Patent ID: 8485274
Filing Date: 2013-07-16
Classification: B25D

Abstract:
1. An impact tool which performs a predetermined hammering operation on a workpiece by a striking movement of a hammer actuating member in its axial direction, including: a tool body, a cylinder housed within the tool body, a driving element that linearly moves in the axial direction of the hammer actuating member, a striker that linearly moves in the axial direction of the hammer actuating member within the cylinder, and an air chamber defined between the driving element and the striker within the cylinder, wherein the striker is caused to linearly move via pressure fluctuations of the air chamber as a result of the linear movement of the driving element and strikes the hammer actuating member, whereby the predetermined hammering operation is performed on the workpiece, comprising: a positioning member that is held in contact with the hammer actuating member under loaded conditions in which the hammer actuating member is pressed against the workpiece and pushed towards the driving element, while being separated from the hammer actuating member under unloaded conditions in which the hammer actuating member is not pressed against the workpiece, an elastically deformable positioning elastic element that positions the tool body with respect to the workpiece by contact with the positioning member under loaded conditions, and in this position, absorbs a reaction force that is caused by rebound from the workpiece and inputted from the hammer actuating member via the positioning member, the elastically deformable positioning elastic element being positioned outside the cylinder, a communication part that provides communication between the air chamber and the outside in order to prevent idle driving, and a communication part opening-closing member comprising the striker disposed inside the cylinder, the communication part opening-closing member being movable between a closed position for closing the communication part and an open position for opening the communication part, wherein, under unloaded conditions, the communication part opening-closing member is placed in the open position for opening the communication part and thereby disables the pressure fluctuations of the air chamber, while, under loaded conditions, the communication part opening-closing member is pushed by the hammer actuating member or the positioning member to the closed position for closing the communication part and thereby enables the pressure fluctuations of the air chamber.