Embedded double-circular-seam laser welding method based on positioner

Abstract

The invention discloses an embedded double-circular-seam laser welding method based on a positioner, belongs to the technical field of laser welding, and aims to solve the problems of unstable welding quality and low efficiency caused by poor accessibility of non-coaxially arranged embedded double circular seams. The method comprises the core steps that firstly, directional scraping pretreatment and laser positioned welding are carried out on a to-be-welded area, and it is ensured that a welding base body is clean and assembly is stable; then, the workpiece is clamped in a special tool, a driving interface on any side of the tool is selected to be connected to a positioner, and the pose of the positioner is adjusted, so that the circle center of the current circular seam to be welded is precisely coaxial with a rotating shaft of the positioner; finally, equipment is started, the rotating speed of the positioner is matched with the laser welding speed, and overall one-time welding of the first circular seam is completed; and then, the whole tool is turned around by 180 degrees, a driving interface is switched, and the process is repeated to complete welding of the second non-coaxial circular seam. Through the collaborative process, high-quality and high-efficiency one-time forming of the double circular seam is realized.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to an embedded double-ring laser welding method based on a positioner. Background Technology

[0002] With the development of lightweight aircraft structures, embedded weld structures are being used more and more widely. These welds are located inside cylindrical components in extremely confined spaces, posing a significant challenge to laser welding.

[0003] Existing laser welding methods often employ workpiece rotation for welding embedded circumferential welds because the laser head cannot penetrate the weld. However, this traditional method has several drawbacks: First, for easily oxidized materials such as aluminum alloys, incomplete pre-weld cleaning can lead to weld porosity. Second, if the workpiece's rotation center and the weld's center are not coaxial, uneven welding speed and penetration depth can result in defects such as incomplete penetration and undercut. Third, when encountering double embedded welds with non-coaxial ends, traditional segmented and multi-stage welding methods lead to repeated disassembly and assembly, accumulated positioning errors, and complex welding stresses. Ultimately, this results in unstable weld quality, substandard mechanical properties, and an inability to meet the high reliability requirements of structural components in aerospace and other fields. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide an embedded double-ring laser welding method based on a positioner to solve the problem that existing welding processes cannot guarantee the continuous one-time forming and internal quality of embedded welds, especially non-coaxial double embedded welds.

[0005] On one hand, embodiments of the present invention provide a laser welding method for welding non-coaxial embedded double circumferential seams, comprising the following steps:

[0006] S1. Clamping: Fix the workpiece with two non-coaxial embedded circumferential welds onto a welding fixture, both ends of which are provided with drive interfaces that can be connected to a positioner.

[0007] S2. First weld: Connect the first drive interface of the tooling to the positioner, adjust the positioner so that the center of the first circumferential weld is coaxial with the rotation axis of the positioner, start the positioner and the laser welding machine, and complete the overall one-time welding of the first circumferential weld;

[0008] S3. Tooling Change: Disconnect the first end of the tooling from the positioner, change the position of the entire tooling, and connect the second drive interface of the tooling to the positioner;

[0009] S4. Second weld: Adjust the positioner so that the center of the second circumferential weld is coaxial with the rotation axis of the positioner. Start the positioner and laser welding machine to complete the overall one-time welding of the second circumferential weld.

[0010] Furthermore, prior to S1, a part cleaning step is included: using pickling and / or scraping methods to remove oxide film, oil stains and excess material from the surface of the part to be welded.

[0011] Furthermore, the scraping is performed by using a scraper to scrape the front and back surfaces and the butt joint surfaces of the position to be welded in the same direction, with a scraping width of 20mm to 25mm.

[0012] Furthermore, after step S1 and before step S2, a positioning welding step is also included: using a handheld laser welder to perform positioning welding to fix the weld seams of the assembled parts.

[0013] Furthermore, in the tack welding step, the tack weld is required to penetrate the base material on both sides, the length of a single tack weld is 20mm to 30mm, and the spacing is 100mm to 150mm; the laser power is 700W-900W, the laser spot width is 2mm-4mm, and the shielding gas flow rate is 8L / min-15L / min.

[0014] Furthermore, in steps S2 and S4, the rotational speed of the positioner is kept consistent with the welding speed of the laser welding.

[0015] Furthermore, in steps S2 and S4, for aluminum alloy welds with a welding depth of 3-5mm, the laser welding power is 1900W-2300W, the runout is 0.5-0.8, the welding speed is 0.007m / s-0.011m / s, the frequency is 180Hz-220Hz, and the shielding gas is argon with a flow rate of 8L / min-15L / min.

[0016] Furthermore, in step S3, the position change is achieved by turning the entire tooling 180°.

[0017] Furthermore, following step S4, an inspection step is also included: radiographic inspection and / or fluorescence inspection of the weld, wherein the tensile strength of the weld is not less than 91% of the strength of the base material.

[0018] Accordingly, the present invention proposes a laser welding apparatus for implementing the above-described method, comprising:

[0019] A rigid crossbeam passes through the interior of the cylindrical workpiece to be welded in sequence along its axial direction.

[0020] The front flange and the rear flange are fixed to both ends of the crossbeam, respectively, for axial clamping and radial positioning of the workpiece from both ends;

[0021] At least two fixed turntables, which are fixed to the crossbeam by support blocks and located inside the workpiece, are used to tighten the workpiece from the inside to enhance its rigidity and transmit torque;

[0022] Two rotary drive interfaces are respectively located on the outside of the front flange and the rear flange, for selectively connecting to an external positioner drive.

[0023] In addition, a support mechanism is provided below the fixed turntable to support the fixed turntable and support the entire device on the working platform.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] 1) The method of the present invention, through a systematic process route of scraping and cleaning → tack welding → coaxial alignment → rotary welding → turning welding, and working in conjunction with special welding fixtures, ensures quality control throughout the entire process from pre-welding treatment to final forming, eliminates segmented welding caused by space constraints, eliminates welding defects (such as arc craters, cracks, etc.) caused by multiple arc starting and extinguishing, and realizes high-quality one-time continuous welding of embedded circumferential welds.

[0026] 2) The method of the present invention, through a precise coaxial alignment step (during the tooling clamping process, by adjusting the height of the positioner to keep the center of the embedded circumferential weld seam coaxial with the rotation axis, and in conjunction with the positioning and support of the front and rear flanges and roller brackets, to ensure the coaxiality of the workpiece during the rotational welding process), ensures a constant welding line speed. Combined with a specific welding parameter combination optimized for 3-5mm thick aluminum alloys (such as laser power of 1900W-2300W, welding speed of 0.007m / s-0.011m / s, etc.), it can obtain a high-quality weld seam with uniform penetration, no internal porosity, and no incomplete fusion, and its tensile strength can reach more than 91% of the base material.

[0027] 3) The welding sequence of the present invention, which is: welding one end → turning the whole body 180° → welding the other end, has a clear logic and is easy to operate. It efficiently solves the process problem of welding two non-coaxial embedded welds on the same workpiece. All welding can be completed by one clamping and simple station change. It is not only safe and convenient to operate, but also ensures the consistency of the quality of the double welds and improves the overall manufacturing efficiency and reliability.

[0028] 4) This invention utilizes rotary drive interfaces (such as hexagonal chucks) located at both ends of the workpiece, combined with the overall turning design of the tooling, to achieve the sequential welding of two non-coaxial embedded circumferential welds after a single clamping and fixing. This avoids the cumbersome operations of multiple disassembly and repositioning required in traditional methods due to the concealed location of the welds, reduces auxiliary time, and significantly improves welding efficiency, making it particularly suitable for mass production.

[0029] 5) This invention utilizes a high-rigidity main frame composed of a rigid crossbeam, a split-type fixed turntable, and circumferentially distributed tension rods to internally support and reinforce the workpiece. This structure ensures that the workpiece does not shift or deform during high-speed rotating welding, providing a stable motion reference for laser welding. It solves defects such as uneven weld formation and incomplete fusion caused by workpiece vibration or displacement, laying a solid foundation for obtaining high-precision, high-quality continuous circumferential welds.

[0030] 6) The split-type fixed turntable design of the tooling of this invention facilitates the loading and unloading of workpieces; the lifting holes on the flange facilitate the hoisting and 180° turning operations of the tooling; and the height-adjustable support mechanism can adapt to welds with different axes, aligning them with the rotating shaft of the positioner. These designs collectively enhance the overall versatility and on-site operability of the tooling, reducing the labor intensity of workers.

[0031] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0032] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0033] Figure 1 This is a schematic diagram of the overall structure of the laser welding clamping and rotating device of the present invention;

[0034] Figure 1a This is a partial schematic diagram of the weld seam of the laser welding clamping and rotating device of the present invention in the state of clamping the workpiece to be welded;

[0035] Figure 2 This is a front view of the laser welding clamping and rotating device of the present invention;

[0036] Figure 3 This is a side view of the laser welding clamping and rotating device of the present invention;

[0037] Figure 4 for Figure 3 A schematic diagram of the structure after the base is disassembled.

[0038] Figure label:

[0039] 1. Front flange; 2. Rear flange; 3. Locating pin; 4. First fixed turntable; 5. Second fixed turntable; 6. Support block; 7. Tensioning rod; 8. Crossbeam; 9. First support mechanism; 10. Second support mechanism; 11. First drive interface; 12. Second drive interface; 13. First base; 14. Second base; 15. First lifting hole; 16. Second lifting hole; 17. Third lifting hole; 18. Weld. Detailed Implementation

[0040] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0041] As aircraft products evolve towards lighter and more compact designs, the adoption of double-layer structure installations and other design concepts has led to the emergence of embedded weld seams within the cabin. These weld seams are located within confined cylindrical spaces with poor accessibility, making it difficult for traditional laser welding equipment to achieve a single, complete weld. This often necessitates segmented welding, resulting in unstable weld quality, low efficiency, and susceptibility to welding deformation and arc initiation / exit defects. This invention aims to provide a laser welding method for embedded double-ring seams based on a positioner, solving the challenge of integral laser welding of non-coaxial embedded circumferential weld seams.

[0042] On one hand, a specific embodiment of the present invention discloses an embedded double-ring laser welding method based on a positioner, comprising the following steps:

[0043] S1. Clamping: Fix the workpiece with two non-coaxial embedded circumferential welds onto a welding fixture, both ends of which are provided with drive interfaces that can be connected to a positioner.

[0044] S2. First weld: Connect the first drive interface of the tooling to the positioner, adjust the positioner so that the center of the first circumferential weld is coaxial with the rotation axis of the positioner, start the positioner and the laser welding machine, and complete the overall one-time welding of the first circumferential weld;

[0045] S3. Tooling Change: Disconnect the first end of the tooling from the positioner, change the position of the entire tooling, and connect the second drive interface of the tooling to the positioner;

[0046] S4. Second weld: Adjust the positioner so that the center of the second circumferential weld is coaxial with the rotation axis of the positioner. Start the positioner and laser welding machine to complete the overall one-time welding of the second circumferential weld. The welding parameter range is the same as in step S2.

[0047] Specifically, in S4, the overall one-time welding refers to completing the welding of a complete circumferential weld in one continuous operation without interrupting the laser output and workpiece rotation, thus avoiding multiple arc initiation and termination, thereby eliminating potential defects at the joint.

[0048] In practice, this method relies on a clamping and rotating device (such as...) Figure 1-4 and Figure 1a As shown, the device includes core components such as a rigid crossbeam penetrating the workpiece, flanges at both ends, a fixed turntable for internal support, and a bottom support mechanism. Figure 1a As shown, after the workpiece is clamped in the device, the weld seam of the ring to be welded is located in the area of ​​support and rotation of the device, which facilitates the precise alignment of subsequent laser welding.

[0049] In step S1, the workpiece is reliably secured within the fixture (the parts are pressed together using the front flange, rear flange, and tightening bolts, with locating pins for limiting movement, followed by locking the entire workpiece with a fixed turntable and tensioning rods to ensure no movement during welding). In welding steps S2 and S4, the positioner height is precisely adjusted to ensure the center of the circumferential weld to be welded is coaxial with the positioner's rotation axis. The positioner is then started to rotate at a constant speed, and the laser welding machine is started simultaneously, achieving relative stillness between the laser beam and the weld position, resulting in high-quality circumferential welding. Step S3, fixture change, is crucial. Typically, the entire fixture and workpiece are lifted and rotated 180° to achieve a turnaround, allowing for rapid switching of the weld to be welded.

[0050] Compared with existing technologies that require segmented welding or complex robot trajectory planning, the method provided in this embodiment greatly simplifies the welding process of embedded non-coaxial double ring seams by rotating the workpiece, fixing it with laser, and combining it with a reversible special tooling, thus ensuring the continuity and consistency of weld quality.

[0051] This method enables the integral one-time welding of embedded narrow space circumferential welds, fundamentally solving the problems of arc start-up and extinguishing defects, uneven joint quality, and low efficiency caused by segmented welding. By simply turning the tooling around, welding of two circumferential welds with different shafts can be completed. It has good process adaptability and is easy to operate.

[0052] Furthermore, in order to ensure the basic quality of the welded joint and avoid defects such as porosity and lack of fusion caused by surface contaminants, a part cleaning step is included before S1: using pickling and / or scraping methods to remove oxide film, oil and excess material from the surface of the part to be welded.

[0053] For example, for aluminum alloy materials, pickling is performed first to remove oil stains, followed by mechanical scraping to completely remove the dense aluminum oxide film.

[0054] Specifically, the scraping involves using a scraper to scrape the front and back surfaces and the butt joint surfaces of the area to be welded in the same direction, with a scraping width of 20mm to 25mm (e.g., 20mm, 21mm, 22mm, 23mm, 24mm, 25mm). This unidirectional scraping prevents the oxide film from being re-embedded into the substrate, ensuring a fresh metallic luster and providing a clean, active surface for subsequent laser welding, significantly improving the density and strength of the weld.

[0055] Furthermore, in the S1 clamping process, a workpiece with two non-coaxial embedded circumferential welds is fixed on a welding fixture, both ends of which are equipped with drive interfaces that can be connected to a positioner. In practice, this method relies on the aforementioned clamping and rotating device, and the workpiece is reliably fixed within the fixture. The specific operation is as follows:

[0056] 1. First, place the crossbeam horizontally, and pre-fix the front flange and rear flange to both ends of the crossbeam with bolts;

[0057] 2. Place the workpiece to be welded on the outside of the crossbeam, so that the front end face of the workpiece is in contact with the inner end face of the front flange and the rear end face is in contact with the inner end face of the rear flange.

[0058] 3. Tighten the top bolts on the front and rear flanges to apply a uniform axial clamping force to the workpiece; insert the locating pin into the pre-dated locating holes on the front flange and the workpiece end frame to complete the radial positioning of the workpiece;

[0059] 4. Assemble the fixed turntable: Pre-install the lower half of the fixed turntable on the crossbeam using the support block, so that the outer end face of the support block is in contact with the inner circumferential wall of the fixed turntable and is fixed with bolts; close the upper half of the fixed turntable and tighten the bolts, so that the outer circumferential wall of the fixed turntable is pressed against the inner surface of the workpiece cylinder wall by interference fit or circumferentially distributed tightening screws (tightening force controlled at 5-8 N·m), ensuring that the fit between the fixed turntable and the workpiece cylinder wall is ≥95%;

[0060] 5. Assemble the tension rods: At least one tension rod is installed along the axial direction of the crossbeam, with both ends passing through the corresponding through holes of the fixed turntable. Tighten the nuts to make the fixed turntable form a rigid whole.

[0061] 6. Assemble the support mechanism: First, pre-assemble the support mechanism with the corresponding first base and second base, and then connect the base to the work platform; by adjusting the bottom lifting screw of the support mechanism, make the top arc-shaped roller group roll in contact with the outer peripheral wall of the lower half of the fixed turntable, and keep the support surface horizontal with the axis of the fixed turntable.

[0062] Furthermore, in order to fix the relative positions of the parts before formal welding and prevent misalignment during clamping or the initial stage of welding, a trial assembly and tack welding step is included after step S1 and before step S2: the parts are assembled by fitting them together to ensure that the gap and step difference are no more than 0.2mm; the workpiece is a lock-bottom butt structure, wherein the welding depth at the end frame round hole is 3-5mm (e.g., 3mm, 4mm, 5mm), and the lock bottom thickness is 2-3mm (e.g., 2mm, 3mm); subsequently, a handheld laser welder is used to fix the weld seam of the assembled parts by tack welding.

[0063] It is worth noting that in the aforementioned tack welding step, the tack weld is required to penetrate the base material on both sides and have a smooth transition. The length of a single tack weld is 20mm to 30mm (e.g., 20mm, 22mm, 25mm, 28mm, 30mm), and the spacing is 100mm to 150mm (e.g., 100mm, 110mm, 120mm, 130mm, 140mm, 150mm). The laser power is 700W to 900W (e.g., 700W, 750W, 800W, 850W, 900W), the laser spot width is 2mm to 4mm (e.g., 2mm, 2.5mm, 3mm, 3.5mm, 4mm), and the shielding gas flow rate is 8L / min to 15L / min (e.g., 8L / min, 10L / min, 12L / min, 15L / min). Appropriate tack welding parameters can ensure tack strength without causing workpiece deformation due to excessive heat input, thus laying a good foundation for subsequent overall welding.

[0064] Furthermore, to achieve uniform weld formation, the rotational speed of the positioner is kept consistent with the welding speed of the laser welder during the S2 first weld and S4 second weld welding steps. That is, the linear velocity of the workpiece rotation is equal to the speed at which the laser beam moves along the weld, so that the laser energy can be applied evenly to the entire circumferential weld, thereby obtaining a high-quality weld with consistent width and penetration depth.

[0065] Furthermore, for typical aluminum alloy embedded weld structures, in steps S2 and S4, for aluminum alloy welds with a weld depth of 3-5mm (e.g., 3mm, 3.5mm, 4mm, 4.5mm, 5mm), the laser welding parameters are as follows:

[0066] Laser welding power ranges from 1900W to 2300W (e.g., 1900W, 2000W, 2100W, 2120W, 2150W, 2200W, 2300W); laser beam deflection is 0.5-0.8 (e.g., 0.5, 0.6, 0.7, 0.8); welding speed is 0.007m / s to 0.011m / s (e.g., 0.007m / s, 0.008m / s, 0.009m / s, 0.010m / s). The laser frequency is 180Hz-220Hz (e.g., 180Hz, 190Hz, 200Hz, 210Hz, 220Hz); the protective gas is argon with a flow rate of 8L / min-15L / min (e.g., 8L / min, 9L / min, 10L / min, 11L / min, 12L / min, 13L / min, 14L / min, 15L / min).

[0067] This series of optimized parameter combinations can effectively control heat input while ensuring full penetration, avoiding burn-through, collapse, or excessive porosity, and resulting in a weld with a beautiful shape and excellent internal quality.

[0068] Specifically, in steps S2 and S4, the overall one-time welding refers to completing the welding of a complete circumferential weld in one continuous operation without interrupting the laser output and workpiece rotation, thus avoiding multiple arc initiation and termination, thereby eliminating potential defects at the joint.

[0069] Furthermore, tooling change in S3 is crucial. It typically involves lifting and rotating the entire tooling and workpiece 180° to achieve a turnaround, thereby quickly switching the weld seam to be welded. Specifically, it is performed as follows:

[0070] (1) As Figure 1 A first base is installed on the outer side of the front flange, and a second base is installed on the outer side of the rear flange. The bases and the support mechanism form a complete support system. When changing the tooling, first disconnect the positioner connected to the drive interface at the welded end (such as the first drive interface), then remove the fasteners connecting the first base to the work platform, so that the first base is separated from the front flange. At this time, the tooling state can be referred to Figure 4 (Right now Figure 3 (The structure after disassembling the base) fully exposes the area of ​​the second weld seam to be welded.

[0071] (2) Connect the lifting device through the first lifting hole of the front flange and the second lifting hole of the rear flange, and use the lifting device to lift the tooling and workpiece as a whole to a suspended state, keeping the crossbeam axially horizontal and rotating it 180° around its axis.

[0072] (3) Adjust the tooling position so that the second drive interface is aligned with the connection end of the positioner, fix the second base to the work platform, and restore the assembly of the support mechanism and the second base to the correct position. Figure 3 The complete support state is shown;

[0073] (4) Connect and fix the second drive interface to the positioner to complete the tooling change.

[0074] This method is simple and efficient, making full use of the symmetrical design at both ends of the tooling to achieve rapid welding changes.

[0075] Furthermore, the welding parameters for the second weld (S4) are the same as those for the first weld (S2). During welding, the shielding gas must continuously cover the weld area to prevent air intrusion and oxidation.

[0076] To ultimately verify the weld quality, following step S4, an inspection step is also included: radiographic testing of the weld (to ensure there are no defects exceeding the standard inside the weld) and / or fluorescence testing (to check for surface defects such as cracks and pinholes in the weld), and the tensile strength of the weld is not less than 91% of the strength of the base material. These measures ensure that the welded joint meets high-standard quality requirements, such as the Class I joint standard commonly used in the aerospace field.

[0077] Compared with existing technologies that require segmented welding or complex robot trajectory planning, the method provided in this embodiment greatly simplifies the welding process of embedded non-coaxial double ring seams by rotating the workpiece, fixing it with laser, and combining it with a reversible special tooling, thus ensuring the continuity and consistency of weld quality.

[0078] This method enables the integral one-time welding of embedded narrow space circumferential welds, fundamentally solving the problems of arc start-up and extinguishing defects, uneven joint quality, and low efficiency caused by segmented welding. By simply turning the tooling around, welding of two circumferential welds with different shafts can be completed. It has good process adaptability and is easy to operate.

[0079] To implement the laser welding method described above, this invention also proposes a laser welding apparatus for implementing the above method, such as... Figure 1-4 As shown. The device includes:

[0080] A rigid crossbeam passes through the interior of the cylindrical workpiece to be welded in sequence along its axis (the crossbeam is the core load-bearing component of the entire device, penetrating the workpiece and various functional components).

[0081] The front flange and the rear flange are respectively fixed to both ends of the crossbeam by bolts (preferably symmetrically distributed at both ends of the crossbeam axis) for axial clamping and radial positioning of the workpiece from both ends;

[0082] At least two fixed turntables (first fixed turntable and second fixed turntable) are fixed to the crossbeam by support blocks and located inside the workpiece (the fixed turntables are in contact with the inner surface of the workpiece cylinder wall) to support the workpiece from the inside to enhance its rigidity and transmit torque.

[0083] Two rotary drive interfaces (first drive interface and second drive interface) are respectively located on the outer sides of the front flange and the rear flange. Figure 1 The raised structure at the outer end of the middle flange is used for selective connection with an external positioner drive.

[0084] Additionally, a support mechanism (bearing component) is provided below the fixed turntable to support the fixed turntable and support the entire device on the working platform.

[0085] The device of this invention provides a stable and precisely rotatable support platform for the circumferential weld seam embedded inside the cylindrical workpiece, so that the laser head can be fixed while the workpiece can rotate with the tooling as a whole, thereby realizing continuous and integral one-time welding of the circumferential weld seam.

[0086] During implementation, the workpieces to be welded (such as cylinder and end frame components) are first pre-treated by cleaning, trial assembly, scraping and cleaning, and tack welding.

[0087] Subsequently, the assembled workpiece is placed over the crossbeam, and the tightening bolts and locating pins on the front and rear flanges are used to axially tighten and radially limit the workpiece to prevent it from shifting during welding. Figure 2 As shown, the locating pin protrudes radially along the flange and precisely matches the pre-dated locating hole on the workpiece end frame to ensure the coaxiality of the workpiece and the crossbeam.

[0088] Next, the lower halves of the first and second fixed turntables are pre-installed on the crossbeam using support blocks. The support blocks extend radially along the crossbeam (the radial dimensions of the support blocks are adapted to the inner circumferential wall of the fixed turntables), and their outer end faces are in contact with the inner circumferential wall of the fixed turntables. The fixed turntables are then fixed to the support blocks using bolts. The upper halves of the fixed turntables are then closed and tightened with bolts. At this point, the outer circumferential wall of the fixed turntable is adapted to the inner surface of the workpiece cylinder wall (the two fit together without gaps). The inner surface of the workpiece cylinder wall is pressed against the workpiece cylinder wall by interference fit or circumferentially distributed tightening screws (integrated into the fixed turntable body), thereby achieving radial tightening of the workpiece from the inside.

[0089] At the same time, at least two tensioning rods (four are shown in the figure) are set along the axial direction of the crossbeam. Their two ends pass through the corresponding through holes opened in the circumference of the first fixed turntable and the second fixed turntable, respectively. The nuts at both ends of the rods are tightened so that the two fixed turntables are tightened together in the axial direction and form a rigid whole, so as to uniformly transmit torque and suppress the radial deformation of the fixed turntables.

[0090] Then, a support mechanism is used to support and fix the turntable: the support mechanism is a height-adjustable roller bracket, the top of which is equipped with an arc-shaped roller assembly adapted to the outer peripheral wall of the fixed turntable (e.g., Figure 4 As shown, the arc-shaped roller assembly has the same contact arc as the lower half of the fixed turntable, and the arc surface of the arc-shaped roller assembly rolls in contact with the outer peripheral wall of the lower half of the fixed turntable; by adjusting the lifting screw at the bottom of the support mechanism, the support surface of the arc-shaped roller assembly is kept horizontal with the axis of the fixed turntable, thereby stably supporting the fixed turntable and the entire device on the working platform.

[0091] Finally, depending on the location of the weld seam to be welded, either the first drive interface on the outside of the front flange or the second drive interface on the outside of the rear flange is connected to an external positioner. The positioner drives the entire fixture and workpiece to rotate synchronously, and the circumferential weld seam is completed in conjunction with the fixed laser head.

[0092] Compared with the prior art, the clamping and rotating device provided in this embodiment constructs a high-rigidity rotating body for cylindrical workpieces through the combination of "internal fixed turntable support + clamping by flanges at both ends", effectively solving the technical problem that the laser head cannot be inserted or its movement is restricted due to the narrow embedded space.

[0093] This embodiment features a design where a crossbeam passes through the workpiece and an internally fixed turntable provides support, ensuring high stability during workpiece rotation and preventing poor weld formation caused by workpiece vibration or deformation. Simultaneously, drive interfaces are provided at both ends of the device, and combined with the adjustable characteristics of the support mechanism, flexible tooling reversal is possible. This allows for separate welding of the non-coaxial circumferential welds at both ends of the workpiece, achieving a "one-device-two-welds" effect, significantly improving production efficiency and application flexibility.

[0094] Furthermore, to enhance the stability and positioning accuracy of the clamping, the front flange and the rear flange are respectively equipped with clamping bolts for axially clamping the workpiece and locating pins for radial limiting:

[0095] In practice, multiple tightening bolts are evenly distributed along the circumference of the flange. By screwing them into and pressing against the end face of the workpiece, a uniform axial clamping force is applied to the workpiece. At least two locating pins are provided on the front flange, protruding radially along the flange. Their cylindrical surfaces are in clearance fit (≤0.05mm) with the inner wall of the pre-dated locating holes in the workpiece end frame. Simultaneously, the end face of the front flange and the end face of the workpiece end frame are in contact. Combined with the axial clamping force of the tightening bolts, circumferential positioning and axial limiting of the workpiece are achieved, preventing slippage during rotation. This design ensures that the axial and circumferential positions of the workpiece are reliably fixed during high-speed rotating welding, ensuring that the laser beam is always precisely aligned with the weld seam, guaranteeing the stability and consistency of welding quality.

[0096] Furthermore, considering the ease of tooling assembly and adaptability to workpieces of different diameters, the fixed turntable has a split structure, including an upper part and a lower part, which are fixed together by bolts.

[0097] During assembly, the lower half can be pre-installed on the crossbeam using support blocks, then the workpiece is hoisted into place, and finally the upper half is closed and secured with bolts. This split design avoids the cumbersome operation of inserting the entire fixture through the end of the workpiece, making it particularly suitable for long cylindrical workpieces or workpieces with one end obstructed, greatly improving clamping efficiency. Furthermore, by changing the fixed turntable to different sizes or adjusting the position of the support blocks on the crossbeam, this device can accommodate workpieces of different diameters and lengths within a certain range, enhancing the versatility of the fixture.

[0098] Furthermore, considering the significant weight of the fixed turntables, a third lifting hole is provided on the upper part of each fixed turntable to facilitate lifting during assembly, disassembly, and maintenance. When installing the turntables or removing them from inside the workpiece, an overhead crane can be used with lifting equipment to connect to this third lifting hole, achieving safe and labor-saving handling operations.

[0099] Furthermore, in order to improve the overall rigidity and torque transmission capability of the tooling and prevent relative displacement of the fixed turntables when subjected to force, the at least two fixed turntables are connected and reinforced by at least one tensioning rod distributed along the circumference.

[0100] During implementation, the tension rods are passed through the corresponding connecting holes on each fixed turntable, and both ends are locked with nuts. This causes the multiple fixed turntables to form an integral frame, which together resists the torque and radial force generated during welding, further reducing the risk of workpiece vibration and deformation. Especially for thin-walled cylindrical workpieces with a large length-to-diameter ratio, this structure can significantly improve the stability of the welding process.

[0101] Furthermore, to facilitate compatibility with different types of positioner interfaces, the rotary drive interface can be a hexagonal chuck, a square chuck, or a spline chuck, etc.

[0102] For example, this embodiment preferably uses a hexagonal chuck because it has the advantages of large torque transmission, convenient docking, and no relative slippage. In implementation, the drive shaft of the positioner can be reliably connected by inserting it into the hexagonal chuck, which is simple to operate and provides good connection rigidity.

[0103] Furthermore, to facilitate adjustment of the tooling height and ensure precise alignment of the weld center with the positioner's rotation axis, the support mechanism is a height-adjustable roller bracket. By adjusting the screws or shims on the roller bracket, the height of each tooling and workpiece can be finely adjusted, ensuring that when welding the circumferential weld at either end, the center of the weld coincides with the positioner's rotation axis. This is a crucial step in achieving uniform penetration and aesthetically pleasing circumferential weld formation.

[0104] Furthermore, to increase the modularity and ease of maintenance of the tooling, the support block and the crossbeam are detachably connected, for example, by bolts or keyway joints. This allows the position of the support block to be flexibly adjusted according to the welds and internal cavity structure of the workpiece, and also facilitates the replacement of worn parts.

[0105] Furthermore, considering the safety of tooling hoisting, the device is provided with a first lifting hole for overall hoisting.

[0106] Preferably, the first lifting hole is located on the front flange and / or the rear flange. When it is necessary to lift the assembled workpiece and tooling as a whole (such as turning it 180° for repositioning), the lifting eye bolts can be connected to these first lifting holes, and the operation can be carried out using a crane or overhead crane, which is safe and stable.

[0107] In addition, a second lifting hole can also be opened separately on the rigid crossbeam, mainly for the assembly or maintenance lifting of tooling components (such as crossbeam assemblies).

[0108] It should be noted that the device provided in this embodiment of the invention is particularly suitable for welding embedded annular welds with misaligned ends. This invention utilizes the characteristic that both ends of the fixture can be driven; after welding one end of the weld, there is no need to disassemble the workpiece. Simply turning the fixture around allows the drive interface at the other end to connect with the positioner for welding the second weld. This method solves the problem of not being able to complete welding in a single clamping operation due to misalignment of the two welds.

[0109] The present invention will be described in more detail below through specific embodiments. These embodiments are merely descriptions of the best implementation of the invention and do not limit the scope of the invention in any way.

[0110] Example 1

[0111] Using the clamping and rotating device and the welding method of the present invention, a certain type of aluminum alloy aircraft section with two non-coaxial embedded circumferential welds is welded.

[0112] Clamping rotary device such as Figure 1 and Figure 2As shown, it includes: a rigid crossbeam that axially passes through the interior of the cylindrical workpiece to be welded; a front flange and a rear flange, respectively fixed to both ends of the crossbeam, for axial clamping and radial positioning of the workpiece from both ends; at least two fixed turntables, fixed to the crossbeam by support blocks and located inside the workpiece, for internally supporting the workpiece to enhance its rigidity and transmit torque; two rotary drive interfaces, respectively located on the outside of the front flange and the rear flange, for selectively connecting to an external positioner drive; and a support mechanism correspondingly located below the fixed turntables, for supporting the fixed turntables and supporting the entire device on a working platform.

[0113] The front and rear flanges are equipped with clamping bolts for axially tightening the workpiece and locating pins for radial positioning. The fixed turntable is a split structure, consisting of an upper and lower half, which are bolted together. The two fixed turntables are connected and reinforced by a circumferentially distributed tension rod. The rotary drive interface is a hexagonal clamp. The support mechanism is a height-adjustable roller bracket. The support block and the crossbeam are detachably connected. The device has a first lifting hole for overall hoisting. The first lifting hole is located on the front and / or rear flanges.

[0114] Welding is performed using the aforementioned clamping and rotating device. The welding method includes the following steps:

[0115] S1. Clamping: Fix the cleaned and positioned welded workpiece onto the tooling.

[0116] S2. First Weld Weld: Connect the hexagonal chuck at one end of the fixture to the positioner. Adjust the positioner height so that the center of the first circumferential weld (weld depth 4.0mm) is coaxial with the positioner's rotation axis. Set the laser welding power to 2120W, yaw rate to 0.6, welding speed to 0.009m / s, frequency to 200Hz, and argon flow rate to 10L / min. Start the positioner and laser welding machine to complete the first circumferential weld in one pass.

[0117] S3. Tooling Change: Disconnect the tooling from the positioner and turn the entire tooling 180°.

[0118] S4. Second weld: Connect the hexagonal chuck at the other end of the fixture to the positioner and adjust for centering. Using the same welding parameters as in S2, complete the entire first-pass welding of the second circumferential weld.

[0119] Example 2

[0120] This embodiment is based on the device described in Embodiment 1, and the steps are the same as in Embodiment 1. However, for a slightly thinner weld (welding depth 3.5mm), the welding parameters are adjusted as follows: laser power 1950W, yaw 0.6, welding speed 0.010m / s, frequency 200Hz, and argon flow rate 10L / min.

[0121] Example 3

[0122] In this embodiment, the apparatus of Embodiment 1 is used. Before clamping at S1, the area to be welded is thoroughly cleaned by pickling followed by mechanical scraping, with a scraping width of 22mm. During tack welding, a laser power of 850W, a spot width of 3.5mm, and an argon gas flow rate of 9L / min are used for tack welding with a length of 25mm and a spacing of 120mm. The formal welding parameters are the same as in Embodiment 1.

[0123] Comparative Example 1

[0124] This comparative example uses a traditional three-jaw chuck to hold one end of the workpiece, while the other end is in a free state for laser welding. The welding method and parameters are the same as in Example 1.

[0125] Comparative Example 2

[0126] This comparative example uses the apparatus of Example 1. However, during the welding of the second weld (step S4), the positioner was not adjusted to ensure that the center of the second circumferential weld was coaxial with the positioner's rotation axis. The welding parameters were the same as in Example 1.

[0127] Comparative Example 3

[0128] This comparative example uses the apparatus of Example 1, but employs segmented welding (pausing after every 1 / 3 of a turn) when welding each circumferential weld, disrupting the continuity of the welding process. The welding parameters are the same as in Example 1.

[0129] Comparative Example 4

[0130] This comparative example uses the apparatus of Example 1, with the following welding parameters: laser power 2500W, welding speed 0.015m / s, and other parameters the same as in Example 1.

[0131] Characterization results and analysis

[0132] The characterization results of the above-described embodiments and comparative examples are shown in the table below.

[0133] Table 1. Comparison of weld quality and mechanical properties

[0134]

[0135] As can be seen from the table, the welds obtained by using the device and method provided by the present invention (Examples 1-3) have good to excellent appearance, and the radiographic test results are all Grade I with no defects. The tensile strength of all welds reaches more than 91% of the strength of the base material, showing stable and high-quality welding performance.

[0136] In contrast, all comparative examples exhibited defects such as poor weld surface quality, lack of fusion, porosity, or incomplete penetration due to unstable tooling, inaccurate alignment, segmented welding, or incorrect parameters. Radiographic testing results were either Grade II or unqualified, and the tensile strength only reached 72.3%–87.2% of the base material strength, resulting in a significant decrease in mechanical properties.

[0137] In summary, this invention, through its innovative clamping and rotating device design and its matching welding method, successfully solves the technical bottleneck of laser welding of non-coaxial embedded circumferential welds, achieving high-quality and high-efficiency one-time welding, and has broad application prospects in high-end manufacturing fields such as aerospace.

[0138] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser welding method for welding non-coaxial embedded double-ring seams, characterized in that, Includes the following steps: S1. Clamping: Fix the workpiece with two non-coaxial embedded circumferential welds onto a welding fixture, both ends of which are provided with drive interfaces that can be connected to a positioner. S2. First weld: Connect the first drive interface of the tooling to the positioner, adjust the positioner so that the center of the first circumferential weld is coaxial with the rotation axis of the positioner, start the positioner and the laser welding machine, and complete the overall one-time welding of the first circumferential weld; S3. Tooling Change: Disconnect the first end of the tooling from the positioner, change the position of the entire tooling, and connect the second drive interface of the tooling to the positioner; S4. Second weld: Adjust the positioner so that the center of the second circumferential weld is coaxial with the rotation axis of the positioner. Start the positioner and laser welding machine to complete the overall one-time welding of the second circumferential weld.

2. The method according to claim 1, characterized in that, Before S1, a part cleaning step is also included: using pickling and / or scraping methods to remove oxide film, oil and excess material from the surface of the part to be welded.

3. The method according to claim 2, characterized in that, The scraping is performed by scraping the front and back sides of the position to be welded and the butt joint surface in the same direction with a scraper, and the scraping width is 20mm to 25mm.

4. The method according to claim 1, characterized in that, After step S1 and before step S2, a positioning welding step is also included: using a handheld laser welder to perform positioning welding to fix the weld seams of the assembled parts.

5. The method according to claim 4, characterized in that, In the tack welding step, the tack weld is required to penetrate the base material on both sides. The length of a single tack weld is 20mm to 30mm, and the spacing is 100mm to 150mm. The laser power is 700W to 900W, the laser spot width is 2mm to 4mm, and the shielding gas flow rate is 8L / min to 15L / min.

6. The method according to claim 1, characterized in that, In steps S2 and S4, the rotational speed of the positioner is kept consistent with the welding speed of the laser welding.

7. The method according to claim 1, characterized in that, In steps S2 and S4, for aluminum alloy welds with a welding depth of 3-5mm, the laser welding power is 1900W-2300W, the runout is 0.5-0.8, the welding speed is 0.007m / s-0.011m / s, the frequency is 180Hz-220Hz, and the shielding gas is argon with a flow rate of 8L / min-15L / min.

8. The method according to claim 1, characterized in that, In step S3, the position change is achieved by turning the entire tooling 180°.

9. The method according to claim 1, characterized in that, Following step S4, an inspection step is also included: radiographic inspection and / or fluorescence inspection of the weld, wherein the tensile strength of the weld is not less than 91% of the strength of the base material.

10. A laser welding apparatus for implementing the method according to any one of claims 1 to 9, characterized in that, include: A rigid crossbeam (8) passes through the interior of the cylindrical workpiece to be welded in sequence along its axial direction; The front flange (1) and the rear flange (2) are fixed to the two ends of the crossbeam (8) respectively, for axial clamping and radial positioning of the workpiece from both ends; At least two fixed turntables, which are fixed to the crossbeam (8) by support blocks (6) and located inside the workpiece, are used to tighten the workpiece from the inside to enhance its rigidity and transmit torque; Two rotary drive interfaces are respectively located on the outside of the front flange (1) and the rear flange (2) for selectively connecting to an external positioner drive. In addition, a support mechanism is provided below the fixed turntable to support the fixed turntable and support the entire device on the working platform.

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