The impact of rolls on product quality in the production of plate and strip steel, roll technology

What are the reasons for sticky roller

The sticking roller is caused by excessive local pressure, broken strip fragments and folded strip steel entering the rolling mill.Generally, the slightly sticky roller can continue to be used after manual grinding with grindstone. When the strip surface is high, the roller must be changed.

What are the material requirements for cold rolling rolls?

In the process of cold rolling, the surface of the roll is subjected to great extrusion and strong wear.Steel jamming and over-burning during high speed rolling will cause cracks on the roll surface.Therefore, the work roll of the cold rolling mill should have high and uniform hardness, a certain depth of hardened layer and good wear resistance and crack resistance.The good overburning resistance and crack resistance of the roll are the main factors to prolong the roll life.

What are the effects of insufficient roll hardness on the rolling process?

Roll hardness is not enough, rolling elastic flattening, roll and strip steel surface contact area increases, to obtain the same thickness of the product, must increase the rolling pressure, and rolling pressure is bad for the adjustment of the shape.When the roll roughness is large, the friction coefficient between the roll and the strip steel surface increases, resulting in the increase of friction force and the increase of rolling pressure.

How to eliminate "side wave" and "middle wave" by bending roll?

When there are waves on both sides of the strip in the rolling process, it means that the rolling pressure on both sides of the strip is too large. At this time, the positive bending roll is applied to eliminate the waves on both sides. When there are waves in the middle, it means that the original crown or thermal crown of the roll is too large, and the negative bending roll is used to eliminate the waves.

How to prevent the belt running off the track?

First of all, before wearing the belt, we must correct the pressure, give a good roll gap, see the quality of incoming material, whether there is a side wave, observe the operation of strip steel.If you find that you are running off track, adjust the pressure in time. If you run off track too fast, stop quickly.In the rolling process, strip running off-track generally occurs when the strip is worn or the tail is thrown off. The main reasons for strip running off-track are as follows:

1)due to the reason of the incoming material sheet shape is not good, there are serious side waves, so that the strip edge control device can not be accurately and timely effective adjustment, resulting in the first strip running off, take measures is not too high rolling speed, timely adjust the pressure swing adjustment or timely stop.

2)Operation reasons due to the operation of pressure swing adjustment is not reasonable, resulting in strip running deviation.

3)due to the sudden decrease or disappearance of the coiler tension in the rolling process, the strip runs off track and breaks the belt.

4)because of the serious taper of the roller after grinding, the pressure can not be found, which increases the difficulty for the operation of the pressure swing in the rolling. The light one will produce serious side waves resulting in plate defects, and the heavy one will cause the running deviation of the broken belt.

5)The failure of strip edge control device, running deviation device, lamp tube or receiving device pollution, etc., causes the failure of running deviation device and causes the first running deviation.

What quality defects will appear in roller grinding?What adverse consequences will occur in the rolling process?

1)Roller body taper: resulting in pressure can not be corrected, and easy to cause side waves, plate shape is difficult to control, the roller taper is less than O.1mm.

2)Grinding is not round: the roller body has ellipticity.In the process of rolling vibration, rolling pressure fluctuation, strip thickness along the length of the wavy change.

3)Convex: the roll is required to be flat in the process of the unit. If the roll has a crown, it is easy to produce middle wave and second rib wave of strip steel in the rolling process

4)The surface roughness of the roller is too large.During the rolling process, the rolling pressure increases, the strip shape is difficult to control, and the surface quality of strip steel is affected.

5)Roller body crack, because the crack is not cut, grinding clean.In the rolling process, the surface of strip steel produces protruding rolling marks with the shape of cracks without flaw detection on the roll.

Cause of roll breaking

1)Roller manufacturing reasons: Roller neck itself has defects, in addition to the part of the maximum torsion.Broken roll generally occurs in the neck of the roll

2)The broken roll is caused by the broken roll: the broken roll is caused by the broken roll in the high rolling force and high speed rolling.The broken roll is located in the burst part.

3)Roller breaking due to operation reasons: deflection under pressure and force on one side of the roller.Easy to cause the roll in the neck of the roll fracture.

The End.