Laser welding apparatus and control method

Abstract

The application relates to a laser welding device and a control method. The laser welding device is composed of a welding mechanism, a first gas source in communication with the welding mechanism, a tool with a material placing plane and a lower containing space, a gas blowing assembly with a first gas outlet opening towards a slit opening in the containing space and a second gas source in communication with the gas blowing assembly, and a controller electrically connected with the above units, wherein the welding mechanism comprises a welding gun and a gas blowing pipe located above a workpiece; the tool is provided with a slit opening extending along a joint seam between adjacent welding areas; and the controller determines and controls a second gas supply parameter according to welding parameters and a first gas supply parameter, so that an airflow from bottom to top lifts a molten pool through the slit opening, effectively solves the problems of metal infiltration, large back face excess height / sagging and oxidation caused by only upper gas supply, and further realizes the consistency improvement of back face forming and welding penetration and the adaptation to multi-station production.

Description

TECHNICAL FIELD

[0001] The present application relates to a welding device, in particular to a laser welding device and a control method. BACKGROUND

[0002] Laser welding is widely used in sheet splicing, box / frame assembly welding, and cover lap welding due to its high energy density, small heat-affected zone, and high welding efficiency. The typical process flow is as follows: the workpiece to be welded is positioned on the material placement plane of the tooling, and is clamped and positioned by the clamp. The weld is usually located at the joint of adjacent workpieces. During welding, the welding torch runs on a preset trajectory, and the protective gas is used to suppress the oxidation of the molten pool and stabilize the penetration and shaping. In multi-station / multi-zone clamps, the material placement plane is often divided into multiple welding zones to improve the cycle and clamping efficiency.

[0003] The existing laser welding device generally includes a welding mechanism (welding torch / mirror), a gas blowing pipe (upper protective gas nozzle) and its first gas source arranged above the workpiece, a tooling and positioning clamp for positioning and clamping, etc. The protective gas (such as Ar, He or their mixture) is sprayed onto the molten pool from the upper gas blowing pipe to achieve metallurgical protection. The welding parameters (such as laser power, welding speed, defocusing amount, oscillation, etc.) and the upper protective gas supply parameters (such as flow rate, pressure, nozzle-weld distance / angle) are generally obtained by process library or experience setting according to the material, sheet thickness and joint form. To improve the back quality, some schemes will add copper back plate, backing agent, back gas chamber or temporary back protection cover on the back of the workpiece, but most of them are external accessories, and the arrangement and control are relatively independent, and the integration with multi-zone tooling is limited.

[0004] Under the condition of relying on the upper gas blowing pipe for gas supply, the molten metal is prone to seep downward along the joint direction under the joint action of gravity and the dynamic pressure of the upper gas flow and solidify on the lower side of the workpiece, resulting in defects such as large back excess height, sagging / hanging tumor, etc. Therefore, it is urgent to provide a laser welding device to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a laser welding device capable of forming a downward blowing gas flow aligned with the joint inside the tooling and cooperatively controlled with the upper protective gas.

[0006] The technical solution adopted by the present application to solve the above problems is: a laser welding device, comprising:

[0007] a welding mechanism, comprising:

[0008] a controlled welding torch;

[0009] a gas blowing pipe arranged above the workpiece to be welded for providing protective gas above the weld;

[0010] A first gas source in communication with the blowing pipe for supplying a protective gas to the blowing pipe;

[0011] A tool having a material placing plane on its upper surface and a containing space below the material placing plane, the material placing plane comprising at least two welding areas for placing workpieces to be welded, and a slit opening in communication with the containing space being provided between adjacent welding areas and extending along a joint between adjacent workpieces to be welded;

[0012] A blowing assembly arranged in the containing space, an outer surface of the blowing assembly being provided with a first gas outlet facing the slit opening;

[0013] A second gas source in communication with the blowing assembly for supplying a protective gas to the first gas outlet so that an upward gas flow acts on molten metal at the joint between adjacent workpieces to be welded through the slit opening;

[0014] A controller electrically connected with the welding mechanism, the first gas source and the second gas source respectively, the controller being configured to determine a second gas supply parameter of the second gas source according to welding parameters of the welding mechanism and a first gas supply parameter of the first gas source when the welding mechanism is in a working state, and to control the second gas source to operate according to the second gas supply parameter so as to provide an upward gas force for the molten metal at the joint between adjacent workpieces to be welded by the upward gas flow during welding.

[0015] Preferably, the blowing assembly comprises:

[0016] A first pipe member, a tubular wall of the first pipe member being continuously provided with a long and narrow gap type first gas outlet in communication with an outer surface along an axial direction thereof;

[0017] A second pipe member coaxially inserted into the first pipe member so that an outer surface of the second pipe member and an inner wall of the first pipe member form an annular gap therebetween, the second pipe member being provided with a second gas outlet in communication with an outer surface on a tubular wall thereof, one end of the second pipe member being closed, and the other end of the second pipe member being in communication with the second gas source;

[0018] At least two sealing members are arranged in the annular gap and divided into two groups, the two groups of sealing members being respectively located on two sides of the first gas outlet along the axial direction of the first pipe member so as to block two open ports of the annular gap formed in the axial direction of the first pipe member, and an annular gas path is formed by the two groups of sealing members and the inner wall of the annular gap on opposite sides thereof;

[0019] The second gas outlet is arranged in a circumferential direction relative to the first gas outlet in a staggered manner and located between the two groups of sealing members.

[0020] Preferably, the air blowing assembly comprises:

[0021] The movable sleeve is arranged outside the adjusting pipe of the first pipe, and the adjusting pipe is used to partially shield the first air outlet to adjust the effective opening length and / or effective jetting section of the first air outlet.

[0022] Preferably, the jetting direction of the first air outlet forms an angle of 15°-30° with the normal direction of the material placing plane.

[0023] In particular, a control method for the laser welding device, comprising the following steps:

[0024] Obtaining the performance parameters of the workpiece to be welded, and determining the welding parameters of the welding mechanism and the first gas supply parameters according to the performance parameters of the workpiece to be welded;

[0025] Controlling the welding mechanism to operate according to the welding parameters, and controlling the first gas source to operate according to the first gas supply parameters;

[0026] Obtaining the depth of the slit opening, the transfer distance from the first air outlet to the side of the slit opening away from the material placing plane, and the turning angle formed by the jetting direction of the first air outlet and the normal direction of the material placing plane;

[0027] Determining the second gas supply parameters of the second gas source according to the depth of the slit opening, the transfer distance, and the turning angle;

[0028] Controlling the second gas source to operate according to the second gas supply parameters.

[0029] Preferably, the obtaining the performance parameters of the workpiece to be welded, and determining the welding parameters of the welding mechanism and the first gas supply parameters according to the performance parameters of the workpiece to be welded, comprises the following steps:

[0030] The performance parameters at least include one or any combination of the following: base material material type and grade, plate thickness, surface state and cleanliness, weld form and groove parameter, seam gap, filler material and wire feeding specification, preheating / interpass temperature target, shielding gas type and purity, clamping / thermal restraint condition;

[0031] Based on the performance parameters, the welding parameters for controlling the welding mechanism are determined from a pre-set welding process library and / or an experience mapping relationship and / or a mathematical model, and the welding parameters at least include one of the following: laser power and / or energy density, welding speed, focal point position / defocusing amount, pulse frequency and duty cycle (such as pulse welding), swing amplitude and frequency (such as with swing), wire feeding speed and / or wire feeding temperature;

[0032] determining the first gas supply parameter for controlling the first gas source according to the performance parameter from a pre-set gas supply process library and / or an empirical mapping relationship, the first gas supply parameter at least including one of the following: a kind and / or purity of shielding gas, a mass flow and / or a volume fraction flow, a gas supply pressure, a distance and / or an inclination angle between a blowing pipe and a weld seam;

[0033] applying a manufacturer's calibration range and a safety threshold constraint to the welding parameter and the first gas supply parameter, and outputting to the controller as a target setting.

[0034] Preferably, the steps of obtaining the depth of the slit opening, the transfer distance from the first gas outlet to the slit opening away from the side of the material placement plane, and the turning angle formed between the jet direction of the first gas outlet and the normal direction of the material placement plane, include the following steps:

[0035] obtaining the depth of the slit opening, the depth of the slit opening being defined as the distance from the surface of the material placement plane to the boundary interface of the slit opening away from the side of the material placement plane in the normal direction of the material placement plane;

[0036] obtaining the transfer distance, the transfer distance being defined as the shortest distance from the first gas outlet jet port surface to the boundary interface of the slit opening away from the side of the material placement plane along the direction of the first gas outlet jet centerline;

[0037] obtaining the turning angle, the turning angle being defined as the angle between the jet direction of the first gas outlet and the normal direction of the material placement plane.

[0038] Preferably, the step of determining the second gas supply parameter of the second gas source according to the depth of the slit opening, the transfer distance and the turning angle, includes the following steps:

[0039] determining a gas flow transfer attenuation coefficient according to the depth of the slit opening, the transfer distance and the turning angle, the gas flow transfer attenuation coefficient reflecting the attenuation of the gas flow momentum / kinetic pressure from the first gas outlet to the outlet of the slit opening;

[0040] determining a target back blowing index at the outlet of the slit opening according to a pre-set forming quality target at the weld seam of the workpiece, the forming quality target at least including one or any combination of the following: an upper limit of back face reinforcement, a penetration level and / or a minimum penetration depth at the root of the weld seam, an allowable sag amount, an oxygen / nitrogen content threshold value in the back surface protection zone; the target back blowing index at least including one of the following: a target kinetic pressure, a target flow rate, a target lifting force per unit length of the seam and / or an upper limit threshold value of the back side reinforcement of the weld seam;

[0041] Solving the target back-blowing index and the airflow transmission decay coefficient together obtains the target jetting condition required at the first air outlet, and the second gas supply parameter of the second gas source is determined according to the target jetting condition, and the second gas supply parameter at least includes the gas supply pressure and flow of the second gas source.

[0042] Preferably, the airflow transmission decay coefficient is given by at least one of a pre-stored calibration curve, an empirical mapping relationship, an analytical / numerical model.

[0043] Applying a rated boundary and a safety threshold limit to the second gas supply parameter obtains the final second gas supply parameter.

[0044] Preferably, the control method further includes a correction step for the relationship between the airflow parameter of the first air outlet and the second gas supply parameter, and the correction step includes:

[0045] Obtaining the actual jetting parameter at the first air outlet of the blowing assembly;

[0046] Comparing the actual jetting parameter with the target jetting condition obtains a deviation value;

[0047] Based on the deviation value, the second gas supply parameter is corrected;

[0048] When the deviation value is less than a preset tolerance threshold, the final second gas supply parameter is confirmed; otherwise, the correction of the second gas supply parameter is continued.

[0049] The beneficial effects of the embodiments in the present application are:

[0050] 1. Since the technical means of setting a slit opening in communication with the accommodation space and extending along the joint between adjacent welding areas on the work device plane, arranging a blowing assembly in the accommodation space facing the slit opening and being supplied with gas by an independent second gas source, and a controller determining the second gas supply parameter according to the welding parameters and the first gas supply parameter of the welding mechanism to cooperatively control the two-way gas, the downward protective gas flow can be directly applied to the back of the molten pool through the slit opening, providing upward aerodynamic force for the molten metal and establishing a stable back protective atmosphere, effectively solving the technical problems of excessive back reinforcement, sagging / hanging and back oxidation caused by the downward infiltration of the molten metal along the joint in the prior art, thereby realizing the technical effects of significantly reducing the back reinforcement, stabilizing the weld formation, and more controllable weld penetration and metallurgical quality, and also considering the rapid adaptation and yield improvement in the multi-station / multi-joint scenario.

[0051] 2、Due to the adoption of the technical means of determining the welding parameters and the first gas supply parameters of the welding mechanism based on the performance parameters of the workpiece to be welded, obtaining the depth of the slit opening, the transmission distance of the first gas outlet to the side of the slit opening away from the material placement plane, and the deflection angle of the jet direction to the normal of the material placement plane before / during welding, and quantitatively determining the second gas supply parameters of the second gas source according to the above, and implementing cooperative control of the first / second gas source and the welding mechanism, the technical problems in the prior art that the molten metal seeps along the seam, the back surface excess height is large and sagging / hanging, the back surface protection is unstable and difficult to quickly match with the material / plate thickness / seam geometry changes are effectively solved, and the parameterized matching of the back blowing strength and direction from bottom to top to the geometry and process is realized, the back surface excess height is significantly reduced and stabilized, the sagging and oxidation defects are inhibited, the weld penetration and forming consistency are improved, the process window is expanded, and the adaptability and yield in the multi-station / multi-region tooling scene are enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is a schematic structural diagram of a laser welding device according to an embodiment of the present application.

[0053] Figure 2 is a schematic structural diagram of a gas blowing assembly according to an embodiment of the present application.

[0054] Figure 3 is a schematic sectional view of a gas blowing assembly according to an embodiment of the present application.

[0055] Figure 4 is a flowchart of a control method for a laser welding device according to an embodiment of the present application.

[0056] Figure 5 is Figure 4 a flowchart of obtaining the performance parameters of the workpiece to be welded and determining the welding parameters and the first gas supply parameters according to the performance parameters.

[0057] Figure 6 is Figure 4 a flowchart of the obtaining method of the depth, transmission distance and deflection angle of the slit opening.

[0058] Figure 7 is Figure 4 a flowchart of determining the second gas supply parameters according to the depth, transmission distance and deflection angle of the slit opening.

[0059] Figure 8 is Figure 4 a flowchart of correcting the relationship between the gas flow parameters of the first gas outlet and the second gas supply parameters.

[0060] Wherein: 10, welding mechanism; 110, welding gun; 120, blowing pipe; 20, tooling; 210, material placing plane; 211, welding area; 212, slit opening; 220, accommodating space; 30, blowing assembly; 310, first pipe; 311, first air outlet; 320, second pipe; 321, second air outlet; 330, adjusting pipe; 40, workpiece. DETAILED DESCRIPTION

[0061] The specific embodiments of the present application will be further described in conjunction with the drawings and examples. The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0062] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0063] In the description of the present application, it needs to be understood that the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0064] Please refer to Figure 1 and Figure 3The application provides a laser welding device, which comprises a welding mechanism 10, a first gas source, a tooling 20, a blowing assembly 30, a second gas source and a controller. The welding mechanism 10 comprises a controlled welding gun 110 and a blowing pipe 120 arranged above the workpiece 40 to be welded and used for providing a protective gas above the welding seam; the first gas source is communicated with the blowing pipe 120 and used for supplying the protective gas to the blowing pipe 120; the tooling 20 has a material placing plane 210 on the upper surface thereof and a containing space 220 below the material placing plane 210, the material placing plane 210 comprises at least two welding areas 211 used for placing the workpiece 40 to be welded, and a slit opening 212 communicated with the containing space 220 is arranged between the adjacent welding areas 211 and extends along the joint between the adjacent workpieces 40 to be welded; the blowing assembly 30 is arranged in the containing space 220, and the outer surface of the blowing assembly 30 is provided with a first gas outlet 311 facing the slit opening 212; the second gas source is communicated with the blowing assembly 30 and used for supplying the protective gas to the first gas outlet 311 so that the gas flow from below acts on the molten metal at the joint between the adjacent workpieces 40 to be welded through the slit opening 212; the controller is electrically connected with the welding mechanism 10, the first gas source and the second gas source respectively, and the controller is configured to determine the second gas supply parameter of the second gas source according to the welding parameter of the welding mechanism 10 and the first gas supply parameter of the first gas source when the welding mechanism 10 is in the working state, and control the second gas source to operate according to the second gas supply parameter, so as to provide the upward gas power for the molten metal at the joint between the adjacent workpieces 40 to be welded through the gas flow from below during the welding process.

[0065] Specifically,

[0066] The welding mechanism 10 comprises the controlled welding gun 110 and the blowing pipe 120 arranged above the workpiece 40 to be welded, and the blowing pipe 120 is communicated with the first gas source and used for providing the protective gas above the welding seam.

[0067] The tooling 20 has the material placing plane 210 on the upper surface thereof and the containing space 220 below the material placing plane 210, the material placing plane 210 is divided into a plurality of welding areas 211 used for placing the workpiece 40 to be welded, and the slit opening 212 communicated with the containing space 220 is formed between the adjacent welding areas 211 and extends along the joint between the adjacent workpieces 40.

[0068] The blowing assembly 30 is arranged in the containing space 220, and the outer surface of the blowing assembly 30 is provided with the first gas outlet 311 facing the slit opening 212. The second gas source is communicated with the blowing assembly 30 and supplies the protective gas to the first gas outlet 311.

[0069] The controller is electrically connected with the welding mechanism 10, the first gas source and the second gas source. In the working state of the welding mechanism 10, the second gas supply parameter of the second gas source is determined based on the welding parameter of the welding mechanism 10 and the first gas supply parameter of the first gas source, and the second gas source is driven accordingly, so that the airflow from bottom to top acts on the molten metal at the joint through the slit opening 212.

[0070] Before welding, the workpieces 40 to be welded are positioned and fixed on each welding area 211 of the material placing plane 210, so that the joints between the adjacent workpieces 40 are in the same direction and aligned with the slit opening 212. During welding, the welding gun 110 operates according to the preset trajectory, and the upper gas blowing pipe 120 continuously or periodically supplies the protective gas for metallurgical protection and molten pool stabilization. At the same time, the second gas source sprays the airflow from the first gas outlet 311 of the gas blowing assembly 30 to the direction of the slit opening 212, and the airflow passes through the opening from bottom to top to the back of the joint, contacts the molten or semi-molten metal pool, forms the upward gas dynamic force and establishes the back protection atmosphere, so as to play the complex role of lifting and shaping the molten pool under the action of gravity and the upper airflow. The controller dynamically calculates and issues the second gas supply parameter according to the welding parameter of the welding mechanism 10 and the first gas supply parameter, so that the back blowing intensity and direction match the current working condition.

[0071] The controller can obtain the welding parameters including power, travel speed, defocusing amount, swing mode and the like from the welding mechanism 10, and obtain the first gas supply parameters including flow rate and pressure from the first gas source. The controller determines the second gas supply parameter based on the preset process mapping relationship or model, in combination with the current joint alignment state and the opening geometric direction. The parameter can include gas supply pressure, mass flow rate, start-stop timing or pulse duty cycle. In some embodiments, a pressure or flow rate detection element (not shown in the figure) can be arranged upstream of the gas blowing assembly 30 or in the cavity, and the controller uses the measured value to compensate the error of the second gas supply parameter, so as to keep the back blowing airflow at the slit opening 212 within the target interval. In order to avoid the molten droplets being sucked in, the jet direction of the first gas outlet 311 can be set as an inclined direction relative to the normal of the material placing plane 210, and the corresponding posture constraint can be set in the controller.

[0072] The device is suitable for thin plate joint welding, box or frame assembly welding, and cover lap welding, and is especially suitable for the case that the joints of the adjacent workpieces 40 are located on the material placing plane 210 and can communicate with the lower cavity through the opening. The tooling 20 should have sufficient flatness and rigidity to ensure the stability of the alignment of the joint and the slit opening 212; the accommodation space 220 should meet the arrangement requirements of the gas channel and the exhaust passage. The protective gas can be inert or active mixed, and the specific type and purity are selected according to the material system and surface quality requirements. The environmental temperature and humidity, dust and smoke treatment can be realized by external exhaust and filtration unit, which does not affect the structure and function of the embodiment.

[0073] In some alternative embodiments, the first gas outlet 311 can be designed as any one of a slit jet, an array of micro-holes or an arc-shaped opening to adapt to different seam lengths and curvatures; the blowing assembly 30 can adopt a slidable guide seat or a replaceable jet module to realize quick switching of the jetting section. To enhance adaptability, the slit opening 212 can be made into a straight-line slit or a segmented opening throughout the section, and a sealing edge or a flow guide lip can also be provided on both sides of the opening to suppress air leakage and vortex. In multi-station applications, the blowing assembly 30 can be made into a partitioned independent control structure, and the second gas supply parameters are respectively issued by the controller according to the station beat. To facilitate maintenance, a detachable slag collecting plate or a flow guide plate can be provided at the bottom of the accommodation space 220 to avoid the influence of metal particles and molten slag on the smoothness of the air path. The above-mentioned variants do not change the basic principle of the present embodiment, i.e., the back blowing air flow in the tool 20 directly acts on the back of the seam through the slit opening 212.

[0074] In the present embodiment, since the technical means of forming the slit opening 212 aligned with the seam in the tool 20 and providing the first gas outlet 311 below it which is supplied with gas by an independent second gas source and whose second gas supply parameters are determined by the controller based on the welding parameters and the first gas supply parameters are adopted, the technical problems in the prior art that only relying on the upper gas supply results in excessive back height of the molten metal, sagging and hanging of the seam, and unstable back protection are effectively solved, thereby realizing the technical effects that the back of the molten pool is stably lifted, the back of the weld is formed more uniformly, the weld penetration and metallurgical quality are more controllable, and the production yield is improved in multi-station scenarios.

[0075] Please refer to Figure 2 and Figure 3 In some embodiments, the blowing assembly 30 comprises a first pipe 310, a second pipe 320 and at least two seals. The first pipe 310 has a pipe wall with a plurality of first gas outlets 311 in the form of long and narrow gaps formed in the pipe wall along the axial direction of the first pipe 310 and communicating with the outer surface of the first pipe 310. The second pipe 320 is coaxially inserted into the first pipe 310, so that an annular gap is formed between the outer surface of the second pipe 320 and the inner wall of the first pipe 310. The second pipe 320 has a pipe wall with a plurality of second gas outlets 321 formed in the pipe wall along the axial direction of the second pipe 320 and communicating with the outer surface of the second pipe 320. One end of the second pipe 320 is closed, and the other end of the second pipe 320 is in communication with the second gas source. The at least two seals are arranged in the annular gap and divided into two groups. The two groups of seals are respectively located on the two sides of the first gas outlets 311 along the axial direction of the first pipe 310 to block the two open ends of the annular gap formed in the axial direction of the first pipe 310, and an annular gas path is formed by the two groups of seals and the inner wall of the annular gap on the opposite sides. The second gas outlets 321 are arranged in a circumferential direction relative to the first gas outlets 311 and located between the two groups of seals.

[0076] Specifically:

[0077] The first pipe 310 is a hollow long cylinder, and a long and narrow gap type first air outlet 311 is continuously formed in the wall of the first pipe 310 in the axial direction, the gap has a substantially constant width in the length direction to form an outlet cross section similar to a linear jet; in order to reduce shear vortex and wall reattachment, the two side edges of the first air outlet 311 can be slightly chamfered or smoothly transitioned.

[0078] The second pipe 320 is coaxially inserted into the first pipe 310, and an annular gap is formed between the two; the second pipe 320 is uniformly distributed with second air outlets 321 on the wall thereof, the second air outlets 321 are in communication with the outer surface thereof, and are arranged in a circumferential direction opposite to the first air outlet 311 to avoid direct penetration and deflection flushing. One end of the second pipe 320 is a closed end, and the other end is an air inlet end and is in communication with a second gas source.

[0079] At least two sealing members are arranged in the annular gap and are divided into two groups, the two groups are respectively located on the two axial sides of the first air outlet 311, and are positioned by means of an annular groove in the inner wall of the first pipe 310 or the outer surface of the second pipe 320; the sealing members and the opposite sides of the inner wall of the annular gap jointly enclose a closed annular gas path, block the axial open port of the annular gap, and make the gas entering the annular gap uniform in pressure and flow in a limited section.

[0080] The first pipe 310 and the second pipe 320 can be made of heat-resistant and corrosion-resistant metal materials, and the inner surface is preferably finely polished or chemically passivated to reduce flow resistance and the risk of fouling; the sealing member can be made of a temperature-resistant and aging-resistant elastic material or a composite lip structure to maintain sealing and low friction under repeated thermal cycles and slight eccentricity conditions.

[0081] The second pipe 320 is inserted into the first pipe 310 from one end to a predetermined position, the closed end faces the section where the first air outlet 311 is located, and the air inlet end is detachably connected to the second gas source through a joint. The sealing members are sequentially loaded into the corresponding annular grooves and form a radial interference or axial pre-pressing with the adjacent structure; after assembly is completed, the sealing members divide the annular gap into a gas supply area and a non-gas supply area, the gas supply area is limited in the axial direction between the two groups of sealing members, and covers the range where the first air outlet 311 is located in the circumferential direction. The second air outlets 321 are all arranged in the gas supply area between the two groups of sealing members, and are arranged in a circumferential direction opposite to the first air outlet 311, so that the gas overflowing from the second pipe 320 first enters the annular gas path and then turns to the first air outlet 311, avoiding direct penetration and local high-speed flushing. If necessary, a thrust washer or a guide bushing can be arranged between the end of the second pipe 320 and the end of the first pipe 310 to control the distance between the annular gaps and suppress vibration.

[0082] The protective gas outputted by the second gas source enters the lumen through the inlet end of the second pipe 320, turns back at the closed end, and is discharged into the annular gas path through the second gas outlet 321. The seal blocks the annular gap at the axial direction, forcing the gas to spread uniformly along the annular gas path and accumulate dynamic pressure in the circumferential direction. The gas flow rectified through the annular gas path converges to the first gas outlet 311 along the path of least resistance, and is sprayed out in the form of linear jet pointing to the direction of the slit opening 212. The second gas outlet 321 is arranged in a staggered manner with the first gas outlet 311 in the circumferential direction, so that the gas flow produces a certain diffusion and pressure balance after entering the annular gas path, which helps to obtain a more consistent face average flow rate and dynamic pressure distribution on the full length of the first gas outlet 311, thereby forming a continuous and uniform linear blowing curtain. The presence of the closed end increases the effective volume and buffering effect in the second pipe 320, reducing the transient influence of gas supply fluctuations on the jet flow field.

[0083] To ensure the quality of the jet flow, the radial gap of the annular gap should be stable and the axial step should be reduced. The gap edge of the first gas outlet 311 should be straight and parallel to the pipe axis to avoid secondary throttling caused by local narrowing. The axial position of the seal should be set corresponding to the start and end edges of the first gas outlet 311, so that the gas supply area covers the entire effective length of the jet. The opening density of the second gas outlet 321 can be distributed along the axial direction to compensate for the flow decay at the end caused by the pressure drop along the way; in the circumferential direction, it should avoid the projection area of the first gas outlet 311 to maintain a staggered relationship. If disassembly and maintenance are required, the second pipe 320 and the first pipe 310 can be reassembled by positioning pins or stopper cooperation to reproduce the angular reference, ensuring the consistency of the staggered relationship and the position of the gas supply area.

[0084] The blowing assembly 30 is arranged in the accommodation space 220 of the tool 20 for use, and is suitable for inert or weakly active protective gas environment. The assembly should avoid direct contact with high-temperature droplets or strong acid and alkali cleaning agents for a long time, and the inner and outer surfaces should be cleaned regularly to prevent dust and metal particles from depositing and causing jet blockage. In high humidity or oil mist environment, it is recommended to configure a front-end filter and drainage device to ensure that the gas entering the second pipe 320 is clean and dry. When assembling, it is necessary to ensure that the first gas outlet 311 faces the slit opening 212, and the surface of the seal is clean and free of scratches to maintain sealing and low leakage.

[0085] In this embodiment, the annular gap structure between the slotted first air outlet 311 of the first pipe 310 and the coaxial second pipe 320 is formed by two groups of sealing elements in the axial direction to form a closed annular air path and arrange the second air outlet 321 in the circumferential direction opposite to the first air outlet 311 between the two groups of sealing elements. This effectively solves the technical problems of uneven line spraying, direct jet penetration leading to local scouring and airflow pulsation, and difficulty in uniformizing the dynamic pressure of the full length of the nozzle in the prior art, and further realizes the technical effects of uniform distribution of airflow in the length direction of the nozzle, stable and controllable jet direction, enhanced anti-fluctuation ability, and significantly improved continuity and coverage of linear back blowing at the slotted opening 212.

[0086] Please refer to Figure 2 and Figure 3 . Further, to enable the air blowing assembly 30 to cooperate with seams of different lengths, the air blowing assembly 30 comprises an adjusting pipe 330 movably sleeved outside the first pipe 310, which is used to partially shield the first air outlet 311 to adjust the effective opening length and / or effective jetting section of the first air outlet 311.

[0087] Specifically:

[0088] The adjusting pipe 330 is a hollow sleeve member movably sleeved on the outer circumferential side of the first pipe 310. A small fitting gap is formed between the inner wall of the adjusting pipe 330 and the outer wall of the first pipe 310 to balance smooth sliding and low leakage. The end edges of the adjusting pipe 330 adopt rounded or beveled transitions, and the end edge close to the first air outlet 311 is provided with a flow guide lip to form a smooth transition between the shielding boundary and the nozzle boundary, thereby weakening the shear mutation. The body of the adjusting pipe 330 is preferably made of a material resistant to heat and corrosion with low thermal deformation, and the inner wall can be finely polished or coated with solid lubricant to reduce friction and dust accumulation. To suppress external leakage and dust intrusion, a circular cross-section sealing ring or a thin-lip sealing ring can be provided between the adjusting pipe 330 and the first pipe 310.

[0089] The adjusting pipe 330 is sleeved from one end of the first pipe 310 and can slide in the axial direction within a predetermined stroke to cover or leave out different sections of the first air outlet 311; if necessary, a small range of circumferential fine adjustment is allowed for alignment of the window and the target jetting section. To ensure repeated positioning, a guide key can be provided on the outer wall of the first pipe 310, and a corresponding key groove is provided on the inner side of the adjusting pipe 330 to limit the unwanted degrees of freedom and ensure that the shielding boundary and the nozzle boundary are parallel. The outer surface of the adjusting pipe 330 is provided with a gripping area and a positioning area, the gripping area is convenient for manual or tool operation, and the positioning area cooperates with an elastic buckle, a spring ring or a screw ring to realize quick locking and resetting.

[0090] When it is necessary to shorten the effective opening length or define the jetting section, the operator pushes the adjusting tube 330 to slide axially, so that its end edge partially blocks the first gas outlet 311, and the unblocked jetting section forms the effective opening. The smooth transition of the guide lip and the slope makes the velocity gradient of the jet flow from the opening section to the blocked section more smooth, reducing vortex shedding and backflow. As the blocking ratio increases, the jetting momentum is concentrated in the remaining section, and the linear density aerodynamic effect is enhanced, which is suitable for shorter seams or local strengthening working conditions; when it is necessary to restore full-length jetting, the adjusting tube 330 is returned to the initial position or a larger window is opened. The entire process does not require disassembly of the first pipe 310, and the change and fine tuning can be completed in the working position.

[0091] The coaxiality of the adjusting tube 330 and the first pipe 310 should be controlled within a small deviation range to avoid jet flow deflection and wall-attached dust accumulation. The matching gap should be stable in both hot and cold states, and the material matching and surface treatment should take into account the size rebound after thermal cycling. The locking mechanism needs to have anti-vibration and anti-jet reaction force capabilities, and can still reliably reproduce the angular and axial positions after long-term operation. It is recommended to maintain continuous curved surface contact or approximately smooth gap shape between the blocking edge and the edge of the first gas outlet 311 to reduce secondary throttling and noise.

[0092] The structure is suitable for production environments with frequent changes, multiple specifications of workpieces 40, and multiple seam lengths. When there are more dust, smoke, or metal particles, the adjusting tube 330 and the nozzle periphery should be cleaned regularly to maintain the smoothness of the blocking boundary and the flow guiding effect. In hot and humid or corrosive medium conditions, higher corrosion-resistant materials or surface protection should be used, and the integrity of the sealing element should be checked according to the maintenance period. To avoid direct washing by high-temperature splashes, a splash baffle or transparent observation window can be installed without affecting the adjustment operation.

[0093] In this embodiment, by using the technical means of setting a movable adjusting tube 330 outside the first pipe 310 and controllably blocking the first gas outlet 311 with a smooth guide edge, the effective opening length and the effective jetting section are flexibly adjusted, thereby effectively solving the problems in the prior art that the fixed jetting length is difficult to match different seam lengths and local strengthening requirements, and the non-target section is inefficiently jetted, resulting in energy dispersion and increased disturbance, and further achieving the technical effects of concentrating the jet flow momentum to the target position, making the back blowing gas curtain cover more suitable for the working condition, and realizing quick and reliable changeover and adjustment, and stable forming in multiple scenarios.

[0094] Please refer to Figure 1 In some embodiments, in order to avoid molten metal falling into the first gas outlet 311 during the welding process, the jetting direction of the first gas outlet 311 and the normal direction of the material placing plane 210 form an included angle of 15°-30°.

[0095] Specifically:

[0096] The first gas outlet 311 is arranged as a slit-shaped nozzle extending axially along the first pipe 310. To form an angle with the normal of the material placement plane 210, the nozzle seat where the nozzle is arranged is inclined relative to the pipe body, and the nozzle seat and the pipe are connected through an inclined surface transition, so that the center line of the nozzle is inclined relative to the normal. The outer lip of the nozzle is provided with a smooth flow guiding round corner, and the inner lip is provided with a wetting-resistant processing or an anti-adhesion coating to reduce the adhesion of molten droplets and stabilize the shear layer. To facilitate assembly and maintenance, a repeatable positioning reference surface is arranged between the nozzle seat and the pipe body, and a press fitting, screwing or positioning pin combination structure is used for fixation. A shallow groove type edge discharge can be arranged on both sides of the nozzle to suppress the wall-attached backflow at high flow rates. The nozzle material is preferably a heat-resistant and corrosion-resistant metal or composite material, and the inner cavity surface is finely polished to reduce the resistance along the way and reduce the risk of slag accumulation.

[0097] During welding, the first gas outlet 311 jet flows out in a direction at a predetermined angle with the normal of the material placement plane 210, and the momentum direction of the jet flow points to the slit opening 212 and the back of the joint. Since the jet flow is not aligned with the gravity direction of the upper molten pool, it forms an aerodynamic deflection of the molten droplet trajectory, reducing the probability of the molten droplet directly reaching the nozzle. The inclined jet generates a wall-attached effect at the outer lip of the nozzle, causing the boundary layer to slide along the surface of the tool 20 and pass over the nozzle opening, thereby forming a low capture zone near the nozzle. In combination with the outer lip flow guiding round corner, the splashes and micro-droplets flow around the nozzle without entering the nozzle. The operator adjusts the jet direction by aligning the reference surface of the tool 20 with the reference line of the nozzle after assembly or changeover, ensuring that the angle falls within the target range.

[0098] The setting of the jet direction depends on the angle accuracy between the center line of the nozzle and the normal of the material placement plane 210. During assembly, the angle should be calibrated based on the plane of the tool 20, and the repeatable positioning is ensured through positioning pins or inclined surface stops. The outer lip round corner radius and the inner lip chamfer of the nozzle need to match the jet speed interval to maintain sufficient jet wall adhesion while avoiding vortex shedding. The relative projection between the nozzle opening edge and the slit opening 212 should maintain high coincidence to avoid jet deviation from the back of the joint due to angle deviation. The nozzle surface treatment needs to consider oxidation resistance and adhesion resistance, and regular cleaning can maintain a stable boundary layer shape. If there is strong splashing in the working condition, a thin splash lip can be arranged above the nozzle to guide the flow in cooperation with the inclined jet.

[0099] The inclined jet arrangement is suitable for thin plate joint, lap joint and clamping scenarios where the back surface is close, especially in working conditions with frequent attitude changes or more splashes. The assembly site should have a reliable plane reference to calibrate the angle of the nozzle, and when the environment has a lot of smoke, it is recommended to cooperate with exhaust and filtration units to reduce the probability of particles entering the boundary layer of the nozzle. For high humidity and corrosive atmosphere, the nozzle and flow guiding components should be made of corrosion-resistant materials and have surface protection.

[0100] In this embodiment, the technical means of the first gas outlet 311 being inclined to the normal line of the material plane 210 and the flow guiding and anti-adhesion design at the outer lip and inner lip of the nozzle effectively solve the technical problem of molten droplets and splashes easily entering the nozzle along the gravity path or the backflow channel, causing clogging and disturbance of the spray flow, thereby achieving the technical effects of enhanced anti-falling capability of the nozzle area, more stable spray boundary layer, more continuous back-blowing effect, and significantly improved consistency and controllability of the weld back shaping.

[0101] Referring to Figure 4 and Figure 8 , in order to effectively control the excess height of the weld underside of the workpiece 40, a control method of the laser welding equipment is proposed, which specifically includes the following steps:

[0102] Step S100: Obtain the performance parameters of the workpiece 40 to be welded, and determine the welding parameters of the welding mechanism 10 and the first gas supply parameters according to the performance parameters of the workpiece 40 to be welded;

[0103] Step S200: Control the welding mechanism 10 to operate according to the welding parameters, and control the first gas source to operate according to the first gas supply parameters;

[0104] Step S300: Obtain the depth of the slit opening 212, the transfer distance from the first gas outlet 311 to the side of the slit opening 212 away from the material plane 210, and the turning angle formed by the jet direction of the first gas outlet 311 and the normal direction of the material plane 210;

[0105] Step S400: Determine the second gas supply parameters of the second gas source according to the depth of the slit opening 212, the transfer distance, and the turning angle;

[0106] In a preferred embodiment, step S500 can be performed after step S400: correcting the relationship between the gas flow parameters of the first gas outlet 311 and the second gas supply parameters.

[0107] Step S600: Control the second gas source to operate according to the second gas supply parameters.

[0108] Specifically:

[0109] Referring to Figure 5 , the step S100 of obtaining the performance parameters of the workpiece 40 to be welded and determining the welding parameters of the welding mechanism 10 and the first gas supply parameters according to the performance parameters of the workpiece 40 to be welded includes the following steps:

[0110] Step S110: the performance parameters at least include one or any combination of the following: base material type and grade, plate thickness, surface state and cleanliness, weld form and groove parameter, gap between seams, filler material and wire feeding specification, preheating / interpass temperature target, shielding gas type and purity, clamping / thermal restraint condition;

[0111] Step S120: based on the performance parameters, determine the welding parameters for controlling the welding mechanism 10 from the pre-set welding process library and / or empirical mapping relationship and / or mathematical model, the welding parameters at least include one of the following: laser power and / or energy density, welding speed, focal point position / defocusing amount, pulse frequency and duty cycle (such as pulse welding), swing amplitude and frequency (such as with swing), wire feeding speed and / or wire feeding temperature;

[0112] Step S130: based on the performance parameters, determine the first gas supply parameters for controlling the operation of the first gas source from the pre-set gas supply process library and / or empirical mapping relationship, the first gas supply parameters at least include one of the following: shielding gas type and / or purity, mass flow and / or volume fraction flow, gas supply pressure, distance and / or inclination angle of the gas blowing pipe 120 to the weld;

[0113] Step S140: impose manufacturer's calibration range and safety threshold constraints on the welding parameters and the first gas supply parameters, and output to the controller as target settings.

[0114] In step S110:

[0115] The base material type and grade directly determine the laser absorption rate, thermal conductivity, melting point, vapor pressure, and whether it is easy to produce pores or cracks; different alloy systems have significant differences in tolerance to heat input and shielding gas, which are the primary independent variables for subsequent power, speed, and gas schemes.

[0116] Plate thickness constraints target penetration and penetration mode; higher line energy or focal point strategy adjustment is needed as the plate thickness increases, otherwise it is difficult to stabilize the forming.

[0117] Surface state and cleanliness: oxidation film, oil stains can reduce the absorption rate or introduce pore sources, directly affecting the lower limit of the required energy density and shielding gas purity, flow.

[0118] Weld form and groove parameter affect effective irradiation area and heat coupling path; different butt joint, lap joint, corner joint and groove angle need different focal point position, swing and wire feeding cooperation.

[0119] The gap between the seams determines whether it needs to be widened by swing forming, whether it needs to be bridged by wire feeding, and the shear of the airflow above should not be too large to prevent the metal from falling down.

[0120] Filler material and wire feed specification affect deposition rate and metallurgical composition, which need to match the coupling relationship of wire feed speed, power and welding speed.

[0121] Preheating or interpass temperature target determines the thermal history of arc initiation and continuous welding, which is related to crack sensitivity and microstructure control, thereby inversely constraining energy and rhythm.

[0122] Gas type and purity: different gases have different thermal conductivity, ionization characteristics and density, which have a great influence on molten pool protection, plasma suppression and gas flow pattern; purity is related to back discoloration and inclusion risk.

[0123] Clamping and thermal constraint conditions determine the heat dissipation boundary and deformation constraint, which affect the required heat input and weaving strategy; rigid clamping and large heat sink will increase the demand for high power or reduce the welding speed.

[0124] The above parameters cover the key dimensions of "material, geometry, process, boundary condition", which are the necessary prerequisites for correctly mapping the experience library or model to "welding parameters" and "first gas parameters". The absence of any of the key dimensions may result in mismatch of linear energy, focal point and gas scheme, thereby causing incomplete penetration, sagging, porosity or back oxidation failure.

[0125] In step S120:

[0126] The determination method for determining the welding parameters for controlling the welding mechanism 10 (the cooperative process of the process library / mapping / model) from the preset welding process library and / or experience mapping relationship and / or mathematical model is as follows:

[0127] Preset process library lookup table: search for recommended intervals with material grade, plate thickness, joint type and groove as index; if the working condition falls between the library items, interpolate according to the main variables such as plate thickness and welding speed to obtain the initial parameter set.

[0128] Experience mapping relationship correction: combined with the gap between the seams, surface state, clamping heat sink, etc., apply regularized mapping for addition and subtraction correction, for example, increase the weaving amplitude or introduce wire feeding and correspondingly increase the power or reduce the welding speed if the gap is too large; moderately increase the energy density or require pretreatment if the surface is severely oxidized.

[0129] Mathematical model checking: use energy conservation and heat transfer approximation for quick checking, such as the correspondence between linear energy and target penetration depth, and the focal point position determines the spot diameter and thus the energy density; if necessary, use analytical or simplified numerical model to determine whether the current parameters can achieve the target penetration depth without overheating.

[0130] Form target setting: the corrected and checked parameters are within the equipment and safety boundaries, which are the target settings issued by the controller.

[0131] The reason why the welding parameters at least include the following parameters is that:

[0132] Laser power and / or energy density: determines the heat input per unit time and area, is the primary quantity for stable conduction welding or keyhole welding, and directly corresponds to the penetration and shape.

[0133] Welding speed and power jointly determine the linear energy; too high speed will lead to incomplete penetration, and too low speed will cause burn-through or excessive reinforcement.

[0134] Focal position or defocus amount changes the spot size and energy density distribution, controls the penetration and weld width, and is also an effective means to deal with the gap between the seams and the groove angle.

[0135] Pulse frequency and duty cycle are suitable for pulse or modulated welding, control the instantaneous peak power and heat cycle, and help to suppress spatter, refine the structure or avoid burn-through on thin plates.

[0136] The oscillation amplitude and frequency are used to widen the weld, homogenize the heat input, and bridge the gap, while improving the shape; when no oscillation is set, the amount can be zero.

[0137] Wire feed speed and / or wire feed temperature determine the deposition rate and filling synchronization, affect the molten pool volume and metallurgical matching; local preheating of the wire can improve wetting and stability.

[0138] These quantities constitute the minimum available set of "heat input, spatial distribution, time modulation, and material supply", which can be used independently or jointly as control variables to cover the main degrees of freedom of the shape and metallurgical quality.

[0139] In step S130:

[0140] The determination method of the first gas supply parameter for controlling the operation of the first gas source is as follows:

[0141] Process library selects gas types and purity: according to the material system and surface quality target, select the gas formula and required purity grade from the library, and give the reference flow and nozzle specification suggestion.

[0142] The mapping relationship sets the flow and pressure: taking the nozzle diameter, nozzle to weld distance, nozzle inclination angle, and welding speed as independent variables, it is mapped to the recommended volume flow or mass flow and gas supply pressure interval, so that the jet Reynolds number and the near-seam area oxygen threshold meet the requirements, while the downward shear on the molten pool is controlled within the limit.

[0143] Posture optimization under geometric constraints: combined with clamping interference and accessibility, the nozzle distance and angle are optimized within the feasible region, which prioritizes the protection gas envelope covering the weld and arc column area, and minimizes the downward pressure on the molten pool.

[0144] Check and boundary processing: check the length of the gas curtain, the width of the coverage and the turbulence tendency; if high-speed welding leads to insufficient follow-up ability, appropriately increase the flow or adjust the angle and distance.

[0145] The first gas supply parameter at least includes the following parameters for the following reasons:

[0146] The type and or purity of the protective gas determines the protection ability, plasma suppression and heat transfer characteristics, which relates to the surface color, inclusion and porosity risk.

[0147] The mass flow and or volume flow rate determines the replacement efficiency and disturbance resistance near the weld; too low protection is insufficient, and too high turns into turbulence and applies too much shear.

[0148] The gas supply pressure and nozzle pressure drop together determine the outlet velocity and jet stability, which are the basic variables of flow control and response speed.

[0149] The distance and / or angle of the blowing pipe 120 from the weld directly determines the shape of the gas envelope and the mechanical action on the molten pool; through the geometric posture, it can be compromised between sufficient protection and minimum depression.

[0150] These quantities together determine the "composition, intensity, shape, and direction of action" of the upper protective gas, which cooperates with the heat input parameters to ensure the metallurgical protection of the upper surface without excessive penetration of the molten pool.

[0151] In step S140:

[0152] The reason for applying the manufacturer's designated range and safety threshold constraints is:

[0153] Equipment consistency and repeatability: different equipment has deviations in power measurement, focused light path, nozzle pressure drop and flow coefficient; working within the manufacturer's designated range can ensure the traceability of "set quantity-actual quantity" and cross-equipment portability.

[0154] Hardware safety and life: exceeding the upper limit of power, duty cycle or gas pressure will cause overheating of optical elements, nozzle erosion, hose shedding and other failures; the lower limit will lead to unstable arc column, tempering or protection failure.

[0155] Process safety window control: limiting parameters within safety thresholds can avoid instability caused by environmental fluctuations and material batch differences, maintaining a "weldable and controllable" window area.

[0156] Regulations and quality compliance: there are often internal control or standard requirements for gas purity, leakage rate, equipment pressure rating, etc.; applying threshold values can ensure the consistency and compliance of mass production.

[0157] And facilitate closed-loop correction: first issue targets within the calibration range, and then make fine adjustments according to the sensor feedback, which can prevent the controller from drifting out of the safety zone in abnormal state, and improve the robustness.

[0158] In summary, by collecting material, geometry and boundary conditions in step S110, determining the welding parameters related to heat input and path based on process library, mapping rules and physical model in step S120, and determining the first gas supply parameters of the upper protective gas in the same way in step S130, and finally limiting the two types of parameters within the equipment calibration and safety threshold in step S140, a stable and repeatable prerequisite for subsequent bottom blowing calculation and collaborative control is provided, the forming discreteness is reduced, and the available width of the process window is improved.

[0159] Please refer to Figure 6 . The steps S300 of obtaining the depth of the slit opening 212, the transfer distance of the first gas outlet 311 away from the material placement plane 210 side of the slit opening 212, and the deflection angle formed by the jet direction of the first gas outlet 311 and the normal direction of the material placement plane 210 include the following steps:

[0160] Step S310, obtaining the depth of the slit opening 212, the depth of the slit opening 212 is defined as the distance from the surface of the material placement plane 210 to the boundary interface of the slit opening 212 away from the material placement plane 210 side in the normal direction of the material placement plane 210;

[0161] Step S320, obtaining the transfer distance, the transfer distance is defined as the shortest distance from the first gas outlet 311 jet port surface to the boundary interface of the slit opening 212 away from the material placement plane 210 side along the first gas outlet 311 jet center line direction;

[0162] Step S330, obtaining the deflection angle, the deflection angle is defined as the angle between the jet direction of the first gas outlet 311 and the normal direction of the material placement plane 210.

[0163] Wherein:

[0164] The method for obtaining the depth of the slit opening 212 in step S310 includes:

[0165] Geometric reading based on design / tooling 20 data: directly read the elevation difference between the material placement plane 210 reference and the distal boundary interface of the slit opening 212 in the tooling 20 three-dimensional model or machining drawing; used as the default value for initial setting and rapid changeover.

[0166] On-machine contact measurement: measure the height of the material placement plane 210 and the distal boundary of the slit with a contact depth gauge, a trigger probe or a surface roughness meter respectively, and the difference between the two is the depth; suitable for low-cost, high-robustness on-site review.

[0167] On-machine non-contact measurement: use a laser displacement sensor or a structured light / 3D profiler to first collect the elevation of the material placement plane 210, then point the light spot at the distal boundary of the slit, and calculate the depth by the difference between the two readings; suitable for narrow slits or conditions where contact is not convenient.

[0168] Visual calibration method: arrange a high-reflectivity strip or a reference block at the distal boundary of the slit, calibrate the camera and the tool 20 coordinate relationship, and then use parallax or a calibrated ruler to calculate the normal displacement difference to obtain the depth.

[0169] The above methods can be used alone or in combination with "designing the reading as the initial value and correcting the sensor measurement". To ensure consistency, the results can be stored in the controller after clamping changes and tool 20 maintenance.

[0170] It should be noted that the depth of the slit opening 212 determines the channel thickness and confinement effect of the airflow from the first air outlet 311 through the containment space 220 to the outlet, directly affecting the flow resistance, wall shear and dynamic pressure decay, and is one of the key independent variables for establishing the airflow transmission decay coefficient. If the depth is too large, the flow path loss and diffusion will be enhanced, and the pressure or flow rate of the second gas source needs to be increased; if the depth is too small, the jet may form strong scouring or backflow, and the supply needs to be reduced to avoid disturbing the molten pool. Therefore, the true depth must be obtained as the basis for subsequent parameter calculation.

[0171] The method for obtaining the transmission distance in step S320 includes:

[0172] Posture / pose calculation: the jet centerline direction and position of the nozzle end are converted to the tool 20 coordinate system through the pose of the robot or motion axis, encoder reading or nozzle installation reference; the shortest distance between the centerline as a parameterized ray and the "distal boundary surface" is calculated to obtain the transmission distance. This method is suitable for online calculation in automated production.

[0173] Visual positioning and geometric solution: the camera recognizes the nozzle end reference mark, combines the calibrated tool 20 boundary line, reconstructs the position relationship between the jet centerline and the distal boundary of the slit, and calculates the shortest distance between the two along the centerline direction.

[0174] Direct measurement and calibration: use a slender measuring needle, a feeler gauge or an endoscope with scale markings to measure the shortest distance to the distal boundary along the centerline direction as a debugging and checking means.

[0175] To enhance robustness, a hybrid strategy of "pose solving as main, visual or direct measurement spot check" is recommended, and the calculation is re-performed after nozzle replacement or position change of the adjusting pipe 330.

[0176] Need to be explained, the transfer distance represents the free path and diffusion path of the jet from the nozzle to the slit outlet, determines the strength of momentum diffusion, velocity decay and jet cross section widening, is the main factor of aerodynamic attenuation and action coverage. If the distance is too large, the jet dynamic pressure will be significantly attenuated and easily disturbed by the environment; if the distance is too small, it is easy to cause local strong flushing and noise, and increase the risk of molten droplet back suction. Accurate acquisition of the transfer distance can reasonably set the gas supply pressure, flow or pulse duty of the second gas source, so that the target dynamic pressure and velocity are reached at the slit outlet.

[0177] The method for obtaining the deflection angle in step S330 includes:

[0178] Direct reading of attitude angle: If the nozzle mounting seat has angle coding or inclination sensor, the included angle with the normal line of the tooling 20 can be directly read; or the included angle is calculated from the direction vector of the robot end in the tooling 20 coordinate and the normal line vector of the tooling 20.

[0179] Visual / Target method: Direction target is set on the nozzle, and nozzle direction vector is obtained by using calibration camera; the normal line of the placement plane 210 is derived from the tooling 20 reference, and the included angle of the two vectors is calculated.

[0180] Mechanical / gauge method: A mechanical angle ruler with scale or a digital angle gauge is placed against the nozzle reference surface and the tooling 20 plane to measure the included angle between them; it is used for on-site rapid calibration.

[0181] To ensure repeatability, a repeatable positioning inclined surface or indexing structure can be provided between the nozzle and the support, so that the included angle after each assembly falls within a predetermined range, and is reviewed by the above method.

[0182] Need to be explained, the deflection angle determines the inclination of the jet relative to the normal line of the placement plane 210, and further determines the momentum direction decomposition and wall sticking effect at the slit outlet. If the included angle is too small, the jet is more perpendicular to the placement plane 210, and although the upward component is large, it is easy to directly bring the molten droplet or splash into the nozzle; if the included angle is too large, the upward component is insufficient and the effective coverage area is shifted backward, which weakens the lifting of the back surface of the molten pool. Obtaining and controlling the included angle within the target range can not only inhibit the metal from entering the nozzle, but also form sufficient upward aerodynamic force and stable protective gas curtain at the outlet, which is a necessary condition to ensure the consistency of the back surface height and the forming.

[0183] In summary, the "slit opening 212 depth" of step S310, the "transfer distance" of step S320 and the "deflection angle" of step S330 together characterize the geometric channel and jet attitude from the first gas outlet 311 to the slit outlet, which is the minimum necessary geometric set for establishing the gas flow transfer decay relationship and determining the minimum necessary second gas supply parameters. Through the combination of design data reading and on-site measurement / calculation, the real values consistent with the current tooling 20 assembly, nozzle attitude and adjustment state can be obtained, providing accurate boundary conditions for subsequent gas supply parameter calculation and closed-loop control.

[0184] Referring to Figure 7 The step S400 of determining the second gas supply parameters of the second gas source according to the depth of the slit opening 212, the transfer distance and the deflection angle includes the following steps:

[0185] Step S410: determining the gas flow transfer decay coefficient according to the depth of the slit opening 212, the transfer distance and the deflection angle, the gas flow transfer decay coefficient reflecting the decay of gas flow momentum / kinetic pressure from the first gas outlet 311 to the outlet of the slit opening 212; the gas flow transfer decay coefficient is given by at least one of the pre-stored calibration curve, the empirical mapping relationship, the analytical / numerical model;

[0186] Step S420: determining the target back blowing index at the outlet of the slit opening 212 according to the preset forming quality target of the weld of the workpiece 40; the forming quality target includes at least one of the following or any combination thereof: upper limit of back surface excess height, penetration level and / or minimum penetration depth of weld root, allowable sag amount, oxygen / nitrogen content threshold of back surface protection zone; the target back blowing index includes at least one of the following: target kinetic pressure, target flow rate, target lifting force per unit length of joint and / or upper limit threshold of back surface excess height of the weld;

[0187] Step S430: solving the target back blowing index and the gas flow transfer decay coefficient to obtain the required target jetting condition at the first gas outlet 311, and determining the second gas supply parameters of the second gas source according to the target jetting condition, the second gas supply parameters including at least the gas supply pressure and flow rate of the second gas source.

[0188] Step S440: applying rated boundary and safety threshold limits to the second gas supply parameters to obtain the final second gas supply parameters.

[0189] Wherein:

[0190] In step S410, the gas flow transfer decay coefficient is determined according to the depth h of the slit opening 212, the transfer distance L and the deflection angle θ. The determination method is as follows:

[0191] The depth h, the transmission distance L, and the deflection angle θ of the slit opening 212 are taken as independent variables, and the attenuation coefficient κ is obtained by combining the known geometry and working conditions of the nozzle and the channel (the total effective area of the first gas outlet 311, the equivalent hydraulic diameter, the gas type and temperature, the nominal Reynolds number, and the surface roughness) in at least one of the following ways:

[0192] Pre-stored calibration curve: The dynamic pressure or centerline velocity at the slit outlet is measured offline at representative h, L, and θ grid points, and κ(h, L, θ) is established by comparing the dynamic pressure or velocity at the nozzle. During online operation, multi-dimensional interpolation is performed according to the current h, L, and θ.

[0193] Empirical mapping relationship: A monotonic or segmented function of κ=f(h / L, θ, Re, A_ratio, roughness) is fitted by regression / interpolation, which is consistent with physical laws, such as κ decreases when L increases or h increases, and κ decreases when θ deviates from the optimal wall attachment angle.

[0194] Analytical / numerical model: The kinetic energy loss equivalent method is used to superimpose the along-path friction and local loss, or a simplified jet attenuation model and wall attachment model are used to estimate the outlet dynamic pressure: q out ≈q noz / (1+∑ζ+4f·L e / D h ), where L e is the equivalent flow path related to h, L, and θ, and κ=q out / q noz .

[0195] The above three methods can be used alone or in combination, with the calibration curve as the main method, the analytical model for boundary correction, and the empirical mapping for non-standard point interpolation.

[0196] It should be noted that κ can reflect the momentum / dynamic pressure attenuation because κ is defined as the ratio of the same aerodynamic momentum at the slit outlet to that at the nozzle (such as the dynamic pressure ratio q out / q noz or the momentum flux ratio), which comprehensively includes the energy and momentum losses caused by channel confinement, jet diffusion, wall friction, geometric expansion and contraction, and direction deflection, and thus can directly quantify the attenuation from the first gas outlet 311 to the slit outlet. Including θ in the independent variables can reflect the influence of jet direction change on wall attachment and diffusion, and including h and L can reflect the dominant role of equivalent flow path and diffusion distance on attenuation.

[0197] In step S420, the target backblow index at the slit outlet is determined according to the forming quality target.

[0198] The forming quality target refers to the inspectable target or limit value set for the weld geometry and metallurgical quality, and at least includes one or a combination of the following: an upper limit of back reinforcement, a penetration level or a minimum root penetration, an allowable sag amount, and an oxygen / nitrogen content threshold value of the back protection zone. They directly correspond to product acceptance and failure modes: back reinforcement and sag reflect back forming, penetration and root penetration reflect structural integrity, and the oxygen / nitrogen threshold value reflects protection sufficiency.

[0199] According to the determination of the target back blowing index, the steps are as follows:

[0200] First, the aerodynamic or mechanical quantity most relevant to the target is selected as the "back blowing index", and then the target value or interval of the index at the slit outlet is calculated by the process library, experience mapping or model conversion. For example:

[0201] If the back reinforcement and sag amount are controlled, the target dynamic pressure or unit length lifting force at the slit outlet is taken as the index, so that it is sufficient to offset the combined force of the self-weight of the molten pool and the downward pressure of the upper airflow, and at the same time, it does not blow the weld.

[0202] If the penetration consistency is controlled, the upper and lower limit interval of the target dynamic pressure is given to avoid excessive root morphology instability caused by back blowing.

[0203] If the back oxidation is controlled, the target flow rate or minimum volume fraction flow rate is taken as the index to ensure that the replacement rate meets the oxygen / nitrogen threshold value requirement.

[0204] Therefore, the target back blowing index at least includes one of the following: target dynamic pressure, target flow rate, target lifting force per unit length of the slit, and / or upper limit threshold value of the weld underside reinforcement (for closed-loop criterion). These indexes can be directly obtained from the calibration library, or can be derived from a simplified mechanical / fluid model or inferred from online quality feedback.

[0205] Step S430 simultaneously solves the target jetting condition and determines the second gas supply parameter.

[0206] The simultaneous solution of the target jetting condition is as follows:

[0207] The target back blowing index (such as q out or v out ) is given at the slit outlet, and κ (h, L, θ) is known, and the target conditions of the jetting port can be inferred:

[0208] If the dynamic pressure index is used: q noz =q out / κ.

[0209] If the velocity index is used: v noz =v out / √κ q (when κ is defined as the dynamic pressure ratio).

[0210] After obtaining the target velocity or dynamic pressure of the nozzle, the nozzle volume flow rate and mass flow rate can be obtained by combining the total effective area A_noz of the nozzle and the gas density ρ (determined by the type and temperature of the gas): noz ·v noz , Qm=ρ·Qv.

[0211] The method for determining the second gas supply parameters is as follows:

[0212] Convert the required velocity / flow rate of the nozzle into the pressure difference requirement and set value of the second gas source:

[0213] In the subsonic and compressible effect is not significant working condition, approximately v noz ≈√(2ΔP / ρ)·C d , ΔP is obtained, and thus P2=P down +ΔP+along the way / local loss;

[0214] Obtain the mass or volume flow rate set Qm or Qv as the flow rate target of the second gas source;

[0215] For pulse or segmented injection, the target dynamic pressure or velocity window can be converted into the duty cycle and frequency;

[0216] The final output of the second gas supply parameters includes the original quantity that can be directly controlled by the gas source actuator and uniquely determines the nozzle outlet state, i.e., the gas supply pressure and flow rate.

[0217] The reason why the second gas supply parameters include the gas supply pressure and flow rate is that these two are the basic execution quantities that can be directly controlled on the gas source side, which determine the nozzle outlet velocity, dynamic pressure and flow rate, and thus determine the back blow index at the slit outlet; only one of them is often insufficient to cover the differences between devices and environmental fluctuations, and joint setting can achieve the target injection condition stably.

[0218] The reason why the rated boundary and safety threshold limit are applied in step S440 is that the second gas supply parameters need to meet the safety working window of the device and process:

[0219] Device limits and service life: pressure exceeding the rated value will cause pipeline and seal failure, and excessive flow rate will cause nozzle erosion and noise to rise sharply; too low will result in protection failure and unstable injection.

[0220] Fluid working condition boundary: avoid entering the compressible critical flow or acoustic howling area to prevent sudden flow field state transition.

[0221] Process stability: limit the parameters within the calibration window to absorb fluctuations in material batches, environmental temperature, etc., and avoid quality dispersion.

[0222] Compliance and consistency: meet internal quality standards and relevant safety specifications to make the results repeatable between multiple devices and multiple shifts.

[0223] Therefore, the obtained pressure, flow rate, and derived time sequence need to be upper and lower limited, and the final executable second gas supply parameters are obtained, and then are sent to the controller for execution.

[0224] In summary, the influence of geometry and posture on jet loss is quantified by obtaining the airflow transmission attenuation coefficient based on h, L, and θ in step S410; the forming quality target is converted into the target back blowing index at the slit outlet in step S420; the outlet target is back calculated to the nozzle target and converted into the second gas supply parameters by taking κ as a bridge in step S430; and the device and process safety window constraints are applied to form executable settings in step S440. The process establishes a calculable closed-loop link among "geometry, aerodynamics, and forming", and ensures that the back blowing intensity and direction match the actual working conditions.

[0225] Further, in some embodiments, the control method further comprises:

[0226] Please refer to Figure 8 . Step S500 corrects the relationship between the airflow parameters of the first gas outlet 311 and the second gas supply parameters, and the correction step includes:

[0227] Step S510 obtains the actual injection parameters at the first gas outlet 311 of the blowing assembly 30;

[0228] Step S520 compares the actual injection parameters with the target injection conditions to obtain a deviation value;

[0229] Step S530 modifies the second gas supply parameters based on the deviation value;

[0230] Step S540 confirms the final second gas supply parameters when the deviation value is less than a preset tolerance threshold; otherwise, the modification of the second gas supply parameters is continued.

[0231] Wherein:

[0232] In step S510, the "actual injection parameters" at the first gas outlet 311 are usually selected as one or more of the following as feedback quantities: dynamic pressure at the nozzle, outlet velocity, volume flow rate, mass flow rate, nozzle static pressure, and gas temperature. If "dynamic pressure" is selected as the control target, the dynamic pressure or the quantity that can be converted into dynamic pressure is preferred. The acquisition approach (optionally one or a combination of multiple approaches) is as follows:

[0233] Nozzle pressure measurement / speed measurement: a very small pressure tapping hole or a micro Pitot probe is arranged near the lip of the first gas outlet 311 to directly read the representative quantity of "injection intensity". In combination with a temperature point, a more accurate density estimation can be obtained, thereby indirectly indicating the speed and dynamic pressure.

[0234] Upstream flowmeter with chamber pressure sensor: install a mass or volume flowmeter between the second gas source and the blowing assembly 30, and read the chamber static pressure. Combine the known total effective area of the nozzle, and you can back-calculate the average blowing speed and dynamic pressure of the nozzle.

[0235] Special wind speed sensor: install a hot film / hot wire anemometer or ultrasonic time difference sensor near the stable section of the nozzle to directly read the speed or flow.

[0236] Soft measurement (estimator): when it is inconvenient to install a sensor, use the known calibration relationship between the source side pressure, valve opening, gas type and temperature, and nozzle flow coefficient to estimate the nozzle speed and flow online; continuously correct this estimate using the upstream measured value (such as chamber pressure or a small amount of time flow) to ensure that the deviation does not accumulate.

[0237] It should be noted that the jet flow may be pulsed or segmented, and the original signal will fluctuate up and down. The general approach is to use moving average or slight low-pass filtering to obtain the "stable comparable" average or root mean square value; at the same time, the original peak value is retained for safety monitoring.

[0238] The method of comparing "actual jet parameters" with "target jet conditions" in step S520 is as follows:

[0239] The target may be defined at the "slit outlet", while the actual measurement is easier to obtain at the "nozzle". Before comparison, use the "transfer coefficient" obtained in step S410 to convert the target to the nozzle side, or convert the measured value to the slit outlet side, and choose one to be consistent.

[0240] Deviation definition and tolerance:

[0241] Single index control: if only "dynamic pressure" is used as the control index, subtract "actual dynamic pressure" from "target dynamic pressure (converted to the same position)" to obtain a "larger / smaller" quantity.

[0242] Double index or multiple index: for example, if both dynamic pressure and flow are concerned, two deviations can be calculated respectively; during actual comparison, a "main index" (such as dynamic pressure) is usually set, and the other is used as a "constraint index" (such as flow within a certain range).

[0243] Tolerance band: to avoid control jitter, a permissible error band is given in advance. As long as the actual value falls within the error band, it is considered to meet the standard and does not need to be continuously corrected.

[0244] Comparison of pulsed / segmented jet: if the jet is pulsed, use "periodic average" or "equivalent average" for comparison, rather than instantaneous peak value; peak value is used for safety monitoring, and average value is used for process control.

[0245] Step S530 corrects the second gas supply parameter with the "deviation value" as follows:

[0246] The second gas supply parameter generally includes two controllable quantities: source-side gas supply pressure setting and source-side flow rate setting (or valve opening). The core idea of correction is:

[0247] If the actual value is lower than the target, the source-side pressure needs to be moderately increased, or the set flow rate needs to be increased;

[0248] If the actual value is higher than the target, the source-side pressure needs to be moderately decreased, or the set flow rate needs to be decreased.

[0249] To make the process both fast and stable, the following methods are commonly used (which can be used alone or in combination):

[0250] (1) Master-slave single-loop correction:

[0251] Select a master index (for example, dynamic pressure). In each control cycle:

[0252] According to the direction and size of the deviation, moderately increase or decrease the source-side pressure setting in proportion;

[0253] At the same time, make a small amplitude correction to the flow rate setting in the same direction to offset the differences caused by pipe and nozzle coefficients;

[0254] The setting change must be limited in amplitude and speed to prevent overshoot; if the setting reaches the upper or lower limit, the "anti-integral saturation" strategy should be used to avoid control accumulation bias.

[0255] (2) Simple decoupling double-loop correction:

[0256] If both dynamic pressure and average flow rate are important:

[0257] First, use the "sensitivity relationship" established during calibration to determine: pressure changes have a greater impact on dynamic pressure, and valve opening changes have a greater impact on flow rate;

[0258] Let the pressure loop mainly take responsibility for the dynamic pressure deviation, and the flow rate loop mainly take responsibility for the flow rate deviation;

[0259] Make "small step" corrections each time, and make fine adjustments based on the new deviation in the next cycle, and so on, until both deviations fall within their respective tolerance bands.

[0260] (3) Duty cycle correction for pulse injection:

[0261] If the injection is in pulse mode and the peak pressure cannot be increased:

[0262] Keep the peak pressure unchanged, and increase the average injection intensity by "increasing the duty cycle"; conversely, decrease the duty cycle to weaken it;

[0263] The duty cycle adjustment also has a maximum change step and upper and lower limits to avoid introducing low-frequency oscillations.

[0264] In addition, when performing safety and boundary constraints, regardless of the correction method, the updated pressure, flow rate, and duty cycle are all subject to upper and lower limits and a change rate constraint to ensure that the device limits are not triggered and the flow is not unstable. If the main indicator meets the requirements but the constraint indicator is out of range, the constraint indicator is pulled back into the safe range first, and then the main indicator is fine-tuned. For changes in environmental temperature and gas type, it is recommended to update the estimated value of the density or flow coefficient before correction to reduce repeated iterations.

[0265] When all monitored deviations are within the tolerance band for a certain number of consecutive sampling periods, the final second gas supply parameters are confirmed in step S540. If any deviation exceeds the tolerance, the correction is continued according to the above principles until the requirements are met.

[0266] In summary, the above-mentioned "measurement, comparison, and adjustment" correction steps feed the real jetting state at the first gas outlet 311 back to the control end through measurable or estimable physical quantities, and make small-step, limited-amplitude, and limited-speed adjustments to the source-side pressure and flow rate to stabilize the actual jetting parameters and approach the target jetting conditions. At the same time, the device and process safety boundaries are always constrained, ensuring that the backblow intensity is controllable and the forming quality is reproducible.

[0267] The above-described content in the specification is merely an example of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the content of the present application specification or exceed the scope defined by the present claims, and should belong to the protection scope of the present application.

Claims

1. A laser welding device, characterized in that, include: Welding mechanism, including: Controlled welding torch; An air blowing pipe positioned above the workpiece to be welded is used to provide protective gas to the weld seam. A first gas source, connected to the air blowing pipe, is used to supply protective gas to the air blowing pipe; The tooling has a material placement plane on its upper surface and a receiving space below the material placement plane. The material placement plane includes at least two welding areas for placing workpieces to be welded, and a slit opening communicating with the receiving space is provided between adjacent welding areas. The slit opening extends along the seam between adjacent workpieces to be welded. An air blowing assembly is disposed within the accommodating space, and the outer surface of the air blowing assembly is provided with a first air outlet facing the slit opening; The second gas source is connected to the air blowing assembly and is used to supply protective gas to the first air outlet so that the airflow from bottom to top acts on the molten metal at the joint between adjacent workpieces to be welded through the slit opening. The controller is electrically connected to the welding mechanism, the first gas source, and the second gas source respectively. The controller is configured to determine the second gas supply parameter of the second gas source based on the welding parameters of the welding mechanism and the first gas supply parameter of the first gas source when the welding mechanism is in operation, and control the operation of the second gas source based on the second gas supply parameter so as to provide upward aerodynamic force to the molten metal at the joint of adjacent workpieces through the bottom-up airflow during the welding process.

2. The laser welding equipment according to claim 1, characterized in that, The air blowing assembly includes: The first pipe fitting has a narrow, elongated, gap-shaped first air outlet continuously formed along its axial direction on its pipe wall, which communicates with its outer surface. The second pipe fitting is coaxially inserted into the first pipe fitting, so that an annular gap is formed between the outer surface of the second pipe fitting and the inner wall of the first pipe fitting; the second pipe fitting has a second air outlet communicating with the outer surface on its pipe wall, one end of the second pipe fitting is closed, and the other end of the second pipe fitting is connected to the second air source; At least two seals are disposed in the annular gap and divided into two groups. The two groups of seals are located on both sides of the first air outlet along the axial direction of the first pipe to block the two open ports formed by the annular gap in the axial direction of the first pipe, and form an annular air passage by the two groups of seals enclosing the inner wall of the annular gap on opposite sides. The second air outlet is offset relative to the first air outlet in the circumferential direction and is located between the two sets of seals.

3. The laser welding equipment according to claim 2, characterized in that, The air blowing assembly includes: An adjusting pipe is movably sleeved outside the first pipe fitting. The adjusting pipe is used to partially block the first air outlet in order to adjust the effective opening length and / or effective spray section of the first air outlet.

4. The laser welding equipment according to claim 1 or 2, characterized in that, The spray direction of the first air outlet forms an angle of 15° to 30° with the normal direction of the material placement plane.

5. A control method for the laser welding equipment according to any one of claims 1 to 4, characterized in that, Includes the following steps: Obtain the performance parameters of the workpiece to be welded, and determine the welding parameters of the welding mechanism and the first gas supply parameters based on the performance parameters of the workpiece to be welded; The welding mechanism is controlled to operate according to the welding parameters, and the first gas source is controlled to operate according to the first gas supply parameters. The depth of the slit opening, the transmission distance from the first air outlet to the side of the slit opening away from the material placement plane, and the angle between the injection direction of the first air outlet and the normal direction of the material placement plane are obtained. The second gas supply parameters of the second gas source are determined based on the depth of the slit opening, the transmission distance, and the turning angle. The second gas source is controlled to operate according to the second gas supply parameters.

6. The control method according to claim 5, characterized in that, The step of obtaining the performance parameters of the workpiece to be welded, and determining the welding parameters of the welding mechanism and the first gas supply parameters based on the performance parameters of the workpiece to be welded, includes the following steps: The performance parameters include at least one of the following or any combination thereof: base material type and grade, plate thickness, surface condition and cleanliness, weld type and bevel parameters, joint gap, filler material and wire feed specifications, preheating / interpass temperature target, shielding gas type and purity, clamping / thermal constraint conditions. Based on the performance parameters, the welding parameters for controlling the welding mechanism are determined from a pre-set welding process library and / or empirical mapping relationship and / or mathematical model. The welding parameters include at least one of the following: laser power and / or energy density, welding speed, focal position / defocusing amount, pulse frequency and duty cycle (e.g., for pulse welding), oscillation amplitude and frequency (e.g., with oscillation), wire feed speed and / or wire feed temperature. Based on the performance parameters, the first gas supply parameters for controlling the operation of the first gas source are determined from a preset gas supply process library and / or empirical mapping relationship. The first gas supply parameters include at least one of the following: the type and / or purity of the protective gas, the mass flow rate and / or the volume fractional flow rate, the gas supply pressure, and the distance and / or inclination angle between the gas blowing pipe and the weld. The parameters obtained from the welding parameters and the first gas supply parameters are subject to manufacturer-defined range and safety threshold constraints, and the results are output to the controller as target settings.

7. The control method according to claim 5, characterized in that, The steps for obtaining the depth of the slit opening, the transmission distance from the first air outlet to the side of the slit opening away from the material placement plane, and the angle between the injection direction of the first air outlet and the normal direction of the material placement plane include the following: The depth of the slit opening is obtained, and the depth of the slit opening is defined as the distance from the surface of the material placement plane to the side boundary of the slit opening away from the material placement plane in the normal direction of the material placement plane; The transmission distance is obtained, and the transmission distance is defined as the shortest distance from the first air outlet injection port surface to the side boundary surface of the slit opening away from the material placement plane along the injection center line direction of the first air outlet. The angle of change is obtained, and the angle of change is defined as the angle between the injection direction of the first air outlet and the normal direction of the material placement plane.

8. The control method according to claim 5, characterized in that, Determining the second gas supply parameters of the second gas source based on the depth of the slit opening, the transmission distance, and the turning angle includes the following steps: The airflow transmission attenuation coefficient is determined based on the depth of the slit opening, the transmission distance, and the angle of change of direction. The airflow transmission attenuation coefficient reflects the attenuation of airflow / dynamic pressure from the first air outlet to the outlet of the slit opening. The target back-blowing index at the slit opening is determined based on the preset forming quality target of the workpiece weld. The forming quality target includes at least one of the following or any combination thereof: the upper limit of the back reinforcement height, the penetration level and / or the minimum penetration depth at the weld root, the allowable sag, and the oxygen / nitrogen content threshold of the back protection zone. The target back-blowing index includes at least one of the following: the target dynamic pressure, the target flow rate, the target lifting force per unit length of the joint and / or the upper limit threshold of the weld underside reinforcement height. The target backblowing index and the airflow transmission attenuation coefficient are solved simultaneously to obtain the target injection conditions required at the first air outlet. The second air supply parameters of the second air source are determined based on the target injection conditions. The second air supply parameters include at least the air supply pressure and flow rate of the second air source.

9. The control method according to claim 8, characterized in that: The airflow transmission attenuation coefficient is given by at least one of the following: a pre-stored calibration curve, an empirical mapping relationship, and an analytical / numerical model; The second gas supply parameters are then subject to rated boundary and safety threshold limits to obtain the final second gas supply parameters.

10. The control method according to claim 8 or 9, characterized in that, It also includes a correction step for the relationship between the airflow parameters of the first outlet and the second supply parameters, the correction step including: Obtain the actual injection parameters at the first air outlet of the air blowing assembly; The actual injection parameters are compared with the target injection conditions to obtain the deviation value; The second gas supply parameter is corrected based on the deviation value; When the deviation value is less than the preset tolerance threshold, the final second gas supply parameter is confirmed; otherwise, the second gas supply parameter continues to be corrected.

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