Spindle Speed Control for Regenerative Chatter Reduction

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Solution Overview

Problem

Existing methods for reducing regenerative chatter in mechanical processing are inefficient and rigid, requiring lengthy analysis and being applicable only to specific processing conditions, with predetermined reduction strategies that do not adapt to the machine's actual status.

Innovation Solution

A method and system that monitor vibrations during processing, detect regenerative phenomena by analyzing frequency content, and adjust operating speed using dynamic reduction strategies based on resonance frequency thresholds, allowing for real-time adaptation and efficient vibration reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dedicated systems are used to detect and treat regenerative chatter by varying operating speed, then vibration reduction is achieved, but the system requires lengthy experimental analysis to reconstruct lobe diagrams and is rigidly applicable only to specific processing conditions

Engineering Contradiction:

Improvevibration reduction effectivenessVSAvoidanalysis time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary identification of machine dynamic characteristics and resonance frequencies before actual processing begins. By pre-characterizing the machine-tool-workpiece system, the lobe diagram can be predicted without lengthy experimental reconstruction during operation, enabling immediate application of vibration reduction strategies.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors vibrations during processing and uses real-time feedback to adjust operating parameters. The vibration signal is analyzed to detect regenerative chatter, and the control system automatically modifies spindle speed or depth of cut to move the operation into stable regions, creating a closed-loop control that adapts to actual processing conditions.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If predetermined reduction strategies are applied without considering actual machine status, then vibration reduction is implemented, but the effectiveness cannot be optimized

Engineering Contradiction:

Improvereduction procedure implementationVSAvoidreduction effectiveness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system transitions from static predetermined strategies to dynamic adaptive control. The reduction strategy is continuously adjusted based on real-time monitoring of machine status, including vibration amplitude, frequency content, and operating parameters. This allows the system to optimize effectiveness by selecting the most appropriate control action for each instantaneous processing condition.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system dynamically changes operating parameters (spindle speed, depth of cut, feed rate) based on detected vibration characteristics. By modifying these parameters in real-time according to the actual machine status and detected regenerative chatter, the system optimizes the effectiveness of vibration reduction while maintaining ease of operation through automated parameter adjustment.

Inventive Principle:

Principle #35Parameter changes

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 system effectively reduces vibrations by autonomously selecting the best reduction strategy, adapting to individual processing conditions, and learning from previous operations, resulting in a robust and efficient solution that surpasses the limitations of prior art.

Implementation Method 1

monitoring the vibration which arises from the contact between the tool and a workpiece being processed

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 2

the assessment of the intensity of the vibration is performed in frequency terms, that is to say, by analysing the frequency spectrum of the vibration signal

Methodology Applied

Scientific EffectFrequency analysis:

Implementation Method 3

reducing the intensity of the vibratory phenomenon by the performance of a first reduction strategy SST and a second reduction strategy SSV

Methodology Applied

Scientific EffectVibration reduction through speed modulation:

Data Source

PatentEP3724732B1Method and a system for reducing vibrations in a mechanical processing for removal of chippings

Publication Date: 2022.06.01 MANDELLI SRL

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AI summary

Described is method for reducing vibrations originating in a mechanical processing for removal of swarf comprising monitoring the vibration which results from the contact between the tool (103) and a workpiece (WP) 5 being processed, detecting the occurrence of a regenerative vibratory phenomenon, calculating the frequency of the vibratory phenomenon (fC), estimating a value representing a resonance frequency (fR) of the machine as a function of the frequency of the vibratory phenomenon (fC) and determining at least one threshold value (ωTR) on the basis of the value 10 representing a resonance frequency (fR). The method also comprises comparing the operating speed (ωL) of the mandrel (102) with the threshold value (ωTR) and reducing the intensity of the vibratory phenomenon by the performance of a first reduction strategy (SST) based on a correction of the operating speed (ωL) when the operating speed (ωL) 15 of the mandrel (102) is greater than the threshold value (ωTR) or by means of a second reduction strategy (SSV) based on a continuous modulation which imparts an oscillation to the speed around the value of the operating speed (ωL), when the operating speed (ωL) of the mandrel (102) is less than the threshold value (ωTR).