Angle Grinder Support Arm Cover for High-Load Rigidity

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Solution Overview

Problem

Hand-held cut-off grinders with compact and delicate support arms face challenges in withstanding high forces during operation, leading to potential damage and reduced stability and rigidity.

Innovation Solution

The support arm is reinforced with a metal arm cover that diverts forces from the support arm, using fastening elements strategically positioned above the axis of rotation to reduce load on the support arm and maintain stability while minimizing the reduction in cutting depth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the support arm is made compact and delicate to achieve increased cutting depths, then the cutting depth is improved, but the stability and rigidity of the support arm deteriorates

Engineering Contradiction:
Improvecutting depthVSAvoidstability and rigidity of support arm
Core Design Contradiction:
Length of moving objectVSStability of the object's composition

Solution Approach 1:

The support arm is divided into functional segments: a compact second end for achieving cutting depth and a reinforced first end with metal arm cover for withstanding forces. This segmentation allows each part to be optimized for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The support arm combines different materials: a compact structure at the second end and a metal material (aluminum or magnesium alloy) for the arm cover at the first end. This composite approach allows the support arm to achieve both compactness for cutting depth and sufficient strength for withstanding forces.

Inventive Principle:
Principle #40Composite materials

2Length of moving object

If the support arm is made compact and delicate to achieve increased cutting depths, then the cutting depth is improved, but the load-bearing capacity of the support arm deteriorates

Engineering Contradiction:
Improvecutting depthVSAvoidload-bearing capacity of support arm
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The support arm is divided into functional segments: a compact second end for achieving cutting depth and a reinforced first end with metal arm cover for withstanding forces. This segmentation allows each part to be optimized for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The metal arm cover is applied locally at the first end of the support arm where forces are generated, rather than throughout the entire support arm. This local reinforcement provides the necessary load-bearing capacity at the critical location while maintaining the compact and delicate design at the second end for achieving cutting depth.

Inventive Principle:
Principle #3Local quality

3Strength

If the arm cover is made of metal material to withstand high forces, then the strength and rigidity are improved, but the weight of the arm cover increases

Engineering Contradiction:
Improvestrength and rigidity of arm coverVSAvoidweight of arm cover
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The support arm combines different materials: a compact structure at the second end and a metal material (aluminum or magnesium alloy) for the arm cover at the first end. This composite approach allows the support arm to achieve both compactness for cutting depth and sufficient strength for withstanding forces.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The metal arm cover is applied locally at the first end of the support arm where forces are generated, rather than throughout the entire support arm. This local reinforcement provides the necessary load-bearing capacity at the critical location while maintaining the compact and delicate design at the second end for achieving cutting depth.

Inventive Principle:
Principle #3Local quality

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 metal arm cover effectively transmits high forces without damage, enhancing the support arm's stability and rigidity while maintaining a compact design, thus preventing damage and ensuring efficient operation under high forces.

Implementation Method 1

An arm cover made of a metal material has the advantage over conventional plastic arm covers that, due to the higher modulus of elasticity, forces generated can be transmitted by the arm cover without damaging the arm cover.

Methodology Applied
Scientific EffectModulus of elasticity: Elasticity

Data Source

PatentEP3670080B1Hand-held abrasive cut-off machine
Publication Date: 2024.05.22 HILTI AG
  • EP3670080B1 patent drawingFigure 1A~1B
  • EP3670080B1 patent drawingFigure 2~3

AI summary

Hand-held angle grinder comprising a cutting disc, a motor housing with a drive unit and a boom with a support arm and an arm cover, which is attached to the support arm via several fastening elements.