Utility Knife Blade Locking for Two-Sided Blade Use

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Solution Overview

Problem

Conventional utility knives with trapezoidal blades face inefficiencies in blade replacement and locking mechanisms, as both sides of the blade are not effectively utilized before disposal, leading to premature blade wear and increased waste.

Innovation Solution

A locking mechanism for utility knife blades that allows selective engagement and release of blades through notch engaging protrusions and actuators, enabling efficient use of both sides of the blade before replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If a conventional blade holder assembly is used with trapezoidal blades, then the blade can be held securely in the housing, but only one side of the blade can be used before disposal

Engineering Contradiction:
Improveblade wasteVSAvoidblade replacement operation
Core Design Contradiction:
Loss of substanceVSEase of operation

Solution Approach 1:

The blade holder assembly incorporates a rotatable blade holder body that can rotate the blade between different angular positions. This dynamic rotation mechanism allows the blade to be oriented in different positions, enabling both sides of the trapezoidal blade to be used sequentially before disposal, thereby reducing blade waste.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the angular parameter of the blade within the holder assembly. By rotating the blade holder body to different angular positions, the blade can be reoriented to present different sides for use. This parameter change enables maximum utilization of the blade material before it needs to be replaced.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a locking mechanism with multiple lock members is used, then the blade can be securely locked in position, but the device complexity increases

Engineering Contradiction:
Improveblade locking reliabilityVSAvoidlocking mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is divided into multiple independent lock members (first lock member and second lock member), each capable of independently engaging with the blade holder assembly. This segmentation allows for enhanced reliability through redundant locking points while maintaining modular complexity that can be managed through standardized components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lock members are designed with universal engagement features that can secure the blade holder assembly in multiple positions. The same lock member structure can function for both blade retention and position locking, reducing the need for specialized components and managing overall system complexity.

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

Data Source

PatentEP3959051B1Multi lock member knife blade release
Publication Date: 2025.11.26 STANLEY BLACK & DECKER INC
  • EP3959051B1 patent drawingFigure 1
  • EP3959051B1 patent drawingFigure 2
  • EP3959051B1 patent drawingFigure 3

AI summary

A utility knife includes a housing and a slidable blade assembly configured to selectively receive a removable blade in a blade channel thereof and to slide relative to the housing, such that the removable blade is stored within the housing when the slidable blade assembly is in a retracted position, and a portion of the blade extends outwardly from the housing when the slidable blade assembly is in an extended position. The slidable blade assembly comprises a plurality of notch engaging protrusions configured to move to selectively enter the blade channel to engage one or more notches of the removable blade. The housing comprises a blade release actuator configured to move or permit movement of the plurality of notch engaging protrusions out of the blade channel to permit removal of the removable blade from the slidable blade assembly.