Oscillating Tool Coupling Surfaces for Higher Torque Fatigue Life
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Solution Overview
Problem
Oscillating tools used in hand-held machine tools experience torque-related stress issues due to alternating bending, leading to microcracks and reduced fatigue strength, resulting in premature failure.
Innovation Solution
The tool device features drive surfaces arranged at a distance from the axis of rotation with inclined tangential planes, distributing torque loads and reducing peak stresses through a connection device with multiple drive surface areas and boundary planes, enhancing torque absorption and force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool device uses a conventional connection device with flat drive surfaces, then the structure is simple and easy to manufacture, but the torque load causes alternating bending stresses leading to microcracks and reduced fatigue strength
Solution Approach 1:
The connection device is segmented into multiple drive surface areas (at least two) arranged at different positions around the axis of rotation. Each drive surface area independently absorbs torque loads, distributing the stress and preventing concentration of bending stresses at a single location, thereby reducing microcrack formation and improving fatigue strength.
Solution Approach 2:
The drive surfaces are arranged in multiple dimensions around the axis of rotation rather than on a single flat plane. This spatial distribution allows torque loads to be absorbed from multiple directions, converting the bending stress problem into a more balanced multi-axial stress state that reduces alternating bending and improves fatigue resistance.
2Power
If the drive surfaces are arranged at a distance from the axis of rotation with inclined tangential planes, then torque absorption capacity increases, but the manufacturing precision requirements increase
Solution Approach 1:
Different regions of the connection device have different functional qualities: the drive surface areas have inclined tangential planes optimized for torque absorption, while other regions maintain simpler geometries. This localized optimization allows high torque capacity where needed without uniformly increasing manufacturing precision requirements across the entire device.
Solution Approach 2:
The inclination angle of the tangential planes is optimized to balance torque absorption capacity with manufacturing feasibility. By selecting appropriate inclination parameters within a reasonable range, the design achieves high power transmission capability while maintaining manufacturability through standard machining processes and tolerances.
3Duration of action of moving object
If multiple drive surface areas are used to distribute torque loads, then local loads are reduced and service life is extended, but the device complexity increases
Solution Approach 1:
The connection device is divided into multiple drive surface areas (at least two) that independently share the torque load. This segmentation distributes localized stresses across multiple regions, preventing any single area from experiencing excessive peak loads, thereby extending service life and reducing premature failure from fatigue and microcracks.
Solution Approach 2:
Multiple drive surface areas are integrated into a unified connection device structure that functions as a single component. This merging approach achieves load distribution benefits of multiple surfaces while maintaining the simplicity of a monolithic or closely-integrated structure, minimizing the increase in device complexity.
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 design increases the tool's torque load capacity, reduces local loads, and extends service life by evenly distributing forces, thereby improving operational stability and durability.
Implementation Method 1
The torque resulting from the machining forces is superimposed by another torque that is effective both during machining and when idle, namely the torque resulting from the mass moment of inertia of the tool for braking the tool after its highest speed
Implementation Method 2
at least two drive surface areas arranged at a distance from this tool axis of rotation are provided, each of which has a large number of surface points
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a tool device which is suitable for use with a machine tool, in particular a hand-held machine tool, which has a drive device which moves, in particular in an oscillating manner, about a drive axis. The tool device has a connection device with which it can be attached to a machine tool in such a way that its drive axis and a tool axis of rotation essentially coincide. In order to absorb a driving force, the connection device has at least two driving surface areas which are arranged at a distance from this tool axis of rotation and each have a large number of surface points. In this case, tangential planes at these surface points are inclined with respect to an axial plane which includes the tool axis of rotation. Furthermore, these tangential planes are inclined with respect to a radial plane which extends perpendicularly to the axis of rotation of the tool. In this way, the torque introduced into the tool device by the machine tool via the drive device is reliably absorbed.