Aluminum alloy busbar having copper-coated end portions, and preparation method therefor

Abstract

Disclosed are an aluminum alloy busbar having copper-coated end portions, and a preparation method therefor, relating to the technical field of copper-aluminum composite eutectic plate production. An aluminum alloy busbar having double or single copper-coated end portions is produced by means of casting, heat treating and slitting steps. Compared with the prior art, an aluminum alloy busbar having double copper-coated or single copper-coated end portions is designed, and the end portion copper coating technique enables both ends to have a copper-aluminum eutectic structure at the same time, thereby significantly improving the mechanical properties and oxidation resistance of the copper-aluminum composite busbar, and significantly reducing the amount of copper. In addition, the peel strength of the copper-coated parts is high, the aluminum layer and the copper layer are not easily separated, and the performance is better, thereby improving the reliability of the copper-aluminum eutectic busbar, and solving the problems that existing busbars are high in cost, pure aluminum alloy busbar connections are unreliable, and copper-aluminum composite busbars have low peel strength.

Description

A copper-clad aluminum alloy busbar with end caps 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 copper-aluminum alloy busbars with double-sided or single-sided end cladding. 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, and can replace existing pure copper conductive busbars.

[0003] However, the amount of copper used in copper-clad aluminum alloy busbars is still relatively high. Although the overall cost has been reduced, the price is still high. Therefore, this application designs an aluminum alloy busbar with copper cladding only on both sides or one side at the ends. Technical issues

[0004] This invention addresses the shortcomings of existing technologies by providing a copper-clad aluminum alloy busbar and its preparation method. This application designs an aluminum alloy busbar with double-sided or single-sided copper cladding at both ends. Through end copper cladding 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 the amount of copper used. Simultaneously, the copper-clad portion exhibits high peel strength, and the copper and aluminum layers are not easily separated, resulting in better performance and improved reliability of the copper-aluminum eutectic busbar. This solves the problems of high cost, unreliable connection of pure aluminum alloy busbars, and low peel strength of copper-aluminum composite busbars in existing systems. Technical solutions

[0005] To solve the above-mentioned technical problems, the present invention provides a method for preparing copper-clad aluminum alloy busbars, comprising the following steps: Step A: Adding raw aluminum ingots to a smelting furnace for smelting to obtain molten aluminum liquid; Step B: Uncoiling copper strips on an uncoiler, with two copper strips on each side of the uncoiler, and a replaceable sleeve in the center of the uncoiler to limit and separate the copper strips on both sides, the distance between the copper strips being the sleeve width; Step C: After being kept at a constant temperature and allowed to settle, the molten aluminum liquid is degassed and filtered through online processing equipment such as a degassing box and a filter box; Step D: Four copper strips are respectively attached in pairs to both sides of the upper and lower rollers, with the interval between the copper strips on the rollers being the sleeve width, and the copper strips are heated before entering the gap between the upper and lower rollers; or Step D is modified. Step D1: Two copper strips are wound around both sides of the lower roll, with the spacing between the copper strips on the lower roll being the width of the sleeve. The copper strips are heated before entering the gap between the upper and lower rolls. Step E: Molten aluminum at a temperature range of 705℃~715℃ is injected into the gap between the upper and lower rolls under static pressure through a casting nozzle. The injection width is the sum of the width of the copper strips on both sides of the roll and the distance between them. The gap between the upper and lower rolls is the solid-liquid casting area. 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-coated ends. Step G: The copper-aluminum composite slab roll is placed in an annealing furnace for homogenization annealing. Step H: The copper-aluminum composite slab roll is then introduced into a slitting device and slitted according to the product size to obtain the required size of the copper-coated aluminum alloy busbar.

[0006] In the above technical solution, preferably, step I is further included: straightening and leveling the copper-plated aluminum alloy busbar at the end, then chamfering it using a chamfering device, and then straightening and leveling it again after the chamfering is completed.

[0007] In the above technical solution, preferably, in step D or D1, the copper strip is wound onto the rolls from opposite directions in the casting and rolling direction. At the same time, each copper strip is equipped with a tension roll and a pressure roll to ensure that the copper strip moves at a consistent speed and that the copper strip is in close contact with the rolls after entering the solid-liquid casting and rolling area. A heating roll that cooperates with the copper strip is also located on one side of the casting nozzle. The heating roll heats the copper strip to between 100°C and 150°C.

[0008] In the above technical solution, preferably, in step D or D1, 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 enter the solid-liquid casting and rolling area and fit tightly against the roll.

[0009] In the above technical solution, preferably, in step A, the aluminum liquid is heated to 720℃~750℃ to obtain a molten aluminum liquid.

[0010] In the above technical solution, preferably, in step C, the aluminum liquid is kept at a temperature of 720℃~740℃ in a holding furnace, and then left to stand for 20 min~60 min.

[0011] In the above technical solution, preferably, in step F, the cooling rate is 300℃ / s to 1000℃ / s.

[0012] In the above technical solution, preferably, in step G, the annealing temperature is 350℃~450℃ and the annealing time is 15 h~30 h.

[0013] In the above technical solution, preferably, after casting and rolling in step F, the copper-aluminum composite slab roll is cold-rolled to the required thickness as needed.

[0014] In the above technical solutions, the preferred method is to perform rolling and cooling only within the solid-liquid casting and rolling zone.

[0015] A copper-clad aluminum alloy busbar is characterized in that it is a double-sided copper-clad aluminum alloy busbar or a single-sided copper-clad aluminum alloy busbar manufactured by a method for preparing copper-clad aluminum alloy busbars.

[0016] When copper is clad on both sides or only one side, the casting nozzle only needs to statically inject molten aluminum onto the copper plate or between two copper plates. The entire injection width 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. This application involves copper cladding on both the top and bottom sides of the end or copper cladding on only one side of the end, meaning there is no copper plate in the middle. During the aluminum injection process, molten aluminum actually overflows from both ends. Therefore, it is necessary to tightly adhere the copper strip to the rolls, leaving space for the molten aluminum and synchronizing the winding speed of the copper strip. For this reason, this application requires additional pressure rollers to press the copper strip tightly onto the rolls.

[0017] This application describes a copper strip as a copper-aluminum eutectic busbar. During the hot rolling of copper and aluminum, the rolls contain a cooling device to cool the copper-aluminum alloy. This cooling helps form smaller grains, increasing material strength. If the copper temperature is between 150°C and 220°C during hot rolling, copper atoms can quickly acquire sufficient energy to migrate at this high temperature, forming a thicker copper-aluminum eutectic layer, thus effectively improving the bonding strength of the copper-aluminum composite interface. However, the copper strip needs to be tightly bonded to the rolls. Since the rolls contain a cooling device, if the copper strip is preheated before passing through the rolls, it will have already lost temperature before entering the solid-liquid casting zone. Therefore, the copper strip needs to be heated before entering the solid-liquid casting zone. This application provides two structures: one for pressing and heating the copper strip as it enters the solid-liquid casting zone in the forward direction, and the other for pressing and heating the copper strip as it enters the solid-liquid casting zone in the reverse direction. By changing from copper plates to copper strips in existing technology, with gaps between the two copper strips, the entry and exit of the copper strips greatly reduces the impact on the casting nozzle and billet.

[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 solid-liquid casting and rolling zone, while reducing the cooling capacity in other areas, thus maximizing the heat preservation of the copper strip. Beneficial effects

[0019] Compared with existing technologies, this application designs an aluminum alloy busbar with double-sided or single-sided copper plating at both ends. Through end copper plating technology, it has a copper-aluminum eutectic structure at both ends, which greatly improves the mechanical properties and oxidation resistance of the copper-aluminum composite busbar, significantly reduces the amount of copper used, and has high peel strength of the copper-plated part, making it difficult for the copper and aluminum layers to separate, resulting in better performance and improved reliability of the copper-aluminum eutectic busbar. This solves the problems of high cost of existing busbars, unreliable connection of pure aluminum alloy busbars, and low peel strength of copper-aluminum composite busbars. Embodiments of the present invention

[0020] 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.

[0021] Example 1: Producing a 1.5m long, 8mm thick double-sided copper-clad aluminum busbar with copper cladding on both ends, meaning there are four copper surfaces at both ends. Each copper sheet is 10cm long and 1.5mm thick.

[0022] The process 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; the raw aluminum ingots are aluminum materials of type 1G20, 1050, 1060, and 1100, with an aluminum content greater than 99.2%.

[0023] 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 either T2 copper or brass. 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°C 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.

[0024] Step C: After the aluminum liquid has been kept at a constant temperature of 720℃~740℃, it is held for 20 min~60 min. It is then degassed and filtered using online processing equipment such as a degassing box and a filter box. The rolls in the twin-roll casting and rolling equipment have a cooling function; ideally, the rolls should only be cooled within the solid-liquid casting and rolling area, and not outside this area, which is beneficial for the insulation of the copper strip.

[0025] 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 solid-liquid casting area. A heating roll is also located on one side of the nozzle, typically one heating roll per copper strip. The heating roll is close to the solid-liquid casting area and heats the copper strip to 150°C.

[0026] 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 solidify them through casting and rolling 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 coil. 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 and rolling zone, and the heat is carried away by the cooling water circulating in the rolls. After casting and rolling, the copper-aluminum composite slab coil can be cold-rolled to the required thickness as needed.

[0027] Step G: Place the copper-aluminum composite slab into an annealing furnace for homogenization annealing at a heating temperature of 400℃ for 15 hours.

[0028] Step H: The copper-aluminum composite plate is then introduced into the slitting equipment. Before slitting, it can be divided into sections to reduce the difficulty of slitting. Slitting is performed according to the product size to obtain the required size copper-aluminum eutectic transition busbar. Step I: The copper-aluminum eutectic transition busbar is straightened and leveled, and then chamfered using a chamfering equipment. After chamfering, it is straightened and leveled again.

[0029] Example 2: Producing a 1.5m long, 10mm thick, single-sided copper-clad aluminum busbar with copper cladding on one end. The end faces are single-sided copper clad, meaning there are two copper surfaces at both ends, both on the same side. Each copper sheet is 10cm long and 2mm thick.

[0030] The process 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; the raw aluminum ingots are aluminum materials of type 1G20, 1050, 1060, and 1100, with an aluminum content greater than 99.2%.

[0031] 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 either T2 copper or brass. 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°C 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.

[0032] Step C: After the aluminum liquid has been held at a constant temperature, pour the molten aluminum liquid into a holding furnace, control the temperature at 720℃~740℃, and hold it for 20 min~60 min. Then, pass it through online processing equipment such as a degassing box and a filtration box for degassing and filtration. The rolls in the twin-roll casting and rolling equipment have a cooling function; ideally, the rolls should only be cooled within the solid-liquid casting and rolling area, and not outside this area, which is beneficial for the insulation of the copper strip.

[0033] Step D: The two 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 enter the solid-liquid casting and rolling area and fit tightly against the rolls. At the same time, it ensures that the two copper strips are wound onto the rolls at the same speed.

[0034] 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 solidify them through casting and rolling 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 coil. 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 and rolling zone, and the heat is carried away by the cooling water circulating in the rolls. After casting and rolling, the copper-aluminum composite slab coil can be cold-rolled to the required thickness as needed.

[0035] Step G: Place the copper-aluminum composite slab into an annealing furnace for homogenization annealing at a heating temperature of 400℃ for 15 hours.

[0036] Step H: The copper-aluminum composite plate is then introduced into the slitting equipment. Before slitting, it can be divided into sections to reduce the difficulty of slitting. Slitting is performed according to the product size to obtain the required size copper-aluminum eutectic transition busbar. Step I: The copper-aluminum eutectic transition busbar is straightened and leveled, and then chamfered using a chamfering equipment. After chamfering, it is straightened and leveled again.

[0037] The mechanical and electrical properties of the busbars produced in Examples 1 and 2 vary significantly depending on the type of aluminum alloy.

[0038] At 25℃ and 68% humidity, the tensile strength is ≥150MPa, the elongation is around 14.0%, and the conductivity varies depending on the aluminum alloy type. Industrial applicability

[0039] This application provides an aluminum alloy busbar with double-sided or single-sided copper cladding at the ends, which is used for busbars and has industrial applicability.

Claims

1. A method of making an end-copper clad aluminum alloy busbar, characterized by, It includes the following steps: Step A: Add the raw aluminum ingots to the smelting furnace for smelting to obtain molten aluminum liquid; 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 replaceable sleeve is set in the center of the uncoiler to limit and separate the copper strips on both sides. The distance between the copper strips is the width of the sleeve. Step C: After being kept at a constant temperature and allowed to stand, the molten aluminum is degassed and filtered by online processing equipment such as a degassing box and a filtration box. Step D: The four copper strips are placed in pairs on both sides of the upper and lower rolls, with the spacing between the copper strips on the rolls being the width of the sleeve. The copper strips are heated before entering the gap between the upper and lower rolls. Alternatively, step D can be changed to step D1: Two copper strips are wound around the two sides of the lower roll respectively, with the copper strips on the lower roll spaced apart by the width of the sleeve, and the copper strips are heated before entering the gap between the upper and lower rolls; 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. The gap between the upper and lower rolls is the solid-liquid casting and rolling area. 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-coated ends. Step G: Place the copper-aluminum composite slab roll into an annealing furnace for homogenization annealing; Step H: The copper-aluminum composite slab is then introduced into the slitting equipment and slitted according to the product size to obtain the end copper-aluminum alloy busbars of the required size.

2. The method of claim 1, wherein the method is characterized by: The process also includes step I: straightening and leveling the copper-plated aluminum alloy busbars at the ends, followed by chamfering using a chamfering machine. After chamfering is completed... The lines were straightened and leveled again.

3. The method of claim 1, wherein the CCAE busbars are prepared by the steps of: In step D or D1, the copper strip is wound onto the rolls from opposite directions in the casting and rolling direction. At the same time, each copper strip is equipped with a tension roll and a pressure roll to ensure that the copper strip moves at a consistent speed and that the copper strip fits tightly against the rolls after entering the solid-liquid casting and rolling area. On one side of the casting nozzle, there is also a heating roll that works with the copper strip. The heating roll heats the copper strip to between 100°C and 150°C. ​ 4. The method of claim 1, wherein the method is characterized by: In step D or D1, the copper strip is wound onto the rolls in the same direction from the casting and rolling direction. At the same time, 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 enter the solid-liquid casting and rolling area and fit tightly against the rolls.

5. The method of claim 1, wherein the method is characterized by: In step A, the temperature is heated to 720°C to 750°C to obtain molten aluminum.

6. The method of claim 1, wherein the CCAE busbars are prepared by the steps of: In step C, the molten aluminum is kept at a temperature of 720℃~740℃ in a holding furnace, and then left to stand for 20 min~60 min. ​ 7. The method of claim 1, wherein the method is characterized by: In step F, the cooling rate is 300℃ / s to 1000℃ / s.

8. The method of claim 1, wherein the method is characterized by: In step G, the annealing temperature is 350℃~450℃, and the annealing time is 15 h~30 h.

9. An end-copper clad aluminum alloy busbar characterized by, The double-sided or single-sided copper-clad aluminum alloy busbars are manufactured using any one of the methods described in claims 1 to 8.