Three-Bevel Cutting Blade for Pruner Effort Reduction

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Solution Overview

Problem

Conventional cutting jaw cutting tools require excessive effort to cut larger materials, such as branches, due to high strain on the blade, particularly in secateurs and pruners, leading to potential jamming issues.

Innovation Solution

A cutting jaw blade with three bevels of different slopes and widths, articulated with a complementary member, reduces cutting effort by distributing force more efficiently, featuring a sharp portion with a cutting edge and a counteredge, where the bevels are arranged successively from the cutting edge, with specific angle and width combinations to minimize strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional blade with one or two bevels is used, then the blade structure is simple, but the cutting effort is excessive and jamming occurs

Engineering Contradiction:
Improvecutting effortVSAvoidblade structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The blade face is segmented into three distinct bevel zones (first bevel with angle α, second bevel with angle β, third bevel with angle γ) where each zone performs a specific function in the cutting process. This segmentation allows the cutting effort to be distributed across multiple stages, reducing the peak force required at any single point and preventing jamming while maintaining a relatively simple overall blade structure.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the blade bevels have small angles to reduce cutting effort, then the cutting becomes easier, but the blade width must be increased which affects the tool size

Engineering Contradiction:
Improvecutting effortVSAvoidblade width
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

Different regions of the blade face are assigned different bevel angles optimized for their specific function: the first bevel (α = 25°-35°) for initial penetration, the second bevel (β = 10°-20°) for sustained cutting with reduced effort, and the third bevel (γ = 5°-15°) for finishing. This local optimization allows each zone to perform its function efficiently without requiring excessive blade width, as the progressive angle reduction accomplishes what a uniformly wide blade would need to do all at once.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3047721B1Blade of a cutting tool with three bevels and cutting tool including said blade
Publication Date: 2021.12.29 PRUNING SHEARS PRADINES
  • EP3047721B1 patent drawingFigure 1~3

AI summary

The present invention relates to a cutting tool blade (2) such as a pruner or a secateur, said blade comprising: - an articulation means (22) intended to articulate with a complementary member, - a cutting part comprising two faces (18) separated from each other by a slice, this slice comprising a cutting edge (14) and a false edge (17) opposite this cutting edge, at least one of these faces comprising three bevels (11, 12, 13) of different slopes, said bevels being arranged successively from the cutting edge towards said false edge.