Low Friction Folding Knife Roller Cam Mechanism

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Solution Overview

Problem

Folding knives with assisted opening mechanisms often suffer from friction, galling, and wear issues, leading to costly repairs or loss of functionality, and existing designs are complex and costly to manufacture.

Innovation Solution

A low-friction folding knife with an adjustable bias element and roller cam system that minimizes contact with the blade, allowing for automatic or assisted opening modes while incorporating a safety mechanism to prevent accidental opening, and simplifies production with spring placement slots in liners.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spring mechanism travels within a slot in the tang of the blade, then assisted opening is achieved, but friction, galling and wear occur over time

Engineering Contradiction:

Improveassisted openingVSAvoidfriction and wear

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

A roller element is introduced as an intermediary between the spring mechanism and the blade tang. The roller travels within the arcuate slot instead of the spring directly contacting the tang, significantly reducing friction and wear. The roller acts as a mediator that transfers the assisting force while minimizing direct contact and wear between the spring and blade components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct mechanical contact between the spring and the blade tang with a rolling contact system. By substituting sliding friction with rolling friction through the roller element, the system achieves assisted opening with dramatically reduced wear and galling on the blade components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a complicated spring mechanism with precision bending and arcuate slots is used, then assisted opening is achieved, but manufacturing cost increases

Engineering Contradiction:

Improveassisted openingVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The mechanism is divided into separate, simpler components: a standard spring, a roller element, and a simple arcuate slot in the tang. This segmentation allows each component to be manufactured using simpler, less expensive processes rather than requiring precision-bent springs with integrated complex geometries.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of creating a complex precision-bent spring with an integrated arcuate slot (as in Onion's patent), the invention inverts the approach by using a simple spring combined with a separate roller element that travels in a slot. This reverses the complexity from the spring component to a simpler rolling contact system.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the spring requires replacement due to wear, then reliability is maintained, but repair cost increases

Engineering Contradiction:

Improvefunctional reliabilityVSAvoidrepair cost

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The roller element is designed as a simple, inexpensive component that can be easily replaced when worn. Rather than replacing an expensive precision-bent spring mechanism, users can replace the simple roller at minimal cost, effectively making it a low-cost consumable component that maintains reliability economically.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 provides a cost-effective, low-friction folding knife with reduced wear and tear, ensuring reliable automatic or assisted opening and enhanced safety features, while simplifying manufacturing and assembly processes.

Implementation Method 1

roller cam extending slightly outside of the perimeter of the tang and rotatably attached within the slot

Methodology Applied

Scientific EffectRolling friction: Friction

Implementation Method 2

The spring distal end is in spring communication with the roller cam on the tang. With the adjustable bias element adjusted to full extension it works as an automatic opening element by maintaining contact with and applying force to the roller cam

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 3

The safety assembly in the safe position lodges a steel ball through a hole in the first liner and into a ball lock hole disposed through the tang of the blade thereby preventing opening of the blade

Methodology Applied

Scientific EffectMechanical locking: Mechanical Force

Data Source

PatentUS7854067B2Low friction folding knife

Publication Date: 2010.12.21 RODALA

AI summary

A folding knife has a slot disposed in the thickness of the tang with a roller cam extending outside of the perimeter of the tang and rotatably attached within the slot. A safety assembly disposed within the handle has a stud extending through a slot in the handle and moves the assembly between a safe and an unsafe position. In the safe position the safety assembly is forced against the tang thereby preventing opening. An adjustable bias element assists the blade in exiting the blade slot. The bias element is in spring communication with the roller cam. Applying pressure to the stud urges the blade from the closed position as the bias element is centered with the roller cam and the blade is forced to an open position by the spring force of the bias element on the roller cam.