Surface Profile Measuring Device with Non-Accelerated Probe Tip
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Solution Overview
Problem
Existing surface profiling measurement devices face inaccuracies due to centrifugal forces caused by probe acceleration, leading to measurement errors from either loss of contact or elastic deformations, which are difficult to correct without prior knowledge of the workpiece surface profile.
Innovation Solution
A measuring device with a carriage moving in a straight line, where the probe tip is not accelerated, detects deflections to calculate dynamic force changes, allowing for accurate surface profiling by maintaining a constant measuring force within specified limits, and automatically adjusts parameters to prevent measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the probe is accelerated to trace the target contour, then the measurement speed is improved, but centrifugal forces cause measurement errors due to stylus deflection
Solution Approach 1:
Instead of accelerating the probe to improve measurement speed, the invention inverts the approach by moving the carriage in a straight line without acceleration and allowing the probe tip to follow the surface profile passively. This eliminates centrifugal forces while maintaining measurement capability through the deflection sensor that detects probe tip displacement.
Solution Approach 2:
The invention replaces the mechanical stylus deflection measurement system with a sensor-based detection system. The deflection sensor directly measures the probe tip position in the measuring direction, eliminating the need for mechanical stylus deflection detection that is susceptible to centrifugal force errors.
2Reliability
If the measuring force is increased to prevent probe lift-off, then contact stability is improved, but elastic deformations occur in the measuring device
Solution Approach 1:
The invention uses feedback by continuously monitoring the deflection sensor output to determine the actual measuring force. The evaluation unit processes the deflection signal to calculate dynamic force changes and compares them with the nominal measuring force, enabling real-time detection and correction of force deviations to maintain both contact stability and measurement accuracy.
Solution Approach 2:
The invention changes the parameter of measuring force from a fixed high value to a dynamically adjusted value. By monitoring deflection and calculating actual force, the system adapts the measuring force to match the nominal value, preventing both probe lift-off and elastic deformations through optimal force control.
3Measurement precision
If the measuring force is decreased to avoid elastic deformations, then measurement accuracy is improved, but the probe may lift off the workpiece surface
Solution Approach 1:
The deflection sensor provides continuous feedback on probe tip position, enabling the evaluation unit to detect when the measuring force approaches levels that could cause probe lift-off. This feedback mechanism allows real-time adjustment to maintain optimal contact force.
Solution Approach 2:
The measuring force parameter is dynamically adjusted based on deflection monitoring. The system increases force when needed to prevent lift-off and decreases it to avoid deformations, optimizing the parameter in real-time rather than using a fixed conservative value.
4Measurement precision
If trajectory acceleration is corrected to improve measurement accuracy, then measurement precision is improved, but prior knowledge of the surface profile is required
Solution Approach 1:
Instead of correcting acceleration effects after they occur, the invention inverts the approach by preventing acceleration entirely. The carriage moves in a straight line at constant velocity, and the probe tip naturally follows the surface profile without experiencing centrifugal forces, eliminating the need for correction algorithms.
Solution Approach 2:
The invention extracts the probe tip acceleration from the measurement system by decoupling the carriage motion from probe tip tracking. The carriage provides stable linear motion while the probe tip independently follows the surface, separating the functions of positioning and surface following.
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 enables precise surface profiling with reduced measurement errors by detecting and correcting dynamic force deviations, ensuring accurate contact and preventing elastic deformations, even in the nanometer range, with automatic error correction mechanisms.
Implementation Method 1
A sensor detects the deflection of the scanning end and generates a deflection variable s which describes the deflection z T of the scanning end 40 in the measuring direction z
Implementation Method 2
The evaluation unit 21 determines the actual deflection and, from this, the acceleration of the scanning end 40 in the measuring direction z
Implementation Method 3
The dynamic force F dyn which is proportional to the acceleration a T is then determined, with the dynamic force F dyn representing the deviation of the measuring force F m from the static pressing force F stat
Data Source
Figure 1~2
AI summary
The invention relates to a measuring device (10) for measuring a surface profile of a workpiece and to a corresponding measuring method. During measurement, a measuring slide (15) is moved in a moving direction (x) in a linear manner and at a distance from the workpiece surface such that the probe tip (25) which is arranged at the slide is not accelerated by the movement of the measuring slide (15). The free end (40) of the probe tip (25) rests on the workpiece surface (11) with a measuring force (Fm) and is deviated during measurement in a measuring direction (z) transverse to the moving direction (x) such that a path-dependent deviation (zT) of the probe end (40) is caused by the surface profile. A measuring sensor (45) detects a deviation variable (s) which describes the deviation of the probe end (40) in the measuring direction (z). In an analysis unit (21) a measuring force alteration variable is generated which is dependent on the deviation variable (s), the measuring force alteration variable describing the alteration of the measuring force (Fm) between the probe end (40) and the workpiece surface (11). On the basis of the measuring force alteration variable it is possible to detect measuring errors or measuring inaccuracies.