Friction welding method of aluminum alloy with ordered arrangement of carbon fibers to CFRP dissimilar materials

Abstract

The application provides an aluminum alloy and CFRP dissimilar material friction welding method with ordered arrangement of carbon fibers, and comprises the following steps: S1, workpiece pretreatment; S2, CFRP plate slotting treatment; S3, aluminum alloy plate and CFRP plate lap friction welding; and S4, welding ending and natural cooling. The application adopts a two-stage welding process, multiple directional pre-welding is first performed on the CFRP to realize preliminary orientation of the carbon fibers, and then the lap welding is used to lock the arrangement of the carbon fibers, so that the problems of disordered distribution and twisted fracture of the carbon fibers are solved from the root, stress concentration is eliminated, and the mechanical performance of the joint is improved. In the pre-welding stage, the temperature is uniformly controlled through the edge angle shearing action of the three-prism stirring needle or the needle-free flat shaft shoulder, the carbon fibers are guided to be directional, the resin degradation and fiber damage are avoided, and meanwhile, uniform micro concaves are formed on the surface of the CFRP, and the interface mechanical interlocking is strengthened.

Description

Technical Field

[0001] This invention relates to the field of friction stir welding technology, specifically to a method for friction welding dissimilar materials such as aluminum alloy with ordered carbon fiber arrangement and CFRP. Background Technology

[0002] Friction stir welding (FSW) technology relies on the mechanical stirring of the stirring pin and the frictional heat of the shaft shoulder to achieve the joining of dissimilar materials. Current methods use a single-shaped stirring head for direct welding, achieving interfacial bonding through the thermo-mechanical coupling effect generated by the rotational friction of the stirring head. Some studies pre-treat CFRP before welding it to aluminum alloys. First, the CFRP surface is plasma modified to remove the surface resin and roughen the surface, and then friction stir welding is used to achieve the connection with the aluminum alloy. The core is to enhance mechanical interlocking through surface modification.

[0003] Existing technologies have many shortcomings and deficiencies. In traditional single-stage friction stir welding, the stirring action of a single stirring head is mostly random disturbance. The carbon fibers in CFRP are prone to twisting, breaking, and disordered distribution due to mechanical impact and resin flow, which cannot form a directional reinforcement effect. As a result, the joint strength is affected by stress concentration caused by fiber disorder. There is a lack of targeted pretreatment. The wettability of the aluminum alloy and CFRP interface is poor and the mechanical interlocking is insufficient, which easily leads to porosity defects. The pretreatment only focuses on surface roughening and does not optimize the internal fiber state of CFRP. After welding, there are still weak bonding areas between the fibers and the aluminum alloy and resin matrix, resulting in poor fatigue resistance of the joint. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a friction welding method for aluminum alloys with ordered carbon fiber arrangement and CFRP dissimilar materials, thus solving the problems mentioned in the background art.

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

[0006] A method for friction welding dissimilar materials, namely aluminum alloy with ordered carbon fiber arrangement and CFRP, comprising the following steps:

[0007] S1. Workpiece pretreatment: Prepare aluminum alloy plates and CFRP plates with matching dimensions; remove oil and oxide layers from the surface of the aluminum alloy plates, and grind off the surface resin of the CFRP plates.

[0008] S2. CFRP plate grooving treatment: S2.1. Fix the pretreated CFRP plate on a special tooling to ensure that the area to be welded is flat and without displacement; S2.2. Assemble the pretreatment stirring head at the bottom of the flat shaft shoulder and set the friction stir welding parameters according to the workpiece thickness; S2.3. Perform multiple unidirectional welding on the CFRP plate. The pretreatment stirring head guides the carbon fibers of the CFRP plate to initially arrange in an orderly manner, so that micro-grooves are formed on the surface of the CFRP plate.

[0009] S3. Friction welding of aluminum alloy plate and CFRP plate: S3.1. Fix the aluminum alloy plate and CFRP plate together in a special tooling; S3.2. Replace the pretreatment stirring head with the lap stirring head, and reset the friction welding parameters according to the overall thickness of the workpiece; S3.3. Rotate and lower the lap stirring head onto the aluminum alloy plate, allowing the aluminum alloy to plastically flow and fill the micro-grooves on the surface of the CFRP plate, forming a mechanically interlocked friction weld, while constraining the carbon fibers to maintain an orderly arrangement in the interface area;

[0010] S4. Welding finishing and natural cooling.

[0011] Furthermore, in S2.2, the pretreatment stirring head is a triangular frustum stirring pin, and in S2.3, the number of unidirectional welding operations on the CFRP plate is greater than 1.

[0012] Furthermore, the triangular frustum stirring pin has a face length of 5-8mm, a height of 3-5mm, and a shoulder diameter of 10-15mm; the specific parameters for friction stir welding are: downward pressure of 0.1-0.3mm, rotation speed of 1600-1800r / min, and welding speed of 50-100mm / min.

[0013] Furthermore, in S2.2, the pretreatment stirring head is a needle-free flat-shoulder stirring head, and in S2.3, the number of unidirectional welding operations on the CFRP plate is greater than 3.

[0014] Furthermore, the shoulder diameter of the needleless flat-shoulder stirring head is 10-15mm; the specific parameters for friction stir welding are: downward pressure 0.1-0.3mm, rotation speed 1600-1800r / min, and welding speed 50-100mm / min.

[0015] Furthermore, S2.3 also includes: after each welding operation, promptly clean the residual resin on the surface of the pretreatment stirring head to avoid resin residue affecting the welding effect of the next pass; allow the workpiece to cool naturally for 6-10 minutes before proceeding to the next round of welding.

[0016] Furthermore, in S3.2, the lap stirring head is a conical stirring head with a diameter of 8-12mm, a cone angle of 60°-90°, and a shoulder diameter of 15-18mm; the specific parameters for friction stir welding are: rotation speed of 2000-3000r / min, welding speed of 80-150mm / min, and downward pressure of 0.5-1.0mm.

[0017] Furthermore, the welding completion and natural cooling process specifically involves the following steps: after the welding reaches the preset endpoint, the overlapping stirring head remains rotating for 3-5 seconds to ensure that the carbon fiber, aluminum alloy, and CFRP resin achieve sufficient interfacial bonding; subsequently, the stirring head stops rotating and slowly rises, keeping the workpiece stationary and allowing it to cool naturally.

[0018] Furthermore, the special tooling includes a base, a enclosure frame is installed on the top surface of the base, a first through hole is opened on the back of the enclosure frame, a second through hole is opened on the front side, the second through hole is located above the first through hole, a first movable plate slides through the interior of the first through hole, and a second movable plate slides through the interior of the second through hole; a chip removal groove is opened on one side of the enclosure frame.

[0019] In S2, the first movable plate presses against the CFRP plate, and the second movable plate presses down from the top.

[0020] In S3, the second movable plate presses against the CFRP plate and lifts the aluminum alloy plate, while the second movable plate presses down from the top and presses against the aluminum alloy plate.

[0021] Furthermore, the base is symmetrically provided with a first support seat and a second support seat, and a first movable block is vertically provided on the outer bottom surface of the first movable plate. The first movable block has an internal thread through which a first adjusting screw passes. The inner end of the first adjusting screw is rotatably connected to the base, and the first movable block is slidably installed on the top of the first support seat.

[0022] The second movable block is vertically provided on the outer bottom surface of the second movable plate. The second movable block has a second adjusting screw threaded through its internal thread. The inner end of the second adjusting screw is rotatably connected to the base. The first movable block is slidably installed on the top of the second support base.

[0023] This invention provides a method for friction welding dissimilar materials, such as aluminum alloy with ordered carbon fiber arrangement and CFRP (carbon fiber reinforced polymer). Compared with existing technologies, it has the following advantages:

[0024] 1. This invention employs a two-stage welding process. First, multiple directional pre-weldings are performed on the CFRP to achieve the initial orientation of the carbon fibers. Then, lap welding is used to lock the arrangement of the carbon fibers, thereby solving the problems of disordered distribution, twisting and breakage of carbon fibers from the root, eliminating stress concentration, and improving the mechanical properties of the joint.

[0025] 2. During the pre-welding stage, the shearing action of the triangular frustum stirring pin or the uniform temperature control of the needleless flat shoulder guides the orientation of carbon fibers and avoids resin degradation and fiber damage. At the same time, it forms uniform micro-pits on the CFRP surface, which strengthens the mechanical interlocking of the interface.

[0026] 3. During the lap welding stage, the conical stirring head is used to roll the edge effect so that the aluminum alloy can plastically flow and fill the pit. Combined with the backing plate support, the welding fit is guaranteed, the carbon fiber is further constrained to arrange in an orderly manner, the interface bonding stability is improved, and defects such as porosity, incomplete welding and incomplete penetration are avoided. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 A schematic diagram of the overall workflow of the present invention is shown;

[0029] Figure 2 A schematic diagram of the triangular frustum stirring needle mounting structure of the present invention is shown;

[0030] Figure 3 A schematic diagram of the mounting structure of the needleless flat-shaft shoulder stirring head of the present invention is shown;

[0031] Figure 4 A schematic diagram of the pre-friction welding structure of the CFRP plate of the present invention is shown;

[0032] Figure 5 A schematic diagram of the microgroove structure of the CFRP plate of the present invention is shown;

[0033] Figure 6 A schematic diagram of the overlapping structure of the CFRP plate and the aluminum alloy plate of the present invention is shown;

[0034] Figure 7 A schematic diagram of the welding structure between the CFRP plate and the aluminum alloy plate of the present invention is shown.

[0035] Figure 8 A schematic diagram of the enclosure frame structure of the present invention is shown;

[0036] Figure 9 This diagram shows the CFRP board of the present invention in a special tooling structure;

[0037] Figure 10 This diagram shows a schematic of the CFRP plate and aluminum alloy plate of the present invention in a special tooling structure;

[0038] As shown in the figure:

[0039] 1. Flat shoulder; 21. Triangular frustum stirring needle; 22. Needleless flat shoulder stirring head.

[0040] 3. CFRP board, 31. Microgrooves,

[0041] 4. First movable plate; 41. First movable block; 42. First adjusting screw; 43. First support base.

[0042] 5. Aluminum alloy plate, 51. Friction weld.

[0043] 6. Fence frame; 61. First perforation; 62. Second perforation; 63. Chip removal groove.

[0044] 7. Base

[0045] 8. Second movable plate; 81. Second movable block; 82. Second adjusting screw; 83. Second support base. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0047] Example 1

[0048] To address the key technical challenges of existing aluminum alloy-CFRP dissimilar material welding technology, such as the tendency of carbon fibers to agglomerate, break, and exhibit disordered arrangement, thereby overcoming the resulting problems of insufficient joint mechanical properties, poor connection stability, and frequent defects such as porosity and cracks, this paper proposes a friction welding method for aluminum alloy-CFRP dissimilar materials. This method employs multiple welding processes using, but is not limited to, a truncated triangular stirring head to achieve initial orientation control of the carbon fibers. Then, a conical stirring head is used for lap welding of the aluminum alloy-CFRP joint, achieving an ordered arrangement of the carbon fibers. This fundamentally improves the strength and connection stability of the welded joint, meeting the high precision and high reliability requirements for dissimilar material connections. The following friction welding method for aluminum alloy and CFRP dissimilar materials with ordered carbon fiber arrangement is presented:

[0049] Combination Figure 1 , Figure 2 , Figures 4-7 As shown, the present invention provides a method for friction welding dissimilar materials, namely aluminum alloy with ordered carbon fiber arrangement and CFRP.

[0050] S1. Workpiece pretreatment:

[0051] Prepare matching aluminum alloy plate 5 and CFRP plate 3; select plates with a thickness of 2-3mm to suit the heat-mechanical action depth of friction stir welding, avoiding incomplete welding due to excessive thickness and easy burning due to excessive thinness; ensure uniform plate dimensions to guarantee a tight fit during subsequent lap welding and prevent gaps from causing incomplete welds or penetration.

[0052] Remove oil and oxide layers from the surface of aluminum alloy plate 5, and grind away the surface resin of CFRP plate 3; removing oil and oxide layers from the aluminum alloy surface eliminates interface bonding barriers and improves the connection reliability between aluminum alloy and CFRP; grinding away the surface resin of CFRP loosens the carbon fiber bundles into fine bundles, without agglomeration and retaining rigidity, breaking the fiber binding and laying the structural foundation for subsequent carbon fiber directional alignment; keeping the carbon fibers in a loose and non-directional state avoids initial agglomeration that leads to stress concentration during subsequent welding.

[0053] S2, CFRP board 3 slotting treatment:

[0054] S2.1 Fix the pre-treated CFRP board 3 onto a special fixture to ensure that the area to be welded is flat and without displacement; ensure that the CFRP area to be welded is flat and without displacement to prevent the board from shifting during welding and causing the carbon fiber arrangement to become disordered; provide stable fixture support for CFRP pre-welding to ensure that the direction of multiple pre-welding passes is consistent and the fiber orientation is uniform.

[0055] S2.2. A pre-treated stirring head is assembled at the bottom of the flat shoulder 1, and the friction stir welding parameters are set according to the workpiece thickness. In S2.2, the pre-treated stirring head is a truncated triangular stirring pin 21. In S2.3, the number of unidirectional welding operations on the CFRP plate 3 is greater than 1. The truncated triangular stirring pin 21 has a face side length of 5-8mm, a height of 3-5mm, and a shoulder diameter of 10-15mm. The specific friction stir welding parameters are: pressure 0.1-0.3mm, rotation speed 1600-1800r / min, and welding speed 50-100mm / min. The combination of the truncated triangular stirring pin 21 and the flat shoulder provides structural support for subsequent angular shearing and orientation of carbon fibers and uniform heat input. The pressure, rotation speed, and welding speed are set according to the plate thickness to avoid excessive heat input leading to resin degradation and fiber damage, or insufficient heat input preventing fiber loosening and orientation.

[0056] S2.3. Perform multiple unidirectional welding on the CFRP plate 3. The pre-treatment stirring head guides the carbon fibers of the CFRP plate 3 to initially arrange in an orderly manner, forming rectangular microgrooves 31 in the area to be joined on the surface of the CFRP plate 3. After each welding, clean the residual resin on the surface of the pre-treatment stirring head in time to avoid the resin residue affecting the welding effect of the next welding. Allow the workpiece to cool naturally for 6-10 minutes before performing the next round of welding. Multi-pass unidirectional welding utilizes the shearing effect of the triangular truncated pyramid to force the carbon fibers to initially arrange in an orderly manner along the welding direction, solving the problem of random fiber twisting and breakage. Cool to room temperature for 6-10 minutes after each welding pass to avoid resin ablation and carbon fiber embrittlement caused by continuous welding heat accumulation. Clean the resin residue on the stirring pin to prevent resin adhesion from interfering with the fiber orientation effect of the next pass. Soften the resin on the CFRP surface and form uniform microgrooves 31, providing a structural basis for the subsequent plastic flow filling of aluminum alloy and the formation of strong mechanical interlocking.

[0057] S3, Aluminum alloy plate 5 and CFRP plate 3 lap friction welding:

[0058] S3.1. The aluminum alloy plate 5 and the CFRP plate 3 are overlapped and fixed in the special tooling.

[0059] S3.2 Replace the pretreatment stirring head with a lap stirring head, and reset the friction stir welding parameters according to the overall thickness of the workpiece; the lap stirring head is a conical stirring head with a diameter of 8-12mm, a cone angle of 60°-90°, and a shoulder diameter of 15-18mm; the specific friction stir welding parameters are: rotation speed 2000-3000r / min, welding speed 80-150mm / min, and downward pressure 0.5-1.0mm; the conical stirring head has a curling effect, which can drive the aluminum alloy to fully plastically flow, adapting to the need for filling micro-dimples; a higher rotation speed and downward pressure are set to match the lap welding conditions to ensure that the aluminum alloy is fully softened and flowed, while not damaging the oriented carbon fibers; the special cone angle and shoulder size ensure uniform welding pressure distribution and more stable interface bonding;

[0060] S3.3 The overlapping stirring head rotates and descends onto the aluminum alloy plate 5, causing the aluminum alloy to plastically flow and fill the micro-grooves 31 on the surface of the CFRP plate 3, forming a mechanically interlocked friction weld 51. At the same time, it constrains the carbon fibers to maintain an orderly arrangement in the interface area. The plastic flow of the aluminum alloy fills the micro-grooves 31 on the CFRP surface, forming a high-strength mechanically interlocked structure, which greatly improves the interfacial bonding force. The plastic aluminum alloy forms a rigid constraint on the carbon fibers at the interface, further calibrating and locking the orderly arrangement of the carbon fibers, avoiding fiber rebound disorder. It eliminates defects such as poor wettability, porosity, and weak bonding areas at the interface between aluminum alloy and CFRP, reducing stress concentration at the joint from the root cause.

[0061] S4. Welding completion and natural cooling:

[0062] After the welding reaches the preset endpoint, the lap stirring head remains rotating for 3-5 seconds to ensure that the carbon fiber, aluminum alloy, and CFRP resin complete a full interfacial bond. Subsequently, the stirring head stops rotating and slowly rises, keeping the workpiece stationary and allowing it to cool naturally.

[0063] Example 2

[0064] Combination Figure 1 , Figures 3-7 As shown, the present invention provides a method for friction welding dissimilar materials, namely aluminum alloy with ordered carbon fiber arrangement and CFRP.

[0065] S1. Workpiece pretreatment:

[0066] Prepare aluminum alloy sheet 5 and CFRP sheet 3 with matching dimensions;

[0067] Remove oil and oxide layer from the surface of aluminum alloy plate 5, and grind off the surface resin of CFRP plate 3;

[0068] S2, CFRP board 3 slotting treatment:

[0069] S2.1 Fix the pre-treated CFRP board 3 onto a special tooling to ensure that the area to be welded is flat and without displacement;

[0070] S2.2. Assemble a pre-treated stirring head at the bottom of the flat shoulder and set the friction stir welding parameters according to the workpiece thickness; the pre-treated stirring head is a needleless flat shoulder stirring head 22. In S2.3, the number of unidirectional welding operations on the CFRP plate 3 is greater than 3 times; the shoulder diameter of the needleless flat shoulder stirring head 22 is 10-15mm; the specific friction stir welding parameters are: downward pressure 0.1-0.3mm, rotation speed 1600-1800r / min, welding speed 50-100mm / min;

[0071] S2.3. Perform multiple unidirectional welding on CFRP plate 3. The pretreatment stirring head guides the carbon fibers of CFRP plate 3 to initially arrange in an orderly manner, so that micro-grooves 31 are formed on the surface of CFRP plate 3. After each welding, clean the residual resin on the surface of the pretreatment stirring head in time to avoid the resin residue affecting the welding effect of the next welding. Let the workpiece cool naturally for 6-10 minutes before performing the next round of welding.

[0072] S3, Aluminum alloy plate 5 and CFRP plate 3 lap friction welding:

[0073] S3.1. The aluminum alloy plate 5 and the CFRP plate 3 are overlapped and fixed in the special tooling.

[0074] S3.2 Replace the pretreatment stirring head with an overlapping stirring head, and reset the friction stir welding parameters according to the overall thickness of the workpiece; the overlapping stirring head is a conical stirring head with a diameter of 8-12mm, a cone angle of 60°-90°, and a shoulder diameter of 15-18mm; the specific friction stir welding parameters are: rotation speed 2000-3000r / min, welding speed 80-150mm / min, and downward pressure 0.5-1.0mm;

[0075] S3.3 The overlapping stirring head rotates and descends to work on the aluminum alloy plate 5, so that the aluminum alloy plastically flows and fills the micro-grooves 31 on the surface of the CFRP plate 3, forming a mechanically interlocked friction weld 51, while constraining the carbon fibers to maintain an orderly arrangement in the interface area.

[0076] S4. Welding completion and natural cooling:

[0077] After the welding reaches the preset endpoint, the lap stirring head remains rotating for 3-5 seconds to ensure that the carbon fiber, aluminum alloy, and CFRP resin complete a full interfacial bond. Subsequently, the stirring head stops rotating and slowly rises, keeping the workpiece stationary and allowing it to cool naturally.

[0078] Example 3

[0079] like Figures 8-10 As shown, the special tooling includes a base 7, a enclosure frame 6 is installed on the top surface of the base 7, a first through hole 61 is opened on the back of the enclosure frame 6, a second through hole 62 is opened on the front side, the second through hole 62 is located above the first through hole 61, the first movable plate 4 slides through the interior of the first through hole 61, and the second movable plate 8 slides through the interior of the second through hole 62; a chip removal groove 63 is opened on one side of the enclosure frame 6;

[0080] In S2, the first movable plate 4 presses against the CFRP plate 3, and the second movable plate 8 presses down from the top.

[0081] In S3, the second movable plate 8 presses against the CFRP plate 3 and lifts the aluminum alloy plate 5, and the second movable plate 8 presses down from the top and presses against the aluminum alloy plate 5.

[0082] The base 7 is symmetrically provided with a first support seat 43 and a second support seat 83. The outer bottom surface of the first movable plate 4 is vertically provided with a first movable block 41. The first movable block 41 has a first adjusting screw 42 threaded through its internal thread. The inner end of the first adjusting screw 42 is rotatably connected to the base 7. The first movable block 41 is slidably installed on the top of the first support seat 43.

[0083] The second movable plate 8 has a second movable block 81 vertically arranged on the outer bottom surface. The second movable block 81 has a second adjusting screw 82 threaded through its internal thread. The inner end of the second adjusting screw 82 is rotatably connected to the base 7. The first movable block 41 is slidably installed on the top of the second support base 83.

[0084] In the above scheme, the positioning of CFRP plate 3 and aluminum alloy plate 5 can be achieved by the first movable plate 4 and the second movable plate 8 arranged symmetrically and staggeredly. The operation is simple and the positioning effect is good. By rotating the adjusting screw, the driving movable block moves along the support base. In this way, the movable block can drive the movable plate to move and achieve extrusion positioning. When cleaning up waste, the operator can use a brush to clean up the waste on the plate from the chip discharge groove 63.

[0085] It should be noted that, in this document, relational terms such as "first" and "second" are used only 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.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for friction welding dissimilar materials, namely aluminum alloy with ordered carbon fiber arrangement and CFRP, characterized in that, The welding method includes the following steps: S1. Workpiece pretreatment: Prepare aluminum alloy sheets and CFRP sheets of matching dimensions; Remove oil and oxide layers from the surface of the aluminum alloy sheet, and grind away the surface resin of the CFRP sheet; S2. Grooving treatment of CFRP board: S2.1 Fix the pretreated CFRP board onto a special fixture to ensure that the area to be welded is flat and without displacement; S2.

2. Assemble a pre-treated stirring head at the bottom of the flat shoulder and set the friction stir welding parameters according to the workpiece thickness; S2.

3. Perform multiple unidirectional welding on the CFRP plate. The pretreatment stirring head guides the carbon fibers of the CFRP plate to initially arrange in an orderly manner, so that micro-grooves are formed on the surface of the CFRP plate. S3. Friction welding of aluminum alloy plate and CFRP plate: S3.

1. Secure the aluminum alloy plate and CFRP plate together in a special tooling. S3.2 Replace the pretreatment stirring head with an overlapping stirring head, and reset the friction stir welding parameters according to the overall thickness of the workpiece; S3.3 The overlapping stirring head rotates and descends to work on the aluminum alloy plate, so that the aluminum alloy plastically flows and fills the micro-grooves on the surface of the CFRP plate, forming a mechanically interlocked friction weld, while constraining the carbon fibers to maintain an orderly arrangement in the interface area. S4. Welding finishing and natural cooling.

2. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: In S2.2, the pretreatment stirring head is a triangular frustum stirring pin, and in S2.3, the number of unidirectional welding operations on the CFRP plate is greater than 1.

3. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 2, characterized in that: The triangular frustum stirring pin has a face side length of 5-8mm, a height of 3-5mm, and a shoulder diameter of 10-15mm. The specific parameters for friction stir welding are: downward pressure of 0.1-0.3mm, rotation speed of 1600-1800r / min, and welding speed of 50-100mm / min.

4. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: In S2.2, the pretreatment stirring head is a needle-free flat-shoulder stirring head. In S2.3, the number of unidirectional welding operations on the CFRP plate is greater than 3.

5. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 4, characterized in that: The shoulder diameter of the needleless flat-shoulder stirring head is 10-15mm; the specific parameters for friction stir welding are: downward pressure 0.1-0.3mm, rotation speed 1600-1800r / min, and welding speed 50-100mm / min.

6. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: S2.3 also includes: after each welding is completed, promptly clean the resin residue on the surface of the pretreatment stirring head to avoid resin residue affecting the welding effect of the next welding pass; wait for the workpiece to cool naturally for 6-10 minutes before proceeding to the next round of welding.

7. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: In S3.2, the lap stirring head is a conical stirring head with a diameter of 8-12mm, a cone angle of 60°-90°, and a shoulder diameter of 15-18mm; the specific parameters for friction stir welding are: rotation speed of 2000-3000r / min, welding speed of 80-150mm / min, and downward pressure of 0.5-1.0mm.

8. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: The welding completion and natural cooling process is as follows: after the welding reaches the preset endpoint, the overlapping stirring head is kept rotating for 3-5 seconds to ensure that the carbon fiber, aluminum alloy, and CFRP resin complete a full interfacial bond; then, the stirring head stops rotating and slowly rises to keep the workpiece stationary and allow it to cool naturally.

9. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 1, characterized in that: The special tooling includes a base, a enclosure frame is installed on the top surface of the base, a first through hole is opened on the back of the enclosure frame, a second through hole is opened on the front side, the second through hole is located above the first through hole, a first movable plate slides through the inside of the first through hole, and a second movable plate slides through the inside of the second through hole; a chip removal groove is opened on one side of the enclosure frame. In S2, the first movable plate presses against the CFRP plate, and the second movable plate presses down from the top. In S3, the second movable plate presses against the CFRP plate and lifts the aluminum alloy plate, while the second movable plate presses down from the top and presses against the aluminum alloy plate.

10. The friction welding method for aluminum alloy with ordered carbon fiber arrangement and CFRP dissimilar materials according to claim 9, characterized in that: The base is symmetrically provided with a first support seat and a second support seat. A first movable block is vertically provided on the outer bottom surface of the first movable plate. A first adjusting screw is threaded through the inner thread of the first movable block. The inner end of the first adjusting screw is rotatably connected to the base. The first movable block is slidably installed on the top of the first support seat. The second movable block is vertically provided on the outer bottom surface of the second movable plate. The second movable block has a second adjusting screw threaded through its internal thread. The inner end of the second adjusting screw is rotatably connected to the base. The first movable block is slidably installed on the top of the second support base.

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