Oscillating Tool Holder Surfaces for Higher Torque Fatigue Life
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Solution Overview
Problem
Machine tools with rotary-oscillating tool holder devices face challenges in reliably transmitting output torque due to alternating bending stresses, which lead to microcracks and reduced fatigue strength, resulting in premature component failure.
Innovation Solution
The design features a torque transmission area with output surfaces arranged at a distance from the axis of rotation and inclined relative to the radial and axial planes, distributing forces more evenly and reducing peak loads, allowing for improved force transmission and increased service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tool holder device transmits torque through conventional output surfaces, then torque transmission is achieved, but alternating bending stresses cause microcracks and reduce fatigue strength
Solution Approach 1:
The output surfaces are designed with curvature instead of being flat, allowing them to conform to the spherical oscillation path of the tool holder. This curved surface design distributes bending stresses more evenly across the contact area, preventing stress concentration that would lead to microcracks and fatigue failure.
Solution Approach 2:
The patent changes the geometric parameters of the output surfaces by inclining them relative to both the radial plane and axial plane. This dual inclination creates an optimized stress distribution pattern that reduces peak loads while maintaining effective torque transmission capability.
2Strength
If output surfaces are arranged at a distance from the output axis, then peak loads are reduced, but torque transmission efficiency decreases
Solution Approach 1:
The patent introduces a third dimension to the output surface orientation by inclining surfaces relative to both radial and axial planes simultaneously. This creates a three-dimensional stress distribution pattern that reduces peak loads at any single point while maintaining overall torque transmission efficiency through the distributed contact area.
Data Source
Figure 1a~1b
Figure 2
Figure 3a~3b
AI summary
The invention relates to a machine tool, in particular a hand-held machine tool, which has a tool holder that is movable about an output axis, and in particular is movable by oscillation. The tool holder is configured to hold a tool assembly on the machine tool such that the output axis and a tool rotation axis essentially coincide. The tool holder has at least one torque transmission area and a holding device. For transmitting a drive force to the tool assembly, the torque transmission area has at least two output surface areas, each with a plurality of surface points, arranged at a distance from this output axis. Tangential planes at these surface points are inclined relative to an axial plane that encloses this output axis.Furthermore, the tangential planes are inclined relative to a radial plane that extends perpendicular to the output axis. In this way, the output torque is reliably transmitted from the machine tool to the tool holder via the tool holder.