Trim Blade Planar Cutting Tips Reduce Ground Collision

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Cutting blades for hand-held brush cutters often suffer from the risk of cutting edges colliding with the ground, leading to reduced performance, increased wear, and obstructions such as thrown-up earth and dust, which hinder visibility and require user compensation.

Innovation Solution

Arranging all cutting tips of the cutting blade in a common plane, preferably the central plane, to minimize the risk of collision with the ground and enhance cutting performance by ensuring the base body touches down when moved horizontally, and reducing wear by alternating the bending direction of cutting teeth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If cutting teeth are arranged with leading edges outside the central plane forming multiple cutting circles, then cutting performance is improved, but the risk of collision with ground and loose material increases

Engineering Contradiction:
Improvecutting performanceVSAvoidrisk of collision with ground
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent transitions from a three-dimensional arrangement of cutting teeth at different radial distances (multiple cutting circles) to a two-dimensional arrangement where all cutting tips lie in a common plane (the central plane of the cutting blade). This dimensional reduction eliminates the protrusion of cutting edges beyond the central plane, thereby preventing collisions with ground and loose material while maintaining effective cutting through the planar configuration.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If cutting edges are positioned to form multiple cutting planes, then cutting capability is enhanced, but wear increases due to ground contact

Engineering Contradiction:
Improvecutting capabilityVSAvoidservice life of cutting blade
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent reconfigures the cutting teeth from a multi-level three-dimensional arrangement to a single-plane two-dimensional arrangement. By positioning all cutting tips in the central plane of the cutting blade, the design eliminates excessive ground contact that would occur with protruding cutting edges, thereby reducing wear and extending the service life of the cutting blade while preserving cutting effectiveness.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Productivity

If cutting teeth are arranged in multiple cutting planes, then cutting efficiency is improved, but vision obstruction increases due to stirred-up debris

Engineering Contradiction:
Improvecutting efficiencyVSAvoidvision obstruction from debris
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent consolidates the cutting teeth into a single central plane, eliminating the multi-plane configuration that causes cutting edges to dig into the ground and stir up debris. This planar arrangement reduces soil disturbance and minimizes the generation of dust and loose material that would obstruct the operator's vision, while maintaining cutting efficiency through the optimized tooth geometry and spacing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2674237B1Grass cutting blade for a trimmer
Publication Date: 2016.08.10 ANDREAS STIHL AG & CO KG
  • EP2674237B1 patent drawingFigure 1
  • EP2674237B1 patent drawingFigure 2~6
  • EP2674237B1 patent drawingFigure 7

AI summary

The cutting blade (20) has a drive motor with a disk-like base body (21) having cutting teeth (30,40) arranged on its periphery. Each cutting tooth has a side plate cutter running forward in a drive direction (13) and extending radially and a roof cutter that is extending in a peripheral direction (23). The side plate cutter and roof cutter are grounded by a formation of a cutting edge alternating from the one and another sides (31,41) of the cutting blade. Multiple cutting tips (36) of the cutting teeth lie in a common plane, where the cutting teeth are successive on the peripheral direction.