Penetration type double-shaft-shoulder friction stir welding device and method thereof

Abstract

The invention relates to the technical field of welding, and provides a penetrating type double-shaft-shoulder friction stir welding device and a method thereof.The welding device comprises a headstock, a tailstock, an outer clamp, an inner supporting tool, an outer welding machine head and a pumpback lower shaft shoulder system; the head frame and the tail frame are arranged on the lathe bed, arranged on the two sides of a welded part respectively and used for clamping the welded part, and the inner supporting tool is arranged between the head frame and the tail frame and used for rounding the welded part from the interior of the welded part. The outer clamp is arranged in the circumferential direction of the welded part and used for clamping the welded part. And the outer welding machine head and the withdrawing lower shaft shoulder system jointly carry out circular seam penetration type double-shaft shoulder friction stir welding on the welded part. The stirring needle penetrates through the welded part, so that the defects of incomplete welding, weak combination and the like of the circular seam are overcome, and the quality of the circular seam is improved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a penetrating double-shoulder friction stir welding device and a method thereof. Background Art

[0002] Friction stir welding technology was first widely used in the welding production of transport fuel tanks. The main material of fuel tanks is aluminum alloy. There are many circumferential seams in the production process of tanks, such as tank bottom circumferential seams, tank bottom-barrel section circumferential seams, barrel section-barrel section circumferential seams, tank bottom-short shell circumferential seams, etc. The quality of the weld is directly related to the quality of the tank product. At present, conventional friction stir welding is widely used for tank welding, but because the length of the stirring needle of conventional friction stir welding is less than the thickness of the welded parts, defects such as incomplete penetration and weak bonding are prone to occur at the root of the weld.

[0003] Double-shoulder friction stir welding connects the upper and lower shoulders to form a stirring tool through a stirring needle, which can penetrate the base material and avoid defects at the root of the weld. Currently, this technology has been used by SpaceX in the production of circumferential seams for rocket fuel tanks. However, double-shoulder friction stir welding has high requirements on the precision of the stirring tool and the base material, and the stirring needle cannot use an inclination angle. After welding, holes will be left at the tail of the weld, and friction plug repair welding is required to form a complete circumferential seam. It cannot be processed in one go, and the production efficiency is low. In addition, the joint performance obtained by friction plug repair welding is lower than that of friction stir welds.

[0004] In addition to conventional double-shoulder friction stir welding, penetration friction stir welding can also be achieved by using a long stirring needle that is thicker than the parent material and a lower shoulder auxiliary support. For example, patent document CN105382405B discloses a welding method that uses a long stirring needle and a stationary shoulder with a blind hole to simultaneously weld to achieve friction stir penetration welding. This welding method can effectively avoid defects such as incomplete welding. However, due to the presence of a blind hole in the stationary shoulder, there will be a keyhole and a back protrusion at the end of the weld. Although a complete weld can be obtained by leaving upper and lower margins and cutting off the margins after welding, this method wastes materials on the one hand and is not suitable for tank circumferential seam welding on the other. Summary of the invention

[0005] In view of the defects in the prior art, an object of the present invention is to provide a penetrating double-shoulder friction stir welding device and method thereof.

[0006] A penetrating double-shoulder friction stir welding device provided by the present invention comprises a head frame, a tail frame, an external clamp, an internal support tooling, an external welding head and a retracting lower shoulder system; The headstock and tailstock are arranged on the bed and are respectively disposed on both sides of the welded part, and are both used to clamp the welded part; the inner support tooling is arranged between the headstock and tailstock, and is used to support the welded part from the inside of the welded part; the outer clamp is arranged along the circumference of the welded part and is used to clamp the welded part; The external welding head is arranged outside the welded part and the retracted lower shoulder system is arranged inside the welded part so that the external welding head and the retracted lower shoulder system jointly perform circumferential seam penetration double shoulder friction stir welding on the welded part.

[0007] Preferably, the headstock and tailstock adopt the same structure, both comprising a gear plate, a fixed seat, a movable seat and a mandrel; The toothed disc is rotatably arranged on one side of the fixed seat, and the movable seat is arranged below the fixed seat and can move on the bed to realize the movement of the headstock and / or tailstock; the mandrel is arranged at the center of the fixed seat and passes through the fixed seat, and is used for installing the internal support tooling and retracting the lower shoulder system, wherein the toothed disc can rotate around the fixed seat, the mandrel does not rotate with the toothed disc, and can independently move along the axial direction of the fixed seat.

[0008] Preferably, the outer clamp comprises two symmetrically arranged clamp assemblies, each of which comprises a clamp base, a centering toothed disc, a clamping claw and a slip ring; The fixture base is arranged on the bed; the centering toothed disc is installed on one side of the fixture base; a plurality of the clamping claws are circumferentially distributed on the inner side surface of the centering toothed disc and are used for synchronously clamping the welded parts.

[0009] Preferably, the outer clamp is equipped with a rotation system so that the outer clamp can drive the welded parts to rotate.

[0010] Preferably, the inner supporting tooling is detachably configured on the core shaft, and includes a telescopic rod, an outer arc plate and a fixed ring. The inner ends of a plurality of the telescopic rods are connected to the fixed ring and are arranged along the circumference of the fixed ring. The outer end of each of the telescopic rods is connected to one of the outer arc plates. All of the outer arc plates form an annular structure. The diameter of the annular structure when it is supported in a circle is the same as the inner diameter of the part to be welded.

[0011] Preferably, the external welding head is arranged outside the external clamp and a movable base is arranged below, so that the external welding head can move horizontally and / or vertically to realize the retraction and centering of the stirring needle on the external welding head; The external welding machine head is equipped with a retractable system so that the stirring needle can be retracted when welding is completed.

[0012] Preferably, the retracting lower shoulder system comprises a lower shoulder pad, a retracting pad, a rotating head, a retracting shaft and a telescopic connecting rod; One end of the telescopic link is fixed on the core shaft, and the lower shoulder pad is arranged at the other end of the telescopic link through the rotating machine head. By adjusting the telescopic amount of the telescopic link, the contact between the shoulder surface of the lower shoulder pad and the inner side surface of the welded part can be controlled; a through hole is arranged inside the lower shoulder pad, the retraction shaft is arranged inside the telescopic link and the retraction pad is arranged at the end thereof, and the retraction pad is located inside the through hole and can be retracted under the drive of the retraction shaft; A portion of the through hole located above the retraction pad forms a hole, and the hole is used for placing a filling material.

[0013] Preferably, the rotating head is equipped with an independent control system, which can drive the lower shoulder pad to rotate.

[0014] A penetrating double-shoulder friction stir welding method provided by the present invention comprises the following steps: Step 1: Preparation stage: fix the telescopic connecting rod of the retracting lower shoulder system in the mandrel of the head frame, install the lower shoulder pad on the rotating head, install the retracting pad on the retracting shaft, manually start the retracting system, adjust the upper end surface of the retracting pad to be flush with the shoulder surface of the lower shoulder pad, assemble the positioning welding stirring tool on the external welding head, adjust the length of the telescopic connecting rod, ensure that the center of the stirring needle of the positioning welding stirring tool and the center of the retracting pad are on the same straight line, constrain the telescopic connecting rod so as not to move in the axial direction of the welded part and allow the external welding head to move in the radial direction of the welded part; Step 2: Assembly stage: Install the tooling corresponding to the welded parts on the gear discs of the headstock and tailstock, assemble the welded parts onto the tooling, move the bracket to the welding end area, and install the inner support tooling on the two mandrels so that the outer arc plate contacts the welded parts, adjust the inner support tooling to hold the welded parts tightly and select the corresponding claws to install on the centering gear disc, start the moving seat and the bracket to move the welded parts into the outer fixture so that the butt joint of the two welded parts is located between the positioning welding stirring tool and the retraction pad, and ensure that there is no gap or misalignment at the butt joint. After alignment, use the claws to press the welded parts tightly with a full circle, adjust the length of the telescopic connecting rod in the axial direction of the welded parts, so that the shoulder surface of the lower shoulder pad is close to the inner surface of the welded parts, and the assembly is completed; Step 3: Positioning stage: first, position the welded parts by fusion welding, then move the retraction stirring tool and align the retraction stirring tool with the weld joint, input the selected positioning welding process parameters into the control system, adjust the inclination angle of the positioning welding stirring tool, start the external welding head for positioning welding, during positioning welding, the rotating head is not started, the retraction lower shoulder system is stationary, the upper end surface of the retraction pad is still flush with the shoulder surface of the lower shoulder pad, the welding method is that the welded parts rotate with the equipment, and the positioning welding stirring tool and the retraction lower shoulder system are fixed; Step 4: Welding stage: remove the positioning welding stirring tool and replace it with the retraction stirring tool. According to the thickness of the welded parts, determine the extension length of the retraction stirring needle. According to the length of the retraction stirring needle, adjust the retraction amount of the retraction pad. The retraction amount is recorded as the hole depth. Place the filling material in the hole of the lower shoulder pad. Change the welding process parameters in the control system of the equipment. After entering the process parameters in the control system of the rotating machine head, align again. Start the two system programs at the same time for formal welding. The welding method is that the welded parts rotate with the equipment, and the retraction stirring tool and the retraction lower shoulder system are fixed; Step 5: Retraction stage: When the welding program ends, the system automatically starts the retraction program. At this time, the retraction stirring needle and the retraction pad are retracted at the same retraction speed. When the retraction pad is retracted until the upper end surface is flush with the shoulder surface of the lower shoulder pad, it reaches the limit position. At this time, the retraction is stopped, but the lower shoulder pad is still rotating. At this time, the root of the retraction stirring needle is just at the bottom of the welded part, and then the retraction stirring needle continues to be retracted upward until it is flush with the shoulder surface of the upper shoulder. At this time, the welding is completed, and the upper shoulder and lower shoulder pads stop rotating at the same time to obtain a complete weld.

[0015] Preferably, in step 4, the extended length of the retraction stirring needle is the needle length, the needle length is 1 to 3 mm larger than the thickness of the part to be welded, the retraction amount of the retraction pad is the hole depth, the hole depth is 1.5 mm larger than the difference between the retraction stirring needle length and the thickness of the part to be welded, the diameter of the filling material is 0.1 to 1 mm smaller than the hole diameter, and the thickness is 0.1 to 0.5 mm smaller than the hole depth.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention can eliminate the risk of incomplete welding of the tank circumferential seam. Compared with the existing tank circumferential seam welding technology, the invention eliminates the defects of incomplete welding of the circumferential seam, weak bonding, etc. by penetrating the welded parts with a stirring needle, thereby improving the quality of the circumferential seam.

[0017] 2. Although the present invention uses two internal support fixtures, when assembling the internal support fixtures, the fixtures only play the role of supporting the circle, and the arc plate does not play the role of a welding leak plate, and there is no need to form a closed circle. That is, the fixture can be applied to storage tanks of various sizes, and during the assembly process, the fixture does not need to be strictly aligned with the center of the weld, which makes it more convenient to assemble the fixture, improves assembly efficiency, and saves fixture costs.

[0018] 3. When welding the annular seam of the storage tank, the present invention does not leave a keyhole like conventional double-shoulder stir friction welding. Therefore, there is no need to repair the weld by plugging welding. The process can be completed in one go, achieving a high-efficiency welding process and improving production efficiency.

[0019] 4. The headstock and tailstock in the present invention adopt the same structure and are not used in a single way. The retractable lower shoulder system is installed on the core shaft to improve the convenience of assembly and disassembly. When the retractable lower shoulder system is not used, conventional circumferential seam stir friction welding can be achieved. Therefore, the welding mode can be switched to achieve multifunctional operation of the welding equipment, meet the welding needs in different situations, and realize the diversification of welding methods.

[0020] 5. The present invention is based on multi-parameter perception, intelligent tool holder perception and end motion detection during laser circular scanning friction stir welding, and detects and intelligently controls the downward pressure / pressure, inclination angle and weld deviation during the welding process, thereby achieving a breakthrough in the intelligent control technology of the friction stir welding process of complex structural parts, improving welding stability and obtaining high-quality welds. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a schematic diagram of the internal cross-section of the welding device, in which the external fixture is hidden in the figure. In addition, for the convenience of explanation, the external welding head and the retracting lower shoulder system are parallel to the Z direction, the two welded parts are respectively fixed on the fixtures of the head frame and the tail frame, the equipment is moved for docking, the two internal support fixtures respectively support the two welded parts, the retracting stirring tool is assembled on the external welding head, it is ensured that the center of the retracting stirring tool, the center of the lower shoulder pad of the retracting lower shoulder system and the weld joint are aligned, the two welded parts are clamped by the claws of the external fixture, and welding is performed after assembly is completed, the welding method is that the head frame, the tail frame and the external fixture drive the two welded parts to rotate, and the external welding head and the retracting lower shoulder system are fixed; Figure 2 It is a schematic diagram of a circular seam penetration double-shoulder friction stir welding device, wherein the headstock and tailstock can move along the X direction on the bed, the outer fixture is fixed on the bed and does not move, and the headstock and tailstock drive the welded parts to move toward the outer fixture; Figure 3The headstock and tailstock have the same composition and structure, including a toothed disc, a fixed seat, a movable seat and a mandrel. The toothed disc is on one side of the fixed seat, and the movable seat is located below the fixed seat, connecting the bed and the fixed seat. The mandrel is located at the center of the fixed seat and passes through the fixed seat. The movable seat can drive the headstock to move horizontally as a whole, and the toothed disc can rotate circumferentially. The mandrel does not rotate with the toothed disc and can move independently in the horizontal direction. Figure 4 The schematic diagram of the side structure of the external fixture and the external welding head. The external fixture consists of two symmetrically distributed fixtures, including a fixture base, a centering gear disc, claws, and a slip ring. The fixture base is fixed on the bed; the centering gear disc is installed on one side of the fixture base; eighteen claws are evenly distributed on the inner side of the centering gear disc, and the centering gear disc rotates in the same direction and at the same speed as the gear disc. The external welding head is located on the right side of the external fixture and is equipped with a laser ring scanning device. Figure 5 It is a schematic diagram of the front structure of the external fixture and the external welding machine head; Figure 6 This is a schematic diagram of the inner support tooling. The inner support tooling is installed on the core shaft. The telescopic rod on the tooling can be manually adjusted to adjust the diameter of the inner support tooling, which can be applied to tank products with different diameters. Figure 7 Schematic diagram of the retraction stirring tool, the retraction stirring tool includes an upper shaft shoulder and a retraction stirring needle, the shaft shoulder surface of the upper shaft shoulder is an inner concave surface, the retraction stirring needle has a bidirectional thread and three sections, wherein the stirring needle that does not penetrate the welded part is set as a left-hand thread, and the stirring needle that penetrates the welded part and is located in the hole of the lower shaft shoulder pad is set as a right-hand thread; Figure 8 This is a schematic diagram of the placement position of the retraction lower shoulder system and the filling material. The retraction lower shoulder system includes a lower shoulder pad, a retraction pad, a rotating head, a retraction shaft and a telescopic connecting rod. The lower shoulder pad is fixed on the rotating head, the rotating head is fixed on the telescopic connecting rod, the retraction pad is installed on the retraction shaft, and the entire retraction lower shoulder system is installed on the core shaft. The lower shoulder pad is a cylindrical structure. The shoulder surface diameter can be the same as the upper shoulder diameter or different. There is a through hole in the center. The retraction pad is also a cylindrical structure, and the retraction pad diameter is the same as the through hole diameter of the lower shoulder pad. The two have a clearance fit, and the circular hole depth of the lower shoulder pad can be adjusted. The filling material is made of the same material as the part to be welded, which is a cylindrical block. It is placed in the hole of the lower shoulder pad during welding.

[0022] The figure shows: Bed 1; Head frame 2; Tailstock 3; External fixture 4; Bracket 5; Internal support tooling 6; External welding machine head 7; Retract the lower shoulder system 8; Welded parts 9; Toothed disc 10; Fixed seat 11; Mobile seat 12; Mandrel 13; A fixture base 14; Centering gear disc 15; Claw 16; Slip ring 17; Retract the stirring tool 18; Upper shoulder 19; Retract the stirring needle 20; Lower shoulder pad 21; Retract the pad 22; Rotating head 23; Retract axis 24; Telescopic connecting rod 25; Filling material 26; Laser ring scanning device 27; Telescopic rod 61; Outer arc plate 62; Fixed ring 63; The movable base 71 . DETAILED DESCRIPTION

[0023] The present invention is 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 are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0024] Embodiment 1: In order to solve the problem that the annular seam of a tank cannot be welded in one go, the present invention provides a gantry-penetrating double-shoulder friction stir welding device suitable for the annular seam of a tank bottom and the annular seam of a tank overall butt joint, such as Figure 1 As shown, it includes a head frame 2, a tail frame 3, an external clamp 4, an internal support tool 6, an external welding head 7 and a retractable lower shoulder system 8. The head frame 2 and the tail frame 3 are used to clamp the welded part 9. The internal support tool 6 is arranged between the head frame 2 and the tail frame 3 and is located inside the welded part 9 to support the welded part 9. The external clamp 4 is arranged along the circumference of the welded part 9 to clamp the outside of the welded part 9. The external welding head 7 is arranged on the outside of the welded part 9 and the retractable lower shoulder system 8 is arranged inside the welded part 9. The external welding head 7 and the retractable lower shoulder system 8 jointly perform retractable penetrating double-shoulder friction stir welding on the welded part 9, which is suitable for the tank annular seam penetrating double-shoulder friction stir welding.

[0025] Specifically, Figure 2 , Figure 3 As shown, the headstock 2 and the tailstock 3 have the same composition and structure and are arranged on both sides of the welded part 9, respectively. The headstock 2 and the tailstock 3 are arranged symmetrically, and both include a toothed disc 10, a fixed seat 11, a movable seat 12 and a mandrel 13. The toothed disc 10 is on one side of the fixed seat 11, and is used to fix the faceplate, barrel section tooling, etc.; the movable seat 12 is located below the fixed seat 11, connecting the bed 1 and the fixed seat 11, and the movable seat 12 can move on the bed 1 to realize the movement of the headstock 2 and the tailstock 3. The mandrel 13 is located at the center of the fixed seat 11 and passes through the fixed seat 11, and is used to install the internal support tooling 6 and retract the lower shoulder system 8. The movable seat 12 can drive other components on the headstock 2 to move in the horizontal direction as a whole, the toothed disc 10 can rotate circumferentially, and the mandrel 13 does not rotate with the toothed disc 10, and can independently move along the axial direction of the fixed seat 11.

[0026] like Figure 2 , Figure 4 , Figure 5 As shown, the outer clamp 4 includes two symmetrically arranged clamp assemblies, each of which includes a clamp base 14, a centering gear disc 15, claws 16, and a slip ring 17. The clamp base 14 is fixed on the bed 1; the centering gear disc 15 is installed on one side of the clamp base 14; eighteen claws 16 are circumferentially distributed on the inner side surface of the centering gear disc 15, and are used to synchronously clamp the welded part 9. The joint of the welded part 9 is located in the middle of the claws 16. The outer clamp 4 is equipped with a rotation system, which can drive the outer clamp 4 to drive the welded part 9 to rotate, thereby realizing rotation in the same direction and at the same speed as the gear disc 10 of the head frame 2 and the tail frame 3.

[0027] Furthermore, the toothed disc 10 can be equipped with different tooling according to the different sizes of the welded parts 9, and the claws 16 can also be replaced, ensuring that the device can be applied to the total butt joint annular seam penetration double-shoulder friction stir welding device of various diameters. It should be noted that the outer clamp 4 is fixed to the bed 1 and does not move, and the welded part 9 is driven by the headstock 2 and the tailstock 3 to move to the middle of the outer clamp 4. During the welding process, the rotation of the welded part 9 is driven by the synchronous rotation of the toothed disc 10 and the centering toothed disc 15, and the retracting stirring tool 18 and the retracting lower shoulder system are fixed in the axial direction.

[0028] like Figure 1 , Figure 6 As shown, the inner support tooling 6 is a detachable manual inner support, which is fixed on the core shaft 13 of the head frame 2 and the tail frame 3, and is mainly composed of a telescopic rod 61, an outer circle arc plate 62 and a fixed ring 63. The inner ends of multiple telescopic rods 61 are connected to the fixed ring 63 and are arranged along the circumference of the fixed ring 63. The outer end of each telescopic rod 61 is connected to an outer circle arc plate 62. All outer circle arc plates 62 form an annular structure. The diameter of the annular structure when supporting a circle is the same as the inner diameter of the part 9 to be welded, which plays a role of supporting a circle. During the welding process, it will rotate with the rotation of the part 9 to be welded.

[0029] Furthermore, an internal support tooling 6 is respectively installed on the core shaft 13 of the head frame 2 and the tail frame 3, and the internal support tooling 6 is located 100 mm on both sides of the weld, and is not used as a welding leak plate, but only plays the role of supporting the circle. The back support of the weld is ensured by the retracted lower shaft shoulder system 8.

[0030] like Figure 4 , Figure 5 As shown, the external welding head 7 is installed outside the external clamp 4, and a movable base 71 is provided below, so that the external welding head 7 can move in the X and Y directions to realize the centering of the stirring needle. The external welding head 7 is equipped with a retractable system, which can realize the retraction of the stirring needle at the end of welding.

[0031] like Figure 1 , Figure 8 As shown, the retraction system 8 for the lower shoulder includes a lower shoulder pad 21, a retraction pad 22, a rotating head 23, a retraction shaft 24, and a telescopic connecting rod 25. The lower shoulder pad 21 is detachably fixed on the rotating head 23, and supports and generates heat on the inner side of the welded part 9 during the welding process. The rotating head 23 is equipped with an independent control system, which can drive the lower shoulder pad 21 to rotate, and does not interfere with the control of the external welding head 7. The retraction shaft 24 is installed in the telescopic connecting rod 25. The retraction pad 22 is fixed at the end of the retraction shaft 24, is located inside the lower shoulder pad 21, and can move axially relative to the lower shoulder pad 21, and starts to retract at the end of welding; the telescopic connecting rod 25 is fixed on the core shaft 13, and the contact between the shoulder surface of the lower shoulder pad 21 and the back of the welded part 9 can be controlled by adjusting the telescopic amount.

[0032] The present invention can realize a double-shoulder friction stir welding device for annular seam penetration of a welded part 9, and cooperates with the retractable technology of the retractable stirring needle 20 and the retractable pad 22 to finally obtain a complete annular seam without a keyhole and a back protrusion.

[0033] Specifically, the retraction stirring tool 18 includes an upper shoulder 19 and a retraction stirring needle 20. The shoulder surface of the upper shoulder 19 is an inner concave surface. The retraction stirring needle 20 is fixed on the external welding head 7 equipped with a retraction system. The length of the retraction stirring needle 20 is 1 to 3 mm larger than the thickness of the welded part 9. The retraction stirring needle 20 has a bidirectional thread and three sections. Among them, the stirring needle that has not penetrated the welded part 9 is a left-handed thread, and the stirring needle that penetrates the welded part 9 and is located in the hole of the lower shoulder pad 21 is a right-handed thread.

[0034] like Figure 7 , Figure 8As shown, the lower shoulder pad 21 is a cylindrical structure, and the diameter of the shoulder surface can be the same as or different from the diameter of the upper shoulder 19. A through hole is opened in the center of the shoulder of the lower shoulder pad 21. The retraction pad 22 is also a cylindrical structure, and the diameter of the retraction pad 22 is the same as the diameter of the through hole of the lower shoulder pad 21, both of which are 4 mm larger than the root diameter of the retraction stirring needle 20. The clearance between the two ensures that the retraction pad 22 can freely expand and contract in the through hole of the lower shoulder pad 21. The retraction pad 22 is placed in the through hole of the lower shoulder pad 21 to form a hole at the top of the through hole, and the hole can be used to place filling material 26. The depth of the hole on the lower shoulder pad 21 is 1.5 mm larger than the difference between the thickness of the welded part 9 and the length of the retraction stirring needle 20. It should be noted that the filling material 26 is made of the same material as the welded part 9 and is a cylindrical block whose diameter is 0.1 to 1 mm smaller than the diameter of the retraction pad 22 and whose thickness is 0.1 to 0.5 mm smaller than the depth of the hole of the lower shoulder pad 21. It is placed in the hole on the lower shoulder pad 21 during welding.

[0035] Specifically, the welding device in the present invention has two retraction systems, and can control the retraction of the retraction stirring needle 20 and the retraction pad 22 at the same retraction speed. At the same time, the welding device also has two heads, which respectively control the rotation of the retraction stirring tool 18 and the lower shoulder pad 21, and their rotation speeds and rotation directions can be the same or different, depending on different situations. When the rotating head 23 does not rotate, the lower shoulder pad 21 can be used as a static lower shoulder pad; when the upper end surface of the retraction pad 22 and the shoulder surface of the lower shoulder pad 21 are in the same horizontal plane, the lower shoulder pad 21 can be used as a flat pad, and this position is the limit position of the retraction pad 22 upward retraction; when the stirring needle of the retraction stirring tool 18 is not retracted, it can be used as a common stirring tool, and when the stirring needle is fully retracted, it can be used as a needle-free stirring tool, and the length of the stirring needle can be adjusted to weld parts 9 of different thicknesses.

[0036] It should be noted that when the device is welding, the welded part 9 is driven to rotate by the head frame 2, tail frame 3 and external clamp 4, and the retraction stirring tool 18 and the retraction lower shoulder system 8 are fixed; the rotation speed and rotation direction of the external welding head 7 and the rotating head 23 can be the same or different; the retraction stirring needle 20 and the retraction pad 22 are both retracted upward after welding, and the retraction speed of the two must be consistent throughout the process. At the same time, the external welding head 7 is equipped with a laser ring scanning device 27, and a laser ring scanning friction stir welding process detection system is adopted. The laser ranging sensor rotates around the retraction stirring tool 18, 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. The parameter extraction algorithm such as the inclination angle of the retraction stirring tool 18, the shoulder pressure and the weld deviation during the online detection of welding is designed.

[0037] Furthermore, the laser circular scanning device 27 equipped on the external welding head 7 adopts a multi-parameter detection system of weld posture with end motion detection to realize the synchronous detection of multiple parameters such as weld deviation, pressing amount, posture, etc., restore the three-dimensional morphology of the surface of the welded part 9 near the retraction stirring tool 18, and adopt an adaptive PID controller based on reinforcement learning to realize adaptive tracking control of the welding process.

[0038] Furthermore, the external welding head 7 is equipped with a laser circular scanning device 27, which adopts a pressure detection elastomer and a strain gauge bridge to convert the strain signal into an electrical signal, and establish a theoretical connection between the signal and the upsetting force, so as to detect and analyze the upsetting force information of the welding process and perform constant pressure adaptive control.

[0039] The present invention also provides a penetrating double-shoulder friction stir welding method suitable for annular seams of tanks, which uses a penetrating double-shoulder friction stir welding device and comprises the following steps: Step 1: Preparation stage: fix the telescopic connecting rod 25 of the retracting lower shoulder system 8 in the core shaft 13 of the head frame 2, install the lower shoulder pad 21 on the rotating head 23, install the retracting pad 22 on the retracting shaft 24, manually start the retracting system, adjust the upper end surface of the retracting pad 22 to be flush with the shoulder surface of the lower shoulder pad 21 (that is, the hole depth is 0 mm), assemble the positioning welding stirring tool (needle length is 3 mm) on the external welding head 7, adjust the length of the telescopic connecting rod 25, ensure that the center of the stirring needle of the positioning welding stirring tool is on the same straight line as the center of the retracting pad 22, constrain the movement of the telescopic connecting rod 25 in the X direction, so that it and the external welding head 7 can only move in the Y direction, that is, the installation of the retracting lower shoulder system 8 is completed; Step 2: Assembly stage: Install the tooling corresponding to the part 9 to be welded on the toothed disc 10 of the head frame 2 and the tail frame 3, loosen the clamping air path of the tooling, cooperate with the crane and the bracket 5 to lift the part 9 to be welded onto the tooling, move the bracket 5 to the welding end area, and then install the inner support tooling 6 on the two core shafts 13. It is required that the inner support tooling 6 is located 100mm from the butt joint, and the outer arc plate 62 is in contact with the part 9 to be welded. Adjust the tightening device of the inner support tooling 6, select the corresponding claw 16 to be installed on the centering toothed disc 15, start the moving seat 12 and the bracket 5 to move the part 9 to be welded into the outer fixture 4, and require that the butt joint is located between the positioning welding stirring tool and the retraction pad 22, and ensure that there is no gap or misalignment at the butt joint. After alignment, start the clamping device, use the claw 16 to clamp the part 9 to be welded in a full circle, adjust the length of the telescopic connecting rod 25 in the Y direction, so that the shoulder surface of the lower shoulder pad 21 is close to the inner surface of the part 9 to be welded, and the assembly is completed.

[0040] Step 3: Positioning stage: first, after the welded part 9 is positioned by fusion welding, the retraction stirring tool 18 is moved and the retraction stirring needle 20 is aligned with the weld joint, the selected positioning welding process parameters are input into the control system, and the inclination angle of the positioning welding stirring tool is adjusted, and the external welding head 7 is started for positioning welding. During positioning welding, the rotating head 23 is not started, the retraction lower shoulder system 8 is stationary, and the upper end surface of the retraction pad 22 is still flush with the shoulder surface of the lower shoulder pad 21. The welding method is that the welded part 9 rotates with the equipment, and the positioning welding stirring tool and the retraction lower shoulder system 8 are fixed; Step 4: Welding stage: remove the positioning welding stirring tool and replace it with the retraction stirring tool 18. According to the thickness of the part 9 to be welded, determine the extension length of the retraction stirring needle 20 (i.e., the needle length). The needle length is usually 1 to 3 mm larger than the thickness of the part 9 to be welded. According to the length of the retraction stirring needle 20, adjust the retraction amount of the retraction pad 22 (i.e., the hole depth). The hole depth is usually set to be 1.5 mm larger than the difference between the length of the retraction stirring needle 20 and the thickness of the part 9 to be welded. Select a filling material 26 of appropriate size. The filling material 26 usually uses a filling material 26 with a diameter 0.1 to 1 mm smaller than the hole diameter and a thickness 0.1 to 0.5 mm smaller than the hole depth. Place it in the hole of the lower shoulder pad 21, change the welding process parameters in the control system of the equipment, enter the process parameters (speed, direction) in the control system of the rotating head 23, and then align again, and start the two system programs at the same time for formal welding. The welding method is that the part 9 to be welded rotates with the equipment, and the retraction stirring tool 18 and the retraction lower shoulder system 8 are fixed.

[0041] Step 5: Retraction stage: When the welding program is finished, the system automatically starts the retraction program. At this time, the retraction stirring needle 20 and the retraction pad 22 are retracted at the same retraction speed. When the retraction pad 22 is retracted until the upper end surface is flush with the shoulder surface of the lower shoulder pad 21, it reaches the limit position. At this time, it stops retracting, but the lower shoulder pad 21 is still rotating. At this time, the root of the retraction stirring needle 20 is just located at the bottom end of the welded part 9, and then the retraction stirring needle 20 continues to retract upward until it is flush with the shoulder surface of the upper shoulder 19. At this time, the welding is completed, and the upper shoulder 19 and the lower shoulder pad 21 stop rotating at the same time to obtain a complete weld.

[0042] Specifically, the inclination angle of the retraction stirring tool 18 mounted on the external welding head 7 is preferably 2.5°. During the welding process, the equipment does not move, the welded part 9, the head frame 2, the tail frame 3 and the external clamp 4 rotate, the retraction stirring needle 20 penetrates the welded part 9 and pierces into the hole of the lower shoulder pad 21, and the shoulder surface of the lower shoulder pad 21 just contacts the back of the welded part 9 (no pressing amount), the shoulder diameter, rotation direction and rotation speed of the retraction stirring tool 18 and the lower shoulder pad 21 are not fixed, but both must start to rotate at the same time.

[0043] Furthermore, the retraction stirring tool 18 and the retraction lower shoulder system 8 are always kept on the same axis during welding, and the retraction speed of the retraction stirring needle 20 and the retraction pad 22 are consistent with the start of retraction.

[0044] The present invention can realize a penetrating double-shoulder friction stir welding device for the annular seam of a storage tank, can be applied to the annular seam of a tank bottom and the annular seam of a storage tank, and cooperates with the retraction technology of a stirring needle and a pad to eliminate the risk of defects at the root of the weld, obtain a complete annular seam without a keyhole and a back protrusion, and greatly improve the welding quality.

[0045] Embodiment 2: This embodiment is a preferred example of Embodiment 1.

[0046] In this embodiment, two 8 mm thick 2219 aluminum alloy cylinder sections are generally butt-jointed as an example to develop a tank annular seam penetrating double-shoulder friction stir welding device. The steps of the tank annular seam penetrating double-shoulder friction stir welding device are described using the above-mentioned equipment and tools. In this embodiment, the shoulder diameter, rotation direction, and rotation speed of the lower shoulder pad 21 are the same as those of the retraction stirring tool 18.

[0047] In this embodiment, the tooling assembled on the toothed disc 10 is suitable for a barrel section with a diameter of 3350 mm. The welded part 9 is two barrel sections with dimensions of 3350 mm (diameter) × 1945 mm (height) × 8 mm (thickness). The upper shoulder 19 has a shoulder diameter of 27 mm; the retraction stirring needle 20 is a conical stirring needle with three sections and bidirectional threads, and the needle length is 10 mm, of which the upper 8 mm of the stirring needle is a left-handed thread, the lower 2 mm is a right-handed thread, and the root diameter of the stirring needle is 7 mm; the lower shoulder pad 21 is a cylindrical structure with a through hole in the center, and its diameter is the same as that of the upper shoulder 19, which is 27 mm in diameter and 11 mm in diameter. The retraction pad 22 is a cylindrical structure with a diameter of 11 mm, which is matched with the through hole clearance of the lower shoulder pad 21, and the length of the retraction pad 22 is 30 mm; the filling material 26 is a cylindrical structure with a diameter of 10 mm and a thickness of 3 mm.

[0048] The upper shoulder 19 and the retraction stirring needle 20 are combined into the retraction stirring tool 18, which is assembled on the external welding head 7; the lower shoulder pad 21 is fixed on the rotating head 23, and the retraction pad 22 is fixed on the retraction shaft 24, and the two together constitute the retraction lower shoulder pad 21; the filling material 26 is placed in the hole of the lower shoulder pad 21.

[0049] The working principle of the tank annular seam penetration double-shoulder friction stir welding device of the present invention is as follows: 1. Preparation stage: fix the telescopic connecting rod 25 of the retracting lower shoulder system 8 in the core shaft 13 of the head frame 2, install the lower shoulder pad 21 on the rotating head 23, install the retracting pad 22 on the retracting shaft 24, manually start the retracting system, adjust the upper end surface of the retracting pad 22 to be flush with the shoulder surface of the lower shoulder pad 21 (that is, the hole depth is 0mm), assemble the positioning welding stirring tool (needle length is 3mm) on the external welding head 7, adjust the length of the telescopic connecting rod 25, ensure that the center of the stirring needle of the positioning welding stirring tool is on the same horizontal line with the center of the retracting pad 22, constrain the movement of the telescopic connecting rod 25 in the X direction, so that it and the external welding head 7 can only move in the Y direction, and the installation of the retracting lower shoulder system 8 is completed.

[0050] 2. Assembly stage: Select 3350 barrel section tooling and install it on the toothed disc 10 of the head frame 2 and the tail frame 3, loosen the clamping air path of the tooling, cooperate with the crane and the bracket 5 to lift the barrel section onto the tooling, move the bracket 5 to the welding end area, then install the inner support tooling 6 suitable for the 3350 barrel section on the two mandrels 13, it is required that the inner support tooling 6 is located 100mm from the weld joint, and the arc plate is in contact with the barrel section, adjust the tightening device of the inner support tooling 6, select the claw 16 suitable for the 3350 barrel section and install it on the centering toothed disc 15, start the moving seat 12 and the bracket 5 to move the barrel section to the outer fixture 4, it is required that the joint is located between the positioning welding stirring tool and the withdrawal pad 22, and ensure that there is no gap or misalignment at the joint, start the clamping device after alignment, use the claw 16 to clamp the barrel section in a full circle, adjust the length of the telescopic connecting rod 25 in the Y direction, so that the shoulder surface is close to the inner surface of the barrel section, and the assembly is completed.

[0051] 3. Positioning stage: After the barrel section is positioned in sections for fusion welding, move the retraction stirring tool 18 and align the retraction stirring needle 20 with the weld joint, input the selected positioning welding process parameters into the control system (rotation speed is 400r / min, welding speed is 150 mm / min, clockwise rotation, and the pressing amount is 0.1 mm~0.2 mm), and adjust the inclination angle of the positioning welding stirring tool (the inclination angle is 2.9°), start the external welding head 7 for positioning welding, first divide it into 7 sections for positioning, and the length of each section is 10° of the circumference. During positioning welding, the rotating head 23 is not started, the retraction lower shoulder system 8 is stationary, and the upper end surface of the retraction pad 22 is still flush with the shoulder surface of the lower shoulder pad 21. The welding method is that the barrel section rotates with the equipment, and the positioning welding stirring tool and the retraction lower shoulder system 8 are fixed.

[0052] 4. Welding stage: remove the positioning welding stirring tool and replace it with the retraction stirring tool 18, adjust the extension length of the retraction stirring needle 20 to 10 mm, adjust the retraction amount of the retraction pad 22 to 3.5 mm (hole depth), select the filling material 26 of 2219 aluminum alloy with a size of 10 mm (diameter) × 3 mm (thickness), and place it in the hole of the lower shoulder pad 21, change the welding process parameters in the control system of the equipment (rotation speed is 700r / min, welding speed is 200 mm / min, clockwise rotation, pressing amount is 0.1 mm~0.2 mm, inclination angle is 2.9°, welding length is 365° in circumference), enter the process parameters (rotation speed is 700r / min, clockwise rotation) in the control system of the rotating head 23, and then align again, and start the two system programs at the same time for formal welding. The welding method is that the barrel section rotates with the equipment, and the retraction stirring tool 18 and the retraction lower shoulder system 8 are fixed.

[0053] 5. Retraction stage: When the welding program is finished, the system automatically starts the retraction program (the retraction welding length is 5° in circumference, and the retraction speed is 2mm / min). At this time, the retraction stirring needle 20 and the retraction pad 22 are retracted at the same retraction speed. When the retraction pad 22 is retracted until the upper end surface is flush with the shoulder surface of the lower shoulder pad 21, it reaches the limit position. At this time, it stops retracting, but the lower shoulder pad 21 is still rotating. At this time, the root of the retraction stirring needle 20 is just located at the bottom end of the barrel section, and then the retraction stirring needle 20 continues to retract upward until it is flush with the shoulder surface of the upper shoulder 19. At this time, the welding is completed, and the upper shoulder 19 and the lower shoulder pad 21 stop rotating at the same time to obtain a complete weld.

[0054] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0055] The above describes the specific embodiments of the present invention. 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 does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A penetrating double-shoulder friction stir welding device, characterized in that: It includes a head frame (2), a tail frame (3), an external clamp (4), an internal support tool (6), an external welding machine head (7) and a retracting lower shaft shoulder system (8); The headstock (2) and tailstock (3) are arranged on the bed (1) and are respectively disposed on both sides of the welded part (9), and are used to clamp the welded part (9); the inner support tool (6) is arranged between the headstock (2) and the tailstock (3), and is used to support the welded part (9) from the inside of the welded part (9); the outer clamp (4) is arranged along the circumference of the welded part (9) and is used to clamp the welded part (9); The external welding head (7) is arranged outside the welded part (9) and the retracting lower shoulder system (8) is arranged inside the welded part (9), so that the external welding head (7) and the retracting lower shoulder system (8) jointly perform circumferential seam penetration double shoulder friction stir welding on the welded part (9).

2. The penetrating double-shoulder friction stir welding device according to claim 1, characterized in that: The headstock (2) and tailstock (3) have the same structure, and both include a toothed disc (10), a fixed seat (11), a movable seat (12), and a core shaft (13); The toothed disc (10) is rotatably arranged on one side of the fixed seat (11); the movable seat (12) is arranged below the fixed seat (11) and is movable on the bed (1) to achieve movement of the headstock (2) and / or the tailstock (3); the mandrel (13) is arranged at the center of the fixed seat (11) and passes through the fixed seat (11) and is used to install an internal support tooling (6) and a retracting lower shoulder system (8); wherein the toothed disc (10) is capable of rotating around the fixed seat (11), the mandrel (13) does not rotate with the toothed disc (10), and is capable of independently moving along the axial direction of the fixed seat (11).

3. The penetrating double-shoulder friction stir welding device according to claim 1, characterized in that: The outer clamp (4) comprises two symmetrically arranged clamp assemblies, each of which comprises a clamp base (14), a centering toothed disc (15), a clamping claw (16) and a slip ring (17); The fixture base (14) is arranged on the bed (1); the centering toothed disc (15) is installed on one side of the fixture base (14); a plurality of clamping claws (16) are circumferentially distributed on the inner side surface of the centering toothed disc (15) and are used to synchronously clamp the welded part (9).

4. The penetrating double-shoulder friction stir welding device according to claim 3 is characterized in that: The outer clamp (4) is equipped with a rotation system, which can drive the outer clamp (4) to drive the welded part (9) to rotate.

5. The penetrating double-shoulder friction stir welding device according to claim 2, characterized in that: The inner support fixture (6) is detachably arranged on the core shaft (13), and comprises a telescopic rod (61), an outer arc plate (62) and a fixing ring (63). The inner ends of a plurality of the telescopic rods (61) are connected to the fixing ring (63) and are arranged along the circumference of the fixing ring (63). The outer end of each telescopic rod (61) is connected to one of the outer arc plates (62). All the outer arc plates (62) form an annular structure. The diameter of the annular structure when it is supported is the same as the inner diameter of the welded part (9).

6. The penetrating double-shoulder friction stir welding device according to claim 1, characterized in that: The external welding head (7) is arranged outside the external clamp (4) and is provided with a movable base (71) below, so that the external welding head (7) can move horizontally and / or vertically to achieve the centering of the retracted stirring needle (20) on the external welding head (7); The external welding machine head (7) is equipped with a retractable system so that the stirring needle (20) can be retracted when welding is completed.

7. The penetrating double-shoulder friction stir welding device according to claim 2, characterized in that: The retracting lower shaft shoulder system (8) comprises a lower shaft shoulder pad (21), a retracting pad (22), a rotating machine head (23), a retracting shaft (24) and a telescopic connecting rod (25); One end of the telescopic connecting rod (25) is fixed on the core shaft (13), and the lower shoulder pad (21) is arranged at the other end of the telescopic connecting rod (25) through the rotating machine head (23). By adjusting the telescopic amount of the telescopic connecting rod (25), the contact between the shoulder surface of the lower shoulder pad (21) and the inner surface of the welded part (9) can be controlled; a through hole is arranged inside the lower shoulder pad (21); the retraction shaft (24) is arranged inside the telescopic connecting rod (25) and the retraction pad (22) is arranged at the end thereof; the retraction pad (22) is located inside the through hole and can be retracted under the drive of the retraction shaft (24); A portion of the through hole located above the retraction pad (22) forms a hole, and the hole is used to place a filling material (26).

8. The penetrating double-shoulder friction stir welding device according to claim 7, characterized in that: The rotating machine head (23) is equipped with an independent control system and is capable of driving the lower shoulder pad (21) to rotate.

9. A penetrating double-shoulder friction stir welding method, characterized in that: The following steps are involved: Step 1: Preparation stage: fix the telescopic connecting rod (25) of the retracting lower shoulder system (8) in the core shaft (13) of the head frame (2), install the lower shoulder pad (21) on the rotating head (23), install the retracting pad (22) on the retracting shaft (24), manually start the retracting system, adjust the upper end surface of the retracting pad (22) to be flush with the shoulder surface of the lower shoulder pad (21), assemble the positioning welding stirring tool on the external welding head (7), adjust the length of the telescopic connecting rod (25), ensure that the center of the stirring needle of the positioning welding stirring tool and the center of the retracting pad (22) are on the same straight line, constrain the telescopic connecting rod (25) so as not to move in the axial direction of the welded part (9) and allow the external welding head (7) to move in the radial direction of the welded part (9); Step 2: Assembly stage: Install the tooling corresponding to the welded part (9) on the toothed discs (10) of the head frame (2) and the tail frame (3), assemble the welded part (9) onto the tooling, move the bracket (5) to the welding end area, and install the inner support tooling (6) on the two mandrels (13) so that the outer arc plate (62) contacts the welded part (9), adjust the inner support tooling (6) to hold the welded part (9) tightly and select the corresponding claws (16) to install on the centering toothed disc (15), and start The movable seat (12) and the bracket (5) move the welded parts (9) into the outer fixture (4) so ​​that the butt joint of the two welded parts (9) is located between the positioning welding stirring tool and the retraction pad (22), and it is ensured that there is no gap or misalignment at the butt joint. After alignment, the welded parts (9) are pressed tightly with the claws (16) in a full circle, and the length of the telescopic connecting rod (25) is adjusted in the axial direction of the welded parts (9) so that the shoulder surface of the lower shoulder pad (21) is closely attached to the inner surface of the welded parts (9), and the assembly is completed. Step 3: Positioning stage: first, the welded part (9) is positioned in sections for fusion welding, then the retraction stirring tool (18) is moved and the retraction stirring needle (20) is aligned with the weld joint, the selected positioning welding process parameters are input into the control system, and the inclination angle of the positioning welding stirring tool is adjusted, and the external welding head (7) is started for positioning welding. During positioning welding, the rotating head (23) is not started, the retraction lower shoulder system (8) is stationary, and the upper end surface of the retraction pad (22) is still flush with the shoulder surface of the lower shoulder pad (21). The welding method is that the welded part (9) rotates with the equipment, and the positioning welding stirring tool and the retraction lower shoulder system (8) are fixed; Step 4: Welding stage: remove the positioning welding stirring tool and replace it with the retraction stirring tool (18). According to the thickness of the welded part (9), determine the extension length of the retraction stirring needle (20). According to the length of the retraction stirring needle (20), adjust the retraction amount of the retraction pad (22), and the retraction amount is recorded as the hole depth. Place the filling material (26) in the hole of the lower shoulder pad (21), change the welding process parameters in the control system of the equipment, input the process parameters in the control system of the rotating machine head (23), and then align again. At the same time, start the two system programs for formal welding. The welding method is that the welded part (9) rotates with the equipment, and the retraction stirring tool (18) and the retraction lower shoulder system (8) are fixed; Step 5: Retraction phase: When the welding procedure is finished, the system automatically starts the retraction procedure. At this time, the retraction stirring needle (20) and the retraction pad (22) are retracted at the same retraction speed. When the retraction pad (22) is retracted until the upper end surface is flush with the shoulder surface of the lower shoulder pad (21), it reaches the limit position and stops retraction. However, the lower shoulder pad (21) is still rotating. At this time, the root of the retraction stirring needle (20) is just located at the bottom of the welded part (9). Then the retraction stirring needle (20) continues to be retracted upward until it is flush with the shoulder surface of the upper shoulder (19). At this time, the welding is finished, and the upper shoulder (19) and the lower shoulder pad (21) stop rotating at the same time to obtain a complete weld.

10. The penetrating double-shoulder friction stir welding method according to claim 9, characterized in that: In step 4, the extended length of the retracted stirring needle (20) is the needle length, which is 1 to 3 mm greater than the thickness of the welded part (9). The retracted amount of the retracted pad (22) is the hole depth, which is 1.5 mm greater than the difference between the length of the retracted stirring needle (20) and the thickness of the welded part (9). The diameter of the filling material (26) is 0.1 to 1 mm smaller than the hole diameter, and the thickness is 0.1 to 0.5 mm smaller than the hole depth.

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