Hybrid welding method

Abstract

The invention provides a hybrid welding method. The hybrid welding method comprises the following steps that the surfaces of a first to-be-welded part and a second to-be-welded part are cleaned; the welding interface of the first to-be-welded part and the second to-be-welded part is coated with a brazing material, and the first to-be-welded part and the second to-be-welded part are clamped to form a to-be-welded assembly; the to-be-welded assembly is fed into a vacuum brazing furnace to be brazed, a brazing material is cooled and solidified to form a brazing layer after being heated and melted, the brazing layer is connected with the first to-be-welded part and the second to-be-welded part, and a brazed welding part is obtained; and the brazing welding part is taken out of the vacuum brazing furnace, laser is focused on a brazing layer of the brazing welding part, the laser conducts scanning welding according to a preset track, and a welding part is obtained. The method can reduce the requirement of the component on the surface machining precision of the to-be-welded part and the requirement on the assembly process precision, can simplify the process, reduces the production cost, and improves the production efficiency.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and more particularly to a composite welding method. Background Art

[0002] The connection between transparent materials and metal materials or transparent materials is used to make optical windows, fairings, sensors, etc., and has been widely used in aircraft, satellites, missiles and other fields. Transparent materials themselves are highly brittle, have poor toughness, and have poor machinability. When used, they are often restricted by their size and shape. In addition, due to the large differences in the melting point, thermal expansion coefficient and other properties between transparent materials and metal materials, the connection between transparent materials and metal materials or transparent materials is very difficult. Therefore, how to improve the safety and reliability of the connection between transparent materials and metal materials or transparent materials is a problem that needs to be solved urgently.

[0003] The currently used bonding technology is a method of connecting transparent materials with metal materials or transparent materials through adhesives, but its bonding is prone to bleaching, aging, and release of harmful gases, and it is difficult to meet the harsh service environment requirements such as high temperature, high pressure, and high load.

[0004] At present, laser welding is generally used to connect transparent materials with metal materials or transparent materials. In order to achieve high-strength welding between transparent materials and metal materials or transparent materials, it requires that the surface of the sample to be welded has extremely low surface roughness and extremely high flatness, so that the sample to be welded can reach an optical contact state. Therefore, it has very high requirements for the surface processing accuracy of the components and the assembly process accuracy. For some large-sized components with complex connection interfaces (such as curved surfaces), it is necessary to use equipment with very high processing accuracy to process the components, and the purchase price of these equipment is very high, which greatly increases the production cost. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is that the existing connection method between transparent material and metal material or transparent material has very high requirements on the surface processing accuracy of components and the assembly process accuracy.

[0007] (II) Technical solution

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] The present invention provides a composite welding method for welding a first workpiece to be welded and a second workpiece to be welded, wherein the first workpiece to be welded is a transparent material, and the second workpiece to be welded is a transparent material or a metal material. The composite welding method comprises the following steps:

[0010] S1, cleaning the surfaces of the first workpiece to be welded and the second workpiece to be welded;

[0011] S2, coating a brazing material on a welding interface between the first workpiece to be welded and the second workpiece to be welded, and clamping the first workpiece to be welded and the second workpiece to be welded to form a welded assembly;

[0012] S3, sending the assembly to be welded into a vacuum brazing furnace for brazing, wherein the brazing material is melted by heat and then cooled and solidified to form a brazing layer, wherein the brazing layer connects the first component to be welded and the second component to be welded to obtain a brazed welded component;

[0013] S4, taking the brazing component out of the vacuum brazing furnace, focusing the laser on the brazing layer of the brazing component, and performing scanning welding with the laser according to a preset trajectory to obtain a welded part.

[0014] Preferably, step S1 specifically includes the following steps:

[0015] Performing surface treatment on the first workpiece to be welded and the second workpiece to be welded to clean impurities on the surfaces thereof;

[0016] After the surface treatment is completed, the first workpiece to be welded and the second workpiece to be welded are ultrasonically cleaned in alcohol and blown dry.

[0017] Preferably, step S3 specifically includes the following steps:

[0018] Placing the assembly to be welded into a vacuum brazing furnace, raising the furnace temperature to the brazing temperature, and melting the brazing material by the heat;

[0019] Keeping the assembly to be welded at the brazing temperature for a preset time;

[0020] The furnace temperature is lowered to room temperature, and the brazing material is cooled and solidified to form a brazing layer, and the brazing layer connects the first part to be welded and the second part to be welded to obtain a brazed welded part.

[0021] Preferably, step S4 specifically includes the following steps:

[0022] The surface of the first workpiece to be welded is facing upward, the laser passes through the first workpiece to be welded and focuses on the brazing layer of the brazed workpiece;

[0023] The laser performs scanning welding according to a preset trajectory, and performs interval welding on the welding interface to form a plurality of nail-shaped welds distributed in a dot matrix on the welding interface. The nail-shaped welds connect the first workpiece to be welded, the brazing layer and the second workpiece to be welded to obtain a welded part.

[0024] Preferably, the laser includes at least one of pulse laser, millisecond laser, nanosecond laser, picosecond laser and femtosecond laser.

[0025] Preferably, the transparent material includes at least one of quartz glass, borosilicate glass, aluminosilicate glass and sapphire.

[0026] Preferably, the metal material includes at least one of copper alloy, Kovar alloy, titanium alloy, stainless steel, aluminum alloy and high-temperature alloy.

[0027] Preferably, the brazing layer comprises a first diffusion layer, a solder layer and a second diffusion layer, the brazing material is diffusion-connected with the first workpiece to be welded to form the first diffusion layer, the brazing material is diffusion-connected with the second workpiece to be welded to form the second diffusion layer, the brazing material is melted and then cooled and solidified to form the solder layer, and the solder layer is located between the first diffusion layer and the second diffusion layer.

[0028] Preferably, the preset trajectory is a circle, a straight line, an arc, or a spiral.

[0029] Preferably, the first workpiece to be welded is made of sapphire material, the second workpiece to be welded is made of titanium alloy material, and the brazing material is AgCuTi solder paste.

[0030] (III) Beneficial effects

[0031] The above technical solution of the present invention has at least the following advantages:

[0032] 1. In the present invention, the brazing material is heated to the brazing temperature. Under the clamping force of the brazing tool, the melted brazing material flows and fills the welding interface between the first part to be welded and the second part to be welded, so that the first part to be welded and the second part to be welded are in close contact. During the brazing process, diffusion connection occurs at the contact interface between the brazing material and the first part to be welded, and at the contact interface between the brazing material and the second part to be welded. After the brazing material cools and solidifies, a brazing layer is formed. The brazing layer realizes the preliminary connection between the first part to be welded and the second part to be welded, forming a brazed welded part. Then, a laser is used to focus on the brazing layer through the first part to be welded, so that the first part to be welded, the brazing material layer and the second part to be welded are quickly melted and solidified under the action of high energy density laser, forming a high-strength fusion weld, and finally realizing the connection of the parts.

[0033] 2. The present invention is particularly suitable for welding connections of complex curved surface welding interfaces. Brazing material is coated on the welding interface between the first workpiece to be welded and the second workpiece to be welded. The brazing material can fill the assembly gap between the first workpiece to be welded and the second workpiece to be welded, so that the first workpiece to be welded and the second workpiece to be welded can be tightly fitted, thereby reducing the requirements for assembly accuracy of parts and the requirements for machining accuracy of the welding interface between the first workpiece to be welded and the second workpiece to be welded, thereby simplifying the process, reducing production costs and improving production efficiency.

[0034] 3. The present invention is particularly suitable for the welding of large-size parts. The assembly to be welded is formed by coating the brazing material on the welding interface between the first workpiece to be welded and the second workpiece to be welded. The assembly to be welded is placed in a vacuum brazing furnace for brazing. The vacuum brazing furnace can form a uniform temperature field, and the brazing material at various locations on the welding interface between the first workpiece to be welded and the second workpiece to be welded is heated at the same time. The brazing material melts and flows to various locations of the welding interface at the same time, so that the molten brazing material on the welding interface flows more fully, thereby ensuring that the first workpiece to be welded and the second workpiece to be welded can achieve close contact at various locations of the welding interface, thereby improving the bonding strength of the welded joint.

[0035] 4. In the present invention, the laser performs scanning welding according to a preset trajectory, and the laser performs interval welding on the welding interface, generating ultra-high temperature, ultra-fast phase change, and strong bonding at the welding interface, performing fusion welding, and forming a plurality of nail-shaped welds distributed in a lattice at the welding interface. The nail-shaped welds are formed by the first workpiece to be welded, the second workpiece to be welded, and the brazing material being melted at the same time under the action of high-energy laser and rapidly cooled and solidified, and the welds formed have high bonding strength. Interval welding can avoid high heat accumulation at the welding interface, reduce the thermal stress generated at the welding interface, and improve the quality of welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a schematic diagram of the process of the composite welding method provided in an embodiment of the present invention.

[0038] Figure 2 It is a schematic diagram of the structure of the assembly to be welded provided in an embodiment of the present invention.

[0039] Figure 3 It is a schematic diagram of the structure of a brazing welding part provided by an embodiment of the present invention.

[0040] Figure 4 It is a schematic diagram of the laser acting on the brazing connection provided by an embodiment of the present invention.

[0041] Figure 5 It is a schematic diagram of the structure of a welding part provided by an embodiment of the present invention.

[0042] The reference numerals in the figures are:

[0043] 1. First workpiece to be welded; 2. Brazing material; 3. Second workpiece to be welded; 4. First diffusion layer; 5. Solder layer; 6. Second diffusion layer; 7. Nail-shaped weld; 8. Laser. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly located on the other element or indirectly located on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element.

[0046] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention, and do not indicate that a device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0047] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating relative importance or indicating the number of technical features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The specific implementation of the present invention is described in more detail below in conjunction with specific embodiments:

[0048] like Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 As shown, an embodiment of the present invention provides a composite welding method for welding a first workpiece 1 to be welded and a second workpiece 3 to be welded, wherein the first workpiece 1 to be welded is a transparent material, and the second workpiece 3 to be welded is a transparent material or a metal material. The composite welding method comprises the following steps:

[0049] S1, cleaning the surfaces of the first workpiece 1 and the second workpiece 3;

[0050] S2. Coat the brazing material 2 on the welding interface of the first workpiece 1 and the second workpiece 3, and clamp the first workpiece 1 and the second workpiece 3 to be welded to form a welded assembly; the specific composition of the brazing material 2 is determined according to the specific materials of the first workpiece 1 and the second workpiece 3 to be welded, and the brazing material 2 should be selected from a material with a lower melting point than the melting points of the first workpiece 1 and the second workpiece 3 to be welded and good compatibility with the materials of the first workpiece 1 and the second workpiece 3 to be welded.

[0051] S3, sending the assembly to be welded into a vacuum brazing furnace for brazing, the brazing material is melted by heat and then cooled and solidified to form a brazing layer, the brazing layer connects the first welded part 1 and the second welded part 3 to obtain a brazed welded part;

[0052] S4. Take the brazed workpiece out of the vacuum brazing furnace, focus the laser 8 on the brazing layer of the brazed workpiece, and scan and weld the laser 8 according to the preset trajectory to obtain a welded part. Specifically, the thickness of the brazing material 2 is in the micron level, that is, the thickness of the brazing material 2 is controlled to be below 30 microns. The laser 8 has a strong penetrating ability, and its energy can penetrate the first workpiece 1 to be welded, and act on the brazing material 2 and the second workpiece 3 to be welded. The laser 8 can be repeatedly scanned on the welding interface for full welding, or it can be interval welding, which is determined according to the specific process requirements.

[0053] Through the above technical solution, during the brazing process, the brazing material is heated to the brazing temperature. Under the clamping force of the brazing tooling, the melted brazing material flows and fills the welding interface between the first part to be welded and the second part to be welded, so that the first part to be welded and the second part to be welded are in close contact. During the brazing process, diffusion connection occurs at the contact interface between the brazing material and the first part to be welded, and at the contact interface between the brazing material and the second part to be welded. After the brazing material cools and solidifies, a brazing layer is formed. The brazing layer realizes the preliminary connection between the first part to be welded and the second part to be welded, forming a brazed welded part. Then, a laser is used to penetrate the first part to be welded and focus on the brazing layer, so that the first part to be welded, the brazing material layer and the second part to be welded are quickly melted and solidified under the action of high energy density laser, forming a high-strength fusion weld, and finally realizing the connection of the parts.

[0054] In one embodiment, step S1 specifically includes the following steps:

[0055] Performing surface treatment on the first workpiece to be welded 1 and the second workpiece to be welded 3 to clean impurities on the surfaces thereof;

[0056] After the surface treatment is completed, the first workpiece 1 to be welded and the second workpiece 3 to be welded are ultrasonically cleaned in alcohol and blown dry.

[0057] In one embodiment, step S3 specifically includes the following steps:

[0058] Place the components to be welded in a vacuum brazing furnace, raise the furnace temperature to the brazing temperature, and melt the brazing material;

[0059] Keep the components to be welded at the brazing temperature for a preset time;

[0060] The furnace temperature is lowered to room temperature, and the brazing material is cooled and solidified to form a brazing layer, and the brazing layer connects the first workpiece 1 and the second workpiece 3 to be welded, thereby obtaining a brazed workpiece.

[0061] In one embodiment, step S4 specifically includes the following steps:

[0062] The surface of the first workpiece to be welded 1 is facing upward, and the laser passes through the first workpiece to be welded 1 and focuses on the brazing layer of the brazed workpiece;

[0063] The laser 8 performs scanning welding according to a preset trajectory. The laser 8 performs interval welding on the welding interface, forming a plurality of nail-shaped welds 7 distributed in a dot matrix on the welding interface. The nail-shaped welds 7 connect the first workpiece 1 to be welded, the brazing layer and the second workpiece 3 to be welded to obtain a welded part.

[0064] In one embodiment, the laser 8 includes at least one of a pulse laser, a millisecond laser, a nanosecond laser, a picosecond laser, and a femtosecond laser.

[0065] In one embodiment, the transparent material includes at least one of quartz glass, borosilicate glass, aluminosilicate glass and sapphire.

[0066] In one embodiment, the metal material includes at least one of copper alloy, Kovar alloy, titanium alloy, stainless steel, aluminum alloy and high temperature alloy.

[0067] In one embodiment, the brazing layer includes a first diffusion layer 4, a solder layer 5 and a second diffusion layer 6. The brazing material is diffusely connected with the first workpiece 1 to be welded to form the first diffusion layer 4. The brazing material is diffusely connected with the second workpiece 3 to be welded to form the second diffusion layer 6. After the brazing material is melted, it is cooled and solidified to form the solder layer 5. The solder layer 5 is located between the first diffusion layer 4 and the second diffusion layer 6.

[0068] In one embodiment, the preset trajectory is a circle, a straight line, an arc, or a spiral.

[0069] The present invention is described by taking the connection between a sapphire part and a titanium alloy part as a specific embodiment: the first welded part is made of sapphire material, and the length×width×thickness of the first welded part is 12×8×3mm; the second welded part is made of titanium alloy, and the length×width×thickness of the second welded part is 20×30×5mm, and the solder is AgCuTi. The specific implementation steps are as follows:

[0070] The surface of the first part to be welded is polished, and the surface of the second part to be welded is polished with sandpaper to remove surface oxides and other impurities. The first and second parts to be welded after surface treatment are ultrasonically cleaned in alcohol and blown dry for use. AgCuTi is selected as the solder, and AgCuTi solder paste is evenly coated on the surfaces to be welded of the first and second parts to be welded using a wire mesh. The coated first and second parts to be welded are pressed together using a brazing tool to form a welded assembly. The assembly to be welded is sent into a vacuum brazing hot treatment furnace, and brazing is performed according to the brazing process route. First, the furnace temperature is raised from room temperature to the brazing temperature of 850°C, and then kept at the brazing temperature of 850°C for 10 minutes, and finally the furnace temperature is lowered to room temperature to complete the brazing process, achieving the preliminary connection between the first and second parts to be welded, and obtaining a brazed welded assembly. A femtosecond laser is selected, and the wavelength of the laser is 1030nm, the maximum power is 20W, and the repetition frequency is 200kHz. The brazing parts are fixed to the laser transmission welding machine by using the laser transmission welding tool, and the un-brazed surface of the first part to be welded is facing upwards. Through optical control, the laser focus of the laser is focused on the melted and resolidified solder AgCuTi through the first part to be welded; the laser processing parameters are selected as speed of 0.5mm / min, power of 10W, and processing path of parallel lines with a spacing of 100um, so that the first part to be welded, the second part to be welded and the brazing layer are melted, and cooled and solidified in a short time to form a high-strength fusion weld, and finally complete the laser transmission welding.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite welding method, characterized in that: The composite welding method is used for welding a first workpiece to be welded and a second workpiece to be welded, wherein the first workpiece to be welded is a transparent material, and the second workpiece to be welded is a transparent material or a metal material. The composite welding method comprises the following steps: S1, cleaning the surfaces of the first workpiece to be welded and the second workpiece to be welded; S2, coating a brazing material on a welding interface between the first workpiece to be welded and the second workpiece to be welded, and clamping the first workpiece to be welded and the second workpiece to be welded to form a welded assembly; S3, sending the assembly to be welded into a vacuum brazing furnace for brazing, wherein the brazing material is melted by heat and then cooled and solidified to form a brazing layer, wherein the brazing layer connects the first component to be welded and the second component to be welded to obtain a brazed welded component; S4, taking the brazing component out of the vacuum brazing furnace, focusing the laser on the brazing layer of the brazing component, and performing scanning welding with the laser according to a preset trajectory to obtain a welded part.

2. The hybrid welding method according to claim 1, characterized in that: Step S1 specifically includes the following steps: Performing surface treatment on the first workpiece to be welded and the second workpiece to be welded to clean impurities on the surfaces thereof; After the surface treatment is completed, the first workpiece to be welded and the second workpiece to be welded are ultrasonically cleaned in alcohol and blown dry.

3. The hybrid welding method according to claim 1, characterized in that: Step S3 specifically includes the following steps: Placing the assembly to be welded into a vacuum brazing furnace, raising the furnace temperature to the brazing temperature, and melting the brazing material by the heat; Keeping the assembly to be welded at the brazing temperature for a preset time; The furnace temperature is lowered to room temperature, and the brazing material is cooled and solidified to form a brazing layer, and the brazing layer connects the first part to be welded and the second part to be welded to obtain a brazed welded part.

4. The hybrid welding method according to claim 1, characterized in that: Step S4 specifically includes the following steps: The surface of the first workpiece to be welded is facing upward, the laser passes through the first workpiece to be welded and focuses on the brazing layer of the brazed workpiece; The laser performs scanning welding according to a preset trajectory, and performs interval welding on the welding interface to form a plurality of nail-shaped welds distributed in a dot matrix on the welding interface. The nail-shaped welds connect the first workpiece to be welded, the brazing layer and the second workpiece to be welded to obtain a welded part.

5. The hybrid welding method according to claim 1, characterized in that: The laser includes at least one of a pulse laser, a millisecond laser, a nanosecond laser, a picosecond laser and a femtosecond laser.

6. The hybrid welding method according to claim 1, characterized in that: The transparent material includes at least one of quartz glass, borosilicate glass, aluminosilicate glass and sapphire.

7. The hybrid welding method according to claim 1, characterized in that: The metal material includes at least one of copper alloy, Kovar alloy, titanium alloy, stainless steel, aluminum alloy and high temperature alloy.

8. The hybrid welding method according to claim 1, characterized in that: The brazing layer includes a first diffusion layer, a solder layer and a second diffusion layer. The brazing material is diffusely connected with the first workpiece to be welded to form the first diffusion layer. The brazing material is diffusely connected with the second workpiece to be welded to form the second diffusion layer. The brazing material is melted, cooled and solidified to form the solder layer. The solder layer is located between the first diffusion layer and the second diffusion layer.

9. The hybrid welding method according to claim 1, characterized in that: The preset trajectory is a circle, a straight line, an arc, or a spiral line.

10. The hybrid welding method according to claim 1, characterized in that: The first workpiece to be welded is made of sapphire material, the second workpiece to be welded is made of titanium alloy material, and the brazing material is AgCuTi solder paste.

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