Resilient Shaft Design for Precision Dimensional Checking
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Solution Overview
Problem
Existing apparatuses for checking dimensions and shape errors face challenges in accurately guiding shafts while ensuring proper coupling with feelers, often resulting in jamming or incorrect measurements due to inadequate backlash or transverse stresses, especially in high-precision applications with multiple feelers.
Innovation Solution
A mechanical transmission assembly with a shaft having a guide portion housed in a guiding element and an intermediate resiliently deformable portion, allowing for axial movement with minimal backlash and accommodating transverse components, ensuring accurate and reliable displacement detection without risk of seizure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a guide mechanism is chosen to constrain axial displacement with minimal play, then measurement precision is improved, but the coupling with feelers becomes improper and transverse stresses cause jamming and seizures
Solution Approach 1:
The shaft is divided into distinct functional segments: a guide portion for precise axial movement, an intermediate resiliently deformable portion for absorbing transverse stresses, and an abutment portion for feeler coupling. This segmentation allows each part to optimize its specific function without compromising the others.
Solution Approach 2:
Different portions of the shaft have different mechanical properties tailored to their specific functions. The guide portion provides precise axial guidance, the intermediate portion provides resilience to transverse loads, and the abutment portion provides proper coupling geometry. This local differentiation resolves the contradiction between precision and reliability.
2Ease of operation
If backlash is increased to improve coupling with feelers, then ease of operation is improved, but the shaft leans and causes wrong indications from the transducer
Solution Approach 1:
The shaft's segmented design isolates the backlash accommodation function to the intermediate resiliently deformable portion, while the guide portion maintains minimal play for precise transducer coupling. This allows backlash to be managed without compromising measurement accuracy.
Solution Approach 2:
The intermediate resiliently deformable portion acts as an intermediary element that absorbs the backlash and transverse stresses between the feeler coupling and the precise axial guidance section, preventing shaft lean while maintaining operational ease.
3Measurement precision
If high accuracy items are used to increase measurement precision, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using high-precision components throughout, the invention changes the parameter of mechanical compliance in the intermediate portion, allowing standard components to achieve high overall precision through proper parameter selection and configuration.
Solution Approach 2:
High precision is localized only where absolutely necessary (the guide portion and transducer interface), while other portions use standard components with appropriate mechanical properties. This reduces overall device complexity while maintaining measurement precision.
4Adaptability or versatility
If three feelers are arranged independently at 120° to increase adaptability, then adaptability is improved, but the coupling between shaft and feelers becomes particularly complex
Solution Approach 1:
The shaft's abutment portion is designed with a universal geometry (such as a V-groove or spherical surface) that can properly couple with multiple feelers arranged at different angular positions. This single universal interface design handles the complexity of multi-feeler arrangements without requiring separate coupling mechanisms for each feeler.
Solution Approach 2:
The abutment portion has a specific local geometry optimized for receiving forces from multiple directions, allowing independent feeler movement while maintaining proper shaft coupling. This localized geometric solution simplifies the overall multi-feeler system complexity.
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 provides a robust, accurate, and easy-to-assemble apparatus with improved precision and reliability, reducing the risk of jamming and incorrect measurements, even in complex configurations with multiple feelers, and supports the use of sensitive transducers without the need for additional anti-rotation mechanisms.
Implementation Method 1
an intermediate resiliently deformable portion (26)
Data Source
AI summary
An apparatus for checking dimensions and/or shape includes one or more feelers (7,8;9;67,68), three for preference, adapted to touch the surface of a mechanical part (2;61) to be checked, a transducer and/or display device (33;78) with a movable part (34;77), and a mechanical transmission assembly (20) to transmit to the movable part of the transducer and/or display device the displacements of the feeler/s. The mechanical transmission assembly includes a shaft (22) defining an axis (A) and a guiding element (30) adapted to house a guide portion (25) of the shaft. The shaft includes a resiliently deformable portion (26), that is preferably a reduced diameter portion having axial symmetry, in an intermediate position between the guide portion and an abutment portion (27).