Multi-Layer Linear Bearing for Low-Particulate Precision Motion
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Solution Overview
Problem
Existing linear bearings face challenges in minimizing particulate generation and foreign object damage (FOD) while maintaining stability and accuracy, particularly in clean room environments, due to multiple points of contact and rubbing, which affect precision and cleanliness.
Innovation Solution
A precision linear bearing design featuring at least two bearing layers with rotationally offset roller bearings within a one-piece housing, minimizing contact points and using materials like stainless steel, anodized aluminum, or titanium, with a surface finish of 63 Ra or better, to reduce particulates and FOD, ensuring stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a slide bearing with rubbing contact is used, then the bearing provides simple linear motion support, but particulate matter is generated causing foreign object damage (FOD)
Solution Approach 1:
The patent replaces the traditional slide bearing rubbing contact mechanism with a roller bearing rolling contact mechanism. The linear bearing uses rollers that rotate on the linear shaft, substituting the harmful rubbing friction with rolling friction, which significantly reduces particulate matter generation while maintaining the linear motion support function
Solution Approach 2:
The patent introduces a multi-layer structure with rollers arranged in multiple planes (at least two layers spaced apart axially). This dimensional arrangement allows the rollers to contact the linear shaft at different circumferential positions, providing stable support while minimizing contact points that generate particulates
2Stability of the object's composition
If multiple rolling elements are used to support load, then the bearing provides stable linear motion, but the number of contact points increases generating more particulates
Solution Approach 1:
The patent arranges rollers in multiple axial layers (at least two layers spaced apart) with each layer containing rollers at different circumferential positions. This multi-dimensional arrangement distributes the load support function across multiple planes, maintaining stability while reducing the concentration of contact points at any single location, thereby minimizing particulate generation
Solution Approach 2:
The bearing is segmented into multiple functional layers with rollers distributed across these layers. Each layer provides partial load support, and the segmentation allows the system to maintain overall stability while reducing the harmful effects concentrated at individual contact points
3Length of moving object
If recirculating rolling elements are used, then unlimited travel distance is achieved, but pulsations affect travel accuracy
Solution Approach 1:
The patent extracts the recirculation mechanism from the bearing design, using non-recirculating rollers that are fixed in position within the housing. The rollers rotate on the linear shaft but do not circulate through a return path, eliminating the pulsations caused by balls moving from non-load-carrying to load-carrying zones while still allowing unlimited travel distance through the linear shaft movement
4Speed
If rolling elements recirculate through a circuit, then unlimited stroke is achieved, but forces on end caps limit maximum speed
Solution Approach 1:
The patent removes the recirculation circuit entirely, using fixed-position rollers that rotate on the linear shaft without traveling through a return path. This eliminates the forces created on end caps during the turning phase of recirculation, allowing higher maximum speeds while maintaining the unlimited stroke capability through direct linear motion
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 design effectively minimizes particulates and FOD, enhances stability and precision, and is suitable for clean room environments by reducing contact points and using high-quality, sealed materials, allowing for compact and precise linear motion.
Implementation Method 1
The journal i.e., the part of a linear member or shaft in contact with the bearing, slides over the bearing surface... The rubbing contact of the linear member with the bushing can generate particulate matter... Each roller bearing has an axis of rotation substantially perpendicular to the axial bore and projects into said axial bore for engagement of a linear member
Data Source
AI summary
A precision linear bearing is designed to minimize the points of contact, rolling and rubbing, to reduce particulates and FOD while ensuring stability and accuracy in a manner suitable for a clean room environment. The linear bearing comprises at least first and second bearing layers within a one-piece housing. Each bearing layer comprises at least three roller bearing spaced around the axial bore in a first plane within the housing, each roller bearing having an axis of rotation substantially perpendicular to the axial bore and projecting into said axial bore for engagement of a linear member extending through the axial bore. Each roller bearing suitably engages the linear member at a single point of contact. The layers are rotationally offset from one another such that the roller bearings contact different positions around the circumference of the linear member. The linear bearing may be configured to engage the inner surface of a cylindrical member.