Tab welding structure and backfill type friction stir spot welding method

Abstract

The invention belongs to the technical field of welding, and discloses a tab welding structure and a backfill type friction stir spot welding method.The tab welding structure comprises a cover plate, a gasket, a tab and a top cover, the cover plate is provided with a groove, a clamping groove is formed in the groove bottom of the groove, the gasket is embedded in the clamping groove, the gasket abuts against the groove wall of the clamping groove in the circumferential direction, the gasket is flush with the groove bottom of the groove, and the top cover is arranged on the top cover; a clamping groove is formed in the cover plate, a through hole is formed in the groove bottom of the clamping groove and used for containing a stirring head, the top cover is buckled on the cover plate, a pole column is integrated on the top cover, the tab is clamped between the pole column and the gasket, and the gasket, the tab and the pole column are integrated through friction stir spot welding. The pole lug and the pole column are welded through backfill type friction stir spot welding, the pole lug is prevented from being torn by a stirring head, the welding quality is improved, the welding speed is high, the welding temperature is low, and the application range is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of welding, and in particular to a tab welding structure and a backfill type friction stir spot welding method. Background Art

[0002] With the development of the new energy industry, lithium-ion batteries have gained widespread application in energy storage, electric vehicles, consumer electronics, and other industries due to their high energy density and conversion efficiency. Inside the battery, the battery cell is connected to the terminal on the top cover via tabs, which discharge energy externally. The positive and negative tabs of the battery cell are composed of multiple layers of aluminum foil and copper foil, respectively. The quality of the connection between the tabs and the terminal significantly affects the overall quality of the battery.

[0003] Currently, resistance spot welding, laser welding and ultrasonic welding are mostly used for welding battery tabs. However, all of the above welding methods have defects. During resistance spot welding and laser welding, the tabs undergo intense thermal cycling, resulting in large residual stresses inside. In addition, metallurgical defects such as pores and inclusions may exist inside the welds. The vibration during ultrasonic welding may lead to the generation of metal dust, causing micro-short circuits inside the battery cells, which ultimately results in unqualified battery self-discharge.

[0004] Friction stir welding is a solid-state joining technology. The welding process temperature is lower than the melting point of the metal, which can effectively avoid various metallurgical defects in the traditional fusion welding process and has high welding efficiency. Backfill friction stir welding further solves the keyhole defect of traditional friction stir welding, and the weld surface is smooth and defect-free. On the other hand, friction stir welding connects the workpieces to be welded by mechanical bonding and can combine dissimilar metals. Therefore, it is suitable for the connection between the lithium battery tab and the top cover. During the friction stir welding process, the stirring head rotates at high speed, heating and softening the metal, and then stirring and mixing the metal to be welded to form a mechanical connection. However, during the welding process, the stirring head will apply a large tangential load to the workpiece to be welded, which will cause the tab to be torn by the stirring head. Summary of the Invention

[0005] The object of the present invention is to provide a tab welding structure, which uses backfill stir friction spot welding and has high connection quality between the tab and the pole.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A tab welding structure comprises a cover plate, a gasket, a tab and a top cover, wherein the cover plate is provided with a groove, the bottom of the groove is provided with a card slot, the gasket is embedded in the card slot, and the gasket circumferentially abuts against the slot wall of the card slot, the gasket is flush with the bottom of the groove, the bottom of the card slot is provided with a through hole, the through hole is used to accommodate a stirring head, the top cover is buckled on the cover plate, and the top cover has an integrated pole, the tab is clamped between the pole and the gasket, and the gasket, the tab and the pole are friction stirred spot welded together.

[0008] Preferably, the top cover integrates the positive electrode column and the negative electrode column, the cover plate is provided with two grooves spaced apart along its length direction, two gaskets are provided, and the two gaskets are respectively embedded in the two slots, the tabs include positive tabs and negative tabs, the positive tab is clamped between the positive electrode column and one of the gaskets, and the negative tab is clamped between the negative electrode column and the other gasket.

[0009] Preferably, two buckles are provided on the back of the top cover, and the two buckles are spaced apart along the length direction of the top cover; two buckling grooves are provided on the front of the cover plate, and the two buckles are respectively buckled into the two buckling grooves.

[0010] Preferably, notches are provided on opposite sides of the groove, and the two notches are symmetrically arranged with the length direction of the cover plate as the axis. The notches penetrate the cover plate, and the opposite sides of the notches extend to the groove walls on the other two sides of the groove respectively, and the notches are used to accommodate the folded part of the tab.

[0011] Preferably, the gasket is made of aluminum alloy.

[0012] The object of the present invention is to provide a backfill type stir friction spot welding method for welding a pole ear and a pole, which has the advantages of high welding speed, low welding temperature and wide application range.

[0013] To achieve this object, the present invention adopts the following technical solutions:

[0014] A backfill friction stir spot welding method for forming the above-mentioned tab welding structure comprises the following steps:

[0015] S1, the stirring head extends into the through hole until the clamping ring abuts against the gasket;

[0016] S2, the shaft shoulder and the stirring needle rotate synchronously and rub against the gasket to generate friction heat and thus plasticize the gasket;

[0017] S3, the stirring needle rises, the shoulder presses down a certain value, and the shoulder squeezes the plastic metal into the cavity left by the rising stirring needle;

[0018] S4, the shaft shoulder rises, and the stirring needle is pressed down to squeeze the plastic metal into the cavity left by the rising shaft shoulder;

[0019] S5. The shaft shoulder is pressed downward and the stirring needle is raised until the clamping ring, the shaft shoulder and the stirring needle are at the same height.

[0020] Preferably, the thickness of the gasket is 1 mm, and in S3, the downward pressure value of the shoulder is 0.8-1.2 mm, and the downward pressure dwell time of the shoulder is 1 s-5 s.

[0021] Preferably, the stirring head includes the clamping ring, the shoulder and the stirring needle, the shoulder is sleeved on the outside of the stirring needle, the clamping ring is arranged on the outside of the shoulder, the stirring needle can rotate and move up and down relative to the shoulder, and the shoulder can rotate and move up and down relative to the clamping ring.

[0022] Preferably, the rotational speed of the shaft shoulder and the stirring needle is 500 rpm-2000 rpm.

[0023] Preferably, the diameter of the through hole is 18 mm, and the diameter of the clamping ring is 18 mm.

[0024] Beneficial effects of the present invention:

[0025] The present invention provides a tab welding structure, comprising a cover plate, a gasket, a tab and a top cover, wherein the cover plate is provided with a groove, the bottom of the groove is provided with a card slot, the gasket is embedded in the card slot, and the gasket is circumferentially abutted against the slot wall of the card slot, the gasket is flush with the bottom of the groove, the bottom of the card slot is provided with a through hole, the through hole is used to accommodate a stirring head, the top cover is buckled on the cover plate, and the top cover is integrated with a pole, the tab is clamped between the pole and the gasket, the gasket, the tab and the pole are friction stirred spot welded as a whole, a backfilling type friction stir spot welding method for forming the above-mentioned tab welding structure comprises the following steps: S1, the stirring head is inserted into the through hole until it is pressed tightly The ring abuts the gasket; S2, the shaft shoulder and the stirring needle rotate synchronously and rub against the gasket to generate friction heat and thus plasticize the gasket; S3, the stirring needle rises, the shaft shoulder presses down a certain value, and the shaft shoulder squeezes the plastic metal into the cavity left by the rising stirring needle; S4, the shaft shoulder rises, the stirring needle presses down, and squeezes the plastic metal into the cavity left by the rising shaft shoulder; S5, the shaft shoulder presses down, and the stirring needle rises until the clamping ring, the shaft shoulder and the stirring needle are at the same height; the present invention uses backfill stir friction spot welding to weld the pole ear and the pole column, which avoids the pole ear being torn by the stirring head, improves the welding quality, has a fast welding speed, a low welding temperature, and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an exploded schematic diagram of a tab welding structure welded by a stirring head provided in the first embodiment of the present invention;

[0027] Figure 2 This is a schematic structural diagram of a cover plate provided in Embodiment 1 of the present invention;

[0028] Figure 3 This is a flow chart of a backfill friction stir spot welding method provided by the second embodiment of the present invention;

[0029] Figure 4 This is a welding schematic diagram of a backfill friction stir spot welding method provided by the second embodiment of the present invention;

[0030] Figure 5 It is a structural schematic diagram of the stirring head provided in the second embodiment of the present invention.

[0031] In the picture:

[0032] 1. Cover plate; 11. Groove; 111. Card slot; 1111. Through hole; 12. Notch; 2. Gasket; 3. Tab; 4. Top cover; 41. Buckle; 5. Pole;

[0033] 10. Stirring head; 101. Clamping ring; 102. Shaft shoulder; 103. Stirring needle. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0035] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0036] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0037] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0038] Example 1

[0039] This embodiment provides a tab welding structure, and the connection quality between the tab and the pole is relatively high.

[0040] See also Figure 1 and Figure 2 A pole tab welding structure includes a cover plate 1, a gasket 2, a pole tab 3 and a top cover 4. The cover plate 1 is buckled on the top cover 4, and the gasket 2 and the pole tab 3 are both located between the cover plate 1 and the top cover 4. The pole post 5 is assembled on the top cover 4, and the pole tab 3 is clamped between the gasket 2 and the pole post 5. The gasket 2, the pole tab 3 and the pole post 5 are friction stirred and spot welded together by a stirring head 10. By adopting friction stir spot welding, the connection quality of the pole tab 3 and the pole post 5 is optimized, the welding efficiency is improved, and the weld surface is smooth and defect-free. By providing the gasket 2, the stirring head 10 is prevented from directly applying a tangential load to the pole tab 3, thereby preventing the pole tab 3 from tearing during welding.

[0041] Preferably, the tab 3 is a multi-layer stacked metal foil material, with a single layer thickness of 0.010 mm to 0.012 mm, 1 to 100 layers, and a total thickness of 0.8 mm to 1.0 mm.

[0042] In this embodiment, the gasket 2 is clamped on the cover plate 1 before spot welding to fix the position of the gasket 2. Figure 2 The cover plate 1 is provided with a groove 11, and a slot 111 is provided at the bottom of the groove 11. The gasket 2 is clamped in the slot 111, and the gasket 2 is circumferentially abutted against the groove wall of the slot 111, thereby fixing the position of the gasket 2 on the cover plate 1 and preventing it from shifting during the spot welding process. Furthermore, the gasket 2 is flush with the bottom of the groove 11, thereby reserving a space for the tab 3. There is a height difference between the bottom of the groove 11 and other areas of the cover plate 1. The tab 3 is accommodated in the space formed by the height difference, preventing the tab 3 from protruding from the surface of the cover plate 1, resulting in a loose fit between the cover plate 1 and the top cover 4.

[0043] Preferably, the gasket 2 is made of aluminum alloy. For example, the thickness of the gasket 2 is 1 mm, the length of the gasket 2 is 20 mm, and the width is 20 mm. Similarly, the depth of the card slot 111 is 1 mm.

[0044] By providing the gasket 2 , on the one hand, the tab 3 is protected from excessive tangential load during the spot welding process, and on the other hand, the tab 3 can be helped to be fixed.

[0045] Furthermore, a through hole 1111 is provided at the bottom of the slot 111, and the through hole 1111 is used to accommodate the insertion of the stirring head 10. The stirring head 10 is inserted into the through hole 1111 and can directly abut against the gasket 2, and then rotate at high speed, frictionally heating the gasket 2 and the pole ear 3 and pole column 5 thereunder, thereby softening the pole ear 3 and pole column 5, and stirring and mixing them. After cooling, the gasket 2, pole ear 3 and pole column 5 are fused into one, realizing the connection between the pole ear 3 and pole column 5.

[0046] Preferably, the through hole 1111 is circular with a diameter of 18 mm.

[0047] For example, the top cover 4 is a rectangular structure, and the two symmetrical sides of the cover plate 1 along its width direction do not exceed the top cover 4, and the two symmetrical sides of the cover plate 1 along its length direction also do not exceed the top cover 4, so as to facilitate battery assembly.

[0048] This embodiment provides a structure for the cover plate 1 to be fastened to the top cover 4. Specifically, the side where the pole 5 protrudes from the surface of the top cover 4 is the front side of the top cover 4, and the side where the pole 5 is flush with the surface of the top cover 4 is the back side. Two snaps 41 are provided on the back side of the top cover 4. The two snaps 41 are spaced apart along the length direction of the top cover 4. Preferably, the two snaps 41 are provided at the edge of the top cover 4. Furthermore, the side where the groove 11 is provided on the cover plate 1 is the front side of the cover plate 1. The front side of the cover plate 1 is provided with two fastening grooves. The two fastening grooves are spaced apart along the length direction of the cover plate 1. Preferably, the two fastening grooves are provided at the edge of the cover plate 1. The two snaps 41 are respectively fastened to the two fastening grooves, thereby limiting the relative displacement of the cover plate 1 and the top cover 4, thereby achieving the fastening of the cover plate 1 and the top cover 4.

[0049] Since the tab 3 extends from the outside of the battery cell to the inside of the battery cell, part of the tab 3 is sandwiched between the gasket 2 and the pole 5, and the remaining area extends away from the top cover 4. Therefore, in this embodiment, two notches 12 are symmetrically provided on the cover 1 to accommodate the folded portion of the tab 3, that is, the area where the tab 3 extends to the inside of the battery cell. Specifically, notches 12 are provided on opposite sides of the groove 11. The notches 12 pass through the cover 1, and the two sides in the length direction of the pole are folded and respectively accommodated in the two notches 12. Preferably, the two notches 12 are symmetrically arranged with the length direction of the cover 1 as the axis, so that the tab 3 is arranged parallel to the width direction of the cover 1. Further preferably, the opposite sides of the notch 12 extend to the groove walls on the other two sides of the groove 11 to prevent the folded part of the tab 3 from wrinkling.

[0050] For example, two poles 5 are integrated on the top cover 4, namely the positive pole 5 and the negative pole 5. Adaptively, two gaskets 2 are provided, and two grooves 11 are provided on the cover plate 1. The two grooves 11 are arranged at intervals along the length direction of the cover plate 1. There are two pole ears 3, namely the positive pole ear 3 and the negative pole ear 3. The positive pole ear 3 is clamped between the positive pole 5 and one of the gaskets 2, and the negative pole ear 3 is clamped between the negative pole 5 and the other gasket 2.

[0051] This embodiment provides a tab welding structure that uses backfill friction stir spot welding. Backfill friction stir spot welding is used to weld the tab 3 without damaging the tab 3 by the stirring head 10, thereby improving the disadvantages of welding methods such as laser welding and ultrasonic welding, reducing the possibility of the tab 3 being desoldered when the battery is subjected to an impact load, and improving the connection quality between the tab 3 and the pole 5.

[0052] Example 2

[0053] This embodiment provides a backfill friction stir spot welding method for forming a tab welding structure in the first embodiment above.

[0054] See also Figure 3-Figure 5 , a backfill friction stir spot welding method, comprising the following steps:

[0055] S1. The stirring head 10 is inserted into the through hole 1111 until the clamping ring 101 contacts the gasket 2.

[0056] S2, the shaft shoulder 102 and the stirring pin 103 rotate synchronously and rub against the gasket 2 to generate friction heat and thus plasticize the gasket 2;

[0057] S3, the stirring needle 103 rises, the shaft shoulder 102 is pressed down to a certain value, and the shaft shoulder 102 squeezes the plastic metal into the cavity left by the rising stirring needle 103;

[0058] S4, the shaft shoulder 102 rises, and the stirring needle 103 is pressed down, squeezing the plastic metal into the cavity left by the rising shaft shoulder 102;

[0059] S5, the shaft shoulder 102 is pressed down, and the stirring needle 103 is raised until the clamping ring 101, the shaft shoulder 102 and the stirring needle 103 are at the same height.

[0060] Specifically, the stirring head 10 includes a clamping ring 101, a shoulder 102, and a stirring needle 103. The shoulder 102 is sleeved on the outside of the stirring needle 103, and the clamping ring 101 is arranged on the outside of the shoulder 102. The stirring needle 103 can rotate and move up and down relative to the shoulder 102, and the shoulder 102 can rotate and move up and down relative to the clamping ring 101. The stirring head 10 used in this embodiment has a clamping ring 101 with a diameter of 18 mm, a shoulder 102 with a diameter of 9 mm, and a stirring needle 103 with a diameter of 2 mm.

[0061] The gasket 2 in the first embodiment is clamped in the slot 111, the tab 3 is clamped between the gasket 2 and the pole 5, the cover 1 and the top cover 4 are buckled together, and after the buckling is completed, they are positioned and placed with the side of the cover 1 with the through hole 1111 facing upwards.

[0062] First, control the stirring head 10 to extend into the through hole 1111 on the cover plate 1 until the clamping ring 101 abuts against the gasket 2;

[0063] The shaft shoulder 102 and the stirring needle 103 are started, and the shaft shoulder 102 and the stirring needle 103 rotate synchronously and rub against the gasket 2 to generate friction heat, thereby plasticizing the gasket 2. For example, the rotation speed of the shaft shoulder 102 and the stirring needle 103 is 500 rpm-2000 rpm;

[0064] Furthermore, the rotating stirring needle 103 moves upward and the rotating shoulder 102 moves downward. In the downward pressing stage, the rising rate of the stirring needle 103 should satisfy a certain matching relationship with the downward pressing rate of the shoulder 102 so that the volume of the gasket 2 squeezed downward by the shoulder 102 is equal to the volume of the cavity withdrawn by the stirring needle 103. For example, the downward pressing value of the shoulder 102 is 0.8-1.2 mm, the downward pressing residence time of the shoulder 102 is 1s-5s, and the downward pressing speed is 10mm / min-100mm / min.

[0065] Furthermore, the rotating stirring needle 103 moves downward, and the rotating shaft shoulder 102 moves upward. The downward pressing rate of the stirring needle 103 should meet a certain matching relationship with the rising rate of the shaft shoulder 102 so that the volume of the cavity withdrawn by the shaft shoulder 102 is equal to the volume of the gasket 2 pressed downward by the stirring needle 103;

[0066] Finally, the rotating stirring needle 103 moves upward and the rotating shaft shoulder 102 moves downward until the clamping ring 101, the shaft shoulder 102 and the stirring needle 103 are at the same height, thereby completing the friction stir spot welding. After softening, the gasket 2, the pole ear 3 and the pole 5 are stirred and mixed, and a weld is formed after cooling.

[0067] Preferably, the stirring head 10 is further provided with a cooling mechanism, which can pass compressed air into the friction surface to reduce the temperature of the stirring head 10 and increase the service life of the stirring head 10.

[0068] The backfill friction stir spot welding method provided in this embodiment has a fast welding speed, a low welding temperature, and a wide range of applications.

[0069] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A tab welding structure, characterized in that: The invention comprises a cover plate (1), a gasket (2), a pole ear (3) and a top cover (4); the cover plate (1) is provided with a groove (11); the bottom of the groove (11) is provided with a clamping groove (111); the gasket (2) is embedded in the clamping groove (111), and the gasket (2) abuts against the groove wall of the clamping groove (111) in the circumferential direction; the gasket (2) is flush with the bottom of the groove (11); the bottom of the clamping groove (111) is provided with a through hole (1111); the through hole (1111) is used to accommodate a stirring head (10); the top cover (4) is buckled on the cover plate (1), and a pole (5) is integrated on the top cover (4); the pole ear (3) is sandwiched between the pole (5) and the gasket (2); the gasket (2), the pole ear (3) and the pole (5) are friction-stirred and spot-welded into one piece.

2. A tab welding structure according to claim 1, characterized in that: The top cover (4) integrates a positive electrode column (5) and a negative electrode column (5); the cover plate (1) is provided with two grooves (11) spaced apart along its length direction; two gaskets (2) are provided, and the two gaskets (2) are respectively embedded in the two slots (111); the pole ears (3) include a positive pole ear (3) and a negative pole ear (3); the positive pole ear (3) is clamped between the positive electrode column (5) and one of the gaskets (2); and the negative pole ear (3) is clamped between the negative electrode column (5) and the other gasket (2).

3. The electrode tab welding structure according to claim 1, characterized in that: The back of the top cover (4) is provided with two buckles (41), and the two buckles (41) are arranged at intervals along the length direction of the top cover (4); the front of the cover plate (1) is provided with two buckling grooves, and the two buckling grooves are arranged at intervals along the length direction of the cover plate (1), and the two buckles (41) are buckled in the two buckling grooves respectively.

4. The electrode tab welding structure according to claim 1, characterized in that: Notches (12) are provided on opposite sides of the groove (11), and the two notches (12) are symmetrically arranged with the length direction of the cover plate (1) as an axis. The notches (12) penetrate the cover plate (1), and opposite sides of the notches (12) respectively extend to the groove walls on the other two sides of the groove (11), and the notches (12) are used to accommodate the folded portion of the pole lug (3).

5. The electrode tab welding structure according to claim 1, characterized in that: The material of the gasket (2) is aluminum alloy.

6. A backfill friction stir spot welding method for forming a tab welding structure as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1, the stirring head (10) extends into the through hole (1111) until the clamping ring (101) abuts against the gasket (2); S2, the shaft shoulder (102) and the stirring needle (103) rotate synchronously and rub against the gasket (2) to generate friction heat, thereby plasticizing the gasket (2); S3, the stirring needle (103) rises, the shoulder (102) is pressed down by a certain value, and the shoulder (102) squeezes the plastic metal into the cavity left by the rising stirring needle (103); S4, the shaft shoulder (102) rises, and the stirring needle (103) is pressed down to squeeze the plastic metal into the cavity left by the rising shaft shoulder (102); S5, the shaft shoulder (102) is pressed downward, and the stirring needle (103) is raised until the clamping ring (101), the shaft shoulder (102) and the stirring needle (103) are at the same height.

7. A backfill friction stir spot welding method according to claim 6, characterized in that: The thickness of the gasket (2) is 1 mm. In S3, the downward pressure value of the shoulder (102) is 0.8-1.2 mm, and the downward pressure residence time of the shoulder (102) is 1 s-5 s.

8. A backfill friction stir spot welding method according to claim 6, characterized in that: The stirring head (10) comprises the clamping ring (101), the shaft shoulder (102) and the stirring needle (103); the shaft shoulder (102) is sleeved on the outer side of the stirring needle (103); the clamping ring (101) is arranged on the outer side of the shaft shoulder (102); the stirring needle (103) can rotate and move up and down relative to the shaft shoulder (102); and the shaft shoulder (102) can rotate and move up and down relative to the clamping ring (101).

9. A backfill friction stir spot welding method according to claim 6, characterized in that: The rotation speed of the shaft shoulder (102) and the stirring needle (103) is 500rpm-2000rpm.

10. A backfill type friction stir spot welding method according to claim 6, characterized in that: The diameter of the through hole (1111) is 18 mm, and the diameter of the clamping ring (101) is 18 mm.

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