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Extend the life of rolling mill bearings

Extend the life of rolling mill bearings

2020-07-03

Large plate and strip hot (cold) continuous mills at home and abroad are equipped with a roll bending device, the common work roll bearing life is short, and even the occurrence of melting accident, so that the maintenance workload increased, the operation rate reduced, the cost increased, resulting in huge economic losses, seriously troubled rolling production.At present, it is difficult to accurately calculate and measure the load distribution of single-row rolling NSK bearings.Rolling mill bearing is a multi - row rolling bearing, due to the large load of rolling mill and small space and other conditions, bearing housing must be relatively thin structure.This special structure will inevitably make the bearing load distribution change.

        

R. L. Ebaugh and J. V. Poplawski once wrote an article on the Iron & Steel Engineer to discuss the relationship between operating conditions, maintenance and the performance of work roller bearings. They also gave the calculation results of non-contact finite element method.At present, there are few reports on measuring the load distribution of rolling mill bearing, which are mainly due to the complexity of rolling mill bearing system structure and the difficulty of measuring the working load under running conditions.The test of radial load distribution of hot rolling mill FAG bearing has not been reported.Rolling mill is a heavy-duty mechanism, so the bearing load of rolling mill should be calculated taking into account the influence of component deformation, non-uniform temperature field, clearance, impact, friction and lubrication.In some heavy-duty mechanisms or those with less rigid components, the deformation of the components will significantly affect the running behavior of the machine.

Therefore, the influence of component deformation must be included in the design of such mechanism, so that the designed mechanism can maintain the motion and bearing characteristics of the rigid component under the assumption of load state.Because the roll is elastomer, bending under load is inevitable, so the work roll bearing of the traditional four-high mill has serious off-load behavior.This problem has not been paid enough attention for a long time, which leads to the loss of low bearing life, abnormal burning and fatigue spalling.After more than ten years of exploration, we have reformed the bearing restraint mechanism of rolling mill by using the comprehensive self-aligning theory of rolling mill, and solved the bearing burning problem of rolling mill fundamentally.

A new way has been created for the study of the load-sharing characteristics of multi-row bearings, which provides conditions for improving the design technology of large rolling mill and the production quality of rolling mill.Theoretical analysis and field test results fully verify the rationality and correctness of the adaptive load-sharing device.A new way has been created for the study of the load-sharing characteristics of multi-row bearings, which provides conditions for improving the design technology of large rolling mill and the production quality of rolling mill.

 

This research is aimed at extending the bearing life of rolling mill, including theoretical research, engineering test research and rolling mill bearing adaptive load sharing.

At the national Ministry of Science and Technology, department of Shanxi Province and baosteel project support, completed the roll bearing and the heat and force analysis of the bearing, rolling mill work roll bearing delicate new theoretical research, bearing and axial fixation device structure design, bearing and axial fixation device structure design, the bearing and bearing load distribution and temperature distribution in the theoretical research, experimental research and industrial inspection, etc.Innovative achievements have been made in the following aspects.

 

(1) Analyze the load characteristics of the bearing under the action of the bending roll force with the special program of the THREE-DIMENSIONAL elastic friction-contact boundary element method, and analyze the thermal deformation of the bearing with the boundary element method or the finite element method. On this basis, study and find out the off-loading condition of the multi-row bearing of the working roll and the off-loading condition of each row;

(2) A new type of bearing housing constraint bar system is invented by using the rolling mill integrated self-aligning theory. Under the combined action of bending and axial force, the roller can be fixed axially and the self-aligning performance can be guaranteed.

(3) The coupling pair between the bearing seat and the roller bending plunger is developed to replace the original high-speed mechanism, which can ensure the self-positioning of the bearing seat and enhance the ability of bearing the roller bending force.

(4) Optimize the boring curve of the bearing seat, so that the clearance of each row bearing is the same after it is subjected to thermal deformation at high speed to ensure that all loads are carried.

(5) The measurement techniques of radial load, axial force of each roll of bearing, bearing seat and bearing temperature are given.

 

This study lays a theoretical foundation for solving the problem of short bearing life of large rolling mill. The results have been applied to Baosteel 2050 hot rolling mill, effectively solving the problem of short life and burning loss of rolling mill combined bearing.The comparison test on site shows that the device reduces the original offset coefficient of the combined bearing to 1.04 from 1.47.The original partial load rate decreased by more than 80%, the life of imported German SKF composite bearing increased from 3,209 hours to 10670 hours, the life of domestic tile Shop composite bearing increased from 1300h to 4120 hours, in order to achieve significant economic benefits, and for China to achieve the realization of large plate and strip mill complete set of equipment domestic significance.


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