DE102016214807A1 - Cutting tool with two cutting sections - Google Patents

Abstract

The invention relates to a cutting tool (30) which is adapted to produce a final contour on a disk projection (14) arranged between two blade receptacles (12) of a blade disk (10). According to the invention, it is proposed that the tool (30) has two cutting sections (32) lying opposite one another in the circumferential direction (UR), which are connected to each other via a base section (34), the two cutting sections (32) being arranged to support non-bearing flank sections (18 ) and supporting flank portions (16) of the disc protrusion (14) to obtain their final contour, and wherein the two cutting portions (32) are movably disposed relative to each other on the base portion (34).

Description

The present invention relates to a cutting tool adapted to produce a final contour on a disk projection located between two blade seats of a blade disk. Furthermore, the invention relates to a machining process for such a disc projection.

Directional details such as "axial" or "axial", "radial" or "radial" and "circumferential" are basically related to the machine axis of the rotor blade or a gas turbine, unless the context explicitly or implicitly something else results.

In the conventional production of blade receptacles, which can also be referred to as blade grooves, in compressor or turbine disks of gas turbines by machining by means of spaces, a cutting tool is guided through the blade groove. Depending on the process, resulting cutting forces are introduced in the circumferential direction (laterally) and radially into the machined non-load-bearing flank sections and bearing flank sections of the blade receptacle or disk projection. The term disk projection used here is also referred to in the art as disk hump.

In particular, in thin, filigree Scheibenvorsprungdesigns the workpiece, in particular the disc projection, during the processing elastically or elasto-plastically radially and in particular laterally (in the circumferential direction) deformed, so that after processing not the desired final contour (product shape) is achieved. In particular, the disk projection is subject to the following types of deformations: radial and circumferential deflection, tilting of the disk projection in the circumferential direction, bulging in the disk projection in the axial direction. Incidentally, the type and extent of deformation on the resulting force acting on the disc protrusion is based on the machining operation (cutting operation) and the bending rigidity of the disc protrusion itself.

The object of the invention is to provide a cutting tool and an associated method in order to avoid the above disadvantages.

To solve this problem, it is proposed that the cutting tool has two circumferentially opposite cutting sections, which are connected to one another via a base section, wherein the two cutting sections are adapted to edit non-bearing flank sections and bearing flank sections of the disc projection, so that this final Contour obtained, and wherein the two cutting portions are arranged relative to each other movable on the base portion.

By providing two cutting portions between which a respective disk projection is received and machined from both sides simultaneously, the above-mentioned deformations can be minimized. In particular, the disc projection is not tilted because it is guided from both sides by the two cutting sections. Accordingly, rather thin-walled or filigree disc projections can be produced without significant deformations.

In the tool, a distance existing between the two cutting sections in the circumferential direction can be adjustable by a spacer provided on the base section. If the distance between the two cutting sections is adjustable, a larger distance between the cutting sections arising during regrinding of the cutting sections can be compensated, so that even with repeatedly used and reground cutting sections, the substantially same final contour can still be produced on the disc projection.

The spacer element can be exchangeable. It is thought in particular that a spy plate is used as a spacer, which is used in the region of the base portion to adjust the two cutting sections to a desired distance from each other. For example, with a new set of cutting sections, a larger-sized spacer element may be provided, and with reground cutting elements, a smaller-sized spacer element may be used.

The two cutting sections can be arranged toward each other at a lead angle and be away from each other during the machining of the disc projection against the lead angle. In this case, the lead angle may in particular be selected such that an anticipated bending effect during machining in the cutting sections itself can be compensated by the lead angle.

In this case, the two cutting portions arranged toward one another under the lead angle can be pressed against the disk projection during the machining of the disk projection in the circumferential direction. As a result, the cutting sections against the Vorhaltewinkel or the angle compensation of the disc projection pushed away or bent.

The two cutting sections may have mutually facing cutting means and be dimensioned in the circumferential direction such that the cutting sections are arranged in the machining of a respective disc projection in the adjacent Schaufelfußaufnahmen, without touching adjacent blade projections.

The arranged under the lead angle cutting sections ensure that the cutting means rest optimally on the machined disc projection, in particular on its flanks.

According to a further aspect of the invention, a machining method is proposed, in particular clearing method, for producing Schaufelfußaufnahmen in a blade of a gas turbine, in particular aircraft gas turbine, wherein the Schaufelfußaufnahme a base portion, a plurality of operating in the gas turbine not carrying flank sections and a plurality of operating in the gas turbine supporting flank sections , wherein the non-load-bearing flank sections and the supporting flank sections merge into one another, comprising the steps:
Providing a blade disk to be processed;
Machining the blade disk by means of a first tool until at least two adjacent Schaufelfußaufnahmen are completed in a preform, wherein between the two adjacent Schaufelfußaufnahmen a radially projecting disk projection is formed in the preform, characterized by
final shaping of the disc projection by means of a second tool by at least one machining step, wherein the non-load-bearing flanking regions and supporting flank regions of the adjacent blade root receptacles are removed on the disc projection in order to produce the final contour for the latter, wherein the disc projection extends in the circumferential direction from both sides through the second tool is applied during machining.

The method combines, on the one hand, a conventional technique in which the blade holder (blade groove) is produced in its preform by means of the first tool, and on the other hand the technique that the disc projection formed between two blade holders is machined by the second tool, so that the one on the Disc protrusion acting resulting forces in the radial and tangential direction are as minimal as possible and do not lead to undesirable deformations.

In the method, the base portion of the blade root receiver may have its final contour before the second tool is inserted. In other words, the base portion is completed in its final contour before the disc projection.

In the method, further, a head portion of the disc protrusion may have its final contour before the second tool is inserted. As in the basic section, the head section can be finished in its final contour in front of the disc projection, in particular its flanks extending between the head section and the base section.

Furthermore, in the method as a second tool, a previously described cutting tool can be used with the two cutting sections.

In other words, this can also be described as follows. In order to prevent the deformation of the disc protrusion during the machining, a state can be achieved by changing the machining strategy from the final finishing of the blade receptacle to the final finishing of the disc protrusion, in which the process-related resulting cutting forces in the radial direction as well as in the circumferential direction almost compensate each other. There is almost no resultant force that bends or deforms the workpiece (the blade projection) during machining.

The manufacturing route differs from the conventional clearing technology as follows: Until the machining of the oversize contour (preform), the conventional process is used. Likewise, the base portion (groove bottom) and the head portion (bump head) are conventionally machined. From this initial state, the part table of the cutting machine (broaching machine) can be switched from the "blade recess center" to "disk projection center", and then all the side flanks of the disk projections can be finished in succession with the enclosing broach in a separate train.

By changing the machining strategy resulting forces on the tool, which bend this during machining to the outside. In order to compensate for this possibly occurring, negative effect, one can use the remaining space in the neighboring blade recesses to increase the bending stiffness of the tool by means of reinforcing elements, eg ribs. Another possibility would be - at reproducible conditions - during the Machining anticipated Aufbiegeeffekt held in the tool by tilting the nominal cutting contour by the expected Aufbiegewinkel to the hump so that during processing - in the bent state - actually the nominal cutting contour is processed.

The invention will be described below by way of example and not limitation with reference to the attached figures.

1 shows in a simplified schematic sectional view of a blade disc with a plurality of blade receptacles and blade projections, and a first cutting tool.

2 shows in a simplified schematic sectional view of the rotor blade of the 1 with a second cutting tool as an embodiment of the invention.

3 shows in a simplified schematic sectional view of the blade disc and two central axes of the machining.

4 shows the second tool the 2 with two different spacers.

5 shows the second tool with under a lead angle closer cutting portions and in a arranged on a disc projection state in which the cutting portions are arranged opposite to the lead angle away from each other or bent.

In 1 is a part of a blade disk 10 shown with a plurality of circumferentially UR adjacent blade receptacles 12 (Paddle grooves) and disc protrusions 14 (Disc humps). The shovel shots 12 serve to receive a blade root of a blade not shown and to secure in the circumferential direction UR and in the radial direction RR. The bucket pickup 12 has bearing flanks 16 and not bearing flanks 18 on. On the supporting flanks 16 The blade root is supported when the blade disc 10 rotates during operation and the blade is subject to centrifugal forces.

Between two disc protrusions 14 is in 1 a first cutting tool 20 shown in simplified form. Through the first cutting tool 20 becomes the vane recess 12 between two adjacent disc protrusions 14 made by machining, preferably by means of a broaching process. In the illustrated simplified example, the first tool has a tool core or center bar 22 and cutting means 24 on. The cutting means 24 have an outer contour, which is essentially the machined inner contour of the blade receptacle 12 equivalent. By means of the first tool 20 becomes the bucket pickup 12 produced in a preform. The shovel shots 12 So be using the first tool 20 pre-cleared to near the end contour of the blade receptacle to be produced 12 or the disc protrusions 14 ,

If the preform of the blade receptacle 12 is made, comes to the finishing, which can be done in one or more machining operations, a second cutting tool 30 used, which is schematic and simplified in the 2 is shown. The second tool 30 includes two cutting sections 32 that with a base section 34 are connected. Of course, this is the second tool 30 connected to a higher-level machine in a suitable manner, wherein a representation of the parent machine is omitted here. The two cutting sections 32 are designed to have the bearing flanks 16 and the non-bearing flanks 18 the shovel shots 12 to produce in their final outline. This is the second tool 30 with its two cutting sections 32 , In particular associated cutting means or cutting blades (not shown in detail) to a disc projection 14 set and this between the two cutting sections 32 added. Accordingly, the disc protrusion becomes 14 in the circumferential direction from both sides, each with a cutting section 32 charged and finally machined.

The cutting sections 32 are in particular in the circumferential direction UR dimensioned so that they are in the disk projection 14 adjacent blade receptacle 12 can be introduced without the respective adjacent disc projection 14 or its contour to touch or damage. In the 2 is greatly simplified on the right cutting section 32 an optional reinforcing element 36 shown. Such a reinforcing element, which may for example be formed as one or more reinforcing ribs, extends substantially in the radial direction RR. In the circumferential direction UR is the reinforcing element 36 depending on the space conditions in the blade receptacle 12 and the contour of the adjacent disc protrusion 14 designed. The reinforcing element 36 in particular serves for the cutting section 32 to support acting bending effects. Of course, reinforcing elements 36 at both cutting sections 32 be provided, even if this is only on the right cutting section 32 is shown as an example.

The machining or broaching by means of the first tool 20 and the second tool 30 is done by moving the tools in the axial direction, ie the direction orthogonal to Circumferential direction UR and the radial direction RR. In the 3 is illustratively a respective central axis or axis of symmetry 38 . 40 located. The axis 38 is the first tool 20 assigned and the axis 40 is the second tool 30 assigned.

From the representations of 1 to 3 It can be seen that when machining the blade disc 10 first the first tool 20 is used and the associated machine is set so that the machining of the blade receptacle 12 in relation to the axis 38 ( 3 ) he follows. Is the bucket pickup 12 almost finished, so she has her preform, comes the second tool 30 for use. Accordingly, the associated machine is set so that the machining of the disc protrusion 14 in relation to the axis 40 ( 3 ) he follows.

By using the second tool 30 for the final processing of the supporting flanks 16 and the non-bearing flanks 18 the shovel shots 12 or the disc protrusion 14 can the on the disc projection 14 acting resultant force, in particular in the radial direction and in the circumferential direction are kept low, so that undesirable deformations on the support flanks 16 and the non-bearing flanks 18 can be counteracted.

Should the in the disc projection 14 as a workpiece axially introduced machining forces or the second tool 30 bending forces are reduced, it is as a variant of in the 2 shown processing strategy (entire contour is at once by the second tool 30 manufactured) also possible, the radially inner and radially outer Tragank areas 16 respectively. 16 ' ( 2 ) to process sequentially one after the other. In this case, a transition region is to be provided between the sections to be machined. The resulting force vector of a partial region should be reduced as far as possible to zero, both in the radial direction and in the circumferential direction, so that the disc projection 14 (Disc hump) is neither pulled radially or compressed nor bent in the circumferential direction.

In the conventional clearing technique, the broaching tools are manufactured to maximum tolerance. The tools are reground regularly. By regrinding the tools, the cutting contour and thus the manufactured blade receptacle or blade groove is getting smaller. After reaching a so-called smallest measure, the tool is no longer used.

With reference to 4 it is suggested that at the second, the disc projection 14 enclosing tool 30 a spacer element 42 is provided. The spacer element 42 is set up, the two cutting sections 32 to keep at a desired distance from each other. In 4 left is a circumferentially wider spacer element 42 shown. Such a wider spacer element 42 can be used when the cutting means or cutting blades of the cutting sections 32 still new and not or hardly worn. Be the cutting means during the life of the tool 30 abraded, that is, the cutting contours are removed in the circumferential direction from each other, this can be achieved by inserting a less wide spacer 42 be compensated as right in 4 is shown. As spacers, for example, trapped spy sheets can be used. Accordingly, the regrinding state of the tool 30 be regulated. For new, large tools 30 one compensates the effect by a wide spy plate 42 , With increasing regression and a decreasing cutting contour, the circumferential extent of the cutting contour can be tracked via a reduction of the spy sheet width.

With reference to 5 is still described a lead angle, under which the two cutting sections 32 can be arranged, wherein the lead angle or an angle compensation generated thereby can be optionally provided. The cutting sections 32 subject to machining the disc protrusion 14 a bending effect, in particular in the circumferential direction UR of the disc projection 14 path. To counteract this effect, it is suggested that the two cutting sections 32 are arranged in the circumferential direction UR towards each other at a Vorhaltewinkel, which is in the upper hatched representation of the tool 30 in 5 is illustrated. The lead angle can be chosen so that a provision of the expected bending effect in the cutting sections 32 itself can be considered or compensated. That is, the two cutting sections 32 are inclined towards each other to the extent as in the machining of each cutting section 32 from the disc protrusion 14 weggebiegen or pushed away. By providing the bending effect, which is also illustrated by the two small arrows, becomes a bending effect when machining the disc projection 14 counteracted. During machining, the two cutting sections 32 pressed against the lead angle in the circumferential direction apart to along the preform of the disc projection 14 to carry out the finishing of the contour. Due to the lead angle are the cutting sections 32 optimal on the disc protrusion 14 and it can be counteracted the mentioned bending effects. For completeness, it should be noted that the cutting sections 32 , Which are arranged closer to each other at a Vorhaltewinkel, are removed by means of so-called Einfädelklingen against the Vorhaltewinkel from each other, so that they then the disc projection 14 with compensated angle can accommodate between them.

Each of the cutting sections shown in the figures 32 has corresponding cutting means or cutting blades, which are the machined to cutting disc projection 14 are facing and are not shown and described in detail here.

It is further referenced by 1 - 3 noted that when making shovel shots 12 or disc protrusions 14 a basic section 44 the bucket pickup 12 and a head section 46 of the disc protrusion 14 already finished with their final contour when the second tool 30 is used ( 2 ).

By changing the machining strategy from clearing the blade receptacle to clearing the disk protrusion provided in accordance with the proposed method, it is possible to minimize deformation of the disk protrusion during machining in the radial and circumferential directions. As a result, in particular, even thin-walled disc projections can be produced. The occurring in the conventional clearing technique errors with respect. Supporting distance and deviations in the flatness of the support flanks are avoided or at least significantly reduced.

LIST OF REFERENCE NUMBERS

10

 Blisk

12

 bucket excavation

14

 disc protrusion

16, 16 '

 supporting flank

18

 non-bearing flank

20

 first tool

22

 center web

24

 cutting means

30

 second tool

32

 cutting section

34

 Base

36

 reinforcing element

38

 Axle for bucket pickup

40

 Axle for disc protrusion

42

 spacer

44

 base portion

46

 header

RR

 radial direction

UR

 circumferentially

Claims (10)

Cutting tool ( 30 ) which is adapted to form a final contour on one between two blade receptacles ( 12 ) of a blade disk ( 10 ) arranged disc projection ( 14 ), characterized in that the tool ( 30 ) in the circumferential direction (UR) opposite cutting sections ( 32 ) having a base portion ( 34 ), wherein the two cutting sections ( 32 ) are adapted to non-load-bearing flank sections ( 18 ) and supporting flank sections ( 16 ) of the disc protrusion ( 14 ), so that they receive their final contour, and wherein the two cutting sections ( 32 ) movable relative to each other at the base portion ( 34 ) are arranged. Tool according to claim 1, wherein one between the two cutting sections ( 32 ) existing distance in the circumferential direction (UR) by a at the base portion ( 34 ) provided spacer element ( 42 ) is adjustable. Tool according to claim 2, wherein the spacer element ( 42 ) is interchangeable. Tool according to one of claims 1 to 3, wherein the two cutting sections ( 32 ) are arranged towards each other at a lead angle and during machining of the disc projection ( 14 ) are away from each other at the angle of inclination. Tool according to claim 4, wherein the two cutting sections ( 32 ) when machining the disc projection ( 14 ) in the circumferential direction (UR) against the disc projection ( 14 ) Tool according to one of claims 1 to 5, wherein the two cutting sections ( 32 ) have mutually facing cutting means and in the circumferential direction (UR) are dimensioned such that the cutting sections ( 32 ) when machining a respective Scheibenvorsprungs ( 14 ) in the adjacent blade footings ( 12 ) are arranged without adjacent blade projections ( 14 ) to touch. Machining process, in particular broaching, for the manufacture of shovels ( 12 ) in a paddle disc ( 10 ) of a gas turbine, in particular an aircraft gas turbine, wherein the blade root receiver ( 12 ) a basic section ( 44 ), several in the operation of the gastrubine not carrying flank sections ( 18 ) and several in the operation of the gas turbine bearing flank sections ( 16 ), wherein the non-load-bearing flank sections ( 18 ) and the supporting flank sections ( 16 ), comprising the steps of: providing a blade disk ( 10 ); Machining the blade disk by means of a first tool ( 20 ) to at least two adjacent blade root receivers ( 12 ) are finished in a preform, wherein between the two adjacent Schaufelfußaufnahmen ( 12 ) a radially projecting disc projection ( 14 ) is formed in the preform, characterized by final shaping of the disc projection ( 14 ) by means of a second tool ( 30 ) by at least one machining step, wherein the on the disc projection ( 14 ) on both sides non-bearing flank areas ( 18 ) and supporting flank areas ( 16 ) of the adjacent blade footings ( 12 ) are removed to produce the final contour for these, wherein the disc projection ( 14 ) in the circumferential direction (UR) from both sides by the second tool ( 30 ) is applied during machining. Method according to claim 7, wherein the basic section ( 44 ) of the blade root receiver ( 12 ) has its final contour before the second tool ( 30 ) is used. Method according to claim 7 or 8, wherein a head section ( 46 ) of the disc protrusion ( 14 ) has its final contour before the second tool ( 30 ) is used. Method according to one of claims 7 to 9, wherein as a second tool a cutting tool ( 30 ) is used according to one of claims 1 to 6.

Images