Coaxial nozzle for laser welding

Abstract

The utility model discloses a coaxial nozzle for laser welding, which comprises a nozzle seat, a flow guide body and a spray head. The upper end of the nozzle seat is provided with a connecting piece. The flow guide body is provided with a flow guide core in the center, and the center is provided with a laser guide core and coaxial with the taper mouth of the spray head. A fixed partition ring is arranged on the inner side of the flow guide body. A shunt hole is formed on the partition ring, and a shunt plate and an annular collecting groove are arranged to form a converging channel gradually narrowing from top to bottom. A cyclone plate is arranged along the outer periphery of the flow guide core on the inner side of the partition ring. The main airflow flows downward through the spiral flow channel, mixes with the converging branch airflow upstream of the taper mouth and is coaxially sprayed out. The structure realizes isobaric distribution and low-turbulence rectification, forms a near-axis symmetrical high-speed beam, suppresses plasma shielding and splashing back, stabilizes the melting depth and forming, provides effective blowing for the protective lens, and improves the welding quality and service life.

Description

Technical Field

[0001] This utility model relates to the field of laser welding equipment technology, specifically a coaxial nozzle for laser welding. Background Technology

[0002] Common nozzle types include straight-tube orifice nozzles, conical converging nozzles, annular coaxial nozzles, and nozzles that introduce swirling flow near the nozzle. These structures generally deliver the protective gas to the workpiece via a single path, or perform simultaneous spraying and mixing of the two gases near the nozzle end. In practical applications, the nozzle-workpiece gap, beam focal point position, and nozzle geometry are highly sensitive to the velocity profile and turbulence intensity of the airflow: when there is a lack of pressure equalization and rectification units upstream or the circumferential distribution is uneven, the circumferential pressure difference at the nozzle increases, leading to jet eccentricity, uneven velocity distribution, and the appearance of backflow vortices; while increasing local shear force, swirling nozzles easily generate lateral disturbances downstream of the nozzle, causing surface fluctuations in the molten pool and spatter rewind; in scenarios involving high-reflectivity materials such as aluminum and copper, or deep penetration welding of thick plates, the metal vapor density and plasma intensity increase, making it difficult for conventional single-hole or simple conical nozzles to maintain a low-turbulence, near-axisymmetric high-speed beam upstream of the focal point, resulting in problems such as decreased energy coupling efficiency, unstable penetration depth, and surface forming defects. In addition, strong mixing near the nozzle can significantly increase turbulence and shear noise, compromising the integrity of the coaxial beam. When there is no effective positive pressure purging path in front of the protective lens, dust and splashes are more likely to rise and adhere, increasing the frequency of cleaning and shortening the life of optical components.

[0003] In summary, existing laser welding nozzles generally suffer from the following technical shortcomings: First, insufficient upstream pressure equalization and circumferential distribution capabilities make it difficult to form a stable, low-turbulence, axisymmetric beam upstream of the nozzle. Second, strong mixing or excessive swirling near the nozzle region easily leads to backflow and gas flow deflection, affecting molten pool stability and weld formation. Third, they are sensitive to assembly errors such as nozzle-workpiece gap and focal point position, resulting in a narrow process window and low parameter tolerance. Fourth, the optical window purging and end-point protection effects are limited, requiring frequent maintenance and exhibiting insufficient stability. Therefore, there is an urgent need for a coaxial nozzle structure that can achieve isobaric distribution and gradual beam convergence upstream of the nozzle, output a near-axisymmetric, low-turbulence, high-speed gas flow while being coaxial with the laser beam, and simultaneously ensure lens purging and long-term stability. Utility Model Content

[0004] This utility model aims to solve one of the technical problems existing in the prior art or related technologies.

[0005] Therefore, the technical solution adopted by this utility model is as follows: a coaxial nozzle for laser welding, comprising: a nozzle seat, the upper end of which is provided with a connector for connecting to a laser welding head; a guide fluid installed inside the nozzle seat; and a nozzle installed at the lower end of the nozzle seat. A guide core is provided inside the guide fluid, and a laser guide core is provided at the center of the guide core, the laser guide core being coaxially arranged with the conical opening of the nozzle. A spacer ring is fixedly installed inside the guide fluid, the surface of the spacer ring is provided with multiple flow-dividing holes and communicates with the gas channel on the outer periphery of the guide core, and an annular collecting groove is opened on the top surface of the nozzle. A spiral swirl plate is arranged along the outer periphery of the guide core on the inner side of the spacer ring, and the main airflow flows downward through the spiral flow channel formed by the swirl plate. Several flow-dividing plates are provided between the spacer ring and the inner wall of the guide fluid, each flow-dividing plate being arranged opposite to the corresponding flow-dividing hole, thereby confining part of the airflow along the outer surface of the spacer ring and the annular collecting groove on the top surface of the nozzle into a gradually contracting converging flow channel from top to bottom, and mixing with the main airflow upstream of the conical opening before being coaxially ejected.

[0006] Technical effect: Through the coupled arrangement of "spiral main stream + circumferentially distributed convergent branch", a near-axisymmetric, low-turbulence high-speed beam is formed upstream of the cone, which significantly suppresses plasma shielding and splash rollback, stabilizes melting depth and forming, and achieves effective positive pressure purging of the protective lens.

[0007] In a preferred example, the diversion holes are further configured such that they are evenly spaced along the circumference, and the hole shape is a slit or a rectangular window, with its long side arranged along the circumference.

[0008] Specific technical effects: Equal spacing and circumferential arrangement along the long side reduce the circumferential pressure difference at the inlet of each convergence channel, reduce flow skew and secondary vortices, and help obtain a consistent velocity profile and lower turbulence intensity.

[0009] In a preferred example, the configuration is further configured such that an annular pressure equalization chamber is formed between the septum and the top surface of the nozzle, and the axial height of the pressure equalization chamber matches the opening height of the diversion orifice.

[0010] Specific technical effects: Secondary pressure equalization makes the inlet static pressure of each beam channel more consistent, reduces the jet eccentricity caused by circumferential unevenness, and improves beam stability and repeatability.

[0011] In a preferred example, the flow divider is further configured such that its lower end smoothly transitions to the annular collection groove on the top surface of the nozzle, and together with the outer surface of the partition ring, defines a top-to-bottom tapering flow channel.

[0012] Specific technical effects: The tapered and smooth transition suppresses boundary layer separation and local backflow, increases axial dynamic pressure and reduces turbulence intensity, and ensures the axisymmetry of the beam at the cone opening.

[0013] In a preferred example, the laser guide is further configured as follows: the laser guide is a component made of optical fiber or borosilicate glass, used to guide laser transmission and maintain coaxiality with the conical aperture.

[0014] Specific technical effects: The temperature resistance and transparency of the beam guiding component ensure the stability and coaxiality of the laser optical path, reduce the risk of beam disturbance, and improve energy coupling efficiency.

[0015] In a preferred embodiment, the nozzle seat and the guide fluid are further configured such that: the connector is an interference fit or a positioning shoulder fit; the connector is an external threaded interface or a quick connector and is directly connected to the air inlet chamber upstream of the spacer ring; the nozzle and the bottom surface of the guide fluid are detachably connected, and the connection is provided with a sealing mating surface or a sealing ring.

[0016] Specific technical effects: ensures gas path sealing and positioning repeatability, facilitates maintenance and replacement, maintains long-term stable pressure equalization and beam effect, and reduces efficiency loss caused by external leakage.

[0017] In a preferred example, the spacer ring and the nozzle seat together define an annular equal pressure chamber, the axial height of which matches the opening height of the diversion orifice.

[0018] Specific technical effects: A main equalization cavity is formed on the upstream side, which further improves the inlet static pressure consistency in the circumferential direction of the diversion orifice. Combined with the secondary equalization, it forms a graded rectification system of "main equalization - secondary equalization", making the beam more stable.

[0019] In a preferred example, the flow guide core and the nozzle are further configured such that a throat gap is formed upstream of the cone orifice, and the axial length of the gap is greater than its minimum radial gap.

[0020] Specific technical effects: It forms a short straight section effect and velocity renormalization effect, suppresses near-mouth turbulence and secondary vortex, and makes the high-speed beam at the cone mouth closer to axisymmetric, thereby improving the robustness of the focus point and nozzle-workpiece gap deviation.

[0021] The beneficial effects achieved by this utility model are as follows: 1. In this utility model, a low-turbulence, high-speed beam coaxial with the laser beam is formed through a continuous gas path of "isobaric - splitting - convergence - mixing - cone ejection". This effectively removes molten pool metal vapor and spatter, suppresses plasma obstruction, stabilizes the protective atmosphere, improves the penetration depth and weld formation quality, and effectively purges the protective lens to reduce contamination and extend its lifespan.

[0022] 2. In this utility model, a synergistic geometric design of swirl plate, flow divider / flow divider plate and annular collection groove is adopted to balance circumferential pressure difference and flow distribution, expand process window and parameter tolerance; the detachable sealing fit between nozzle and guide fluid facilitates maintenance and replacement, reduces gas consumption and improves long-term stability and consistency. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the overall structure of one embodiment of the present utility model; Figure 2 This is a cross-sectional structural diagram of one embodiment of the present invention; Figure 3 This is a schematic diagram of the fluid guiding structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the bottom surface structure of the fluid guide in one embodiment of the present invention.

[0024] Figure label: 1. Nozzle seat; 2. Inlet fluid; 3. Nozzle head; 11. Connector; 21. Guide core; 211. Laser guide core; 22. Spacer ring; 221. Swirl plate; 222. Diverting hole; 23. Diverting plate; 31. Conical opening; 32. Collecting groove. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features of the present utility model can be combined with each other.

[0026] It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this invention.

[0027] The following describes, with reference to the accompanying drawings, some embodiments of the present invention, providing a coaxial nozzle for laser welding.

[0028] Combination Figures 1-4 As shown, this utility model provides a coaxial nozzle for laser welding, embodiment one. Combination Figure 1 and Figure 2 As shown, this utility model provides a coaxial nozzle for laser welding, including a nozzle seat 1, a guide body 2, and a nozzle head 3. A connector 11 is provided at the upper end of the nozzle seat 1 for connecting to the air outlet and mounting interface of the laser welding head. The guide body 2 is assembled inside the nozzle seat 1; the nozzle head 3 is detachably installed on the bottom surface of the guide body 2, forming a sealed fit with it. To ensure reliable sealing, an annular sealing surface or sealing ring is provided at the connection between the nozzle head 3 and the guide body 2, isolating the internal gas passage from the outside after assembly.

[0029] In this embodiment, a guide core 21 is provided inside the guide fluid 2, and a laser guide core 211 is formed at the center of the guide core 21 to guide the laser beam to pass through coaxially. A conical opening 31 is formed at the center of the nozzle 3, and the laser guide core 211 and the conical opening 31 are arranged on the same axis to ensure the coaxiality and stability of the beam and the airflow. To reduce beam disturbance, a rounded transition can be provided on the inlet side of the laser guide core 211, and the outlet position is located at a predetermined distance upstream of the conical opening 31.

[0030] like Figure 2 — Figure 4 As shown, a partition ring 22 is fixedly installed inside the guide fluid 2. Multiple diversion holes 222 are evenly spaced along the circumference of the partition ring 22, and each diversion hole 222 communicates with an annular gas channel formed by the outer periphery of the guide core 21. A spiral swirl plate 221 is arranged along the outer periphery of the guide core 21 on the inner side of the partition ring 22. The swirl plate 221 and the outer surface of the guide core 21 together define a spiral flow channel, used to form the circumferential component of the main airflow and stably guide it to the upstream region of the cone 31. Several diversion plates 23 are arranged between the partition ring 22 and the inner wall of the guide fluid 2. Each diversion plate 23 and its corresponding diversion hole 222 are arranged circumferentially opposite each other. The diversion plate 23, the outer surface of the partition ring 22, and the annular collecting groove 32 on the top surface of the nozzle 3 together define a gradually contracting converging flow channel from top to bottom. Each converging channel will cause the distributed gas to meet the main gas flow formed by the swirl plate 221 in the upstream region of the cone 31. After the two are mixed, they will be ejected coaxially through the cone 31, thereby forming a near-axis symmetric, low-turbulence high-speed beam in the welding area.

[0031] In this embodiment, the flow divider 222 is preferably slit-shaped or rectangular window-shaped, with its long side arranged along the circumferential direction to reduce circumferential pressure drop and inlet flow deviation. The flow divider 23 is arranged radially, with its lower end smoothly transitioning to the annular collecting groove 32. The convergence channel formed by the flow divider 23 and the outer surface of the spacer ring 22 has a tapered geometry. The cone 31 of the nozzle 3 forms a minimum cross-section to increase axial velocity, and a short straight section is provided upstream of the cone 31 as a throat gap. The axial length of the throat gap is greater than its minimum radial gap to obtain a high-speed beam that is closer to axisymmetric. The annular collecting groove 32 is continuously arranged in the circumferential direction for secondary pressure equalization and confluence rectification of each convergence channel upstream of the cone 31.

[0032] To ensure long-term stability and durability, the nozzle seat 1 and the guide fluid 2 can be fitted with an interference fit or a positioning shoulder. The connector 11 can be an external threaded interface or a quick connector, and it is directly connected to the air inlet chamber upstream of the spacer ring 22. The outer surface of the guide core 21 is preferably a contracted-arc transition surface to reduce boundary layer separation and the generation of secondary vortices. Considering the welding spatter and heat radiation environment, the nozzle 3, the flow divider plate 23, and the spacer ring 22 can be made of high-temperature resistant copper alloy or stainless steel. The edges subjected to high-speed scouring can be rounded and coated with a wear-resistant coating. The laser guide core 211 can be made of a high-temperature resistant transparent material or a coaxial guide hole structure, and it must be strictly coaxial with the conical opening 31. After assembly, the roundness and coaxiality of the conical opening 31 are checked to ensure that the coaxiality tolerance between the laser guide core 211 and the conical opening 31 meets the process requirements.

[0033] In a typical size configuration of this embodiment, the protective gas is argon or nitrogen. In practical applications, the area of ​​the flow divider 222, the number and angle of the flow divider plates 23, and the cone angle of the cone 31 can be adapted and adjusted according to the material type and plate thickness to maintain a stable beam and good molten pool protection under different operating conditions.

[0034] In another embodiment, the gas path distribution and geometric parameters are configured differently to adapt to deep penetration welding or welding of high-reflectivity materials. Specifically, an annular isobaric cavity is preferably formed between the spacer ring 22 and the top surface of the nozzle 3, and its axial height matches the opening height of the diversion orifice 222, so that the static pressure at the inlet of each convergence channel is more consistent. The diversion orifices 222 are arranged at equal intervals around the circumference, and the opening area of ​​each orifice is equal and corresponds one-to-one with the corresponding diversion plate 23; in order to reduce the local pressure drop difference, the long side of the diversion orifice 222 is still arranged along the circumferential direction.

[0035] In this embodiment, a throat gap is provided between the guide core 21 and the nozzle 3 upstream of the cone opening 31; the cone angle and minimum diameter of the nozzle 3 are determined according to the laser power and focal position used, and the ratio of the minimum diameter to the spot diameter at the laser guide core 211 is not less than 1.2 to avoid beam obstruction or edge ablation. To adapt to materials with high reflectivity or strong plasma, the annular collecting groove 32 can form a short straight section secondary rectification zone with the lower end of the splitter plate 23 to further stabilize the velocity profile before entering the cone opening 31; in addition, the angle of attack of the swirling plate 221 can be configured in a smaller range to reduce the influence of the circumferential velocity component on the formation of the molten pool.

[0036] In terms of manufacturing and assembly, a positioning shoulder is provided between the nozzle seat 1 and the guide fluid 2 to ensure the repeatability of the positioning accuracy of the spacer ring 22, the flow divider plate 23, and the swirl plate 221 in the axial and circumferential directions; the nozzle 3 adopts a threaded or snap-fit ​​detachable connection, and the sealing ring is made of temperature-resistant and corrosion-resistant material to ensure long-term sealing reliability. After assembly, the coaxiality of the laser guide core 211 and the cone 31 is checked, and if necessary, it is corrected by fine-tuning the positioning surface or shims to meet the process requirements for coaxiality and roundness.

[0037] Working principle and usage process of this utility model: The protective / auxiliary gas enters the nozzle seat 1 from the connector 11, forming an isobaric zone within the annular space enclosed by the nozzle seat 1 and the guide fluid 2. This isobaric effect provides a basically uniform inlet static pressure to each downstream channel, avoiding uneven circumferential flow.

[0038] A portion of the gas after isobaricization enters the spiral flow channel defined by the swirl plate 221 and the outer periphery of the guide core 21 along the inner edge of the partition ring 22 on the inner side of the guide fluid 2. The gas is given a stable circumferential velocity component in this channel, forming an axisymmetric main spiral airflow, and is transported downward along the outer surface of the guide core 21 to the upstream region of the cone 31; the laser beam passes through the laser guide core 211 and always remains coaxial with the main airflow.

[0039] Another stream of gas is evenly distributed to various points around the circumference through several diversion holes 222 on the partition ring 22, and then converges downwards along the tapering channel defined by the outer surface of the partition ring 22 and the annular collecting groove 32 on the top surface of the nozzle 3, guided by the diversion plate 23. The annular collecting groove 32 performs secondary pressure equalization in the circumference, making the flow rate entering each convergence channel more uniform.

[0040] The converged circumferential airflow merges and mixes with the main helical airflow upstream of the conical inlet 31. The two airflows provide axial dynamic pressure and circumferential rectification, respectively: firstly, the tapering geometry of the convergence channel increases the axial velocity of the gas and reduces the turbulence intensity; secondly, the main helical component forms a central "air curtain" along the outer periphery of the guide core 21, suppressing backflow and lateral vortices. After their superposition, a near-axisymmetric high-speed beam is formed at the conical inlet 31, which is ejected coaxially with the laser beam guided by the laser guide core 211 to remove molten pool vapor and spatter and maintain a stable protective atmosphere.

[0041] By adjusting the area of ​​the flow divider 222, the number / angle of the flow divider 23, the angle of attack of the swirl plate 221, and the geometric ratio of the cone 31, it is possible to adapt to different materials and plate thicknesses on the same nozzle: the main airflow provides strong purging of the penetration zone, and the annular convergent flow forms an envelope and secondary rectification at the outer edge, thereby improving the aspect ratio stability, reducing plasma obstruction, and extending the cleaning cycle of the optical window.

[0042] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0043] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A coaxial nozzle for laser welding, characterized in that, include: The nozzle holder (1) has a connector (11) at its upper end that is connected to the laser welding head. A guide fluid (2) is installed inside the nozzle seat (1); The nozzle (3) is installed at the lower end of the nozzle seat (1); The guide fluid (2) contains a guide core (21), and a laser guide core (211) is located at the center of the guide core (21). The laser guide core (211) is coaxially arranged with the conical opening (31) of the nozzle (3). A partition ring (22) is fixedly installed inside the guide fluid (2). The surface of the partition ring (22) is provided with multiple diversion holes (222) that communicate with the gas channel located on the outer periphery of the guide core (21). The top surface of the nozzle (3) is provided with an annular collecting groove (32). The inner surface of the partition ring (22) contains... A spiral swirl plate (221) is provided on the side along the outer periphery of the guide core (21). The main airflow flows through the spiral flow channel formed by the swirl plate (221) on the outer periphery of the guide core (21). Several diversion plates (23) are provided between the partition ring (22) and the inner wall of the guide fluid (2). The diversion plates (23) are arranged corresponding to each diversion hole (222). A portion of the airflow is confined along the outer surface of the partition ring (22) and the top surface of the nozzle (3) to form a gradually contracting flow channel from top to bottom, which is then mixed with the main airflow and output.

2. The coaxial nozzle according to claim 1, characterized in that: The diversion holes (222) are arranged at equal intervals along the circumference. The diversion holes (222) are slit-shaped or rectangular window-shaped, with their long sides arranged along the circumference to reduce the local pressure drop difference when entering the convergence channel defined by each diversion plate (23).

3. The coaxial nozzle according to claim 1 or 2, characterized in that: The spacer (22) and the top surface of the nozzle (3) form an annular equal pressure cavity. The axial height of the annular equal pressure cavity matches the opening height of the diversion hole (222) to reduce the pressure difference at the inlet of each converging flow channel.

4. The coaxial nozzle according to claim 1, characterized in that: The flow divider (23) is arranged radially, and its lower end smoothly transitions to the annular flow collection groove (32) on the top surface of the nozzle (3), and together with the outer surface of the partition ring (22), defines a gradually narrowing flow channel from top to bottom.

5. The coaxial nozzle according to claim 1, characterized in that: The laser guide core (211) is a light guide component or coaxial guide hole structure made of high temperature resistant transparent material, used to guide the laser through and maintain coaxiality with the conical opening (31).

6. The coaxial nozzle according to claim 1, characterized in that: The nozzle seat (1) and the guide fluid (2) are interference fit or positioning shoulder fit. The connector (11) is an external thread interface or quick connector and is directly connected to the air inlet chamber upstream of the partition ring (22). The nozzle (3) is detachably installed on the bottom surface of the guide fluid (2). The connecting part is provided with a sealing mating surface or sealing ring to isolate the gas passage where the partition ring (22) and the diverter plate (23) are located from the outside.

7. The coaxial nozzle according to claim 1, characterized in that: The partition ring (22) and the nozzle seat (1) together define an annular equal pressure chamber. The axial height of the annular equal pressure chamber matches the opening height of the diversion orifice (222) to reduce the pressure difference between each diversion orifice (222).

8. The coaxial nozzle according to claim 1, characterized in that: A throat gap is formed between the guide core (21) and the nozzle (3) upstream of the cone opening (31). The axial length of the throat gap is greater than its minimum radial gap, thereby obtaining a near-axisymmetric high-speed beam at the cone opening (31).

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