Hand-held machine tool for sanding or polishing a workpiece adapted for realizing two different types of working movements

Abstract

The invention refers to a hand-held machine tool for sanding or polishing a workpiece, the machine tool comprising: a housing, a motor for actuating a tool shaft of the machine tool and for making thetool shaft rotate about its axis of rotation, and a backing pad for releasable attachment of a sanding element or a polishing element thereto and eccentrically attachable to the tool shaft by means of an eccentric element in such a way as to allow the backing pad to perform a working movement, wherein the machine tool is adapted for realizing two different types of working movements of the backing pad attached thereto. It is suggested that the housing of the machine tool comprises a plurality of first magnetic elements facing the backing pad, and that the backing pad attached to the eccentricelement comprises a plurality of second magnetic elements facing the housing, wherein the machine tool is adapted for realizing a first type of working movement if a magnetic force is active betweenat least some of the first and second magnetic elements, and is adapted for realizing a second type of working movement if no magnetic force is active between the first and second magnetic elements.

Description

technical field [0001] The present invention relates to a hand-held machine tool for sanding or polishing workpieces. The machine tool includes a housing, a motor for actuating and rotating a tool shaft of the machine tool about its axis of rotation, and a backing pad for releasably attaching a sanding or polishing element thereto , the backing pad is eccentrically attached to the tool shaft by an eccentric element, thereby allowing the backing pad to perform working movements. The machine tool is adapted to achieve two different types of working motions of the backing pad to which it is attached. Background technique [0002] Conventional machine tools have backing pads that perform only one specific type of working motion, depending on the type of connection or coupling of the backing pad to the motor shaft via gearing and / or eccentric elements, etc. For example, an orbital sander or polisher with a backing pad that performs a pure orbital motion, a random orbital sander...

AI Technical Summary

Problems solved by technology

[0005] This known sander has several disadvantages: firstly, the switch for selecting the desired type of working motion acts on the mechanical transmission arrangement located inside the housing and connects the motor shaft to the backing pad

Furthermore, purely rotary working motions are not very efficient and require particularly powerful motors to compensate for any power loss in the backing pad, or the backing pad operates in rotary working motion with only reduced power

Finally, the mechanical transmission arrangement that can switch between the two different types of working movements of the backing pad is mechanically complex, heavy and, due to its complex structure, not very strong and very expensive

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