Contact Probe Edge Location via Stylus Orientation
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Solution Overview
Problem
Current methods for measuring the edge of objects, such as turbine blades, face challenges in accurately locating the edge due to uncertainty in the position of contact, leading to potential slippage or collision of the stylus tip, especially when the edge is small and out of position.
Innovation Solution
A method using a contact probe that takes multiple measurements along the edge, utilizing stylus orientation-related information to reduce uncertainty in the location of the edge, allowing for more precise alignment and subsequent accurate measurement by intersecting measurement volumes to determine the edge's location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stylus tip is brought into contact with the blade edge using conventional edge finding methods, then the edge location can be determined, but the stylus tip may clash with or slip off the edge causing measurement errors
Solution Approach 1:
The patent applies preliminary action by performing edge finding measurements at multiple discrete points before the actual edge scanning measurement. These preliminary measurements establish the edge location and orientation in advance, allowing the stylus to approach the edge correctly during the main measurement, thereby preventing slippage or collision and ensuring reliable measurements.
2Measurement precision
If three point measurements are taken to locate the edge before scanning, then the edge position can be found, but the process requires repeating this multiple times at different locations along the edge
Solution Approach 1:
The patent merges the edge finding function with the main edge scanning measurement by using the same stylus and measurement process for both purposes. Instead of separating edge location determination from edge measurement, the method combines them into a single integrated process, eliminating the need to repeat edge finding multiple times and significantly improving measurement efficiency.
3Ease of operation
If the stylus tip is driven into the blade surface in a direction not normal to the surface, then contact is made with the edge, but the stylus tip slips along the surface compromising the measurement
Solution Approach 1:
The patent applies feedback by using the preliminary edge finding measurements to determine the actual edge location and orientation, then using this information to guide the approach direction of the stylus during the main measurement. The measurement system feedbacks the edge geometry information back to control the stylus approach, ensuring it moves normal to the surface and preventing slippage.
Data Source
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AI summary
A method of locating a feature of an object in which the method comprises bringing a stylus of a contact probe mounted on a positioning apparatus into contact with the object to obtain at least first and second measurements of the object. Each which the measurements gives rise to a range of possible points of contact between the object and a part of the stylus along its length and therefore inherently containing uncertainty in the location of the object along said length. The at least first and second measurements are used to reduce the extent of said uncertainty which comprises using stylus orientation related information associated with the at least first and second measurements.