Magnetic Scale Device for Multi-Axis Error Correction
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Solution Overview
Problem
High-precision machining tools face challenges in maintaining reproducibility due to changes in workpiece weight, cutting reaction forces, and guide surface wear, which existing two-dimensional or three-dimensional scales cannot effectively correct, especially in environments contaminated with cutting fluids and chips.
Innovation Solution
A compact magnetic scale device with incremental and absolute tracks, utilizing multiple incremental signal detection heads and a processing unit to generate relative positional information, parallel movement amounts, and angular information, allowing for correction of movement errors across axes while being resistant to environmental loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-dimensional holographic scale is used to measure movement errors with sub-nanometer resolution, then measurement precision is improved, but the device cannot be practically installed on machine tools due to lack of detection area and high cost
Solution Approach 1:
The patent divides the measurement function into separate one-dimensional linear scales installed on each axis independently, rather than using a single two-dimensional scale. This segmentation allows each scale to have a compact form factor suitable for actual machine tool installation while maintaining high measurement precision through the use of multiple detection heads on each axis.
Solution Approach 2:
The patent transitions from a two-dimensional measurement approach to a multi-axis one-dimensional measurement system. By installing linear scales on multiple axes (X, Y, Z) and using multiple detection heads, the system achieves three-dimensional measurement capability without requiring a large two-dimensional detection area, thus resolving the contradiction between precision and device complexity.
2Measurement precision
If correction values are acquired under ideal conditions without workpiece weight and cutting forces, then measurement reproducibility is improved, but the correction values cannot account for actual machining conditions causing errors to persist
Solution Approach 1:
The patent implements a feedback mechanism where the scale device continuously monitors actual position during machining operations with workpieces installed. The system compares commanded positions with actual measured positions and generates correction values that account for real machining conditions including workpiece weight and cutting forces, thereby improving both precision and adaptability.
Solution Approach 2:
The patent performs preliminary measurement and correction value generation under actual machining conditions with workpieces installed, rather than under ideal empty conditions. This preliminary action ensures that the correction values inherently account for gravitational effects, cutting forces, and other machining-specific factors, making the system adaptable to real-world conditions.
3Measurement precision
If optical scales are used for high-precision measurement, then measurement precision is improved, but the scales become sensitive to environmental contamination from cutting fluids and chips
Solution Approach 1:
The patent replaces optical measurement systems with a magnetic-based linear scale system. The linear scales use magnetic fields rather than optical fields for measurement, making them inherently resistant to contamination from cutting fluids and chips. This substitution maintains high measurement precision while eliminating the harmful sensitivity to environmental factors present in optical 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
The solution enables accurate correction of movement errors in high-precision machining tools, maintaining precision and reliability even in challenging environments, with a compact and cost-effective design that reduces the need for bulky detection areas and high manufacturing costs.
Implementation Method 1
a scale main body having at least two incremental tracks; at least two or more incremental signal detection heads for detecting incremental signals from the incremental tracks
Data Source
AI summary
A scale device includes a scale main body having at least two incremental tracks, at least two or more incremental signal detection heads for detecting incremental signals from the incremental tracks, and an operation processing unit that generates, based upon detection outputs by the two or more incremental signal detection heads, relative positional information in a measuring direction of a measuring axis and parallel movement amount information in a direction orthogonal to the measuring direction.