Patent ID: 7013986
Filing Date: 2006-03-21
Classification: B25D,B25F,Y10T

Abstract:
1. An impact tool comprising: an impact tool assembly including a reciprocating ram, an anvil positioned forward of said ram to receive an impact force from said ram, a needle chisel holder for carrying needle chisels longitudinally and movably, and for receiving the impact force from said ram through said anvil, and a cylinder that accommodates said ram, anvil and needle chisel holder in coaxial alignment with one another; a cylindrical housing slidably retaining said impact tool assembly; and a grip extending outward from one side of said housing, said grip being adapted to be held by an operator; wherein said cylinder has a small-diameter portion extending axially along an outer peripheral surface of said cylinder through a predetermined length, said small-diameter portion having a front end and a rear end, said cylindrical housing having a spring engaging portion provided on an inner peripheral surface thereof, said cylindrical housing further having a spring retainer provided at a rear end thereof, wherein a first coil spring is set between the front end of said small-diameter portion of said cylinder and the spring engaging portion of said cylindrical housing, and a second coil spring is set between the rear end of said small-diameter portion and said spring engaging portion, and a third coil spring is set between a rear end of said impact tool assembly and the spring retainer at the rear end of said cylindrical housing, said first and second coil springs being adapted to floatingly support said impact tool assembly in an axial direction of said cylindrical housing, said third coil spring being adapted to receive a substantial part of reaction force acting on said impact tool assembly when tips of the needle chisels are pressed against a workpiece to perform a desired operation.