Friction stir riveting structure, device and method for cylindrical structures

Abstract

The application relates to a friction stir riveting structure, device and method for a cylindrical structure, the device comprising a first spindle capable of rotating around the axis of the first spindle and a second spindle having a first end connected to the first spindle and a second end provided with a stir head provided with a forming cavity for forming a rivet cap, the axis of the second spindle being perpendicular to the axis of the first spindle, the second spindle having two roots, the two roots of the second spindle being symmetrically arranged along the axis of the first spindle and each root of the second spindle being capable of rotating around the axis of the second spindle. The two roots of the second spindle are symmetrically arranged on the first spindle, the position of the second spindle is adjusted by rotating the first spindle, so that the second spindle can be switched and welded on riveting holes at different positions. The second spindle is provided with the rotatable stir head, the stir head can stir the rivet to form the rivet cap, and riveting is realized, work efficiency is improved, the process is simplified, and time is saved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to friction stir welding structures, apparatus and methods for cylindrical structures. Background Technology

[0002] Friction stir welding (FSW) is a novel solid-state welding technology that offers advantages over traditional welding techniques, including high efficiency, energy saving, no pollution, minimal welding deformation, and high weld quality. It is particularly suitable for welding and joining lightweight metals such as magnesium alloys and aluminum alloys. Friction stir rivet welding (FSRW), which combines the FSW principle with traditional riveting, offers significant advantages over traditional riveting, including higher joint strength and better sealing. It has broad application prospects in joining similar or dissimilar materials, such as metals and composite materials.

[0003] Chinese patent publication number 102248112A, entitled "A Friction Stir Riveting Device for Light Metal Sheets," discloses that: "The device includes a riveting device and a rivet, as well as a sheet metal clamping ring, a rotatable rivet clamping device located within the sheet metal clamping ring, the rivet, a mold, and a piston rod located within the mold hole. Through the high-speed rotation of the rivet, friction is generated between it and the sheet metal to be riveted. The heat generated by this friction softens the sheet metal, reducing the feed resistance of the rivet. This allows the rivet to pierce the sheet metal under relatively low pressure. Under the pressure of the piston-type mold and piston rod involved in the invention, a mechanical interlock is formed between the rivet and the sheet metal to be riveted, achieving a mechanical connection of the light metal alloy sheet."

[0004] The above riveting method has the following shortcomings: In order to facilitate the rivet piercing the riveted plate, the rivet material used in this patent needs to have a higher density than the riveted 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; the method of riveting each hole sequentially can meet the riveting requirements, but the work efficiency is not high; for cylindrical structures, when multiple holes in the circumference need to be riveted efficiently, this method is complicated and the adjustment and calibration of the tooling requires a lot of time. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] This invention provides a friction stir riveting structure, apparatus, and method for cylindrical structures. By symmetrically arranging two second main shafts on a first main shaft and setting a rotatable stirring head on the second main shafts, the riveting is achieved, solving the technical problems of low efficiency, complex process, and time-consuming operation of existing riveting methods.

[0007] (2) Technical solution

[0008] In a first aspect, embodiments of the present invention provide a friction stir riveting structure for a cylindrical structure, comprising: a first main shaft and a second main shaft; the first main shaft is rotatable about the axis of the first main shaft; the second main shaft has a first end and a second end, the first end being connected to the first main shaft, the second end being axially extendable and retractable along the second main shaft, the second end being provided with a stirring head, the stirring head being provided with a forming cavity for forming a rivet head; wherein, the axis of the second main shaft is perpendicular to the axis of the first main shaft, there are two second main shafts, the two second main shafts are symmetrically arranged along the axis of the first main shaft, and each second main shaft is rotatable about the axis of the second main shaft.

[0009] Furthermore, the stirring head includes a shoulder and a clamping ring sleeved on the shoulder. The shoulder is rotatable about the axis of the shoulder, and the shoulder and the clamping ring cooperate to form the forming cavity.

[0010] Furthermore, the shoulder is made of stainless steel, cemented carbide, nickel-based alloy, tungsten-based alloy, or polycrystalline cubic boron nitride; and / or, the clamping ring is made of stainless steel, cemented carbide, nickel-based alloy, tungsten-based alloy, or polycrystalline cubic boron nitride.

[0011] Furthermore, a certain gap is spaced between the shoulder and the clamping ring, and the width of the gap is 0.1mm to 1mm.

[0012] Furthermore, the friction stir riveting structure for cylindrical structures also includes a host computer, and both the first spindle and the second spindle are equipped with tension and compression sensors, which are electrically connected to the host computer.

[0013] Secondly, a friction stir riveting device for a cylindrical structure is provided, comprising two cylindrical structures nested together, a rivet, and a friction stir riveting structure for a cylindrical structure as described in any of the above technical solutions. The two cylindrical structures are provided with a plurality of corresponding riveting holes along the circumferential direction. The rivet passes through the riveting holes, one end of the rivet is supported, and the other end of the rivet is used to abut against the stirring head.

[0014] Furthermore, the axis of the first main shaft is collinear with the axis of the cylindrical structure, and the two riveting holes arranged opposite to each other are coaxial with the diameter of the cylindrical structure.

[0015] Furthermore, the volume of the rivet protruding from the inner side of the cylindrical structure is greater than the volume of the forming cavity.

[0016] Thirdly, a friction stir welding method for cylindrical structures is provided, employing any of the above-described friction stir welding apparatuses for cylindrical structures, comprising the following steps S10 to S50:

[0017] S10, the cylindrical structure is placed on the fixture and clamped and fixed, the plurality of rivets are placed into the welding holes and fixed, and a supporting force is applied to the rivets toward the inside of the cylindrical structure;

[0018] S20, adjust the length of the first spindle so that the axial direction of the stirring head is on the same horizontal plane as the axial direction of the rivet, adjust the angle of the first spindle so that the stirring head is coaxial with the rivet, adjust the length of the second spindle so that the lengths of the two second spindles are equal, and set the stirring head at a position corresponding to a pair of riveting holes;

[0019] S30, start the two second spindles, the stirring head rotates at a first speed and moves towards the corresponding riveting hole at a second speed. When the stirring head contacts the rivet, the second spindle stops rotating in place and preheats for a first preset time. After the rivet softens, it moves at a third speed.

[0020] S40, after the rivet is formed, the second main shaft stops rotating, holds pressure for a second preset time, and then the second main shaft retracts, the stirring head separates from the rivet, and one riveting process ends;

[0021] S50, the first spindle rotates at a preset angle at a fourth speed to reach the position of the next pair of riveting holes, and repeats steps S30 and S40 until all riveting holes are completed.

[0022] Furthermore, the first speed is 400 rpm to 12000 rpm; the second speed is 1 mm / min to 5 mm / min; the third speed is 50 mm / min to 1000 mm / min; and the fourth speed is 20 rpm to 100 rpm.

[0023] (3) Beneficial effects

[0024] This invention symmetrically arranges two second spindles on a first spindle. Rotation of the first spindle adjusts the position of the second spindles, allowing for switching between welding the rivet holes at different locations. Each second spindle is equipped with a rotatable stirring head, which agitates and rubs the rivet to form a rivet head, thus achieving the riveting process. The two second spindles can simultaneously weld two corresponding rivet holes, improving work efficiency, simplifying the process, and saving time. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a friction stir welding structure for a cylindrical structure according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of a friction stir riveting device for a cylindrical structure according to an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram illustrating the implementation principle of an embodiment of the present invention.

[0029] Figure 4 This is a partial structural schematic diagram of an embodiment of the present invention.

[0030] Figure 5 This is a diagram showing the riveting and welding effect of the cylindrical structure according to an embodiment of the present invention.

[0031] In the picture:

[0032] 100. Friction stir riveting structure for cylindrical structures; 200. Friction stir riveting device for cylindrical structures;

[0033] 1. First main shaft; 2. Second main shaft; 21. First end; 22. Second end; 23. Stirring head; 231. Forming cavity; 232. Shaft shoulder; 233. Pressure ring;

[0034] 210. Cylindrical structure; 211. Welding hole; 220. Rivet. Detailed Implementation

[0035] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments, and any modifications, substitutions and improvements to the parts, components and connection methods are covered without departing from the spirit of the present invention.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Figure 1 This is a schematic diagram of a friction stir riveting structure for a cylindrical structure according to an embodiment of the present invention, as shown below. Figure 1 , Figure 2, Figure 3 , Figure 4 , Figure 5 As shown, an embodiment of the present invention proposes a friction stir welding structure 100 for cylindrical structures. The friction stir welding structure 100 for cylindrical structures can be applied to welding equipment or welding robots. The friction stir welding structure 100 for cylindrical structures includes a first spindle 1 and a second spindle 2. The first spindle 1 is rotatable about its axis. The second spindle 2 has a first end 21 and a second end 22. The first end 21 is connected to the first spindle 1, and the second end 22 is provided with a stirring head 23. The second end 22 is axially extendable and retractable along the second spindle 2. The stirring head 23 is provided with a forming cavity 231 for forming rivet heads. The axis of the second spindle 2 is perpendicular to the axis of the first spindle 1. There are two second spindles 2, symmetrically arranged along the axis of the first spindle 1, and each second spindle 2 is rotatable about its axis. Specifically, both the first spindle 1 and the second spindle 2 are connected to a drive assembly capable of driving their rotation, preferably a motor. Specifically, the second end 22 can extend and retract along the axial direction of the second main shaft 2. This can be achieved by installing an electric push rod or a hydraulic push rod at the second end 22. This technical solution is well known to those skilled in the art, and this application will not elaborate further. It is understood that the two second main shafts 2 are preferably symmetrically arranged along the axis of the first main shaft 1. The two symmetrically arranged second main shafts 2 can provide mutual support force. The two second main shafts 2 can simultaneously abut against their corresponding rivets 220, thereby restricting the axial movement of the second main shafts 2 and ensuring the stability of the riveting process.

[0038] The implementation principle of this embodiment is as follows: The rotation of the first main shaft 1 can adjust the placement position of the second rotating shaft 2 on it. The rotation of the second main shaft 2 can drive the stirring head 23 on it to rotate. The stirring head 23 is used to contact and rub the rivet 220. The stirring head 23 rubs against the rivet 220 at high speed, generating a large amount of heat. The heat and the shear force generated by the stirring friction cause some of the rivets 220 to undergo plastic deformation in the forming cavity 231, and stir the rivets 220 in the plastic state, making its grains finer and its structure more uniform. Due to the constraint and compression of the inner wall of the forming cavity 231, the rivet material in the plastic state cools in the forming cavity 231 to form a rivet head corresponding to the shape of the forming cavity 231.

[0039] In a preferred embodiment of this invention, the stirring head 23 includes a shoulder 232 and a clamping ring 233 sleeved around the shoulder 232. The shoulder 232 is rotatable about its axis, and the shoulder 232 and the clamping ring 233 cooperate to form a molding cavity 231. Specifically, the clamping ring 233 does not rotate with the shoulder 232, and it restricts the outflow of rivet head material. Rotation of the shoulder 232 can stir and rub the rivet 220 in contact with it. The clamping ring 233 can restrict material outflow, reduce frictional heat, reduce residual thermal stress, and improve the overall molding quality.

[0040] In one preferred embodiment of this invention, the shoulder 232 is made of stainless steel, cemented carbide, nickel-based alloy, tungsten-based alloy, or polycrystalline cubic boron nitride; in another preferred embodiment of this invention, the clamping ring 233 is made of stainless steel, cemented carbide, nickel-based alloy, tungsten-based alloy, or polycrystalline cubic boron nitride. All of these materials possess excellent physical properties and stable chemical properties.

[0041] In a preferred embodiment of this invention, a certain gap is maintained between the shoulder 232 and the clamping ring 233, with a gap width of 0.1mm to 1mm. When the gap width is within this range, the rivet head is well formed and does not affect the rotation of the shoulder 232. The cylindrical structure 210, the rivet 220, and any of the friction stir riveting structures 100 used for the cylindrical structure in the above embodiments are provided. Both cylindrical structures 210 have multiple corresponding riveting holes 211 arranged circumferentially. The rivet 220 passes through the riveting holes 211, one end of the rivet 220 is supported, and the other end of the rivet 220 is used to abut against the stirring head 23. Specifically, the cylindrical structure 210 can be made of metal, non-metal, or composite materials. Specifically, multiple welding holes 211 are evenly arranged along the circumference of the cylindrical structure 210 so that the distance between any two adjacent welding holes 211 is equal, so that the second main shaft 2 can rotate at a fixed angle to weld the rivets 220 in the welding holes 211.

[0042] In a preferred embodiment of this invention, the axis of the first main shaft 1 is collinear with the axis of the cylindrical structure 210, and the two riveting holes 211 arranged opposite to each other are coaxial with the diameter of the cylindrical structure 210.

[0043] In a preferred embodiment of this invention, the volume of the rivet 220 protruding from the inner side of the cylindrical structure 210 is greater than the volume of the molding cavity 231. The rivet 220 passes through the welding hole 211, with one end protruding from the inner side of the cylindrical structure 210. This protruding end is used to contact the stirring head 23. The volume of the rivet 220 protruding from the inner side of the cylindrical structure 210 is greater than the volume of the molding cavity 231, thereby allowing the plasticized rivet 220 to completely fill the molding cavity 231, forming a rivet head with a shape corresponding to the molding cavity 231.

[0044] Through the above technical solution, this invention enables rapid riveting and welding of multiple circumferential welding holes 211 on a cylindrical structure 210, significantly improving the riveting and welding efficiency of the cylindrical structure 210. This invention can achieve high-quality riveting and welding of similar / dissimilar metals and composite materials. For riveting and welding structures with a metal inner layer (the outer layer material can be similar, dissimilar, or composite materials), this invention selects rivets of the same metal as the inner layer. On the one hand, similar rivets and welding plates can achieve high-quality metallurgical bonding, thereby improving the connection quality; on the other hand, it also shows outstanding advantages in effectively promoting structural lightweighting. For riveting and welding structures with a composite material inner layer, this invention can improve the physical adsorption and micro-mechanical interlocking between the rivet and the composite material through heat input control and pressure holding process, thereby improving the weld quality. Specifically, the rivet material is preferably magnesium alloy, aluminum alloy, or other metals.

[0045] This embodiment also provides a friction stir riveting method for cylindrical structures, employing any of the friction stir riveting devices for cylindrical structures described in the above embodiments. The method includes:

[0046] S10, the cylindrical structure 210 is placed on the fixture and clamped and fixed. Multiple rivets 220 are placed into the welding holes 211 and fixed. A supporting force is applied to the rivets 220 toward the inside of the cylindrical structure 210 so as to achieve close contact between the stirring head 23 and the rivets 220.

[0047] S20, adjust the length of the first spindle 1 so that the axial direction of the stirring head 23 is on the same horizontal plane as the axial direction of the rivet 220, adjust the angle of the first spindle 1 so that the stirring head 23 is coaxial with the rivet 220, adjust the length of the second spindle 2 so that the lengths of the two second spindles 2 are equal, and set the stirring head 23 at the position corresponding to a pair of riveting holes 211.

[0048] S30, the two second spindles 2 are started. The stirring head 23 rotates at a first speed ω2 and moves towards the corresponding riveting hole 211 at a second speed v1. When the stirring head 23 contacts the rivet 220, the second spindle 2 stops and rotates in place for a first preset time to preheat. After the rivet 220 softens, it moves at a third speed v2. At the same time, the second spindle 2 applies a certain amount of upsetting force to the rivet 220. Specifically, the upsetting force of the second spindle 2 during operation is 1000~15000N. The first preset time is preferably 1~5s.

[0049] S40, after the rivet 220 is formed, the second main shaft 2 stops rotating, holds pressure for a second preset time, and then the second main shaft 2 is pulled back, the stirring head 23 separates from the rivet 220, and one riveting and welding process ends; specifically, the second preset time is preferably 3 to 10 seconds.

[0050] S50, the first spindle 1 rotates at a preset angle at a fourth speed ω1 to reach the position of the next pair of riveting holes 211, and repeats steps S30 and S40 until all riveting holes 211 are completed.

[0051] In a preferred embodiment of this invention, the first speed ω2 is preferably 400 rpm to 12000 rpm; the second speed v1 is preferably 1 mm / min to 5 mm / min; the third speed v2 is preferably 50 mm / min to 1000 mm / min; and the fourth speed ω1 is preferably 20 rpm to 100 rpm. These parameters can be determined based on actual usage requirements (such as rivet material, rivet length, etc.).

[0052] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For the embodiments of the method, relevant parts can be referred to the description of the device embodiments (as appropriate). The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0053] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A friction stir rivet welding device for a cylindrical structure, characterized by, The device comprises: two cylinder structures, rivets; a first spindle, which can rotate around the axis of the first spindle; a second spindle, which has a first end connected to the first spindle and a second end that can extend and retract along the axis of the second spindle, and the second end is provided with a stirring head, and the stirring head is provided with a forming cavity for rivet cap forming; a plurality of corresponding riveting holes are arranged on the two cylinder structures in the circumferential direction, the rivets are arranged in the riveting holes, one end of the rivet is supported, and the other end of the rivet is used to abut against the stirring head; the axis of the first spindle is coaxial with the axis of the cylinder structure, and the two riveting holes arranged oppositely are coaxial with the diameter of the cylinder structure; wherein the axis of the second spindle is perpendicular to the axis of the first spindle, and the second spindle has two roots, the two roots of the second spindle are symmetrically arranged along the axis of the first spindle, and each of the second spindles can rotate around the axis of the second spindle; the stirring head comprises a shaft shoulder and a compression ring sleeved outside the shaft shoulder, the shaft shoulder can rotate around the axis of the shaft shoulder, and the shaft shoulder and the compression ring cooperate to form the forming cavity; the shaft shoulder and the compression ring are spaced apart by a certain gap, and the width of the gap is 0.1mm-1mm.

2. The friction stir riveting apparatus for a cylindrical structure according to claim 1, characterized by The material of the shaft shoulder is stainless steel, hard alloy, nickel-based alloy, tungsten-based alloy or polycrystalline cubic boron nitride; and / or, the material of the compression ring is stainless steel, hard alloy, nickel-based alloy, tungsten-based alloy or polycrystalline cubic boron nitride.

3. The friction stir riveting apparatus for a cylindrical structure according to Claim 1, wherein The device for friction stir riveting of the cylinder structure further comprises a host computer, and the first spindle and the second spindle are both provided with a tension and pressure sensor, and the tension and pressure sensor is electrically connected with the host computer.

4. The friction stir riveting apparatus for a cylindrical structure according to Claim 1, wherein The volume of the rivet exposed inside the cylinder structure is greater than the volume of the forming cavity.

5. A friction stir rivet welding method for a cylindrical structure, characterized by, The device for friction stir riveting of the cylinder structure according to any one of claims 1-4, the method comprises: S10, placing the cylinder structure on a clamp and clamping and fixing it, putting a plurality of rivets into the riveting holes and fixing them, and applying a supporting force to the rivets towards the inside of the cylinder structure; S20, adjusting the length of the first spindle so that the axial direction of the stirring head is in the same horizontal plane as the axial direction of the rivet, adjusting the angle of the first spindle so that the stirring head is coaxial with the rivet, adjusting the length of the second spindle so that the lengths of the two second spindles are equal, and setting the stirring head at a position corresponding to a pair of riveting holes; S30, starting the two second spindles, the stirring head rotates at a first speed and advances towards the corresponding riveting hole at a second speed, when the stirring head contacts the rivet, the second spindle stays in place and rotates, preheats for a first preset time, and after the rivet is softened, advances at a third speed; S40, after the rivet is formed, the second spindle stops rotating, maintains pressure for a second preset time, and then the second spindle is retracted, the stirring head is separated from the rivet, and the riveting process is completed. S50, the first main shaft rotates at a fourth speed by a preset angle to reach a position of a next pair of riveting and welding holes, and steps S30 and S40 are repeated until all the riveting and welding holes are completed.

6. The friction stir riveting method according to claim 5, wherein The first speed is 400 rpm-12000 rpm; the second speed is 1 mm / min-5 mm / min; the third speed is 50 mm / min-1000 mm / min; and the fourth speed is 20 rpm-100 rpm.

Images