EP4126433A1

EP4126433A1 - Method for producing a workpiece threaded hole

Info

Publication number: EP4126433A1
Application number: EP21704523.6A
Authority: EP
Inventors: Peter Kopton
Original assignee: Audi AG
Current assignee: Audi AG
Priority date: 2020-04-01
Filing date: 2021-02-10
Publication date: 2023-02-08
Also published as: JP2023519004A; CN115335172A; JP7470812B2; US20230094117A1; DE102020109035A1; WO2021197696A1; DE102020109035B4

Abstract

The invention relates to a method for producing a workpiece threaded hole (1) by means of a tapping tool, the method comprising a drilling stroke (B), in which the rotating tapping tool is driven into the workpiece (5) in a drilling direction to an intended drilling depth (t_B), such that a screw-thread-free pilot hole (51) is formed, and comprising a screw-thread stroke (G), in which the tapping tool produces an internal screw thread (9) in the pilot hole (51) at a screw-thread advancing rate (v_f) and a screw-thread rotational speed (n), which is synchronized with the screw-thread advancing rate. According to the invention, a reversing stroke (R1) is carried out after the drilling stroke (B), in which reversing stroke the tapping tool is led out of the pilot hole (51) in a reversing direction counter to the drilling direction. Subsequently, the tapping tool executes a controlled lateral movement radially by a radial offset (Δr₁) in an offset stroke (V1). Thereafter, the radially adjusted, rotating tapping tool is guided in a circular rotational motion along a circular path (53) about the hole axis (A) in the screw-thread stroke (G).

Description

Process for creating a workpiece tapped hole

DESCRIPTION:

The invention relates to a method for producing a workpiece threaded hole according to the preamble of claim 1 and a tapping tool according to claim 19. In a generic method, when creating the workpiece threaded hole, a drilling stroke is initially carried out, in which the rotating The tapping tool is driven in one drilling direction up to a target drilling depth into the non-pre-drilled workpiece, to be precise with the formation of a thread-free pre-drilling. In addition, a thread stroke takes place in the process, in which the tapping tool generates an internal thread in the pre-hole with a thread feed and a thread speed synchronized with it.

For example, the method can be implemented as a so-called one-shot tapping process, in which both the pre-drilling (i.e. core drilling) and the generation of an internal thread are carried out in a common tool stroke. In this case, the drilling stroke and the thread stroke are temporally superimposed on one another. This leads to a high load on the tool and possibly to a reduced tool life.

Such a one-shot tapping process is known from WO 2019/029850 A1. At the end of the tapping stroke, the direction of rotation of the rotating tool is reversed. The tool is then versierhub led out of the threaded hole free of stress, namely at a reversing speed synchronized with the reversing feed, at which the thread machining teeth of the tapping tool move free of stress in the threads of the workpiece threaded hole.

The object of the invention is to provide a method for producing a workpiece threaded hole and a tapping tool in which the tool load is reduced compared to the prior art and the threaded hole can be produced in a reduced process time.

The object is achieved by the features of claim 1 or 19. Preferred developments of the invention are disclosed in the subclaims.

In a departure from the above WO 2019/029850 A1, according to the invention, both the pilot hole and the internal thread are no longer produced in the drilling stroke, which is associated with a high load on the tool. Rather, in the invention, the tapping tool is designed in such a way that the pre-drilling takes place in the drilling stroke alone. The internal thread is then generated in an independent thread stroke. According to the characterizing part of claim 1, in preparation for the thread stroke after the drilling stroke, a reversing stroke takes place in which the tapping tool is completely led out of the pre-drilling in a reversing direction opposite to the drilling direction. The tapping tool led out of the pilot hole is controlled in an offset stroke by a radial offset towards the outside radially. Then the radially controlled threaded debohr tool is guided in a circular rotary movement along a circular path around the bore axis, whereupon the thread stroke starts.

It should be emphasized that, according to the invention, the internal thread generation does not take place during the reversing stroke. In this case, a time-consuming speed control would have to be used to prepare the internal thread generation. Adaptation of the tapping tool takes place in which the tapping tool would have to be controlled from a drilling speed (from the previous drilling stroke) to a thread speed (for the subsequent generation of internal threads). In addition, with such an internal thread generation, the tapping tool would be subjected to a tensile force, as a result of which the tool is less resilient.

According to the invention, the thread stroke and the drilling stroke can have an identical stroke direction. In the drilling stroke, the tool axis around which the tapping tool rotates and the drilling axis can be coaxial with one another. In addition, in the drilling stroke, a drilling section of the tapping tool is in chip engagement with the workpiece, while a thread-generating section is carried along free of stress.

In a preferred embodiment variant, the thread stroke can be extended by a free cut stroke when the target thread depth is reached. In the free-cutting stroke, the feed and the speed of the tapping tool are no longer synchronized with one another, as a result of which a circumferential free-cut groove adjoining the internal thread is created without thread pitch. In the thread stroke, the tool axis and the bore axis are axially parallel to one another, with an axis distance that corresponds to the radial offset by which the tapping tool has been radially controlled in the offset stroke.

After the circumferential free cut groove has been generated during the free cut stroke, a second offset stroke can take place. In the second offset stroke, the tapping tool is retracted by a radial offset in the radial direction from the internal thread or from the cutout groove. This enables the tapping tool to be guided out of the threaded hole in the workpiece in a subsequent reverse stroke without stress, that is to say without thread engagement or chip engagement. To prepare for the thread stroke, the direction of rotation of the tapping tool can be reversed if necessary. The reversal of the direction of rotation can take place, for example, while the first reversing stroke is being carried out.

After the drilling stroke has been carried out, the speed of the tapping tool can be slowed down to zero and the first reversing stroke can be started.

In the thread stroke, thread cutting takes place through synchronous interpolation in an xy plane around the center point of the outer thread diameter dA and through a simultaneous synchronous movement along the drilling axis (or tool axis) with a feed rate of one pitch per revolution. The time for one revolution of the tapping tool (nw) corresponds to the time for one revolution around the center point of the outer thread diameter (CG). The infeed along the bore axis (thread feed) during this time corresponds to the thread pitch.

In the first offset stroke (i.e. between the first reversing stroke and the thread stroke) the rotating tapping tool is controlled by a radial offset and guided in a circular rotary movement along a circular path around the bore axis.

The tapping tool is designed in such a way that a tool thread generating section (required for generating internal threads) remains stress-free and disengaged from the wall of the pilot hole during the drilling stroke. In the subsequent thread stroke, however, the tool drilling section (required to generate the pilot hole) remains free of stress and except for a handle with the generated internal thread. The tool drilling section moves in the thread stroke with its cutting edges radially inside the radially inner thread apex of the internal thread. The thread stroke takes place with a tool axis which is axially parallel to the bore axis. The tapping tool has at least a first cutting edge and a second cutting edge, which are spaced apart from one another by a cutting angle in the circumferential direction of the tool. The cutting edge angle is dimensioned so that the two cutting edges can be guided out of the workpiece threaded hole in the thread stroke without stress and out of engagement with the internal thread produced.

In a technical implementation, the thread generating section formed on the tapping tool is arranged in a tool circumferential direction outside the range of rotation angle spanned by the two cutting edges.

An outer cutting edge contour of the two cutting edges moves on a circular path when the tool rotates. In the same way, when the tool rotates, a tooth contour of the tool thread generating section moves on a tooth contour circular path with a tooth contour diameter. The tooth contour diameter is designed to be smaller than the cutting contour diameter in order to support an interference contour-free clearance cut of the tapping tool in the radial direction and the second reverse stroke. In this way, there is a radial tool clearance between the cutting edge circular path and the circular tooth contour path. The tool clearance is partially used up during the clearance cut in the radial direction.

The cutting edge angle spanned between the first cutting edge and the second cutting edge can, purely by way of example, be smaller than 180 ° and, for example, be dimensioned in the range of 120 °.

Each of the cutting edges can have at least one end-face transverse cutting edge formed on the tool tip. The transverse cutting edge of each cutting edge can merge into a longitudinal cutting edge of the cutting edge at a radially outer cutting corner. In addition, in a specific embodiment variant, in each case a drill bit can be formed on a drill web running in the longitudinal direction of the tool. The two the drill webs can be spaced apart from one another in the tool circumferential direction via chip spaces. A rake face delimiting the chip space can merge (in the tool circumferential direction) at the longitudinal cutting edge into a circumferential drill web flank. Guide chamfers can project radially outward from each of the two drill web free surfaces. In addition, the tool thread generating section can be formed on one of the two circumferential drill web free surfaces.

At the tool tip of the tapping tool, a rake face delimiting the chip space can merge into an end face flank on the front side transverse cutting edge that tapers conically in the direction of the tool axis. With regard to a uniform drill bit loading, it is preferred if the first and second drill bits are arranged in different height positions in the tool axial direction, that is to say they are axially offset in height relative to one another. The axial height offset between the two cutting edges (in particular their cross cutting edges with associated cutting edge) can be dimensioned in such a way that the cutting edge loads per cutting edge in the drilling stroke are approximately the same. With drill bits that are axially offset in height, an approximately even drill bit load can be achieved, despite the drill bits that are not diametrically opposite with respect to the tool axis (as is the case in a conventional tapping tool), so that the Tooth feed per cutting edge is approximately the same. In particular, the two end-face transverse cutting edges of the cutting edges can be offset in height relative to one another in the axial direction of the tool.

An exemplary embodiment of the invention is described below with reference to the accompanying figures.

Show it:

1 shows, in a sectional side view, a threaded blind hole bore formed in a workpiece; 2 and 3 different views of a tapping tool;

4 to 8 are each views illustrating the generation of the threaded blind hole shown in FIG. 1 in a process sequence;

9 and 10 a conventional drilling tool in different views; Figures 11 to 14 show an embodiment of the invention; as

FIGS. 15 to 18 show a further embodiment of the invention.

In Fig. 1, a finished threaded blind hole 1 is shown. The hole 1 is worked with its hole bottom 3 up to a target drilling depth te in a workpiece 5 by means of a process sequence which will be explained later with reference to FIGS. 4 to 8. The threaded hole 1 has at its hole approximately opening on a circumferential counterbore 7, which merges into an internal thread 9 in the further Ver run down. The internal thread 9 extends along the bore axis A up to a usable nominal thread depth tG. As can also be seen from FIG. 1, a thread passage of the internal thread 9 opens into an annular circumferential clearance or free cut groove 13. The thread core of the internal thread 9 in FIG. 1 is on a core hole diameter dK. The thread root of the internal thread 9 lies on an outer thread diameter dA.

The threaded blind hole 1 shown in FIG. 1 is produced with the aid of a tapping tool described below with reference to FIGS. 2 and 3. Accordingly, the tool in FIG. 2 has a clamping shank 15 to which a tapping body 17 is connected. In FIG. 3, a first cutting edge S1 and a second cutting edge S2 are formed on the tapping body 17, which are spaced apart from one another in a tool circumferential direction u by a cutting angle α. The tapping tool has in Fig. 3 two in one work- tool-longitudinal direction extending drill webs 14. A cutting edge S1, S2 is formed on each of the two drill webs 14. The two drill webs 14 are spaced apart from one another in the tool circumferential direction u (FIG. 3) via chip spaces 23. Each of the cutting edges S1, S2 each has a longitudinal cutting edge 27 running in the longitudinal direction of the tool (only indicated in FIGS. 12 and 14) and an end-face transverse cutting edge 29 formed on the tool tip. The front transverse cutting edge 29 merges into the longitudinal cutting edge 27 at a radially outer cutting corner 33.

A rake face delimiting the chip space 23 merges at the longitudinal cutting edge 27 into a circumferential drill web flank 35 (FIG. 3). On the circumferential drill web open areas 35, guide chamfers 37 protruding from the side are formed in each case. In addition, a tool thread generating section 39 is formed on the wide drill web 14 (specifically on its drill web free surface 35). This consists in Fig. 3 of a total of three machining teeth, namely a pre-machining tooth 40, an intermediate tooth 41 and a finishing tooth 42. Alternatively or additionally, further teeth (such as the tooth 43 shown in Fig. 1) can be provided. The teeth 40 to 42 are arranged one behind the other in the tool circumferential direction u in FIG. 3 and are positioned approximately at the same height in the axial direction. As an alternative to this, however, the thread generating section 39 is not limited to this special embodiment variant. Rather, fewer or more cutting teeth can also be provided and / or the cutting teeth can also be arranged axially offset from one another on the drill web free surfaces 35.

The thread generating section 39 also has, viewed in the axial direction, on both sides of the machining teeth 40, 41, 42 in each case a circumferential cylindrical support web 44 (FIGS. 3 and 4), the outer diameter of which when the thread is generated (see FIG. 7) is approximately on the Pre-drilling diameter dve, so that when threading the Support web (44) of the tapping tool is supported against the wall of the pilot hole

As can also be seen from FIG. 3, an outer cutting contour of the first and second cutting edges S1, S2 moves with a tool rotation on a cutting edge circular path 45 with a cutting contour diameter (identical to core hole diameter d «). In the same way, a tooth contour of the tool thread generating section 39 moves during a tool rotation on a tooth contour circular path or envelope curve 47 (FIGS. 3 and 4) with a tooth contour diameter. In Fig. 3 or 4, the tooth contour diameter is dimensioned smaller than the cutting contour diameter (identical to the core hole diameter d «). This results in a radial tool clearance 49 (FIGS. 3 or 4) between the circular path 45 and the circular tooth contour path 47. The tool clearance 49 is required in a free travel step F (FIG. 8b) described later.

A thread generation with the aid of the tapping tool according to the invention is described below with reference to FIGS. Drilling depth te driven in to form a pilot hole 51. In the drilling stroke B, the two cutting edges S1, S2 are in cutting engagement with the workpiece 5, while the tool thread generating section 39 remains stress-free and out of engagement with the pre-drilling wall. The tool axis W is aligned coaxially to the bore axis A, the feed rate Vf and the speed n of the tapping tool are freely selectable. The drilling process takes place in FIG. 4 in the direction of rotation 38 shown, for example, counterclockwise.

After the end of the drilling stroke (FIG. 5), the thread stroke G (FIG. 8a) is prepared with the following process steps: After the drilling stroke B, a first reversing stroke R1 (FIG. 6) takes place, in which the tapping tool moves in one direction to the drilling direction opposite reversing direction is guided out of the pilot hole 51 so far that a first offset hub V1 (Figure 7) can take place. In the first offset stroke V1, the tapping tool guided out of the pilot hole 51 is controlled radially by a radial offset Dh.

Then the thread stroke starts (Figure 8a), in which the radially controlled, rotating tapping tool is guided in a circular rotary movement (Figure 7) along a circular path 53 around the bore axis A and with a thread feed and a synchronized with it Thread speed is introduced into the pilot hole 51. In the thread stroke G, the tool rotation and the tool circular movement take place both in the same direction of rotation and at the same speed, as is indicated in FIG.

In the thread stroke G (FIG. 8a), the thread generating section 39 of the tapping tool generates the internal thread 9 until the target thread depth tG is reached. When the target thread depth tG is reached, the thread stroke G is extended with a free cut stroke F (FIG. 8a). In the free cut stroke F, the feed rate Vf and the speed n of the tapping tool are no longer synchronized with one another. It is therefore generated on the internal thread 9 to closing circumferential free cut groove 13 without thread pitch.

After the circumferential free cut groove 13 has been produced, a second offset stroke V2 (FIG. 8b) follows, in which the tapping tool is moved clear of the free cut groove 13 by a radial offset DG2 in the radial direction. This enables a second reversing stroke R2 (FIG. 8b), in which the threaded drilling tool can be guided out of the workpiece threaded hole 1 without stress, that is to say without thread engagement and without chip engagement.

The following description relates specifically to the drilling process step and the drilling section of the tapping tool: In general, when designing a drilling process step, the process parameters (i.e. speed n and feed Vf of the drilling tool) correspond to the positions of the cutting edges S1, S2 on the drilling tool to agree that the cutting edge load per cutting edge S1, S2 is approximately the same, that is the feed vtz (tooth feed) per cutting edge S1, S2 is ideally the same. This is achieved in a conventional drilling tool (FIGS. 9 and 10) by constant spacing between the cutting edges S1, S2. In FIG. 9, the cutting edges S1, S2 are therefore diametrically opposite with respect to the tool axis W, so that the feed (tooth feed) per cutting edge S1, S2 is approximately the same, as can be seen from FIG. 10. In Fig. 10, the lateral surface of the conventional drilling tool is shown in a development. Accordingly, the cutting edges S1, S2 are positioned at the same axial height H. The cutting edges S1, S2 in FIG. 10 are each in chip engagement with the inner wall of a workpiece bore over identical cutting widths s. In FIG. 10, the cutting paths wi and W2 of the two cutting edges S1, S2 resulting in the drilling process are shown. The cutting paths wi and W2 run spirally along the inner wall of the bore at an angle of inclination β, so that in the development (FIG. 10) a straight course of the cutting paths wi and W2 results. The cutting paths wi and W2 do not overlap in FIG. 10, but rather go into one another in the axial direction without overlapping.

In the embodiment of FIGS. 11 to 14 - in contrast to the prior art according to FIGS. 9 and 10 - the spacings between the two cutting edges S1, S2 are no longer identical, but different. Correspondingly, in FIG. 12 the feed rate ftz per cutting edge is no longer the same for each cutting edge, but rather different. This means that in FIG. 12, the cutting edges S1, S2 are no longer evenly loaded in the drilling process, but are loaded differently. According to FIG. 12, the first cutting edge S1 is assigned the largest feed vtz per cutting edge, that is, the first cutting edge S1 is exposed to the greater cutting edge load. In FIG. 12, the two cutting edges S1, S2 are positioned at the same height H without an axial height offset DH. According to FIGS. 13 and 14, each transverse cutting edge 29 of each cutting edge S1, S2 with the tool axis W spans a point angle βi, β2. The point angles ßi, ß2 of the two cutting edges S1, S2 are shown in Fig. 14 (as with conventional drilling tools with symmetrical cutting edge distribution) sized identically. The point angles ßi, ß2 are selected so that the axial height offset DH is set at the tool circumference, i.e. at the cutting corners 33 of the two cutting edges S1, S2, or the different height positions H1, H2 of the cutting edges S1, S2, as shown in FIG.

In order to ensure an approximately even load on the cutting edges S1, S2 despite the different spacing, the cutting edges S1, S2 are no longer positioned at the same axial height H in the exemplary embodiment of FIGS H2 arranged. These height positions H1 and H2 are selected in such a way that, in comparison to FIGS. 11 and 12, the result is a more even cutting edge load on the two cutting edges S1, S2. The height positions H1 and H2 are selected depending on the process parameters in the drilling process (i.e. tool speed, tool feed) and depending on the respective pitch.

As can be seen from FIG. 16, the cutting edges S1, S2 - analogously to FIGS. 9 and 10 - are each in cutting engagement with the inner wall of the bore over identical cutting widths s. In addition, in FIG. 14 the cutting paths wi and W2 do not overlap, but rather they merge into one another without overlapping.

According to FIGS. 17 and 18, each transverse cutting edge 29 of each cutting edge S1, S2 with the tool axis W spans a point angle β1, β2. The point angles ßi, ß2 of the two cutting edges S1, S2 are not measured identically in FIG. 18 (as in conventional drilling tools with symmetrical cutting edge distribution), but rather measured differently from one another. The tip angles ßi, ß2 are chosen so that the axial height offset DH on the tool circumference, that is, at the cutting corners 33 of the two cutting edges S1, S2, or the different height positions H1, H2 of the cutting edges S1, S2 are set as shown in FIG. REFERENCE LIST

1 threaded hole

3 bottom of the hole

5 workpiece

7 Counterbore

8 chamfer 9 internal thread

13 circumferential free cut groove

14 drill bars

15 clamping shank 17 tool body

14, 16 Drill webs S1, S2 Drill cutting edges 23 Chip space 25 Longitudinal cutting edge

29 Cross cutting edge

30 End face 33 cutting corner 35 Drill web open face

37 guide chamfers

38 Direction of rotation in the drilling stroke

39 Tool threading section

40, 41, 42 cutting teeth of the thread generating section

43 alternative cutting tooth

44 Support base

45 Cutting edge circular path 47 Envelope curve of the thread generating section 39 49 Tool clearance 51 Pre-drilling 53 Circular circular path

ΪB Target drilling depth dK Core diameter u Tool circumferential direction a cutting angle

A hole axis

W tool axis

B drilling stroke G thread stroke F free cut stroke

V1, V2 offset stroke Dh, DG2 radial offset

DH Height offset H1, H2 Height positions ßi, ß2 point angle

Vf feed tG nominal thread depth

Claims

PATENT CLAIMS:

Method for producing a workpiece threaded hole (1) by means of a tapping tool, with a drilling stroke (B), in which the rotating tapping tool is driven into the workpiece (5) in a drilling direction up to a target drilling depth (te) , namely under formation of a thread-free pilot hole (51), and with a thread dehub (G), in which the tapping tool with a thread feed (vf) and a thread speed (n) synchronized with it has an internal thread (9 ) generated in the pilot hole (51), characterized in that to prepare the thread stroke (G) after the drilling stroke (B), a reversing stroke (R1) takes place, in which the tapping tool in a reversing direction opposite to the drilling direction from the pilot hole ( 51) is brought out so far that the thread tapping tool is controlled radially in an offset stroke (V1) by a radial offset (Dp), and that in the thread stroke (G) the radially controlled, rotating tapping tool is in a circle r rotary movement is guided along a circular path (53) around the bore axis (A), and that in the thread stroke (G) the tool rotation and the tool circular movement take place in the same direction and at the same speed.

Method according to claim 1, characterized in that the thread stroke (G) and the drilling stroke (B) have an identical stroke direction, and / or that in the thread stroke (G) a thread generating section (39) of the tapping tool down to a target - Thread depth (tG) generates the internal thread (9), and that in particular the thread stroke (G) is extended by a free cut stroke (F) when the target thread depth (tG) is reached, at which the feed rate (vf) and the speed (n) of the tapping tool are no longer synchronized with one another and, in particular, a circumferential free cut groove (13) without thread pitch, which closes on the internal thread (9), is generated. Method according to Claim 2, characterized in that, after the free cut stroke (F), a second offset stroke (V2) takes place in preparation for a reversing stroke (R2), in which the tapping tool is offset by a radial offset (DG2) in the radial direction from the internal thread (9 ) or is cleared from the free cut groove (13) so that the tapping tool can be removed from the threaded hole (1) of the workpiece in the reversing stroke (R2) without stress, i.e. without thread engagement or chip engagement.

Method according to one of the preceding claims, characterized in that in the drilling stroke (B) a drilling section (S1, S2) of the tapping tool is in chip engagement with the workpiece (5) and the thread-generating section (39) is carried along free of stress, and / or that In the thread stroke (G) the thread generating section (39) is in form and / or cutting engagement with the inner wall of the pilot hole and the drilling section (S1, S2) is carried along free of stress.

Method according to one of the preceding claims, characterized in that in the drilling stroke (B) the tool axis (W) and the drilling axis (A) are coaxial with one another, and / or that in the thread dehub (G) the tool axis ( W) and the bore axis (A) are axially parallel to one another, with a center distance that corresponds to the radial offset (An).

Method according to one of Claims 1 to 5, characterized in that the drilling section (S1, S2) of the tapping tool has at least one first cutting edge (S1) and one second cutting edge (S2) which extend in the circumferential direction of the tool (u) a cutting angle (a) are spaced apart, and that the cutting angle (ot) is dimensioned so that the two cutting edges (S1, S2) in the thread stroke (G) are free of stress and disengaged from the internal thread (9) generated in the workpiece -Threaded hole (1) are insertable.

7. The method according to claim 6, characterized in that the tool thread generating section (39) is arranged in the tool circumferential direction (u) outside the angle of rotation range (a) spanned by the two cutting edges (S1, S2).

8. The method according to claim 6 or 7, characterized in that the first and second cutting edges (S1, S2) move during a tool rotation on a common circular path (45) with a cutting edge diameter (d «), and that in particular in the drilling stroke (B) the tool thread generating section (39) moves to an outer diameter which is smaller than the pilot hole diameter (dve).

9. The method according to any one of the preceding claims, characterized in that the tool thread generating section (39) has at least one, in particular several thread teeth (40, 41, 42), and / or that each machining tooth (40, 41, 42) on one own tooth contour diameter, the difference being the oversize between two consecutive thread teeth and / or that the machining tooth trailing in the direction of rotation (38) as the last machining tooth (42) is a finishing tooth whose tooth contour diameter is larger is than the tooth contour diameter of the leading machining tooth (41, 42), and / or that the thread teeth (40, 41, 42) lie on an envelope curve (FIG. 4; 47).

10. The method according to claim 9, characterized in that the cutting geometry of the machining tooth (40, 41, 42) is designed so that the machining tooth (40, 41, 42) is drawn into the material of the pilot hole wall during thread generation, whereby the tapping -Tool is acted upon by a lateral deflection force, and that for a deflection force compensation of the tool thread generating section (39) at least one circumferentially attached has arranged support base (44), the outside diameter of which is approximately on the pre-drilling diameter (dve) when the thread is generated, so that the support base (44) of the tapping tool is supported against the pre-drilling wall when the thread is generated.

11. The method according to claim 10, characterized in that, viewed in the axial direction, at least one support base (44) is formed on both sides of the machining tooth (40, 41, 42).

12. The method according to any one of claims 6 to 11, characterized in that the first and second drill bits (S1, S2) in the tool axial direction in different height positions (H1, H2), that is to each other with an axial height offset (DH) , and that in particular the axial height offset (DH) between the drill bits (S 1, S2) is dimensioned such that the drill bit loads per drill bit (S1, S2) in the drilling stroke (B) are approximately the same.

13. The method according to any one of claims 6 to 12, characterized in that each cutting edge (S 1, S2) has at least one end-face transverse cutting edge (29) formed on the tool tip, and that in particular the transverse cutting edges (29) of both cutting edges (S1 , S2) are vertically offset from one another by a height offset (DH) in the tool axial direction.

14. The method according to claim 13, characterized in that the transverse cutting edge (29) of each cutting edge (S1, S2) merges into a longitudinal cutting edge (Fig. 14: 27) at a radially outer cutting corner (33), and / or that the cutting edge (S1, S2) are each formed on drill webs (14) running in the longitudinal direction of the tool, and that the drill webs (14) are spaced from one another in the tool circumferential direction (u) via chip spaces (23), and / or that one of the Chip space (23) delimiting the rake face on the longitudinal cutting edge (27) in a circumferential drill web flank (35) and / or that guide chamfers (37) protrude from the circumferential drill web open surfaces (35), and / or that the tool thread generating section (39) is formed on a circumferential drill web open surface (35).

15. The method according to claim 14, characterized in that the transverse cutting edge (29) of each cutting edge (S1, S2) with the tool axis (W) spans a point angle (ßi, ß2), and that the Spit zenwinkel (ßi, ß2) the cutting edges (S1, S2) are the same, or that the point angles (ßi, ß2) of the cutting edges (S1, S2) are different, whereby the axial height offset (DH) at the tool circumference, i.e. at the cutting corners (33) the cutting edges (S1, S2) or the different height positions (H1, H2) of the cutting edges (S1, S2) result.

16. The method according to claim 15, characterized in that at the tool tip a rake face delimiting the chip space (23) on the end-face transverse cutting edge (29) merges into an end-face flank (30) which is conical in the direction of the tool axis (W) to running.

17. The method according to any one of the preceding claims, characterized in that the process steps for generating the threaded bore are carried out by means of a CNC control.

18. The method according to any one of claims 1 to 16, characterized in that some process steps for generating the threaded hole are carried out by means of a receptacle in which the tool can be mechanically controlled, and that in particular before the thread hub (G), a direction of rotation of the threaded hole is reversed -Tool it follows, for example during the first reversing stroke (R1), and that in particular the reversal of the direction of rotation is used as a signal for modulating the radial offset (An).

19. Tapping tool for performing a method for generating a workpiece threaded hole (1) according to one of the preceding claims.