Aluminum alloy bus bar with copper-clad end parts and preparation method of aluminum alloy bus bar

Abstract

The invention discloses an aluminum alloy busbar with a copper-clad end part and a preparation method thereof, relates to the technical field of copper-aluminum composite eutectic plate production, and the aluminum alloy busbar with a double-sided or single-sided copper-clad end part is produced through the steps of cast rolling, heat treatment and striping. Compared with the prior art, according to the aluminum alloy bus bar with the ends coated with copper on the double faces or on the single face, through the end copper coating technology, the two ends of the aluminum alloy bus bar are provided with copper-aluminum eutectic structures at the same time, the mechanical property and oxidation resistance of the copper-aluminum composite bus bar are greatly improved, the use amount of copper is greatly reduced, meanwhile, the peeling strength of the copper-coated part is high, and the service life of the copper-aluminum composite bus bar is prolonged. The copper layer and the aluminum layer are not easy to separate, the performance is better, the reliability of the copper-aluminum eutectic busbar is improved, and the problems of high cost of the existing busbar, unreliable connection of the pure aluminum alloy busbar and low peeling strength of the copper-aluminum composite busbar are solved.

Description

Technical Field

[0001] The invention relates to the technical field of copper-aluminum composite eutectic plate production, and in particular to a production technology of a copper-aluminum alloy busbar with double or single ends. Background Art

[0002] Busbar, also known as busbar line or busbar, busbar, is a metal conductor, mainly made of copper or aluminum and other materials with high conductivity and corrosion resistance. The main function of busbar is to effectively conduct electricity from power sources (such as transformers or generators) to various types of power loads. It is not only an important connection point for electrical equipment, such as circuit breakers, fuses, switches, etc., but also can be directly installed or connected to these components by bolts, clips or other means. Since the number of busbars required for large-scale equipment is very large, if pure copper busbars are used, the cost of busbars is unbearable for most production units; while pure aluminum busbars can reduce costs, they are easy to oxidize when used, and the connection between aluminum and aluminum at the end is unreliable. After long-term use, most of the busbars have problems in the connection part. The connection between copper and copper is more reliable than the former. For this reason, copper-clad aluminum alloy busbars of various sizes have been developed on the market. The main structure is aluminum alloy covered with copper, which can ensure reliable connection while reducing costs. Copper-aluminum composite busbar is a new type of bimetallic composite conductor with the advantages of good conductivity, low density and low price. It can replace the existing pure copper conductive busbar.

[0003] However, the copper usage of copper-clad aluminum alloy busbars is still high. Although the overall cost has been reduced, it is still expensive. For this reason, the present application designs an aluminum alloy busbar that is copper-clad only on one or both sides of the end. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides an aluminum alloy busbar with copper clad ends and a preparation method thereof. The present application designs an aluminum alloy busbar with copper clad ends on both sides or on one side. Through the end copper cladding technology, both ends of the busbar have a copper-aluminum eutectic structure, which greatly improves the mechanical properties and oxidation resistance of the copper-aluminum composite busbar and greatly reduces the amount of copper used. At the same time, the copper-clad part has high peeling strength, and the copper layer and aluminum layer are not easy to separate, so the performance is better, which improves the reliability of the copper-aluminum eutectic busbar and solves the problems of high cost of existing busbars, unreliable connection of pure aluminum alloy busbars, and low peeling strength of copper-aluminum composite busbars.

[0005] In order to solve the above technical problems, the present invention is solved by the following technical solutions: a method for preparing an end copper-clad aluminum alloy busbar, comprising the following steps: step A: adding a raw aluminum ingot into a smelting furnace for smelting treatment to obtain molten aluminum liquid; step B: the copper strip is unwound on an unwinder, and there are two copper strips on the unwinder and they are respectively on both sides of the unwinder. A replaceable sleeve is arranged in the center of the unwinder to limit and separate the copper strips on both sides, and the distance between the copper strips is the sleeve width; step C: the aluminum liquid after being kept and allowed to stand is degassed and filtered through online processing equipment such as a degassing box and a filter box; step D: four copper strips are respectively placed close to both sides of the upper and lower rollers, and the interval between the copper strips on the same roller is the sleeve width, and the copper strips are heated before entering the gap between the upper and lower rollers; or step D is changed to step D1: two copper strips are respectively wound on both sides of the lower roller, and the interval between the copper strips on the lower roller is the sleeve width, and the copper strips enter the gap between the upper and lower rollers. The aluminum liquid is heated before the gap is formed; Step E: aluminum liquid in the temperature range of 705°C to 715°C is injected into the gap between the upper and lower rollers under static pressure through a casting nozzle, and the injection width is the sum of the width of the copper strips on both sides of the rollers and the distance between them, and the gap between the upper and lower rollers is the solid-liquid casting area; Step F: The upper and lower rollers cool the molten aluminum liquid and the copper strip and perform solid-liquid casting to form a copper-aluminum composite slab coil with copper clad at the end; Step G: The copper-aluminum composite slab coil is placed in an annealing furnace for homogenization annealing; Step H: The copper-aluminum composite slab is then introduced into a slitting device, and slitting is performed according to the product size to obtain an aluminum alloy busbar with copper clad at the end of the required size.

[0006] In the above technical solution, preferably, it also includes step I: straightening and leveling the aluminum alloy busbar with copper cladding at the end, then chamfering it through a chamfering device, and straightening and leveling it again after the chamfering is completed.

[0007] In the above technical scheme, preferably, in step D or D1, the copper strip is wound around the roller in the opposite direction of the casting and rolling direction, and each copper strip is equipped with a tensioning roller and a pressure roller to ensure that the movement speed of the copper strip is consistent and the copper strip is tightly fitted with the roller after entering the solid-liquid casting and rolling area. A heating roller cooperating with the copper strip is also provided on one side of the casting nozzle, and the heating roller heats the copper strip to between 100°C and 150°C.

[0008] In the above technical scheme, preferably, in step D or D1, the copper strip is wound around the rolling roller in the same direction as the casting direction, and each copper strip is equipped with a clamping heating roller, which heats the copper strip to between 100°C and 150°C and allows the copper strip to fit tightly with the rolling roller after entering the solid-liquid casting area.

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

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

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

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

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

[0014] In the above technical solution, preferably, rolling and cooling are performed only in the solid-liquid casting and rolling area.

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

[0016] When copper is coated on both sides or one side, the casting nozzle only needs to statically inject the aluminum liquid onto the copper plate or between two copper plates. The entire injection width is uniform. As long as the copper plate conveying speed, hot rolling speed and injection speed are constant, continuous hot rolling production can be achieved. However, this application is completely different. This application is copper coated on both sides of the end or copper coated on one side of the end, that is, there is no copper plate in the middle position. During the aluminum liquid injection process, aluminum liquid actually overflows from the two ends. For this reason, the copper strip must be tightly attached to the roller, leaving space for aluminum liquid and the winding speed of the copper strip synchronously. For this reason, this application requires an additional clamping roller to press the copper strip tightly against the roller.

[0017] The copper strip of the present application is a copper-aluminum eutectic busbar. When the rollers are hot-rolling the copper and aluminum, there is a cooling device inside the rollers, which can cool the copper-aluminum alloy. The benefit of cooling is that smaller grains can be formed and the material strength can be improved. If the temperature of copper is between 150°C and 220°C during the hot rolling of copper and aluminum, the copper atoms can obtain enough energy to migrate in a short time under high temperature to form a thicker copper-aluminum eutectic layer, thereby effectively improving the bonding strength of the copper-aluminum composite interface. However, the copper strip needs to fit tightly on the rollers, and there is a cooling device inside the rollers. If the copper strip is preheated and then passes through the rollers, it will lose temperature before entering the solid-liquid casting and rolling area. For this reason, the copper strip needs to be heated before entering the solid-liquid casting and rolling area. The present application sets up two structures, one is how the copper strip is pressed and heated when it enters the solid-liquid casting and rolling area in the positive direction, and the other is how the copper strip is pressed and heated when it enters the solid-liquid casting and rolling area in the negative direction. Since the copper plates in the prior art are changed into copper strips, that is, there is a gap between the two copper strips, the influence of the copper strips on the casting nozzle and the blank is greatly reduced when they are brought in and out.

[0018] This application requires an improvement in the cooling system of the rolls. The original cooling system of the rolls was evenly distributed inside the rolls, that is, the cooling rate of the roll surface was consistent, but this application required the copper strip to be heated before hot rolling, which required an improvement in the cooling system of the rolls, so that the cooling rate in the solid-liquid casting area was maximized, and the cooling capacity in other areas was reduced, so as to keep the copper strip warm to the greatest extent.

[0019] Compared with the prior art, the present application designs an aluminum alloy busbar with double-sided or single-sided copper cladding at the ends. Through the end copper cladding technology, both ends of the busbar have a copper-aluminum eutectic structure, which greatly improves the mechanical properties and oxidation resistance of the copper-aluminum composite busbar and greatly reduces the amount of copper used. At the same time, the copper-clad part has high peeling strength, and the copper layer and aluminum layer are not easy to separate, so the performance is better, which improves the reliability of the copper-aluminum eutectic busbar and solves the problems of high cost of existing busbars, unreliable connection of pure aluminum alloy busbars, and low peeling strength of copper-aluminum composite busbars. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions of the various embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1: Production of a 1.5m long, 8mm thick, double-sided copper-clad aluminum busbar, with the end surfaces clad in copper on both sides, i.e., a total of four copper surfaces at the two ends. A single copper sheet is 10cm long and 1.5mm thick.

[0022] The method comprises the following steps: Step A: adding raw aluminum ingots into a smelting furnace for smelting treatment, heating to 720° C. to 750° C., and obtaining molten aluminum liquid; the raw aluminum ingots are aluminum materials of models 1G20, 1050, 1060, and 1100, and the aluminum content is greater than 99.2%.

[0023] Step B: The copper strip is unwound on the unwinder. There are two copper strips on the unwinder and they are located on both sides of the unwinder. A sleeve is set in the center of the unwinder to limit the separation of the copper strips on both sides. The copper strip is T2 copper or brass. Before unwinding, the copper strip is first rinsed with high pressure to quickly remove solid impurities on the surface of the copper plate, and then rinsed with low pressure. The rinse liquid is an alkaline degreasing liquid at 50°C for degreasing treatment to remove grease on the surface of the copper plate. Finally, the oxide layer on the surface of the copper plate is polished off by a steel brush. After polishing, the roughening degree of the copper strip surface can be improved, and the copper-aluminum composite area can be increased, thereby enhancing the bonding ability of the composite material.

[0024] Step C: After the aluminum liquid is kept at a temperature of 720℃~740℃, it is kept at a temperature of 20min~60min; it is degassed and filtered through online processing equipment such as degassing boxes and filter boxes. The rollers in the twin-roll casting equipment have a cooling function. It is best that the rollers are cooled only in the solid-liquid casting area, and not outside the solid-liquid casting area, which is conducive to the insulation of the copper strip.

[0025] Step D: Four copper strips are wound on rollers from the injection direction of the casting nozzle. Each copper strip is equipped with a tensioning roller and a pressing roller. The speed of the copper strips is adjusted by the tensioning roller and the pressing roller to ensure that the speed of the four copper strips winding the rollers is consistent. At the same time, the pressing roller ensures that the copper strips are tightly attached to the rollers when entering the solid-liquid casting area. There is also a heating roller on one side of the casting nozzle. Usually, one copper strip is equipped with a heating roller. The heating roller is close to the solid-liquid casting area and heats the copper strip to 150°C.

[0026] Step E: Inject aluminum liquid in the temperature range of 710℃ into the gap between the upper and lower rollers through the casting nozzle, and the injection width is the sum of the width of the copper strips on both sides of the rollers and the distance between them; Step F: The upper and lower rollers cool the molten aluminum liquid and the copper strip and solid-liquid cast to form a copper-aluminum composite slab coil with copper on both sides of the end; At the same time, the upper and lower rollers cool the copper-aluminum composite slab. The cooling rate is 300℃ / s. The coolant in the upper and lower rollers is water, and the water is kept at a temperature of 20℃ in the upper and lower rollers. When the aluminum liquid is injected through the casting nozzle, the aluminum liquid contacts the rollers and cools rapidly to solidify. Similarly, the aluminum liquid contacts the copper strips and cools rapidly. The aluminum liquid contacts the upper and lower copper strips in the casting and rolling area to crystallize, and the heat is taken out by the cooling water circulating in the rollers. After casting, the copper-aluminum composite slab coil can also be cold-rolled to the required thickness as needed.

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

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

[0029] Example 2: Production of a 1.5m long, 10mm thick, single-sided copper-clad aluminum busbar, with the end surface single-sidedly copper-clad, i.e., two ends share two copper surfaces, both on the same side. A single copper sheet is 10cm long and 2mm thick.

[0030] The method comprises the following steps: Step A: adding raw aluminum ingots into a smelting furnace for smelting treatment, heating to 720° C. to 750° C., and obtaining molten aluminum liquid; the raw aluminum ingots are aluminum materials of models 1G20, 1050, 1060, and 1100, and the aluminum content is greater than 99.2%.

[0031] Step B: The copper strip is unwound on the unwinder. There are two copper strips on the unwinder and they are located on both sides of the unwinder. A sleeve is set in the center of the unwinder to limit the separation of the copper strips on both sides. The copper strip is T2 copper or brass. Before unwinding, the copper strip is first rinsed with high pressure to quickly remove solid impurities on the surface of the copper plate, and then rinsed with low pressure. The rinse liquid is an alkaline degreasing liquid at 70°C for degreasing treatment to remove grease on the surface of the copper plate. Finally, the oxide layer on the surface of the copper plate is polished off by a steel brush. After polishing, the roughening degree of the copper strip surface can be improved, and the copper-aluminum composite area can be increased, thereby enhancing the bonding ability of the composite material.

[0032] Step C: After the aluminum liquid is kept warm and still, pour the molten aluminum liquid into the holding furnace, control the temperature at 720℃~740℃, keep warm and still for 20min~60min; degas and filter through online processing equipment such as degassing box and filter box. The rollers in the twin-roll casting equipment have cooling function. It is best that the rollers are cooled only in the solid-liquid casting area, and not outside the solid-liquid casting area, which is conducive to the insulation of the copper strip.

[0033] Step D: Two copper strips are respectively wound on the rollers in the same direction of injection from the casting nozzle. Each copper strip is equipped with a clamping heating roller. The clamping heating roller heats the copper strip to 150°C and allows the copper strip to fit tightly with the roller after entering the solid-liquid casting area, while ensuring that the two copper strips are wound on the rollers at the same speed.

[0034] Step E: Inject aluminum liquid in the temperature range of 710℃ into the gap between the upper and lower rollers through the casting nozzle, and the injection width is the sum of the width of the copper strips on both sides of the rollers and the distance between them; Step F: The upper and lower rollers cool the molten aluminum liquid and the copper strip and solid-liquid cast to form a copper-aluminum composite slab coil with copper on both sides of the end; At the same time, the upper and lower rollers cool the copper-aluminum composite slab. The cooling rate is 300℃ / s. The coolant in the upper and lower rollers is water, and the water is kept at a temperature of 20℃ in the upper and lower rollers. When the aluminum liquid is injected through the casting nozzle, the aluminum liquid rapidly cools and solidifies after contacting the rollers. Similarly, the aluminum liquid also rapidly cools after contacting the copper strip. The aluminum liquid contacts and crystallizes with the upper and lower copper strips in the casting and rolling area, and the heat is taken out by the cooling water circulating in the rollers. After casting, the copper-aluminum composite slab coil can also be cold rolled to the required thickness as needed.

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

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

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

[0038] At 25°C and 68% humidity, the tensile strength is ≥150MPa, the elongation is around 14.0%, and the conductivity varies depending on the aluminum alloy model.

Claims

1. A method for preparing an end copper-clad aluminum alloy busbar, characterized in that: It includes the following steps: Step A: adding raw aluminum ingots into a smelting furnace for smelting to obtain molten aluminum liquid; Step B: The copper strip is unwound on the unwinding machine. There are two copper strips on the unwinding machine and they are located on both sides of the unwinding machine. A replaceable sleeve is arranged in the center of the unwinding machine 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 warm and allowed to stand, the 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 placed in pairs on 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 changed to step D1: two copper strips are respectively wound on both sides of the lower roller, the interval between the copper strips on the lower roller is the sleeve width, and the copper strips are heated before entering the gap between the upper and lower rollers; Step E: injecting aluminum liquid in a temperature range of 705°C to 715°C into the gap between the upper and lower rollers under static pressure through a casting nozzle, the injection width being the sum of the width of the copper strips on both sides of the rollers and the distance between them, and the gap between the upper and lower rollers is the solid-liquid casting area; Step F: The upper and lower rollers cool the molten aluminum and copper strip and perform solid-liquid casting to form a copper-aluminum composite slab coil with copper clad ends; Step G: placing the copper-aluminum composite sheet coil into an annealing furnace for homogenization annealing; Step H: The copper-aluminum composite slab is then introduced into a slitting device, and slitting is performed according to the product size to obtain an end copper-clad aluminum alloy busbar of a required size.

2. The method for preparing a copper-clad aluminum alloy busbar at the end according to claim 1, characterized in that: The step also includes step I: straightening and leveling the aluminum alloy busbar with copper cladding at the end, then chamfering it through a chamfering device, and straightening and leveling it again after the chamfering is completed.

3. The method for preparing a copper-clad aluminum alloy busbar at an end portion according to claim 1, characterized in that In step D or D1, the copper strip is wound around the roller in the opposite direction of the casting and rolling direction. At the same time, each copper strip is equipped with a tensioning roller and a pressure roller to ensure that the copper strip moves at a consistent speed and that the copper strip fits tightly with the roller after entering the solid-liquid casting and rolling area. A heating roller that cooperates with the copper strip is also provided on one side of the casting nozzle, and the heating roller heats the copper strip to between 100°C and 150°C.

4. The method for preparing a copper-clad aluminum alloy busbar at the end according to claim 1, characterized in that: In step D or D1, the copper strip is wound around the roller in the same direction as the casting direction, and each copper strip is equipped with a clamping heating roller, which heats the copper strip to between 100°C and 150°C and allows the copper strip to fit tightly with the roller after entering the solid-liquid casting area.

5. The method for preparing a copper-clad aluminum alloy busbar at the end according to claim 1, characterized in that: In step A, the aluminum liquid is heated to 720° C. to 750° C. to obtain molten aluminum.

6. The method for preparing an end copper-clad aluminum alloy busbar according to claim 1, characterized in that In step C, the aluminum liquid is kept warm in a holding furnace, the holding temperature is controlled at 720° C. to 740° C., and then allowed to stand for 20 min to 60 min.

7. The method for preparing an end copper-clad aluminum alloy busbar according to claim 1, characterized in that: In step F, the cooling rate is 300° C. / s to 1000° C. / s.

8. The method for preparing an end copper-clad aluminum alloy busbar according to claim 1, characterized in that: In step G, the annealing temperature is 350° C. to 450° C., and the annealing time is 15 h to 30 h.

9. A copper-clad aluminum alloy busbar, characterized in that: An end double-sided copper-clad aluminum alloy busbar or an end single-sided copper-clad aluminum alloy busbar manufactured by any one of the methods for preparing an end copper-clad aluminum alloy busbar according to claims 1 to 8.