Machine Tool Chatter Detection With Interrupted Machining Resume

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Solution Overview

Problem

Machine tools face challenges in maintaining processing quality and preventing tool wear and damage due to chatter vibrations during machining, as existing methods continue machining while analyzing vibrations, potentially causing defects in the workpiece and tool damage.

Innovation Solution

A machine tool equipped with a detection unit for chatter vibration, which interrupts machining upon detection, analyzes the vibration frequency using FFT, and adjusts processing conditions to prevent recurrence, allowing for resumed machining from the interrupted position with reduced processing time loss and uniform quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If machining continues while analyzing chatter vibration frequency, then productivity is maintained, but manufacturing precision deteriorates due to generation of processing defects and tool wear

Engineering Contradiction:
Improvemachining continuityVSAvoidprocessing quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection of chatter vibration during machining and interrupts the machining process before significant defects or tool damage occur. The detection unit continuously monitors vibration, and when chatter is detected, the control unit stops machining to prevent further degradation of processing quality while minimizing interruption time.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If machining is interrupted when chatter vibration is detected, then manufacturing precision is improved by preventing defects and tool wear, but productivity decreases due to loss of machining time

Engineering Contradiction:
Improveprocessing qualityVSAvoidmachining time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system dynamically adjusts the machining process by intermittently interrupting machining only when chatter vibration is detected, rather than continuously stopping or never stopping. This dynamic approach allows machining to proceed normally during stable conditions while pausing only when necessary, thereby maintaining high productivity while ensuring processing quality.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If machining is interrupted and resumed from the starting point for light cutting, then manufacturing precision is improved by eliminating chatter marks, but productivity decreases due to reprocessing time

Engineering Contradiction:
Improvesurface quality uniformityVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The machining process is segmented into heavy cutting and light cutting phases. When chatter occurs during heavy cutting, the system interrupts and resumes with light cutting to eliminate chatter marks. This segmentation allows the system to optimize for quality during problematic phases while maintaining efficiency during stable heavy cutting phases.

Inventive Principle:
Principle #1Segmentation

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 effectively reduces defects in the workpiece and tool wear by interrupting machining during chatter vibration analysis, enabling resumed machining with improved quality and minimizing processing time loss, especially in heavy cutting, and allows for the elimination of chatter marks through light cutting.

Implementation Method 1

a detection unit for detecting chatter vibration

Methodology Applied
Scientific EffectVibration detection: Vibration

Implementation Method 2

analyzes the vibration frequency using FFT

Methodology Applied
Scientific EffectFFT analysis:

Data Source

PatentEP3611585B1Machine tool
Publication Date: 2023.11.22 NAKAMURATOME SEIMITSU IND
  • EP3611585B1 patent drawingFigure 1
  • EP3611585B1 patent drawingFigure 2
  • EP3611585B1 patent drawingFigure 3

AI summary

A machine tool includes: a main spindle that holds a work piece; a tool holding unit that holds a tool for processing the work piece; a detection unit that detects vibration generated during processing of the work piece; and a processor that controls machining of the work piece performed by the tool, in which the processor compares a detected value detected by the detection unit with a predefined threshold value, interrupts the machining by releasing contact between the work piece and the tool at time of generation of chatter vibration or when there is a sign of the generation of the chatter vibration in which the detected value exceeds the threshold value, and analyzes the chatter vibration while the machining is being interrupted on basis of the detected value detected by the detection unit before the interruption.