NC Machine Tool Measurement with Dual Reference Elements

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Solution Overview

Problem

Existing methods for measuring numerically controlled machine tools are inefficient, requiring multiple setups and introducing additional error influences, with limited ability to detect inaccuracies in certain areas and being sensitive to environmental changes.

Innovation Solution

A method using two measuring elements with a spacer element, allowing for simultaneous measurement of multiple axes and compensation for errors, with a rigid connection and low thermal expansion material to maintain accuracy and stability across varying conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple measuring setups are used to measure different axes, then measurement coverage is improved, but measurement time and error introduction increase

Engineering Contradiction:
Improvemeasurement coverageVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent combines multiple measuring elements (at least two) into a single measuring setup that can simultaneously measure multiple axes. The measuring elements are arranged at different positions and/or orientations on a common support structure, enabling comprehensive measurement of machine tool axes without requiring multiple separate setups, thus reducing measurement time while maintaining coverage.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The measuring setup is designed with universal applicability to measure different types of machine tool axes (linear and rotary) using the same basic configuration. The measuring elements can detect positions along multiple axes simultaneously, making the setup multi-functional rather than requiring specialized setups for each axis type.

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

2Measurement precision

If measuring setup is relocated to measure specific axes, then measurement accuracy for specific axes is improved, but additional errors are introduced

Engineering Contradiction:
Improveaxis measurement accuracyVSAvoidmeasurement error
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

By combining multiple measuring elements into a single rigidly connected setup, the patent eliminates the need to relocate the measuring device between axes. All axes are measured simultaneously from a fixed reference frame, preventing the introduction of additional errors that would occur during relocation and setup changes.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If support element is positioned close to rotation center, then circular movement measurement is improved, but positioning error sensitivity increases

Engineering Contradiction:
Improvecircular movement measurementVSAvoidpositioning error sensitivity
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent measures circular movement not by positioning a single element close to the rotation center, but by using multiple measuring elements arranged at different positions and determining the circular path through mathematical evaluation of their coordinated measurements. This dimensional approach reduces sensitivity to individual positioning errors while maintaining measurement precision.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 calibration of machine geometry and kinematics, significantly increasing machine accuracy while simplifying the measurement process and reducing error influences.

Implementation Method 1

a spacer element (2) on which the two measuring elements (3) are arranged at a distance from one another... made of a material having a thermal expansion coefficient of less than or equal to 3.0 10^-6

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP4027104B1Method for measuring a numerically controlled machine tool
Publication Date: 2024.07.31 DMG MORI PFRONTEN GMBH
  • EP4027104B1 patent drawingFigure 1
  • EP4027104B1 patent drawingFigure 2
  • EP4027104B1 patent drawingFigure 3

AI summary

The present invention relates to a method for measuring a numerically controlled machine tool 100 using a device 1 comprising a first measuring element 3 for measurement by a measuring device 10 and a second measuring element 3 for measurement by the measuring device 10, which is arranged at a distance from the first measuring element 3, wherein the method comprises the steps of attaching the device 1 to a linearly and/or rotaryally movable machine part 20 of the machine tool 100, determining a respective actual position of the first measuring element 3 of the device 1 with the measuring device 10 at at least two positions of the machine part 20 on the numerically controlled machine tool 100,Determining the actual position of the second measuring element 3 of the device 1 with the measuring device 10 at at least two positions of the machine part 20 on the machine tool 100 and determining one or more coordinate reference parameters of one or more controllable axes of the machine tool 100 based on the determined actual positions of the first and second measuring element 3 at the at least two positions of the machine part 20 of the machine tool 100, the respective target positions of the first and second measuring element 3 at the at least two positions of the machine part 20 of the machine tool 100 and a known distance between the first and second measuring element 3.