Milling Machine Calibration Using Dimple Fixture Registration
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Solution Overview
Problem
Existing milling machine calibration techniques in CAD/CAM systems for dental restorations are limited by slow and inaccurate calibration processes, which affect the precision and efficiency of tool path execution.
Innovation Solution
A calibration technique using a cube-shaped fixture with precision-milled dimples and an elongated calibration pin, combined with x-axis directional position error-based probing and Singular Value Decomposition (SVD)-based registration methods, to accurately map spindle-mandrel spatial relationships and improve calibration speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then the calibration process is simple to implement, but the calibration speed is slow and accuracy is limited
Solution Approach 1:
The calibration fixture is pre-designed with precisely positioned dimples according to a predetermined pattern before calibration. This preliminary preparation of reference features eliminates the need for time-consuming measurement setup during calibration, while ensuring high accuracy through pre-established geometric relationships
Solution Approach 2:
The patent replaces traditional mechanical measurement methods with an automated probing system that uses position error-based detection. The probe automatically detects dimple locations by measuring position errors, substituting manual mechanical measurement with automated sensor-based detection to improve both speed and accuracy
2Manufacturing precision
If traditional calibration fixtures are used, then the device complexity is low, but the manufacturing precision of calibration is insufficient
Solution Approach 1:
The calibration system is segmented into distinct functional components: a calibration fixture with precisely positioned dimples, a probing system for detection, and software for SVD-based registration. This segmentation allows each component to be optimized independently, achieving high calibration precision through specialized design of each element
Solution Approach 2:
The patent changes the calibration approach by using position error as a detectable parameter instead of direct dimensional measurement. By monitoring position errors during probing and using SVD to register transformations, the system achieves higher manufacturing precision through parameter-based detection and mathematical optimization
Data Source
AI summary
A milling machine calibration technique, and article of manufacture are described. The article comprises a calibration fixture, together with a calibration pin. The calibration fixture preferably is shaped as a cube, and each of the side faces of the cube comprise a set of indentations (dimples or features) that are configured in a predetermined pattern. A preferred pattern is a “5-dimple” pattern. To find a mapping between axis coordinates (of a mill spindle) and the mill mandrel at some orientation, the calibration fixture is inserted into the mandrel, and the calibration pin is inserted into a collet. Using an x-axis directional position error-based probing mechanism, the system then registers the exact position of each of the five (5) dimples on the surface of the die. Using the positional information so determined, spindle-mandrel spatial relationships for one or more orientations of the mandrel are then identified for calibration purposes.