Power tools having a quick clamping device are known in the art.  An example of such a tool is found in U.S. Pat.  No.  6,569,001 which is directed to an angular grinder equipped with a hollow mandrel shaft in which a clamping device movable between a clamped position and a released position along the axial direction of the shaft is mounted.  The clamping device comprises a clamping flange which is provided with a threaded pin arranged in the middle thereof and is used for cooperating with an opposite flange on the end of the hollow mandrel shaft to clamp a working element therebetween.  A thrust component mated with the threaded pin is further arranged in the hollow mandrel shaft.  At the clamped position, the threaded pin is screwed into the thread of the trust component and maintained in the clamped position under the action of the spring force, and at the released position, the thrust component pushes the threaded pin so as to drive the clamping flange to overcome the spring force and disengage from the clamped surface of the working element.  Because there is no frictional force therebetween when the clamping flange and the clamped working element rotates relative to each other, the threaded pin of the clamping flange can be manually screwed out of the thrust component without the aid of any accessory so that the working element can be replaced conveniently. 
For this kind of clamping device, the working element can be substantially clamped to the output shaft of the hand tool without any auxiliary tool.  However, this clamping device is only suitable for clamping a device to a rotatably driven working element.  If the working element is to be driven by a vibration device, such that the working element sways forward and rearward along a longitudinal axis of the output shaft, the know clamping device can not ensure continued clamping of the working element against the forces resulting from the operation of such a vibration device.