Hand-Operated Striking Tool Vibration Reduction Design

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Solution Overview

Problem

Conventional striking tools, such as hammers, generate substantial vibrations that lead to musculo-skeletal issues like carpal tunnel pain and loss of sensation in the fingertips, and existing solutions like single-part hammers and tuning-fork systems do not adequately address these problems.

Innovation Solution

A striking tool design featuring an intermediate shaft and handle made from rigid materials with a flexible link part and a free terminal area within a tube, which breaks the vibration bridge and isolates vibrations by allowing the shaft to vibrate in an air zone, increasing the frequency of vibrations above human perception thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single-part hammer or tuning-fork system is used to reduce vibrations, then vibration absorption is improved, but the solution does not provide satisfactory reduction of vibrations

Engineering Contradiction:

ImprovevibrationsVSAvoideffectiveness of vibration reduction

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The hammer is divided into separate components: a handle, a shaft, and a head, connected through intermediate bearing areas. This segmentation allows each component to be optimized independently, with the shaft and handle made from rigid materials and the bearing areas made from flexible materials to absorb vibrations effectively.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The hammer combines rigid materials (for the shaft and handle) with flexible materials (for the bearing areas) to create a composite structure. The rigid materials provide structural strength while the flexible materials absorb vibrations, achieving both durability and vibration reduction.

Inventive Principle:

Principle #40Composite materials

2Strength

If the shaft is made rigid to maintain structural strength, then strength is improved, but vibrations are transmitted to the user

Engineering Contradiction:

Improvestructural strengthVSAvoidvibrations transmitted to user

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

Different parts of the hammer have different material properties: the shaft and handle are made from rigid materials for structural strength, while the bearing areas are made from flexible materials to absorb vibrations. This local differentiation of material properties allows the structure to simultaneously achieve strength and vibration reduction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Flexible bearing areas act as intermediaries between the rigid shaft and handle. These intermediary elements absorb and dampen vibrations before they are transmitted to the user's hand, while still allowing force transmission for effective hammering.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If flexible materials are used to absorb vibrations, then vibration absorption is improved, but structural strength is reduced

Engineering Contradiction:

Improvevibration absorptionVSAvoidstructural strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The flexible materials are applied only at specific bearing areas where vibration absorption is needed, rather than throughout the entire structure. This localized application allows vibration absorption at critical points while maintaining structural strength in the shaft and handle.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

By segmenting the hammer into distinct rigid and flexible components, the design allows the flexible bearing areas to absorb vibrations without compromising the overall structural integrity provided by the rigid shaft and handle.

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

Significantly reduces vibrations perceived by the user, improving the overall handling experience while maintaining efficiency and cost-effectiveness.

Implementation Method 1

a link part, for absorbing the vibrations, made from a flexible material presenting a second hardness considerably lower than the first hardness

Methodology Applied

Scientific EffectVibration absorption: Damping

Implementation Method 2

a free terminal area not covered by the link part, radially separated from the walls of the tube so as to be able to vibrate freely in an internal volume of the tube

Methodology Applied

Scientific EffectFree vibration: Vibration

Implementation Method 3

the rigidity of the shaft tends to increase the frequency of the vibrations, in part above the threshold perceived by human beings

Methodology Applied

Scientific EffectVibration frequency: Vibration

Data Source

PatentUS8893585B2Hand-operated striking tool enabling vibrations to be reduced, and method for manufacturing

Publication Date: 2014.11.25 FISKARS FRANCE

AI summary

This tool, which is in particular a hammer, comprises a gripping handle, a striking head, and an intermediate shaft extending the handle and supporting the head, whereas the handle comprises a tube in which the shaft partially extends, this tube and this shaft being made from a rigid material presenting a first hardness.This shaft has a radial area bearing against the tube, with interposition of a link part, for absorbing vibrations, made from flexible material presenting a second hardness that is much lower than the first hardness, and a free terminal area, not covered by the link part, radially separated from the walls of the tube so as to be able to vibrate freely in an internal volume of the tube.