Aluminum alloy busbar for busbar duct having double copper-coated end portions, and preparation method therefor
The method of preparing aluminum alloy busbars with double-sided copper plating at the ends, using a copper-aluminum eutectic structure, solves the problems of fracture and corrosion of copper-aluminum composite busbars during long-term use, improves the mechanical properties and connection reliability of the busbars, and reduces costs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- CIXI CHIMA METAL PRODUCTS CO LTD
- Filing Date
- 2025-12-08
- Publication Date
- 2026-04-23
AI Technical Summary
Existing copper-aluminum composite busbars are prone to breakage or cracking during long-term use, and the welded joints are susceptible to corrosion, leading to safety hazards and economic losses. They are also costly, have unreliable connections, and have low peel strength.
A method for preparing aluminum alloy busbars with double-sided copper cladding at the ends is adopted. Through transverse cold rolling and longitudinal cold rolling processes, a copper-aluminum eutectic structure is formed, which reduces the amount of copper used, improves the bonding strength, and reduces the possibility of electrochemical corrosion.
The mechanical properties and oxidation resistance of copper-aluminum composite busbars have been improved, costs have been reduced, connection reliability has been enhanced, and safety hazards and performance issues of existing busbars have been resolved.
Smart Images
Figure CN2025140742_23042026_PF_FP_ABST
Abstract
Description
Aluminum alloy busbar with double-sided copper cladding at both ends and its preparation method Technical Field
[0001] This invention relates to the field of copper-aluminum composite eutectic plate production technology, specifically to a production technology for double-sided copper-aluminum alloy busbars. Background Technology
[0002] Busbars, also known as busbar lines, are metallic conductors, primarily made of highly conductive and corrosion-resistant materials such as copper or aluminum. Their main function is to efficiently transfer electricity from power sources (such as transformers or generators) to various electrical loads. They serve as crucial connection points for electrical equipment, such as circuit breakers, fuses, and switches, and allow for direct installation or connection of these components via bolts, clips, or other methods. Due to the large number of busbars required for large machinery, using pure copper busbars would be prohibitively expensive for most manufacturers. While pure aluminum busbars can reduce costs, they are prone to oxidation during use, and the aluminum-to-aluminum connections at the ends are unreliable, leading to frequent connection problems after prolonged use. Copper-to-copper connections are more reliable. Therefore, various sizes of copper-clad aluminum alloy busbars have been developed for the market, with an aluminum alloy body covered by copper, ensuring reliable connections while reducing costs. Copper-aluminum composite busbars are a new type of bimetallic composite conductor with advantages such as good conductivity, low density and low price. They can replace existing pure copper conductive busbars and can be widely used in building power distribution busbars, high and medium frequency heating equipment, various control cabinets and large busbars in the metallurgical and chemical industries.
[0003] For large and extra-large transformers, generators, or starters, the internal busbar length needs to exceed 3 meters. However, existing casting and rolling processes are limited by the size of the casting rolls, allowing only busbars shorter than 1.75 meters to be produced directly. For ultra-long copper-aluminum composite busbars, welding is the only option to connect two or more smaller busbars together. However, busbars need to carry high currents for extended periods during use. Due to material differences and welding quality at the weld joints, ultra-long copper-aluminum composite busbars may break or crack after prolonged use. This can lead to serious safety hazards and incalculable economic losses. Furthermore, electromagnetic oxidation and corrosion can occur at the weld joints, increasing resistance and significantly reducing the busbar's capacity, even rendering it unusable. Therefore, one-piece molded busbars offer far superior conductivity and mechanical properties compared to welded composite busbars.
[0004] To address this issue, this application designs an aluminum alloy busbar with double-sided copper plating at the ends. Through a new process, its length can reach 3 meters, solving the problem that current equipment cannot produce large-size copper-aluminum eutectic composite materials. Technical issues
[0005] This invention addresses the shortcomings of existing technologies by providing a method for manufacturing aluminum alloy busbars with double-sided copper plating at both ends. Through end copper plating technology, both ends simultaneously possess a copper-aluminum eutectic structure, significantly improving the mechanical properties and oxidation resistance of the copper-aluminum composite busbar, greatly reducing copper usage. Simultaneously, the copper-plated portion exhibits high peel strength, making separation between the copper and aluminum layers less likely, resulting in better performance and improved reliability of the copper-aluminum eutectic busbar. This solves the problems of high cost, unreliable connections in pure aluminum alloy busbars, and low peel strength in copper-aluminum composite busbars in existing systems. Furthermore, transverse cold rolling extends the width of the copper-aluminum eutectic composite plate, overcoming the current equipment's inability to produce large-size copper-aluminum eutectic composite materials. The longitudinal cold rolling process reduces the process seam between copper and aluminum, lowering the possibility of electrochemical corrosion. Technical solutions
[0006] To solve the above-mentioned technical problems, the present invention provides a method for preparing an aluminum alloy busbar with double-sided copper cladding at the ends, comprising the following steps: Step A: Adding raw aluminum ingots to a smelting furnace for smelting and heating to 720℃~750℃ to obtain molten aluminum liquid. The molten aluminum liquid is then poured into a holding furnace, with the temperature controlled at 720~740℃, and held for 20~60 minutes. Step B: Uncoiling copper strips on an uncoiler. The uncoiler has two copper strips on each side, and a sleeve is set in the center of the uncoiler to limit and separate the copper strips on both sides. Step C: After holding for 20 minutes, the molten aluminum liquid is degassed and filtered by online processing equipment such as a degassing box and a filter box. Step D: Four copper strips are wound onto both sides of the upper and lower rolls, with the spacing between the copper strips on the rolls equal to the sleeve width. The copper strips are heated before entering the gap between the upper and lower rolls, with a heating temperature not lower than 50℃. Step E: Molten aluminum at a temperature range of 705℃~715℃ is injected into the gap between the upper and lower rolls through a casting nozzle under static pressure. The injection width is the sum of the width of the copper strips on both sides of the rolls and the spacing between them. Step F: The upper and lower rolls cool the molten aluminum and copper strips and perform solid-liquid casting to form a copper-aluminum composite slab roll with copper cladding on both sides at the ends. Step G: The copper-aluminum composite slab roll is then unwound. The copper-aluminum composite slab is subjected to homogenization annealing in an annealing furnace at a heating temperature of 350℃~450℃ for 15~30h; Step H: The length of the copper-aluminum composite slab is the same as the rolling length of the rolls. After annealing, the copper-aluminum composite slab roll is cut in the width direction according to the final product specifications and subsequent steps; Step I: The movement direction of the copper-aluminum composite slab in the length direction is aligned with the tangential rolling direction of the cold rolling mill rolls. Subsequently, the copper-aluminum composite slab is continuously cold rolled to extend the slab length to the required specifications. The total cold rolling reduction rate is 15%~20%, and the rolling force is not less than 600. ~ 800t; Step J: Make the movement direction of the copper-aluminum composite slab in the width direction consistent with the tangential rolling direction of the cold rolling mill rolls, and then perform cold rolling on the copper-aluminum composite slab at least once until the process gap between the rolled copper and the base aluminum is no greater than 1mm. After rolling, a copper-aluminum composite plate is obtained; Step K: Then the copper-aluminum composite plate is introduced into the slitting equipment and slitting according to the product size to obtain aluminum alloy busbars with double-sided copper cladding at the ends of the required size; Step M: The aluminum alloy busbars with double-sided copper cladding at the ends are straightened and leveled, and then chamfered by a chamfering equipment. After chamfering, they are straightened and leveled again; Step N: The aluminum alloy busbars with double-sided copper cladding at the ends are put back into the annealing furnace for annealing. The heating temperature is 300℃~400℃ and the annealing time is 6~8h.
[0007] In the above technical solution, preferably, in step D, the copper strip is wound onto the rolls from opposite directions in the casting and rolling direction, and each copper strip is equipped with a tension roll and a pressure roll to ensure that the four copper strips move at the same speed and that the copper strips are in close contact with the rolls after entering the hot rolling area.
[0008] In the above technical solution, preferably, in step D, a heating roller that cooperates with the copper strip is located on one side of the casting nozzle, and the heating roller heats the copper strip to between 100°C and 150°C.
[0009] In the above technical solution, preferably, in step D, the copper strip is wound onto the roll in the same direction from the casting and rolling direction, and each copper strip is equipped with a pressing and heating roll. The pressing and heating roll heats the copper strip to between 100°C and 150°C and allows the copper strip to be tightly bonded to the roll after entering the casting and rolling area.
[0010] In the above technical solution, preferably, in step F, the cooling rate is 300℃ / s to 1000℃ / s.
[0011] In the above technical solutions, the preferred method is to perform rolling and cooling only within the solid-liquid casting and rolling zone.
[0012] A type of aluminum alloy busbar for busbar trunking with double-sided copper plating at both ends is manufactured by a method for preparing aluminum alloy busbars for busbar trunking with double-sided copper plating at both ends. The total thickness does not exceed 7mm, the copper plating thickness on one side is 5% to 35% of the total thickness, the length of a single busbar is <3.25m, and the copper plating length at both ends accounts for 5% to 15% of the total length.
[0013] In the above technical solution, preferably, the peel strength of the copper-aluminum eutectic composite part is between 30 MPa and 85 MPa, the shear strength is greater than 50 MPa, and the composite rate is 100%.
[0014] In the above technical solutions, preferably, the overall conductivity of the aluminum alloy busbar is greater than 60%, and the tensile strength is greater than 150 MPa.
[0015] This application primarily manufactures copper-plated aluminum alloy busbars with lengths of 3m and above. Compared to existing technologies, this application has two substantial features: First, the end-copper plating technology significantly reduces copper usage compared to existing double-sided copper-plated busbars without compromising conductivity for the same size. Second, the large-size production technology demonstrates superior conductivity and mechanical properties compared to existing welded composite busbars.
[0016] Therefore, the technical solution of this application overcomes several technical difficulties. When copper is clad on both sides or one side, the casting nozzle only needs to statically inject molten aluminum onto the copper plate or between two copper plates. The width of the injection is uniform, and continuous hot rolling production can be achieved as long as the copper plate conveying speed, hot rolling speed, and injection speed are constant. However, this application is completely different. Copper is clad on both the top and bottom ends, meaning there is no copper plate in the middle. This means that molten aluminum actually overflows from both ends during the aluminum injection process. If the copper strip is not tightly attached to the rolls, especially the copper strip on the upper roll, the molten aluminum will overflow onto the copper strip that has not entered the rolls. At the same time, a total of four copper strips are required on both ends, and the speed of these four copper strips must be consistent. Otherwise, if the speed of even one copper strip is inconsistent, serious quality problems will occur. Therefore, it is necessary to tightly attach the copper strip to the rolls, leave space for the molten aluminum, and synchronize the winding speed of the four copper strips. For this reason, this application requires an additional pressing roller to press the copper strip tightly onto the rolls.
[0017] This application presents a copper strip as a copper-aluminum eutectic busbar. During the hot rolling of copper and aluminum on the rolls, a cooling device is installed within the rolls to cool the copper-aluminum alloy. This cooling helps form smaller grains, increasing material strength. If the copper temperature is between 150℃ and 220℃ during hot rolling, copper atoms can acquire sufficient energy for migration in a short time at this high temperature, forming a thicker copper-aluminum eutectic layer, thus effectively improving the bonding strength of the copper-aluminum composite interface. However, as mentioned above, the copper strip needs to be tightly adhered to the rolls. Since the rolls have a cooling device, if the copper strip is preheated before passing through the rolls, it will have lost temperature before entering the hot rolling zone. Therefore, the copper strip needs to be heated before entering the hot rolling zone. This application provides two structures: one for pressing and heating the copper strip when it enters the hot rolling zone in the forward direction, and another for pressing and heating the copper strip when it enters the hot rolling zone in the reverse direction. By replacing the copper plate with copper strip, creating a gap between the two copper strips, the impact of the copper strip's entry and exit on the casting nozzle and billet is greatly reduced.
[0018] This application requires improvements to the cooling system of the rolls. Previously, the cooling system of the rolls was uniformly distributed within the rolls, meaning the cooling rate across the roll surface was consistent. However, this application requires the copper strip to be heated before hot rolling. Therefore, the cooling system of the rolls needs to be improved to maximize the cooling rate in the hot rolling zone while reducing the cooling capacity in other areas, thus maximizing the heat preservation of the copper strip.
[0019] This application mainly extends a billet from 1.6m to 1.75m to over 2.8m by cold rolling. However, since this application does not cover the entire surface with copper, after cold rolling in the length direction, a seam will appear at the copper-aluminum contact point on the billet surface. The appearance of the seam seriously affects the performance of the busbar and will cause electrochemical corrosion after long-term use. Therefore, this application also needs to perform cold rolling in the width direction after cold rolling in the length direction to minimize the seam as much as possible.
[0020] This application requires secondary annealing after cold rolling. Due to the internal stress present during rolling, the strength of the composite material will decrease. Therefore, the annealing process can reduce residual stress, stabilize dimensions, reduce deformation and cracking tendency, and ensure that the product has good comprehensive mechanical properties and good metallurgical bonding. Beneficial effects
[0021] Compared with existing technologies, this application designs an aluminum alloy busbar with double-sided copper plating at both ends. Through end copper plating technology, both ends simultaneously possess a copper-aluminum eutectic structure, significantly improving the mechanical properties and oxidation resistance of the copper-aluminum composite busbar, greatly reducing copper usage. Simultaneously, the copper-plated portion exhibits high peel strength, making separation between the copper and aluminum layers less likely, resulting in better performance and improved reliability of the copper-aluminum eutectic busbar. This solves the problems of high cost, unreliable connections in pure aluminum alloy busbars, and low peel strength in copper-aluminum composite busbars found in existing busbars. By using transverse cold rolling to extend the width of the copper-aluminum eutectic composite plate, the current equipment cannot produce large-size copper-aluminum eutectic composite materials. The longitudinal cold rolling process reduces the process seam between copper and aluminum, lowering the possibility of electrochemical corrosion. Attached Figure Description
[0022] Figure 1 is a structural diagram of the double-sided copper-aluminum composite busbar at the end of this application. Embodiments of the present invention
[0023] The technical solutions of various embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0024] As shown in Figure 1, the double-sided copper-aluminum alloy busbar of this application includes a copper cladding 2 and a base aluminum alloy 1 located on the upper and lower sides of the end.
[0025] Example 1: Production of 3m long, 6mm thick double-sided copper-clad aluminum busbars, with each copper piece 20cm long and 1.5mm thick. The process includes the following steps: Step A: Adding raw aluminum ingots to a smelting furnace for melting, heating to 720℃~750℃ to obtain molten aluminum; pouring the molten aluminum into a holding furnace, controlling the temperature at 720~740℃, and holding for 20~60 minutes; the raw aluminum ingots are of grades 1G20, 1050, 1060, and 1100, with an aluminum content greater than 99.2% and a thickness of 16mm.
[0026] Step B: The copper strip is uncoiled on an uncoiler. Two strips are placed on each side of the uncoiler, and a sleeve in the center of the uncoiler separates the two strips. The copper strip is T2 copper or brass, with a thickness of 4mm. Before uncoiling, the copper strip undergoes high-pressure rinsing to quickly remove solid impurities from the copper plate surface. It is then rinsed under low pressure with a 50℃ alkaline degreasing solution to remove grease from the copper plate surface. Finally, the oxide layer on the copper plate surface is polished off using a steel brush. Polishing also increases the roughness of the copper strip surface, increases the copper-aluminum composite area, and thus enhances the adhesion of the composite material.
[0027] Step C: After being kept at a constant temperature and allowed to settle, the molten aluminum is degassed and filtered through online processing equipment such as a degassing box and a filtration box. The rolls in the twin-roll casting and rolling mill have a cooling function; ideally, the rolls should only be cooled within the hot rolling zone, and not outside of it, to facilitate the insulation of the copper strip.
[0028] Step D: Four copper strips are wound onto the rolls from opposite directions of the injection nozzle. Each strip is equipped with a tension roll and a pressure roll. The speed of the copper strips is adjusted by the tension roll and the pressure roll to ensure that the winding speed of the four strips is consistent. The pressure roll ensures that the copper strips are tightly adhered to the rolls when they enter the hot rolling zone. A heating roll is also located on one side of the nozzle; typically, one heating roll is provided for each copper strip. The heating roll is close to the hot rolling zone and heats the copper strip to 150°C.
[0029] Step E: Molten aluminum at a temperature of 710℃ is injected into the gap between the upper and lower rolls through a casting nozzle. The injection width is the sum of the width of the copper strips on both sides of the rolls and the distance between them. Step F: The upper and lower rolls cool the molten aluminum and copper strips and perform solid-liquid casting to form a copper-aluminum composite slab coil with copper cladding on both ends. Simultaneously, the upper and lower rolls cool the copper-aluminum composite slab. The cooling rate is 300℃ / s. The coolant inside the upper and lower rolls is water, which is maintained at a temperature of 20℃ within the rolls. When the molten aluminum is injected through the casting nozzle, it cools and solidifies rapidly upon contact with the rolls. Similarly, it cools rapidly upon contact with the copper strips. The molten aluminum and the upper and lower copper strips crystallize in the casting zone, and the heat is carried away by the circulating cooling water within the rolls.
[0030] Step G: Place the copper-aluminum composite slab into an annealing furnace for homogenization annealing at a heating temperature of 400℃ for 15 hours.
[0031] Step H: The length of the copper-aluminum composite slab is the rolling length of the rolls. After annealing, the copper-aluminum composite slab is cut in the width direction according to the final product specifications and the requirements of subsequent steps. Step I: The movement direction of the copper-aluminum composite slab in the length direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then continuously cold rolled to extend the slab length to the required specifications. The total cold rolling reduction rate is 20%, and the rolling force is not less than 600t. Step J: The movement direction of the copper-aluminum composite slab in the width direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then cold rolled at least once until the process seam between the rolled copper cladding and the base aluminum is no greater than 1mm. After rolling, a copper-aluminum composite plate is obtained.
[0032] Step K: The copper-aluminum composite plate is then introduced into the slitting equipment and slitted according to the product dimensions to obtain copper-aluminum eutectic transition busbars of the required size. Step M: The copper-aluminum eutectic transition busbars are straightened and leveled, then chamfered using a chamfering device. After chamfering, they are straightened and leveled again. Step N: The copper-aluminum eutectic transition busbars are placed back into the annealing furnace for annealing at a heating temperature of 350℃ for 6 hours.
[0033] Example 2: Production of 2.8m long, 7mm thick double-sided copper-clad aluminum busbars, with each copper piece 15cm long and 1mm thick. The process includes the following steps: Step A: Adding raw aluminum ingots to a smelting furnace for melting, heating to 720℃~750℃ to obtain molten aluminum; pouring the molten aluminum into a holding furnace, controlling the temperature at 720~740℃, and holding for 20~60 minutes; the raw aluminum ingots are of grades 1G20, 1050, 1060, and 1100, with an aluminum content greater than 99.2% and a thickness of 16mm.
[0034] Step B: The copper strip is uncoiled on an uncoiler. Two strips are placed on each side of the uncoiler, and a sleeve in the center of the uncoiler separates the two strips. The copper strip is T2 copper or brass, with a thickness of 3.5mm. Before uncoiling, the copper strip undergoes high-pressure rinsing to quickly remove solid impurities from the copper plate surface. It is then rinsed under low pressure with a 70℃ alkaline degreasing solution to remove grease from the copper plate surface. Finally, the oxide layer on the copper plate surface is polished off using a steel brush. Polishing also increases the roughness of the copper strip surface, increases the copper-aluminum composite area, and thus enhances the adhesion of the composite material.
[0035] Step C: After being kept at a constant temperature and allowed to settle, the molten aluminum is degassed and filtered through online processing equipment such as a degassing box and a filtration box. The rolls in the twin-roll casting and rolling mill have a cooling function; ideally, the rolls should only be cooled within the hot rolling zone, and not outside of it, to facilitate the insulation of the copper strip.
[0036] Step D: The four copper strips are wound onto the rolls in the same direction from the injection direction of the casting nozzle. Each copper strip is equipped with a pressing and heating roller. The pressing and heating roller heats the copper strip to 150°C and allows the copper strip to fit tightly against the rolls after entering the hot rolling area, while ensuring that the four copper strips are wound onto the rolls at the same speed.
[0037] Step E: Molten aluminum at a temperature of 710℃ is injected into the gap between the upper and lower rolls through a casting nozzle. The injection width is the sum of the width of the copper strips on both sides of the rolls and the distance between them. Step F: The upper and lower rolls cool the molten aluminum and copper strips and perform solid-liquid casting to form a copper-aluminum composite slab coil with copper cladding on both ends. Simultaneously, the upper and lower rolls cool the copper-aluminum composite slab. The cooling rate is 300℃ / s. The coolant inside the upper and lower rolls is water, which is maintained at a temperature of 20℃ within the rolls. When the molten aluminum is injected through the casting nozzle, it cools and solidifies rapidly upon contact with the rolls. Similarly, it cools rapidly upon contact with the copper strips. The molten aluminum and the upper and lower copper strips crystallize in the casting zone, and the heat is carried away by the circulating cooling water within the rolls.
[0038] Step G: Place the copper-aluminum composite slab into an annealing furnace for homogenization annealing at a heating temperature of 430℃ for 30 hours.
[0039] Step H: The length of the copper-aluminum composite slab is the same as the rolling length of the rolls. After annealing, the copper-aluminum composite slab is cut in the width direction according to the final product specifications and the requirements of subsequent steps. Step I: The movement direction of the copper-aluminum composite slab in the length direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then continuously cold rolled to extend its length to the required specifications. The total cold rolling reduction rate is 15%, and the rolling force is not less than 700t. Step J: The movement direction of the copper-aluminum composite slab in the width direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then cold rolled at least once until the process seam between the rolled copper cladding and the base aluminum is no greater than 1mm. After rolling, a copper-aluminum composite plate is obtained.
[0040] Step K: The copper-aluminum composite plate is then introduced into the slitting equipment and slitted according to the product dimensions to obtain copper-aluminum eutectic transition busbars of the required size. Step M: The copper-aluminum eutectic transition busbars are straightened and leveled, then chamfered using a chamfering device. After chamfering, they are straightened and leveled again. Step N: The copper-aluminum eutectic transition busbars are placed back into the annealing furnace for annealing at a heating temperature of 350℃ for 7 hours.
[0041] Example 3: Production of 3.2m long, 6mm thick double-sided copper-clad aluminum busbars, with each copper piece 25cm long and 1.5mm thick. The process includes the following steps: Step A: Adding raw aluminum ingots to a smelting furnace for melting, heating to 720℃~750℃ to obtain molten aluminum; pouring the molten aluminum into a holding furnace, controlling the temperature at 720~740℃, and holding for 20~60 minutes; the raw aluminum ingots are of grades 1G20, 1050, 1060, and 1100, with an aluminum content greater than 99.2% and a thickness of 16mm.
[0042] Step B: The copper strip is uncoiled on an uncoiler. Two strips are placed on each side of the uncoiler, and a sleeve in the center of the uncoiler separates the two strips. The copper strip is T2 copper or brass, with a thickness of 2mm. Before uncoiling, the copper strip undergoes high-pressure rinsing to quickly remove solid impurities from the copper plate surface. It is then rinsed under low pressure with a 70℃ alkaline degreasing solution to remove grease from the copper plate surface. Finally, the oxide layer on the copper plate surface is polished off using a steel brush. Polishing also increases the roughness of the copper strip surface, increases the copper-aluminum composite area, and thus enhances the adhesion of the composite material.
[0043] Step C: After being kept at a constant temperature and allowed to settle, the molten aluminum is degassed and filtered through online processing equipment such as a degassing box and a filtration box. The rolls in the twin-roll casting and rolling mill have a cooling function; ideally, the rolls should only be cooled within the hot rolling zone, and not outside of it, to facilitate the insulation of the copper strip.
[0044] Step D: Two of the four copper strips, covering the aluminum alloy, are wound onto the upper rolls from opposite directions of the injection direction from the casting nozzle. Both strips are equipped with tension rollers and pressure rollers. The tension rollers and pressure rollers adjust the strip speed, while the pressure rollers ensure the strips adhere tightly to the rolls when entering the hot rolling zone. A heating roller is also located on one side of the casting nozzle; typically, one heating roller is provided for each copper strip. The heating rollers are close to the hot rolling zone and heat the copper strips to 150°C. The other two copper strips, covering the aluminum alloy, are wound onto the upper rolls from the same direction of the injection direction from the casting nozzle. Each strip is equipped with a pressure heating roller. The pressure heating rollers heat the strips to 150°C and ensure tight adhesion to the rolls after the strips enter the hot rolling zone, while maintaining a consistent winding speed for all four strips.
[0045] Step E: Molten aluminum at a temperature of 710℃ is injected into the gap between the upper and lower rolls through a casting nozzle. The injection width is the sum of the width of the copper strips on both sides of the rolls and the distance between them. Step F: The upper and lower rolls cool the molten aluminum and copper strips and perform solid-liquid casting to form a copper-aluminum composite slab coil with copper cladding on both ends. Simultaneously, the upper and lower rolls cool the copper-aluminum composite slab. The cooling rate is 300℃ / s. The coolant inside the upper and lower rolls is water, which is maintained at a temperature of 20℃ within the rolls. When the molten aluminum is injected through the casting nozzle, it cools and solidifies rapidly upon contact with the rolls. Similarly, it cools rapidly upon contact with the copper strips. The molten aluminum and the upper and lower copper strips crystallize in the casting zone, and the heat is carried away by the circulating cooling water within the rolls.
[0046] Step G: Place the copper-aluminum composite slab into an annealing furnace for homogenization annealing at a heating temperature of 450℃ for 630 hours.
[0047] Step H: The length of the copper-aluminum composite slab is the same as the rolling length of the rolls. After annealing, the copper-aluminum composite slab is cut in the width direction according to the final product specifications and the requirements of subsequent steps. Step I: The movement direction of the copper-aluminum composite slab in the length direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then continuously cold rolled to extend its length to the required specifications. The total cold rolling reduction rate is 20%, and the rolling force is 800t. Step J: The movement direction of the copper-aluminum composite slab in the width direction is aligned with the tangential rolling direction of the cold rolling mill rolls. The copper-aluminum composite slab is then cold rolled at least once until the process seam between the rolled copper cladding and the base aluminum is no greater than 1mm. After rolling, a copper-aluminum composite plate is obtained.
[0048] Step K: The copper-aluminum composite plate is then introduced into the slitting equipment and slitted according to the product dimensions to obtain copper-aluminum eutectic transition busbars of the required size. Step M: The copper-aluminum eutectic transition busbars are straightened and leveled, then chamfered using a chamfering device. After chamfering, they are straightened and leveled again. Step N: The copper-aluminum eutectic transition busbars are placed back into the annealing furnace for annealing at 350℃ for 6–8 hours.
[0049] The copper-aluminum eutectic layer compounds in Examples 1 to 3 above include Al2Cu and Al4Cu9, and the interface layer thickness of the eutectic layer is 300nm-500nm. The conventional shear strength of the eutectic composite material is greater than 50MPa, the conventional peel strength is 30MPa-85MPa, the conductivity of the aluminum alloy busbar is >60%, and the tensile strength is >150MPa. Industrial applicability
[0050] This application provides an aluminum alloy busbar with double-sided copper plating at both ends, which is used for busbars and has industrial applicability.
Claims
1. An aluminum alloy busbar for a bus duct with double-sided copper clad end portions, the main body being an aluminum alloy, characterized in that, The aluminum alloy has copper plating on both the top and bottom ends. The length of a single busbar is no more than 3.25m. The copper plating length at both ends accounts for 5% to 15% of the total length, and the copper plating thickness on one side is 5% to 35% of the total thickness.
2. The aluminum alloy busbar for the end double-sided copper-clad bus duct according to claim 1, characterized by, The peel strength of the copper-aluminum eutectic composite is between 30 MPa and 85 MPa, the shear strength is greater than 50 MPa, and the composite rate is 100%.
3. The aluminum alloy busbar for the end double-sided copper-clad bus duct according to claim 1, characterized by, The tensile strength of the aluminum alloy busbar is greater than 150 MPa.
4. A method of producing an aluminum alloy busbar for a double-sided copper-clad bus duct according to claim 1, characterized by, It includes the following steps: Step A: Add the raw aluminum ingots to the smelting furnace for smelting and heat to 720℃~750℃ to obtain molten aluminum liquid. Pour the molten aluminum liquid into the holding furnace, control the temperature at 720~740℃, and hold for 20~60 minutes. Step B: The copper strip is uncoiled on the uncoiler. There are two copper strips on the uncoiler, one on each side of the uncoiler. A sleeve is set in the center of the uncoiler to limit and separate the copper strips on both sides. Step C: After being kept at a constant temperature, the molten aluminum is degassed and filtered by online processing equipment such as a degassing box and a filter box; Step D: Four copper strips are wound onto both sides of the upper and lower rollers respectively, with the spacing between the copper strips on the rollers being the width of the sleeve. Step E: The aluminum liquid, which is in the temperature range of 705℃~715℃, is injected into the gap between the upper and lower rolls under static pressure through the casting nozzle. The injection width is the sum of the width of the copper strip on both sides of the roll and the distance between them. Step F: The upper and lower rolls cool the molten aluminum liquid and copper strip and perform solid-liquid casting and rolling to form a copper-aluminum composite slab coil with copper cladding on both ends. Step G: Place the copper-aluminum composite slab roll into an annealing furnace for homogenization annealing. The heating temperature is 350℃~450℃ and the annealing time is 15 h~30 h. Step H: The length of the copper-aluminum composite slab is the rolling length of the roll. After annealing, the copper-aluminum composite slab roll is cut in the width direction according to the final product specifications and the requirements of subsequent steps. Step I: Make the direction of movement of the copper-aluminum composite slab in the length direction consistent with the tangential rolling direction of the cold rolling mill rolls, and then continuously cold roll the copper-aluminum composite slab to extend the slab length to the required specifications. The total cold rolling reduction rate is 15% to 20%, and the rolling force is not less than 600 t to 800 t. Step J: Align the movement direction of the copper-aluminum composite slab in the width direction with the tangential rolling direction of the cold rolling mill rolls, and then perform at least one cold rolling operation on the copper-aluminum composite slab until the process gap between the rolled copper cladding and the base aluminum is no greater than [missing value]. 1mm, after rolling, a copper-aluminum composite plate is obtained; Step K: The copper-aluminum composite plate is then introduced into the slitting equipment and slitted according to the product size to obtain aluminum alloy busbars with double-sided copper coating at the ends of the required size; Step M: Straighten and level the aluminum alloy busbar with double-sided copper plating at the ends, then chamfer it using a chamfering machine, and straighten and level it again after chamfering. Step N: Place the aluminum alloy busbar with double-sided copper plating at the ends back into the annealing furnace for annealing. The heating temperature is 300℃~400℃ and the annealing time is 6 h~8 h.
5. The method of claim 4, wherein the step of preparing the aluminum alloy busbar for a double-sided copper-clad bus duct is characterized by In step D, the copper strip is wound onto the rolls from opposite directions in the casting and rolling direction, and each copper strip is equipped with a tension roll and a pressure roll. Ensure that the four copper strips move at the same speed and that the copper strips fit tightly against the rolls after entering the hot rolling zone.
6. The method of claim 4, wherein the method is characterized by: In step D, the side of the casting nozzle also has a heating roller matched with the copper strip, which heats the copper strip to 100℃-150℃. In step D, the copper strip is coiled on the roller from the casting direction, and each copper strip is matched with a pressing heating roller, which heats the copper strip to 100℃-150℃ and makes the copper strip closely contact with the roller after entering the casting area.
7. The method of claim 4, wherein the step of preparing the aluminum alloy busbar for a double-sided copper-clad bus duct is characterized by In step F, the cooling rate is 300℃ / s-1000℃ / s.
8. The method of claim 4, wherein the method is characterized by: Only rolling and cooling are performed in the solid-liquid casting area.
9. A method of producing an aluminum alloy busbar for a double-sided copper-clad bus duct according to any one of claims 4 to 8, characterized by,