Abstract:
The invention relates to a modular drill including a shank part with an end side. A cutting part can be connected to the shank part at its end side. The shank part has at least one torque transmission element which projects on the end side and has at least one torque transmission face for transmitting a torque in the rotational direction from the shank part to the cutting part. The cutting part has at least one torque receiving region for receiving the torque. The at least one torque receiving region has at least one torque receiving face which corresponds with the torque transmission face. The cutting part has at least one centering element for radially centering the cutting part in relation to the shank part. The cutting part is clamped to the shank part via a clamping element which acts at least predominantly in the axial direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claim is a 371 national stage application of a 371 of international application No. PCT/EP2010/053485, filed on Mar. 17, 2010, and claims the benefit of and priority to German Patent Application No. 10 2009 013 580.4, filed Mar. 19, 2009, the contents of each of which are hereby incorporated by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a modular drill, comprising a shank part with an end side, and a cutting part which is connected or can be connected to the shank part at its end side. 
     2. Background and Relevant Art 
     Drills, in particular made from solid carbide, have previously been configured in one piece as a rule. On account of the steeply rising raw material prices, in particular for carbide, manufacturers are changing, however, to manufacture and market modular tools. 
     Modular drills comprise firstly a shank part and secondly a cutting part, the shank part and the cutting part being connected or being capable of being connected to one another at a dividing point. In modular drills, the torque which is exerted on the shank part in order to make the drilling operation possible has to be transmitted to the cutting part. 
     In modular drills, only the cutting part is usually or at least frequently formed from solid carbide, and in contrast the shank part is formed from hardened steel. 
     Modular drills are known from JP 2005 16 14 62, DE 696 29 943 T2, WO 03/070408, DE 44 35 857 A1 and DE 698 25 586 T2. 
     BRIEF SUMMARY OF THE INVENTION 
     It is firstly an object of the invention to provide a new dividing point for a modular drill. It is additionally an object of the invention to provide a modular drill which has as satisfactory a possibility for transmitting the torque as possible and additionally can be operated as inexpensively as possible. 
     The objects are achieved by a modular drill as claimed in claim  1  of the invention, advantageous embodiments and developments resulting, in particular, from the subclaims. 
     In accordance with claim  1 , the invention relates to a modular drill, comprising 
     a) a shank part with an end side, 
     a1) the shank part being rotatable in a rotational direction about a rotational axis, 
     b) a cutting part which is rotatable about a or the rotational axis, and which is connected or can be connected to the shank part at its end side, 
     c) the shank part having at least one torque transmission element which projects on the end side, 
     c1) the at least one torque transmission element having at least one torque transmission face for transmitting a torque in the rotational direction from the shank part to the cutting part, 
     d) the cutting part having at least one torque receiving region for receiving the torque, 
     d1) the at least one torque receiving region having at least one torque receiving face which corresponds with the torque transmission face, 
     e) the cutting part having at least one centering element for radially centering the cutting part in relation to the shank part, 
     f) the cutting part being clamped or being capable of being clamped to the shank part via a clamping element which acts at least predominantly in the axial direction. 
     With the aid of the modular drill according to the invention, a dividing point is therefore produced between the shank part and the cutting part, by way of which dividing point torques can be transmitted advantageously from the shank part to the cutting part. In addition, the modular drill according to the invention permits radial centering and clamping of the cutting part in relation to the shank part. 
     The modular drill according to the invention makes a material saving possible, since usually the entire drill no longer has to be replaced as a result of wear, but rather only the cutting part. If only the cutting part is replaced, regrinding of the drill which is customary in non-modular drills is also dispensed with, which regrinding usually takes place at the drill manufacturer and also causes additional costs for shipping, with the result that the logistics costs for the provision of the drill are also reduced further by the modular drill according to the invention. 
     The shank part preferably has, on its end side, a dividing face which extends at least substantially perpendicularly with respect to the rotational axis and/or the cutting part has, on its base side which is remote from the end side, a dividing face which extends at least substantially perpendicularly with respect to the rotational axis, the dividing face of the shank part and the dividing face of the cutting part particularly preferably adjoining one another or being capable of adjoining one another flatly, in particular in contact with one another. This increases the stability of the connection of cutting part and shank part in an additional way. 
     The shank part preferably has exactly or at least two drill bodies extending parallel to the rotational axis or helically around the rotational axis at a helix angle, which drill bodies are separated from one another by flutes, the or in each case one torque transmission element particularly preferably being formed at the end-side end of a or each drill body or forming the end-side end. Torques can be transmitted in a particularly advantageous way via the end-side end. 
     The cutting part preferably has at least two drill bodies extending parallel to the rotational axis or helically around the rotational axis at a helix angle, which drill bodies are separated from one another by flutes, the or each drill body forming a cutting edge at its end-side edge which is arranged in the rotational direction, a cutting edge corner being formed at the outer end of the or each cutting edge. 
     In one preferred embodiment, the or each drill body has a drill body end face at its end-side end, which drill body end face is particularly preferably adjoined in the opposite rotational direction by a drill body intermediate face which forms a transition to the or to a flute. As a result, firstly the stability of the edge can be increased and secondly the discharging of the accumulating chips can be improved. 
     The or in each case one torque receiving element preferably extends from the dividing face to the drill body intermediate face and/or to the drill body end face and adjoins the drill body intermediate face and/or the drill body end face. In this way, the torque receiving element and optionally the torque transmission element can be of particularly large configuration, as a result of which the torque can be transmitted in a particularly effective way. 
     As an alternative or in addition, the torque receiving region extends parallel to the rotational axis in the direction of the drill body end face and/or of the drill body intermediate face or has an inclination counter to the rotational direction. This makes particularly simple mounting of the cutting part on the shank part possible, since the cutting part can be attached to the shank part without a rotation of the cutting part in relation to the shank part being required as they approach one another. 
     The torque transmission element preferably has at least one centering face for radially centering the cutting part in relation to the shank part, the at least one torque receiving region having a mating centering face which corresponds with the centering face, the at least one centering face forming, together with the mating centering face, a centering element. A centering face on the torque transmission element makes particularly efficient production of cutting and shank parts possible, since the torque transmission element can act at the same time as a centering element in this case. 
     In one preferred embodiment, a pin is arranged on the cutting part along the rotational axis, a central hole being arranged on the shank part along the rotational axis. 
     The pin preferably engages into the central hole or can engage into the latter and/or forms a centering element for radially centering and/or stabilizing the cutting part in relation to the shank part. A pin along the rotational axis as centering element makes simple production possible, since said pin can be produced in a centered manner and in a simple way during rotation of the cutting part around its rotational axis. 
     The drill preferably has a drill diameter on the cutting part, the clamping element having holes (or: through holes) for fastening screws in the cutting part, the shank part having threaded holes (or: holes which have a thread), preferably as a continuation of the holes in the cutting part, for fastening screws, the fastening screws having a diameter of between 10% and 30%, preferably of approximately 15%, of the drill diameter. Fastening screws on the cutting part can be used in a simple way for clamping, and in addition the clamping force can be metered in a simple way by fixing of the torque to be used during tightening of the fastening screws. 
     In one preferred embodiment, the cutting part has a drill diameter, the cutting part having two drill bodies, a first plane 
     a) being remote from the rotational axis by from 40% to 70%, preferably by approximately 60%, of half the drill diameter, 
     b) being parallel to the rotational axis, and 
     c) being rotated by from 50° to 85°, preferably by 68°, with respect to a second plane through the shank-side cutting edge corners of the two drill bodies, in which second plane the rotational axis preferably extends, 
     d) the center axis for the screw holes for the fastening screws extending on the first plane, in particular at an angle in relation to a line which is parallel to the rotational axis, preferably of from approximately 30% to 80%, particularly preferably of from approximately 40% to 60%, of the helix angle. 
     This arrangement of the center axes can firstly be set simply to a predefined helix angle, and secondly the two screw connections make a particularly stable connection possible as a result of their relative angle with respect to one another. 
     The drill preferably has a drill diameter, the cutting part having two drill bodies, the center axis for a or each screw hole for the fastening screws extending in each case on a first plane and on a third plane, the first plane
     a) extending at an angle of from 50° to 85°, preferably of approximately 68°, with respect to a second plane through the shank-side cutting edge corners and at least substantially through the rotational axis, and   b) extending at least substantially parallel to the rotational axis, the spacing of the first plane from the rotational axis being from 40% to 70%, preferably approximately 60%, of half the drill diameter, and
 
the third plane being at an angle of approximately 90° with respect to the first plane and/or being inclined by from approximately 40% to 60% of the helix angle.
   

     The clamping element on the cutting part preferably has, along the rotational axis, a threaded hole for a fastening screw, the shank part having, along the rotational axis, a through hole for the fastening screw. In this embodiment, effective clamping of cutting part and shank part which can be metered satisfactorily can be achieved merely with a single screw, which clamping additionally exerts a direct axial force on the cutting part and, moreover, does not have to impair the end face of the cutting part. 
     The clamping element preferably comprises a fastening screw which is screwed or can be screwed laterally at an angle into the shank part, the fastening screw engaging or being capable of engaging laterally at an angle into the pin, the pin having a recess for the engagement. This connection of cutting part and shank part which can also be called a whistle notch can likewise be metered satisfactorily, does not have to impair the end face of the drill and additionally can be set and/or fixed even when the drill is clamped. 
     At least one or in each case one cooling channel hole preferably extends within at least one or each drill body, it preferably but not necessarily being possible for the at least one cooling channel hole to extend so as to correspond with the course of the drill body in relation to the rotational axis, and it being possible, in particular, for it to extend parallel to or helically around the rotational axis, and/or the at least one cooling channel hole exiting in at least one flute of the shank part. This makes the feed of coolant possible without impairment of the cutting part and/or without the requirement for holes for the feed of coolant on the cutting part. 
     In one preferred embodiment, the torque transmission face and/or the torque receiving face are/is of straight, convex or concave configuration, and/or the torque transmission face and/or the torque receiving face extends/extend at a positive or negative angle of between 5° and 35°, preferably between 15° and 30°, particularly preferably of at least approximately 20°, with respect to the rotational axis. 
     The drill preferably has a drill diameter, the torque receiving face extending at an angle with respect to the dividing face, and/or a first transition region extending between a first torque receiving face and the dividing face and a second transition region extending between a second torque receiving face and the dividing face, the longitudinal edges of the first transition region extending at least approximately parallel to the longitudinal edges of the second transition region, and/or the longitudinal edges of the first transition region being at a spacing of from approximately 40 to 60%, preferably of approximately 50%, of half the drill diameter from the longitudinal edges of the second transition region, measured perpendicularly with respect to the course direction of the longitudinal edges. 
     The centering face and/or the mating centering face are/is preferably of flat or curved configuration, in particular as part of a cylinder shell face with the rotational axis as center axis. A centering face which is configured as part of a cylinder shell face with the rotational axis as center axis can likewise be produced in a particularly effective way, whereby the drill can also be operated at least comparatively inexpensively. 
     The or each torque transmission element preferably comprises an end face at its end-side end, the following adjoining the end face in the counterclockwise direction: 
     a) at least one outer face which merges at the other end into an outer face of the drill body, 
     b) the torque transmission face which adjoins the dividing face at the other end, 
     c) the or a centering face which adjoins the dividing face at the other end, and 
     d) a mating torque transmission face which merges at the other end into a flute. 
     The torque receiving face preferably adjoins the mating centering face at an angle, the angle being approximately 90°, the torque transmission face particularly preferably or as an alternative adjoining the centering face at an angle, the angle being approximately 90°. These variants make particularly satisfactory centering of the cutting part possible in relation to the shank part with simultaneously satisfactory torque transmission. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following text, the invention will be explained further using exemplary embodiments and with reference to the appended drawings, in which: 
         FIGS. 1 and 2  show exemplary embodiments for modular drills according to the invention, 
         FIG. 3  shows one exemplary embodiment for a shank part according to the invention, and 
         FIGS. 4 to 8  show exemplary embodiments for cutting parts according to the invention. 
         FIGS. 9 and 10  show exemplary embodiments for shank parts according to the invention, and 
         FIG. 11  shows one exemplary embodiment for a shank part according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The modular drills  1  according to  FIGS. 1 and 2  in each case comprise a shank part  2  and a cutting part  3  (or drill head) which can be connected to the shank part, which shank part  2  and cutting part  3  can be rotated in each case in a rotational direction about the rotational axis D. The base side  39  of the cutting part  3 , which base side  39  is remote from the end side, can be connected to the shank part  2  at the end side  29  of the latter. 
     For machine-side receiving, the shank part  2  has a shank which can be configured in a manner known per se, for example in cylindrical form, and is not shown in the figures. 
     The shank part  2  has two drill bodies  22  and  23  which extend helically around the rotational axis D at a helix angle □ 1 . As an alternative, the drill bodies could also extend in the axial direction, parallel to the rotational axis D. A greater number of drill bodies is likewise possible. 
     The drill bodies  22  and  23  of the shank part  2  are separated from one another in each case by flutes  27  and  28 . 
     The cutting part  3  accordingly has two drill bodies  32  and  33  which extend helically around the rotational axis D, likewise at a helix angle □ 1 . As an alternative, in particular if this is the case in the shank part  2 , the drill bodies  32  and  33  could also extend in the axial direction, parallel to the rotational axis D. A greater number of drill bodies is likewise accordingly possible. 
     The drill bodies  32  and  33  of the cutting part  3  are also separated from one another in each case by flutes  37  and  38 . The cutting part  3  has a dividing face  34  at its end which faces the shank part  2 . 
     As can be seen, for example, from  FIG. 6 , the drill body  32  has a drill body end face  322  at its end-side end, which drill body end face  322  is adjoined in the opposite rotational direction by a drill body intermediate face  323  which forms a transition to the flute  37 . 
     At its end-side end, which can be seen only partially in  FIG. 6 , the drill body  33  has a drill body end face  332  which is adjoined in the opposite rotational direction by a drill body intermediate face  333  which forms a transition to the flute  38 . 
     As can be seen, in particular, from  FIG. 5 , the drill body  32  of the cutting part  3  forms a cutting edge  321  at its end-side edge which is arranged in the rotational direction, an end-side cutting edge corner  324  being formed at the outer end of the cutting edge. The cutting edge continues in the direction of the shank part  2  as far as the dividing face  34 , at which the cutting edge forms a shank-side cutting edge corner  325 . 
     Accordingly, the drill body  33  forms a cutting edge  331  at its end-side edge which is arranged in the rotational direction, an end-side cutting edge corner  334  being formed once again at the outer end of the cutting edge  331 . The cutting edge continues in the direction of the shank part  2  as far as the dividing face  34 , at which the cutting edge forms a shank-side cutting edge corner  335 . 
     As can be seen, for example, from  FIG. 7 , the torque receiving element  30  extends from the dividing face  34  to the drill body intermediate face  323  and adjoins the drill body intermediate face  323 . 
     In the direction of the drill body intermediate face  323 , the torque receiving region  30  has an inclination counter to the rotational direction, but it can also extend parallel to the rotational axis D. 
     The torque receiving element  31  correspondingly extends from the dividing face  34  to the drill body intermediate face  333  and adjoins the drill body intermediate face  333 . 
     Like the torque receiving region  30 , the torque receiving region  31  has an inclination in the direction of the drill body intermediate face  333  counter to the rotational direction, but it can also extend parallel to the rotational axis D. 
     As can also be seen from  FIG. 3 , the shank part  2  has a dividing face  24  on its end side  29 , which dividing face  24  extends perpendicularly with respect to the rotational axis D, and, at the outer edges of the dividing face  24 , two torque transmission elements  20  and  21  which project on the end side. 
     On an end side, the torque transmission element  20  has an end face  202  which is adjoined, in each case at least approximately at right angles, on the outer side by an outer face  203  and, in the viewing direction of the shank part  2  in the counterclockwise direction, by a torque transmission face  200 , an inwardly directed centering face  201  and a mating torque transmission face  204 . 
     At its end which is remote from the end side  202 , the outer face  203  merges smoothly into the outer face  220  of the drill body  22  and has a curvature which is at least approximately like the outer face  220  of the drill body  22 . 
     The torque transmission face  200  and the centering face  201  are of flat or curved configuration and, at their end which is remote from the end side  202 , in each case merge approximately at right angles or at another angle into the dividing face (or connecting face)  24 . 
     At its end which is remote from the end side  202 , the mating torque transmission face  204  merges smoothly into the flute  27 . 
     In a corresponding way, the torque transmission element  21  has, on its end side, an end face  212  which is adjoined, in each case at least approximately at right angles, on the outer side by an outer face  213  and, in the viewing direction of the shank part  2  in the counterclockwise direction, a torque transmission face  210 , an inwardly directed centering face  211  and a mating torque transmission face  214 . 
     At its end which is remote from the end side  212 , the outer face  213  merges smoothly into the outer face  230  of the drill body  23  and has a curvature which is at least approximately like the outer face  230  of the drill body  23 . 
     The torque transmission face  210  and the centering face  211  are of flat or curved configuration and, at their end which is remote from the end side  212 , merge in each case approximately at right angles or at another angle into the dividing face (or connecting face)  24 . 
     At its end which is remote from the end side  202 , the mating torque transmission face  214  merges smoothly into the flute  28 . 
     In a corresponding manner to the dividing face (or: connecting face)  24 , the cutting part  3  forms a dividing face (or: connecting face)  34  which likewise extends perpendicularly with respect to the rotational axis D. 
     In a corresponding way to the torque transmission element  20 , a torque receiving region  30  is formed on the cutting part  3 , which torque receiving region  30  has a torque receiving face  300  which can bear flatly against the torque transmission face  200  and a mating centering face  301  which can bear flatly against centering face  201 . This can be seen from  FIG. 2  and from  FIGS. 4 to 8 ,  FIG. 3  and  FIG. 7  showing embodiments which can be combined with one another. To this extent, the torque receiving face  300  corresponds with the torque transmission face  200  and the mating centering face  301  corresponds with the centering face  201 . The mating centering face  301  and the torque receiving face  300  are at an angle of approximately 90° with respect to one another. 
     In a corresponding way to the torque transmission element  21 , furthermore, a torque receiving region  31  is formed on the cutting part  3 , which torque receiving region  31  has a torque receiving face  310  and a mating centering face  311 . This can likewise be seen from  FIG. 2  and partially from  FIGS. 4 to 8 . Here, the torque receiving face  310  corresponds with the torque transmission face  210  and the mating centering face  311  corresponds with the centering face  211 . The mating centering face  311  and the torque receiving face  310  are also at an angle of approximately 90° with respect to one another. 
     Furthermore, a central pin  340  is arranged as centering pin on the cutting part  3  according to  FIGS. 1 ,  4 ,  6 ,  7  and  8 , which centering pin extends from the center of the dividing face  34  in the direction of the shank part  2 . In a corresponding way, a central hole  240  is made in the shank part  2 , into which central hole  240  the pin  340  engages circularly and thus likewise centers the cutting part  3  in relation to the shank part  2 . 
     As an alternative,  FIG. 2  shows a screw  42  which is introduced into a corresponding through hole  243  which is arranged centrally within the shank part  2 . The screw  42  extends with its first end on the end side in the direction of the cutting part  3  and crosses the shank part  2  along its rotational axis D, the opposite second end having a hexagon socket  420  for adjusting the screw  42 . 
     In a corresponding way, the cutting part  3  comprises a threaded hole  343  which has a thread, into which the screw  42  can engage. 
       FIG. 6  shows a threaded pin  43  with an external thread  430 , which threaded pin  43  can be screwed laterally at an angle by way of a suitable threaded hole (not shown) which is directed away from the end side through the shank part as far as a recess  350  in the pin  340  of the cutting part  3 , which recess  350  is arranged within the shank part, whereby the pin  340  and therefore the cutting part  3  can be fixed on the shank part (whistle notch). 
     In contrast,  FIG. 1  shows two screws  40  and  41  which engage at an angle into a hole  341  and a hole  342  of the cutting part  3 , two threaded holes  241  and  242  being made additionally on the shank part  2 , into which threaded holes  241  and  242  the screws  40  and  41  can engage. 
     Coolant channels  221  and  231  which extend helically or else in a straight line in a manner known per se and of which, however, only the outlet opening of the coolant channel  221  can be seen in the FIG can be formed within the drill bodies  22  and  23  of the shank part  2 . 
       FIG. 4  shows a further embodiment of the cutting part  3  according to the invention with torque receiving face  302  and mating centering face  303 . The torque receiving face  302  has a curvature counter to the rotational direction. 
       FIG. 8  shows a further embodiment of a cutting part  3  according to the invention with a straight, non-curved torque receiving face  304  and a mating centering face  305 . The mating centering face  305  has a radial curvature. The associated torque transmission element (not shown) of the shank part  2  is shaped in a corresponding way. 
     In order to operate the modular drill  1 , to this extent the cutting part  3  is fastened to the shank part  2  by screws  40  and  41  and/or a screw  42  and/or the pin  340 , which brings about fixing in the axial direction and, in particular as a result of the pin  340 , in the radial direction. 
     Furthermore, the cutting part  3  can be fixed in the radial direction with respect to the shank part  2  by the centering faces  201 ,  211  and can transmit the required torque M via the torque transmission faces  200 ,  210 . 
     Together with the centering face  211  in correspondence with the mating centering face  311 , the centering face  201  in correspondence with the mating centering face  301  brings about radial centering of the cutting part  3  in relation to the shank part  2 . 
     To this extent, the torque transmission elements  20  and  21  make both radial centering of the cutting part  3  in relation to the shank part  2  and a satisfactory transmission of the torque from the cutting part  3  to the shank part  2  possible. 
     The angle □ 3  (which can be seen in  FIG. 6 ) of the torque receiving face  300  with respect to the drill axis D is preferably approximately 20° in the opposite rotational direction. 
     A first transition region  308  is arranged, in each case at an angle, between the first torque receiving face  300  and the dividing face  34 , and a second transition region  318  extends between a second torque receiving face  310  and the dividing face  34 . This can likewise be seen in  FIG. 5 . 
     The first transition region  308  extends parallel to the second transition region  318 . The first transition region  308  has a spacing A from the second transition region  318  of approximately 50% of half the drill diameter B, as measured perpendicularly with respect to the course direction of the longitudinal edges of the transition regions  308  and  318 . 
     As is shown in  FIG. 1  and  FIG. 5 , the screws  40  and  41  are inclined in each case at an angle with respect to the rotational axis D. This represents one preferred embodiment of the invention. The inclined screws  40  and  41  make radial play-free mounting of the cutting part  3  possible, since the torque transmission faces and the corresponding mating torque transmission faces are clamped against one another. 
     In order to realize the angle of the screws  40  and  41  with respect to the rotational axis D, the center axes for the associated screw holes  341 ,  342  are positioned obliquely. 
     Here, the center axis for the screw hole  341  lies both on a first plane K and on a third plane P. 
     The first plane K is at an angle generally of between 50° and 85°, of approximately 68° for the concrete embodiment, with respect to a second plane N through the shank-side cutting edge corners  325 ,  335  and through the rotational axis, the spacing of the first plane K from the rotational axis D generally being between 40% and 70%, approximately 60% for the concrete embodiment, of half the drill diameter B. The plane K extends parallel to the rotational axis D. 
     The third plane P is at an angle of approximately 90° with respect to the first plane K and is inclined by from approximately 40% to 60% of the helix angle. 
     The center axis for the screw hole  342  lies both on a first plane L and on a third plane Q. 
     The first plane L is at an angle generally of between 50° and 85°, of approximately 68° for the concrete embodiment, with respect to the second plane N through the shank-side cutting edge corners  325 ,  335  and through the rotational axis, the spacing of the first plane L from the rotational axis D generally being between 40% and 70%, approximately 60% for the concrete embodiment, of half the drill diameter B. The plane L extends parallel to the rotational axis D. 
     The third plane Q is at an angle of approximately 90° with respect to the first plane L and is inclined by from approximately 40% to 60% of the helix angle. 
     To this end,  FIG. 5  shows the first plane K and the plane L parallel thereto, which planes K, L are remote from the drill axis D generally by between 40% and 70%, approximately 60% in the concrete embodiment, of half the drill diameter, are parallel to said drill axis D, and are rotated here in each case generally by between 50° and 85°, by approximately 68° for the concrete embodiment, with respect to the second plane N through the shank-side cutting edge corners  325  and  335  and the rotational axis D. Furthermore,  FIG. 5  shows a section through the planes P and Q, the plane P extending parallel to the center axis of the screw hole  341  in the direction of the end side of the cutting part  3 , and the plane Q extending parallel to the center axis of the screw hole  342  in the direction of the end side. 
     The center axis of the screw hole  341  for the fastening screw  40  extends on the first plane K through the drill body  32  at an angle of approximately 60% of the helix angle □ 1  which is approximately 30° in relation to a line which is parallel to the rotational axis D. 
     The center axis of the screw hole  342  for the fastening screw  41  extends on the plane L through the drill body  34  at an angle of approximately 60% of the helix angle □ 1  in relation to a line which is parallel to the rotational axis D. 
     In the embodiment according to  FIG. 1  and  FIG. 5 , the screw diameter S of the screws  40  and  41  is from 10% to 30%, preferably approximately 15%, of the diameter B of the drill  1 . 
       FIG. 9  shows a further shank part  2  which corresponds with the cutting part  3  according to  FIG. 8 . 
     The shank part  2  once again has a dividing face  24  on its end side  29 , which dividing face  24  extends perpendicularly with respect to the rotational axis D, and two torque transmission elements  20  and  21  which project on the end side at the outer edges of the dividing face  24 . 
     On its end side, the torque transmission element  20  has an end face  202  which is adjoined, in each case at least approximately at right angles, on the outside by an outer face  203  and, in the viewing direction of the shank part  2  in the counterclockwise direction, a torque transmission face  200 , an inwardly directed centering face  201  and a mating torque transmission face  204 . 
     At its end which is remote from the end side  202 , the outer face  203  merges smoothly into the outer face  220  of the drill body  22  and has a curvature which is at least approximately like the outer face  220  of the drill body  22 . 
     The torque transmission face  200  according to  FIG. 9  is of flat configuration and, at its end which is remote from the end side  202 , merges at an angle of approximately 110° into the dividing face (or connecting face)  24 , another angle also being possible. 
     In a corresponding manner to the face  305  of the cutting part  3  according to  FIG. 8 , the centering face  201  according to  FIG. 9  is of tangentially curved configuration and, at its end which is remote from the end side  202 , merges approximately at a right angle into the dividing face (or connecting face)  24 , another angle also being possible in correspondence with the face  305  according to  FIG. 8 . 
     At its end which is remote from the end side  202 , the mating torque transmission face  204  according to  FIG. 9  merges smoothly into the flute  27 . 
     In a corresponding way, the torque transmission element  21  has an end face  212  on its end side, which end face  212  is adjoined, in each case at least approximately at right angles, on the outer side by an outer face  213  and, in the viewing direction of the shank part  2  in the counterclockwise direction, a torque transmission face  210 , an inwardly directed centering face  211  and a mating torque transmission face  214 . 
     At its end which is remote from the end side  212 , the outer face  213  merges smoothly into the outer face  230  of the drill body  23  and has a curvature which is at least approximately like the outer face  230  of the drill body  23 . 
     The torque transmission face  210  is of flat configuration and, at its end which is remote from the end side  212 , merges at an angle of approximately 110° into the dividing face (or connecting face)  24 , another angle also being possible in correspondence with the corresponding face in the cutting part according to  FIG. 8 . 
     In a corresponding manner to the face  315  according to  FIG. 8 , the centering face  211  according to  FIG. 9  is of tangentially curved configuration and, at its end which is remote from the end side  212 , merges approximately at a right angle into the dividing face (or: connecting face)  24 , another angle also being possible once again in a corresponding manner with the face  315 . 
     At its end which is remote from the end side  212 , the mating torque transmission face  214  according to  FIG. 9  merges smoothly into the flute  28 . 
     In a corresponding manner to the dividing face (or: connecting face)  24  according to  FIG. 9 , the cutting part  3  according to  FIG. 8  forms a dividing face (or: connecting face)  34  which likewise extends perpendicularly with respect to the rotational axis D. 
     Furthermore, the cutting part  3  according to  FIG. 9  can be fixed in the radial direction with respect to the shank part  2  by the centering faces  201 ,  211  and can transmit the required torque M via the torque transmission faces  200 ,  210 . 
       FIG. 10  shows a further shank part  2  which corresponds with the cutting part  3  according to  FIG. 11 . 
     On its end side  29 , the shank part  2  according to  FIG. 10  has a dividing face  24  which extends perpendicularly with respect to the rotational axis D, and two torque transmission elements  20  and  21  which project on the end side at the outer edges of the dividing face  24 . 
     On its end side, the torque transmission element  20  has an end face  207  which is adjoined, in each case at least approximately at right angles, on the outside by an outer face  208  and, in the viewing direction of the shank part  2  in the counterclockwise direction, a torque transmission face  205 , an inwardly directed centering face  206  and a mating torque transmission face  209 . 
     At its end which is remote from the end side  207 , the outer face  208  merges smoothly into the outer face  220  of the drill body  22  and has a curvature which is at least approximately like the outer face  220  of the drill body  22 . 
     The torque transmission face  205  is of flat configuration and, at its end which is remote from the end side  207 , merges at an angle of approximately 60° into the dividing face (or: connecting face)  24 , another angle also being possible in correspondence with the corresponding face on the cutting part  3  according to  FIG. 11 . 
     The centering face  206  according to  FIG. 10  is of curved configuration and, at its end which is remote from the end side  207 , merges approximately at a right angle into the dividing face (or: connecting face)  24 , another angle also being possible in correspondence with the corresponding face on the cutting part  3  according to  FIG. 11 . 
     At its end which is remote from the end side  207 , the mating torque transmission face  209  according to  FIG. 10  merges smoothly into the flute  27 . 
     In a corresponding way, the torque transmission element  21  has an end face  217  on its end side, which end face  217 , in each case at least approximately at right angles, is adjoined on the outside by an outer face  218  and, in the viewing direction of the shank part  2  in the counterclockwise direction, a torque transmission face  215 , an inwardly directed centering face  216  and a mating torque transmission face  219 . 
     At its end which is remote from the end side  217 , the outer face  218  merges smoothly into the outer face  230  of the drill body  23  and has a tangential curvature which is at least approximately like the outer face  230  of the drill body  23 . 
     The torque transmission face  215  according to  FIG. 10  is of flat configuration and, at its end which is remote from the end side  217 , merges at an angle of approximately 60° into the dividing face (or: connecting face)  24 , another angle also being possible according to the associated face according to  FIG. 11 . 
     The centering face  216  according to  FIG. 10  is of curved configuration and, at its end which is remote from the end side  217 , merges approximately at a right angle into the dividing face (or: connecting face)  24 , another angle also being possible according to the associated face according to  FIG. 11 . 
     At its end which is remote from the end side  217 , the mating torque transmission face  219  according to  FIG. 10  merges smoothly into the flute  28 . 
     In a corresponding manner to the dividing face (or: connecting face)  24  according to  FIG. 10 , the cutting part  3  according to  FIG. 11  forms a dividing face (or: connecting face)  34  which likewise extends perpendicularly with respect to the rotational axis D. 
       FIG. 11  shows a cutting part  3  which belongs to the shank part  2  according to  FIG. 10 . 
     In a corresponding way to the torque transmission element  20  according to  FIG. 10 , a torque receiving region  30  is formed on the cutting part  3  according to  FIG. 11 , which torque receiving region  30  has a torque receiving face  306  which can bear flatly against the torque transmission face  205  and a mating centering face  307  which can bear flatly against centering face  206 . 
     To this extent, the torque receiving face  306  according to  FIG. 11  corresponds with the torque transmission face  205  according to  FIG. 10 , and the mating centering face  307  corresponds with the centering face  206 . The mating centering face  307  and the torque receiving face  306  are at an angle of approximately 90° with respect to one another. 
     The angle of the torque receiving face  306  with respect to the drill axis D is preferably approximately 30° in the rotational direction. 
     Furthermore, in a corresponding way to the torque transmission element  21  according to  FIG. 10 , a torque receiving region  31  which has a torque receiving face  316  and a mating centering face  317  is formed on the cutting part  3  according to  FIG. 11 . 
     Here, the torque receiving face  316  according to  FIG. 11  corresponds with the torque transmission face  215  according to  FIG. 10 , and the mating centering face  317  corresponds with the centering face  216 . The mating centering face  317  and the torque receiving face  316  are also at an angle of approximately 90° with respect to one another. 
     LIST OF DESIGNATIONS 
     
         
           1  Drill 
           2  Shank part 
           20 ,  21  Torque transmission element 
           200 ,  210  Torque transmission faces 
           201 ,  211  Centering faces 
           202 ,  212  End faces 
           203 ,  213  Outer faces 
           204 ,  214  Mating torque transmission faces 
           22 ,  23  Drill body 
           220 ,  230  Outer faces of the drill body 
           221 ,  231  Cooling channel holes 
           24  Dividing face 
           240  Central hole 
           241 ,  242  Threaded holes 
           243  Through hole 
           27 ,  28  Flutes 
           29  End side 
           3  Cutting part 
           30 ,  31  Torque receiving regions 
           300 ,  302 ,  304 ,  310  Torque receiving faces 
           301 ,  303 ,  305 ,  311  Mating centering face 
           308 ,  318  Transition region 
           32 ,  33  Drill body 
           320 ,  330  Outer faces of the drill body 
           321 ,  331  Cutting edges 
           322 ,  332  Drill body end face 
           323 ,  333  Drill body intermediate face 
           324 ,  334  End-side cutting edge corners 
           325 ,  335  Shank-side cutting edge corners 
           34  Dividing face 
           340  Pin 
           341 ,  342 ,  343  Holes 
           350  Recess 
           37 ,  38  Flutes 
           39  Base side 
           40 ,  41 ,  42  Screws 
           420  Hexagon socket 
           43  Threaded pin 
         A, C, S Spacings 
         B Drill diameter 
         D Rotational axis 
         K, L, N, P, Q Planes 
         M Torque 
         □ 1 □ Helix angle 
         □ 2 □ Rotation angle 
         □ 3  Inclination angle