Tool Holder Locking Sleeve Geometry for Wear-Resistant Power Tools

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Solution Overview

Problem

Existing hand-held power tools with tubular tool holders experience significant wear in the locking mechanism, limiting their use in powerful applications due to insufficient resistance to wear in the locking elements and pressure sleeves.

Innovation Solution

The design incorporates a stop sleeve with a spherical contact surface and a spring-actuated pressure sleeve with adapted pressure surfaces, ensuring surface contact with locking elements to enhance wear resistance, and a locking sleeve for simple unlocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional locking elements with point contact are used, then the device complexity is low, but the wear resistance is insufficient

Engineering Contradiction:
Improvewear resistanceVSAvoidcontact surface geometry
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking elements are designed with spherical contact surfaces that match the spherical inner surface of the stop sleeve. This curvature adaptation transforms point contact into surface contact, significantly increasing wear resistance while maintaining relatively simple spherical geometry in both the locking elements and the stop sleeve.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Power

If the tool holder is used in powerful hand-held power tools, then the power capability is improved, but the wear on locking mechanism increases

Engineering Contradiction:
Improvepower capabilityVSAvoidwear resistance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The spherical contact surfaces between the locking elements and the stop sleeve distribute the high loads from powerful applications over larger contact areas. This surface contact geometry reduces contact stress and wear, enabling the tool holder to withstand the demands of powerful hand-held power tools.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Duration of action of stationary object

If point contact locking elements are used, then the manufacturing is simple, but the service life is limited

Engineering Contradiction:
Improveservice lifeVSAvoidcontact surface precision
Core Design Contradiction:
Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The spherical contact surfaces can be manufactured using standard spherical machining operations. The stop sleeve receives a spherical inner surface, and the locking elements are provided with matching spherical contact surfaces. This geometry, while requiring precision, uses conventional manufacturing methods and significantly extends service life through surface contact.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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

This configuration significantly extends the service life of the tool holder and allows its use in more powerful hand-held power tools by reducing wear on the stop and pressure sleeves.

Implementation Method 1

a pressure sleeve (230) which is spring-loaded via an associated spring element (280)

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4063076B1Handheld machine tool with locking device
Publication Date: 2026.04.08 ROBERT BOSCH GMBH
  • EP4063076B1 patent drawingFigure 1
  • EP4063076B1 patent drawingFigure 2
  • EP4063076B1 patent drawingFigure 3~4

AI summary

In a hand-held power tool with a tool holder (140) having a tubular tool holder (210) in which an insert tool (190) can be locked by an associated locking device (200) via at least one locking element (250), wherein the locking device (200) has a pressure sleeve (230) actuated by an associated spring element (280) and a stop sleeve (242), wherein the spring-actuated pressure sleeve (230) acts the at least one locking element (250) against the stop sleeve (242) in a locking position, and wherein the tubular tool holder (210) has at least one recess (216) in which the at least one locking element (250) is arranged at least partially in the locking position, the stop sleeve (242) has at least one contact surface (244) on its inner circumference (249).which is adapted to an outer contour (255) of the at least one locking element (250) in order to enable surface contact between the at least one contact surface (244) and the at least one locking element (250) in the locking position.