GB2059829A

GB2059829A - Drill chuck with cutting edges

Info

Publication number: GB2059829A
Application number: GB8032398A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-10-11
Filing date: 1980-10-08
Publication date: 1981-04-29
Also published as: DE3038465A1

Abstract

A drill chuck of the guided multi-jaw type in which the jaws 12 may be simultaneously retracted and moved apart, or advanced and brought together, to accept and hold drills 20 of any of a wide range of diameters, has cutting edges 19 provided on the tips of the jaws, each cutting edge abutting, and being substantially in a plane radial to, a drill held by the chuck. For countersinking, each cutting edge is at an acute angle to the drill, and for spot-facing the cutting edges are perpendicular to the drill. <IMAGE>

Description

SPECIFICATION A countersinking drill chuck BACKGROUND OF THE INVENTION THIS INVENTION relates to a countersinking drill chuck.

When it is required that holes be drilled, and also countersunk, or de-burred, or counter-bored, or spot-faced, it is the usual practice, when the hole has been formed by the use of a twist drill, to carry out the subsequent operation by using a larger-diameter drill of a countersink-cutting tool. This involves the time consuming changing of tools engaged by the drilling machine chuck, and the result is often unsatisfactory, as the largerdiameter drill or countersink tool may not be precisely or positively centred on the hole already formed, resulting in a countersink which is rough and multisided owing to chattering of the tool.

It is known to provide countersinks capable of being engaged coaxially on drills, such a tool commonly being in the form of a sleeve held removably on the drill by a set screw, and having cutting edges for countersinking the hole formed by the drill. I am also aware of U.K. Patents Nos. 1,378,868 and 1,378,869 which relate to a countersinker assembly for attachment to a twist drill, having an axial bore to accommodate the drill and being divided longitudinally into two halves, each with a cutting edge, and means for urging the halves together to clamp onto the drill. I am aware also of U.K. Patent No.

1,498,841 relating to a countersink and/or counterbore device having a cutter and a shank which may be engaged by a drilling machine chuck, a bore being formed axially through the shank and cutter to receive a twist drill which is secured releasably by a set screw.

Each of these tools is made to be fitted onto a drill of one particular diameter, and so for each drill size, a separate countersink-cutting tool is required.

The present invention has been devised with the general object of providing a drill chuck, adjustable to engage drills of a range of diameters, and incorporating means for quickly and accurately countersinking holes formed by any such drill.

SUMMARY OF THE INVENTION Accordingly, the invention resides broadly in a drill chuck of the type having a plurality of jaws and means for causing them simultaneously to diverge or to converge to accept, and to grip between them, drills of different diameters; wherein at least one of the jaws is provided at its end with a cutting edge abutting, and in a plane substantially radial to the axis of, a drill engaged by the jaws. Other features of the invention will become apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS In order that preferred embodiments of the invention may be readily understood and carried into practical effect, reference is now made to the accompanying drawings, wherein: Figure 1 is a side elevational view of a countersinking drill chuck according to the invention, engaging a twist drill, Figure 2 is a bottom view of the chuck and drill shown in Fig. 1, Figure 3 is a half-sectioned view of the chuck with its jaws in fully opened position, and Figure 4 is a half-sectioned view of a chuck modified for spot-facing and counter-boring.

DETAILED DESCRIPTION OF THE PRE FERRED EMBODIMENTS Each of the chucks shown in the drawings is generally of conventional guided three-jaw type, having a body 10 within which there are formed oblique guides 11 for three similar convergent jaws 12, their drill-gripping edges 13 being parallel to and equidistant from the axis of the chuck. Each of the jaws 12 is formed with teeth 14 engaged by a threaded annulus 15 secured in a collar 16 rotatably mounted on the chuck body. The collar may be rotated by means of a geared operating key (not shown) of usual type rotatable in any one of a number of radial holes 17 in the chuck body, the geared key meshing with teeth 18 formed on the collar.Rotation of the collar in one direction causes the jaws 12 to be moved outwardly of the chuck body, and thus towards each other, rotation of the collar in the opposite direction causing the jaws to be retracted and moved apart.

The outer end portion or tip of each of the jaws 12 is formed with a cutting edge 19 lying in a plane radial to the axis of the chuck and passing through the drill-gripping edge 13 of the jaw. When, as shown in Figs. 1 and 2, a twist drill 20 is held between the jaws 12, the cutting edges 19 of the jaws abut against the drill.

In the embodiment shown in Figs. 1, 2 and 3, the cutting edge 19 of each jaw 12 is at an angle of about 45 to the drill 20, and is formed by conical grinding and radial grinding which automatically give the edge its cutting clearance without complicated non-circular clearance grinding. It will be seen that each cutting edge 19 will remain in a plane radial to the chuck axis however the jaws are extended or retracted to engage drills of different diameters.

A hole formed by the drill will be countersunk by advancing the drill sufficiently to cause the cutting edges 19 to cut into the workpiece, and the countersink will be clean and accurate. De-burring may be effected by a very brief application of the cutting edges 19.

In the embodiments shown in Fig. 4, the cutting edges 19 are perpendicular, instead of oblique, to the axis of the chuck, and the outside part of the tip of each of the jaws 1 2 is relieved, as indicated at 21, to give the necessary cutting clearance. This form of the invention is use for spot-facing, or forming a plane machined seating about a drilled hole, or for counter-boring a hole.

Claims

1. A drill chuck of the type having a plurality of jaws and means for causing them simultaneously to diverge or to converge to accept and to grip between them drills of different diameters; wherein at least one of the jaws is provided at its end with a cutting edge abutting, and in a plane substantially radial to the axis of, a drill engaged by the jaws.

2. A drill chuck according to Claim 1 wherein the cutting edge is inclined at an acute angle to the axis of the chuck.

3. A drill chuck substantially as herein described with reference to Figs. 1, 2 and 3 of the accompanying drawings.

4. A drill chuck substantially as herein described with reference to Fig. 4 of the accompanying drawings.