Digital Micrometer Stator Fixation for Precision
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Solution Overview
Problem
Existing digital micrometers face measurement errors due to the axial movement and inclination of the stator when enhancing encoder resolution for higher accuracy, making it difficult to achieve a spindle lead of 1 mm or more while maintaining precision.
Innovation Solution
The digital displacement measuring instrument fixes the stator to the body via a stator holder, preventing axial displacement and using an orientation maintaining unit to ensure the rotor's orthogonal orientation, thus avoiding measurement errors and allowing for a spindle lead of 1 mm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the encoder resolution is enhanced to increase measurement accuracy and efficiency, then the measurement precision is improved, but the stator movement is detected by the high-accuracy encoder which easily results in measurement errors
Solution Approach 1:
The harmful factor (spring bias on stator) is removed from the system. The stator is no longer biased by the spring toward the rotor, eliminating the source of axial fluctuation and inclination that causes measurement errors in high-resolution encoders.
Solution Approach 2:
Instead of allowing the stator to be movable and biased by a spring (conventional design), the invention inverts the approach by making the stator fixed and non-biased. The stator is directly or indirectly fixed to the body, reversing the traditional role assignment between stator and rotor support mechanisms.
2Productivity
If the lead of the spindle screw is enlarged to enhance measurement efficiency, then the productivity is improved, but the measurement precision deteriorates due to assembly accuracy requirements and encoder movement
Solution Approach 1:
The invention inverts the conventional design by fixing the stator to the body and eliminating the spring bias mechanism. This allows the spindle lead to be enlarged to 1 mm or more while maintaining measurement precision, as the fixed stator prevents the movement and inclination errors that would otherwise occur with higher leads.
3Ease of operation
If the stator is biased toward the rotor by the spring to maintain encoder operation, then the ease of operation is improved, but the stator axially fluctuates or inclines to the spindle which causes measurement errors
Solution Approach 1:
The spring bias mechanism is completely removed from the system. The stator is no longer biased by the spring toward the rotor, eliminating the source of axial fluctuation and inclination that causes measurement errors while the encoder continues to operate accurately with the fixed stator.
Solution Approach 2:
Instead of biasing the stator toward the rotor with a spring (conventional design), the invention inverts the approach by making the stator fixed and non-biased. The stator is directly or indirectly fixed to the body, reversing the traditional role assignment and eliminating the harmful fluctuations.
Data Source
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AI summary
A digital displacement measuring instrument includes a spindle (2) screwed into a body (10) to be axially advanced and retracted relative to the body (10); and an encoder (40) that detects a displacement of the spindle (2). The encoder includes a rotor (41) and a stator (42). The rotor is supported by a rotor bushing (44). The rotor bushing includes an engaging key (43) engageable with a key groove (23) axially provided on the outer circumference of the spindle (2), and is displaced in the axial direction of the spindle (2) via a position adjusting screw (51). The stator is fixed to the body via a stator bushing (45) in the vicinity of the spindle so as not to be displaceable in the axial direction of the spindle.