What operating behaviors will cause the backup roll to overload?

Improper setting of rolling parameters

Excessive rolling force

• Blindly increasing the rolling force without understanding the characteristics of the strip material and the load-bearing capacity of the roller is a common cause of overload operation.

  For example, when the operator wants to quickly roll a thick strip into a thin strip, if the parameters are not set according to the yield strength of the strip material and the rated rolling force of the strip roller, but the rolling force is excessively increased, the strip roller will be subjected to pressure far exceeding its design capacity. This may cause excessive elastic deformation or even plastic deformation of the roller, which will damage the shape accuracy of the roller and also increase the wear of the roller surface.

Rolling speed is too fast

• There is a correlation between rolling speed and rolling force. If the rolling speed is too fast, a large friction will be generated between the strip and the strip roller. In order to maintain the stable rolling of the strip, the rolling force often needs to be increased accordingly.

  For example, during high-speed rolling, the forward and backward slip of the strip will be more obvious, which requires a higher rolling force to overcome this phenomenon, which can easily lead to overload of the strip roller. Moreover, too high a rolling speed will also cause a sharp increase in the heat generated during the rolling process, resulting in thermal expansion of the roller body, further increasing the pressure on the roller body.

Improper tension control

• When the tension of the strip is set too high, additional pressure will be generated on the strip roller.

  For example, in a continuous rolling production line, if the tension between the front and rear tension rollers exceeds a reasonable range, the strip will be pressed tightly against the strip roller, resulting in an increase in the radial pressure on the strip roller.

  This excessive tension may also cause uneven distribution of friction between the strip and the roller body, excessive local pressure, causing local overload of the strip roller, and causing problems such as excessive wear and deformation of the roller body.

Improper handling of equipment failure or abnormal situations

Strip deviation

Strip deviation is a common problem in the rolling process. When the strip deviates, the strip will produce uneven pressure on one side of the roller.
If the operator does not find and correct the strip deviation in time, this uneven pressure will continue to act on the strip roller, causing local overload.
For example, if the strip accumulates on one side of the roller, the pressure on the strip roller on that side will be much higher than the pressure during normal rolling, which will cause local deformation and increased wear of the roller.

Foreign matter enters the rolling area

When foreign matter (such as metal chips, tools, etc.) enters between the strip and the strip roller, the rolling force will increase instantly.

If the equipment is not equipped with effective foreign matter detection and protection devices, or the operator does not stop the machine in time after discovering the foreign matter, the strip roller will be overloaded under the action of the foreign matter. This overload may be a short but strong impact, which will cause damage to the roller body, such as pits or cracks on the roller surface.

Unreasonable production plan arrangement

Continuous rolling of strips exceeding the load-bearing capacity:

• In production arrangements, if the strip rollers are allowed to continuously roll strips that are too thick, too hard, or too wide without considering the bearing capacity of the strip rollers, overload operation will occur.

  For example, if the strip rollers are arranged to continuously roll ultra-thick high-strength alloy steel strips without proper equipment adjustment, the strip rollers are prone to fatigue damage under long-term high loads, because this high-intensity rolling task will keep the strip rollers in a high stress state, exceeding their normal working range.