A liquid cooling plate structure

Abstract

The utility model discloses a liquid cooling plate structure, including main part, plugging part and welding part, the main part is provided with the flow channel and the opening of communication with flow channel, the plugging part seals and covers the opening, and the welding part sets up in the butt joint edge of main part and plugging part, and the welding part includes welding section and lead -out section, and the welding section extends along the butt joint edge and covers the outer periphery of opening, and the lead -out section is located at the end of welding section, and the thickness of lead -out section is greater than the thickness of welding section, and it is designed to solve how to effectively alleviate the technical problem of spoon hole influence liquid cooling cavity tightness caused by friction stir welding.

Description

Technical Field

[0001] This utility model relates to the field of liquid cooling plate technology, and in particular to a liquid cooling plate structure. Background Technology

[0002] As a key thermal management component in power battery packs, electronic devices, and high-power components, liquid cooling plates typically have internal liquid cooling chambers for coolant flow, achieving efficient heat transfer through liquid circulation. To ensure the structural sealing of the liquid cooling plate and the precise shaping of its internal flow channels, metal sheets are usually assembled and welded along a predetermined path to form a closed cooling circuit structure.

[0003] Among numerous welding processes, friction stir welding is widely used in the welding of liquid-cooled plate shells due to its advantages such as a small heat-affected zone, high joint performance, and minimal deformation. This process utilizes a high-speed rotating stirring needle to locally heat and plastically stir the workpiece, achieving solid-state bonding without the need to melt the material.

[0004] However, during friction stir welding, the stirring head needs to be removed at the end of the welding process, leaving a circular hole-like defect called a "keyhole" at the end of the weld. This keyhole usually penetrates vertically through the weld surface and extends into the liquid cooling cavity. If it is not effectively sealed, it can easily form a leakage channel, seriously affecting the sealing performance and service life of the liquid cooling plate.

[0005] Therefore, it is urgent to solve the problem of keyholes affecting the sealing of liquid cooling chambers caused by friction stir welding while ensuring welding strength. Utility Model Content

[0006] One objective of this invention is to provide a liquid cooling plate structure that addresses the technical problem of how to effectively mitigate the impact of keyholes caused by friction stir welding on the sealing performance of the liquid cooling cavity.

[0007] To achieve the above objectives, the present invention provides a solution as follows: a liquid cooling plate structure, the liquid cooling plate structure including a main body having a flow channel and an opening communicating with the flow channel; a sealing part for sealing and covering the opening; and a welding part disposed at the mating edge of the main body and the sealing part, the welding part including a welding section and a lead-out section, the welding section extending along the mating edge and covering the outer periphery of the opening, the lead-out section being located at the end of the welding section, and the thickness of the lead-out section being greater than the thickness of the welding section.

[0008] Optionally, the length L1 of the lead-out section along the welding direction satisfies: 2D≤L1≤4D, where D is the diameter of the friction stir welding needle.

[0009] Optionally, the thickness T2 of the lead-out section and the thickness T1 of the welding section satisfy: 2.0≤T2 / T1≤3.

[0010] Optionally, along the direction away from the welding section, the thickness of the lead-out section gradually increases, and the thickness change angle α satisfies the relationship: 1°≤a≤5°.

[0011] Optionally, the lead-out section includes a residual portion, the welding section extends to the edge of the main body and the sealing portion, the residual portion protrudes from the edge, and the residual portion includes a cut-off surface for cutting off the lead-out area of ​​the friction stir welding needle.

[0012] Optionally, the distance between the cut surface and the edge is L2, satisfying the relationship: 3mm≤L2≤5mm.

[0013] Optionally, the angle between the cut surface and the plane containing the edge is b, satisfying the relationship: 80°≤b≤90°.

[0014] Optionally, the width of the residual portion gradually increases along the direction of extension of the mating edge.

[0015] Optionally, the lead-out section includes a withdrawal zone for the withdrawal of the friction stir welding needle. The minimum distance L3 between the withdrawal zone and the junction of the lead-out section and the welding section satisfies: 0.8D≤L3≤D, where D is the diameter of the friction stir welding needle.

[0016] Optionally, the exit area is provided with a boss structure, the surface of which is higher than the reference plane of the lead-out section.

[0017] The beneficial effects of this utility model are as follows:

[0018] Compared to the problem of keyhole-induced sealing failure in liquid cooling chambers in existing technologies, this application addresses this issue by incorporating an extension section with a thickness greater than that of the weld section. This provides the weld end with stronger structural buffering and sealing adaptability. Furthermore, the extension section can be located either within the edge of the liquid cooling plate or extended beyond it. In particular, when positioned outside the edge, the keyhole can be effectively guided to the outside of the liquid cooling chamber. By cutting off the extension section, the defective area can be completely isolated, fundamentally resolving the adverse effects of the keyhole at the weld end on the sealing structure. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is an overall schematic diagram of a liquid cooling plate structure provided in an embodiment of this utility model;

[0021] Figure 2This is a partial cross-sectional view of the liquid cooling plate structure provided in this embodiment of the utility model along the vertical direction;

[0022] Figure 3 This is a schematic cross-sectional view of the liquid cooling plate structure provided in this embodiment of the present invention along the horizontal direction;

[0023] Figure 4 This is a partial cross-sectional view of another liquid cooling plate structure provided in this embodiment of the present invention along the horizontal direction;

[0024] Figure 5 This is a partial cross-sectional view of another liquid cooling plate structure provided in this embodiment of the present invention along the horizontal direction;

[0025] Figure 6 This is a top enlarged view of a partial structure of a liquid cooling plate provided in an embodiment of the present invention;

[0026] Figure 7 This is a partial cross-sectional view of a new liquid cooling plate structure provided in this embodiment of the present invention along the horizontal direction.

[0027] Explanation of icon numbers:

[0028] 10. Main body; 11. Flow channel; 12. Opening; 20. Sealing part; 30. Welding part; 31. Welding section; 32. Lead-out section; 321. Residual part; 322. Exit area. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0031] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0032] Please see Figures 1 to 3, Figure 1 This is an overall schematic diagram of a liquid cooling plate structure provided in an embodiment of this utility model. Figure 2 This is a partial cross-sectional view of the liquid cooling plate structure provided in this embodiment of the utility model along the vertical direction. Figure 3 This is a cross-sectional view of the liquid cooling plate structure provided in this embodiment of the utility model along the horizontal direction.

[0033] This utility model provides a liquid cooling plate structure, which aims to alleviate the adverse effects of the keyhole formed by the needle being pulled out during the friction stir welding process on the sealing performance of the liquid cooling cavity, thereby improving the overall sealing reliability and product stability of the liquid cooling plate.

[0034] The liquid-cooled plate structure includes a main body 10, a sealing part 20, and a welding part 30. The main body 10 is the main shell of the liquid-cooled plate, and has an internal flow channel 11 for coolant flow. An opening 12 communicating with the flow channel 11 is formed on the main body 10, and the opening 12 is used for subsequent sealing with the sealing part 20. The sealing part 20 is sized to fit the opening 12 and can cover it. The sealing part 20, through welding to the main body 10, seals the opening 12, thereby forming a closed liquid-cooled cavity.

[0035] A welding section 30 is located at the mating edge of the main body 10 and the sealing section 20, used to connect the two and achieve structural sealing. The welding section 30 includes a welding segment 31 and a lead-out segment 32. The welding segment 31 extends along the mating edge of the main body 10 and the sealing section 20, and is arranged around the opening 12 to form a continuous friction stir weld, thereby achieving the joining of the two components. The lead-out segment 32 is located at the end of the welding segment 31 and serves as the natural lead-out path for the friction stir welding needle.

[0036] Specifically, the thickness of the lead-out section 32 is set to be greater than that of the welded section 31. This structure provides additional material redundancy and structural buffer when the stirring needle is withdrawn, ensuring that the resulting keyhole is far from the actual boundary of the liquid cooling cavity and located in the middle or end of the lead-out section 32, thereby effectively avoiding the risk of leakage caused by the keyhole communicating with the liquid cooling cavity. In addition, due to the larger thickness of the lead-out section 32, it has greater structural stability when bearing residual welding thermal stress and subsequent sealing treatment, facilitating reliable sealing of the keyhole through subsequent processes (such as cold pressing sealing, repair welding, and stud sealing).

[0037] Furthermore, the lead-out section 32 can be located within the edge of the main body 10 and the sealing part 20, or it can extend along the welding path direction and be located outside the edge of the main body 10 and the sealing part 20. When the lead-out section 32 is located within the edge, the keyhole will be formed within the structure of the liquid cooling plate body; while when the lead-out section 32 extends outside the edge, the stirring needle can naturally retract after welding and form a keyhole in the extended area. This keyhole and the extended section can be directly cut off or removed after welding, thereby completely eliminating the impact on the sealing performance of the liquid cooling cavity.

[0038] Furthermore, in order to ensure that the needle can be drawn out smoothly during the friction stir welding process, the length L1 of the lead-out section 32 along the welding direction satisfies the following range: 2D≤L1≤4D, where D is the diameter of the friction stir welding needle.

[0039] In actual welding, the withdrawal of the stirring needle is usually accompanied by a gradual decrease in heat input and a backfilling process. If the length of the lead-out section 32 is insufficient, resulting in a small distance between the weld termination position and the welding section 31, the high temperature and disturbance area generated by the stirring needle at the moment of withdrawal will inevitably affect the welding section 31. The heat-affected zone will cause insufficient backfilling of the joint metal structure, a decrease in the bonding force at the keyhole edge, and even the keyhole structure may extend directly into the interior of the welding section 31, thereby disrupting the weld continuity.

[0040] By setting L1 ≥ 2D, sufficient buffer space is ensured for energy release and material backfilling before the weld end point, effectively limiting the keyhole to the lead-out section 32 and avoiding negative impacts on the welding section 31. Limiting L1 to 4D helps to ensure welding process stability while preventing excessive length of the lead-out section 32, thus avoiding material waste and structural redundancy. Therefore, limiting the length of the lead-out section 32 to 2 to 4 times the diameter of the stirring needle fully meets the requirements of the friction stir welding lead-out process while maintaining structural compactness and improving overall welding quality.

[0041] Considering the strength redundancy and processing capacity of the keyhole of the lead-out section 32, the thickness T2 of the lead-out section 32 and the thickness T1 of the welding section 31 satisfy the following relationship: 2.0≤T2 / T1≤3.

[0042] Friction stir welding creates a keyhole structure at the weld endpoint during the needle withdrawal phase, which can easily become a weak point in the liquid-cooled plate sealing structure. If the lead-out section 32 is not thick enough, it will not only be difficult to effectively accommodate the material deformation caused by welding disturbances, but may also lead to leakage risks during subsequent sealing processes due to insufficient local thickness.

[0043] By setting T2 to 2 to 3 times the thickness T1 of the welded section 31, the lead-out section 32 can provide a thicker base structure to accommodate the keyhole, enhancing the structural rigidity and sealing material adhesion area of ​​the region. On the one hand, this facilitates more reliable sealing of the keyhole after welding through mechanical removal, repair welding, plugging, or other processes; on the other hand, it also improves the overall stability of the weld end region under subsequent vibration or thermal cycling conditions.

[0044] If T2 / T1 is less than 2.0, the lead-out section 32 cannot adequately support the keyhole and its edge defects under welding disturbance and thermal stress, leading to a degradation in welding strength. If T2 / T1 is greater than 3.0, the structure becomes overly redundant, increasing material costs and hindering dimensional control. Therefore, controlling T2 / T1 within the range of 2.0 to 3.0 achieves a better balance between strength, safety, and manufacturability.

[0045] Please see Figure 4 , Figure 4 This is a partial cross-sectional view of another liquid cooling plate structure provided in this embodiment of the present invention along the horizontal direction. In some embodiments, the thickness of the lead-out section 32 can be set to gradually increase along the direction away from the welding section 31, that is, to form a thickness transition zone with a certain slope, so that the thermal stress and mechanical disturbance of the stirring needle during the pulling process can diffuse more smoothly to the outer periphery of the structure.

[0046] Specifically, the thickness variation of the lead-out section 32 forms a certain inclination angle α, which is defined as the angle between the inclined surface formed by the thickness variation of the lead-out section 32 along the welding direction and the welding plane. Preferably, the thickness variation angle α satisfies: 1° ≤ α ≤ 5°.

[0047] The gradually increasing thickness causes the lead-out section 32 to gradually transition outward from one end near the welding section 31 to the maximum thickness, forming a sloping area. During the welding process, this effectively guides the stirring needle from the main weld to the thicker structural area, reducing the degree of material disturbance at the moment of needle withdrawal and preventing adverse phenomena such as structural tearing and keyhole extension caused by local heat accumulation or poor material flow.

[0048] When a < 1°, the thickness transition is too gentle, failing to significantly improve the structural buffering capacity of the needle-pulling area. Conversely, when a > 5°, the slope is too steep, leading to an excessively rapid increase in the overall thickness of the lead-out section 32. This not only increases material costs but also introduces significant thickness abrupt changes in the structure, affecting the uniformity of stress distribution across the entire plate. Therefore, by setting the lead-out section 32 to gradually thicken along the welding direction and controlling its thickness change angle α within the range of 1° to 5°, not only are the material response characteristics of the welding transition zone optimized, but the thermal shock resistance and sealing adaptability of the weld end are also improved.

[0049] Please see Figure 5 , Figure 5 This is a partial cross-sectional view of another liquid cooling plate structure provided by this utility model along the horizontal direction. In some embodiments, the lead-out section 32 can extend along the welding path direction beyond the edges of the main body 10 and the sealing part 20, that is, it extends beyond the outline of the liquid cooling plate body structure to form an extension area. This extension area is used to accommodate the lead-out trajectory of the stirring needle when the weld ends during the welding process, so that the keyhole is fixed in this extension area, thereby preventing the welding section 31 and the liquid cooling cavity structure it covers from being disturbed by the keyhole, ensuring its airtightness and structural integrity.

[0050] After the welding process is completed, in order to achieve a regularized final product structure, the extended lead-out section 32 will be completely removed, retaining only the functional structural areas required by the liquid cooling plate. The structural portion left at the edge of the liquid cooling plate after removal is called the residual portion 321, which is part of the original lead-out section 32 from the welding process and remains connected to the plate edge after removal. The residual portion 321 is typically a structural transition zone. The residual portion 321 includes a cut surface, which is the separation interface formed after the removal operation, typically appearing as an exposed machined metal surface or a flat cross-section.

[0051] With the above structure, this application extends the welding keyhole from the functional structure to the non-functional area and removes it by mechanical cutting after welding, leaving only the complete sealing weld and the liquid cooling cavity body structure. This effectively avoids the problems in the prior art, such as keyhole penetration of the liquid cooling cavity, damage to the sealing structure, and leakage caused by the direct pulling out of the friction stir welding needle.

[0052] Furthermore, in some optimized embodiments, the distance between the cut surface and the edge of the main body 10 or the blocking part 20 is set to L2, and satisfies the following range: 3mm≤L2≤5mm.

[0053] Wherein, L2 represents the axial distance from the edge of the liquid cooling plate body structure to the cut surface, that is, the length of the residual portion 321 retained in the final product after the welding path extends outward. When L2 ≥ 3mm, it can provide sufficient processing safety margin for mechanical cutting to prevent affecting the interior of the welded section 31; while when L2 ≤ 5mm, it can limit the size of the residual portion 321 within a reasonable range to avoid structural redundancy and affecting the product appearance.

[0054] It is worth noting that the location of the cut surface does not necessarily coincide with the welding endpoint. In actual processes, in order to obtain a more stable needle removal effect, the stirring needle is usually moved a certain distance along the path after welding is completed before being withdrawn, so that it is completely removed from the weld zone and then pulled out in the middle or end of the extension section.

[0055] Considering the regularity of the edge morphology after the lead-out segment 32 is removed, in some embodiments, the angle between the cut surface and the plane containing the edge is b, and the relationship is satisfied: 80°≤b≤90°.

[0056] Here, the cut surface refers to the exposed metal interface formed at the separation point between the residual portion 321 and the lead-out section 32 after the welding is completed and the lead-out section 32 is removed from the outer extension area of ​​the liquid cooling plate through machining. The plane containing the edge refers to the extended reference plane of the edge of the liquid cooling plate body. The included angle b between the two defines the inclination angle of the cut surface relative to the edge of the plate body.

[0057] When b is close to 90°, the cut surface is almost perpendicular to the edge of the plate, forming a flat and regular boundary, which helps to improve the geometric consistency of the finished liquid cooling plate. This is especially suitable for applications where the outer contour of the liquid cooling plate needs to be precisely assembled or sealed. When b is slightly less than 90° (e.g., 80° to 89°), it can guide the machining tool to cut along a certain angle, thereby reducing tearing or burr formation on the cross-section and improving the surface quality of the machined surface.

[0058] If b is less than 80°, the excessive tilt of the cut surface will result in uneven thickness distribution of the remaining portion 321, and may even cause problems such as deformation, cracking, or poor edge sealing during the cutting process. If b exceeds 90°, the cutting direction will deviate towards the inner side of the plate, which will weaken the edge strength or cause the welded section 31 to be cut incorrectly. Therefore, by controlling the angle b between the cut surface and the edge within the range of 80° to 90°, it is possible to ensure the operational stability and surface quality of the processing, while also maintaining the integrity and strength of the plate edge at the structural level.

[0059] Additionally, please refer to Figure 6 , Figure 6 This is a top enlarged view of a partial structure of a liquid cooling plate provided in an embodiment of the present invention. In some embodiments, the residual portion 321 may be configured with a gradually increasing width along the direction away from the edge of the liquid cooling plate. That is, as it extends outward from the position near the edge of the liquid cooling plate, the lateral dimension of the residual portion 321 (i.e., the cross-sectional width perpendicular to the welding path direction) gradually widens, forming a flared or wedge-shaped structure.

[0060] During friction stir welding, the needle tip disturbs the surrounding material and causes heat input fluctuations during the withdrawal phase. If the cross-section of the residual portion 321 is too narrow, the heat concentration area may cause microcracks or material warping. By setting a gradually increasing width, stress can diffuse to a wider area, reducing the stress density per unit area of ​​the cross-section. At the same time, the wider end region of the residual portion 321 provides a larger cutting allowance, which can effectively suppress problems such as burrs and fractures caused by processing vibration or warping, thereby forming a more regular cut surface.

[0061] Please see Figure 7 , Figure 7 This is a partial cross-sectional view along the horizontal direction of a novel liquid-cooled plate structure provided by an embodiment of this utility model. In some optimized embodiments, a dedicated exit area 322 may be provided in the lead-out section 32 to clearly define the exit position of the friction stir welding needle, avoiding structural disturbance or stress concentration to the weld section or liquid-cooled cavity during its withdrawal. This exit area 322 is typically located at the far end of the lead-out section 32, forming a functional separation from the welding section 31.

[0062] Specifically, the minimum distance between the exit zone 322 and the junction of the lead-out section 32 and the welding section 31 is defined as L3, and its length is set in this embodiment to satisfy the following range: 0.8D≤L3≤D, where D represents the diameter of the friction stir welding needle.

[0063] When the length of L3 is not less than 0.8D, it ensures that the stirring needle has a sufficient buffer path before withdrawal, allowing for a natural termination of the stirring process and preventing defects such as material accumulation, voids, or metal structure damage at the end of the weld segment. Especially in high-speed stirring welding, if the needle withdrawal action is too close to the weld segment, it can easily cause the keyhole boundary to erode the weld body, negatively impacting the sealing performance of the liquid cooling cavity. By setting L3 ≥ 0.8D, the withdrawal action can be completed independently outside the welding segment 31, ensuring the integrity of the weld structure and a smooth stress transition.

[0064] Meanwhile, to avoid excessive length of the lead-out section 32, which could lead to structural redundancy or material waste, the upper limit of L3 is limited to D. This limitation ensures that the exit area 322 meets the welding buffer requirements without excessive extension, which is beneficial for controlling the compactness of the liquid cooling plate structure.

[0065] Furthermore, in some embodiments, in order to make it easier to identify the withdrawal position of the friction stir welding needle after welding is completed, the surface of the withdrawal area 322 may be designed to be slightly raised relative to the rest of the lead-out section 32, that is, the surface of the withdrawal area 322 protrudes generally from the body surface of the lead-out section 32.

[0066] This protruding structure can be achieved by locally thickening, slightly bulging, or forming an arc surface on the lead-out section 32 before welding, or it can be formed in one step during the pre-processing stage of the sheet metal using methods such as die-cutting or stamping. Its structural height can be set according to the precision of the welding path, typically a micro-scale protrusion of 0.1 mm to 0.5 mm, which will not significantly interfere with the welding trajectory while forming a clearly identifiable marker.

[0067] This structural design allows operators to quickly and intuitively determine the retraction position of the stirring needle and the location of the keyhole after welding, without relying on auxiliary measurements. It is particularly suitable for post-processing techniques such as automated identification, visual positioning, and CNC cutting. In manufacturing scenarios where robots or automated equipment are used for cutting operations, this protruding structure can also serve as a physical positioning reference for the starting point of the processing path, improving cutting accuracy and consistency.

[0068] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0069] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A liquid-cooled plate structure, characterized in that, include: The main body has a flow channel and an opening communicating with the flow channel; The sealing part seals and covers the opening; A welding section is disposed at the mating edge between the main body and the sealing section. The welding section includes a welding segment and a lead-out segment. The welding segment extends along the mating edge and covers the outer periphery of the opening. The lead-out segment is located at the end of the welding segment, and the thickness of the lead-out segment is greater than the thickness of the welding segment.

2. The liquid-cooled plate structure according to claim 1, characterized in that, The length L1 of the lead-out section along the welding direction satisfies: 2D≤L1≤4D, where D is the diameter of the friction stir welding needle.

3. The liquid-cooled plate structure according to claim 1, characterized in that, The thickness T2 of the lead-out section and the thickness T1 of the welding section satisfy the following condition: 2.0≤T2 / T1≤3.

4. The liquid-cooled plate structure according to claim 3, characterized in that, Along the direction away from the welding section, the thickness of the lead-out section gradually increases, and the thickness change angle α satisfies the relationship: 1°≤a≤5°.

5. The liquid-cooled plate structure according to claim 1, characterized in that, The lead-out section includes a residual portion, the welding section extends to the edge of the main body and the sealing portion, the residual portion protrudes from the edge, and the residual portion includes a cutting surface for cutting off the lead-out area of ​​the friction stir welding needle.

6. The liquid-cooled plate structure according to claim 5, characterized in that, The distance between the cut surface and the edge is L2, which satisfies the relationship: 3mm≤L2≤5mm.

7. The liquid-cooled plate structure according to claim 5, characterized in that, The angle between the cut surface and the plane containing the edge is b, satisfying the relationship: 80°≤b≤90°.

8. The liquid-cooled plate structure according to claim 5, characterized in that, The width of the residual portion gradually increases along the direction of extension of the mating edge.

9. The liquid-cooled plate structure according to any one of claims 1 to 8, characterized in that, The lead-out section includes a withdrawal area for withdrawing the friction stir welding needle. The minimum distance L3 between the withdrawal area and the junction of the lead-out section and the welding section satisfies: 0.8D≤L3≤D, where D is the diameter of the friction stir welding needle.

10. The liquid-cooled plate structure according to claim 9, characterized in that, The exit area is provided with a boss structure, the surface of which is higher than the reference plane of the lead-out section.

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