Ultra-narrow gap gas metal arc welding gun and welding method

Abstract

The invention provides an ultra-narrow gap consumable electrode gas shielded welding gun and a welding method, relates to the field of welding equipment, and aims to solve the problems that a conventional welding gun with a cylindrical structure is difficult to be suitable for an ultra-narrow gap groove and a shielding gas supply mode of a common welding gun with a flat structure is difficult to meet the requirement of a high-humidity environment. The space in the shell is divided by the conductive assembly to form two shielding gas conveying channels, after entering the shell from the connecting end, shielding gas firstly flows through the front-section cavity and then enters the middle-section cavity with the larger sectional area, the pore screen of the middle section disperses and buffers airflow, reduces the flow speed and stabilizes the air pressure, and pressure fluctuation caused by airflow torrential turbulence is avoided; the protective gas flow subjected to pressure stabilization penetrates through the tail-section cavity and then is discharged from the protective gas output port, a double-side protective gas curtain surrounding the tail end of the welding wire is formed, and a molten pool area can be accurately covered.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding equipment, in particular to a super-narrow gap gas shielded welding gun and a welding method. BACKGROUND

[0002] In the key structural parts of marine engineering equipment and nuclear power equipment, a large number of super-thick steel plates (60-400mm) are needed to be welded into shape, and the weld quality directly determines the extreme environment service life, fatigue resistance and safety of the equipment. Narrow gap welding is commonly used for welding thick-walled structures. Compared with traditional multi-layer multi-pass open groove welding, narrow gap welding can greatly reduce the amount of welding wire and welding heat input by reducing the groove width, thereby suppressing welding residual stress and welding deformation, and greatly improving the welding quality.

[0003] In narrow gap welding, the smaller the groove gap, the smaller the weld metal and heat input needed, thereby saving welding materials and improving welding efficiency. However, most of the welding guns equipped with the gas shielded welding machine face the problem of insufficient adaptability in narrow gap groove scenarios, mainly manifested in geometric limitations and insufficient protection. The diameter of the traditional welding gun is usually greater than 12mm, which cannot be deeply inserted into the super-narrow gap groove (≤8mm), and there is no accessibility in the super-narrow gap groove. In addition, the traditional welding gun cannot concentrate the supply of protective gas to the narrow gap groove welding position, and insufficient groove protection can easily cause porosity, resulting in poor weld quality or even scrap of the welded part. At present, the welding gun suitable for narrow gap welding mostly adopts a flat structure, and the wire feeding channel and the protective gas supply pipeline are arranged in sequence, so that the protective gas range can move with the welding position of the welding wire, improving the protection of the molten pool position. However, for marine engineering equipment and nuclear power equipment welding, they are mostly located near the coast, with high humidity. Simply using the protective gas supply pipeline located in the welding gun to deliver protective gas cannot provide sufficient protective gas to the molten pool position, and it is difficult to disperse the humid air near the molten pool, resulting in problems such as increased porosity, increased risk of welding cracks, poor welding forming, and decreased mechanical properties during welding. When increasing the protective gas supply pressure to improve the protective gas coverage range to solve this problem, the high protective gas flow will disturb the arc during welding, causing the molten pool to deviate and the forming effect to be poor, making it difficult to achieve the required weld quality. SUMMARY

[0004] The purpose of the present application is to provide an ultra-narrow gap gas shielded welding gun and welding method to solve the problems in the prior art, which is configured with a shell and a conductive assembly, the space in the shell is separated by the conductive assembly to form two protective gas conveying channels, the protective gas enters the shell from the connecting end, flows through the front cavity, and then enters the middle cavity with a larger cross-sectional area, the gas holes in the gas hole screen in the middle cavity disperse and buffer the gas flow, reduce the flow rate and stabilize the gas pressure, and avoid pressure fluctuations caused by turbulent gas flow; the stabilized protective gas flow passes through the end cavity and is discharged from the protective gas outlet, forming a double-sided protective gas curtain around the end of the welding wire, which can accurately cover the molten pool area; the double-channel gas flow forms a superimposed protection effect near the molten pool.

[0005] The first purpose of the present application is to provide an ultra-narrow gap gas shielded welding gun, which adopts the following scheme: Comprise: The shell is flat, and at least three cavities are sequentially arranged in the shell, one end of the shell is formed as a connecting end for connecting to a welding machine, the other end is a cavity opening, the cross-sectional area of the middle cavity is larger than that of the two end cavities, and a gas hole screen is arranged in the middle cavity; The conductive assembly is located in the shell and forms a wire passage inside, one end of the conductive assembly extends to the connecting end, the other end passes through the cavity opening and separates the cavity opening into two protective gas outlets, and the cavities on both sides of the conductive assembly form two protective gas conveying channels connected to the protective gas outlets.

[0006] Further, the cavities in the shell are divided into a front cavity, a middle cavity and an end cavity arranged in sequence, and transition cavities with gradually changing cross-sectional areas are arranged between the front cavity and the middle cavity and between the middle cavity and the end cavity.

[0007] Further, along the direction of protective gas flow, the protective gas conveying channel comprises multiple channels with changing cross-sectional areas.

[0008] Further, the shell is of an integrated structure, the middle cavity is provided with an annular mounting groove for mounting the gas hole screen, and the gas hole screen is provided with a through hole for the conductive assembly to pass through, and the gas hole screen outside the through hole is arrayed with gas holes.

[0009] Further, the connecting end of the shell is provided with a positioning key groove parallel to the axis of the shell to constrain the direction of connecting to the welding machine.

[0010] Further, the conductive assembly comprises a conductive rod and a conductive nozzle, the conductive rod and the conductive nozzle are butt-jointed in the middle cavity, the conductive rod extends to the connecting end, and the conductive nozzle passes through the cavity opening.

[0011] Further, the conductive rod and the conductive nozzle are detachably connected, the conductive nozzle is provided with a plurality of, and the internal wire supply channels of different conductive nozzles are configured with different sizes.

[0012] Further, the cross section of the shell is rectangular, and the two protective gas outlets are symmetrically distributed relative to the wire supply channel axis.

[0013] Further, the upper end of the shell is provided with an axial positioning key groove structure to ensure a unique correct installation direction.

[0014] The second object of the present application is to provide a method for ultra-narrow gap gas shielded welding, which utilizes the ultra-narrow gap gas shielded welding gun provided in the first object, comprising: The welding gun is connected to the welding machine through the connecting end of the shell, the welding wire is delivered to the front end through the wire supply channel in the conductive assembly, and the protective gas enters the internal cavity of the shell from the connecting end; The protective gas first enters the front cavity of the shell, and then flows into the middle cavity with a larger cross-sectional area. The gas hole screen in the middle cavity plays a role in shunting and stabilizing the gas pressure. After the gas is stabilized, it enters the two protective gas delivery channels on both sides of the conductive assembly, and is finally sprayed out through the two protective gas outlets separated by the conductive assembly, forming a ring-shaped or double-sided protective gas curtain at the end of the welding wire and the welding area; After the conductive assembly is powered on, an arc is generated between the conductive assembly and the workpiece, the welding wire and the base material form a molten pool, and the double-path protective gas continuously isolates the air, completing the welding process of the ultra-narrow gap.

[0015] Further, during the welding process, laser auxiliary welding is applied.

[0016] Compared with the prior art, the present application has the advantages and positive effects that: In view of the problem that the protective gas supply mode of the existing flat structure welding gun cannot meet the needs of high humidity environment, the shell and the conductive assembly are configured, the space in the shell is divided by the conductive assembly to form two protective gas delivery channels, the protective gas enters the shell from the connecting end, first flows through the front cavity, and then enters the middle cavity with a larger cross-sectional area. The gas hole screen in the middle cavity disperses and buffers the gas flow, reduces the flow rate and stabilizes the gas pressure, avoiding pressure fluctuations caused by turbulent gas flow; after the stabilized protective gas flow passes through the end cavity, it is discharged from the protective gas outlet, forming a double-sided protective gas curtain around the end of the welding wire, which can accurately cover the molten pool area; the double-path gas flow forms a superimposed protection effect near the molten pool. Compared with the narrow delivery gas pipe, the protective gas delivery channel formed by the internal structure of the shell has a larger cross-sectional area, which reduces the gas flow resistance and buffers the gas flow speed to ensure the delivery gas flow. Without relying on excessively high gas pressure, the effective protection range can be expanded, which can not only disperse the surrounding humid air, but also avoid the disturbance of single-path high-pressure gas flow to the arc, ensuring the stability of the arc and the formation of the molten pool.

[0017] The conductive assembly is composed of a conductive rod and a conductive nozzle, which are connected in the middle segment cavity to form a through wire feeding channel. The conductive rod extends to the connection end, which is responsible for connecting with the current output end of the welding machine and conducting current; the conductive nozzle passes through the cavity opening and directly acts on the welding area, and the front end outlet cooperates with the welding wire to form a stable arc. The segmented design not only facilitates the replacement of conductive nozzles of different specifications according to welding requirements, but also separates and optimizes the current conduction and welding wire guiding functions. The conductive rod can be made of low-resistance conductive material, and the conductive nozzle can be made of wear-resistant material, and a wire feeding channel matched with the diameter of the welding wire is arranged to improve the guiding accuracy.

[0018] The shell cross section adopts a rectangular design, which is more suitable for the flat space of the ultra-narrow gap than the circular cross section. The short side dimension can be controlled within 6 mm, ensuring that the welding torch can penetrate into the ultra-narrow groove. Two protective gas outlets are symmetrically distributed relative to the wire feeding channel axis, so that the two-sided protective gas curtain formed by the ejected gas forms a mirror-symmetrical structure. The gas flow covers the molten pool area more evenly, avoiding the blind area caused by the deflection of one-sided protective gas. The symmetrical distribution of the protective gas outlet combined with the guidance of the rectangular shell can make the protective gas flow along the groove wall in the narrow groove, further expanding the protection range, especially suitable for full-range protection during deep groove welding. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings accompanying the specification of this application form a part thereof, serve to further provide a further understanding of the application, and together with the description of the exemplary embodiments of the application, serve to explain the application, and do not constitute an improper limitation of the application.

[0020] Figure 1 A schematic view of the ultra-narrow gap gas shielded welding gun in one or more embodiments of the application.

[0021] Figure 2 A sectional view of the ultra-narrow gap gas shielded welding gun in one or more embodiments of the application.

[0022] Figure 3 A structural schematic view of the ultra-narrow gap gas shielded welding gun in one or more embodiments of the application.

[0023] Figure 4 A schematic view of the conductive assembly in one or more embodiments of the application.

[0024] Figure 5 A schematic view of the gas hole screen in one or more embodiments of the application.

[0025] Figure 6 A schematic view of the ultra-narrow gap gas shielded welding gun during welding in one or more embodiments of the application.

[0026] Figure 7A schematic diagram of a laser-assisted welding of a super-narrow gap GMAW gun in one or more embodiments of the present application.

[0027] Wherein, 1, welding wire; 2, shell; 3, shielding gas outlet; 4, front cavity; 5, middle cavity; 6, end cavity; 7, shielding gas delivery channel; 8, conducting nozzle; 9, conducting rod; 10, positioning key groove; 11, ring-shaped mounting groove; 12, gas hole screen; 13, via hole; 14, gas hole; 15, super-narrow gap groove; 16, electric arc; 17, laser beam. DETAILED DESCRIPTION

[0028] Embodiment 1 In one exemplary embodiment of the present application, as shown in Figures 1-7 , a super-narrow gap GMAW gun is provided.

[0029] In the welding scene of key structural parts of offshore engineering equipment and nuclear power equipment, the super-narrow gap (≤8mm) welding needs to face the challenge of high humidity environment. It is difficult for the shielding gas to effectively isolate the humid air. In a high humidity environment, it is difficult to form a shielding gas curtain with sufficient coverage and stability by using a flat structure welding gun combined with the shielding gas supply mode of the internal shielding gas delivery pipe. It cannot disperse the humid air near the molten pool, which is easy to cause pores and cracks, and cannot be solved by simply increasing the gas pressure, which will disturb the electric arc 16 and cause the molten pool to deviate. Based on this, the present embodiment provides a super-narrow gap GMAW gun, which is configured with a shell 2 and a conducting assembly. The shell 2 is divided into two shielding gas delivery channels 7 by the conducting assembly. After the shielding gas enters the shell 2 from the connecting end, it flows in the shielding gas delivery channel 7 with an enlarged cross-sectional area formed by the shell 2. Compared with the additional arrangement of the shielding gas delivery pipe, the cross-sectional area is enlarged, and multiple sections with varying cross-sectional areas are configured to realize the rectification of the shielding gas and form a double-sided shielding gas curtain around the end of the welding wire 1, which can accurately cover the molten pool area, exclude the high humidity air near the molten pool, and improve the protection effect.

[0030] As shown in Figures 1-6 , the super-narrow gap GMAW gun includes a shell 2 and a conducting assembly. The conducting assembly forms a wire feeding channel for the welding wire 1 to pass through inside the conducting assembly, and the conducting assembly is installed in the shell 2.

[0031] The shell 2 is in a flat structure as a whole, which is adapted to the geometric space of the super-narrow gap groove 15, ensuring that the welding gun can penetrate into a narrow area ≤8mm; the inner cavity of the shell 2 is divided into at least three cavities that are sequentially connected. In this embodiment, three cavities are taken as an example, which are sequentially connected, the cross-sectional area of the middle section is larger than that of the two ends, and the gas hole screen 12 is installed in the middle cavity.

[0032] In other optional embodiments, the inner cavity of the shell 2 can be divided into four, five or more sections, and in this case, multiple intermediate sections can be arranged, and the cross-sectional areas of different intermediate sections are different, so as to adjust the protective gas flow multiple times through the intermediate sections, so as to meet the requirements of the required conveying flow and stability.

[0033] The conductive assembly penetrates the shell 2, and the cavity openings are divided into two protective gas outlets 3, and two independent protective gas conveying channels 7 are formed on both sides of the assembly; the inside of the conductive assembly is provided with a wire conveying channel, which simultaneously bears the conductive function, realizing the integration of wire 1 conveying and current conduction.

[0034] The flat shell 2 design significantly reduces the transverse size of the welding gun, enabling it to fit into a ≤8mm ultra-narrow groove 15 space, breaking through the geometric limitations of traditional round or large-diameter welding guns, ensuring that the front end of the welding gun can be deeply inserted into the groove 15, and effectively reaching the welding position. After the protective gas enters the shell 2 from the connecting end, it first flows through the front section cavity, and then enters the intermediate section cavity with a larger cross-sectional area. The gas holes 14 of the intermediate section disperse and buffer the gas flow, reduce the flow rate and stabilize the gas pressure, avoiding pressure fluctuations caused by turbulent gas flow; the stabilized protective gas passes through the two conveying channels on both sides of the conductive assembly and is directed out from the two protective gas outlets 3. Since the outlets are separated by the conductive assembly on both sides of the wire 1, a double-sided protective gas curtain is formed around the end of the wire 1, which can accurately cover the molten pool area.

[0035] The double-path gas flow forms a superimposed protection effect near the molten pool, without relying on excessively high gas pressure to expand the effective protection range, which can not only disperse the surrounding humid air and reduce the invasion of hydrogen and oxygen, but also avoid the disturbance of single-path high-pressure gas flow to the electric arc 16, ensuring the stability of the electric arc 16 and the formation of the molten pool. The double-path protective gas curtain, combined with the pressure stabilizing effect of the gas holes 14 in the gas hole screen 12, significantly enhances the protection capability of the molten pool without disturbing the electric arc 16, effectively isolates the humid air, and reduces defects such as gas holes and cracks; stable electric arc 16 and sufficient protection make the weld form uniform, and the mechanical properties are guaranteed, which is especially suitable for high-precision welding requirements such as marine engineering and nuclear power equipment in high-humidity environments; without excessive reliance on high-pressure protection, the welding interruption or rework caused by gas flow disturbance is reduced, and the ultra-narrow gap itself can reduce the amount of filler metal, further improving welding efficiency.

[0036] To solve the core problem that the protective gas of the flat structure welding gun cannot effectively isolate the humid air in high-humidity environments, through the cooperative configuration of the shell 2 and the conductive assembly, a protective gas supply system that can balance gas flow, gas pressure stability and protection range is constructed. The separation of the conductive assembly to the space in the shell 2 forms a double-path channel, combined with the gas pressure regulating ability of the multi-section cavity of the shell 2, the molten pool area is efficiently and stably protected without relying on high-pressure gas flow.

[0037] The conductive assembly is arranged longitudinally in the shell 2 and penetrates from the connecting end to the cavity opening, and naturally forms two protective gas conveying channels 5 penetrating through the shell 2 at both ends between the inner wall of the shell 2. The protective gas conveying channel 7 is not only locally present at the end of the shell 2, but also extends from the front cavity to the end cavity, wrapping the conductive assembly throughout, ensuring that the protective gas is stably conveyed along a fixed path during the flow process, avoiding airflow turbulence caused by intermittent channels.

[0038] Compared with the narrow gas conveying pipe independently arranged in the traditional flat welding gun, the channel naturally formed by the internal structure of the shell 2 has a larger cross-sectional area: on the one hand, it can reduce the airflow resistance and ensure sufficient gas flow per unit time to meet the gas demand for dispersing humid air in a high-humidity environment; on the other hand, the larger cross-sectional area can buffer the airflow velocity and reduce local turbulence, laying a foundation for subsequent stable pressure.

[0039] The flow process of the protective gas is accompanied by precise pressure and flow rate regulation. After the protective gas enters from the connecting end, it is first preliminarily gathered in the front cavity. Due to the smaller cross-sectional area of the front cavity, the airflow forms a preliminary guide at this stage and flows to the middle cavity. The middle cavity, as the core control area, has a larger cross-sectional area than the two ends, causing the flow rate to naturally decrease after entering. In combination with the gas holes 14 on the built-in gas hole screen 12, the concentrated airflow is dispersed into multiple fine streams, achieving the effects of flow splitting, buffering, and pressure stabilization, which not only eliminates pressure fluctuations caused by turbulent airflow, but also keeps the pressure stable before entering the end cavity. The protective gas after stable pressure flows into the end cavity along the double-channel, and at this time, the cross-sectional area of the channel returns to a smaller size. The airflow, while maintaining stable pressure, has a moderately increased flow rate, which is still below the high-pressure disturbance threshold, and finally is sprayed out from the two protective gas outlets 3.

[0040] After the double-channel airflow is sprayed out from the two outlets at the opening, the outlets are naturally located on both sides of the welding wire 1 due to the fact that the channel wraps the conductive assembly throughout, forming a symmetrical double-sided protective gas curtain.

[0041] The gas curtain is centered on the end of the welding wire 1 and diffuses and superimposes towards the molten pool area, forming a protective area with a larger range and more uniform density, effectively covering the molten pool and the heat-affected zone. Since the pressure is kept moderate after being stabilized in the middle section, high pressure is not required. The airflow can not only disperse the surrounding humid air and prevent water vapor and oxygen from invading the molten pool, but also will not disturb the arc 16 due to excessively high flow rate, ensuring stable combustion of the arc 16 and uniform molten pool formation.

[0042] It specifically addresses the core challenge of high humidity environments. The large cross-sectional area channel ensures airflow, meeting the requirement of "replacing humid air with sufficient gas" in high humidity environments. The combination design of the multi-segment cavity and the air sieve 12 avoids the drawbacks of high-pressure airflow and achieves effective protection under stable air pressure. The double-sided air curtain surrounds the welding wire 1 and the molten pool, providing more comprehensive coverage. Compared with a single-path shielding gas, it is more adaptable to the complex space within the narrow bevel 15, ensuring that the molten pool area is always protected by an inert atmosphere.

[0043] In high-humidity environments (such as marine and nuclear power engineering), it can solve the problems of porosity and cracks caused by insufficient protection of traditional welding torches, and avoid arc disturbance caused by high-pressure airflow, so as to achieve high-quality and stable output of ultra-narrow gap welding.

[0044] The housing 2 is integrally formed using additive manufacturing to eliminate interface errors and sealing risks caused by assembling multiple parts. The middle section cavity 5 is machined with an annular mounting groove 11 for mounting the air vent screen 12, ensuring it is perpendicular to the cavity axis and covers the cross-section of the middle section cavity 5, providing a structural basis for airflow dispersion and pressure stabilization. The upper end of the housing 2 has a positioning keyway structure 10 parallel to the axial direction of the housing 2 to ensure a uniquely correct installation orientation. Figure 5 As shown, the array of air holes 14 on the air hole screen 12 can evenly divide the concentrated protective gas into multiple fine streams, which not only reduces the local airflow velocity, but also makes the gas pressure more evenly distributed throughout the middle section cavity, avoiding pressure fluctuations caused by airflow impact.

[0045] The pore screen 12 is provided with through holes 13 for conductive components to pass through. The pore screen 12 forms radial support for the conductive components, reducing component displacement caused by vibration during welding. In addition, the gap between the conductive components and the pore screen 12 can be sealed by arranging gaskets, applying glue, etc., to prevent the protective gas from flowing directly through the gap without diversion, and to ensure that all airflow passes through the pressure stabilization treatment of the pore screen 12.

[0046] like Figure 2 As shown, the inner cavity of the shell 2 is subdivided into a front cavity 4, a middle cavity 5, and a final cavity 6, with adjacent cavities connected by transition cavities of gradually changing cross-sectional area, allowing for a smooth transition of the protective gas during flow. When entering the middle cavity 5 from the front cavity 4, the cross-sectional area gradually increases, and the airflow velocity slowly decreases to avoid turbulence caused by sudden expansion; when entering the final cavity 6 from the middle cavity 5, the cross-sectional area gradually decreases, and the airflow velocity steadily increases, accumulating kinetic energy for the final ejection to form a protective gas curtain.

[0047] As the protective gas conveying passage 7 is formed through the shell 2, the protective gas conveying passage 7 also forms a plurality of sections with varying cross-sectional areas along the direction of the flow of the protective gas, echoing the gradual change feature of the cavity. The coordinated variable cross-section structure of the cavity and the passage can control the flow state throughout the process: the front passage guides the flow to converge, the middle passage cooperates with the air hole screen 12 to achieve stable pressure, and the last passage directs the stable flow to the output port, ensuring that the whole process from entering to spraying of the protective gas is in a controllable state.

[0048] As shown in Figure 4 The conductive assembly is composed of a conductive rod 9 and a conductive nozzle 8, which are connected at the middle section cavity to form a through wire feeding passage. The conductive assembly is attached to a set of opposite inner walls of the shell 2, so that after installation, the internal cavity of the shell 2 can be divided into two independent protective gas conveying passages 7 for conveying protective gas. The conductive rod 9 extends to the connection end, responsible for connecting with the current output end of the welding machine and conducting current; the conductive nozzle 8 passes through the cavity opening and directly acts on the welding area, and the front end outlet cooperates with the welding wire 1 to form a stable arc 16. The segmented design not only facilitates the replacement of different specifications of the conductive nozzle 8 according to welding requirements, but also separates and optimizes the current conduction and welding wire 1 guiding functions. The conductive rod 9 focuses on low-resistance conduction, using low-resistance conductive materials, while the conductive nozzle 8 focuses on wear resistance and welding wire 1 guiding accuracy, and the conductive nozzle 8 is configured with a wire feeding passage matching the diameter of the welding wire 1. The shell 2 is made of high-temperature-resistant alloy die steel, the thickness of the shell 2 is 0.5mm, and the outer surface of the shell 2 is sprayed with a layer of high-temperature-resistant and anti-splashing insulating material (alumina-based composite ceramic material) to prevent the shell 2 from being burned and to prevent arc wiping between the shell 2 and the workpiece.

[0049] The detachable connection of the conductive rod 9 and the conductive nozzle 8, combined with the configuration of the conductive nozzle 8 of various sizes of wire feeding passages, enables the welding torch to adapt to welding wires 1 of different diameters (such as 1.2mm, 1.6mm, etc.), improving the versatility of the equipment. At the same time, as a consumable part, the conductive nozzle 8 can be replaced separately to reduce maintenance costs and avoid waste caused by replacing the entire conductive assembly.

[0050] The shell 2 adopts a rectangular cross-section design, which is more suitable for ultra-narrow gap flat spaces than a circular cross-section. The short side dimension can be controlled within 6mm, ensuring that the welding torch can penetrate into the ultra-narrow groove 15. The two protective gas outlets 3 are symmetrically distributed relative to the wire feeding passage axis, so that the mirror-symmetric structure of the sprayed double-sided protective gas curtain is formed, the flow coverage in the molten pool area is more balanced, and the protective blind area caused by the deflection of single-sided protective gas is avoided. The combination of symmetric design and the corner guidance of rectangular shell 2 can make the protective gas flow along the wall surface of the narrow groove 15 in the narrow groove 15, further expanding the protection range, especially suitable for full-range protection during large-depth groove 15 welding.

[0051] The protective gas enters the front cavity from the connecting end, flows along the channels on both sides of the conductive assembly, and slowly enters the middle cavity with a larger cross-sectional area through the transition cavity. At this time, the gas flow impacts the array of gas holes 14 of the gas hole screen 12 and is dispersed into dozens of fine streams, forming a uniformly distributed low-pressure gas flow field (gas pressure fluctuation ≤5%) in the second cavity. The stabilized gas flow passes through another transition cavity into the end cavity, and the gradually decreasing cross-sectional area of the channel allows the gas flow velocity to smoothly increase, and finally the gas flow is ejected from the two symmetrical output ports, forming a balanced double-sided gas curtain. Throughout the process, the combination of the variable cross-section cavity and the gas hole screen 12 completely solves the problem of turbulent gas flow and unstable pressure in traditional welding guns, laying the foundation for effective protection in high humidity environments.

[0052] The short side dimension of the rectangular cross-section shell 2 can be customized according to the width of the groove 15 (e.g., 6-8 mm), which matches the flat overall structure, allowing the welding gun to penetrate along the axis of the groove 15. The lengthwise arrangement of the conductive assembly ensures that the wire feeding channel is always in the center of the shell 2, avoiding interference with the walls of the groove 15; the symmetrically distributed protective gas outlets 3 are close to the walls of the groove 15 on both sides, and the ejected gas flow can climb along the walls, covering the molten pool area at the root of the groove 15, solving the problem that traditional welding guns cannot penetrate due to their bulky structure and protective gas cannot reach the bottom of the groove 15.

[0053] The detachable conductive rod 9 and the conductive nozzle 8 allow a single welding gun to adapt to different wire 1 diameters by replacing the conductive nozzle 8, meeting the welding needs of different thicknesses of base materials.

[0054] In this embodiment, the welding gun shell 2 is used to deliver coaxial protective gas into a narrow gap groove 15, and the width of this part of the welding gun is reduced from 10 mm to 6 mm, allowing it to be applied to ultra-narrow gap grooves 15 with a width of 7 mm and above. The 6 mm wide welding gun has a length of 90 mm, allowing it to be applied to ultra-narrow gap grooves 15 with a depth of 80 mm and below, as shown in Figure 2 and Figure 3 .

[0055] The shell 2 of the welding gun has an overall structure of being wider at the top and narrower at the bottom, with a width of 10 mm at the top and a width of 6 mm at the bottom. The width is reduced from 10 mm to 6 mm in the middle transition part, allowing the protective gas to converge in the shell 2 towards the middle. The flow rate of the protective gas increases at the bottom of the shell 2 due to the gas convergence effect, improving the protection effect on the welding position of the ultra-narrow gap groove 15, as shown in Figure 2 and Figure 3 .

[0056] The array of air holes and symmetrical output ports control the flow difference of the double-sided air curtain within 3%, and the inert gas coverage rate in the molten pool area is increased to more than 95%, effectively isolating water vapor and oxygen in the high-humidity environment, and the porosity is reduced by 60%-80% compared with the traditional welding gun. The combination of the rectangular cross-section shell 2 and the thin diameter conducting nozzle 8 enables the welding gun to be adapted to the ultra-narrow groove 15 with a width of 5 mm at the minimum, and the application range is expanded by 30% compared with the existing flat welding gun, meeting the narrow gap welding requirements of thick-walled structures in ocean engineering. The configuration of various sizes of the conducting nozzle 8 enables the welding gun to be compatible with the welding wire 1 with a diameter of 0.8-2.0 mm, and the stable airflow control can realize high-quality welding on carbon steel, low-alloy steel, stainless steel and other materials in a high-humidity environment.

[0057] Example 2 In another typical embodiment of the present application, as shown in Figures 1-7 a method for ultra-narrow gap gas metal arc welding is given, using the ultra-narrow gap gas metal arc welding gun in example 1.

[0058] A method for ultra-narrow gap gas metal arc welding, comprising: The welding gun is connected to the welding machine through the connecting end of the shell 2, the welding wire 1 is delivered to the front end through the wire supply channel inside the conducting assembly, and the shielding gas enters the internal cavity of the shell 2 from the connecting end; The shielding gas first enters the front cavity 4 of the shell 2, and then flows into the middle cavity 5 with a larger cross-sectional area. The air hole screen 12 in the middle cavity 5 plays a role in shunting and pressure stabilizing. After the stabilized gas is stabilized, it enters the two shielding gas delivery channels 5 on both sides of the conducting assembly, and is finally sprayed out through the two shielding gas output ports 3 separated by the conducting assembly, forming a ring-shaped or double-sided shielding gas curtain at the end of the welding wire 1 and the welding area; After the conducting assembly is powered on, an arc 16 is generated between the conducting assembly and the workpiece, the welding wire 1 and the base material are melted to form a molten pool, and the double-path shielding gas continuously isolates air to complete the ultra-narrow gap welding process.

[0059] During the welding process, a laser beam 17 acts on the molten pool position by applying an external laser-assisted welding.

[0060] Specifically, the method for ultra-narrow gap gas metal arc welding is described in combination with example 1 and Figures 1-7 .

[0061] After the welding gun is connected to the welding machine through the connecting end, a power supply, a conducting assembly, a welding wire 1, and a workpiece form a conducting loop, and a gas source, a shell 2 cavity, a shielding gas delivery channel 7, and a shielding gas output port 3 form a gas delivery path. The welding wire 1 is continuously fed through the wire supply channel of the conducting assembly, and the wire feed speed is linked with the welding machine current and voltage parameters to ensure that the welding wire 1 melting rate matches the molten pool formation rhythm.

[0062] AsFigure 7 As shown, when the laser is applied, the laser beam 17 is focused in front of the molten pool area, and the laser beam 17 and the electric arc 16 form a “composite heat source”, which enhances the penetration ability to the bottom of the ultra-narrow gap and the sidewall, and avoids the defects of incomplete fusion; the photo-induced plasma formed by the laser can provide a low-resistance path for the combustion of the electric arc 16, reduce the ignition voltage of the electric arc 16, make the electric arc 16 more stable in a high-humidity environment, reduce the defects of pores, incomplete fusion and the like caused by the instability of the electric arc, and is especially suitable for the scene where there may be oil stains or small rusts on the surface of the groove 15.

[0063] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement and the like within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An ultra-narrow gap gas metal arc welding torch, characterized by, The utility model relates to a welding torch, comprising: a shell in a flat shape, the shell is provided with at least three cavities in sequence, one end of the shell is provided with a connecting end for connecting a welding machine, the other end is provided with a cavity opening, the cross-sectional area of the middle cavity is larger than that of the two end cavities, and a gas hole screen is arranged in the middle cavity; a conductive assembly is arranged in the shell and forms a wire channel inside, one end of the conductive assembly extends to the connecting end, the other end passes through the cavity opening and divides the cavity opening into two protective gas outlets, and the two cavities on the two sides of the conductive assembly form two protective gas conveying channels connected with the two protective gas outlets.

2. The ultra-narrow gap gas metal arc welding torch of claim 1, wherein, The cavities in the shell are divided into a front cavity, a middle cavity and a rear cavity arranged in sequence, and transition cavities with gradually changing cross-sectional areas are arranged between the front cavity and the middle cavity and between the middle cavity and the rear cavity.

3. The ultra-narrow gap flux cored gas shielded welding gun of claim 2, wherein, The protective gas conveying channels include channels with changing cross-sectional areas in the direction of the flow of the protective gas.

4. The ultra-narrow gap flux cored gas shielded welding gun of claim 2 or 3, wherein, The shell is of an integrated structure, the middle cavity is provided with an annular mounting groove for mounting the gas hole screen, the gas hole screen is provided with through holes for the conductive assembly to pass through, and the gas hole screen outside the through holes is provided with gas holes arranged in an array.

5. The ultra-narrow gap flux cored gas shielded welding gun of claim 1, wherein, The connecting end of the shell is provided with a positioning key groove parallel to the axis of the shell to constrain the direction of the welding machine.

6. The ultra-narrow gap flux cored gas shielded welding gun of claim 1, wherein, The conductive assembly includes a conductive rod and a conductive nozzle, the conductive rod and the conductive nozzle are connected at the middle cavity, the conductive rod extends to the connecting end, and the conductive nozzle passes through the cavity opening.

7. The ultra-narrow gap flux cored gas shielded welding gun of claim 7, wherein, The conductive rod and the conductive nozzle are detachably connected, the conductive nozzle is provided with a plurality of conductive nozzles, and the internal wire channels of the different conductive nozzles are configured to have different sizes.

8. The ultra-narrow gap flux cored gas shielded welding gun of claim 1, wherein, The cross section of the shell is rectangular, and the two protective gas outlets are symmetrically distributed relative to the axis of the wire channel.

9. A method of ultra-narrow gap shielded metal arc welding using the ultra-narrow gap shielded metal arc welding gun according to any one of claims 1 to 8, characterized in that, The utility model relates to a welding torch, comprising: a welding torch is connected to a welding machine through the connecting end of the shell, a welding wire is conveyed to the front end through the wire channel inside the conductive assembly, and a protective gas enters the cavity inside the shell from the connecting end; the protective gas first enters the front cavity of the shell and then flows into the middle cavity with a larger cross-sectional area. The gas hole screen in the middle cavity plays a role in shunting and pressure stabilizing the gas, the pressure-stabilized gas enters the two protective gas conveying channels on the two sides of the conductive assembly, and is finally sprayed out through the two protective gas outlets divided by the conductive assembly, forming a ring-shaped or double-sided protective gas curtain at the end of the welding wire and the welding area; an electric arc is generated between the conductive assembly and a workpiece after the conductive assembly is powered on, the welding wire and the base material are melted to form a molten pool, and the double-path protective gas continuously isolates air to complete the welding process of the ultra-narrow gap.

10. The method of ultra-narrow gap gas metal arc welding of claim 9, wherein, In the welding process, laser is used for auxiliary welding.

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