Cut-Off Machine 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 compromised 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 increase cutting depth, then cutting depth is improved, but stability and rigidity deteriorate

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

Solution Approach 1:

The arm cover is made of metal material (aluminum or magnesium) instead of conventional plastic, creating a composite structure with the support arm. This metal arm cover provides the necessary rigidity and stability to withstand high processing forces while allowing the support arm to maintain a compact and delicate design for increased cutting depth.

Inventive Principle:
Principle #40Composite materials

2Length of moving object

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

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

Solution Approach 1:

The metal arm cover serves as a load-bearing component that works together with the support arm. The metal material (aluminum or magnesium) provides high strength-to-weight ratio, enabling the compact support arm design while maintaining sufficient load-bearing capacity to handle high processing forces.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The arm cover is specifically positioned and designed to provide reinforcement where needed - covering the support arm in regions subjected to high forces during operation. This localized reinforcement allows the support arm to remain compact and delicate in other areas, maintaining cutting depth capability while providing strength where required.

Inventive Principle:
Principle #3Local quality

3Weight of moving object

If conventional plastic arm cover is used, then weight is reduced, but force transmission capability deteriorates

Engineering Contradiction:
Improvearm cover weightVSAvoidforce transmission capability
Core Design Contradiction:
Weight of moving objectVSForce

Solution Approach 1:

The arm cover material is changed from plastic to metal (aluminum or magnesium), fundamentally changing the material parameters including modulus of elasticity, strength, and force transmission capability. This parameter change enables the arm cover to transmit and withstand high forces generated during cutting operations while maintaining relatively low weight due to the lightweight metal materials used.

Inventive Principle:
Principle #35Parameter changes

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 and maintains cutting depth, offering improved stability and rigidity while optimizing weight with light metal materials like aluminum or magnesium.

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

PatentEP3670077B1Hand-held abrasive cut-off machine
Publication Date: 2024.05.15 HILTI AG
  • EP3670077B1 patent drawingFigure 1A~1B
  • EP3670077B1 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.