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ÓÊÐÀÈÍÑÊÈÉ | |
RUSSIAN |
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Krivoplyasov Eugenij Leonidovich
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Actuality
There are a lot of derangements in today’s metallurgical equipment as in any other equipment as well. The most common error reasons (more than 50% of the total figure) are lubrication problems. Severe mechanical equipment blocs operating conditions at the present time (high dust condition, temperature) forces to look for new quality improving pathways and necessary lubrication material properties, right choice of which has a direct effect on availability and durability of the lubricating equipment’s unit work. Theoretical and practical investigations showed that the right choice of the type of the lubrication system and its quantity allows to prolong the mechanical and service life of the equipment which in its turn minimizes repair expenses and increases profits. Purpose and objectives of the work
Purpose of this work is motion study of lubrication in bearing blocs of the metallurgical equipment. One of the aims is to define the properties and conditions of lubrication in bearing blocs. Knowing properties of the material directly in the bloc and conditions of work allows improving conditions and prolonging life of the equipment, to increase service safety and easy maintenance operation. Aims: 1. To determine service properties of modern viscous lubrication. 2. To examine constructions and parameters of the work of the bearing blocs. 3. To calculate motion study of lubrication in bearing bloc. 4. To work out the rules of choice and proportion of needed amount of lubrication. 5. To find rational method of lubrication supply (frequency, replacement age, direction and quality). Scientific originality
Earlier used lubrication gave place to modern one which is more qualitative. This fact is a basis for changing of the existing norms of proportions and methods of the material feeding in bearing blocs of the metallurgical equipment. Performed calculations and the results of theoretical and practical investigations will help to understand better the whole scheme of the work of the bearing bloc with viscous lubrication usage in difficult conditions of metallurgical equipment work. There will be worked out complex approach on evaluating the bearing bloc status on the basis of the analysis of the used viscous lubrication.
Characteristics figures
I its properties viscous (consistent) lubrication take middle position between solid lubrications and oils. Basically lubrications consist of two components: low-viscosity origin (mineral, plant oil, synthetic oil and other oils) and gelling agent (solid hydrocarbons, high molecular weight fatty acid salts – soaps, finely divided silica gels and bentonites, other products of organic and nonorganic origin). Besides they have in its composition admixture which improves operational characteristics. Lubrication may also have compounds: graphite (mineral carbon), molybdenum disulfide, powdered metals or its oxides, mica and others. Gelling agents, to be more precise, soaps in the process of preparing of lubrication build its tridimensional structural frame where oil is hanged on. Thank to structural frame and not at full load lubrications behave as solid bodies (don’t flow under own weight, remain on leaning and vertical planes) and under critical loads which overcome the structural frame strength they flow like oil. Basic lubrications advantages are: ability to keep in non tight friction units, efficiency at wide temperature and speed range, better lubricating, higher corrosion protective properties, efficiency with the water contact and other aggressive media, high economical usage. As for negative lubrication points: bad cooling ability, more high corrosion ability, difficult supply to friction unit. Knowing lubrication abilities and properties, identifying job conditions and motion pair construction one can choose lubrication for concrete friction unit.
Mechanical stability
Volume and mechanical properties changes, for example ultimate resistance, machining job results and the following rest are called mechanical lubrication constancy. Mechanical stability is an important performance criterion of the features of lubrication which is used in junctures, plate bearings, friction bearings because in this case all lubrication supplies are involved. Unstable mechanical lubrication, in other words strongly destroyed and not restored starting qualities after deform load will leak from this friction unit and will bring to early damage. Mechanical stability is specified by All-Union State Standard (GOST) 19295 - 73
Colloid stability
Lubrication ability to keep oil in its structural frame units under the influence of the outside forces is called colloid stability. Colloid stability is determined by All-Union State Standard (GOST) 7142 – 74 in percentage terms evolved oil. Colloid stable lubrication cannot bleed oil when it is kept and used for a long time. Exudation of oil from lubrication during the work in the friction unit is always useful because it provides better lubrication conditions of the rubbing parts. However too high exudation of oil from lubrication (low colloid stability) will bring to oil discharge from friction unit and appearing set body gelling agent in it that is the break of lubrication rate. Potential evaporation is determined by All-Union State Standard (GOST) 9566 – 74 in percentage terms of vaporous oil under certain temperature in strict specified time. Oil loss because of evaporation rises gelling agent amount in lubrication and agreeably rises its ultimate resistance, viscosity and changes of the other lubrication service properties
Lubrication film loading capacity
The notion loading capacity (efficiency) of the lubrication film is closely connected with the friction and run-out questions so with the laws which they obey. This is very important work material lubrication characteristic cumulating set of features which are determined in the contact of the borderline oil film with metal surface that is in boundary friction conditions. Here lubrication film critical destruction temperature, critical pressure which it can stand, it's plasticization effects, adhesion forces, antifriction and antiwear properties, antiwelding properties are taken into account. Considering that lubrication have surfactant materials their lubricating ability is higher than oils on which they are made apart special additives. Lubrication film loading capacity borderline lubrication is tested on friction and run-out including evaluating method of antiwear and antiscuff characteristics on friction four-ball machine FBM – 3 on All-Union State Standard (GOST) 9490 - 75.
Content of mechanical impurities
Content of mechanical impurities in lubrication is determined in several ways on All-Union State Standard (GOST) 1036 – 75, diluting lubrication in hydrocarbon solvents with the next filtration of solvents and mud weighting at the filter. In this case it is allowed for different lubrications filtrated mud content no more than 0,1-0,5%; All-Union State Standard (GOST) 6479 – 73 provides determination of content of mechanical impurities not dissolved salt acid, presence of this impurities is not allowed as a rule. According to All-Union State Standard (GOST) 9270 – 59 with the scope in the light lubrication film on the glass determine amount and size of the foreign impurity. The first two methods are used to mark general-purpose grease and the last – to determine lubrication mechanical impurities which are used in precision friction couple, instrumental bearings etc.
Viscous lubrication units constructions
One defines lubrication with constant lubrication for the whole bearing working time and that one with periodically added and changed lubrication. In the first case lubrication life time is equal or bigger than the bearing working time or machine maintenance cycle with erected bearings into it. To this lubrication type belong closed bearings filled with viscous lubrication. (Drawing 2) Drawing 2 - closed bearings filled with viscous lubrication (viscous lubrication with a red).
In capacity of standard lubrication for closed bearings lithium gelling agent and lubricating mineral oil with NLGI 2 or 3 consistence viscous lubrications are used to provide work at temperature -20 ... 100 ?Ñ. In case of special conditions operation task-specific viscous lubrications are used. If closed bearing works under hard conditions (high temperature, water and dust) it is reasonable to use not only task-specific viscous lubrications but also intensified build in sealer constructions otherwise foreign material composition will strongly reduce standard viscous lubrications working time. Viscous lubrication feed in bearing unit and position inside the unit is an important component of powerful lubrication. Inner bearing unit construction plays main role here. Drawing 3 – Special side plate with increased blister for lubrication
The usage of side plate (Drawing 3) from the side of external seal creates increased lubrication blister to supply good bearing security from outside poisoning and longer working period without maintenance support. Drawing 4 - Viscous lubrications holding in bearing units with vertical shaft.
Conclusion
There was made the analysis of existing lubrications and bearing units’ constructions during execution of work. There was viewed viscous lubrication behavior in the bearing unit of the metallurgical equipment in connection with stagnant zone formation. As a result portion for lubrication usage recommendations and means of lubrication supply in the bearing unit steps will be taken.
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