Friction Stir Stationary Shoulder, Friction Stir Welding Tool and Its Usage Method

Abstract

The present invention discloses a friction stir stationary shoulder, a friction stir welding tool and a using method thereof, belonging to the technical field of friction stir welding. Among them, the friction stir stationary shoulder includes a shoulder end face, a material guiding groove, a rear pressing surface and a cutting edge surface. The material guiding groove is in a semi-circular shape in the radial projection plane and is closely arranged in a ring shape behind the outside of the shoulder end face; the rear pressing surface is in a semi-circular shape in the radial projection plane and is closely arranged in a ring shape around the outer periphery of the notch of the material guiding groove, and the shoulder end face protrudes axially from the rear pressing surface; the cutting edge surface is vertically arranged at the front end of the rear pressing surface and is distributed on the opposite sides outside the shoulder end face, and a cutting edge is arranged at the lower end of the cutting edge surface at the outside of the material guiding groove. The friction stir stationary shoulder of the present invention can remove flash online during welding, obtain a weld without flash completely, and has the characteristics of interference avoidance, convenient processing and low price.

Description

Technical Field

[0001] The present invention relates to the technical field of friction stir welding, and in particular, to a friction stir stationary shoulder, a friction stir welding tool and a method for using the same. Background Art

[0002] The stationary shoulder friction stir welding process (SSFSW) is an extended technology of friction stir welding technology. Friction stir welding is a solid-phase welding method, which generally requires a stirring head to penetrate into the plate to be welded, rotate and feed in the XY plane, and rely on friction and deformation to generate heat to make the materials close. The stirring head generally has two key structures, namely the tip part and the shoulder part. During welding, the tip part penetrates into the plate to be welded, and the shoulder part presses tightly on the surface of the plate to be welded. A large amount of heat is generated by the shoulder part during welding, resulting in an uneven temperature field of the weld seam, a relatively high surface temperature, and good fluidity of the surface material, which not only causes serious thermal deformation of the workpiece but also easily causes flash on both sides of the weld seam. Therefore, in order to control excessive heat generation by the shoulder and excessive flash, the stationary shoulder friction stir welding process has emerged. During welding, the shoulder actually remains stationary and only the central tip rotates. The SSFSW process effectively controls material thermal deformation and flash. However, in actual production, due to various factors such as uneven plate thickness and pressure fluctuation, there is still a small amount of flash on both sides of the weld seam of the welded product, and the surface of the welded product cannot reach the state where it can directly enter the next process without grinding. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, an object of the first aspect of the present invention is to provide a friction stir stationary shoulder, which can remove flash online during welding, obtain a weld seam completely free of flash, and has anti-interference, convenient processing and low cost.

[0004] The friction stir stationary shoulder according to an embodiment of the first aspect of the present invention includes:

[0005] The shoulder end face;

[0006] The material guiding groove, which is semi-circular and closely arranged in a ring shape on the outer rear side of the shoulder end face in the radial projection plane;

[0007] The rear pressing surface, which is semi-circular and closely arranged in a ring shape on the outer periphery of the notch of the material guiding groove in the radial projection plane, and the shoulder end face protrudes axially from the rear pressing surface;

[0008] The cutting edge surface, which is vertically arranged at the front end of the rear pressing surface and distributed on the relative outer sides of the shoulder end face, and a cutting edge is arranged at the lower end of the cutting edge surface outside the material guiding groove.

[0009] The friction stir stationary shoulder according to the first aspect embodiment of the present invention has the following advantages: on the one hand, through the material guiding groove and the back pressing surface, the warped and lifted burrs overflowing from the outer peripheral edge of the shoulder end face can be restricted. The material guiding groove can effectively capture the warped and lifted burrs at the outer peripheral edge immediately behind the shoulder end face. The cutting edge can synchronously and effectively cut off the overflowing burrs at the radial outside of the front groove diameter of the material guiding groove in real time online. The back pressing surface can effectively flatten the warped and lifted burrs captured by the material guiding groove and the part after the burrs are cut off by the cutting edge. Thus, the obtained weld seam is completely burr-free and the weld seam surface is smooth, saving the post-welding product the burr removal and grinding process. On the other hand, the friction stir stationary shoulder is small in volume, will not interfere with other components, has interference avoidance, is convenient to process, and is cheap.

[0010] In some embodiments, the axial distance between the shoulder end face and the back pressing surface is 0.25 - 0.5 mm.

[0011] In some embodiments, the groove depth of the material guiding groove is 0.5 - 1.5 mm, and the groove width of the material guiding groove is 0.6 - 1.5 mm.

[0012] In some embodiments, the minimum length of the cutting edge is 0.4 mm.

[0013] In some embodiments, the cutting edge is directly formed at the lower edge of the cutting edge surface; or, a blade is fixed on the cutting edge surface, and the cutting edge of the blade is the cutting edge.

[0014] In some embodiments, an open space area is formed on the front side of the cutting edge surface.

[0015] The second aspect of the present invention proposes a friction stir welding tool.

[0016] The friction stir welding tool according to the second aspect embodiment of the present invention includes the friction stir stationary shoulder according to the first aspect embodiment of the present invention.

[0017] Since the friction stir welding tool according to the second aspect embodiment of the present invention adopts the friction stir stationary shoulder according to the first aspect embodiment of the present invention, therefore, the friction stir welding tool according to the second aspect embodiment of the present invention has basically the same technical effects as the friction stir stationary shoulder according to the first aspect embodiment of the present invention.

[0018] The third aspect of the present invention proposes a using method of a friction stir stationary shoulder.

[0019] The using method of the friction stir stationary shoulder according to the third aspect embodiment of the present invention includes the following steps:

[0020] S1: Mounting the stirring head and the friction stirring stationary shoulder of the first embodiment of the present invention on the welding equipment;

[0021] S2: making the cutting edge face the welding direction, and making the stirring head and the stirring friction static shoulder maintain a predetermined inclination angle in the opposite direction of the welding direction;

[0022] S3: Start friction stir welding, rotate the stirring needle of the stirring head and penetrate into the product to be welded, and at the same time press the shoulder end face into the product to be welded to a predetermined depth, so that there is a gap between the rear pressure surface and the original surface of the product to be welded. During the welding process, the cutting edge surface is always facing the welding direction, the material guide groove captures the warped burrs overflowing from the outer peripheral edge of the shoulder end face, the cutting edge cuts off the overflowing burrs located radially outside the front end notch of the material guide groove, and the rear pressure surface flattens the burrs captured by the material guide groove and the part after the burrs are cut off by the cutting edge.

[0023] The method for using the stirring friction stationary shoulder of the third aspect of the embodiment of the present invention has the following advantages: the material guide groove and the rear pressure surface can limit the warped burrs overflowing from the peripheral edge of the shoulder end face, the material guide groove can effectively capture the warped burrs at the peripheral edge immediately behind the shoulder end face, the cutting edge can synchronously and effectively cut off the overflowing burrs located radially outside the front end groove of the material guide groove online in real time, the rear pressure surface can effectively flatten the warped burrs captured by the material guide groove and the area after the burrs are cut off by the cutting edge, thereby, the obtained weld is completely burr-free and the weld surface is smooth, so that the post-weld product eliminates the burr removal grinding process.

[0024] In some embodiments, the distance between the cutting edge and the original surface of the product to be welded is 0.1-0.2 mm.

[0025] In some embodiments, the stationary shoulder rotates under the control of the tangential following functional module of the welding equipment so that the cutting edge surface always faces the welding direction.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0028] Figure 1 A three-dimensional schematic diagram of one orientation of the friction stir stationary shoulder of the present invention;

[0029] Figure 2a forFigure 1 The enlarged schematic diagram at A in the middle;

[0030] Figure 2b It is a partial effect diagram of the friction stir stationary shoulder of the present invention;

[0031] Figure 3 A three-dimensional schematic diagram of another orientation of the friction stir stationary shoulder of the present invention;

[0032] Figure 4 This is a schematic diagram of an application scenario of the friction stir stationary shoulder of the present invention;

[0033] Figure 5 Schematic diagram of the application scenario of conventional friction stir stationary shoulder.

[0034] Reference numerals:

[0035] Stirring friction stationary shaft shoulder 1000; shaft shoulder end face 1; material guide groove 2; rear pressure surface 3; cutting edge surface 4; cutting edge 401; stirring head 2000. DETAILED DESCRIPTION

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0037] Combine the following Figures 1 to 4 The friction stir stationary shoulder 1000 , the friction stir welding tool and the method for using the friction stir stationary shoulder 1000 according to the embodiments of the present invention are described.

[0038] like Figures 1 to 4 As shown, the first aspect of the present invention proposes a friction stirring stationary shoulder 1000 .

[0039] According to the first embodiment of the present invention, the friction stirring stationary shoulder 1000 (reference Figures 1 to 4 ), at the conventional stationary shoulder (reference Figure 5 ), including a shaft shoulder end face 1, a material guide groove 2, a rear pressure surface 3 and a cutting edge surface 4.

[0040] The shaft shoulder end face 1 is as complete as the conventional static shaft shoulder end face and is in a complete ring shape. The shaft shoulder end face 1 is slightly pressed into the product to be welded during welding, that is, the shaft shoulder end face 1 presses the surface position of the product to be welded opposite to the shaft shoulder end face 1 downward by a small amount of displacement, and then the product to be welded will overflow with a raised flash at the peripheral edge of the shaft shoulder end face 1.

[0041] The guide groove 2 is semi-circular on the radial projection surface and is arranged adjacent to the outer rear of the shaft shoulder end face 1. In this way, during welding, the guide groove 2 is located behind the welding and can capture or limit the flash that rises behind the outer rear of the shaft shoulder end face 1.

[0042] The rear pressure surface 3 is semi-circular on the radial projection surface and is closely arranged on the outer periphery of the slot of the guide groove 2, so that the rear pressure surface 3 is separated from the shaft shoulder end face 1 by the guide groove 2 in the radial direction, and the distance between the rear pressure surface 3 and the shaft shoulder end face 1 in the radial direction is the slot width of the guide groove 2; the shaft shoulder end face 1 protrudes from the rear pressure surface 3 in the axial direction, that is, the rear pressure surface 3 is higher than the shaft shoulder end face 1 in the vertical direction, and forms a step difference with the shaft shoulder end face 1, and the step difference is determined by the welding thinning amount of the product to be welded (that is, the position of the weld after welding of the product to be welded becomes thinner than before welding). During welding, the rear pressure surface 3 is at the rear of the welding, and the rear pressure surface 3 does not press into the original surface of the product to be welded, and maintains a suitable gap with the original surface of the product to be welded. The rear pressure surface 3 can limit the flash at the surface position opposite to the rear pressure surface 3 and flatten the warped flash captured by the guide groove 2. It should be noted that if the rear pressure surface 3 is pressed into the original surface of the product to be welded, although it has little effect on the function of removing burrs, it will have an adverse effect on the appearance of the product. If the welding equipment uses a constant pressure welding process, it will also cause certain pressure fluctuations, affecting the welding process.

[0043] The cutting edge surface 4 is vertically arranged at the front end of the rear pressure surface 3 and distributed on the opposite sides of the shoulder end surface 1. The lower end of the cutting edge surface 4 is provided with a cutting edge 401 at the outer side of the material guide groove 2. During welding, the cutting edge surface 4 is always facing the welding direction, that is, facing the welding direction. The cutting edge 401 at the lower end of the cutting edge surface 4 can cut off the overflow flash located at the radial outer side of the front end notch of the material guide groove 2 in real time online, and the part after the flash is cut off by the cutting edge 401 is flattened by the subsequent rear pressure surface 3.

[0044] According to the stir friction stationary shoulder 1000 of the first aspect of the present invention, when in use, the stirring head 2000 and the stir friction stationary shoulder 1000 are first installed on the welding equipment; then the cutting edge surface 4 is made to face the welding direction, and the stirring head 2000 and the stir friction stationary shoulder 1000 are kept at a predetermined inclination angle in the opposite direction of the welding direction; then, the stir friction welding is started, the stirring needle of the stirring head 2000 is rotated and inserted into the product to be welded, and at the same time, the shoulder end face 1 is pressed into the product to be welded to a predetermined depth, so that a suitable gap is maintained between the rear pressure surface 3 and the original surface of the product to be welded. During the welding process, the cutting edge surface 4 is always facing the welding direction, the guide groove 2 captures the warped flying edges overflowing from the outer peripheral edge of the shoulder end face 1, and the cutting edge 401 cuts off the overflowing flash located at the radial outer side of the front end notch of the guide groove 2 in real time online, and the rear pressure surface 3 flattens the flash captured by the guide groove 2 and the part after the flash is cut off by the cutting edge 401, thereby obtaining a weld with no flash after the stir friction welding, and the weld surface is smooth.

[0045] The friction stir stationary shoulder 1000 according to the embodiment of the first aspect of the present invention has the following advantages: on the one hand, through the material guiding groove 2 and the rear pressing surface 3, the warped and lifted burrs overflowing from the outer periphery of the shoulder end face 1 can be restricted. The material guiding groove 2 can effectively capture the warped and lifted burrs at the outer periphery immediately behind the shoulder end face 1. The cutting edge 401 synchronously and effectively cuts off the overflowing burrs at the radial outside of the front groove diameter of the material guiding groove 2 in real time. The rear pressing surface 3 can effectively flatten the warped and lifted burrs captured by the material guiding groove 2 and the part after the burrs are cut off by the cutting edge 401. Thus, the obtained weld seam is completely burr-free and the surface of the weld seam is smooth, saving the post-welding product the burr removal and grinding process; on the other hand, the friction stir stationary shoulder 1000 is small in volume, will not interfere with other components, has interference avoidance, is convenient to process, and is inexpensive.

[0046] In some embodiments, the axial distance between the shoulder end face 1 and the rear pressing surface 3 is 0.25 - 0.5 mm. Since the thinning amount during welding of the product to be welded is usually required to be 0.2 - 0.3 mm, and it must be ensured that during welding, the shoulder end face 1 is slightly pressed into the product to be welded, for example, slightly pressed into the product to be welded by about 0.1 - 0.2 mm, and the rear pressing surface 3 is not pressed into the original surface of the product to be welded, and a proper gap such as 0.1 - 0.2 mm is maintained with the original surface of the product to be welded. If the rear pressing surface 3 is pressed into the original surface of the product to be welded, although the influence on the function of removing burrs is small, it will have an adverse effect on the appearance of the product, and if the welding equipment uses a constant pressure welding process, it will also cause a certain pressure fluctuation, affecting the welding process. Therefore, it is more reasonable to determine the axial distance between the shoulder end face 1 and the rear pressing surface 3 to be 0.25 - 0.5 mm.

[0047] In some embodiments, the groove depth of the material guiding groove 2 is 0.5 - 1.5 mm, and the groove width of the material guiding groove 2 is 0.6 - 1.5 mm. According to the welding process and the interference avoidance requirements of the working conditions, the groove depth and width of the material guiding groove 2 can be adjusted to a certain extent. If the overflowing burrs are larger, the larger values of the depth and width can be taken; if the overflowing burrs are smaller, the smaller values of the depth and width can be taken. The burrs will have a certain warping during the welding process. Once the burrs warp, the material guiding groove 2 can capture the warped burrs, and the rear pressing surface 3 flattens the warped and lifted burrs captured by the material guiding groove 2. Since the cutting edge 401 maintains a proper gap with the original surface of the product to be welded during operation, this gap can be 0.1 - 0.2 mm. If the warped burrs exceed the radial outside of the front groove diameter of the material guiding groove 2 and cannot be captured by the material guiding groove 2, they are cut off by the cutting edge 401, and the rear pressing surface 3 flattens the part after being cut off.

[0048] In some embodiments, the minimum length of the cutting edge 401 is 0.4 mm, which can ensure that the overflowing burrs at the radial outside of the front groove diameter of the material guiding groove 2 can be completely cut off.

[0049] In some embodiments, the cutting edge 401 is directly formed at the lower end edge of the cutting edge surface 4, which is convenient for processing and has a simple structure. Alternatively, a blade is fixed on the cutting edge surface 4, and the cutting edge of the blade is the cutting edge 401. For example, a threaded hole is formed on the cutting edge surface 4, and the blade is fixed on the cutting edge surface 4 by passing a fixing screw through the blade and connecting it to the threaded hole, which is convenient for processing and has a simple structure.

[0050] In some embodiments, as Figures 2a to 3 shown, an open space area is formed on the front side of the cutting edge surface 4. This open space area is conducive to the timely discharge of the removed flash, without affecting the normal operation of the stationary shoulder.

[0051] The second aspect of the present invention proposes a friction stir welding tool.

[0052] The friction stir welding tool according to the embodiment of the second aspect of the present invention includes the friction stir stationary shoulder 1000 of the embodiment of the first aspect of the present invention.

[0053] Since the friction stir welding tool of the embodiment of the second aspect of the present invention adopts the friction stir stationary shoulder 1000 of the embodiment of the first aspect of the present invention, therefore, the friction stir welding tool of the embodiment of the second aspect of the present invention has basically the same technical effects as the friction stir stationary shoulder 1000 of the embodiment of the first aspect of the present invention.

[0054] The third aspect of the present invention proposes a method for using the friction stir stationary shoulder 1000.

[0055] The method for using the friction stir stationary shoulder 1000 according to the embodiment of the third aspect of the present invention includes the following steps:

[0056] S1: Cooperatively install the friction stir head 2000 and the friction stir stationary shoulder 1000 of the embodiment of the first aspect of the present invention on the welding equipment; specifically, the friction stir stationary shoulder 1000 is coaxially clamped on the outer periphery of the friction stir head 2000, and the stirring pin of the friction stir head 2000 extends out of the shoulder end face 1. The friction stir head 2000 is clamped to the equipment tool shank, the tool shank is connected to the main shaft rotor, and it rotates at a certain speed during operation. The friction stir stationary shoulder 1000 is installed on the bushing, and the bushing is clamped on the main shaft housing.

[0057] S2: As Figure 2b and Figure 4As shown, make the cutting edge surface 4 face the welding direction, and the material guiding groove 2 and the rear pressing surface 3 are located behind the welding position. This is beneficial during the welding process, as the material guiding groove 2 and the rear pressing surface 3 can restrict the warped and lifted burrs overflowing from the outer peripheral edge of the shoulder end face 1. The material guiding groove 2 can effectively capture the warped and lifted burrs at the outer peripheral edge immediately behind the shoulder end face 1. The cutting edge 401 synchronously and effectively cuts off the overflowing burrs located radially outside the front groove diameter of the material guiding groove 2 in real time. The rear pressing surface 3 can effectively flatten the warped and lifted burrs captured by the material guiding groove 2 and the part after the burrs are cut off by the cutting edge 401. Also, make the stirring head 2000 and the friction stir stationary shoulder 1000 maintain a predetermined inclination angle in the opposite direction of the welding direction. This is beneficial for the smoothness of the weld seam and also meets the requirements of the friction stir welding process.

[0058] S3: Start performing friction stir welding. Rotate the stirring pin of the stirring head 2000 and plunge it into the product to be welded. At the same time, press the shoulder end face 1 into the product to be welded to a predetermined depth, so that there is a gap between the rear pressing surface 3 and the original surface of the product to be welded, to ensure that the rear pressing surface 3 does not scratch the product to be welded and the welded seam that has been welded. During the welding process, make the cutting edge surface 4 always face the welding direction. The material guiding groove 2 captures the warped and lifted burrs overflowing from the outer peripheral edge of the shoulder end face 1. The cutting edge 401 cuts off the overflowing burrs located radially outside the front groove diameter of the material guiding groove 2. The rear pressing surface 3 flattens the burrs captured by the material guiding groove 2 and the part after the burrs are cut off by the cutting edge 401.

[0059] The method of using the friction stir stationary shoulder 1000 in the third aspect embodiment of the present invention has the following advantages: The warped and lifted burrs overflowing from the outer peripheral edge of the shoulder end face 1 can be restricted by the material guiding groove 2 and the rear pressing surface 3. The material guiding groove 2 can effectively capture the warped and lifted burrs at the outer peripheral edge immediately behind the shoulder end face 1. The cutting edge 401 synchronously and effectively cuts off the overflowing burrs located radially outside the front groove diameter of the material guiding groove 2 in real time. The rear pressing surface 3 can effectively flatten the warped and lifted burrs captured by the material guiding groove 2 and the part after the burrs are cut off by the cutting edge 401. Thus, the obtained weld seam is completely burr-free and the weld seam surface is smooth, eliminating the need for the post-welding product to undergo the burr removal and grinding process.

[0060] In some embodiments, the predetermined inclination angle is 2° - 3°. This is beneficial for the smoothness of the weld seam and also meets the requirements of the friction stir welding process.

[0061] In some embodiments, the distance between the cutting edge 401 and the original surface of the product to be welded is 0.1 - 0.2 mm. In this way, the cutting edge 401 will not produce scratches on the original surface of the product to be welded and the weld seam, and at the same time, it can effectively cut off the overflowing burrs located radially outside the front groove diameter of the material guiding groove 2.

[0062] In some embodiments, the stationary shoulder rotates under the control of the tangential following function module of the welding device, so that the cutting edge surface 4 is always facing the welding direction. During the welding feed process, by controlling the rotation of the stationary shoulder through the tangential following function module, it can be ensured that even when the friction stir welding head 2000 and the friction stir stationary shoulder 1000 turn and weld on the XY plane, the cutting edge surface 4 of the friction stir stationary shoulder 1000 always faces the front of the welding, and the material guiding groove 2 and the back pressure surface 3 are always at the back of the welding, maintaining this positional relationship. The main shaft of the welding device rotates and feeds synchronously on the XY plane to complete friction stir welding, ensuring that the obtained weld seam has no flash and the weld surface is smooth.

[0063] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0064] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A friction stir stationary shoulder, characterized in that: include: Shoulder end face; A material guide groove, which is semi-circular in shape on a radial projection surface and is arranged adjacent to the outer rear of the shaft shoulder end surface; A rear pressure surface, which is semi-annular in radial projection and is closely arranged around the outer periphery of the slot of the material guide slot, and the shaft shoulder end surface protrudes from the rear pressure surface in the axial direction; The cutting edge surface is vertically arranged at the front end of the rear pressure surface and distributed outside the opposite sides of the shoulder end surface. The lower end of the cutting edge surface is provided with a cutting edge at the outer side of the material guide groove.

2. The friction stir stationary shoulder according to claim 1, characterized in that: The axial distance between the shaft shoulder end face and the rear pressure surface is 0.25-0.5 mm.

3. The friction stir stationary shoulder according to claim 1, characterized in that: The groove depth of the material guide groove is 0.5-1.5 mm, and the groove width of the material guide groove is 0.6-1.5 mm.

4. The friction stir stationary shoulder according to claim 1, characterized in that: The minimum length of the cutting edge is 0.4 mm.

5. The friction stir stationary shoulder according to claim 1, characterized in that: The cutting edge is directly formed at the lower end edge of the cutting edge surface; or, a blade is fixed on the cutting edge surface, and the blade edge of the blade is the cutting edge.

6. The friction stir stationary shoulder according to claim 1, characterized in that: The front side of the cutting edge surface forms an open space area.

7. A friction stir welding tool, characterized in that: It comprises the friction stirring stationary shoulder as described in any one of claims 1 to 6.

8. A method for using a friction stir stationary shoulder, characterized in that: The steps include: S1: Mounting the stirring head and the friction stirring stationary shoulder according to any one of claims 1 to 6 on the welding equipment; S2: making the cutting edge face the welding direction, and making the stirring head and the friction stirring static shoulder maintain a predetermined inclination angle in the opposite direction of the welding direction; S3: Start friction stir welding, rotate the stirring needle of the stirring head and penetrate into the product to be welded, and at the same time press the shoulder end face into the product to be welded to a predetermined depth, so that there is a gap between the rear pressure surface and the original surface of the product to be welded. During the welding process, the cutting edge surface is always facing the welding direction, the material guide groove captures the warped burrs overflowing from the outer peripheral edge of the shoulder end face, the cutting edge cuts off the overflowing burrs located radially outside the front end notch of the material guide groove, and the rear pressure surface flattens the burrs captured by the material guide groove and the part after the burrs are cut off by the cutting edge.

9. The method for using the friction stir stationary shoulder according to claim 8, characterized in that: The distance between the cutting edge and the original surface of the product to be welded is 0.1-0.2 mm.

10. The method for using the friction stir stationary shoulder according to claim 8, characterized in that: The stationary shaft shoulder rotates under the control of the tangential following functional module of the welding equipment, so that the cutting edge surface always faces the welding direction.

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