C O N T A C T SEALS FOR R O L L I N G M I L L S

(UDC 62-223: 669.1)

L. I. M a m o n , V. P. K u z ' m i n , G. G. N e d o b a c h i n , a n d A. V. M a t u k h n o

Dzerzhinskii Dnepropetrovsk Chemical-Technological Institute Translated from Metallurg, No. 1, pp. 29-30, January, 1965

The Plant Department in our institute has investigated a number of metallurgical factories of the Dneprope- trovsk sovnarkhoz in order to develop improved designs of seals which would reduce oil losses in rolt tables, pinion stands, reduction gears, and electric motors. Thus, according to an investigation in 1961, the losses of oil (motor oil 10, motor oil 18) were 439 t in the new-section and medium-section roiling shop of the Dzerzhinskii factory, 165 t in the sheet rolling shop No. 1 and section rolling shop of the Komintern factory, and 72.4 t in the section roll- ing shop of the Petrovskii factory.

The results of the investigation have shown that the use of improved seal designs could considerably reduce the consumption of oii in the various units of machines and mechanisms. The existing labryinth seals and repelling col- lars do not ensure the required leak-tightness of the units, since they are working at elevated temperatures, at con- siderable radial and axial displacements of the sealed shafts, and in an atmosphere containing large amounts of dust. The installation of cup seals does also not give the desired results, since the sealed neck of the shaft is worn away and a high leak-tightness can be reached only after regrinding the neck of the shaft.

Contact (face) stuffing boxes are the best seals for work in such conditions.

After the experiments, the authors developed a range of designs for contact seals. In the designs special care was taken to avoid, as far as possible, any alteration of the existing units. A brief description of the contact seal is given below.

The face of the internal bearing race (Fig. 1) is at the same time a rotating contact bushing. The fixed con- tact bushing 4 is made from bronze O8-10-10. Spring 5 holds the bushing in contact. The pin 8 prevents the bush-

4 ~ ] 3 ing from rotating during an axial displacement of up to 6-8 ram. x , , ~ , ~ The outside is packed with felt or with a secondary, thick feltseal.

~-~/<'~-~,,, ,, The existing felt seal is retained as a protection against dust and / ~ " x ~ ' ' x ~ . ~:)2] ~h3.;: ~ , . , scale, and to reduce the amount of scale or dust falling onto the

I ..% m _ ' - 5

1 1 5

Fig. 1. Contact seal unit for table roller. 1)Seal- ing ring; 2) binding bolts; 3) pin; 4) contact bushing; 5) spring; 6) thrust collar.

contact seal. The secondary seal can also be made from oil-re- sistant rubber, polyethylene, or Teflon,

The contact seal (Fig. 2) is dismountable, since it is not possible to design contact bushing in a single unit because of the sleeve of the sealed shaft. The joints of the bushings are ground in or scraped in. The bushing 5 is tightened and rotated by using the pins 8. The secondary seal 6 prevents the oil from seeping between the shaft and the bushing. The seal (Fig. 3) has no dis- mountable elements. The rotating bronze bushing 8 is fixed to the shaft by screwing it onto bushing 5. The secondary seal ? is made from thick felt. Seal 4 serves as a protection against dust and scale. The contact bushings are tightened by springs.

The contact seal on pinion stands are reliable at consider- able displacements of the shaft and radial clearance in the bear- ing.

44

Fig. 2. Dismountable contactsealof pinion stand. 1) Check; S) clamp bolt; 3) fixed bushing; 4) bronze insert; 5) mov- ing bushing; 6) secondary seal; ?) spring; 8) pins.

~3

10 9 8 7

Fig. 4. Contact seal of reduction gear TsOS- 200. 1) Body; 2) diaphragm; 3) bolt; 4) fixed bushing; 8) insert; 6) shaft; 7) stud bolt; 8) steel gasket; 9) nut; 10)bush- ing; 11) spring, 12) washer; 13) cover.

Contact stuffing boxes with secondary diaphragm seals were developed for the main reduction gear of the wire mill TsOS-200. The presence of the drive clutch and flywheels pressed onto the shafts called for section- al designs.

The contact seal of a low-speed shaft is shown in Fig. 4. The diaphragm 2 prepared from low-resisting

f 2 3

8 7 8

i Fig. 3. Contact seal of pinion stand. 1) Bolt; g) cover; 3) moving bronze bushing; 4) second- ary seal; 5) moving steel bushing; 6) fixed bushing; ?) secondary seal; 8) spring.

I

3

I

_

5 6 v 8

Fig. 5. Contact seal of high-speed shaft. I) Hous-

ing of reduction gear; 2) bolt; 3) fixed bushing;

4) moving bushing; 5) stud bolt; 6) insert; 7) sec- ondary seat; 8) nut; 9) washer; 10) spring; 11)con- tact bushing,

rubber is pressed by the sectional cover 13 against the body of the reduction gear. The shoulder of shaft 6 of the re- duction gear is a rotating contact bushing. The fixed contact bushing 4 consists of two halves. The bronze insert 5 is pressed into it. The joint is thoroughly ground in, or scraped in, and assembled on set pins. The contact bushings are clamped by the springs 11, the force of which is regulated by the position of the bushings 10. This makes assem- bly of the unit easy and takes up the torque brought about by the friction between the contact surfaces,

The sealing unit of a dismountable, high-speed shaft is shown in Fig, 6. Here, the rotating contact bushing 11 is pressed by the springs 10 against insert 6 of the fixed bushing. The felt seal prevents the oil from seeping along the shaft. The contact bushing is rotated by the moving bushing 4 through the stud bolt 5.

The contact seals of the designs shown work at peripheral speeds 1-11 m/sec. The inserts press-fitted into the fixed or rotating contact bushings can be made from various bearing materials, depending on working conditions. The investigation and experience show that the contact seals can be used for over two years without maintenance.

45