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Stepanov Vadim Donetsk National Technical University Speciality: "Mechanical equipment of ferrous metallurgy plants" Master's work theme : "Theoretical research of the dynamic loadings onto roller of main mill table under rolling on blooming" Work supervisor : Dr.Ph., associate Professor of MOZCHM department Vladimir Rudenko |
ABSTRACT
URGENCY OF THE THEME
Recently, interest in problems of reliability of machines, apparatus and appliances in a variety of industries has quickened.
Originating the problem of reliability due to constant technical sophistication of equipment, increase equipment productivity, the growth of power-driven engines. The problem of ensuring high reliability becomes a crucial condition for further technical progress in any industry.
Improving the reliability of the equipment for the metallurgical industry is the actual problem.
Major blooming delays due to the low reliability of the main mill table. Particularly high proportion of main mill table’s downtimes registered in Enakievskiy and Makeyevkiy metallurgical plants. Therefore, the object of further research is selected Enakievskiy plant's main mill table.
Ensuring the reliability of equipment is one of the major challenges of modern technology.
RESEARCH PURPOSE AND TASKS
Main mill tables of blooming refer to heavy-duty machines again - the short-term mode of operation. They are in the blooming stream, so any failures resulting in downtime shop.
The purpose of the master's work is to research the interaction between the power rollers operating table with ingot in the rolling process, study the laws of failures of major elements of main mill table (rollers, bearings and fasteners covers the bearings) and develop recommendations aimed at improving the operational reliability of these details.
1. Determination indicators of operational reliability of the main elements of the main mill table (rollers, bearings and fasteners covers the bearings) basing on statistical data of its use.
2. Realization of experimental researches to determine deflections of main mill table’s roller when ingot interacting with the roller during rolling and the methodology for such research.
3. Definition of fictitious strike forces during the interaction between an ingots with the roller during rolling on the blooming.
PLANNED PRACTICAL RESULT
Identification and analysis of the indicators of operational reliability of the main elements of the main mill table in the blooming basing on statistical data on its use, realization of experimental researches to determine deflections of main mill table’s roller when ingot interacting with the roller during rolling and the methodology for such research, definition of fictitious strike forces during the interaction between an ingot with the roller - all this points, in general, will increase the efficiency of its operation in terms of production.
SCIENTIFIC NOVELTY 1. Identified and examined factors contributing to reliability and serviceability of the main elements of the main mill table.
2. Experimentally determined deflections of main mill table’s roller when rollers ingot interacting with the roller during rolling and described the methodology of this research.
3. The resulting deflection rolls made it possible to identify the actual load on the roller (force of impact). Indicators of operational reliability
An analysis of variational series shows that the failures of major components of main mill table are described by law Veybulla.
For Law Veybulla:
-mean time between failures - in Table 1 shows the average time between failures T 3 main elements of main mill tables;
Table 1- Average time between failures of major elements of the main mill tables
-probability of work - in Figure 1 shows the dependence of P (t) for the 3 main elements of the main mill tables;
Figure 1 - Graph the function P (t) for: a) rollers á) bearings â) fasteners covers the bearings
-failure - in Figure 2 shows the dependence for the 3 main elements of the main mill tables;
Figure 2 - Chart function failure to: a) rollers á) bearings â) fasteners covers the bearings
-density distribution of the probability of failures - in Figure 3 shows the dependence of f (t) for the 3 main elements of the main mill tables;
Figure 3 - Graph the function f (t) for: a) rollers á) bearings â) fasteners covers the bearings rollers
The analysis of reliability showed that the mean time between failures T (Table 1) and the probability P (t) (Fig. 1) for 3-researched details of the main mill table is very low.
Calculation of indicators repairability
Analysis of the distribution of the number of recovery in the interval shows that the restoration of the main mill table’s roller described by law Veybulla. Parameters of the law: a = 64,39; b = 3,29.
For Law Veybulla:
-average recovery time - t = 57,75 min;
-probability of recovery - in Figure 4 shows the dependence Pv (t) for the main mill table’s rollers;
Figure 4 - Graph the function Pv (t) for the rollers
-intensity recovery - in Figure 5 shows the dependence M (t) for the main mill table’s rollers;
Figure 5 - Graph the function M (t) for the rollers
-density recovery function - in Figure 6 shows the dependence f (t) for the main mill table’s rollers;
Figure 6 - Graph the function f (t) for the rollers.
Analyzing the performance reliability and maintainability come to the conclusion that the low time between failures considered basic elements of the main mill tables and a significant recovery time indicates a poor design of these components, reducing the overall reliability of the main mill tables. In order to determine the reasons for the low reliability realized experimental researches to determine the actual load on the wheel main mill table’s roller in the rolling process.
CONCLUSIONS
During implementation of master's work its purpose has been realized and the put tasks of research have been decided, such as:
1. Identified and assessed indicators of reliability of the main elements of the main mill table (rollers, bearings and fasteners covers the bearings) basing on statistical data on its use.
2. Carried out experimental researches to determine deflections of main mill table’s roller when rollers ingot interacting with the roller during rolling and the methodology for such researches.
3. Determined the fictitious force of impact in the interaction of an ingot with a roller while rolling on the blooming.
Today, there are three tasks which I need to solve in my master's work, but only one of them has been resolved, the other two tasks are in the process of solving. Until December 2009 I hope to resolve them fully.
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