Narrow-gap laser welding method and device for thick-wall materials

Abstract

The invention provides a narrow-gap laser welding method and device for a thick-wall material, and the method comprises the following operation steps: S1, after a narrow-gap groove is formed in a to-be-welded workpiece, an upright-focal flat-topped laser beam emitted by a laser head acts on the bottom and the side wall of the narrow-gap groove, a flux-cored wire fed into the groove is melted, molten drops are formed and are transited to a molten pool, and the narrow-gap groove is formed; filling the groove and solidifying to form a filling layer; s2, a laser sensor is used for obtaining the original geometrical shape of the weld joint, and the weld joint groove morphology with feature points is extracted through coordinate transformation and visual image analysis; s3, the shape of the weld groove is converted into a geometrical shape under a welding robot coordinate system through a control unit, the position of the welding robot is adjusted according to the depth and width of the groove, and it is ensured that the distances between the flux-cored wire and the two sides of the groove are the same; according to the method, the welding quality and the welding efficiency can be improved, the stability of the welding process can be remarkably improved, the incomplete fusion defect of the side wall is reduced, and therefore self-adaption and automatic welding of large-thickness materials are achieved.

Description

Technical Field

[0001] The invention relates to the field of welding technology, and in particular to a method and a device for narrow gap laser welding of thick-walled materials. Background Art

[0002] With the continuous development of my country's industry and science and technology, the manufacturing and application of major technical equipment have been gradually promoted, which has promoted the development of related industrial chains. Among these major equipment, large-thickness material structures are widely used, such as the core components of the International Thermonuclear Experimental Reactor (ITER project) toroidal field coil box, nuclear reactor pressure vessel, and nuclear power turbine rotor and other large structures. The thickness of the materials used in these structures is 200 to 300 mm, and the materials need to be connected through welding processes, and there are high requirements for the deformation and mechanical properties of the welded structure.

[0003] At present, the welding of medium and large thickness materials in the engineering field is still mainly based on traditional arc welding manufacturing processes. This type of technical solution generally has common problems such as complex process implementation, large welding heat input, difficulty in controlling post-weld deformation, and serious deterioration of the mechanical properties of weld joints. It has become one of the bottleneck technologies restricting the rapid development of large-scale equipment manufacturing industry.

[0004] High-energy beam welding technologies, such as laser beams, electron beams, and plasma beams, are very suitable for high-precision welding of thick materials due to their high heat source energy density, deep and narrow welds, and low welding stress and deformation. At present, China has mature domestic industrial 10,000-watt fiber laser manufacturing capabilities, which has promoted the research of 10,000-watt laser deep-melting welding in my country, giving full play to the advantages of laser welding with low stress and small deformation, and realizing efficient and high-precision manufacturing of large thick-walled structures. However, limited by the maximum output power of existing lasers, the existing high-power lasers are still unable to meet the needs of single-pass deep-melting welding of thick materials over 100 mm.

[0005] Narrow gap laser welding with wire filling combines the advantages of laser welding and narrow gap welding. Compared with traditional welding methods, it has the advantages of good welding quality, high efficiency and small deformation after welding. It is suitable for high-quality welding of thick materials of future nuclear power equipment. At present, although there have been attempts to weld thick plates with ultra-narrow gaps based on conventional Gaussian laser heat sources, the radiation range of Gaussian lasers is limited, the spread of the molten pool is poor, and the welded joints are prone to pores and defects such as lack of fusion between the side walls of the molten pool and the interlayers, which limits its industrial application.

[0006] In addition, when the Gaussian laser heat source is performing wire welding at the groove, the size and position of the weld groove often change due to welding deformation and other reasons, making it impossible for the laser beam and welding wire to be accurately aligned with the center of the weld, resulting in unfused sides of the weld or holes. This problem seriously affects the welding quality and efficiency. Summary of the invention

[0007] In view of this, the present invention proposes a narrow gap laser welding method and device for thick-walled materials to solve the problems of poor molten pool spreading, easy formation of pores at the weld, and easy unfusion between the side walls of the molten pool and the layers in the existing narrow gap laser wire filling welding process.

[0008] In a first aspect, the present invention provides a method for narrow gap laser welding of thick-walled materials, comprising the following steps:

[0009] S1. After a narrow gap groove is formed on the workpiece to be welded, the welding robot synchronously drives the wire feeding mechanism and the laser head to move, and the flux-cored welding wire is fed into the groove through the wire feeding mechanism. The upright focus flat-top laser beam emitted by the laser head acts on the bottom and side wall of the narrow gap groove, and the flux-cored welding wire is melted by heat conduction welding to form a molten droplet that transfers to the molten pool, fills the groove and solidifies to form a filling layer;

[0010] S2, using a laser sensor to obtain the original geometric shape of the weld, and extracting the weld groove morphology with characteristic points through coordinate transformation and visual image analysis;

[0011] S3, converting the weld groove morphology into a geometric shape in the welding robot coordinate system through the control unit, adjusting the position of the welding robot according to the groove depth and width, and ensuring that the flux-cored welding wire is at the same distance from both sides of the groove;

[0012] S4. After each layer is filled, use cleaning equipment to automatically remove impurities on the surface of the filling layer;

[0013] S5, measuring the interlayer temperature through the temperature sensor, and when the interlayer temperature drops to the specified temperature, the next layer is filled;

[0014] S6. Fill layer by layer until all filling is completed.

[0015] On the basis of the above technical solution, preferably, in step S1, it also includes positioning the wire feeding mechanism and the laser head, ensuring that the light outlet of the laser head and the wire feeding outlet of the wire feeding mechanism are located in the same plane, the light outlet of the laser head is perpendicular to the welding plane, the end of the flux-cored welding wire is close to one side of the forward direction of welding, and the center of the flat-top laser spot and the end of the flux-cored welding wire coincide with each other.

[0016] On the basis of the above technical solution, preferably, the flat-top laser beam spot diameter is 1 to 3 mm larger than the narrow gap groove width.

[0017] On the basis of the above technical solution, preferably, the angle between the flux-cored welding wire and the plane where the base weld is located is 20° to 60°.

[0018] On the basis of the above technical solution, preferably, the diameter of the flux-cored welding wire is 1.0-2.2 mm, the wire feeding speed of the flux-cored welding wire is 4-9 m / min, the flux-cored welding wire includes a metal sheath and a flux core filled inside, and the flux core includes iron powder, deoxidizer, alloy elements, slag forming agent and gas forming components.

[0019] On the basis of the above technical solution, preferably, the shape of the narrow gap groove is I-shaped, U-shaped or V-shaped with a groove surface angle of 1-3°, and the width of the narrow gap groove is 3-10 mm.

[0020] On the basis of the above technical solution, preferably, a plurality of grooves are arranged on the side wall of the narrow gap groove at intervals in the reverse direction along its height, and the depth of the grooves is 0.5 mm to 2 mm.

[0021] On the basis of the above technical scheme, preferably, in step S3, the Z coordinate of the welding robot is determined according to the current groove depth, so that the distance between the laser head and the bottom of the groove is kept constant to ensure that the laser spot size is always consistent, and the centerline position of the groove is determined according to the current groove width, and the XY coordinates of the welding robot are determined to ensure that the distance between the flux-cored welding wire and both sides of the groove is the same, and then the XYZ coordinates of the next position of the welding robot are transmitted to the robot controller and converted into a tracking path in the welding robot coordinate system. The welding robot continues to perform narrow gap laser wire filling welding according to the new path.

[0022] On the basis of the above technical solution, preferably, during the welding process, the molten pool is protected by using a shielding gas volume of 10 to 30 L / min, the shielding gas is nitrogen or argon, and the flow direction of the shielding gas is at an angle of 30° to 45° to the plane where the base weld is located.

[0023] In a second aspect, the present invention provides a narrow gap laser welding device for thick-walled materials, which is used to implement the narrow gap laser welding method for thick-walled materials described in the first aspect, and the narrow gap laser welding device includes:

[0024] A laser head is used to emit a flat-top laser beam toward the narrow gap groove in a vertical direction to form a flat-top laser spot at the weld groove;

[0025] A wire feeding mechanism, used to provide flux-cored welding wire to the weld groove at the flat-top laser spot;

[0026] A welding robot, whose execution end is connected to a laser head and a wire feeding mechanism, and is used to drive the laser head and the wire feeding mechanism to move in a three-dimensional space;

[0027] A laser sensor is fixedly mounted on the execution end of the welding robot to obtain the geometry of the weld;

[0028] The temperature sensor is fixedly installed at the execution end of the welding robot to obtain the interlayer temperature at the weld;

[0029] A control unit, used for converting the weld groove morphology into a geometric shape in a welding robot coordinate system;

[0030] The robot controller is used to control the welding robot to execute a new welding path according to the instructions of the control unit so that the flux-cored welding wire is at the same distance from both sides of the groove.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The narrow gap laser welding method for thick-walled materials disclosed in the present invention utilizes a flat-top laser beam with positive defocusing, uses flux-cored welding wire as a filling material, and performs narrow gap laser wire welding on thick materials through a thermal conduction laser welding method. At the same time, the weld shape is obtained through a laser sensor, and the weld position deviation problem caused by welding deformation of the workpiece to be welded is corrected in real time. This method can not only improve welding quality and welding efficiency, but also significantly improve the stability of the welding process and reduce the occurrence of side wall unfused defects, thereby realizing adaptive and automated welding of thick materials.

[0033] (2) A flat-top laser beam is used to evenly distribute the energy in the spot area, avoiding the situation where the center energy of the traditional Gaussian beam is too high and the edge energy is too low. The material is heated evenly, local overheating and uneven heat input are reduced, and the uneven energy distribution of the molten pool is improved. By reducing the temperature gradient difference between the center and the edge of the molten pool, the residence time of the high-temperature liquid metal in the molten pool is prolonged, the lateral fluidity of the liquid metal is improved, and the wetting and spreading of the high-temperature liquid metal to the side wall is promoted, the weld formation is improved, and the side wall unfused defects are reduced.

[0034] (3) Flux-cored wire is used for narrow gap laser welding. During the welding process, the slag-forming agent components (such as SiO2, TiO2, Al2O3, etc.) in the flux-cored wire will undergo welding metallurgical chemical reactions, increase the oxygen content in the molten droplet and the molten pool, reduce the surface tension of the liquid metal and slag, and make the molten pool flow more easily from the center to the surrounding area, thereby improving the wettability of the liquid metal on the side wall of the narrow gap groove, effectively reducing the defects of unfused side wall of the weld, and improving welding efficiency.

[0035] (4) By setting up a laser sensor, the weld groove morphology is tracked in real time, the groove depth is measured, and the position of the laser head is adjusted in real time to keep the distance between the laser head and the bottom of the groove constant, so as to ensure that the size of the flat-top laser spot is always consistent. The weld groove size and position changes caused by the welding deformation of the workpiece to be welded are corrected in real time, and the welding path of the welding robot is adjusted in real time to ensure that the deviation between the center of the laser spot and the center of the weld groove is small enough to avoid unfusion or holes on both sides of the weld, improve the welding quality, and realize adaptive welding.

[0036] (5) By aligning the center of the flat-top laser spot with the end of the flux-cored wire near the welding forward direction, it is possible to ensure that the laser energy fully acts on the welding wire, causing the welding wire to melt quickly, and the molten material can smoothly transition to the molten pool to fill the weld, which not only improves the welding efficiency, but also ensures the welding quality and reduces welding defects such as lack of fusion and porosity.

[0037] (6) The diameter of the flat-top laser beam spot is 1 to 3 mm larger than the narrow gap groove width. With this setting, the laser spot can fully cover the bottom and both side walls of the groove. This allows the laser energy to be concentrated not only at the center of the groove, but also to effectively irradiate the side walls of the groove. This comprehensive coverage helps ensure that all parts of the groove are evenly heated during each layer of welding, thereby achieving a stable fusion effect and reducing incomplete fusion and other welding defects.

[0038] (7) By providing a plurality of grooves at intervals along the height of the side wall of the narrow gap groove, the presence of the grooves increases the contact area between the weld metal and the base material of the workpiece to be welded, which helps to improve the fusion effect of the molten pool and enhance the mechanical strength and density of the weld. The grooves help to release and evenly distribute the welding stress during the welding process, reduce the welding stress concentration, and reduce the risk of welding cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a flow chart of the narrow gap laser welding method disclosed in the present invention;

[0041] Figure 2 It is a schematic diagram of the narrow gap laser welding device disclosed in the present invention;

[0042] Figure 3 for Figure 2 Sectional view at AA;

[0043] Figure 4 for Figure 2 Enlarged view of point B in the middle;

[0044] Reference numerals:

[0045] 1. Laser head; 11. Flat-top laser beam; 2. Wire feeding mechanism; 3. Flux-cored welding wire; 31. Molten droplet; 4. Welding robot; 5. Laser sensor; 6. Temperature sensor; 7. Control unit; 9. Robot controller; 10. Workpiece to be welded; 101. Groove; 102. Filling layer; 103. Molten pool; 104. Groove; 11. Shielding gas duct; 110. Shielding gas. DETAILED DESCRIPTION

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] like Figure 1 As shown, combined Figure 2-4 The embodiment of the present invention discloses a narrow gap laser welding method for thick-walled materials, including the following steps:

[0048] Step S1, after the narrow gap groove 101 is formed on the workpiece 10 to be welded, the wire feeding mechanism 2 and the laser head 1 are synchronously driven to move by the welding robot 4, the flux-cored welding wire 3 is fed into the groove 101 by the wire feeding mechanism 2, and the positive defocused flat-top laser beam 11 emitted by the laser head 1 acts on the bottom and side wall of the narrow gap groove 101, and the flux-cored welding wire 3 is melted by heat conduction welding to form a molten droplet 31 that transitions to the molten pool 103, fills the groove 101 and solidifies to form a filling layer 102;

[0049] Specifically, after the narrow gap groove 101 is formed on the workpiece 10 to be welded, a welding path is reasonably planned according to the shape and size of the groove 101. According to the planned path, the front wire feeding method is adopted to melt the flux-cored welding wire 3 through the positive defocused flat-top laser beam 11 to fill the groove 101.

[0050] By using a flat-top laser beam 11, the energy in the spot area is evenly distributed, avoiding the situation where the center energy of the traditional Gaussian beam is too high and the edge energy is too low, uniformly heating the material, reducing the problems of local overheating and uneven heat input, and improving the uneven energy distribution of the molten pool 103. By reducing the temperature gradient difference between the center and the edge of the molten pool 103, the residence time of the high-temperature liquid metal in the molten pool 103 is extended, the lateral fluidity of the liquid metal is improved, the wetting and spreading of the high-temperature liquid metal to the side wall is promoted, the weld formation is improved, and the side wall unfused defects are reduced.

[0051] In this embodiment, the mechanical properties (such as yield strength, tensile strength, elongation, impact toughness, etc.) of the flux-cored welding wire 3 match those of the workpiece 10 to be welded, and the chemical composition is similar, but the content of alloy elements can also be appropriately increased to improve the mechanical properties of the welding wire.

[0052] As some preferred embodiments, the flux-cored welding wire 3 is composed of a metal outer skin and a flux core filled inside, and the flux core includes iron powder, a deoxidizer, alloy elements, a slag-forming agent and a gas-forming component.

[0053] Among them, iron powder is the main filling material of the flux-cored welding wire 3, which increases the metal content of the weld. Deoxidizer: such as silicon (Si), manganese (Mn), etc., used to remove oxygen in the molten pool 103, prevent the formation of oxides in the weld, and improve the welding quality. Alloy elements: such as chromium (Cr), nickel (Ni), molybdenum (Mo), etc., according to the requirements of the welding material, specific alloy elements are added to improve the corrosion resistance, strength and wear resistance of the weld.

[0054] Slag-forming agents: such as silicon dioxide (SiO2), calcium oxide (CaO), titanium dioxide (TiO2) and aluminum oxide (Al2O3), are used to form protective slag, which covers the surface of the molten pool 103 to prevent the molten pool 103 from contacting with the air and reduce oxidation.

[0055] Gas-generating components: such as calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), decompose to generate gas during welding, forming a gas protection layer, further reducing oxidation, and improving the weld surface formation while generating gas, avoiding the formation of pores, unfused, and slag inclusion defects. Carbonates decompose into CO / CO2 gas and corresponding oxides during the formation stage of the molten droplet 31. The gas can prevent air from invading the molten droplet 31 to cause pores, and the oxide can reduce the surface tension of the molten droplet 31, adjust the wettability of the molten pool 103 during solidification, and improve the weld formation.

[0056] Flux-cored welding wire 3 is used for narrow gap laser welding. During the welding process, the slag-forming agent components (such as SiO2, TiO2, Al2O3, etc.) in the flux-cored welding wire 3 will undergo welding metallurgical chemical reactions, increase the oxygen content in the molten droplet 31 and the molten pool 103, reduce the surface tension of the liquid metal and the slag, and make the molten pool 103 flow more easily from the center to the surroundings, thereby improving the wettability of the liquid metal to the side wall of the narrow gap groove 101, effectively reducing the defects of unfused side wall of the weld, and improving welding efficiency.

[0057] As the flat-top laser beam 11 and the flux-cored welding wire 3 travel, the workpiece 10 to be welded is deformed due to uneven heating and uneven stress distribution, the welding trajectory deviates from the center of the groove 101, and the welding wire deviates to one side wall, resulting in a side wall unfused defect.

[0058] To this end, this embodiment also solves the problem through the following operation method.

[0059] Step S2: Use the laser sensor 5 to obtain the original geometric shape of the weld, and extract the shape of the weld groove 101 with characteristic points through coordinate transformation and visual image analysis.

[0060] Specifically, the laser sensor 5 identifies the weld position, obtains the original geometric shape of the weld, obtains the geometric shape in the sensor coordinate system after coordinate transformation, and then obtains an image with feature points through visual image analysis stages such as filtering. After feature extraction, the morphology of the filled weld groove 101 is obtained.

[0061] Through precise weld morphology extraction, accurate data can be provided for subsequent welding robot 4 path planning, ensuring the stability and consistency of the welding process and improving welding accuracy.

[0062] Step S3, the control unit 7 converts the weld groove 101 morphology into a geometric shape in the coordinate system of the welding robot 4, and adjusts the position of the welding robot 4 according to the depth and width of the groove 101 to ensure that the flux-cored welding wire 3 is at the same distance from both sides of the groove 101.

[0063] Specifically, the control unit 7 converts the morphology of the weld groove 101 into a geometric shape in the coordinate system of the welding robot 4, determines the Z coordinate of the welding robot 4 according to the current depth of the groove 101, keeps the distance between the laser head 1 and the bottom of the groove 101 constant to ensure that the laser spot size always remains consistent, and determines the centerline position of the groove 101 according to the current width of the groove 101, determines the XY coordinates of the welding robot 4 to ensure that the distance between the flux-cored welding wire 3 and both sides of the groove 101 is the same, and then transmits the XYZ coordinates of the next position of the welding robot 4 to the robot controller 9 and converts it into a tracking path in the coordinate system of the welding robot 4. The welding robot 4 continues to perform narrow gap laser wire filling welding according to the new path.

[0064] By setting the laser sensor 5, the morphology of the weld groove 101 is tracked in real time, the depth of the groove 101 is measured, and the position of the laser head 1 is adjusted in real time to keep a constant distance between the laser head 1 and the bottom of the groove 101 to ensure that the size of the flat-top laser spot is always consistent, and the size and position changes of the weld groove 101 caused by the welding deformation of the workpiece 10 to be welded are corrected in real time, and the welding path of the welding robot 4 is adjusted in real time to ensure that the deviation between the center of the laser spot and the center of the weld groove 101 is small enough to avoid unfusion or holes on both sides of the weld, improve the welding quality, and realize adaptive welding.

[0065] Step S4, after each layer of filling is completed, a cleaning device is used to automatically remove impurities on the surface of the filling layer 102; this arrangement can keep the surface of each layer of filling clean, avoid impurities affecting the welding quality of the next layer, ensure the firmness and consistency of the interlayer bonding, and improve the quality of the overall weld.

[0066] Step S5, the interlayer temperature is measured by the temperature sensor 6, and when the interlayer temperature drops to the specified temperature, the next layer is filled. In this embodiment, the interlayer temperature is controlled at 150-250° C. During welding, each layer is welded at a suitable temperature by controlling the interlayer temperature, avoiding thermal stress and deformation, and improving the stability of the welding process and the mechanical properties of the weld.

[0067] Step S6, filling layer by layer until all filling is completed. The layer-by-layer filling method ensures the controllability and stability of the welding process, and finally forms a high-quality weld, which is suitable for the welding requirements of thick-walled materials and significantly improves the welding efficiency and the strength of the welded joint.

[0068] As some preferred embodiments, in step S1, to ensure the accuracy and consistency of welding, the wire feeding mechanism 2 and the laser head 1 are positioned so that the light outlet of the laser head 1 and the wire feeding outlet of the wire feeding mechanism 2 are located in the same plane. This helps to accurately control the relative position of the laser and the welding wire, ensuring that the laser energy is concentrated in the melting area of ​​the welding wire, thereby improving the welding efficiency and weld quality.

[0069] The light outlet of the laser head 1 is perpendicular to the welding plane, ensuring that the laser beam acts on the welding area at the best angle, so that the laser energy can be evenly distributed in the welding area. In addition, the end of the flux-cored welding wire is close to the side of the welding forward direction, and the center of the flat-top laser spot and the end of the flux-cored welding wire are overlapped. This method can ensure that the laser energy fully acts on the welding wire, so that the welding wire melts quickly, and the melted material can smoothly transition to the molten pool 103 to fill the weld. This method not only improves the welding efficiency, but also ensures the welding quality and reduces the generation of welding defects such as lack of fusion and pores.

[0070] As some preferred embodiments, the spot diameter of the flat-top laser beam 11 is 1 to 3 mm larger than the width of the narrow gap groove 101. With this arrangement, the laser spot can fully cover the bottom and both side walls of the groove 101. This allows the laser energy to be concentrated not only at the center of the groove 101, but also to be effectively irradiated to the side walls of the groove 101. This comprehensive coverage helps ensure that each part of the groove 101 is evenly heated during each layer of welding, thereby achieving a stable fusion effect and reducing lack of fusion and other welding defects.

[0071] In the process of welding thick-walled materials, welding is usually performed in a layer-by-layer filling manner. As the number of welding layers increases, the laser head 1 needs to move upward layer by layer, and the diameter of the laser spot can be adaptively adjusted according to the changes in the groove 101. This adjustment can be achieved through the control system of the laser head 1, so as to maintain the optimal ratio of the spot diameter to the groove 101 width at different welding heights and groove 101 widths. The adaptive adjustment enables the laser spot to always cover the key area of ​​the groove 101, thereby ensuring uniform energy distribution during welding, reducing welding defects, and improving welding efficiency.

[0072] As some preferred embodiments, the angle between the flux-cored welding wire 3 and the plane where the base weld is located is 20° to 60°. The appropriate angle enables the flux-cored welding wire 3 to better fuse with the underlying weld and reduce welding defects such as lack of fusion. By controlling the wire feeding angle of the flux-cored welding wire 3, the fluidity and stability of the molten pool 103 can be optimized, a uniform weld can be formed, and the mechanical properties and forming quality of the weld can be improved. An angle between 20° and 60° helps the flux-cored welding wire 3 to effectively cooperate with the laser energy during welding, ensuring uniform filling of each layer of the weld.

[0073] In this embodiment, the diameter of the flux-cored welding wire 3 is 1.0-2.2 mm. By properly selecting the diameter of the welding wire, the requirements of different welding tasks can be met, the uniformity and high mechanical properties of the weld can be ensured, and various complex welding environments and requirements can be adapted. The wire feeding speed of the flux-cored welding wire is 4-9 m / min. By properly setting the wire feeding speed, the welding rate can be increased while meeting the weld quality.

[0074] In this embodiment, the flat-top laser beam power is 5-8 kW, which can be determined according to the width of the groove.

[0075] As some preferred embodiments, the narrow gap groove 101 has an I-shape, a U-shape, or a V-shape with a groove 101 surface angle of 1-3°.

[0076] The I-type groove 101 refers to a straight groove 101 without any inclination or angle. The welding edges of the two materials to be welded are parallel and perpendicular to the material surface. This type of groove 101 is suitable for materials with small thickness or small welding filling amount. The advantages of the I-type groove 101 are simple processing and uniform filling of the weld metal during welding, but on thick-walled materials, higher laser power and more filling material may be required.

[0077] The U-shaped groove 101 has a circular arc bottom, which makes it easier to fill metal during welding and forms a smooth transition zone. The U-shaped groove 101 is suitable for occasions requiring higher welding quality and larger welding thickness. It can provide better mechanical properties and fatigue strength, and is suitable for projects requiring higher welding tightness and strength.

[0078] The V-groove 101 has a certain groove 101 face angle (1-3°) to enable better fusion at the weld root. This design facilitates the formation of the molten pool 103 and the flow of metal during welding. The V-groove 101 with the groove 101 angle is suitable for welding thicker materials, provides a gradually changing welding area, helps reduce welding stress concentration, and improves the mechanical properties of the weld.

[0079] In this embodiment, the width of the narrow gap groove 101 is 3 to 10 mm. The width of the groove 101 can be selected according to the different thickness of the material, so as to ensure the quality and mechanical properties of the weld. According to the shape and width of the groove 101, the flux-cored wire 3 with a suitable diameter and composition is selected to ensure sufficient and uniform filling metal during welding.

[0080] As some preferred embodiments, a plurality of grooves 104 are arranged at intervals on the side wall of the narrow gap groove 101 along the height reverse direction thereof, and the depth of the grooves 104 is 0.5 mm to 2 mm. Thus, the presence of the grooves 104 increases the contact area between the weld metal and the substrate of the workpiece 10 to be welded, helps to improve the fusion effect of the molten pool 103, and enhances the mechanical strength and density of the weld. The grooves 104 help to release and evenly distribute the welding stress during the welding process, reduce the welding stress concentration, and reduce the risk of welding cracks.

[0081] As some preferred embodiments, during the welding process, the molten pool 103 is protected by using a shielding gas 110 of 10 to 30 L / min, and the shielding gas 110 is nitrogen or argon. The shielding gas 110 can effectively isolate oxygen and moisture in the air, prevent oxidation and other chemical reactions during welding, and ensure the purity and mechanical properties of the weld. In this embodiment, the shielding gas blowing flow direction is toward the welding movement direction V. Specifically, the shielding gas, the flux-cored welding wire and the laser beam are located in the same vertical plane, and the shielding gas and the flux-cored welding wire are located on both sides of the laser beam.

[0082] By setting the flow direction of the shielding gas 110 and the plane where the base weld is located at an angle of 30° to 45°, the shielding gas 110 can be effectively guided to cover the entire molten pool 103 area to form a stable protective environment. This angle can ensure that the shielding gas 110 forms a uniform airflow layer above the molten pool 103, avoid gas turbulence and uneven protection area, thereby improving welding quality. In this embodiment, the shielding gas 110 is provided by a shielding gas duct 11 provided on the welding robot.

[0083] The present invention also provides a narrow gap laser welding device for thick-walled materials, Figure 2-4As shown, it includes a laser head 1, a wire feeding mechanism 2, a welding robot 4, a laser sensor 5, a temperature sensor 6, a control unit 7 and a robot controller 9.

[0084] The laser head 1 is used to emit a flat-top laser beam 11 in a vertical direction toward the narrow gap groove 101 to form a flat-top laser spot at the weld groove 101; a flat-top laser spot is formed at the weld groove 101 to ensure uniform distribution of laser energy and improve welding quality.

[0085] A wire feeding mechanism 2, used for providing a flux-cored welding wire 3 to the weld groove 101 at the flat-top laser spot;

[0086] The welding robot 4, whose execution end is connected to the laser head 1 and the wire feeding mechanism 2, is used to drive the laser head 1 and the wire feeding mechanism 2 to move in three-dimensional space; ensure the automation and accuracy of the welding process, and realize the tracking of complex welding paths.

[0087] The laser sensor 5 is fixedly arranged at the execution end of the welding robot 4 and is used to obtain the geometric shape of the weld; by real-time monitoring the morphology of the weld groove 101, feedback data is provided to adjust the welding path.

[0088] The temperature sensor 6 is fixedly arranged at the execution end of the welding robot 4 and is used to obtain the interlayer temperature at the weld; monitor the temperature change during the welding process, prevent overheating or uneven cooling, and ensure the welding quality.

[0089] The control unit 7 is used to convert the weld groove 101 morphology into a geometric shape in the coordinate system of the welding robot 4; process the data from the laser sensor 5, generate new welding path information, and ensure that the welding robot 4 can accurately perform the welding task.

[0090] Specifically, the control unit 7 converts the morphology of the weld groove 101 into a geometric shape in the coordinate system of the welding robot 4, determines the Z coordinate of the welding robot 4 according to the current depth of the groove 101, keeps the distance between the laser head 1 and the bottom of the groove 101 constant to ensure that the laser spot size always remains consistent, and determines the centerline position of the groove 101 according to the current width of the groove 101, determines the XY coordinates of the welding robot 4 to ensure that the distance between the flux-cored welding wire 3 and both sides of the groove 101 is the same, and then transmits the XYZ coordinates of the next position of the welding robot 4 to the robot controller 9, so that the robot controller 9 controls the welding robot 4 to execute a new path according to the new coordinate information.

[0091] The robot controller 9 is used to control the welding robot 4 to execute a new welding path according to the instruction of the control unit 7, so that the distance between the flux-cored welding wire 3 and both sides of the groove 101 is the same.

[0092] The narrow gap laser welding device disclosed in the present invention utilizes a flat-top laser beam 11 with positive defocusing, uses a flux-cored welding wire 3 as a filling material, and performs narrow gap laser wire welding on thick materials by thermal conduction laser welding. At the same time, the weld shape is obtained by a laser sensor 5, and the weld position deviation problem caused by welding deformation of the workpiece 10 to be welded is corrected in real time. The device can not only improve welding quality and welding efficiency, but also significantly improve the stability of the welding process and reduce the generation of side wall unfused defects, thereby realizing adaptive and automatic welding of thick nuclear power materials.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A narrow gap laser welding method for thick-walled materials, characterized in that: The steps are as follows: S1. After a narrow gap groove is formed on the workpiece to be welded, the welding robot synchronously drives the wire feeding mechanism and the laser head to move, and the flux-cored welding wire is fed into the groove through the wire feeding mechanism. The upright focus flat-top laser beam emitted by the laser head acts on the bottom and side wall of the narrow gap groove, and the flux-cored welding wire is melted by heat conduction welding to form a molten droplet that transfers to the molten pool, fills the groove and solidifies to form a filling layer; S2, using a laser sensor to obtain the original geometric shape of the weld, and extracting the weld groove morphology with characteristic points through coordinate transformation and visual image analysis; S3, converting the weld groove morphology into a geometric shape in the welding robot coordinate system through the control unit, adjusting the position of the welding robot according to the groove depth and width, and ensuring that the flux-cored welding wire is at the same distance from both sides of the groove; S4. After each layer is filled, use cleaning equipment to automatically remove impurities on the surface of the filling layer; S5, measuring the interlayer temperature through the temperature sensor, and when the interlayer temperature drops to the specified temperature, the next layer is filled; S6. Fill layer by layer until all filling is completed.

2. The narrow gap laser welding method for thick-walled materials according to claim 1, characterized in that: In step S1, it also includes positioning the wire feeding mechanism and the laser head to ensure that the light outlet of the laser head and the wire feeding outlet of the wire feeding mechanism are located in the same plane, the light outlet of the laser head is perpendicular to the welding plane, the end of the flux-cored welding wire is close to the side of the welding forward direction, and the center of the flat-top laser spot and the end of the flux-cored welding wire coincide with each other.

3. The narrow gap laser welding method for thick-walled materials according to claim 2, characterized in that: The flat-top laser beam spot diameter is 1 to 3 mm larger than the narrow gap groove width.

4. The narrow gap laser welding method for thick-walled materials according to claim 2, characterized in that: The angle between the flux-cored welding wire and the plane where the base weld is located is 20° to 60°.

5. The narrow gap laser welding method for thick-walled materials according to claim 1, characterized in that: The diameter of the flux-cored welding wire is 1.0-2.2 mm, the wire feeding speed of the flux-cored welding wire is 4-9 m / min, the flux-cored welding wire comprises a metal sheath and a flux core filled inside, and the flux core comprises iron powder, a deoxidizer, alloy elements, a slag-forming agent and a gas-forming component.

6. The narrow gap laser welding method for thick-walled materials according to claim 1, characterized in that: The narrow gap groove has an I-type, U-type or V-type with a groove surface angle of 1-3°, and a width of the narrow gap groove is 3-10 mm.

7. The narrow gap laser welding method for thick-walled materials according to claim 6, characterized in that: A plurality of grooves are arranged on the side wall of the narrow gap groove at intervals along the height reverse direction thereof, and the depth of the grooves is 0.5 mm to 2 mm.

8. The narrow gap laser welding method for thick-walled materials according to claim 1, characterized in that: In step S3, the Z coordinate of the welding robot is determined according to the current groove depth, so that the distance between the laser head and the bottom of the groove is kept constant to ensure that the laser spot size is always consistent, and the center line position of the groove is determined according to the current groove width, and the XY coordinates of the welding robot are determined to ensure that the distance between the flux-cored welding wire and both sides of the groove is the same. Then, the XYZ coordinates of the next position of the welding robot are transmitted to the robot controller and converted into a tracking path in the welding robot coordinate system. The welding robot continues to perform narrow gap laser wire filling welding according to the new path.

9. The narrow gap laser welding method for thick-walled materials according to claim 1, characterized in that: During the welding process, the molten pool is protected by using a shielding gas volume of 10 to 30 L / min. The shielding gas is nitrogen or argon. The flow direction of the shielding gas is at an angle of 30° to 45° to the plane where the base weld is located.

10. A narrow gap laser welding device for thick-walled materials, used to implement the narrow gap laser welding method for thick-walled materials as claimed in any one of claims 1 to 8, characterized in that: include: A laser head is used to emit a flat-top laser beam toward the narrow gap groove in a vertical direction to form a flat-top laser spot at the weld groove; A wire feeding mechanism, used to provide flux-cored welding wire to the weld groove at the flat-top laser spot; A welding robot, whose execution end is connected to a laser head and a wire feeding mechanism, and is used to drive the laser head and the wire feeding mechanism to move in a three-dimensional space; A laser sensor is fixedly mounted on the execution end of the welding robot to obtain the geometry of the weld; The temperature sensor is fixedly installed at the execution end of the welding robot to obtain the interlayer temperature at the weld; A control unit, used for converting the weld groove morphology into a geometric shape in a welding robot coordinate system; The robot controller is used to control the welding robot to execute a new welding path according to the instructions of the control unit so that the flux-cored welding wire is at the same distance from both sides of the groove.

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