Patent ID: 9079286
Filing Date: 2015-07-14
Classification: B24B,B25D,B44B

Abstract:
1. A pneumatic impact tool comprising a pneumatic actuator including a pneumatic cylinder comprising a pneumatic chamber including an air supply inlet, and a piston assembly including a piston base movably mounted in the pneumatic chamber to be driven forward from a home position in the pneumatic chamber to an impact position in the pneumatic chamber in response to pressure delivered via the air supply inlet, the piston assembly further including a striker head operatively connected to and spaced from the piston base and located forward of and outside the pneumatic chamber, the pneumatic impact tool further comprising a non-pneumatic guide bore containing the striker head, the non-pneumatic guide bore located forward of the pneumatic chamber and pneumatically separate from the pneumatic chamber such that the non-pneumatic guide bore remains at a pressure essentially equal to atmosphere outside the pneumatic impact tool, the non-pneumatic guide bore terminating in a graver assembly, the striker head movably positioned in the non-pneumatic guide bore and movable with the piston base toward and away from the graver assembly sufficient to strike the graver assembly at the forward end of a drive stroke, wherein: the piston base has a first diameter and rides in and approximates the diameter of the pneumatic chamber, and a striker pin having a second diameter smaller than the first diameter extends forwardly from the piston base through a forward end of the pneumatic cylinder body and includes an outer end residing outside the pneumatic chamber in the non-pneumatic guide bore, the striker head secured to the outer end of the striker pin in the non-pneumatic guide bore, the striker head having a diameter and mass greater than the diameter and mass of the striker pin and/or a mass greater than the mass of the piston base inside the pneumatic chamber; and, a spring return means in the pneumatic chamber is in operative engagement with the piston base for returning the piston assembly from the impact position to the home position.