Spindle Vibration Sensing for Accurate Tool Status Detection

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Solution Overview

Problem

Existing tool monitoring systems in machine tools are vulnerable to disturbances and vibrations, leading to inaccurate tool status detection and high system costs due to reliance on wireless communication and signal reliability issues.

Innovation Solution

The implementation of a tool monitoring apparatus with two MEMS-type vibration accelerometers attached to a non-rotational part of the spindle, measuring signals in a wired manner, and analyzing these signals to detect tool status by converting acceleration signals into cutting force representations on a polar coordinate system, allowing for accurate visualization and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If wireless communication method is used for signal transmission in tool monitoring system, then system cost is reduced and installation is simplified, but signal reliability deteriorates

Engineering Contradiction:

Improveinstallation simplicityVSAvoidsignal reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces wireless communication with wired connection (mechanical/electrical connection) between the tool holder and control device. This substitution ensures stable signal transmission and high reliability while maintaining ease of installation through the integrated wired sensor system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If vibration monitoring is implemented during machine tool processing, then tool status detection is enabled, but vulnerability to disturbance and vibration increases

Engineering Contradiction:

Improvetool status detection accuracyVSAvoidvibration disturbance

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary processing device that receives vibration signals from the tool holder, performs signal processing and analysis, and distinguishes between normal cutting vibrations and abnormal vibrations indicating tool damage. This intermediary system filters out disturbances and extracts meaningful tool status information.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system continuously monitors vibration signals and provides real-time feedback about tool status. When abnormal vibrations are detected, the system can trigger alerts or automatic shutdown, creating a closed-loop feedback mechanism that prevents defective product generation.

Inventive Principle:

Principle #23Feedback

3Reliability

If tool monitoring system is added to detect tool damage, then product defect prevention is achieved, but system complexity increases

Engineering Contradiction:

Improveproduct quality assuranceVSAvoidmonitoring system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the tool monitoring function into the existing machine tool control device, allowing the control device to perform both its original control functions and the new tool status monitoring function. This multi-functionality approach avoids adding separate complex monitoring systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the vibration sensor, signal processing unit, and tool status determination logic into an integrated system where the control device serves multiple purposes. The sensor unit is attached to the tool holder which is already part of the machining system, merging monitoring with existing components.

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

This approach provides reliable and accurate tool status detection, preventing processing defects by visualizing tool conditions and enabling alarm or control actions, thereby reducing material processing errors and system costs.

Implementation Method 1

two MEMS (Micro Electro-Mechanical Systems)-type vibration accelerometers attached to a non-rotational part of a spindle

Methodology Applied

Scientific EffectMEMS (Micro Electro-Mechanical Systems): Microelectromechanical Systems

Implementation Method 2

a first acceleration sensor configured to sense the acceleration of the spindle in the x-axis direction; a first amplifier configured to amplify the signal sensed by the first acceleration sensor

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12157195B2Apparatus for detecting status of tool in machine tool

Publication Date: 2024.12.03 WIA MACHINE TOOLS CORPORATION

AI summary

An apparatus for detecting the status of a tool in a machine tool may include: a sensor unit configured to sense acceleration of a spindle of the machine tool in an x-axis direction and a y-axis direction during processing; and a processing device configured to convert the x-axis signal and the y-axis signal, sensed by the sensor unit, into signals capable of representing a cutting force by processing the x-axis and y-axis signals, detect a resultant force, and plot the detected resultant force on a polar coordinate system.