Patent ID: 7677325
Filing Date: 2010-03-16
Classification: B23D,B24B

Abstract:
1. A pneumatic tool comprising: a tubular housing having a rear end and a forward end; a stationary shaft having a rear end, a forward end, and extending in the housing forward from the rear end of the housing in an axial direction of the housing; a first piston having a forward end and a shaft sliding hole longitudinally extending therethrough and being slidably engaged with the stationary shaft so that the first piston is slidable along the stationary shaft, the shaft sliding hole having an inner wall surface and a forward end portion; a second piston disposed at the forward end of the first piston; a tool attachment member drivingly connected to the second piston and extending forward in the axial direction of the housing through the forward end of the housing, the tool attachment member being configured to attach a tool to a forward end thereof; a first urging member configured to urge the first piston forward; a second urging member configured to urge the second piston rearward; a compressed air supply path configured to supply compressed air between the first piston and second piston; and an air discharge path for discharging the compressed air supplied between the first piston and second piston to an outside of the housing when the first piston and the second piston are driven rearward and forward, respectively, and separated by a predetermined distance by the compressed air supplied therebetween and against the first urging member and the second urging member; the compressed air supply path comprising an axial portion extending in the stationary shaft along an axis of the stationary shaft, the axial portion having a rear end configured to be connected to a compressed air source and extending from the rear end of the stationary shaft to a position adjacent a forward end of the stationary shaft, a radial portion extending radially from the axial portion at a position adjacent the forward end of the stationary shaft and opening on a side surface of the stationary shaft, and a recess in the inner wall surface of the shaft sliding hole behind the forward end portion of the shaft sliding hole, the recess extending in an axial direction of the shaft sliding hole and being in communication with the radial portion of the compressed air supply path to receive compressed air, the recess extending forward beyond the forward end of the stationary shaft to enable compressed air to be supplied between the first piston and the second piston from the axial portion through the radial portion, the compressed air inlet space and a forward end portion of the shaft sliding hole; and wherein the first piston is positioned relative to the stationary shaft such that when the first piston and the second piston are driven to move away from each other by the predetermined distance by compressed air supplied therebetween, the forward end portion of the shaft sliding hole reaches the forward end of the stationary shaft, so that a forward end of the stationary shaft blocks compressed air from being supplied between the first piston and second piston from the compressed air inlet space through the forward end portion of the shaft sliding hole, and wherein the air discharge path is configured to discharge the compressed air supplied between the first piston and the second piston when the first piston and the second piston are driven to move away from each other by the predetermined distance.