A dual-shouldered friction stir welding tool and method of use thereof

Abstract

The present application relates to the technical field of friction stir welding, and discloses a double-shoulder friction stir welding tool and a use method thereof, which comprises an upper clamping body arranged at an upper portion, an upper shaft shoulder arranged at a middle portion, an outer sleeve sleeved outside the upper clamping body and the upper shaft shoulder, a stirring needle, and a lower shaft shoulder arranged at a lower portion; the upper clamping body, the upper shaft shoulder, the stirring needle, and the lower shaft shoulder are coaxially arranged; the shaft centers of the upper clamping body, the upper shaft shoulder, and the stirring needle are respectively provided with an upper clamping body core passage, an upper shaft shoulder core hole passage, and a stirring needle core passage; and a spiral turbulence support is further arranged in the stirring needle core passage. The present application can guide the cooling medium into the core working area of the stirring needle, reduce the working temperature of the stirring needle and the stirring tool during the welding process, and has the advantages of refining the weld grain and prolonging the service life of the stirring tool.

Description

Technical Field

[0001] This invention belongs to the field of friction stir welding technology, and relates to a dual-shoulder friction stir welding tool and its usage method, specifically a core-cooled dual-shoulder friction stir welding tool and its usage method. Background Technology

[0002] Compared to conventional friction stir welding (FSW), dual-shoulder friction stir welding (BTFSW) addresses the issue of weak connections on the back of the weld seam through its simultaneous double-sided welding process, thereby improving joint strength. BTFSW utilizes the lower shoulder to support the workpiece under the weld during the welding process, eliminating the need for rigid supports at the bottom of the workpiece. This significantly simplifies welding fixtures, reduces welding costs, and enhances the process flexibility of friction stir welding.

[0003] The double-shoulder structure of the BTFSW results in a higher heat input during welding compared to the FSW. This high temperature leads to coarsening of the weld grains, thus reducing the weld's mechanical properties. Simultaneously, the BTFSW stirring pin must withstand the enormous torque generated by the friction between the lower shoulder and the plate material. This high heat input significantly reduces the stirring pin's lifespan and increases the risk of breakage. Chinese invention patent (application number 201710098353.3) proposes a water-cooling device and method for a double-shoulder friction stir head. This method uses cooling water to cool the non-welding parts of the upper and lower shoulders of the double-shoulder friction stir head, achieving a cooling function for both the friction stir head and the friction stir welding machine head. However, this method has limited cooling effect on the stirring pin located in the high-temperature zone of the weld nugget, still posing risks of high-temperature stirring pin breakage and coarse grains at the joint. Furthermore, the centrifugal drainage component increases the complexity of the device and the workload of pre-welding installation and debugging. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a dual-shoulder friction stir welding tool and its usage method, which can introduce cooling medium into the core working area of ​​the stirring pin, reduce the working temperature of the stirring pin and the stirring tool during the welding process, and improve the service life of the stirring tool.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention proposes a core-cooled dual-shoulder stirring tool, comprising an upper clamping body disposed at the upper part, an upper shoulder disposed at the middle part, an outer sleeve fitted outside the upper clamping body and the upper shoulder, a stirring needle, and a lower shoulder disposed at the lower part; the upper clamping body, the upper shoulder, the stirring needle, and the lower shoulder are all coaxially arranged, and the core of the upper clamping body, the upper shoulder, and the stirring needle are respectively provided with a core channel of the upper clamping body, a core hole channel of the upper shoulder, and a core channel of the stirring needle.

[0007] In conjunction with the first aspect, furthermore, a turbulence-inducing support is provided within the core channel of the stirring needle. This turbulence-inducing support has a ribbon-type helical blade structure, with its blades contacting the inner wall of the core channel. The outer diameter of the blades of the turbulence-inducing support is equal to the diameter of the core channel. The ribbon-type helical blade structure of the turbulence-inducing support significantly increases the heat exchange area of ​​the cooling medium and disturbs the flow field of the cooling medium, thereby improving the heat exchange efficiency of the stirring needle. Furthermore, by providing the turbulence-inducing helical support, not only can the cooling effect on the stirring needle be improved, but the rigidity of the stirring needle is also further enhanced, increasing its durability.

[0008] In conjunction with the first aspect, further, when the stirring needle core channel is not provided with a turbulence support, the stirring needle core channel is one of a polygonal through hole, a petal-shaped through hole, and a topological curved surface porous structure.

[0009] In conjunction with the first aspect, further, the outer wall surface of the stirring needle is provided with, from top to bottom, a stirring needle positioning cylindrical surface, a stirring needle first direction external thread, a stirring needle working area, and a stirring needle second direction external thread; wherein the first direction and the second direction are opposite directions, one is left-handed and the other is right-handed, one is right-handed and the other is left-handed; the upper shoulder is provided with, from top to bottom, a stirring needle positioning hole and an upper shoulder first direction internal thread hole along the upper shoulder core hole channel; the stirring needle positioning hole and the stirring needle positioning cylindrical surface are provided for shaft hole positioning matching, and the upper shoulder first direction internal thread hole and the stirring needle first direction external thread are provided for thread matching, so that the stirring needle is coaxially fixed inside the upper shoulder; the lower shoulder has a through lower shoulder second direction internal thread hole on its axis, and the lower shoulder second direction internal thread hole and the stirring needle second direction external thread are provided for thread matching.

[0010] When the spindle of the friction stir welding machine rotates counterclockwise, the first thread of the stirring pin is a left-hand thread, which allows the welding to become tighter as it rotates. The second thread at the bottom of the stirring pin is a right-hand thread. The lower shoulder tends to loosen during welding, but the locking thread prevents it from loosening. This design prevents the stirring pin from loosening and improves the stability of the height difference between the upper and lower shoulders during the welding process.

[0011] In conjunction with the first aspect, the stirring tool of the present invention further includes a locking nut, which is disposed at the lower part of the lower shoulder. The locking nut can fix the lower shoulder at a set height, thereby adjusting the pressing amount of the double shoulders.

[0012] In conjunction with the first aspect, the stirring needle working area further includes a second upward-spinning stirring thread disposed on the upper part of its main body, a first downward-spinning stirring thread disposed on its lower part, and stirring needle cross-sections evenly distributed in the stirring needle working area. Preferably, there are three stirring needle cross-sections.

[0013] When the spindle of the friction stir welding machine rotates counterclockwise, the right-hand thread on the upper part causes the material on the top surface to move downwards, while the left-hand thread on the lower part causes the material on the bottom surface to move upwards. This helps to form a dense weld. The stirring pin has three facets, evenly distributed at 120 degrees, making it approximately hexagonal. This is more conducive to the plastic mixing of materials compared to triangular or quadrilateral shapes.

[0014] In conjunction with the first aspect, the upper shoulder further includes a first fixing surface and a second fixing surface. The first fixing surface is disposed on the outer circumferential surface of the upper part of the upper shoulder, and the upper shoulder is installed on the lower part of the upper clamping body through a surface fit between the first fixing surface and the lower part of the upper clamping body. The second fixing surface is disposed on the outer circumferential surface of the lower part of the upper shoulder. The upper shoulder is fixed in the Z-direction to the outer sleeve through the second fixing surface. An outer sleeve fixing screw is provided on the outer sleeve, and a second fixing surface of the upper clamping body is provided on the outer circumferential surface of the middle part of the upper clamping body. The outer sleeve is fixed to the lower part of the upper clamping body through a surface fit between the outer sleeve fixing screw and the second fixing surface of the upper clamping body.

[0015] In conjunction with the first aspect, the upper clamping body further includes an upper clamping body head, which is connected to the adapter handle of the friction stir welding machine. The adapter handle has a core channel extending through its shaft. The upper clamping body head, the upper clamping body core channel, the upper shaft shoulder core hole channel, and the stirring needle core channel are connected through the shaft to form a cooling channel.

[0016] Secondly, the present invention proposes a core-cooled friction stir welding machine, comprising a frame, a gantry frame, an X-axis drive module, a Y-axis drive module, a Z-axis drive module, an adapter tool holder, a stirring tool, a welding platform, and the stirring tool as described in any one of claims 1 to 9; the gantry frame is mounted on the base of the frame; the Y-axis drive module is mounted on the crossbeam of the gantry frame; the Z-axis drive module is connected to the Y-axis drive module, its lower output end is connected to the adapter tool holder, the lower part of the adapter tool holder is connected to the stirring tool, and the Z-axis drive module drives the stirring tool to perform Z-axis movement and Z-axis rotation through the adapter tool holder; the X-axis drive module is mounted on the frame, the welding platform is mounted on the X-axis drive module, and the X-axis drive module drives the welding platform to perform X-axis movement; the welding platform is provided with a through-hole for the lower shoulder and the stirring needle to pass through.

[0017] Thirdly, the present invention provides a method for using a dual-shoulder friction stir welding tool, comprising the following steps:

[0018] S1: After grinding and cleaning the workpiece to be welded, clamp it onto the welding platform, and make sure that the mating surface of the workpiece to be welded coincides with the symmetrical plane of the through hole set on the welding platform.

[0019] S2: Drive the dual-shoulder friction stir welding tool so that the upper shoulder end face is at the same height as the starting surface of the workpiece to be welded, and record the position of the dual-shoulder friction stir welding tool. Position the stirring pin axis on the mating surface of the workpiece to be welded, and ensure the outer wall of the stirring pin is in contact with the starting point of the weld on the workpiece. Record the position of the dual-shoulder friction stir welding tool as follows: , The starting point calibration of the dual-shoulder friction stir welding tool is completed;

[0020] S3: Set the thickness of the workpiece to be welded to... The press-in amount of the upper shoulder is The press-in amount of the lower shoulder is Spindle speed (rpm), welding speed (mm / min); Install the lower shaft shoulder and adjust its distance from the upper shaft shoulder to be... The lower shoulder is then fixed in this position by tightening the lock nut.

[0021] S4: Drive the dual-shoulder friction stir welding tool to a certain position away from the welding start position of the workpiece in the X-axis direction. Set the starting rotation position of the dual-shoulder friction stir welding tool to ( , , ),in , , ;

[0022] S5: Welding begins according to the set path, as the stirring needle rotates and enters the workpiece to be welded. After a certain time, the flow rate will be... (L / min), temperature is (°C) cooling medium is introduced into the channel of the stirring needle core;

[0023] S6: When the stirring pin leaves the workpiece to be welded Then stop spinning in place and wait. The cooling medium supply will be stopped after a certain time.

[0024] S7: Welding work completed.

[0025] Compared with the prior art, the present invention provides a dual-shoulder stirring tool and its method of use, which has the following beneficial effects:

[0026] (1) The present invention provides a through-hole channel in the core of the stirring needle, which can directly introduce the coolant into the core stirring working area of ​​the stirring needle. It has the advantages of simple structure, convenience and reliability, and good cooling performance. In addition, the cooling of the core of the stirring needle can significantly reduce the temperature of the weld nugget area, reduce the risk of high temperature fatigue fracture of the stirring needle, and improve the service life of the stirring tool.

[0027] (2) The dual-shoulder friction stir welding tool of the present invention can reduce the peak temperature of the joint and increase the cooling rate of the weld, thus achieving the benefits of refining the weld grains and improving the mechanical properties of the joint.

[0028] (3) The present invention provides a spiral turbulence support that contacts the wall of the channel in the core channel of the stirring needle. The spiral blade structure can significantly increase the heat exchange area between the cooling medium and the stirring needle, and turbulent the flow field of the cooling medium to improve the heat exchange efficiency. Moreover, the spiral turbulence support enhances the overall rigidity of the stirring needle and improves the durability of the stirring friction tool.

[0029] (4) The dual-shoulder friction stir welding tool of the present invention adopts a combined structure. By changing the shoulder and stirring pin of different specifications, the tool can be quickly changed, reducing the cost of changing the tool. The overall service life of the stirring tool can also be increased by replacing the easily worn stirring pin. Attached Figure Description

[0030] Figure 1 A three-dimensional structural diagram of a friction stir welding machine equipped with the friction stir welding tool of the present invention;

[0031] Figure 2 This is a side view of the entire friction stir welding machine equipped with the friction stir welding tool of the present invention.

[0032] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along the middle AA;

[0033] Figure 4 for Figure 3 A magnified structural diagram of partial view A' in the middle;

[0034] Figure 5 This is a three-dimensional assembly diagram of the dual-shoulder friction stir welding tool in this invention;

[0035] Figure 6 This is a schematic front view of the dual-shoulder friction stir welding tool of the present invention;

[0036] Figure 7 for Figure 6 Schematic diagram of the cross-sectional structure along the middle BB;

[0037] Figure 8 for Figure 7 A magnified structural diagram of partial view B' in the middle;

[0038] Figure 9 This is a three-dimensional structural diagram of the spiral-type aerodynamic support in this invention;

[0039] Figure 10 for Figure 9 A schematic diagram of the cross-section of the spiral-type aerodynamic support;

[0040] Figure 11 This is a three-dimensional structural diagram of the stirring needle in this invention;

[0041] Figure 12 This is a schematic diagram of the main structure of the stirring needle in this invention;

[0042] Figure 13 for Figure 12 A magnified structural diagram of partial view C' in the middle;

[0043] Figure 14 for Figure 12 A schematic diagram of the cross-section CC of the stirring needle, in which... Figure 14 The stirring core channel in part a is a circular through hole. Figure 14 b. The stirring core channel is a porous topological surface. Figure 14 c. The stirring core channel is a polygonal through hole. Figure 14 The stirring core channel is a petal-shaped through-hole;

[0044] Figure 15 This is a schematic front view of the dual-shoulder friction stir welding tool of the present invention;

[0045] Figure 16 for Figure 15 A schematic diagram of a double-shoulder friction stir welding tool and its participation in the refrigerant circulation, viewed in DD section.

[0046] Figure 17 This is a schematic diagram illustrating the method of using the dual-shoulder friction stir welding tool in this invention, wherein... Figure 17 a to Figure 17 d represents the welding steps in sequence;

[0047] Figure 18 This is a schematic diagram of the assembled dual-shoulder friction stir welding tool of the present invention;

[0048] Figure 19 Metallographic images of traditional biaxial shoulder friction stir welding and the present invention at different welding speeds;

[0049] Figure 20 The graph shows a comparison of peak temperatures at different welding speeds between conventional biaxial shoulder friction stir welding and the present invention, with the thermocouple sampling point located on the advancing side and 13 mm away from the weld center.

[0050] Figure 21This is a schematic diagram of a tensile specimen, where a0 is the plate thickness, b0 is the specimen width, Lc is the parallel length, Lt is the total specimen length, r is the transition arc, WD represents the rolling direction (i.e., the direction of metal flow during the rolling process), TD represents the transverse direction (i.e., the direction perpendicular to the rolling direction), and ND represents the normal direction (i.e., the thickness direction of the plate).

[0051] Figure 22 The graph shows a comparison of the tensile properties of traditional biaxial shoulder friction stir welding and the present invention at different welding speeds.

[0052] The meanings of the reference numerals in the figure are as follows:

[0053] 1. Friction stir welding machine; 11. Z-axis drive module; 111. Adapter tool holder; 1111. Rotary interface; 1112. Tool holder core channel; 1113. Adapter tool holder fixing flange; 1114. Sealing gasket; 1115. Upper clamping body fixing screw hole; 12. Welding platform; 121. Workpiece to be welded; 122. Fixing fixture; 123. Through-hole; 124. Cooling medium storage tank; 1241. Storage tank outlet; 13. X-axis drive module; 14. Frame; 15. Gantry frame; 16. Y-axis drive module; 2. Stirring tool; 21. Upper clamping body; 211. Upper clamping body head; 2111. Upper clamping body first fixing surface; 212. Upper clamping body second fixing surface; 213. Upper clamping body core channel. 22. Outer sleeve; 221. Outer sleeve fixing screw; 23. Upper shaft shoulder; 231. Upper shaft shoulder core hole channel; 232. Upper shaft shoulder first fixing surface; 233. Upper shaft shoulder second fixing surface; 234. Stirring needle positioning hole; 235. Upper shaft shoulder first threaded hole; 236. Upper shaft shoulder end face; 2361. Upper cutting surface; 24. Lower shaft shoulder; 241. Lower shaft shoulder end face; 2411. Lower cutting surface; 242. Lower shaft shoulder annular groove; 243. Lower shaft shoulder second threaded hole. 25. Locking nut; 26. Stirring needle; 261. Stirring needle core channel; 262. Baffle bracket; 263. Stirring needle positioning cylindrical surface; 264. First external thread of stirring needle; 265. Working area of ​​stirring needle; 2651. Second upward thread of stirring needle; 2652. Cross-section of stirring needle; 2653. First downward thread of stirring needle; 266. Second external thread of stirring needle. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0056] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] like Figures 5 to 16 As shown, this invention proposes a core-cooled dual-shoulder stirring tool, comprising an upper clamping body 21 at the top, an upper shoulder 23 at the middle, an outer sleeve 22 fitted over the upper clamping body 21 and the upper shoulder 23, a lower shoulder 24 at the bottom, a locking nut 25 located below the lower shoulder 24, and a stirring needle 26. The upper shoulder 23 includes a first fixing surface 232 and a second fixing surface 233. The first fixing surface 232 of the upper shoulder is disposed on the outer circumferential surface of the upper part of the upper shoulder 23. The upper shoulder 23 is installed on the lower part of the upper clamping body 21 through the form-fit between the first fixing surface 232 of the upper shoulder and the cavity of the lower part of the upper clamping body 21. The second fixing surface 233 of the upper shoulder is disposed on the outer circumferential surface of the lower part of the upper shoulder 23. The upper shoulder 23 is fixed in the Z direction with the outer sleeve 22 through the second fixing surface 233 of the upper shoulder. The outer sleeve 22 is also provided with an outer sleeve fixing screw 221. The second fixing surface 212 of the upper clamping body is provided on the middle outer circumferential surface of the upper clamping body 21. The outer sleeve 22 is fixed through the form-fit between the outer sleeve fixing screw 221 and the second fixing surface 212 of the upper clamping body, thereby realizing the overall fixation of the upper clamping body 21, the outer sleeve 22, and the upper shoulder 23.

[0059] The stirring pin 26 is made of tool steel or cemented carbide, and its shaft has a through-hole channel 261. The channel 261 has a baffle bracket 262 that contacts its wall surface. Figure 9 and Figure 10 As shown, the main structure of the baffle bracket 262 is a ribbon-type helical blade, the outer diameter of which is equal to the diameter of the stirring needle core channel 261. The ribbon-type helical blade of the baffle bracket 262 is fixed to the stirring needle core channel 261 by brazing. The main body of the stirring needle 26 is rod-shaped, and its outer wall surface is provided with a stirring needle positioning cylindrical surface 263, a stirring needle first helical external thread 264, a stirring needle working area 265, and a stirring needle second helical external thread 266 from top to bottom. The stirring needle working area 265 includes a stirring second helical upward thread 2651 provided on the upper part of its main body and a stirring first helical downward thread 2653 provided on the lower part of its main body. The main body of the stirring needle working area 265 also has three evenly distributed stirring needle cross-sections 2652, the depth of which is greater than or equal to the depth of the thread root. The three evenly distributed stirring needle cross-sections 2652 are approximately hexagonal. A deeper cut is closer to a hexagon, resulting in better stirring effect, while a shallow cut results in poor stirring effect.

[0060] The upper shoulder 23 has a through-hole channel 231 on its shaft. Along the through-hole channel 231, from top to bottom, are arranged a stirring pin positioning hole 234 and a first internal threaded hole 235. The stirring pin positioning hole 234 and the first internal threaded hole 235 are respectively matched with the stirring pin positioning cylindrical surface 263 and the first external thread 264, so that the stirring pin 26 is positioned inside the upper shoulder 23 and is coaxially screwed to it. The lower shoulder 24 has a through-hole 243 on its shaft. The second internal threaded hole 243 and the second external thread 266 of the stirring pin are matched as a threaded hole and thread. The lower shoulder 24 and the locking nut 25 are fixed at a set height on the second external thread 266 of the stirring pin by a top-to-top screw connection, allowing the double-shoulder stirring tool 2 to adapt to welding workpieces 121 of different thicknesses.

[0061] In one specific implementation of this embodiment, the first direction of rotation is left-handed. For example, the first direction of rotation internal thread hole 235 on the upper shoulder is a left-handed internal thread hole on the upper shoulder, and the first direction of rotation external thread 264 on the stirring needle is a left-handed external thread on the stirring needle. Similarly, the second direction of rotation is right-handed. For example, the second direction of rotation internal thread hole 243 on the lower shoulder is a right-handed internal thread hole on the lower shoulder, and the second direction of rotation external thread 266 on the stirring needle is a right-handed external thread on the stirring needle.

[0062] like Figures 1 to 4As shown, the friction stir welding machine 1 in this embodiment includes a frame 14, a gantry frame 15, an X-axis drive module 13, a Y-axis drive module 16, a Z-axis drive module 11, an adapter tool holder 111, a stirring tool 2, a welding platform 12, and a cooling medium storage tank 124. The gantry frame 15 is mounted on the base of the frame 14; the Y-axis drive module 16 is mounted on the crossbeam of the gantry frame 15; the Z-axis drive module 11 is connected to the Y-axis drive module 16, and its lower output end is connected to the adapter tool holder 111. The lower part of the adapter tool holder 111 is connected to the stirring tool 2. The Z-axis drive module 11 can drive the double-shoulder stirring tool 2 to move and rotate along the Z-axis through the adapter tool holder 111; the X-axis drive module 13 is mounted on the frame 14, and the welding platform 12 is mounted on the X-axis drive module 13. The X-axis drive module 13 can drive the welding platform 12 to move along the X-axis through the gantry frame 15. The welding platform 12 is provided with a through-hole 123 for the lower shoulder 24 and the stirring needle 26 to pass through.

[0063] One specific implementation method in this embodiment is as follows: Figures 1 to 3 As shown, a cooling medium storage tank 124 is provided at the lower part of the welding platform 12 for recovering liquid cooling medium, and a storage tank outlet 1241 is provided to directly return the cooling medium for recycling.

[0064] The upper clamping body 21 also includes an upper clamping head 211 disposed on the upper part of its main body, and the upper clamping body 21 is connected to the adapter handle 111 through the upper clamping head 211. The lower part of the adapter handle 111 is provided with an upper clamping body mounting hole and an upper clamping body fixing screw hole 1115, for fitting and fixing the upper clamping head 211 with screws, so that the dual-shoulder stirring tool 2 is fixed on the adapter handle 111 as a whole. A through handle core channel 1112 is provided on the axis of the adapter handle 111. A rotating interface 1111 is provided on the upper part of the handle core channel 1112 for introducing a cooling medium (water, ethylene glycol, liquid nitrogen, etc.) into the dual-shoulder stirring tool 2. The tool holder core channel 1112, upper clamping body core channel 213, upper shaft shoulder 23 and stirring needle core channel 261, which are correspondingly arranged on the axis of the adapter tool holder 111, upper clamping body 21, upper shaft shoulder core hole channel 231 and stirring needle core channel 261, are connected through each other to form a cooling channel.

[0065] In one specific embodiment of this invention, the upper clamping head 211 includes an upper clamping first fixing surface 2111, which is correspondingly provided with the upper clamping fixing screw hole 1115 for fixed connection with the adapter handle 111.

[0066] In one specific embodiment of this invention, the adapter tool holder 111 further includes an adapter tool holder fixing flange 1113, which is used to fix the adapter tool holder 111 onto the Z-axis drive module.

[0067] In one specific embodiment of this invention, the adapter tool holder 111 further includes a sealing washer 1114. The sealing washer 1114 is disposed at the end of the upper clamping head 211 and is used to seal and prevent the cooling medium of the tool holder core channel 1112 from leaking to the connection between the adapter tool holder 111 and the upper clamping head 211.

[0068] One specific implementation method in this embodiment is as follows: Figure 7 and Figure 8 As shown, the upper shoulder 23 also includes an upper shoulder end face 236 disposed at the lower part, the upper shoulder end face 236 including an upper cutting surface 2361. The lower shoulder 24 also includes a lower shoulder end face 241 disposed at the upper part, the lower shoulder end face 241 including a lower cutting surface 2411 and a lower shoulder annular groove 242. Both the upper shoulder end face 236 and the lower shoulder end face 241 are concave designs and have the same diameter, preferably 20mm.

[0069] Example 2

[0070] The difference between Example 2 and Example 1 is that the turbulence support 262 is removed, and the flow field of the cooling medium is disturbed by changing the structural shape of the stirring needle core channel 261, thereby improving the heat exchange efficiency.

[0071] like Figure 14 In Figure 14 b to Figure 14 As shown in d, the cross-section of the stirring needle core channel 261 can be set as one of the following: topological curved porous structure, polygonal through hole and petal-shaped through hole, with the topological curved porous structure being preferred.

[0072] It should be noted that: Figure 14 In Figure 14 a represents the cross-sectional shape of the stirring needle in Example 1. The core channel 261 of the stirring needle is a circular through hole, and a turbulence bracket 262 is fixedly installed inside the circular through hole.

[0073] Example 3

[0074] This embodiment uses the stirring tool from Embodiment 1 for friction stir welding, such as... Figure 17 As shown, its usage includes the following steps:

[0075] S1: After grinding and cleaning the workpiece 121 to be welded, it is clamped onto the welding platform 12, and the mating surface of the workpiece 121 to be welded coincides with the symmetrical plane of the through hole 123 provided on the welding platform 12.

[0076] S2: Drive the dual-shoulder friction stir welding tool so that the upper shoulder end face 236 is at the same height as the starting surface of the workpiece 121 to be welded, and record the position of the dual-shoulder friction stir welding tool as follows. Position the stirring pin axis on the mating surface of the workpiece 121 to be welded, and ensure that the stirring pin 26 is in contact with the starting position of the workpiece 121. Record the position of the dual-shoulder friction stir welding tool as follows: , Complete the calibration of the starting point for the dual-shoulder friction stir welding tool;

[0077] S3: Set the thickness of the workpiece 121 to be welded to be... The press-in amount of the upper shoulder 23 is The press-in amount of the lower shoulder 24 is Spindle speed (rpm), welding speed (mm / min); Install the lower shaft shoulder 24 and adjust its distance from the upper shaft shoulder 23 to... The lower shoulder 24 is fixed in this position by locking nut 25;

[0078] S4: Drive the dual-shoulder friction stir welding tool to a certain position away from the workpiece to be welded in the X-axis direction, 121 away from the welding start position. Set the starting rotation position of the dual-shoulder friction stir welding tool to ( , , ),in , , S5: Welding begins according to the set path. When the stirring pin 26 rotates into the workpiece 121 to be welded... Then, the traffic will be (L / min), temperature is (°C) cooling medium is introduced into the stirring needle core channel 261;

[0079] S6: When the stirring needle 26 leaves the workpiece 121 to be welded. After a distance, stop and turn in place, wait. The cooling medium supply will be stopped after a certain time.

[0080] S7: Welding work completed.

[0081] Example 4

[0082] This embodiment uses the stirring tool from Embodiment 1 for friction stir welding, such as... Figure 18 As shown, the turbulence bracket 262 is a spiral blade structure made of T2 copper, while the upper shoulder 23, lower shoulder 24, and stirring pin 26 are made of quenched H13 tool steel. Figure 4As shown, the workpieces 121 to be welded are two 6061-T6 aluminum alloy plates that need to be butt-welded by friction stir welding, with dimensions of 300 mm long × 100 mm wide × 6 mm thick. The butt joint area of ​​the workpieces 121 is sanded and cleaned with alcohol. After pre-treatment, the workpieces 121 are clamped onto the welding platform 12 using the fixing clamp 122. Both the upper shoulder end face 236 and the lower shoulder end face 241 have a concave design with a diameter of 20 mm. This concave design helps to restrain the softened plastic material during welding, promoting material mixing and filling, reducing defects such as internal porosity and surface grooves in the weld joint, and improving the quality of the weld joint. The distance between the upper shoulder 23 and the lower shoulder 24 is adjusted to 5.8 mm using the locking nut 25.

[0083] The process steps for using a stirring tool in friction stir welding in this embodiment are as follows:

[0084] 1) Drive the Z-axis drive module 11 to make the double-shoulder stirring tool 2 pass through the welding platform 12. The axis of the stirring needle 26 is located on the mating surface of the workpiece 121 to be welded. The upper shoulder end face 236 is 0.1mm lower than the upper surface of the workpiece 121 to be welded. Setting a shoulder pressure of 0.1mm helps to improve the compactness of the weld joint structure.

[0085] 2) Start the friction stir welding machine 1. The dual-shoulder stirring tool 2 rotates counterclockwise at 600 rpm and the welding speed is 500 mm / min, and begins the welding process. As the dual-shoulder stirring tool 2 moves in the welding direction, the upper cutting surface 2361 of the upper shoulder 23 and the lower cutting surface 2411 of the lower shoulder 24 first come into contact with the workpiece 121 to be welded and rub against it. As the upper shoulder 23 and the lower shoulder 24 further rotate and cut in, the stirring needle working area 265 comes into contact with the workpiece 121 to be welded.

[0086] 3) such as Figure 16 As shown, the cooling function is activated, and a cooling medium (water at a temperature of 20°C) with a flow rate of 5L / min is introduced from the rotary interface 1111 of the adapter tool holder 111. The cooling medium passes sequentially through the tool holder core channel 1112, the upper clamping body core channel 213, the upper shaft shoulder core hole channel 231, and the stirring needle core channel 261, and finally the cooling medium falls directly into the cooling medium storage tank 124 below the welding platform 12.

[0087] 4) The dual-shoulder stirring tool 2 continues to move and weld along the set welding path;

[0088] 5) Once the predetermined welding path is completed, the dual-shoulder stirring tool 2 rotates away from the welded workpiece;

[0089] 6) The dual-shoulder stirring tool 2 stops rotating and moving, and the cooling medium supply stops after about 2 minutes;

[0090] 7) Drive the Z-axis drive module 11 to return the dual-shoulder stirring tool 2 to the origin position and complete the welding.

[0091] like Figure 19 As shown, following the above steps and adjusting the welding speed parameters to 100 mm / min and 1000 mm / min, samples with three different welding speeds were welded using the method of this invention, as shown below. Figure 19 b、 Figure 19 d and Figure 19 As shown in f, Figure 19 In b, 600rpm-100 mm / min indicates that the dual-shoulder stirring tool 2 rotates counterclockwise at 600rpm and the welding speed is 100mm / min, and then begins to move and weld. Figure 19 In d, 600rpm-500 mm / min indicates that the dual-shoulder stirring tool 2 rotates counterclockwise at 600rpm and the welding speed is 500mm / min, and then begins to move and weld. Figure 19 The dual-shoulder stirring tool 2 rotates counterclockwise at 600 rpm and the welding speed is 1000 mm / min, starting the welding process.

[0092] Furthermore, in step 3) of this embodiment, the cooling medium is turned off (i.e., the stirring pin core is not supplied with cooling water), and biaxial shoulder friction stir welded samples with the same welding parameters but without cooling water supplied to the stirring pin core are obtained, as shown below. Figure 19 a, Figure 19 c and Figure 19 As shown in e, Figure 19 In section a, 600rpm-100 mm / min-NW indicates that, without cooling water flowing through the core of the stirring needle, the dual-shoulder stirring tool 2 of this invention is used to rotate counterclockwise at 600rpm and the welding speed is 100mm / min to begin the walking welding process. Figure 19 In c, 600rpm-500 mm / min-NW indicates that when there is no cooling water in the core of the stirring needle, the dual-shoulder stirring tool 2 of this invention is used to rotate counterclockwise at 600rpm and the welding speed is 500mm / min to start the walking welding process. Figure 19 In the equation 600rpm-1000 mm / min-NW, it indicates that without cooling water flowing through the core of the stirring needle, the dual-shoulder stirring tool 2 of this invention is used to start the welding process by rotating counterclockwise at 600rpm and welding at a speed of 1000mm / min. Figure 19 Metallographic images of biaxial shoulder friction stir welding performed using the biaxial shoulder stirring tool 2 of this invention without cooling water flow to the stirring needle core, and at different welding speeds (100–1000 mm / min) of this invention, are shown below. Figure 19 b、 Figure 19 d、 Figure 19As can be seen, within this welding speed range, the joint of the present invention exhibits no porosity or tunnel defects, resulting in a good joint. And as... Figure 19 As shown in the red box in section a, the biaxial shoulder friction stir welding without cooling water exhibits numerous pores and tunnel defects at the intermediate layer position during a 100 mm / min advance measurement; for example... Figure 19 As shown in the red box in section c, when the welding speed increases to 500 mm / min, the defect on the advancing side improves into a single tunnel. This is mainly because, without cooling water, the material flow is intense and uneven under low welding speed and high heat input conditions, resulting in insufficient material filling in the triangular confluence area on the advancing side, leading to the appearance of porosity and tunnel defects. Figure 19 As shown in Figure e, with the welding speed increasing to 1000 mm / min, the material flow in the biaxial shoulder friction stir welding head region without cooling water reached equilibrium. Metallographic analysis revealed no defects such as pores or tunnels, indicating a good joint was obtained at high welding speeds. A thermocouple was installed on the plate 13 mm from the joint on the advancing side to collect temperature data during the welding process. Figure 20 As shown, it can be found that under different welding speed process parameters of 100 to 1000 mm / min, the temperature of biaxial shoulder friction stir welding without cooling water is about 6 to 23°C higher than that of the present invention. This means that the present invention can significantly reduce the heat input during the welding process, which helps to refine the joint grains and improve the joint strength.

[0093] like Figure 21 As shown, tensile specimens were obtained by wire cutting in the latter half of the weld (the specimen dimensions were: plate thickness a0 = 6 mm, specimen width b0 = 24 mm, parallel length Lc = 67 mm, total specimen length Lt = 145 mm, and transition radius r = 24 mm). Tensile specimens of conventional biaxial shoulder friction stir welding and the present invention were prepared at different welding speeds. Figure 22 As shown, the welded samples obtained by the present invention have significantly better tensile strength than the traditional biaxial shoulder friction stir welding method. Therefore, the present invention has a wider process parameter window, significantly reduces the heat input of the joint welding process, and is conducive to obtaining excellent mechanical properties of the joint.

[0094] Example 5

[0095] The difference between this embodiment and Embodiment 4 lies in the use of different process parameters and materials for friction stir welding. Titanium alloys readily react with oxygen and nitrogen under high-temperature welding conditions, forming titanium oxide and titanium nitride. These oxides significantly reduce the plasticity and toughness of the titanium alloy. Therefore, this embodiment specifically adds a nozzle to provide argon gas protection to the working area 265 of the stirring pin, thereby effectively improving the welding quality of the titanium alloy.

[0096] This embodiment uses the stirring tool from Embodiment 1 for friction stir welding. For example... Figure 4 As shown, the workpieces 121 to be welded are two TC4 titanium alloy plates that require butt friction stir welding, each with dimensions of 300 mm long × 100 mm wide × 4 mm thick. The butt joint area of ​​the workpieces 121 is sanded and cleaned with alcohol. After pre-treatment, the workpieces 121 are clamped onto the welding platform 12 using the fixing clamp 122. The upper shoulder 23, lower shoulder 24, and stirring pin 26 are made of tungsten-rhenium alloy, while the upper clamping body 21 and outer sleeve 22 are made of tool steel H13 (heat-treated by quenching). The end faces 236 of the upper shoulder and 241 of the lower shoulder are both concave, with a diameter of 16 mm. The distance between the upper shoulder 23 and the lower shoulder 24 is adjusted to 3.9 mm using the locking nut 25.

[0097] The process steps for using a stirring tool in friction stir welding in this embodiment are as follows:

[0098] (1) Drive the Z-axis drive module 11 to make the double-shoulder stirring tool 2 pass through the welding platform 12. The axis of the stirring needle 26 is located on the mating surface of the workpiece 121 to be welded, and the upper shoulder end face 236 is 0.05 mm lower than the upper surface of the workpiece 121 to be welded.

[0099] (2) Start the friction stir welding machine 1. The double-shoulder stirring tool 2 rotates counterclockwise at 350 rpm and the welding speed is 20 mm / min. The welding process begins. As the double-shoulder stirring tool 2 moves in the welding direction, the upper cutting surface 2361 of the upper shoulder 23 and the lower cutting surface 2411 of the lower shoulder 24 first come into contact with the workpiece 121 to be welded. As the upper shoulder 23 and the lower shoulder 24 rotate and cut in further, the stirring needle working area 265 comes into contact with the workpiece 121 to be welded.

[0100] (3) such as Figure 16 As shown, the cooling function is activated, and the cooling medium (cooling water with a flow rate of 7L / min and a temperature of 20°C) is introduced from the rotary interface 1111 of the adapter tool holder 111. The cooling medium passes sequentially through the tool holder core channel 1112, the upper clamping body core channel 213, the upper shoulder core hole channel 231, and the stirring pin core channel 261, and finally falls directly into the cooling medium storage tank 124 below the welding platform 12. An argon protective atmosphere is provided to the working area 265 of the stirring pin through a nozzle (the nozzle is not shown in the attached figure).

[0101] (4) The dual-shoulder stirring tool 2 continues to move and weld along the set welding path;

[0102] (5) After completing the predetermined welding path, the double-shoulder stirring tool 2 rotates away from the workpiece after welding;

[0103] (6) The dual-shoulder stirring tool 2 stops rotating and moving, and the cooling medium and argon gas supply is stopped after about 2 minutes;

[0104] (7) Drive the Z-axis drive module 11 to make the dual-shoulder stirring tool 2 return to the origin position and complete the welding task.

[0105] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0106] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-shouldered friction stir welding tool characterized by: It includes an upper clamping body at the top, an upper shoulder at the middle, an outer sleeve fitted over the upper clamping body and the upper shoulder, a stirring needle, and a lower shoulder at the bottom; the upper clamping body, the upper shoulder, the stirring needle, and the lower shoulder are all coaxially arranged, and the core of the upper clamping body, the upper shoulder, and the stirring needle are respectively provided with a core channel of the upper clamping body, a core hole channel of the upper shoulder, and a core channel of the stirring needle; The outer wall of the stirring needle is provided with a stirring needle positioning cylindrical surface, a stirring needle first external thread, a stirring needle working area, and a stirring needle second external thread from top to bottom. The upper shoulder is provided with a stirring needle positioning hole and an upper shoulder first internal thread hole from top to bottom along the upper shoulder core hole channel. The stirring needle positioning hole and the stirring needle positioning cylindrical surface are matched for shaft hole positioning, and the upper shoulder first internal thread hole and the stirring needle first external thread are matched for thread matching, so that the stirring needle is coaxially fixed inside the upper shoulder. The lower shoulder is provided with a through lower shoulder second internal thread hole on the axis, and the lower shoulder second internal thread hole and the stirring needle second external thread are matched for thread matching.

2. A bi-shouldered friction stir welding tool according to claim 1, wherein: A turbulence support is provided inside the core channel of the stirring needle. The turbulence support has a ribbon-type spiral blade structure, and its blades are in contact with the inner wall of the core channel of the stirring needle.

3. The dual-shouldered friction stir welding tool of Claim 1, wherein: The stirring needle core channel is one of the following: polygonal through hole, petal-shaped through hole, and topological curved porous structure.

4. The dual-shouldered friction stir welding tool of Claim 1, wherein: It also includes a locking nut, which is located at the lower part of the lower shoulder.

5. The dual-shouldered friction stir welding tool of Claim 1, wherein: The stirring needle working area includes a second upward stirring thread on the upper part of its main body, a first downward stirring thread on the lower part of its main body, and stirring needle cross-sections evenly distributed in the stirring needle working area.

6. The dual-shoulder friction stir welding tool according to claim 1, characterized in that: The upper shoulder includes a first fixing surface and a second fixing surface. The first fixing surface is located on the outer circumferential surface of the upper part of the upper shoulder, and the upper shoulder is installed on the lower part of the upper clamping body through the first fixing surface of the upper shoulder engaging with the surface of the lower part of the upper clamping body. The second fixing surface is located on the outer circumferential surface of the lower part of the upper shoulder. The upper shoulder is fixed in the Z-direction with the outer sleeve through the second fixing surface of the upper shoulder. The outer sleeve is provided with an outer sleeve fixing screw, and the upper clamping body second fixing surface is provided on the outer circumferential surface of the middle part of the upper clamping body. The outer sleeve is fixed by the outer sleeve fixing screw engaging with the surface of the upper clamping body second fixing surface.

7. A core-cooled friction stir welding machine characterized by: The system includes a frame, a gantry frame, an X-axis drive module, a Y-axis drive module, a Z-axis drive module, an adapter tool holder, a mixing tool, a welding platform, and the mixing tool as described in any one of claims 1 to 6; the gantry frame is mounted on the base of the frame; the Y-axis drive module is mounted on the crossbeam of the gantry frame; the Z-axis drive module is connected to the Y-axis drive module, and its lower output end is connected to the adapter tool holder, the lower part of the adapter tool holder is connected to the mixing tool, and the Z-axis drive module drives the mixing tool to perform Z-axis movement and Z-axis rotation through the adapter tool holder; The X-axis drive module is mounted on the frame, and the welding platform is mounted on the X-axis drive module. The X-axis drive module drives the welding platform to move in the X-axis direction. The welding platform is provided with a through-hole for the lower shoulder and the stirring needle to pass through.

8. A method of using a dual-shouldered friction stir welding tool, the method comprising: Using the dual-shoulder friction stir welding tool according to any one of claims 1 to 6, the steps include: S1: Clamp the workpiece to be welded onto the welding platform, and make the mating surface of the workpiece to be welded coincide with the symmetrical plane of the through hole provided on the welding platform. S2: Drive the dual-shoulder friction stir welding tool so that the upper shoulder end face is at the same height as the starting surface of the workpiece to be welded, and record the position of the dual-shoulder friction stir welding tool as follows. Position the stirring pin axis on the mating surface of the workpiece to be welded, and ensure the stirring pin contacts the starting point of the weld on the workpiece. Record the position of the dual-shoulder friction stir welding tool as follows: , The starting point calibration of the dual-shoulder friction stir welding tool is completed; S3: Set the thickness of the workpiece to be welded to... The press-in amount of the upper shoulder is The press-in amount of the lower shoulder is spindle speed Welding speed Install the lower shaft shoulder and adjust its distance from the upper shaft shoulder to be as follows: The lower shoulder is then fixed in this position by tightening the lock nut. S4: Drive the dual-shoulder friction stir welding tool to a certain position away from the welding start position of the workpiece in the X-axis direction. Set the starting rotation position of the dual-shoulder friction stir welding tool to ( , , ),in , , ; S5: Welding begins according to the set path, as the stirring needle rotates and enters the workpiece to be welded. After a certain time, the flow rate will be... Temperature is The cooling medium is introduced into the channel of the stirring needle core; S6: When the stirring pin leaves the workpiece to be welded post-dwell, wait after a time, stop the cooling medium supply; S7: Welding work completed.

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