GB1575598A - Drill chuck - Google Patents

Description

(54) 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 state ment:- The present invention is concerned with drill chucks suitable for securing a tool, such as a drill bit, to a drilling machine.

Drill chucks are known which comprise a base member, a plurality of clamping jaws which are slidably guided in bores in the base member which are inclined to the axis of the chuck, and a ring nut rotatably mounted in an annular groove in the periphery of the base member, the ring nut being formed in two halves which are held together by a sleeve surrounding them and being internally screw threaded and engaging external screw threads on the clamping jaws whereby rotation of the ring nut and the sleeve serves to displace the clamping jaws longitudinally. In known drill chucks of this kind the sleeve is rigidly connected to the ring nut by flanging or shrinking-on, but these procedures are laborious and expensive.

We have now found that the sleeve in such a drill chuck can be rigidly connected to the ring nut in a simpler, safer and cheaper manner by causing radial compression of the sleeve by means of electromagnetic deformation.

According to the present invention, therefore, we provide a drill chuck of the kind referred to in which the sleeve is rigidly connected to the ring nut by radial compression of the sleeve by means of electromagnetic deformation.

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 a longitudinal section of a first embodiment of drill chuck, and Figures 2 to 4 are similar views of second, third and fourth embodiments of drill chuck, respectively.

Referring to Figure 1, the drill chuck consists of a substantially cylindrical base member 10 with a central bore 11 for receiving a tool, for example a drill bit. Clam- ping jaws (not shown) are slidingly guided in a plurality of inclinded bores 12 in the base member and serve to rigidly clamp the tool when tightened together. A transversely divided ring nut 13 is rotatably mounted in an annular groove in the periphery of the base member 10 and the halves of the ring nut 13 are held together by a sleeve 14. The ring nut 13 has an internal screw thread 131 which engages in external screw threads on the jaws whereby rotation of the ring nut 13 and the sleeve 14 effects longitudinal displacement of the jaws. The sleeve 14 is rigidly connected to the ring nut 13 by electromagnetic deformation of the former to effect radial compression. The sleeve extends completely over the axial length of the ring nut and its foot end is provided with bevelled teeth 15 which can be engaged by the teeth of a manually operated separate chuck key to effect rotation of the sleeve 14 and with it the ring nut 13. The sleeve 14 extends over the entire rear portion of the base member and sealingly encloses the latter.

The embodiment shown in Figure 2 differs from that shown in Figure 1 only in that the sleeve - now referenced 17 - only partially extends over the axial length of the ring nut -- referenced 18. The rigid interconnection between the two parts is effected in the same manner as previously described. The bevelled teeth -- referenced 19 are now formed on the foot end of the ring nut.

The embodiment shown in Figure 3 differs from that shown in Figure 1 only in that an annular groove 22 is formed on the periphery of the ring nut 21, into which a portion of the wall of the sleeve 14 is forced by electromagnetic deformation.

The embodiment shown in Figure 4 dif fers from that shown in Figure 2 in that an annular groove 25 is formed on the ring nut 24 into which is formed the end of the sleeve 26 by electromagnetic deformation.

The sleeve 14, 17 or 26 is preferably formed of steel, but may also be formed of aluminium. Increased resistance to wear of the sleeve may be obtained by generating a hard aluminium oxide layer. An aluminium sleeve can be strengthened by annular ribs and the like.

The sleeve can be additionally connected to the ring nut by welding or soldering WHAT WE CLAIM IS:- 1. A drill chuck comprising a base member, a plurality of clamping jaws which are slideably guided in bores in the base member which are inclined to the axis of the chuck, and a ring nut rotatably mounted in an annular groove in the periphery of the base member, the ring nut being formed in two halves which are held together by a sleeve surrounding them and being internally screw threaded and engaging external screw threads on the clamping jaws whereby rotation of the ring nut and sleeve serves to displace the clamping jaws longitudinally, in which the sleeve is rigidly connected to the ring nut by radial compression of the sleeve by means of electromagnetic deformation.

2. A drill chuck acording to claim 1, in which. the sleeve extends wholly over the axial length of the ring nut.

3. A drill chuck according to claim 1 or 2, in which the ring nut has a peripheral annular groove into which a portion of the sleeve is radially compressed.

4. A drill chuck according to any of claims 1 to 3, in which the sleeve is formed of aluminium or steel.

5. A drill chuck according to any of claims 1 to 4, in which the sleeve is additionally connected to the ring nut by welding or soldering.

6. A drill chuck according to any of claims 1 to 5, in which the tool end of the sleeve or the ring nut is provided with bevelled teeth suitable for engagement by the teeth of a separate chuck key.

7. A drill chuck substantially as herein described with reference to any of Figures 1 to 4 of the accompanying drawings.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. fers from that shown in Figure 2 in that an annular groove 25 is formed on the ring nut 24 into which is formed the end of the sleeve 26 by electromagnetic deformation. The sleeve 14, 17 or 26 is preferably formed of steel, but may also be formed of aluminium. Increased resistance to wear of the sleeve may be obtained by generating a hard aluminium oxide layer. An aluminium sleeve can be strengthened by annular ribs and the like. The sleeve can be additionally connected to the ring nut by welding or soldering WHAT WE CLAIM IS:-

1. A drill chuck comprising a base member, a plurality of clamping jaws which are slideably guided in bores in the base member which are inclined to the axis of the chuck, and a ring nut rotatably mounted in an annular groove in the periphery of the base member, the ring nut being formed in two halves which are held together by a sleeve surrounding them and being internally screw threaded and engaging external screw threads on the clamping jaws whereby rotation of the ring nut and sleeve serves to displace the clamping jaws longitudinally, in which the sleeve is rigidly connected to the ring nut by radial compression of the sleeve by means of electromagnetic deformation.

2. A drill chuck acording to claim 1, in which. the sleeve extends wholly over the axial length of the ring nut.

3. A drill chuck according to claim 1 or 2, in which the ring nut has a peripheral annular groove into which a portion of the sleeve is radially compressed.

4. A drill chuck according to any of claims 1 to 3, in which the sleeve is formed of aluminium or steel.

5. A drill chuck according to any of claims 1 to 4, in which the sleeve is additionally connected to the ring nut by welding or soldering.

6. A drill chuck according to any of claims 1 to 5, in which the tool end of the sleeve or the ring nut is provided with bevelled teeth suitable for engagement by the teeth of a separate chuck key.

7. A drill chuck substantially as herein described with reference to any of Figures 1 to 4 of the accompanying drawings.