Self-aligning fixture for pre-loading and aligning pivot bearing assemblies

• US 6,651,340 B2
• Filed: 02/18/2003
• Issued: 11/25/2003
• Est. Priority Date: 06/26/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Prater, Walter L.
• Primary Examiner(s): Vidovich, Gregory
• Assistant Examiner(s): Omgba, Essama
• Application Number:
  US10/368,840
• Publication Number:
  US 20030126739A1
• Time in Patent Office: 280 Days
• Field of Search: 298/980.7, 298/980.9, 298/980.4, 298/980.62, 297/24, 384/537, 384/542
• US Class Current: 29/898.09
• CPC Class Codes: F16C 19/54 Systems consisting of a plurality of bearings with rolling friction spindle bearings F16C35/08
• CPC Class Codes: F16C 2226/40 with adhesive
• CPC Class Codes: F16C 2229/00 Setting preload
• CPC Class Codes: F16C 2370/12 Hard disk drives or the like
• CPC Class Codes: F16C 25/06 Ball or roller bearings
• CPC Class Codes: F16C 35/06 Mounting or dismounting of ball or roller bearings; Fixing them onto shaft or in housing
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: Y10T 29/49696 Mounting
• CPC Class Codes: Y10T 29/497 Pre-usage process, e.g., preloading, aligning
• CPC Class Codes: Y10T 29/53104 Roller or ball bearing

Abstract

A fixture for pre-loading a pivot assembly has a stationary base and a tool that is axially movable relative to the base. The tool has a platen with a pre-load mass and a cylindrical enclosure. A sphere is suspended within the enclosure but is free to roll and move laterally along three degrees of freedom. The pivot assembly has an external sleeve with a coaxial shaft mounted on bearings. Each ball bearing has an inner ring, an outer ring, and balls in between. The rings are adhesively bonded to the shaft and sleeve. The pivot is placed on the base of the fixture and the tool is lowered. The sphere is free to “float” within the enclosure until it makes contact with the inner ring of the upper bearing in the pivot. Upon contact, the compliant, rolling sphere automatically self-aligns with the pivot. The pre-load mass applies the desired force against the pivot until the adhesive cures. The sphere ensures that the pre-load force is uniform around the ball compliment circumference of the bearings such that the inner and outer rings of the bearings float and their raceways self-align under the pre-load force. After the adhesive cures, the pivots have negligible torque ripple and consistent dynamic response.

Claims

1. A method of pre-loading a pivot assembly having a sleeve, a shaft, and a bearing therebetween, comprising the steps of:

(a) providing a base and a tool having two degrees of rotational freedom;

(b) placing the pivot assembly on the base;

(c) moving one of the base and the tool toward the other such that the tool contacts the bearing of the pivot assembly and applies a uniform, compliant, pro-load force to the pivot assembly around a ball compliment circumference of the bearing such that an inner ring and an outer ring of the bearing float and that raceways of the rings self-align under the pre-load force;

and wherein step (c) further comprises;

moving a sphere within a tool enclosure to achieve compliance until the sphere makes contact with the bearing and a tool platen.

2. The method of claim 1 wherein the tool has a pre-load mass mounted thereto and wherein step (c) comprises lowering the tool onto the pivot assembly.

3. A method of pre-loading a pivot assembly having a sleeve, a shaft, and a bearing therebetween, comprising the steps of:

(a) providing a base and a tool having two degrees of rotational freedom;

(b) placing the pivot assembly on the base;

(c) moving one of the base and the tool toward the other such that the tool contacts the bearing of the pivot assembly and applies a uniform, compliant, pre-load force to the pivot assembly around a ball compliment circumference of the bearing such that an inner ring and an outer ring of the bearing float and that raceways of the rings self-align under the pre-load force;

and wherein step (c) further comprises;

articulating a dual gimbal assembly to achieve compliance between the tool and the pivot assembly, and wherein the tool has a tubular anvil with a hard, polished, lower annular surface for engaging the inner ring.

4. The method of claim 3, wherein the tool has a pre-load mass mounted thereto and wherein step (c) comprises lowering the tool onto the pivot assembly.