A half-thread type stirring head

Abstract

The application discloses a half-thread type stirring head, which comprises a shaft shoulder surface and a stirring needle, the shaft shoulder surface is provided with a radial spiral groove, the outer circumferential surface of the stirring needle is provided with a threaded groove, the root of the threaded groove is located at the joint of the shaft shoulder surface and the stirring needle, and the thread length of the threaded groove is smaller than the needle length of the stirring needle. The stirring head is redesigned, the threaded structure of the stirring needle is changed from a full-thread structure to a half-thread structure, the inner concave structure of the shaft shoulder surface is changed to a petal structure, the thread depth of the stirring needle is deepened, the stirring force is increased, the cold lap joint defects in FSW are solved through structural adjustment and size fine adjustment, and the drawing requirements and the trial performance requirements of the parts are met.

Description

Technical Field

[0001] This invention relates to friction welding, specifically a semi-threaded stirring head. Background Technology

[0002] The unique defect that occurs during friction stir welding (FSW) – cold lap – can significantly affect weld strength. Under prolonged high-pressure working conditions, it can cause cracking or detachment of the weld plate. The cold lap problem has always been a complex and difficult technical challenge in the FSW process.

[0003] Existing stirring heads such as Figure 1 and Figure 2 As shown, the shoulder surface 2 of the stirring head 1 is provided with an inwardly concave arc shoulder 21. The starting point of the thread 31 of the stirring needle 3 is located at the junction of the shoulder surface 2 and the stirring head 3, and ends at the outer end face of the stirring head 3, which is a fully threaded state.

[0004] Defect generation principle: 1. Cold lap joint defects generally occur in structural parts with lap welds (overlap welds); 2. The main reason is that the length and shape of the stirring needle are not ideal, which results in the material at the bottom of the weld not being fully stirred or insufficient frictional heat. In addition, the equipment used is an inclined device. During the stirring and friction process, since the lap welding requires penetrating the welding plate to stir and fuse the materials of the shell and the welding plate, the stirred slurry will fuse and fill to the side of the stirring head rotation. Also, the welding movement speed is fast, and there is a loss of slurry and heat on the retreating side, which will cause this defect. Figure 3 This is a diagram of a cold-lap joint. Figure 4 This refers to the cold lap joint interface that occurs during actual friction welding when using an existing stirring head solution. Figure 5 yes Figure 4 Enlarged view of a portion of the diagram. Figure 5 The dimensions are marked in the text. h represents the penetration depth of the cold lap / hook defect, t1 represents the thickness of the upper plate, and wp represents the effective lap width. The standard requirements for cold lap are h≤0.15t1 and wp≥0.8t1.

[0005] When t1=2mm, h must satisfy h≤0.15×2, i.e., h≤0.3mm to be qualified. However, in this scheme, h=0.85mm is greater than 0.3mm, which means that h does not meet the requirements. wp must satisfy wp≥0.8×2, i.e., wp≥1.6mm to be qualified. However, in this scheme, wp=1.45mm is less than 1.6mm, which means that wp does not meet the requirements.

[0006] Therefore, the structure of the existing stirring head needs to be improved. Summary of the Invention

[0007] To address the shortcomings of the prior art, the present invention provides a semi-threaded stirring head.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solution: a semi-threaded stirring head, comprising a shoulder surface and a stirring pin, wherein the shoulder surface is provided with radial spiral grooves, and the outer peripheral surface of the stirring pin is provided with threaded grooves, the root of the threaded grooves being located at the junction of the shoulder surface and the stirring pins, and the thread length of the threaded grooves being less than the pin length of the stirring pins.

[0009] The thread length of the threaded groove is 25%-75% of the needle length of the stirring needle.

[0010] The stirring needle has a frustum structure.

[0011] In summary, the present invention has achieved the following technical effects: This invention redesigns the stirring head, changing the thread structure of the stirring pin from a full thread structure to a half thread structure, and changing the shoulder surface from an inward concave structure to a petal structure. The thread depth of the stirring pin is increased to enhance the stirring force. Through structural adjustments and dimensional fine-tuning, the cold lap joint defect that occurs in FSW is resolved, meeting the requirements of the drawings and the trial performance requirements of the parts. Attached Figure Description

[0012] Figure 1 This is a front view of the existing mixing head; Figure 2 yes Figure 1 Schematic diagram of the shaft side of the stirring head; Figure 3 This is a diagram of a cold-lap joint; Figure 4 This is a schematic diagram of the cold lap joint interface that occurs during actual friction welding using an existing stirring head solution. Figure 5 yes Figure 4 Enlarged view of a portion of the image; Figure 6 This is a front view of the stirring head of this application; Figure 7 yes Figure 6 Right view of the shoulder surface of the central shaft and the side of the stirring needle; Figure 8 yes Figure 6 Schematic diagram of the shaft side of the stirring head; Figure 9 It is Figure 8 The main view; Figure 10 This is a schematic diagram of material flow during the friction stir welding process using an existing stirring head. Figure 11 This is a schematic diagram of the microscopic defect morphology generated by the existing stirring head design. Figure 12This is a schematic diagram of the material flow during the friction stir welding process with the stirring head of this application; Figure 13 This is a schematic diagram of the microscopic defect morphology generated by the stirring head of this application; Figure 14 This is a schematic diagram of the cold lap joint interface that occurs during actual friction welding using the stirring head of this application. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings.

[0014] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

[0015] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention 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 invention.

[0016] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0017] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0018] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0019] like Figures 6 to 9 As shown, a semi-threaded stirring head 1 includes a shoulder surface 2 and a stirring needle 3. The shoulder surface 2 is provided with radial spiral grooves 22, and the outer peripheral surface of the stirring needle 3 is provided with threaded grooves 32. The root of the threaded grooves 32 is located at the junction of the shoulder surface 2 and the stirring needle 3, and the thread length of the threaded grooves 32 is less than the needle length of the stirring needle 3.

[0020] This invention sets the shoulder surface as a radial petal structure, which can improve the guiding and extrusion effect. The threaded groove 32 of the stirring needle 3 guides and accumulates the slurry from bottom to top. Under the extrusion force of the shoulder surface 2, the slurry is guided by the radial spiral groove 22 of the petal structure and then disperses to all sides. Combined with the forward and rotational movement of the stirring head 1, the friction welding process is realized. This application sets the threaded structure as a semi-threaded structure, which can lift the slurry from bottom to top, transfer the material concentration area to the top of the overlapping interface, and release force to all sides, effectively suppressing the height of the hook defect.

[0021] The thread depth of the thread groove 32 is 0.25mm. This invention increases the thread depth from the original 0.13mm to 0.25mm. The increased groove depth can increase the stirring force, reduce the penetration depth h of cold lap / hook defects, and increase the effective lap width wp.

[0022] Furthermore, the thread length of the threaded groove 32 in this application is 25%-75% of the needle length of the stirring needle 3, for example, 25%, 57%, 60%, 75%, etc.

[0023] The stirring needle 3 has a frustum structure.

[0024] exist Figures 10 to 14 In this context, Lap Interface represents the lap joint interface, TMAZ represents the thermo-mechanical affected zone, material concentrated zone represents the material concentrated zone, HAZ represents the heat affected zone, SAZ represents the shoulder affected zone, WNZ represents the weld nugget zone, EST represents the outer side of the shoulder, AS represents the advancing side, RS represents the retreating side, BM represents the base material, and ELW represents the effective lap width, i.e., wp mentioned above.

[0025] Figure 10 This is a schematic diagram of material flow during the friction stir welding process using an existing stirring head. Figure 11 This is a schematic diagram of the microscopic defect morphology generated by the existing mixing head. It can be seen that the material concentrated zone is located below the lap interface. The force released in all directions below the lap interface will significantly cause hook-shaped defects and increase the penetration depth h of the cold lap / hook-shaped defects.

[0026] Figure 12 This is a schematic diagram of the material flow during the friction stir welding process using the stirring head of this application. Figure 13 This is a schematic diagram of the microscopic defect morphology generated by the stirring head of this application. It can be seen that a material concentrated zone appears above the lap interface. The upper material concentrated zone releases force outwards from the upper side of the lap interface, while the lower material concentrated zone releases force outwards from the lower side of the lap interface. This results in force release from both the upper and lower sides of the lap interface, which can cancel each other out, thereby effectively suppressing the intrusion depth h of cold lap / hook-shaped defects, i.e., effectively suppressing... Figure 12 The degree of fluctuation of the purple line in the middle.

[0027] Comparative Example: Parameter settings: upper plate thickness t1 = 2mm, needle length of stirring pin 3 is 2.8mm, thread length of thread groove 31 is 2.8mm, accounting for 100% of the needle length; friction welding is performed using a stirring head that meets the above parameters, and the results are as follows. Figure 5 As shown.

[0028] Example: Parameter settings: upper plate thickness t1 = 2mm, needle length of stirring pin 3 is 2.8mm, thread length of thread groove 32 is 1.6mm, approximately 57% of the needle length; friction welding is performed using a stirring head conforming to the above parameters, and the results are as follows. Figure 14 As shown.

[0029] It can be seen that, Figure 14 In the equation, h = 0.12mm is less than 0.3mm, indicating that h meets the requirements; wp = 2.35mm is greater than 1.6mm, indicating that wp meets the requirements.

[0030] In summary, the stirring head of this application can significantly improve defects in the overlapping area, and may even make the defects negligible, thus meeting performance requirements and drawing requirements.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A semi-threaded stirring head, characterized in that: It includes a shoulder surface (2) and a stirring needle (3). The shoulder surface (2) is provided with radial spiral grooves (22). The outer peripheral surface of the stirring needle (3) is provided with a threaded groove (32). The root of the threaded groove (32) is located at the junction of the shoulder surface (2) and the stirring needle (3). The thread length of the threaded groove (32) is less than the needle length of the stirring needle (3).

2. The semi-threaded stirring head according to claim 1, characterized in that: The thread length of the threaded groove (32) is 25%-75% of the needle length of the stirring needle (3).

3. A semi-threaded stirring head according to claim 1, characterized in that: The stirring needle (3) has a frustum structure.

4. A semi-threaded stirring head according to claim 1, characterized in that: The thread depth of the threaded groove (32) is 0.25 mm.

5. A semi-threaded stirring head according to claim 1, characterized in that: The thread length of the threaded groove (32) is 1.6 mm, and the needle length of the stirring needle (3) is 2.8 mm.

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