An ultrasonic welding method, assembly

Abstract

The present invention provides an ultrasonic welding method and an assembly, relating to the technical field of materials, and aiming to solve the technical problems of complex connection methods and low connection strength between metals themselves or between metals and composite materials. The ultrasonic welding method includes: spraying a spraying material onto the surface of a metal workpiece to form a spraying material layer, the spraying material including thermoplastic resin particles and abrasive materials, the spraying material layer being a thermoplastic resin layer, and the thickness of the thermoplastic resin layer being 8 μm to 200 μm; overlapping and fixing the surface of the metal workpiece having the thermoplastic resin layer with the surface to be connected of a first workpiece, and performing welding by using ultrasonic waves. The ultrasonic welding method of the present invention is used for connecting the metal workpiece and the first workpiece, and the material of the first workpiece is at least one of metal, thermoplastic resin composite material, and thermosetting resin composite material. The ultrasonic welding method of the present invention can perform welding without using energy guiding ribs, not only has high connection strength, but also has a simpler process and lower cost.

Description

Technical Field

[0001] The present disclosure relates to the field of materials, and particularly to an ultrasonic welding method and an assembly. Background Art

[0002] The combination of lightweight metals such as aluminum alloy, magnesium aluminum alloy and titanium alloy with fiber-reinforced thermoplastic resin composite materials and fiber-reinforced thermosetting resin composite materials is used for the lightweight of products in the fields of aerospace, rail transit and new energy vehicles.

[0003] For the connection between metals and between metals and heterogeneous materials, it is generally mechanical connection or adhesive bonding. Among them, mechanical connection requires drilling of workpieces, which will cause local stress concentration and damage the continuity of the fiber-reinforced phase in the fiber-reinforced composite material. And the adhesive bonding process requires efficient surface treatment of the surfaces of the workpieces to be connected, and the curing period of the adhesive joint is long and the energy consumption is high, so the cost is relatively high.

[0004] Ultrasonic welding technology is a fast, efficient and reliable connection process, which is widely used in the connection of thermoplastic plastics and their composite materials. In the prior art, ultrasonic waves between metal materials and composite materials are generally used for assistance, either the process is complex or the connection strength is low. Summary of the Invention

[0005] The purpose of the present invention is to provide an ultrasonic welding method and an assembly to solve the technical problems of complex connection methods and low connection strength between metals themselves or between metals and composite materials.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] An embodiment of the present invention provides an ultrasonic welding method for connecting a metal workpiece and a first workpiece, wherein the material of the first workpiece is at least one of metal, thermoplastic resin composite material and thermosetting resin composite material, and the welding method includes the following steps:

[0008] Spray material is sprayed on the surface of the metal workpiece to form a spray material layer. The spray material includes thermoplastic resin particles and abrasive materials, the spray material layer is a thermoplastic resin layer, and the thickness of the thermoplastic resin layer is 8μm - 200μm;

[0009] The surface of the metal workpiece with the thermoplastic resin layer overlaps and is fixed with the surface to be connected of the first workpiece, and ultrasonic welding is performed.

[0010] According to at least one embodiment of the present disclosure, the volume ratio between the thermoplastic resin particles and the abrasive materials is (10 - 50):(50 - 90).

[0011] According to at least one embodiment of the present disclosure, the particle size of the thermoplastic resin particles is 10 μm to 100 μm;

[0012] The particle size of the sand material is 20 μm to 200 μm.

[0013] According to at least one embodiment of the present disclosure, the material of the thermoplastic resin particles includes one or more of polyether ether ketone, polyether ketone, polyphenylene sulfide, low molecular weight polyarylether ketone, polyether ketone ketone, polyetherimide, and polycarbonate.

[0014] According to at least one embodiment of the present disclosure, the sand material includes one or more of alumina, emery, titanium alloy particles, silicon carbide, stainless steel beads, copper beads, aluminum beads, glass beads, ceramic beads, steel beads, and steel grit.

[0015] According to at least one embodiment of the present disclosure, the welding method further includes applying a first thermoplastic resin film on the surface of the thermoplastic resin layer on the surface of the metal workpiece, and the thickness of the first thermoplastic resin film is greater than the thickness of the thermoplastic resin layer; and / or,

[0016] When the material of the first workpiece is metal or a thermosetting resin composite material, a second thermoplastic resin film is applied on the surface of the area to be joined of the first workpiece.

[0017] According to at least one embodiment of the present disclosure, the thickness of the first thermoplastic resin film is 10 μm to 500 μm; and / or,

[0018] The sum of the thicknesses of the thermoplastic resin layer, the first thermoplastic resin film, and the second thermoplastic resin film satisfies 50 μm to 1000 μm.

[0019] According to at least one embodiment of the present disclosure, the materials of the first thermoplastic resin film, the second thermoplastic resin film, and the thermoplastic resin particles are the same or different; and / or,

[0020] When the first workpiece is a thermoplastic resin composite material, the materials of the first thermoplastic resin film, the thermoplastic resin particles, and the resin in the thermoplastic resin composite material are the same or different.

[0021] According to at least one embodiment of the present disclosure, the steps of applying the first thermoplastic resin film on the surface of the thermoplastic resin layer on the surface of the metal workpiece and applying the second thermoplastic resin film on the surface of the area to be joined of the first workpiece adopt one of vacuum hot pressing, injection molding, or compression molding processes.

[0022] Compared with the prior art, in the ultrasonic welding method of the present invention, a spraying material is obtained by compounding thermoplastic resin particles and abrasive materials, and the spraying material is sprayed onto the surface of a metal workpiece to form a thermoplastic resin layer. In this process, the abrasive materials for sandblasting improve the cleanliness and roughness of the metal workpiece surface, strengthen the interfacial bonding strength between the thermoplastic resin particles and the metal workpiece, and the thermoplastic resin particles deform and adhere to the surface of the metal workpiece during the high-speed impact and friction process. The synergistic effect of the two realizes the high-strength interfacial bonding between the thermoplastic resin layer and the metal workpiece surface. Further, the surface of the metal workpiece with the thermoplastic resin layer overlaps and is fixed with the surface to be connected of the first workpiece, and ultrasonic welding is performed. Since the thickness of the thermoplastic resin layer formed on the surface of the metal workpiece is controllable, within the range of 8 μm to 200 μm, high-frequency ultrasonic vibration is applied to the overlapping area through ultrasonic waves to melt the thermoplastic resin at the interface, and a welded connection is formed after cooling. Not only the appearance quality and connection strength of the joint are very high, but also it is applicable to the ultrasonic welding process without energy guiding ribs, which can greatly improve the rapid and high-strength connection of medium and large-sized welding surfaces.

[0023] Another object of the present invention is to further provide an assembly, which at least includes a metal workpiece and a first workpiece. The material of the first workpiece is at least one of metal, thermoplastic resin composite material, and thermosetting resin composite material, and the metal workpiece and the first workpiece are connected together by the above welding method.

[0024] Compared with the prior art, the assembly of the present invention has the following advantages:

[0025] The assembly and the above ultrasonic welding method have the same advantages as those compared with the prior art, and will not be elaborated here. Description of the Drawings

[0026] The drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, are used to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure, and the drawings are included in this specification and form a part of this specification.

[0027] Figure 1 It is a spraying schematic diagram according to an embodiment of the present disclosure.

[0028] Figure 2 It is a schematic cross-sectional structure diagram of the metal workpiece after spraying treatment according to an embodiment of the present disclosure.

[0029] Figure 3 It is a schematic cross-sectional structure diagram of the metal workpiece with the first thermoplastic resin film attached according to an embodiment of the present disclosure.

[0030] Figure 4Schematic diagram of ultrasonic spot welding between two metal workpieces with a first thermoplastic resin film attached to their surfaces according to an embodiment of the present disclosure.

[0031] Figure 5 Schematic diagram of ultrasonic continuous welding between a metal workpiece and a thermoplastic resin composite according to an embodiment of the present disclosure.

[0032] Figure 6 Schematic diagram of ultrasonic continuous welding between a curved metal workpiece and a thermosetting resin composite according to an embodiment of the present disclosure.

[0033] Reference numerals: 1, metal workpiece; 2, spraying material; 3, spraying equipment; 4, thermoplastic resin layer; 5, welding head; 6, first thermoplastic resin film; 7, first workpiece; 8, second thermoplastic resin film. Detailed implementation manners

[0034] The present disclosure will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific implementation manners described herein are only used to explain the relevant content and do not limit the present disclosure. Additionally, it should be noted that for the sake of description, only parts related to the present disclosure are shown in the drawings.

[0035] It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings and embodiments. For those conditions not specified in the examples, they shall be carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0036] In the ultrasonic welding of metal and composite materials or metals in the prior art, energy guiding ribs, laser beams, etc. are required, resulting in low efficiency, and high-temperature heating of metal parts is required, increasing the operation complexity and cost. Some require processing grooves or microporous structures on the metal surface. For example, grooves are processed on the metal surface using mechanical processing methods. The treatment of this micro-structure makes the process complex and the welding efficiency relatively low. The microporous structure requires electrochemically machining hole-shaped micro-structures on the metal material surface to enable the high-temperature molten resin and short carbon fibers to flow into and fill the holes on the metal surface during the ultrasonic welding process, thereby promoting the mechanical locking and chemical bonding between the metal and the short-cut fibers at the interface and improving the strength of the welded joint. However, insufficient filling of the hole-shaped micro-structure by the fibers and the molten resin will have a negative impact on the connection strength and reliability. Therefore, both of the above have the problems of complex process and high cost, and the technical problems that the connection strength and reliability cannot be guaranteed.

[0037] To solve the problems existing in the above prior art, please refer to Figures 1-4As shown, an ultrasonic welding method provided by an embodiment of the present invention not only has a simple process method, but also has high connection strength and high reliability. The ultrasonic welding method of the embodiment of the present invention is used for the connection between a metal workpiece 1 and a first workpiece 7. The material of the first workpiece 7 is at least one of metal, thermoplastic resin composite material, and thermosetting resin composite material. The welding method includes the following steps: The spraying material 2 is sprayed on the surface of the metal workpiece 1 to form a spraying material 2 layer. The spraying material 2 includes thermoplastic resin particles and abrasive materials. The spraying material 2 layer is a thermoplastic resin layer 4, and the thickness of the thermoplastic resin layer 4 is 8 μm to 200 μm. The surface of the metal workpiece 1 with the thermoplastic resin layer 4 overlaps and is fixed to the surface to be connected of the first workpiece 7, and ultrasonic welding is performed.

[0038] In actual use, please refer to Figures 1-2 As shown, a spraying material 2 formed by compounding thermoplastic resin particles and sandblasting abrasive materials is sprayed at a high speed onto the surface to be connected of the metal workpiece 1 by using a sandblasting device or a cold spraying device 3. After the spraying is completed, the thermoplastic resin particles are firmly embedded in the surface of the metal workpiece 1 and deformed, and a thermoplastic resin layer 4 is formed on the surface of the metal workpiece. The thickness of the thermoplastic resin layer 4 is between 8 μm and 200 μm. The metal workpiece 1 with the thermoplastic resin layer 4 attached and the first workpiece 7 to be connected to it are overlapped and fixed, placed on the support anvil of the ultrasonic welding device, and ultrasonic oscillation is performed on it by using an ultrasonic welding device. After the thermoplastic resin attached to the surface of the metal workpiece 1 is melted and cooled, a rapid and high-strength connection between the metal workpiece 1 and the first workpiece 7 is achieved.

[0039] Please refer to Figure 2 As shown, the thickness of the above-mentioned thermoplastic resin layer 4 can be controlled between 8 μm and 200 μm by the spraying time, the particle size of the sprayed particles, etc. If the thickness of the thermoplastic resin layer 4 is too low, the adhesion between it and the metal workpiece 1 will be greatly reduced, affecting the strength of the final welded joint; if the thickness of the thermoplastic resin layer 4 is too high, the mechanical properties of the thermoplastic resin layer 4 itself will be greatly reduced, and ultimately the connection strength of the welded joint will not be high.

[0040] In some embodiments, please refer to Figure 3As shown, for metal workpieces with high requirements for welding strength, the above ultrasonic welding method further includes applying a first thermoplastic resin film 6 on the surface of the thermoplastic resin layer 4 on the surface of the metal workpiece 1. The thickness of the first thermoplastic resin film 6 is greater than that of the thermoplastic resin layer 4, which can ensure that there is enough resin on one side of the metal workpiece 1 for melting connection to obtain sufficient welding strength. The resin of the first thermoplastic resin film 6 should be the same as that of the thermoplastic resin layer 4, or the material of the first thermoplastic resin film 6 should be selected as a material with good bonding performance with the resin of the thermoplastic resin layer 4. Since the thermoplastic resin layer 4 is strongly bonded to the metal workpiece 1 by spraying, and by setting the first thermoplastic resin film 6, the thickness and uniformity of the thermoplastic resin film can be controlled. The thermoplastic resin layer 4 and the first thermoplastic resin film 6 cooperate with each other, so that a thermoplastic resin with high interfacial bonding strength is applied on the surface of the metal workpiece 1, and the appearance quality and connection strength of the two are very high through ultrasonic welding. Exemplarily, attaching the first thermoplastic resin film 6 to the surface of the thermoplastic resin layer 4 can adopt one of processes such as vacuum hot pressing, injection molding or compression molding.

[0041] Considering the bonding strength between the thermoplastic resin layer 4 and the metal workpiece 1, in some embodiments, the volume ratio of the above thermoplastic resin particles to the abrasive is (10 - 50):(50 - 90). If the proportion of the thermoplastic resin particles in the spraying material is less than 10%, the spraying time will be greatly increased, and the thickness of the thermoplastic resin layer 4 formed on the surface of the metal workpiece 1 will be less than 8 μm. If the proportion of the thermoplastic resin particles in the spraying material is more than 50%, the impact and erosion ability of the overall spraying material on the surface of the metal workpiece 1 will become poor, and an effective thermoplastic resin layer 4 cannot be formed on the surface of the metal workpiece 1.

[0042] In some embodiments, the particle size of the thermoplastic resin particles is 10 μm - 100 μm, optionally 30 μm - 70 μm; the particle size of the abrasive is 20 μm - 200 μm, optionally 30 μm - 150 μm, and also optionally 50 μm - 100 μm. The abrasive particle size in this range can relatively efficiently form the thermoplastic resin layer 4 on the metal surface, and the thickness distribution of the thermoplastic resin layer 4 is more uniform. Exemplarily, the shape of the abrasive can be irregular particles or spheres, and the abrasive materials include but are not limited to one of alumina, emery, titanium alloy particles, silicon carbide, stainless steel beads, copper beads, aluminum beads, glass beads, ceramic beads, steel beads, steel gravel. The selection of the abrasive should be as similar as possible to the performance of the metal workpiece 1. For the common aluminum alloy and titanium alloy in aerospace applications, aluminum alloy preferably selects aluminum oxide particles, aluminum beads, steel beads, copper beads, etc., and titanium alloy preferably selects titanium alloy particles, aluminum oxide and steel beads, etc. And the shape of the thermoplastic resin particles can be spherical or irregular particle shape.

[0043] In some embodiments, the material of the thermoplastic resin particles can be any thermoplastic resin, including but not limited to high-performance resins such as polyetheretherketone (abbreviated as PEEK), polyetherketone (abbreviated as PEK), polyphenylene sulfide (abbreviated as PPS), low molecular weight polyaryletherketone (abbreviated as LM-PAEK), polyetherketoneketone (abbreviated as PEKK), and polyetherimide (abbreviated as PEI), or other thermoplastic resins such as polycarbonate (abbreviated as PC).

[0044] To obtain good weld accuracy and strength, the thickness of the first thermoplastic resin film 6 is between 10 μm and 500 μm, optionally between 50 μm and 400 μm, and further optionally between 100 μm and 300 μm. When the thickness is too low, there will be insufficient resin on one side of the metal workpiece 1 during the welding process for fusion connection, resulting in low strength. When the thickness is higher than 500 μm, a large amount of thermoplastic resin will overflow during the ultrasonic welding process, leading to a decrease in the dimensional accuracy of the welded joint and the stability of the weld quality.

[0045] In some embodiments, the first workpiece 7 can be a fiber-reinforced thermoplastic resin composite material, a fiber-reinforced thermosetting resin composite material, or a metal material.

[0046] For example, please refer to Figure 5 As shown, when the first workpiece 7 is a fiber thermoplastic resin composite material, its welding surface can be attached with a thermoplastic resin film similar to that of the metal workpiece 1. According to the actual situation, it can also not be processed. In this case, the resin particles used for spraying on the surface of the metal workpiece 1 are made of the same material as the first workpiece 7, and the first thermoplastic resin film 6 is also made of the same material as the first workpiece 7. According to actual needs, the materials of the resin in the first thermoplastic resin film 6, the thermoplastic resin particles, and the thermoplastic resin composite material can also be different. It can be understood that the resin materials of the three are preferably selected as resins with similar properties or strong bonding force.

[0047] When the first workpiece 7 is a metal material, please refer to Figure 4 As shown, its welding surface can be treated in the same way as the metal workpiece 1, that is, a thermoplastic resin layer 4 is first formed on the welding surface by spraying, and then a first thermoplastic resin film 8 is attached to the surface of the thermoplastic resin layer 4. It can be understood that according to actual needs, the welding surface of the first workpiece 7 can also be selected not to be processed, or only a thermoplastic resin layer 4 can be formed by spraying, or only a first thermoplastic resin film 6 can be attached to the surface of the first workpiece 7. It can be understood that the materials of the second thermoplastic resin film 8, the first thermoplastic resin film 6, and the thermoplastic resin particles can be the same or different. It can be understood that the resin materials of the three are preferably selected as resins with similar properties or strong bonding force.

[0048] When the first workpiece 7 is a fiber-reinforced thermosetting resin composite material, please refer to Figure 6 As shown, its welding surface to be welded can be untreated, or a second thermoplastic resin film 8 can be attached to its welding surface to be welded. Exemplarily, the first workpiece 7 is a thermosetting composite workpiece with a thermoplastic resin film co-cured on its surface. It can be understood that the materials of the first thermoplastic resin film 6, the thermoplastic resin particles, and the second thermoplastic resin film 8 on the metal workpiece 1 can be the same or different. It can be understood that the resin materials of the three are preferably selected as resins with similar properties or strong bonding force.

[0049] It can be understood that regardless of the material of the first workpiece, the ultrasonic welding method of the embodiments of the present invention is applicable to both flat welding surfaces to be welded and curved welding surfaces to be welded. When the welding surface to be welded is a curved surface, the welding head 5 of the ultrasonic welding device can be a welding head with an arc-shaped structure, so that the thermoplastic resin in the welding surface to be welded is uniformly melted. The ultrasonic welding device of the embodiments of the present invention can be traditional ultrasonic spot welding, such as Figure 4 As shown, or ultrasonic continuous welding, such as Figures 5-6 As shown, even if an energy guiding rib is not applied between the two workpieces to be welded, the quality and strength of the welding head can still be guaranteed.

[0050] When a second thermoplastic resin film 8 needs to be applied to the surface of the first workpiece 7, the total thickness of it, the first thermoplastic resin film 6 on the metal workpiece 1, and the thermoplastic resin layer 4 should satisfy 50 μm to 1000 μm, so as to provide sufficient molten resin material to ensure the welding strength. At the same time, it will not cause a decrease in the welding dimensional accuracy and a decline in the welding quality stability due to excessive resin material at the weld.

[0051] The embodiments of the present invention also provide a combination body, at least including a metal workpiece 1 and a first workpiece 7. The material of the first workpiece 7 is at least one of metal, thermoplastic resin composite material, and thermosetting resin composite material. The metal workpiece 1 and the first workpiece 7 are connected together by the above ultrasonic welding method.

[0052] It can be understood that in order to ensure the welding strength, before the metal workpiece is subjected to spraying treatment, the welding area to be welded should be cleaned. Exemplarily, the surface of the metal workpiece is wiped or ultrasonically cleaned with an organic solvent such as ethanol, acetone, or ethylene glycol to remove oil stains and other pollutants on the metal surface.

[0053] It can be understood that in order to obtain thermoplastic resin layers 4 with different thicknesses in the sandblasting step, it can be achieved by controlling the spraying time or spraying speed.

[0054] The following gives several examples of ultrasonic welding methods, and selects representative welded combinations for performance analysis.

[0055] Test method: According to the ASTM-D1002 test standard, the size of the lap joint area is 25.4 mm × 12.7 mm, and the shear strength of the single-lap joint is tested.

[0056] Example 1

[0057] The ultrasonic welding method provided in this example specifically includes:

[0058] The two metal workpieces are made of 3-mm-thick aluminum alloy 2024-T3 material, and the spraying material is a mixture of PPS particles and Al 2 O 3 particles, where the content of PPS particles is 30%, the particle size is 25 μm, and the Al 2 O 3 particle size is distributed between 30 μm and 60 μm;

[0059] (1) Wipe the surface of one metal workpiece with acetone for degreasing and cleaning;

[0060] (2) Spray the spraying material onto the surface of the aluminum alloy workpiece by sandblasting. The sandblasting pressure is 0.4 MPa, the distance between the nozzle and the surface of the aluminum alloy workpiece is 40 mm, and a PPS layer with an average thickness of 48 μm is formed on the metal surface;

[0061] (3) After sandblasting, apply a 150-μm-thick PPS film to the surface of the aluminum alloy workpiece by molding;

[0062] (4) Repeat steps (1)-(3) to process the surface of the other metal workpiece;

[0063] (5) Perform ultrasonic spot welding on the two aluminum alloy workpieces for ultrasonic welding without energy guiding ribs. Set the ultrasonic welding frequency to 20 Hz, the welding pressure to 0.6 kN, and the holding pressure to 0.6 kN to obtain an aluminum alloy single-lap joint structure.

[0064] Example 2

[0065] The difference between the ultrasonic welding method provided in this example and Example 1 is:

[0066] In step (2), a PPS layer with an average thickness of 8 μm is formed on the metal surface by sandblasting.

[0067] Example 3

[0068] The difference between the ultrasonic welding method provided in this example and Example 1 is:

[0069] In step (2), a PPS layer with an average thickness of 197 μm is formed on the metal surface by sandblasting.

[0070] Example 4

[0071] The metal workpiece is made of high-strength DB590 steel material with a thickness of 1.6 mm, and the spraying material is a mixture of PC particles and Al 2 O 3 particles. The content of PC particles is 25%, the particle size is 40 μm, and the Al 2 O 3 particle size distribution is between 30 μm and 60 μm; the workpiece to be joined is a thermosetting resin composite material, made of unidirectional tapes of carbon fiber reinforced epoxy prepreg, with a thickness of 2.1 mm.

[0072] (1) Wipe the surface of the metal workpiece with acetone for degreasing and cleaning;

[0073] (2) Spray the spraying material onto the surface of the DB590 steel workpiece by sandblasting process. The sandblasting pressure is 0.4 MPa, the distance between the nozzle and the surface of the steel workpiece is 50 mm, and a PC layer with an average thickness of 63 μm is formed on the metal surface;

[0074] (3) After sandblasting treatment, apply a PC film with a thickness of 200 μm to the surface of the DB590 steel workpiece by vacuum hot pressing process;

[0075] (4) A PC film with a thickness of 175 μm is attached to the surface of the thermosetting resin composite workpiece. After surface treatment, the PC film is attached to the surface of the thermosetting composite curved workpiece by co-curing molding;

[0076] (5) Perform ultrasonic spot welding on two aluminum alloy workpieces to obtain an ultrasonic welding without energy guiding ribs. Set the ultrasonic welding frequency to 20 Hz, the welding pressure to 0.5 kN, and the holding pressure to 0.5 kN to obtain a DB590 steel-thermosetting composite single-lap joint structure.

[0077] Example 5

[0078] The metal workpiece is made of aluminum alloy 2024-T3 material with a thickness of 3 mm, and the spraying material is a mixture of PPS particles and Al 2 O 3 particles. The content of PPS particles is 35%, the PPS particle size is 50 μm, and the Al 2 O 3 particle size distribution is between 50 μm and 70 μm; the workpiece to be joined is a carbon fiber reinforced thermoplastic composite material, carbon fiber reinforced PPS, with a thickness of 2 mm.

[0079] (1) Wipe the surface of the metal workpiece with acetone for degreasing and cleaning;

[0080] (2) The abrasive is sprayed onto the surface of the aluminum alloy workpiece using a sandblasting process. The sandblasting pressure is 0.5 MPa, the distance between the nozzle and the surface of the steel workpiece is 40 mm, and a PPS layer with an average thickness of 32 μm is formed on the metal surface;

[0081] (3) After the sandblasting treatment, a PPS film with a thickness of 200 μm is applied to the surface of the aluminum alloy workpiece using a molding process;

[0082] (4) Ultrasonic spot welding is used to perform ultrasonic welding without energy guiding ribs on two workpieces. The ultrasonic welding frequency is set to 20 Hz, the welding pressure is 0.6 kN, and the holding pressure is 0.6 kN, obtaining an aluminum alloy - PPS composite single - lap joint structure.

[0083] Example 6

[0084] The metal workpiece is made of 2.5 - mm - thick titanium alloy Ti - 6Al - 4V material. The abrasive is a mixture of PEEK particles and titanium alloy particles, where the content of PEEK particles is 30%, the particle size of PEEK particles is 25 μm, and the particle size distribution of titanium alloy powder is between 40 μm and 55 μm; the workpiece to be joined is a carbon fiber - reinforced PEEK composite material with a thickness of 2 mm.

[0085] (1) The surface of the metal workpiece is wiped with acetone for degreasing and cleaning;

[0086] (2) The abrasive is sprayed onto the surface of the titanium alloy workpiece using a cold - spraying process. The accelerating gas is N2 at 0.8 MPa, the throat diameter of the spray gun is 2 mm, the outlet diameter is 8 mm, the distance between the nozzle and the surface of the titanium alloy workpiece is 60 mm, and a PEEK layer with an average thickness of 36 μm is formed on the metal surface;

[0087] (3) After the sandblasting treatment, a PEEK film with a thickness of 200 μm is applied to the surface of the titanium alloy workpiece using a molding process;

[0088] (4) Ultrasonic continuous welding is used to perform ultrasonic welding without energy guiding ribs on two workpieces. The ultrasonic welding frequency is set to 20 Hz, the welding pressure is 0.8 kN, and the holding pressure is 0.8 kN. During the welding process, the welding head of the welding equipment moves at a speed of 30 mm / s, completing continuous ultrasonic welding with a weld length of 300 mm and a width of 12.7 mm, obtaining a titanium alloy - PEEK composite connection structure. The obtained welded structure is cut into a single - lap joint structure with a lap - joint area size of 25.4 mm × 12.7 mm using a precision grinding wheel cutting machine.

[0089] Example 7

[0090] The metal workpiece is made of 3 - mm - thick aluminum alloy 2024 - T3 material. The metal workpiece is a curved workpiece. The abrasive is PEEK particles and Al 2 O3 Obtained by mixing particles, with the PEEK particle content being 20%, the particle size being 50 μm, and Al 2 O 3 The particle size distribution is between 50 μm and 70 μm; the workpiece to be joined is a thermosetting composite made of carbon fiber reinforced epoxy prepreg unidirectional tape, and the workpiece to be joined is a curved workpiece with a thickness of 2 mm.

[0091] (1) Wipe the surface of the metal workpiece with acetone for degreasing and cleaning;

[0092] (2) Adopt a sandblasting process to spray the abrasive onto the surface of the aluminum alloy workpiece. The sandblasting pressure is 0.5 MPa, and the distance between the nozzle and the surface of the aluminum alloy workpiece is 30 mm, forming a PEEK layer with an average thickness of 25 μm on the metal surface;

[0093] (3) After sandblasting treatment, apply a 100-μm-thick PEEK film to the surface of the aluminum alloy workpiece by vacuum hot pressing;

[0094] (4) Attach a 200-μm-thick PEEK film to the surface of the thermosetting composite curved workpiece to be joined by co-curing molding;

[0095] (5) Perform ultrasonic welding without energy guiding ribs on the two workpieces by continuous ultrasonic welding. Set the ultrasonic welding frequency to 20 Hz, the welding pressure to 0.5 kN, and the holding pressure to 0.5 kN. During the welding process, the welding head of the welding equipment moves at a speed of 30 mm / s, completing continuous ultrasonic welding with a weld length of 320 mm and a width of 12.7 mm, obtaining a titanium alloy-thermosetting composite connection structure. Use a precision grinding wheel cutting machine to cut the obtained welded structure into a single-lap joint structure with a lap area size of 25.4 mm × 12.7 mm.

[0096] Comparative Example 1

[0097] The ultrasonic welding method provided in this example is different from that in Example 1 only in that:

[0098] The treatment of the two metal workpieces does not include step (2).

[0099] Comparative Example 2

[0100] The ultrasonic welding method provided in this example is different from that in Example 1 in that:

[0101] In step (2), a PPS layer with an average thickness of 5 μm is formed on the metal surface by the sandblasting process.

[0102] Comparative Example 3

[0103] The ultrasonic welding method provided in this example is different from that in Example 1 in that:

[0104] In step (2), a PPS layer with an average thickness of 306 μm is formed on the metal surface by a sandblasting process.

[0105] Comparative Example 4

[0106] The ultrasonic welding method provided in this embodiment is different from that in Embodiment 1 in that:

[0107] The spraying material is 100% Al 2 O 3 , and no PPS particles are added.

[0108] The shear strength of the welded joints of the embodiments and comparative examples is given below. Please refer to Table 1.

[0109] Table 1 Shear strength of welded joints

[0110]

[0111] As shown in Table 1, when a thermoplastic resin layer is applied to the surface of the area to be welded of the metal workpiece without using the sandblasting process in Comparative Example 1, its shear strength decreases by 57% compared to the strength of the welded joint using the spraying process. In Comparative Examples 2 and 3, when the thickness of the thermoplastic resin layer formed by the spraying process is less than 8 μm, the shear strength drops sharply, and when it is higher than 200 μm, it will also have a certain negative impact on the shear strength. In Comparative Example 4, when using the spraying process for spraying, only sand materials are used as the spraying material instead of thermoplastic resin particles, and its shear strength is 24.8 MPa. Compared with Embodiment 1, the shear strength decreases by 37%. Therefore, thermoplastic resin particles in the spraying material need to be compounded and synergistically combined with traditional sandblasting materials to play their role in enhancing the connection strength.

[0112] In the description of this specification, the description referring to terms such as "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / ways or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments / ways or examples described in this specification and the features of different embodiments / ways or examples.

[0113] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0114] Those skilled in the art should understand that the above embodiments are merely for clearly illustrating the present disclosure and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications can be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. An ultrasonic welding method, characterized in that, it is used for the connection between a metal workpiece and a first workpiece, the material of the first workpiece is at least one of metal, thermoplastic resin composite material and thermosetting resin composite material, and the welding method includes the following steps: Spray material is sprayed on the surface of the metal workpiece to form a spray material layer, the spray material includes thermoplastic resin particles and abrasive materials, the spray material layer is a thermoplastic resin layer, and the thickness of the thermoplastic resin layer is 32 µm to 200 µm; The surface of the metal workpiece with the thermoplastic resin layer overlaps and is fixed with the surface to be connected of the first workpiece, and ultrasonic welding is carried out; the volume ratio between the thermoplastic resin particles and the abrasive materials is (10 - 50):(50 - 90); The particle size of the thermoplastic resin particles is 10 µm to 100 µm; The particle size of the abrasive materials is 20 µm to 200 µm; The material of the thermoplastic resin particles includes one or more of polyether ether ketone, polyether ketone, polyphenylene sulfide, low molecular weight polyarylether ketone, polyether ketone ketone, polyetherimide, polycarbonate; The abrasive materials include one or more of alumina, diamond sand, titanium alloy particles, copper beads, aluminum beads, glass beads, ceramic beads, steel beads.

2. The welding method according to claim 1, characterized in that, the welding method further includes applying a first thermoplastic resin film on the surface of the thermoplastic resin layer on the surface of the metal workpiece, and the thickness of the first thermoplastic resin film is greater than the thickness of the thermoplastic resin layer.

3. The welding method according to claim 1, characterized in that, when the material of the first workpiece is metal or thermosetting resin composite material, a second thermoplastic resin film is applied on the surface of the area to be connected of the first workpiece.

4. The welding method according to claim 3, characterized in that, the thickness of the first thermoplastic resin film is 10 µm to 500 µm; and / or, the sum of the thicknesses of the thermoplastic resin layer, the first thermoplastic resin film and the second thermoplastic resin film satisfies 50 µm to 1000 µm.

5. The welding method according to claim 3, characterized in that, the materials of the first thermoplastic resin film, the second thermoplastic resin film and the thermoplastic resin particles are the same or different; and / or, when the first workpiece is a thermoplastic resin composite material, the materials of the first thermoplastic resin film, the thermoplastic resin particles and the resin in the thermoplastic resin composite material are the same or different.

6. An assembly, characterized in that, it at least includes a metal workpiece and a first workpiece, the material of the first workpiece is at least one of metal, thermoplastic resin composite material and thermosetting resin composite material, and the metal workpiece and the first workpiece are connected together by the welding method according to any one of claims 1 - 5.

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