Multi-Axis CNC Calibration Using Measured Rotation Axis Positions

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

CNC machines with multiple rotation axes suffer from inaccuracies due to imperfections in the mechanisms that move components, leading to variations in finished parts that do not meet predetermined geometrical tolerances.

Innovation Solution

A calibration method that involves measuring the position of a reference feature at multiple angular positions around each rotation axis, determining a coordinate system based on these measurements, and applying a displacement matrix to adjust the machine's coordinate system to account for practical imperfections, ensuring precise machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional calibration methods are used for CNC machines with multiple rotation axes, then the machining process can proceed, but machining precision deteriorates due to inaccuracies from mechanical imperfections in rotation mechanisms

Engineering Contradiction:

Improvemachining precisionVSAvoidconsistency of finished parts

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The calibration method changes the parameters used to define the coordinate system by measuring actual positions of rotation axes at multiple angular positions and using these measured parameters to create a corrected coordinate system that accounts for mechanical imperfections

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The method uses feedback from measuring the actual positions of rotation axes at multiple angular positions to identify deviations from ideal positions, then applies correction factors to the coordinate system to compensate for these deviations

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If the machine coordinate system is not calibrated to account for mechanical imperfections, then the calibration process is simplified, but manufacturing precision deteriorates due to variations in finished parts

Engineering Contradiction:

Improvegeometrical tolerancesVSAvoidcalibration process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The calibration method performs preliminary measurements of rotation axis positions at multiple angular positions before machining operations, establishing corrected coordinate system parameters in advance to prevent precision errors during actual machining

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The calibration process segments the measurement into multiple discrete angular positions around each rotation axis, measuring the position at each segment point to build a comprehensive correction model

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3822720B1Method of calibrating a machine having at least two rotation axes

Publication Date: 2025.10.01 PRATT & WHITNEY CANADA CORP

Figure 1
Figure 2
Figure 3

AI summary

The method can include measuring the tridimensional positions of a reference feature (34) for a first at least three different angular positions (P1, P1', P1") of the reference feature around the first rotation axis (24) and a same first reference angular position around the second rotation axis (28), the reference feature being fixed relative to the component (22); and measuring the tridimensional positions of the reference feature for a second at least three different angular positions (P2, P2', P2") of the reference feature around the first rotation axis and a same second reference angular position around the second rotation axis.