Thin-gauge steel strip thickness fluctuations Causes and Control
Manufactures thickness of 0.3 mm or less thin gauge steel, finished there will pass rolling force, thickness fluctuation is large, analysts believe that the reason there is a new work roll diameter, short time as well as hot rolls emulsion performance variation coefficient of friction caused between the work roll and the strip increases, the rolling force increases.
This control measures are:
1, rolling schedule
Compression rolling passes, reducing the deformation resistance due to work hardening caused by the rolling force increases Finished passes lead to increased volatility thickness.
In addition the finished pass reduction rate of about 25% to over 30%, and when finished rolling passes to manually add coiling tension to compensate for insufficient reduction rate adjusted to ensure that the finished product to the target pass rolling thickness.
Second, direct-liter vehicle speed after start rolling, to improve emulsion lubrication conditions, increasing fuel and oil film thickness between rolling rolls and strip, Mocha coefficient is reduced, decreasing the rolling force, to reduce the thickness fluctuations.
2, the emulsion
1) increasing the concentration
The concentration of emulsion was increased from 2.5% to about 4%, is increased during rolling rolls and the strip of film thickness effective contact area, improve lubricity, reduce the rubbing coefficient, thereby reducing the rolling force, improve the thickness fluctuation.
2) increase the heating temperature
The normal production of the mill when the emulsion is heated by a temperature 50 ~ 55 ℃, increased to 55 ~ 60 ℃, in order to accelerate the velocity of the emulsion droplets molecules, molecular aggregation of oil droplets is increased, to improve the lubrication conditions.
3) Reduce ESI
By adding an acidic additives, pH control emulsion at 5 to 5.5, so that the rolling oil particle size tends to increase, decrease the stability of the emulsion, so ESI from 60% to 80% to 40% to 60%, thus improve water separation, improve lubrication conditions.
3, roll quality
The work roll diameter, roll surface roughness and thermal crown to adjust:
1) Priority small roll diameter work roll. Optimal allocation through rollers, try to arrange small roller diameter (<360 mm) work roll production of thin gauge strip 0.3 mm or less.
2) reduce the work roll surface roughness. The roll surface roughness is reduced by the 0.8 ~ 1.0 μm to 0.4 ~ 0.6 μm.
3) increasing the work roll hot roll time, the roller surface heat evenly crown. For 360 ~ 385 mm roll diameter work roll appropriate to increase the hot rolling roll material. Before rolling hot roll material is 0.3 mm or less rolling thin gauge strip, first rolled strip 2,3 volume above 0.6 mm, so that the work roll surface and roll body heat permeability uniform, to ensure the effective reduction efficiency, resolve When the roll is pressed against the effective rolling force reduction issues.
