GB2030485A - Impact drill chucks - Google Patents

Abstract

A chuck comprises clamping jaws (28-31) provided with longitudinal cams (40-43) which may engage a smooth cylindrical drill shank or provide torque transmitting engagement with axial clearance in a longitudinally grooved (13, 14, 16) drill shank (15). The chuck body has a splined socket (21) receiving a splined drive shaft (18) to allow relative axial movement during impact drilling whereby movement is limited by a stop element (52) which extends into an annular recess (50) of the drive shaft. The element (52) is releasably retained in the recess (50) by a spring loaded rotary sleeve (57) and the jaws are moved along inclined guides in the chuck body between operative and retracted positions by screw-threaded engagement with a ring unit (33, 34) keyed to the sleeve and rotatable thereby. <IMAGE>

Description

SPECIFICATION A chuck for hand tool machines especially drill and/or percussion hammers State oftheArt The invention originates from a chuck for hand tool machines, especially for drill and/or percussion hammers according to the type set forth in the main claim. Drilling machine chucks are known which are only suitable for clamping cylindrical tool shafts and are fixed components of the machines. On the other hand, tool holders on the end of the machine, of a special kind, chiefly for drill and percussion hammers, are known and which for the transmission of the torque have two inner teeth in the tool holder arranged at the same angular distance from each other in the peripheral direction. Each tooth engages in an associated longitudinal groove of substantially the same form which is provided in the tool shaft and is open towards the end of the tool shaft.To permit axial movement of the tool with simultaneous axial locking, two balls which engage in associated longitudinal grooves in the tool shaft, are provided in the tool holder, for example, arranged at the same angular distances from each other in the peripheral direction and retained, guided and radially movable in radial bores. At both axial ends, the longitudinal grooves have sphericaliy formed abutment surfaces. According to the lengths of these longitudinal grooves and the position of the balls engaging therein, the tool can perform a forward axial movement over a path, for example, between substantially 2 and 6 mm.Thus, the tool shaft is designed exactly in accordance with the construction of the tool holder on the end of the machine; Thus, without exception, tools are acceptable in the tool holder which fit therein thus, for example, no tool with a completely smooth cylindrical shaft. This is of considerable disadvantage since, when the user of the machine has available a machine of a particular manufacture and type, for example with a tool holder as previously described, then, for the user, there is a considerable need to use, together with the said machine, not only the special tools which fit therein but tools designed in other ways.

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 following advantages. On the one hand, it permits the reception of tools with recessed longitudinal grooves which are specially adaoted to the tool holder on the end of the machine.

In addition, the longitudinal cams on the clamping jaws each engage in a respective associated longitudinal groove wherein, for example, with four longitudinal grooves on the tool, four clamping jaws and thus four longitudinal cams are provided of which two longitudinal cams engage in the longitudinal grooves on the tool shaft provided for the purpose for torque transmission, whereas the two other longitudinal cams engage in those longitudinal grooves in the tool shaft which serve to provide for axial displacement of the tool with simultaneous axial locking of the tool againstfalling out. Thus, the latter are those longitudinal grooves which, on direct insertion into the machine tool holder, cooperate therein with the balls referred to above.The tool received in that manner in the chuck in the form of a supplementary unit, thus remains movable in an axial direction. Axial impacts generated by the machine can act from the receiving shaft of the chuck directly on the tool shaft wherein the chuck body and the other parts of the chuck must not move in a axial direction therewith. Thus, a direct transmission of the percussive energy results without any marked loss. The torque is transmitted to the tool shaft from the rotated receiving shaft through the chuck body and its clamping jaws provided with longitudinal cams. Instead of the desired tools provided with longitudinal grooves in the shaft, such other shaft formations can also be accepted in the chuck and be clamped therein, especially tools with smooth cylindrical shafts, which are then rigidly clamped in the chuck frictionally.For this purpose, the cam surfaces on all the longitudinal cams extending radially with respect to the receiving bore radially engage the cylindrical shaft like normal clamping jaws and rigidly clamp the shaft frictionally in axial and peripheral directions.

Advantageous further developments and improvements of the chuck set forth in the main claim are made possible by the measures set forth in the sub-claims 2to 20. In order to avoid unecessary repetition, the full wording of these claims is not reproduced but instead, reference is made to them simply by citing the claim number wherein, however, all these claims' features are to be considered as disclosed expressly and in accordance with the essentials of the invention in that passage.

Drawing The invention is described in greater detail by way of example in the following with the aid of an embodiment of a chuck for hand tool machines illustrated in the drawing. This shows: Figure 1 a diagrammatic longitudinal section through the chuck at least partially along the line I-I in Figure 2a, Figure2a is a section along the line Il-Il in Figure 1, Figure 26 is a section of the cross-section according to Figure 2a enlarged many times, Figure 3 and 4 are respective sections along the lines Ill-Ill- and IV-IV in Figure 1.

Description of the embodiment The illustrated chuck 10 is intended especially for drill and/or percussion hammers and is indeed for the torque transmitting reception of a tool inserted therein in the form of the illustrated drill 11 or of the other kind of drill 12 simply illustrated in dotted lines in Figure 2b.

Drill and/or percussion hammers of many kinds are known and each is provided with a specially designed tool holder according to its manufacture, which requires a specially associated design of tool shaft for the reception of the tool. One type of aplicant's tool holder on the machine has means not only for entraining rotation but also fr axial displace ment with simultaneous axial locking of the drill 11.

Moreover the means for entraining rotation consist of, for example, two inner longitudinal teeth on the tool holder arranged in the peripheral direction at the same angular distance from each other and which engage in respective associated longitudinal grooves 13 and 14 in the shaft 15 of the drill 11 for entraining rotation. In cross-section, these longitudinal grooves 13 and 14 are substantially trapezoidal and are open towards the righthand end of the shaft 15 in Figure 1.

The means (not shown) for axial displacement with simultaneous axial locking of the drill 11 consist of, for example, two balls, which serve the purpose of locking members, radially movably retained in radial bores in the tool holder and at the same angular distance from each other in the peripheral direction. These balls engage in associated longitudinal grooves 16 and 17 which are likewise provided in the shaft 15 of the drill 11. The longitudinal grooves 16 and 17 are arcuate in cross-section and have radial abutment surfaces at both axial ends.

The result is that, according to the length of the said longitudinal grooves 16 and 17 and the position of the balls on the machine engaging therein, the drill 11 can perform a predetermined axial path of movement which is necessary during percussion drilling for the axial percussive influence on the drill 11 together with an overlapping rotary drive.

Thus, the illustrated drill 11 with the shaft 15 and the longitudinal grooves 13, 14 and 16 and 17 therein is designed in the usual manner. It is made suitable for the described construction of tool holder in the applicant's known machines so that it can be received therein.

Due to this special fitting of the drill 11 to the tool holder on the machine, drills of other design, for example the drill 12 of Figure 2b with a completely non-grooved cylindrical shaft 2, may not be received in the tool holder. This applies also to drills of other design, for example of other firms. However, when using drill and/or percussion hammers in accordance with regulations, there is a compelling need for the userto be able to introduce tools with different shafts into a machine of one type and manufacture and thus not to be bound to particular types of machne manufactures having regard to the use of the tools.

To this end, the chuck 10 is designed as an additional unit which can be connected to the tool holder on the machine to transmit torque to and transmit simultaneously the axial persussive energy, by means of a receiving shaft 18 which can be received in the tool holder. The chuck 10 has a chuck body 19 with a central receiving bore 20 for the shaft 15 of the tool 11 and in the same manner also for the shaft 2 of the other tool 12 (Figure 2b). The receiving shaft 18 engages rotationally in the chuck body 19, however, with the possibility of relative axial movement. Forthat purpose, the chuck body 19 has a plug-in receiver 21 coaxial to the receiving bore 20 with internal torque transmitting elements in the form of teeth 22. Over its section engaging in the plug-in receiver 21, the receiving shaft 18 carries associated transmitting elements, likewise in the form of teeth 23.Thus, the teeth 22 and 23 engage in one another like a splined connection whereby the rotary drive on the one hand and the relative movability between the chuck body 19 and the receiving shaft 18 on the other hand is guaranteed.

An axial locking is effective between the two which limits the relative path of movement in Figure 1 towards the left and towards the right and is explained in detail later on.

The chuck body 19 has four guides 24 - 27 extending substantially as splines with respect to the receiving bore 20 arranged in the peripheral direction at substantially equal angular distances from one another of 900. An associated clamping jaw 28 31 is displaceably retained and supported in each guide 24 - 27. Moreover, each clamping jaw 28 - 31 projects, by way of its portion directed radially towards the receiving bore 20, into the receiving bore 20. On their outer surfaces, the clamping jaws 28 - 31 are provided with screwthreads in the usual manner as can be seen at 32 in the clamping jaw 28 in Figure 1. Moreover, all four clamping jaws 28 - 31 are surrounded by a ring which, for example, consists of two semicircular ring segments 33 and 34 for manufacturing reasons and is assembled.The ring segments 33,34 carry a conical screwthread 35 which is in engagement with the screwthread 32 on the clamping jaw 28 and with the screwthreads of all the other clamping jaws 29 - 31, so that rotation of the ring segments 33,34 as a ring unit without axial displacement leads to screwing in or screwing out of the four clamping jaws 28 - 31.

The ring segments 33, 34 are rigidly connected to a clamping ring 36 which surrounds them. The connection is produced, for example, by press-fitting.

The clamping ring 36 is rotatably mounted on the other peripheral surface 37 of the chuck body 19 and is axially non-displaceable, however, due to the rigid connection with the ring segments 33, 34 rotatable in their turn. On the left-hand end surface in Figure 1, the clamping ring 36 is provided in the usual manner with a conical set of teeth 38 and can be rotated by rotation of the key for the clamping ring 38.

Each of the clamping jaws 28 - 31 carries an embossed longitudinal cam 40 - 43 projecting radially away from the receiving bore 20 and extending substantially parallel thereto. With their respective axially parallel inner cam surfaces 44 - 47 (Figure 2b) the longitudinal cams each form a clamping surface for the frictional rigid clamping of an inserted drill 12 provided with an exclusive cylindrical shaft 2 (Figure 2b in dotted lines) in an axial and peripheral direction. Thus, a drill 12 with an exclusive cylindrical shaft 2 can be clamped in the chuck 10 and indeed in a normal manner by means of a drill chuck key as is previously described.

Each longitudinal cam 40 - 43 is somewhat slightly trapezoidal viewed in an axial direction and made to extend trapezoidally viewed in cross-section (Figures 2a, 2b) whereby the respective cam surfaces 44 - 47 proceed flat, in a straight line and axially parallel. Moreover, the trapezoidal shape of each longitudinal cam 40 - 43 matches in cross-section the shape and dimensions of the trapezoidal shape of the recessed longitudinal grooves 13 and 14 in the shaft 15 of the other drill 11 which-are open in an axial direction towards the right-hand end of the shaft in Figure 1. All the longitudinal cams 40 - 43 are made the same.

As Figure 2a shows, the clamping jaws 28 - 31 each have a back contour at their back supported in the respective associated guides 24 - 27 in the chuck body 19 and the respective guides 24 - 27 also have a back contour in a corresponding manner viewed in cross-section, the back contour following substantially the curvature of a circular segment of preferably substantially 180' circumferential angle.

It is of special importance that the radial overhang and also the axial length of each longitudinal cam 40 - 43 are matched to the recessed longitudinal grooves 13, 14 and 16, 17 arranged on the shaft 15 of the drill 11 at the same angular distances in the peripheral direction as the longitudinal-cams 40 - 43, in such a manner that, with the tool 11 inserted, each longitudinal cam 40 - 43 engages in an associated longitudinal groove in a positive and torquetransmitting mannerwhilstallowing, however, relative axial movement, simultaneous axial security against falling out and restriction of the path of movement. The diametrically opposite longitudinal cams 41 and 43 engage a respective longitudinal groove 14 or 13, trapezoidal in cross-section and open towards the right in Figure 1, substantially completely clearance-free in the peripheral direction.

The other diametrically opposite longitudinal cams 40 and 42 engage in the associated longitudinal grooves 16 and 17 respectively without, however, coming into contact therewith in the peripheral direction and in the radial direction (Figure 2b). Thus, the drill 11, which in this form likewise fits well into the tool holder on the machine (not shown) is likewise received in the chuck 10 in such a manner that it is coupled to the latter for torque transmission but is axially displaceable relatively thereto.

If it is desired to receive the drill 12 with exclusive cylindrical shaft 2 in the chuck 10 instead of the drill 11, this is also possible as Figure 2b shows. The drill 12 is then rigidly clamped in its cylindrical shaft 2 frictionally in an axial and peripheral direction by the cam surfaces 44 - 47 on the longitudinal cams 40 - 43.

The axial locking between the receiving shaft 18 and the chuck body 19 is so maintained and matched to the other parts of the chuck 10 that the end 48 of the inserted tool shaft 15 is axially percussively influenceable from the remote e 7d 49 of the receiving shaft 18 and the receiving shaft 18 and the drill 11 can be reciprocated together relatively to the chuck body 19 up to their particular axial abutment. On the one hand, the axial locking is formed by an annular groove 50 in the receiving shaft-18 and on the other hand by an end 51 of a roller element 52 engaging in the receiving shaft 18 and which is mounted radially in the chuck body 19, for example rotatable, and the end 51 of which extends into the annular groove 50 and the other end 53 of which projects beyond the peripheral surface 37 of the chuck body 19.In the region which is directly adjacent to the rear end surface 54 (to the right of Figure 1) of the chuck body 19, the receiving shaft 18 carries a rubber elastic damping and abutment ring 55 anda reinforcing and dust protecting cap 56 overlapping the latter. On the axial side which is directed towards the rear end surface 54 of the chuck body 19, the dust cap forms, together with the chuck body, an axial abutment for restricting the insert movement of the receiving shaft 18 into the insert receiver 21. In the condition according to Figure 1, this axial abutment has just been reached. The receiving shaft 18 cannot penetrate any deeper into the insert receiver 21.With a return movement in the opposite sense with respect to the insert movement relatively between the receiving shaft 18 and the chuck body 19, restriction of the axial movement is produced by the left-hand axial end of the anular groove 50 in Figure 1 abutting against the shoulder-like abutment surface on the end 51 of the roller element 52.

In other respects, the receiving shaft 18 is formed as a substantially straight, stepless cylindrical rod of substantially uniform diameter over its entire length which leads to the most loss-free transmission of the percussive energy through the receiving shaft 18 directly on the drill 11, from the point of view of shock wave theory. Moreover, the chuck body 10 together with all the other parts is not moved, at least as a rule. Moreover, it remains in an axial position as a result of inertia. The rotary driving movement additionally transmitted through the receiving shaft 18 is transmitted to the chuck body 19 and from the latter through the guides 25, 27, the clamping jaws 29,31, their longitudinal cams 41,43 and the longitudinal grooves 14 and 13 on the drill to the drill 11 itself.Limitation of the axial reciprocating movement of the drill 11 in the axial direction takes place through the longitudinal cams 40 and 42 which engage in the associated longitudinal grooves 16 and 17. Since the transmission of the reaction torque takes place from the drill 11 through the clamping jaws 29 and 31 directly on the guides 25 and 27 and thus on the chuck body 19, no self-releasing force acts on the screwthread 32 and the conical screwthread 35 with the danger of a possible release, with the drill 11 held in the chuck 10 (Figure 1). Such a danger only exists on the ground of possible chattering and then chiefly when the drill 12 with the continuous cylindrical shaft 2 (dotted lines in Figure 2b) is clamped instead of the drill 11.In order to avoid the danger of a release, a special securing device is provided which secures the clamping ring 36 together with the ring segments 33, 34 positively and/or frictionally against release with respect to the chuck body 19.

A component of the securing device is a rotary sleeve 57. This overlaps the clamping ring 36 and the peripheral surface 37 of the chuck body 19 on which it is rotatably mounted together with the clamping 36. These produce a longitudinal slot 58 at the left-hand end of the rotary sleeve 57 in Figure 1 on the one hand and, on the other hand, a radial pin 59 which is mounted on the clamping ring 36 engaging in the longitudinal slot 58.By means of this coupling, the rotary sleeve 57 is connected for rotation with the clamping ring 36 but is axially displaceable with respect to the latter; Thus rotation, of the rotary sleeve 57 leads to a rotation of the clamping ring 36 together with the ring segments 33, 34 and to the screwing in and screwing out of the clamping jaws 28 - 31 without a drill chuck key being required for that purpose which is then only necessary when a drill 12 (Figure 2b) with an exclusive cylindrical shaft 2 is to be rigidly clamped by friction.

The rotary sleeve 57 is frictionally and/or positively coupled to the chuck body 19 by a spring loaded locking device. The locking device has a radial locking pin in the chuck body 19 which is formed by the radially projecting end 53 of the roller element 52. Furthermore, a component of the locking device is an axial locking surface 60 on the rotary sleeve 57 which comprises a locking recess 61 recessed axially towards the left in Figures 1 and 4 receiving the end 53 of the roller element 52 in the illustrated locking position. Furthermore, the locking device comprises a locking spring 62 by means of which the rotary sleeve 57 is forced in an axial direction (towards the right in Figures 1 and 4) together with its locking surface 60 and in the locking position, with its locking recess 61 against the end 53 of the roller element 52.The locking surface 60 with the locking recess 61 is located at the end of the rotary sleeve 57 which is remote from the longitudinal slot 58 and is facing the receiving shaft 18. The rotary sleeve 57 overlaps the peripheral surface 37 of the chuck body 19 whilst forming an annular space 63 therebetween in which is arranged the locking spring 67 formed as a cylindrical helical spring. One end of the latter is supported on a shoulder on the clamping rings 36 and the opposite end on a shoulder on the rotary sleeve 57. The locking surface 60 on the rotary sleeve 57 is formed by the annular shoulder of an annular recess 64 which is machined in the rotary sleeve 57 at the end facing the receiving shaft 18. Moreover, the locking recess 61 is formed by an axial somewhat triangular depression in the said annular shoulder of the annular recess 64 directed towards the clamping ring 36.Figure 4 shows the triangular shape. The two wall surfaces 65,66 of the locking recess 61 extend at substantially an angle of 90 to one another with a rounding at the base. Each wall surface 65,66 is set at substantially an angle of 45 inclined with respect to the circulating annular shoulder.

As can be seen chiefly from Figures 1 and 2b (dotted therein) each of the clamping jaws 28 - 31 has a cut-out elongate section with inner axially parallel supporting surfaces 67 - 70 of circular segmental shape in cross-section at the portion in front of the longitudinal cams 40 - 43 in the insert direction of the drill 11 or 12, thus on the left in Figure 1.With a drjll 11 having longitudinal grooves 13, 14 and 16, 17 inserted these supporting surfaces 67 - 70 guide its shaft 15 along the cylindrical surface in front of the longitudinal grooves 13,14and 16,17 and support the shaft 15 in a radial direction and thus against bending. This applies, for example to a drill 1 having a 10 mm shaft diameter.

The method of operation with a drill 11 according to Figure 1 inserted in the chuck 10 has already been described. If the drill 11 is to be removed from the chuck 10, then an axial movement of the rotary sleeve 57 in Figure 1 towards the left against the action of the locking spring 62 is sufficient for that purpose, whereby the locking recess 61 arrives out of axial engagement with the end 53 of the roller element 52. If, in this unlocked position, the rotary sleeve 57 is held against the action of the spring and rotated in the direction which results in opening of the locking jaws 28 to 31, then the longitudinal cams 40 and 42 in accordance with a corresponding displacement in their guides 24 and 26, finally release the drill 11 in an axial direction for removal.

It is, of course, to be understood that by rotating the rotary sleeve 57 and a corresponding rotation of the clamping ring 36 together with the ring segments 33,34, all four clamping jaws 28 to 31 are simultaneously influenced and in Figure 1 are shifted towards the right in their guides 24 - 27. Moreover, only the longitudinal cams 40 and 42 which engage in an axially locking manner in the longitudinal grooves 16 and 17 ofthe drill 11, are decisive for releasing the drill 11 in an axial direction.

Then, a new drill 11 of the same design can be inserted. After insertion, the rotary sleeve 57 is rotated in the opposite sense, for example by hand, whereupon the clamping ring 36 and through this all four clamping jaws 28 - 31 are actuated in a clamping direction. If the drill 11 together with its shaft 15 is not so introduced in a peripheral direction that the longitudinal cams 40 - 43 can engage in the longitudinal grooves 13, 14 and 16, 17 then a slight rotation of the drill 11 in a peripheral direction is sufficient until that is achieved. A further rotation of the rotary sleeve 57, for example by hand, finally leads to the longitudinal cams 41,43 engaging in the longitudinal grooves 14 and 13 in the proper manner and also deep enough whilst allowing a clearance for axial displacement.Moreover, the rotary sleeve 57 need not be in any way held by hand out of the locking position against the action of the locking spring 62.

Rotary actuation of the rotary sleeve 57 is simply sufficient with an increased rotary grip when the locking recess 61 in the rotary sleeve 57 receives the end 53 of the roller element 52 on reaching the locking position which occurs once every revolution.

At a predetermined rotary position of the rotary sleeve 57 and thus at a predetermined radial position of the longitudinal cams 40 - 43 on the clamping jaws 28 - 31, the end 53 locks in the locking recess 61 and indeed when the locking cams 40 - 43 have entered sufficiently deeply into the longitudinal grooves 13, 14 and 16, 17 in the shaft 15, however whilst allowing the said clearance, so that the drill 11 remains axially movable. Acceptance of the drill 11 is then terminated. The latter is then guided on thecylindrical surface of its shaft 15 additionally by the supporting surfaces 67 - 70 on the clamping jaws 28 31 and is supported against bending. A drill chuck key need not be used.

Since, as already described above, the reaction torque from the drill 11 is not transmitted through the screwthread 32 and the conical screwthread 35 but much more throught the clamping jaws to their guide and to the chuck body 19, the result is no self-releasing or unlocking force which is transmitted to the clamping ring 36 and the rotary sleeve 57.

Possible chattering which could effect rotation of the rotary sleeve 57 and with it rotation of the clamping ring 36, is not sufficient to move the rotary sleeve 57 out of the locking position illustrated in Figure 4 in which the end 53 of the roller element 52 engages in the locking recess 61 and the rotary sleeve 57 is forced against the roller element 52 by the action of the locking spring 62. Should chattering upset the contact between the locking recess 61 and the end 53, then the locking spring 62 acts against that effect.

It ensures that the locking position according to Figure 4 is always restored. The torque required for overriding the said locking position is considerably greater than the maximum occurring with chattering during operation.

If, instead of the drill 11, it is desired to clamp another drill 12 with an exclusive cylindrical shaft 2 (dotted in Figure 2b) in the chuck 10, this takes place in the normal manner. The drill 12 is inserted with its cylindrical shaft 2. Then a chuck key of the usual kind is used and the clamping ring 36 is rotated therewith.

Simultaneously with the rotation of the clamping ring 36, the rotary sleeve 57 is also rotated and indeed as a result of the radial pin 59 which engages in the longitudinal slot 58. In so doing the rotary sleeve 57 is not gripped. Moreover, the locking position of the rotary sleeve 57 illustrated in Figure 4 is overridden and indeed at a predetermined torque which is determined by the angular position of the wall surfaces 65,66 of the locking recess 61. As a result of the lever action through the drill chuck key, the override torque is negligibly low in comparison to the starting torque of the drill 12 with a cylindrical shaft 2 so that, during clamping of the cylindrical shaft 2, the locking position according to Figure 4 can be very slightly overridden simply by rotation of the drill chuck key. The latter is rotated until the cam surfaces 44 - 47 on the longitudinal cams 40 - 43 engage the cylindrical shaft 2 of the drill 12 and rigidly clamp the shaft by friction due to further tightening of the drill chuck key. It is to be understood that the cam surfaces 44 - 47 can be provided for example with additional surface roughness, for example transverse ribs, for this purpose of having regard to the surface shape can be still better matched to that of the cylindrical shaft 2.

Claims (21)

1. A chuck for hand tool machines, especially drill and/or percussion hammers, for the torque transmitting reception of tools to be inserted having a substantially cylindrical tool shaft, comprising a chuck body with a central receiving bore for the tool shaft and a plurality of clamping jaws projecting into the receiving bore, at substantially the same angular distance from one another in the peripheral direc tion, displaceable and supported in guides extend ing conically towards the receiving bore, the clamp ing jaws being provided on their outer surfaces with screwthreads and being surrounded by ring portions which carry a conical screwthread in engagement with the screwthreads on all the clamping jaws and are rigidly connected to a clamping ring surrounding them, non-displaceable but rotatable on the outer peripheral surface of the chuck body and through the rotary actuation of which the clamping jaws are displaceable together in their guides and can be screwed into the receiving bore and screwed out of the latter with a torque transmitting grip or release of the tool shaft of an inserted tool, characterised by the formation in the form of an additional unit which can be connected for torque transmission to the tool holder of the hand tool machine through a receiving shaft engaging the chuck body for rotation but preferablywith relative axial displacement and in that the respective clamping jaws carry embossed longitudinal cams extending radially with respect to and projecting away from the receiving bore and extending substantially parallel thereto, and which, with their axially parallel inner cam surfaces form a respective clamping surface for the frictional rigid clamping in an axial and peripheral direction of an inserted tool provided with an exclusive cylindrical shaft and the respective degree of radial projection of which and respective axial length are so matched to a tool shaft with recessed longitudinal grooves arranged in the peripheral direction at the same angular distances as the clamping jaws with the longitudinal cams that, with a tool of that kind inserted, at least one of the longitudinal cams positively engages and in a torque transmitting manner in a longitudinal groove, whilst allowing relative axial displacement with simultaneous axial security against falling out and restriction of the displacement path.

2. A chuck according to claim 1 characterised in that, the chuck body has a plug- in receiver coaxial with respect to the receiving bore and provided with inner torque transmitting elements especially longitudinal recesses and/or longitudinal webs, that the receiving shaft has associated transmission eie- ments, especially longitudinal webs for longitudinal recesses, and engages in the plug-in receiver relatively displaceable thereto by mutual engagement of the elements and the transmitting elements and that an axial locking effective between the chuck body and the receiving shaft is provided and which so restricts the relative displacement path whilst matching that of an inserted tool provided with recessed longitudinal grooves that the end of the tool shaft is axially percussively influenceable by the facing end of the receiving shaft and the receiving shaft and the tool are together reciprocably displaceable relatively to the chuck body over a somewhat equal displacement path up to their respective axial abutment.

3. A chuck according to claim 2 characterised in that, the axial locking is formed, on the one hand, by a longitudinal trough, for example an annular groove, in the receiving shaft and on the other hand, by an axial pin engaging in the longitudinal trough, especially by a roller element on the chuck body projecting, on the one hand, into the plug-in receiver and on the other hand, radially beyond the outer peripheral surface.

4. A chuck according to one of claims 1 to 13 characterised in that, in the region directly adjacent to the rear end surface of the chuck body, the receiving shaft carries a rubber elastic damping and abutment ring and a reinforcing and dust protection cap overlapping the ring, the dust protective cap forming on its end directed towards the rear end surface of the chuck body together with the latter, an axial abutment for restricting the degree of movement of the receiving shaft into the plug-in receiver.

5. A chuck according to one of claims 1 to 4 characterised in that, the receiving shaft is designed as a cylindrical rod substantially completely straight, radially stepless and having a substantially uniform diameter over its entire length.

6. A chuck according to one of claims 1 to 5 characterised by a safety device frictionally and/or positively secured against release of the clamping ring together with the ring portions with respect to the chuck body.

7. A chuck according to claim 6 characterised in that the safety device has a rotary sleeve which in its turn is supported frictionally and/or positively with reference to the chuck body, which overlaps the clamping ring and the outer peripheral surface of the chuck body and is rotatably mounted thereon together with the clamping ring.

8. A chuck according to claim 7 characterised in that the rotary sleeve is coupled to the clamping ring in a peripheral direction through a longitudinal slot on one part, especially the rotary sleeve, and a radial pin engaging in the longitudinal slot on the other part, especially the clamping ring, and is relatively longitudinally movable with respect to the clamping ring.

9. A chuck according to claim 7 or 8 characterised in that the rotary sleeve is coupled to the chuck body by means of a preferably spring loaded locking device.

10. A chuck according to claim 9 characterised in that the locking device has a radial locking pin on the chuck body and an axial locking surface with an axial recessed locking recess on the rotary sleeve receiving the locking pin in the locking position as well as a locking spring, by means of which the rotary sleeve is forced against the locking pin in an axial direction with its locking surface and in the locking position with its locking recess.

11. A chuck according to claims 3 and 10 characterised in that the locking pin is formed by the radially projecting end section of the roller elment and the roller element is mounted in the chuck body for rotation preferably about its longitudinal central axis.

12. A chuck according to one of claims 8 to 11 characterised in that the longitudinal slot is arranged on the end of the rotary sleeve remote from the receiving shaft and the axial locking surface together with the locking recess is mounted on the end of the rotary sleeve facing the receiving shaft.

A chuck according to one of claims 7 to 12 characterised in that the rotary sleeve overlaps the outer peripheral surface of the chuck body whilst forming an annular space therebetween, within which is arranged a cylindrical helical spring in the form of a locking spring one axial end of which is supported against a shoulder on the clamping ring and the opposite end of which is supported on a shoulder on the rotary sleeve.

14. A chuck according to one of claims 10 to 13 characterised in that the axial locking surface on the rotary sleeve is formed by the annular shoulder of an annular recess on the end of the rotary sleeve directed towards the receiving shaft and the recessed locking recess is formed by a substantially triangular depression in the annular shoulder directed axially towards the clamping ring.

15. A chuck according to claim 14 characterised in that the wall surfaces of the depression together form an angle of about 9048 and are each set with respect to the circulating annular shoulder inclined at an angle of about 45 .

16. A chuck according to one of claims 1 to 15 characterised in that, at the part in front of the longitudinal cams in the plug-in direction of the tool each of the clampingsjaws has a pressed out longitudinal section with inner axially parallel supporting surfaces, segments of a circle in crosssection, which, with a tool provided with longitudinal grooves in its shaft, guides the tool on its cyclindrical surface axially in front of the longitudinal grooves and spports it in radial direction, preferably when a tool with a 10 mm shaft diameter is inserted.

17. A chuck according to one of claims 1 to 16 characterised in that the longitudinal cams on each of the clamping jaws is made somewhat slightly trapezoidal in an axial direction and is made trapezoidal in cross-section, preferably with flat, straight axially parallely extending inner cam surfaces.

18. A chuck according to claim 17 characterised in that the trapezoidal shape of each of the longitudinal cams is matched in cross-section with respect of its shape and dimensions to those recessed longitudinal grooves on the shaft of the tool of an inserted tool which are open in an axial direction towards the end of the shaft.

19. A chuck according to one of claims 1 to 18 characterised in that four grouped locking jaws each with the same kind of longitudinal cams are provided, at an angular distance of about 90 from one another in a peripheral direction.

20. A chuck according to one of claims 1 to 19 characterised in that, on their backs supported in the respective associated guide in the chuck body, the clamping jaws and in a corresponding manner the guides, viewed in cross-section, each have a back contour substantially following the curvature of a circular segment, preferably having a circumferential angle of about 180 .

21. A drill chuck for hand tool machines, substantially as herein described with reference to the accompanying drawings.