflow channel (7) is provided through the metal core rod (1) along the axial direction. A continuous spiral water cooling groove is opened on the outer cylindrical surface of the metal core rod (1). The ceramic jacket (2) is coaxially fitted to the outside of the metal core rod (1) and precisely fits the metal core rod (1). The inner wall of the ceramic jacket (2) and the spiral water cooling groove form a closed cooling water channel (9). The protective airflow channel (7) and the cooling water channel (9) are separated from each other by a metal core material. The protective airflow channel (7) and the cooling water channel (9) are respectively connected to the same air-water conversion connector (5) to form two sets of media circulation channels that are not connected to each other.

2. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The metal core rod (1) is made of a material selected from beryllium bronze alloy, aluminum alloy, or molybdenum alloy.

3. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The ceramic jacket (2) is made of a material selected from zirconium oxide and silicon nitride.

4. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The spiral water cooling tank is arranged continuously along the entire working section of the metal core rod (1), and the cooling water channel (9) is completely arranged around the outer periphery of the metal core rod (1).

5. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The protective airflow channel (7) is a through-hole structure with one or more through holes. The medium transported by the protective airflow channel (7) simultaneously completes the isolation of the molten pool and the internal heat exchange of the mandrel.

6. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The front end of the metal core rod (1) is provided with a protective gas ejection chamber (8), and the front end of the protective gas flow channel (7) is connected to the protective gas ejection chamber (8).

7. The integrated structure of the small-diameter inner bore welding torch head according to claim 6, characterized in that, The ceramic jacket (2) is provided with a protective gas nozzle at its front end, and the protective gas nozzle is arranged coaxially with the protective gas ejection chamber (8).

8. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The overall coaxial straightness of the metal core rod (1) and the ceramic jacket (2) after assembly is no greater than 0.05 mm.

9. The integrated structure of the small-diameter inner bore welding torch head according to claim 1, characterized in that, The internal cooling water circulation flow rate of the cooling water channel (9) shall not be less than 2L / min.

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