Method for producing a milled part with a countersinking tool and countersinking tool

Abstract

The invention relates to a method for producing a blisk comprising a plurality of blade profiles and channels extending between the blade profiles using a bell-type countersink having a conical lateral surface, wherein the method comprises the steps providing a disk-shaped blank, and, to form the channels in the blank, plunging the bell-type countersink into the blank on a lateral surface of the blank and thereby moving it in a direction along a generating line of the bell-type countersink, wherein the displacement of the bell-type countersink is a 3-axial movement on a linear path and/or a 5-axial movement on a curved path. The invention also relates to a bell-type countersink.

Claims

1. A method for producing a blisk comprising a plurality of blade profiles and channels extending between the blade profiles using a bell-type countersink having a conical lateral surface, wherein the method comprises the following steps: providing a disk-shaped blank, to form the channels in the blank, plunging the bell-type countersink into the blank on a lateral surface of the blank and thereby moving it in a direction along a generating line of the bell-type countersink, wherein the displacement of the bell-type countersink is a 3-axial movement on a linear path and/or a 5-axial movement on a curved path.

2. The method according to claim 1, wherein first a pre-channel is formed in the blank at a position between two blade profiles and the pre-channel is then widened in at least one direction by means of the bell-type countersink to form the channels extending between the blade profiles.

3. The method according to claim 1, wherein an allowance of at least 0.3 mm is initially left on the blade profiles during machining of the blank with the bell-type countersink.

4. The method according to claim 1, wherein the channels are first rough-machined by means of the bell-type countersink to a first depth that is less than a final depth of the channel, and then at least one of the blade flanks adjoining a channel is respectively finished to the first depth.

5. The method according to claim 4, wherein, after the finishing of the at least one blade flank to the first depth, the channels are rough-machined to a second depth by means of the bell-type countersink and then the at least one blade flank adjoining the channel is finished to the second depth.

6. The method according to claim 4, wherein all of the channels are first rough-machined to the first depth and all of the blade flanks are finished to the first depth and then all of the channels are rough-machined to the second depth.

7. The method according to claim 4, wherein a channel is first rough-machined and finished to a final depth and then an adjoining channel is machined by rough-machining and finishing.

8. The method according to claim 1, wherein, to machine the blade flanks, the bell-type countersink is moved along the blade flanks in a plurality of application directions.

9. The method according to claim 1, wherein the channels are finished by means of the bell-type countersink, wherein the displacement of the bell-type countersink during semi-finishing and/or finishing is a 5-axial movement.

10. The method according to claim 1, wherein at least two different bell-type countersinks which differ in their flank angle are used to machine the blank.

11. A bell-type countersink for carrying out a method according to claim 1, wherein the bell-type countersink comprises a base body having a conical lateral surface and receptacles for cutting inserts are present in the base body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further advantages and features of the invention result from the following description and from the accompanying drawings, to which reference is made. The drawings show:

[0037] FIG. 1 a bell-type countersink according to the invention in a perspective view,

[0038] FIG. 2 a bell-type countersink according to the invention in a sectional view,

[0039] FIG. 3 a cutting insert in the bell-type countersink in a detail view,

[0040] FIG. 4 the bell-type countersink of FIGS. 1 and 2 in an angle of engagement relative to a blisk,

[0041] FIG. 5 a bell-type countersink relative to a blisk in a plunged-in state,

[0042] FIG. 6 a partial view of a blisk in a plan view onto the blade profiles,

[0043] FIG. 7 a schematic plan view of a blade profile,

[0044] FIG. 8 a further partial view of a blisk,

[0045] FIG. 9 a bell-type countersink when machining a blisk, and

[0046] FIG. 10 a removal volume of a bell-type countersink 10.

DETAILED DESCRIPTION

[0047] FIGS. 1 and 2 each show a bell-type countersink 10. A countersink is a tool for machining a workpiece.

[0048] The bell-type countersink 10 comprises a base body 12 having a conical lateral surface 14, which results in the bell shape of the bell-type countersink 10.

[0049] The base body 12 is at least partly hollow, as a result of which the bell-type countersink 10 can plunge particularly deep into a blank to be machined.

[0050] A flank angle α of the conical base body 12 shown in FIG. 2 is between 25° and 35°, for example, in particular 30°. The flank angle α is preferably optimized to a geometry to be machined.

[0051] In the base body 12 there are receptacles 15, in which cutting inserts 16 are inserted. The cutting inserts 16 are made of ceramic, hard metal, polycrystalline cubic boron nitrate (PCBN) or polycrystalline cubic diamond (PCD), for example.

[0052] The cutting inserts 16 are fastened by means of fixing elements 18, which are screwed onto the base body 12.

[0053] FIG. 3 shows a detail view of a cutting insert 16 fastened by means of a fixing element 18.

[0054] The bell-type countersink 10 is suitable for producing a blisk 20 (blade integrated disk), comprising a plurality of blade profiles 22 and channels 24 extending between the blade profiles 22. Such a blisk 20 is illustrated in FIG. 4.

[0055] A blisk 20 is typically produced from a disk-shaped blank 26 by machining. In FIG. 4, the geometry of such blank 26 for the blisk 20 is visualized using dashed lines.

[0056] To produce the blisk 20, the bell-type countersink 10 is plunged into the blank 26 on a lateral surface 28 of the blank 26 using stabbing movements.

[0057] FIG. 4 shows the bell-type countersink 10 in a position prior to being plunged into the blank 26 and FIG. 5 shows it in a plunged-in state.

[0058] A direction of movement of the bell-type countersink 10 when plunging into the blank 26 is visualized in FIG. 4 by means of an arrow.

[0059] The bell-type countersink 10 is in particular moved in a direction along a generating line of the bell-type countersink 10. More specifically, the displacement of the bell-type countersink 10 takes place on a 3-axial linear path.

[0060] In the illustrated design example, the path is rectilinear. The path along which the bell-type countersink 10 is moved is in particular not curved.

[0061] The angle of engagement of the bell-type countersink 10 remains constant during a sequence of movements.

[0062] It is alternatively also conceivable that the displacement of the bell-type countersink 10 is 5-axial at least in one section.

[0063] A 3-axial stabbing movement of the bell-type countersink 10 along a linear path results in an annular groove having approximately the shape of an asymmetrical, elliptical hollow cylinder. FIG. 10 shows an example of a removal volume that can be achieved by the bell-type countersink 10.

[0064] A method for producing a blisk 20 from a blank 26 using a bell-type countersink 10 as shown in FIGS. 1 and 2 is explained in the following with reference to FIGS. 6 to 8.

[0065] The channels 24 extending between the blade profiles 22 are in particular first rough-machined using the bell-type countersink 10 and optionally also prefinished using the bell-type countersink 10 before a final fine machining of the blisk 20 is carried out.

[0066] Coarse machining is generally referred to as rough-machining and fine machining is referred to as finishing.

[0067] First, a pre-channel is formed at a position between two blade profiles 22. This can be accomplished by means of the bell-type countersink 10 or by means of another tool, for example by means of a side milling cutter.

[0068] The blade profiles 22 are not yet free-standing at this time, but are surrounded by solid material.

[0069] The pre-channel is then widened in at least one direction by means of the bell-type countersink 10 to form a channel 24 extending between the blade profiles 22.

[0070] FIG. 6 illustrates three examples of penetrations of the bell-type countersink 10 using the lines marked 1, 2, 3. Depending on the spacing of the blade profiles 22 and the width of the cutting inserts 16, however, more than three penetrations may be required.

[0071] According to one embodiment of the production method, the pre-channel is formed centrally between the blade profiles 22. This means that a first penetration into the blank 26 takes place along line 1.

[0072] The pre-channel extending along line 1 is then widened in both directions by means of the bell-type countersink 10. This means that the next penetrations take place along lines 2, 3.

[0073] The penetrations can, however, also be carried out in a different sequence.

[0074] The penetrations can be carried out from the suction side toward the pressure side, for example. In other words, the pre-channel is formed near the convex suction side of a blade profile 22 adjoining the channel 24 and the pre-channel is then widened toward the concave pressure side.

[0075] With reference to the example illustrated in FIG. 6, the pre-channel is formed along line 3, followed by a penetration along line 1 and lastly a penetration along line 2.

[0076] This sequence is particularly suitable when using cutting inserts 16 having a relatively low flank inclination. This avoids the cutting inserts 16 cutting on their inner flank.

[0077] Alternatively, it is also conceivable that the penetrations are carried out from the pressure side toward the suction side, i.e. in the sequence 2-1-3 of the penetrations illustrated in FIG. 6.

[0078] The machining of the concave pressure side is in particular carried out by an outer flank of the bell-type countersink 10 and the machining of the convex suction side is carried out by the inner flank of the bell-type countersink 10.

[0079] As illustrated in FIG. 7, a plurality of penetrations can be carried out near the suction side of a blade profile 22 using the bell-type countersink 10, whereby the penetrations take place at a different angle of engagement of the bell-type countersink 10 relative to the blank 26. This means that the angle of an axis of rotation R of the bell-type countersink 10 and/or the position of the bell-type countersink 10 relative to the blank 26 is changed between penetrations.

[0080] However, here too, penetration takes place in one direction along a generating line of the bell-type countersink 10.

[0081] FIG. 7 shows an example of three penetrations along the suction side of a blade profile 22 with different angles of engagement of the bell-type countersink 10.

[0082] The three penetrations are visualized in FIG. 7 using numbered lines 1, 2, 3. The respective cutting directions are visualized by means of arrows.

[0083] The illustrated penetrations can be carried out in different sequences.

[0084] For example, a central penetration, which is visualized in FIG. 7 using line 2, is carried out last. This sequence has the advantage that stabilizing material remains on the center of the flank of the blade profile 22 for as long as possible.

[0085] If the cut along line 1 is carried out last, however, the advantage is achieved that the width of the material is as small as possible when leaving the material. This sequence is most gentle on the bell-type countersink 10.

[0086] According to an alternative embodiment, only two penetrations can be carried out at a time on the suction side of a blade profile 22 at different angles of engagement of the bell-type countersink 10. In this case, slightly more residual material may remain on the blade flank than with three penetrations.

[0087] Carrying out multiple penetrations near the suction side at different angles of engagement of the bell-type countersink 10, achieves that the geometry of the blank 26 can already be particularly well approximated to a final geometry of the blisk 20. This process is also referred to as prefinishing.

[0088] This also minimizes allowance fluctuations on the flanks of the blade profiles 22. This simplifies final fine machining.

[0089] However, an allowance of at least 0.3 mm remains on the blank 26 after prefinishing.

[0090] A maximum allowance is preferably 0.6 mm.

[0091] It is also conceivable to use different bell-type countersinks 10 having different flank angles for machining the pressure side and machining the suction side.

[0092] A further aspect of a method for producing a blisk 20 using a bell-type countersink 10 is explained with reference to FIG. 8.

[0093] Rough-machining and subsequent finishing of the channels 24 can in particular be carried out in multiple stages. This means that a channel 24 is initially not rough-machined to a final depth, but only to a first depth T1. The depth T1 is visualized in FIG. 8 using a dashed line.

[0094] Rough-machining and finishing of the channels 24 can in principle be carried out in any number of stages. For the sake of simplicity, the following describes a two-stage machining operation.

[0095] Before the channel 24 is rough-machined to a final depth, the channel 24 is finished to the first depth T1. This is advantageous in terms of the behavior of the blade profiles 22 during finishing, as will be explained in more detail below.

[0096] To make it easier to follow, the various machining positions in FIG. 8 are numbered. The channels 24 in FIG. 8 are also numbered sequentially in accordance with the machining sequence.

[0097] FIG. 8 shows an already completely machined blisk 20. However, this blisk 20 is first produced by the method steps described in the following.

[0098] For example, first a first channel 24-1 is rough-machined and finished to the final depth at a position 0.

[0099] Next, an adjoining channel 24-2 (in FIG. 8, to the left of the first channel) is rough-machined to the first depth T1 at a position 1.

[0100] Rough-machining is carried out as described in connection with FIG. 6, for example, i.e. by forming a pre-channel to depth T1, which is then widened.

[0101] It is also possible, as described in connection with FIG. 7, to carry out multiple penetrations of the bell-type countersink 10 to the depth T1 at different angles of engagement in the area of a flank of the blade profile 22, in particular a prefinishing.

[0102] When the channel 24-2 has been rough-machined to the first depth T1, a flank of the blade profile 22 delimiting the channel 24-2 to the previously machined channel 24-1 is finished to the first depth T1 at a position 2.

[0103] The blade profile 22 is advantageously stabilized in the area above the first depth T1 during finishing by the solid material located below the first depth T1, so that no or only minor vibrations occur in the blade profile 22 during finishing. A lever arm is in particular shortened during finishing.

[0104] The channel 24-2 is then rough-machined and finished in a similar manner at positions 3 and 4 to a second depth, which corresponds to the final depth in the illustrated design example.

[0105] The flank face of the blade profile 22, which delimits the channel 24-2 to the as yet unmachined channel 24-3, is then finished to the final depth at position 5. The blade profile 22 is hereby supported by the solid material of the as yet unmachined channel 24-3.

[0106] The multistage machining makes it possible to change the angle of engagement of the bell-type countersink 10 between the machining steps. The rough-machining to the first depth T1 can in particular be carried out with a different angle of engagement of the bell-type countersink 10 than the rough-machining to the final depth.

[0107] The subsequent channels 24-3, 24-4, etc. are then machined in the same manner as channel 24-2, until all of the channels 24 are formed.

[0108] In the case of the last channel 24-n, the finishing of the two flanks has to be carried out in multiple stages, because the adjoining blade profile 22 cannot be stabilized since the channel 24-1 has already been opened.

[0109] In an alternative embodiment, in contrast to the sequence described above, one and the same method step can be carried out first for each channel 24.

[0110] This means that all of the channels 24 can initially be rough-machined to the first depth T1, for example. Rough-machining is in particular carried out at positions 1, 6, 11, etc.

[0111] In this case, the bell-type countersink 10 successively carries out the same penetration in all of the channels 24. For this purpose, the blank 26 is rotated so far about its central axis between each penetration that the bell-type countersink 10 can successively plunge into all of the channels 24.

[0112] Once all of the channels 24 have been rough-machined to the first depth T1, the blade profiles 22 are finished to the first depth T1 on both flanks, i.e. on the pressure side and on the suction side.

[0113] All of the channels 24 are then rough-machined and finished to the final depth in the same manner.

[0114] As can be seen in FIG. 9, due to the shape and angle of engagement of the bell-type countersink 10 on the bottom, a greater amount of residual material remains in the area of a leading edge as well as in the area of a trailing edge.

[0115] This residual material is removed with a solid carbide milling cutter, for example.

[0116] The residual material can alternatively also be removed with the bell-type countersink 10, in particular by means of a tilting movement of the bell-type countersink 10.

[0117] If the rough-machining of the channels 24 is carried out in multiple stages as described in connection with FIG. 8, residual material also remains on the intermediate bottoms. This unevenness has to be taken into account for the starting point of the paths when rough-machining to the second depth.

[0118] Lastly, the flanks of the blade profiles can be semi-finished or finished using the bell-type countersink 10. Unlike for rough-machining, the movement of the bell-type countersink 10 for finishing is preferably 5-axial.

[0119] For finishing, suitable contact paths on the blade flanks and an associated course of the angle of engagement are determined.

[0120] Because the direction of movement during finishing is not necessarily in a direction along the generating line of the base body 12, the cutting inserts 16 cannot be permitted to machine in full width. However, since the channels 24 have already been cleared to a small allowance at the time of finishing, this is not a problem in the present case.