Tunable Boring Bar Vibration Absorber for Multi-Mode Chatter

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Solution Overview

Problem

Conventional tunable boring bars and anti-vibration bars do not effectively address vibrations at multiple natural frequencies, particularly the second mode, leading to chatter and poor surface finish in metalworking operations, especially with narrow, long-length boring bars.

Innovation Solution

A tunable boring tool with a dynamic vibration absorber featuring a mass supported by proximal and distal resilient supports of different stiffnesses, allowing for adjustment to minimize vibrations at both the first and second natural frequencies by varying the compression of the supports against the mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional single-frequency vibration absorber is used, then vibration at one natural frequency is reduced, but vibration at other natural frequencies (particularly the second mode) becomes dominant and causes chatter

Engineering Contradiction:

Improvevibration suppression effectivenessVSAvoidchatter and surface finish quality

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the single vibration absorber into multiple independent absorbers, each tuned to a specific natural frequency of the boring bar. Each absorber segment targets a specific mode of vibration (first mode, second mode, etc.), allowing simultaneous suppression of multiple vibration frequencies that would otherwise cause chatter and poor surface finish

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the tuning parameters of the vibration absorbers to match multiple natural frequencies of the boring bar system. By adjusting the mass and stiffness parameters of each absorber, the system can be tuned to counteract vibrations at different frequencies, transforming a single-frequency solution into a multi-frequency solution

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If cutting parameters are reduced to minimize vibration, then surface finish quality improves, but metal removal rate decreases leading to low productivity

Engineering Contradiction:

Improvesurface finish qualityVSAvoidmetal removal rate

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent converts the harmful vibration energy into useful counter-vibration by using the vibration absorbers to generate opposing vibrations at the same frequency. This allows the system to maintain high cutting parameters and metal removal rates while the absorbers neutralize the harmful vibrational effects, improving surface finish without sacrificing productivity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If a stiffer material like carbide is used for the boring bar, then vibration is reduced, but the bar becomes more expensive and more brittle

Engineering Contradiction:

Improveboring bar stiffnessVSAvoidcost and manufacturability

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent introduces vibration absorbers as intermediary elements between the boring bar and the vibration source. These absorbers act as mediators that capture and neutralize vibration energy, allowing the use of more economical steel boring bars instead of expensive carbide bars while maintaining vibration control and avoiding the brittleness issues of carbide

Inventive Principle:

Principle #24Intermediary (Mediator)

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 cancels or minimizes vibrations at multiple modes, reducing chatter and improving surface finish quality, enabling increased metal removal rates and productivity.

Implementation Method 1

The proximal support and the distal support have different stiffnesses

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

the mass oscillates in response to vibration produced in the boring bar to cancel out vibration

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9533357B2Optimized vibration absorber

Publication Date: 2017.01.03 KENNAMETAL INC

AI summary

A tuned or tunable boring tool includes a boring bar defining an elongated cavity therein. A distal end of the boring bar is configured to support a tool or cutting insert. The boring tool further includes a dynamic vibration absorber inserted within the elongated cavity of the boring bar. The dynamic vibration absorber includes a mass that vibrates in conjunction with vibration of the boring bar. The mass has a proximal end and a distal end. The dynamic vibration absorber further includes at least one resilient proximal support positioned adjacent to and supporting the proximal end of the mass and at least one distal resilient support positioned adjacent to and supporting the distal end of the mass. The at least one proximal support and at least one distal support have a different stiffness.