Grinding Machine State Detection Using Difference Sound Spectra

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Solution Overview

Problem

Conventional grinding machines require trained personnel to set up and monitor their operating states, which is time-consuming and prone to errors, as they rely on manual selection of frequency bands for evaluating structure-borne sound signals.

Innovation Solution

A machine tool with a measuring device equipped with structure-borne sound sensors that form a broadband difference spectrum between a reference and actual spectrum, allowing the control device to evaluate the power over time, enabling autonomous determination of the machine's state without manual intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual selection of frequency bands is used for evaluating structure-borne sound signals, then the machine tool requires trained personnel for setup and monitoring, but this approach is time-consuming and prone to errors

Engineering Contradiction:
Improvedetection accuracy of machine stateVSAvoidsetup time and monitoring time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The machine tool system performs self-diagnosis by automatically analyzing structure-borne sound signals to determine its own operational state. The control device compares measured vibration spectra with stored reference spectra and autonomously identifies states such as idle running, machining, tool wear, or faults without requiring external expert intervention.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual expert assessment with automated signal processing and spectral analysis. The control device uses computational methods to evaluate vibration spectra, compare them against reference data, and determine machine states, substituting the need for trained personnel with an automated diagnostic system.

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

2Reliability

If trained personnel are used to monitor machine operating states, then accurate detection can be achieved, but the cost and complexity increase due to requirement for specialized knowledge

Engineering Contradiction:
Improveaccuracy of machine state determinationVSAvoidcomplexity of setup and operation
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system autonomously performs state determination by comparing measured vibration spectra with stored reference spectra. The control device automatically identifies machine states including idle running, machining operations, tool wear conditions, and faults without requiring trained personnel to interpret the data.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously monitors structure-borne sound signals, compares them against reference data, and provides real-time feedback about machine states. This closed-loop approach ensures reliable detection of operational conditions, tool wear, and faults while eliminating the need for manual expertise.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If broadband spectrum analysis is used instead of selective frequency band monitoring, then comprehensive machine state information can be obtained, but the data processing complexity increases

Engineering Contradiction:
Improveability to detect various operating conditionsVSAvoidcomplexity of signal processing
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Reference spectra are stored in advance for different machine states (idle running, machining, tool wear, faults). During operation, the control device simply compares the current measured spectrum against these pre-stored references, eliminating the need for complex real-time analysis while maintaining comprehensive monitoring capability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates spectral copies of reference states and stores them for comparison. Instead of performing complex real-time analysis of broadband signals, the control device matches the current spectrum against stored spectral templates, simplifying the processing while maintaining versatility in detecting various operating conditions.

Inventive Principle:
Principle #26Copying

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

This approach reduces the need for trained personnel, allows for faster and more precise detection of machine states, and enables the machine to independently determine its operating conditions, improving setup efficiency and reducing the risk of human error.

Implementation Method 1

the sensor device arranged on the spindle housing, which has at least one structure-borne sound sensor which is designed to detect structure-borne sound waves or vibrations occurring during grinding operations

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3562619B1Machine tool, in particular grinding machine, and method for determining an actual state of a machine tool
Publication Date: 2024.07.17 FRITZ STUDER AG
  • EP3562619B1 patent drawingFigure 1
  • EP3562619B1 patent drawingFigure 2a~2b
  • EP3562619B1 patent drawingFigure 3a~5

AI summary

The subject of the disclosure is a machine tool (10), in particular a grinding machine, comprising a measuring device (38) which is received on the machine tool (10), said measuring device (38) having at least one structure-borne sound sensor (36), and further comprising a control device (40) which is couplable to the measuring device (38) and a tool unit (22), the control device (40) being configured to sense structure-borne sound signals caused by the machine tool (10) by means of the measuring device (38) and to determine a state variable, describing an actual state of the machine tool (10), by forming a difference spectrum (56) from a broadband reference spectrum (50) and a broadband actual spectrum (54). The disclosure also relates to a method for determining an actual state of a machine tool (10).