Calibration Artefact Locking for Accurate Machine Tool Axis Setup
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Solution Overview
Problem
Existing calibration devices for machine tools with rotary axes are complex and costly, particularly when determining the Z-position of a calibration sphere, as they often require manual procedures that are inaccurate and operator-dependent.
Innovation Solution
A calibration device with a deflection mechanism that allows a calibration artefact to be moved into a known position using a reference tool, then locked in place, eliminating the need for sensing contact or measuring deflection, and reducing complexity and cost by allowing arbitrary positioning within the machine coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual procedures are used to determine the Z-position of a calibration sphere, then the calibration can be performed, but the accuracy is poor and results vary from operator to operator
Solution Approach 1:
The patent replaces manual mechanical procedures with an automated sensor-based system. A sensor detects when the calibration artefact contacts the machine tool component, automatically determining the Z-position without operator intervention. This eliminates operator dependency while maintaining measurement accuracy.
Solution Approach 2:
The calibration system performs self-determination of the Z-position through automatic sensor detection. The sensor autonomously detects contact between the calibration artefact and machine component, calculating the position without requiring operator skill or judgment, thereby eliminating variability between operators.
2Measurement precision
If automated calibration devices with sensors are used to achieve high accuracy, then measurement precision improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts only the essential sensing function needed for calibration - a simple contact detection sensor that detects when the calibration artefact touches the machine component. This minimal sensing approach achieves high accuracy without requiring complex measurement systems, reducing device complexity while maintaining precision.
Solution Approach 2:
The patent uses a simple, inexpensive sensor for contact detection rather than expensive high-precision measurement systems. The sensor performs its function of detecting contact and determining position, then can be replaced or reset, providing cost-effective automation without complex machinery.
3Ease of operation
If a deflection mechanism is used to allow the calibration artefact to move into a known position, then flexibility and ease of positioning improve, but device complexity increases
Solution Approach 1:
The patent employs a deflection mechanism that allows the calibration artefact to dynamically move from a rest position to a contact position with the machine tool component. This dynamic positioning capability enables flexible adjustment and known position determination while using a relatively simple mechanical deflection system rather than complex actuation mechanisms.
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
The solution provides a cost-effective and accurate calibration method that reduces operator variability and complexity, enabling precise calibration of machine tools without the need for expensive automation or high-precision sensors.
Implementation Method 1
A spring is provided which biases the calibration artefact into a known and repeatable rest position relative to the base
Implementation Method 2
The base may be magnetically attachable to the bed of a machine tool
Data Source
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Figure 3a~3b
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AI summary
A calibration device for a co-ordinate positioning machine, such as a machine tool, is described. The device (200) comprises a base (30; 130; 202), a calibration artefact (34;134), and a deflection mechanism (32) that attaches the calibration artefact (34;134) to the base (30;130; 202) and allows the calibration artefact (34;134) to be moved relative to the base (30;130; 202) by application of an external force. The device further comprises a releasable lock that, when locked, immobilises the calibration artefact (34;134) relative to the base (30; 130; 202).