After chemical descaling and coating treatment of wire rod or intermediate billet, it is necessary to heat the hydrogen and moisture to dry at low temperature. Drying temperature is generally%26lt;300℃, the temperature should not be too high, to prevent lubrication coating failure. Hydrogen removal in the process of pickling to break into the steel-based hydrogen, the purpose is to eliminate hydrogen embrittlement, restore the plastic rod. Remove the water on the surface of the wire rod to make it dry, in order to prevent moisture deterioration of the use of lubricant effect.
There are 3 types of drying facilities commonly used:
Drying box. For a box with a lid, the effective size is determined by the maximum diameter of the reel. When working, the box is 150~250℃ with hot air.
This kind of equipment dries faster, time is about 2~15min, drying is more even.
Tunnel type drying furnace. By the combustion chamber under the furnace to provide a heat source, the temperature of the drying chamber can reach about 280 ℃. The bottom of the furnace is covered with a trolley rail and an arched cast iron heatsink. The drying wire rod or the middle line billet is hung on the trolley by means of a hoist or manually fed into the furnace. Each furnace can be loaded into a 10~12 trolley.
This equipment has a large capacity, high output, but the workers in and out of the car labor intensity, and drying temperature is uneven, the bottom of the car temperature is high.
Chain-type drying furnace. The bottom of the furnace is the combustion chamber and the flame can be returned from the bottom to the side of the furnace wall and then run out through the flue. The furnace temperature is 200~400℃. The wire rod is placed on the moving chain when drying, and the movement speed of the chain is about 12m/min.
This is a more advanced type of furnace, large capacity, fast speed, high yield, at the same time overcome the tunnel furnace workers labor intensity, drying temperature uneven shortcomings. Coating treatment is to be removed from the oxide sheet or the middle of the surface of the billet coated with a solid layer by itself has a certain lubricating properties, especially drawing can effectively adsorption and carrying lubricant into the deformation zone of the material formed by the film%26mdash; coating. So the coating is essentially the carrier of the lubricant (see lubricant carrier). The purpose of the coating is to create good lubrication conditions for drawing to reduce friction and heat in the drawing process.
The treatment method includes two kinds of physical and chemical methods, the main forms are dip lime, yellowing, phosphating, copper plating, borax treatment, etc.