Method for friction stir welding of aluminum alloy interface connection and self-cleaning of the tool
By optimizing friction stir welding parameters and self-cleaning processes, the problems of interface connection defects and weld head deposits in aluminum alloy friction stir welding were solved, achieving efficient and non-destructive welding quality improvement and extended weld head life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGXI UNIV
- Filing Date
- 2026-05-12
- Publication Date
- 2026-06-09
AI Technical Summary
In aluminum alloy friction stir welding, interface joints are prone to defects such as incomplete welding, voids, and excessive brittle intermetallic compounds. Adhesives on the weld head surface affect the stability and quality of the welding process, and there is a lack of effective welding parameter optimization and weld head self-cleaning technology.
By optimizing friction stir welding parameters and self-cleaning processes, including selecting the fixing method, setting the stirring head speed, feed rate, tilt angle, and insertion depth, and combining frictional heat softening and mechanical shearing peeling mechanisms, welding quality is improved and the welding head becomes self-cleaning.
It improves the mechanical properties and forming quality of aluminum alloy friction stir welding, extends the life of the welding head, and ensures the continuity and stability of the welding process.
Smart Images
Figure CN122165014A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum alloy friction stir welding technology, and in particular to a method for interface connection and self-cleaning of welding head in aluminum alloy friction stir welding. Background Technology
[0002] In the context of intelligent manufacturing, aluminum alloys, with their advantages of being lightweight, high-strength, and corrosion-resistant, are widely used in the manufacture of large and complex structural components in aerospace, rail transportation, and national defense industries. Friction stir welding (FSW), as a core technology for solid-state joining of aluminum alloys, directly determines the reliability of components in service due to the quality of its interface bonding. However, aluminum oxides, metal debris, and other adhering substances on the weld head surface can severely affect the stability of the welding process, the interface bonding effect, and the weld formation quality, becoming a key bottleneck restricting the efficient application of FSW. This study addresses the common defects in the interface bonding of aluminum alloy FSW, such as incomplete bonding, voids, and excessive brittle intermetallic compounds. Based on the solid-state joining characteristics of aluminum alloy FSW, this study analyzes the influence of welding parameters such as stirring head rotation speed, feed rate, tilt angle, and insertion depth on interface plastic flow, heat input distribution, and oxide film breakage and dispersion. This aims to solve the technical challenges of poor interface bonding and high defect rate in aluminum alloy FSW, thereby improving the mechanical properties and forming quality of the weld. This study aims to clarify the synergistic mechanism of frictional heat generation, softening and embrittlement of deposits, and mechanical peeling during the cleaning process. It optimizes self-cleaning process parameters to achieve efficient, non-destructive, and rapid removal of deposits from the welding head surface, avoiding wear and secondary contamination during cleaning and ensuring the continuity and stability of the welding process. By integrating interface connection optimization and welding head self-cleaning technology, an integrated process solution for aluminum alloy friction stir welding is constructed, balancing connection quality and cleaning efficiency. This provides technical support for the efficient and high-quality welding of large and complex aluminum alloy structures. Current research on aluminum alloy friction stir welding lacks studies on the influence of welding parameters on welding quality and on welding head self-cleaning processes.
[0003] To address the aforementioned issues, this invention proposes a method for interface connection and self-cleaning of the welding head in aluminum alloy friction stir welding. This method enables aluminum alloy friction stir welding and parameter selection and optimization; it fills the technical gap in the mechanism of parameter action and self-cleaning of the welding head in aluminum alloy friction stir welding, and promotes the development of engineering technology. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies and fill related technological gaps, this invention provides a method for interface connection and self-cleaning of the welding head in aluminum alloy friction stir welding. This method addresses the interface connection technology and self-cleaning of the welding head in aluminum alloy friction stir welding, including selecting a fixing method based on the position, shape, and thickness of the welded components; performing tool setting and zeroing operations on the friction stir welding equipment; and conducting trial welding with the stirring head following a preset trajectory. It also involves setting aluminum alloy friction stir welding parameters and analyzing the effects of stirring head rotation speed, feed rate, tilt angle, and insertion depth on the welding effect; and cleaning residual oxides from the friction stir welding head using a composite cleaning mechanism combining frictional heat softening and mechanical shearing peeling.
[0005] The technical solution adopted by this invention to solve its technical problem is as follows: A method for interface connection and self-cleaning of welding head in aluminum alloy friction stir welding, characterized by comprising the following steps:
[0006] Step (1): Select the fixing method according to the structural shape and plate thickness of the aluminum alloy welded component. Use pressure blocks to compact the welding plate so that the aluminum alloy component is placed as close as possible to the center of the work platform and remains symmetrical. Use pressure blocks to compact the aluminum alloy welded component to ensure that it cannot move and that the welded aluminum alloy mother plate or component is flat, tight and does not warp.
[0007] Step (2): After fixing the aluminum alloy mother plate, move the stirring head in the X direction along the feeding direction of the stirring head, in the Y direction along the back and forth movement direction of the working platform, and in the Z direction along the up and down movement direction of the stirring head spindle. Move the stirring head in the XYZ direction of the friction stir welding equipment to a position above the working platform where there will be no impact for pre-starting. Adjust the starting movement speed to prevent the equipment from moving too fast and causing a collision. Observe the equipment operation status. Stop the operation when the equipment starts normally. Move the stirring needle on the XYZ axis of the friction stir welding equipment so that the tip of the stirring needle is located at the middle of the weld start position symmetrically, so that it contacts and presses down 0.1mm~0.2mm. Record the initial position of the aluminum alloy friction stir welding and zero the position of the friction stir welding equipment, including zeroing the X-axis, Y-axis, Z-axis and stirring head tilt angle. Set the path preset program according to the welding requirements of the welding component. Adjust the program to keep the X-axis and Y-axis stationary. Move the Z-axis 0.2~0.3mm higher than the workpiece. Start the friction stir welding equipment and observe the trajectory movement to ensure the correctness of the welding path. Place the stirring head in the initial position to prepare for actual welding.
[0008] Step (3): After determining the predetermined trajectory and the position of the stirring head, determine the welding parameters for aluminum alloy friction stir welding; use 6061-T6 aluminum alloy with dimensions of 200mm×180mm×6mm, the stirring head is a conical stirring pin with threads, the total length of the stirring head is 98mm, the length of the stirring pin is 2.5~3mm, and the diameter of the stirring head shoulder is 12mm; the stirring head speed is 800~1200rpm, the feed speed is 100~250mm / min, the stirring head tilt angle is 2°, and the pressing depth is 0.2~0.45mm. Select the above welding parameters to weld the aluminum plate and analyze the influence of different welding parameters on the welding effect of friction stir welding;
[0009] Step (4): Analyze the welding effect based on the aluminum plate and adjust the welding parameters; set the stirring head speed to 800 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, and set the stirring head to rotate forward and backward according to the predetermined trajectory. After welding, the aluminum plate has weld grooves, poor material flow, and material accumulation on the forward side; at 800 rpm, feed speed to 150 mm / min, and pressing depth to 0.3 mm, the aluminum plate has weld grooves, good material flow, and layered accumulation on the forward side; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.3 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation. At a speed of m / min and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects and good material flow, but flash was present on the retreating side. At a stirring head speed of 1000 rpm, a feed rate of 150 mm / min, and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects and good material flow, with good welding results. At a stirring head speed of 1000 rpm, a feed rate of 100 mm / min, and a pressing depth of 0.45 mm, the welded aluminum plate showed no defects and good material flow, but significant flash was present. Based on the performance of different welding parameters, the rotation speed affects material flow; the feed rate determines the residence time of the material in the weld zone, thus affecting material formation; the pressing depth determines the pressing force and effective weld thickness. Based on the welding results, a pressing depth of 0.4 mm resulted in a welded aluminum plate with no defects, good material flow, and good welding results.
[0010] Step (5): Clean the residual oxides on the friction stir welding head; During aluminum plate welding, the material flow will cause the stirring head to adhere to metal oxides, which will affect the life of the stirring head and the welding effect; For aluminum alloy welding, the interface between the stirring head and the aluminum plate generates instantaneous high temperature due to high-speed friction, which softens or even slightly melts the aluminum alloy substrate adhering to the surface of the stirring head, causing the outer aluminum oxide film to lose support and become brittle. At the same time, the shear force and centrifugal force generated by high-speed rotation peel off and throw off the softened aluminum substrate and the broken oxide film, thus cleaning the surface of the stirring head. Set the stirring head speed to 1000rpm~1500rpm. At rpm and an insertion depth of 0.4mm~0.45mm, hold the agitator in the aluminum plate for 2~3 seconds, then lift it up to achieve self-cleaning of the welding head. During aluminum-copper welding, the self-cleaning operation must be performed on a copper plate, not an aluminum plate. Aluminum has low hardness and easily softens and melts at high temperatures, failing to provide effective grinding. Furthermore, aluminum easily diffuses and adheres to the agitator, not only failing to remove existing oxides but also causing new aluminum adhesion, leading to cleaning failure. In other words, for cleaning agitators of the same metal, choose a plate of the same metal; for cleaning agitators of different metals, choose a plate with a higher melting point.
[0011] Compared with existing technologies, this invention brings significant positive effects: The aluminum alloy friction stir welding (FSM) section connection and weld head self-cleaning technology enables full-process operation of aluminum alloy FSM welding. The fixing method is determined based on the shape characteristics of the aluminum alloy component. Under normal operating conditions, the moving FSM allows for test welding with tool and trajectory settings. The mechanism of action and welding effect on welding quality is analyzed based on different welding parameters such as stirring head rotation speed, feed rate, stirring head tilt angle, and depth of penetration, leading to parameter optimization. The self-cleaning of the weld head is based on the principles of frictional heat softening and mechanical shearing, filling the gap in aluminum alloy FSM interface connection and weld head self-cleaning technology. This provides a technical method for improving the welding quality and extending the life of the weld head in aluminum alloy FSM welding. Attached Figure Description
[0012] Figure 1 This is a flowchart of the method for interface connection and self-cleaning of welding head in aluminum alloy friction stir welding;
[0013] Figure 2 This is a schematic diagram of aluminum alloy friction stir welding. Detailed Implementation
[0014] Embodiments of the present invention will be described with reference to the accompanying drawings, which will be further described below. Figure 1 and Figure 2 The specific embodiments of the present invention will be described in detail below.
[0015] like Figure 1 The diagram shows a flowchart of a method for interface bonding and self-cleaning of the welding head in aluminum alloy friction stir welding, including the following steps:
[0016] Step (1): Select the fixing method according to the structural shape and plate thickness of the aluminum alloy welded component. Use pressure blocks to compact the welding plate so that the aluminum alloy component is placed as close as possible to the center of the work platform and remains symmetrical. Use pressure blocks to compact the aluminum alloy welded component to ensure that it cannot move and that the welded aluminum alloy mother plate or component is flat, tight and does not warp.
[0017] Step (2): After fixing the aluminum alloy mother plate, move the stirring head in the X direction along the feeding direction of the stirring head, in the Y direction along the back and forth movement direction of the working platform, and in the Z direction along the up and down movement direction of the stirring head spindle. Move the stirring head in the XYZ direction of the friction stir welding equipment to a position above the working platform where there will be no impact for pre-starting. Adjust the starting movement speed to prevent the equipment from moving too fast and causing a collision. Observe the equipment operation status. Stop the operation when the equipment starts normally. Move the stirring needle on the XYZ axis of the friction stir welding equipment so that the tip of the stirring needle is located at the middle of the weld start position symmetrically, so that it contacts and presses down 0.1mm~0.2mm. Record the initial position of the aluminum alloy friction stir welding and zero the position of the friction stir welding equipment, including zeroing the X-axis, Y-axis, Z-axis and stirring head tilt angle. Set the path preset program according to the welding requirements of the welding component. Adjust the program to keep the X-axis and Y-axis stationary. Move the Z-axis 0.2~0.3mm higher than the workpiece. Start the friction stir welding equipment and observe the trajectory movement to ensure the correctness of the welding path. Place the stirring head in the initial position to prepare for actual welding.
[0018] Step (3): After determining the predetermined trajectory and the position of the stirring head, determine the welding parameters for aluminum alloy friction stir welding; such as Figure 2 The aluminum plate, measuring 200mm × 180mm × 6mm, is made of 6061-T6 aluminum alloy. The stirring head is a conical threaded stirring pin with a total length of 98mm, a stirring pin length of 2.5mm, and a stirring head shoulder diameter of 12mm. The stirring head rotation speed is 800~1200rpm, the feed rate is 100~250mm / min, the stirring head tilt angle is 2°, and the pressing depth is 0.2~0.45mm. The aluminum plate is welded using the above welding parameters, and the influence of different welding parameters on the welding effect of friction stir welding is analyzed.
[0019] Step (4): Analyze the welding effect based on the aluminum plate and adjust the welding parameters; set the stirring head speed to 800 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, and set the stirring head to rotate forward and backward according to the predetermined trajectory. After welding, the aluminum plate has weld grooves, poor material flow, and material accumulation on the forward side; at 800 rpm, feed speed to 150 mm / min, and pressing depth to 0.3 mm, the aluminum plate has weld grooves, good material flow, and layered accumulation on the forward side; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.3 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation; at 1000 rpm, feed speed to 100 mm / min, and pressing depth to 0.2 mm, the aluminum plate has smaller weld grooves, good material flow, and no material accumulation. At a speed of m / min and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects and good material flow, but flash was present on the retreating side. At a stirring head speed of 1000 rpm, a feed rate of 150 mm / min, and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects and good material flow, with good welding results. At a stirring head speed of 1000 rpm, a feed rate of 100 mm / min, and a pressing depth of 0.45 mm, the welded aluminum plate showed no defects and good material flow, but significant flash was present. Based on the performance of different welding parameters, the rotation speed affects material flow; the feed rate determines the residence time of the material in the weld zone, thus affecting material formation; the pressing depth determines the pressing force and effective weld thickness. Based on the welding results, a pressing depth of 0.4 mm resulted in a welded aluminum plate with no defects, good material flow, and good welding results.
[0020] Step (5): Clean the residual oxides on the friction stir welding head; During aluminum plate welding, the material flow will cause the stirring head to adhere to metal oxides, which will affect the life of the stirring head and the welding effect; For aluminum alloy welding, the interface between the stirring head and the aluminum plate generates instantaneous high temperature due to high-speed friction, which softens or even slightly melts the aluminum alloy substrate adhering to the surface of the stirring head, causing the outer aluminum oxide film to lose support and become brittle. At the same time, the shear force and centrifugal force generated by high-speed rotation peel off and throw off the softened aluminum substrate and the broken oxide film, thus cleaning the surface of the stirring head. Set the stirring head speed to 1000rpm~1500rpm. At rpm and an insertion depth of 0.4mm~0.45mm, hold the agitator in the aluminum plate for 2~3 seconds, then lift it up to achieve self-cleaning of the welding head. In aluminum-copper welding, the self-cleaning operation of the welding head must be performed on the copper plate, not the aluminum plate. Because aluminum has low hardness and is easily softened and melted at high temperatures, it cannot provide an effective grinding effect. In addition, aluminum and the agitator are prone to diffusion and adhesion, which not only fails to remove the original oxides but also causes new aluminum adhesion, resulting in the failure of the cleaning effect. That is, for cleaning agitators of the same metal, choose a metal plate of the same metal for cleaning, while for cleaning agitators of different metals, choose a metal plate with a higher melting point.
[0021] The above description is merely a preferred embodiment of the invention and does not constitute any limitation on the invention. Any modifications, alterations, or equivalent changes made to the above embodiments based on the essence of the invention shall still fall within the protection scope of the invention.
Claims
1. A method for interface bonding and self-cleaning of welding heads in aluminum alloy friction stir welding, characterized in that, Includes the following steps: Step (1): Select the fixing method according to the structural shape and plate thickness of the aluminum alloy welded component. The aluminum alloy component is placed in the center of the work platform and kept symmetrical. Use pressure blocks to compact it to ensure that the aluminum alloy welded component cannot move, and ensure that the welded aluminum alloy mother plate or component is flat, tight and does not warp. Step (2): After fixing the aluminum alloy mother plate, move the stirring head in the X direction along the feeding direction of the stirring head, in the Y direction along the back-and-forth movement direction of the working platform, and in the Z direction along the up-and-down movement direction of the stirring head spindle. Move the stirring head in the XYZ direction of the friction stir welding equipment to a position above the working platform where there will be no impact for pre-starting. Adjust the starting movement speed to prevent collision due to excessive speed. Stop the operation when the equipment starts normally. Move the stirring needle on the XYZ axis of the friction stir welding equipment to position the tip of the stirring needle at the symmetrical position in the middle of the weld start position, so that it contacts and presses down 0.1mm~0.2mm. Record the initial position of the aluminum alloy friction stir welding and zero the position of the friction stir welding equipment, including the X axis, Y axis, Z axis and the tilt angle of the stirring head. Pre-set the path according to the welding requirements of the welded component. Adjust the program to keep the X axis and Y axis stationary. Move the Z axis 0.2~0.3mm higher than the weldment. Start the friction stir welding equipment and observe the trajectory movement to ensure the correctness of the welding path. Place the stirring head in the initial position. Step (3): After determining the predetermined trajectory and the position of the stirring head, determine the welding parameters for aluminum alloy friction stir welding; for different aluminum alloy plate sizes, the stirring head adopts a conical stirring pin with threads, the total length of the stirring head is 98mm, the length of the stirring pin is 2.5~3mm, and the diameter of the stirring head shoulder is 12mm; the stirring head speed is 800~1200rpm, the feed speed is 100~250mm / min, the stirring head tilt angle is 2°, and the pressing depth is 0.2~0.45mm. Select the above welding parameters to weld the aluminum plate; Step (4): Analyze the welding effect based on the aluminum plate and adjust the welding parameters; when the stirring head speed is 800 rpm, the feed speed is 100 mm / min, and the pressing depth is 0.2 mm, the aluminum plate after welding has weld grooves, poor material flow, and material accumulation on the forward side; when the stirring head speed is 800 rpm, the feed speed is 150 mm / min, and the pressing depth is 0.3 mm, the aluminum plate after welding has weld grooves, the material flow is relatively good, and layered accumulation occurs on the forward side; when the stirring head speed is 1000 rpm, the feed speed is 100 mm / min, and the pressing depth is 0.3 mm, the aluminum plate after welding has smaller weld grooves, good material flow, and no material accumulation occurs. At a stirring head speed of 1000 rpm, a feed rate of 100 mm / min, and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects and good material flow, but flash was present on the retreating side. At a stirring head speed of 1000 rpm, a feed rate of 150 mm / min, and a pressing depth of 0.4 mm, the welded aluminum plate showed no defects, good material flow, and good welding effect. At a stirring head speed of 1000 rpm, a feed rate of 100 mm / min, and a pressing depth of 0.45 mm, the welded aluminum plate showed no defects and good material flow, but significant flash was present. Based on the performance of different welding parameters, a pressing depth of 0.4 mm resulted in a welded aluminum plate with no defects, good material flow, and good welding effect. Step (5): Clean the residual oxides on the friction stir welding head; During aluminum plate welding, the material flow will cause the stirring head to adhere to metal oxides, which will affect the life of the stirring head and the welding effect; For aluminum alloy welding, the interface between the stirring head and the aluminum plate generates instantaneous high temperature due to high-speed friction, which softens or even slightly melts the aluminum alloy substrate adhering to the surface of the stirring head, causing the outer aluminum oxide film to lose support and become brittle. At the same time, the shear force and centrifugal force generated by high-speed rotation peel off and throw off the softened aluminum substrate and the broken oxide film, thus cleaning the surface of the stirring head. Set the stirring head speed to 1000rpm~1500rpm. At rpm and an insertion depth of 0.4mm~0.45mm, hold the agitator in the aluminum plate for 2~3 seconds, then lift it up to achieve self-cleaning of the welding head. In aluminum-copper welding, the self-cleaning operation of the welding head must be performed on the copper plate, not the aluminum plate. Because aluminum has low hardness and is easily softened and melted at high temperatures, it cannot provide an effective grinding effect. In addition, aluminum and the agitator are prone to diffusion and adhesion, which not only fails to remove the original oxides but also causes new aluminum adhesion, resulting in the failure of the cleaning effect. That is, for cleaning agitators of the same metal, choose a metal plate of the same metal for cleaning, while for cleaning agitators of different metals, choose a metal plate with a higher melting point.