Angle Grinder Tool Holder for Tool-Less Secure Tool Changes

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Solution Overview

Problem

Existing hand-held power tools require additional tools or fastening elements for tool changes, which are time-consuming and inconvenient, especially at high rotational speeds.

Innovation Solution

A hand-held machine tool with a tool holder device that allows tool attachment and detachment without additional securing elements, utilizing a clamping device with movable hook devices that engage and disengage with centrifugal force at high speeds, enabling quick and tool-less tool changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional fastening elements or tools are used for tool changes, then secure attachment is achieved, but tool change time increases and operation becomes more complex

Engineering Contradiction:
Improvesecure attachmentVSAvoidtool change time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The invention extracts and eliminates the need for separate fastening elements and tools by integrating the clamping function directly into the tool holder device. The clamping device with movable clamping jaws provides secure attachment without requiring additional securing elements, thus reducing tool change time while maintaining reliable tool attachment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The clamping device is designed to be actuated directly by the user's hand during tool insertion, making the fastening process self-service and eliminating the need for separate fastening tools. The mechanical advantage provided by the lever arm enables the clamping action to be performed easily by hand, achieving both speed and security in tool attachment.

Inventive Principle:
Principle #25Self-service

2Reliability

If additional fastening elements or tools are used for tool changes, then secure attachment is achieved, but device complexity increases

Engineering Contradiction:
Improvesecure attachmentVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the functions of tool holding and tool fastening into a single integrated tool holder device. The clamping device with its movable clamping jaws and lever arm is built into the tool holder, eliminating the need for separate fastening elements and tools. This integration reduces device complexity while maintaining secure tool attachment.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The tool holder device is designed with multi-functionality, serving both as the tool mounting structure and as the fastening mechanism. The clamping device can accommodate different tool types while providing a universal fastening action through its movable clamping jaws and lever arm system, reducing the need for multiple specialized components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If clamping device is activated by hand, then tool change speed increases, but clamping force may be insufficient at high speeds

Engineering Contradiction:
Improvetool change speedVSAvoidclamping force
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The clamping device is designed with dynamic characteristics where the clamping force increases with the rotational speed of the tool holder. The movable clamping jaws and lever arm system are configured to utilize centrifugal forces generated during high-speed rotation to enhance the clamping action, ensuring sufficient holding force is achieved automatically as the tool holder reaches operating speed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention utilizes parameter changes where the clamping force is not static but varies with the operational parameters of the tool holder. As the rotational speed increases, the dynamic forces acting on the clamping device increase, automatically adjusting the clamping force to be sufficient for high-speed operation while maintaining quick manual activation capability.

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 fast and convenient tool changes by eliminating the need for additional tools, ensuring secure attachment and detachment, and reducing operational time.

Implementation Method 1

as the rotational speed of the tool holder increases, the clamping device can exert an increased clamping force on the tool holder due to a centrifugal force acting on the clamping device

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP4079452B1Machine tool
Publication Date: 2025.07.30 ROBERT BOSCH GMBH
  • EP4079452B1 patent drawingFigure 1
  • EP4079452B1 patent drawingFigure 2
  • EP4079452B1 patent drawingFigure 3

AI summary

The invention relates to a machine tool, in particular a hand-held machine tool, preferably an angle grinder, which has a tool holding device that is rotatable about an output axis, wherein this tool holding device is configured to hold a tool device, in particular an insert tool, on the machine tool in such a way that the output axis and a tool rotation axis essentially coincide, wherein the tool holding device has at least one driving device and a clamping device movable relative to the driving device, wherein this driving device has at least one torque transmission area arranged at a distance from this output axis for transmitting a drive force to the tool device.It is proposed that the driving device and the clamping device be designed to reach through a recess in the tool device, in particular extending through the entire material thickness of the tool device, and to clamp the tool device by means of the clamping device which is movable essentially in a radial direction to the output axis.