Stir friction bidirectional riveting welding device and method

Abstract

The present invention belongs to the field of advanced riveting technology, specifically to a stir friction bidirectional riveting device and method, comprising a forming die, a spindle, a stirring head, a clamping ring, and a forming ring. The forming die has a forming recess for forming the lower rivet head of the rivet; the spindle is connected to a rotating component; the stirring head is fixed to the spindle; the clamping ring is arranged at the upper end of the forming die, and a placement space for fixing the metal sheet to be riveted is formed between the forming die and the clamping ring, and the clamping ring has an inner cavity for accommodating the descent and rotation of the rivet; the forming ring is used to contact the rivet cap of the rivet and is connected to multiple traction mechanisms. The traction mechanisms are controlled by a host computer to cause the forming ring to perform differential rolling motion on the rivet cap of the rivet. The purpose is to solve the problems of existing stir friction riveting devices such as complex rivet design, large mass, and stress concentration caused by heterogeneity with the base material.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced riveting welding, and in particular relates to a friction stir bidirectional riveting welding device and method. Background Art

[0002] Friction stir welding (FSW), proposed by the British Welding Institute in 1991, is a new solid-phase welding technology with advantages such as high efficiency, energy saving, pollution-free, small welding deformation, and high weld quality. It is widely used in aerospace, automotive, shipbuilding, electronics and other fields. Friction stir rivet welding (FSRW) is a new riveting technology developed based on the concept of friction stir welding. FSRW uses the frictional heat and pressure generated by the high-speed rotation of the stirring head to form a riveted joint between the metal rivet and the welding plate, which is a combination of mechanical and metallurgical bonding. Compared with traditional riveting using a single mechanical connection method, it is easier to obtain high-quality connections.

[0003] Currently, among the published patents, there is a “Stir Friction Riveting Device for Light Metal Sheets” (102248112A). The device includes a riveting device and a rivet, a sheet material clamping ring, a rivet clamping device rotatable in the sheet material clamping ring, a rivet, a mold, and a piston rod located in the mold hole. Through the high-speed rotation of the rivet, friction is formed between it and the riveted sheet material, and the heat generated by the friction is used to soften the riveted sheet material, reducing the feed resistance of the rivet, so that the rivet pierces the riveted sheet material under the action of a smaller pressure, and under the top pressure of the piston mold and the piston rod involved in the invention, a mechanical interlock is formed between the rivet and the riveted sheet material, thereby realizing the mechanical connection of the light metal alloy sheet material. However, this riveting method has shortcomings: due to the complex design of the rivet (hollow, divided into a rivet body and a plug), the rivet body and the plug may be misaligned when piercing the sheet material, resulting in loss of matching accuracy. When using rivets to make holes, it can be seen that the rivet material is harder than the metal plate, so the weight of the rivet will also be greater than that of light metal rivets, which increases the weight of the overall structure.

[0004] In addition, the patent that has been published is "A stir friction riveting device and riveting method" (101468421A). The device includes a driving rod, a rivet and a rigid pad. A driving rod that can cooperate with the rivet and drive the rivet to rotate is provided above the rivet, and a rigid pad is provided below the rivet. The driving rod cooperates with the rivet, and the plate is placed between the rivet and the rigid pad. First, the rigid pad is aligned with the driving rod; then, the connected plates and rivets are arranged in order, the driving rod is lowered, so that the driving rod and the rivet are fully matched, and at the same time, the driving rod starts to drive the rivet to rotate; under the action of pressure and frictional heat, the connected plates are locally heated and softened. As the rivet continues to rotate and move downward, the local material of the connected plates fully flows under the action of frictional heat and mechanical stirring, filling the groove on the rigid pad and the space at the neck of the rivet, so that the rivet and the plate are metallurgically bonded, completing the stir friction riveting joint. However, this riveting method also has its shortcomings: in addition to the shortcomings mentioned in the first patent, stress concentration will occur at the interface between the rivet and the base material due to the hardness difference between the soft and hard materials. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] The present invention mainly addresses the above problems and proposes a stir friction bidirectional riveting welding device and method, the purpose of which is to solve the problems of existing stir friction riveting welding devices such as complex rivet design, large mass, and stress concentration caused by heterogeneity with the base material.

[0007] (2) Technical solution

[0008] To achieve the above object, the present invention provides a friction stir bidirectional riveting welding device, comprising:

[0009] a forming die having a forming recess for forming a lower rivet head of the rivet;

[0010] a main shaft connected to the rotating member;

[0011] a stirring head, fixed on the main shaft;

[0012] A clamping ring is provided at the upper end of the forming die, and forms a placement space for fixing the metal sheet to be riveted between the forming die and the clamping ring, and has an inner cavity for accommodating the descent and rotation of the rivet;

[0013] The forming ring is used to contact the rivet cap of the rivet and is connected to multiple traction mechanisms. The upper computer controls the traction mechanisms to make the forming ring perform differential rolling motion on the rivet cap of the rivet.

[0014] Furthermore, an annular auxiliary heating belt is arranged around the forming pit.

[0015] Furthermore, the gap between the forming ring and the stirring head and the pressing ring is 0.1 to 2 mm.

[0016] Furthermore, the forming ring is a hard alloy ring.

[0017] Furthermore, the clamping ring is a hard alloy cylinder.

[0018] Furthermore, guide holes symmetrically distributed along the annular axis are reserved at the position where the lower end of the clamping ring contacts the metal plate to be riveted.

[0019] Furthermore, the traction mechanisms are symmetrically distributed along the circumferential axis, and there are three of them.

[0020] Furthermore, the direction of the differential rolling motion is a rotational motion that swings up and down, and the rotation direction is the same as the rotation direction of the stirring head, and the rotation speed is lower than the rotation speed of the main shaft.

[0021] To achieve the above object, the present invention provides a friction stir bidirectional riveting method, comprising the following steps:

[0022] Place the metal sheet to be riveted and welded, which has been pre-drilled, on the forming die, so that the riveting hole is concentric with the die pit, and fix the metal sheet to be riveted and welded with a clamping ring;

[0023] Fix the stirring head and the rivet coaxially, place the stirring head at the starting position of riveting, and adjust the position of the forming ring so that its lower surface is level with the lower surface of the stirring head;

[0024] Heat the forming mold and start the main shaft rotation, so that the stirring head and rivet rotate at a certain speed, and then rivet is inserted. When the rivet contacts the forming mold, the main shaft stops rotating to preheat, and then the rivet is softened by friction and deformation, and then the rivet is inserted again.

[0025] While the rivet is being driven, multiple traction mechanisms on the forming ring perform differential rolling motion in the same direction as the main shaft rotation, starting with the first traction mechanism and rolling in sequence. When the tension and pressure sensor on the traction mechanism measures that the rolling force reaches the preset value, the first traction mechanism pulls up the forming ring and returns it to its initial state level with the lower surface of the stirring head, and the second traction mechanism starts working, and this cycle repeats until the riveting process is completed.

[0026] After the riveting is completed, the main shaft is stopped from rotating, the stirring head and the rivet are separated, and the clamping ring is removed. Furthermore, the rotation speed of the forming ring is lower than the rotation speed of the main shaft.

[0027] (3) Beneficial effects

[0028] Compared with the prior art, the friction stir bidirectional riveting welding device and method provided by the present invention has the following advantages:

[0029] 1. Especially when riveting metal plates such as magnesium alloys, metallurgical bonding occurs between the rivet cap and the metal plate, and between the rivet and the metal plate; compared with traditional riveting, the connection strength is improved and the joint has excellent sealing.

[0030] 2. During the riveting process, the forming ring is driven by the traction device to perform differential rolling motion to obtain a reliable riveted joint. By adjusting the shape of the forming ring, different riveted joint morphologies can be obtained.

[0031] 3. The double-sided riveted joint shape is formed independently by using the forming pits and forming rings of the forming mold, without the need for secondary processing.

[0032] 4. The clamping ring can ensure the coaxiality of the plate, stirring head and rivet during the riveting and welding process, ensure uniform force and stability of the riveting and welding process, that is, it plays a "limiting" role. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention discloses a cross-sectional structural diagram of a friction stir bidirectional riveting welding device.

[0034] Figure 2 The present invention discloses a three-dimensional structural diagram of a friction stir bidirectional riveting welding device.

[0035] Figure 3 This is a schematic diagram of a riveting and welding forming structure disclosed in the present invention.

[0036] Figure 4 The present invention discloses a structural schematic diagram of a riveted joint.

[0037] Figure 5 This is a schematic diagram of a forming ring rolling process disclosed in the present invention.

[0038] Figure 6 This is a bottom view of a compression ring disclosed in the present invention.

[0039] The reference numerals shown in the figure are: 1. stirring head; 2. forming ring; 3. clamping ring; 4. rivet; 5. guide hole; 6. metal sheet to be riveted; 7. forming pit; 8. forming mold; 9. heating belt; 10. main shaft. DETAILED DESCRIPTION

[0040] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0043] like Figures 1-6 The present invention discloses a friction stir bidirectional riveting device that utilizes frictional heat and pressure generated by the high-speed rotation of a stirring head to form a riveted joint between a metal rivet and a welded sheet, achieving both mechanical and metallurgical bonding. This device includes, but is not limited to, friction stir bidirectional riveting of homogeneous or dissimilar metal sheets, such as magnesium alloys. The device comprises a stirring device, a rivet 4, and a forming die 8. The structures and connections of these components are described in detail below.

[0044] The forming die 8 is made of cemented carbide and has a recessed recess 7 on its upper surface, which is used to form the lower rivet head of the rivet 4. The lower end of the forming die 8 is fixed to a base, and the upper end is used to place the metal sheet 6 to be riveted. The recessed recess 7 of the forming die 8 can be designed and manufactured as needed, for example, it can be an inverted spherical recess, which is used to receive the rivet 4 and assist in the softening of the material to form the lower riveted joint.

[0045] The stirring device includes a main shaft 10 , a stirring head 1 , a forming ring 2 and a pressing ring 3 .

[0046] The spindle 10 is the core component of the device and is driven to rotate by a motor. The diameter and length of the spindle 10 can be designed and manufactured as needed to accommodate riveting workpieces of different sizes.

[0047] The stirring head 1 is a rotating component fixed on the main shaft 10, and is used to rotate the rivet 4 during the manufacturing process of the rivet 4, thereby achieving the effect of stir friction riveting.

[0048] The clamping ring 3 is arranged at the upper end of the forming die 8, and a space is formed between the clamping ring 3 and the forming die 8 to fix the metal plate 6 to be riveted. The clamping ring 3 has an inner cavity that runs vertically through the ring 3 to accommodate the descent and rotation of the rivet 4. The diameter and depth of the inner cavity can be designed and manufactured as needed.

[0049] The forming ring 2 is used to contact the rivet cap at the upper end of the rivet 4 and is connected to multiple traction mechanisms (not shown). The traction mechanisms are controlled by the host computer, causing the forming ring 2 to perform a differential rolling motion on the rivet cap of the rivet 4. During the forming process, the differential rolling motion moves in an up-and-down rotational motion in the same direction as the stirring head 1, and the rotation speed is lower than the rotation speed of the main shaft 10.

[0050] During use, the metal sheet 6 to be riveted is first placed on the forming die 8, and the clamping ring 3 fixes it to the upper end of the forming die 8, and then the rivet 4 is inserted. Next, the motor drives the main shaft 10 and the stirring head 1 to rotate, and the lower rivet head of the rivet 4 contacts the forming pit 7 of the forming die 8 and begins to form. As the stirring head rotates, the rotating rivet 4 contacts the forming pit 7 of the forming die 8 and friction generates heat, and the rivet softens. As the main shaft 10 is lowered, the softened rivet material is continuously filled into the forming pit 7, and the rivet material filled into the forming pit 7 solidifies to form the lower rivet head of the rivet 4. At the upper end, the upper computer controls the traction mechanism to make the forming ring 2 perform differential rolling motion according to the set rolling conditions, and the rivet cap is formed into the upper rivet head.

[0051] During the riveting process, the friction stir bidirectional riveting device can not only achieve metallurgical bonding between the rivet cap and the metal plate 6 to be riveted, and between the rivet 4 and the metal plate 6 to be riveted by means of friction stir, thereby achieving high-strength connection between the homogeneous rivet cap and the rivet and the substrate, ensuring excellent sealing of the joint and reducing the weight of the structural parts; but also ensures uniform force on the rivet 4 and stability of the riveting process through the clamping ring 3, thereby obtaining different riveted joint morphologies; and because the clamping ring 3 and the forming mold 8 cooperate autonomously, the riveted joint is formed in one step.

[0052] In some implementations, the center line of the inner cavity is coaxially arranged with the center line of the main shaft 10, the stirring head 1, and the forming ring 2, so that the clamping ring 3 can ensure the coaxiality of the metal plate 6 to be riveted, the stirring head 1 and the rivet 4 during the riveting process, ensure uniform force and stability of the riveting process, that is, play a "limiting" role; the clamping ring 3 can ensure the shape of the rivet head.

[0053] like Figure 1As shown, an annular auxiliary heating belt 9 is arranged around the forming pit 7 to provide a heat source to assist the rivet 4 in softening the material and forming it. During the friction stir riveting process, the friction heat generated by the stirring head 1 can locally soften the material in the riveted area. However, if the hardness of the material is too high, the friction heat may not be able to completely soften it, resulting in poor quality of the riveted joint. Therefore, by arranging an annular auxiliary heating belt 9 around the forming pit 7, an additional heat source can be provided to help soften and shape the material in the riveted area, thereby improving the quality of the riveted joint. At the same time, due to the annular arrangement of the heating belt 9, the shape of the riveted joint can be better controlled and heated evenly, thereby improving the stability and quality of the riveted joint.

[0054] In the stir friction bidirectional riveting welding device, an appropriate gap is set between the forming ring 2 and the stirring head 1 and the clamping ring 3 to avoid dead points during the rolling process and unnecessary friction during the stirring process. Preferably, the gap between the forming ring 2 and the stirring head 1 and the clamping ring 3 is 0.1 to 2 mm.

[0055] In addition to the basic structure and riveting process described above, the following are some further details and features of the invention:

[0056] Forming ring 2 is driven up and down by three traction mechanisms symmetrically distributed along the annular axis. This mechanism guides, positions, and controls the deformation of the rivet material, ensuring the quality of the rivet 4 while simultaneously squeezing out excess material. The frictional heat between forming ring 2 and rivet 4 provides the heat source required for plasticizing and molding the upper rivet, acting as a heating aid. When not in use or in the raised position after rolling, the lower surface of forming ring 2 remains level with the lower surface of stirring head 1. Forming ring 2 is a cemented carbide circular ring whose shape can be adjusted as needed to achieve different rivet joint morphologies.

[0057] The clamping ring 3 is a carbide cylinder that secures the metal sheet 6 to be riveted, defines the rivet head's shape, and ensures axial stability during the downward rotation of the rivet 4. The lower end of the clamping ring 3, where it contacts the metal sheet 6, features guide holes 5 symmetrically distributed along the annular axis. These holes allow excess material to escape, effectively limiting the rivet head's shape and ensuring a consistent appearance.

[0058] The stirring head 1 is a cylindrical, pinless, flat-shoulder design. This flat-shoulder design allows the rivet 4 to remain coaxial and stable during the stirring process, ensuring accurate and reliable riveting. The material of the stirring head 1 can be designed and manufactured as needed, for example, stainless steel, cemented carbide, nickel-based alloy, tungsten-based alloy, or polycrystalline cubic boron nitride.

[0059] In addition, a tension and pressure sensor is installed on the traction mechanism to transmit information to the host computer, which controls the reciprocating motion of the traction mechanism. In some embodiments, the pressure of the forming ring 2 during rolling is 50 to 5000N.

[0060] The rivet 4 is an integrated unit, comprising a rivet cap and a rivet body. Both the rivet cap and the rivet body are cylindrical and easy to process. The rivet is made of magnesium alloy or other metals that are the same as or different from the metal sheet.

[0061] An embodiment of the present invention provides a friction stir bidirectional riveting method, comprising the following steps:

[0062] Step S100: placing the metal plate 6 to be riveted and welded, which has been pre-drilled with holes, on the forming die 8 so that the riveting holes are concentric with the die recess 7 , and fixing the metal plate 6 to be riveted and welded with the clamping ring 3 .

[0063] In this step, the metal sheet 6 to be riveted must be pre-machined to allow for a tight connection with the rivet 4 during the subsequent riveting process. A mold recess 7 is provided on the forming die 8 to facilitate the penetration of the rivet 4 into the riveting hole during the riveting process. The clamping ring 3 secures the metal sheet 6 to the forming die 8 to prevent movement or deflection during the subsequent riveting process.

[0064] Step S200: Fix the stirring head 1 and the rivet 4 coaxially, place the stirring head 1 at the riveting starting position, and adjust the position of the forming ring 2 so that its lower surface is level with the lower surface of the stirring head 1.

[0065] In this step, the stirring head 1 and rivet 4 need to be fixed together and aligned. The stirring head 1 needs to be placed in the starting position for rivet welding so that it can be accurately aligned with the rivet hole during the rivet welding process. At the same time, the position of the forming ring 2 needs to be adjusted so that its lower surface is level with the lower surface of the stirring head 1 to ensure smooth rolling during the subsequent rivet welding process.

[0066] Step S300: Heat the forming mold 8 and start the main shaft 10 to rotate, so that the stirring head 1 and the rivet 4 rotate at a certain speed, and at the same time, the rivet 4 is driven downward. When the rivet 4 contacts the forming mold 8, the main shaft 10 stops rotating for preheating, and continues to drive downward after the rivet 4 is deformed and softened by friction.

[0067] In this step, the forming die 8 needs to be heated to a certain surface temperature to facilitate the penetration and friction of the rivet 4 and the stirring head 1. For example, an annular auxiliary heating belt 9 is arranged around the forming pit 7 to heat the joint, and the heating temperature and time are used to control the joint forming and connection quality. At the same time, the main spindle 10 is started to rotate at a speed of 500-10000rpm. The stirring head 1 and rivet 4 also rotate at this speed. The main spindle 10 continues to rotate and penetrates the rivet at a speed of 1-5mm / min. When the rivet 4 contacts the forming die 8, the main spindle 10 stops rotating in place and preheats for 3-5 seconds. After the rivet 4 is softened by friction deformation, it continues to penetrate the rivet at a speed of 50-800mm / min. In this step, the rotating rivet 4 contacts the forming pit 7 and friction generates heat, causing the rivet to soften. As the main shaft 10 is lowered, the softened rivet material is continuously filled into the forming pit 7 , and the rivet 4 and the metal sheet 6 to be riveted are metallurgically bonded, eventually forming a lower riveted joint.

[0068] Step S400: While the rivet 4 is being driven in, the multiple traction mechanisms on the forming ring 2 perform differential rolling motion in the same direction as the rotation direction of the main shaft 10, starting from the first traction mechanism and rolling in sequence. When the tension and pressure sensor on the traction mechanism measures that the rolling force reaches the preset value, the first traction mechanism pulls up the forming ring 2 and returns to the initial state horizontal with the lower surface of the stirring head 1, and the second traction mechanism starts working, and so on, until the riveting process is completed.

[0069] In this step, while the rivet 4 continues to be driven down, the multiple traction mechanisms on the forming ring 2 perform differential rolling motion in the same direction as the rotation of the main shaft 10. Rolling is performed sequentially starting from the first traction mechanism. When the tensile pressure sensor on the traction mechanism measures a rolling force of 50 to 5000N, the first traction mechanism pulls up the forming ring 2 and returns it to the initial state horizontal with the lower surface of the stirring head 1. The second traction mechanism starts working, and this process repeats until the riveting process is completed. The tensile pressure sensor can monitor the force applied by the traction mechanism to ensure that the rolling force reaches the preset value. At the same time, differential rolling can ensure that the material around the riveted weld is evenly stressed, thereby avoiding fracture and cracking of the weld.

[0070] Step S500: After the riveting is completed, the main shaft 10 is stopped from rotating, the stirring head 1 and the rivet 4 are separated, the clamping ring 3 is removed, and the material in the guide hole 5 is cleaned to complete the riveting.

[0071] Furthermore, in the present invention, the rotation speed of the forming ring 2 is lower than the rotation speed of the main shaft 10. The friction heat generated between the forming ring 2 and the rivet 4 provides a heat source for the plasticization forming of the upper rivet, playing an auxiliary heating role on the upper part of the rivet 4.

[0072] To further reveal the nature of the present invention, the following examples are described in detail. It should be understood that the present invention is not limited to the specific conditions or details set forth in these examples except as specifically indicated in the appended claims.

[0073] Example 1:

[0074] Specific embodiment: Riveting welding of AZ31 magnesium alloy and 2024 aluminum alloy

[0075] Specifications of metal plates to be riveted: 300mm×200mm×3mm

[0076] Rivet: Made of AZ31 magnesium alloy, both the cap and the body are cylindrical, with a cap diameter of 6mm and a thickness of 1.5mm, and a body diameter of 3mm and a length of 8.5mm.

[0077] Stirring head: Made of H13 steel, cylindrical, 3.2mm in diameter.

[0078] Forming ring: Made of H13 steel, circular, inner diameter 3.4mm, outer diameter 5.8mm, thickness 2.5mm.

[0079] Clamping ring: Made of 440C steel, inner diameter 6mm, outer diameter 10mm.

[0080] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0081] like Figure 1 As shown, a stir friction bidirectional riveting method includes the following steps:

[0082] Step 1: Place the metal plate 6 to be riveted and welded, which has been pre-drilled with holes, on the forming mold 8, so that the riveting holes are concentric with the forming pit 7 of the mold, and use the clamping ring 3 to fix the metal plate 6 to be riveted and welded.

[0083] Step 2: Fix the stirring head 1 and the rivet 4 coaxially, and place the stirring head 1 in the starting position for riveting. Adjust the position of the forming ring 2 so that its lower surface is level with the lower surface of the stirring head 1. Start the auxiliary heating belt 9 to heat the forming mold 8. Start the main shaft 10 to rotate at a speed of 2000 rpm ω. The stirring head 1 and the rivet 4 also rotate at this speed. The main shaft 10 continues to rotate and plunges at a speed V1 of 3 mm / min. When the rivet 4 contacts the forming mold 8, the main shaft 10 stops rotating in place and preheats for 3 seconds. After the rivet 4 is softened by friction deformation, it continues to plunge at a speed V2 of 500 mm / min. At this time, the three traction mechanisms on the forming ring 2 start to move, performing differential rolling movement in the same direction of rotation as the main shaft 10, and rolling starts from the first traction mechanism. When the tension and pressure sensor on the traction mechanism measures a rolling force of 1000N, the first traction mechanism pulls up the forming ring 2 and returns it to the initial state horizontal with the lower surface of the stirring head 1, and the second traction mechanism starts working, and so on. When the last traction mechanism pulls up the forming ring 2 and returns it to the initial state horizontal with the lower surface of the stirring head 1, the first traction mechanism starts working, and so on, until the riveting process is completed.

[0084] Step 3: The rotating rivet 4 contacts and rubs against the molded recess 7, generating heat and softening the rivet 4. As the spindle 10 plunges downward, the softened rivet material continuously fills the recess 7, eventually forming a riveted joint.

[0085] Step 4: The main shaft 10 stops rotating, separates the stirring head 1 from the rivet 4, removes the clamping ring 3, cleans the material in the guide hole 5, and completes the riveting.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A stir friction bidirectional riveting welding device, characterized in that: include: a forming die having a forming recess for forming a lower rivet head of the rivet; a main shaft connected to the rotating member; a stirring head, fixed on the main shaft; A clamping ring is provided at the upper end of the forming die, and forms a placement space for fixing the metal sheet to be riveted between the forming die and the clamping ring, and has an inner cavity for accommodating the descent and rotation of the rivet; A forming ring, which is used to contact the rivet cap of the rivet and is connected to a plurality of traction mechanisms, wherein the traction mechanisms are controlled by a host computer to cause the forming ring to perform differential rolling motion on the rivet cap of the rivet; An annular auxiliary heating belt is arranged around the forming pit; The position where the lower end of the clamping ring contacts the metal plate to be riveted is provided with guide holes symmetrically distributed along the annular axis; The traction mechanisms are symmetrically distributed along the circumferential axis, and there are three of them; The movement direction of the differential rolling movement is an up-and-down swinging rotation movement, and the rotation direction is the same as the rotation direction of the stirring head, and the rotation speed is lower than the rotation speed of the main shaft.

2. A friction stir bidirectional riveting device according to claim 1, characterized in that: The gap between the forming ring, the stirring head and the pressing ring is 0.1 to 2 mm.

3. A friction stir bidirectional riveting device according to claim 1, characterized in that: The forming ring is a hard alloy ring.

4. A friction stir bidirectional riveting device according to claim 1, characterized in that: The clamping ring is a hard alloy cylinder.

5. A stir friction bidirectional riveting method, characterized in that: The friction stir bidirectional riveting welding device according to any one of claims 1 to 4 is used for the purpose; the friction stir bidirectional riveting welding method comprises the following steps: Place the metal sheet to be riveted and welded, which has been pre-drilled, on the forming die, so that the riveting hole is concentric with the die pit, and fix the metal sheet to be riveted and welded with a clamping ring; Fix the stirring head and the rivet coaxially, place the stirring head at the starting position of riveting, and adjust the position of the forming ring so that its lower surface is level with the lower surface of the stirring head; Heat the forming mold and start the main shaft rotation, so that the stirring head and rivet rotate at a certain speed, and then rivet is inserted. When the rivet contacts the forming mold, the main shaft stops rotating to preheat, and then the rivet is softened by friction and deformation, and then the rivet is inserted again. While the rivet is being driven, multiple traction mechanisms on the forming ring perform differential rolling motion in the same direction as the main shaft rotation, starting with the first traction mechanism and rolling in sequence. When the tension and pressure sensor on the traction mechanism measures that the rolling force reaches the preset value, the first traction mechanism pulls up the forming ring and returns it to its initial state level with the lower surface of the stirring head, and the second traction mechanism starts working, and this cycle repeats until the riveting process is completed. After riveting is completed, stop the spindle rotation, separate the stirring head and rivet, and remove the clamping ring.

6. A friction stir bidirectional riveting method according to claim 5, characterized in that: The rotation speed of the forming ring is lower than the rotation speed of the main shaft.

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