US 5,988,653 AGranted

Auto-locking bit holding system of a hand tool

AssigneeChum Power Machinery Corp.

InventorWen-Chin Kuo

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Abstract

An auto-locking bit holding system includes a plurality of clamping rods secured by a nut to hold a bit in a transmission block being connected to a transmission shaft of an electric hand tool, a shell covered around the transmission block and the nut, and a locating barrel fastened to the shell to stop the nut inside the shell, wherein: the nut has two projecting blocks at one end; the locating barrel has a body and a plurality of longitudinal locating ribs equiangularly spaced around the periphery of the body; an annular impact member is mounted around the cylindrical transmission block between the nut and the locating barrel, the annular impact member having two projecting blocks bilaterally disposed at one end, and a plurality of equiangularly spaced and longitudinally extended locating grooves on the inside respectively forced into engagement with the locating ribs of the body of the locating member, the projecting blocks of the annular impact member being turned with the annular impact member to strike the projecting blocks of the nut when the transmission block is rotated, causing the nut to be fastened tight with threaded portions of the clamping rods.

An auto-locking bit holding system installed in the housing of an electric hand tool to hold a bit, enabling the bit to be turned with the transmission shaft of the electric hand tool, comprising a hollow cylindrical transmission block having a rear end thereof fixedly connected to one end of the transmission shaft of the electric hand tool and a plurality of through holes spaced around a block body thereof, a plurality of clamping rods respectively obliquely inserted through the through holes on the block body of said hollow cylindrical transmission block and forced to hold down said bit, said clamping rods each having a threaded portion at an outer side outside said hollow cylindrical transmission block, a nut having a tapered screw hole threaded onto the threaded portions of said clamping rods, a shell covered around said hollow cylindrical transmission block and said nut, and a locating barrel fastened to a front end of said shell to stop said nut inside said shell, wherein:

said nut comprises two projecting blocks bilaterally axially extended from a front end thereof, said projecting blocks each having two downwardly outwardly extended sloping side walls;
said locating member comprises a body and a plurality of longitudinal locating ribs equiangularly spaced around the periphery of the body;
an annular impact member is mounted around said cylindrical transmission block within said shell between said nut and said locating barrel, said annular impact member having two projecting blocks bilaterally axially extended from a rear side thereof, and a plurality of equiangularly spaced and longitudinally extended locating grooves on the inside respectively forced into engagement with the locating ribs of the body of said locating barrel, the projecting blocks of said annular impact member being turned with said annular impact member to strike the projecting blocks of said nut when said transmission block is rotated, causing said nut to be fastened tight with the threaded portions of said clamping rods.

Abstract

Claims12