CMM Probe Reference Member for Vibration-Resistant Measurement
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Solution Overview
Problem
Current methods face challenges in accurately and efficiently measuring small features, such as recessed features, on coordinate positioning apparatuses, particularly due to noise from vibrations and the limitations of traditional contact probes in capturing geometrical dimensional information.
Innovation Solution
A method utilizing a contact probe with a reference/datum member placed on the part being measured, allowing the stylus to traverse the feature while collecting data, and extracting geometric dimension information, which reduces noise and enables accurate measurement of smaller features by steadying the probe against the part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional contact probe is used to measure small features on a coordinate positioning apparatus, then the measurement process can be performed, but the measurement precision deteriorates due to noise from vibrations and the probe's inability to steady against the part
Solution Approach 1:
A reference member is introduced as an intermediary element between the contact probe and the part being measured. The reference member engages with a reference feature on the part to provide a stable reference point, while the stylus measures the target feature. This intermediary structure filters out vibration noise by establishing a stable reference frame, thereby improving measurement precision without requiring the entire probe assembly to be rigidly stabilized.
Solution Approach 2:
The measurement function is segmented into two independent components: the reference member that engages with the reference feature to establish a stable baseline, and the stylus that performs the actual measurement of the target feature. This segmentation allows the reference member to filter vibrations independently while the stylus focuses on capturing precise dimensional data, resolving the contradiction between measurement precision and vibration noise.
2Measurement precision
If a dedicated profilometer is used to measure small features, then measurement accuracy can be achieved, but the device complexity and cost increase
Solution Approach 1:
The contact probe system is enhanced with a reference member to perform multiple functions: it can measure various features on a part while simultaneously using the reference member to filter vibrations and establish stable measurements. This multi-functionality allows a single CMM system to achieve profilometer-level accuracy for small features without requiring separate dedicated equipment, thereby reducing device complexity and cost while maintaining measurement precision.
3Productivity
If traditional contact probe measurement methods are used for small features, then the measurement process can be completed, but the productivity decreases due to the need for dedicated profilometers and multiple measurement systems
Solution Approach 1:
The reference member functionality is merged with the existing contact probe system, allowing the CMM to perform both general dimensional measurement and high-precision small feature measurement with a single integrated system. This merging eliminates the need for separate profilometers and multiple measurement systems, thereby improving productivity by consolidating measurement capabilities into one versatile apparatus while reducing the complexity of having multiple specialized devices.
Data Source
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AI summary
A method of inspecting at least one feature of a part, the at least one feature having a predetermined nominal shape, comprising: i) loading a contact probe onto a probe mount of a coordinate positioning apparatus which is configured to facilitate the exchanging of probes thereon and which is configured to facilitate relative movement of the probe mount and a part in three orthogonal degrees of freedom, the contact probe comprising a reference member for engaging the part, and the contact probe further comprising a stylus, the stylus being deflectable relative to the reference member and having a tip for contacting the surface to be measured, wherein the relative position of the tip and the reference member is transduced; ii) bringing the reference member and the stylus of the contact probe into contact with the part on one side of the feature, and then causing the stylus to traverse the feature whilst collecting measurement data concerning the relative position of tip and the reference member; and iii) extracting dimension information about the feature from the measurement data, and comparing the extracted dimension information to nominal dimension information for the nominal shape of the feature of the part.