DE20111666U1 - Drilling or boring tool - Google Patents

Description

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Patent Attorneys Lawyers

Dr. jur. Alf-Olav Gleiss, Dipl.-Ing. PA Rainer Große, Dipl.-Ing. PA Dr. Andreas Schrell, Dipl.-Biol. PA Torsten Armin Krüger, RA Nils Heide, RA
Armin Eugen Stockinger, Attorney Georg Brisch, Dipl.-Ing. PA Erik Graf v. Baudissin, RA

PA: Patent Attorney European Patent Attorney European Trademark Attorney

RA: Attorney-at-law D-70469 STUTTGART MAYBACHSTRASSE 6A Telephone: +49(0)711 81 45 55 Fax: +49(0)711 81 30 32 E-Mail: office@gleiss-grosse.com Homepage: www.gleiss-grosse.com

In cooperation with

Shanghai Hua Dong Patent Agency Shanghai, China

Utility model application

Drilling or reaming tool

Kemmer

Hardmetal Tools GmbH
In the Valley 11

72218 WILDBERG

16310t GR-to-ho

July 11, 2001

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Patent Attorneys Lawyers

Description

The invention relates to a drilling or boring tool with a shaft and an exchangeable head, according to the preamble of claim 1.

Tools of the type discussed here are known.

They are used, among other things, in conjunction with machine tools in which a tool shaft can be clamped and exchanged, in particular by means of a clamping device. An exchangeable head with a face geometry that forms or has at least one cutting edge is arranged on the shaft. The exchangeable head is subject to wear and can be exchanged without the entire drilling/boring tool having to be removed.

Torque transmission means are provided between the shaft and the interchangeable head in order to introduce a torque from the shaft into the interchangeable head or from the interchangeable head into the shaft. In a known tool, these torque transmission means are formed by several contact surfaces provided in one end face of the shaft, which extend radially from the outer circumference of the shaft in the direction of the longitudinal center axis of the shaft, and by corresponding counter surfaces on the interchangeable head, each of which interacts with a contact surface. The counter surfaces are also

16310b GR-to-ho ··· ■ * *·* '

July 11, 2001

arranged at a radial distance from the longitudinal center axis of the interchangeable head and extend to the outer circumference of the interchangeable head. It has been found to be disadvantageous that the torque transmission means of the known tools can only be implemented if the shaft has a sufficiently thick material in the area of its interface with the interchangeable head. This is not always available, especially with shafts that have several spiral grooves.

It is an object of the invention to provide a drilling or boring tool of the type mentioned at the outset, the torque transmission means provided between the shaft and the replaceable head can also be implemented if the shaft - seen in cross section - has only a relatively small wall or material thickness.

To solve the problem, a drilling and/or boring tool with the features of claim 1 is proposed. It is characterized in that the torque transmission means are arranged at a distance from an imaginary circumferential circle that determines the borehole diameter. They therefore do not extend into the radially outer region of the drilling/boring tool in which the at least one cutting edge of the tool is located. Due to this design, a firm and secure connection can be made between the replaceable head and the shaft even with shafts that - viewed in cross section - have only small wall/material thicknesses.

An embodiment of the drilling/boring tool is proposed in which the shaft has a flat, first separating surface and the interchangeable head has a flat, second separating surface, which lie flat against one another when the interchangeable head is mounted. These separating surfaces are preferably formed by one end face of the shaft and one end face of the interchangeable head. Because the separating surfaces do not have a complicated and therefore expensive to produce contour/geometry, but are flat, they can be machined in a simple and cost-effective manner, for example by grinding.

According to a further development of the invention, a first torque transmission means is formed by a projection extending from the first or second separating surface and a second torque transmission means is formed by a recess extending into the second or first separating surface, wherein in the assembled state of the interchangeable head the projection is arranged in the recess. The projection and the recess thus form a pin-hole connection which is relatively simple and therefore inexpensive to produce. The projection can therefore be arranged both on the shaft and on the interchangeable head, wherein depending on which of the two functional elements (shaft, interchangeable head) the projection is located on, the recess is arranged on the other functional element. The projection and possibly also the recess are preferably arranged in an area of their separating surface in which the shaft or the interchangeable head - seen in cross section -

has a relatively large material thickness, i.e. is thick-walled, so that a firm and secure connection between the interchangeable head and the shaft can be guaranteed even when high torques are transmitted from the shaft to the interchangeable head or from the interchangeable head to the shaft.

In a preferred embodiment, it is provided that in the assembled state of the interchangeable head, in which the projection engages in the recess or is arranged in it, there is little or no play between the projection and the recess. This ensures that - if at all - only a very small relative movement between the interchangeable head and the shaft in the circumferential direction of the drilling/boring tool is possible.

A particularly preferred embodiment of the drilling/boring tool is one in which the shape of the projection and the recess are selected and adapted to one another in such a way that when the interchangeable head is attached to the shaft, the interchangeable head is centered relative to the shaft. This ensures that the interchangeable head is precisely aligned relative to the shaft and - if the drilling/boring tool is driven to rotate around its longitudinal center axis during the machining of a component - that the drilling/boring tool runs precisely. Additional centering means are therefore not required.

In an advantageous embodiment, it is provided that the outer contour of the projection of the

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The inner contour of the recess corresponds to this. This means that the projection and the recess are in contact with one another over a relatively large area in relation to the total area of the projection. Line or edge contact between the projection and the recess, which leads to high surface pressure when machining a component using the drilling/boring tool, can therefore be safely avoided.

In a particularly advantageous embodiment of the drilling/boring tool, the projection is formed by a cylindrical pin which can be inserted into a receptacle provided therein after machining the separating surface. The flat separating surfaces can therefore be machined in a simple manner, for example by grinding them flat, as they do not have any disruptive edges. The pin is a separate functional element which can also be made of a different material than the interchangeable head or the shaft. According to another variant of the drilling/boring tool, the projection is formed in one piece with the shaft or the interchangeable head. This can be advantageous, for example, if the shaft or the interchangeable head is produced by sintering, so that a further machining step may not be necessary.

According to a further development of the invention, it is provided that several first and several second torque transmission means are provided, wherein in each case a first and a second torque transmission

The first and second torque transmission means can be designed like the torque transmission means described above. It is advantageous if the torque transmission means arranged at a distance from the imaginary circumferential circle determining the borehole diameter are evenly distributed in the circumferential direction of the drilling or reaming tool. In order to ensure in this arrangement of the torque transmission means that when the interchangeable head is attached, the same first and second torque transmission means always cooperate with each other or are assigned to each other, an advantageous embodiment provides that at least one first and one second torque transmission means interacting with it have a shape and/or size that differs from the other torque transmission means. This ensures that preferably only one way of attaching the interchangeable head to the shaft is possible. This is particularly advantageous in the case of a drilling/reaming tool in which the interchangeable head has a spiral groove area, so that by means of the above-mentioned differently designed torque transmission means, the interchangeable head is always connected to the shaft in the same spiral groove.

Finally, an embodiment of the drilling/boring tool is preferred which is characterized by the fact that it is a multi-cutter, in particular a two-cutter or a three-cutter. The inventive design of the torque transmission

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The torque transmission means or their arrangement in relation to the imaginary circumferential circle that determines the borehole diameter also enable the realization of a quick-change head with three cutting edges and, accordingly, three spiral grooves. These three-cutting edge tools are known to have only low material or wall thicknesses due to the three spiral grooves - seen in cross-section. Nevertheless, a firm and secure connection between the interchangeable head and shaft can be ensured with the aid of the torque transmission means according to the invention.

Further advantageous embodiments result from combinations of the features mentioned in the subclaims.

The invention is explained in more detail below with reference to the drawing.

Figure 1 is a side view of a first embodiment of a drilling/boring tool, partially in section;

Figure 2 is a side view of an interchangeable head of the drilling/boring tool shown in Figure 1;

Figure 3 is a sectional view of the interchangeable head shown in Figure 2 along the

Section line A-A;

Figure 4 is a side view of a shaft of the drilling/boring tool shown in Figure 1;

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Figure 5 is a plan view of a parting surface of the shaft shown in Figure 4;

Figure 6 is a plan view of a separating surface of another embodiment of the interchangeable head; and

Figures each show an embodiment of a 7A to 9B between the interchangeable head and the shaft

arranged torque transmission means.

Figures 1 to 5 each show a view of an embodiment of a drilling and boring tool 1, by means of which an existing hole can be bored out or drilled into the solid. During the machining of a component, chips are removed from it. The drilling/boring tool 1 generally carries out a circular cutting movement and at the same time a feed movement in the direction of its axis of rotation 3. In some cases, the cutting movement is carried out by the rotating component, for example when drilling on a lathe.

In Figure 1, the drilling/boring tool 1 designed as a twist drill is shown in the assembled state. It comprises a shaft 5 and an exchangeable head 7 arranged at the end thereof. The shaft 5 has a clamping area 9 and a spiral groove area 11. In the clamping area 9, the shaft 5 is held by means of a suitable clamping device of a machine tool, clamping device or the like. The

Tool 1 is designed here as a three-cutter, that is, the interchangeable head 7 has three cutting edges 13, 15, 17, as can be seen in particular from Figure 3, which shows a plan view of the interchangeable head 7 along the section line A-A shown in Figure 2.

The tool 1 further comprises a number of helical chip grooves 19 corresponding to the number of cutting edges 13, 15 and 17, i.e. three, which enable the removal of chips. The chip grooves 19 are - like the cutting edges 13 to 17 - evenly distributed in the circumferential direction of the tool 1, i.e. at a distance of 120°.

The shaft 5 has a first separating surface 21 which is flat and against which the interchangeable head 7 rests in the assembled state, as shown in Figure 1, with a second separating surface 23 which is also flat. The separating surfaces 21, 23 are each located on an end face of the shaft 5 or the interchangeable head 7. The interface between the shaft 5 and the interchangeable head 7 is indicated by a separating plane E in which the separating surfaces 21, 23 are located. The separating plane E runs orthogonal to the longitudinal center axis 3/rotation axis 3 of the tool 1, which in turn coincides with the longitudinal center axis 25 of the shaft 5 and the longitudinal center axis 27 of the interchangeable head 7.

The tool 1 further comprises torque transmission means for the rotationally fixed coupling of the shaft 5 0 and the interchangeable head 7, which are arranged between the shaft 5 and the interchangeable head 7 and at a radial distance from the

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Longitudinal center axis 3 of the drilling/boring tool 1 and will be explained in more detail below with reference to Figures 3 to 5. A total of three first torque transmission means 29 are provided here, which in this exemplary embodiment are arranged on the shaft 5 and are each formed by a projection 31 which extends from the first separating surface 21, that is to say protrudes from it (Figure 4). The projections 31 are - as can be seen from Figure 5 - evenly distributed from one another in the circumferential direction at a distance of approximately 120°. Each of the projections 31 is arranged at a distance x from an imaginary circumferential circle which determines the borehole diameter and which is indicated by a dashed line in Figures 3 and 5. The circumferential circle 33 is defined by the radial distance of the cutting edges 13 to 17 from the longitudinal center axis 3 of the tool 1. It is readily apparent from Figure 5 that the projections 0 31 are also spaced apart from the areas of the outer surface of the shaft 5 in which the three spiral grooves 19 are located. The projections 31 are thus practically completely surrounded by the separating surface 21 and protrude dome-like above it.

In the embodiments of the tool 1 shown in Figures 1 to 5, the projections 31 are each formed by a cylindrical pin 35, in particular a precision pin, which has a circular cross-section. The pins 35 are each inserted into a receptacle 37 formed by a bore, of which only one can be seen in partial section in Figures 1 and 4.

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The pins 35 are precisely fixed in their respective receptacles 37, for example by means of a force fit or by means of a material bond, in particular by soldering 5 or gluing. The pins 35 are therefore separate parts which are preferably only arranged after completion of the flat, first separating surface 21 on the shaft 5 in the manner described above. The first separating surface 21 can therefore be produced in a simple manner, for example by surface grinding.

Each of the first torque transmission means 29 interacts with a second torque transmission means 3 9 which, in the embodiment described with reference to Figures 1 to 5, are arranged on the interchangeable head 7, since the first torque transmission means 29 are located on the shaft 5. A total of three second torque transmission means 3 9 are therefore provided, each of which is formed by a recess 41 extending into the second separating surface 23 of the interchangeable head 7. The recesses have a circular cross-section and can be produced, for example, by drilling or - if the interchangeable head 7 is a sintered part - by sintering corresponding cores in a sintered mold. The second torque transmission means 3 9 are also arranged at a distance from the circumferential circle 3 3 which determines the borehole diameter and also at a distance from the other areas of the outer circumferential surface of the interchangeable head 7.

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As can be seen from Figure 3, the center of the recesses 41 is located on an imaginary circle 42 indicated by a dashed line, the center of which lies on the longitudinal center axis 27 of the interchangeable head 7. The circle 42 is preferably arranged concentrically to the circumferential circle 33, which means that in this embodiment the recesses 41 - like the projections 31 on the shaft 5 - have the same radial distance from the longitudinal center axis 27.

When the interchangeable head 7 and the shaft 5 are joined together, they are aligned with one another in the circumferential direction in such a way that each of the recesses 41 is located opposite the respective associated projection 31. By means of an axial relative movement between the shaft 5 and the interchangeable head 7, the projections 31 are then introduced into the recesses 41 until the separating surfaces 21, 23 lie flat against one another, as shown in Figure 1. The assignment of the projections 31 and recess 41 is carried out in such a way that when the interchangeable head 7 and the shaft 5 are joined together, they are aligned with one another in the same spiral groove. This means that the chip grooves 19, of which a first longitudinal section is arranged on the shaft 5, namely in the spiral groove area 11, and a second longitudinal section on the interchangeable head 7, namely in a spiral groove area 43, have a continuous screw shape.

0 The embodiment of the tool 1 described with reference to Figures 1 to 5 has the outer contour of a known, three-edged drilling/boring tool.

tool that is ground out of solid material, wherein the transition from the spiral groove area 43 of the interchangeable head 7 to the spiral groove area 11 of the shaft 5 is preferably designed to be stepless. In other words, the interchangeable head 7 and the shaft 5 have the same cross-sectional areas in the area of their interface (separation plane E).

A particularly advantageous feature of the design or arrangement of the torque transmission means 29, 39 according to the invention is that it creates a closed outer circumferential surface of the replaceable head 7 and the shaft 5, which, in contrast to known tools, is not interrupted by the torque transmission means 29, 39.

Although the interchangeable head 7 and the shaft 5 - seen in cross-section - have only small material or wall thicknesses, a firm and secure connection between the interchangeable head 7 and the shaft 5 can be ensured.

0 In the embodiment according to Figures 1 to 5, the interchangeable head 7 is secured to the shaft 5 by means of a screw connection in the axial direction. The screw connection is realized by a sleeve 45 arranged on the interchangeable head 7 with a threaded hole 47 provided therein, into which a threaded pull rod (not shown in the figures) is screwed. For this purpose, the shaft 5 has a stepped channel 4 9 running concentrically to its longitudinal center axis 25, which penetrates the shaft 5 0. The threaded pull rod is introduced into the channel 49 from the end of the shaft 5 facing away from the interchangeable head 7. The thread of the

The screw connection can be either a right-hand or left-hand thread. The sleeve 4 5 is only attached to the interchangeable head 7 when its separating surface 23 has been completely machined, for example by surface grinding.

As can be seen from Figure 5, the channel 49 has a circular cross-section, at least in the region of its mouth in the separating surface 21. The sleeve 45 is inserted into a recess 51 leading into the second separating surface 23 and is fixed therein, for example soldered in. The sleeve 45 projects slightly beyond the second separating surface 23 and, when the interchangeable head 7 is assembled, engages in the channel 49, preferably with little play. The longitudinal section of the sleeve 45 projecting beyond the second separating surface 23 is preferably shorter than the longitudinal section of the projections 31 projecting beyond the first separating surface 21 on the shaft 5. In another exemplary embodiment, when the interchangeable head 7 is placed on the shaft 5, the sleeve 45 first engages in the channel 49 before the projections 31 enter the receptacles 41.

It should be noted that the arrangement and design of the projections 31 and receptacles 41 on the shaft 5 or the interchangeable head 7 is preferably so precise that the interchangeable head 7 is exactly aligned with respect to the shaft 5 and, if necessary, is fixed in place by friction.

0 It is immediately clear that the arrangement of the torque transmission means 29, 39 without further

res is also interchangeable, that is, the first torque transmission means 2 9 can also be arranged on the interchangeable head 7 and the receptacles 41 on the shaft 5, which has no effect on the function of the torque transmission means 29, 39. It is also conceivable that part of the first and part of the second torque transmission means 29, 3 9 are arranged on the interchangeable head 7 and the other part of the torque transmission means on the shaft 5.

In the simplest embodiment, the drilling/boring tool 1 has two first and two second torque transmission means. Of course, more than three first and second torque transmission means can also be provided without any problem.

Figure 6 shows a top view of the separating surface 23 of a further embodiment of the interchangeable head 7. Parts that have already been described with reference to the previous figures are provided with the same reference numerals, so that reference is made to their description. In the following, only the differences are discussed in more detail. The interchangeable head 7 has a total of three first torque transmission means 29A, 29B and 29C, of which the torque transmission means 29B and 29C are identical in shape and size. They have - seen in plan view - a circular contour in the plane of the separating surface 23. The torque transmission means 29A differs from the torque transmission means 29B, 29C in that it has an oval shape and a length of

which is larger than the diameter of the torque transmission means 29B, 29C.

Figure 7A shows a cross section through the interchangeable head 7 along the section line A-A shown in Figure 6. It can be seen that the torque transmission means 29C and thus also the identically designed torque transmission means 29B are formed by a projection 31 extending from the flat separating surface 23, which is convexly curved, in particular hemispherical, and is formed in one piece with the interchangeable head 7. The first torque transmission means 29 assigned to the torque transmission means 39C and formed by a recess 41 arranged on the shaft 5 (not shown) is designed such that the projection 31 is completely received so that the first and second separating surfaces 21, 23 of the shaft 5 or the interchangeable head 7 lie flat against one another. In a preferred embodiment, the inner contour of the recess 41 corresponds to the outer contour of the projection 31, that is, the recess 41 has a concavely curved, for example spherical, in particular hemispherical, inner contour.

Figure 7B shows a cross section through the interchangeable head 7 along the section line B-B shown in Figure 6. It can be seen that the torque transmission means 29A is also formed in one piece with the interchangeable head 7 and has a convexly curved outer contour.

The fact that the torque transmission means 3 9A shown in Figure 6 and the first torque transmission means arranged on the shaft 5 which interacts with it differs in shape and size from the other torque transmission means 3 9B, 3 9C ensures that the interchangeable head 7 is always arranged in the same way on the shaft 5 and is not angularly offset in the circumferential direction, as would theoretically be possible, for example, in the exemplary embodiment described with reference to Figures 1 to 5. Due to this design of the second torque transmission means 3 9A and the associated first torque transmission means on the shaft 5, it can be ensured that the interchangeable head 7 is always connected to the shaft 5 in the same spiral groove.

Figures 8A and 8B as well as 9A and 9B each show a section of a further embodiment of the drilling/boring tool 1 according to the invention, in which the second torque transmission means 39 are arranged on the interchangeable head 7 by way of example. Their representation corresponds to the section line AA or BB marked in Figure 6. The interchangeable head 7 therefore comprises, instead of the first torque transmission means 29A to 29C, second torque transmission means 39A, 39B and 39C which, when viewed from above, have the same contour, whereby here too the torque transmission means 39 indexed with "B" and ^" C" are identically designed, while the torque transmission means 39 marked with "A" is larger and has a different shape.

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Figure 8A shows a longitudinal section through a second torque transmission means 39C, which is formed by a recess 41, which here has a hemispherical inner contour. In this embodiment, the first torque transmission means provided on the shaft 5 is correspondingly designed as a projection 39, which is preferably also spherical. A further embodiment of the second torque transmission means 39C is shown in Figure 9A, in which it is also formed by a recess 41, the base 53 of which, however, is flat and runs parallel to the second separating surface 23. The projection associated with the recess 41 is preferably formed by a pin with a circular cross-section, as described, for example, with reference to Figures 1 and 5. Both embodiments of the torque transmission means 39C have in common that they extend into the second separating surface 23.

Figure 8B shows a variant of the torque transmission means 39A, which is formed by a concavely curved recess 41. Figure 9B shows an embodiment of the torque transmission means 39A, which is formed by a recess 41 with a flat base 55 running parallel to the second separating surface 23.

All embodiments of the drilling and/or boring tool 1 described with reference to Figures 1 to 9B have in common that the first and second torque transmission means are arranged at a distance from the imaginary circumferential circle 33 determining the borehole diameter and

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furthermore, they also have a distance from the other outer areas of the tool 1. The first and second torque transmission means therefore do not extend to the outer circumferential surface of the tool 1, so that they can be designed to be closed, i.e. free of recesses. Depending on the embodiment, i.e. whether they are designed as a projection or as a recess receiving the projection, the first and second torque transmission means are embedded in the first separating surface 21 or the second separating surface 23, or extend from it.

The design of the projections 31 and recesses 41 is basically arbitrary, i.e. it is not limited to the embodiments shown in the figures. As mentioned, each projection is assigned at least one recess, with either the projection or the recess being arranged on the interchangeable head 7 and the other functional element being arranged on the shaft 5.

The drilling and/or boring tool 1 according to the invention enables a very quick change of the interchangeable head 7, which may be necessary, for example, as a result of wear or damage.

For this purpose, the shaft 5 can remain clamped in the machine tool or the like. The axial securing of the interchangeable head 7 only has to be released, which is done in the embodiments of the tool 1 described with reference to Figures 1 to 5 by unscrewing the threaded drawbar guided through the channel 49 from the sleeve 4 5 arranged in the interchangeable head 7.

The interchangeable head 7 can then be removed from the shaft 5 and replaced with a new or reground interchangeable head 7.

The shaft 5 can be made of high-speed steel (HSS) or a case-hardened steel, for example. This gives the tool 1 more axial flexibility. For example, it easily follows radial deviations in a pre-drilled hole and this flexibility prevents cutting edge breakages. The replaceable head can be made in one piece and made of hard materials, for example full PCD, full CBM or full CERMET. Replaceable heads 7 that are equipped with hard materials, such as PCD or CBM, can also be used without any problem.

The inventive design or arrangement of the torque transmission means 0 arranged between the interchangeable head 7 and the shaft 5 is not limited to 3-cutting-edge interchangeable heads as described with reference to Figures 1 to 9B, but can also be used with 1-cutting-edge and 2-cutting-edge interchangeable heads or with interchangeable heads that have more than three cutting edges.

Claims (15)

1. Drilling or boring tool ( 1 ) with a shaft ( 5 ) having a spiral groove region ( 11 ) with a front geometry which is arranged on an exchangeable interchangeable head ( 7 ), and with torque transmission means ( 29 , 39 ; 39 A to 39 C; 29 A to 29 C) between the shaft ( 5 ) and the interchangeable head ( 7 ), characterized in that the torque transmission means ( 29 , 39 ; 39 A to 39 C; 29 A to 29 C) are arranged at a distance (x) from an imaginary circumferential circle ( 33 ) determining the borehole diameter. 2. Tool according to claim 1, characterized in that the shaft ( 5 ) has a flat, first separating surface ( 21 ) and the interchangeable head ( 7 ) has a flat, second separating surface ( 23 ), which lie flat against one another in the assembled state of the interchangeable head ( 7 ). 3. Tool according to claim 2, characterized in that the first and second separating surfaces ( 21 , 23 ) are each formed by an end face of the shaft ( 5 ) and the interchangeable head ( 7 ). 4. Tool according to one of the preceding claims, characterized in that a parting plane (E) located between the shaft ( 5 ) and the interchangeable head ( 7 ), in which the first and second parting surfaces ( 21 , 23 ) lie, runs orthogonally or substantially orthogonally to the longitudinal center axis ( 3 ) of the drilling and/or boring tool ( 1 ). 5. Tool according to one of the preceding claims, characterized in that a first torque transmission means ( 29 ; 29 A to 29 C) is formed by a projection ( 31 ) extending from the first or the second separating surface ( 21 , 23 ) and a second torque transmission means ( 39 ; 39 A; 39 B; 39 C) is formed by a recess ( 41 ) extending into the second or the first separating surface ( 23 ; 21 ), wherein in the assembled state of the interchangeable head ( 7 ) the projection ( 31 ) is arranged in the recess ( 41 ), preferably with little play, in particular free of play. 6. Tool according to one of the preceding claims, characterized in that the first and second torque transmission means ( 29 , 39 ; 39 A to 39 C; 29 A to 29 C) are arranged at a radial distance from the longitudinal central axis ( 3 ) of the drilling and/or boring tool ( 1 ). 7. Tool according to one of the preceding claims, characterized in that the shape of the projection ( 31 ) and that of the recess ( 41 ) are selected such that when the interchangeable head ( 7 ) is attached to the shaft ( 5 ), the interchangeable head ( 7 ) is centered relative to the shaft ( 5 ). 8. Tool according to one of the preceding claims, characterized in that the outer contour of the projection ( 31 ) corresponds to the inner contour of the recess ( 41 ). 9. Tool according to one of the preceding claims, characterized in that the projection ( 31 ) is formed integrally with the interchangeable head ( 7 ) or the shaft ( 5 ). 10. Tool according to one of the preceding claims 1 to 8, characterized in that the projection ( 31 ) is formed by a pin ( 35 ) which, after machining of the separating surface ( 21 ; 23 ), can be introduced into a receptacle ( 37 ) provided therein. 11. Tool according to one of the preceding claims, characterized in that the projection ( 31 ) and the recess ( 41 ) have a circular cross-section. 12. Tool according to one of the preceding claims, characterized in that a plurality of first and second torque transmission means ( 29 , 39 ; 39 A to 39 C; 29 A to 29 C) are provided, which - seen in the circumferential direction of the drilling and/or construction tool ( 1 ) - are preferably arranged in a uniformly distributed manner. 13. Tool according to claim 12, characterized in that at least one first and one second torque transmission means cooperating therewith have a shape and/or size that differs from the other torque transmission means. 14. Tool according to one of the preceding claims, characterized in that the interchangeable head ( 7 ) has a spiral groove region ( 43 ) and that the shaft ( 5 ) and the interchangeable head ( 7 ) have the same cross-sectional areas at least in the region of their adjacent spiral grooves. 15. Tool according to one of the preceding claims, characterized in that it is a multiple cutter, in particular a two-cutter or three-cutter.