Friction stir overlap welding tool and method for realizing high-speed vertical flow

Abstract

The invention belongs to the technical field of welding, and particularly relates to a friction stir lap welding tool and method for achieving high-speed vertical flow, the welding tool comprises a shaft shoulder and conical vortex-shaped needles, and the conical vortex-shaped needles which are concentric with the end face of the shaft shoulder, are arranged in the circumferential direction and do not make contact with one another are arranged on the end face of the shaft shoulder; a plurality of spiral grooves are formed in gaps, corresponding to the tops of the conical vortex-shaped needles, in the end face of the shaft shoulder, a plurality of large-lead-angle threads are arranged on the side faces of the conical vortex-shaped needles, high-speed vertical flow of materials on the inner sides of the needles is facilitated through the design of the multi-spiral shaft shoulder and the conical multi-vortex-shaped needles, and high-speed vertical flow of materials on the outer sides of the needles is facilitated through the design of the large-lead-angle threads. The welding tool is installed on a friction stir welding machine, friction stir lap welding is conducted on two plates of the same kind or different kinds, the conical vortex-shaped needle of the stirring tool can be inserted into a lower plate in a non-pricking mode or a micro-pricking mode or a large-pricking mode, and high-quality welding joints can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a friction stir lap welding tool and method for realizing high-speed vertical flow. Background Art

[0002] Lap joints are an important joint form for aluminum alloy structures such as aircraft fuselages, rocket fairings, and automobile chassis, and welding is a common connection process for manufacturing lap joints. At present, the demand for metal lap joints in the fields of aerospace, vehicles, and ships is increasing. However, metal materials are prone to problems such as poor weldability, large welding tool wear, and low joint strength during welding. In particular, the large physical and chemical property differences between dissimilar materials (such as aluminum / steel composite structures) make the welding problems more obvious. At the same time, the softening phenomenon of the material after welding makes the weld core and its surrounding area a weak area with lower strength than the parent material, and the degree of softening increases with the increase of welding temperature. Friction stir lap welding (FSLW) has the advantages of high strength, low energy consumption, and no pollution in material welding due to its low welding temperature, which has great advantages over fusion welding. However, how to achieve the manufacture of high-performance (including high-load-bearing) joints while reducing welding tool wear is the key to expanding the application of this technology in aviation, aerospace and other fields.

[0003] Chinese invention patent CN114406439A discloses a claw-type rivet and a friction stir riveting method suitable for friction stir riveting. This method can effectively reduce the difficulty of rivet deformation, improve the mechanical self-locking strength of rivets, and guide the flow of plastic metal through the newly designed claw-type rivet. However, this method is only applicable to friction stir riveting, and does not mention its applicability in friction stir lap welding; at the same time, the addition of rivets will increase the weight of structural parts, which is not conducive to the lightweight design requirements of the overall structure.

[0004] Chinese patent CN113500285A discloses a friction stir welding joint for dissimilar metal materials and a method for preparing and improving the strength of the joint. The method uses a shoulder with a concave angle of 5° to 10° and a conical threaded stirring needle at the front end of the shoulder for welding, and the stirring head forms an angle of 2° to 3° with the normal line of the test plate during the welding process. This method can form a better hook-shaped locking structure for friction stir lap welding of magnesium alloy and steel, thereby effectively improving the quality of the joint. However, during the implementation of this method, the stirring needle needs to go deep into the lower plate, which will cause serious wear of the stirring head and greatly shorten the service life of the stirring head.

[0005] Chinese patent CN113020776A discloses a stirring head and welding method for metal and thermoplastic polymer welding. The stirring head is characterized by its concave shoulder and inverted tower-shaped stirring needle with a multi-stage flow-blocking truncated cone structure. The welding method is to complete the friction stir lap welding by heating the upper surface of the weld with a resistive auxiliary heating strip on both sides. The auxiliary heat source can provide the welding plate with the effect of preheating before welding and slow cooling after welding. This method has the effect of eliminating internal defects, optimizing the interface structure, and improving the quality of heterogeneous joints for the friction stir lap welding joints of metal and thermoplastic polymers to a certain extent. However, the user objects of this method have certain pertinence. In addition, stricter resistance auxiliary heating temperature control is required during the welding process, and the operation is cumbersome. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a stir friction lap welding tool and method for realizing high-speed vertical flow, and designs a "hollow" large-angle threaded conical multi-vortex needle, which can realize the downward high-speed vertical flow of materials inside and outside the needle, strongly impact and break the lap interface on a large scale, so that the interface changes from the straight and continuous distribution before welding to a complex structure with a wide discontinuous area and a continuous part that is bent downward on the retreating side, thereby improving the forming quality and bearing capacity of the lap welding head. At the same time, the gaps between the multi-vortex needles allow the outflow of materials in the lower and middle parts of the stirring zone to converge into the hollow area, which is conducive to the material better filling the cavity formed by the forward movement of the vortex needle, thereby realizing welding with a large ratio of vortex needle diameter to plate thickness.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A stir friction lap welding tool for realizing high-speed vertical flow comprises a shaft shoulder and a conical vortex needle. A plurality of conical vortex needles are arranged circumferentially and do not contact each other, which are concentric with the shaft shoulder end face. A plurality of spiral grooves are provided in the gaps corresponding to the tops of the plurality of conical vortex needles on the shaft shoulder end face. A plurality of large-angle threads are provided on the side faces of the conical vortex needles.

[0009] The end of the spiral groove is close to the starting end of the large lead angle thread. The rotation direction of the large lead angle thread needs to match the rotation direction of the shaft shoulder. When the rotation direction of the shaft shoulder is counterclockwise, the large lead angle thread is right-handed; when the rotation direction of the shaft shoulder is clockwise, the large lead angle thread is left-handed. The top of the conical vortex needle is arc-shaped, and the tail is "wavy" or "straight".

[0010] The diameter of the shaft shoulder is 10mm≤Φ1≤20mm; the end face of the shaft shoulder is provided with n spiral grooves, n≥2, and the width of the spiral groove is Φ1 / 10≤W1≤Φ1 / 5.

[0011] The conical vortex needles are provided with m, m≥2, and the angle γ between adjacent conical vortex needles is 20°~60°; the length of the conical vortex needle is L=(0.5~1.5)×W1, the outer diameter of the top arc of the conical vortex needle is Φ2=Φ1 / 3, the outer diameter of the bottom arc of the top of the conical vortex needle is Φ3=2 / 3×Φ2, the longitudinal section width of the conical vortex needle is W2=2 / 3×Φ3, W3=4 / 5×W2; the transverse section width of the conical vortex needle is W4=2×W1, W5=4 / 5×W4; the cone angle α corresponding to the transverse section of the conical vortex needle is 25°~45°.

[0012] The large lead angle threads are provided with k numbers, k≥2, the width W6 of the large lead angle threads is equal to the depth of 0.6 mm to 2.2 mm, and the inclination angle β is equal to 45° to 70°.

[0013] A friction stir lap welding method for realizing high-speed vertical flow comprises the following steps:

[0014] Step 1: Select a welding tool with a suitable vortex needle length according to the plate thickness and overlap area of ​​the upper plate and the lower plate;

[0015] Step 2: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine;

[0016] Step 3: The welding tool is installed on the main shaft of the friction stir welding machine, the welding tool rotates at a speed of 600rpm≤ω≤1500rpm, and penetrates into the upper plate and the lower plate to be welded at a speed of 0.1mm / min~3mm / min at the welding starting position;

[0017] Step 4: When the conical vortex needle of the welding tool reaches the predetermined penetration depth and the shoulder of the welding tool penetrates into the upper plate by 0.1 to 0.5 mm, the welding tool stops penetrating and continues to rotate for 2 to 3 minutes;

[0018] Step 5: The welding tool advances at a rotation welding ratio of 20 to 100 to promote the upper and lower plate materials to flow downward and upward violently respectively to form a full metallurgical bond;

[0019] Step 6: After reaching the end point of the weld, retract the welding tool and the entire welding process is completed.

[0020] The upper plate is made of a low melting point metal, and the lower plate is made of a low melting point metal or a high melting point metal.

[0021] The thickness of the upper plate is 1.0 mm to 2.0 mm, and the thickness of the lower plate is 2.0 mm to 4.0 mm.

[0022] The conical vortex needle can be used in friction stir butt welding, and the number of large lead angle threads on the side of the vortex needle k=0.

[0023] Beneficial effects of the present invention:

[0024] 1. The welding tool designed in the present invention consists of two parts: a multi-spiral groove shoulder and a tapered multi-vortex needle with a large lead angle thread. The design of the multi-spiral shoulder and the tapered multi-vortex needle helps the material on the inner side of the needle to achieve high-speed vertical flow, and the design of the large lead angle thread helps the material on the outer side of the needle to achieve high-speed vertical flow; the variable cross-section design of the tail of the vortex needle can further accelerate the cohesion of the material, promote the convergence of the material to the center of the vortex needle, and enhance the impact effect of the material on the overlapping interface.

[0025] 2. For the same or different low-melting-point alloy materials (aluminum alloy, magnesium alloy, etc.), the vortex needle can be slightly or not penetrated into the lower plate to strongly impact and break the lap interface on a large scale, so that the interface changes from a straight and continuous distribution before welding to a complex structure with a wide discontinuous area and a continuous part that is bent downward on the retreating side, thereby improving the bearing capacity of the lap weld. When the present invention uses a method of not penetrating the lower plate during the stir friction lap welding process of the upper plate being a low-melting-point material (such as aluminum, etc.) and the lower plate being a high-melting-point material (such as steel, etc.), a good metallurgical bonding of the lap interface below the needle can be achieved, and even mechanical interlocking can occur, thereby obtaining a high-strength weld joint.

[0026] 4. The present invention also has significant advantages in the case where the vortex needle penetrates deeply into the lower plate during the friction stir lap welding process. The vortex needle penetrates deeply into the lower plate, which can cause the material around the vortex needle to gather below the tip of the vortex needle and form a gathering area; the "hollow" design formed by multiple vortex needles is conducive to weakening the upward flow trend of the material outside the vortex needle, weakening the effect of the gathering area located on the lower plate on the lap interface, and reducing the upward bending height of the hook-shaped defect, thereby obtaining a high-quality welding joint.

[0027] 5. The large-angle threaded tapered multi-vortex needle designed by the present invention is also suitable for stir friction butt welding. During the welding process, the high-speed vertical flow and material aggregation characteristics inside and outside the vortex needle can effectively enhance the impact effect of the aggregated area material on the lower material of the welding plate, eliminate the incomplete penetration defect of the weld, and thus obtain a high-quality butt joint.

[0028] 6. The gaps between the multi-vortex needles allow the material to flow out of the hollow area in the lower part of the stirring zone, which is conducive to the material better filling the cavity formed by the forward movement of the vortex needle. Therefore, compared with the solid design of the traditional stirring needle, the "hollow" design formed by the multi-vortex needle of the present application can achieve a larger ratio of stirring needle diameter to plate thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A structural schematic diagram of a friction stir lap welding tool for realizing high-speed vertical flow;

[0030] Figure 2 for Figure 1A bottom view of the spiral needle and an enlarged view of the longitudinal section and the transverse section of the spiral needle;

[0031] Figure 3 It is a schematic diagram of material flow during the welding process of the "wavy" tail vortex needle;

[0032] Figure 4 It is a structural schematic diagram of the "straight-line" tail vortex needle and an enlarged view of the spiral groove;

[0033] Figure 5 It is a schematic diagram of material flow during the welding process of the "straight" tail vortex needle;

[0034] Among them: 1. Clamping end; 2. Shaft shoulder; 3. Conical vortex needle; 4. Spiral groove; 5. Large lead angle thread. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0036] like Figures 1 to 5 As shown, the present invention provides a stir friction lap welding tool and method for realizing high-speed vertical flow. The welding tool consists of two parts: a multi-spiral groove shoulder and a large-angle threaded conical multi-vortex needle. The multi-spiral groove design of the shoulder can accelerate the inward convergence of the material in contact with it, further enhance the vertical flow speed of the material in the needle, and complicate the lap interface structure, thereby improving the load-bearing capacity of the welded joint.

[0037] Specific:

[0038] A stir friction lap welding tool for realizing high-speed vertical flow, comprising a shaft shoulder 2 and a conical vortex needle 3, wherein a plurality of conical vortex needles 3 are arranged on the end face of the shaft shoulder 2, which are concentric with the end face of the shaft shoulder 2 and arranged circumferentially and do not contact each other, a plurality of spiral grooves 4 are opened in the gap corresponding to the tops of the plurality of vortex needles 3 on the end face of the shaft shoulder 2, a plurality of large lead angle threads 5 are arranged on the side face of the conical vortex needle 3, the end of the spiral groove 4 is close to the starting end of the large lead angle thread 5, the rotation direction of the large lead angle thread 5 needs to match the rotation direction of the shaft shoulder 2, when the rotation direction of the shaft shoulder 2 is counterclockwise, the large lead angle thread 5 is right-handed; when the rotation direction of the shaft shoulder 2 is clockwise, the large lead angle thread 5 is left-handed; wherein the diameter of the shaft shoulder 2 is 10mm≤Φ1≤20mm; the end face of the shaft shoulder 2 is provided with n spiral grooves, n≥2, and the width of the spiral groove 4 is Φ1 / 10≤ W1≤Φ1 / 5; m conical vortex needles 3 are provided, m≥2, and the angle γ between adjacent conical vortex needles 3 is 20°~60°; the length L of the conical vortex needle 3 is (0.5~1.5)×W1, the outer diameter of the top arc of the conical vortex needle 3 is Φ2=Φ1 / 3, the outer diameter of the bottom arc of the top of the conical vortex needle 3 is Φ3=2 / 3×Φ2, the longitudinal section width of the vortex needle 3 is W2=2 / 3×Φ3, W3=4 / 5×W2; the transverse section width of the vortex needle 3 is W4=2×W1, W5=4 / 5×W4,; the cone angle α corresponding to the transverse section of the vortex needle 3 is 25°~45°; k large lead angle threads 5 are provided, k≥2, the width W6 of the large lead angle threads 5 is depth=0.6mm~2.2mm, and the inclination angle β=45°~70°;

[0039] The tail of the vortex needle 3 is "wavy" or "straight". The "wavy" tail can make the material converge at the middle position of adjacent vortex needles 3 first, and then impact the center position of the vortex needle 3, while the "straight" tail can make the material at the middle position of adjacent vortex needles 3 directly impact the center position of the vortex needle.

[0040] A friction stir lap welding method for realizing high-speed vertical flow comprises the following steps:

[0041] Step 1: Select a welding tool with a suitable vortex needle length according to the plate thickness and overlap area of ​​the upper plate and the lower plate; the thickness of the upper plate is 1.0mm-2.0mm, and the thickness of the lower plate is 2.0mm-4.0mm; the plate material is a low melting point metal (such as aluminum, magnesium and other alloys, etc.), and the lower plate material is a low melting point metal or a high melting point metal (such as copper, steel, etc.);

[0042] Step 2: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine;

[0043] Step 3: The welding tool is mounted on the main shaft of the friction stir welding machine through the clamping end 1, the welding tool rotates at a speed of 600rpm≤ω≤1500rpm, and penetrates into the upper plate and the lower plate to be welded at a speed of 0.1-3mm / min at the welding starting position;

[0044] Step 4: When the conical vortex needle 3 of the welding tool reaches a predetermined penetration depth and the shoulder 2 of the welding tool penetrates the upper plate by 0.1 mm to 0.5 mm, the welding tool stops penetrating and continues to rotate for 2 min to 3 min;

[0045] Step 5: The welding tool advances at a transfer ratio of 20 to 100 to promote the upper and lower plate materials to flow downward and upward violently, respectively, to form a sufficient metallurgical bond;

[0046] Step 6: After reaching the end point of the weld, retract the welding tool and the entire welding process is completed.

[0047] The conical vortex needle can be used in stir friction butt welding. At this time, the number of large-angle threads on the side of the vortex needle k=0. During the welding process, the high-speed vertical flow and material aggregation characteristics inside / outside the vortex needle can effectively enhance the impact effect of the material in the aggregation area on the lower material of the welding plate, eliminate the incomplete penetration defects of the weld, and thus obtain a high-quality butt joint.

[0048] Example 1

[0049] A friction stir lap welding tool for realizing high-speed vertical flow, the welding tool consists of a shaft shoulder 2 and a conical vortex needle 3.

[0050] In this embodiment, the welded plate is a flat plate, the upper plate material is 2024 aluminum alloy with a thickness of 1 mm, and the lower plate material is 7075 aluminum alloy with a thickness of 2 mm; the diameter of the shoulder 2 is Φ1=18 mm; the end face of the shoulder is provided with 6 spiral grooves 4, and the width of the spiral groove 4 is W1=1.8 mm; the end face of the shoulder is provided with 6 vortex needles 3, the vortex needle length L=0.9 mm, the outer diameter Φ2=6 mm, Φ3=4 mm, the angle γ=30°, the vortex needle width W2=2.7 mm, W3=2.1 mm, W4=3.6 mm, W5=2.9 mm, and the cone angle α=30°; the side of the vortex needle is provided with 3 large lead angle threads 5, the thread width W6=depth=1.2 mm, and the inclination angle β=45°.

[0051] A friction stir lap welding method for realizing high-speed vertical flow comprises the following steps:

[0052] Step 1: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine;

[0053] Step 2: The welding tool is mounted on the main shaft of the friction stir welding machine through the clamping end 1, the welding tool rotates at a speed of 900 rpm, and penetrates into the upper plate and the lower plate to be welded at a speed of 1 mm / min at the welding starting position;

[0054] Step 3: When the conical vortex needle 3 of the welding tool reaches the predetermined penetration depth and the shoulder 2 of the welding tool penetrates the upper plate by 0.1 mm and does not penetrate the lower plate, the stirring head stops penetrating and continues to rotate for 2 minutes;

[0055] Step 4: The stirring head moves forward at a transfer welding ratio of 50 to promote the upper and lower plate materials to flow downward and upward violently respectively to form a full metallurgical bond;

[0056] Step 5: After reaching the end point of the weld, retract the stirring head and the entire welding process is completed.

[0057] In this embodiment, the vortex needle adopts a method of not piercing the lower plate, which can strongly impact and break the 2024 / 7075 lap interface on a large scale, so that the interface changes from the straight and continuous distribution before welding to a complex structure with a wide discontinuous area and the continuous part bending downward on the retreat side, thereby improving the bearing capacity of the lap weld joint.

[0058] Example 2

[0059] A stir friction lap welding tool and method for realizing high-speed vertical flow. The welding tool consists of a shaft shoulder 2 and a conical vortex needle 3.

[0060] In this embodiment, the welded plate is a flat plate, the upper plate material is 6061 aluminum alloy, the thickness is 1.5mm, the lower plate material is AZ31 magnesium alloy, the thickness is 3mm; the shoulder 2 diameter Φ1 = 15mm; the shoulder end face is provided with 5 spiral grooves 4, the spiral groove 4 width W1 = 2.0mm; the shoulder end face is provided with 4 vortex needles 3, the vortex needle length L = 1.4mm, outer diameter Φ2 = 5mm, Φ3 = 3.3mm, angle γ = 25°, vortex needle width W2 = 2.2mm, W3 = 1.8mm, W4 = 4.0mm, W5 = 3.2mm, cone angle α = 35°; the vortex needle side is provided with 4 large lead angle threads 5, thread width W6 = depth = 1.4mm, inclination angle β = 60°.

[0061] A friction stir lap welding method for realizing high-speed vertical flow comprises the following steps:

[0062] Step 1: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine;

[0063] Step 2: The welding tool is mounted on the main shaft of the friction stir welding machine through the clamping end 1, the stirring head rotates at a speed of 800 rpm, and penetrates into the plate to be welded at a speed of 1.2 mm / min at the welding starting position;

[0064] Step 3: When the conical vortex needle 3 of the welding tool reaches the predetermined penetration depth, the shoulder 2 of the welding tool penetrates the upper plate by 0.3 mm and slightly penetrates the lower plate by 0.2 mm, the welding tool stops penetrating and continues to rotate for 2 minutes;

[0065] Step 4: The welding tool advances at a transfer welding ratio of 80 to promote the upper and lower plate materials to flow downward and upward violently respectively to form a full metallurgical bond;

[0066] Step 5: After reaching the end point of the weld, retract the welding tool and the entire welding process is completed.

[0067] In this embodiment, the vortex needle is slightly penetrated into the lower plate by 0.2 mm, which can strongly impact and break the 6061 / AZ31 overlap interface on a large scale, so that the interface changes from the straight and continuous distribution before welding to a complex structure with a wide discontinuous area and a continuous part that is bent downward on the retreat side, thereby improving the bearing capacity of the overlap weld joint.

[0068] Example 3

[0069] A stir friction lap welding tool and method for realizing high-speed vertical flow. The welding tool consists of a shaft shoulder 2 and a conical vortex needle 3.

[0070] In this embodiment, the welded plate is a flat plate, the upper plate material is 7075 aluminum alloy, the thickness is 2.0mm, the lower plate material is T2 copper, the thickness is 3mm; the shoulder 2 has a diameter of Φ1=20mm; the shoulder end face is provided with 4 spiral grooves 4, the spiral groove 4 has a width W1=3.0mm; the shoulder end face is provided with 5 vortex needles 3, the vortex needle length L=1.5mm, the outer diameter Φ2=6.7mm, Φ3=4.4mm, the angle γ=45°, the vortex needle width W2=3.0mm, W3=2.4mm, W4=6.0mm, W5=4.8mm, and the cone angle α=45°; the vortex needle side is provided with 5 large lead angle threads 5, the thread width W6=depth=2.0mm, and the inclination angle β=65°.

[0071] A friction stir lap welding method for realizing high-speed vertical flow comprises the following steps:

[0072] Step 1: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine;

[0073] Step 2: The welding tool is mounted on the main shaft of the friction stir welding machine through the clamping end 1, the welding tool rotates at a speed of 1000 rpm, and penetrates into the plate to be welded at a speed of 1.5 mm / min at the welding starting position;

[0074] Step 3: When the conical vortex needle 3 of the welding tool reaches a predetermined penetration depth and the shoulder 2 of the welding tool penetrates the upper plate by 0.3 mm and does not penetrate the lower plate, the welding tool stops penetrating and continues to rotate for 3 minutes;

[0075] Step 4: The welding tool advances at a transfer ratio of 100 to promote the upper and lower plate materials to flow downward and upward violently respectively to form a full metallurgical bond;

[0076] Step 5: After reaching the end point of the weld, retract the welding tool and the entire welding process is completed.

[0077] In this embodiment, since the lower plate material is high melting point T2 copper material, a method without piercing the lower plate is adopted, which can achieve good metallurgical bonding of the overlapping interface below the needle, produce a mechanical interlocking effect, and obtain a welding joint with high load-bearing capacity.

Claims

1. A friction stir lap welding tool for realizing high-speed vertical flow, characterized in that: It includes a shaft shoulder and a conical vortex needle. The shaft shoulder end face is provided with a plurality of conical vortex needles which are concentric with the shaft shoulder end face, arranged circumferentially and do not contact each other. The side of the conical vortex needle is provided with a plurality of large-angle threads. A plurality of spiral grooves are opened in the gaps corresponding to the tops of the plurality of conical vortex needles on the shaft shoulder end face.

2. A friction stir lap welding tool for realizing high-speed vertical flow according to claim 1, characterized in that: The end of the spiral groove is close to the starting end of the large lead angle thread; the rotation direction of the large lead angle thread needs to be coordinated with the rotation direction of the shaft shoulder. When the rotation direction of the shaft shoulder is counterclockwise, the large lead angle thread is right-handed; when the rotation direction of the shaft shoulder is clockwise, the large lead angle thread is left-handed.

3. A friction stir lap welding tool for realizing high-speed vertical flow according to claim 1, characterized in that: The top of the conical vortex needle is in an arc shape, and the tail is in a "wave shape" or a "straight shape".

4. A stir friction lap welding tool for realizing high-speed vertical flow according to claim 1, characterized in that: The diameter of the shaft shoulder is 10mm≤Φ1≤20mm; the end face of the shaft shoulder is provided with n spiral grooves, n≥2, and the width of the spiral groove is Φ1 / 10≤W1≤Φ1 / 5.

5. A friction stir lap welding tool for realizing high-speed vertical flow according to claim 3, characterized in that: The conical vortex needles are provided with m, m≥2, and the angle γ between adjacent conical vortex needles is 20°~60°; the length of the conical vortex needle is L=(0.5~1.5)×W1, the outer diameter of the top arc of the conical vortex needle top is Φ2=Φ1 / 3, the bottom arc of the top of the conical vortex needle is Φ3=2 / 3×Φ2, the longitudinal section width of the conical vortex needle is W2=2 / 3×Φ3, W3=4 / 5×W2; the transverse section width of the conical vortex needle is W4=2×W1, W5=4 / 5×W4; the cone angle α corresponding to the transverse section of the conical vortex needle is 25°~45°.

6. A friction stir lap welding tool for realizing high-speed vertical flow according to claim 1, characterized in that: The large lead angle threads are provided with k numbers, k≥2, the width W6 of the large lead angle threads is equal to the depth of 0.6 mm to 2.2 mm, and the inclination angle β is equal to 45° to 70°.

7. A stir friction lap welding method for realizing high-speed vertical flow, according to the welding tool described in claim 1, characterized in that: The following steps are involved: Step 1: Select a welding tool with a suitable length of conical vortex needle according to the plate thickness and overlap area of ​​the upper plate and the lower plate; Step 2: Clamp the upper plate and the lower plate to be welded on the tooling of the friction stir welding machine; Step 3: The welding tool is installed on the main shaft of the friction stir welding machine, the welding tool rotates at a speed of 600rpm≤ω≤1500rpm, and penetrates into the upper plate and the lower plate to be welded at a speed of 0.1mm / min~3mm / min at the welding starting position; Step 4: When the conical vortex needle of the welding tool reaches the predetermined penetration depth and the shoulder of the welding tool penetrates into the upper plate by 0.1 to 0.5 mm, the welding tool stops penetrating and continues to rotate for 2 to 3 minutes; Step 5: The welding tool advances at a transfer ratio of 20 to 100 to promote the upper and lower plate materials to flow downward and upward violently, respectively, to form a sufficient metallurgical bond; Step 6: After reaching the end point of the weld, retract the welding tool and the entire welding process is completed.

8. The friction stir lap welding method for realizing high-speed vertical flow according to claim 7, characterized in that: The upper plate is made of low melting point metal, and the lower plate is made of low melting point metal or high melting point metal.

9. The friction stir lap welding method for realizing high-speed vertical flow according to claim 7, characterized in that: The thickness of the upper plate is 1.0 mm to 2.0 mm, and the thickness of the lower plate is 2.0 mm to 4.0 mm.

10. The friction stir lap welding method for realizing high-speed vertical flow according to claim 1, characterized in that: The conical vortex needle can be used in friction stir butt welding, and at this time, the number of large lead angle threads on the side of the conical vortex needle k=0.

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