Oscillating Tool Drive Surfaces for Torque Absorption
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Solution Overview
Problem
Hand-held machine tools with oscillating drive devices face challenges in reliably absorbing torque, leading to increased stress and reduced fatigue strength due to alternating bending loads, which results in component failure.
Innovation Solution
The tool device is designed with drive surfaces arranged at a distance from the axis of rotation and inclined relative to both axial and radial planes, increasing the force application point and reducing local loads, allowing for improved torque absorption and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tool device is attached to an oscillating drive device, then the tool can perform machining operations with high frequency, but the alternating bending loads cause increased stress and reduced fatigue strength
Solution Approach 1:
The drive surface is designed with a double inclination: inclined relative to the axial plane (angle α) and inclined relative to the radial plane (angle β). This three-dimensional orientation distributes the oscillating loads across multiple dimensional directions, transforming the stress distribution pattern and reducing peak stresses that would otherwise concentrate in a single plane, thereby improving fatigue strength while maintaining high oscillation frequency
Solution Approach 2:
The drive surface features localized regions with different inclination angles (α and β) to optimize stress distribution in specific areas. By creating zones with tailored surface orientations, the design addresses local stress concentration points while maintaining overall structural integrity under high-frequency oscillating loads
2Stress or pressure
If the drive surface is arranged at a distance from the axis of rotation, then the force application point increases and local loads decrease, but the torque transmission path becomes longer
Solution Approach 1:
The drive surface is positioned at an optimized radial distance from the axis of rotation, and inclined at specific angles (α relative to axial plane, β relative to radial plane). This parameter optimization balances the torque transmission path length with the force application point distance, reducing local loads through distributed contact while maintaining efficient torque transmission through geometric optimization
3Strength
If the tangential planes at the drive surface are inclined relative to both axial and radial planes, then the torque absorption capability improves, but the manufacturing complexity increases
Solution Approach 1:
The drive surface is divided into distinct zones with different inclination characteristics: one inclination relative to the axial plane (angle α) and another inclination relative to the radial plane (angle β). This segmentation allows each zone to be optimized for specific torque absorption functions while simplifying the manufacturing process by breaking down the complex double-inclined surface into manageable, independently controllable surface features
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 axis of rotation 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 axis of rotation. Tangential planes at these surface points are inclined relative to an axial plane that includes the tool axis of rotation. Furthermore, these tangential planes are inclined relative to a radial plane that extends perpendicular to the tool axis of rotation.In this way, the torque introduced from the machine tool via the drive unit into the tool unit is reliably absorbed.