Nail Centering Mechanism with Elastic Ring and Ball Array

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Solution Overview

Problem

Existing driving tools for fasteners often experience misalignment due to insufficient guidance and uneven spring compression in nail centering mechanisms, which leads to centering errors and limited compatibility with fasteners of different diameters.

Innovation Solution

A nail centering device with a centering housing containing a ring of balls, where the centering opening is defined by the balls and an elastic ring prestressed against them, ensuring precise centering of fasteners by radially pressing the balls apart and together, accommodating various diameters and maintaining even force distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If two pivoting flaps mounted on the lower end of the muzzle tool are used for centering, then centering of nails can be achieved, but the springs fatigue differently causing uneven compression and centering errors

Engineering Contradiction:
Improvecentering precisionVSAvoidspring fatigue uniformity
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The centering mechanism is segmented into multiple independent balls (at least three balls arranged in a circle) instead of using two pivoting flaps. Each ball can move independently in radial directions, allowing uniform force distribution and eliminating the spring fatigue unevenness problem that occurs with flap-based systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An elastic ring is introduced as an intermediary element that applies uniform radial prestress to all balls simultaneously. This elastic ring acts as a mediator that distributes the centering force evenly across all balls, preventing the uneven compression and fatigue issues experienced with individual springs on pivoting flaps.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a centering opening with oval cross-sectional shape is used, then nails with different diameters can be centered, but the same nail centering can only be used for nails with slightly different diameters

Engineering Contradiction:
Improvecompatibility with different nail diametersVSAvoidcentering accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The centering mechanism uses movable balls that can dynamically adjust their positions in radial directions rather than a fixed oval opening. This dynamic adjustment allows the mechanism to adapt to various nail diameters while maintaining precise centering, as the balls conform to the nail's actual dimensions rather than forcing the nail into a predetermined shape.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The effective centering geometry changes based on the nail diameter being processed. The balls can move to different radial positions to accommodate different nail sizes, transforming the centering parameters dynamically. This allows the same mechanism to precisely center nails with widely differing diameters without being limited to a single diameter range.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the muzzle tool is placed on a workpiece, then even driving depth can be ensured, but the flaps cannot deflect causing centering problems

Engineering Contradiction:
Improvedriving depth uniformityVSAvoidcentering mechanism deflection
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The centering mechanism is divided into multiple independent balls that can move individually in radial directions even when the muzzle tool is placed on the workpiece. This segmentation allows each ball to deflect independently to accommodate the nail head passing through, unlike rigid flap structures that cannot deflect when constrained by the workpiece surface.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The elastic ring functions as a flexible element that allows the balls to move and deflect radially. This flexibility enables the centering mechanism to adapt when the muzzle tool is placed on the workpiece, maintaining both driving depth uniformity and centering capability simultaneously.

Inventive Principle:
Principle #30Flexible shells and thin films

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

This solution provides precise centering of fasteners with widely differing diameters, reduces centering errors, and allows for even driving depth and alignment perpendicular to the workpiece surface, while the elastic ring's gradual fatigue is compensated by uniform ball pressure.

Implementation Method 1

an elastic ring which bears against the outside of the balls under pretension

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

which is pretensioned by at least one spring device in the radial direction towards the centering opening

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP3403769B1Driving tool for driving fastening means into workpieces
Publication Date: 2020.02.19 JOH FRIEDRICH BEHRENS AG
  • EP3403769B1 patent drawingFigure 1
  • EP3403769B1 patent drawingFigure 2
  • EP3403769B1 patent drawingFigure 3

AI summary

Driving device for driving fasteners into workpieces comprising: - a drive unit in a housing, - a terminal tool projecting from the lower end of the housing with a driving channel, - a driving plunger projecting into the driving channel and connected to the drive unit at the top, - a magazine for fasteners connected to the driving channel to supply fasteners to the driving channel, and - a nail centering device at the bottom of the terminal tool, which has a centering opening bounded by radially movable guide elements biased towards the centering opening by at least one spring device, characterized in that: - the nail centering device comprises a centering housing in which at least one ring of balls is arranged, between which the centering opening is defined, and - the spring device is an elastic ring that bears against the outside of the balls under bias.