Vertical Penetrating Twin Shoulder Friction Stir Welding Equipment and Method for the Longitudinal Seam of a Storage Tank

Abstract

The present invention relates to the technical field of friction stir welding, and provides a vertical penetration type double-shoulder friction stir welding device and method for the longitudinal seam of a storage tank. The welding device includes: a part tooling assembly; a back synchronous support system arranged inside the part to be welded and configured with a synchronous backing plate; an external welding assembly having an external welding head and a clamping jaw system capable of clamping the part to be welded. A stirring tool and a stationary lower shoulder pad are respectively installed on the external welding head and the synchronous backing plate, thereby realizing the vertical penetration type double-shoulder friction stir welding operation for the longitudinal seam of the storage tank. The present invention adopts a conventional stirring head and a stationary lower shoulder pad, and realizes the synchronous movement of the conventional stirring head and the stationary lower shoulder pad along the welding direction through two drive systems, which can effectively avoid the formation of defects such as incomplete penetration and weak bonding at the root of the weld seam, realizes the penetration type double-shoulder friction stir welding for the longitudinal seam of the storage tank, and improves the welding stability.

Description

Technical Field

[0001] The present invention relates to the technical field of friction stir welding, and particularly to a vertical penetration type double-shoulder friction stir welding device and method for longitudinal seams of a storage tank. Background Art

[0002] Friction stir welding technology is widely used in the manufacturing of aerospace products, especially in the manufacturing of launch vehicle storage tanks. At present, full friction stir welds for launch vehicle storage tanks have been achieved. For the longitudinal seams of the barrel section and shell section of the storage tank, the length of the stirring pin used in conventional friction stir welding is generally less than the thickness of the workpiece to be welded, which easily leads to welding defects such as incomplete penetration and weak connection at the root of the weld, posing a relatively large potential risk. Although traditional double-shoulder friction stir welding can avoid the problem of weak connection and to a certain extent reduce the requirement for pre-welding assembly accuracy, double-shoulder friction stir welding has high requirements for the stirring tool, and the stirring pin cannot use an inclination angle, and the heat input during the welding process is relatively high.

[0003] Patent document CN105382405A discloses a stationary shoulder-assisted support inclined penetration friction stir welding device and method, which realizes friction stir penetration welding by using the method of synchronous movement of a conventional stirring head and a stationary shoulder with a blind hole. This welding method can effectively avoid the defect of incomplete fusion, but this welding device is only applicable to the butt welding of laboratory test plates and fails to achieve vertical friction stir welding. For the curved parts of aerospace storage tanks, this device and method are not applicable. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a vertical penetration type double-shoulder friction stir welding device and method for longitudinal seams of a storage tank.

[0005] According to a vertical penetration type double-shoulder friction stir welding device for longitudinal seams of a storage tank provided by the present invention, it includes:

[0006] A part tooling assembly for fixing the workpiece to be welded;

[0007] A back synchronous support system arranged inside the workpiece to be welded and equipped with a synchronous backing plate for supporting the workpiece to be welded into a circular shape;

[0008] An external welding assembly having an external welding head and a jaw system, the jaw system being capable of pressing the workpiece to be welded, and a stirring tool and a stationary lower shoulder pad are respectively installed on the external welding head and the synchronous backing plate to realize the vertical penetration type double-shoulder friction stir welding operation for the longitudinal seams of the storage tank.

[0009] Preferably, the part tooling assembly includes a tooling base, an internal welding tooling, and an external welding tooling. The bottoms of the internal welding tooling and the external welding tooling are both arranged on the tooling base. The external welding tooling is arranged circumferentially along the internal welding tooling, and the part to be welded is arranged between the internal welding tooling and the external welding tooling. The external welding tooling is fixed and cooperates with the internal welding tooling to jointly clamp the part to be welded.

[0010] Preferably, the back synchronous support system includes an internal support system, a synchronous backing plate, an internal transmission mechanism, internal columns, and an internal base;

[0011] The internal columns are arranged on the internal base. The internal support system is arranged on the internal columns so that the internal columns and the internal welding tooling form an integral body. The internal transmission mechanism can drive the synchronous backing plate to move synchronously with the external welding head.

[0012] Preferably, the internal support system includes a plurality of hydraulic cylinders. The plurality of hydraulic cylinders are installed on the internal columns, and the internal columns and the internal welding tooling form an integral body through the hydraulic cylinders.

[0013] Preferably, the external welding assembly includes an external welding head, a jaw system, a top tensioning system, an external welding transmission system, external welding columns, and an external welding base. The external welding head is arranged at the bottom of the external welding columns and is equipped with a stirring tool;

[0014] The jaw system is arranged on the side of the external welding columns and faces the part to be welded; both ends of the top tensioning system are respectively connected to the internal columns and the external welding columns and can tension the internal columns and the external welding columns.

[0015] Preferably, the external welding head adopts a mechanical external spindle motor;

[0016] The top tensioning system is driven by a winch at the top of the external welding columns to realize the rotational movement of the tensioning arm.

[0017] Preferably, both the internal columns and the external welding columns are equipped with transmission systems, and the two transmission systems belong to the same set of control systems, which can realize the synchronous movement of the external welding head and the synchronous backing plate.

[0018] Preferably, a laser ring scanning device is configured on the external welding head. The laser ring scanning device adopts a laser ring scanning type friction stir welding process detection system, including a laser distance sensor. The laser distance sensor can rotate around the stirring tool, obtain the three-dimensional spatial coordinates of the monitoring point through the encoder in the servo motor and the height of the detection point, and can design a parameter extraction algorithm for online detecting the inclination angle of the stirring tool, the shoulder penetration amount, and the weld deviation during the welding process.

[0019] Preferably, the laser ring scanning device adopts a pressure - detecting elastomer, uses a strain - gauge group bridge to convert the strain signal into an electrical signal, establishes a theoretical relationship between the signal and the upsetting force, and is used to detect, analyze the upsetting - force information during the welding process and perform constant - pressure adaptive control.

[0020] A vertical penetration - type two - shoulder friction stir welding method for the longitudinal seam of a storage tank according to the present invention includes the following steps:

[0021] S1: Preliminary preparation: Assemble the stirring tool on the external welding head, fix the stationary lower - shoulder pad on the synchronous backing plate, observe whether the center of the stirring pin of the stirring tool is located 0 - 3 mm from the center of the kidney - shaped hole of the stationary lower - shoulder pad, start the drive system, and move the stirring tool and the stationary lower - shoulder pad along the welding direction in the no - load state, and observe whether they are synchronized during the process;

[0022] S2: Part assembly: Perform fusion - welding segmented positioning on the welding edges of the parts to be welded to form a complete cylinder, assemble the parts to be welded between the internal welding tooling and the external welding tooling and clamp the parts to be welded, start the top - tensioning system to tension the internal column and the external - welding column, then start the internal - support system to expand the parts to be welded outwards in a circular shape, and then start the jaw system to press the parts to be welded tightly from the outside. At this time, the assembly is completed;

[0023] S3: Positioning welding: After ensuring that the stirring tool and the stationary lower - shoulder pad move synchronously, disassemble the stirring tool and the stationary lower - shoulder pad, replace them with a flat pad without holes and a positioning - welding stirring tool for positioning welding. Ensure that the butt - welding position of the parts to be welded is at the center of the positioning - welding stirring tool, and the surface of the flat pad is in close contact with the lower surface of the parts to be welded. Input the selected welding process parameters into the control system, and adjust the inclination angle of the positioning - welding stirring tool. Start the equipment for positioning welding. The welding method is that the parts to be welded are fixed, and the positioning - welding stirring tool and the flat pad move synchronously along the welding direction;

[0024] S4: Formal welding: Disassemble the positioning - welding stirring tool and the flat pad, replace them with the stirring tool and the stationary lower - shoulder pad, and move them to the welding starting position. Change the welding process parameters in the control system of the equipment. After centering again, start the friction stir welding equipment for formal welding. The welding method is that the parts to be welded are fixed, and the stirring tool and the stationary lower - shoulder pad move synchronously along the welding direction. During the process, the penetration amount can be adjusted according to the actual situation.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention uses a conventional stirring head and a stationary lower shoulder pad to replace the traditional double-shoulder stirring tool. Through two drive systems, the conventional stirring head and the stationary lower shoulder pad are synchronously moved along the welding direction, realizing the penetration double-shoulder friction stir welding of the longitudinal seam of the storage tank, which can effectively avoid the formation of defects such as incomplete penetration and weak bonding at the root of the weld seam; adding a filling material into the waist-shaped hole of the stationary lower shoulder pad can eliminate the defects at the starting point of the penetration friction stir weld.

[0027] 2. For welded parts with a thickness of more than 6 mm, the present invention usually uses friction stir double-sided welding for welding. Its assembly and welding time are doubled compared with single-sided welding, and the back weld needs to be polished after welding. However, using penetration friction stir welding can achieve single-pass welding forming and does not require polishing the back weld, greatly saving the product production time.

[0028] 3. Aiming at the problems of the traditional double-shoulder stirring tool, such as difficult processing and manufacturing, high dimensional accuracy requirements for the upper and lower shaft spacing, cumbersome centering of the stirring tool during the welding process, inability to adjust the penetration amount and inclination angle, low life of the stirring tool, large heat generation during the welding process, and narrow welding process window, etc., the penetration double-shoulder friction stir welding tool adopted in the present invention is the same as the traditional stirring tool, and the control during the welding process is relatively simple. At the same time, the penetration amount and inclination angle can be adjusted, which reduces the design and control difficulty of the stirring tool to a certain extent and further improves the joint quality.

[0029] 4. Compared with the conventional vertical friction stir welding longitudinal seam equipment, the equipment in the present invention adds a synchronous backing plate to the back support system. When using a stationary lower shoulder pad with holes, vertical penetration friction stir welding can be realized; when using a flat pad without holes, traditional vertical friction stir welding can be realized. Therefore, the welding mode can be switched to realize the multi-functional operation of the welding equipment and meet the welding requirements under different conditions.

[0030] 5. Based on the multi-parameter perception, intelligent tool shank perception and end motion detection during the laser ring-scanning friction stir welding process, the present invention detects and on-line intelligently controls the downward pressure / downward force, inclination angle, and weld deviation during the welding process, which can realize the penetration double-shoulder friction stir welding process of the longitudinal seams of the storage tank shell section, cylinder section, etc., eliminate potential welding risks such as incomplete penetration and weak bonding, and finally obtain high-quality welded joints, realizing a breakthrough in the intelligent control technology of the friction stir welding process of complex structural parts, improving the welding stability and obtaining high-quality weld seams. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects, and advantages of the present invention will become more apparent:

[0032] Figure 1Front structural schematic diagram of the present invention;

[0033] Figure 2 Top structural schematic diagram of the present invention;

[0034] Figure 3 Front structural schematic diagram of the part tooling assembly;

[0035] Figure 4 Top structural schematic diagram of the part tooling assembly;

[0036] Figure 5 Front structural schematic diagram of the back synchronous support system;

[0037] Figure 6 Side structural schematic diagram of the back synchronous support system;

[0038] Figure 7 Schematic diagram of the placement position of the shoulder pad waist-shaped hole of the filling material at rest;

[0039] Figure 8 Side structural schematic diagram of the external welding assembly;

[0040] Figure 9 Top view schematic diagram of the shoulder pad at rest;

[0041] Figure 10 Cross-sectional structural schematic diagram of the shoulder pad at rest.

[0042] The figure shows:

[0043] Part tooling assembly 1;

[0044] Back synchronous support system 2;

[0045] External welding assembly 3;

[0046] Tooling base 4;

[0047] Internal welding tooling 5;

[0048] External welding tooling 6;

[0049] Parts to be welded 7;

[0050] Internal support system 8;

[0051] Synchronous backing plate 9;

[0052] Internal transmission mechanism 10;

[0053] Internal column 11;

[0054] Internal base 12;

[0055] Shoulder pad at rest 13;

[0056] Waist-shaped hole 131;

[0057] External welding head 14;

[0058] Clamping jaw system 15;

[0059] Top tensioning system 16;

[0060] External welding drive system 17;

[0061] External welding column 18;

[0062] External welding base 19;

[0063] Stirring tool 20;

[0064] Filling material 21;

[0065] Laser ring scanning device 22. Detailed implementation manners

[0066] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0067] Embodiment 1:

[0068] To solve the inadaptability of the existing device, the present invention provides a vertical penetration type double-shoulder friction stir welding device for the longitudinal seam of a storage tank, which is applicable to the vertical penetration type double-shoulder friction stir welding of the longitudinal seams of the cylinder section and the shell section of the storage tank, as Figures 1 to 10 shown, including a part tooling assembly 1, a back synchronous support system 2, and an external welding assembly 3. The part tooling assembly 1 is used to fix the part to be welded 7 and restrict the movement of the part to be welded 7; the back synchronous support system 2 can support the part to be welded 7 in a circular shape and can simultaneously realize the synchronous movement of the synchronous backing plate 9 and the external welding head 14; the external welding assembly 3 has a clamping jaw system 15, and the clamping jaw system 15 can clamp the part to be welded 7. A stirring tool 20 and a stationary lower shoulder pad 13 are respectively installed on the external welding head 14 and the synchronous backing plate 9, and the operation of vertical penetration type double-shoulder friction stir welding of the longitudinal seam of the storage tank can be realized.

[0069] As Figures 1 to 4As shown in the figure, the part tooling assembly 1 includes a tooling base 4, an internal welding tooling 5, and an external welding tooling 6. The bottoms of the internal welding tooling 5 and the external welding tooling 6 are both arranged on the tooling base 4. The tooling base 4 is mainly used for the overall tooling support. The internal welding tooling 5 mainly cooperates with the back synchronous support system 2 to tightly support the welded part 7 externally, ensuring the flatness and roundness of the welding edge of the welded part 7 and preventing edge dislocation. The welded part 7 is arranged between the internal welding tooling 5 and the external welding tooling 6. The external welding tooling 6 is fixed, and the external welding tooling 6 and the internal welding tooling 5 cooperate to clamp the welded part 7 together.

[0070] Furthermore, the internal welding tooling 5 and the external welding tooling 6 can be replaced according to the size of the welded part 7 to ensure that the equipment can be applied to the penetration type double-shoulder friction stir welding of longitudinal seams of shell sections and cylinder sections with various diameters.

[0071] As Figure 5 、 Figure 6 shown in the figure, the back synchronous support system 2 includes an internal support system 8, a synchronous backing plate 9, an internal transmission mechanism 10, internal columns 11, and an internal base 12. The internal columns 11 are arranged on the internal base 12, and the internal support system 8 is arranged on the internal columns 11. The internal support system 8 includes a plurality of hydraulic cylinders. The plurality of hydraulic cylinders are installed on the internal columns 11, and their main function is to form an integral body of the internal columns 11 and the internal welding tooling 5, improving the rigidity of both. The synchronous backing plate 9 is installed with a stationary lower shoulder pad 13, and its main function is to support the back of the welding edge of the welded part 7 during the welding process, playing a supporting role. The internal transmission mechanism 10 is arranged on the internal columns 11, and the internal transmission mechanism 10 can enable the synchronous backing plate 9 to move synchronously with the external welding head 14. The internal base 12 is mainly used for overall support.

[0072] As Figure 7 、 Figure 8 shown in the figure, the external welding assembly 3 includes an external welding head 14, a clamping jaw system 15, a top tensioning system 16, an external welding transmission system 17, an external welding column 18, and an external welding base 19. A stirring tool 20 is installed on the external welding head 14. The external welding head 14 selects a mechanical external spindle motor, which improves the welding ability and stability while also improving the maintenance economy. The clamping jaw system 15 is arranged on the side of the external welding column 18 and faces the welded part 7 directly, mainly used for clamping the welded part 7. The top tensioning system 16 is driven by a winch at the top of the external welding column 18 to realize the rotational movement of the tensioning arm. After reaching the position, the hydraulic drive mechanism at the top of the internal column 11 pushes the pin for locking. The top tensioning system 16 is used to connect the internal column 11 and the external welding column 18, improving the top rigidity and reducing the opening amount when the welded part 7 is welded to the upper end. It should be noted that both the internal column 11 and the external welding column 18 are equipped with transmission systems, and both belong to the same control system, enabling the synchronous movement of the external welding head 14 and the synchronous backing plate 9.

[0073] Specifically, the stationary lower shoulder pad 13 has a kidney-shaped hole 131 for containing the filling material 21. The length of the stirring pin of the stirring tool 20 is 1 mm greater than the thickness of the part to be welded 7. The diameter of the stationary lower shoulder pad 13 is 6 mm greater than the diameter of the shoulder on the stirring tool 20. The length of the kidney-shaped hole 131 of the stationary lower shoulder pad 13 is 8 mm greater than the diameter of the root of the stirring pin of the stirring tool 20. The width of the kidney-shaped hole 131 of the stationary lower shoulder pad 13 is 4 mm greater than the diameter of the root of the stirring pin of the stirring tool 20. The depth of the kidney-shaped hole 131 of the stationary lower shoulder pad 13 is 1.5 mm greater than the difference between the thickness of the part to be welded 7 and the length of the needle of the stirring tool 20.

[0074] Furthermore, the length of the filling material 21 is 0.1 - 1 mm less than the length of the kidney-shaped hole 131 of the stationary lower shoulder pad 13. The width of the filling material 21 is 0.1 - 1 mm less than the width of the kidney-shaped hole of the stationary lower shoulder pad. The thickness of the filling material 21 is 0 - 0.5 mm less than the depth of the kidney-shaped hole of the stationary lower shoulder pad, and it has a clearance fit with the kidney-shaped hole of the stationary lower shoulder pad. During tack welding, only the stationary lower shoulder pad 13 with holes needs to be replaced with a flat pad without holes, which improves the flexibility of welding and assembly.

[0075] As Figure 8 shown, the external welding head 14 is equipped with a laser ring-scanning device 22. The laser ring-scanning device 22 uses a laser ring-scanning type friction stir welding process detection system. The laser distance sensor rotates around the stirring tool 20, and the spatial three-dimensional coordinates of the monitoring point are obtained through the encoder in the servo motor and the height of the detection point. An algorithm for extracting parameters such as the inclination angle of the stirring tool 20, the shoulder penetration amount, and the weld deviation during the welding process is designed.

[0076] Furthermore, the laser ring-scanning device 22 uses a multi-parameter detection system for weld position and posture based on end motion detection to realize the synchronous detection of multiple parameters such as weld deviation, penetration amount, and posture, and restore the three-dimensional morphology of the surface of the part to be welded 7 near the stirring tool 20. An adaptive PID controller based on reinforcement learning is used to realize adaptive tracking control during the welding process. At the same time, the laser ring-scanning device 22 uses a pressure detection elastomer, and the strain signal is converted into an electrical signal by using a strain gauge group bridge to establish a theoretical connection between the signal and the upsetting force, so as to detect, analyze, and perform constant pressure adaptive control on the upsetting force information during the welding process.

[0077] The present invention also provides a vertical double-shoulder friction stir welding method for the longitudinal seam of a storage tank, which uses a vertical penetration double-shoulder friction stir welding device for the longitudinal seam of a storage tank, and includes the following steps:

[0078] First step, preliminary preparation: Assemble the stirring tool 20 on the external welding head 14, fix the static lower shaft shoulder spacer 13 on the synchronous backing plate 9, observe whether the center of the stirring pin of the stirring tool 20 is positioned 0 - 3 mm from the center of the kidney-shaped hole 131 of the static lower shaft shoulder spacer 13, start the drive system, and move the stirring tool 20 and the static lower shaft shoulder spacer 13 along the welding direction under no-load conditions to observe whether they are synchronous during the process;

[0079] Second step, part assembly: Perform fusion welding and segmented positioning on the welding edges of the parts to be welded 7 to form a complete cylinder. With the cooperation of the crane, lift the parts to be welded 7 between the internal welding fixture 5 and the external welding fixture 6, clamp the parts to be welded 7 with the fixture, start the top tensioning system 16 to tension the internal column 11 and the external welding column 18, then start the internal support system 8 to expand the parts to be welded 7 outward in a circular shape, and then start the jaw system 15 to press the parts to be welded 7 from the outside. At this time, the assembly is completed;

[0080] Third step, positioning welding: After ensuring the synchronous movement of the stirring tool 20 and the static lower shaft shoulder spacer 13, disassemble the stirring tool 20 and the static lower shaft shoulder spacer 13, replace them with a flat spacer without holes and a positioning welding stirring tool (the needle length is selected to be 2 - 2.5 mm) for positioning welding. Ensure that the welded joint of the parts to be welded 7 is located at the center of the positioning welding stirring tool, and the surface of the flat spacer is in close contact with the lower surface of the parts to be welded 7. Input the selected welding process parameters into the control system, and adjust the inclination angle of the positioning welding stirring tool. Start the equipment for positioning welding. The welding method is that the parts to be welded 7 are fixed, and the positioning welding stirring tool and the flat spacer move synchronously along the welding direction;

[0081] Fourth step, formal welding: Disassemble the positioning welding stirring tool and the flat spacer, replace them with the stirring tool 20 and the static lower shaft shoulder spacer 13, and move them to the welding starting position. Change the welding process parameters in the control system of the equipment. After centering again, start the friction stir welding equipment for formal welding. The welding method is that the parts to be welded 7 are fixed, and the stirring tool 20 and the static lower shaft shoulder spacer 13 move synchronously along the welding direction. During the process, the penetration depth can be adjusted according to the actual situation.

[0082] In practical applications, the inclination angle of the stirring tool 20 fixed on the external welding head 14 is preferably 2.5°. During the welding process, the part fixture assembly 1 and the parts to be welded 7 are stationary. The stirring pin of the stirring tool 20 penetrates the parts to be welded 7 and inserts into the kidney-shaped hole of the static lower shaft shoulder spacer 13. The external welding head 14, the synchronous backing plate 9, the stirring tool 20, the static lower shaft shoulder spacer 13, and the filler material 21 move along the welding direction with the drive system and always remain on the same axis until the welding is completed. The present invention can achieve vertical penetration double-shaft shoulder friction stir welding, which can be applied to the longitudinal seam welding of storage tank barrel sections and shell sections, eliminating the potential risks of incomplete penetration and weak connection at the root of the weld seam.

[0083] Example 2:

[0084] This example is an optimized example of Example 1. Taking the friction stir welding of a 2219 aluminum alloy cylinder segment wall plate with a thickness of 10 mm as an example, the steps of friction stir welding are described using a vertical penetration type double shoulder friction stir welding device and corresponding tools.

[0085] In this example, the part fixture assembly 1 is applicable to a cylinder segment with a diameter of 3350 mm. The parts to be welded 7 are 4 identical 1 / 4 arc wall plates, with dimensions of 2631 mm (arc length) × 1945 mm (height) × 10 mm (thickness); the upper shoulder diameter of the stirring tool 20 is 26 mm, and the stirring pin is a conical stirring pin with three cutting surfaces and a right-handed thread, with a pin length of 11 mm and a root diameter of 6 mm; the stationary lower shoulder pad 13 has a kidney-shaped hole, the lower shoulder diameter is 32 mm, the kidney-shaped hole is located at the center of the stationary lower shoulder pad 13, with dimensions of 16 mm (length) × 10 mm (width) × 2.5 mm (depth); the filling material 21 is a kidney-shaped block of 2219 aluminum alloy, which is the same material as the parts to be welded 7, with dimensions of 15.5 mm (length) × 9.5 mm (width) × 2 mm (thickness), and has a clearance fit with the kidney-shaped hole of the stationary lower shoulder pad 13.

[0086] The principle of the vertical penetration type double shoulder friction stir welding in this example is as follows:

[0087] I. Preliminary preparation: Assemble the stirring tool 20 on the external welding head 14, fix the stationary lower shoulder pad 13 on the synchronous backing plate 9, observe whether the center of the stirring pin of the stirring tool 20 is located 0 - 3 mm from the center of the kidney-shaped hole of the stationary lower shoulder pad 13, start the drive system, and move the stirring tool 20 and the stationary lower shoulder pad 13 along the welding direction under no-load conditions, and observe whether they are synchronized during the process;

[0088] II. Part assembly: Perform fusion welding segmented positioning on the welding edges of the parts to be welded 7 to form a complete cylinder. With the cooperation of the overhead crane, lift the parts to be welded 7 between the internal welding fixture 5 and the external welding fixture 6, clamp the parts to be welded 7 with the fixture, start the top tensioning system 16 to tension the internal column 11 and the external welding column 18, then start the internal support system 8 to expand the parts to be welded 7 outward in a circular shape, and then start the jaw system 15 to clamp the parts to be welded 7 from the outside. At this time, the assembly is completed;

[0089] III. Tack Welding: After ensuring the synchronous movement of the stirring tool 20 and the stationary lower shoulder pad 13, remove the stirring tool 20 and the stationary lower shoulder pad 13, replace them with a flat pad without holes and a tack-welding stirring tool (the needle length is selected to be 2 - 2.5 mm) for tack welding. Ensure that the butt-welding position of the part to be welded 7 is at the center of the tack-welding stirring tool, and the surface of the flat pad is in close contact with the lower surface of the part to be welded 7. Input the selected welding process parameters into the control system (rotation speed is 600 r / min, welding speed is 200 mm / min), and adjust the inclination angle of the tack-welding stirring tool (the inclination angle is 2.5°). Start the equipment for tack welding. The welding method is that the part to be welded 7 remains stationary, and the tack-welding stirring tool and the flat pad move synchronously along the welding direction;

[0090] IV. Formal Welding: Remove the tack-welding stirring tool and the flat pad, replace them with the stirring tool 20 and the stationary lower shoulder pad 13, and move them to the welding starting position. Change the welding process parameters in the control system of the equipment (rotation speed is 500 r / min, welding speed is 150 mm / min, inclination angle is 2.5°). After centering again, start the friction stir welding equipment for formal welding. The welding method is that the part to be welded 7 remains stationary, and the stirring tool 20 and the stationary lower shoulder pad 13 move synchronously along the welding direction. The penetration amount can be adjusted according to the actual situation during the process.

[0091] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0092] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments and features in the embodiments of the present application can be combined arbitrarily.

Claims

1. A vertical penetration double-shoulder friction stir welding device for tank longitudinal seams, characterized in that: include: A parts and tooling assembly (1) for fixing the parts to be welded (7); A back synchronous support system (2) arranged inside the welded part (7) and provided with a synchronous pad (9) for supporting the welded part (7); The external welding assembly (3) comprises an external welding head (14) and a pressure claw system (15), wherein the pressure claw system (15) is capable of pressing the welded part (7), and a stirring tool (20) and a stationary lower shoulder pad (13) are respectively installed on the external welding head (14) and the synchronous pad (9), thereby realizing a vertical penetrating double-shoulder friction stir welding operation of a tank longitudinal seam; The part tooling assembly (1) comprises a tooling base (4), an inner welding tooling (5), and an outer welding tooling (6); the bottoms of the inner welding tooling (5) and the outer welding tooling (6) are both arranged on the tooling base (4); the outer welding tooling (6) is arranged along the circumference of the inner welding tooling (5), and the welded part (7) is arranged between the inner welding tooling (5) and the outer welding tooling (6); the outer welding tooling (6) is fixed and cooperates with the inner welding tooling (5) to clamp the welded part (7); The back synchronous support system (2) comprises an internal support system (8), a synchronous pad (9), an internal transmission mechanism (10), an internal column (11) and an internal base (12); The internal column (11) is arranged on the internal base (12), the internal support system (8) is configured on the internal column (11) so that the internal column (11) and the internal welding tool (5) form a whole, and the internal transmission mechanism (10) can drive the synchronous pad (9) to achieve synchronous movement with the external welding machine head (14); The back synchronous support system (2) realizes the rounding of the welded part (7) through the cooperation of the internal support system (8), the synchronous pad (9) and the internal transmission mechanism (10), and the pressing claw system (15) cooperates with the back synchronous support system (2) to press the welded part (7).

2. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 1 is characterized in that: The internal support system (8) comprises a plurality of hydraulic cylinders, wherein the plurality of hydraulic cylinders are mounted on an internal column (11), and the internal column (11) and the internal welding tool (5) are formed into a whole by the hydraulic cylinders.

3. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 1 is characterized in that: The external welding assembly (3) comprises an external welding head (14), a pressure claw system (15), a top tensioning system (16), an external welding transmission system (17), an external welding column (18), and an external welding base (19); the external welding head (14) is arranged at the bottom of the external welding column (18) and is equipped with a stirring tool (20); The pressure claw system (15) is arranged on the side of the outer welding column (18) and faces the welded part (7); the two ends of the top tensioning system (16) are respectively connected to the inner column (11) and the outer welding column (18) and are capable of tensioning the inner column (11) and the outer welding column (18).

4. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 3 is characterized in that: The external welding machine head (14) adopts a mechanical external spindle motor; The top tensioning system (16) is driven by a winch at the top of the externally welded column (18) to achieve rotational movement of the tensioning arm.

5. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 3 is characterized in that: The inner column (11) and the outer welding column (18) are both equipped with a transmission system, and the two transmission systems belong to the same control system, which can achieve synchronous movement of the outer welding machine head (14) and the synchronous pad (9).

6. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 3 is characterized in that: The external welding machine head (14) is provided with a laser circular scanning device (22). The laser circular scanning device (22) adopts a laser circular scanning type stir friction welding process detection system, including a laser distance measuring sensor. The laser distance measuring sensor can rotate around the stirring tool (20), obtain the spatial three-dimensional coordinates of the monitoring point through the encoder in the servo motor and the height of the detection point, and can design a parameter extraction algorithm for online detection of the inclination angle, shoulder pressing amount and weld deviation of the stirring tool (20) during the welding process.

7. The vertical penetration double-shoulder friction stir welding equipment for tank longitudinal seams according to claim 6, characterized in that: The laser ring scanning device (22) adopts a pressure detection elastic body and utilizes a strain gauge bridge to convert a strain signal into an electrical signal, thereby establishing a theoretical connection between the signal and the upsetting force, so as to detect and analyze the upsetting force information during the welding process and to perform constant pressure adaptive control.

8. A vertical penetration double-shoulder friction stir welding method for tank longitudinal seams, characterized in that: The vertical penetration double-shoulder friction stir welding device for the longitudinal seam of a tank according to any one of claims 1 to 7 comprises the following steps: S1: Preliminary preparation: Assemble the stirring tool (20) on the external welding machine head (14), fix the stationary lower shoulder pad (13) on the synchronous pad (9), observe whether the center of the stirring needle of the stirring tool (20) is placed 0 to 3 mm away from the center of the waist-shaped hole of the stationary lower shoulder pad (13), start the transmission system, and move the stirring tool (20) and the stationary lower shoulder pad (13) along the welding direction in a no-load state, and observe whether the two are synchronized during the process; S2: Parts assembly: The welding edge of the welded part (7) is welded and positioned in sections to form a complete cylinder, the welded part (7) is assembled between the inner welding fixture (5) and the outer welding fixture (6) and the welded part (7) is clamped, the top tensioning system (16) is started to tighten the inner column (11) and the outer welding column (18), then the internal support system (8) is started to support the welded part (7) outward, and then the pressure claw system (15) is started to press the welded part (7) from the outside, and the assembly is completed at this time; S3: Position welding: After ensuring that the stirring tool (20) and the stationary lower shoulder pad (13) move synchronously, the stirring tool (20) and the stationary lower shoulder pad (13) are removed, and a flat pad without holes is replaced to perform position welding with the positioning welding stirring tool, ensuring that the welding point of the welded part (7) is located at the center of the positioning welding stirring tool, and the surface of the flat pad is in close contact with the lower surface of the welded part (7), the selected welding process parameters are input into the control system, and the inclination angle of the positioning welding stirring tool is adjusted, and the equipment is started to perform position welding, and the welding method is that the welded part (7) is fixed and the positioning welding stirring tool and the flat pad move synchronously along the welding direction; S4: Formal welding: Remove the positioning welding stirring tool and the flat pad, replace them with the stirring tool (20) and the stationary lower shoulder pad (13), and move them to the welding starting position. Change the welding process parameters in the control system of the equipment. After centering again, start the stir friction welding equipment for formal welding. The welding method is that the welded part (7) is fixed, and the stirring tool (20) and the stationary lower shoulder pad (13) move synchronously along the welding direction. During the process, the pressing amount can be adjusted according to the actual situation.

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