Tool Vibration Amplitude Measurement Using a Laser Light Barrier

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Solution Overview

Problem

Existing methods for measuring vibration amplitude in machine tools are inadequate, particularly for non-rotationally symmetrical tools, as they either lose measurement signals due to complete shading or are limited by rotational symmetry, leading to inaccurate measurements.

Innovation Solution

A method and device utilizing a conventional tool measurement laser as a light barrier to measure vibration amplitude without contact, where the tool is rotated to appear rotationally symmetrical, allowing asymmetries to be compensated, and the tool tip's position is varied to calibrate the signal strength, enabling accurate amplitude measurement in multiple directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a light beam measurement method is used to measure vibration amplitude, then the measurement can be performed without contact, but complete obscuration of the light beam by the tool tip causes loss of measurement signal

Engineering Contradiction:
Improvecontactless measurementVSAvoidmeasurement signal loss
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent transitions from measuring vibration in a single linear dimension (along the light beam path) to measuring in multiple dimensions by detecting vibrations perpendicular to the light beam. This dimensional change allows the tool to vibrate without completely blocking the beam, as the vibration occurs in a different spatial plane.

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

Solution Approach 2:

The patent specifically addresses non-rotationally symmetrical tools by using vibrations perpendicular to the light beam direction. This approach exploits the asymmetry of the tool geometry in a way that creates measurable shadow effects without complete obscuration, converting the previously problematic asymmetric shape into a measurement advantage.

Inventive Principle:
Principle #4Asymmetry

2Measurement precision

If a light beam measurement method is used, then measurement can be performed, but non-rotationally symmetrical tools create measurement errors due to asymmetries protruding into the light beam

Engineering Contradiction:
Improvevibration amplitude measurementVSAvoidapplicability to non-symmetrical tools
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent measures vibrations in a direction perpendicular to the light beam rather than parallel to it. This dimensional change allows non-rotationally symmetrical tools to be measured accurately, as the asymmetric features that would normally block the beam are now viewed from a different angle where they create measurable shadow patterns without complete obscuration.

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

Solution Approach 2:

The patent pre-compensates for the effects of tool asymmetry by orienting the measurement perpendicular to the light beam direction. This preliminary adjustment of the measurement geometry prevents asymmetric features from causing measurement errors before they can interfere with the measurement process.

Inventive Principle:
Principle #9Preliminary anti-action

3Adaptability or versatility

If tool geometry and material properties vary, then different tools can be used, but resonance frequencies and vibration amplitudes cannot be calibrated at the factory

Engineering Contradiction:
Improvetool compatibilityVSAvoidcalibration requirement
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent enables each tool to perform its own calibration by using its actual vibration characteristics during measurement. The system determines resonance frequencies and vibration amplitudes in-situ for each specific tool, allowing the measurement system to adapt automatically to different tool geometries and materials without requiring external calibration procedures.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent allows the measurement system to dynamically adjust to different tool parameters (geometry, material) by measuring the actual vibration amplitude and resonance frequency of each tool during use. This parameter adaptation eliminates the need for factory calibration, as each tool's unique characteristics are automatically captured and used for measurement.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If additional measurement equipment is installed inside the machine tool, then measurement capability is improved, but cost and structural complexity increase

Engineering Contradiction:
Improvevibration measurement capabilityVSAvoidstructural modifications
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the existing light barrier serve multiple functions: its primary function for detecting tool breakage is maintained, and additionally it is used for measuring vibration amplitude and resonance frequency. This multi-functionality allows vibration measurement capability to be added without installing separate dedicated measurement equipment, avoiding additional structural modifications.

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

Solution Approach 2:

The patent combines the vibration measurement function with the existing tool breakage detection light barrier system. By merging these two measurement functions into a single system, the patent eliminates the need for separate vibration measurement equipment and reduces structural complexity while maintaining both measurement capabilities.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables cost-effective, tool-specific measurement of vibration amplitude in the ultrasonic frequency range without damaging the tool, allowing for precise characterization of tool vibrations in various directions using existing machine tool equipment.

Implementation Method 1

the shadowing of a light beam by the oscillating tip of the capillary is detected by a light receiver

Methodology Applied
Scientific EffectShadowing: Shadow

Implementation Method 2

An electrical voltage causes a change in the thickness of the piezo discs. For certain frequencies, this creates a standing wave in the tool holder (resonant excitation).

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

For certain frequencies, this creates a standing wave in the tool holder (resonant excitation)

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3347685B1Method and device for determining a vibration amplitude of a tool
Publication Date: 2024.05.22 DMG MORI ULTRASONIC LASERTEC GMBH
  • EP3347685B1 patent drawingFigure 1
  • EP3347685B1 patent drawingFigure 2
  • EP3347685B1 patent drawingFigure 3

AI summary

The present invention relates to a method for determining a vibration amplitude of a tool 3, comprising the steps: generating a light beam 23 of a light barrier 2 with a transmitter 21 for generating the light beam 23 and a receiver 22 for detecting a light intensity of the light beam 23; generating a receiver signal on the basis of a light intensity, detected by the receiver 22 of the light barrier 2, of the light beam 23; positioning a tooltip 31 of the tool 3 in the light beam 23; causing the tool 3 to vibrate ; determining the vibration amplitude of the tool 3 from a modulation of the receiver signal brought about by the vibration of the tool 3.