Combination tool

Abstract

Method for drilling a workpiece through-hole (39) in a workpiece (25) and for deburring a hole edge (27) away from the tool using a combination tool according to one of the preceding claims, wherein the combination tool has at least one pre-drilling cutting edge (17) having a smaller pre-drilling diameter (d) and extending axially from the tool tip (5) over a cutting length (L) towards the tool shank (1), and at least one peeling cutting edge (19) located on a larger nominal drill diameter (D), characterized in that the peeling cutting edge (19) has a butt cutting edge (21) on its end face facing the tool tip (5), and that a drilling / deburring process is carried out with the combination tool, comprising the following process steps: a pre-drilling step in which the combination tool is driven into the workpiece (25) with a pre-drilling stroke (hv) and a pre-drilling speed (nv), so that at the end of the pre-drilling stroke the bore edge (27) furthest from the tool is produced with the pre-drilling diameter (d) which is smaller by a material allowance (m) than the nominal drilling diameter (D), while the peeling edge (19) is still located inside the bore and offset by an axial offset (a) to the bore edge (27) facing away from the tool, a thrust step in which the combination tool is driven with a thrust stroke (hv) through the material allowance (m) of the pre-drilled inner wall, so that a thrust groove (29) is produced in the material allowance (m) over the axial offset (a), which penetrates the workpiece surface (31) facing away from the tool, wherein preferably during the thrust step the peeling edge (19) is guided in the thrust groove (29) without chip engagement and / or substantially without load; and a peeling step in which the combination tool operates at a peeling speed (n A ) is operated so that the peeling edge (19) peels off the remaining material excess (m), forming the workpiece through hole (39) with the nominal drill diameter (D) and deburring the tool-away edge of the hole (27).

Description

[0001] The invention relates to a method for drilling and deburring a workpiece through-hole according to claim 1 or 2. The invention also relates to a combination tool for drilling a workpiece through-hole in a workpiece without a pre-hole and for deburring a hole edge facing away from the tool according to the preamble of claim 4.

[0002] When drilling a through-hole in a workpiece, a drilling tool is driven into a workpiece without a pre-hole using a drilling stroke and a drilling speed until it penetrates the workpiece surface facing away from the tool. A burr may form on the edge of the through-hole facing away from the tool. The burr may later detach from the hole edge and potentially lead to operational malfunctions. If the edge of the hole facing away from the tool is located in an area that cannot be seen, it is not easy to determine whether a burr is present on the edge of the hole facing away from the tool.

[0003] A generic combination tool can be used both for drilling a through-hole in a workpiece without a pilot hole and for deburring a hole edge facing away from the tool. The combination tool has at least one pilot cutting edge with a smaller pilot diameter and at least one skiving edge with a larger nominal drilling diameter. The pilot cutting edge extends axially from the tool tip over a cutting edge length toward the tool shank. The skiving edge is connected axially to the pilot cutting edge in the direction of the tool shank.

[0004] EP 2 7 99 171 A1 discloses a combination tool having a small-diameter cutting edge at the tool tip, which transitions into a larger-diameter cutting edge toward the tool shank. DD 8219 A discloses a shaped-hole drilling tool. DE 41 21 695 A1 discloses a combination countersink for producing deburred holes. DE 25 50 905 A1 discloses a drill for drilling and deburring. DE 10 2019 109 916 A1 and WO 2018 / 197364 A1 disclose further drilling tools for drilling and deburring.

[0005] The object of the invention is to provide a method for drilling and deburring a workpiece through-hole and a combination tool therefor, with which both drilling of a workpiece through-hole and deburring of a hole edge facing away from the tool are possible in a technically simple manner.

[0006] The object is solved by the features of claim 1, 2 or 4. Preferred developments of the invention are disclosed in the subclaims.

[0007] The invention is based on a combination tool for drilling a workpiece through-hole in a workpiece without a pilot hole and for deburring a hole edge facing away from the tool. The combination tool has at least one pilot cutting edge with a smaller pilot diameter, which extends axially from the tool tip over a cutting edge length in the direction of the tool shank. The pilot cutting edge is followed axially in the direction of the tool shank by at least one spiral cutting edge with a larger nominal drilling diameter. According to the invention, the spiral cutting edge has a cutting edge on its end face facing the tool tip. A chip space can be arranged upstream of the cutting edge in the direction of the tool tip, in which chip space impact chips can collect during a cutting stroke of the combination tool, described later. In this case, the course of the longitudinal cutting edge is interrupted at the chip space.This means that the chip space divides the longitudinal cutting edge into the pre-drilling cutting edge at the tool tip and the peeling cutting edge on the shank side.

[0008] With the aid of the combination tool according to the invention, a drilling / deburring process can be carried out, comprising the following process steps: First, in a pre-drilling step, the combination tool is driven into the workpiece with a pre-drilling stroke and a pre-drilling speed. At the end of the pre-stroke, the bore edge facing away from the tool is created with the pre-drilling diameter, which is smaller by a material allowance than the target bore diameter of the finished workpiece through-hole. Furthermore, at the end of the pre-stroke, the skiving edge is located completely inside the bore and offset by an axial offset from the bore edge facing away from the tool.

[0009] After the end of the pre-drilling stroke, a pushing step follows, during which the combination tool is driven through the material allowance of the pilot hole's inner wall with a pushing stroke. This creates a pushing groove in the material allowance across the axial offset, which pierces the workpiece surface facing away from the tool. During the pushing step, the skiving cutter is guided in the pushing groove without stress, i.e., without chip engagement.

[0010] After the shaping step, a skiving step is performed, during which the combination tool is operated at a skiving speed. This allows the skiving cutting edge to skive away the remaining stock in the inner wall of the pilot hole. This creates the workpiece through-hole with the target diameter. In addition, the skiving step deburrs the edge of the hole facing away from the tool.

[0011] In a technical implementation, the slotting edge can have a groove base cutting edge and groove flank cutting edges. The groove base cutting edge forms a radially outer slotting groove base during the slotting step. The slot flank cutting edges of the slotting edge form slotting groove flanks in the slotting step, which extend radially inward from the slotting groove base. The slotting edge, and in particular its groove base cutting edge, lies on a nominal bore diameter. This ensures that, after the skiving step, the bore wall of the finished workpiece through-hole is groove-free and smooth-cylindrical.

[0012] At the end of the impact stroke, the combination tool is guided to a reversal point where the skiving edge is at least partially positioned within the impact groove. Alternatively, the skiving edge can be guided to a reversal point where it extends completely beyond the bore edge facing away from the tool.

[0013] To reduce process time, it is preferable if the skiving step is performed immediately after the end of the impact stroke. In a first process variant, the combination tool can be operated without feed during the skiving step, i.e., only at skiving speed. In this case, the skiving cutting edge positioned in the impact groove is brought into skiving contact with the material allowance, specifically into skiving contact with a face of the impact groove positioned upstream in the direction of rotation.

[0014] Alternatively, the combination tool can be operated at both the skiving speed and a reversing feed rate during the skiving step. In this case, a burr at the edge of the hole can be drawn inward, thereby deburring it.

[0015] After the skiving step, a reversing step is performed, in which the combination tool is reversibly removed from the finished workpiece through-hole. In all process steps—pre-drilling, punching, skiving, and reversing—the combination tool can be moved coaxially to the hole axis.

[0016] To reduce cutting edge stress, it is preferable if the peeling edge is not arranged in axial alignment with the tool axis, but rather runs helically or spirally around the tool axis. In this case, it is preferable if the impact stroke is performed not only with an impact feed, but also with a synchronized impact speed. In this way, a helical or spiral-shaped impact groove is created in the inner wall of the pilot hole, in which the helical peeling edge is guided without stress during the impact stroke.

[0017] To further reduce the cutting edge load on the skiving edge during the skiving step, it is preferable if the pitch of the skiving edge and the pitch of the butt groove are not identical. Instead, the skiving edge pitch can be reduced compared to the butt groove pitch. This has the following effect: At the start of the skiving step, the skiving contact between the skiving edge and the material allowance (i.e., the butt groove flank upstream in the direction of rotation) is still low. As the tool rotates, the cutting contact increases continuously. The continuous increase in skiving contact results in an overall reduced cutting edge load compared to the case where the skiving edge comes into complete skiving contact with the material allowance with its entire cutting edge length right at the start of the skiving step.

[0018] The combination tool has a clamping shank that transitions into a drill body. The drill body can be designed with at least one drill web. This can run in axial alignment with the tool axis or in a helical or spiral shape from the tool tip to the clamping shank. A chip groove is arranged in front of the drill web in the direction of tool rotation, which can optionally also extend in a helical shape from the tool tip to the clamping shank 1. A chip groove surface delimiting the chip groove and a drill web back surface converge at the longitudinal cutting edge, which runs along the tool axis analogous to the drill web. The longitudinal cutting edge transitions at a front-side, radially outer cutting edge corner into a front-side chisel cutting edge, which extends radially inward approximately to the tool axis.

[0019] Exemplary embodiments of the invention are described below with reference to the accompanying figures. They show: Fig. 1 a unique combination tool; Fig. 2a to 2e are views illustrating a drilling / deburring process according to a first embodiment; Fig. 3 partial development of the pilot hole inner wall with chip groove in which the peeling cutting edge is arranged; Fig. 4a to 4e are views illustrating a drilling / deburring process according to a second embodiment; Fig. 5a to 5e are views illustrating a drilling / deburring process according to a third embodiment; and Fig. 6a to 6d are views illustrating a drilling / deburring process according to a fourth embodiment; Fig. 7 a step drilling tool for carrying out the drilling in the Fig. 6a to 6d illustrated drilling / deburring process; and Fig. 8 in a view corresponding to the Fig. 3 a development according to the fourth embodiment.

[0020] In the Fig. 1 is a combination tool for producing a workpiece through-hole 39 ( Fig. 2e). The combination tool has a clamping shaft 1, which merges into a drill body 3. The drill body 3 is formed with a helical drill web 7 running from a tool tip 5 to the clamping shaft 1. The drill web 7 is provided with a groove in the tool rotation direction DR ( Fig. 3) a chip groove 9 is arranged in front of it, which also extends in a helical shape from the tool tip 5 to the clamping shank 1. A chip groove surface delimiting the chip groove 9 and a drill web back surface converge at a longitudinal cutting edge 11, which, analogous to the drill web 7, also runs in a helical shape along the tool axis A. The longitudinal cutting edge 11 merges at a front-side, radially outer cutting edge corner 13 into a front-side transverse cutting edge 15, which extends radially inwards approximately to the tool axis A.

[0021] In the Fig. 1, the longitudinal cutting edge 11 is divided in the axial direction into a pre-drilling cutting edge 17 and a peeling cutting edge 19. The pre-drilling cutting edge 17 extends from the tool tip 5 over a cutting length L axially in the direction of the tool shank 1. The peeling cutting edge 19 adjoins it further in the direction of the tool shank 1. The pre-drilling cutting edge 17 has a smaller pre-drilling diameter d, while the peeling cutting edge 19 has a larger nominal drilling diameter D, to which the workpiece through-bore 39 is drilled.

[0022] In the Fig. 1, the peeling cutting edge 19 is formed with a cutting edge 21 on its end face facing the tool tip 5. A cutting stroke hs, described later, is carried out by means of the cutting edge 21. A chip space 23 is arranged in front of the cutting edge 21 in the direction of the tool tip 5, through which chippings are removed during the cutting stroke hs. The chip space 23 is open in the direction of the chip groove 9, so that the chips generated during the cutting stroke hs / Fig. 2c) generated impact chips are transported from the chip space 23 to the outside of the bore.

[0023] The following is based on the Fig. 2a to 2e describe a drilling / deburring process that can be carried out using the combination tool: Accordingly, in a pre-drilling step ( Fig. 2b) the combination tool is driven into a workpiece 25 without a pilot hole with a pilot stroke hv and a pilot speed nv. At the end of the pilot stroke ( Fig. 2b), a bore edge 27 is produced on the workpiece surface 31 facing away from the tool, on which a burr 28 is formed. The bore edge 27 facing away from the tool has in the Fig. 2b the pre-drill diameter d, which is increased by a material allowance m (only in the Fig. 3) is smaller than the target drilling diameter D. At the same time, at the end of the pre-drilling stroke ( Fig. 2b) the peeling cutting edge 19 completely inside the bore and by an axial offset a (only in the Fig. 3, Fig. 4b and Fig. 5b) offset from the bore edge 27 facing away from the tool.

[0024] Following the end of the pre-drilling stroke ( Fig. 2b) is followed by a push step ( Fig. 2c), in which the combination tool is driven with the impact stroke hs through the material allowance m of the pilot hole inner wall. This creates a pushing groove 29 in the material allowance m across the axial offset a, which pierces the workpiece surface 31 facing away from the tool. The pushing groove 29 created in the pushing stroke hs is shown in the schematic development of the Fig. 3. In addition, the Fig. 3 indicates the position of the cutting edge 21 at the reversal point U, i.e., after the cutting stroke hs has been completed. The peeling edge 19 is guided in the cutting groove 29 during the cutting step (in the direction of arrow F) without any load, i.e., without chip engagement.

[0025] To produce the butt groove 29, the butt cutting edge 21 has Fig. 1 and Fig. 3 a groove base cutting edge 33 and groove flank cutting edges 35 (in the Fig. 1 only one of them is visible). With the help of the groove base cutting edge 33, a radially outer butt groove base 36 ( Fig. 3) is produced. With the help of the butt groove flanks 35, the butt groove flanks 37 ( Fig. 3). The cutting edge 21, i.e. its groove base cutting edge 33, as well as the skiving cutting edge 19, lies on the nominal drilling diameter D.

[0026] In the push step ( Fig. 2c) the impact stroke hs is carried out with an impact feed fs and a synchronized impact speed ns. In this way, a helical impact groove 29 is created in which the helical peeling cutting edge 19 is guided without stress during the impact stroke hs. Fig. 3, the pitch α1 of the peeling edge 19 and the pitch α2 of the butt groove 29 are not identical.

[0027] Rather, the skiving edge pitch α1 is reduced compared to the butt groove pitch α2. In this way, at the start of the skiving step ( Fig. 2d) the peeling contact between the peeling cutting edge 19 and the material allowance m with continuous tool rotation DR ( Fig. 3) continuously larger, which reduces the cutting load.

[0028] In the Fig. 2c and Fig. 3, the combination tool is guided at the end of the impact stroke to a reversal point U, in which the peeling cutting edge 19 is positioned within the impact groove 29. In the subsequent peeling step ( Fig. 2d) the combination tool is operated with the peeling speed n A ( Fig. 2d), but without feed. As a result, the peeling cutting edge 19 arranged in the butt groove 29 comes into peeling contact with the butt groove flank 37 positioned upstream in the direction of rotation DR, whereby the material allowance m is peeled off.

[0029] After the peeling step ( Fig. 2d) a reversing step ( Fig. 2e) is carried out, in which the combination tool is guided in a reversing direction R out of the finished workpiece through-bore 39.

[0030] In the Fig. 4a to 4e show a drilling / deburring process performed with a roughly schematically illustrated combination tool according to a second embodiment. The combination tool is basically identical in construction to the one shown in Fig. 1 and Fig. 2 shown combination tool. In contrast to the Fig. 1 and Fig. 2 indicates the combination tool in the Fig. 4a to 4e comprise a total of two opposing butt cutting edges 21. These each transition axially in the direction of the clamping shank 1 into a skiving edge 19. Accordingly, in the butt step, two opposing butt grooves 29 are created in the inner wall of the pilot bore, in each of which a skiving edge 19 is guided.

[0031] In the Fig. 5a to 5e show a further drilling / deburring process performed with a combination tool according to a third embodiment. In contrast to the second embodiment ( Fig. 4a to 4e) is in the Fig. 5a to 5e in the impact stroke hs, the peeling cutting edge 19 is guided with a projection x completely beyond the bore edge 27 facing away from the tool. Subsequently, the peeling step ( Fig. 4d), where the combination tool is not only operated at the peeling speed n A , but also with a reversing feed f A In this way, the burr 28 is pulled from the bore edge 27 toward the inside of the bore and deburred.

[0032] In the Fig. 6a to 6d, a drilling / deburring process is carried out using a step drill. This is shown in the Fig. 7. This shows that the step drill essentially has the same component geometry as the one shown in the Fig. 1 to 5. Therefore, reference is made to the specification. In contrast to the combination tool, the step drill has neither a cutting edge 21 nor a chip space 23 at the transition from the pre-drilling cutting edge 17 to the peeling cutting edge 19. Rather, according to the Fig. 8 the peeling edge 19 merges at a frontal cutting edge corner 20 into a free surface 22, which during the peeling step ( Fig. 6c and Fig. 8) is out of contact with the material allowance m.

[0033] The following is based on the Fig. 6a to 6e and the Fig. 8 describes a drilling / deburring process that can be carried out using the step drill: Accordingly, in a pre-drilling step ( Fig. 6b) the step drill is driven into a workpiece 25 without a pilot hole with a pilot stroke hv and a drilling speed n. At the end of the pilot stroke ( Fig. 6b), a bore edge 27 is produced on the workpiece surface 31 facing away from the tool, on which a burr 28 is formed. The bore edge 27 facing away from the tool has in the Fig. 6b the pre-drilling diameter d, which is increased by a material allowance m ( Fig. 8) is smaller than the target drilling diameter D. At the same time, at the end of the pre-drilling stroke ( Fig. 6b) the peeling cutting edge 19 is still completely inside the bore and by an axial offset a ( Fig. 8) offset from the bore edge 27 facing away from the tool.

[0034] Immediately after the end of the pre-drilling stroke ( Fig. 6b) is not followed by a pushing step (as in the previous embodiments), but by a peeling step ( Fig. 6c), in which the step tool is drilled with a peeling feed fs and at the drilling speed n through the material allowance m of the pilot hole inner wall, so that the peeling cutting edge 19 peels off the material allowance m, specifically while forming the workpiece through-hole 39 with the target drilling diameter D and while deburring the hole edge 27 facing away from the tool. In order to ensure perfect deburring, the peeling feed f A is significantly larger than the pre-drill feed fv. In the Fig. 6c or in the Fig. 8 the step drill is guided at the end of the stroke to a reversal point U. In the Fig. Figure 8 shows a process point during the skiving step. Accordingly, the skiving cutting edge 19 is in chip engagement with the material allowance m located upstream in the direction of rotation DR. The front flank 22, however, is out of chip engagement with the material allowance m.

[0035] After the peeling step ( Fig. 6c) a reversing step ( Fig. 6d) is carried out, in which the step drill is guided in a reversing direction R out of the finished workpiece through-hole 39.

[0036] In the peeling step ( Fig. 6c) the peeling feed fs and the drilling speed n are not synchronized with each other, in contrast to the impact step according to the previous embodiments, in which the impact feed fs and the impact speed ns are synchronized with each other in such a way that the peeling cutting edge 19 is guided in the impact groove without load, i.e. without chip engagement. LIST OF REFERENCE SYMBOLS: 1 clamping shaft 3 drill bodies 5 tool tip 7 Drill bridge 9 chip groove 11 Longitudinal cutting edge 13 Cutting corner 15 Cross cutting edge 17 Pre-drilling cutting edge 19 Paring blade 20 frontal cutting edge of the peeling edge 19 21 Butt cutting edge 22 frontal open space 23 chip space 25 workpiece 27 Hole edge 28 ridges 29 Butt groove 31 Workpiece surface 33 Groove base cutting edge 35 groove flank cutting edges 36 Butt groove base 37 butt groove flanks A tool axis m material allowance U reversal point DR direction of rotation hv pre-drilling stroke hs shock stroke R Reversing direction D Target drilling diameter d pre-drill diameter L Cutting length x supernatant fv pre-drilling feed fs impact feed f A Peeling feed

Claims

[1] Method for drilling a workpiece through-bore (39) in a workpiece (25) and for deburring a bore edge (27) facing away from the tool using a combination tool according to one of the preceding claims, wherein the combination tool has at least one pre-drilling cutting edge (17) having a smaller pre-drilling diameter (d), which extends from the tool tip (5) over a cutting length (L) axially in the direction of the tool shank (1), and at least one peeling cutting edge (19) which lies on a larger target drilling diameter (D), characterized by that the peeling cutting edge (19) has a cutting edge (21) on its end face facing the tool tip (5), and that a drilling / deburring process is carried out with the combination tool, which process steps include: a pre-drilling step in which the combination tool is driven into the workpiece (25) with a pre-drilling stroke (hv) and a pre-drilling speed (nv) so that at the end of the pre-drilling stroke the bore edge (27) facing away from the tool is produced with the pre-drilling diameter (d) which is smaller than the target drilling diameter (D) by a material allowance (m), while the peeling cutting edge (19) is still inside the bore and offset by an axial offset (a) from the bore edge (27) facing away from the tool, a pushing step, in which the combination tool is driven with a pushing stroke (hv) through the material allowance (m) of the pilot hole inner wall, so that in the material allowance (m) across the axial offset (a) a pushing groove (29) is created, which pierces the workpiece surface (31) facing away from the tool, wherein preferably during the pushing step the peeling cutting edge (19) is guided in the pushing groove (29) without chip engagement and / or substantially without load; and a peeling step in which the combination tool is operated at a peeling speed (n A ) is operated so that the peeling cutting edge (19) peels off the remaining material allowance (m), specifically by forming the workpiece through-bore (39) with the nominal bore diameter (D) and by deburring the bore edge (27) facing away from the tool. [2] Method for drilling a workpiece through-bore (39) in a workpiece (25) and for deburring a bore edge (27) facing away from the tool, with the aid of a stepped drilling tool which has at least one pre-drilling cutting edge (17) having a smaller pre-drilling diameter (d) and extending from the tool tip (5) over a cutting length (L) axially in the direction of the tool shank (1), and at least one peeling cutting edge (19) which lies on a larger target drilling diameter (D), characterized by that a drilling / deburring process is carried out with the step drilling tool, which comprises the following process steps: a pre-drilling step in which the combination tool is driven into the workpiece (25) with a pre-drilling stroke (hv) and a drilling speed (n) so that at the end of the pre-drilling stroke the bore edge (27) facing away from the tool is produced with the pre-drilling diameter (d) which is smaller than the target drilling diameter (D) by a material allowance (m), while the peeling cutting edge (19) is still inside the bore and offset by an axial offset (a) from the bore edge (27) facing away from the tool, and a peeling step in which the step tool is operated with a peeling feed (f A ) is driven through the material allowance (m) of the pilot hole inner wall, so that the peeling cutting edge (19) peels off the material allowance (m), specifically while forming the workpiece through-hole (39) with the target hole diameter (D) and while deburring the hole edge (27) facing away from the tool. [3] Method according to claim 2, characterized by that in the peeling step the peeling feed (fA ) and the drilling speed (n) are not synchronized with each other, and / or that the peeling feed (f A ) is dimensioned substantially larger than the pre-drilling feed (fv), and / or that in particular during the peeling step the peeling cutting edge (19) is in chip engagement with the material allowance. [4] Combination tool for carrying out the method according to claim 1 or claim 2 for drilling a workpiece through-bore (39) in a workpiece (25) and for deburring a bore edge (27) facing away from the tool, with at least one pre-drilling cutting edge (17) having a smaller pre-drilling diameter (d) which extends from the tool tip (5) over a cutting length (L) axially in the direction of the tool shank (1), and with at least one peeling cutting edge (19) having a larger target drilling diameter (D), characterized by that the peeling cutting edge (19) has a cutting edge (21) on its end face facing the tool tip (5). [5] Combination tool according to claim 4, characterized by that the butting cutting edge (21) has a groove base cutting edge (33) which produces a butting groove base (36) in the butting step, and groove flank cutting edges (35) which produce butting groove flanks (37) in the butting step which are raised radially inwards from the butting groove base (36), and / or that a chip space (23) is arranged in front of the butting cutting edge (21) in the direction of the tool tip (5), and / or that the butting cutting edge (21), in particular its groove base cutting edge (33), lies on the target drilling diameter (D). [6] Combination tool according to claim 4 or 5, characterized bythat at the end of the impact stroke, the combination tool is guided to a reversal point (U), and that at the reversal point (U) the peeling cutting edge (19) is arranged at least partially within the impact groove (29), or that at the reversal point (U) the peeling cutting edge (19) is guided with a projection (x) completely beyond the bore edge (27) facing away from the tool, and / or that in particular the peeling step immediately follows the end of the impact stroke, and that in particular in the peeling step the combination tool is moved without feed, that is to say only at peeling speed (n A ), so that the peeling cutting edge (19) arranged in the butt groove (29) comes into peeling contact with the material allowance (m), in particular with a butt groove flank (37) arranged upstream in the direction of rotation (DR). [7] Combination tool according to claim 6, characterized by that in the peeling step the combination tool with the peeling speed (n A ) and a reversing feed (f R) is operated so that a burr (28) on the bore edge (27) is deburred, and / or that in particular after the peeling step a reversing step takes place in which the combination tool is guided in the reversing direction (R) out of the finished workpiece through-bore (39). [8] Combination tool according to one of claims 4 to 7, characterized by that the peeling cutting edge (19) runs helically around the tool axis (A) or in a straight line along the tool axis (A), and that the impact stroke (hs) is carried out with an impact feed (fs) and with an impact speed (ns) synchronized therewith in such a way that the impact groove (29) is produced helically, or that the impact stroke (hs) only carries out an axial movement at a speed of zero, and / or that the peeling cutting edge (19) is guided in the impact groove (29) without any load during the impact stroke (hs). [9] Combination tool according to claim 8, characterized bythat the pitch (α1) of the peeling cutting edge (19) and the pitch (α2) of the butt groove (29) are not identical, but the peeling cutting edge pitch (α1) is reduced in comparison to the butt groove pitch (α2), so that at the start of the peeling step the peeling contact between the peeling cutting edge (19) and the material allowance (m) increases continuously with continuous tool rotation.

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