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DOUBLE ACTION TAPERED ROLLER THRUST BEARINGS FOR HEAVY DUTY MIDDL-SPEED UNITS

1. Reasons for development

Toughened operating conditions of modern rolling mills (especially of continuous wide-strip mills) required using in roll supports reliable thrust bearings able to react heavy axial alternating loads when rotated at relatively high speed.

Use of similar bearings, including those of leading world producers (Timken, SKF, FAG), is limited by their low speed capabilities. That is why they are usually installed in low-speed stands of plate and rail-and-section mills as well as in roughing stands of section mills. On the other hand, radial-thrust tapered roller bearings able to react axial loads require, as a rule, using of supports of considerable size and weight, and provoke high friction losses, so that extra cooling of supports is needed.

The bearings with high load and speed characteristics are designed, first of all, for thrust units of roll supports of sheet mills but they can also be used in other heavy duty bearing units with both longitudinal and vertical rotation axes.

2. Functional characteristics

Our bearings, as well as their well-known foreign analogs
- guarantee radial self-alignment (from ± 0,5 to ± 1,0 mm) of the bearing unit shaft with shaft washer relative to the bearing housing with housing washers;
- require neither adjustment of the axial clearance nor fitting into bearing units of any special springs intended to take up clearances on the idle side of the bearing.

Besides, due to use of some novel approaches which permit reducing dissipative energy losses and equalizing the load distribution on the contact surfaces, some news features are provided, such as:
- singular (up to ± 10') self-alignment of bearing unit shaft relative to the bearing housing;
- use of bearings in the comparative high rotation speed units – up to 5…8 rps (300…500 rpm)

Thrust tapered roller bearing:
1 – shaft washer; 2 – housing washers;
3- distance sleeve; 4- rollers; 5 – bearing race;
6 – cages; 7 – ring-shaped spring; 8 – built-in seals

General data of our bearings are listed in the table below:

Presented in this table the bearing range was developed in 1990-s with participation «NKMZ» (Novo-Kramatorsky machine-building plant) as it applies to the tasks of modernization and construction of domestic sheet rolling mills.

3. Application

Bearings 189740 X and 189750 X, manufactured by the VNIPP Bearing Factory (Moscow, Russia), have been successfully used on the bar mill of Byelorussia Metallurgical Works (Zhlobin, Byelorussia) since 1992

Bearings of other sizes from represented range are produced by the Samara Bearing Factory (Russia). In particular, bearings №№ 1899757 XM, 189772XM, 189778XM and 189892XM are entered in the production catalogue of the Samara Bearing Factory and delivered by job lots by orders of the metallurgical enterprises of the CIS.

Delivery of bearings represented in the table, as well as development and supply of bearings of other standard sizes, according to the customer´s needs, could be realized during one year.