Oscillating Tool Holder Geometry for Fatigue-Resistant Torque Transfer

Solution Overview

Problem

Existing machine tools with rotating oscillating tool receiving devices face challenges in reliably transmitting output torque due to alternating bending stresses, leading to micro cracks and reduced fatigue strength, resulting in premature failure under high oscillation frequencies.

Innovation Solution

The design features a torque transmission region with output areas arranged at a distance from the rotational axis, inclined to reduce local loads, and a holding device that secures the tool without clearance, allowing for efficient force transmission and tool change, while minimizing peak stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a rotating oscillating tool receiving device is used to transmit output torque, then the tool can perform machining operations at high oscillation frequencies, but alternating bending stresses cause micro cracks and reduce fatigue strength leading to premature failure

Engineering Contradiction:

Improveoscillation frequencyVSAvoidfatigue strength

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating a clearance-free connection between the tool and tool receiving device specifically at the torque transmission interface. This localized structural optimization ensures that critical stress areas have enhanced load distribution and no clearance-induced stress concentrations, while other parts of the system maintain their original design characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by designing the tool receiving device to actively prevent clearance formation through a clearance-free connection mechanism. Instead of accepting clearance as inevitable and designing around it, the solution eliminates clearance at its source, fundamentally changing how the torque transmission interface is constructed to prevent alternating bending stresses and micro crack formation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If a rotating oscillating tool receiving device is used, then machining operations can be performed, but alternating bending stresses result in micro cracks and reduced tool life

Engineering Contradiction:

Improvemachining capabilityVSAvoidtool life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies local quality by creating a clearance-free connection between the tool and tool receiving device specifically at the torque transmission interface. This localized structural optimization ensures that critical stress areas have enhanced load distribution and no clearance-induced stress concentrations, while other parts of the system maintain their original design characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by designing the tool receiving device to actively prevent clearance formation through a clearance-free connection mechanism. Instead of accepting clearance as inevitable and designing around it, the solution eliminates clearance at its source, fundamentally changing how the torque transmission interface is constructed to prevent alternating bending stresses and micro crack formation.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If conventional torque transmission is used with clearance connections, then tool changes are simple, but peak stress concentrations occur leading to premature failure

Engineering Contradiction:

Improvetool change simplicityVSAvoidstress concentration resistance

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent applies local quality by creating a clearance-free connection between the tool and tool receiving device specifically at the torque transmission interface. This localized structural optimization ensures that critical stress areas have enhanced load distribution and no clearance-induced stress concentrations, while other parts of the system maintain their original design characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by designing the tool receiving device to actively prevent clearance formation through a clearance-free connection mechanism. Instead of accepting clearance as inevitable and designing around it, the solution eliminates clearance at its source, fundamentally changing how the torque transmission interface is constructed to prevent alternating bending stresses and micro crack formation.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS10967435B2Power tool

Publication Date: 2021.04.06 C & E FEIN GMBH & CO KG

AI summary

The invention relates to a machine tool, in particular a hand held machine tool, which has a tool receiving device that is movable, in particular in an oscillating manner, around an output shaft. The tool receiving device is designed to hold a tool device on the machine tool in such a manner that the output shaft and a tool rotation axis substantially coincide. The tool receiving device has at least one torque transmission region and a holding device. In order to transmit a driving force to the tool device, the torque transmission region has at least two output area regions that are arranged at a distance from said output shaft and each have a multiplicity of surface points. Here, the tangent planes to said surface points are inclined in regard to an axial plane which includes said output shaft. Furthermore, the tangent planes are inclined in regard to a radial plane which extends perpendicularly to the output shaft. In this way, the output torque is transmitted reliably to the tool device by the machine tool via the tool receiving device.