Rewinding Line

The recoiling line running speed also can affect the total friction between the strip and the roll surface. When the strip runs under a higher speed, the positive pressure of the strip on the roll surface is lower, and the gas passing between strip and roll surface in the entrance cannot be exited quickly, which can continue to accumulate with the increase of speed.  Therefore, on the one hand, the actual wrap angle between the strip and the roll surface is reduced, on the other hand, the coefficient of friction between them is also diminished. Finally, all of them results in the decrease of the whole friction, which can be represent apparently under the poor incoming plate shape. In conditions of the same initial tension of tension roller unit, the entrance roller unit with a small force has a higher slip probability than the exit one with a higher force.

The slipping of any tension roll unit will cause scratches to the surface of the strip. In the rewinding line, the light damage can degrade product quality, while the heavy one will scrap the strip. So the slipping of the tension roll unit is extremely harmful to production.

At the same time, the slipping of any tension roll unit will have a direct effect on itself, which can make the roller surface smoother and smoother. The friction coefficient diminished rapidly, so we need to regrind the roll surface and the roll usage period will be shorted. In addition, the skidding of tension roller unit can cause motor output torque to fluctuate, impact the transfer decelerator, make gear failure and defect the decelerator.

In order to prevent slipping, rewinding line diameter is selected based on the principle that no plastic deformation occurs after the strip passed through the tension roller. The max thickness of coil processing line strip is the main factor to determine the max diameter of tension roller. The phenomenon that the slipping probability of cold-rolled thin strip steel is significantly increased under the large tension roll diameter. There should be a limit to the adaptation scope of strip, the diameter of tension roller is not the bigger the better. In order to add the friction coefficient as soon as possible, we need to increase the roughness of the roll surface.

Although we cannot eliminate the slipping of tension roll through the way of improve the electrical control of tension roller unit, we can provide the reasonable and perfect electrical control method which can benefit to diminish the degree of slippage. Therefore, we can decrease the wear of tension roll, and it is helpful for us to find and correct the slipping.