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Ball bearing
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- 2. Bearings Function: • Carry loadin one or several directions while allowing frictionless motion in other directions Fatigue = F(Pressure, Velocity) • 3 main types of Bearings – Rolling Element Bearings – Sliding Bearings – Elastomeric Bearings
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- 4. 2 TYPES OFROLLING BEARINGS I. Ball Bearings II. Roller Bearings
- 5. • Ball Bearing –Incorporates hardened steel balls – Steel balls geometrically contact inner and outer race at a point – This creates high stresses locally www.duratrax.com I. Ball Bearing: cage seals Inner race Outer race
- 6. Ball Bearings How toAssemble -Inner race press fit onto shaft shoulder (FN1, FN2) -Assembly slides into housing (RC2) between outer race and housing
- 7. Types of BallBearings • Deep Groove Ball Bearings – Primarily radial load carrying – Thrust load equal to 25% of radial load – Can get as large as 300K radial load capacity http://my.ecplaza.net/nbsinobest/12l.asp
- 8. Types of BallBearings • Double Deep Groove – Increases radial load
- 9. Types of BallBearings • Angular contact ball bearing – Increased thrust load due to increase in lateral contact area between ball and race www.hz-bearing.com
- 10. Types of BallBearings • Thrust Bearings – Used in applications with significant thrust load http://kianho.com
- 11. Types of BallBearings • Super precision ball bearings – Nearly perfect spheres – High surface finish • Applications – High speed grinding, milling, boring, routing – No Vibration!! • Ceramics – Hard – No deformationwww.timken.com
- 12. HOW It’s MADE: 1.http://www.youtube.com/watch?v=eGyoMuE4gDQ 2. http://www.youtube.com/watch?v=k8SHKy5tXbI&feature=related
- 13. II. Roller Bearings •Roller Bearings – Hardened steel cylindrical rollers – Line contact deforms into areas larger then ball bearings – Capable of carrying higher radial loads
- 14. Types of RollerBearings • Needle Bearings – 4 joint machine applications – As the number of rollers goes up the greater the contact area – The greater the contact area the greater the load www.clworldwide.com
- 15. Types of RollerBearings • Spherical Roller Bearings – Centers inner race about shaft to avoid binding www.dclcorp.co.kr/image/Nachi3.jpg
- 16. Types of RollerBearings • Tapered Roller Bearing – Support high thrust loads (wheel bearing) – Supports radial load (car weight) while supporting thrust loads (cornering) – Wheel rotates with little resistance/friction www.ahrinternational.com
- 17. Types of RollerBearings • Thrust Roller Bearings – Used in applications with significant thrust load www.timken.com
- 19. Mounted Bearings Precision machine elementssuch as transmissions, reducers, right angle drives usually incorporate un-mounted bearings
- 20. Other Types ofBearings • Thompson linear bearings • Sliding Bearings – No rolling elements – Sleeve over shaft where sleeve acts like bearing (Generally higher friction) – Bronze good material due to coefficient of friction, porosity and wear resistance www.intbearing.com
- 21. Other Types ofBearings • Self Lubricating Bearings – Low Friction – No lubrication needed Elastomeric Bearings www.garlockbearings.com http://www.polygoncompany.com/ http://www.polygoncompany.com/
- 23. Ball Joint –3 rotational DOF HEIM Bearing See heim overview powerpoint
- 24. V-22 OSPREY Drive LinkDriveLink Hub Spring SetHub Spring Set PendulumPendulum SpringSpring PitchPitch Change BearingChange Bearing GimbalGimbal BearingBearing Outboard SpindleOutboard Spindle CentrifugalCentrifugal BearingBearing InboardInboard BeamBeam PitchPitch Change SystemChange System DownstopDownstop www.lordmpd.com
- 25. HCL Components ofV-22 Osprey Drive Link Centrifugal Bearing www.lordmpd.com
- 26. Bearing Selection seesec 14.6 – 14.10:
- 27. Selecting Bearings Load-Life Relationship: k P P L L = 2 1 1 2 P1= load 1, L1 = life at load 1, k = 3.00 for ball bearings k = 3.333 for roller bearings Example: A ball bearing lasts 3,000 hours at 500 lb, how long will it last at 1,000 lbs? SIMPLE!
- 28. Selecting Bearings Cont’d k P P L L = 2 1 1 2 Mostmanufacturers specify basic dynamic load rating, C, which is the load that results in 106 cycles. So, this equation can be rewritten as: 6 10 k d d P C L = = Design Life for your specific application for a design load of Pd k d d L PC /1 6 10 = = Required dynamic load rating for a design life = Ld Note, these are all L10 lives!!! Which is the life for 90% reliability
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- 30. Example: A horizontalwashing machine rotates at 1,100 rpm. Spec out bearings on ends if the dynamic radial load is 400 lb and static load is 75 lb. Want machine to last 20 years @ 3 loads per day, 30 minute cycle time/load.
- 32. Can use chartsshown in 14-12 to get C. Or equation presented earlier.
- 33. CAREFUL! • Previous equationsassumes: L10 life, and inner race rotates and radial load only!! 1. Inner race rotates, then Pd = P = V*R where V = 1.0 if inner race rotates and V = 1.2 if outer race rotates. 2. Lar = CR * L10 Washing machine example, what if want 99% reliability?? 3. What if thrust load is present??? - iteration
- 34. P = VXR+ YT P = Load V = Rotation Factor (1.0 – Inner Race, 1.2 – Outer Race) X = Radial Factor (.56 if Y>0) R = Applied Radial Load Y = Thrust Factor T = Applied Thrust Load *Thrust Load Present – Deep Groove Ball Bearing
- 35. START FIND R,T ASSUMEY P=VXR+YT C=PdfL/fN Select Bearing Compute T/Co Find e T/R>e? P=VR C=PdfL/fN Select Bearing END FIND Ynew Ynew=Yold? END Figure 14-12 Table 14-3 YES NO YES NO Table 14-5 Iterate within reason Usually get for shaft analysis ~1.5 *Must initially guess