1.The influence of raw materials
A. Electrolytic copper cathode
It is the production of qualified by the quality of copper cathode oxygen free copper rod is the most critical factor, as stipulated in the production process: used in the manufacture of oxygen free copper rod copper plate must conform to the standard specified in GB/T467-1997 NO. 1 technical requirements of cathode copper. If the copper surface is copper bean (including S/H) and patina (CuSO4 · 5H2O), copper plate in the process of smelting, along with the rise of temperature will break down the H2 and O2 and S and a large amount of dissolved in molten copper, when into a bar and precipitation formation porosity. Therefore, under the standard of electrolytic copper can continual production.
B.Recycled copper scrap wire
For copper scrap from the factory production line, must be attached in front of the melting into the rubber, plastic, paper, silver plated copper wire, tin copper wire, steel wire and aluminum wire and other mixed material picking clean.
Because the smelting process itself can't reduce the impurity content, so the copper scrap wire before charging must be dry, clean, shall not be attached to the surface oil, emulsion, water, oil to pick away, there are water must be dry before charging, otherwise the impurity copper rod charging once into copper smelting to produce harmful impurities and gas liquid, lead to crystallization of copper rod resistivity exceeds bid, the precipitation gases "hollow" rod or shrinkage cavity.
2.The influence of coating agent
At present, charcoal is covering the surface of copper liquid, and a better option is flake graphite, mainly used to restore degassing, get rid of copper liquid oxygen, charcoal carbon and oxygen generation oxidation, into a gas, and achieve the goal of oxygen, charcoal also have the function of the isolation air and heat preservation, avoid copper liquid hydrogen and oxygen from the air.
But if the poor quality of charcoal and damp, not bake charging, can make the charcoal in the harmful material such as hydrogen and oxygen into the molten copper, copper rod causes porosity, so the quality of the charcoal must conform to the requirement of production technology, charcoal must pass a size selection before charging, purification and then to bake .
3. The influence of the production equipment
On combination furnace, induction furnace is commonly connected by melting furnace, let stand transition positions and holding furnace of three parts, but I plant no. 3 on the engine of induction furnace only two parts namely the melting furnace and the holding furnace, look from the usage of these years, the probability of the machine in the production of copper rod in stomatal is higher than 1, no. 2 on the led machine, the study found that the problem was lack of rest transition warehouse, the result causes:
(1) temperature fluctuations. Just put in a coin, in low temperature state on one side of the melting furnace, holding furnace temperature reduced many degrees, when after a solid copper mineralization, copper water mobility increases, copper liquid temperature follow increase, the formation of stable crystal copper rod environment adverse, crystalline state performance along the length direction of the copper rod is inconsistent;
(2) for copper water purification. So-called purification, including two aspects: one is the precipitation of the gas, the second is suspended impurities. Gas mainly comes from electrolytic copper, charcoal and furnace gas, besides some few harmful gas sulphur, phosphorus 02, H2, H20 is the main, if supersaturated precipitation in the center of the copper rod, form the "hollow", so the purpose of setting transition warehouse so that I can have more time to complete degassing of physics, chemistry.
To compensate for congenital deficiency lead machine furnace in no. 3, in the operation to do a few job: 1) increasing the furnace slag removal, in carbon number, to ensure that the cover agent not failure; 2) pay attention to the balance charging, decrease of copper liquid temperature fluctuations; 3) with or without packaging waste copper line charging as little as possible, to cut copper scrap wire.
4.The influence of process parameters
Furnace temperature, cooling water flow and guide rod speed is of the three factors directly affect the quality of copper rod.
A.the furnace temperature
General requirements, the temperature of the melting furnace for 1175 + 5 ℃, the temperature of the holding furnace for 1145 + 5 ℃, in actual operation, are generally control the temperature of the furnace, if the copper liquid temperature is exorbitant, copper rod is bulky, its organization is loose easily produce the defects such as shrinkage cavity, also easy to absorb hydrogen and oxygen from the air; Copper liquid temperature is too low, copper liquid illiquid, copper rod appearance is easy to produce the defects such as cracks and cold insulation. Therefore control the furnace temperature is the key to lead good copper rod, pay special attention to the balanced charging operation.
B.cooling water flow rate
If mold water temperature is too high and the traffic is too hours, will lead to bad copper liquid cooling, crystallization uneven, high temperature, easy oxidation and produce the hollow copper rod rod. In daily production, copper liquid temperature and basic guide rod speed is constant, the operator only adjustable is the water pressure and water yield. So adjust water pressure and flow is the precondition of good casting rod, according to the different season, different inlet water temperature to adjust water pressure and flow, and often should check whether the copper rod surface and the water temperature is normal.
C.the guide rod speed
Guide rod speed must be with copper liquid temperature, cooling intensity, such as in the case of other conditions must, fast guide rod, copper rod is bulky, osteoporosis, processing performance is bad, the formation of shrinkage; Slow guide rod, copper rod is easy to produce surface crack, and low production, can't play equipment production effect.
5.Operator precautions
A.Do daily maintenance of the mould on a regular basis. Descaling cleaning, to ensure that waterways are clear.
B.electrolytic copper charging must be clean before, first on the chamber of a stove or furnace baking hot, remove moisture, electrolytic copper and copper scrap process was not alignment pole are strictly forbidden to charging.
C. charging should be balanced, less frequently, and keeping the temperature constant copper liquid level is stable, and join the COINS or recycled copper scrap material, can't float on the surface of copper liquid, to timely pressure into the molten copper sticks.
D.must be baked before charging, charcoal, charcoal layer must be tightly, and keep enough thickness, avoid copper liquid inhalation of oxygen and hydrogen in the air.
E.slag removal in carbon must be carefully according to the process standard operation, avoid molten copper exposed to breathe in the air.
F. remove slag furnace wall hanging on a regular basis, prevent harmful substances into the copper liquid again.
G.To pay attention to the quality of copper rod, at any time of copper liquid surface height and charcoal cover and the change of process parameters. If discover the quality of copper rod exception, should take timely measures to dispose of.
To sum up, the oxygen free copper rod porosity is caused by the comprehensive factors, any negligence in production each link will cause porosity, cannot say which link is particularly important, can only say that none of the link is not important. From raw material, process, equipment, environment, personnel quality, various aspects have ample guarantee, can reduce the pores to produce copper rod. So now what we should focus on the following link? According to me over the past few years on the top of the copper rod production, product quality tracking, and recycled waste copper wire packaging before picking, classification, processing and "copper scrap packaging process quality control regulations" requirement is still a gap. Is of great importance to strengthen its management perfect, believe in our joint efforts, the guide of oxygen free copper rod quality will be improved gradually.
