After the wire rod or the intermediate wire billet is chemically descaled and coated, it needs to be heated at low temperature and dried in order to remove hydrogen and moisture. The temperature should not be too high to prevent failure of the lubricating coating. Dehydrogenation is to eliminate the hydrogen that has penetrated into the steel base during the pickling process. The purpose is to eliminate hydrogen embrittlement and restore the plasticity of the wire rod. The purpose of removing moisture from the surface of the wire rod and making it dry is to prevent moisture from deteriorating the effectiveness of the lubricant. There are three kinds of drying boxes in common use, which are boxes with upper lids, and their effective size is determined by the maximum diameter of the wire reel. When working, the box is filled with hot air of 150~250℃. The drying speed of this kind of equipment is relatively fast, the time is about 2~15min, and the drying is relatively uniform. The tunnel drying furnace relies on the combustion chamber under the furnace to provide the heat source, and the temperature of the drying chamber can reach about 280°C. The bottom of the furnace is covered with trolley tracks and arched cast iron radiating fins.
The dried wire rod or intermediate wire billet is hung on the trolley with the aid of a hanging bar, and is fed into the furnace by a hoist or manually. Each furnace can be loaded with 10-12 trolleys. This equipment has a large capacity and a high output, but the labor intensity of the workers when entering and exiting the trolley is greater, and the drying temperature is uneven, and the temperature at the bottom of the trolley is relatively high. The bottom of the chain drying furnace is a combustion chamber, and the flame can return from the bottom to the furnace walls on both sides and then run out through the flue.
The furnace temperature is 200~400℃. When drying, the wire rod is placed on a moving chain, and the moving speed of the chain is about 12m/min. This is a more advanced furnace type with large capacity, high speed and high output, and it overcomes the labor intensity of tunnel furnace workers. The disadvantages of large and uneven drying temperature. Coating treatment is to coat the surface of the wire rod or intermediate wire blank after the oxide scale has been removed with a firm layer that has a certain lubricating performance, especially the substance that can effectively absorb and carry the lubricant into the deformation zone during drawing.
