Angular deformation control method for laser welded T-joints

Abstract

The present invention relates to a method for controlling the angular deformation of a laser-welded T-joint, and belongs to the technical field of metal material connection and processing. The present invention uses the novel process technology to replace the unidirectional vertical downward pressure pre-tightening method with the upper and lower simultaneous clamping pre-assembly method for pre-welding preparation, thereby avoiding the original deformation trend on both sides of the welding area of ​​the bottom plate of the T-joint. By means of the protrusion control of the lower ejection mechanism and the rapid cooling of the auxiliary copper plate in the welding area, and then by a reasonable reverse deformation angle preset, the outer surface of the bottom plate without edge traces can be obtained. This technology is used to manufacture large-scale welded wall panels, and the outer surface of the wall panel obtained, i.e., the pneumatic surface, is smooth and continuous, without obvious edges, the waviness is controlled, and the profile accuracy is high.

Description

Technical Field

[0001] The invention relates to a method for controlling angular deformation of a laser-welded T-joint, and belongs to the technical field of metal material connection processing. Background Art

[0002] The outer surface of the integral wall panel in the aircraft body structure directly constitutes the aerodynamic shape of the aircraft, and the surface quality after processing will directly affect the accuracy, smoothness and aesthetics of the overall shape of the aircraft. The wall panel structure is generally composed of skin, long stringers and bulkheads through a connection process. In the wall panel structure, the main function of the long stringers is to support the skin surface, withstand and transmit external aerodynamic pressure, and avoid concave deformation caused by insufficient local stiffness of the skin. There are two common methods for connecting aircraft wall panel structures: riveting and welding. In comparison, welding has the advantages of reducing the overall structural weight and improving structural performance, especially for titanium alloy materials.

[0003] Taking titanium alloy wall panels as an example, using welding instead of riveting can make the joint more integrated, thereby achieving the goal of increasing strength, reducing aircraft manufacturing costs, shortening production cycles, and reducing aircraft weight, thus improving aircraft performance to a certain extent. Although the laser welding method has the advantages of small heating range of the material to be welded, high welding line speed, small weld heat input, small welding heat affected zone, small welding residual stress and deformation, angular deformation is still inevitable after the double-sided welds of the T-joint are formed. Figure 1 As shown, the two sides of the lower bottom plate skin will warp, causing edge marks to form at the corresponding weld position just below the long stringer reinforcement. This is particularly prominent for the curved skin structure when it is difficult to match the reinforcement welding edge with the skin.

[0004] Large wall panels have many long truss reinforcement structures, so the multiple ridge marks on the skin surface directly affect the surface quality of the aircraft, and will also lead to the accumulation of deformation and warping, which will not only affect the overall surface accuracy of the wall panel, but also cause the welding and repair conditions of the next process to deteriorate. The current correction method is vacuum heat treatment correction, using a high-rigidity frame-type heat treatment fixture to eliminate the internal stress in the vacuum after welding and stabilize the overall correction. However, since the fixture cannot adopt the overall surface correction method, it is impossible to achieve targeted correction for the ridge problem on the skin surface, and it is difficult to eliminate appearance defects.

[0005] At the same time, although the welding process of the T-joint with multiple reinforcement ribs of large wall panels can be mechanically assisted to resist deformation, it will cause a series of problems such as difficulty in removing parts after welding and difficulty in clamping before heat treatment. Although the overall wall panel profile can meet the fit requirement of no more than 0.3mm after multiple heat treatments and stabilization and correction, the remaining multiple rows of ridges on the outer surface will still cause the aerodynamic surface waviness to decrease. It is difficult to fully meet the manufacturing requirements of small deformation and high surface accuracy of large welded wall panel components of the new generation of aircraft. Summary of the invention

[0006] In order to overcome the above technical problems, the present invention provides a new process method, which innovatively utilizes a welding fixture with vertical ribs corresponding to the lower ejection mechanism, changes the traditional unidirectional prestressed compression assembly welding method into a counter-prestressed clamping assembly welding method, releases the assembly prestress of the skin, and combines the airflow rapid cooling method at the same time. On this basis, the reverse deformation is appropriately utilized to eliminate the overall welding angle deformation, so as to ultimately eliminate the problem of the ridge corrugation of the outer surface of the T-joint, and greatly improve the aerodynamic surface quality of the welded wall panel type components.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The steps of controlling the angular deformation of laser welded T-joints are as follows:

[0009] Step 1: If Figure 3 As shown, remove the upper pressure beam clamp, and adjust the adjusting screw so that the ejector does not protrude from the upper surface of the fixture bottom plate, and adjust the clamping screw to remove the clamping force of the pressure plate;

[0010] Step 2: If Figure 4 As shown, install the bottom plate on the fixture bottom plate, use a pressing plate to press the edges around the bottom plate, and finally use a pressing screw to apply a pressing force to fix the bottom plate;

[0011] Step 3: If Figure 5 As shown, the vertical ribs are assembled with the upper compression beam clamp and fixed with a clamp, and can only move slightly in the single downward pressing direction;

[0012] Step 4: If Figure 6 As shown, use a pin to connect the upper pressure beam clamp to the card support, and then fix it with the fixture bottom plate. Adjust the clamping mechanism on the upper pressure beam to make the vertical rib contact with the bottom plate. Use mechanical means such as grinding and scraping to repair the bottom end of the vertical rib, and finally make it fit closely with the bottom plate surface, with a fitting gap of no more than 0.1mm.

[0013] Step 5: Remove the upper pressure beam together with the vertical ribs, use alcohol or acetone to clean the vertical ribs and the bottom plate surface to be welded, and then reassemble according to step 4;

[0014] Step 6: Fine-tune the adjusting screw to make the ejector move upward until the protrusion reaches the anti-deformation requirement, and then press the vertical ribs upward through the clamping mechanism of the upper pressure beam clamp to form a tight clamp on the bottom plate;

[0015] Step 7: After the T-shaped structure is pre-assembled, the robot is called to calibrate the weld, generate a path program, set welding parameters, introduce argon gas into the heat sink A and heat sink B, and perform positioning welding and welding in turn to finally complete the fillet weld connection;

[0016] Step 8: After welding is completed, first adjust the adjusting screw to lower the height of the ejector to remove its ejection force on the bottom surface of the base plate, then loosen the upper pressure beam clamp, separate it from the vertical ribs, then remove the pin shaft and take down the upper pressure beam;

[0017] Step 9: Loosen the tightening screws and the pressing plate in turn to obtain the T-joint weldment. After removing it, perform appropriate surface splashing, oxide skin cleaning, etc.;

[0018] Step 10: Repeat steps 1-9 to assemble and connect the panel type components, and weld the long stringers and bulkhead type reinforcement rib structures on the inner surface of the skin.

[0019] Step 11: After the welding of multiple T-joints in the wall panel is completed, vacuum stress relief annealing treatment is carried out, and the wall panel profile is fixed with a special frame-type fixture. After taking it out, the appearance surface quality with high precision and no edge traces is obtained, such as Fig.11 shown.

[0020] The beneficial effects of this new technology are:

[0021] The present invention uses the novel process technology to replace the unidirectional vertical downward pressure pre-tightening method with the upper and lower simultaneous clamping pre-assembly method for pre-welding preparation, thereby avoiding the original deformation trend on both sides of the welding area of ​​the T-joint bottom plate. By means of the convex amount control of the lower ejection mechanism and the rapid cooling of the auxiliary copper plate in the welding area, and then by the reasonable reverse deformation angle preset, the outer surface of the bottom plate without edge traces can be obtained. The outer surface of the wall plate obtained by using this technology for manufacturing large-scale welded wall panels, i.e., the pneumatic surface, is smooth and continuous, without obvious edge lines, the corrugation is controlled, and the profile precision is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of a typical laser welded T-joint;

[0023] Figure 2 This is a schematic diagram of the T-joint laser welding fixture structure;

[0024] Figure 3 is a schematic diagram of the fixture base structure;

[0025] Figure 4 This is a schematic diagram of installing the base plate on the fixture;

[0026] Figure 5 This is a schematic diagram of installing the vertical reinforcement on the clamping mechanism;

[0027] Figure 6 This is a schematic diagram of the assembly of the T-joint reinforcement and the bottom plate before welding;

[0028] Figure 7 It is the top view of the T-joint rib and bottom plate before welding;

[0029] Figure 8 This is the AA section view of the fixture;

[0030] Fig. 9 This is the BB section view of the fixture;

[0031] Fig.10 Detailed drawings of the ejector, heat sink A and heat sink B of the fixture base;

[0032] Fig.11 Schematic diagram of the improvement effect of the large multi-T-rib welded wall panel structure without edges.

[0033] In the figure: 1 vertical rib; 2 bottom plate; 3 fixture bottom plate; 3.1 heat sink A; 3.2 heat sink B; 3.3 ejector; 3.4 pressure plate; 3.5 clamping screw; 3.6 adjusting screw; 3.7 clamping plate support; 3.8 pin shaft; 3.9 air path; 4 upper pressure beam. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be further described below in conjunction with specific embodiments and drawings.

[0035] Embodiment 1:

[0036] like Figure 2 As shown, in order to ensure the matching clearance at the weld before welding and the high rigidity fixation during welding, it is generally necessary to use a mechanical method to make the end face of the vertical rib 1 to be welded closely contact with the upper surface of the bottom plate 2. If only a single pressing force is applied normally downward on the vertical rib 1, the material at the position to be welded on the upper surface of the bottom plate 2 will be squeezed, and the material on the lower surface will tend to overflow to both sides, thereby causing the far ends of both sides to warp, and the cross deformation will be aggravated by the cooling and shrinkage of the fillet weld after welding. The pre-welding pre-assembly operation mode is now optimized, and the upper and lower clamping welding is innovatively adopted instead of unidirectional pressing welding to eliminate the unidirectional deformation trend of the bottom plate 2 material, thereby reducing the accumulation of welding deformation.

[0037] like Figure 2As shown, a new type of T-joint welding fixture is designed, including vertical ribs 1, bottom plate 2, fixture bottom plate 3, heat sink A3.1 and heat sink B3.2. The heat sink A3.1 and heat sink B3.2 are connected and embedded in the fixture bottom plate 3 by screws, and the upper surface is flat. The ejector 3.3 and the middle seam formed by the heat sink A3.1 and the heat sink B3.2 are clearance-matched, and can be freely ejected. The bottom is inside the fixture bottom plate 3, and the vertical movement is adjusted by adjusting screws 3.6. The pressing plate 3.4 is tightened by the screws 3. .5 screws to adjust the downward pressure, the clamping screw 3.5 and the clamp bottom plate 3 are threaded, the clamp support 3.7 is fixed to the clamp bottom plate 3 by screws, the pin 3.8 is transitionally matched with the support hole and the upper pressure beam 4, and an overall rigid frame is formed after installation. During use, the vertical rib 1 is rigidly clamped and pressed down by the upper pressure beam 4, and the bottom plate 2 is pressed by the pressure plate 3.4. The downward pressure applied by the upper pressure beam 4 to the vertical rib 1 acts on the bottom plate 2, which is balanced with the ejector 3.3 acting on the bottom plate 2, and can be adjusted by adjusting the screw 3.6;

[0038] During use, an ejector device, namely an ejector 3.3, is provided inside the fixture bottom plate 3, which is embedded inside the heat sink A3.1 and the heat sink B3.2 to form a clearance fit to achieve normal sliding. Four adjusting screws 3.6 are installed at both ends of the bottom surface of the ejector 3.3, which can control the normal lifting and lowering movement through its own axial rotation, thereby directly controlling the amount of activity of the ejector 3.3 protruding from the upper surface of the fixture bottom plate 3, and can form a clamping fit with the upper pressing device, thereby controlling the prestress distribution of the bottom plate 2;

[0039] like Figure 5 As shown, the vertical rib 1 forms a fixed mechanical connection with the upper compression beam 4 by means of shape positioning, such as Figure 6 As shown, the upper pressure beam 4 forms a fixed mechanical connection with the card support 3.7 through two pins 3.8, which can make the vertical rib 1 and the bottom plate 2 perpendicular after pre-assembly to form a T-shaped structure. The downward displacement of the vertical rib 1 can be adjusted by the upper pressure screw, and the bottom plate 2 is pressed downward to form a tight fit;

[0040] like Figure 8 , Fig. 9 As shown, through the innovation of the special welding fixture structure, the bottom plate 2 can be controlled in three states: when the upper end of the ejector 3.3 is lower than the surface of the fixture bottom plate 3, the bottom plate 2 is only subjected to the normal upward prestress transmitted by the vertical rib 1, and the materials on both sides of the weld form in-plane compressive stress; when the upper end of the ejector 3.3 is level with the surface of the fixture bottom plate 3, the pressure transmitted by the vertical rib 1 on the bottom plate 2 is balanced with the ejection force of the ejector 3.3, so that the material outside the clamping area is not subjected to external force and no prestress is generated; when the upper end of the ejector 3.3 is higher than the surface of the fixture bottom plate 3, the bottom plate 2 is also in a force balance state. At this time, after forcibly pressing down the two sides of the bottom plate 2, the pre-deformation can be achieved, thereby having a means to achieve the offset of the welding angle deformation;

[0041] like Fig.10 As shown, in order to further reduce the heat input during laser welding, accelerate the recrystallization rate of the material in the weld area, shorten its cooling time, and achieve rapid cooling of the weld and heat-affected zone, thereby achieving the effect of reducing the post-welding angle deformation, two heat sinks A3.1 and B3.2 are designed in the area near the weld position corresponding to the lower surface of the bottom plate 2. The material is copper, and chamfers are made on the edges of the corresponding ejectors 3.3 respectively. Φ1.2 air outlet holes are evenly distributed on the chamfered inclined surfaces, with a spacing of about 10 to 20 mm; the heat sink A3.1 and the heat sink B3.2 are designed to be hollow structures inside, which can form a sealing effect after being installed in conjunction with the fixture bottom plate 3, leaving a gas path channel 3.9, which can be externally piped with high-pressure argon gas, and finally form an argon protective atmosphere on the bottom surface of the bottom plate 2 after the T-shaped structure is pre-assembled, which can not only take away the welding heat of the bottom plate 2 and the ejector 3.3, but also form anti-oxidation protection for the surface;

[0042] like Figure 3 As shown, the length of ejector 3.3 should exceed the length of the weld of vertical rib 1 plus the length of arc starting and arc ending to achieve full coverage, and the width should be ≥ the thickness of the material of vertical rib 1. The length of heat sink A3.1 and heat sink B3.2 should fully surround ejector 3.3, and the clearance around the circle should be 0.2-0.5mm. The material of ejector 3.3 is copper, which is conducive to heat dissipation. If the ejection strength is insufficient, steel material can be used, and cooling water pipelines can be added inside to ensure the heat dissipation effect.

[0043] Calculation method of pre-deformation of bottom plate 2: firstly, adjust ejector 3.3 to be flush with the surface of bottom plate 3 of fixture, then install the clamping mechanism of upper pressure beam 4, ensure the gap between vertical rib 1 and bottom plate 2 before welding, carry out laser welding of double-sided fillet welds, after completion and cooling, measure the warping of bottom plates on both sides and the surface of bottom plate 3 of fixture to obtain angle A, and measure the horizontal distance B between weld and edge, then the protrusion L of ejector 3.3 = B × tanA; in actual use, the protrusion of ejector 3.3 can be fine-tuned according to the angular deformation and corrected at any time; this method can obtain the bottom plate 2 surface without welding edge traces under appropriate parameters, such as Fig.11 As shown;

[0044] For the structure of the wall panel type with horizontal and vertical cross T-joints, a special anti-deformation welding fixture can be uniformly designed for the longitudinal long stringer T-joints, and then a special anti-deformation welding fixture can be uniformly designed for the transverse bulkhead T-joints, and the overall small deformation welding manufacturing of the wall panel can be realized in steps. Since the cumulative deformation is greatly reduced, the number of intermediate heat treatment corrections can be avoided, and the accumulation of process turnover errors can be avoided. The cyclic iteration further improves the overall accuracy of the wall panel after welding, such as Fig.11 shown.

[0045] Embodiment 2:

[0046] The steps of controlling the angular deformation of laser welded T-joints are as follows:

[0047] Step 1: If Figure 3 As shown, remove the upper pressing beam 4, adjust the adjusting screw 3.6 so that the ejector 3.3 does not protrude from the upper surface of the fixture bottom plate 3, adjust the clamping screw 3.5, and remove the clamping force of the pressing plate 3.4;

[0048] Step 2: If Figure 4 As shown, the bottom plate 2 is mounted on the fixture bottom plate 3, and the edges of the bottom plate 2 are pressed by the pressing plate 3.4, and finally the pressing screws 3.5 are used to apply the pressing force to fix the bottom plate 2;

[0049] Step 3: If Figure 5 As shown, the vertical rib 1 is assembled with the upper compression beam 4 and fixed with a clamp, and can only move slightly in the only downward pressing direction;

[0050] Step 4: If Figure 6 As shown, the upper pressing beam 4 is connected to the clamp support 3.7 by using the pin 3.8, and then fixed with the fixture bottom plate 3, and the clamping mechanism on the upper pressing beam 4 is adjusted to make the vertical rib 1 contact with the bottom plate 2, and the bottom end of the vertical rib 1 is repaired by mechanical means such as grinding and scraping, and finally it is closely matched with the surface of the bottom plate 2, and the fitting gap is not greater than 0.1mm;

[0051] Step 5: Remove the upper pressure beam 4 together with the vertical rib 1, use alcohol or acetone to clean the vertical rib 1 and the surface of the bottom plate 2 to be welded, and then assemble again according to step 4;

[0052] Step 6: Fine-tune the adjusting screw 3.6 to move the ejector 3.3 upward until the protrusion reaches the anti-deformation requirement, and then press the vertical rib 1 upward through the clamping mechanism of the clamping device of the upper pressure beam 4 to form a tight clamping of the bottom plate 2;

[0053] Step 7: After the T-shaped structure is pre-assembled, the robot is called to calibrate the weld, generate a path program, set welding parameters, introduce argon gas into the heat sink A3.1 and heat sink B3.2, and perform positioning welding and welding in turn to finally complete the fillet weld connection;

[0054] Step 8: After welding is completed, first adjust the adjusting screw 3.6 to lower the height of the ejector 3.3 to remove its ejection force on the bottom surface of the bottom plate 2, then loosen the upper pressure beam 4 pressure beam clamp, separate it from the vertical rib 1, then remove the pin 3.8 and take down the upper pressure beam 4;

[0055] Step 9: Loosen the compression screws 3.5 and 3.4 in sequence to obtain the T-joint weldment. After removing it, clean the surface splashes and oxide scales appropriately.

[0056] Step 10: Repeat steps 1-9 to assemble and connect the panel type components, and weld the long stringers and bulkhead type reinforcement rib structures on the inner surface of the skin.

[0057] Step 11: After the welding of multiple T-joints in the wall panel is completed, vacuum stress relief annealing treatment is carried out, and the wall panel profile is fixed with a special frame-type fixture. After taking it out, the appearance surface quality with high precision and no edge traces is obtained, such as Fig.11 shown.

Claims

1. A method for controlling the angular deformation of a laser-welded T-joint, characterized in that: Here are the steps: Step 1: Remove the upper pressure beam (4) pressure device, adjust the adjustment screw (3.6) so that the ejector (3.3) does not protrude from the upper surface of the fixture bottom plate (3), adjust the clamping screw (3.5), and remove the pressure of the pressure plate (3.4); Step 2: Install the base plate (2) on the fixture base plate (3), use the pressure plate (3.4) to press the edges of the base plate (2), and finally use the pressure screws (3.5) to apply pressure to fix the base plate (2); Step 3: Assemble the vertical rib (1) and the upper pressure beam (4) with a clamp and fix them with a clamp so that they can only move slightly in the downward pressure direction; Step 4: Use the pin (3.8) to connect the upper pressure beam (4) clamp to the clamp support (3.7), and then fix it to the fixture bottom plate (3). Adjust the clamping mechanism on the upper pressure beam (4) so ​​that the vertical rib (1) contacts the bottom plate (2). Use grinding and scraping to repair the bottom end of the vertical rib (1) so that it fits tightly with the surface of the bottom plate (2) and the gap is no more than 0.1 mm. Step 5: Remove the upper pressure beam (4) together with the vertical ribs (1), use alcohol or acetone to clean the vertical ribs (1) and the surface of the bottom plate (2) to be welded, and then reassemble according to step 4; Step 6: Finely adjust the adjusting screw (3.6) to move the ejector (3.3) upward until the protrusion reaches the anti-deformation requirement, and then press the vertical rib (1) upward through the clamping mechanism of the upper pressure beam (4) to form a tight clamp on the bottom plate (2); Step 7: After the T-shaped structure is pre-assembled, the robot is called to calibrate the weld, generate a path program, set welding parameters, introduce argon gas into the heat sink A (3.1) and heat sink B (3.2), and perform positioning welding and welding in sequence to finally complete the fillet weld connection; Step 8: After welding is completed, first adjust the adjusting screw (3.6) to lower the height of the ejector (3.3) to remove its ejection force on the bottom surface of part 2, then loosen the clamp of the upper pressure beam (4) to separate it from the vertical rib (1), then remove the pin (3.8) and take down the upper pressure beam (4); Step 9: Loosen the clamping screw (3.5) and the pressure plate (3.4) in sequence to obtain the T-joint weldment. After removing it, perform appropriate surface splash and oxide skin cleaning. Step 10: Repeat steps 1-9 to assemble and connect the wall panel components, and weld the long stringers and bulkhead reinforcement structures on the inner surface of the skin; Step 11: After the welding of multiple T-joints on the wall panels is completed, vacuum stress relief annealing treatment is carried out.

2. The method for controlling the angular deformation of a laser welded T-joint according to claim 1, characterized in that: The heat sink A (3.1) and the heat sink B (3.2) are connected by screws and embedded in the fixture bottom plate (3). The upper surface is flat. The ejector (3.3) and the center seam formed by the heat sink A (3.1) and the heat sink B (3.2) are clearance-matched and can be freely ejected. The bottom is inside the fixture bottom plate (3). The vertical movement is adjusted by adjusting the screw (3.6). The pressure plate (3.4) is adjusted by the clamping screw (3.5). The clamping screw (3.5) is threadedly matched with the fixture bottom plate (3). The clamping plate support (3.7) is fixed to the fixture bottom plate (3) by screws.

3. The method for controlling the angular deformation of a laser welded T-joint according to claim 1 or 2, characterized in that: Four adjusting screws (3.6) are installed at both ends of the bottom surface of the ejector (3.3).

4. The method for controlling the angular deformation of a laser welded T-joint according to claim 1 or 2, characterized in that: The upper pressure beam (4) forms a fixed mechanical connection with the clamping plate support (3.7) via two pins (3.8), so that the vertical ribs (1) and the bottom plate (2) can be pre-assembled at a perpendicular angle to form a T-shaped structure.

5. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 3, characterized in that: The upper pressure beam (4) forms a fixed mechanical connection with the clamping plate support (3.7) via two pins (3.8), so that the vertical ribs (1) and the bottom plate (2) can be pre-assembled at a perpendicular angle to form a T-shaped structure.

6. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 1, 2 or 5, characterized in that: The edges of the ejector (3.3) are chamfered, and Φ1.2 air outlet holes are evenly distributed on the chamfered inclined surface with a spacing of 10 to 20 mm; the heat sink A (3.1) and the heat sink B (3.2) are designed to have a hollow structure inside, which can form a sealing effect after being installed in conjunction with the fixture bottom plate (3), leaving an air path (3.9).

7. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 3, characterized in that: The edges of the ejector (3.3) are chamfered, and Φ1.2 air outlet holes are evenly distributed on the chamfered inclined surface with a spacing of 10 to 20 mm; the heat sink A (3.1) and the heat sink B (3.2) are designed to have a hollow structure inside, which can form a sealing effect after being installed in conjunction with the fixture bottom plate (3), leaving an air path (3.9).

8. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 4, characterized in that: The edges of the ejector (3.3) are chamfered, and Φ1.2 air outlet holes are evenly distributed on the chamfered inclined surface with a spacing of 10 to 20 mm; the heat sink A (3.1) and the heat sink B (3.2) are designed to have a hollow structure inside, which can form a sealing effect after being installed in conjunction with the fixture bottom plate (3), leaving an air path (3.9).

9. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 1, 2, 5, 7 or 8, characterized in that: The method for calculating the pre-deformation amount of the bottom plate (2) is as follows: first, the ejector (3.3) is adjusted to be flush with the surface of the fixture bottom plate (3), and then the upper pressure beam (4) is installed to tighten the mechanism to ensure the pre-welding gap between the vertical rib (1) and the bottom plate (2), and double-sided fillet laser welding is carried out. After completion and cooling, the warping of the bottom plates on both sides and the surface of the fixture bottom plate (3) are measured to obtain an angle A, and at the same time, the horizontal distance B between the weld and the edge is measured, and the protrusion amount L of the ejector (3.3) is L=B×tanA; in actual use, the protrusion amount of the ejector (3.3) can be fine-tuned according to the angular deformation amount and corrected at any time; and the surface of the bottom plate (2) can be obtained without welding edge traces.

10. The method for controlling the angular deformation of a laser welded T-joint as claimed in claim 3, characterized in that: The method for calculating the pre-deformation amount of the bottom plate (2) is as follows: first, the ejector (3.3) is adjusted to be flush with the surface of the fixture bottom plate (3), and then the upper pressure beam (4) is installed to tighten the mechanism to ensure the pre-welding gap between the vertical rib (1) and the bottom plate (2), and double-sided fillet laser welding is carried out. After completion and cooling, the warping of the bottom plates on both sides and the surface of the fixture bottom plate (3) are measured to obtain an angle A, and at the same time, the horizontal distance B between the weld and the edge is measured, and the protrusion amount L of the ejector (3.3) is L=B×tanA; in actual use, the protrusion amount of the ejector (3.3) can be fine-tuned according to the angular deformation amount and corrected at any time; and the surface of the bottom plate (2) can be obtained without welding edge traces.

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