Angle Grinder Support Arm Reinforcement for Cutting Depth

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Solution Overview

Problem

Hand-held cut-off machines with compact and delicate support arms face reduced stability and rigidity under high processing forces, leading to potential damage and limited cutting depth.

Innovation Solution

The support arm is reinforced with a metal arm cover and strategically positioned fastening elements that divert forces into the arm cover, reducing the load on the support arm and maintaining 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 cutting depth is improved, but stability and rigidity of the support arm deteriorate

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 structure is segmented into two functional parts: the main support arm body and the arm cover. The arm cover is detachably attached to the support arm via fastening elements, allowing the support arm to maintain a compact design for increased cutting depth while the arm cover provides additional structural reinforcement for stability and rigidity under high processing forces.

Inventive Principle:
Principle #1Segmentation

2Length of moving object

If the support arm is made compact and delicate to achieve increased cutting depths, then cutting depth is improved, but the ability to withstand high forces deteriorates

Engineering Contradiction:
Improvecutting depthVSAvoidability to withstand high forces
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The support arm structure combines different material properties through the composite design of the support arm body and the arm cover. The arm cover is made of a different material than the support arm, creating a composite structure that leverages the strengths of each material to simultaneously achieve compactness for cutting depth and sufficient strength to withstand high processing forces.

Inventive Principle:
Principle #40Composite materials

3Strength

If fastening elements are positioned to redirect forces to the arm cover, then load on support arm is reduced, but cutting depth may be reduced

Engineering Contradiction:
Improveload bearing capacity of support armVSAvoidcutting depth
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

The fastening elements are strategically positioned at specific locations on the support arm where they can effectively redirect forces to the arm cover without interfering with the cutting depth. This local optimization of fastening element placement ensures that force redistribution occurs at critical stress points while maintaining the overall compact design and maximum cutting depth capability of the support arm.

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 solution enhances the support arm's ability to withstand high forces without damage, maintaining stability and rigidity while allowing for minimal reduction in cutting depth.

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

PatentEP3670078B1Hand-held abrasive cut-off machine
Publication Date: 2024.05.22 HILTI AG
  • EP3670078B1 patent drawingFigure 1A~1B
  • EP3670078B1 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 by several fastening elements.