Some people find that there are pores formed when using the upward drawing method to produce copper rods. Once there are pores, it will have a significant impact on the quality of the copper rods. So, what are the factors that cause copper rod pores and their solutions?

Reasons and solutions for the formation of air holes in copper rods

1. Covering agent issue

The covering agent is generally charcoal, which covers the surface of copper liquid in the furnace. Its main function is to reduce and degass, remove oxygen from the copper liquid. The combination of charcoal and oxygen generates carbon oxide, which is converted into gas for elimination, thus achieving the purpose of deoxygenation. At the same time, charcoal also has the function of isolating air and insulation, preventing copper liquid from absorbing oxygen and hydrogen from the air. If the quality of charcoal is poor and humid, and it is not baked into the furnace, it will cause harmful substances such as hydrogen and oxygen in the charcoal to enter the copper liquid, causing copper rods to produce pores.

Solution: The quality of charcoal should meet the production process regulations, and the particle size should be selected before entering the furnace. After purification, it should be baked for backup.

2. Reasons for production equipment

The upward induction furnace is generally composed of a melting furnace, a stationary transition chamber, and a holding furnace. However, some induction furnaces do not have a stationary transition chamber and only have the other two parts, which can lead to:

(1) Large temperature fluctuations

When a copper plate is first placed, the melting furnace is in a low-temperature state, and the insulation furnace will correspondingly decrease by a few degrees. When the solid copper is melted, the fluidity of copper water increases, and the temperature of copper liquid also increases. This is not conducive to the formation of a stable copper rod crystallization environment, and the crystallization state performance of the copper rod is inconsistent along the length direction.

(2) Not conducive to copper water purification

The purification of copper water is not only the precipitation of gases, but also the suspension of impurities. The gas mainly comes from electrolytic copper, charcoal, and furnace gas. Except for a small amount of harmful sulfur and phosphorus gases, 02, H2, and H20 are the main ones. If supersaturated, they will precipitate at the center of the copper rod, forming a "hollow". Therefore, the setting of the transition chamber is to have more time to complete the degassing reaction.

Solution: It is possible to increase the frequency of slag cleaning and carbon replacement in the furnace appropriately to ensure that the covering agent does not fail; Pay attention to balanced feeding to reduce the fluctuation of copper liquid temperature; Less or no need to pack waste copper wire into the furnace, cut waste copper wire can be used.

3. Raw material issues

(1) Cathode electrolytic copper

The quality of electrolytic copper is a key factor in the production of oxygen free copper rods. Generally, according to the production process regulations, the copper plate used to manufacture oxygen free copper rods must meet the technical requirements of No. 1 cathode copper specified in the GB/T467-1997 standard. If there are copper beans and copper green on the surface of the copper plate, it will decompose into H2, O2, and S with the increase of temperature and dissolve in a large amount in the copper liquid. Then, when crystallized into rods, it will precipitate and form pores.

Solution: When selecting raw materials, it is important to pay attention that electrolytic copper below this standard cannot be used for production.

(2) Returned scrap copper wire

The content of impurities cannot be reduced in the smelting process, so the waste copper wire must be dry and clean before being put into the furnace, and the surface must be free of oil, moisture, lotion, etc. Once the harmful impurities and gases produced by melting the soft and dirty waste copper rod into the furnace are dissolved in the copper liquid, the resistivity of the crystallized copper rod will exceed the standard, and the released gas will form a "hollow" rod or shrinkage cavity

Solution: When selecting waste copper wire, select and remove any oil stains, and dry any moisture before entering the furnace.

4. The reason for the speed of the guide rod

When other conditions are constant and the lead speed is fast, the copper rod crystallizes coarsely, has a loose structure, poor processing performance, and is prone to forming shrinkage pores; When the speed of the guide rod is slow, the copper rod is more prone to surface cracks, resulting in low production and inability to fully utilize the production efficiency of the equipment.

Solution: Therefore, the speed of the guide rod needs to match the cooling strength and copper liquid temperature.

5. Reasons for cooling water flow

If the inlet temperature of the crystallizer is too high and the flow rate is small, it will lead to uneven crystallization, poor cooling of the copper liquid, high temperature of the copper rod, easy oxidation, and the formation of hollow rods.

Solution: In production, the temperature of the copper liquid and the speed of the guide rod are basically unchanged, and the staff only need to adjust the water pressure and water output. The water pressure and quantity should be adjusted according to different inlet temperatures and seasons, and the surface and outlet temperature of the copper rod should be regularly checked for normal operation.

6. Reason for furnace temperature

The general furnace temperature requirement is 1175 ± 5 ℃ for the melting furnace and 1145 ± 5 ℃ for the holding furnace. During operation, the temperature of the holding furnace is usually controlled. If the temperature of the copper liquid is too high, the crystallization of the copper rod will be coarse, the structure will be loose, and it is easy to produce shrinkage holes, as well as absorb hydrogen and oxygen from the air; If the temperature of the copper liquid is too low, its fluidity will be poor, and the appearance of the copper rod is prone to defects such as cracks and cold shuts.

Solution: The key is to control the furnace temperature well, and also pay attention to balanced feeding during operation.

The above is the answer to the question of what factors cause copper rod porosity. After the above introduction, it can be seen that the main causes of copper rod porosity are covering agents, production equipment, raw materials, rod speed, cooling water flow rate, furnace temperature, and other reasons. If we encounter copper rod porosity, we should promptly find the cause and solve the problem based on the specific reason. We can also learn to avoid copper rod porosity in advance.

Article source: Internet

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