GB1575488A - Drill chuck - Google Patents

Description

(54) A DRILL CHUCK (71) We, ROBERT BOSCH GMBH., a German company of Postfach 50, 7000 Stuttgart 1, 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:- This invention is concerned with drill chucks for connecting drill bits or other tools to the spindle of a driving machine, particularly a hand-held drilling machine.

Drill chucks are known which comprise a base member, a plurality of clamping jaws which are slidably positioned in guides in the base member, which guides are inclined with respect to the axis of the chuck, and a ring nut which surrounds and is rotatably mounted on the base member and has an internal screw-thread which engages with external screw-threads on the clamping jaws whereby rotation of the ring nut in one sense causes the clamping jaws to be longitudinally displaced towards the tool end and closed together, while rotation in the other sense causes the clamping jaws to be longitudinally displaced towards the hand end and separated. In this specification, "tool end" means the end of the chuck in which the tool is inserted and "hand end" means the other end.

German OLS 2,613,134 describes a drill chuck of this kind in which the base member is formed as one part and has an annular groove for receiving the ring nut. In order to be able to insert the ring nut in the annular groove in the base member, the ring nut must be divided into two parts.

After inserting the two parts of the ring nut in the annular groove in the base member, a sleeve formed of sheet metal or a turned metal part is forced over the parts of the ring nut to hold them together. Due to this construction of the ring nut, the drill chuck is liable to be damaged by shocks. Thus when used in percussion drilling machines and rock-working drill hammers in which the drill chuck is subject to axial blows in addition to being rotated, the divided ring nut is inclined to lose the pressed on sleeve and the ring nut, and with it the drill chuck, falls to pieces.

We have now developed a drill chuck of the kind referred to in which the ring nut is formed in one piece and which is substantially less sensitive to percussive stresses than the drill chuck described in the said German specification.

According to the present invention, there is provided a drill chuck of the kind referred to in which the base member is formed in two parts which are rigidly joined together in a plane perpendicular to the chuck axis and the ring nut is formed in one piece.

The joining of the two parts of the base member can be made much more robust and acceptable (than the joining of the two parts of the ring nut in the chuck of the German specification) because the parts are more substantial. The parts of the Ibase member are preferably welded together, ad vantageously by electrical resistance welding. When the latter method is used, the welding point is preferably formed on at least one part of the base member as a raised annulus with an inverted V crosssection.

The ring nut preferably comprises an integral sleeve which covers the hand end of the clamping jaws.

In order that the invention may be more fully understood, preferred embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation, partly in longitudinal section, of a first embodiment of drill chuck, Figure 2 is a similar view of a second embodiment, Figure 3 is a similar view of a third embodiment, Figure 4 is an axial view of the hand end part of the base member of the chuck shown in any of Figures 1 to 3 before welding it to the tool end part of the base member, viewed in the direction of the arrow IV, and Figure 5 is a scrap section on line V-V of Figure 4.

The drill chuck of Figure 1 comprises a base member part 1 which has a co-axial bore 2 at the hand end provided with a screw-thread 3 for fixing the chuck on the spindle of a driving machine. At the hand end, the base member part 1 is formed as a cylinder 4 provided with a cylindrical recess 4' from which a conical portion 4" extends towards the tool end. In the conical portion 4", there are formed three half bores 5 which penetrate the cylindrical portion 4 as complete bores 5'. A sleeve 7 surrounds the part 1 and abuts against the cylindrical portion 4 thereof by means of an annular flange 6 perpendicular to the axis; the sleeve is pushed onto the part 1 in the direction of the arrow IV. At its tool end, the sleeve 7 has bevelled teeth 8 and it is internally screw-threaded to form a ring nut 9. A cylindrical base member part 10 is smaller in diameter and also shorter than the part 1. It has three semicylindrical bores 11 converging towards the tool end which are connected to one another inerntally by a central co-axial bore 11'. The part 10 is connected to the part 1 so that the bores 11 in the former are aligned with the semi-bores 5 in the latter.

An annular rib 13 which has an inverted V cross-section (see Figures 4 and 5) is provided on the tool end plane surface of the part 1 and serves to provide the necessary weld connecting surface for the electrical resistance welding used to join parts 1 and 10.

A clamping jaw 14 is guided in each of the semi-bores 5 and their extensions 11 and the jaws are formed at their tool ends so that they are in mutual contact at their tool end limit position. Externally the clamping jaws 14 are provided with a screwthread 15 in which the internal screwthread 9 on the sleeve 7 engages. A plurality of radial bores 16 are formed in the part 10 adjacent the bevelled teeth 8 on the sleeve 7, these radial bores serving for the reception of the pin of a chuck key (not shown), the bevelled -teeth of which can engage in the bevelled teeth 8 on the sleeve 7.

At its hand end, the part 1 has a radial wall 17. At the hand end, the sleeve 7 is extended so that it surrounds the space receiving the hand ends of the clamping jaws 14 and formed by the recess 4' in the part 1 and the radial wall 17.

The drill chuck is assembled by inserting the clamping jaws in the semi-bores in the part 1. The sleeve is then pushed over the part 1 so that the screw-thread on the sleeve engages the screw-thread on the clamping jaws. The part 10 is pushed over the clamping jaws so that the latter project through the semi-bores therein. The part 10 is then connected to the part 1 by electrical resistance welding. The sleeve is then protected against displacement towards the hand end by abutting against the annular flange 6 on the part 1 and is prevented from displacement towards the tool end by abutting against the part 10. By rotating the sleeve with respect to the base member, which is effected manually or by means of a chuck key pushed into one of the bores 16 and engaging the bevelled teeth 8, the clamping jaws are either displaced towards the tool end, where they close together, or towards the hand end, where they are separated.

The chuck shown in Figure 2 comprises a base member part 101 which has a conical portion 104" which extends from the recess 104' towards the tool end and in which are formed three semi-bores 105. A cylindrical portion 4 corresponding to that of the Figure 1 embodiment is not provided, nor is an annular surface corresponding to 6. In order to support the sleeve 107 at the hand end, the radial wall 117 on the part 101 at the hand end is provided with an abutment surface 117' facing the tool end and the hand end of the sleeve 107 is provided with a corresponding annular surface 107'. In other respects, this drill chuck corresponds constructionally to that of Figure 1. With this drill chuck, the sleeve is secured against displacement towards the tool end just like the chuck of Figure 1, by abutment against the part 110 but is secured against displacement towards the hand end by abutment of the annular surface 107' on the sleeve against the abutment surface 117' on the part 101.

A third embodiment of drill chuck is illustrated in Figure 3. With this arrangement also, the guides for the clamping jaws in the base member part 201 are formed as semi-bores 205 and an annular surface corresponding to 6 supporting the sleeve at the hand end is omitted. In order to reduce the use of material, a radial wall corresponding to 117 is not provided at the hand end of the part 201. Instead, an annular recess 201' is formed at the hand end of the main portion 201 in which an annular disc 218 is inserted. After the insertion of the annular disc 218, the material of the part 201 projecting towards the hand end is outwardly rolled or flanged so that a collar 201" of increased diameter is formed to retain the annuuar disc 218. At the hand end, the sleeve 207 is supported against the annular disc 218 by means of an annular surface 207' on the sleeve.

WHAT WE CLAIM IS: 1. A drill chuck comprising a drill chuck base member, a plurality of clamping jaws which are slidably positioned in guides in the base member, which guides are inclined with respect to the axis of the chuck, and a ring nut which surrounds and is rotatably mounted on the base member and has an internal screw-thread which engages with external screw-threads on the clamping jaws whereby rotation of the ring nut in one sense causes the clamping jaws to be longitudinally displaced towards the tool end and closed together, while rotation in the other sense causes the clamping jaws to be longitudinally displaced towards the hand end and separated, and in which the base member is formed in two parts which are rigidly joined together in a plane perpendicular to the chuck axis and the ring nut is formed in one piece.

2. A drill chuck according to claim 1, in which the parts of the base member are welded to one another.

3. A drill chuck according to claim 1 or 2, in which the parts of the base member are joined to one another by electrical resistance welding.

4. A drill chuck according to claim 3, in which the welding point is formed on at least one part of the base member as a raised annulus with an inverted V crosssection.

5. A drill chuck according to any of claims 1 to 4, in which the ring nut comprises an integral sleeve which covers the hand end of the clamping jaws.

6. A drill chuck according to claim 5, in which the hand end of the sleeve is guided by a flange on the base member.

7. A drill chuck according to claim 6, in which the hand end of the sleeve is axially supported by the flange on the base member.

8. A drill chuck according to claim 5, in which the hand end of the sleeve is supported by an annular disc fixed to the base member.

9. A drill chuck according to any of claims 1 to 8, in which the periphery of the tool end of the ring nut is provided with bevelled teeth for co-operation with a separate chuck key.

10. A drill chuck substantially as herein described with reference to Figure 1, 2 or 3 or any of said Figures in combination with Figures 4 and 5 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. 201" of increased diameter is formed to retain the annuuar disc 218. At the hand end, the sleeve 207 is supported against the annular disc 218 by means of an annular surface 207' on the sleeve. WHAT WE CLAIM IS:

1. A drill chuck comprising a drill chuck base member, a plurality of clamping jaws which are slidably positioned in guides in the base member, which guides are inclined with respect to the axis of the chuck, and a ring nut which surrounds and is rotatably mounted on the base member and has an internal screw-thread which engages with external screw-threads on the clamping jaws whereby rotation of the ring nut in one sense causes the clamping jaws to be longitudinally displaced towards the tool end and closed together, while rotation in the other sense causes the clamping jaws to be longitudinally displaced towards the hand end and separated, and in which the base member is formed in two parts which are rigidly joined together in a plane perpendicular to the chuck axis and the ring nut is formed in one piece.

2. A drill chuck according to claim 1, in which the parts of the base member are welded to one another.

3. A drill chuck according to claim 1 or 2, in which the parts of the base member are joined to one another by electrical resistance welding.

4. A drill chuck according to claim 3, in which the welding point is formed on at least one part of the base member as a raised annulus with an inverted V crosssection.

5. A drill chuck according to any of claims 1 to 4, in which the ring nut comprises an integral sleeve which covers the hand end of the clamping jaws.

6. A drill chuck according to claim 5, in which the hand end of the sleeve is guided by a flange on the base member.

7. A drill chuck according to claim 6, in which the hand end of the sleeve is axially supported by the flange on the base member.

8. A drill chuck according to claim 5, in which the hand end of the sleeve is supported by an annular disc fixed to the base member.

9. A drill chuck according to any of claims 1 to 8, in which the periphery of the tool end of the ring nut is provided with bevelled teeth for co-operation with a separate chuck key.

10. A drill chuck substantially as herein described with reference to Figure 1, 2 or 3 or any of said Figures in combination with Figures 4 and 5 of the accompanying drawings.