A heterogeneous joint welding system and method based on a uniform temperature field

Abstract

This invention relates to the field of laser welding technology, specifically to a welding system for dissimilar joints based on a uniform temperature field. A first base material and a second base material are sequentially overlapped and pressed together by a welding fixture. At least one set of temperature field equalization modules is provided between the first base material and the welding fixture to form a uniform temperature field between the base materials. By incorporating temperature field equalization modules between the base materials and the welding fixture, preheating before welding improves welding efficiency. During dissimilar joint welding, a uniform temperature field is effectively established, enabling laser welding of dissimilar materials. This effectively reduces welding defects such as porosity and improves the adaptability of the laser welding process. Simultaneously, the heat concentrated at the weld seam is rapidly conducted to other parts of the weld, effectively increasing the weldable temperature range. This results in a larger effective connection width and area under the same welding parameters, enhancing the joint strength. A welding method for dissimilar joints is also provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser welding, in particular to a heterogeneous joint welding system and method based on a uniform temperature field. BACKGROUND

[0002] Heterogeneous materials, especially materials with large differences in thermal conductivity, are usually difficult to connect due to the large difference in physical properties between the two materials. At present, thermoplastic and its composite materials have developed rapidly in various fields such as automobiles, machinery, medical treatment, etc. due to their advantages of small density, high strength, short molding cycle and reusability. During use, thermoplastic and its composite materials also inevitably need to be connected with other materials, especially heterogeneous materials with large differences in thermal conductivity such as various steels or light alloys.

[0003] The connection technology of the above two heterogeneous materials in the prior art is usually divided into three categories: glueing, mechanical connection (such as screwing and riveting) and welding technology; among them, glueing and mechanical connection have poor mechanical properties and connection performance of the heterogeneous joint after connection, and it is difficult to meet the actual use requirements; at present, laser welding technology is used more, but due to the high energy density characteristics of laser with high concentration and high brightness, the thermal conductivity of thermoplastic and its composite materials is low (thermal conductivity <1 W / mK) and sensitive to heat (such as nylon-66 melting temperature is 260~290℃, and starts to vaporize when the temperature exceeds 300℃), and if the laser power is too high, it is easy to produce penetrating defects, and if the laser power is too low, the connection area is too small or effective connection cannot be achieved. Therefore, how to realize effective connection of heterogeneous joints under the condition of ensuring high efficiency of laser welding is a problem to be solved at present. SUMMARY

[0004] The purpose of the present application is to provide a heterogeneous joint welding system and method based on a uniform temperature field to solve the above-mentioned problems in the background art.

[0005] To solve the above technical problems, the technical solution provided by the present application is:

[0006] A heterogeneous joint welding system based on a uniform temperature field is provided, comprising a first base material and a second base material, the first base material and the second base material being heterogeneous materials, the first base material and the second base material being overlapped in turn and being pressed by a welding tool, at least one set of temperature field balancing modules being provided between the first base material and the welding tool to form a uniform temperature field between the welded base materials.

[0007] On the basis of the above technical scheme, the temperature field equalization module comprises a temperature control module and a heat insulation module and a high-thermal-conductivity module arranged in sequence between the welding tool and the first base material, the heat insulation module is made of heat insulation material, the high-thermal-conductivity module is made of high-thermal-conductivity metal material, and the temperature control module is electrically connected with the high-thermal-conductivity module.

[0008] On the basis of the above technical scheme, the material of the heat insulation module is one of epoxy resin and phenolic resin, and the material of the high-thermal-conductivity module is one of silver and copper.

[0009] On the basis of the above technical scheme, a reinforcing phase is further arranged between the first base material and the second base material.

[0010] On the basis of the above technical scheme, the reinforcing phase is arranged as a short rod carbon fiber, a short rod glass fiber or a short rod metal wire.

[0011] On the basis of the above technical scheme, the diameter of the reinforcing phase is 0.5-10 μm, the length is 10-50 mm, and the spreading thickness of the reinforcing phase is 5-20 μm.

[0012] On the basis of the above technical scheme, the first base material is a lightweight alloy, and the second base material is a thermoplastic plastic or a carbon fiber or glass fiber reinforced composite material.

[0013] A welding method of a heterogeneous joint based on a uniform temperature field is also provided, comprising the following steps:

[0014] Step one, base material cleaning: a lightweight alloy is used as the first base material, and a thermoplastic plastic or a composite material thereof is used as the second base material, and then the surfaces of the two welding base materials are cleaned with an organic solvent to remove dust, oil stains and impurities on the surfaces;

[0015] Step two, concave-convex structure preparation: a concave-convex structure is processed on the surface of the lightweight alloy by using a shot blasting, mechanical processing or laser etching method;

[0016] Step three, temperature field equalization module installation: a heat insulation module and a high-thermal-conductivity module with suitable materials are arranged in sequence between the welding tool and the first base material, and a temperature control module is connected with the high-thermal-conductivity module to form a temperature field equalization module;

[0017] Step four, laser welding: the thermoplastic plastic base material, the lightweight alloy base material and the temperature field equalization module are placed in sequence from bottom to top between the welding tools and are fixed by the welding tools, the required temperature is adjusted by the temperature control module, then the heterogeneous joint is welded by a laser welding device to obtain the final heterogeneous joint.

[0018] On the basis of the above technical scheme, the step two further comprises spreading one or more layers of short rod carbon fibers between the first base material and the second base material.

[0019] On the basis of the above technical scheme, the tensile shear force of the heterogeneous joint is 5000-6000 N.

[0020] The technical scheme provided by the application has the following beneficial effects:

[0021] 1. In the application, the temperature field equalization module is arranged between the welding base material and the welding tool, preheating before welding can improve the welding efficiency, and a uniform temperature field can be effectively established during the welding of the heterogeneous joint, realizing the laser welding of the heterogeneous materials, especially for the heterogeneous materials with large difference in thermal conductivity; welding defects such as pores are effectively reduced, the adaptability of the laser welding process is improved, the damage of the laser with high concentration and high energy density to the base material during laser welding is reduced; at the same time, the heat gathered at the weld is rapidly conducted to other positions of the weld, effectively increasing the weldable temperature interval, so that the effective connection width is increased under the same welding parameters, the effective connection area is increased, and the connection strength of the heterogeneous joint is effectively enhanced.

[0022] 2. By arranging the reinforcing phase on the connecting interface of the first base material and the second base material, on the basis of the concave-convex structure generated on the metal bonding surface, one or more layers of reinforcing phases are added, which can not only increase the heat conduction efficiency, compensate for the defects of the base material with poor heat conduction coefficient, speed up the heat conduction from the light alloy to the thermoplastic plastic, but also improve the strength of the heterogeneous joint after embedding into the molten weld during the welding process, that is, the effective connection between the heterogeneous base materials can still be realized when the laser welding process is adopted. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic view of the heterogeneous joint welding system in the application;

[0024] Figure 2 is a cross-sectional view of the heterogeneous joint welding system in the application;

[0025] Figure 3 is a structural schematic view of the temperature field equalization module in the application;

[0026] Figure 4 is a comparison schematic view of the heterogeneous joint with / without the temperature field equalization module in the application;

[0027] Figure 5 is a schematic view of the reinforcing phase embedding structure in the application;

[0028] Figure 6 is a schematic view of the fracture of the heterogeneous joint after stretching without the temperature field equalization module in the application;

[0029] Figure 7 This is a schematic diagram of the fracture surface of a heterogeneous joint after tensile testing, obtained by welding a reinforcing phase and a temperature field equalization module in this invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0031] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] In the description of this invention, it should be understood that the terms "left", "right", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Example 1

[0034] like Figures 1 to 7 As shown, a heterogeneous joint welding system based on a uniform temperature field includes a first base material 1 and a second base material 2. The first base material 1 and the second base material 2 are heterogeneous materials. The first base material 1 and the second base material 2 are overlapped in sequence and pressed together by a welding fixture 3. At least one set of temperature field equalization modules 5 is provided between the first base material 1 and the welding fixture 3 to form a uniform temperature field between the welding base materials.

[0035] In this invention, a temperature field equalization module 5 is set between the base material and the welding fixture. Preheating before welding can improve welding efficiency. When welding dissimilar joints, a uniform temperature field can be effectively established, realizing laser welding of dissimilar materials, especially for two dissimilar materials with significantly different thermal conductivity, such as two different materials with thermal conductivity differences of 2-4 orders of magnitude. It effectively reduces welding defects such as porosity, improves the adaptability of laser welding process, and reduces damage to the base material caused by highly concentrated and high-energy-density laser during laser welding. At the same time, the heat concentrated at the weld is quickly conducted to other parts of the weld, effectively increasing the weldable temperature range. This results in a larger effective connection width and area under the same welding parameters, effectively enhancing the connection strength of dissimilar joints.

[0036] It can be understood that the welding tool 3 is provided with a welding window 4; more preferably, the temperature field balancing module 5 is symmetrically arranged between the bottom end of the welding tool 3 and the base material on both sides of the welding window 4, the heat conduction effect is better, a more uniform temperature field is formed, and the welding quality of the heterogeneous joint is improved.

[0037] On the basis of the above technical scheme, the temperature field balancing module 5 comprises a temperature control module 51 and a heat insulation module 52 and a high-thermal-conductivity module 53 arranged in sequence between the welding tool 3 and the first base material 1, the heat insulation module 52 is made of heat insulation material, the high-thermal-conductivity module 53 is made of high-thermal-conductivity metal material, and the temperature control module is electrically connected with the high-thermal-conductivity module.

[0038] On the basis of the above technical scheme, the material of the heat insulation module 52 is one of epoxy resin and phenolic resin, and the material of the high-thermal-conductivity module 53 is one of silver and copper.

[0039] Specifically, the temperature field balancing module 5 mainly comprises a temperature control module 51, a heat insulation module 52 and a high-thermal-conductivity module 53, the heat insulation module 52 and the high-thermal-conductivity module 53 are fixedly connected through bolts or other fastening modes, the temperature control module 51 is connected with the high-thermal-conductivity module 53, and the temperature of the high-thermal-conductivity module can be displayed and controlled. The temperature control module 51 can be obtained from the prior art, that is, a device for realizing temperature detection and control functions, preferably, the temperature control module 51 is a device with resistance wire heating and thermocouple temperature measurement and temperature monitoring, according to a preset temperature, when the temperature of the high-thermal-conductivity module collected by the thermocouple is lower than the preset value, the high-thermal-conductivity module starts to be heated by power, and when the temperature exceeds the preset value, the high-thermal-conductivity module stops heating.

[0040] The heat insulation module 52 is made of thermosetting materials such as epoxy resin and phenolic resin, plays a role of heat insulation and heat preservation, prevents welding heat from being conducted to the welding tool during welding and then being dissipated, reduces heat loss, reduces welding power, and can also realize welding quality of a lap joint meeting requirements, is suitable for welding of heat-sensitive materials, has stronger applicability, and has lower use cost.

[0041] The high-thermal-conductivity module 53 is made of high-thermal-conductivity metals such as silver and copper, according to actual welding requirements, in the case that the ambient temperature is relatively low or the temperature difference is large, the high-thermal-conductivity module 53 can be heated in advance before welding, preheating of the heterogeneous workpiece is realized before welding, welding quality is improved, welding efficiency is improved, and a uniform temperature field can be quickly established. In the welding process, the high-thermal-conductivity module 53 can rapidly conduct heat gathered in the center area of the weld to other positions of the weld, reduce the temperature difference, effectively increase the weldable temperature interval, make the effective connection width larger under the same welding parameters, increase the effective connection area, and strengthen the joint strength; the welding interface temperature field before and after optimization is as follows Figure 4As shown, the effect of the weld is to reduce the highest temperature in the center of the weld, widen the effective welding temperature, and achieve efficient laser welding of dissimilar base materials.

[0042] Preferably, the shape of the temperature field equalization module 5 can be adjusted according to the needs of the temperature field during welding of different materials, providing a more suitable temperature field, improving the temperature distribution during laser welding, and improving the welding quality of dissimilar joints. More preferably, the cross-sectional shape of the high-thermal-conductivity module 53 can be selected as a trapezoidal shape to meet the needs of the temperature field during actual welding; it is more suitable.

[0043] On the basis of the above technical solution, the first base material 1 is a lightweight alloy, and the second base material 2 is a thermoplastic plastic or a composite material reinforced with carbon fibers or glass fibers. Preferably, the lightweight alloy is one of magnesium alloy, aluminum alloy, and titanium alloy.

[0044] A welding method for dissimilar joints based on a uniform temperature field, comprising the following steps:

[0045] Step one, base material cleaning: using a lightweight alloy as the first base material and a thermoplastic plastic or its composite material as the second base material, then using an organic solvent to clean the surfaces of the two welding base materials to remove dust, oil stains and impurities; preferably, the organic solvent is set as alcohol or acetone;

[0046] Step two, concave-convex structure preparation: using shot blasting, mechanical processing or laser etching to process a concave-convex structure on the surface of the lightweight alloy; preferably, the concave-convex structure is set as a micron-level concave-convex structure, which can effectively improve the mechanical embedding effect of the dissimilar joint and effectively improve the strength of the dissimilar joint during welding.

[0047] Step three, temperature field equalization module installation: selecting a heat insulation module and a high-thermal-conductivity module suitable for the material to be welded and setting them in turn between the welding tooling and the first base material, and connecting the temperature control module with the high-thermal-conductivity module to form a temperature field equalization module;

[0048] Step four, laser welding: placing the thermoplastic plastic base material, the lightweight alloy base material and the temperature field equalization module in turn from bottom to top between the welding tooling and fixing them tightly by the welding tooling, adjusting the required temperature by the temperature control module, then welding the dissimilar joint by the laser welding equipment to obtain the final dissimilar joint.

[0049] Example 2

[0050] A dissimilar joint welding system based on a uniform temperature field is provided in this embodiment. On the basis of the technical solution of example 1, an enhanced phase is further provided between the first base material 1 and the second base material 2.

[0051] More preferably, the reinforcing phase is arranged as a short rod carbon fiber, a short rod glass fiber or a short rod metal wire; by using a short rod reinforcing phase, it can better enter the concave-convex structure prepared in the matrix material, and it is easier to spread uniformly in the matrix material, effectively improving the connection strength of the heterogeneous joint.

[0052] By arranging the reinforcing phase on the connecting interface of the first matrix material 1 and the second matrix material 2, on the basis of the concave-convex structure on the metal bonding surface, one or more layers of reinforcing phase are added, which not only increases the heat conduction efficiency, makes up for the defect that the matrix material with poor thermal conductivity conducts heat poorly, and speeds up the heat conduction from the light alloy to the thermoplastic plastic, but also improves the strength of the heterogeneous joint after being embedded in the molten weld during welding. That is, when laser welding process is used, effective connection between heterogeneous matrix materials can still be achieved. Figure 5 The structure schematic diagram of the reinforcing phase embedded in the matrix material is shown.

[0053] Preferably, the diameter of the reinforcing phase is 0.5-10 μm, the length is 10-50 mm, and the spreading thickness of the reinforcing phase is 5-20 μm.

[0054] The embodiment also provides a welding method of a heterogeneous joint based on a uniform temperature field, which comprises the following steps:

[0055] Step one, matrix material cleaning: using a light alloy as the first matrix material and a thermoplastic plastic or a composite material thereof as the second matrix material, then using an organic solvent to clean the surfaces of the two welding matrix materials respectively to remove dust, oil stains and impurities on the surfaces; preferably, the organic solvent is arranged as alcohol or acetone;

[0056] Step two, concave-convex structure preparation: using a shot blasting, mechanical processing or laser etching method to process a concave-convex structure on the surface of the light alloy; then spreading one or more layers of short rod carbon fibers between the first matrix material and the second matrix material. Preferably, after the concave-convex structure is prepared on the surface of the light alloy, one or more layers of extremely thin short rod carbon fibers are spread on the interface between the light alloy and the thermoplastic plastic. On the one hand, the short rod carbon fibers can increase the heat conduction efficiency of the light alloy, and on the other hand, the short rod carbon fibers can increase the connection strength of the heterogeneous joint after entering the molten plastic. Preferably, the concave-convex structure is arranged as a micron-level concave-convex structure, which can effectively improve the mechanical embedding effect of the heterogeneous joint and effectively improve the strength of the heterogeneous joint during the welding process.

[0057] Step three, temperature field equalization module installation: selecting a heat insulation module and a high thermal conductivity module with suitable materials and arranging them in the bottom end of the temperature control module in sequence to form a temperature field equalization module.

[0058] Step four, laser welding: thermoplastic base material, light alloy base material and temperature field balancing module are placed in the welding tool from bottom to top in turn and fixed by the welding tool, the required temperature is adjusted by the temperature control module, then the laser welding equipment is used to weld the heterogeneous joint, and the final heterogeneous joint is obtained.

[0059] Figure 6 is a schematic diagram of the fracture after stretching of the heterogeneous joint welded without the temperature field balancing module in the application; Figure 7 is a schematic diagram of the fracture after stretching of the heterogeneous joint welded with the temperature field balancing module and the reinforcing phase in the application; it can be seen that the effective connection width of the joint is obviously increased after the temperature field balancing module is added, that is, the temperature field balancing module can effectively conduct the heat accumulated at the weld to other positions of the weld, effectively increase the weldable temperature range, make the effective connection width larger under the same welding parameters, increase the effective connection area, and strengthen the strength of the obtained heterogeneous joint. The tensile shear force of the heterogeneous joint obtained after welding is 5000-6000N.

[0060] The basic principles and main features of the application are shown and described above, and it is obvious for those skilled in the art that the application is not limited to the details of the above exemplary embodiments, therefore the embodiments should be regarded as exemplary and non-limiting, the scope of the application is defined by the appended claims instead of the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the application.

[0061] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments which can be understood by those skilled in the art.

Claims

1. A homogeneous temperature field based dissimilar joint welding system comprising a first base material and a second base material, the first base material and the second base material being dissimilar materials, characterized in that, The first and second base materials are overlapped and pressed by a welding tool, the first base material is a light alloy, the second base material is a thermoplastic plastic or a carbon fiber and glass fiber reinforced composite material, and the thermal conductivity difference is 2-4 orders of magnitude; at least one set of temperature field balancing modules is arranged between the first base material and the welding tool to form a uniform temperature field between the welded base materials; a welding window is arranged on the welding tool, and the temperature field balancing modules are symmetrically arranged between the bottom end of the welding tool on both sides of the welding window and the first base material; the temperature field balancing module comprises a temperature control module and a heat insulation module and a high thermal conductivity module arranged between the welding tool and the first base material in sequence; the temperature control module is electrically connected with the high thermal conductivity module; the heat insulation module is made of heat insulation material; and the high thermal conductivity module is made of high thermal conductivity metal material.

2. A uniform temperature field based heterogeneous joint welding system as claimed in claim 1, wherein, The temperature field balancing module comprises a temperature control module and a heat insulation module and a high thermal conductivity module arranged between the welding tool and the first base material in sequence; the heat insulation module is made of heat insulation material; the high thermal conductivity module is made of high thermal conductivity metal material; and the temperature control module is electrically connected with the high thermal conductivity module.

3. A uniform temperature field based heterogeneous joint welding system as claimed in claim 2, wherein, The material of the heat insulation module is one of epoxy resin and phenolic resin, and the material of the high thermal conductivity module is one of silver and copper.

4. The uniform temperature field based heterogeneous joint welding system of claim 1, wherein, A reinforcing phase is further arranged between the first and second base materials.

5. A uniform temperature field based heterogeneous joint welding system as claimed in claim 4, wherein, The reinforcing phase is a short rod carbon fiber, a short rod glass fiber or a short rod metal wire.

6. A uniform temperature field based heterogeneous joint welding system as claimed in claim 4, wherein, The diameter of the reinforcing phase is 0.5-10 microns, the length is 10-50 mm, and the spreading thickness of the reinforcing phase is 5-20 microns.

7. The uniform temperature field based heterogeneous joint welding system of claim 1, wherein, The first base material is a light alloy, and the second base material is a thermoplastic plastic or a carbon fiber and glass fiber reinforced composite material.

8. A method of welding a homogeneous temperature field based heterojunction according to claim 7, characterized in that, The method comprises the following steps: Step one, base material cleaning: light alloy is used as the first base material, and thermoplastic plastic or its composite material is used as the second base material, then the surfaces of the two welding base materials are cleaned by using organic solvents to remove dust, oil stains and impurities on the surfaces; Step two, concave-convex structure preparation: a concave-convex structure is processed on the surface of the light alloy by using shot blasting, mechanical processing or laser etching; Step three, temperature field balancing module installation: heat insulation modules and high thermal conductivity modules of suitable materials are arranged between the welding tool and the first base material in sequence, and a temperature control module is connected to form a temperature field balancing module; Step four, laser welding: the thermoplastic plastic base material, the light alloy base material and the temperature field balancing module are placed in the welding tool from bottom to top and are fixed by the welding tool, the required temperature is adjusted by the temperature control module, then the heterogeneous joint is welded by a laser welding device to obtain the final heterogeneous joint.

9. A method of welding a heterogeneous joint based on a uniform temperature field according to claim 8, characterized in that, The step two further comprises spreading one or more layers of short rod carbon fibers between the first and second base materials.

10. The method of claim 8, wherein the method is a method of welding a heterogeneous joint based on a uniform temperature field, characterized in that, The tensile shear force of the heterogeneous joint is 5000-6000 N.

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