A friction stir welding head

Abstract

This invention provides a friction stir welding head, comprising a main body having a central axis defining a downward and an upward direction. The main body has a shoulder with a relatively small diameter along the downward direction of the central axis, and a flash cutter is provided on the outer peripheral wall of the shoulder. When the main body rotates, the flash generated by friction stir welding can be removed by the flash cutter. The cutting edge of the flash cutter is positioned in a direction parallel to the central axis. Correspondingly, a chip removal groove is provided on the main body adjacent to the flash cutter. The chip removal groove includes a first groove wall, which is collinear with the cutting edge of the flash cutter. This friction stir head can achieve simultaneous welding and milling, resulting in a weld joint surface free of flash and burrs. Furthermore, by aligning the first groove wall of the chip removal groove with the cutting edge of the flash cutter, the flash removed by the flash cutter can be discharged upwards along the first groove wall, preventing flash accumulation near the shoulder and improving welding efficiency.

Description

Technical Field

[0001] This utility model relates to the field of friction stir welding technology, and in particular to a friction stir welding head capable of removing burrs. Background Technology

[0002] Friction stir welding (FSW) is a new solid-state joining technology primarily used for joining non-ferrous metals such as aluminum and magnesium alloys. The basic principle of FSW, as described in patent US5460317, involves a cylindrical stirring head with shoulders and a stirring pin that rotates and inserts into the workpieces. Friction between the stirring head and the workpieces generates frictional heat, causing the material to thermoplasticize. As the stirring tool moves forward along the interface, the thermoplasticized material transfers from the front to the rear of the stirring head, achieving a solid-state connection between the workpieces under the action of the stirring tool. The advantages of FSW include the elimination of the need for shielding gas, filler wire, and solder; simple pre- and post-weld treatment; good mechanical properties of the resulting weld; absence of casting defects similar to those found in fusion welds; and ease of operation. Therefore, FSW technology is now widely used in industries such as shipbuilding, aerospace, rail transportation, road transportation, and automobile manufacturing.

[0003] However, during friction stir welding, due to the inherent height difference between the two sides of the weld seam caused by the welding material itself, or excessive downward pressure on the shoulder of the stirring tool during the welding operation, the softened material is squeezed out from the shoulder when the stirring tool rotates at high speed, forming obvious rough burrs and flash on both sides of the weld seam, making effective welding impossible or resulting in obvious cracks and defects after welding.

[0004] To eliminate the aforementioned burrs and flash, Chinese utility model patent No. 202321275432.4 (authorization announcement No. CN219818373U) discloses a "friction stir welding head". This friction stir welding head adds a milling cutter edge to the outer surface of the shoulder, so that the milling cutter and the stirring head are integrated into one. This allows the milling cutter edge to rotate synchronously when the friction stir welding head is rotating, thereby milling off the flash and burrs generated during friction stir.

[0005] While the aforementioned friction stir welding head can remove burrs and flash, it still has the following problems: First, with the drain groove located between the cutter edge and the outer surface of the shaft shoulder, the burrs and flash cut by the cutter edge cannot directly enter the drain groove for timely cleaning, easily accumulating near the shaft shoulder or in the drain groove. Second, since the flash is formed by the extrusion of molten material, when the cutter removes the flash during friction stir, incompletely solidified molten material can easily adhere to the cutter surface, affecting the normal cutting operation. In summary, the existing friction stir welding head still needs improvement. Summary of the Invention

[0006] The first technical problem to be solved by this utility model is to provide a stirring friction welding head that can remove burrs while welding and avoid material accumulation, in view of the above-mentioned existing technology.

[0007] The second technical problem to be solved by this utility model is to provide a friction stir welding head that can prevent molten material from adhering to the surface of the milling cutter, in view of the above-mentioned existing technology.

[0008] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: The friction stir welding head includes a main body, which has a central axis defining a relative downward direction and an upward direction. The main body is provided with a shoulder with a relatively small diameter in the downward direction along the central axis, and a flash cutter is provided on the outer peripheral wall of the shoulder. When the main body rotates, the flash generated by friction stir welding can be removed by the flash cutter. The flash cutter is characterized in that the cutting edge of the flash cutter is arranged in a direction parallel to the central axis. Correspondingly, a chip removal groove is provided on the main body adjacent to the flash cutter. The chip removal groove includes a first groove wall, which is collinear with the cutting edge of the flash cutter.

[0009] To further prevent the accumulation of burrs removed by the burr cutter near the shoulder, preferably, the main body is rotatable about the central axis in the rotational direction. Along the rotational direction, the chip removal groove is located in front of the cutting edge of the burr cutter. The chip removal groove also includes a second groove wall located in front, extending obliquely upward from bottom to top. By placing the chip removal groove in front of the cutting edge of the burr cutter and including the second groove wall, when burrs removed by the burr cutter tend to accumulate at the shoulder, the burrs can be discharged upward along the second groove wall, thereby preventing the accumulation of burrs near the shoulder.

[0010] Furthermore, the first and second walls of the chip removal groove form a sideways V-shape, with the common end of the first and second walls located at the middle tip of the V-shape, and the opening of the V-shape facing downwards along the central axis. This V-shaped chip removal groove design creates a space for chip removal between the first and second walls, with the V-shape opening facing downwards. Flash removed by the flash removal tool can enter this space from the opening. Flash removed by the cutting edge of the flash removal tool is discharged upwards along the first wall, while some flash that accumulates near the shoulder for timely upward discharge is discharged upwards along the second wall, thus effectively removing flash chips.

[0011] To address the second technical problem mentioned above, preferably, the flash tool further includes a guide wall connected to the rear end of the flash tool and opposite to the cutting edge. This guide wall directs the molten material overflowing from the friction stir welding away from the cutting edge. In this way, the overflowing molten material can be directed away from the cutting edge along the guide wall, preventing the molten material from sticking to the tool and achieving a well-formed weld surface.

[0012] In order to guide the molten material away from the cutting edge, preferably, the guide wall is located behind the cutting edge along the direction of rotation and extends gradually backward from bottom to top.

[0013] To ensure the effectiveness of the flash removal tool, preferably, the lower end of the flash removal tool extends a predetermined distance S above the lower end face of the shoulder. This predetermined distance S corresponds to the weld depth formed by the welding process. If the predetermined distance S is too large, the flash cannot be completely removed; if the predetermined distance S is too small, the flash removal tool will mill the welding material as the friction stir welding head rotates. Therefore, setting the predetermined distance S to be the same as the weld depth ensures that the flash is completely removed while minimizing milling of the welding material.

[0014] To reduce flash, preferably, the lower end face of the shoulder is concave to form a recess for accommodating molten material, and a stirring head extends downward from the center of the recess along the central axis. This recess design concentrates the molten welding material, allowing more welding material to be pressed into the weld bead, reducing the weld depth. Simultaneously, because more molten welding material is pressed into the weld bead, excess molten material overflow is reduced, thus minimizing flash.

[0015] To improve welding quality, preferably, the longitudinal cross-sectional width of the stirring head gradually decreases from top to bottom along the central axis. Designing the stirring head as a cone shape with a thicker root and a thinner tip has the following advantages: First, it can suppress breakage of the stirring head at the root; second, it can generate material flow towards the lower side, forming good mixing; third, due to the thinner tip, the weld bead generated by the passage of the stirring head is smaller, thereby suppressing the formation of defects near the tip of the stirring head.

[0016] To improve the stirring speed, preferably, the stirring head has at least two resistance surfaces distributed circumferentially, and on any cross-section of the stirring head, the distance between the resistance surface and the central axis is less than the radius of the stirring head. This design of the resistance surfaces increases the resistance when the stirring head rotates, thereby increasing the stirring speed.

[0017] Compared with the prior art, the advantages of this utility model are as follows: the friction stirring head of this utility model can achieve simultaneous welding and milling, and the surface of the welded joint is free of burrs and flash. Furthermore, the first groove wall of the chip removal groove is set collinearly with the cutting edge of the burr removal tool, so that the burrs removed by the burr removal tool can be discharged upward along the first groove wall, avoiding the accumulation of burrs near the shoulder and improving welding efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;

[0019] Figure 2 for Figure 1 Enlarged view of point A (dashed arrows indicate the chip removal path of the burr);

[0020] Figure 3 This is a cross-sectional schematic diagram of an embodiment of the present utility model;

[0021] Figure 4 for Figure 3 Enlarged view of point C in the middle;

[0022] Figure 5 This is a bottom view of an embodiment of the present invention. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1-5 The figure shown is a preferred embodiment of the present invention.

[0025] This embodiment of the friction stir welding head includes a main body 1, which has a central axis B defining a downward direction DF and an upward direction DR. The main body 1 can rotate around the central axis B in the rotational direction R. The main body 1 has a shoulder 2 with a relatively small diameter along the downward direction DF of the central axis B. A stirring head 5 is provided on the shoulder 2 along the downward direction DF of the central axis B. A flash cutter 3 is provided on the outer periphery of the shoulder 2. When the main body 1 rotates, the flash generated by friction stir welding can be removed by the flash cutter 3. This friction stir welding head can achieve milling while welding, and the weld joint surface is free of flash and burrs, eliminating the need for post-weld flash grinding of traditional stirring heads, reducing production costs and improving production efficiency. In addition to providing the flash removal cutter 3, this application more importantly explains how to prevent the removed flash from accumulating on the shoulder 2 and how the generated flash adheres to the flash cutter 3.

[0026] Specifically, in order to remove the flash from the flash cutter 3 in a timely manner and avoid material accumulation, this embodiment is provided with a chip discharge groove 4, which is used to discharge the chips generated when the flash and burrs are removed by the flash cutter 3.

[0027] For the specific structure of chip removal groove 4, please refer to [link / reference]. Figure 1-2 The chip removal groove 4 is formed on the main body 1 and is located adjacent to the flash tool 3. Specifically, the chip removal groove 4 is located in front of the cutting edge 31 of the flash tool 3 along the rotation direction R of the main body 1. The cutting edge 31 of the flash tool 3 is arranged in a direction parallel to the central axis B, and the chip removal groove 4 includes a first groove wall 41 arranged collinearly with the cutting edge 31 of the flash tool 3, and a second groove wall 42 located in front of the first groove wall 41. The second groove wall 42 extends obliquely upward from bottom to top. The first groove wall 41 and the second groove wall 42 form a sideways V-shape. The common end of the first groove wall 41 and the second groove wall 42 is located at the middle tip of the V-shape, and the opening 43 of the V-shape faces the downward direction DF of the central axis B. In use, since the first groove wall 41 and the cutting edge 31 of the flash tool 3 are collinear, the flash can be directly discharged upward along the first groove wall 41 after being cut off by the cutting edge 31, avoiding the accumulation of flash near the shoulder 2 and improving welding efficiency. Even if some flash fails to enter the chip removal groove 4 in time and is discharged along the first groove wall 41 and accumulates near the shoulder 2, it can enter the chip removal groove 4 from the V-shaped downward DF opening 43 and be discharged upward along the second groove wall 42, thereby effectively discharging the flash and avoiding the accumulation of flash near the shoulder 2.

[0028] During friction stir welding, some molten welding material overflows. This overflowing molten welding material, before it has completely cooled and solidified (i.e., when the welding material is in a highly elastic or viscous state), can adhere to the flash cutter 3, affecting the welding quality. To avoid this adhesion phenomenon, this embodiment features a special design for the flash cutter 3. See details... Figure 1-2 The flash cutter 3 also includes a guide wall 32 connected to its rear end and opposite to the cutting edge 31. The guide wall 32 can guide the molten material overflowing from the friction stir welding away from the cutting edge 31. Along the rotation direction R, the guide wall 32 is located behind the cutting edge 31 and extends gradually backward from bottom to top, so that the overflowing molten material can be guided away from the cutting edge 31 along the guide wall 32, avoiding the phenomenon of molten material sticking to the cutter, so as to obtain a well formed weld surface.

[0029] Furthermore, since friction stir welding is achieved by inserting a stirring head into the welding material and rotating it to melt the welding material, and then applying pressure with the shoulder 2 to forge the welding material, a weld of a certain depth will remain after welding. In order to effectively remove burrs, the lower end of the burr cutter 3 in this embodiment is positioned a preset distance S above the lower end face of the shoulder 2. If this preset distance S is greater than the depth of the weld, the burrs cannot be completely removed, and even after milling with the burr cutter 3, burrs will still remain. If the preset distance S is less than the depth of the weld, the welding material will be milled while removing the burrs. Therefore, in this embodiment, the preset distance S is set to be the same as the depth of the weld formed by welding, thereby ensuring that the burrs are completely removed while minimizing the milling of the welding material. For example, when the depth of the weld is 0.2 mm, it is optimal to position the burr cutter 3 0.2 mm above the lower end face of the shoulder 2.

[0030] This embodiment also makes special improvements to shoulder 2 to reduce burrs. See details. Figure 3-4 In this embodiment, the lower end face of the shoulder 2 is concave to form a recess 21 for accommodating molten material, and the stirring head 5 extends downward along the central axis B from the center of the recess 21 in the direction DF. The design of this recess 21 concentrates the molten welding material, allowing more welding material to be pressed into the weld bead, reducing the weld depth. Simultaneously, because more molten welding material is pressed into the weld bead, excess molten material overflow is reduced, minimizing flash. The greater the depth and width of the recess 21, the more molten material it can accommodate, extending the single pressing time and improving welding efficiency. It also better suppresses excess molten material overflow, reducing flash. However, if the depth and width are too large, it will affect the weld quality, making effective welding impossible or resulting in weld defects. In this embodiment, to minimize flash while ensuring welding quality, the depth of the recess 21 is limited to 0.7 mm and the diameter to 10 mm.

[0031] Finally, the structure of the stirring head 5 will be described. See [link / reference] Figure 4 In this embodiment, the longitudinal cross-sectional width of the stirring head 5 gradually decreases from top to bottom along the central axis B. That is, the stirring head 5 is designed as a cone shape with a thicker root and a thinner tip. This design has the following advantages: First, it can suppress breakage of the stirring head 5 at the root; second, it can generate material flow towards the lower side, forming good mixing; third, because the tip is thinner, the weld bead generated by the passage of the stirring head 5 is smaller, thereby suppressing the formation of defects near the tip of the stirring head 5. (See also...) Figure 5The root diameter d1 and shoulder diameter d2 of the stirring head 5 satisfy the ratio d1∶d2=1∶1.5. Compared to the traditional friction stir welding head where the root diameter of the stirring head 5 and the shoulder diameter of the shoulder 2 are 1∶2, this ratio increases the root diameter d1 of the stirring head 5, thereby increasing its stirring speed, improving its crushing function, and reducing internal defects in the welded material. Furthermore, the stirring head 5 has three resistance surfaces 51 distributed circumferentially. On any cross-section of the stirring head 5, the distance between the resistance surface 51 and the central axis B is less than the radius of the stirring head 5. This design of the resistance surface 51 increases the resistance during the rotation of the stirring head 5, thereby further improving the stirring speed.

Claims

1. A friction stir welding head comprising a body portion (1) having a central axis (B) defining a downward direction (DF) and an upward direction (DR), said body portion (1) being provided with a shoulder portion (2) of relatively small diameter in the downward direction (DF) along the central axis (B) and being provided with a flash tool (3) on the outer peripheral wall of said shoulder portion (2), the flash generated by the friction stir welding being removable by said flash tool (3) when said body portion (1) is rotating, characterized in that: The cutting edge (31) of the flash cutter (3) is arranged in a direction parallel to the center axis (B), and a chip groove (4) is arranged on the main body (1) adjacent to the flash cutter (3), the chip groove (4) comprises a first groove wall (41) arranged in line with the cutting edge (31) of the flash cutter (3).

2. The friction stir welding tool according to claim 1, wherein: The main body (1) can rotate around the center axis (B) in the rotation direction (R), and the chip groove (4) is located on the front side of the cutting edge (31) of the flash cutter (3) along the rotation direction (R), and the chip groove (4) further comprises a second groove wall (42) located on the front side, which extends upward from bottom to top.

3. The friction stir welding tool according to claim 2, wherein: The first groove wall (41) and the second groove wall (42) of the chip groove (4) form a side V-shaped type, the joint end of the first groove wall (41) and the second groove wall (42) is located at the middle tip of the V-shaped type, and the opening part (43) of the V-shaped type faces the downward direction (DF) of the center axis (B).

4. The friction stir welding tool according to any one of claims 1 to 3, characterized in that: The flash cutter (3) further comprises a guide wall (32) connected to the rear end of the flash cutter (3) and opposite to the cutting edge (31), which can guide the molten material overflowing from the friction stir welding to a direction away from the cutting edge (31).

5. The friction stir welding tool according to claim 4, wherein: Along the rotation direction (R), the guide wall (32) is located on the rear side of the cutting edge (31) and gradually extends backward from bottom to top.

6. The friction stir welding tool according to Claim 4 wherein: The lower end of the flash cutter (3) is higher than the lower end surface of the shoulder (2) by a predetermined distance S, which corresponds to the welding seam depth formed by welding.

7. The friction stir welding tool according to any one of claims 1 to 3, wherein: The lower end surface of the shoulder (2) is concave to form a recess (21) for accommodating molten material, and the recess (21) extends along the downward direction (DF) of the center axis (B) to the stir head (5).

8. The friction stir welding tool according to claim 7, wherein: The longitudinal cross-sectional width of the stir head (5) gradually decreases from top to bottom along the center axis (B).

9. The friction stir welding tool according to Claim 7 wherein: The stir head (5) is distributed with at least two resistance surfaces (51) along the circumference, and the distance between the resistance surface (51) and the center axis (B) is less than the radius of the stir head (5) in any cross section of the stir head (5).

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