Essential information: Copper strip production knowledge that metal people must collect!
Copper strip is a very common metal component. It is often seen in electrical components, lamp holders, battery caps, buttons, seals, connectors, etc. Its main function is to conduct electricity, heat, corrosion resistance, etc. There are six areas in copper strip production, namely the furnace area, laboratory, cutting area, hot rolling area, water washing area and plate rolling area. Today's article mainly talks about the copper strip production process and solutions to some common problems, such as discoloration and shear indentation.
Copper strip production process flow:
1. Preparation: According to the predetermined production target, different amounts of zinc blocks are added to the scrap copper material to produce copper raw materials of different specifications.
2. Laboratory testing: In order to ensure the production of finished products that are both qualified and economically beneficial, the accuracy of laboratory testing results is extremely important. The responsibility of the laboratory is to quickly and accurately report the test results to the furnace master based on the copper blocks submitted for inspection.
3. Cutting: The complete copper bar is pulled by a hanging rope, placed stably on a special cutting table, and then cut by a cutting wheel saw. The uneven surface of the copper bar is then smoothed by a copper bar washing machine, which is beneficial to later processing. The flatness and smoothness of the copper strip surface.
4. Hot rolling: The cut copper strip is heated at a high temperature of 1000°C, then hot rolled, and rolled into a copper strip with a thickness of about 2.3cm.
5. Water washing: After each copper block has been rolled, due to the presence of surface impurities, in order to avoid affecting the quality of the finished product, it must go through the sealing furnace again and then go through the water washing process. The water washing area is divided into two types of pools according to the acidity. The high concentration is 6-8 degrees, and the low concentration is 3-5 degrees.
Among them, the medium red patches on the surface of copper rods and copper strips can be washed away by the acid in the washing tank, while the dark red patches can be removed by brushing with fine iron hair during washing. The copper strips after this series of treatments are obviously The ground shines with the inherent luster of copper. Similarly, if there are still red patches and red patches during the rolling process, the water washing step still needs to be repeated. During the washing period, the acidity in the pool should be checked regularly and acid should be added in time to avoid insufficient washing due to low acid content.
6. Plate rolling: The plate rolling area is divided into 180 preliminary rolling and 110 intermediate rolling according to the roller area. According to the different sizes of various rollers, the hot-rolled copper strips that have been forged in the sealing furnace are processed from rough to fine through the above two steps.
Solutions to common problems with copper strips:
1. Solution to discoloration of copper strips
(1) Control the concentration of acid during pickling. In the case of washing away the oxide layer on the surface of the annealed copper strip, a high acid concentration does not make any sense. On the contrary, if the concentration is too high, the residual acid attached to the surface of the copper strip is not easy to wash off, and it accelerates the pollution of the cleaning water, causing the concentration of residual acid in the cleaning water to be too high, making the cleaned copper strip more likely to change color. Therefore, when determining the concentration of the pickling solution, the following 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 much as possible.
(2) Control the conductivity of pure water. Control the conductivity of pure water, that is, control the content of harmful substances such as chloride ions in pure water. Generally, it is safer to control the conductivity below 50μS/cm.
(3) Control the conductivity of hot cleaning water and passivation agent. The increase in conductivity of hot cleaning water and passivation agent mainly comes from the residual acid brought in by the running copper strip. Therefore, while ensuring the quality of pure water for cleaning, controlling the conductivity means controlling the amount of residual acid. According to many experiments, it is safe to control the conductivity of hot cleaning water and passivation agent below 200 μS/cm respectively.
(4) Ensure the copper strip is dry. Partially seal the coiling outlet of the air cushion furnace, and use a dehumidifier and air conditioner in the partially enclosed device to control the humidity and temperature during copper strip coiling within a certain range.
(5) Use passivation agent to passivate. Most copper processing plants now use benzotriazole, or BTA (molecular formula: C6H5N3) as a passivating agent. Practice has proven that it is an easy to use, economical and practical passivation agent. When the copper strip passes through the BTA solution, the oxide film on the surface undergoes a complexing reaction with the BTA to form a dense complex, which protects the copper matrix.
2. Solution to copper strip shear indentation
To prevent shear blade indentation, it is necessary to choose a reasonable circular knife and the outer diameter difference of the rubber stripping ring based on the thickness, softness and hardness of the strip; the hardness of the rubber stripping ring meets the use requirements of the cut strip; when cutting When the width of the strip is small, the thickness of the circular knife should be appropriately selected to increase the width of the rubber peeling ring.
