The characteristics of rolling mill bearings are harsh working environment, heavy workload, high unit pressure, high heat generation, and short life. It can be said that if the bearing can be used in accordance with the specification, it can completely meet the normal scrap standard. However, in the actual use process, various overload phenomena often occur, here one is human factors, the other is accident factors, and the third is equipment factors. No matter what kind of overload, it will have a relatively large impact on the bearing, and the serious one will cause an accident.
Rolling mill bearings running under overload conditions will generally cause abnormal wear and fatigue damage, and even equipment accidents such as rolling element fragmentation and instantaneous destruction of the bearing.
The overload forms of rolling mill bearing are as follows:
Stable one-way overload: For example, there are problems with the installation of parts of the transmission system of the rolling mill, and the change of the roll diameter causes the excessive deflection angle of the transmission system to cause additional load. Such loads are stable and unidirectional. This type of overload generally does not have a large overload value, but this type of overload usually takes a long time and is not easy to be found. It will only be found when there is a problem. For this type of overload, by strengthening equipment overhaul, maintenance, standardized management in accordance with equipment drawings, technical requirements, and overhaul and maintenance procedures can be avoided. The key is to strengthen the sense of responsibility of operators, maintenance, and management personnel.
Cyclic load overload: unreasonable rolling process arrangement, causing the unreasonable distribution of rolling pass processing rate; uneven bearing load distribution in each rolling pass, causing the bearing to run under heavy load for a long time. There are four reasons.
1) One is the process scheduler lacking a thorough understanding of the technical parameters and performance parameters of the rolling mill, and the planned rolling process is unreasonable, causing the rolling mill to be overloaded.
2) Second, in order to the pursuit of output, the process arrangement of high processing rate was intentionally carried out, and the bearing capacity of the rolling mill was not considered much, which caused the rolling mill to be overloaded.
3) The third is that the rolling mill operators do not operate according to the process, and they reduce the number of rolling passes during use or change the reasonable rolling process, which causes the rolling mill to overload.
4) Fourth, the rolling mill with the function of bending rolls, the bending force is too large, and the deformation resistance of the rolled piece works together on the rolling mill bearing, causing the bearing to be overloaded.
Instantaneous overload: In the rolling process, due to the occurrence of process accidents, the bearing will be overloaded instantaneously, such as rolling after the strip is broken, and the tolerance of the rolled strip is too large. For the hot rolling mill, the billet temperature is too low, overhead rolling, etc., to promote the bearing of the rolling mill to bear the concentrated overload load in a short time, causing damage and failure.
In steel rolling machinery and equipment, one-way overload or cyclic load overload occurs frequently in rolling mill bearings. These overload effects often cause local fatigue cracks in the rolling elements and cause bearing fatigue failure.
How to avoid the overload of four-row cylindrical roller bearings used in rolling mills is a key factor to improve their effective service life. Analysis from the actual use, copper processing companies are pursuing output unilaterally, causing long-term overloading of four-row cylindrical roller bearings used in rolling mills. This also requires enterprise managers to improve their understanding and strengthen management.
Please check the Product Guide to select suitable bearings for your machinery.
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