Oscillating Tool Coupling Surfaces for Higher Torque Fatigue Strength
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Solution Overview
Problem
Oscillating tools experience torque-related stress issues due to alternating bending loads, 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 and reducing local loads through a larger force application point, and incorporating curved or flat drive surfaces to enhance torque transmission and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool is mounted directly on the drive unit with conventional mounting, then the connection is simple, but the alternating bending loads cause microcracks and reduced fatigue strength
Solution Approach 1:
The mounting device is divided into a connection device with drive surfaces and a tool bearing with tool receiving surfaces, separating the torque transmission function from the tool mounting function. This segmentation allows the drive surfaces to be designed specifically for torque distribution while the tool bearing provides secure tool attachment, resolving the contradiction between reliability and complexity.
Solution Approach 2:
The drive surfaces are arranged at a distance from the axis of rotation in a radial direction, creating a moment arm that transforms the torque application. This dimensional arrangement distributes the bending loads across multiple surface contact points rather than concentrating them at the mounting interface, improving fatigue strength without excessive complexity.
2Strength
If torque is applied at the axis of rotation, then the connection is direct, but the local loads become too high causing premature failure
Solution Approach 1:
The drive surfaces are positioned at a radial distance from the axis of rotation rather than at the center, creating localized contact points that distribute the torque load. This local quality change ensures that high torque capacity is achieved through distributed surface contact rather than concentrated axial loading, reducing peak stresses.
Solution Approach 2:
The drive surfaces and tool receiving surfaces are designed with curved geometries that conform to each other, creating extended contact areas rather than point contacts. This curvature allows torque to be distributed across larger surface areas, reducing local loads while maintaining high torque load capacity.
3Power
If the drive surfaces are arranged close to the axis of rotation, then the mounting is compact, but the torque transmission efficiency is reduced
Solution Approach 1:
The drive surfaces are arranged in a radial direction at an optimized distance from the axis of rotation, creating a moment arm that improves torque transmission efficiency. This radial dimensionality change allows the mounting device to maintain a compact overall volume while achieving effective torque transmission through the lever arm effect.
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 torque load capacity, reduces peak loads, and extends the tool's service life by improving torque distribution and stress management.
Implementation Method 1
drive surfaces arranged at a distance from the axis of rotation with inclined tangential planes, distributing torque and reducing local loads through a larger force application point
Implementation Method 2
at least two drive surface areas... each having a plurality of surface points... arranged at a distance from this tool axis of rotation
Implementation Method 3
The tangent planes at these surface points are inclined relative to a radial plane and relative to an axial plane
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a tool assembly suitable for use with a machine tool, particularly a hand-held one, which has a drive unit that moves about a drive axis, in particular in an oscillating manner. The tool assembly has a connection device with which it can be attached to a machine tool such that its drive axis and a tool rotation axis essentially coincide. For receiving a drive force, the connection device has at least two drive surface areas, each with a plurality of surface points, arranged at a distance from this tool rotation axis. Tangential planes at these surface points are inclined relative to an axial plane that includes the tool rotation axis. Furthermore, these tangential planes are inclined relative to a radial plane that extends perpendicular to the tool rotation axis.In this way, the torque introduced from the machine tool via the drive unit into the tool unit is reliably absorbed.