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SEALING UNITS OF SUPPORTS WITH ROLLING BEARINGS

Modernization of existing sealing units of large-sized bearing supports (mainly for rolling mills) and development of new such units, are one of the basic directions of our works and services.

The characteristic feature of our sealing units, is the joint usage of both reinforced radial seals and nonstiffened seals of special type. These can be, for example, axial V-ring or radial outer-lip seals installed in the cover units of the bearing chocks. The main function of the radial shaft seals is to confine lubricants (packed grease or oil-air mixture) inside the chocks, while the nonstiffened seals protect them from external pollutants like water and scale.

The advantage of these units consists in assuring the effect in case of deviations in size, connected with manufacturing inaccuracies or wear-and-tear, as well as in cases of misalignment and displacement of the components of rotatory units to be tightened.

Realization of these sealing units required, as a rule, the usage of lip seals, which were absent not only in manufacture, but also in standarts of domestic seals. Therefore for the decision of problems of modernization and creation of modern sealing units we had been developed necessary lip seals and their manufacture is adjusted.

In many units we used the own-designed radial seals with the removable reinforcing rings (the PCK-tipe).The peculiarity of this seals is the augmented retaining force of elastic lips, which guarantees sealing effect even if the contact surfaces are skewed or worn. The removable reinforcing rings don't need to be replaced along with worn seals, which considerably facilitates the usage of sealing units.

The modernized sealing units have received the most widespread use in work chocks of continuous strip mills where problems of bearings service life increase and decrease in expense of greasing are especially actual.

In particular, by them are completely equipped finishing stands of the most powerful in the CIS continuous hot strip mill 2000 (in Magnitogorsk Metallurgical Works) with the lubricant system «oil-air», as well as rouphing stands of this mill, working both with «oil-air» system and with mortgage greasing.

In sealing units presented at Figure 1 the protective function is carried out with V-ring seal 2 (V3-555), established in a seating at roll 1 and contacted with the counter face of a contact disk 3 in a back cover 5. Sealing function is carried out with seal 6 (PCK 20-580), contacting directiy with the shaft of roll. The drainage of the water which have been last through seal V3-555 is carried out through a drainage hole 4 in a back cover 5. The sealing unit of a front cover used also radial seals PCK 20-580 and V-rings V3-555.

Such our seal units are successfully used, for example, at Metallurgical Enterprise «Severstal» (Cherepovets, Russia) in hot strip mill 1700, in 4-stand cold strip mill, in plate mill 5000, as well as at many other largest metallurgical enterprises of the CIS ( «Mechel», Chelyabinsk, Russia; «Illicha Works», Mariupol; «Zaporogstal», Ukraine).

Fig.1. Sealing units for the finishing stands work chocks of the hot strip mill 2000 («MMK», Magnitogorsk)

In sealing units representated at Figures 2 and 3 it is visible, that their basic structure and functioning are similar with the sealing units for the finishing stands work chocks of the «MMK» hot strip mill 2000 (fig.1) and a rational choice of lip seals and their combinations are caused in each case by dimensions and design features of work chocks units.

Fig.2. Sealing units for the work chocks of the 4-stand cold strip mill («Severstal», Cherepovets):
1 – work roll; 2 – seal V2-380; 3- seal PCK 20-340; 4 – back cover in assembly;
5 – back distance ring; 6 – front cover in assembly; 7 – seal V2-325; 8 – distance ring; 9, 10 – rubber seal rings.

Fig.3. Sealing units for the work chock of the hot stup mill 1700(«Severstal», Cherepovets):
1 – work roll; 2 – seal V3-480; 3 – back cover in assembly; 4 – seal PCK 25-500;
5 – work chock; 6 – front cover in assembly; 7 – seal PH2-505; 8 – seal PCK 25-470;
9 – distance ring; 8 - rubber seal ring X70-385-400.

Everywhere the application of the modernized sealing units which was carried out with the minimal changes (or at all without changes) of chocks and rolls, resulted to increase of roll bearings service life and to decrease in expense of greasing.

At the order modernized (or new) sealing units for bearing supports of the specific equipment their development is may be executed within 1-2 months, and manufacturing and delivery – within the next 4-6 months, depending from volume of the order.