Hollow Stem Flail Element Reduces Impact Force

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Solution Overview

Problem

Existing flail elements for vegetation cutting machines are prone to damage when impacting hard objects due to the force transferred during centrifugal motion, which can lead to rotor shaft and flail damage.

Innovation Solution

A flail element design featuring a stem with a cavity, potentially frustoconical in shape, and raised portions to reduce impact force, combined with a cutting head and mounting formation, all formed as a single piece or linked components, to minimize damage and improve cutting efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the flail element is made solid without cavities, then the stem provides structural strength, but the weight increases and impact force on the rotor shaft increases

Engineering Contradiction:
Improvestructural strengthVSAvoidweight of flail element
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The stem of the flail element incorporates cavities (voids) within its structure, transforming it from a solid homogeneous form to a porous or hollow configuration. This reduces the overall weight and mass of the flail element while maintaining adequate structural strength for cutting vegetation. The cavities are strategically positioned to balance weight reduction with structural integrity requirements.

Inventive Principle:
Principle #31Porous materials

2Strength

If the flail element is made solid without cavities, then the stem provides structural strength, but the impact force on the rotor shaft increases

Engineering Contradiction:
Improvestructural strengthVSAvoidimpact force
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The cavities within the stem reduce the mass and momentum of the flail element, thereby decreasing the impact force generated during centrifugal motion and upon impact with hard objects. This porous configuration allows the flail to maintain structural strength for cutting while minimizing the harmful impact forces that could damage the rotor shaft or surrounding components.

Inventive Principle:
Principle #31Porous materials

3Ease of manufacture

If the cutting head has a flat base, then manufacturing is simple, but vegetation builds up on the leading edge

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcutting efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The base of the cutting head is designed with a curved or rounded leading edge instead of a flat surface. This curvature prevents vegetation from building up on the leading edge by allowing cut material to be thrown clear more effectively. The curved geometry maintains manufacturing feasibility while significantly improving cutting efficiency and preventing vegetation accumulation that would otherwise require frequent cleaning.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 design reduces the risk of damage to the rotor shaft and flail element by minimizing the impact force, while also preventing vegetation buildup on the cutting head, ensuring a better finish and reduced power consumption.

Implementation Method 1

as the rotor shaft is rotated, the flails swing out under the centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2926641B1Flail cutting element
Publication Date: 2017.05.31 MCCONNEL LTD
  • EP2926641B1 patent drawingFigure 1
  • EP2926641B1 patent drawingFigure 2
  • EP2926641B1 patent drawingFigure 3

AI summary

A flail element (10) for use on a vegetation cutting mower that has a mounting formation (15) at one end that enables the flail element (10) to be mounted on a shaft mounting of a cutting machine, a cutting head (25) at the opposite end for cutting vegetation and a hollow stem (40) that extends between the cutting head (25) and the mounting formation (15).