Integrally Formed Bearing Race for Pivot Arm Assembly
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Solution Overview
Problem
Existing semiconductor wafer handling robots experience fretting and contamination due to the rubbing movement between ball bearings and their housing in prior art designs, which can damage wafers and compromise the sterile environment.
Innovation Solution
A pivot arm assembly with an integrally formed bearing construction, featuring a radially inwardly opening groove in the outer integral race portion and a radially outwardly opening groove in the inner race portion, allowing for the precise alignment and retention of rolling bearing elements within an eccentric gap, eliminating the need for separate outer bearing races and reducing fretting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate outer bearing races are used in the pivot arm assembly, then the bearing mounting is simplified, but fretting occurs between the bearing outer races and housing arm recesses producing metallic particles that contaminate wafers
Solution Approach 1:
The patent merges the outer bearing race with the housing arm recess by integrally forming the bearing race portion from the housing material. This eliminates the separate outer bearing race component, preventing fretting between the outer race and housing while maintaining simplified manufacturing through integral construction.
Solution Approach 2:
The patent removes the outer bearing race from the bearing assembly, extracting only the necessary bearing function through the integral housing structure. This eliminates the source of metallic particle contamination while preserving the essential support and guidance functions.
2Device complexity
If ball bearings are mounted in separate outer bearing races, then the bearing assembly is modular, but rubbing movement causes fretting that destroys the sterile environment
Solution Approach 1:
The patent combines the housing and outer bearing race into a single integral structure, eliminating the interface where fretting occurs. This maintains reliability by preventing metallic particle generation while preserving modular assembly through the inner bearing race and ball bearing components.
3Ease of operation
If the pivot arm assembly uses conventional bearing mounting, then installation is straightforward, but improper installation causes severe fretting and contamination
Solution Approach 1:
The patent integrates the outer bearing race with the housing structure, eliminating the critical installation step of mounting outer races. This removes the risk of improper installation while maintaining ease of assembly through the remaining modular components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes fretting and contamination, ensuring precise orientation and long operating life while maintaining a sterile environment for semiconductor wafers, enhancing the handling efficiency and reliability of semiconductor wafer handling robots.
Implementation Method 1
A plurality of rolling bearing elements are sequentially inserted through the gap at the wider portion thereof and into the first and second bearing tracks
Implementation Method 2
The bearing elements are then positioned in a regularly spaced apart relationship about the first and second bearing tracks
Data Source
AI summary
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.