Tapping tool and method for producing a threaded hole

Abstract

The invention relates to a tapping tool for producing a threaded hole (1) in a workpiece, the internal thread (9) of the workpiece threaded hole having a thread outer diameter (d A ) and a thread inner diameter (d K ). According to the invention, the tapping tool (23) has a plurality of inner diameter cutting edges (34) between a thread generation section (29) and a counterbore cutting edge (49). During the tapping stroke (G), the inner diameter tools (34) are guided into the thread grooves (15) of the rough profile (8) of the internal thread blank. During the retraction stroke (F), the inner diameter tools (34) remove the diameter allowance (Δd) at the radially inner thread crest (21) by cutting until the thread inner diameter (d K ).

Description

Field of the Invention

[0001] The present invention relates to a tapping tool and a method for producing a threaded hole in a workpiece. Background Art

[0002] In a so-called one-shot tapping process, a tapping tool performs both a pilot hole drilling (i.e., drilling a pilot hole) and an internal thread generation with a common tool stroke (i.e., a tapping stroke). For this purpose, the tapping tool has at least one pilot hole cutting edge and a thread generation section with at least one machining tooth. In this method, first, a tapping stroke is performed, in which the tapping tool can enter a workpiece without a pre-drilled pilot hole until a rated thread depth is reached. When the rated thread depth is reached, a retraction stroke follows, in which the rotational speed of the tapping tool is braked and the direction of rotation is reversed. After the direction of rotation is reversed, a reverse stroke is performed, in which the tapping tool can be guided out of the workpiece threaded hole in the opposite direction of rotation. At this time, the machining teeth of the thread generation section move without load in the thread grooves of the internal thread.

[0003] This type of tapping tool has an end-side pilot hole cutting edge at its drill tip for generating a pilot hole. A thread generation section is provided axially offset relative to the drill tip. In the tapping stroke, an internal thread rough profile is generated on the pilot hole wall using the thread generation section, where the diameter at which the radially inner thread crest is located is smaller than the inner diameter of the thread to be produced by a diameter allowance. In addition, the tapping tool has a counterbore cutting edge, by means of which a thread counterbore can be generated at the opening edge of the workpiece threaded hole.

[0004] In the prior art, the pilot hole generated in the tapping stroke already has the inner diameter of the thread. In this case, the radially outer pilot hole cutting corner up to which the end-side pilot hole cutting edge extends lies on the pilot hole diameter. The correspondingly large cutting edge length of the pilot hole cutting edge is subject to a correspondingly large cutting edge load during the tapping stroke.

[0005] This type of tapping tool is known, for example, from EP 3 458 219 B1 and EP 3 484 647 B1. Summary of the Invention

[0006] It is an object of the present invention to provide a tapping tool and a method for producing a threaded hole in a workpiece, in which the tool load is reduced during the tapping process.

[0007] According to one aspect of the present invention, the tapping tool has a plurality of inner diameter cutting edges between the thread generating section and the counterbore cutting edge in the tool axial direction. These inner diameter cutting edges can generate the inner diameter of the thread independently of the bottom hole diameter of the bottom hole cutting edge on the end side during the tapping stroke. The inner diameter cutting edges are guided within the thread grooves of the inner thread rough profile during the tapping stroke. Immediately after the tapping stroke, a retraction stroke is performed in the same stroke direction. During this retraction stroke, the inner diameter cutting edges remove the diameter allowance at the radially inner thread crest by machining until the inner diameter of the thread.

[0008] In one technical implementation, each inner diameter cutting edge can be configured on the ridge surface of the hole drilling rib of the tapping tool. Here, the inner diameter cutting edge projects radially outward from the cutting edge bottom by the cutting edge height.

[0009] The cutting edge geometry of the inner diameter cutting edge is advantageous for reliably generating an internal thread in the threaded hole of the workpiece: Therefore, each inner diameter cutting edge can have a radially outer longitudinal cutting edge extending along the tool axis. These longitudinal cutting edges can be located on the inner diameter of the thread. The longitudinal cutting edges can converge with a cutting edge side at a cutting angle facing the drill tip. In the same way, the longitudinal cutting edges can converge with a cutting edge side at a cutting angle facing the tool shank. The two cutting edge sides of the inner diameter cutting edge can transition to the cutting edge bottom in an inclined extension manner, and the cutting edge bottom is located on the cutting edge bottom diameter.

[0010] During the retraction stroke, the cutting edge side facing the drill tip, the cutting angle facing the drill tip, and the longitudinal cutting edge of the corresponding inner diameter cutting edge are in action to remove the diameter allowance.

[0011] To produce the bottom hole, the bottom hole cutting edge on the end side of the tapping tool can converge with a secondary cutting edge extending along the tool axis at a radially outer bottom hole cutting angle. The radially outer bottom hole cutting angle is located on the bottom hole diameter. According to the present invention, the bottom hole diameter is smaller than the inner diameter of the thread. The bottom hole diameter can also be smaller than or larger than the cutting edge bottom diameter, or alternatively can be the same as the cutting edge bottom diameter.

[0012] The inner diameter cutting edges can be spaced apart from each other along the tool axis by a cutting edge clearance. The cutting edge clearance is dimensioned such that during the tapping stroke, each inner diameter cutting edge extends into the thread groove of the inner thread rough profile. The number of inner diameter cutting edges can be at least corresponding to the number of thread grooves.

[0013] The above-mentioned tool geometry has the following advantages during the tapping stroke: The chips generated during the tapping stroke are thus conveyed out of the threaded hole in a chip evacuation direction opposite to the tapping stroke. By means of the inner diameter cutting edge that extends into the thread groove during the tapping stroke, it is reliably prevented that chips enter the previously generated thread rough profile and damage the previously generated thread rough profile.

[0014] Since the bottom hole diameter is smaller than the inner diameter, the feed force and the torque during the tapping stroke can be designed to be lower than in the prior art.

[0015] In a first embodiment variant, the inner diameter cutting edges can be located on the same inner diameter along the tool axis. Alternatively thereto, the inner diameter of the inner diameter cutting edges can vary along the tool axis.

[0016] In a first embodiment variant, during the tapping stroke, the inner diameter cutting edges can be guided into the thread grooves of the inner thread rough profile without cutting engagement. In this case, it is preferred that, during the tapping stroke, the cutting edge flanks of the inner diameter cutting edges can rest on the thread flanks of the previously generated inner thread rough profile. In this way, lateral guidance of the tapping tool is provided during the tapping stroke.

[0017] In an embodiment variant, the cutting edge bottom diameter of the inner diameter cutting edges can be smaller than or equal to the bottom hole diameter of the bottom hole cutting angle.

[0018] In a second embodiment variant, during the tapping stroke, the inner diameter cutting edges can be guided into the thread grooves of the inner thread rough profile not without a cutting effect but rather with a cutting effect. In this case, a first material removal can be carried out during the tapping stroke, wherein the inner diameter cutting edges (especially their cutting edge bottoms) remove a part of the diameter allowance. A second material removal can be carried out during the subsequent retraction stroke, wherein the inner diameter cutting edges (especially their longitudinal cutting edges) remove the remaining part of the diameter allowance.

[0019] In a further embodiment variant, the thread generation section can be configured with at least one reverse tooth. During the tapping stroke, the reverse tooth does not engage in cutting with the workpiece. Only during the reverse stroke can the reverse tooth remove or shape away possible additional remaining side allowances from, for example, the thread flanks facing the chips, thereby enabling the machining of the internal thread of the workpiece to be completed.

[0020] The following is a description of a preferred process sequence for producing a threaded hole: Drilling and tapping are carried out in one operation (i.e., during the tapping stroke). During the tapping stroke, the inner diameter cutting edge moves protectively within the thread profile and prevents chips from entering and damaging the previously produced thread profile. Different from the prior art, the pilot hole cutting edge does not produce the inner diameter, but produces a smaller pilot hole diameter. Since the pilot hole diameter is smaller than the inner diameter, the feed force and torque can be lower than in the prior art. At the rated thread depth, a retraction stroke is carried out, during which the synchronization of the feed and the rotational speed is cut off. When the tool feed is braked, a retraction groove is produced similarly to the prior art; additionally, the inner diameter cutting edge cuts out the inner diameter. The inner diameter cutting edge can be arranged such that the inner diameter can vary along the thread. During the retraction stroke, the rotational direction of the tool is reversed. In addition, the opposite tool feed is switched on, synchronization is carried out, and the tool is guided out of the hole without force through the previously produced thread profile. The tool can be designed such that the thread profile produced during the tapping stroke is not finish-machined. If necessary, finish machining can be carried out when the tool is guided out of the hole after the machining allowance has been offset along the tool axis in the retraction groove. Description of the Drawings

[0021] Embodiments of the present invention will be described below with reference to the accompanying drawings. Among them:

[0022] Figure 1 A side sectional view showing a threaded blind hole formed in a workpiece;

[0023] Figure 2 and Figure 3 Showing different views of the tapping tool;

[0024] Figure 4 The tapping tool is shown in a highly simplified equivalent diagram, and only the geometric shape features related to the present invention are shown in the drawing plane;

[0025] Figures 5 to 8 Showing the production of Figure 1 The threaded blind hole shown in; and

[0026] Figures 9 to 12 Showing another embodiment of the present invention. Detailed Description of the Invention

[0027] Figure 1 The completed workpiece threaded hole 1 is shown. By means of a so-called one-shot drilling process, the hole 1 with a hole bottom 3 up to the target hole depth t B is machined into the workpiece 5, and this one-shot drilling process will be described later in connection with Figures 4 to 8is explained. The threaded hole 1 has a circumferential countersink 7 at its orifice, and in further extension, the threaded hole transitions downward to an internal thread 9. The internal thread 9 extends along the hole axis B up to the available rated thread depth t G . It can be further seen from Figure 1 that the thread grooves 15 of the internal thread 9 with a thread tail portion 11 lead into a circumferential relief groove 13, which has no pitch and is constructed between the internal thread 9 and the hole bottom 3 when viewed in the axial direction. The thread groove 15 has a radially outer thread root 17 and lateral upper and lower thread flanks 18, 19 that transition radially inward to the thread core / thread core (Gewindekern) 20. The thread root 17 is located at the outer diameter d A while the thread core 21 is located at the internal thread diameter d K . Figure 1 The upper thread flank 19 in Figure 1 is the thread flank facing the chips during tapping, while

[0028] The workpiece threaded hole 1 shown in Figure 2 , Figure 3 and Figure 4 is machined with the tapping tool 23 described below in connection with Figure 1 . Thus, Figure 2 the tool 23 in Figure 3 has three circumferentially uniformly distributed end-side and laterally extending bottom-hole cutting edges 27 at its drill tip 25 and a thread generation section 29 trailing in the tapping direction ( Figure 3 ).

[0029] In Figure 3 , the tool 23 includes a tool shank 24 and an adjacent tapping tool body 26, and a total of three circumferentially distributed chip flutes 28 extend along the tool axis W to the corresponding end-side bottom-hole cutting edges 27 at the drill tip 25. At each bottom-hole cutting edge 27, the rake face 31 defining the chip flute 28 of the drill tip 25 and the end-side flank 33 ( Figure 2 ) converge. In the circumferential direction of the tool, the respective chip flutes 28 are bounded by hole-drilling ribs 35. Figure 2 and Figure 3 The tapping tool 23 shown in Figure 3 has a total of three hole-drilling ribs 35. The rake face 31 of the chip flute 28 transitions to the outer circumferential ridge face 37 of the corresponding hole-drilling rib 35 in the case of forming a secondary cutting edge 36. In Figure 3 , the secondary cutting edge 36 and the end-side bottom-hole cutting edge 27 converge at a radially outer bottom-hole cutting angle 39.

[0030] On the ridge surface 37 on each outer peripheral side of the three hole-drilling type ribs 35, the thread generating sections 29 respectively have machining teeth 41, 42, 43. The machining teeth 41, 42, 43 are implemented with different geometries and are spaced apart at different axial distances from the drill tip 25 so as to generate Figure 1 the thread grooves 15 of the internal thread 9 shown in

[0031] The tapping tool 23 has a counterbore cutting edge 49 at the transition between the tapping tool base body 26 and the tool shank 24 for forming Figure 1 the thread counterbore 7 shown in

[0032] It is further known from Figure 3 that internal diameter cutting edges 34 are respectively formed on the ridge surface 37 on the outer peripheral side of the hole-drilling type rib 35, and these internal diameter cutting edges respectively project radially outward from the cutting edge bottom 38 by the cutting edge height.

[0033] In Figure 4 , each internal diameter cutting edge 34 has a radially outer longitudinal cutting edge 40 extending along the tool axis W, and the longitudinal cutting edge is located on the thread internal diameter d K . The longitudinal cutting edge 40 transitions to the first cutting edge side 46 at the cutting angle 44 facing the drill tip 25. In the same way, the cutting edge 40 transitions to the second cutting edge side 50 at the cutting angle 48 facing the tool shank 24. The two cutting edge sides 46, 50 converge with the cutting edge bottom 38, and the cutting edge bottom is located on the cutting edge bottom diameter d SG .

[0034] The end-side bottom hole cutting edge 27 transitions to the secondary cutting edge 36 at the radially outer bottom hole cutting angle 39. The radially outer bottom hole cutting angle 39 is located on the bottom hole diameter d VB .

[0035] It can be further seen from Figure 3 or Figure 4 that the internal diameter cutting edges 34 are spaced apart from each other by the cutting edge clearance 51 along the tool axis W. The cutting edge clearance 51 is dimensioned in such a way that in the tapping stroke G described below ( Figure 5 or Figure 6 ), each internal diameter cutting edge 34 extends into the thread groove 15 of the internal thread rough profile 8. The number of the internal diameter cutting edges 34 is at least corresponding to the number of the thread grooves 15 to be generated.

[0036] Hereinafter, a method for generating Figures 5 to 8 the workpiece thread hole 1 shown in Figure 1 will be described in conjunction with Figure 5 or Figure 6) enters into the workpiece 5. During the tapping stroke G, the pilot hole cutting edge 27 produces a pilot hole 30 with a pilot hole diameter of d VB ([ Figure 5 or Figure 6 ). The subsequent thread generation section 29 produces an internal thread rough profile 8 ([ Figure 6 or Figure 7 ) on the inner wall portion of the pilot hole 30. The tapping stroke G is performed in the tapping feed condition and at a tapping rotational speed synchronized therewith along the tapping rotation direction, more precisely until the rated thread depth t G is reached. During the above-mentioned thread forming stroke G, the inner diameter cutting edge 34 is guided into the thread groove 15 of the internal thread rough profile 8 without a cutting engagement. As Figure 5 and Figure 6 show, the cutting edge sides 46, 50 of the inner diameter cutting edge 34 are supported on the thread flank sides 18, 19 of the thread groove of the internal thread rough profile 8.

[0037] In Figures 4 to 8 's embodiment, the cutting edge bottom diameter d SG of the inner diameter cutting edge 34 is smaller than the pilot hole diameter d VB of the pilot hole cutting angle 39.

[0038] In Figure 6 , the tapping tool 23 at the end of the tapping stroke G is shown. Immediately thereafter, a retraction stroke ([ Figure 6 and Figure 7 ) is performed. Different from the tapping stroke G, in the retraction stroke, the synchronization of the feed and the rotational speed is cut off. In the retraction stroke F, the rotational speed of the tapping tool 23 is braked and the rotation direction is reversed. At the same time, the counterbore cutting edge 49 produces a surrounding thread counterbore 7. In addition, in the retraction stroke F, the inner diameter cutting edge 34 removes the diameter allowance Δd at the radially inner thread crest 21 ([ Figure 5 and Figure 6 ) by cutting until the thread inner diameter d K . The material removal of the diameter allowance Δd performed in the retraction stroke F is carried out by the cutting edge side 46 of the corresponding inner diameter cutting edge 34 facing the drill tip 25, by the cutting angle 44 facing the drill tip 25, and by the longitudinal cutting edge 40.

[0039] In the internal thread rough profile 8, the radially inner thread crest 21 ([ Figure 5 and Figure 6 ) is located on the diameter d S , which corresponds to the pilot hole diameter d VB , and this diameter is smaller than the thread inner diameter d K by the diameter allowance Δd.

[0040] In the retraction stroke F ([ Figure 5 andFigure 6 ) In order to prepare for the reverse stroke R Figure 8 ) the direction of rotation is reversed. In the reverse stroke R, the tapping tool 23 is guided out of the threaded hole 1 in the reverse direction, more precisely with an opposite reverse feed and a synchronized reverse rotational speed. These parameters are dimensioned such that the thread generating section 29 of the tapping tool 23 is led out of the thread groove 15 of the internal thread 9 with substantially no load.

[0041] In the reverse stroke R( Figure 8 ) the machining teeth 41, 42, 43, the bottom hole cutting edge 27, the secondary cutting edge 36 and the inner diameter cutting edge 34 are led out of the threaded hole 1 without load.

[0042] Hereinafter, the structure and mode of operation of the tapping tool 23 according to a further embodiment will be described in conjunction with Figure 9 the description. Figure 9 The tapping tool 23 shown in Figure 9 and Figure 10 corresponds to the tapping tool in the previous figure. Therefore, reference is made to the previous description.

[0043] In Figure 11 and Figure 12 an alternative embodiment is shown, in which the tapping tool 23 corresponds essentially to that shown in the previous figure. Therefore, reference is made to the previous description. The difference from the embodiment in Figures 4 to 8 is as follows: Figure 11 and Figure 12 the cutting edge bottom diameter d SG of the inner diameter cutting edge 34 is not less than the bottom hole diameter d VB of the bottom hole cutting edge 39 but greater than the bottom hole diameter. Thereby, the cutting edge bottom 38 of the inner diameter cutting edge 34 engages in cutting with the rough profile 8 of the internal thread during the tapping stroke G( Figure 11 ). In the tapping stroke G shown in Figure 11 the first material removal M1 is achieved, in which the cutting edge bottom 38 of the inner diameter cutting edge 34 removes a part of the diameter allowance Δd. In the subsequent retraction stroke F, the second material removal M2 is achieved, in which the longitudinal cutting edge 40 of the inner diameter cutting edge 34 removes the remaining part of the diameter allowance Δd.

[0044] List of reference numerals

[0045] 1 Threaded hole

[0046] 3 Hole bottom

[0047] 5 Workpiece

[0048] 7 Countersunk threaded hole

[0049] 8 Internal thread rough profile

[0050] 9 Internal thread

[0051] 11 Thread run-out section

[0052] 13 Relief groove

[0053] 15 Thread groove

[0054] 17 Root of the thread on the radial outside

[0055] 18, 19 Thread flank

[0056] 20 Thread core

[0057] 21 Thread crest

[0058] 23 Tapping tool

[0059] 24 Tool shank

[0060] 25 Drill point

[0061] 27 Bottom hole cutting edge

[0062] 29 Thread generation section

[0063] 26 Tapping tool substrate

[0064] 28 Chip flute

[0065] 30 Bottom hole

[0066] 31 Front cutting face

[0067] 33 Rear cutting face on the end side

[0068] 34 Inner diameter cutting edge

[0069] 35 Hole drilling rib

[0070] 36 Subordinate cutting edge

[0071] 37 Ridge surface on the outer peripheral side

[0072] 38 Bottom of the cutting edge

[0073] 39 Radial outside bottom hole cutting angle

[0074] 40 Longitudinal cutting edge

[0075] 41, 42, 43 Machining teeth

[0076] 44 Cutting angle

[0077] 46 First cutting edge flank

[0078] 48 Cutting angle

[0079] 49 Counterbore cutting edge

[0080] 50 Second cutting edge flank

[0081] 51 Cutting edge clearance

[0082] 69 Reverse teeth

[0083] d SG Cutting edge bottom diameter

[0084] d VB Pilot hole diameter

[0085] d A Thread outside diameter

[0086] d I Thread inside diameter

[0087] d K Thread inside diameter

[0088] d S Thread crest diameter

[0089] Δd Diameter allowance

[0090] Δz Flank allowance

[0091] G Tapping stroke

[0092] F Retracting stroke

[0093] R Reverse stroke

[0094] B Hole axis

[0095] W Tool axis

[0096] M1 First material removal

[0097] M2 Second material removal

Claims

1. A tapping tool for producing a threaded hole (1) in a workpiece, the internal thread (9) of the workpiece threaded hole having a thread outer diameter (d A ) and a thread inner diameter (d K ), wherein, The tapping tool (23) can enter the workpiece (5) without a pre-drilled bottom hole during the tapping stroke (G) until the rated thread depth (t G ) is reached. During the retraction stroke (F) following the reaching of the rated thread depth (t G ), the rotational speed of the tapping tool (23) is braked and the direction of rotation is reversed. During the reverse stroke (R), the tapping tool (23) can be guided out of the workpiece thread hole (1) in the opposite direction of rotation. At least one end-side bottom-hole cutting edge (27) for producing a bottom hole (30) is formed on the drill tip (25) of the tapping tool (23). A thread-producing section (29) having at least one machining tooth (41, 42, 43) is formed axially offset relative to the drill tip (25). During the tapping stroke (G), the thread-producing section can be used to produce a rough internal thread profile (8) in the bottom-hole wall. The radially inner thread crest (21) is located on the crest diameter (d S ), which is smaller than the thread inner diameter (d K ) by a diameter allowance (Δd). The tapping tool (23) has at least one counterbore cutting edge (49), and a thread counterbore (7) can be produced at the opening edge of the workpiece thread hole (1) by means of the counterbore cutting edge. It is characterized in that the tapping tool (23) has a plurality of inner-diameter cutting edges (34) in the tool axial direction (W) between the thread-producing section (29) and the counterbore cutting edge (49). During the tapping stroke (G), the inner-diameter cutting edges (34) are guided into the thread grooves (15) of the rough internal thread profile (8). During the retraction stroke (F), the inner-diameter cutting edges (34) remove the diameter allowance (Δd) at the radially inner thread crest (21) by cutting until the thread inner diameter (d K ). The inner-diameter cutting edges (34) radially extend outward from the cutting-edge bottom (38) at the cutting-edge height, and the cutting-edge bottom is located on the cutting-edge bottom diameter (d SG ). Each inner-diameter cutting edge (34) has a radially outer longitudinal cutting edge (40) extending along the tool axis (W), and the longitudinal cutting edge is located on the thread inner diameter (d K ).

2. The tapping tool according to claim 1, wherein Each inner-diameter cutting edge (34) is constructed on the ridge surface (37) of the hole-drilling rib (35) of the tapping tool (23).

3. The tapping tool according to claim 2, characterized in that, The longitudinal cutting edge (40) merges with the cutting-edge flank (46) at a cutting angle (44) facing the drill tip (25), and / or the cutting edge (40) merges with the cutting-edge flank (50) at a cutting angle (48) facing the tool shank (24), and the cutting-edge flanks (46, 50) transition into the cutting-edge bottom (38).

4. The tapping tool according to claim 3, characterized in that, The material removal of the diameter allowance (Δd) carried out during the retraction stroke (F) is effected by the cutting-edge flank (46) of the respective inner-diameter cutting edge (34) facing the drill tip (25), by the cutting angle (44) facing the drill tip (25), and by the longitudinal cutting edge (40).

5. The tapping tool according to any one of the preceding claims, characterized in that, The bottom hole cutting edge (27) on the end side converges with a secondary cutting edge (36) extending along the tool axis (W) at a bottom hole cutting angle (39) radially outside, and the radially outside bottom hole cutting angle (39) is located on the bottom hole diameter (d VB ).

6. The tapping tool according to claim 1, characterized in that, The inner-diameter cutting edges (34) are spaced from one another along the tool axis (W) via a cutting-edge clearance (51), and during the tapping stroke (G), each inner-diameter cutting edge (34) projects into the thread groove (15) of the inner-thread rough profile (8), and / or the number of the inner-diameter cutting edges (34) corresponds at least to the number of the thread grooves (15) in the workpiece thread hole (1).

7. The tapping tool according to claim 1, characterized in that, The inner diameter (d K ) of all the inner diameter cutting edges (34) is the same, or the inner diameter (d K ) of the inner diameter cutting edges (34) varies along the tool axis (W).

8. The tapping tool according to claim 6 or 7, characterized in that, During the tapping stroke (G), the chips produced are conveyed out of the workpiece thread hole (1) in a chip evacuation direction opposite to the tapping stroke (G), and the inner-diameter cutting edges (34) projecting into the thread grooves (15) prevent the chips from remaining on the thread grooves (15) to a large extent.

9. The tapping tool according to claim 1 or 2, characterized in that, The cutting edge bottom diameter (d SG ) of the inner diameter cutting edge (34) is less than or equal to the bottom hole diameter (d VB ) of the bottom hole cutting angle (39).

10. The tapping tool according to claim 9, characterized in that, During the tapping stroke (G), the cutting-edge bottom (38) of the inner-diameter cutting edge (34) is guided in such a way that it does not engage in a cutting manner with the inner-thread rough profile (8), and the cutting-edge flanks (46, 50) of the inner-diameter cutting edge (34) rest on the thread flanks (18, 19) of the thread grooves (15) of the inner-thread rough profile (8), thereby ensuring the guidance of the tapping tool (23).

11. The tapping tool according to claim 1, characterized in that, The bottom diameter (d SG ) of the cutting edge is larger than the bottom hole diameter (d VB ) of the bottom hole cutting angle (39).

12. The tapping tool according to claim 11, wherein, During the tapping stroke (G), the cutting-edge bottom (38) of the inner-diameter cutting edge (34) engages in a cutting manner with the inner-thread rough profile (8).

13. The tapping tool according to claim 11 or 12, characterized in that, A first material removal (M1) is carried out during the tapping stroke (G), in which the inner-diameter cutting edge (34) removes a part of the diameter allowance (Δd), and a second material removal (M2) is carried out during the retraction stroke (F), in which the inner-diameter cutting edge (34) removes the remaining part of the diameter allowance (Δd).

14. The tapping tool according to claim 6, characterized in that, During the tapping stroke (G), the chips produced collide at least partially with the chip-facing thread flank (19) of the inner-thread rough profile (8), and / or the thread production section (29) has at least one reverse tooth (69) by means of which, during the reverse stroke (R), in the case of the completion of the machining of the workpiece internal thread (9), the flank allowance (Δz) can be removed and / or machined off from the chip-facing thread flank (19).

Images