Dual Blade Locking Mechanism for Folding Tool Stability

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Solution Overview

Problem

Folding knives with multiple blades face challenges in securely locking one blade in the open position while maintaining the other blade in a closed position, ensuring safety and functionality, as existing mechanisms often result in free swinging or interference during operation.

Innovation Solution

A dual-bladed folding knife design incorporating an axis lock mechanism for securing blades in the open position and a closed blade retention system using a detent hole, detent ball, and detent retainer spring to maintain the closed position, along with a secondary stop pin to prevent binding of the lock bar mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking mechanism is used to secure one blade in the open position, then the open blade is locked securely, but the closed blade may become unstable or interfere with the locking mechanism

Engineering Contradiction:
Improvelocking reliabilityVSAvoidblade operation stability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The knife is divided into two independent blade systems, each with its own retention mechanism. The first blade has a lock bar and detent mechanism, while the second blade has a separate detent ball and detent hole mechanism. This segmentation allows each blade to be controlled independently, preventing interference between blades during operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A second stop pin is introduced as an intermediary element to prevent the lock bar from binding against the second blade during closing. This mediator component resolves the conflict between securing the first blade open and allowing the second blade to close smoothly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If a retention mechanism is added to keep the closed blade stationary, then the closed blade stability is improved, but the device complexity increases

Engineering Contradiction:
Improveclosed blade stabilityVSAvoidmechanism complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The retention mechanisms for both blades are merged into a unified system using the same basic components (detent balls, detent holes, and springs) located within the handle body. This approach provides stable retention for both blades while avoiding the need for separate, complex mechanisms for each blade.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The handle body serves multiple functions: it houses the locking mechanism for the first blade, the retention mechanism for the second blade, and provides structural support for both blades. This multi-functionality reduces overall device complexity by consolidating multiple mechanisms into a single integrated structure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If the lock bar is allowed to move freely to lock the open blade, then the locking action is effective, but the lock bar may bind against the closed blade

Engineering Contradiction:
Improvelocking effectivenessVSAvoidmechanism interference
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The second stop pin is positioned to preemptively prevent the lock bar from contacting the second blade during its closing motion. By providing this preliminary constraint, the design prevents potential binding or interference before it can occur, ensuring smooth operation of both blades.

Inventive Principle:
Principle #9Preliminary anti-action

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 locks one blade open and retains the other blade closed, preventing free swinging and ensuring smooth operation by applying the appropriate force to maintain the blades in their respective positions, enhancing safety and functionality.

Implementation Method 1

a detent retainer spring positioned within the handle to apply pressure to the detent ball

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

an axis lock mechanism for securing blades in the open position

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP3672766B1Dual blade locking mechanism
Publication Date: 2024.04.17 BENCHMADE KNIFE CO INC
  • EP3672766B1 patent drawingFigure 1
  • EP3672766B1 patent drawingFigure 2
  • EP3672766B1 patent drawingFigure 3

AI summary

A folding tool including a handle having a first handle half and a second handle half held in a spaced apart relationship to form an implement groove therebetween. Two or more implements are pivotally connected between the first handle half and a second handle half by a pivot shaft and movable between an open position and closed position and lockable in the open position. The folding tool includes a closed blade retention system, with a detent feature (or hole) on each tang, a detent retainer spring, and a detent ball. When the implement is in the closed position, the detent aligns with the ball thereby retaining the blade in the closed position.