A dual laser beam welding shielding gas adaptive control device for T-shaped welds

Abstract

The present invention discloses an adaptive control device for dual laser beam welding with shielding gas for T-shaped welds. The device includes a stringer clamping assembly, a skin clamping assembly, shielding gas assemblies on both sides and back, a bottom workbench, a control assembly, and a laser head. The back shielding gas assembly includes a shielding gas inlet, a shielding gas outlet, and a shielding gas groove. The skin and stringer clamping assemblies of the present invention are fixed by pressure strips and pressure plates, and the columns of the fixed pressure plates are fixed to the workbench; the present invention can be applied to the dual-sided dual laser beam synchronous welding of skins and stringers of different thicknesses, and can detect the flow of synchronous shielding gas on both sides and back shielding gas during welding, and force it to close when the shielding gas reaches a threshold value. This design can accurately protect the weld area with shielding gas during welding, thereby reducing welding deformation, reducing or even eliminating residual stress after welding.

Description

Technical Field

[0001] The invention belongs to the field of laser welding, and in particular relates to an adaptive control device for double laser beam welding shielding gas for T-shaped welds. Background Art

[0002] In the manufacturing of large and complex wall panels and cabins in aerospace, laser welding is an ideal connection process technology for such materials and structures. Compared with traditional riveting and machining, laser welding has the advantages of significant weight reduction, good air tightness, high fatigue performance, high production efficiency, easy automation, and flexibility. The use of welded T-joint structure to replace traditional riveting not only greatly reduces its weight, but also improves the air tightness of the component. The dual laser beam double-sided synchronous welding technology can double the welding efficiency, and the joint forming effect is good during the welding process. Compared with the traditional laser welding method, the residual stress of the component after welding is small. In addition, since the dual laser beam double-sided synchronous welding process of the T-shaped structure avoids the damage to the integrity of the skin by the traditional T-shaped structure single-sided welding and double-sided forming process, it is significantly favored in the aviation manufacturing industry.

[0003] During the welding process, residual stress and deformation will inevitably be generated on the welded workpiece due to local heating and subsequent rapid cooling. Even laser welding with concentrated energy and fast welding speed still has residual stress and deformation. Residual stress may cause brittle fracture, fatigue fracture and stress corrosion damage, thereby reducing the strength and service life of the component. Therefore, it is particularly important to study the residual stress and deformation of titanium alloy plate welded components used in aircraft. However, there is currently no operable and targeted equipment for the dual laser beam double-sided synchronous welding method of the skin-stringer T-type structure to reduce or even eliminate the residual stress after welding.

[0004] Chinese patent CN100413635C discloses a device for controlling welding stress and deformation by friction extrusion during welding. The invention applies friction and extrusion to different areas of the weld joint through three rotating friction rods of specific shapes, forcing this part of the metal to undergo plastic deformation and flow in the required direction. A front friction rod and a rear friction rod are provided. The end face of the front friction rod is pressed on the weld toe of the weld, and the rear friction rod is vertically arranged just above the weld. The friction rods pressurize the weld while moving forward. A fixed platform is provided below the lifting plate, and a front friction rod assembly device and a rear friction rod assembly device are provided below the fixed platform. The maximum longitudinal flexural deformation and lateral shrinkage of the test piece obtained by using the device described in the invention are significantly reduced, and welding defects such as pores, shrinkage, and microcracks are greatly reduced.

[0005] Chinese patent CN107891216A discloses a method for preventing stress concentration in welding of high-strength steel thick plates. The invention provides a steel plate, and preheats the steel plate with electric heating; after preheating, the steel plate is welded into a circular steel pipe through a longitudinal seam, and the welding method adopts any one of positioning welding, manual arc welding, gas shielded welding and submerged arc welding; after welding, the steel pipe is electrically heated and insulated, and the insulation temperature is above 160°C, until the weld is naturally cooled; the cooled steel pipe is inspected, and the qualified steel pipe is rounded to complete the production of the arch rib steel pipe. The method for preventing stress concentration in welding of high-strength steel thick plates provided by the present invention reduces the stress concentration generated in the welding process of high-strength steel thick plates and reduces the restraint stress generated in the process of rounding the longitudinal seam of the steel pipe by adopting welding process measures, thereby solving the problem of surface cracks appearing after the longitudinal seam of the steel pipe is rounded, and providing a reliable guarantee for the smooth production of steel structure bridges.

[0006] The above-mentioned existing technical solutions are generally suitable for butt and overlap welding methods, but are not suitable for T-shaped structures, and are not suitable for dual laser beam double-sided synchronous welding. In addition, the size of the clamp and the stress relief gas protection area cannot be changed according to actual welding requirements, which may easily lead to consequences such as a small number of equipment users and unsatisfactory residual stress effect after de-welding. Summary of the invention

[0007] In view of the deficiencies of the above-mentioned prior art, the present invention aims to provide an adaptive control device for dual-laser beam dual-sided synchronous welding of skin-truss T-shaped structures with synchronous synchronization on both sides and back protection gas. The device can cope with the precise clamping of welded parts of different sizes and welding methods, and is applied to the welding of skin-truss T-shaped structures.

[0008] In order to achieve the above object, the specific technical solution of the present invention is as follows:

[0009] A dual laser beam welding shielding gas adaptable control device for T-shaped welds, comprising a workbench, a stringer clamping assembly, a skin clamping assembly, shielding gas assemblies on both sides and at the back, a bottom tooling table, a control assembly, and a laser head. The stringer clamping assembly comprises a stringer fixture table, a stringer clamping fixing plate, and three pressing plates. The stringer clamping fixing plate is fixed to the stringer fixture table by tightening bolts and is used to clamp stringers of different lengths. The stringer fixture table is fixed to the workbench by tightening bolts, and stringers of different thicknesses can be clamped by changing the distance between the stringer clamping fixing plate and the pressing plate. The skin clamping assembly comprises two pressure strips and four fixed pressing plates to fix the skin. The columns of the fixed pressing plate are fixed to the workbench, and skins of different thicknesses can be clamped by changing the distance between the pressure strips and the workbench. The shielding gas assemblies on both sides and at the back comprise a shielding gas inlet, a shielding gas outlet, a shielding gas slot, shielding gas outlets on both sides, and a shielding gas outlet. A gas shielding head, a gas shielding inlet and a gas shielding outlet are arranged on both sides of the workbench. The gas shielding passes through the gas shielding inlet and the gas shielding slot to control the deformation of the skin-truss T-shaped structure to be welded, and then the gas shielding is discharged through the gas shielding outlet. The gas shielding heads on both sides perform welding protection. The bottom workbench is supported by four brackets. The back gas shielding assembly is placed on the bottom workbench. The gas shielding passes into the gas shielding slot through the inlet. During the welding process, the back of the weld is protected by the gas shielding, and the upper surface of the weld is protected by the gas shielding heads on both sides to control or even eliminate residual stress. The control assembly includes a control center, a back gas shielding control and gas flow monitoring device, and a side gas shielding control and gas flow monitoring device, which monitor the back and side gas flows respectively, and stop the gas discharge after reaching the set domain value. The laser head performs laser welding.

[0010] The holes and grooves on the workbench are used to fix and adjust the stringer clamping table. If the stringer clamping table is not installed, the device is used for laser welding of flat plate butt joints; if the stringer clamping table is installed, the device is used for dual laser beam bilateral synchronous welding of skin-stringer T-shaped structure. The holes and grooves on the stringer clamping table are used to fix and adjust the stringer clamping plate. The stringer clamping plate is fixed to the stringer clamping table by tightening bolts, and stringers of different lengths can be clamped by changing the position of the stringer clamping plate.

[0011] Several holes and slots are set on the bottom tooling table to adjust the position of the fixture according to the size of the skin.

[0012] The back shielding gas control and gas flow monitoring equipment monitors the shielding gas flow on the back of the weld. When the set shielding gas threshold value is reached, the back shielding gas outlet is stopped immediately. The shielding gas control and gas flow monitoring equipment on both sides monitor the shielding gas flow on both sides of the weld. When the set shielding gas threshold value is reached, the shielding gas outlet on both sides is stopped immediately.

[0013] Beneficial technical effects brought by the present invention:

[0014] 1. The present invention adjusts the clamping assembly according to the size of the skin and the stringer. The pressure plate is fixed by the column, the movable column, and the column sleeve. The column and the column sleeve are fixed on the working platform. The lower end of the movable column is connected to the column sleeve and fixed by two set screws. The height of the movable column and the column sleeve can be adjusted according to the height of the stringer. The clamp increases the size range of the plate applicable to the equipment, and the clamping height of the clamp can be adjusted according to the thickness of different parts to be welded.

[0015] 2. The truss fixture table of the present invention is provided with a hollow groove, and whether to install the truss fixture table can be selected according to different welding methods. If the truss fixture table is not installed, the equipment can be used for flat plate docking; if the truss fixture table is installed, the equipment can be used for dual laser beam double-sided synchronous welding.

[0016] 3. The present invention adjusts the width of the fixture and the protective gas slot according to different welding methods and different plate sizes, thereby expanding the application range of the equipment and improving the accuracy of residual stress control after welding.

[0017] 4. The present invention sets the shielding gas threshold value according to the real-time welding situation. When the shielding gas flow reaches the threshold value, the shielding gas delivery will be stopped, so as to achieve the purpose of accurately controlling the welding residual stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the device structure.

[0019] Figure 2 Front view of the device.

[0020] Figure 3 Device side view

[0021] Figure 4 Schematic diagram of the structure of the back protection air assembly.

[0022] Figure 5 Schematic diagram of the structure of the beam fixing fixture.

[0023] Numbers marked in the figure: 1 workbench, 2 bottom tooling table, 3 bracket, 5 laser head; 11 beam fixture table, 12 pressure plate, 13 beam clamping fixing plate; 31 protective gas inlet, 32 protective gas outlet, 33 protective gas heads on both sides; 43 protective gas groove; 44 pressure strip; 52 fixed pressure plate; 61 protective gas control and gas flow monitoring equipment on both sides, 62 back protective gas control and gas flow monitoring equipment, 63 control center. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0025] Reference Figure 1-5As shown, a dual laser beam welding shielding gas adaptable control device for T-shaped welds includes a workbench 1, a stringer clamping assembly, a skin clamping assembly, shielding gas assemblies on both sides and back, a bottom tooling table 2, a control assembly 63, and a laser head 5. The stringer clamping assembly includes a stringer clamping table 11, a stringer clamping fixing plate 13 and three pressing plates 12. The stringer clamping fixing plate 13 is fixed to the stringer clamping table 11 by tightening bolts and is used to clamp stringers of different lengths. The stringer clamping table 11 is connected to the stringer clamping table 11 by a fixing bolt. The fixing bolts are fixed on the workbench 1, and the beams of different thicknesses can be clamped by changing the distance between the beam clamping fixing plate 13 and the pressure plate 12; the skin clamping assembly includes two pressure strips 44 and four fixed pressure plates 52 to fix the skin, and the columns of the fixed pressure plates 52 are fixed on the workbench 1, and the skins of different thicknesses can be clamped by changing the distance between the pressure strips and the workbench 1; the two side and back protective gas assemblies include a protective gas inlet 31, a protective gas outlet 32, and a protective gas groove 4 3. Shielding gas heads 33 on both sides, a shielding gas inlet 31 and a shielding gas outlet 32 ​​are arranged on both sides of the workbench 1. The shielding gas is passed from the shielding gas inlet 31 through the shielding gas groove 43 to control deformation protection of the skin-beam T-shaped structure to be welded, and then the shielding gas is discharged through the shielding gas outlet 32. The shielding gas heads 33 on both sides perform welding protection; the bottom workbench 2 is supported by four brackets 3; the back shielding gas assembly is placed on the bottom workbench 2, and the shielding gas is passed into the shielding gas groove 43 through the inlet. During the welding process, the back of the weld is protected by shielding gas, and the upper surface of the weld is protected by shielding gas heads 33 on both sides to control or even eliminate residual stress. The control assembly includes a control center 63, a back shielding gas control and gas flow monitoring device 62, and a side shielding gas control and gas flow monitoring device 61, which monitor the back and side shielding gas flows respectively, and stop the shielding gas discharge after reaching the set domain value; the laser head 5 performs laser welding.

[0026] The holes and grooves on the workbench 1 are used to fix and adjust the stringer clamping platform 11. If the stringer clamping platform 11 is not installed, the device is used for laser welding of flat plate butt joints; if the stringer clamping platform 11 is installed, the device is used for dual laser beam bilateral synchronous welding of the skin-stringer T-shaped structure. The holes and grooves on the stringer clamping platform 11 are used to fix and adjust the stringer clamping fixing plate 13. The stringer clamping fixing plate 13 is fixed to the stringer clamping platform 11 by tightening bolts, and the stringers of different lengths can be clamped by changing the position of the stringer clamping fixing plate 13.

[0027] The bottom tooling table 2 is provided with several holes and slots for adjusting the position of the fixture according to the size of the skin.

[0028] The back shielding gas control and gas flow monitoring equipment 62 monitors the shielding gas flow on the back of the weld, and immediately stops the back shielding gas output when the set shielding gas threshold is reached. The side shielding gas control and gas flow monitoring equipment 61 monitors the shielding gas flow on both sides of the weld, and immediately stops the shielding gas output on both sides when the set shielding gas threshold is reached.

[0029] First determine the welding method, and choose whether to install the stringer clamping table according to the welding method. If it is a flat plate butt welding method, remove the stringer clamping table. If it is a skin-stringer T-type structure, use a threaded column to pass through the stringer clamping table and the workbench, and then use two nuts to fix one side of the stringer clamping table, and repeat the operation to fix the other side of the stringer clamping table.

[0030] The following introduces the assembly and use process of the skin-truss T-shaped structure. The first step is to accurately measure the dimensions of the skin and the truss before welding, determine the position of the skin and truss T-shaped structure, and accurately measure and record the relevant dimensional information. Next, determine the position of the skin, place it parallel and static on the workbench 1, place two pressure strips 44 symmetrically on the skin, and fix the pressure strips 44 with a fixed pressure plate 52, so that the skin is fastened to the workbench 1, and adjust the distance between the fixed pressure plate 52 and the workbench 1 to fix the skin structure of different thicknesses; next, determine the position of the truss and the T-shaped structure, place it vertically on the skin along the welding position, place the truss clamping plate 13 on the truss, and fix the two ends of the pressure plate 12 with three pairs of bolts and nuts respectively, so that it is fixed on the truss clamping plate 13, and adjust the distance between the pressure plate 12 and the truss clamping plate 13 to fix the truss structure of different thicknesses. Then, according to the actual welding parameters, the distance between the two movable plates is adjusted to adjust the range protected by the back shielding gas, and finally the welding position, defocusing amount and incident angle are calibrated. After all the debugging is completed, the T-shaped structure weld is welded on both sides with dual laser beams, and the shielding gas is supplied from the beginning to the end of welding. After welding is completed, the welding device is dismantled and the weldment is taken out.

[0031] The following uses a back protection gas controllable area device for dual laser beam double-sided synchronous welding of a skin-stringer T-shaped structure as an example to illustrate the complete assembly and use process of the present invention.

[0032] First, the size of the welded parts 1 and 2 is accurately measured, and the position of the T-shaped structure is determined. The skin size is 4mm×200mm×500mm, the beam size is 4mm×100mm×500mm, and the T-shaped joint is in the middle of the 200mm side length of the welded parts. The workbench size is 25mm×300mm×650mm, and seven threaded holes are opened on one side of the 650mm length direction, with a threaded hole diameter of 5mm. The back protection groove size is 15mm×50mm×450mm, and the bottom tooling table size is 25mm×500mm×900mm, with several threaded holes, and the outer circle thread hole diameter is 7mm, and the internal thread hole diameter is 5mm. According to the size of the skin and stringers, the size of each part of the clamping assembly is determined. The size of the stringer fixture is 162mm×40mm×110mm, the size of the stringer clamping plate is 14mm×45mm×590mm, three threaded holes are opened in the 590mm length direction, the threaded hole diameter is 5mm, and the size of the three stringer pressure plates is 6mm×14mm×44mm. All fixed columns are opened with threaded grooves of appropriate size and position.

[0033] Secondly, determine the position of the skin and the truss, and thereby determine the exact position of the column, and weld and fix them by spot welding. Place the skin at the determined position, place two pressure strips 44 symmetrically on the skin, and fix the two pressure strips 44 by a clamp fixing plate 52. Insert the steel column at one end of the clamp into the threaded hole preset on the workbench 1 and fix it to the workbench 1. The other end fixes the pressure strip 12 fixing plate 52 by tightening screws, so that the skin is fastened to the workbench 1. The height of the truss is 100mm. Place the truss vertically on the skin along the welding position, insert the movable column into the truss clamping plate 13, and screw three screws with a diameter of 5mm into the threaded holes of the column sleeve to hold the truss pressure plate 12 to fix it.

[0034] Then determine the welding heat input according to the welding parameters, and adjust the movable plate of the back protection groove on both sides of the back protection groove 50mm according to the different welding heat input, so as to change the protection range of the back protection gas. After fixing the movable plate, connect the protection gas pump to the protection gas inlet and turn on the protection gas pump.

[0035] Then set the shielding gas thresholds on both sides and the back, that is, the maximum shielding gas flow rate. When the shielding gas flow rate reaches the threshold, the shielding gas delivery will be stopped.

[0036] After that, the welding position of the dual laser beams was calibrated, and the laser beam spots on both sides were aligned with the vertical junction of the skin and the stringer to complete the focusing. The incident angle of the dual laser beams was adjusted to 30°, the defocus of the dual laser beams was -2mm, the laser power was adjusted to 8000W, and the power of the two laser beams was 4000W each. The welding speed of the robot was set to 35mm·s-1, and the starting and end positions were set. After all preparations were completed, welding was carried out.

[0037] After welding is completed, wait for the weldment to cool to room temperature, remove the truss fixing plate in turn, open the clamp, remove the pressure strip, and obtain the final T-shaped welded structure.

Claims

1. A dual laser beam welding shielding gas adaptable control device for T-shaped welds, characterized in that: It includes a workbench, a stringer clamping assembly, a skin clamping assembly, a back protective gas assembly, a bottom tooling table, a control assembly, and a laser head. The stringer clamping assembly includes a stringer clamping table, a stringer clamping fixing plate and three pressure plates. The stringer clamping fixing plate is fixed to the stringer clamping table by fastening bolts and is used to clamp stringers of different lengths. The stringer clamping table is fixed to the workbench by tightening bolts, and stringers of different thicknesses can be clamped by changing the distance between the stringer clamping fixing plate and the pressure plate; the skin clamping assembly includes two pressure strips and four fixed pressure plates to fix the skin, and the columns of the fixed pressure plate are fixed on the workbench, and skins of different thicknesses can be clamped by changing the distance between the pressure strip and the workbench; the back protective gas assembly includes a protective gas inlet, a protective gas outlet, a protective gas groove, and protective gas heads on both sides, and the protective gas inlet and protective gas outlet are arranged On both sides of the workbench, the shielding gas is passed from the shielding gas inlet through the shielding gas groove to control the deformation of the skin-truss T-shaped structure to be welded, and then the shielding gas is discharged through the shielding gas outlet, and the shielding gas heads on both sides perform welding protection; the bottom workbench is supported by four brackets; the shielding gas components on both sides and the back are placed on the bottom workbench, and the shielding gas is passed into the shielding gas groove through the inlet. During the welding process, the back of the weld is protected by the shielding gas, and the upper surface of the weld is protected by the shielding gas heads on both sides to control or even eliminate residual stress. The control component includes a control center, a back shielding gas control and gas flow monitoring device, and a side shielding gas control and gas flow monitoring device, which monitor the back and side shielding gas flows respectively, and stop the shielding gas discharge after reaching the set threshold; the laser head performs laser welding.

2. The device for controlling T-shaped welds with dual laser beams and shielding gas according to claim 1, characterized in that: The holes and grooves on the workbench are used to fix and adjust the stringer clamping table. If the stringer clamping table is not installed, the device is used for laser welding of flat plate butt joints; if the stringer clamping table is installed, the device is used for dual laser beam bilateral synchronous welding of skin-stringer T-shaped structure. The holes and grooves on the stringer clamping table are used to fix and adjust the stringer clamping fixing plate. The stringer clamping fixing plate is fixed to the stringer clamping table by tightening bolts, and stringers of different lengths can be clamped by changing the position of the stringer clamping fixing plate.

3. The device for controlling T-shaped seam dual laser beams with shielding gas according to claim 1, characterized in that: The side and back protective gas components are placed on the bottom workbench, and the protective gas is passed into the protective groove through the inlet. During the welding process, the back of the weld is protected by the protective gas, and the upper surface of the weld is protected by the protective gas heads on both sides to control or even eliminate residual stress.

4. The device for controlling T-shaped seam dual laser beams with shielding gas according to claim 1, characterized in that: Several holes and slots are set on the bottom tooling table to adjust the position of the fixture according to the size of the skin.

5. The device for controlling T-shaped welds with dual laser beams and shielding gas according to claim 1, characterized in that: The back shielding gas control and gas flow monitoring equipment monitors the shielding gas flow on the back of the weld. When the set shielding gas threshold is reached, the back shielding gas outlet is stopped immediately. The shielding gas control and gas flow monitoring equipment on both sides monitor the shielding gas flow on both sides of the weld. When the set shielding gas threshold is reached, the shielding gas outlet on both sides is stopped immediately.

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