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Slotted Sleeve Pivot Bearing for Reduced Torque Ripple

IP.com Disclosure Number: IPCOM000014276D
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Abstract

Described is a pivot bearing design that has slots in the sleeve for the purpose of reducing torque ripple of the pivot. Pairs of either axial or circumferential slots in the sleeve will reduce the overall sleeve distortion that occurs when the side attach screw applies a clamping force, see figures 1 and 2. Two slots create a beam with a centrally located tapped hole (for the side attach screw) thereby localizing the distortion to the beam. When the pivot sleeve is distorted circumferentially, into an ellipse, the balls in the bearing see a higher preload in proximity to the minor axis and have a lower preload along the major axis. This causes a pivot to have high torque ripple, or peak-to-peak variation, demanding non-linear and unpredictable coil current required during an actuator seek. When the pivot sleeve is distorted (bowed) along its axis, the ball bearing outer rings become angularly misaligned relative to the inner rings. This causes the pivot to have higher running torque demanding a larger coil current required during an actuator seek. Slotted pivots have lower average running torque and lower peak-to-peak torque compared to unslotted pivots. Figure 1. Pivot with radial slots in sleeve. Figure 2. Pivot with axial slots in sleeve. 1

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Slotted Sleeve Pivot Bearing for Reduced Torque Ripple

   Described is a pivot bearing design that has slots in the sleeve for the purpose of reducing torque ripple of the pivot. Pairs of either axial or circumferential slots in the sleeve will reduce the overall sleeve distortion that occurs when the side attach screw applies a clamping force, see figures 1 and 2. Two slots create a beam with a centrally located tapped hole (for the side attach screw) thereby localizing the distortion to the beam. When the pivot sleeve is distorted circumferentially, into an ellipse, the balls in the bearing see a higher preload in proximity to the minor axis and have a lower preload along the major axis. This causes a pivot to have high torque ripple, or peak-to-peak variation, demanding non-linear and unpredictable coil current required during an actuator seek. When the pivot sleeve is distorted (bowed) along its axis, the ball bearing outer rings become angularly misaligned relative to the inner rings. This causes the pivot to have higher running torque demanding a larger coil current required during an actuator seek. Slotted pivots have lower average running torque and lower peak-to-peak torque compared to unslotted pivots.

Figure 1. Pivot with radial slots in sleeve.

Figure 2. Pivot with axial slots in sleeve.

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