A friction stir welding tool

Abstract

This invention provides a stirring head for friction stir welding. The stirring head includes a holding handle, a stirring pin, and a shoulder. The shoulder is located at one end of the holding handle and is frustoconical in shape. The lower surface of the shoulder connects to the holding handle, and the center of the upper surface of the shoulder connects to the root of the stirring pin. The stirring pin is conical, and its side is provided with a double right-hand thread structure. The double right-hand thread structure includes a first right-hand thread and a second right-hand thread. The first right-hand thread includes a single-start thread, and the second right-hand thread includes a three-start thread. The stirring head provided by this invention can solve the weld defects caused by insufficient heat input and inadequate material flow in the initial stage of friction welding, and improve the weld formation quality and mechanical properties in the initial stage of welding.

Description

Technical Field

[0001] This utility model relates to the field of friction stir welding technology, and specifically to a stirring head for friction stir welding. Background Technology

[0002] Friction stir welding is a solid-state joining technology. Its core principle involves inserting a high-speed rotating stirring head (consisting of a shoulder and stirring pins) into the workpiece to be welded. Frictional heat and plastic deformation soften the material without melting it, and metallurgical bonding is achieved as the stirring head moves. In the initial stage of welding (typically within the first 20-100mm), traditional stirring heads often fail to stabilize due to unstable temperature fields, material flow, and mechanical states, leading to weld defects (such as voids, incomplete fusion, and surface grooves), which reduce the weld's mechanical properties. Severe defects may necessitate rework or even product scrap, resulting in wasted materials and processing time, and reduced production efficiency.

[0003] Statistics show that approximately 68% of defects in friction stir welding are concentrated within the first 50mm of the weld. In the aerospace field, the scrap rate of welds due to initial defects is as high as 15-20%. In the welding of battery trays for new energy vehicles, initial defects reduce fatigue life by 30-45%. To address these issues, existing processes mainly involve adding a lead-in plate or laser preheating. However, removing the lead-in plate easily leads to material loss (approximately 15-25%) and increases clamping and cutting steps, extending the production cycle. While laser preheating can rapidly increase the initial temperature and shorten the thermal equilibrium time, it has higher manufacturing costs and expands the heat-affected zone, potentially causing grain coarsening or deformation of the base material.

[0004] CN119566506A discloses a friction stir welding head for improving the flow efficiency of base metal. The friction stir welding head body includes a clamping part, and a spiral stirring pin is provided at one end of the clamping part. The spiral stirring pin spirals and contracts toward the end of the stirring pin, and a shoulder is provided on the radial outer circumference of the spiral stirring pin. The shoulder is a concave asymptotic groove shoulder. The spiral stirring pin has a three-sectioned conical thread structure. The end of the spiral stirring pin is provided with an outwardly protruding end structure.

[0005] CN119525689A discloses a method for improving the flowability of weld metal in friction stir welding of dissimilar aluminum alloys. The method includes the following steps: butt-fitting 7075 and 6061 aluminum alloy plates and performing friction stir welding; the ratio of the length of the stirring pin to the thickness of the aluminum alloy plate is 0.675-0.725. This method influences the flowability and uniformity of hardness distribution of the weld joint in friction stir butt welding of dissimilar aluminum alloys by adjusting the length of the stirring pin.

[0006] However, the aforementioned stirring pin still cannot solve the welding defect problem in the initial stage of welding. Therefore, it is of great significance to provide a stirring head for friction stir welding that can solve the above problems. Utility Model Content

[0007] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a stirring head for friction stir welding. The stirring head can solve the weld defects caused by insufficient heat input and insufficient material flow in the initial stage of friction welding, and improve the weld formation quality and mechanical properties in the initial stage of welding.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This utility model provides a stirring head for friction stir welding, the stirring head including a holding handle, a stirring needle and a shoulder;

[0010] The shoulder is located at one end of the holding handle. The shoulder is shaped like a frustum. The lower bottom surface of the shoulder is connected to the holding handle, and the center of the upper bottom surface of the shoulder is connected to the root of the stirring needle.

[0011] The stirring needle is conical, and the side of the stirring needle is provided with a double right-hand thread structure;

[0012] The double right-hand thread structure includes a first right-hand thread and a second right-hand thread;

[0013] The first right-hand thread includes a single-start thread;

[0014] The second right-hand thread includes a three-thread thread.

[0015] Traditional friction stir heads suffer from insufficient heat generation, poor material flowability, and less than 60% material filling rate on the retreating side during the initial welding stage. This leads to defects such as voids and surface grooves in the weld, reducing its mechanical properties and, in severe cases, requiring rework or even scrapping. This invention improves the shoulder and stirring pin of the stirring head. The stirring pin adopts a conical structure, effectively avoiding stress concentration during welding and thus extending the head's lifespan. Furthermore, the stirring pin's side is designed with a double right-hand thread structure, consisting of a single-start thread and a triple-start thread (symmetrically distributed along the stirring pin's axis). The two spiral channels formed facilitate material flow and mixing in different directions, ensuring uniform material distribution within the weld and more effectively promoting material flow within the welding area. Its complex surface structure generates more heat during welding, contributing to a more uniform heat distribution in the welding area and achieving a more uniform temperature field. This allows the welding area to reach thermal equilibrium more quickly, resulting in a defect-free weld joint with excellent mechanical properties.

[0016] Preferably, the upper bottom surface of the shoulder is provided with a spiral groove.

[0017] Preferably, the groove depth of the spiral groove is 1-1.5mm, for example, it can be 1mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm or 1.5mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] In this invention, the structure of the shoulder is optimized by incorporating a spiral groove with its depth preferably controlled within a specific range. When the shoulder rotates, it generates centripetal pressure, forcing material to fill the cavity behind the stirring needle. This spiral groove allows edge material to return to the weld center, reducing surface groove defects. Furthermore, the spiral groove structure increases the actual frictional contact area by 20-30% (compared to a flat surface), improving frictional heat generation efficiency and rapidly establishing the welding temperature field, thereby preventing defects in the initial welding stage. In short, the spiral groove in this invention improves material flowability, optimizes the thermal field, and solves the problem of insufficient edge material filling.

[0019] Preferably, the cone angle of the stirring needle is 20-35°, for example, it can be 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°, 29°, 30°, 31°, 32°, 33°, 34° or 35°, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the connection between the root of the stirring needle and the bottom surface of the shoulder is rounded.

[0021] Preferably, the radius of the fillet is 1-2 mm, for example, it can be 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm or 2 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In this invention, by preferably setting the rounded corners and controlling their radius, the stress concentration phenomenon of the stirring pin during the welding process can be further avoided, thereby improving the service life of the stirring head.

[0023] Preferably, the pitch of the single-threaded thread is 0.8-1.2mm, for example, it can be 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1.0mm, 1.05mm, 1.1mm, 1.15mm or 1.2mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the thread depth of the single-threaded thread is 0.4-0.7mm, for example, it can be 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, 0.52mm, 0.54mm, 0.56mm, 0.58mm, 0.6mm, 0.62mm, 0.64mm, 0.66mm, 0.68mm or 0.7mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, the pitch of the three-thread thread is 10-15mm, for example, it can be 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm or 15mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the thread depth of the three-thread is 1.5-3mm, for example, it can be 1.5mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm or 3mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] The stirring head for friction stir welding provided by this utility model is used in the friction stir welding process as follows:

[0028] Connect the clamping handle to the spindle of the friction stir welding equipment, adjust the parameters of the welding equipment, such as the spindle speed and the feed speed of the stirring head, move the stirring head to the starting position of the workpiece to be welded, start the welding equipment, the spindle drives the stirring head to rotate, under the rotation and feed motion of the stirring head, the stirring needle penetrates into the interior of the workpiece material, causing the material to flow around the stirring needle, the stirring needle continuously penetrates into new welding areas, and at the same time pushes the mixed material to the back of the weld, forming a continuous weld.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) In this utility model, the stirring pin adopts a conical structure, which can effectively avoid the stress concentration phenomenon of the stirring pin during the welding process, thereby improving the service life of the stirring head; at the same time, the side of the stirring pin is designed with a double right-hand thread structure, and the two spiral channels formed by it help the material to flow and mix in different directions, thereby ensuring the uniform distribution of the material in the weld, more effectively promoting the material flow in the welding area, and its complex surface structure can generate more heat during the welding process, which is conducive to achieving a more uniform temperature field, enabling the welding area to reach the thermal equilibrium state more quickly, and forming a defect-free welding joint with good mechanical properties.

[0031] (2) In this utility model, a spiral groove is preferably provided on the shaft shoulder. When the shaft shoulder rotates, it generates centripetal pressure, which forces the material to fill the cavity behind the stirring needle. The spiral groove allows the edge material to return to the center of the weld, reducing surface groove defects. Furthermore, the structure of the spiral groove increases the actual friction contact area by 20-30% (compared to a plane), which can improve the friction heat generation efficiency and quickly establish the welding temperature field, thereby avoiding the generation of defects in the initial stage of welding. Attached Figure Description

[0032] Figure 1 This is a front view of the stirring head for friction stir welding provided in Embodiment 1 of this utility model;

[0033] Figure 2 for Figure 1 Right view of the stirring head provided for friction stir welding;

[0034] Figure 3 This is a schematic diagram of the structure of the stirring needle in the stirring head provided in Embodiment 1 of this utility model;

[0035] In the diagram: 1-Holding handle; 2-Shoulder; 3-Stirring needle; 4-Single thread; 5-Three thread; 6-Helical groove; 7-Rounded corner. Detailed Implementation

[0036] It should be understood that in the description of this utility model, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying 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 limitations on this utility model.

[0037] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0038] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] This embodiment provides a stirring head for friction stir welding, such as... Figure 1 , Figure 2 and Figure 3 As shown, the stirring head includes a holding handle 1, a stirring needle 3, and a shoulder 2. The shoulder 2 is located at one end of the holding handle 1 and is shaped like a frustum. The lower surface of the shoulder 2 is connected to the holding handle 1, and the center of the upper surface of the shoulder 2 is connected to the root of the stirring needle 3. The stirring needle 3 is conical with a cone angle of 30°. The side of the stirring needle 3 is provided with a double right-hand thread structure, which includes a first right-hand thread and a second right-hand thread. The first right-hand thread includes a single-start thread 4 with a pitch of 1 mm and a thread depth of 0.5 mm. The second right-hand thread includes a triple-start thread 5 with a pitch of 12 mm and a thread depth of 2 mm.

[0041] The upper bottom surface of the shoulder 2 is provided with a spiral groove 6, the groove depth of the spiral groove 6 is 1.2mm, and the connection between the root of the stirring needle 3 and the upper bottom surface of the shoulder 2 is provided with a rounded corner 7, the radius of which is 1.5mm.

[0042] Example 2

[0043] This embodiment provides a stirring head for friction stir welding. The stirring head includes a holding handle, a stirring pin, and a shoulder. The shoulder is disposed at one end of the holding handle and is frustoconical in shape. The lower surface of the shoulder is connected to the holding handle, and the center of the upper surface of the shoulder is connected to the root of the stirring pin. The stirring pin is conical with a cone angle of 20°. The side of the stirring pin is provided with a double right-hand thread structure, which includes a first right-hand thread and a second right-hand thread. The first right-hand thread includes a single-start thread with a pitch of 1.2 mm and a thread depth of 0.7 mm. The second right-hand thread includes a triple-start thread with a pitch of 15 mm and a thread depth of 3 mm.

[0044] The upper bottom surface of the shoulder is provided with a spiral groove with a groove depth of 1.5mm. The connection between the root of the stirring needle and the upper bottom surface of the shoulder is provided with a rounded corner with a radius of 2mm.

[0045] Example 3

[0046] This embodiment provides a stirring head for friction stir welding. The stirring head includes a holding handle, a stirring pin, and a shoulder. The shoulder is located at one end of the holding handle and is frustoconical in shape. The lower surface of the shoulder is connected to the holding handle, and the center of the upper surface of the shoulder is connected to the root of the stirring pin. The stirring pin is conical with a cone angle of 35°. The side of the stirring pin is provided with a double right-hand thread structure, which includes a first right-hand thread and a second right-hand thread. The first right-hand thread includes a single-start thread with a pitch of 0.8 mm and a thread depth of 0.4 mm. The second right-hand thread includes a triple-start thread with a pitch of 10 mm and a thread depth of 1.5 mm.

[0047] The upper bottom surface of the shoulder is provided with a spiral groove with a groove depth of 1mm. The connection between the root of the stirring needle and the upper bottom surface of the shoulder is provided with a rounded corner with a radius of 1mm.

[0048] The stirring head for friction stir welding provided in the above embodiments is used in the following process:

[0049] Connect the clamping handle to the spindle of the friction stir welding equipment, adjust the parameters of the welding equipment, such as the spindle speed and the feed speed of the stirring head, move the stirring head to the starting position of the workpiece to be welded, start the welding equipment, the spindle drives the stirring head to rotate, under the rotation and feed motion of the stirring head, the stirring needle penetrates into the interior of the workpiece material, causing the material to flow around the stirring needle, the stirring needle continuously penetrates into new welding areas, and at the same time pushes the mixed material to the back of the weld, forming a continuous weld.

[0050] In summary, the stirring head provided by this utility model can solve the problem of weld defects caused by insufficient heat input and insufficient material flow in the initial stage of friction welding, and improve the weld formation quality and mechanical properties in the initial stage of welding.

[0051] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A friction stir welding tool, characterized by, The stirring head includes a holding handle, a stirring needle, and a shaft shoulder; The shoulder is located at one end of the holding handle. The shoulder is shaped like a frustum. The lower bottom surface of the shoulder is connected to the holding handle, and the center of the upper bottom surface of the shoulder is connected to the root of the stirring needle. The stirring needle is conical, and the side of the stirring needle is provided with a double right-hand thread structure; The double right-hand thread structure includes a first right-hand thread and a second right-hand thread; The first right-hand thread includes a single-start thread; The second right-hand thread includes a three-thread thread.

2. The friction stir welding tool according to claim 1, wherein The upper bottom surface of the shoulder is provided with a spiral groove.

3. The stirring head for friction stir welding according to claim 2, characterized in that, The depth of the spiral groove is 1-1.5 mm.

4. The friction stir welding tool of Claim 1 wherein, The cone angle of the stirring needle is 20-35°.

5. The friction stir welding tool of Claim 1 wherein, The connection between the root of the stirring needle and the bottom surface of the shoulder is rounded.

6. The friction stir welding tool of Claim 5 wherein, The radius of the fillet is 1-2 mm.

7. The friction stir welding tool of Claim 1 wherein, The pitch of the single-threaded thread is 0.8-1.2 mm.

8. The friction stir welding tool of Claim 1 wherein, The thread depth of the single-threaded thread is 0.4-0.7 mm.

9. The friction stir welding tool of Claim 1 wherein, The pitch of the three-threaded screw is 10-15mm.

10. The friction stir welding tool of Claim 1 wherein, The thread depth of the three-thread is 1.5-3mm.

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