GB2035156A - Chucks - Google Patents

Abstract

A drill chuck for percussion drilling and hammer drilling machines, ensures a clamping force acting on the drill after tightening the latter by locking the clamping sleeve with respect to the chuck base member. Within a threaded bore (23) the clamping sleeve (13) includes a counter-sunk clamping screw (22) in the form of an internally hexagonal screw, the radially inner end of which is forced directly against the cylindrical peripheral surface (24) of a base member (12) or alternatively through an intermediate portion (34; 44) located therebetween. The clamping screw (22) is secured and retained against being lost by caulking (25) of the outermost screw thread. It can be tightened by means of an hexagonal key (21) on the end of the handle (20) of the drill chuck key (15). <IMAGE>

Description

SPECIFICATION A chuck for hand tool machines, especially ring gear drill chucks State of the art The invention originates from a chuck for hand tool machines, especially ring gear drill chucks comprising, for example, three clamping jaws according to the type set forth in the main claim. Known drill chucks of this kind (DIN 6349) have the disadvantage that a clamped tool, especially a clamped drill, rigidly clamped in the chuck by means of a drill chuck key engaging the gear ring, can become loose in operation when using the hand tool machine in the intended manner due to the fact that the co-operating surfaces under clamping pressure during clamping lift off at least slightly whereby the original continuous direction of force originally provided by the clamping is interrupted.Such a loosening occurs, for example, due to the clamping jaws of the chuck biting into the shank of the tool.

Above all, when such a chuck is used for percussive drilling and hammer drilling machines, a loosening of the clamped tool is practically unavoidable and indeed due to the radial pulses then occurring during operation which are conducted from the percussion mechanism of the machine through the drill spindle to the base member of the chuck and thus to its clamping sleeve and gear ring.

Advantages of the invention As opposed to this, the chuck in accordance with the invention comprising the characterising features of the main claim has the advantage that the clamping sleeve can be secured with respect to the base member in the clamping position by means of the locking means. Thus, a security against loosening or even releasing of a tool clamped in the chuck is achieved with simple means wherein the locking action guarantees a reliable tool clamping even when the chuck is used in percussion drilling machines and which otherwise produce operational circumstances during percussion drilling causing release of the clamped tool, especially the clamping jaws biting into the tool shank, the occurence of radial pulses which originate from the hand tool machine, or the like.The chuck in accordance with the invention guarantees a double function and indeed clamping on the one hand and locking in the clamping position on the other hand. Otherwise, the chuck can, in the main, be constructed in the usual manner, thus it can consist of mass produced basic elements so that in addition the chuck in accordance with the invention is simple and particularly cheap.

Advantageous further developements and improvements of the chuck set forth in the main claim are made possible by the measures set forth in the sub-claims.

A preferable arrangement is produced from claim 2. Moreover, according to the design of the chuck, it can be equally advantageous when the clamping force between the clamping sleeve and the base member is effective in an axial direction or even in a radial direction.

A further advantageous embodiment is provided by claims 3 and 4. Forming the locking element of the locking means as a radial locking screw is particularly simple and cheap.

That guarantees a reliable safeguard of the clamping force.

Claims 5 to 9 include further advantageous embodiments. With an appropriate construction of the intermediate member, these arrangements lead to still greater securing force which can be applied by means of the clamping screw between the clamping sleeve on the one hand and the base member on the other hand.

Moreover, an arrangement according to claim 10 is of advantage. Such an internally hexagonal screw may be tightened with the same drill chuck key with which the tool is rigidly clamped by engagement with the gear ring insofar as the drill chuck key is provided with a corresponding hexagonal profile at the end of its handle. The clamping of the tool on the one hand and the securing of the clamping force by locking the clamping sleeve on the other hand is then made possible by a simple rearrangement of the drill chuck key with the minimum of additional expenditure in time. Firstly, by axially securing the internally hexagonal screw account is taken of a protection against accident since the automatic unscrewing of the internally hexagonal screw accompanied by a radial projection beyond the external peripheral surface of the clamping sleeve is thus effectively prevented.Secondly, the internally hexagonal screw is at the same time secured against loss during its life.

Drawing The invention is described in more detail in the following with the aid of the embodiments illustrated in the drawing. These show: Figure 1 a side view of a drill chuck provided with a gear ring partly in axial crosssection, Figure 2 a side view of a drill chuck key, Figure 3a diagrammatic radial section of a portion of a chuck base member with an intermediate portion and a radial clamping screw, in accordance with a second embodiment, Figure 4 a diagrammatic axial longitudinal section of a portion of a chuck base member with an intermediate portion and a radial clamping screw in accordance with a third embodiment.

Description of the embodiments A drill chuck 10 which is suitable for drill ing machines and above all also for percussion drilling and hammer drilling machines, which are not illustrated further, is shown diagrammatically in Fig. 1. The drill chuck 10 is constructed in the standard manner, for example according to DIN 6349, and is consequently provided with three clamping jaws 11 within a base member 12. A clamping sleeve 13, which carries a forward gear ring 14 at the left-hand end in Fig. 1, is mounted for rotation on the base member 12. By rotating the clamping sleeve 13 by means of the gear ring 14 the drill chuck 10 can be opened widely enough in the region of the clamping jaws 11 so that the shank of a tool (not shown) can be inserted therein. The drill chuck key 15 according to Fig. 2 is used for rigidly clamping the tool in the drill chuck 10.

The key has a cylindrical shank portion 16 on which is arranged teeth 17. During clamping, the teeth 17 engage positively in the gear ring 14 on the clamping sleeve 13. A pin 18 coaxial with respect to the teeth 17 is arranged at the end of the teeth 17 which are remote from the shank portion 16, for supporting the drill chuck key 15 in the drill chuck 10. For supporting the drill chuck key 15, the pin 18 engages in one of three associated receiving bores 19 in the base member 12 of the drill chuck 10.

At the end remote from the teeth 17, the shank portion 16 of the drill chuck key 15 carries a handle 20. At its free left-hand end in Fig. 2, the handle is provided with an hexagonal profile 21.

The drill chuck TO is provided with locking means which secures the clamping sleeve 1 3 in the particular clamping position with reference to the base member 12. The locking means have a radial clamping screw 22 which is formed as an internally hexagonal screw. A radially effective clamping force, which secures the clamping sleeve 13 in the clamping position, can be applied between the clamping sleeve 13 and the base member 12 by means of the clamping screw 22. The clamping screw 22 is arranged at that end of the clamping sleeve 13 which lies axially opposite to the gear ring. The clamping screw 22 is countersunk within a radial threaded bore 23 in the clamping sleeve 13 and which extends radially as far as the inner cylindrical peripheral surface 24 of the base member 12.

By tightening the clamping screw 22, the latter can be urged in a clamping manner directly against the peripheral surface 24 of the base member 12 acting as a clamping surface. To guard against automatic unscrewing or even loss of the clamping screw 22 from within the threaded bore 23, either the radially outermost thread of the threaded bore 23 is caulked, as shown in Fig. 1 at 25, or a spring ring, snap-ring or the like, is inserted radially externally in the threaded bore 23.

The internal hexagon in the clamping screw 22 corresponds to the hexagonal profile 21 on the drill chuck key 1 5 (Fig. 2). Thus, the latter serves, on the one hand, for rigidly clamping an inserted tool wherein the teeth 17 engage in the gear ring 14, and on the other hand also serves by a simple inversion as a tool for tightening the clamping screw 22. For this purpose, the hexagonal profile 21 on the handle 20 engages in the inner hexagon in the clamping screw 22 so that after rigidly clamping the tool, the clamping screw can also be so rigidly tightened that, due to the radial clamping force between the base member 12 and the clamping sleeve 13, the latter is thereby secured even against only slight rotation and accompanying loosening.

The second embodiment shown diagrammatically in Fig. 3, differs from the first embodiment according to Fig. 1 by the fact that, between the base member 32 and the clamping sleeve (not shown) at least over the peripheral region above which the clamping screw 33 is arranged, an intermediate portion 34 in the form of a slide block is located which, for example, is arranged within the clamping sleeve or even on the periphery of the base member 32. The intermediate portion 34 is influenced by clamping pressure from the radially inner end of the clamping screw 33 and in its turn can be forced against the said peripheral surface by way of an associated clamping surface 35 which, having regard to shape, matches the cylindrical peripheral surface of the base member 32.

The clamping surface 35 of the intermediate portion 34 is provided with surface roughening 36, for example a knurling, whereby the grip in the said region and with it the clamping force is increased still further.

The third embodiment illustrated in Fig. 4, differs from the second embodiment according to Fig. 3 by the fact that the intermediate portion 44 is formed as a clamping member somewhat wedge-shaped in cross-section engaging in an appropriately shaped recess 47 in the base member 42, wherein the tip of the wedge is directed radially inwards. Moreover, the said clamping member 44 is formed, for example, as a split ring and the recess 47 as an annular groove inside the base member 42 shaped to correspond to the cross-section of the ring. The annular intermediate portion 44 rests within the annular groove-like recess 47.

Also, with this embodiment, the intermediate portion 44 can be influenced by the clamping pressure from the radially inner end of the clamping screw 43. Under the effect of this clamping pressure, the wedge surfaces on the 'wedge-shaped intermediate portion 44 are pressed into the wedge-shaped recess 47.

Due to the wedging effect, an especially good secure clamping force is effected between the clamping sleeve on the one hand and the base member 42 on the other hand.

Claims (11)

1. A chuck for hand tool machines, especially a gear ring gear chuck comprising for example three clamping jaws, comprising a clamping sleeve and a forward gear ring rotatable on the base member, characterised by a locking means securing the clamping sleeve in the respective locking position with reference to the base member.

2. A chuck according to claim 1 characterised in that the locking means has a clamping element by means of which a clamping force effective axially, or in particular radially, can be applied between the clamping sleeve and the base member and that the clamping element is arranged at the end of the clamping sleeve and of the base member lying axially opposite to the gear ring.

3. A chuck according to claim 1 or 2 characterised in that the locking means has a radial clamping screw arranged countersunk within a radial threaded bore in the clamping sleeve which clamping screw can be forced radially in a clamping manner directly or indirectly against an inner clamping surface on the base member (12; 32; 42).

4. A chuck according to claim 3 characterised in that the radially inner end of the clamping screw can be urged directly against an inner clamping surface on the base member formed as a cylindrical peripheral surface.

5. A chuck according to one of claims 1 to 3 characterised in that an intermediate portion which can be influenced by the clamping pressure from the radially inner end of the clamping screw and in its turn can be urged by means of an associated clamping surface against the inner clamping surface on the base member is arranged between the base member and the clamping sleeve at least in the peripheral region above which the clamping screw is located.

6. A chuck according to claim 5 characterised in that the intermediate portion consists of a slide block within the clamping sleeve or on the base member.

7. A chuck according to claim 5 characterised in that the intermediate member is formed as a clamping member with a radially inwardly directed wedge tip somewhat wedgeshaped in cross-section engaging in a correspondingly shaped recess in the base member.

8. A chuck according to claim 7 characterised in that the wedge-shaped clamping member is formed particularly as a split ring which is retained within an annular groove in the base member formed with a corresponding cross-section.

9. A chuck according to one of claims 5 to 8 characterised in that the inner clamping surface of the base member and/or of the intermediate portion is provided with surface roughening, for example a knurling.

10. A chuck according to one of claims 3 to 9 characterised in that the clamping screw is formed as an internally hexagonal screw and is secured and retained against loss within the threaded bore by means of caulking of the radially outermost screw thread, or by means of an inserted spring ring or snap ring or the like.

11. A drill chuck substantially as herein described with reference to Figs. 1 and 2, Fig 3 or Fig. 4 of the accompanying drawings.