Browse Prior Art Database

Thrust Retainer Constrained Stepper Motor Shaft

IP.com Disclosure Number: IPCOM000061783D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Krimm, DL: AUTHOR [+3]

Abstract

A permanent magnet claw-type stepper motor has its end play reduced to a few thousandths of an inch by an assembly technique in which a spring washer, which has previously been used to bias the shaft in one direction to minimize end play, is eliminated so that internal friction caused by the spring load of the spring washer also is eliminated. The stepper motor assembly is a follows: 1. A front bearing 1 is pressed and staked into a front mounting plate 2. 2. A rear bearing 3 is pressed and staked into a rear cover 4. 3. Inner cans 5 and 6 are aligned with each other and staked or riveted. 4. A rotor hub 7, which is formed of aluminum, is pressed onto a shaft 8, and a magnet 9 is glued or molded onto the hub 7. 5.

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Thrust Retainer Constrained Stepper Motor Shaft

A permanent magnet claw-type stepper motor has its end play reduced to a few thousandths of an inch by an assembly technique in which a spring washer, which has previously been used to bias the shaft in one direction to minimize end play, is eliminated so that internal friction caused by the spring load of the spring washer also is eliminated. The stepper motor assembly is a follows: 1. A front bearing 1 is pressed and staked into a front mounting plate 2. 2. A rear bearing 3 is pressed and staked into a rear cover 4. 3. Inner cans 5 and 6 are aligned with each other and staked or riveted. 4. A rotor hub 7, which is formed of aluminum, is pressed onto a shaft 8, and a magnet 9 is glued or molded onto the hub 7. 5. A front outer can 10 is staked or riveted to the front mounting plate 2, and a rear outer can 11 is staked or riveted to the rear cover 4. This produces two outer can assemblies. 6. Bobbins (not shown) forming toroidal windings are assembled. 7. The front mounting plate 2, the front bearing 1, and the front outer can 10 are placed face down. 8. A bobbin is placed within the front outer can 10.
9. The joined inner cans 5 and 6 are pressed into the front outer can 10. 10. A bobbin is placed within the rear inner can 6. 11. A rotor assembly of the shaft 8, the hub 7, and the magnet 9 is placed with the shaft 8 extending down into the front bearing 1 and against a front thrust washer 12, which is used to prevent wear between the aluminum hub 7 and the bronze front bearing 1. If the hub 7 were formed of steel, for example, the front thrust washer 12 would not be required. 12. This preassembly is placed in a fixture supported by a block 13. 13. The rotor assembly is biased downwardly with a one-pound load on the shaft 8 by a block 14 (shown in phantom...