Drill countersinking tool arrangement

Abstract

A drilling and countersinking tool arrangement comprising a drilling tool (9) and a countersink sleeve (11), wherein the drilling tool (9) has a clamping shank (13) and a drill body (15) adjoining it, along the rotational axis (R) of which at least one drill web (17) extends as far as a drill tip, and wherein the drilling tool (9) projects through the countersink sleeve (11), which has a countersink sleeve cutting edge (37) on its end face facing the drill tip, which is set back from the drill tip by an axial distance (Δa), so that in a drilling process, the drilling tool (9) can be driven into a workpiece (1) with a drilling stroke to create a workpiece bore (5), and in the further course of the drilling process, the countersink sleeve (11) with its countersink sleeve cutting edge (37) comes into chip engagement with the opening edge region of the workpiece bore (5) in order to perform a face machining of the opening edge region,wherein the drilling tool (9) for producing a borehole chamfer (7) has a chamfer cutting edge (26), the cutting edge diameter of which widens conically in the direction of the clamping shaft (13), and wherein the countersink sleeve cutting edge (37) is arranged in an axial height position which, viewed in the axial direction, is located between an end of the chamfer cutting edge (26) facing away from the drill tip and an end of the chamfer cutting edge (26) facing the drill tip, , characterized in that at the axial height of the countersunk sleeve cutting edge (37), a radially inner cutting edge corner (43) of the countersunk sleeve cutting edge (37) lies on an inner diameter which is smaller than the outer diameter of the drilling tool (9), and that in the clamped state, the countersink sleeve (11) and the drilling tool (9) are spaced apart from each other without contact via an annular gap (41).

Description

[0001] The invention relates to a drilling countersinking tool arrangement according to the preamble of claim 1, a drilling tool according to the preamble of claim 8 and a countersinking sleeve according to the preamble of claim 9.

[0002] Such a drilling and countersinking tool arrangement is used, for example, in vehicle construction when producing a cylinder head bore and for facing an opening edge area of ​​the cylinder head bore, which may have to fulfil a sealing function.

[0003] In a process for machining such a workpiece, the first step involves pre-milling, in which a first milling tool pre-mills the tool surface to be machined with an allowance. This is followed by finish milling in a second step, in which the allowance is milled off the tool surface to be machined. In a final third step, a drilling tool is driven into the solid workpiece material on the flat-machined tool surface to create a workpiece bore.

[0004] To reduce the manufacturing and process complexity involved in machining the workpiece, a generic countersinking tool assembly is provided. This comprises a drilling tool with a clamping shank and an adjoining drill body. At least one drill web with at least one supporting chamfer extends along the axis of rotation of the drill body to a drill tip. The drilling tool is guided by a countersink sleeve, which has a countersink sleeve cutting edge on its end face facing the drill tip. This cutting edge is set back from the drill tip by an axial distance. This tool combination enables the following machining process: The drilling tool is driven into the workpiece with a drilling stroke to create a workpiece bore.At the end of the drilling stroke, the countersink sleeve with its countersink cutting edge comes into chip engagement with the opening edge area of ​​the workpiece bore, whereby the opening edge area of ​​the workpiece bore is machined flat.

[0005] This arrangement presents, among other things, the following problems: If the countersink sleeve and the drilling tool are designed as separate components, an annular gap inevitably forms between them. At the end of the drilling stroke, when the countersink sleeve cutting edge comes into contact with the surface edge of the workpiece, a slug or accumulation of material can build up in this annular gap, which can lead to premature tool breakage.

[0006] Countersinking tools are known from US 4 353 670 A, US 8 469 642 B1, DE 31 25 480 A1, DE 20 62 757 C, and CH 582 554 A5. DE 10 2019 203 531 A1 discloses a drilling / chamfering tool comprising a longitudinally extending drill with a clamping sleeve designed to receive and fix the drill in a variable-length manner. US 2005 / 0047882 A1 discloses a tool comprising a drill and a countersink attached to the drill. The drill has a protruding web and at least one chip flute. The countersink comprises a plurality of adjustable inserts.

[0007] The object of the invention is to provide a drilling and countersinking tool arrangement which enables a more reliable machining of a workpiece compared to the prior art.

[0008] The object is achieved by the features of claim 1, 8 or 9. Preferred developments of the invention are disclosed in the subclaims.

[0009] The invention is based on a countersinking tool arrangement comprising a drilling tool and a countersink sleeve. The drilling tool is designed with a clamping shank and an adjoining drilling body, along the rotational axis of which at least one drill web with at least one supporting chamfer extends to a drill tip. The drilling tool projects through the countersink sleeve. On its end face facing the drill tip, the latter has a countersink sleeve cutting edge running in particular transversely to the rotational axis. The countersink sleeve cutting edge is set back from the drill tip by an axial distance. A drilling process is thus carried out as follows: First, the drilling tool is driven into the solid material of a workpiece with a drilling stroke to a desired drilling depth in order to create a workpiece bore.As the drilling process continues, for example towards the end of the drilling stroke, the countersink sleeve comes into chip engagement with its cutting edge into the opening edge area of ​​the workpiece bore in order to machine the surface of the opening edge area by removing material. The countersink sleeve and the drilling tool are inserted into one another as separate components. Accordingly, an annular gap forms between the inner circumference of the countersink sleeve and the drilling tool. When the countersink sleeve cutting edge comes into chip engagement with the workpiece surface, there is a risk of material build-up in the annular gap. To avoid this, the following measure is provided according to the characterizing part of claim 1: A radially inner cutting edge corner of the countersink sleeve cutting edge lies on an inner diameter which, at the level of the countersink sleeve cutting edge, is smaller than the outer diameter of the drilling tool.Accordingly, the countersink cutting edge overlaps the annular gap between the countersink and the drilling tool with an excess. This ensures that there is no interruption in the cutting action in the annular gap, preventing material buildup in the annular gap.

[0010] According to the invention, the countersink sleeve and the drilling tool interact only functionally to keep the annular gap free of workpiece material. Direct mechanical coupling between the countersink sleeve and the drilling tool, however, should be avoided in order to reduce tool stress during the drilling process. Against this background, according to the invention, the countersink sleeve and the drilling tool are mechanically decoupled from each other, i.e., they are essentially not connected to each other in a force-transmitting manner, and / or, when clamped, are spaced apart from each other via the annular gap without contact.

[0011] The countersinking tool assembly can have a chuck that serves as a tool holder for the countersink sleeve and the drilling tool. The chuck can be attached to a machine spindle of a machine tool via an adapter. It is preferred if the drilling tool and the countersink sleeve can be clamped independently of each other in the chuck. In this case, the drilling tool and the countersink sleeve can be mounted and removed from the chuck independently of each other. When not clamped, the drilling tool and the countersink sleeve can be loosely inserted into one another as separate components with some play.

[0012] To avoid a collision between the drilling tool and the countersink sleeve, the drilling tool can have a clearance into which the countersink sleeve projects with its cutting edge with radial excess. The clearance can extend along the rotation axis of the drilling tool. It is preferred if the countersink sleeve cutting edge does not project directly into a chip space of the drilling tool, but rather into a clearance formed on the back of the drill bit of the drill web. This can be implemented as a web groove. The web groove can be defined by two support chamfers spaced apart from one another in the circumferential direction of the drill bit with an intermediate groove base. The groove base can be set back radially inwards by one groove depth compared to the support chamfers. The groove depth is dimensioned such that a collision with the radially inner cutting corner of the countersink sleeve can be avoided.

[0013] In the bore geometry to be produced, the workpiece bore transitions into the flat-machined opening edge area at a borehole chamfer. For this purpose, the drilling tool has at least one chamfer cutting edge. The longitudinal edge of the drill bit, running along the rotational axis of the drilling tool, transitions into the chamfer cutting edge toward the clamping shank. The cutting edge diameter widens conically toward the clamping shank to create the desired borehole chamfer.

[0014] To produce the bore geometry described above, the countersink cutting edge and the chamfer cutting edge overlap each other, viewed circumferentially. In this case, the countersink cutting edge is positioned at an axial height that, viewed in the axial direction, is located between an end of the chamfer cutting edge facing away from the drill tip and an end of the chamfer cutting edge facing the drill tip.

[0015] For easy assembly / disassembly of the countersink sleeve with the drilling tool, it is advantageous if the clearance extends all the way to the drill tip. In this case, the clearance at the drill tip can be open, allowing the countersink sleeve to be inserted onto the drilling tool with its radially inwardly projecting cutting edge in one direction from the drill tip to the clamping shank, and to be removed from it in the opposite direction.

[0016] Alternatively and / or additionally, the clearance can extend to the shank-side tool end facing away from the drill tip. In this case, the clearance is open at the shank-side tool end, allowing the countersink sleeve to be inserted into the drilling tool in one direction from the clamping shank to the drill tip and removed from it in the opposite direction.

[0017] The chuck for clamping the drilling tool and the countersink sleeve can have a clamping channel that has a large-diameter countersink sleeve clamping point for clamping the countersink sleeve and a small-diameter clamping shaft clamping point for clamping the clamping shaft. The larger-diameter countersink sleeve clamping point can be arranged directly at an outlet opening of the clamping channel, while the smaller-diameter clamping shaft clamping point is axially spaced therefrom.

[0018] It is preferred if the chuck is a shrink-fit chuck. Its clamping channel has an inner diameter that is smaller than the diameter of the countersunk sleeve and the clamping shank at ambient temperature and when unloaded. The clamping channel of the shrink-fit chuck can expand under the influence of heat. This allows the countersunk sleeve and the drilling tool to be inserted into the expanded clamping channel. Upon cooling, the shrink-fit chuck is shrunk onto the countersunk sleeve and the clamping shank.

[0019] An embodiment of the invention is described below with reference to the figures.

[0020] They show: Fig. 1 to 8 different views illustrating the drilling and countersinking tool arrangement according to the invention.

[0021] In the Fig. Figure 1 shows a workpiece 1 machined with a countersinking tool according to the invention. Using the countersinking tool, a planar workpiece surface 3 is machined to a desired dimension. Furthermore, using the countersinking tool, a bore 5 is driven into the solid workpiece material in the workpiece surface 3. The bore 5 transitions at a bore chamfer 7 into the opening edge area of ​​the bore 5 or into the planar workpiece surface 3.

[0022] The Fig. The workpiece geometry indicated in Figure 1 is determined using the following Fig. 2 to 7. The drilling tool is manufactured according to Fig. 2 to 7 are constructed in two parts with a drilling tool 9 and a countersunk sleeve 11. The drilling tool 9 is designed as a spiral drilling tool with a clamping shaft 13 and an adjoining drilling body 15 ( Fig. 5). The drill body 15 is double-edged with a total of two drill webs 17 ( Fig. 3 or Fig. 6) are formed, which extend spirally along a rotational axis R of the twist drilling tool 9 up to a drill tip. The two drill webs 17 are connected in the circumferential direction of the drill via drill flutes 19 ( Fig. 3 or Fig. 6) are spaced apart from each other. In addition, the drill webs 17 are arranged according to the Fig. 3 or Fig. 6 are point-symmetrical to each other with respect to the rotation axis R.

[0023] Each of the drill flutes 19 extends in the direction of the drill tip to a transverse main cutting edge 21 ( Fig. 2 or Fig. 3). On the main cutting edge 21 there is a chip surface 23 ( Fig. 6) of the drill flute 19 and a frontal clearance surface 24 ( Fig. 3) of the drill tip. In addition, the chip surface 23 of the drill flute 19 merges into a supporting chamfer 27 ( Fig. 3 or Fig. 6). The main cutting edge 21 and spiral drill longitudinal edge 25 of the drilling tool 9 run along a frontal, radially outer cutting edge 29 ( Fig. 2) together.

[0024] Each drill bit web 5 has a total of two support lands 27, 31 on its drill bit back. The two support lands 27, 31 are spaced apart in the circumferential direction by a groove width of a web groove 33. The web groove 33 also has a groove bottom 35 ( Fig. 6).

[0025] The drilling tool 9 is, for example, in the Fig. 2 is guided through the countersink sleeve 11. This has on its end face facing the drill tip two countersink sleeve cutting edges 37 which are diametrically opposed with respect to the rotation axis R and are spaced apart by an axial distance Δa ( Fig. 7) are set back from the drill tip of the drilling tool 9. The two countersunk cutting edges 37 are in the circumferential direction over chip spaces 39 ( Fig. 4 or Fig. 6) spaced apart.

[0026] According to the invention, the drilling tool 9 and the countersink sleeve 11 are realized as two separate components, which are Fig. 4 and Fig. 5 are each shown individually. The drilling tool 9 and the countersunk sleeve 11 can be loosely inserted into one another with some play. To carry out a drilling process, the drilling tool 9 and the countersunk sleeve 11 are mounted in a shrink chuck 41 ( Fig. 3 or Fig. 7), in which the drilling tool 9 and the countersink sleeve 11 are clamped independently of each other. In the unclamped state, however, the drilling tool 9 is loosely mounted in the countersink sleeve 11 with some play.

[0027] To generate the Fig. 1, the countersinking tool is driven into the workpiece solid material with a drilling stroke on the still unmachined workpiece surface 3 to a desired drilling depth, whereby the workpiece bore 5 is formed. At the end of the drilling stroke (roughly schematically in the Fig. 2), the countersink sleeve 11 with its countersink cutting edges 37 comes into chip engagement with the opening edge area of ​​the workpiece bore 5, whereby the opening edge area of ​​the bore 5 is machined flat.

[0028] As exemplified in the Fig. 2, the drilling tool 9 has two chamfer cutting edges 26. The cutting diameter of the respective chamfer cutting edge 26 widens conically towards the clamping shank 13. During the drilling process, the chamfer cutting edges 26 of the drilling tool 9 create the bore chamfer 7. According to the Fig. 2, each of the countersunk cutting edges 37 overlaps with one of the chamfer cutting edges 26, viewed in circumferential overlap. For this purpose, the countersunk cutting edges 37 are arranged in an axial height position which, viewed in the axial direction, is located between an end of the chamfer cutting edge 26 facing away from the drill tip and an end of the chamfer cutting edge 26 facing the drill tip.

[0029] The creation of the bore chamfer 7 and the planar machining of the workpiece surface 3 takes place at the end of the drilling stroke. The following problem arises especially at the end of this drilling stroke: Between the inner circumference of the countersink sleeve 11 and the drilling tool 9 there is a Fig. 2 or Fig. 6 exaggeratedly large) annular gap 41. At the end of the drilling stroke, a slug of material or an accumulation of material can build up in this annular gap 41, which may lead to premature tool breakage of the drilling tool 9.

[0030] To avoid this, the following measures are taken according to the invention: According to the Fig. 2 or Fig. 6 a radially inner cutting edge 43 of the respective countersunk sleeve cutting edge 37 with a radial oversize Δr ( Fig. 2) is extended radially inward. The radially inner cutting edge 43 of the respective countersunk sleeve cutting edge 37 therefore projects into the web groove 33 on the drill back of the respective drill web 17. The web groove 33 therefore acts as a clearance into which the radially inner cutting edge 43 of the countersunk sleeve cutting edge 11 projects without contact. In this way, the annular gap 41 between the countersunk sleeve 43 and the drilling tool 9 is radially overlapped. With the radially inner oversize Δr ( Fig. 2) the countersunk sleeve cutting edge 37, the material slug that builds up in the annular gap 41 is easily removed by machining.

[0031] In the Fig.Figure 8 shows the shrink-fit chuck 40 in isolation. Accordingly, the shrink-fit chuck 40 has a clamping channel 45, which is configured with a large-diameter countersunk sleeve clamping point 47 for clamping the countersunk sleeve 11 and a smaller-diameter clamping shaft clamping point 49 for clamping the clamping shaft 13. The larger-diameter countersunk sleeve clamping point 47 is arranged directly at an outlet opening of the clamping channel 45, while the smaller-diameter clamping shaft clamping point 49 is axially spaced therefrom.

[0032] At ambient temperature and in the unloaded state, the clamping channel 45 of the chuck 40 has an inner diameter that is smaller than the diameter of the countersunk sleeve 11 and the clamping shaft 13. Under the influence of heat, the clamping channel 45 of the shrink-fit chuck 40 can be expanded, so that the drilling tool 9 and the countersunk sleeve 11 can be inserted into the expanded clamping channel 45. Upon cooling, the shrink-fit chuck 40 is shrunk onto the countersunk sleeve 11 and the clamping shaft 13 of the drilling tool 9. LIST OF REFERENCE SYMBOLS: 1 workpiece 3 Workpiece surface 5 Hole 7 Bore chamfer 9 Drilling tool 11 Countersunk sleeve 13 clamping shaft 15 drill bodies 17 Drill bridge 19 flute 21 Main cutting edge 23 clamping surface 24 Frontal clearance 25 drill longitudinal edge 27 Support chamfer 29 Cutting corner 31 support chamfer 33 web groove 35 groove bottom 37 Countersunk sleeve cutting edge 39 chip space 40 chucks 41 Annular gap 43 radial inner cutting corner of the countersunk sleeve 45 clamping channel 47 Countersunk sleeve clamping point 49 Clamping shaft clamping point R rotation axis Δr radial interference

Claims

[1] Drilling and countersinking tool arrangement with a drilling tool (9) and a countersink sleeve (11), wherein the drilling tool (9) has a clamping shaft (13) and a drill body (15) adjoining thereto, along the rotational axis (R) of which at least one drill web (17) extends as far as a drill tip, and wherein the drilling tool (9) projects through the countersink sleeve (11), which has a countersink sleeve cutting edge (37) on its end face facing the drill tip, which is set back from the drill tip by an axial distance (Δa) so that in a drilling process the drilling tool (9) can be driven into a workpiece (1) with a drilling stroke to produce a workpiece bore (5), and in the further course of the drilling process the countersink sleeve (11) with its countersink sleeve cutting edge (37) comes into chip engagement with the opening edge region of the workpiece bore (5) in order to face the opening edge region to carry out,wherein the drilling tool (9) for producing a borehole chamfer (7) has a chamfer cutting edge (26), the cutting edge diameter of which widens conically in the direction of the clamping shaft (13), and wherein the countersink sleeve cutting edge (37) is arranged in an axial height position which, viewed in the axial direction, is located between an end of the chamfer cutting edge (26) facing away from the drill tip and an end of the chamfer cutting edge (26) facing the drill tip, characterized by , that at the axial height of the countersunk sleeve cutting edge (37), a radially inner cutting edge corner (43) of the countersunk sleeve cutting edge (37) lies on an inner diameter which is smaller than the outer diameter of the drilling tool (9), and that in the clamped state, the countersink sleeve (11) and the drilling tool (9) are spaced apart from each other without contact via an annular gap (41). [2] Drilling and countersinking tool arrangement according to claim 1, characterized bythat the radially inner cutting corner (43) of the countersunk sleeve cutting edge (37) is extended radially inwards by an excess (Δr), and / or that the countersunk sleeve cutting edge (37) radially overlaps the annular gap (41) between the countersunk sleeve (11) and the drilling tool (9) so that there is no cutting interruption in the area of ​​the annular gap (41) and therefore a material build-up in the annular gap (41) is prevented. [3] Drilling and countersinking tool arrangement according to claim 1 or 2, characterized by , that the drilling and countersinking tool arrangement comprises a chuck (40) in which the drilling tool (9) and the countersinking sleeve (11) can be clamped independently of one another, and / or that in the unclamped state, the drilling tool (9) and the countersunk sleeve (11) can be loosely inserted into one another as separate components with play, and / or that the drilling tool (9) has a clearance (33) into which the countersink sleeve (11) projects with its countersink sleeve cutting edge (37). [4] Drilling and countersinking tool arrangement according to claim 3, characterized by that the clearance (33) extends along the axis of rotation (R) of the drilling tool (9), and that the clearance (33) is formed on the drill back of the drill web (17), specifically as a web groove, and that the web groove (33) is defined by two support chamfers (27, 31) spaced apart from one another in the circumferential direction of the drill with an intermediate groove base (35) which is set back radially inwards by a groove depth relative to the support chamfers (27, 31). [5] Drilling and countersinking tool arrangement according to one of claims 3 or 4, characterized bythat the clearance (33) extends to the drill tip and is open at the drill tip, so that the countersunk sleeve (11) can be plugged onto the drilling tool (9) in a plug-in direction from the drill tip to the clamping shaft (13) and can be removed therefrom in the opposite direction, and / or that the clearance (33) extends to the shaft-side tool end facing away from the drill tip, i.e. is open at the tool end, so that the countersunk sleeve (11) can be plugged onto the drilling tool (9) in a plug-in direction from the clamping shaft (13) to the drill tip and can be removed therefrom in the opposite direction. [6] Drilling and countersinking tool arrangement according to one of the preceding claims, characterized bythat the chuck (40) has a clamping channel (45) which has a large-diameter countersunk sleeve clamping point (47) for clamping the countersunk sleeve (11) and a small-diameter clamping shaft clamping point (49) for clamping the clamping shaft (13), and that the larger-diameter countersunk sleeve clamping point (47) is arranged directly at an outlet opening of the clamping channel (45), while the smaller-diameter clamping shaft clamping point (49) is axially spaced therefrom. [7] Drilling and countersinking tool arrangement according to one of the preceding claims, characterized bythat the chuck (40) is a shrink chuck, the clamping channel (45) of which has an inner diameter which is reduced compared to the diameter of the countersunk sleeve (11) and the clamping shaft (13) at ambient temperature and in the unloaded state, and that the clamping channel (45) of the shrink chuck (40) can be expanded under the influence of heat, so that the drilling tool (9) and the countersunk sleeve (11) can be inserted into the expanded clamping channel (45), and that the shrink chuck (40) can be shrunk onto the countersunk sleeve (11) and the clamping shaft (13) when cooled. [8] Drilling tool (9) for a drilling and countersinking tool arrangement according to one of the preceding claims, wherein the drilling tool (9) has a clamping shank (13) and a drill body (15) adjoining it, along the rotational axis (R) of which at least one drill web (17) extends as far as a drill tip, and wherein the drilling tool (9) projects through a countersink sleeve (11) which, on its end face facing the drill tip, has a countersink sleeve cutting edge (37) which is set back from the drill tip by an axial distance (Δa), so that in a drilling process, the drilling tool (9) can be driven into a workpiece (1) with a drilling stroke to create a workpiece bore (5), and in the further course of the drilling process, the countersink sleeve (11) with its countersink sleeve cutting edge (37) comes into chip engagement with the opening edge region of the workpiece bore (5) in order to perform a face machining of the opening edge region,wherein the drilling tool (9) for producing a borehole chamfer (7) has a chamfer cutting edge (26), the cutting edge diameter of which widens conically in the direction of the clamping shaft (13), and wherein the countersink sleeve cutting edge (37) is arranged in an axial height position which, viewed in the axial direction, is located between an end of the chamfer cutting edge (26) facing away from the drill tip and an end of the chamfer cutting edge (26) facing the drill tip, characterized by , that at the axial height of the countersunk sleeve cutting edge (37), a radially inner cutting edge corner (43) of the countersunk sleeve cutting edge (37) lies on an inner diameter which is smaller than the outer diameter of the drilling tool (9), and that in the clamped state, the countersink sleeve (11) and the drilling tool (9) are spaced apart from each other without contact via an annular gap (41). [9] Countersink sleeve (11) for a drilling and countersinking tool arrangement according to one of the preceding claims, through which countersink sleeve (11) a drilling tool (9) projects, which has a clamping shaft (13) and a drill body (15) adjoining thereto, along the rotational axis (R) of which at least one drill web (17) extends as far as a drill tip, and wherein the countersink sleeve (11) has, on its end face facing the drill tip, a countersink sleeve cutting edge (37) which is set back from the drill tip by an axial distance (Δa), so that in a drilling process the drilling tool (9) can be driven into a workpiece (1) with a drilling stroke to produce a workpiece bore (5), and in the further course of the drilling process the countersink sleeve (11) with its countersink sleeve cutting edge (37) comes into chip engagement with the opening edge region of the workpiece bore (5) in order to face the opening edge region to carry out,wherein the drilling tool (9) for producing a borehole chamfer (7) has a chamfer cutting edge (26), the cutting edge diameter of which widens conically in the direction of the clamping shaft (13), and wherein the countersink sleeve cutting edge (37) is arranged in an axial height position which, viewed in the axial direction, is located between an end of the chamfer cutting edge (26) facing away from the drill tip and an end of the chamfer cutting edge (26) facing the drill tip, characterized by , that at the axial height of the countersunk sleeve cutting edge (37), a radially inner cutting edge corner (43) of the countersunk sleeve cutting edge (37) lies on an inner diameter which is smaller than the outer diameter of the drilling tool (9), and that in the clamped state, the countersink sleeve (11) and the drilling tool (9) are spaced apart from each other without contact via an annular gap (41).

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