CN102357526B - Two-step composite rolling method for copper-aluminum-copper double-side ultrathin composite strip - Google Patents

Abstract

The invention relates to a composite rolling method for a copper-aluminum-copper double-side composite strip, which belongs to the technical field of material processing. The composite strip has a three-layer structure, the upper and lower layers are copper layers, and the middle layer is an aluminum layer. The method disclosed by the invention comprises the following steps of: carrying out the rolling composition of a copper-aluminum single-side composite strip when the copper-aluminum-copper double-side composite strip is prepared, wherein the thickness ratio of the copper strip to the aluminum strip is 1:1; finishing the uncoiling, straightening, grinding, centering and rolling composition on the copper strip and the aluminum strip in sequence; carrying out aluminum surface secondary rolling composition of the copper-aluminum single-side composite strip; and making the aluminum surfaces of the copper-aluminum single-side composite strip opposite and carrying out secondary rolling so as to realize the rolling composition of the copper/aluminum/copper double-side composite strips and obtain a copper-aluminum-copper double-side composite strip, wherein the thickness ratio of the copper layer to the aluminum layer to the copper layer is equal to 1:2:1. The invention can obtain the ultrathin composite strip with a small size, high precision, firm composite interface combination and high surface quality under the condition that 50 percent of copper is ensured to be saved, and the thickness size of the composite strip is between 0.1mm and 0.15mm.

Description

A two-step composite rolling method for copper-aluminum-copper double-sided ultra-thin composite strip

technical field

The invention belongs to the technical field of metal material processing, and in particular relates to a rolling method of a copper-aluminum composite strip.

Background technique

Due to the rapid development of science and technology, the performance requirements of modern industry for metal materials are getting higher and higher, and the requirements for the improvement of material structures are also becoming stronger and stronger. A single metal material can no longer meet these needs. New composite materials with different mechanical properties and prices have emerged as the times require, which will make more effective use of the characteristics of materials, overcome and make up for the lack of performance of a single material, and thus obtain new materials with more excellent comprehensive properties. Therefore, the development and preparation of these new materials with excellent or special properties have become the research focus of scientific and technological personnel in the field of contemporary metallurgical materials. Among them, the processing and forming technology of low-cost, high-performance metal composite materials is not only valued by engineers and technicians , and has been included in the high-tech fields supported by the state, and will be supported from two aspects of policy and funds in the future.

China is a copper-poor and aluminum-rich country. The annual copper consumption of current-carrying conductor materials in China's electrical industry accounts for nearly one-third of the world's total copper consumption. Therefore, copper has become another important commodity in China besides oil. strategic resources. Since the 1990s, as the shortage of non-ferrous metal resources has intensified, the price of copper has risen sharply, resulting in a substantial increase in the production and use costs of copper manufacturers and customers. Therefore, on the basis of ensuring the performance of the original copper materials, the development of new materials to replace traditional materials has become a hot spot in the research and development of domestic and foreign manufacturers. The use of alternative composite materials to reduce raw material costs has become a development trend in the production and application of copper materials at home and abroad. .

Metal copper has good electrical conductivity and welding performance, but resources are scarce and processing is expensive. Metal aluminum has good electrical conductivity and relatively low price, but aluminum's welding, arc extinguishing, wear resistance, electrical conductivity, and thermal conductivity are worse than copper. In many occasions, it is difficult to directly replace copper with aluminum. Forming copper-clad aluminum composite strips with copper-clad aluminum can not only save the consumption of metal copper, but also maintain the ductility, conductivity, and Solderability, corrosion resistance and other characteristics. In addition, my country is rich in aluminum resources, the price of aluminum is lower than that of copper, and its density is less than 1/3 of that of copper, which means that under the same weight conditions, the length of aluminum is three times that of pure copper. Especially in the field of communication, the frequency of cable TV signal and mobile communication signal is relatively high, generally at 500-800MHZ. Due to the "skin effect", the high-frequency current is concentrated on the surface of the conductor for transmission. When pure copper is used for information transmission, the center The copper in the part does not play the role of the main transmission signal, so it is an ideal method to partially replace the copper in the middle layer with aluminum, which can greatly save the relatively scarce and expensive copper resources in our country. In fact, not only in the field of communication, but also in the field of power transmission, copper-clad aluminum composite strips will have a wider application prospect in the field of power transmission, and are expected to form a huge industry. The development of high-efficiency and low-energy composite technology suitable for industrial-scale production and the preparation of new materials for copper-clad aluminum composite strips will undoubtedly provide ideal new products for my country's rapidly developing industries such as electronics, electric power, and machinery manufacturing. It not only has significant economic benefits, but also has important social benefits for the rational use of resources and the sustainable development of the national economy. Therefore, the development of this technology has become the goal of researchers at home and abroad.

There are many production methods of metal composite materials, which can be roughly divided into two categories: solid-solid phase composite method and liquid-solid phase composite method. The solid-solid composite method includes rolling composite, explosive composite, extrusion-drawing composite, welding method, etc., and the liquid-solid composite method includes core-filling continuous casting, double mold continuous casting, etc. Among them, the rolling method is the most widely used.

Conventional compound rolling technology adopts one-time composite technology in the production of three-layer composite strip. For the production of large-size composite strip, the effect is obvious, the process is stable, and the production efficiency is high. However, for the lamination of ultra-thin strips with a thickness of less than 0.15mm, the effect of the one-time lamination technology is not good. Therefore, the application of this technology is relatively limited.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention provides a two-step compound rolling method for copper/aluminum/copper (referred to as copper-aluminum-copper) three-layer ultra-thin composite strip, which is an efficient copper-copper/aluminum The production method of/copper three-layer ultra-thin composite strip, when preparing copper/aluminum/copper double-sided composite strip, first carry out the rolling compound of copper/aluminum single-sided composite strip, the thickness ratio of copper strip, aluminum strip is 1: 1. Carry out secondary rolling and compounding of the aluminum side of the copper/aluminum single-sided composite strip to obtain a copper/aluminum/copper double-sided composite strip. The thickness ratio of each layer is copper: aluminum: copper=1:2:1. Using the composite strip prepared by this method, the amount of copper strip can be saved by 50%.

According to the present invention, a kind of composite rolling method of copper-aluminum-copper double-sided composite strip is provided, which is characterized in that a four-roll cold rolling mill is used, and the rolling of the composite strip is carried out in the following steps: (1) the prepared After the copper strip and the aluminum strip are centered, compound rolling is carried out. The rolling speed is 15-30mm/s, the rolling pressure is less than 4000kN, the temperature of the copper strip is controlled at 120-150°C during rolling, and the aluminum strip is taken at room temperature. After the system is completed, the thickness of the copper-aluminum composite strip is 1.5-3.0mm, and then the annealing furnace is used to carry out intermediate annealing treatment for the copper-aluminum composite strip formed through the first rolling; (2) the copper obtained through the first composite rolling The aluminum side of the aluminum single-sided composite strip is opposite, and the second rolling is carried out using the equipment and process parameters of the first rolling. The surface temperature of the strip is controlled at 200-250°C. The copper-aluminum-copper composite strip after rolling The thickness is 1.0-1.5mm; then use an annealing furnace to carry out intermediate annealing treatment on the obtained copper-aluminum-copper composite strip; (3) carry out multi-pass precise rolling on the annealed copper-aluminum-copper composite strip, and then carry out final annealing treatment.

Preferably, the combined rolling reduction in each step is not less than 65%. Optionally, the annealing temperature of the intermediate annealing is 260-350° C., the annealing holding time is 3-5 hours, and the inert gas protection is used.

According to the present invention, the multi-pass precise rolling of the annealed copper-aluminum-copper composite strip refers to the 7-pass rolling of the copper-aluminum-copper composite strip, and the thickness deformation during rolling is as follows Show:

1.0mm→0.75mm→0.55mm→0.4mm→0.3mm→0.22mm→0.16mm→0.12mm.

According to the present invention, the temperature of the annealing furnace for the final annealing treatment of the annealed copper-aluminum-copper composite strip is 500-560° C., the speed of continuous annealing and stripping is 3-5 m/min, and the annealing time is 6-5 m/min. 10 minutes.

According to the present invention, the annealed copper-aluminum-copper composite strip is characterized in that: the surface layer is a copper layer, the middle layer is an aluminum layer, the thickness ratio of each layer is 1:2:1, and the thickness of the composite strip is 0.1 -0.15mm.

Description of drawings

Fig. 1 is the rolling composite schematic diagram of the first step, and among the accompanying drawings, 1 is a copper strip, 2 is an aluminum strip, and 3 is a copper-aluminum composite strip;

Fig. 2 is the composite schematic diagram of rolling in the second step, among the accompanying drawings, 4 is the copper layer in the copper-aluminum composite, and 5 is the copper-aluminum-copper composite strip;

Figure 3 is an electron microscope photograph of the cross-sectional size of a copper-aluminum-copper three-layer ultra-thin composite tape with a thickness of 0.12 mm.

Detailed ways

Aiming at the deficiencies in the prior art, the present invention provides a two-step composite rolling method for copper/aluminum/copper (referred to as copper-aluminum-copper) three-layer ultra-thin composite strip, which is an efficient copper/aluminum/copper The production method of the copper three-layer ultra-thin composite strip, when preparing the copper/aluminum/copper double-sided composite strip, first carries out the rolling and compounding of the copper/aluminum single-sided composite strip, and the thickness ratio of the copper strip and the aluminum strip is 1:1 , and then carry out the secondary rolling and compounding of the aluminum side of the copper/aluminum single-sided composite strip to obtain a copper/aluminum/copper double-sided composite strip, and the thickness ratio of each layer is copper: aluminum: copper=1:2:1. Using the composite strip prepared by this method, the amount of copper strip can be saved by 50%.

The specific content of the copper/aluminum/copper three-layer ultra-thin composite strip two-step composite rolling method that this invention has completed is as follows:

1. Material selection. Select aluminum strips and copper strips with smooth and flat surfaces and a thickness tolerance of less than 0.05mm, of which:

Aluminum strip thickness H _Al = 3.0±0.03mm, width 220±0.1mm, aluminum content above 99.6%, soft state σ _b is 70-94Mpa, δ ₅ is 25-35%;

Copper strip thickness H _Cu = 3.0±0.03mm, width 220±0.1mm, copper content above 99.9%, oxygen content less than 0.01%, extra soft state, σ _b is 200-220MPa, δ ₅ is 38-48%;

The initially selected aluminum and copper strips should have the same thickness, the thickness of each strip should be within the range of 1.5-3.0±0.03mm, and the width should be within the range of 200-220±0.1mm.

2. Pre-rolling treatment. Copper strip and aluminum strip are processed by decoiler, straightening machine and grinding device in turn to complete the process of decoiling, straightening and grinding of the strip;

After the aluminum strip is uncoiled and straightened, it is required that the surface of the plate be straight without bending or wave shape. The straightening machine focuses on straightening the head and tail of the aluminum strip, and does not adopt the full-length straightening scheme;

The aluminum strip can be polished with an emery cloth wheel or a wire brush, and the entire board surface should be effectively polished, and the grinding depth is 0.005-0.03mm. The diameter of the bristles of the copper strip steel wire brushing machine is selected as 0.15-0.3mm. After cleaning, there should be uniform and dense groove marks on the surface of the copper strip, and no missing brush and deformation are allowed;

3. The first composite rolling. The upper and lower automatic centering of the copper strip and the steel strip is carried out through the photoelectric centering device. The aluminum strip on the lower side is based on the rolling center line, and the copper strip on the upper side is automatically aligned on the center of the aluminum strip. The deviation correction accuracy is 0.5-1.0 within millimeters. Rolling is carried out by a four-roller composite cold rolling unit with a specification of Φ250×400/Φ450×380. The rolling speed is 15-30mm/s, the tension is stable, the shape of the plate is well controlled, and no large side bends and edge waves, etc. Phenomenon, the rolling pressure is less than 4000kN, and the transmission mode is work roll transmission. During rolling, the temperature of the copper strip is controlled at 120-150°C, and the aluminum strip is not heated. The thickness of the copper/aluminum composite strip should be 1.5-3.0mm when the first composite rolling is completed.

4. The first annealing treatment. The copper-aluminum composite strip after the first composite needs to be treated with intermediate annealing. The intermediate annealing adopts a strong circulation type gas shield type annealing furnace with good annealing airtightness and high thermal efficiency. The annealing temperature is 260-350°C, and the annealing holding time is 3 -5 hours, inert gas protection.

5. The second compound rolling. During the second composite rolling, the copper-aluminum single-sided composite strip obtained through the first composite rolling is compounded together, wherein the aluminum surface of the composite strip is opposite, and the equipment for the first rolling is adopted and passed through the first During the rolling process, the surface temperature of the strip is controlled at 200-250°C to realize the rolling and compounding of the copper/aluminum/copper double-sided composite strip, and the thickness of the composite strip after rolling is 1.0-1.5mm.

6. The second annealing treatment. After the second compounding, intermediate annealing treatment is carried out. The intermediate annealing adopts a strong circulation gas shielded annealing furnace, the heating temperature is 260-350 ° C, the annealing holding time is 3-5 hours, and the inert gas protection is used.

7. Multi-pass precision rolling. In order to increase the composite strength of the copper-aluminum-copper composite, realize the metallurgical bonding between each other, and also to further reduce the thickness of the composite strip, it is necessary to carry out multi-pass precise rolling on the completed composite strip. Among them, it can be tied 7 times, and the thickness deformation of each time is as follows:

1.0mm→0.75mm→0.55mm→0.4mm→0.3mm→0.22mm→0.16mm→0.12mm (finished product).

8. Finished product annealing. The finished product obtained through multi-pass rolling is sent to a continuous annealing furnace for finished product annealing. The temperature of the annealing furnace is 500-560°C, the annealing speed is 3-5m/min, and the annealing time is 6-10 minutes.

The implementation of the patent of the present invention is divided into two steps of rolling and compounding process. Firstly, the single-sided compounding of copper/aluminum is realized. Aluminum surface composite, the thickness of copper/aluminum/copper three-layer composite strip can be changed within 1.0-1.5mm, the interface is metallurgical bonding, and the thickness ratio of each layer is 1:2:1.

Specific embodiments of the method according to the present invention will be described in detail below. According to a specific embodiment of the present invention, the following steps are included:

Raw material selection:

Aluminum strip H _Al = 3.0±0.03mm, width 220±0.1mm, aluminum content 99.7%, soft state, σ _b is 82MPa, δ ₅ is 28%;

Copper strip H _Cu = 3.0±0.03mm, width 220±0.1mm, copper 99.95%, oxygen 0.085%, σ _b 208MPa, δ ₅ 41%;

H＝H _Al +H _Cu ＝6.0mm, the surface of copper strip and aluminum strip is smooth and flat, and the thickness tolerance is 0.03mm.

The first step composite rolling reduction procedure:

6mm→1.5mm

Copper strip and aluminum strip pass through decoiler, straightening machine, grinding device, photoelectric centering device, compound rolling mill and other equipment in sequence.

After the aluminum strip is uncoiled and straightened, the surface of the strip is straight without bending or wave shape, and the straightening machine straightens the head and tail of the aluminum strip.

The abrasive cloth wheel is used for grinding the aluminum strip, and the entire board surface is effectively ground, and the grinding depth is 0.005-0.03mm. The copper strip is polished with a steel wire brush, and the diameter of the bristles of the steel wire brushing machine is 0.2mm. After polishing, the groove marks on the surface of the copper strip are uniform and dense, without missing brushes and deformation.

The rolling process is automatically centered, the aluminum strip is based on the rolling center line, and the copper strip is automatically aligned around the aluminum strip, and the deviation correction accuracy is within the range of 0.5-1.0mm.

The composite rolling mill is a Φ250×400/Φ450×380 four-roll composite cold rolling unit with a rolling speed of 20mm/s, stable tension, good shape control, no large side bending and edge waves, etc., and a rolling pressure of 3800kN. During the rolling process, the temperature of the copper strip is controlled between 125-145°C, the aluminum strip is not heated, and there is no oxidation phenomenon. After the rolling is completed, the thickness of the composite copper-aluminum composite plate is 1.5mm.

Intermediate annealing is carried out after the first compounding, using a strong circulation gas shield annealing furnace, heating temperature 300 ° C, annealing holding time 4.5 hours, argon protection.

The second step composite rolling reduction procedure:

3.0mm→1.0mm

During the second step of rolling and compounding, the aluminum faces of the copper-aluminum single-sided composite strips are opposite and superimposed together. The surface temperature of the strip is controlled at 220±20°C to realize the rolling and compounding of the copper-aluminum-copper double-sided composite strip. During the rolling process, the shape of the roll and the shape of the strip are stable. The thickness of the composite strip after rolling is 1.0 mm. After the second compounding, intermediate annealing treatment is carried out on the composite tape again. The intermediate annealing adopts a strong circulation type gas shield type annealing furnace, the heating temperature is 260±10°C, the annealing holding time is 3 hours, and the argon gas protection is used.

Finally, the finished product is finished rolling, and the following reduction procedure is adopted:

1.0mm→0.75mm→0.55mm→0.4mm→0.3mm→0.22mm→0.16mm→0.12mm (finished product)

Final annealing is carried out on the finished product, the heating temperature is 550° C., and the speed of continuous annealing tape is 5 m/min. Annealing time 8 minutes.

Figure 3 is an electron microscope photo of the section size of the 0.12mm ultra-thin composite strip. It can be seen from the photo that after rolling, the copper, aluminum and copper have completely achieved metallurgical bonding.

The invention patent can obtain ultra-thin composite strips with small size, high precision, firm composite interface and good surface quality under the condition of saving 50% copper material. The thickness of the three-layer composite strip is 0.1-0.15mm, each layer The thickness ratio is 1:2:1. Therefore, according to the present invention, in the production of copper-aluminum-copper three-layer composite strip, the two-step composite rolling technology is adopted, and the effect is remarkable in the production of ultra-thin composite strip with a final thickness of 0.1-0.15 mm.

The method of the present invention is realized on the production line of the existing four-high composite cold rolling mill, so the method is not only applicable to the production of copper/aluminum/copper three-layer ultra-thin composite strips, but also applicable to the production of other three-layer ultra-thin composite strips Production.

Claims (3)

1. the composite rolling method of a copper aluminum bronze double composite strip material is characterized in that using the 4-roller cold rolling mill group, adopts following steps to carry out the rolling of composite strip:

(1) will carry out composite rolling after ready copper strips and the aluminium strip centering, its mill speed is 15-30mm/s, draught pressure is less than 4000kN, the control of copper strips temperature is at 120-150 ℃ when rolling, and aluminium strip is got the normal temperature temperature, and the thickness of copper aluminum composite belt is 1.5-3.0mm after rolling the finishing, utilizing annealing furnace to carry out intermediate annealing for the copper aluminum composite belt through rolling formation for the first time then handles, its annealing temperature is 260-350 ℃, and the annealing temperature retention time is 3-5 hour, inert gas shielding;

(2) the aluminium face of the copper aluminium single face composite strip that will obtain through the composite rolling first time is relative, it is rolling that the equipment that employing is for the first time rolling and technological parameter thereof carry out the second time, the control of strip surface temperature is at 200-250 ℃, and the copper aluminum bronze composite strip thickness after rolling is 1.0-1.5mm; Utilize annealing furnace that the copper aluminum bronze composite strip that obtains is carried out intermediate annealing then and handle, its annealing temperature is 260-350 ℃, and the annealing temperature retention time is 3-5 hour, inert gas shielding;

(3) it is accurately rolling the copper aluminum bronze composite strip through annealing in process to be carried out multi-pass, carry out last annealing in process then, the temperature of its annealing furnace is 500-560 ℃, the speed of continuous annealing tape transport is 3-5m/min, annealing time 6-10 minute, finally obtaining copper aluminum bronze composite strip top layer was the copper layer, and the intermediate layer is aluminium lamination, each layer thickness ratio is 1: 2: 1, and the thickness of composite strip is 0.1-0.15mm.

2. according to the composite rolling method of the described copper aluminum bronze of claim 1 double composite strip material, it is characterized in that the rolling compound reduction ratio in each step all is not less than 65%.

3. according to the composite rolling method of the described copper aluminum bronze of claim 1 double composite strip material, it is characterized in that describedly copper aluminum bronze composite strip through annealing in process being carried out multi-pass accurately rolling to refer to that copper aluminum bronze composite strip is carried out 7 passages rolling, the thickness deformation amount when rolling is as follows:

1.0mm→0.75mm→0.55mm→0.4mm→0.3mm→0.22mm→0.16mm→0.12mm。

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