Flexure Assembly for Precision Actuator Motion

Solution Overview

Problem

High-tolerance ball bearings or bushings are unsuitable for long-life applications with small range of motion due to localized wear, which quickly decreases their dimensional tolerances and renders them unusable.

Innovation Solution

A flexure assembly comprising two metallic flexure arrays molded into a thermoplastic support base, allowing rotational movement about one axis while providing high stiffness against off-axis movement, formed using an injection molding process to achieve high precision and low-cost, unlimited-cycle operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-tolerance ball bearings or bushings are used for precise actuator motion, then measurement precision is improved, but reliability deteriorates due to localized wear in small range of motion applications

Engineering Contradiction:

Improveactuator motion precisionVSAvoidbearing life

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces traditional mechanical bearing systems (ball bearings or bushings) with a flexure-based mechanical system. The flexure assembly uses elastic deformation of flexible beams to enable precise rotational movement without contact between moving parts, eliminating localized wear and extending operational life while maintaining measurement precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs flexible beams (thin film structures) that undergo elastic deformation to provide the desired rotational motion. These flexible elements are designed with specific geometries to achieve the required compliance in the rotational direction while maintaining stiffness in other directions, replacing rigid bearing components

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of manufacture

If traditional bearing systems are used, then ease of manufacture is improved, but productivity deteriorates due to limited life and frequent replacement

Engineering Contradiction:

Improvebearing installationVSAvoidactuator operational cycles

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces traditional mechanical bearing systems (ball bearings or bushings) with a flexure-based mechanical system. The flexure assembly uses elastic deformation of flexible beams to enable precise rotational movement without contact between moving parts, eliminating localized wear and extending operational life while maintaining measurement precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs flexible beams (thin film structures) that undergo elastic deformation to provide the desired rotational motion. These flexible elements are designed with specific geometries to achieve the required compliance in the rotational direction while maintaining stiffness in other directions, replacing rigid bearing components

Inventive Principle:

Principle #30Flexible shells and thin films

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 flexure assembly achieves high precision and long-life performance by preventing harmonic resonance and minimizing wear, suitable for applications requiring small, high-cycle movements without the limitations of traditional bearings.

Implementation Method 1

two metallic flexure arrays molded into a thermoplastic support base to allow rotational movement about one axis while providing high stiffness with respect to off-axis movement

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8857052B2Method of forming a flexure assembly

Publication Date: 2014.10.14 MSSL CONSOLIDATED INC

AI summary

A flexure assembly includes two metallic flexure arrays molded into a thermoplastic support base. The two flexure arrays are positioned in parallel in the thermoplastic support base to allow rotational movement about one axis while providing high stiffness with respect to off-axis movement. Flexible supports in the two flexure arrays may be interleaved to form a cross flexure configuration. Off-axis stiffness of the flexure assembly prevents harmonic resonance in directions that cannot be compensated for in a single-axis actuator.