Machine Tool Calibration Sphere with Deflection Sensing
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Solution Overview
Problem
Current calibration methods for machine tools, particularly five-axis machines, are inaccurate and operator-dependent when determining the z-position of a calibration sphere, relying on manual procedures that vary in precision.
Innovation Solution
A calibration device with a deflection mechanism and sensor that allows a calibration artefact, such as a sphere, to move relative to its base under external force, enabling automated and precise measurement of its position using a reference tool, eliminating the need for manual gauge block alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual procedures are used to measure the sphere centre z-position, then the calibration can be performed, but the measurement precision varies from operator to operator and is inaccurate
Solution Approach 1:
The patent replaces manual mechanical measurement procedures with an automated sensor-based system. A sensor detects the position of a calibration artefact (sphere) and automatically determines the sphere centre z-position, eliminating operator dependency and improving measurement precision and repeatability
Solution Approach 2:
The calibration system performs self-measurement by using the machine tool's own spindle and sensor to automatically measure the calibration artefact position. The system autonomously completes the measurement process without requiring manual intervention, ensuring consistent results across different operators
2Extent of automation
If a rigidly mounted calibration sphere is used, then the structure is simple, but the automated measurement of sphere centre z-position cannot be performed
Solution Approach 1:
The patent introduces a dynamic element (deflectable mechanism) that allows the calibration artefact to move slightly in response to external forces. This enables automated measurement by allowing a reference tool to gently contact and deflect the artefact, with the sensor detecting the deflection to calculate the sphere centre position automatically
Solution Approach 2:
The patent introduces a deflectable mechanism as an intermediary between the rigid base and the calibration artefact. This intermediary component allows controlled movement and force transmission, enabling automated measurement while maintaining overall system stability through the base connection
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 improved accuracy and consistency in calibration by automating the process, reducing variations between operators and simplifying the calibration technique compared to existing methods.
Implementation Method 1
a deflection mechanism that attaches the calibration artefact to the base and allows movement of the calibration artefact relative to the base when an external force is applied to the calibration artefact, the deflection mechanism also maintaining the calibration artefact in a defined rest position relative to the base in the absence of an applied external force
Implementation Method 2
a sensor for sensing the extent of movement of the calibration artefact relative to the base
Data Source
AI summary
A calibration device for a machine tool is described that includes a base attachable to a machine tool and a calibration artefact, such as a sphere of known radius. A deflection mechanism attaches the calibration artefact to the base and allows movement of the calibration artefact relative to the base when an external force is applied to the calibration artefact. The deflection mechanism also maintains the calibration artefact in a defined rest position relative to the base in the absence of an applied external force. A sensor is provided for sensing the extent of movement of the calibration artefact relative to the base. A method of using the device with a reference tool to accurately determine a position of a calibration artefact is also described.