A friction stir welding method for connecting metal and resin materials based on zoning

Abstract

The application provides a friction stir welding method for connecting metal and resin material based on partition. The steps include: surface treatment of the metal plate to be welded, partitioning the connecting part between the surface of the metal plate to be welded and the surface of the resin plate into a core connecting area, a middle connecting area and an outer connecting area, two middle connecting areas are located on both sides of the core connecting area, and two outer connecting areas are located on the outer sides of the middle connecting areas; fixing the resin plate and the metal plate on a welding workbench, the metal plate is located above the resin plate, and the connecting surface of the metal plate is attached to the upper surface of the resin plate; installing the friction stir welding tool, so that the static shoulder lower plane and the dynamic shoulder lower plane of the friction stir welding tool coincide with the working surface; setting the welding process parameters and then performing welding, and cooling and solidifying to form a weld after the welding is completed. The application greatly improves the interface connecting strength and tensile performance of the metal material / resin structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal and non-metal connection by friction stir welding, and particularly relates to a friction stir welding method for connecting metal and resin material based on partition. BACKGROUND

[0002] Lightweight structure has experienced a development process from traditional high-strength steel to light high-strength aluminum and magnesium alloy, and then to carbon fiber reinforced resin matrix composite (CFRP). Aluminum alloy, magnesium alloy and other metal materials have the advantages of light weight, high strength, good ductility, heat resistance and corrosion resistance, and are currently the mainstream load-bearing components of vehicle body structure. CFRP has the advantages of small density, high specific strength, good corrosion resistance, strong energy absorption and impact resistance, and easy recycling, and has broad application prospects in structural weight reduction. The combination of metal materials and CFRP can maximize the performance advantages of the two materials, and further meet the technical requirements of lightweight, improve the overall performance of the structure, and further achieve emission reduction and consumption reduction. However, the traditional metal material / CFRP connection process still uses mechanical connection, which introduces fasteners such as rivets and bolts, and has the problems of structure weight increase and stress concentration at the connection point. In addition, the commonly used adhesive connection method for metal material / CFRP has the problems of long curing time of the adhesive layer, easy aging failure due to temperature and humidity, etc.

[0003] Although laser welding, resistance welding, friction stir welding and other thermal connection methods have been used to realize the connection of metal materials and CFRP plates, the joint strength obtained by the existing methods is limited, and it is difficult to meet the industrial application requirements. Therefore, it is urgent to develop new process methods to enhance the interface connection strength of metal material / CFRP.

[0004] In the prior art, document CN2016108089101 discloses a method for connecting metal material and resin matrix composite by friction stir welding, which uses an integrated friction stir welding tool of shaft shoulder / stirring pin, and performs welding in the form of metal plate on the top and resin matrix composite on the bottom. The stirring pin penetrates into the metal plate without entering the FRP material, and preliminarily realizes the connection of metal and FRP. However, the resin material is extruded due to thermal pressure at the interface position, resulting in limited interface connection strength.

[0005] In order to further expand the application range of metal material / CFRP composite structure, how to realize high-strength connection of metal material / CFRP composite structure interface, shorten the connection time, improve engineering efficiency, and meet the service requirements of metal material / CFRP structure under different working conditions is a technical bottleneck that needs to be broken through in the field. SUMMARY

[0006] At least in order to solve the technical problems mentioned in the background, the present application aims to provide a friction stir welding method for connecting metal and resin material based on zoning.

[0007] The present application adopts the following technical solutions.

[0008] A friction stir welding method for connecting metal and resin material based on zoning, the steps comprising:

[0009] Step 1, surface treatment of the metal plate to be welded, along the width direction of the connecting part, the connecting part of the surface of the metal plate to be welded and the surface of the resin plate is divided into core connecting area, middle connecting area and outer connecting area, two middle connecting areas are located on both sides of the core connecting area, and two outer connecting areas are located on the outer side of the middle connecting area; wherein, a chemical film layer capable of connecting metal and resin through chemical bond is coated on the surface of the metal plate to be welded located in the middle connecting area, and surface micro-texture is arranged on the surface of the metal plate to be welded located in the outer connecting area;

[0010] Step 2, fix the resin plate and the metal plate on the welding workbench, the metal plate is located above the resin plate, and the connecting surface of the metal plate is attached to the upper surface of the resin plate; install the friction stir welding tool, so that the static shaft shoulder lower plane, the dynamic shaft shoulder lower plane and the working surface of the friction stir welding tool coincide;

[0011] Step 3, after setting the welding process parameters, implement welding, and after welding, cool and solidify to form a weld.

[0012] In the present application, the core connecting area corresponds to the working area of the stirring pin, the stirring pin passes through the core connecting area and extends downward to the core connecting area in the resin material, under the stirring action of the stirring pin, the metal and non-metal in the core connecting area are fused and interlocked into one, forming a fused and interlocked connecting structure, and the interface of the core connecting area is in the form of a wave structure arranged at intervals.

[0013] In the present application, the middle connecting area corresponds to the working area of the dynamic shaft shoulder, under the rotation of the dynamic shaft shoulder and the stirring pin, the metal plate and the resin plate are connected together through chemical bond.

[0014] In the present application, the outer connecting area corresponds to the working area of the static shaft shoulder, under the pressure action of the static shaft shoulder, the non-metal is embedded in the surface micro-texture of the metal plate to realize the mutual embedding connection of the metal plate and the resin plate.

[0015] In order to further improve the connection strength of the metal and the resin material, two sets of auxiliary friction tools are arranged at the outer boundary of the outer connection area, the auxiliary stirring pins and the stirring pins of the two sets of auxiliary friction tools are arranged in a triangular shape in the plane direction, and the axis of the auxiliary stirring pin is coincided with the outer boundary of the outer connection area; during the welding process, the two sets of auxiliary friction tools and the stirring pins are synchronously operated, so that the outer connection area of the metal plate and the resin plate gradually transitions from the mechanical embedding structure to the fusion interlocking connection structure.

[0016] As a preferred scheme, the metal plate is an aluminum alloy plate or a magnesium alloy plate, and the resin plate is a carbon fiber reinforced resin-based composite plate.

[0017] As a preferred scheme, the gap between the static shaft shoulder and the dynamic shaft shoulder is controlled to be 0.3-0.6mm, the dynamic shaft shoulder is located in the inner cavity of the static shaft shoulder, the inner diameter of the dynamic shaft shoulder is 10mm-20mm, and the outer diameter of the static shaft shoulder is 15mm-30mm; the outer side wall of the stirring pin has a threaded structure, and the cross section of the stirring pin is cylindrical or polygonal.

[0018] In the application, the width of the core connection area is 1-2mm larger than the diameter of the top of the stirring pin, the total width of the middle connection area is 2-5mm larger than the outer diameter of the dynamic shaft shoulder, and the total width of the outer connection area is 5-10mm larger than the outer diameter of the static shaft shoulder.

[0019] As a preferred scheme, the method for realizing surface micro-texturing on the surface of the metal plate to be welded adopts laser texturing, sandblasting treatment or chemical etching; the chemical film layer for realizing the chemical bond connection between the metal and the resin adopts silane coupling agent, aluminate coupling agent or phthalate coupling agent.

[0020] As a preferred scheme, the welding tool rotation speed is controlled to be 500rpm-2000rpm; the welding speed is controlled to be 500mm / min-2000mm / min; the pressing amount of the lower end of the static shaft shoulder on the upper surface of the metal plate to be welded is 0.4mm-0.6mm; the cooling and solidification cooling gradient is 10℃ / min, and the air humidity is controlled to be 20-30%.

[0021] Beneficial effects: compared with the connection mode implemented by using the conventional friction stir welding, the scheme of the application greatly improves the interface connection strength and tensile performance of the metal material / resin structure, and compared with the same specification of the connected material, the interface connection strength can be improved by three times or even more.

[0022] The metal material / resin structure part processed by the scheme of the present application has a connection part in a regional composite connection structure, the metal and non-metal in the core connection area are fused and interlocked to form a fused interlocked connection structure, the middle connection area is connected together by chemical bonds under the rotation of the dynamic shaft shoulder and the stirring needle, and the outer connection area is embedded in the micro-texture on the surface of the metal plate under the pressure of the static shaft shoulder to realize the mutual embedding of the metal plate and the resin plate. Through the mutual cooperation of the connection structures in the three areas, the connection interface of the metal plate and the resin plate has excellent mechanical properties, and is suitable for use in more complex working conditions. In a further scheme, the outer connection area of the metal plate and the resin plate gradually transitions from the mechanical embedding structure to the fused interlocked connection structure outward, which can more effectively prevent the connection structure from failing under impact and tension. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The connection interface of the metal plate and the resin plate in Example 1 is shown schematically;

[0024] Figure 2 The connection interface of the metal plate and the resin plate in Example 2 is shown schematically;

[0025] Figure 3 The arrangement of the stirring pins of the two sets of auxiliary friction stir tools in Example 2 is shown schematically, and the direction indicated by the arrow in the figure represents the direction of travel of the friction stir welding tool;

[0026] Figure 4 The micrograph of the connection interface of the metal plate and the resin plate in Example 1 is shown (23X3=69 pictures were taken at a basic magnification of 139X by an optical microscope, and a high-quality macroscopic panoramic picture was formed by splicing them together). DETAILED DESCRIPTION

[0027] The technical solutions in the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0028] Example 1

[0029] In combination Figure 1As shown, the friction stir welding tool used in Example 1 includes coaxially arranged dynamic shaft shoulder 1 and static shaft shoulder 2, the lower end of dynamic shaft shoulder 1 is connected with stirring pin 5, the gap between static shaft shoulder 2 and dynamic shaft shoulder 1 is controlled to be 0.5mm, and dynamic shaft 1 is located in the inner cavity of static shaft shoulder, the inner diameter of dynamic shaft shoulder 1 is 15mm, the outer diameter of static shaft shoulder 2 is 20mm, the outer side wall of stirring pin 5 has a threaded structure, and the cross section of stirring pin 5 is cylindrical.

[0030] A friction stir welding method for connecting metal and resin material based on zoning, the steps include:

[0031] Step 1, surface treatment of the metal plate 3 to be welded (6061-T6 aluminum alloy plate with a thickness of 3mm), along the width direction of the connecting part, the connecting part between the surface of the metal plate 3 to be welded and the surface of the resin plate 4 (30% chopped carbon fiber reinforced PA66 plate) is divided into core connecting area 12, middle connecting area 11 and outer connecting area 10, two middle connecting areas 11 are located on both sides of the core connecting area 12, and two outer connecting areas 10 are respectively located on the outer side of the middle connecting area 11; wherein, a chemical film layer capable of connecting metal and resin by chemical bond is coated on the surface of the metal plate 3 to be welded located in the middle connecting area 11, and surface micro-texture is arranged on the surface of the metal plate 3 to be welded located in the outer connecting area 10;

[0032] Wherein, the method for realizing surface micro-texture on the surface of the metal plate 3 to be welded adopts laser texturing process, and the chemical film layer for realizing chemical bond connection between metal and resin adopts silane coupling agent;

[0033] Step 2, fix the resin plate 4 and the metal plate 3 to be welded on the welding workbench, the metal plate 3 to be welded is located above the resin plate 4, and the connecting surface of the metal plate 3 to be welded is attached to the upper surface of the resin plate 4; install the friction stir welding tool, so that the lower plane of static shaft shoulder 2 and the lower plane of dynamic shaft shoulder 1 of the friction stir welding tool are coincident with the working surface (the upper surface of the metal plate 3 to be welded);

[0034] Step 3, after setting the welding process parameters, implement welding, and after welding, cool and solidify to form a weld;

[0035] Wherein, the rotating speed of the tool is controlled to be 600rpm, the welding speed is controlled to be 800mm / min, the amount of depression of the lower end of static shaft shoulder 2 on the upper surface of the surface of the metal plate 3 to be welded is 0.5mm, the cooling and solidification temperature gradient is 10℃ / min, and the air humidity is controlled to be 25%.

[0036] During the machining process, the following points are combined Figure 4As shown, the core connecting area 12 corresponds to the working area of the stirring needle 5, the stirring needle 5 passes through the core connecting area 12 and extends downward into the resin material, under the stirring action of the stirring needle 5, the metal and non-metal of the core connecting area 12 are fused and interlocked into one, forming a fused and interlocked connecting structure (i.e. a macroscopic mechanical interlocking mechanism is reformed), and the interface of the core connecting area 12 is arranged in a spaced wave structure (due to the stirring action of the stirring needle 5, and under the restriction of the outer connecting area 10 and the middle connecting area 11, the interface of the core connecting area 12 along the width direction of the connecting part is as shown in the wave structure, the core connecting area 12 is arranged in a spaced interface structure along the length direction of the connecting part, and part of the non-metal (resin) is embedded in the metal (aluminum alloy) in the form of a block, such a core connecting area 12 has very high connecting strength, and can effectively prevent the interface of the connecting structure from being transversely torn or dislocated, thereby solving the technical problem that the aluminum alloy plate and the resin plate are prone to transverse failure when connected, while ensuring the longitudinal stability of the connecting structure); the middle connecting area 11 corresponds to the working area of the dynamic shaft shoulder 1, under the rotation action of the dynamic shaft shoulder 1 and the stirring needle 5, the metal plate 3 and the resin plate 4 are connected together through chemical bonds; the outer connecting area 10 corresponds to the working area of the static shaft shoulder 2, under the pressure action of the static shaft shoulder 2, the metal plate 3 and the resin plate 4 are embedded in each other through the non-metal embedded in the micro-texture on the surface of the metal plate 3. The width of the core connecting area 12 is 1-2mm larger than the diameter of the top of the stirring needle 5, the total width of the middle connecting area 11 is 2-5mm larger than the outer diameter of the dynamic shaft shoulder 1, and the total width of the outer connecting area 10 is 5-10mm larger than the outer diameter of the static shaft shoulder 2. Figure 4 As shown in the wave structure, the core connecting area 12 is arranged in a spaced interface structure along the length direction of the connecting part, and part of the non-metal (resin) is embedded in the metal (aluminum alloy) in the form of a block, such a core connecting area 12 has very high connecting strength, and can effectively prevent the interface of the connecting structure from being transversely torn or dislocated, thereby solving the technical problem that the aluminum alloy plate and the resin plate are prone to transverse failure when connected, while ensuring the longitudinal stability of the connecting structure); the middle connecting area 11 corresponds to the working area of the dynamic shaft shoulder 1, under the rotation action of the dynamic shaft shoulder 1 and the stirring needle 5, the metal plate 3 and the resin plate 4 are connected together through chemical bonds; the outer connecting area 10 corresponds to the working area of the static shaft shoulder 2, under the pressure action of the static shaft shoulder 2, the metal plate 3 and the resin plate 4 are embedded in each other through the non-metal embedded in the micro-texture on the surface of the metal plate 3. The width of the core connecting area 12 is 1-2mm larger than the diameter of the top of the stirring needle 5, the total width of the middle connecting area 11 is 2-5mm larger than the outer diameter of the dynamic shaft shoulder 1, and the total width of the outer connecting area 10 is 5-10mm larger than the outer diameter of the static shaft shoulder 2. Figure 4 As shown in the wave structure, the core connecting area 12 is arranged in a spaced interface structure along the length direction of the connecting part, and part of the non-metal (resin) is embedded in the metal (aluminum alloy) in the form of a block, such a core connecting area 12 has very high connecting strength, and can effectively prevent the interface of the connecting structure from being transversely torn or dislocated, thereby solving the technical problem that the aluminum alloy plate and the resin plate are prone to transverse failure when connected, while ensuring the longitudinal stability of the connecting structure); the middle connecting area 11 corresponds to the working area of the dynamic shaft shoulder 1, under the rotation action of the dynamic shaft shoulder 1 and the stirring needle 5, the metal plate 3 and the resin plate 4 are connected together through chemical bonds; the outer connecting area 10 corresponds to the working area of the static shaft shoulder 2, under the pressure action of the static shaft shoulder 2, the metal plate 3 and the resin plate 4 are embedded in each other through the non-metal embedded in the micro-texture on the surface of the metal plate 3. The width of the core connecting area 12 is 1-2mm larger than the diameter of the top of the stirring needle 5, the total width of the middle connecting area 11 is 2-5mm larger than the outer diameter of the dynamic shaft shoulder 1, and the total width of the outer connecting area 10 is 5-10mm larger than the outer diameter of the static shaft shoulder 2.

[0037] In the comparative scheme, on the basis of example 1, the static shaft shoulder 2 is omitted, and the outer connecting area 10 and the middle connecting area 11 are also omitted, that is, only the dynamic shaft shoulder 1 and the stirring needle 5 are used to connect the aluminum alloy plate and the resin plate (30% chopped carbon fiber reinforced PA66 plate), and the results show that only part of the resin extends into the aluminum alloy matrix in the area passed by the stirring needle to form a connecting structure, and the cross section of the connecting structure is an irregular cluster structure (in essence, a conventional friction stir welding connecting structure).

[0038] The mechanical property test (tensile mode is to pull the aluminum alloy plate and the resin plate along the width direction of the connecting part, the sample overlap width is 40mm, and the tensile rate is 0.5mm / min) is performed on the connecting structure of the metal plate 3 (aluminum alloy) and the resin plate 4 (30% chopped carbon fiber reinforced PA66 plate) prepared in this example, and the results show that the tensile shear strength is 1035N; while the tensile shear strength of the connecting structure sample in the comparative scheme is only about 302N.

[0039] Example 2

[0040] In combinationFigure 2 and Figure 3 As shown in FIG. 2, the friction stir welding tool used in Example 2 includes coaxially arranged dynamic shoulder 1 and static shoulder 2, the lower end of dynamic shoulder 1 is connected with stir pin 5, the gap between static shoulder 2 and dynamic shoulder 1 is controlled to be 0.5 mm, and dynamic shoulder 1 is located in the inner cavity of static shoulder 2, the inner diameter of dynamic shoulder 1 is 15 mm, the outer diameter of static shoulder 2 is 20 mm, the outer side wall of stir pin 5 has a threaded structure, and the cross section of stir pin 5 is cylindrical. Two sets of auxiliary friction stir tools are arranged at the outer boundary of outer joint area 10, the auxiliary stir pins 8 and stir pin 5 of the two sets of auxiliary friction stir tools are arranged in a triangular shape in the plane direction, and the axis of auxiliary stir pin 8 coincides with the outer boundary of outer joint area 10.

[0041] A friction stir welding method for connecting metal and resin material based on zoning, the steps comprising:

[0042] Step 1, surface treatment of the metal plate 3 to be welded (6061-T6 aluminum alloy plate with a thickness of 3.5 mm), along the width direction of the joint, the joint between the surface of the metal plate 3 to be welded and the surface of the resin plate 4 (30% chopped carbon fiber reinforced PA66 plate) is divided into core joint area 12, middle joint area 11 and outer joint area 10, two middle joint areas 11 are located on both sides of core joint area 12, and two outer joint areas 10 are respectively located on the outer side of middle joint area 11; wherein, a chemical film layer capable of connecting metal and resin by chemical bond is coated on the surface of the metal plate 3 to be welded located in the middle joint area 11, and surface micro-texture is provided on the surface of the metal plate 3 to be welded located in the outer joint area 10;

[0043] Wherein, the method for realizing surface micro-texture on the surface of the metal plate 3 to be welded adopts chemical etching process, and the chemical film layer for realizing chemical bond connection between metal and resin adopts aluminate coupling agent;

[0044] Step 2, fixing the resin plate 4 and the metal plate 3 on the welding workbench, the metal plate 3 is located above the resin plate 4, and the connecting surface of the metal plate 3 is attached to the upper surface of the resin plate 4; installing the friction stir welding tool, so that the lower plane of static shoulder 2 and the lower plane of dynamic shoulder 1 of the friction stir welding tool coincide with the working surface (the upper surface of the metal plate 3);

[0045] Step 3, after setting the welding process parameters, welding is carried out, and after welding, the weld is formed after cooling and solidification;

[0046] Wherein, the rotation speed of the tool is controlled to be 700 rpm, the welding speed is controlled to be 600 mm / min, the amount of pressing the lower end of static shoulder 2 on the upper surface of the surface of the metal plate 3 to be welded is 0.4 mm, the cooling and solidification temperature gradient is 10 ℃ / min, and the air humidity is controlled to be 20%.

[0047] During the processing, the core connecting area 12 corresponds to the working area of the stirring needle 5, the stirring needle 5 penetrates through the core connecting area 12 and extends downward into the core connecting area 12 of the resin material, under the stirring action of the stirring needle 5, the metal and non-metal of the core connecting area 12 are fused and interlocked into one, forming a fused interlocking connection structure (i.e. a macroscopic mechanical interlocking mechanism is reformed); the middle connecting area 11 corresponds to the working area of the dynamic shaft shoulder 1, under the rotating action of the dynamic shaft shoulder 1 and the stirring needle 5, the metal plate 3 and the resin plate 4 are connected together through chemical bonds; the outer connecting area 10 corresponds to the working area of the static shaft shoulder 2, under the pressure action of the static shaft shoulder 2, the metal plate 3 and the resin plate 4 are embedded in each other through the non-metal embedded in the micro-texture on the surface of the metal plate 3. At the same time, the two sets of auxiliary friction stir tools and the stirring needle 5 operate synchronously to make the outer connecting area 10 of the metal plate 3 and the resin plate 4 gradually transition from the mechanical embedding structure to the fused interlocking connection structure. Among them, the width of the core connecting area 12 is 1-2mm larger than the top diameter of the stirring needle 5, the total width of the middle connecting area 11 is 2-5mm larger than the outer diameter of the dynamic shaft shoulder 1, and the total width of the outer connecting area 10 is 5-10mm larger than the outer diameter of the static shaft shoulder 2.

[0048] During the implementation process, when the metal plate 3 is surface treated, the surface of the metal plate 3 is divided into multiple areas (including the core connecting area 12, the middle connecting area 11 and the outer connecting area 10) with the center of the action area of the stirring needle 5 as the reference, then the surface micro-texture is processed on the corresponding area of the surface of the metal plate 3 in an inert environment, then the surface of the metal plate 3 is coated with a film (polyethylene film) to prevent the surface from being oxidized again in an inert environment, then the film layer of the middle connecting area 11 is quickly coated on the surface of the metal plate 3 after being torn off, then the metal plate 3 is quickly adhered to the resin plate 4 after the film layer on the surface of the metal plate 3 is torn off, and finally the stirring friction welding is implemented after clamping and fixing.

Claims

1. A friction stir welding method for joining metal and resin materials based on partitioning, characterized in that the steps include... include: Step 1: Surface treatment of the metal sheet to be welded. Along the width direction of the connection area, the connection area between the surface of the metal sheet to be welded and the surface of the resin sheet is divided into a core connection area, a middle connection area, and an outer connection area. Two middle connection areas are located on both sides of the core connection area, and two outer connection areas are located on the outside of the middle connection area. Among them, a chemical film layer that can connect the metal and the resin through chemical bonds is coated on the surface of the metal sheet to be welded located in the middle connection area, and a surface microtexture is set on the surface of the metal sheet to be welded located in the outer connection area. The core connection area corresponds to the working area of ​​the stirring needle. The stirring needle passes through the core connection area and extends downward into the core connection area within the resin material. Under the stirring action of the stirring needle, the metal and non-metal of the core connection area fuse and interlock into one, forming a fused and interlocked connection structure. The interface of the core connection area has a wave-like structure with intervals. The external connection area corresponds to the stationary shoulder working area. Under the pressure of the stationary shoulder, the metal plate and the resin plate are interlocked by non-metallic materials embedded in the micro-texture on the surface of the metal plate. Step 2: Fix the resin plate and the metal plate on the welding worktable, with the metal plate above the resin plate and the connecting surface of the metal plate against the upper surface of the resin plate; install the friction stir welding tool, making the lower plane of the stationary shoulder and the lower plane of the moving shoulder of the friction stir welding tool coincide with the working surface; Step 3: After setting the welding process parameters, carry out the welding. After the welding is completed, cool and solidify to form a weld. Two sets of auxiliary friction stir tools are arranged at the outer boundary of the external connection area. The auxiliary stirring pins and stirring pins of the two sets of auxiliary friction stir tools are arranged in a triangular shape in the plane direction, and the axis of the auxiliary stirring pins coincides with the outer boundary of the external connection area. During the welding process, the two sets of auxiliary friction stir tools and stirring pins operate synchronously so that the external connection area between the metal plate and the resin plate gradually transitions from a mechanical interlocking structure to a fusion interlocking connection structure.

2. The friction stir welding method according to claim 1, characterized in that: The central connecting area corresponds to the working area of ​​the moving shaft shoulder. Under the rotational action of the moving shaft shoulder and the stirring needle, the metal plate and the resin plate are connected together by chemical bonds.

3. The friction stir welding method according to any one of claims 1-2, characterized in that: The metal sheet is an aluminum alloy sheet or a magnesium alloy sheet, and the resin sheet is a carbon fiber reinforced resin-based composite board.

4. The friction stir welding method according to claim 3, characterized in that: The gap between the stationary shoulder and the moving shoulder is controlled to be 0.3~0.6mm, and the moving shoulder is located in the inner cavity of the stationary shoulder. The inner diameter of the moving shoulder is 10mm~20mm, and the outer diameter of the stationary shoulder is 15mm~30mm. The outer wall of the stirring needle has a threaded structure, and the cross-section of the stirring needle is cylindrical or polygonal.

5. The friction stir welding method according to claim 4, characterized in that: The width of the core connection area is 1-2 mm larger than the diameter of the top of the stirring needle, the total width of the middle connection area is 2-5 mm larger than the outer diameter of the moving shaft shoulder, and the total width of the outer connection area is 5-10 mm larger than the outer diameter of the stationary shaft shoulder.

6. The friction stir welding method according to claim 5, characterized in that: Methods for achieving surface microtexture on the surface of the metal sheet to be welded include laser texturing, sandblasting, or chemical etching; chemical films that achieve chemical bonding between the metal and resin are achieved using silane coupling agents, aluminate coupling agents, or phthalate coupling agents.

7. The friction stir welding method according to claim 6, characterized in that: The welding tool rotation speed is controlled at 500 rpm to 2000 rpm; the welding speed is controlled at 500 mm / min to 2000 mm / min; the downward pressure of the lower end of the stationary shoulder on the surface of the metal plate to be welded is 0.4 mm to 0.6 mm; the cooling and solidification temperature gradient is 10℃ / min; and the air humidity is controlled at 20% to 30%.

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