CN118215551A

CN118215551A - Combination tool for drilling and deburring

Info

Publication number: CN118215551A
Application number: CN202280074507.4A
Authority: CN
Inventors: P·科普顿; A·布加尔
Original assignee: Audi AG; Audi Hungaria Kft
Current assignee: Audi AG; Audi Hungaria Kft
Priority date: 2021-11-10
Filing date: 2022-11-07
Publication date: 2024-06-18
Also published as: DE102021129274A1; WO2023083725A1; EP4429838A1; DE102021129274B4

Abstract

The invention relates to a combination tool for drilling a workpiece through-hole (39) in a workpiece (25) and for deburring a hole edge (27) facing away from the tool, comprising: at least one bottom hole cutting edge (17) having a smaller bottom hole diameter (d), which extends axially from the tool tip (5) in the direction of the tool shank (1) over a cutting edge length (L); and at least one scraping edge (19) having a larger theoretical drilling diameter (D). According to the invention, the cutting edge (19) has a cutting edge (21) on its end face facing the tool tip (5).

Description

Combined tool for drilling and deburring

Technical Field

The invention relates to a combination tool according to the preamble of claim 1 for drilling a workpiece through-hole in a workpiece without a prefabricated hole and for deburring the hole edge facing away from the tool. The invention further relates to a method for drilling and deburring a workpiece through-hole according to claim 7 or 8.

Background

In the production of a workpiece through-hole, the drilling tool is driven into the workpiece without the prefabricated hole with a drilling stroke and a drilling rotational speed until the drilling tool penetrates the workpiece surface facing away from the tool. Burrs may be produced on the hole edge of the through hole facing away from the tool. The burrs may later come off the hole edges and may cause work interruption. If the hole edge facing away from the tool is located in an invisible area, it cannot be easily assessed whether a burr is present at the hole edge facing away from the tool.

Such a combination tool can be used not only for drilling workpiece through holes in workpieces without prefabricated holes, but also for deburring the hole edges facing away from the tool. The combination tool has at least one pilot cutting edge with a smaller pilot diameter and at least one scraping edge with a larger theoretical drilling diameter. The bottom hole cutting edge extends axially from the tool tip toward the shank through a cutting edge length. Axially toward the shank, the cutting edge abuts the bottom hole cutting edge.

A combined countersink for machining deburring bores is known from DE 41 21 695 A1. A drill for drilling and deburring is known from DE 25 50:255 a 1. Other drilling tools for drilling and deburring are known from DE 10 2019 109 916A1 and WO 2018/197364 A1.

Disclosure of Invention

The object of the present invention is to provide a combination tool by means of which not only the drilling of a workpiece through-hole but also the deburring of the hole edge facing away from the tool can be achieved in a process-technically simple manner.

This object is achieved by the features of claim 1, 7 or 8. Preferred developments of the invention are disclosed in the dependent claims.

The invention is based on a combination tool for drilling a workpiece through-hole in a workpiece without a prefabricated hole and for deburring the hole edge facing away from the tool. The combination tool has at least one bottom hole cutting edge/bottom hole cutting portion having a smaller bottom hole diameter, the bottom hole cutting edge extending axially from the tool tip toward the shank through a cutting edge length. Axially toward the shank, at least one scraping edge/portion adjoins the bottom hole cutting edge, the scraping edge having a larger theoretical borehole diameter. The feature of claim 1, the cutting edge having a cutting edge on its end side facing the tool tip. A chip cavity may be provided in front of the cutting edge in the direction of the tool tip, in which chip cavity chips may be collected during a cutting stroke of a combination tool described later. In this case, the running direction of the longitudinal edge is interrupted at the chip cavity. That is, the chip cavity divides the longitudinal edge into a bottom hole cutting edge at the tool tip and a scraping edge at the shank side.

By means of the combination tool according to the invention, a drilling/deburring process can be performed with the following process steps:

First, in the bottom hole drilling step, the composite tool is driven into the workpiece with a bottom hole drilling stroke and a bottom hole drilling rotational speed. At the end of the bottom hole drilling stroke, a hole edge facing away from the tool is machined with a bottom hole diameter that is smaller than the theoretical drilling diameter of the finished workpiece through hole by a material margin. At the end of the bottom-hole drilling stroke, the scraping edge is furthermore located, in particular, completely in the hole and is offset by an axial offset with respect to the hole edge facing away from the tool.

After the bottom hole drilling stroke is finished, a slotting step is performed, wherein the combined tool is driven through the material allowance of the inner wall of the bottom hole by the slotting stroke. Thereby, through the axial offset, a cutting groove is machined into the material allowance, which cutting groove passes through the workpiece surface facing away from the tool. During the slotting step, the cutting edges are guided in the slotting groove without load, that is to say without cutting engagement.

After the slotting step, a shaving step is performed, wherein the combination tool is operated at a shaving rotational speed. Thereby, the scraping edge can remove the material allowance remaining in the inner wall of the bottom hole. In this way, a workpiece through hole having a theoretical borehole diameter is formed. In addition, in the shaving step, deburring of the hole edge facing away from the tool takes place.

In one embodiment, the slotting edge can have a groove bottom cutting edge and a groove side edge. In the slotting step, the radially outer slotting groove bottom is formed by means of groove bottom cutting edges. In the slotting step, slotting groove flanks that rise radially inward from the slotting groove bottom are formed by means of groove flank edges of the slotting edge. The cutting edge, in particular the groove bottom cutting edge, is located on the theoretical drilling diameter. This ensures that after the skiving step has been completed, the hole wall of the finished workpiece through-hole is free of grooves and is configured in a smooth cylindrical shape.

At the end of the slotting travel, the gang tool is guided to a reversal point in which the cutting edge is positioned at least partially within the slotting flute. Alternatively, the cutting edge can be guided to a reversal point in which it is guided out completely beyond the hole edge facing away from the tool.

In terms of shortening the process time, it is preferable to carry out the shaving step directly after the end of the slotting travel. In a first process variant, in the shaving step, the gang tool can be operated with no feed, that is to say only at the shaving rotational speed. In this case, the cutting edge positioned in the cutting groove is brought into cutting contact with the material allowance, in particular with the cutting groove side surface located ahead in the direction of rotation.

Further alternatively, in the skiving step, the gang tool may be operated not only at the skiving rotational speed but also at the reverse feed amount. In this case, the burrs at the edges of the hole are pulled into the hole and thereby deburred.

After the shaving step is completed, a reversing step is performed in which the gang tool is guided out of the completed workpiece through-hole in a reverse direction. During all process steps, that is to say during the bottom hole drilling step, the slotting step, the shaving step and the reversing step, the combination tool can be moved coaxially with respect to the hole axis.

In order to reduce the blade load, it is preferred that the scraping edge is not arranged in axial alignment with the tool axis, but extends helically or helically around the tool axis. In this case, it is preferable to perform the slotting process not only at the slotting feed but also at the slotting rotational speed synchronized therewith. In this way, a spiral or spiral cutting groove is formed in the inner wall of the bottom hole, in which the spiral cutting edge is guided without load during the cutting stroke.

In order to further reduce the blade load of the cutting edge during the cutting step, it is preferred that the pitch (Steigung) of the cutting edge is not the same as the pitch of the slotting groove. But the cutting edge pitch can be reduced as compared to the slotting groove pitch. Thereby producing the following effects: at the beginning of the shaving step, there is little shaving contact between the shaving edge and the material allowance, that is to say the flank of the slotting groove lying ahead in the direction of rotation. As the cutter continues to rotate, cutting contact continues to increase. By increasing the scraping contact, a reduction in the blade load is produced overall, in particular in comparison with the case in which the scraping blade is already in complete scraping contact with the material allowance by its entire blade length at the beginning of the scraping step.

The composite cutter has a clamping shank which transitions into the bit body. The bit body may be configured with at least one bit bridge. The bit bridge may be axially aligned with the cutter axis, or extend helically or helically from the cutter tip to the clamping shank. In the direction of rotation of the tool, a chip flute is provided in front of the drill bridge, which can likewise extend helically from the tool tip to the clamping shank 1 if necessary. The chip flute surfaces and the drill rib lands that delimit the chip flute converge at a longitudinal edge, which, like the drill bridge, extends along the tool axis. The longitudinal edge transitions into an end-side transverse edge at the end-side, radially outer nose, which extends radially inward approximately to the tool axis.

Drawings

Embodiments of the present invention are described below with reference to the accompanying drawings. Wherein:

FIG. 1 shows the gang tool in isolation;

Fig. 2a to 2e show views illustrating a drilling/deburring process according to a first embodiment;

FIG. 3 shows a partially expanded view of the inner wall of the bottom hole with the cutting edge arranged therein;

Fig. 4a to 4e show views illustrating a drilling/deburring process according to a second embodiment;

Fig. 5a to 5e show views illustrating a drilling/deburring process according to a third embodiment, respectively; and

Fig. 6a to 6d show views illustrating a drilling/deburring process according to a fourth embodiment, respectively;

Fig. 7 shows a stepped drilling tool for performing the drilling/deburring process illustrated in fig. 6a to 6 d; and

Fig. 8 shows an expanded view according to a fourth embodiment in a view corresponding to fig. 3.

Detailed Description

In fig. 1, a gang tool for producing a workpiece through-hole 39 (fig. 2 e) is shown. The combination tool has a clamping shank 1 which transitions into a bit body 3. The drill body 3 is configured with a drill bridge 7 which extends helically or spirally from the tool tip 5 to the clamping shank 1. In the tool rotational direction DR (fig. 3), a chip flute 9 is provided in front of the drill bridge 7, which likewise extends helically from the tool tip 5 to the clamping shank 1. Chip flute surfaces and drill rib lands (Bohrersteg-) Converging at the longitudinal edge 11, which likewise extends helically or helically along the tool axis a, like the drill bridge 7. The longitudinal edge 11 merges at the end-side, radially outer nose 13 into an end-side transverse edge 15, which extends radially inwards approximately to the tool axis a.

In fig. 1, the longitudinal edge 11 is axially divided into a bottom hole cutting edge 17 and a scraping edge 19. The bottom hole cutting edge 17 extends from the tool tip 5 axially towards the shank 1 over a cutting edge length L. The cutting edge 19 follows in the continued extension in the direction of the shank 1. The bottom hole cutting edge 17 has a smaller bottom hole diameter D and the scraping edge 19 has a larger theoretical borehole diameter D to which the workpiece through hole 39 should be drilled.

In fig. 1, the cutting edge 19 is configured with a cutting edge 21 on its end side facing the tool tip 5. The later-described slotting travel h _S is completed by means of this slotting edge 21. In the direction of the tool tip 5, a chip space 23 is provided in front of the cutting edge 21, through which chip space the cutting chips are discharged during a cutting stroke h _S. The chip space 23 is designed to open in the direction of the chip flute 9, so that the chip that is produced during the cutting stroke h _S/fig. 2 c) is conveyed from the chip space 23 to the outside of the hole.

The following describes, with reference to fig. 2a to 2e, a drilling/deburring process which can be carried out with the aid of the combination tool: accordingly, first in a bottom hole drilling step (fig. 2 b), the combination tool is driven into the workpiece 25 without the prepared hole with a bottom hole drilling stroke h _V and a bottom hole drilling rotational speed n _V. At the end of the bottom hole drilling stroke (fig. 2 b), a hole edge 27 is machined in the workpiece face 31 facing away from the tool, at which hole edge a burr 28 is formed. In fig. 2b, the hole edge 27 facing away from the tool has a bottom hole diameter D which is smaller than the theoretical borehole diameter D by a material margin m (only shown in fig. 3). At the same time, at the end of the bottom-hole drilling stroke (fig. 2 b), the scraping edge 19 is located completely inside the hole and is offset by an axial offset a (shown only in fig. 3, 4b and 5 b) with respect to the hole edge 27 facing away from the tool.

Immediately after the end of the bottom hole drilling stroke (fig. 2 b), a slotting step (fig. 2 c) is performed, wherein the combination tool is driven through the material allowance m of the bottom hole inner wall with a slotting stroke h _S. Thereby, a cutting groove 29 is machined into the material allowance m by the axial offset a, which cutting groove passes through the workpiece surface 31 facing away from the tool. In the schematic development of fig. 3, the slotting groove 29 machined in the slotting travel h _S is shown. In fig. 3, furthermore, the position of the cutting edge 21 is shown at the reversal point U, that is to say after the completion of the cutting stroke h _S. During the slotting step (in the direction of arrow F), the cutting edges 19 are guided in the slotting groove 29 without load, that is to say without cutting engagement.

In order to produce the cutting flute 29, the cutting edge 21 according to fig. 1 and 3 has a flute base cutting edge 33 and a flute side edge 35 (only one of which is visible in fig. 1). In the slotting step, a radially outer slotting groove bottom 36 (fig. 3) is machined by means of the groove bottom cutting edge 33. In the slotting step, slotting groove flanks 37 (fig. 3) are machined by means of slotting groove flank edges 35, which stand radially inwards from the slotting groove bottoms 36. The cutting edge 21, that is to say its groove bottom cutting edge 33, and the scraping edge 19 are located on the theoretical drilling diameter D.

In the slotting step (fig. 2 c), a slotting stroke h _S is performed with a slotting feed f _S and a slotting rotational speed n _S synchronized therewith. In this way, a spiral-shaped cutting groove 29 is produced, in which the spiral-shaped cutting edge 19 is guided without load during the cutting path h _S. In fig. 3, the pitch α ₁ of the cutting edge 19 differs from the pitch α ₂ of the slotting groove 29. Conversely, the cutting edge pitch α ₁ is reduced as compared to the slotting groove pitch α ₂. In this way, at the beginning of the skiving step (fig. 2 d), the skiving contact between the skiving edge 19 and the material allowance m is increased continuously with the continued tool rotation DR (fig. 3), whereby the edge load is reduced.

In fig. 2c and 3, at the end of the slotting travel, the combined tool is guided to a reversal point U, in which the scraping edge 19 is positioned inside the slotting groove 29. In the following shaving step (fig. 2 d), the gang tool is operated at a shaving rotational speed n _A (fig. 2 d), but without a feed. Thereby, the scraping edge 19 located in the slotting groove 29 comes into scraping contact with the slotting groove side surface 37 placed forward in the rotation direction DR, thereby scraping off the material margin m.

After the skiving step (fig. 2 d), a reversing step is carried out, in which the combination tool is guided out of the finished workpiece through-hole 39 in the reversing direction R.

In fig. 4a to 4e, a drilling/deburring process carried out with a schematically outlined combination tool according to a second embodiment is shown. The combination tool is basically constructed the same as the combination tool structure shown in fig. 1 and 2. In contrast to fig. 1 and 2, the combination tool in fig. 4a to 4e has a total of two opposite cutting edges 21. The two cutting edges each transition axially into the scraping edge 19 in the direction of the clamping shank. Correspondingly, in the slotting step, two opposite slotting grooves 29 are machined into the inner wall of the bottom hole, in which the cutting edges 19 are guided, respectively.

Another drilling/deburring process performed with a combination tool according to a third embodiment is shown in fig. 5a to 5 e. In contrast to the second exemplary embodiment (fig. 4a to 4 e), in fig. 5a to 5e the cutting edge 19 is guided completely beyond the hole edge 27 facing away from the tool by the excess x in the slotting travel h _S. The skiving step (fig. 4 d) is then carried out, wherein the combination tool is operated at a skiving speed n _A, but also at a reverse feed f _A. In this way, the burr 28 is pulled from the hole edge 27 into the hole and deburred.

In fig. 6a to 6d, a drilling/deburring process is performed using a stepped drill bit. The stepped drill bit is shown in isolation in fig. 7. It is shown therefrom that the stepped drill bit has essentially the same component geometry as the combination tool shown in fig. 1 to 5. Reference is therefore made to the description above. Unlike the combination tool, the stepped drill has neither a cutting edge 21 nor a chip cavity 23 at the transition from the bottom hole cutting edge 17 to the scraping edge 17. In contrast, according to fig. 8, the cutting edge 19 transitions into the free surface/rear surface at the end-side nose 2022, The relief surface is not in contact with the material margin m during the skiving step (fig. 6c and 8).

The drilling/deburring process which can be carried out with the aid of the stepped drill bit is described next with reference to fig. 6a to 6e and also with reference to fig. 8: accordingly, first in a bottom hole drilling step (fig. 6 b), the stepped drill bit is driven into the workpiece 25 without a prepared hole with a bottom hole drilling stroke h _V and a drilling speed n. At the end of the bottom hole drilling stroke (fig. 6 b), a hole edge 27 is machined in the workpiece face 31 facing away from the tool, at which hole edge a burr 28 is formed. In fig. 6b, the hole edge 27 facing away from the tool has a bottom hole diameter D which is smaller than the theoretical borehole diameter D by a material margin m (fig. 8). At the end of the bottom-hole drilling stroke (fig. 6 b), the scraping edge 19 is at the same time not yet fully located in the hole and is offset by an axial offset a (fig. 8) with respect to the hole edge 27 facing away from the tool.

After the end of the pilot hole stroke (fig. 6 b), the slotting step (as in the above-described exemplary embodiment) is not carried out directly, but rather a shaving step (fig. 6 c), in which the stepped tool is driven through the material allowance m of the pilot hole inner wall with a shaving feed f _S and a drilling speed n, so that the shaving edge 19 shaves off the material allowance m, in particular in the case of forming a workpiece through hole 39 having a setpoint hole diameter D and in the case of deburring a hole edge 27 facing away from the tool. In order to ensure perfect deburring, in the skiving step the skiving feed f _A is designed to be significantly greater than the bottom hole feed f _V. In fig. 6c and in fig. 8, at the end of the slotting travel, the stepped drill bit is guided to the reversal point U.

The process times during the skiving step are shown in fig. 8. Accordingly, the scraping edge 19 is in cutting engagement with the material margin m placed forward in the rotational direction DR. Conversely, the end-side free surface 22 is not in cutting engagement with the material allowance m.

After the skiving step (fig. 6 c), a reversing step (fig. 6 d) is performed, in which the stepped drill is guided out of the finished workpiece through-hole 39 in the reversing direction R.

In the skiving step (fig. 6 c), the skiving feed f _S and the drilling speed n are not synchronized with one another—in contrast to the skiving step according to the previous embodiment, in the skiving step of the previous embodiment the skiving feed f _S and the skiving speed n _S are synchronized with one another in such a way that the skiving edge 19 is guided in the skiving groove without load, i.e. without cutting engagement.

List of reference numerals

1 Clamping handle

3 Bit body

5 Cutter tip

7 Bit bridge

9 Chip groove

11 Longitudinal edge

13 Knife point

15 Transverse blade

17 Bottom hole cutting edge

19 Scraping blade

20 Edge of the scraping blade 19

21 Slotting blade

Yielding surface of 22 end sides

23 Chip cavity

25 Work piece

27 Hole edge

28 Burrs

29 Slotting groove

31 Workpiece surface

33 Groove bottom cutting edge

35 Groove side edge

36 Slotting groove bottom

37 Slotting groove side

Atool axis

M material allowance

U inversion point

DR direction of rotation

H _V bottom hole drilling travel

H _S slotting travel

R reverse direction

D theoretical borehole diameter

D bottom hole diameter

L cutting edge length

X excess

F _V bottom hole feed

F _S slotting feed

F _A shaving feed quantity

Claims

1. A combined tool for drilling a through hole (39) in a workpiece (25) and for deburring a hole edge (27) facing away from the tool, the combined tool comprising: at least one bottom hole cutting edge (17) with a smaller bottom hole diameter (d), the bottom hole cutting edge extending axially from the tool top (5) in the direction of the tool shank (1) over a cutting edge length (L); and at least one scraping edge (19) with a larger theoretical drilling diameter (D), characterized in that the scraping edge (19) has a plunge cutting edge (21) on its end side facing the tool top (5); a drilling/deburring process can be performed with the combined tool, in particular with the following process steps:

A bottom hole drilling step, wherein the combined tool can be driven into the workpiece (25) at a bottom hole drilling stroke ( _hV ) and a bottom hole drilling speed ( _nV ), so that at the end of the bottom hole drilling stroke, a hole edge (27) with a bottom hole diameter (d) facing away from the tool is machined, the bottom hole diameter is smaller than a theoretical drilling diameter (D) by a material excess (m), and the scraping edge (19) is still located in the hole and is offset by an axial offset (a) relative to the hole edge (27) facing away from the tool,

a slotting step, wherein the combined tool can be driven with a slotting stroke (h _V ) through a material excess (m) of the inner wall of the bottom hole, so that a slotting groove (29) is machined in the material excess (m) via an axial offset (a), the slotting groove passing through a workpiece surface (31) facing away from the tool, wherein preferably during the slotting step, the scraping edge (19) is guided in the slotting groove (29) without cutting engagement and/or substantially without load; and

A scraping step in which the combined tool can be operated at a scraping speed (n _A ) so that the scraping edge (19) removes the remaining material excess (m), specifically while forming a workpiece through-hole (39) with a theoretical drilling diameter (D) and while deburring the hole edge (27) facing away from the tool.

2. The combined tool according to claim 1 is characterized in that the slotting edge (21) has a slot bottom cutting edge (33) and a slot side edge (35), and in the slotting step, the slot bottom cutting edge processes a slotting slot bottom (36), and in the slotting step, the slot side edge processes a slotting slot side (37) that stands radially inward from the slot bottom (36); and/or a chip cavity (23) is arranged in front of the slotting edge (21) in the direction of the tool top (5); and/or the slotting edge (21), especially its slot bottom cutting edge (33), is located on the theoretical drilling diameter (D).

3. The combined tool according to claim 1 or 2, characterized in that at the end of the slotting stroke, the combined tool is guided to a reversal point (U); at the reversal point (U), the scraping edge (19) is at least partially located within the slotting groove (29); or at the reversal point (U), the scraping edge (19) is guided out completely beyond the hole edge (27) facing away from the tool with an overhang (x); and/or a scraping step is carried out, in particular directly after the end of the slotting stroke; in particular, in the scraping step, the combined tool is operated without feed, that is, only at a scraping speed ( _nA ), so that the scraping edge (19) located in the slotting groove (29) is in scraping contact with the material residue (m), in particular with the slotting groove side (37) located in front in the rotational direction (DR).

4. The combined tool according to claim 3 is characterized in that, during the scraping step, the combined tool is operated at a scraping speed (n _A ) and a reverse feed (f _R ) to remove burrs (28) at the hole edge (27); and/or a reverse step is performed, in particular after the scraping step, wherein the combined tool is guided out of the finished workpiece through hole (39) in the reverse direction (R).

5. A combined tool according to any one of the preceding claims, characterized in that the scraping edge (19) extends helically about the tool axis (A) or extends linearly along the tool axis (A); the slotting stroke (h _S ) is carried out with a slotting feed (f S ) and a slotting speed (n _S ) synchronized therewith so that a spiral slotting groove (29) is produced or the slotting stroke (h _S ) only carries out an axial movement at zero speed; and/or during the slotting stroke (h _S ), the scraping edge (19) is guided in the slotting groove (29) without load.

6. The combined tool according to claim 5, characterized in that the pitch (α ₁ ) of the scraping edge (19) is not the same as the pitch (α ₂ ) of the slotting groove (29), but has a reduced scraping edge pitch (α ₁ ) compared to the slotting groove pitch (α ₁ ), so that at the beginning of the scraping step, the scraping contact between the scraping edge (19) and the material residue (m) increases continuously as the tool continues to rotate.

7. A method for drilling a through hole (39) in a workpiece (25) and deburring a hole edge (27) facing away from the tool by means of a combined tool according to any of the preceding claims, wherein the combined tool comprises: at least one bottom hole cutting edge (17) with a smaller bottom hole diameter (d), the bottom hole cutting edge extending axially from the tool top (5) in the direction of the tool shank (1) over a cutting edge length (L); and at least one scraping edge (19) at a larger theoretical drilling diameter (D), characterized in that the scraping edge (19) has a plunge cutting edge (21) on its end side facing the tool top (5); a drilling/deburring process having the following process steps is performed using the combined tool:

A bottom hole drilling step, wherein the combined tool is driven into the workpiece (25) with a bottom hole drilling stroke ( _hV ) and a bottom hole drilling speed ( _nV ), so that at the end of the bottom hole drilling stroke, a hole edge (27) with a bottom hole diameter (d) facing away from the tool is machined, the bottom hole diameter is smaller than a theoretical drilling diameter (D) by a material excess (m), and the scraping edge (19) is still located in the hole and is offset by an axial offset (a) relative to the hole edge (27) facing away from the tool,

a slotting step, wherein the combined tool is driven with a slotting stroke (h _V ) through a material excess (m) of the inner wall of the bottom hole, thereby machining a slotting groove (29) in the material excess (m) via an axial offset (a), the slotting groove passing through a workpiece surface (31) facing away from the tool, wherein preferably during the slotting step, the scraping edge (19) is guided in the slotting groove (29) without cutting engagement and/or substantially without load; and

A scraping step in which the combined tool is operated at a scraping speed (n _A ) so that the scraping edge (19) removes the remaining material excess (m), specifically while forming a workpiece through-hole (39) with a theoretical drilling diameter (D) and while deburring the hole edge (27) facing away from the tool.

8. A method for drilling a through hole (39) in a workpiece (25) and deburring the hole edge (27) facing away from the tool by means of a step drilling tool, the step drilling tool having: at least one bottom hole cutting edge (17) with a smaller bottom hole diameter (d), the bottom hole cutting edge extending axially from the tool top (5) in the direction of the tool shank (1) over a cutting edge length (L); and at least one scraping edge (19) at a larger theoretical drilling diameter (D), characterized in that a drilling/deburring process having the following process steps is carried out with the step drilling tool:

A bottom hole drilling step, wherein the combined tool is driven into the workpiece (25) at a bottom hole drilling stroke ( _hV ) and a drilling speed (n), so that at the end of the bottom hole drilling stroke, a hole edge (27) with a bottom hole diameter (d) facing away from the tool is machined, the bottom hole diameter is smaller than a theoretical drilling diameter (D) by a material excess (m), and the scraping edge (19) is still located in the hole and is offset by an axial offset (a) relative to the hole edge (27) facing away from the tool,

A scraping step, wherein the combined tool is driven at a scraping feed ( _fA ) through the material excess (m) of the inner wall of the bottom hole, so that the scraping edge (19) removes the material excess (m), specifically, while forming a through-hole (39) in the workpiece with a theoretical drilling diameter (D) and while deburring the hole edge (27) facing away from the tool.

9. The method according to claim 8, characterized in that, during the scraping step, the scraping feed (f _A ) and the drilling speed (n) are not synchronized with each other; and/or the scraping feed (f _A ) is designed to be significantly greater than the bottom hole feed (f _V ); and/or in particular during the scraping step, the scraping edge (19) is in cutting engagement with the material excess.