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Kalsi Thrust Bearing Introduction
The
award-winning
Kalsi Bearing is a patented, impact-resistant one-piece thrust bearing
element that uses geometry-induced hydrodynamic lubrication to support heavy
thrust loads on a lubricant film. The result is a bearing that is
fundamentally superior to conventional thrust bushings that operate in a
boundary/mixed lubrication regime.
The Kalsi Thrust Bearing was developed for
downhole oil well drilling applications, such as mud motors, turbines, and
roller cone bits. Bearings in such downhole tools are subjected to extremely
harsh operating conditions that include high unit loads, speeds, impacts,
and vibration. Key advantages of the Kalsi Bearing for such applications
are:
- Tolerates much higher impact loads, compared to roller thrust
bearings, without brinelling damage or performance degradation, and
- Significantly reduced friction, compared to plain thrust bushings, as
a result of the hydrodynamic lubrication. This allows higher load/speed
combinations, cooler operation, and extended operational life.
The Kalsi Bearing is also suitable for applications where
tilting pad thrust bearings are used, offering the advantages of simplicity,
compactness, economy and low friction over a wider load range.
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The Kalsi Thrust Bearing
generates a hydroplaning action during rotation that reduces
friction and permits higher loads and speeds, and provides long
life. Bearings are available for both uni-directional rotation
(shown) and bi-directional rotation. The bearings are suitable
for both oil and grease-type lubricants.
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The Kalsi Thrust Bearing was developed using
coupled modal-based elastohydrodynamic analysis to predict
interfacial lubricant film thickness, pressure and running
friction, to optimize the design, and to confirm the bearing
design methodology. During development, the elastohydrodynamic
analyses results compared favorably to laboratory test results
obtained with a highly accurate test apparatus over a wide range
of operating conditions.
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Due to hydrodynamic operation,
Kalsi Thrust Bearings typically operate with friction coefficients in
the range of 0.003 to 0.005. This is significantly lower friction than
experienced with conventional oilfield drill bit thrust bushings,
which operate in a boundary/mixed lubrication regime. This advantage
is apparent over a wide speed range. These graphs compare performance
results for 1" x 2" bearings. In this test, the load was incrementally
increased under constant rotary speed. The duration of each load step
was sufficient to achieve steady state operating conditions. With the
Kalsi Thrust Bearing, the friction coefficient decreased with
increasing load until the hydrodynamic load-carrying capacity limit is
reached. When the load limit is reached, friction increases as the
bearing reverts to mixed/boundary lubrication, with friction
coefficients that are in approximately the same range as oilfield
drill bit thrust bushings. |
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Thrust Bearing Selection and Implementation
Kalsi Thrust
Bearings are custom-designed for the envelope constraints and load
requirements of each application using coupled elastohydrodynamic
analysis software. The bearings are available in an assortment of
materials, including beryllium copper, steel, and spinodally hardened
copper-nickel-tin alloy. Kalsi bearings are typically run against a
carburized or Stellite 6 overlaid steel counter-face. Silver-plating
of the counter-face is sometimes employed with non-ferrous Kalsi
Thrust Bearings for added over-load protection.
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Finite Element Elastic Deformation Solution Showing
Wedge Formation under Static Load
a
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This figure shows the elastic deformation of a
Kalsi Bearing under static thrust load, as predicted by finite element
analysis. Deflection is exaggerated, making the formation of a static
wedge clearly visible. Upon commencement of rotation, the statically
formed wedge initiates the development of interfacial hydrodynamic
pressure. This lubricant pressure in turn changes the deflection of
the bearing, and the resulting dynamic wedge shape dictates the
lubricant film thickness and bearing thrust load capacity. The Kalsi
Thrust Bearing design methodology accounts for these static and
dynamic effects. |
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Thrust
Bearing Application Support
Experienced Kalsi Engineering personnel are also available to
provide thrust bearing technical support and implementation guidance.
If you would like Kalsi Engineering to review your bearing
application, please download an
application questionnaire in MS Word format, and forward it to us.
Alternately, you can e-mail us
with your thrust bearing questions, or call us directly at
281-240-6500.
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Kalsi Bearings are offered for sale under the terms and
conditions of the "Offer of Sale" that is included in the current revision of
the
Kalsi Seals Handbook.
Kalsi Bearing, Kalsi Bearings, Kalsi Thrust Bearing and Kalsi Thrust Bearings
are trademarks of Kalsi Engineering, Inc.
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