cask roller bearings machined by electrical erosion prof ... popa.pdf · cask roller bearings...

Annals of the „Constantin Brancusi” University of Targu Jiu, Engineering Series , No. 2/2014

21

CASK ROLLER BEARINGS MACHINED BY ELECTRICAL

EROSION

Prof.univ.dr.ing. MARCEL S.POPA, Technical University of Cluj-Napoca

Drd. Ing. IOAN BADIU, Technical University of Cluj-Napoca

ABSTRACT: At low speeds of rotation or heavily loaded bearings in motion analysis of bearing

elements can be neglected dynamic effects. It can be considered as pressure angles of the ball and the two rings

are the same and does not change during operation, in the general case in which both the inner ring and the

outer orbital rotation of the ball rotesc.Intrucat generally occurs in a different plan rolling plane between the

ball and raceway will occur relative pivoting movement will affect vitrzei vector angular position and size of the

ball.

KEY WORDS : angular velocity of the ball, electrical erosion, rotation speed.

1.INTRODUCTION .

Because moments friction pivot ball in

relation to the two runways are unequal, it is

assumed that this will occur only pivoting

movement relative to the tread in contact with

the friction when the pivot is small. As a rule

when the friction at the contact with the inner

path is higher, it means that the ball is rolling

without pivoting on the inner path (which is

said so that you control the movement) and

rolls and pivots relative to the exterior. Due

to the geometrical shape of the rolling

elements moving and elastic deformations,

the contact surface will curve its radius in the

plane perpendicular to the direction of motion

is equal to the harmonic mean of the radii of

curvature in the plan.Because of the curvature

of the linear speeds in the region of the

contact points will be different. Only certain

points will achieve equality condition gear, so

pure rolling.

The other points will be subject to partial slip

before and partly back. Size differential slip

velocities can be determined by calculation.

Considering the contact of the ball with two

horses running in a radial-axial bearing, the

outer ring is fixed to analyze the relative

motion will give the ball to the center related

fix.In conditions remain dry or mixed friction

regime in reality there will be slip differential

on the entire surface contact friction forces

causing a non-slip grip relative to a specific

portion.Adhesion causes tangential tensile

stress in those areas that will help as those in

the differential slip rolling resistant moment

creating, modifying the character wear. By

choosing proper bearing geometric

parameters pate pure rolling lines change

position so that the center of the ellipse of

contact, the contact normal stresses

requested, to enter the area without slip

differential adhesion, thus resulting in a reduce

wear.


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2.EXPERIMENTAL RESULTS

FROM THE POCESSING OF

ELECTRICAL EROSION

Fig.1.Machine is manufactured by electrical

erosion AF-10

Spherical roller bearings consist of solid

outer rings with spherical raceway, solid

ring with two collars cylindrical or conical

hole and spherical roller cage. With self-

aligning capability, they are particularly

suitable in the radial, axial load capacity is

usually reduced.

Fig.3. Spherical roller bearings SKF Energy

Fig.2. The processing of bearings circular

orbits.

Fig.4. The Timken spherical roller bearings


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Fig.5. NSK spherical roller bearings.

Fig. 9. The connection between electrical

erosion parameters

Fig. 6. Table containing the values parameters

of electrical erosion

Fig. 10. The graph parameters electrical

erosion

Fig. 7. The graph electrical erosion parameters

Fig. 11. The reporting of electric erosion

productivity parameters


24

Fig. 8. The electrical erosion parameter values.


productivity parameters

Fig. 13. Table containing the values

parameters of electrical erosion.



Fig. 14. The connection between electrical

erosion parameters.


parameters of electrical erosion


25


productivity parameters.

Fig. 19. The shape 3D graphics parameters

electrical erosion.


electrical erosion.




electrical erosion.


electrical erosion.


26


electrical erosion.





Fig. 27.The shape 2D electrical erosion

parameters.


electrical erosion.

Fig. 28. The shape 2D electrical erosion

parameters.


27


productivity parameters.


parameters.




parameters.

Fig.31. The shape 2D electrical erosion

parameters.


parameters.


28




parameters.

Fig. 37. The electrical erosion parameter

values.

Fig. 41. 2D representation of the parameters

the electrical erosion.


parameters the electrical erosion.


the electrical erosion


29

Fig. 39. 3D graphical representation of the

parameters the electrical erosion.




parameters the electrical erosion

Fig. 44. 2D representation of the electrical

erosion parameters expressed in percentage.



Fig. 46. 2D representation of the electrical

erosion parameters expressed in percentage.


30

Fig. 47. 2D representation of the electrical erosion parameters expressed in percentage.

3.CONCLUSIONS.

If bearing operating at high speeds

due to the action of centrifugal forces, the

down force on the ball at the contact of the

two rings will be different, and therefore,

pressure angles will have different values.

Under the action of gyroscopic moments

there is a tendency of further spins the ball

which, depending on the speed and the

bearing lubrication conditions, there will

always be hampered by the forces of friction.

Arises in this case spin balls with adverse

effects on the bearing friction moment. For a

rigorous analysis will be necessary to

consider the angular velocity vector of the

ball, which has the following components in

the general case after three directions:

ωjx = ω

jb cos β

' cos β

''

ωjy = ω

jb cos β

' sin β

''

ωjz = ω

jb sin β

'

External forces acting on the bearing

are related to the total axial and radial

deformations. Theoretical analysis can be

deepened further by considering the

interaction between the balls and cage, which

is limited due to practical orbital velocity

amplitude variation around the average bead,

ie the angular velocity of the cage. The large

volume of calculations justify complete

analysis only in special cases, as was done,

for example, bearing devices used in

aerospace missions. In particular situations,

simpler, such as radial bearings symmetric

load, the number of unknowns is significantly

reduced.Given that between balls and

raceways there is a dry or mixed friction

regime, it is assumed that the gyroscopic

moment is insufficient to produce rotation of

the ball in the camp charged. Therefore the

angle β will be void ball rotation vector

finding thus in the plane passing through the

bearing and ball Cetra. In addition, if using

the assumption of control of the ball, that ball

is considered rolls and pivots in relation to

the path that controls movement and rolls and

pivots in relation to the other runway will

result in the opposing friction moment gyro

(gyro moment is zero) will act only upon

contact with conductive path.

Analysis of the dynamics and kinematics of

the ball is so much simplificata.In dry friction

conditions hypothesis ball control gives

sufficiently accurate results only for the

orbital velocity of the ball, and pivot about


31

not really zero in relation to any of

cai.Valorile angles setting for a given load and

speed of the bearing should be determined in

this case by analyzing the position of the ball,

for symmetrical load bearing situation is much

simplified.The ball control by the inner or

outer ring equation results from the analysis

points in the direction perpendicular to the

orbital motion (yaw moments are

components). Non-compliance leads to an

exciting outer ring control.

In the partial-load operation medium is

typically accomplished so ball control will be

provided by the inner ring.

At high speeds, due to the action of

centrifugal force, the force becomes larger

and more than a speed limit control is taken

over by the outer ring. It should be noted

again that in terms of fluid friction, ball

control assumption is no longer valid. To

analyze the kinematics of the bearing

imposing a complex calculation.

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