Hole Grip Length Measurement via Probe Array
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Solution Overview
Problem
Existing fastener grip length measurement systems are inefficient as they require multiple motions and may get stuck in holes, and struggle to accurately measure grip lengths in the presence of obstructions like nut plates or countersinks.
Innovation Solution
A shaft with an array of radially spaced ball plunger probes that generate signals upon contact with the hole walls, allowing for precise grip length measurement without needing to 'bottom out' the shaft, and capable of measuring through obstructions or countersinks with a single insertion motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single shaft with multiple probes is used for measurement, then measurement efficiency is improved, but device complexity increases
Solution Approach 1:
The measurement device is segmented into multiple independent probes arranged along a shaft, each capable of detecting hole wall contact separately. This segmentation allows simultaneous measurement at multiple positions, improving efficiency while keeping each individual probe relatively simple in structure
Solution Approach 2:
Multiple probes are combined onto a single shaft structure, integrating multiple measurement functions into one unified device. This merging approach enables comprehensive measurement in a single insertion operation, improving productivity without proportionally increasing overall device complexity
2Measurement precision
If the shaft is inserted deeply to bottom out for measurement, then measurement accuracy is improved, but the risk of getting stuck increases
Solution Approach 1:
The probes are positioned along the shaft to make contact with the hole wall before the shaft reaches the bottom. This preliminary contact action allows measurement to be taken at the appropriate depth without requiring the shaft to bottom out, eliminating the risk of getting stuck while maintaining measurement accuracy
Solution Approach 2:
The mechanical bottoming-out method is replaced with a sensor-based detection system. Instead of relying on mechanical contact at the bottom, the probes detect hole wall contact through electrical sensors, substituting mechanical force with electrical detection to achieve accurate measurement without excessive insertion depth
3Adaptability or versatility
If multiple insertion motions are required for measurement, then adaptability to obstructions is improved, but measurement time increases
Solution Approach 1:
The measurement process is made continuous through a single insertion motion that activates multiple probes simultaneously along the shaft. This continuous action eliminates the need for multiple separate insertion motions, reducing measurement time while maintaining adaptability to various obstruction scenarios through the array of probes
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
Enables precise and efficient grip length measurement along the central axis of a hole, allowing for accurate fastener selection without getting stuck, and can measure grip lengths regardless of obstructions or countersinks, simplifying the process and improving measurement accuracy.
Implementation Method 1
A sliding probe is supported on the handle for reciprocal motion generally parallel to and along the shaft in opposition to the fixed probe. The fixed probe is inserted through a hole to be measured, e.g., a hole extending through a stack of two or more panels, and is engaged against a far, opposite-facing surface of the panel stack.
Implementation Method 2
A spring is generally disposed between the ball and a closed end of the sleeve in a position to bias the ball toward the opening and into a position against the forward stop with a portion of the ball protruding through the opening.
Data Source
AI summary
A system for determining the grip length of a hole extending through a stack of panels so that a fastener of appropriate length can be selected for insertion into the hole. A shaft carrying an array of probes is inserted into the hole and the array generates signals indicating which probes of the array are contacting an inner wall of the hole.