Method for connecting metal pieces, metal workpiece, and electronic device

Abstract

This application provides a method for joining metal parts, a metal workpiece, and an electronic device. The joining method includes: providing a first metal part and a second metal part; the first metal part includes a base and a connecting portion disposed on the surface of the base; the connecting portion includes a first part and a second part, the first part being connected to the base, and the second part being connected to the side of the first part away from the base; the second metal part has a first surface, the first surface having a through hole that mates with the first part; inserting the connecting portion of the first metal part into the through hole of the second metal part in a direction toward the first surface, the first part being located within the through hole, and the second part extending out of the through hole; and fusing the connecting portion and the second metal part together by welding to form a welded part, thereby obtaining a metal workpiece, the welded part including a welding protrusion protruding from the first surface. This joining method allows the connection between two metal parts to form a riveted reinforced structure, thereby improving the structural stability of the welded part and extending the service life of the product.

Description

Technical Field

[0001] This application relates to the field of joining dissimilar alloy materials, specifically to a method for joining metal parts, a metal workpiece, and an electronic device. Background Technology

[0002] With the development of science and technology, modern industry has placed higher and more stringent demands on the performance of components. In addition to conventional mechanical properties, components are required to have properties such as corrosion resistance, reduced electromagnetic shielding, and thermal conductivity. However, a single type of metal material often cannot meet the requirements of multiple properties simultaneously. Welded components made of dissimilar materials can maximize the advantages of each material, meet the different requirements of materials in practical applications, and give full play to the performance advantages of different materials.

[0003] However, welding between dissimilar metals is constrained by issues such as mutual solubility and the formation of intermetallic compounds. Defects are easily generated at the weld, resulting in low bonding strength between dissimilar metals and poor structural stability of the welded components, which is not conducive to the long-term use of the product. Therefore, it is necessary to provide a new method for connecting dissimilar metal parts to improve the bonding force between different metal materials and enable the welded components to have higher structural stability. Summary of the Invention

[0004] In view of this, this application provides a method for connecting metal parts. This method uses welding and a special structural design to form a riveted reinforced structure at the connection point of two metal parts, thereby improving the structural stability of the welded parts and extending the service life of the product.

[0005] Specifically, the first aspect of this application provides a method for connecting metal parts, the method comprising: providing a first metal part and a second metal part, the first metal part comprising a base and a connecting portion disposed on the surface of the base, the connecting portion comprising a first part and a second part, the first part being connected to the base, and the second part being connected to the side of the first part away from the base; the second metal part having a first surface, the first surface being provided with a through hole that mates with the first part;

[0006] The connecting portion of the first metal part is inserted into the through hole of the second metal part in the direction toward the first surface, the first portion is located in the through hole, and the second portion protrudes from the through hole; the connecting portion and the second metal part are fused together by welding to form a welded portion, thereby obtaining a metal workpiece, the welded portion including a welding protrusion protruding from the first surface.

[0007] This application extends the connecting portion of the first metal part to form a second part located outside the through hole of the second metal part. During the welding process, the connecting portion interacts with the second metal part at high temperature to form a welded part. Since the first metal part has a longer connecting portion, the welded part has a welding protrusion higher than the first surface. This welding protrusion can strengthen the bonding force between the first metal part and the second metal part and improve the structural stability of the metal workpiece.

[0008] Optionally, in the extending direction of the through hole, the height ratio of the second portion to the first portion is 0.15 to 0.35.

[0009] Optionally, the surface of the second part away from the first part has a bevel, and the angle of the bevel relative to the interface between the first part and the second part is 20° to 70°.

[0010] Optionally, the first metal part and the second metal part have different melting points, and the welding site is biased towards the side of the metal part with the higher melting point.

[0011] Optionally, the offset of the welding site is 0.1 mm to 0.3 mm.

[0012] Optionally, the welding includes laser welding, wherein the welding speed of the laser welding is 50mm / s to 150mm / s; the power of the laser welding is 320W to 560W; and the frequency of the laser welding is 4kHz to 6kHz.

[0013] Optionally, the connection method further includes: injection molding the welding protrusion to form a plastic body on the surface of the welding protrusion; the plastic body covering the first metal part and the second metal part.

[0014] Optionally, the path shape of the welding site includes one or more of the following: straight, C-shaped, figure-eight shaped, and spiral.

[0015] Optionally, the first metal part includes an aluminum alloy part, and the second metal part includes a magnesium alloy part. Optionally, the shape of the first portion includes a cylinder; the welding path curve includes a helical shape, the helical shape includes a spiral line, and the outer circle diameter of the spiral line is less than or equal to the radius of the cylinder.

[0016] Optionally, the pitch of the helix is ​​less than or equal to 0.1 mm.

[0017] Optionally, the outer circle diameter of the spiral shape is less than or equal to half the radius of the cylinder.

[0018] Secondly, this application provides a metal workpiece, which is prepared by the metal workpiece joining method as described in the first aspect.

[0019] Optionally, the welding strength of the metal workpiece is greater than or equal to 80N.

[0020] Thirdly, this application provides an electronic device that includes a metal workpiece as described in the second aspect. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a first metal part provided in an embodiment of this application;

[0022] Figure 2 This is a schematic diagram of the structure of the second metal part provided in an embodiment of this application;

[0023] Figure 3 A schematic diagram of the fitting of a first metal part and a second metal part according to an embodiment of this application;

[0024] Figure 4 A schematic cross-sectional view of the fitting of a first metal part and a second metal part provided in an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of the structure of a metal workpiece provided in an embodiment of this application;

[0026] Figure 6 A schematic diagram of the interlocking cross-section of the third and fourth metal parts provided in proportion to this application;

[0027] Figure 7 A structural schematic diagram of a welded component provided on a proportional basis for this application;

[0028] Figure 8 A schematic cross-sectional view of the fitting of a first metal part and a second metal part provided in an embodiment of this application;

[0029] Figure 9 A schematic cross-sectional view of the fitting of a first metal part and a second metal part provided in an embodiment of this application;

[0030] Figure 10 A welding schematic diagram provided for one embodiment of this application;

[0031] Figure 11 A welding schematic diagram provided for one embodiment of this application;

[0032] Figure 12 This is a schematic diagram of a welding path provided in an embodiment of this application;

[0033] Figure 13 A schematic diagram of a spiral provided in one embodiment of this application;

[0034] Figure 14 This is a schematic diagram of the structure of a metal workpiece provided in an embodiment of this application;

[0035] Figure 15 This is a schematic diagram of the structure of the first metal component in Embodiment 1 of this application;

[0036] Figure 16 This is a schematic diagram of the structure of the metal workpiece in Embodiment 1 of this application;

[0037] Figure 17 This is a schematic diagram of the structure of the first metal component in Embodiment 10 of this application;

[0038] Figure 18 Metallographic image of the weld joint of a cross-section of a metal workpiece provided in Embodiment 11 of this application;

[0039] Figure 19 This is a diagram of the weld points on the surface of a metal workpiece provided in Embodiment 12 of this application;

[0040] Figure 20 This is a schematic diagram of a welding strength testing method;

[0041] Figure 21 This is a welding strength test diagram of the composite metal part in Embodiment 1 of this application. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0043] Aluminum alloys have the advantages of corrosion resistance, impact resistance and good machinability, while magnesium alloys have low density, good heat dissipation and good electromagnetic shielding properties. Combining aluminum alloys and magnesium alloys to form composite materials can combine the properties of both, achieve product lightweighting and enrich product appearance. However, due to significant differences in composition, microstructure, and metallurgical properties between magnesium alloys and aluminum alloys, the following problems arise during welding: 1. Aluminum and magnesium readily form oxide films in air. These oxide films have very high melting points, and during welding, they fail to melt, leading to various defects in the weld joint and reducing its mechanical properties. 2. Aluminum and magnesium have different crystal structures: aluminum has a face-centered cubic structure, while magnesium has a close-packed hexagonal structure. Not only is their mutual solubility very low, but their liquid and solid solubility differ significantly. During welding, various intermetallic compounds easily form at the interface between the liquid and liquid phases of magnesium and aluminum, reducing the mechanical properties of the joint. 3. Aluminum and magnesium exhibit significant differences in their gas solubility in liquid and solid states. At high-temperature liquid states, they can dissolve large amounts of gas, while at low-temperature solid states, gas solubility is low. During solidification, the gas cannot escape quickly enough, easily leading to defects such as porosity in the weld and reducing the mechanical properties of the joint. It can be seen that welding magnesium and aluminum results in numerous weld defects, lower bonding strength between the aluminum and magnesium alloys in the resulting welded components, and a low product yield. Therefore, this application provides a method for connecting metal parts, which enables a stable connection between metal parts through a special structural design, thereby improving the structural stability of the product.

[0044] The methods for connecting metal parts provided in this application include:

[0045] Step 100: Provide a first metal part and a second metal part. The first metal part includes a base and a connecting part disposed on the surface of the base. The connecting part includes a first part and a second part. The first part is connected to the base, and the second part is connected to the side of the first part away from the base. The second metal part has a first surface, and the first surface is provided with a through hole that mates with the first part.

[0046] Step 200: Insert the connecting part of the first metal part into the through hole of the second metal part in the direction toward the first surface, with the first part located in the through hole and the second part protruding out of the through hole; weld the connecting part and the second metal part to form a welded part, thereby obtaining a metal workpiece, the welded part including a welding protrusion protruding from the first surface.

[0047] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a first metal component provided in an embodiment of this application. The first metal component 100 includes a base 13 and a connecting portion directly connected to the base 13. The connecting portion includes a first part 11 and a second part 12, with the second part 12 located on the surface of the first part 11 away from the base 13. Please refer to [link / reference]. Figure 2 , Figure 2 This is a schematic diagram of the structure of a second metal part provided in one embodiment of this application. The second metal part 200 has a through hole 21 that matches the first part of the first metal part. In some embodiments of this application, the shape of the through hole in the orthographic projection of the first metal part can be any one of a circle, an ellipse, a rectangle, and a polygon. In this application, the first part of the first metal part and the through hole of the second metal part can cooperate with each other, that is, the first part of the first metal part can completely fill the through hole of the second metal part. This engaging structure can fix the first metal part and the second metal part together, which is beneficial to subsequent welding and can also improve the structural stability of the metal workpiece.

[0048] In step 200 of this application, when the connecting portion of the first metal part is inserted into the through hole of the second metal part in the direction toward the first surface, the first part of the first metal part engages with the through hole of the second metal part, and the second part of the first metal part protrudes from the through hole and is exposed on the outside of the first metal part. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram illustrating the fitting of a first metal part and a second metal part according to an embodiment of this application. Figure 3 In this embodiment, the first portion 11 of the first metal member 100 is embedded in the through hole of the second metal member 200, and the second portion 12 of the first metal member 100 protrudes from the through hole and protrudes from the first surface. In this application, to ensure that the second portion of the first metal member can protrude from the through hole of the second metal member, the projection of the second portion on the second metal member falls into the through hole, that is, the projection of the second portion on the second metal member is completely within the projection of the through hole on the first metal member, and the projection area of ​​the second portion on the second metal member is less than or equal to the projection area of ​​the through hole on the second metal member.

[0049] For ease of explanation, in this application, the extension direction of the through hole is taken as the thickness direction, i.e., the height direction, of the first and second metal parts. Please refer to [link / reference]. Figure 4 , Figure 4 This is a schematic cross-sectional view of the fitting of the first metal part and the second metal part according to an embodiment of this application. Figure 4 In the first direction, the extension direction of the through hole of the second metal part is the first surface, which is the side surface of the second metal part 200 close to the second part 12. In the first direction, the height H1 of the first part 11 is equal to the depth of the through hole. The second part 12 extends from the first part 11. The second part 12 is higher than the plane where the first surface is located in the first direction. The height H2 of the second part 12 is the maximum distance between the top surface of the second part 12 and the first surface. The top surface of the second part refers to the side surface of the second part away from the first part.

[0050] In this embodiment, when welding the first metal part and the second metal part, the interface area between the first and second metal parts melts, that is, the metal at the interface between the connecting part and the through hole melts. Different elements in the two metal parts fuse at high temperature to form intermetallic compounds. Due to the high thermal conductivity of metals, the second part in the connecting part also melts and participates in the formation of the welded part, allowing the welded part to form a weld protrusion higher than the first surface. This weld protrusion can reinforce the welded area and work together with the base material to form a fastening internal locking structure similar to riveting between the first and second metal parts, thereby greatly improving the structural stability of the metal workpiece. Please refer to [link to relevant documentation]. Figure 5 , Figure 5 This is a schematic diagram of the structure of a metal workpiece provided in an embodiment of this application. In the metal workpiece 300, the welding portion 30 is located between the first metal part 100 and the second metal part 200. The welding portion 30 has a welding protrusion that protrudes above the plane containing the first surface in a first direction. This welding protrusion can effectively strengthen the bonding force between the first metal part and the second metal part, thereby improving the structural stability of the metal workpiece. For further explanation of the effects of this application, please refer to... Figure 6 , Figure 6 The schematic cross-sectional view of the fitting of the third and fourth metal parts provided to account for this application shows that the third metal part 101 does not have a second part extending from the first part. Please refer to [link / reference needed]. Figure 7 , Figure 7 The above is a schematic diagram of the structure of the welded component provided in the example. Since the fourth metal part of the example does not have the second part, after the welding is completed, the molten metal flows horizontally and cools to form a weld 31. The weld 31 does not have a welding protrusion higher than the first surface, and the structural stability of its welded component is relatively poor.

[0051] In some embodiments of this application, the height ratio of the second portion to the first portion in the extension direction of the through hole is 0.15 to 0.35. Specifically, the height ratio of the second portion to the first portion may be, but is not limited to, 0.15, 0.2, 0.25, 0.3, or 0.35. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 In this diagram, the first direction is the extension direction of the through hole. The height H2 of the second part refers to the distance of the side surface of the second part 12 away from the first part 12 relative to the first surface in the first direction. The height H1 of the first part refers to the distance of the side surface of the first part 12 away from the second part 12 relative to the first surface in the first direction. By controlling the ratio of the height H2 of the second part to the height H1 of the first part, the welding protrusion can effectively improve the bonding strength of the metal parts, thereby further enhancing the structural stability of the metal workpiece.

[0052] In some embodiments of this application, the surface of the second portion away from the first portion has a bevel. Providing a bevel in the second portion improves production efficiency, allows for full penetration at the connection between the first and second metal parts, and reduces weld defects. Please refer to [link to relevant documentation]. Figure 8 , Figure 8 This is a schematic cross-sectional view of the fitting of the first metal part and the second metal part according to an embodiment of this application. Figure 8 In the first metal part, the second part has a bevel, specifically a Y-type bevel. (See also...) Figure 9 , Figure 9 This is a schematic cross-sectional view of the fitting of the first metal part and the second metal part according to an embodiment of this application. Figure 9 In the second part, there is a bevel, specifically a V-groove. The angle α of the bevel surface refers to the acute angle between the plane containing the bevel surface and the interface between the first and second parts. The interface between the first and second parts is the angle between the plane containing the first surface. In some embodiments of this application, the angle of the bevel surface is 20° to 70°. In some embodiments, the angle of the bevel surface is 25° to 60°. In some embodiments of this application, the bevel type is a V-groove, meaning the bevel surface of the second part is adjacent to the first surface of the second metal part. A V-groove is more advantageous for adjusting the structure of the weld protrusion formed after welding, effectively strengthening the weld.

[0053] In this application, the welding method includes either electron beam welding or laser welding. In some embodiments, the welding method includes laser welding. Laser welding does not require inert gas protection, making operation more convenient. Furthermore, laser welding features low heat input, high energy density, and a narrow heat-affected zone, effectively reducing defects such as cracks and porosity in the weld joint and forming a metal workpiece with high bonding strength. In some embodiments of this application, the laser welding speed is 50 mm / s to 150 mm / s, the laser welding power is 320 W to 560 W, and the laser welding frequency is 4 kHz to 6 kHz. Under the above laser welding conditions, the first and second metal parts can form a weld with fewer defects, thereby improving the structural stability of the metal workpiece. In some embodiments of this application, the laser used for laser welding includes continuous lasers and pulsed lasers. In some embodiments, the laser used for laser welding is a continuous laser.

[0054] In some embodiments of this application, during the welding process, the welding point is biased towards the metal part with the higher melting point. Taking aluminum alloy and magnesium alloy as examples, aluminum alloy has a higher melting point than magnesium alloy. During the welding process, the welding point can be shifted from the interface between the two metal parts towards the aluminum alloy. Due to the differences in thermal conductivity, heat capacity, melting point, and the fluidity and density of molten metal between aluminum alloy and magnesium alloy, when the welding point is located at the interface between the two metal parts, the molten metal inside the weld is not mixed uniformly, resulting in more brittle intermetallic compounds and thus reducing the mechanical strength of the weld joint. By shifting the welding point towards the aluminum alloy, the melting ratio of aluminum alloy and magnesium alloy during the welding process can be optimized, thereby improving the performance of the weld joint. Specifically, taking laser welding as an example, when the center of the laser beam spot is biased towards one of the metal parts, due to the difference in heating between the two metal parts, the difference in fluidity between the two metals becomes smaller, making it easier to bond, thus obtaining a weld with excellent performance.

[0055] In some embodiments of this application, the offset of the welding point towards the metal part with a higher melting point is 0.1 mm to 0.3 mm. Specifically, the offset of the welding point can be, but is not limited to, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, or 0.3 mm. The offset of the welding point refers to the offset of the welding point relative to the interface between the two metal parts. Please refer to... Figure 10 , Figure 10 This is a welding schematic diagram provided for one embodiment of the present application. Figure 10 In this context, the second direction is perpendicular to the interface between the two metal parts, and the offset 'd' of the welding point refers to the distance of the welding point relative to the interface in the second direction. In some embodiments, the first metal part is an aluminum alloy, the second metal part is a magnesium alloy, and the welding point is offset towards the first metal part, that is, the welding point falls on the surface of the second part. A schematic diagram of the welding point is shown below. Figure 10 As shown in some embodiments, the first metal part is a magnesium alloy, the second metal part is an aluminum alloy, and the welding point is offset towards the second metal part, that is, the welding point falls on the surface of the second metal part. A schematic diagram of the welding point is shown below. Figure 11 As shown, Figure 11 This is a welding schematic diagram provided for one embodiment of the present application. Figure 11 In this process, the welding point is offset from the interface between the two metal parts towards the second metal part. The inventors of this application have discovered that the offset of the welding point can adjust the temperature distribution at the interface between the magnesium alloy and the aluminum alloy. Offsetting the welding point towards the aluminum alloy side by 0.1mm to 0.3mm can reduce the magnesium content in the weld molten zone. Since the maximum solubility of magnesium in aluminum is 17.4%, controlling the offset of the welding point can dilute the Mg element in the molten pool, keeping the magnesium content below 17.4%. Within the offset range of this application, the intermetallic compound formed at the weld is mainly Mg2Al3, while the intermetallic compound formed without offset is mainly Mg.17 Al 12 Mg 17 Al 12 Compared to Mg2Al3, it is more brittle, which is detrimental to the structural stability of the weld. Therefore, this application uses offset treatment to reduce the content and types of brittle intermetallic compounds at the weld, thereby effectively improving the connection strength between metal parts.

[0056] In some embodiments of this application, the path shape of the welding site includes one or more of the following: straight line, C-shape, figure-eight shape, and spiral shape. In some embodiments, the first metal part is an aluminum alloy, the second metal part is a magnesium alloy, the first part is cylindrical, and a spiral path is used to weld the first metal part and the second metal part. Please refer to [link to relevant documentation]. Figure 12 , Figure 12 This is a schematic diagram of a welding path provided in one embodiment of this application. Figure 12 In the first part, the shape is a cylinder with a radius of R, and the welding path is a spiral. Please refer to [link / reference]. Figure 13 , Figure 13 This is a schematic diagram of a helix provided in one embodiment of this application. The outer circle diameter r1 of the helix is ​​the maximum diameter of the helix, and the pitch r2 of the helix is ​​the distance between two adjacent threads. In some embodiments of this application, the outer circle diameter r1 of the helix is ​​less than or equal to the radius R of the cylinder. Further, the outer circle diameter r1 of the helix is ​​less than or equal to half the radius of the cylinder, i.e., r1 ≤ 0.5R. Controlling the outer circle diameter of the helix is ​​beneficial for promoting the fusion of the first metal part and the second metal part to form a welded part, improving welding efficiency, shortening production time, and reducing production energy consumption. In some embodiments, the pitch of the helix is ​​less than or equal to 0.1 mm. In some embodiments of this application, the number of weld points on the helix is ​​set such that the overlapping area of ​​two weld points is less than or equal to 1 / 3 of the area of ​​a single weld point.

[0057] In this application, the first metal component and the second metal component have different melting points. In some embodiments, the first metal component is an aluminum alloy, and the second metal component is a magnesium alloy; in other embodiments, the first metal component is a magnesium alloy and the second metal component is an aluminum alloy. In some embodiments of this application, the aluminum alloy includes one or more of 2-series, 5-series, and 6-series aluminum alloys, as well as 7-series aluminum alloys with a zinc content in the range of 1%-10%. In some embodiments, the aluminum alloy grade can be any one of 2014, 2024, 2224, 5052, 5252, 5182, 6063, 6061, and 6013, and the aluminum alloy forming method can be any one of rolling, extrusion, CNC forming, die casting, casting, injection molding, semi-solid forming, powder metallurgy, and additive manufacturing. In some embodiments of this application, the magnesium alloy can be any one of Mg-Al-Zn alloy, Mg-Li-Zn alloy, Mg-Al-Mn alloy and Mg-Zn-Gr alloy, and the forming method of the magnesium alloy can be any one of rolling forming, extrusion forming, CNC forming, die casting forming, casting forming, injection molding, semi-solid forming, powder metallurgy and additive manufacturing.

[0058] In some embodiments of this application, a metal welded part is obtained by welding a first metal part and a second metal part together, and then injection molding is performed on the surface of the metal welded part having the welding protrusion to form a plastic body on the surfaces of the first metal part and the second metal part. Please refer to [link to relevant documentation]. Figure 14 , Figure 14 This is a schematic diagram of the structure of a metal workpiece provided in an embodiment of this application. The metal workpiece includes a first metal part 100, a second metal part 200, a welding portion 30, and a plastic body 40. The plastic body 40 covers the surfaces of the first metal part 100, the second metal part 200, and the welding portion 30. Providing the plastic body at the welding portion further strengthens the bond strength between the first and second metal parts, giving the metal workpiece good structural stability.

[0059] In some embodiments of this application, the plastic body includes one or more of polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyamide (PA), polyphthalamide (PPA), polypropylene (PP), polycarbonate (PC), polyethersulfone (PPSU), and polyetheretherketone (PEEK). In some embodiments of this application, the plastic body also includes glass fibers, with the glass fibers comprising less than or equal to 55% by mass. The specific mass percentage of glass fibers in the plastic body may be, but is not limited to, 1%, 5%, 10%, 20%, 30%, or 55%. Adding an appropriate amount of glass fibers to the plastic body can improve its mechanical properties, enabling it to adequately protect welded joints and extend the service life of metal workpieces.

[0060] In some embodiments of this application, the injection temperature is 200℃~500℃, the mold temperature is 80℃~350℃, and the injection pressure is 75MPa~300MPa. Specifically, the injection temperature can be, but is not limited to, 200℃, 300℃, 400℃, or 500℃; the mold temperature can be, but is not limited to, 80℃, 100℃, 150℃, 200℃, 250℃, 300℃, or 350℃; and the injection pressure can be, but is not limited to, 75MPa, 100MPa, 150MPa, 200MPa, or 300MPa. In some embodiments of this application, the injection temperature is 300℃~380℃, the mold temperature is 130℃~230℃, and the injection pressure is 120MPa~200MPa. Controlling the temperature and pressure during the injection molding process allows the plastic to penetrate into the pores of the porous membrane, ensuring a tight bond between the plastic and the bonding method. In some embodiments of this application, the plastic is dried in an oven before injection molding at a temperature of 80°C to 200°C for 1 to 7 hours. In some embodiments, the plastic is dried at a temperature of 100°C to 150°C for 2 to 6 hours.

[0061] In some embodiments of this application, the surface of the metal welded parts is pretreated before injection molding to improve the connection strength between the plastic and the metal welded parts. In some embodiments, the surface treatment includes one or more of degreasing, acid etching, alkaline etching, and neutralization. The degreasing reagent can be a sodium carbonate solution with a pH value greater than or equal to 10.2, a degreasing temperature of 50°C to 70°C, and a degreasing time of 2 to 10 minutes. The acid etching reagent can be a sulfuric acid solution with a concentration of 10 g / L to 50 g / L, an acid etching temperature of 15°C to 35°C, and an acid etching time of 10 to 60 seconds. The alkaline etching reagent can be a sodium hydroxide solution with a concentration of 30 g / L to 60 g / L, an alkaline etching temperature of 50°C to 60°C, and an alkaline etching time of 1 to 2 minutes. The neutralization reagent can be a nitric acid solution with a concentration of 10 g / L to 50 g / L, a neutralization temperature of 15°C to 35°C, and a neutralization time of 5 to 20 seconds. In some embodiments, the surface treatment includes creating pores on the metal surface of the metal weldment. The pore-making process includes placing the metal weldment in a metal chloride solution and then performing anodizing treatment in an alkali metal hydroxide solution to form a porous oxide film on the surface of the metal weldment. The porous oxide film can increase the friction between the metal weldment and the plastic body, thereby improving the bonding strength between the plastic body and the metal weldment.

[0062] The metal connection method provided in this application enables a reliable connection between metal parts, resulting in a metal workpiece with good structural stability. This metal workpiece has good dustproof and waterproof properties and can achieve product lightweighting, which is beneficial for its application in mobile communication equipment, electronic and electrical equipment, automotive machinery and other fields.

[0063] This application also provides a metal workpiece, which is prepared by the metal workpiece joining method provided in this application.

[0064] This application also provides an electronic device that includes the metal workpiece provided in this application.

[0065] The implementation methods of this application will be further described below through several embodiments.

[0066] Example 1

[0067] A method for connecting metal parts, comprising:

[0068] Aluminum alloy of grade 6013 was machined into a 20mm × 8mm × 12mm template. A cylinder with a diameter of 1.5mm and a height of 1.5mm was machined on one side of the template. A V-shaped bevel was then created on the top surface of the aluminum alloy cylinder, forming a bevel face with an angle of 45° and a height of 0.3mm. (See also...) Figure 15 , Figure 15 This is a schematic diagram of the structure of the first metal part in Embodiment 1 of this application, wherein the connecting part is a columnar structure, the height of the first part of the connecting part is 1.2mm, and the height of the second part is 0.3mm.

[0069] Magnesium alloy of grade AZ31B was machined into a 20mm×8mm×1.2mm strip, with a 1.5mm diameter ring machined at the center, followed by laser welding. To improve the quality of the weld joint, the surfaces of the magnesium and aluminum alloys to be welded were first sanded with sandpaper to remove the oxide film, and then cleaned with acetone to remove oil, impurities, etc. During the welding experiment, the laser beam spot scanning path was set as a spiral, with a minimum spiral pitch of 0.035mm, a maximum spiral pitch of 0.1mm, an outer boundary diameter of 0.35mm, and 14 spirals. Welding was then performed at a laser welding speed of 100mm / s, a laser power of 400W, a frequency of 5kHz, and the laser beam was offset 0.15mm towards the aluminum alloy side to form a weld, resulting in a composite metal part.

[0070] The welded 6013 aluminum alloy and AZ31B magnesium alloy composite metal underwent nano-injection molding pretreatment. First, it was placed in a 55℃ sodium carbonate degreasing solution for 10 minutes to remove oil. After rinsing with water, it was acid-etched in a 20 g / L sulfuric acid solution for 1 minute, followed by rinsing with water. Then, it was alkaline-etched in a 50℃ 50 g / L sodium hydroxide solution for 1.5 minutes. After rinsing with water, it was neutralized in a 30 g / L nitric acid solution for 15 seconds. After rinsing with water, it was activated in a 12 g / L sodium chloride solution for 30 minutes. After activation, it was rinsed with water and then anodized (pore-forming treatment) in an 8 g / L sodium hydroxide solution at 20℃ for 25 minutes at a voltage of 23V. After anodizing, it was rinsed with water and dried in an oven at 130℃ for 25 minutes. After drying, the magnesium / aluminum composite metal is placed into an injection mold and injection molded using PBT resin (containing 40% glass fiber). The material temperature is set to 265°C and the mold temperature is set to 150°C. After injection molding, a metal workpiece is obtained. A schematic diagram of the metal workpiece in Example 1 is shown below. Figure 16 As shown.

[0071] Example 2

[0072] The difference between the connection method in Example 2 and Example 1 is that when the aluminum alloy cylinder is subjected to V-shaped beveling, the angle of the bevel surface is 10°.

[0073] The metal workpiece was prepared using the same method as in Example 1.

[0074] Example 3

[0075] The difference between the connection method in Example 3 and Example 1 is that a cylinder with a diameter of 1.5 mm and a height of 1.6 mm is machined on one side surface of the aluminum alloy strip. The aluminum alloy cylinder is then subjected to V-shaped beveling treatment to form a bevel surface on the top surface of the cylinder. The bevel surface has an angle of 45° and a bevel depth of 0.4 mm.

[0076] The metal workpiece was prepared using the same method as in Example 1.

[0077] Example 4

[0078] The difference between the connection method in Example 4 and Example 1 is that a cylinder with a diameter of 1.5 mm and a height of 1.7 mm is machined on one side surface of the aluminum alloy strip. That is, the height of the first part is 1.2 mm and the height of the second part is 0.5 mm. When the aluminum alloy cylinder is beveled, the bevel depth is 0.4 mm and the vertical section distance in the second part is 0.1 mm.

[0079] The metal workpiece was prepared using the same method as in Example 1.

[0080] Example 5

[0081] The difference between the connection method in Example 5 and Example 1 is that, during the welding process, the connection is offset by 0.25 mm towards the aluminum alloy side.

[0082] The metal workpiece was prepared using the same method as in Example 1.

[0083] Example 6

[0084] The difference between the connection method in Example 6 and Example 1 is that the outer diameter of the helix is ​​0.25 mm. The metal workpiece was prepared using the same method as in Example 1.

[0085] Example 7

[0086] The difference between the connection method in Example 7 and Example 1 is that, during the injection molding process, the plastic is replaced by PBT containing 40% glass fiber with PPS containing 25% glass fiber, and the injection temperature is set to 310°C.

[0087] The metal workpiece was prepared using the same method as in Example 1.

[0088] Example 8

[0089] The difference between the connection method in Example 8 and Example 1 is that, during the injection molding process, the plastic is replaced by polyaryletherketone resin (PAEK) containing 30% glass fiber instead of PBT containing 40% glass fiber. The material temperature is set to 390°C and the mold temperature is set to 210°C during injection molding.

[0090] The metal workpiece was prepared using the same method as in Example 1.

[0091] Example 9

[0092] The difference between the connection method in Example 9 and Example 1 is that the AZ31B magnesium alloy is replaced with the AZ91D magnesium alloy, and the 6013 aluminum alloy is replaced with the 6063 aluminum alloy.

[0093] The metal workpiece was prepared using the same method as in Example 1.

[0094] Example 10

[0095] The difference between the connection method in Example 10 and Example 1 is that in Example 10, the first metal part is AZ31B magnesium alloy, and the second metal part is 6013 aluminum alloy. The connecting part of the first metal part is cylindrical, with a height of 1.7 mm, a first portion height of 1.2 mm, and a second portion height of 0.5 mm. When performing Y-shaped beveling on the magnesium alloy cylinder, the bevel angle is 40°, the bevel depth is 0.4 mm, and the vertical section distance in the second portion is 0.1 mm. A schematic diagram of the first metal part is shown below. Figure 17 As shown.

[0096] The metal workpiece was prepared using the same method as in Example 1.

[0097] Example 11

[0098] The difference between the connection method in Example 11 and Example 10 is that the AZ31B magnesium alloy is replaced with the AZ91D magnesium alloy, and the 6013 aluminum alloy is replaced with the 6063 aluminum alloy.

[0099] The metal workpiece was prepared using the same method as in Example 1. Please refer to... Figure 18 , Figure 18 This is a metallographic image of the weld joint of a cross-section of a metal workpiece provided in Embodiment 11 of this application. Figure 18 There is a weld between the magnesium alloy and the aluminum alloy (marked by the black line).

[0100] Example 12

[0101] The difference between the connection method in Example 12 and Example 10 is that the magnesium alloy cylinder is treated with a V-shaped bevel, the angle of the bevel surface is 55°, and the bevel depth is 0.5mm.

[0102] Welding was performed using the same method as in Example 1, except that during the welding process, the weld was offset 0.35 mm towards the aluminum alloy side. Please refer to [link / reference]. Figure 19 , Figure 19 This is a diagram of the weld points on the surface of a metal workpiece provided in Embodiment 12 of this application. Figure 19 In the middle, the welded part has a weld protrusion that is higher than the surface of the aluminum alloy.

[0103] Example 13

[0104] The difference between the connection method in Example 13 and Example 12 is that a cylinder with a diameter of 1.5 mm and a height of 1.5 mm is machined on one side surface of the magnesium alloy strip, and a V-shaped bevel is made on the magnesium alloy cylinder to form a bevel surface on the top surface of the cylinder with a bevel depth of 0.3 mm.

[0105] The metal workpiece was prepared using the same method as in Example 1.

[0106] Example 14

[0107] The difference between the connection method in Example 14 and Example 1 is that the laser beam does not deflect during the welding process, resulting in a composite metal.

[0108] The metal workpiece was prepared using the same method as in Example 1.

[0109] Comparative Example 1

[0110] The difference between Comparative Example 1 and Example 1 is that the height of the cylinder on the surface of the aluminum alloy specimen is 1.2 mm, that is, the cylinder completely fills the through-hole structure of the magnesium alloy.

[0111] Effect Example

[0112] To verify the nature and effect of the connection method of this application, this application also provides effective examples.

[0113] 1) The composite metal parts (metal parts that have not been injection molded after welding) prepared in Examples 1-14 and Comparative Example 1 were tested for welding strength using a universal testing machine. A schematic diagram of the welding strength testing method is shown below. Figure 20 As shown. The welding strength test method includes: clearing the area below the aluminum alloy position of the weld joint, then applying force to the aluminum alloy side using a special push rod with a contact area smaller than the weld joint diameter. As the push rod continuously moves downwards (at a speed of 5 mm / min), the force continues until the weld joint fails, thus completing the test of the weld joint's mechanical properties. Please refer to [link to relevant documentation]. Figure 21 , Figure 21 This is a welding strength test diagram of the composite metal part according to Embodiment 1 of this application, by... Figure 1 As can be seen, the welding strength of the composite metal part in Example 1 is shown in Table 1 for relevant test results.

[0114] Table 1 Mechanical properties of composite metal parts from Examples 1-14 and Comparative Example 1

[0115]

[0116]

[0117] As can be seen from Table 1, when metal workpieces are welded using the connection method provided in this application, the metal workpieces can have a high bonding strength and the resulting metal workpieces have high structural stability, which is beneficial for their application in consumer electronics, automobiles, intelligent manufacturing and other fields.

[0118] The above description represents the preferred embodiments of this application, but should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. A method for connecting metal parts, characterized in that, include: A first metal part and a second metal part are provided. The first metal part includes a base and a connecting portion disposed on the surface of the base. The connecting portion includes a first part and a second part. The first part is connected to the base, and the second part is connected to the side of the first part away from the base. The second metal part has a first surface, and the first surface is provided with a through hole that mates with the first part. The first metal part includes an aluminum alloy and the second metal part includes a magnesium alloy. The connecting portion of the first metal part is inserted into the through hole of the second metal part in the direction toward the first surface, with the first portion located in the through hole and the second portion protruding from the through hole; the connecting portion and the second metal part are fused together by welding to form a welded part, thereby obtaining a metal workpiece, the welded part including a welding protrusion protruding from the first surface; the first metal part and the second metal part have different melting points, and the welding point of the weld is biased toward the side of the metal part with the higher melting point; the welding includes laser welding; the bias of the welding point is 0.1mm~0.3mm.

2. The connection method as described in claim 1, characterized in that, In the extending direction of the through hole, the height ratio of the second part to the height of the first part is 0.15 to 0.

35.

3. The connection method as described in claim 1 or 2, characterized in that, The second part has a beveled surface on the side away from the first part, and the angle of the beveled surface relative to the interface between the first part and the second part is 20° to 70°.

4. The connection method as described in claim 1 or 2, characterized in that, The connection method further includes: injection molding the welding protrusion to form a plastic body on the surface of the welding protrusion; the plastic body covers the first metal part and the second metal part.

5. The connection method as described in claim 1 or 2, characterized in that, The laser welding speed is 50mm / s to 150mm / s; the laser welding power is 320W to 560W; and the laser welding frequency is 4kHz to 6kHz.

6. The connection method as described in claim 1 or 2, characterized in that, The welding path curve includes one or more of the following: straight line, C-shape, figure-eight shape, and spiral shape.

7. The connection method as described in claim 6, characterized in that, The first part has a cylindrical shape; the welding path curve includes a helical shape, the helical shape includes a spiral line, and the outer circle diameter of the spiral line is less than or equal to the radius of the cylinder.

8. A metal workpiece, characterized in that, It is prepared by the metal part joining method as described in any one of claims 1-7.

9. An electronic device, characterized in that, The electronic device includes the metal workpiece as described in claim 8.

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