Browse Prior Art Database

Hydrodynamic Ball Nut with Rotary Preload Adjustment

IP.com Disclosure Number: IPCOM000090471D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Bernardo, ET: AUTHOR [+3]

Abstract

Increased accuracy in the positioning of X-Y tables used with printed circuit generators is obtained by minimizing backlash in the drive train through the use of this hydrodynamic ball nut. A double-ball nut is modified by the addition of negative castings at each end that further reduce backlash. In addition, pressurized oil is delivered to the center of the assembly and pulled through the grooves in the end castings by vacuum.

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Hydrodynamic Ball Nut with Rotary Preload Adjustment

Increased accuracy in the positioning of X-Y tables used with printed circuit generators is obtained by minimizing backlash in the drive train through the use of this hydrodynamic ball nut. A double-ball nut is modified by the addition of negative castings at each end that further reduce backlash. In addition, pressurized oil is delivered to the center of the assembly and pulled through the grooves in the end castings by vacuum.

The double-ball assembly includes main housing 1 which supports conventional adjustable type ball nuts 2. Attached to each ball nut 2 is the added negative ball screw casting 3. These castings of sintered steel are provided with ridges 4 that engage grooves 5 on shaft 6. Castings 3 are formed as exact replicas of shaft 6 by using it as a mold after first increasing the diameter a fixed amount. Oil return vacuum manifolds 7 provided with a port 8 encircle castings 3 to provide a connection for the vacuum. Oil inlet fitting 9 is provided at the center of the assembly. The end casting and the ball nuts are locked together by rings 10 that coact with housing 1 to ensure proper loading.

Each half of the assembly consisting of the ball nut and the negative casting is preassembled on the shaft and adjusted to be free running. The two units are then assembled to the housing and preloaded by differential screw 11 to reduce backlash to a minimum. After assembly and adjustment, pressurized oil is ...