GB1584327A - Drill chuck - Google Patents

Description

(54) DRILL CHUCK (71)l We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a drill chuck which serves for the connection of tools, in particular drill bits, with the spindle of a driving machine, in particular a hand-held power drill.

A drill chuck is known from published German Patent Specification (Offenleguns schrift) No. 26 12 372, wherein a gear for engagement by a chuck key and an annular nut for displacing the chuck jaws are in the form of a component which is inserted in two halves into an annular groove on the chuck body and the two halves are held together by a relatively thin-walled sleeve pushed from the hand side over the halves.

This thin-walled sleeve, evidently constructed as a sheet-metal part, abuts in the direction of the hand side on a steady bearing for supporting the sleeve. The sleeve is rotatably connected with the annular nut for displacing the chuck jaws. The com- pressive force of the sleeve holding together the parts of the annular nut and of the gear is limited by the thin-walled construc tion of the sleeve, which in the event of an impact stress being applied to such chuck favours the loosening of the compressive connection. Such an impact stress occurs especially with impact or percussion power wools.

Furthermore a drill chuck is known from Fig. 3 of published German Patent Specification (Offenlegungsschrift) No. 25 04 219, wherein the annular nut for displacing the chuck jaws is supported rotatably in the annular groove of the chuck body and is constructed in two parts, but the gear for engagement by the chuck key and the sleeve for rotating the nut are made in one piece as a machine-turned part and are pressed from the tool side over the parts of the annular nut. This achieves a better compression of the parts of the annular nut.

This drill chuck has a steady bearing between the sleeve and the body for supporting the sleeve, remote from the annular nut, but which is merely in the form of a radial bearing and does not support the sleeve against axial displacement.

An object of the present invention is to provide an improved drill chuck which does not have the above-mentioned disadvantages.

In accordance with the invention there is provided a drill chuck for connection to a driving machine comprising: a body, a plurality of chuck jaws displaceable along guideways in the body in directions oblique to the chuck axis, an annular nut rotatable in an annular groove surrounding the body and having an internal thread cooperating with an external thread on the chuck jaws for displacing the jaws along the guideways, the annular nut being formed of a plurality of arcuately-extending, circumferentially juxtaposed individual parts, a sleeve, manufactured by machine turning, mounted for rotation on the said body and surrounding the annular nut and that part of the body remote from the chuck jaws, means providing a rotary driving connection from the sleeve to the annular nut, gear teeth formed integrally with the sleeve for engagement by the teeth of a separate drill chuck key, and an annular disc connected to that end of the sleeve remote from the chuck jaws with that side of the disc facing the jaws abutting a shoulder formed on the said body, whereby the disc serves as a bearing enabling the body to support the said end of the sleeve, the body, the nut and the sleeve being so shaped and dimensioned that the chuck can be assembled by passing the sleeve over the body and the annular nut with the chuck jaws therein in the direction from the jaws towards the said shoulder.

The drill chuck according to the invention has the advantage over the prior art that the better compression of the annular nut parts is combined with an additional supporting of the sleeve in relation to the body. The chuck is particularly easy to manufacture, if for the connection of the annular disc to the sleeve, the edge of the sleeve is beaded over onto the disc by a rolling operation. The rolled-in annular disc prevents unintentional disintegration of the drill chuck. For this reason the disc is secured to the sleeve and not to the chuck body.

An embodiment of the invention is hereinafter described, by way of example, with reference to the accompanying drawing of which the sole figure is a side elevational view of a drill chuck in accordance with the invention partly in section.

In the preceding and following description by "tool side" is meant the direction towards the tool, e.g. a drill bit, that is to be chucked, and by "hand side" the opposite direction. The drill chuck comprises a body 1 wherein three chuck jaws 3 move in guideways 2. On the tool side the body 1 has a co-axial bore 4, and on the hand side a co-axial bore 5 with a tapped thread 6. The threaded bore 5 serves for the screwing of the chuck onto the spindle of a driving machine, e.g. a hand-held power drill. The chuck jaws 3 have a thread 7 into which engages the internal thread 8 of an annular nut 9. The annular nut 9 is accomodmated within an annular groove of the body 1 and is guided on the hand side by the boundary plane 10 of the body 1 perpendicular to the chuck axis, and on the tool side by the corresponding plane surface 11 of the annular groove. A machineturned sleeve 12 is integrally formed at its tool side end with a conical gear 13. Adjoining the gear 13 several radial bores 13' are moulded into the body 1 into which can be inserted the peg of a drill chuck key, not shown in the drawing. To enable the annular nut 9 to be positioned in the groove of the body 1 the nut is divided in a median plane parallel to the chuck axis into two semi-circular halves. To assemble the chuck, the sleeve 12 is pushed from the tool side over the body 1 and over these halves with the jaws 3 therein, and drive means (not shown) are provided to ensure that rotary motion of the sleeve 12 is transmitted to the nut 9. On its end on the hand side a shoulder 15 is recessed into the inner surface 14 of the sleeve 12. Into the shoulder 15 an annular disc 16 is inserted, whereupon the projecting edge 17 of the sleeve 12 is beaded over, by a rolling operation, towards the annular disc. As a result the annular dise is joined firmly to the sleeve. On the hand side the body 1 has a shoulder 18 on which the sleeve 12 abuts by means of the annular disc 16 and thus axial movement of the sleeve in the direction towards the chuck jaws is pre vented in the instance that the sleeve should ever become loose.

By a combination of the construction of the sleeve 12 as a machine-turned part of appropriate wall thickness with the abut ment facility of the sleeve on the body 1 of the drill chuck by means of the disc 16, a hitherto unknown security of the chuck against loosening of the sleeve from the divided annular nut 9 has been achieved for the percussion drill operation of drill chucks.

WHAT WE CLAIM IS: 1. A drill chuck for connection to a driving machine comprising: a body, a plurality of chuck jaws displaceable along guideways in the body in directions oblique to the chuck axis, an annular nut rotatable in an annular groove surrounding the body and having an internal thread cooperating with an external thread on the chuck jaws for displacing the jaws along the guideways, the annular nut being formed of a plurality of arcuately-extending, circum ferentially juxtaposed individual parts, a sleeve, manufactured by machine turning, mounted for rotation on the said body and surrounding the annular nut and that part of the body remote from the chuck jaws, means providing a rotary driving connection from the sleeve to the annular nut, gear teeth formed integrally with the sleeve for engagement by the teeth of a separate drill chuck key, and an annular disc connected to that end of the sleeve remote from the chuck jaws with that side of the disc facing the jaws abutting a shoulder formed on the said body, whereby the disc serves as a bearing enabling the body to support the said end of the sleeve, the body, the nut and the sleeve being so shaped and dimensioned that the chuck can be assembled by passing the sleeve over the body and the annular nut with the chuck jaws therein in the direction from the jaws towards the said shoulder.

2. A drill chuck in accordance with claim 1, in which the annular disc is connected to the sleeve by beading over the edge of the sleeve by a rolling operation.

3. A drill chuck in accordance with claim 1 or claim 2, in which the annular nut is divided into two semi-circular parts.

4. A drill chuck substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

5. A hand-held power drill including a drill chuck according to any preceding

Claims (1)

1. claim.