阅读说明：本技术 一种复合材料铆钉原位搅拌摩擦成型的铆焊工艺方法 (Rivet welding process method for in-situ friction stir forming of composite rivet ) 是由 姬书得 熊需海 李鸣申 马琳 张利国 吕赞 杨康 胡为 于 2019-09-26 设计创作，主要内容包括：一种复合材料铆钉原位搅拌摩擦成型的铆焊工艺方法,步骤1,将待连接上下板材的预制孔对中定位,将复合材料铆钉插入预制孔内,复合材料铆钉背部用刚性约束衬垫固定；步骤2,选用轴肩直径合适且轴肩内凹槽符合工艺要求的搅拌头,将选好的搅拌头安装到搅拌摩擦焊机上,将搅拌头与铆钉对中定位,并设定焊接工艺参数及搅拌头行走路径；步骤3,搅拌头以预定转速和下扎速度移动到指定位置并维持一段停留时间后,随后搅拌头回抽,待铆焊部位冷却后即完成复合材料铆钉的成型,得到铆焊接头。该方法解决了长纤维增强复合材料铆钉无法通过传统压铆及冲击铆接进行成型、高分子聚合物铆钉热铆成型过程中铆钉端部流动性差等问题。(A rivet welding process method of friction stir forming in situ of composite rivet, step 1, position the prefabricated hole of upper and lower boards to be connected in the centering, insert the composite rivet in the prefabricated hole, the back of the composite rivet is fixed with the rigid restraint liner; step 2, selecting a stirring head with a proper shaft shoulder diameter and a shaft shoulder inner groove meeting the process requirements, installing the selected stirring head on a friction stir welding machine, centering and positioning the stirring head and a rivet, and setting welding process parameters and a stirring head walking path; and 3, moving the stirring head to a specified position at a preset rotating speed and a rolling speed, maintaining for a certain retention time, then pumping back the stirring head, and cooling the rivet welding part to finish the forming of the composite rivet to obtain the rivet welding joint. The method solves the problems that the long fiber reinforced composite material rivet can not be formed by the traditional press riveting and impact riveting, the flowability of the end part of the rivet is poor in the hot riveting forming process of the high polymer rivet, and the like.)

1. A rivet welding process method for in-situ friction stir forming of composite rivets is characterized by comprising the following steps:

step 1, centering and positioning a prefabricated hole to be connected with an upper plate and a lower plate, inserting a composite rivet into the prefabricated hole to expose an end part to be formed, and fixing the back of the composite rivet by using a rigid constraint liner matched with the composite rivet in shape;

step 2, selecting a stirring head with the diameter of a shaft shoulder matched with the sum of the thicknesses of the upper plate and the lower plate, wherein the inner groove of the shaft shoulder meets the process requirement, installing the selected stirring head on a friction stir welding machine, centering and positioning the stirring head and a rivet, and setting welding process parameters and a stirring head walking path through a control panel of the friction stir welding machine;

step 3, the stirring head is driven by a main shaft of the friction stir welding machine to move to a specified position at a preset rotating speed and a binding speed, and the preset retention time is maintained; and (4) the stirring head is pumped back under the rotation drive of the main shaft of the friction stir welding machine, and the composite material rivet is formed after cooling to obtain the rivet welding joint.

2. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the upper plate is made of a polymer material, the lower plate is made of a metal material, the thicknesses of the upper plate and the lower plate are both 1-50 mm, and the upper plate and the lower plate are arranged in an equal thickness mode or in different thicknesses; the sum of the number of layers of the upper plate and the lower plate is 1-10 layers; the upper plate and the lower plate are flat plates, curved plates or complex-structure plates combined by the flat surfaces and the curved surfaces; the upper plate and the lower plate are made of the same material or different materials.

3. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the prefabricated hole is cylindrical, truncated cone-shaped, polygonal column-shaped or prismoid-shaped, and the diameter is 2-40 mm.

4. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the prefabricated hole is a threaded hole matched with the threaded rivet, a special-shaped hole matched with the stepped or tapered reducing rivet or a prefabricated hole suitable for a countersunk rivet and provided with countersinks at two ends.

5. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the composite rivet is made of long fiber reinforced resin base, short carbon fiber reinforced resin base, particle reinforced resin base, metal or metal base composite material.

6. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the part of the rivet rod of the composite material rivet, which extends out of the plate, is an end to be formed, the diameter of the end to be formed is smaller than or equal to that of the rivet rod, the diameter of the rivet head of the non-forming end of the composite material rivet is larger than that of the rivet rod of the composite material rivet, and the rivet head is semicircular, oblate, conical, square or polygonal; a taper hole, a straight-line-shaped groove or a cross-shaped groove matched with a rigid constraint liner is machined in the center of a rivet head of the non-forming end of the composite material rivet.

7. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the end face of the rigid constraint liner, which is contacted with the rivet head of the composite material rivet, is provided with a circular, square, rectangular or polygonal groove; the center of the end face of the rigid constraint liner, which is contacted with the rivet head of the composite material rivet, is provided with a conical bulge, a straight bulge or a cross bulge.

8. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the stirring head adopts a stirring head with a spherical groove on the end surface, a stirring head with a cylindrical groove on the end surface and a chamfer angle at the bottom of the groove, a stirring head with a spherical groove on the end surface and a diversion conical bulge in the groove, a stirring head with a spherical groove on the end surface and a diversion spiral arc-shaped groove in the groove, and a plane shaft shoulder stirring head suitable for forming a countersunk head rivet or a stirring head with a non-contact induction heating coil on the outer side; the diameter of the shaft shoulder of the stirring head is 4-80 mm, the end part of the stirring head is a plane and spherical groove, and a cylindrical groove with a chamfer or a groove with a backflow conical bulge can be manufactured according to requirements; the outer surface of the shaft shoulder of the stirring head is provided with one or more layers of coatings, and when the upper plate is made of hard alloy, in order to prevent the shaft shoulder of the stirring head from being worn, a wear-resistant coating is sprayed; when the upper plate is made of high-melting-point metal, in order to prevent the shaft shoulder of the stirring head from softening and deforming, a heat insulation coating is sprayed; when the upper plate is made of resin-based composite material, in order to prevent the shaft shoulder of the stirring head from being adhered with the material, a demolding coating is sprayed; the rotating speed of the stirring head is 50-10000 r/min; the speed of the downward rolling is 0.1-10 mm/min, the speed of the back pumping is 0.1-100 mm/min, and the preset retention time is 0-200 s.

9. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the molding mode of the composite material rivet is divided into a single-side processing molding mode and a double-side processing molding mode, when the single-side processing molding mode is adopted, a to-be-molded end is processed by using a rotary stirring head, a back non-molded end is in a prefabricated mode, and a back rigid constraint liner is used for fixing in the riveting and welding process; when the double-side processing molding is adopted, the composite material rivet is inserted into the prefabricated holes of the upper plate and the lower plate, the upper end and the lower end of the rivet are exposed out of the part to be processed, and the shaft shoulders of the two stirring heads in opposite rotating directions carry out friction stir rivet welding processing on the upper side and the lower side of the rivet to form the friction stir rivet welding joint formed by the double-side in-situ processing molding.

10. The rivet welding process method for in-situ friction stir forming of the composite rivet according to claim 1, characterized in that: the rivet welding structure suitable for the composite material rivet is divided into a rivet welding structure suitable for the rivet head to be spherical and convex according to a specific process, a rivet welding structure suitable for the rivet head to be cylindrical and convex, a rivet welding structure suitable for the rivet head end with a groove, a rivet welding structure suitable for the countersunk rivet, a rivet welding structure suitable for the dimple rivet hole, a rivet welding structure suitable for the composite material plate or the metal plate, and a rivet welding structure suitable for the prefabricated fiber reinforced composite material rivet and the lower composite material plate integrated formed metal plate upper rivet welding structure and the composite material rivet double-sided processing formed rivet welding structure.

Technical Field

The invention belongs to the technical field of composite material and metal connection, and particularly relates to a rivet welding process method for in-situ friction stir forming of a composite material rivet.

Background

The composite rivet has the characteristics of light weight, high specific strength, corrosion resistance and the like, has comprehensive performance superior to that of a metal rivet, and has great application potential under the trend of light-weight structure design at present. In particular, the long fiber reinforced resin-based composite rivet has high shear resistance and is suitable for connecting occasions such as mechanical structures and reinforced concrete beams. Due to the characteristics of high brittleness and easy cracking of the composite material rivet, the traditional impact hammer riveting, the blind rivet-based pulling riveting, the novel electromagnetic riveting and other pressure riveting modes are not suitable for the riveting process any more. At present, the forming processing of the composite material rivet mainly comprises two types: firstly, the field assembly mode is that the impregnation, fiber arrangement, molding and solidification of the composite rivet are completed in a production field, and the riveting of the structure is completed after the composite rivet is solidified and molded; and secondly, carrying out hot riveting processing on the end to be formed of the rivet. Both processes are time-consuming and labor-consuming, and the production efficiency is low. Meanwhile, the riveting assembly mode of field rivet curing molding has narrow environmental applicability, and the structure can be riveted and assembled only in a workshop production field. For the hot riveting processing mode, the strength of a hot riveting head is low because the fibers in the composite rivet cannot be wound or rearranged; the method is only suitable for pure resin materials with lower melting points, and the connection of the high-temperature resistant composite material is difficult and the structure performance is also adversely affected by the continuous higher temperature; because the plastic heat conductivity is lower, no material mixing action exists between the plastic rivet and the hole wall and between the plastic rivet and the upper surface of the plate, and the sealing performance of the riveted joint cannot be further improved. For example, in the hot riveting method disclosed in chinese patent application No. 201580003629.4, a plastic rivet is heated by a central heating rod, and a metal sheet at the end of a hot riveting device presses the plastic rivet to ensure rivet formation. In the whole process of heating and pressing the rivet head for forming, the plastic material in the rivet head does not flow well, so the technology is not suitable for forming the composite material rivet with long fiber reinforced in the rivet head. In conclusion, an efficient and convenient connecting process widely applicable to composite rivet machining and forming is found, the application range of the composite rivet can be effectively widened, and the method has important significance for achieving the aim of structure light weight in the industrial industry.

Disclosure of Invention

The invention aims to provide a rivet welding process method capable of realizing efficient and convenient in-situ friction stir forming of a composite rivet, which is characterized in that the composite rivet is fixed in a prefabricated rivet hole in a back clamping mode, a high-speed rotating and downward-pressing stirring head is used for performing friction heat generation and upsetting pressing on resin at the end to be formed of the rivet, so that the softening and flowing of a matrix of the composite rivet head and the rotating, interlacing and redistribution of internal reinforcing fibers are promoted, and finally the in-situ friction stir forming of the rivet and the rivet welding connection between metal and composite plates under the action of the rivet are completed.

A rivet welding process method for in-situ friction stir forming of composite rivets comprises the following steps:

step 1, centering and positioning a prefabricated hole to be connected with an upper plate and a lower plate, inserting a composite rivet into the prefabricated hole to expose an end part to be formed, and fixing the back of the composite rivet by using a rigid constraint liner matched with the composite rivet in shape;

step 2, selecting a stirring head with the diameter of a shaft shoulder matched with the sum of the thicknesses of the upper plate and the lower plate, wherein the inner groove of the shaft shoulder meets the process requirement, installing the selected stirring head on a friction stir welding machine, centering and positioning the stirring head and a rivet, and setting welding process parameters and a stirring head walking path through a control panel of the friction stir welding machine;

step 3, the stirring head is driven by a main shaft of the friction stir welding machine to move to a specified position at a preset rotating speed and a binding speed, and the preset retention time is maintained; and the stirring head is rotationally pumped back under the driving of the main shaft of the friction stir welding machine, and the composite material rivet is molded after being cooled, so that the rivet welding joint is obtained.

The upper plate is made of a polymer material, the lower plate is made of a metal material, the thicknesses of the upper plate and the lower plate are both 1-50 mm, and the upper plate and the lower plate are arranged in an equal thickness or unequal thicknesses; the sum of the number of layers of the upper plate and the lower plate is 1-10 layers; the upper plate and the lower plate are plane plates, curved plates or complex-structure plates combined by planes and curved surfaces. In particular, the upper plate and the lower plate can also be made of the same material or different materials.

The prefabricated hole is cylindrical, truncated cone-shaped, polygonal column-shaped or prismoid-shaped, and the diameter is 2-40 mm.

The prefabricated hole is a threaded hole matched with the threaded rivet, a special-shaped hole matched with the stepped or tapered reducing rivet or a prefabricated hole suitable for a countersunk rivet and provided with countersinks at two ends.

The composite rivet is made of long fiber reinforced resin base, short carbon fiber reinforced resin base, particle reinforced resin base, metal or metal base composite material.

The part of the rivet rod of the composite material rivet, which extends out of the plate, is an end to be formed, the diameter of the end to be formed is not more than that of the rivet rod, the diameter of the rivet head of the non-forming end of the composite material rivet is more than that of the rivet rod of the composite material rivet, and the rivet head is semicircular, oblate, conical, square or polygonal; a taper hole, a straight-line-shaped groove or a cross-shaped groove matched with a rigid constraint liner is machined in the center of a rivet head of the non-forming end of the composite material rivet.

The end face of the rigid constraint liner, which is contacted with the rivet head of the composite material rivet, is provided with a circular, square, rectangular or polygonal groove; the center of the end face of the rigid constraint liner, which is contacted with the rivet head of the composite material rivet, is provided with a conical bulge, a straight bulge or a cross bulge.

The stirring head adopts a stirring head with a spherical groove on the end surface, a stirring head with a cylindrical groove on the end surface and a chamfer angle at the bottom of the groove, a stirring head with a spherical groove on the end surface and a diversion conical bulge in the groove, a stirring head with a spherical groove on the end surface and a diversion spiral arc-shaped groove in the groove, and a plane shaft shoulder stirring head suitable for forming a countersunk head rivet or a stirring head with a non-contact induction heating coil on the outer side; the diameter of the shaft shoulder of the stirring head is 4-80 mm. The end part of the groove is a plane and spherical groove, and a cylindrical groove with a chamfer or a groove with a reverse flow conical bulge can be manufactured according to the requirement.

The outer surface of the shaft shoulder of the stirring head is provided with one or more layers of coatings, and when the upper plate is made of hard alloy, in order to prevent the shaft shoulder of the stirring head from being worn, a wear-resistant coating is sprayed; when the upper plate is made of high-melting-point metal, a heat-insulating coating is sprayed to prevent the shaft shoulder of the stirring head from softening and deforming; when the upper plate is made of resin-based composite material, in order to prevent the shaft shoulder of the stirring head from being adhered with the material, a demoulding coating is sprayed.

The rotating speed of the stirring head is 50-10000 r/min; the speed of the downward rolling is 0.1-10 mm/min, the speed of the back pumping is 0.1-100 mm/min, and the preset retention time is 0-200 s.

The molding mode of the composite material rivet is divided into a single-side processing molding mode and a double-side processing molding mode, when the single-side processing molding mode is adopted, a to-be-molded end is processed by using a rotary stirring head, a back non-molded end is in a prefabricated mode, and a back rigid constraint liner is used for fixing in the riveting and welding process; when the double-side processing molding is adopted, the composite material rivet is inserted into the prefabricated holes of the upper plate and the lower plate, the upper end and the lower end of the rivet are exposed out of the part to be processed, and the two stirring head shaft shoulders in opposite rotating directions carry out friction stir rivet welding processing on the upper side and the lower side of the rivet to form the friction stir rivet welding joint formed by the double-side in-situ processing molding.

Rivet welding structures suitable for composite rivets can be divided into a plurality of different forms according to specific processes: the rivet welding structure is suitable for a rivet head which is spherical and convex, the rivet welding structure is suitable for a rivet head which is cylindrical and convex, the rivet welding structure is suitable for a rivet head end part with a groove, the rivet welding structure is suitable for a countersunk rivet, the rivet welding structure is suitable for a dimple rivet hole, the rivet welding structure is suitable for a composite material plate upper-arranged or a metal plate upper-arranged, and the rivet welding structure is suitable for a prefabricated fiber reinforced composite material rivet, a lower composite material plate integrated formed metal plate upper-arranged rivet welding structure and a composite material rivet double-sided processing formed rivet welding structure.

The invention has the beneficial effects that:

(1) the method solves the problems that the long fiber reinforced composite material rivet can not be formed by the traditional press riveting and impact riveting, and the flowability of the end part of the rivet is poor in the hot riveting forming process of the high molecular polymer rivet, and can efficiently and conveniently carry out forming processing on the composite material rivet in an assembly in situ or carry out in-situ repairability processing on the damaged rivet in the service process.

(2) In the process, the upper part of the rivet is softened and flows under the action of the friction heat and the downward binding force of the rotary stirring head, fibers in the finally formed rivet head are rotated, intertwined and rearranged, and the arrangement area of the fibers is larger than the diameter of the rivet hole, so that the axial and radial load resistance of the rivet can be greatly improved. In addition, if the upper plate is made of thermoplastic resin matrix composite material, the resin matrix on the upper part of the rivet and the resin matrix on the wall of the rivet hole are mixed and flow in the rivet welding process, the combination effect of the interface between the rivet and the rivet hole is far better than that of the common riveting mode, and the improvement of the strength and the good sealing performance of the rivet welding joint are also better than those of the common riveting mode.

(3) The connecting material has wide applicability, flexible and various rivet welding forms and no special requirements on the types (metal and nonmetal materials), the number of layers (double layers or multiple layers) and the shape (plane or curved surface) of the connecting plates.

(4) The material adaptability of the composite material rivet is wide. The rivet can be selected from polymer materials (containing long fibers, short fibers and particle reinforced resin matrix composite materials) and metals (containing metal matrix composite materials) according to the process requirements.

(5) The processing technology has strong expandability, and because the rotary stirring head which is contacted with the upper end part and the lower end part of the rivet and the back rigid constraint liner are designed in a split mode, the device is more rapid to disassemble and replace, and is more convenient to improve auxiliary technologies such as non-contact heating and the like aiming at the stirring head, thereby being beneficial to the technology expansion in the later period.

Drawings

FIG. 1 is a schematic diagram of the upper plate and the lower plate after welding and welding based on the rivet welding process method for composite material rivet in-situ friction stir forming of the invention;

FIG. 2 is a flow chart of a rivet welding process based on in-situ friction stir forming of composite rivets according to the present invention;

FIG. 3 is a schematic view of the mixing head of the present invention; wherein: FIG. 3(a) is a mixing head suitable for forming an oblate head rivet having an oblate spherical recess in the shoulder end; FIG. 3(b) is a schematic view of a mixing head suitable for cylindrical head rivet forming, having a cylindrical recess on the end face and a flow promoting chamfer at the edge of the bottom of the recess; FIG. 3(c) is a view of a mixing head suitable for forming an oblate head rivet, with an oblate spherical recess on the end face and a flow guide cone projection on the bottom of the recess; FIG. 3(d) is a view of a mixing head suitable for forming an oval head rivet, with an end surface having an oval recess with a spiral flow directing arcuate slot therein; FIG. 3(e) is a flat shoulder mixing head suitable for blind rivet forming; FIG. 3(f) is a view showing a stirring head equipped with a non-contact induction heating coil at the outer side thereof;

FIG. 4 is a schematic view of a rivet and rivet welding configuration suitable for use with the present invention; wherein: FIG. 4(a) is a rivet welding structure adapted for a rivet head with a spherical projection; FIG. 4(b) is a rivet welding structure suitable for a rivet head having a cylindrical protrusion; FIG. 4(c) is a rivet welding configuration suitable for a rivet head with a recess in the end; FIG. 4(d) is a rivet welding configuration suitable for a blind rivet; FIG. 4(e) is a rivet welding configuration suitable for use with a countersink; FIG. 4(f) is a rivet welding structure suitable for composite plate placement or metal plate placement; FIG. 4(g) is a top rivet welding structure for a metal plate suitable for integrally forming a preformed fiber-reinforced composite rivet and a bottom composite; fig. 4(h) shows a rivet welding structure formed by processing both sides of the composite rivet.

1. The composite material comprises an upper plate, 2 a lower plate, 3 prefabricated holes, 4 composite material rivets, 5 rigid constraint gaskets, 6 stirring heads, 7 rivet welding joints.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

A rivet welding process method for in-situ friction stir forming of composite rivets is shown in figures 1 and 2 and comprises the following steps:

step 1, centering and positioning a prefabricated hole 3 to be connected with an upper plate 1 and a lower plate 2, inserting a composite rivet 4 into the prefabricated hole 3 from the back to expose an end part to be formed and face a stirring head 6, fixing the back of the composite rivet 4 by a rigid constraint liner 5 matched with the composite rivet in shape, and matching the rigid constraint liner 5 with the composite rivet 4 for fixing the composite rivet 4;

step 2, selecting a stirring head 6 with the diameter of a shaft shoulder matched with the sum of the thicknesses of the upper plate 1 and the lower plate 2, wherein the inner groove of the shaft shoulder meets the process requirements, installing the selected stirring head 6 on a friction stir welding machine, centering and positioning the stirring head 6 and a rivet, and setting welding process parameters and a stirring head 6 walking path through a control panel of the friction stir welding machine;

step 3, the stirring head 6 is driven by a main shaft of the friction stir welding machine to move to a specified position at a preset rotating speed and a binding speed, and the preset retention time is maintained; and the stirring head 6 is rotationally pumped back under the driving of the main shaft of the friction stir welding machine, and the composite material rivet 4 is molded after cooling to obtain the rivet welding joint 7.

The upper plate 1 is made of a polymer material, the lower plate 2 is made of a metal material, the thicknesses of the upper plate 1 and the lower plate 2 are both 1-50 mm, and the upper plate 1 and the lower plate 2 are arranged in an equal thickness mode or in different thicknesses; the sum of the number of layers of the upper plate 1 and the lower plate 2 is 1-10 layers; the upper plate 1 and the lower plate 2 are flat plates, curved plates or plates with complex structures formed by combining the flat surfaces and the curved surfaces; the upper plate 1 and the lower plate 2 are made of the same material or different materials.

The prefabricated holes 3 are cylindrical, truncated cone-shaped, polygonal prism-shaped or prismatic frustum-shaped holes, and the diameter of the prefabricated holes is 2-40 mm.

The prefabricated hole 3 be with screw rivet complex screw hole, with notch cuttype or tapered reducing rivet complex abnormal shape hole or be applicable to the countersunk head rivet and both ends have the prefabricated hole 3 of dimple, the prefabricated hole 3 of dimple form is convenient for soften the flow of resin material in the forming process.

The composite material rivet 4 is made of long fiber reinforced resin base, short carbon fiber reinforced resin base, particle reinforced resin base, metal or metal base composite material, and the long fiber reinforced resin base rivet is internally provided with long fibers arranged at two sides or the periphery so as to enhance the rivet reinforcing effect.

The composite material rivet 4 comprises a rivet rod, an upper end to be formed and a back non-forming end, the part, extending out of the plate, of the rivet rod of the composite material rivet 4 is the end to be formed, the diameter of the end to be formed is smaller than or equal to that of the rivet rod, the diameter of a rivet head of the non-forming end of the composite material rivet 4 is larger than that of the rivet rod of the composite material rivet 4, and the rivet head is semicircular, oblate, conical, square or polygonal; in order to enhance the positioning and clamping constraint effect of the composite rivet, a taper hole, a straight-line-shaped groove or a cross-shaped groove matched with a rigid constraint liner is processed in the center of the rivet head of the non-forming end of the composite rivet 4.

The end face of the rigid constraint liner, which is in contact with the rivet head of the composite material rivet 4, is provided with a circular, square, rectangular or polygonal groove; the center of the end face of the rigid constraint liner, which is contacted with the rivet head of the composite material rivet 4, is provided with a conical bulge, a straight bulge or a cross bulge.

The stirring head 6 adopts a stirring head with a spherical groove on the end surface, a stirring head with a cylindrical groove on the end surface and a chamfer angle at the bottom of the groove, a stirring head with a spherical groove on the end surface and a diversion conical bulge in the groove, a stirring head with a spherical groove on the end surface and a diversion spiral arc-shaped groove in the groove, and a stirring head with a plane shaft shoulder or a stirring head with a non-contact induction heating coil on the outer side, which is suitable for forming a countersunk head rivet, as shown in figure 3; the diameter of the 6 shaft shoulders of the stirring head is 4-80 mm. The end part of the rivet is provided with a plane and a spherical groove, a cylindrical groove with a chamfer or a groove with a backflow conical bulge can be manufactured according to the requirement, the stirring head 6 is used for providing rotary friction heat and axial upsetting force of the composite material rivet 4 in the rivet welding process, and in order to improve the flowing effect of the material at the rivet forming end, the stirring head with the spherical groove at the end surface and the flow guide conical bulge in the groove can improve the flowing of a resin matrix in the forming process and facilitate the arrangement of internal fibers to the periphery; in order to reduce the rotating speed of the stirring head 6 under the condition of ensuring sufficient heat input so as to prevent the fibers in the composite material rivet 4 from being broken by overlarge rotating shearing force, the stirring head with the non-contact induction heating coil arranged on the outer side can perform induction auxiliary heating on the stirring head 6 in the riveting and welding process so as to ensure sufficient heat input at the molding part of the composite material rivet 4.

The outer surface of the shaft shoulder of the stirring head 6 is provided with one or more layers of coatings, and when the upper plate is made of hard alloy, in order to prevent the shaft shoulder of the stirring head from being worn, a wear-resistant coating is sprayed; when the upper plate is made of high-melting-point metal, a heat-insulating coating is sprayed to prevent the shaft shoulder of the stirring head from softening and deforming; when the upper plate is made of resin-based composite material, in order to prevent the shaft shoulder of the stirring head from being adhered with the material, a demoulding coating is sprayed.

The rotating speed of the stirring head 6 is 50-10000 r/min; the speed of the downward rolling is 0.1-10 mm/min, the speed of the back pumping is 0.1-100 mm/min, and the preset retention time is 0-200 s.

The forming mode of the composite material rivet 4 is divided into a single-side processing forming mode and a double-side processing forming mode, when the single-side processing forming mode is adopted, namely, a to-be-formed end is processed by using a rotary stirring head 6, a back non-formed end is in a prefabricated form, and a back rigid constraint gasket is used for fixing in the riveting and welding process; when the double-side processing molding is adopted, the composite material rivet 4 is inserted into the prefabricated holes 3 of the upper plate 1 and the lower plate 2, the upper end and the lower end of the rivet are exposed out of the part to be processed, and the two shaft shoulders of the two stirring heads 6 in opposite rotating directions carry out friction stir rivet welding processing on the upper side and the lower side of the rivet to form a friction stir rivet welding joint 7 formed by double-side in-situ processing molding.

The rivet welding structure can be divided into a plurality of different forms according to specific processes: the rivet welding structure is suitable for a rivet head which is spherical and convex, the rivet welding structure is suitable for a rivet head which is cylindrical and convex, the rivet welding structure is suitable for a rivet head end part with a groove, the rivet welding structure is suitable for a countersunk rivet, the rivet welding structure is suitable for a dimple, the rivet welding structure is suitable for a composite material plate upper or a metal plate upper, and the rivet welding structure is suitable for a metal plate upper rivet welding structure of the prefabricated fiber reinforced composite material rivet 4 and a lower composite material plate integrated molding and the rivet welding structure of the composite material rivet 4 double-face processing molding, as shown in figure 4.