CN-121973455-A - Friction stir welding method with welding interface fiber filling

Abstract

The invention provides a friction stir welding method filled with fiber at a welding interface, which comprises the steps of preparing composite particles with carbon fiber, cleaning and clamping a fiber reinforced thermoplastic resin matrix composite board, preheating a welding tool of friction stir welding equipment to a set temperature, arranging an axial through hole on a stirring needle of the welding tool, arranging the lower end of the axial through hole at the lower end of the stirring needle, arranging a jacking mechanism at the top of the axial through hole, jacking the composite particles in the axial through hole to the lower end of the stirring needle through the jacking mechanism, welding, and cooling a workpiece. By adopting the scheme of the invention, the interface shearing resistance and the connection strength of the FRP plate friction stir welding joint can be greatly improved, and long fiber yarns can be implanted in a base material near the interface of the weld joint along with welding, so that the continuous fiber longitudinal reinforcement and the transverse reinforcement of the weld joint are realized.

Inventors

• ZHOU LI
• LIU YUCHUN
• SONG XIAOGUO
• DONG JING
• GAO SHIKANG
• LIANG TAO
• WANG XINBO

Assignees

• 哈尔滨工业大学（威海）
• 青岛哈尔滨工业大学(威海)研究院

Dates

Publication Date

20260505

Application Date

20260324

Claims (7)

1. 1. The friction stir welding method filled with the welding interface fibers is characterized by comprising the following steps of: step 1, preparing composite particles with carbon fiber wires, and loading the composite particles into a microsphere feeding system of a friction stir welding device; step 2, cleaning and clamping the fiber reinforced thermoplastic resin matrix composite board; step 3, presetting a welding tool of the friction stir welding equipment to a set temperature which is 50-80 ℃, wherein a stirring needle of the welding tool is provided with an axial through hole, the lower end of the axial through hole is positioned at the lower end of the stirring needle, and the top of the axial through hole is provided with a jacking mechanism, so that composite particles in the axial through hole can be jacked to the lower end of the stirring needle through the jacking mechanism; Step 4, moving the welding tool to a welding starting point, setting friction stir welding parameters, and then starting to weld; And 5, after the welding is finished, cooling the workpiece.
2. 2. The friction stir welding method according to claim 1, wherein the composite particles comprise thermoplastic resin spheres and carbon fiber filaments embedded in the thermoplastic resin spheres, and wherein individual carbon fiber filaments in the thermoplastic resin spheres have a length of not less than 40cm.
3. 3. The friction stir welding method of claim 2 wherein the method of preparing the composite particles with filaments comprises rolling carbon filaments into clusters, placing the clusters in a resin powder to substantially encapsulate the carbon filaments, and forming the composite particles by melting, maintaining the temperature and solidifying.
4. 4. A friction stir welding method according to claim 3 wherein the step of winding carbon fiber filaments into a cluster body comprises winding the carbon fiber filaments around a needle body having a diameter of not more than 0.5mm, removing the filaments from the needle body, compacting the filaments, and then dropping a molten resin and rounding the filaments to obtain the cluster body.
5. 5. A friction stir welding method according to any one of claims 1 to 4 wherein during the welding process, the composite particles are plasticized by the pin and a portion of the carbon fiber filaments of the composite particles are embedded in the base material.
6. 6. The friction stir welding method according to claim 5, wherein the friction stir welding parameters include a tool inclination angle of 1 to 3 °, a shoulder press amount of 0.1 to 0.3mm, a tool rotation speed of 500 to 3000rpm, and a welding speed of 500 to 3000mm/min.
7. 7. The friction stir welding method according to claim 6, wherein the penetration depth of the lower end of the stirring pin is just at the lap joint interface of the base material.

Description

Friction stir welding method with welding interface fiber filling Technical Field The invention relates to the technical field of friction stir welding, in particular to a friction stir welding method filled with welding interface fibers. Background With the continuous development of lightweight technology, fiber (chopped fiber) reinforced thermoplastic resin matrix composites (Fiber Reinforced Polymer, abbreviated as FRP) are increasingly becoming emerging materials widely used in the fields of aerospace, rail transit, vehicle manufacturing, etc. due to their excellent service performance and lightweight characteristics. Common methods of FRP material attachment include mechanical attachment, cementing, and welding. The mechanical connection needs to be additionally added with structural members, so that the weight increment of the whole structure and the stress concentration are easily caused, the service life of the plate is influenced, the cementing and curing time is relatively long, and the joint strength is easily influenced by the environment. Friction stir welding is used as a solid phase connection technology and has certain advantages in the field of welding of low-melting-point materials. At present, a certain research is conducted on the aspects of welding tool design, material weldability, connection principle, mechanical properties of a post-welding joint and the like of friction stir welding of thermoplastic resin matrix composite materials. But the whole is still in the laboratory research stage, and the practical industrial application is less. One key reason is that for friction stir welding of conventional FRP materials, the properties of the interface position materials are changed after the interface position materials undergo welding thermal cycles during welding, the strength of the welded joint is obviously reduced compared with that of a base material, and the shearing resistance of a weld joint interface is poor. In the prior art, ghasemi et al have found that the joint strength is only 25% of the base material by using friction stir welding technique to connect carbon fiber reinforced polypropylene composite materials. Therefore, how to improve the joint strength of FRP sheets in particular and the shear resistance of the weld joint interface is a problem to be solved. Disclosure of Invention At least aiming at the technical problems in the background art, the invention aims to provide a friction stir welding method filled with welding interface fibers. The invention adopts the following technical scheme. A friction stir welding method filled with welding interface fibers comprises the following steps: step 1, preparing composite particles with carbon fiber wires, and loading the composite particles into a microsphere feeding system of a friction stir welding device; step 2, cleaning and clamping the fiber reinforced thermoplastic resin matrix composite board; Step 3, preheating a welding tool of the friction stir welding equipment to a set temperature, wherein the set temperature is 50-80 ℃, a stirring needle of the welding tool is provided with an axial through hole, the lower end of the axial through hole is positioned at the lower end of the stirring needle, the top of the axial through hole is provided with a jacking mechanism, and composite particles in the axial through hole can be jacked to the lower end of the stirring needle through the jacking mechanism; Step 4, moving the welding tool to a welding starting point, setting friction stir welding parameters, and then starting to weld; And 5, after the welding is finished, cooling the workpiece. Preferably, the composite particles comprise thermoplastic resin spheres and carbon fiber filaments embedded in the thermoplastic resin spheres, the individual carbon fiber filaments in the thermoplastic resin spheres having a length of not less than 20cm. Further, the method for preparing the composite particles with the fiber filaments comprises the steps of firstly rolling the carbon fiber filaments into a cluster body, then placing the cluster body into resin powder to enable the resin powder to fully wrap the carbon fiber filaments, and then forming the composite particles after the steps of heating, melting, heat preservation, cooling (naturally cooling to room temperature) solidification. Wherein, the heating and melting process is that the cluster body coated by the resin powder is sent into a curing furnace for heating, the heating temperature is higher than the melting temperature (or viscous flow temperature) of the resin material and lower than the thermal decomposition temperature of the resin material, and the heat preservation time is determined according to the viscosity of the resin, so that the resin powder is observed to be converted into liquid state and not dripped to be optimal. Further, the step of winding the carbon fiber filaments into a cluster body comprises the steps of winding the carbon fiber filaments