Analogue Probe Scanning Offset Traverses
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Solution Overview
Problem
Analogue measurement probes on machine tools face challenges due to the lack of real-time control capabilities, leading to inefficient data collection and potential over-deflection issues when scanning objects with varying or unknown shapes, as opposed to dedicated CMMs which have advanced control loops for maintaining probe deflection within preferred ranges.
Innovation Solution
A method involving offset traverses with the analogue probe to manage its position relative to the object, updating the course of motion based on previous data to maintain the probe within its preferred measurement range, ensuring efficient data collection and avoiding over-deflection by adjusting the probe's path dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analogue probes are used on machine tools without real-time control, then measurement detail and surface form acquisition are improved, but measurement reliability and avoidance of over-deflection deteriorate
Solution Approach 1:
The system performs preliminary scanning at a reduced rate to build an initial data set and determine a preferred measurement range for the analogue probe. This preliminary action establishes safe operating parameters before high-speed measurement, preventing over-deflection while enabling detailed measurement.
Solution Approach 2:
The measurement system dynamically adjusts the probe's movement rate based on real-time feedback from the analogue probe's output signal. When the probe approaches the boundaries of its preferred measurement range, the system automatically reduces speed to maintain measurement reliability while continuing to collect detailed surface data.
2Productivity
If the analogue probe moves quickly across the workpiece surface, then productivity is improved, but the risk of over-deflection and measurement errors increases
Solution Approach 1:
The measurement process uses periodic scanning with alternating phases: a preliminary scan at reduced speed to establish safe parameters, followed by high-speed measurement phases that periodically check probe output signals. This periodic approach maintains productivity while ensuring measurement accuracy through intermittent verification.
Solution Approach 2:
The system continuously monitors the analogue probe's output signal and uses this feedback to adjust the probe's movement rate in real-time. When the signal indicates the probe is approaching the boundaries of its preferred measurement range, the system automatically reduces speed to prevent over-deflection, maintaining both productivity and accuracy.
3Measurement precision
If the probe is kept within its preferred measurement range through real-time control, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses the analogue probe's own output signal as the basis for determining when to adjust measurement parameters. The probe essentially serves itself by providing the feedback information needed to maintain optimal operation, eliminating the need for external sensors or complex monitoring systems.
Solution Approach 2:
The system maintains measurement precision by dynamically changing the probe's movement rate parameter based on the analogue output signal. When the signal indicates the probe is approaching the boundaries of its preferred measurement range, the system adjusts the speed parameter to keep measurements within the optimal range, avoiding the need for complex positional control systems.
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
This approach enhances the efficiency of scanned measurement data acquisition by allowing the analogue probe to maintain measurements within its preferred range, reducing the risk of over-deflection and enabling more accurate data collection on both known and unknown objects, even in harsh machine tool environments.
Implementation Method 1
transducers within the probe which measure the deflection of the stylus relative to the probe body
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
A method of building up a measurement data set for a surface of an object using an analogue measurement probe mounted on a machine tool apparatus which obtains scanned measurement data of the surface over a plurality of offset traverses. Subsequent traverses are offset from previous traverses such that over a series of traverses the analogue probe's surface detecting region progresses i) laterally across the object, and/or ii) away from or towards the object. The course of relative motion for at least one subsequent traverse is generated and/or updated based on data obtained during at least one previous traverse.