Scanning Head Synchronous Motion for Bore Measurement
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Solution Overview
Problem
Existing methods for measuring surface profiles using motorized scanning heads on coordinate positioning machines are limited in their ability to accurately measure large or small bores due to access restrictions and are not suitable for all surface geometries, particularly when the stylus tip cannot maintain contact or is misaligned.
Innovation Solution
The method involves synchronizing the motion of the coordinate positioning apparatus and the scanning head to maintain a constant lead angle, allowing for circular or spiral motion superimposed on linear motion, ensuring the surface sensing device remains within its measurement range and aligned with the surface, using a combination of linear and rotational movements to achieve precise surface profiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stylus is positioned using conventional linear motion of the coordinate positioning apparatus, then the measurement method is simple, but it cannot accurately measure large bores or very small bores due to access restrictions and stylus length limitations
Solution Approach 1:
The patent applies dynamic motion control by superimposing circular or spiral motion onto linear motion of the coordinate positioning apparatus. The scanning head rotates about one or more axes while the coordinate positioning apparatus moves linearly, creating a combined helical or spiral scanning path that enables the stylus to access and measure large bores and very small bores that cannot be measured with simple linear motion alone.
2Adaptability or versatility
If the scanning head is used to measure complex surfaces with restricted access, then measurement capability is improved, but misalignment and loss of contact occur when the lead angle varies
Solution Approach 1:
The patent maintains measurement reliability by controlling the lead angle parameter. The scanning head is rotated and the coordinate positioning apparatus moves in a coordinated manner such that the lead angle remains nominally constant throughout the scanning process. This parameter control ensures the stylus maintains proper contact with the surface and prevents misalignment, even when measuring complex surfaces with restricted access.
3Productivity
If conventional scanning methods are used for bores, then the process is simple, but productivity is reduced due to inability to measure large or very small bores and restricted access areas
Solution Approach 1:
The patent combines multiple motion modes into a unified scanning system. The circular or spiral motion of the scanning head is merged with the linear motion of the coordinate positioning apparatus through synchronized control. This combination enables the system to measure various features including large bores, very small bores, and restricted access areas in a single integrated process, significantly improving measurement productivity despite the increased complexity of the motion control system.
Data Source
AI summary
A method and apparatus for measuring a surface using a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus. The coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and the scanning head includes a drive for producing rotational movement of the surface sensing probe about one or more axis. The coordinate positioning apparatus is driven to provide relative movement between the member and the surface profile in a circular path and the probe head is driven to move the surface sensing device about said one or more axes, such that the surface sensing device maintains a nominally constant lead angle. The motion of the coordinate positioning apparatus and probe head is synchronous.