Copper belt is a very common metal element, often in electrical components, lamp caps, battery caps, buttons, seals, connectors and other places to see, the main role is electrical conductivity, heat conduction, corrosion resistance equipment.

There are six zones for copper belt production, which are smelting furnace area, laboratory area, cutting area, hot rolling area, washing area and rolling plate area.

The following Xiaobian will tell you about the copper strip production process, the characteristics of cold rolling and hot rolling in the production method, and the solutions to some common problems, such as discoloration and shear indentation, we have a look!

Production process of copper belt:

1. Embryo-making: according to the predetermined production target, different amounts of zinc blocks are added into the waste copper material to produce copper raw materials of different specifications.

2, test: in order to ensure the production of both qualified and ensure the economic benefits of the finished products, the accuracy of test results is particularly important.

The duty of the laboratory is to inform the smelter of the test results quickly and accurately based on the copper blocks submitted for inspection.

3. Cutting: the complete copper strip is pulled by the hanging rope and placed smoothly on the special cutting platform. Then it is cut off by the cutting wheel saw, and the uneven surface of the copper strip surface is polished and smooth by the copper strip washing machine, which is conducive to the smoothness and smoothness of the copper strip surface processed in the later stage.

4. Hot rolling: the cut copper strip is heated at a high temperature of 1000℃ and then rolled to a copper strip with a thickness of about 2.3cm.

5, washing: each copper block after the initial rolling steps, due to the presence of impurities on the surface, in order to avoid affecting the quality of the finished product, must go through the sealing furnace and then washing process.

The washing area is divided into two pools according to the acidity.

The high concentration is 6-8 degrees, and the low concentration is 3-5 degrees.

The medium red patches on the surface of the copper rod and copper belt can be washed off by the acid solution of the water bath, while the dark red patches can be brushed off by the fine iron hairs during the water washing. After such a series of treatment methods, the copper belt obviously shines the inherent luster of copper itself.

If there are still red patches and red patches in the rolling process, the washing step needs to be repeated again.

During the washing period, the acidity in the pool should be checked regularly, and the acid should be added in time to avoid the acid content being too low and resulting in insufficient water washing.

6. Rolling plate: the rolling plate area is divided into 180 initial rolling and 110 medium rolling according to the rollers.

According to the size of the different rollers will be hot rolled down by sealing furnace forging burned copper belt through the above two steps, from rough to fine processing.

Features of copper belt production method:

1, copper strip cold rolling

(1) Plastic deformation.

(2) The pressure in the roll gap area is high and there is pressure distribution, up to 2700MPa.

(3) there is a friction force along the rolling direction and the reverse rolling direction.

(4) the instantaneous temperature of the roll gap is high, up to 200 ~ 300℃.

(5) Rolling and sliding states coexist.

2, copper strip hot rolling

Copper strip hot rolling advantages:

(1) Hot rolling can significantly reduce energy consumption and cost.

The metal has high plasticity and low deformation resistance during hot rolling, which greatly reduces the energy consumption of hot rolling.

(2) Hot rolling can improve the processing properties of metals and alloys, that is, the coarse grains in the casting state are broken, the significant cracks are healed, the casting defects are reduced or eliminated, the as-cast microstructure is transformed into deformation microstructure, and the processing properties of the alloy are improved.

(3) Hot rolling usually adopts large ingot and rolling with large pressure, which not only improves production efficiency, but also creates conditions for improving rolling speed and realizing continuous and automation of rolling process.

Disadvantages of copper strip hot rolling:

(1) After hot rolling, non-metallic inclusions (mainly sulfides and oxides, as well as silicate) in the metal are compressed into thin sheets, resulting in lamination (interlayer) phenomenon.

Delamination greatly worsens the tensile properties of the metal along the thickness, and there is the possibility of interlaminar tearing as the weld shrinks.

The local strain induced by weld shrinkage is often several times the yield point strain, which is much larger than the strain induced by load.

(2) Residual stress caused by uneven cooling.

Residual stress is the internal self-equilibrium stress under the action of no external force. All kinds of hot-rolled steel sections have this kind of residual stress. Generally, the larger the section size of the steel section, the greater the residual stress.

Although the residual stress is self-phase equilibrium, it still has some influence on the performance of metal under external force.

Such as deformation, stability, fatigue resistance and other aspects may have adverse effects.

(3) Hot rolling can not control the mechanical properties required by the product very accurately, and the structure and properties of hot rolling products can not be uniform.

Its strength index is lower than that of cold-hardening products, but higher than that of fully annealed products.

The plasticity index is higher than that of cold-hardening products, but lower than that of fully annealed products.

(4) Hot rolled product thickness size is difficult to control, the control accuracy is relatively poor;

The rough Ra value of hot rolled products is generally 0.5 ~ 1.5μm than that of cold rolled products.

Therefore, hot - rolled products are generally used as blank for cold - rolled processing.

The solution to the common problems of copper belt:

1, copper belt discoloration solution

(1) control the concentration of acid solution in pickling.

When the oxide layer is removed from the surface of the annealed copper strip, the high acid concentration is of no significance.

On the contrary, when the concentration is high, the residual acid attached to the surface of the copper belt is not easy to wash off, and speeds up the pollution of the cleaning water, resulting in the high concentration of the residual acid in the cleaning water, which makes the copper belt after cleaning easier to discolor.

Therefore, when determining the concentration of pickling solution, the principle should be followed: on the premise that the oxide layer on the surface of the copper strip can be cleaned, the concentration should be reduced as far as possible.

(2) control the electrical conductivity of pure water.

To control the electrical conductivity of pure water, that is, to control the content of chlorine ions and other harmful substances in pure water.

Generally, it is safer to control the electrical conductivity below 50μS/cm.

(3) to control the conductivity of hot cleaning water and passivating agent.

The increase of conductivity of hot cleaning water and passivating agent mainly comes from the residual acid brought into the copper strip.

Therefore, under the condition of ensuring the quality of clean water, the control of conductivity is to control the amount of residual acid.

According to many experiments, it is safe to control the conductivity of hot cleaning water and passivator below 200μS/cm respectively.

(4) ensure that the copper belt is dry.

Local closure is carried out at the exit of coiling air cushion furnace, and dehumidifier and air conditioner are used in the local closure device to control the humidity and temperature of copper strip coiling within a certain range.

(5) use passivation agent passivation.

Most copper processing plants now use benzotriazole or BTA(molecular formula: C6H5N3) as a passivator.

It has been proved that it is a convenient, economical and practical passivating agent.

When the copper strip passes through BTA solution, the oxide film on the surface reacts with BTA to form a dense complex, which plays a role in protecting the copper matrix.

2, copper belt shear indentation solution

In order to prevent the indentation of the cutting edge, the reasonable diameter difference between the circular cutter and the rubber stripping ring should be selected according to the thickness and hardness of the strip.

The hardness of the rubber stripping ring meets the requirements of the cutting strip;

When the width of the cutting strip is small, the thickness of the round knife should be selected reasonably and the width of the rubber stripping ring should be increased.