Fiber Optic Tool Wear Measurement for Real-Time Machining

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Solution Overview

Problem

Current methods for monitoring tool wear during machining processes, especially in grinding, are inaccurate due to thermal and atmospheric effects, and lack real-time precision, leading to inefficiencies in determining the optimal dressing moment for grinding wheels and cutting tools.

Innovation Solution

A tool device equipped with an interferometric fiber optic sensor that measures changes in optical path length using a Fabry-Perot interferometer, allowing for direct and accurate monitoring of tool wear and process parameters during machining, enabling real-time analysis and optimization of tool conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If indirect sensors are used to monitor tool wear, then monitoring can be performed during machining, but measurement accuracy is impaired by thermal effects and atmospheric conditions

Engineering Contradiction:
Improvereal-time monitoring capabilityVSAvoidtool wear measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect mechanical/thermal sensors with direct optical fiber sensors that measure tool wear geometry optically. The fiber optic sensor system uses light reflection and optical path length changes to directly measure the cutting edge geometry, eliminating sensitivity to thermal and atmospheric conditions while maintaining real-time monitoring capability

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

Solution Approach 2:

The patent introduces optical fiber as an intermediary sensing element that can withstand harsh machining environments. The optical fiber transmits light to and from the cutting edge, acting as a mediator that is immune to thermal and atmospheric interference, thereby enabling accurate real-time measurements

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If vision sensors are used to measure tool wear, then direct measurement is possible, but measurements can only be done between machining runs as the wear area is not visible during machining

Engineering Contradiction:
Improvedirect wear measurement capabilityVSAvoidmeasurement timing flexibility
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent embeds the optical fiber sensor in the tool before machining begins, positioning the sensing element at the cutting edge. This preliminary placement enables continuous measurement throughout the machining process, eliminating the need to stop for measurements while maintaining direct measurement accuracy

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent enables continuous tool wear measurement throughout the entire machining operation. The optical fiber sensor remains active during machining, providing uninterrupted measurement data, thereby converting intermittent between-run measurements into continuous real-time monitoring

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If conductor paths are embedded in the cutting material to measure wear, then on-line measurement is possible, but the system becomes complex with multiple conductors and circuitry

Engineering Contradiction:
Improveon-line measurement capabilityVSAvoidsensor system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces complex electrical conductor paths and circuitry with a simpler optical fiber sensor system. The optical fiber uses light instead of electrical signals, eliminating the need for multiple conductors, connections, and external measuring circuitry while maintaining on-line measurement capability

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

Solution Approach 2:

The patent extracts the sensing function from complex electrical systems and isolates it into a single optical fiber element. This extraction simplifies the overall system by removing unnecessary conductors and circuitry, keeping only the essential optical sensing component

Inventive Principle:
Principle #2Taking out (Extraction)

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 reliable, low-cost, and precise monitoring of tool wear and process parameters, enhancing productivity by allowing for timely dressing and maintenance of machining tools, thereby improving the quality and efficiency of machining operations.

Implementation Method 1

A tool device equipped with an interferometric fiber optic sensor that measures changes in optical path length using a Fabry-Perot interferometer

Methodology Applied
Scientific EffectFabry-Perot interferometer: Fabry-Perot Interferometer

Implementation Method 2

the sensor is configured as a fiber optic sensor comprising at least one optical fiber providing an incident optical path and a reflected optical path for light beam emitted by a connectable light source

Methodology Applied
Scientific EffectOptical fiber: Optical Fibre

Data Source

PatentEP3666457B1Tool device and method for measuring a condition of a machining tool
Publication Date: 2023.08.09 AGATHON MASCHFAB
  • EP3666457B1 patent drawingFigure 1~2
  • EP3666457B1 patent drawingFigure 3~4
  • EP3666457B1 patent drawingFigure 5

AI summary

A tool device (1) for machining a workpiece (4) by cutting, milling, drilling or grinding, comprising a sensor (20) for detecting a condition of the tool device (1) during machining, wherein the sensor (20) is connectable to a receiving unit (40), which transmits data to an analysis unit (50) for analyzing the received data. The sensor (20) is configured as a fiber optic sensor (20) comprising at least one optical fiber (26) providing an incident optical path (22) and a reflected optical path (24) for a light beam emitted by a connectable light source (30) and with a distal end thereof lying in a surface (14, 74) of the tool device (1) such that the optical path length can be measured.