Quick Clamping Device for Angle Grinder Drive Shaft

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Solution Overview

Problem

Existing quick clamping devices for portable power tools, such as angle grinders, face challenges in providing efficient and operator-friendly mechanisms for tool-free fixing and release, especially at high rotational speeds, and in preventing inadvertent release of tools.

Innovation Solution

A quick clamping device with a movably mounted clamping element and operator control unit, featuring a decoupling unit that separates the operator control unit from the clamping unit at high rotational speeds, and a securing unit that prevents unintended movement of the clamping element, allowing for tool-free fixing and release with low actuation force and high operator convenience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the operator control unit is directly connected to the clamping unit for tool-free fixing, then the ease of operation is improved, but at high rotational speeds the reliability deteriorates due to centrifugal forces affecting the clamping element position

Engineering Contradiction:

Improveease of tool attachment and detachmentVSAvoidreliability of clamping element position at high rotational speeds

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system is divided into two functional segments: the operator control unit and the clamping unit, connected through a decoupling mechanism. This segmentation allows the control unit to operate independently from the clamping unit during high-speed rotation, preventing centrifugal forces from affecting the clamping element position while maintaining operational control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A decoupling unit acts as an intermediary between the operator control unit and the clamping unit. This intermediary mechanism transmits control forces during low-speed operations but decouples the connection during high-speed rotation, thereby maintaining reliability while preserving ease of operation during normal conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the clamping element is made freely movable for easy release, then the ease of operation is improved, but the risk of inadvertent release increases

Engineering Contradiction:

Improveease of tool releaseVSAvoidprevention of inadvertent release

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The clamping element's movement characteristics are made dynamic rather than static. The element is freely movable during low-speed operations for easy release, but automatically restricts movement during high-speed rotation through centrifugal forces, thereby preventing inadvertent release while maintaining ease of operation during normal conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The movement constraints of the clamping element are changed as a parameter based on operational conditions. During low-speed operation, the element allows free movement for easy release; during high-speed rotation, centrifugal forces naturally restrict movement, thereby preventing inadvertent release while preserving operational ease.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If a complex decoupling mechanism is added to prevent inadvertent release at high speeds, then the reliability is improved, but the device complexity increases

Engineering Contradiction:

Improveprevention of inadvertent release at high rotational speedsVSAvoidcomplexity of clamping mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The clamping element utilizes the rotational speed of the tool itself to automatically regulate its movement. During high-speed rotation, centrifugal forces generated by the rotating tool naturally restrict the clamping element's movement, preventing inadvertent release without requiring additional active control mechanisms or complex decoupling devices.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The potentially harmful centrifugal forces generated during high-speed rotation are converted into a beneficial effect. These forces naturally restrict the clamping element's movement, preventing inadvertent release and improving reliability, thereby transforming a potentially problematic physical effect into a useful safety mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11607772B2Quick clamping device for at least one rotationally drivable drive shaft having a portable machine tool, in particular an angle grinding machine

Publication Date: 2023.03.21 ROBERT BOSCH GMBH

AI summary

A quick clamping device for a portable machine tool includes at least one drive shaft, at least one clamping unit, and at least one operating unit. The clamping unit has, for tool-less fastening of an insertion tool on the drive shaft, at least one clamping element for exerting a clamping force on the insertion tool in a clamping position. The operating unit is configured to move the clamping element into a release position, and includes at least one operating element, in particular an operating lever. The operating element has at least one activation surface for movement of the clamping element into the release position. The activation surface is arranged such that at least one force initiation point of the operating element is movable, upon interaction with a contact surface of an actuating element of the operating unit, as a factor of movement of the operating element on the contact surface.