The role and size of cold rolling tension are determined
1, the role of tension
The function of tension is to reduce the unit pressure, so that the stress state in the deformation zone changes, and the longitudinal compressive stress is reduced, so that the unit pressure is reduced during rolling.
The strip thickness can be controlled by adjusting the tension. The rolling thickness is changed by changing the tension. If other conditions do not change, increasing the tension can make the strip thinner.
Prevent strip deviation and ensure rolling stability. The reason of strip deviation in rolling is that the strip has uneven extension in the width direction. When the rolled parts have uneven extension, the tension distribution along the wide direction will change accordingly, the tension of the part with large extension will decrease, and the tension of the part with small extension will increase, resulting in the tension playing an automatic correcting force. Good synchronization of tension correction and no control lag. The disadvantage of tension correction is that the change of tension distribution can not exceed a certain limit, otherwise it will cause edge splitting, bending and even broken tape.
2. Determination of tension size
The determination of the tension size depends on the rolling conditions of different metals, but the maximum tensile stress value can not be greater than or equal to the yield strength of the metal, otherwise it will cause plastic deformation of the strip outside the deformation zone, or even break the strip. Disrupt the rolling process or deteriorate the quality of the product.
Reduce the rolling pressure, the back tension is more significant than the front tension, but too much tension will increase the load of the main motor, such as the incoming material loose will cause scratches. On the contrary, when the back tension is less than the front tension, the load of the main motor can be reduced. On the four-high reversible strip mill, where the shift of the work roll from the support roll is small, the back tension is less than the front tension, which is conducive to the stability of the work roll during rolling, can make the deformation uniform, and has a significant effect on the shape control. However, excessive front tension will make the strip roll too tight, which is easy to produce bonding during annealing and easy to break the strip during rolling.
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