Oscillating Tool Holder Geometry for Reliable Torque Transfer

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Solution Overview

Problem

Existing hand-held machine tools face challenges in reliably transmitting output torque to tools with oscillating movements, leading to stress concentrations and reduced operational lifespan due to alternating bending stresses and notch effects in metallic components.

Innovation Solution

The design features output surfaces arranged at a distance from the axis of rotation with inclined orientations, increasing the force application point and reducing local stress, and a torque transmission area with multiple output surface areas between boundary planes for uniform force introduction, enhancing the tool's ability to withstand torque loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the tool holder transmits output torque to the tool during oscillating movement, then the tool can perform machining operations, but alternating bending stresses and notch effects cause stress concentrations that reduce operational lifespan

Engineering Contradiction:
Improvetorque transmission capabilityVSAvoidoperational lifespan
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent applies local quality by creating a torque transmission area with multiple output surface areas arranged between boundary planes. This distributes the torque transmission function across multiple localized contact points rather than a single point, reducing stress concentration at any one location while maintaining overall torque transmission capability

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The torque transmission area is segmented into multiple output surface areas positioned between first and second boundary planes. This segmentation divides the torque transmission function into discrete contact zones, preventing alternating bending stresses from concentrating at a single notch or interface point during oscillating movement

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If output surfaces are arranged close to the axis of rotation, then the structure is compact, but force application point is reduced leading to higher local stress

Engineering Contradiction:
Improvestructural compactnessVSAvoidlocal stress
Core Design Contradiction:
Volume of moving objectVSStress or pressure

Solution Approach 1:

The patent resolves this contradiction by extending the torque transmission in the axial dimension between boundary planes rather than only radially from the axis. Multiple output surface areas are positioned at different axial locations, increasing the effective force application point distance without compromising structural compactness

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Device complexity

If a single output surface area is used for torque transmission, then the structure is simple, but force introduction is non-uniform causing stress concentrations

Engineering Contradiction:
Improvestructure simplicityVSAvoidforce distribution uniformity
Core Design Contradiction:
Device complexityVSStress or pressure

Solution Approach 1:

The single output surface area is segmented into multiple output surface areas positioned between boundary planes. This segmentation creates multiple force introduction points that distribute torque more uniformly across the tool holder interface, reducing stress concentrations while maintaining relatively simple overall structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple output surface areas are merged into a unified torque transmission area bounded by boundary planes. This merging creates a distributed contact zone that achieves uniform force introduction while maintaining structural simplicity through the bounded region approach

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3027367B1Hand-held power tool
Publication Date: 2023.07.19 C & E FEIN GMBH & CO KG
  • EP3027367B1 patent drawingFigure 1~1b
  • EP3027367B1 patent drawingFigure 2
  • EP3027367B1 patent drawingFigure 3~3b

AI summary

The invention relates to a power tool, in particular a hand-held power tool, which has a tool receiving device that is movable, in particular in an oscillating manner, about an output axis (2). The tool receiving device is designed to hold a tool device on the power tool such that the output axis and a tool rotation axis substantially coincide. The tool receiving device has at least one torque transmission region (9) and a holding device (4a, 4b). In order to transmit a drive force to the tool device, the torque transmission region has at least two output surface regions (9a) that are at a distance from said output axis and each have a multiplicity of surface points. Here, tangent planes to said surface points are inclined with respect to an axial plane which includes said output axis. Furthermore, the tangent planes are inclined with respect to a radial plane which extends perpendicularly to the output axis. In this way, the output torque is transmitted reliably to the tool device by the power tool via the tool receiving device.