Dental Restoration Tool Wear Detection Using Spindle Current

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Solution Overview

Problem

Current methods for determining grinder wear during dental restoration production are inaccurate, as they rely on empirical values and do not account for the actual condition of the grinder, potentially leading to the use of worn or defective tools.

Innovation Solution

A manufacturing device equipped with a detection device to measure the spindle current of a rotary spindle and a calculation device to calculate tool wear based on these measurements, allowing for precise detection of tool wear and enabling timely replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If empirical values are used to determine grinder wear, then the monitoring process is simple, but the accuracy of wear detection is poor

Engineering Contradiction:
Improvewear detection accuracyVSAvoidmonitoring system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces empirical wear determination methods with electrical measurement-based detection. By monitoring spindle motor current, the system substitutes mechanical wear assessment with electrical parameter analysis, achieving more accurate and objective wear detection without significantly increasing system complexity.

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

Solution Approach 2:

The system continuously monitors spindle current and provides feedback on tool wear status. This real-time feedback mechanism allows for accurate wear detection by comparing actual current values against reference values, enabling timely tool replacement decisions.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If spindle current monitoring is implemented, then tool wear detection accuracy is improved, but the device complexity increases

Engineering Contradiction:
Improvetool wear measurement accuracyVSAvoiddetection and calculation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The spindle motor current serves multiple functions: it drives the spindle and simultaneously provides wear detection data. This multi-functionality allows accurate wear measurement without adding separate sensing systems, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The spindle motor inherently provides the measurement signal through its own current consumption during operation. The system uses the motor's operational characteristics to self-diagnose tool wear, eliminating the need for external sensors or complex measurement apparatus.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If multiple measured values are processed, then calculation accuracy is improved, but processing time increases

Engineering Contradiction:
Improvespindle current measurement accuracyVSAvoidwear calculation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system processes multiple current measurements but applies selective filtering and averaging only when necessary to achieve sufficient accuracy. This partial processing approach balances measurement precision with processing efficiency, avoiding unnecessary computational overhead.

Inventive Principle:
Principle #16Partial or excessive 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 solution provides accurate and real-time monitoring of tool wear, preventing the use of worn tools, reducing material waste, and ensuring high precision in dental restoration manufacturing.

Implementation Method 1

a detection device (103) for detecting a spindle current of a rotary spindle (117)

Methodology Applied
Scientific EffectElectrical current measurement: Ohm's Law

Data Source

PatentEP4306074B1Dental restoration manufacturing apparatus
Publication Date: 2025.05.21 IVOCLAR VIVADENT AG
  • EP4306074B1 patent drawingFigure 1
  • EP4306074B1 patent drawingFigure 2
  • EP4306074B1 patent drawingFigure 3

AI summary

The present invention relates to a manufacturing device (100) for a dental restoration (200), comprising a tool (101) for machining a blank (201); a detection device (103) for detecting a spindle current of a rotary spindle (117); and a calculation device (105) for calculating wear of the tool (101) based on the spindle current.