Dental Milling Touch Probe Alignment for Precise Workpiece Positioning

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Solution Overview

Problem

Existing milling machines have imprecise detection systems for the relative position between the workpiece and the tool, leading to inaccuracies and unproductive idling, especially when clamping or aligning workpieces.

Innovation Solution

A tactile sensor with a deflectable touch probe is used to detect the approach between the workpiece and the tool in multiple spatial directions, allowing for precise alignment without rotating the workpiece, and emitting a signal when a predetermined threshold is reached, enabling improved accuracy and reproducibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If detection devices are used to detect the relative position between workpiece and tool, then the milling machine can avoid unproductive idling, but the detection accuracy is insufficient

Engineering Contradiction:
Improvedetection reliabilityVSAvoidposition detection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces optical scanning systems and braking-based detection methods with a tactile sensor system that uses direct mechanical contact between the probe and workpiece surface. The deflectable sensing element provides precise mechanical detection of surface topology, achieving higher measurement accuracy while maintaining reliable detection of workpiece presence and position.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the workpiece is rotated to detect approach in multiple directions, then comprehensive position detection is achieved, but the detection process becomes more complex and time-consuming

Engineering Contradiction:
Improvemulti-directional detection capabilityVSAvoiddetection process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from a single-point detection approach to a multi-point tactile sensor array that can detect workpiece approach and surface topology simultaneously in multiple spatial directions. The deflectable sensing element with multiple contact points provides three-dimensional position information without requiring workpiece rotation, simplifying the detection process while maintaining comprehensive measurement capability.

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

3Productivity

If the milling machine operates at high speed, then productivity is improved, but the detection of precise position requires complete braking upon contact

Engineering Contradiction:
Improvemilling speedVSAvoidbraking time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent performs preliminary detection of workpiece presence and position using the tactile sensor before the high-speed milling operation begins. The deflectable probe detects workpiece approach and establishes precise position information in advance, allowing the milling machine to operate continuously at high speed without repeated braking for detection during the machining process.

Inventive Principle:
Principle #10Preliminary action

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 tactile sensor provides precise detection of the workpiece's position with an accuracy of 0.005 mm and repeatability of 0.002 mm, reducing errors due to incorrect clamping or alignment and ensuring accurate milling results.

Implementation Method 1

this sensor has a sensing element that is deflectable. 'Deflection' here encompasses both a detectable movement in the two transverse directions (X and Y) and in the longitudinal direction of the sensor (Z direction). The deflection of the sensor detects the approach between a surface of the workpiece and the probe.

Methodology Applied
Scientific EffectDeflection: Deformation

Data Source

PatentEP3848666B1Dental milling machine and dental milling method
Publication Date: 2023.06.21 IVOCLAR VIVADENT AG
  • EP3848666B1 patent drawingFigure 1~2
  • EP3848666B1 patent drawingFigure 3~5
  • EP3848666B1 patent drawingFigure 6

AI summary

The invention relates to a milling machine (10) with a milling spindle (12) and a workpiece holder (24) which is movably mounted relative to the milling spindle (12) in at least 3 or 4 spatial directions, with a workpiece which is clamped to the workpiece holder (24), with a probe relative to which the workpiece can be brought into contact and relative to which the probe can be moved to probe the workpiece, wherein the probe is designed as a sensing sensor (18) with a deflection and detection of a deflection of its sensing element (30) in at least 1 spatial direction, or in 2 or 3 spatial directions.