Impact power tool

Abstract

An object of the invention is to provide an improved technique for lessening an imp force caused by rebound of a tool bit after its striking movement in an impact power tool. representative impact power tool comprises a tool body, a hammer actuating member, a holder, a driving mechanism, a weight placed in contact with the hammer actuating member move rearward by a reaction force transmitted from the hammer actuating member when hammer actuating member performs a hammering operation on the workpiece and an ela element elastically deformed when the weight moves rearward in the tool body to push the ela element such that the elastic element absorbs the reaction force transmitted to the weight. weight is defined one or both of the cylinder and the tool holder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view schematically showing an entire electric hammer d according to a first embodiment of the invention under loaded conditions in which a hammer bit pressed against a workpiece.

FIG. 2 is an enlarged sectional view showing an essential part of the hammer drill.

FIG. 3 is a sectional plan view showing the entire hammer drill.

FIG. 4 is a sectional plan view showing an electric hammer drill according to a seco embodiment of the invention under loaded conditions in which the hammer bit is pressed agains workpiece.

FIG. 5 is a sectional plan view showing the hammer drill during operation of an impa damper.

FIG. 6 is a partially enlarged view of FIG. 4.

FIG. 7 is a sectional plan view showing an electric hammer drill according to a thi embodiment of the invention under loaded conditions in which the hammer bit is pressed against workpiece.

FIG. 8 is a sectional plan view showing the hammer drill during operation of the impa damper.

FIG. 9 is a partially enlarged view of FIG. 7.

FIG. 10 is a sectional plan view showing an electric hammer drill according to embodiment as a reference example of the invention under loaded conditions in which th hammer bit is pressed against a workpiece.

FIG. 11 is a sectional plan view showing the hammer drill during operation of the impa damper.

FIG. 12 is a partially enlarged view of FIG. 7.

Claims

1. An impact power tool comprising: a tool body,a hammer actuating member that is disposed in a tip end region of the tool body a performs a predetermined hammering operation on a workpiece by reciprocating movement in axial direction,a tool holder to entirely or partially hold the hammer actuating member,a driving mechanism that is disposed on the rear side of the tool body opposite hammer actuating member and linearly drives the hammer actuating member,a cylinder that houses the driving mechanism,a weight placed in contact with the hammer actuating member to move rearward in tool body by a reaction force transmitted from the hammer actuating member when the ham actuating member performs a hammering operation on the workpiece andan elastic element elastically deformed when the weight moves rearward in the t body to push the elastic element such that the elastic element absorbs the reaction fo transmitted to the weight, wherein the weight is defined one or both of the cylinder and the t holder.

2. The impact power tool as defined in claim 1, wherein the weight is placed in cont with the hammer actuating member via an intervening member made of metal and is caused move rearward in the tool body by receiving a reaction force from the hammer actuating mem via the intervening member.

3. The impact power tool as defined in claim 1, wherein, while the weight entirely partially comprises the cylinder, the cylinder includes a rear cylinder element that comprises a portion of the cylinder and defines the weight and a front cylinder element that comprises a portion of the cylinder, and wherein the rear cylinder element is separated from the front cyli element and placed in contact with the hammer actuating member via the front cylinder eleme via the metal intervening member and the front cylinder element in series, and the rear cyl element is caused to move rearward in the tool body by a reaction force transmitted from hammer actuating member via the front cylinder element or via the metal intervening member the front cylinder element.

4. The impact power tool as defined in claim 1, wherein, when the weight entirely partially comprises the tool holder, the tool holder includes a rear tool holder element comprises a rear portion of the tool holder and defines the weight and a front tool holder ele that comprises a front portion of the tool holder, and wherein the rear tool holder eleme separated from the front tool holder element and placed in contact with the hammer actua member, and the rear tool holder element is caused to move rearward in the tool body by a reac force transmitted from the hammer actuating member.

5. The impact power tool as defined in claim 1, wherein the hammer actuating mem comprises an impact bolt that is linearly driven in the axial direction by the driving mechani and a tool bit that is caused to reciprocate by receiving a striking force from the impact bolt thereby performs a hammering operation on the workpiece, and wherein, during hammer operation on the workpiece, the impact bolt transmits the reaction force from the workpiece to weight by contact with the weight.

6. The impact power tool as defined in claim 1, wherein the hammer actuating mem further comprises an impact bolt linearly driven in the axial direction by the driving mechan and a tool bit linearly moved by receiving a striking force from the impact bolt to perfo hammering operation on the workpiece, and wherein the tool holder rotates on the axis of hammer actuating member to make the tool bit rotate such that the tool hit performs a ham drill operation by linear striking movement via the driving mechanism and the impact bolt and rotation via the tool holder.

7. The impact power tool as defined in claim 1, wherein the elastic element is provi under a predetermined initial load to normally bias the cylinder forward.

8. The impact power tool as defined in claim 1 further comprising a dynamic vibra reducer having a vibration reducing weight and at least one biasing spring that biases the vibra reducing weight, wherein the vibration reducing weight is positively driven by utilizing a pres fluctuation caused in relation to the movement of the driving mechanism within the cylinder.