Pivot arm assembly for semiconductor wafer handling robots and method for making the same

Abstract

A method for making a robot pivot arm assembly includes forming from a rigid, machinable material a circular disk, and forming a circular aperture through the center of the disk. An outer bearing track is formed integrally in the inside surface which defines the aperture, and the apertured disk is positioned in a machining device with a fixturing portion that engages the outer bearing track. An integral outer race, an arm and a gear segment with teeth are then machined into the disk to form the outer portion of the pivot arm assembly. An inner race with an inner bearing track is positioned inside the integral outer race, and rolling bearing elements are inserted into the first and second bearing tracks.

1 - 21 . (canceled) 
     
     
         22 . In a robotic machine for handling semiconductor wafers and the like, the improvement of a pivot arm assembly, comprising:
 a rigid, annularly-shaped ring portion having a cylindrically-shaped inside surface and a cylindrically-shaped outside surface, with a radially inwardly opening groove formed in said inside surface of said ring portion to define a first bearing track;   a rigid, cylindrically-shaped sleeve portion having a cylindrically-shaped inside surface configured to closely receive and retain a mounting portion of said robotic machine therein, and a cylindrically-shaped outside surface with a radially outwardly opening groove formed in said outside surface of said sleeve portion to define a second bearing track which is shaped substantially similar to said first bearing track in said ring portion;   said sleeve portion being positioned inside said inside surface of said ring portion in an assembly condition, wherein said first and second bearing tracks are radially aligned, and said sleeve portion is in an eccentric relationship with said ring portion to form between said inside surface of said ring portion and said outside surface of said sleeve portion an eccentric gap having a wider portion and a narrower portion;   a gear segment portion with teeth formed along one portion thereof, with an opposite portion thereof fixedly connected with said outside surface of said ring portion such that said teeth protrude radially outwardly from said ring portion;   a rigid connector arm portion having one end thereof fixedly connected with said outside surface of said ring portion such that said connector arm portion extends radially outwardly from said ring portion in a circumferentially spaced apart relationship with said gear segment portion;   a plurality of rolling bearing elements sequentially inserted through said gap at said wider portion thereof and into said first and second bearing tracks, and subsequently positioned in a regularly spaced apart relationship around said first and second bearing tracks with said sleeve portion and the ring being contemporaneously shifted into a concentric relationship; and   a separator portion connected with said bearing elements and pivotally retaining said bearing elements in said regularly spaced apart relationship in said first and second bearing tracks.   
     
     
         23 . A robotic machine as set forth in  claim 22 , wherein:
 said rolling bearing elements comprise spherical ball bearing elements.   
     
     
         24 . A robotic machine as set forth in  claim 23 , wherein:
 said separator includes a plurality of radially oriented teeth which snap onto said ball bearing elements.   
     
     
         25 . A robotic machine as set forth in  claim 24 , wherein:
 said gear segment portion is formed integrally with said ring portion.   
     
     
         26 . A robotic machine as set forth in  claim 25 , wherein:
 said connector arm portion is formed integrally with said ring portion.   
     
     
         27 . A robotic machine as set forth in  claim 26 , wherein:
 said first and second bearing tracks are shaped for four point contact with said ball bearing elements.   
     
     
         28 . A robotic machine as set forth in  claim 22 , wherein:
 said separator includes a plurality of radially oriented teeth which snap onto said ball bearing elements.   
     
     
         29 . A robotic machine as set forth in  claim 22 , wherein:
 said gear segment portion is formed integrally with said ring portion.   
     
     
         30 . A robotic machine as set forth in  claim 22 , wherein:
 said connector arm portion is formed integrally with said ring portion.   
     
     
         31 . A robotic machine as set forth in  claim 22 , wherein:
 said first and second bearing tracks are shaped for four point contact with said ball bearing elements.