Rotating Spindle Displacement Measurement via Intermediate Decoupling
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Solution Overview
Problem
Current devices for measuring displacements of rotating objects, such as machine tool spindles, face challenges in achieving high precision due to rotational forces and thermal expansion, which affect machining accuracy.
Innovation Solution
A device comprising a rotor coupled to the rotating object, an intermediate part decoupled from the rotor via a radial bearing that transmits displacements in four freedoms, and measuring means on both the intermediate part and stator to measure displacements in five degrees of freedom, including contactless scanning, with a focus on minimizing thermal influence and maintaining structural rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a radial bearing is used to decouple rotation, then rotational forces are isolated from the measurement system, but measurement precision deteriorates due to bearing play and flexibility
Solution Approach 1:
The patent introduces an intermediate part as a mediator between the rotor and stator. This intermediate part carries the measuring standard and is coupled to the rotor via the radial bearing, while the scanning head on the stator scans this intermediate standard. The intermediary structure allows rotational decoupling through the bearing while maintaining precise measurement capability by keeping the measurement reference (intermediate standard) directly connected to the rotating component's displacement.
2Temperature
If contactless scanning is used to avoid friction, then thermal influence is reduced, but measurement complexity increases due to multiple measuring standards and scanning heads
Solution Approach 1:
The patent segments the measurement system into multiple independent measurement channels, each with its own measuring standard and scanning head arrangement. Five separate measuring means are provided, each measuring displacement in a specific degree of freedom. This segmentation allows contactless scanning for each channel independently, reducing thermal influence while maintaining manageable complexity through modular design where each measuring means can be independently configured and calibrated.
3Measurement precision
If multiple measuring means are used to cover all degrees of freedom, then measurement completeness is improved, but device complexity increases
Solution Approach 1:
The patent employs a universal measurement approach where the intermediate part serves multiple functions: it is coupled to the rotor, carries the measuring standard, and transmits displacement information to the scanning heads. The radial bearing also serves dual purposes by both decoupling rotation and transmitting displacement in four degrees of freedom. This multi-functionality reduces the need for separate dedicated components for each function, managing device complexity while achieving complete six-degree-of-freedom measurement coverage.
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
Enables precise measurement of displacements in rapidly rotating objects, enhancing machining accuracy by accurately detecting and isolating displacements caused by rotational and thermal effects.
Implementation Method 1
a radial bearing with an axis of rotation that decouples the rotation of the rotor is arranged between the rotor and the intermediate part. The radial bearing is designed to decouple rotations of the rotor about the axis of rotation from the intermediate part.
Implementation Method 2
measuring means which are designed to measure displacements of the intermediate part relative to the stator in these five degrees of freedom, these measuring means each comprising the components measuring standard and scanning head for contactless scanning of the measuring standard
Data Source
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AI summary
The invention relates to a device particularly suited for measuring thermally induced displacements of a rapidly rotating spindle with high accuracy. The device comprises a rotor (1) to which the spindle to be measured is rigidly coupled. The rotor (1) is mounted axially and radially without play in an intermediate part (2), so that all movements of the rotor (1) – except for rotation about the axis of rotation (D) – are transmitted to the intermediate part (2). The movements transmitted from the spindle to the rotor (1) and to the intermediate part (2) in five degrees of freedom are measured by measuring instruments arranged on the intermediate part (2) and the stator (3).