WO2016181067A1

WO2016181067A1 - Method and system for simulating wear of a tooth of a broach used to broach cavities, particularly for turbomachine compressor or rotor disks

Info

Publication number: WO2016181067A1
Application number: PCT/FR2016/051099
Authority: WO
Inventors: Sébastien MANDRILE; Gilles DESSEIN; Vincent WAGNER
Original assignee: Turbomeca
Priority date: 2015-05-13
Filing date: 2016-05-11
Publication date: 2016-11-17
Also published as: FR3036049A1; FR3036049B1

Abstract

The invention relates to a method for simulating the wear of a tooth of a broach, comprising a step of machining a test part (10) using a turning tool (3) comprising an active section (2), during which said test part (10) and the turning tool (3) are moved in relative movements such that, in a referential relating to the turning tool (3), the test part is rotated about an axis (A) while the turning tool (3) is progressively moved in the test part (10), the active section (2) of the turning tool (3) thereby machining a front annular groove (13) in said test part.

Description

METHOD AND SYSTEM FOR SIMULATING WEAR OF A TOOTH OF A PIN FOR ALVEOLING PINK, IN PARTICULAR FOR DISC OF ROTORS OR

TURBOMACHINE COMPRESSORS

FIELD OF THE INVENTION

The present invention relates to wear tests of pins, in particular pins for pinning cells for parts such as turbine rotor disks or turbomachine compressor disks.

STATE OF THE ART

Conventionally, an aircraft turbine engine or turboprop engine comprises a compressor part and a rotary turbine. This turbine itself comprises a rotor disk which has peripheral fasteners (so-called "fir-tree" or "bulbs" shaped cells) which are distributed around its circumference and which receive and hold the blade roots of said turbine . Some compressor disks also have such fasteners.

These fasteners are generally machined in a turbomachine disk by broaching. To this end, several passes are made by means of a spindle in a cell to be machined. This is illustrated in FIGS. 1 and 2, on which is represented a pin 9 intended to machine cavities in a turbomachine disk 4.

Said pin 9 has several teeth 8, two successive teeth 8 being separated in pairs by a core 5.

Pin 9 is for example tungsten carbide or tungsten steel, which is an alloy of iron-carbon plus tungsten, cobalt, manganese, chromium, vanadium, molybdenum, and which is commonly called special high speed steel.

When pinning a cell, several passes of the spindle are made in the cell to be machined, a different tooth 8 removing material at each pass.

The main stitching parameters are:

- the cutting angle y, - the draft angle a,

- the pitch P,

the flute radius ( _flute ),

- the chip chamber depth (c),

- the advance by fixed tooth (f),

- cutting speed.

All of these parameters except the cutting speed are defined by the shape of pin 9. Once the part which constitutes the pin 9 manufactured, only the cutting speed can be adjusted. The way spindle 9 will wear out during broaching depends on all other parameters and can only be determined by performing a machining test with spindle 9.

However, as the broaching of a cell requires several passes of the pin 9, a different tooth 8 removing material at each pass, the time required to significantly wear a tooth 8 of the spindle by machining cells with it is important.

In addition, the time required to machine a cell is decomposed into two phases: a machining phase, during which the factory spindle, and a repositioning phase during which pin 9 does not machine and does only return to its starting point to prepare the next machining phase. The teeth 8 only wear out during the machining phase, and the time required to significantly wear a tooth 8 of the spindle 9 is all the more important.

For example, for a spindle length of 2 meters and a cutting speed of 2 meters / minute, the machining time is 60 seconds. The rise time of pin 9 to return to the starting point is 30 seconds (90 seconds in total). Machining is done in two lines of pins (one for roughing and one for finishing), the machining time of a cell is 180 seconds. For example, for a machining test on a workpiece of L _B = 15 mm thick, to machine 30 m it is necessary to broach 2000 cells, which requires 100 hours of machining.

In addition, testing a pin 9 on a piece intended to be stitched involves the destruction of this piece. However, particularly in the case of rotor disks from Turbine turbines or turbomachine compressor disks, these parts are very expensive.

It has already been proposed to simulate the machining of the pins 9 by machining disc-shaped test pieces 20 with turning tools 3 on the turning tool 3 machining the periphery of the disc. This is illustrated in Figure 3a. This solution is nevertheless unsatisfactory because the clearance angle between the turning tool 3 is the periphery of the disc 20 is not constant (Figure 3b).

As illustrated in FIG. 3c, it has also been proposed to simulate the machining of the pins 9 by machining test pieces in the form of a tube 30 with turning tools 3 comprising an active part 2 identical to the tooth 8 of the spindle. 3 to be tested, the turning tool 3 machining the edge of the tube 30. This solution is also unsatisfactory because only the tip of the turning tool 3 is in contact with the test piece, the sides of the turning tool. 3 not being in contact with the test piece (Figure 3d).

In addition, both in the case of a disk-shaped test piece and a tube-shaped test piece, the test piece does not make it possible to reproduce the shocks suffered by a pin 3 during the pin assignment. a cell at the time of transition between the repositioning phase and the machining phase. SUMMARY OF THE INVENTION

The invention overcomes the disadvantages of the test techniques known to date.

It proposes in particular a method for simulating wear of a tooth of a spindle, comprising a step of machining a test piece by means of a turning tool comprising an active part identical to the tooth of the spindle. during which said test piece and the turning tool are moved in relative motions such that, in a reference frame related to the turning tool, the test piece is rotated about an axis, while that the turning tool is progressively moved in the test piece, the active part of the turning tool thus machining a frontal annular groove therein. The proposed method makes it possible to simulate the wear of a spindle by reproducing certain characteristics of the broaching of a cell in a turbomachine disk.

The fact that the tooth mills a front annular groove makes it possible to have a contact of the two lateral edges of the turning tool with the test piece.

The proposed method also makes it possible to considerably reduce the time required to evaluate the wear of a pin intended to pin cells relative to a conventional wear test of machining cells with the pin to be tested.

Indeed, when pinning a cell, several teeth of the spindle machine one after the other, each tooth removing additional material relative to the previous tooth, while in the proposed simulation method, a single tooth is used continuously. Since all the teeth of the spindle are identical to a scale factor, the wear of a tooth during a test according to the proposed method makes it possible to evaluate how the set of teeth of the spindle would be worn if the pin was used to broach a cell. The method thus makes it possible to divide the duration of the wear test, with respect to the duration of a conventional wear test on the workpiece, by the number of teeth present on a spindle.

In addition, in the proposed simulation method, there are no repositioning steps of the spindle during which the spindle does not machine, which further reduces the duration of the test compared to the duration of the spindle. a standard wear test on the workpiece.

Also, the proposed method makes it possible to perform a spindle wear test not on the part intended to be stitched but on a part which is less expensive to manufacture while being made of the same material as the part intended to be used. paperback.

The invention is advantageously completed by the following characteristics, taken individually or in any of their technically possible combinations: ^■ the test piece can be cylindrical in shape, with a front annular groove which allows to maintain a constant draft angle;

^■ the test piece may have a side surface in which are formed lateral grooves distributed on the periphery of the test piece; the grooves make it possible to reproduce the shocks due to the succession of machining and repositioning phases characteristic to the pinning of cavities;

^■ the lateral grooves are formed in the test piece with a side wall, the side of the groove for engagement by the tooth, which extends in the test piece parallel to an axis at a non-zero angle radially passing through the axis of the test piece and the middle of said flank wall;

^■ the spindle is of the type intended for the broaching of recesses, in particular for rotors or discs of a turbomachine compressor;

^■ the spindle is of the type for machining of the cavities with a predetermined pin angle, and wherein the grooves are formed in the test piece with a side wall, the side of the groove for engagement by the tooth, which extends in the test piece parallel to an axis at an angle, with respect to the radial plane passing through the axis of the test piece and the middle of said flank wall, equal to the predefined pinning angle;

^■ said angle is between 5 ° and 20 °;

^■ the ratio of the width of the annular groove and the diameter of the annular groove is less than 10%;

^■ several turning tools each simultaneously machine a front annular groove on the same test piece;

The invention also proposes a system for simulating the wear of a tooth of a spindle, the wear test system comprising:

- a test piece;

a turning tool comprising an active part identical to the tooth of the spindle to be tested; a machine tool configured to control the relative movements between the test piece and the turning tool, the test piece being, in a reference frame linked to the turning tool displaced in rotation about an axis, while the The turning tool is progressively moved into the test piece, the active part of the turning tool thus machining a frontal annular groove in the test piece.

The test piece can be, in particular, one of the materials of the following list: nickel base alloy, cast iron, aluminum base alloy, titanium base alloy. DESCRIPTION OF THE FIGURES

Other objectives, features and advantages will be further apparent from the detailed description which follows with reference to the drawings given by way of non-limiting illustration, among which:

- Figures 1 and 2, already discussed, represent pins for machining alveoli fir feet;

FIG. 3a, also already discussed, illustrates the machining of a disc-shaped test piece by a turning tool comprising an active part, FIG. 3b being in its view an enlarged view of FIG. 3a around the active part of the turning tool;

FIG. 3c illustrates the machining of a tube-shaped test piece by a turning tool comprising a tooth, FIG. 3d being for its part an enlarged view of FIG. 3c around the tooth of the tool of FIG. filming;

FIG. 4 represents a test piece of a system according to a possible embodiment of the invention;

FIG. 5 shows the machining of a test piece according to a method according to the invention;

- Figure 6 shows a close view of Figure 5 around the active part of the turning tool;

- Figure 7 shows a turbomachine disk in which is formed a cell; FIG. 8 is a close-up view around the cell of the turbomachine disk of FIG. 7;

FIG. 9 represents a test piece;

FIG. 10 is a close-up view around two grooves of the test piece of FIG. 9;

- Figure 1 1 is a front view of the test piece of Figure 9;

- Figure 12 is a detail view of Figure 1 1;

FIG. 13 is a side view of the test piece of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

In what follows, reference is made to FIGS. 4 and following an exemplary method of simulating wear of a pin 9 of the type illustrated in FIGS. 1 and 2 comprising a series of teeth 8.

During the wear test method, a test piece 10 is machined by turning, by means of a turning tool 3, as illustrated in FIG.

The turning tool 3 comprises a handle 31 ending in a head 32. The handle 31 is fixed to the machine tool by a tool holder.

The head 32 carries an active part 2. The active part 2 comprises a cutting face, a flank face and at least one cutting edge. The active part 2 is the part of the tool that intervenes directly in the cutting operation.

The active part 2 can in particular be a wafer. The head 32 is then equipped with a wafer holder, which is typically a square steel body, provided with a device for fixing the interchangeable wafer.

The active part 2 can also be a grain. This is then mounted in a housing pierced at the end of a metal rod and fixed for example by a needle screw.

The active part 2 consists of the same material as the pin 9, namely tungsten carbide or tungsten steel. The active part 2 is identical in shape to the tooth 8 of the pin 9 to be tested. As illustrated in FIG. 4, the test piece 10 has the general shape of a cylinder of revolution about an axis A with two end bases 14a, 14b perpendicular to the axis A of said part 10 and a cylindrical peripheral surface. 1 1.

A plurality of lateral grooves 12 are distributed around the periphery of the test piece 10. These lateral grooves 12 all extend from the same base (base 14a), parallel to the axis A of the piece 10, with a constant depth in the height of the room 10.

The test piece 10 is for example nickel alloy, cast iron, aluminum alloy or titanium alloy.

As illustrated in FIG. 5, during the broaching step, the active part 2 produces in the test piece 10 a front annular groove 13 centered on the axis A of the piece 10 and of a diameter slightly smaller than that the peripheral diameter of said piece 10. The front annular groove 13 is itself cylindrical. It extends from the end base 14a of said part 10, parallel to the axis A.

For this purpose, the test piece 10 is rotated about its axis A, while the turning tool 3 is progressively advanced in the test piece 10, parallel to the axis A to gradually form the groove 13.

The displacement of the turning tool 3 and the rotation of the test piece 10 removes the constituent material of the test piece 10 so as to hollow out the front annular groove 13. During cutting, the material of the piece 10 interference with the path of the turning tool 3 is detached by machining the rest of the workpiece and turns into chips.

A machine tool 15 controls the relative movements between the test piece 10 and the turning tool 3. This machine tool 15 incorporates in particular different actuators ensuring the movements of the workpiece 10 and the turning tool 3, as well as a digital control unit configured to control and synchronize the actuators.

Thus, the removal of material is achieved by the conjunction of two relative movements between the test piece 10 and the turning tool 3: the rotational movement and cutting and the advance movement in depth. The feed rate Vf, which is the speed of movement of the turning tool 3 in the depth of the test piece 10, defines the amount of material removed.

The cutting speed Vc, which is the speed of rotation of the test piece 10 around its main axis A, defines the frequency of the successive cuts.

Such a machining of the test piece 10 makes it possible to simulate the wear of the teeth 8 of a pin 9 by reproducing certain characteristics of the pinning of a cell in a turbomachine disk, by means of a turning tool 3 having an active part 2 identical to the teeth 8 of the spindle 9.

In particular, the surface 14a machined by the active part 2 of the tool turning tool 3 to make the front annular groove 13 in the test piece 10 is a flat surface, which has the consequence that the machining is done at an angle constant clearance during all machining, the draft angle being the angle between the clearance face of the tool (surface of the teeth 8) and the machined surface.

Moreover, the lateral grooves 12 make it possible to simulate the alternation of the machining and repositioning phases characteristic of the machining of cavities. Indeed, the machining of a cell in the form of a fir tree in a turbomachine disk, consists of an alternation of machining phases, during which the pin 9 factory itself, and repositioning phases, during which pin 9 does not factory and only returns to its starting point to prepare the next phase of machining.

In the test method, the phase during which the turning tool 3 is moved in the groove 13 without touching the walls of said groove 13 corresponds to the repositioning phase.

The phase during which the active part 2 machines the groove 13 corresponds to the machining phase.

During the machining of cells, the alternation generates shocks each time the pin 9 comes into contact with the material after a repositioning phase.

During the test procedure, the active part 2 undergoes an identical shock when it comes into contact with the material after passing through a lateral groove 12. For example, if the test piece 10 has ten lateral grooves 12, each turn of the test piece 10 on itself corresponds to ten pin passes 9 in a cell.

As illustrated in FIGS. 7 and 8, the pinning of cells in a trench 51 of a turbomachine disk 4 is often made with a certain angle "ab" of pinning corresponding to the inclination between the axis At of the trench 51 and the main axis Ap of the turbomachine disk 4.

The angle "ab" pinning affects the wear of the pin 9 in that it determines the input of the pin in the coin broaching.

To reproduce the effect of the inclination of the broaching on the wear of the pin 9, the lateral grooves 12 are formed in the test piece 10 with a flank wall, on the side of the groove intended to be attacked by the tooth. , which extends in the test piece 10 parallel to an axis A1 making an angle "a" equal to the angle "ab" of broaching with respect to the radial plane Ar passing through the axis A and the middle of said wall sidewall, as shown in Figure 1 1.

The angle a is non-zero, and typically between 5 ° to 20 °. The inclination of these flanks of the grooves 12 reproduces the progressive entry of the pin 9 into the workpiece.

Moreover, unlike the broaching where the movement of the broaching piece is straight, the movement of the turning tool 3 is circular, which implies a variation of the cutting speed as a function of the machined diameter.

FIG. 12 illustrates the variation of the cutting speeds on three different diameters: the minimum cutting speed Vmin on the inside diameter of the groove 13, the nominal cutting speed Vnom on the mean diameter of the groove 13 and the maximum cutting speed Vmax on the external diameter of the groove 13.

To minimize the speed variation between the outer diameter and the inner diameter, it is ensured that the nominal diameter D _n0 m of the groove is at least 10 times greater than the width of the groove 13, the width of the groove 13 being equal to (Dmax-Dmin) / 2.

For example, for a width of the front annular groove of 3 mm and a nominal diameter D _name of 72mm, the front annular groove has a diameter outer diameter D _max 75 mm and inner diameter D _min 69 mm. The average diameter of the groove is P = 72 π mm. By way of illustration, for a nominal cutting speed V _n0 m = 2 ^m / _mm applied to the machined nominal diameter, the rotational speed of the part is N = ^{1000 xVnom} "8.84

π xD _name ^tr '/ _m ni _i m _n , the cutting speeds V _max and V _min for the diameters D _max and D _min are V _max = ^Nx ^ _o ^D _Q ^max , and V _min = "^ *"" ¹¹ ". In this example, the speed variation Δ _ν = ^{Vmax ~ Vmin} is of the order of 8.3%, which is

"last name

acceptable.

The described wear test method makes it possible to perform a wear test of a tooth 2 quickly and easily.

For example, for a machined length l _u = "30 m, with a depth of the annular groove 1 _T = 20 mm, L _B = 15 mm, and an advance per tooth (corresponding to the chip taking between each round) f = 0.1 mm, the feed rate per revolution is V _f = N xf * 0.884 ^rev / _mm - ^the P ^s ^tem machining is then

1

t _u = - "22 min.

v _f Therefore, in this example, the shooting wear test lasts 22 minutes while a conventional wear test pin lasted 100 hours. The method therefore offers a significant time saving.

Several teeth 2 can be tested simultaneously on the same test piece 10. The various turning tools 3 each carry an active part 2 and each machine a front annular groove 13 in the test piece 10, the front annular grooves 13 being concentric. Several turning tools 3 can also machine a single frontal annular groove simultaneously.

Claims

A method of simulating wear of a tooth (8) of a pin (9), comprising:

a step of machining a test piece (10) by means of a turning tool (3) comprising an active part (2) identical to the tooth (8) of the pin (9) to be tested, during which said test piece (10) and the turning tool (3) are moved in relative movements such that, in a frame linked to the turning tool (3), the test piece is displaced in rotation around an axis (A), while the turning tool (3) is progressively moved in the test piece (10), the active part (2) of the turning tool (3) thus machining a groove frontal ring (13) therein, the method being characterized in that the test piece (10) has a peripheral surface (1 1) in which lateral grooves (12) are provided to simulate the alternation of the phases. machining and repositioning when pinning a slot by the pin to be tested.

Simulation method, according to the preceding claim, wherein the test piece (10) is cylindrical in shape of revolution.

Simulation method, according to one of the preceding claims, in which the lateral grooves (12) are formed in the test piece (10) with a flank wall on the side of the groove to be attacked by the tooth, which extends in the test piece (10) parallel to an axis (A1) forming a non-zero angle (a) with respect to the radial plane passing through the axis (A) of the test piece and the middle of said wall flank.

4. Simulation method according to one of the preceding claims, wherein the pin (9) is of the type intended for the pinout of cells, in particular for rotors disks or turbomachine compressors.

The simulation method according to claim 4, wherein the spindle (9) is of the type intended to machine cells with a predefined pin angle, and wherein the grooves (12) are provided in the test piece (10). ) with a flank wall, on the side of the groove to be attacked by the tooth, which extends in the test piece (10) parallel to an axis (A1) at an angle (a), with respect to the plane radial passing through the axis (A) of the test piece and the middle of said flank wall, equal to the predefined broaching angle.

The simulation method according to one of claims 3 or 5, wherein said angle (a) is between 5 ° and 20 °.

Simulation method, according to one of the preceding claims, the ratio between the width of the annular groove (13) and the diameter of the annular groove (13) being less than 10%.

Simulation method, according to one of the preceding claims, wherein several turning tools (3) each simultaneously machine a front annular groove on the same test piece.

A tooth wear simulation system (8) of a spindle (9), the wear test system comprising:

- A test piece (10) having a peripheral surface (1 1) in which are formed lateral grooves (12) for simulating the alternation of the machining and repositioning phases when pinning a cell by the spindle to test ;

a turning tool (3) comprising an active part (2) identical to the tooth of the spindle (9) to be tested;

a machine tool (15) configured to control the relative movements between the test piece (10) and the turning tool (3), so that the test piece (10) is, in a reference frame linked to the turning tool (3) rotated about an axis (A) while the turning tool (3) is progressively moved in the test piece (10), the active part (2) of the turning tool (3) thus machining a front annular groove (13) in the test piece (10). 10. Simulation system according to the preceding claim, wherein the test piece (10) is cylindrical in shape of revolution.

A simulation system according to one of claims 9 to 10, wherein the test piece (10) has a peripheral surface (11) in which lateral grooves (12) are provided.

12. Simulation system according to one of claims 9 to 11, wherein the test piece (10) is in one of the following materials: nickel base alloy, cast iron, aluminum base alloy, titanium alloy base.