Angle Grinder Protective Hood Clamping Mechanism

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Solution Overview

Problem

Hand-held power tools, such as angle grinders, face difficulties in adjusting the protective hood due to varying clamping forces and the need for precise alignment, which complicates setting and securing the hood in different rotational positions.

Innovation Solution

A clamping device that allows adjustable clamping forces between maximum and zero, enabling the protective hood to be securely positioned and adjusted independently of the clamp's preload, with a clamping screw that is axially adjustable and rotatable, using alternating axial supports and abutments for secure positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the protective hood is frictionally locked and form-fittingly fixed to the bearing neck via a clamp with radially flared clamping ends, then the protective hood achieves secure positioning and reliable locking, but the clamping forces required for loosening become correspondingly large, making adjustment difficult and requiring relatively large clearance

Engineering Contradiction:
Improvesecure positioning of protective hoodVSAvoidadjustment of protective hood
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The clamp is designed with dynamically adjustable clamping force through a clamping device that allows the operator to vary the preload on the clamping ends. The clamping force can be reduced during adjustment operations to enable easy loosening and repositioning, then increased during operation to maintain secure frictional locking and form-fitting fixation. This dynamic adjustment capability resolves the contradiction between secure positioning and ease of adjustment.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the clamp is designed with high preload to ensure secure locking of the protective hood, then the reliability of positioning is improved, but the effort required to loosen and reposition the clamp increases significantly

Engineering Contradiction:
Improvelocking reliabilityVSAvoidclamping force for loosening
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The clamping device enables parameter changes in the clamping force applied by the clamp. By adjusting the preload on the clamping ends, the operator can reduce the clamping force to minimal levels during adjustment operations, making loosening and repositioning easy. During actual operation, the clamping force can be increased to provide secure locking. This parameter adjustment capability directly resolves the contradiction between locking reliability and the force required for loosening.

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

Facilitates easy and controlled adjustment of the protective hood, allowing for precise rotational positioning and reduced twisting effort, regardless of the clamp's prestress, enhancing operational safety and usability.

Implementation Method 1

one of which is through the screw head of the clamping screw and the other by a support disk that is threaded onto the screw shank

Methodology Applied
Scientific EffectThreaded connection: Screw

Implementation Method 2

the protective hood is frictionally locked in its respective locking position

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2428316B1Hand tool machine, in particular manual angle grinder
Publication Date: 2013.03.06 ROBERT BOSCH GMBH
  • EP2428316B1 patent drawingFigure 1~4
  • EP2428316B1 patent drawingFigure 5~8
  • EP2428316B1 patent drawingFigure 9~11

AI summary

The hand-held machine tool comprises a tool, which is carried by a drive shaft extending through an axle journal (3) and is partially covered by a protective casing (1). A protection collar (4) is provided, which is mounted on the axle journal. The clamp ends (9,10) are provided, which are slidable against each other over a clamping unit in clamping manner and in opening direction.