Oscillating Tool Attachment Geometry for Torque and Fatigue Loads
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Solution Overview
Problem
Existing machine tools with oscillating tools face challenges in reliably absorbing the torque introduced by machining forces, leading to stress concentrations and reduced operational stability due to the alternating bending stresses, which result in micro cracks and reduced fatigue life.
Innovation Solution
The tool device is designed with driving area regions spaced apart from the axis of rotation and inclined, allowing for a larger force application point, reducing local loads, and featuring a planar or curved surface to improve force transmission and stability, thereby enhancing the tool's ability to absorb torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tool device uses a conventional attachment device with circumferential driving device, then the tool can be rotated at high speeds (near 0 to several 1000 revolutions per minute), but the alternating bending stresses from oscillating motion cause stress concentrations and micro cracks, reducing fatigue life and operational stability
Solution Approach 1:
The attachment device is segmented into multiple driving area regions (at least two) spaced apart around the axis of rotation, each region having surface points with tangent planes inclined at different angles. This segmentation distributes the torque transmission across multiple discrete areas, preventing stress concentration at single locations and reducing alternating bending stresses that cause fatigue failures.
Solution Approach 2:
Different driving area regions have different local geometries with tangent planes inclined at different angles relative to radial and axial planes. This local quality variation allows each region to handle torque transmission differently, optimizing stress distribution across the attachment device and preventing uniform stress patterns that lead to fatigue cracking.
2Device complexity
If the tool device concentrates force application at a single point or small area, then the attachment device structure can be simpler, but the local loads create peak stress concentrations that reduce operational stability and cause micro cracks
Solution Approach 1:
The force application is segmented across multiple driving area regions instead of concentrated at a single point. Each region has its own surface points and tangent planes, distributing the mechanical loads across the structure and eliminating peak stress concentrations while maintaining structural integrity.
Solution Approach 2:
The driving area regions are distributed around the axis of rotation in the circumferential direction, adding a dimensional aspect to force application. This spatial distribution transforms a point-load problem into a distributed load system, reducing peak stresses through geometric dispersion of force application points.
Data Source
AI summary
The invention relates to a tool device which is suitable for use with a machine tool, in particular a hand guided machine tool, having a driving device moving, in particular in an oscillating manner, around a driving axis. The tool device has an attachment device which allows it to be fastened on a machine tool such that its driving axis and an axis of rotation of the tool substantially coincide. The attachment device, for absorbing the driving force, has at least two driving area regions, which are spaced apart from said tool axis of rotation and each has a plurality of surface points. The tangent planes to said surface-area points are inclined in regard to an axial plane, which encloses the tool axis of rotation. Furthermore, said tangent planes are inclined regard to a radial plane which extends perpendicularly to the tool axis of rotation. This means that the torque introduced into the tool device by the machine tool, via the driving device, is reliably absorbed.