Rotary Table Error Correction Using Distance Sensors

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Solution Overview

Problem

Existing coordinate measuring machines face challenges in reducing errors associated with turntable deviations, such as translational and wobble movements, which are not effectively detected or corrected without prior measurement using test specimens, leading to inefficiencies and increased costs.

Innovation Solution

The arrangement includes at least three distance sensors arranged on a stationary part of the coordinate measuring machine to detect translational and wobble movements of a turntable relative to a fixed reference plane, allowing for online correction of coordinate measurement values without pre-measurement, using sensors that detect distances in radial and axial directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If test specimens are measured at various angular positions to determine correction values, then measurement precision is improved, but measurement time and operational complexity increase significantly

Engineering Contradiction:
Improvecoordinate measurement precisionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-determining the rotary table's angular position deviations and runout deviations through a single comprehensive measurement run, rather than requiring repeated measurements at various angular positions. This preliminary characterization of the rotary table's error profile enables subsequent correction without time-consuming repeated testing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements self-service by having the rotary table itself generate the correction values through its own measurement of coordinate measurement machine deviations. The system uses the rotary table's inherent geometric relationships and the coordinate measurement machine's own positioning capabilities to self-characterize and self-correct, eliminating the need for external test specimens.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If multiple measuring heads are used to measure rotational movement of the rotary table, then measurement precision is improved, but device complexity and assembly effort increase considerably

Engineering Contradiction:
Improverotational movement measurement precisionVSAvoidmeasuring system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by using the coordinate measurement machine's existing probe head for dual purposes: both for measuring workpiece coordinates and for characterizing the rotary table's geometric errors. This multi-functional approach eliminates the need for separate measuring heads while maintaining measurement precision through the use of the rotary table's own rotation during workpiece measurement.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses the workpiece coordinate measurement process itself as an intermediary to indirectly measure the rotary table's geometric deviations. By measuring the positions of points on the workpiece and analyzing the resulting coordinate data, the system extracts information about the rotary table's angular position deviations and runout without requiring direct measurement of the rotary table itself.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If test specimens are repeatedly measured at various angular positions, then correction accuracy is improved, but operational complexity and time consumption increase

Engineering Contradiction:
Improvecorrection accuracyVSAvoidoperational simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent applies continuity of useful action by incorporating the determination of rotary table correction values into the normal workpiece measurement process. The coordinate measurement machine continuously measures coordinate values during workpiece inspection, and this continuous data is used to simultaneously characterize the rotary table's geometric errors, eliminating interruptions for separate correction value determination.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent implements feedback by using the measured coordinate values from workpiece points to iteratively determine and refine the rotary table's angular position deviations and runout deviations. The system continuously monitors the measured positions, compares them against expected values, and uses the discrepancies to update the correction values, creating a closed-loop feedback mechanism that improves accuracy without requiring repeated manual intervention.

Inventive Principle:
Principle #23Feedback

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 solution enables real-time detection and correction of turntable errors during measurement, reducing the need for test specimen measurements and saving time, while ensuring accurate coordinate measurement values by using a minimal number of sensors effectively.

Implementation Method 1

at least three distance sensors for detecting a distance of the rotatable second part to the at least three distance sensors are arranged on the stationary first part

Methodology Applied
Scientific EffectOptical detection: Photoelectric Effect

Data Source

PatentEP3839416B1Arrangement for reducing errors in a rotating device during the determination of coordinate measurements of a workpiece
Publication Date: 2024.11.06 HEXAGON METROLOGY GMBH
  • EP3839416B1 patent drawingFigure 1
  • EP3839416B1 patent drawingFigure 2~3
  • EP3839416B1 patent drawingFigure 4

AI summary

Arrangement for reducing errors of a rotary device when determining coordinate measurement values ​​of a workpiece, wherein the arrangement comprises a coordinate measuring machine and the rotary device on which a workpiece can be arranged and rotatable about an axis of rotation of the rotary device, wherein the rotary device comprises a first part that is stationary relative to the coordinate measuring machine during a measurement and a second part that is rotatable relative to the first part, wherein at least three distance sensors arranged on the stationary first part are provided for detecting a distance of the rotatable second part to the at least three distance sensors. (Fig. 1).