TEMPLATE AND METHOD FOR CONTROLLING THE PITCH BETWEEN TWO CELLS OF A ROTOR DISC

Abstract

Jig (20) for checking the pitch (P1) between two cells (12) of a rotor disk (11), in particular of an aircraft turbomachine (1), this jig comprising: - a first body (22) having a predetermined general shape to be able to be engaged in a first cell (12) of the disk (11) along a first axis (X1), - a second body (24) identical to the first body (22) to be able to be engaged in a second cell (12) of the disk (11) along a second axis (X2), and - a bridge (26) connecting the first and second bodies (22, 24) and forming with these first and second bodies (22, 24) a single-piece assembly. Figure for the abstract: Figure 4

Description

Title of the invention: TEMPLATE AND METHOD FOR CONTROLLING THE PITCH BETWEEN TWO CELLS OF A ROTOR DISC Technical field of the invention

[0001] The present invention relates in particular to a template and a method for controlling the pitch between two cells of a rotor disk, in particular of an aircraft turbomachine. Technical approval plan

[0002] A double-flow turbojet engine 1 such as that of [Fig.l], comprises an inlet sleeve 2 into which the air is admitted before being sucked in by the blades of a fan 3.

[0003] After passing the blower region, the air splits into a central primary flow and a secondary flow that surrounds the primary flow.

[0004] The primary air flow then passes through a first compressor 4 located immediately after the blower 3 while the secondary flow is propelled backwards to directly generate additional thrust by being blown around the primary flow.

[0005] The primary flow then passes through a second compression stage 6, before reaching a chamber 7 where its combustion takes place, after injection and vaporization of a fuel.

[0006] After combustion, this primary flow expands in a high pressure turbine 8 then in a low pressure turbine 9 to drive the compression stages and the fan in rotation, before being expelled towards the rear of the engine to generate thrust.

[0007] Each turbine comprises a succession of stages each comprising a series of blades oriented radially and regularly spaced around a rotation shaft of the engine. This shaft which extends along a longitudinal axis AX carries the rotating elements of the turbine as well as the rotating elements of the compressor and the fan.

[0008] The blades of the fan and of each turbine are carried by a rotor disc 11, such as that illustrated in [Fig.2]. This rotor disc 11 comprises at its periphery a series of cells 12 regularly distributed around the axis AX and which extend parallel to each other in the direction of the axis of rotation or forming a certain angle with this axis. Each cell 12 is produced by broaching the disc 11 in general and is intended to receive the root of a blade by male-female fitting.

[0009] Each cell 12 is a groove whose cross-sectional shape is similar to a dovetail or fir tree outline with rounded tops. Each cell 12 delimits over its entire length a rectangular opening opening radially towards the outside of the disc, and it ends in the front and rear faces of this disc where it opens in the form of dovetail or fir-shaped openings with rounded tops.

[0010] The assembly of a blade consists of engaging the root of this blade in the cell 12 by a face of the disc 11 in which it opens by moving this root in the cell to engage it there.

[0011] The outline of each cell 12 seen in cross-section, that is to say in a plane normal to its generatrices, is very rounded instead of having acute angles as in the case of a dovetail shape.

[0012] As with all engine parts, the various characteristics of these discs are checked. This check consists in particular of measuring the shape of the cell contour in a transverse plane to determine whether or not it conforms to predetermined geometric criteria.

[0013] In the event of a geometric shape defect that is too significant compared to reference values, the disc must be replaced.

[0014] In the prior art, the evaluation of the geometry of the cell can be carried out with metrological equipment comprising a mechanical probe with a touch, this equipment being relatively heavy and tedious to handle. This probe has a specific elongated shape which allows it to be engaged inside the cell, but which is in fact liable to flex, which also tends to distort the measurements in certain configurations.

[0015] The applicant has already proposed an alternative in document FR-A1-3 032 270, which consists of using a measuring tool with optical sensors.

[0016] There are other techniques for controlling the geometry of the disc cells which consist of using one or more templates. A template is a counterform which is intended to be engaged in a cell of a disc. The template has a shape complementary to that of a cell and the geometry of a cell is validated when the template is engaged without play in the cell, and is considered non-compliant when the insertion of the template in the cell is not possible or when play appears between the template and the cell after insertion of the template in the cell.

[0017] Depending on the shape and dimensions of the template, one or more geometric parameters of the cell can be controlled.

[0018] The disadvantage of current techniques is that they are focused on individual cell control and do not take into account the relative positions between cells. A cell may be dimensionally correct but may be poorly positioned relative to adjacent cells.

[0019] There is therefore a need to identify a solution for controlling the relative positions of the cells and in particular the pitch between the cells.

[0020] The invention provides a solution to this problem which is simple, effective and economical. Summary of the invention

[0021] The invention relates to a template for checking the pitch between two cells of a rotor disk, in particular of an aircraft turbomachine, this template comprising:

[0022] - a first body having a predetermined general shape to be capable of being engaged in a first alveolus of the disc along a first axis, this first body having a first median plane passing through the first axis and through a virtual axis intended to correspond to the axis of revolution of the disc,

[0023] - a second body identical to the first body to be able to be engaged in a second alveolus of the disc along a second axis, the second alveolus being adjacent to the first alveolus, this second body having a second median plane passing through the second axis and through said virtual axis, and

[0024] - a bridge connecting the first and second bodies and forming with these first and second body a single-piece assembly,

[0025] the first and second median planes forming a first angle in a plane perpendicular to the virtual axis, which corresponds to a control step.

[0026] First of all, the template forms a single-piece assembly and is therefore easy to handle and relatively inexpensive to manufacture. This template does not simply have a single cell counterform as in the prior art, but comprises two counterforms which are intended to cooperate by engagement with two adjacent cells of a rotor disk in order in particular to control the pitch between these cells. These counterforms are formed by the bodies of the template, which are identical. The connecting bridge of the bodies allows them to be secured to each other and facilitates the handling of the template.

[0027] The control pitch corresponds to the pitch between the bodies and more particularly to the angle between the first and second median planes of the bodies. This angle is measured in a plane perpendicular to the virtual axis, that is to say to the axis of revolution of the disc when the template is mounted on the disc.

[0028] The template according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another: • the first and second bodies have a dovetail or fir tree shape; • the first and second median planes are planes of symmetry respectively of the first and second bodies; • the first and second median planes form a second angle in a plane tangent to a circumference centered on the virtual axis, which corresponds to a convergence control angle; in the present application, a distinction is made between convergence and relative convergence. The convergence of a cell is the angle formed by the median plane of this cell or of the body intended to be engaged in this cell, with a plane perpendicular to the aforementioned virtual or revolution axis. The relative convergence between two adjacent cells is the angle formed between the median planes of these two cells, which corresponds to the angle formed between the median planes of the two bodies of the template. This angle, called the relative convergence angle, is measured in a plane tangent to a circumference centered on the aforementioned virtual or revolution axis; • for each of the bodies a control axis is defined which forms an angle with another axis parallel to the virtual or revolution axis and passing through the median plane of this body, which corresponds to a control angle of the perpendicularity of the body, this angle being measured in said median plane; • the first body comprises a free end opposite the bridge which forms a first bulb, this first bulb comprising a peripheral contour having two first perpendicularity control points, forming a first perpendicularity control angle with a virtual axis parallel to the axis of revolution of the disc and belonging to the median plane of the alveolus; • the second body comprises a free end opposite the bridge which forms a second bulb, this second bulb comprising a peripheral contour having two second perpendicularity control points forming a second perpendicularity control angle with a second virtual axis parallel to the axis of revolution of the disc and belonging to the median plane of the alveolus;

[0029] in the present application, a distinction is made between perpendicularity and relative perpendicularity. The perpendicularity of a cell is the angle formed by the axis obtained by measuring the two perpendicularity control points of the cell and the virtual axis parallel to the axis of revolution of the disc and belonging to the median plane of the cell. The relative perpendicularity between two adjacent cells is the angle formed between the two virtual axes formed by the two perpendicularity control points of each of the cells, which corresponds more particularly to the difference between the two angles formed from the axes of the two bodies of the template. This angle, called the perpendicularity control angle, is measured on the median plane of each cell; • the bridge is connected to or includes a gripping element such as a loop or a hook; • the bridge has a general parallelepiped shape, possibly curved, and comprises a first surface for connection to the first and second bodies, and a second surface opposite the first surface and connected to the gripping element; • it is made of metal, for example hardened steel.

[0030] The present invention also relates to a control kt comprising two templates as described above, the first template comprising first and second bodies having transverse dimensions a few microns smaller than those of the first and second bodies of the second template.

[0031] The present invention also relates to an assembly comprising a template or one as described above, and a rotor disk, in particular of an aircraft turbomachine, this rotor disk having an axis of revolution and comprising at its periphery cells configured to receive rotor blade roots.

[0032] The present invention finally relates to a method for controlling at least the pitch between two cells of a rotor disk, in particular of an aircraft turbomachine, by means as described above, comprising a step of moving the template towards the rotor disk with a view to inserting the first and second bodies into two adjacent cells of the disk, the pitch between these cells being considered as compliant if the first and second bodies engage in the cells and being considered as non-compliant if the first and second bodies do not engage completely in the cells.

[0033] The method according to the invention may comprise one or more of the following characteristics or steps, taken in isolation from one another, or in combination with one another:

[0034] — the method can be carried out directly at the output of the broaching operation or after three-dimensional metrological measurement control, during a dimensional inspection for example; • the step is repeated for each pair of adjacent cells around the entire periphery of the rotor disc; • the first template (with the smallest dimensions) is moved towards the rotor disc with a view to inserting its first and second bodies into two adjacent cells of the disc, the pitch between these cells being considered compliant if the first and second bodies engage without play in the cells; • the second template (with larger dimensions) is moved towards the rotor disc for the purpose of inserting its first and second bodies into two adjacent cells of the disc, the pitch between these cells being considered as compliant if the first and second bodies do not engage in the cells and as non-compliant if these bodies engage in these cells. Brief description of the figures

[0035] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0036] [Fig-1] [Fig.l] is a schematic axial sectional view of a turbomachine aircraft;

[0037] [Fig.2] [Fig.2] is a schematic perspective view of a rotor disk of the turbomachine of [Fig.l]

[0038] [Fig.3] [Fig.3] is a schematic perspective view of a rotor disk, partially shown, and illustrates a step of a control method according to the invention;

[0039] [Fig.4] [Fig.4] is a schematic perspective view of a control template according to the invention; and

[0040] [Fig.5] [Fig.5] is a schematic perspective view of a control kit according to the invention. Detailed description of the invention

[0041] Figures 1 and 2 have been described in the above.

[0042] [Fig. 3] schematically and partially illustrates a rotor disk 11 for an aircraft turbomachine such as that of [Fig. 1].

[0043] The rotor disk 11 has an axis AX, called the axis of revolution, and comprises at its periphery a series of cells 12 of which only three are shown in the figure.

[0044] These cells 12 extend over the entire thickness or axial dimension of the disc 11 and open radially outwards relative to the axis AX.

[0045] The cells 12 are fir-tree shaped in the example shown but could have another shape such as a dovetail shape, these shapes being well known to those skilled in the art.

[0046] The geometric parameters of the cells 12 must be precisely controlled after manufacturing the disc 11. The cells 12 are generally produced by broaching and this operation can in fact generate dimensional and positional deviations from the specifications.

[0047] Among the geometric parameters that can be controlled are the pitch between the cells, the perpendicularity of each cell and the perpendicularity between two adjacent cells, the convergence of a cell and the relative convergence between two cells, and the transverse dimensions of each cell.

[0048] The median plane H1 of a cell 12 is the plane which passes through the middle of the cell and through the axis AX. This plane H1 is parallel to the axis AX and can be a plane of symmetry of the cell.

[0049] The pitch between two adjacent cells is noted PI in [Fig.3] and corresponds to the angle yl which is formed between the median planes H1 of these cells and which is measured in a plane perpendicular to the axis AX.

[0050] The convergence of a cell 12 is noted Cl in [Fig.3] and corresponds to the angle al formed between the median plane H1 of this cell and a plane perpendicular to the axis AX, this angle al being measured in a plane tangent to a circumference centered on the axis AX. The plane perpendicular to the axis AX can pass through one of the faces of the disc 11.

[0051] The relative convergence between two adjacent cells is noted DI in [Fig.3] and corresponds to the angle al' formed between the median planes H1 of these cells and which is measured in a plane tangent to a circumference centered on the axis AX.

[0052] With regard to the perpendicularity of a cell 12, control points are defined, for example two per cell. The control points are located in the cell 12 and located on a virtual axis AB.

[0053] The perpendicularity of a cell is noted RI in [Fig.3] and corresponds to the angle [31 formed between the virtual axis AB of this cell and another virtual axis GH parallel to the axis AX and belonging to the median plane H1 of the cell Hl, this angle being measured in the median plane HL

[0054] The relative perpendicularity between two adjacent cells is noted SI in [Fig.3] and corresponds to the angle bl ' calculated by taking the difference between the two angles of perpendicularity bl and b2 of two cells, each measured in the median plane of each of the two cells.

[0055] The present invention makes it possible to control one or more of these geometric parameters, and in particular the PL pitch.

[0056] [Fig.4] illustrates an embodiment of a control template 20 according to the invention.

[0057] The template 20 essentially comprises three parts, namely two bodies 22, 24 and a bridge 26 which connects the bodies 22, 24 together.

[0058] The first body 22 has a predetermined general shape, for example dovetail as in the example shown or fir tree, to be able to be engaged in a first cell 12 of the disk 11 to be checked, along a first axis XL. This first axis XI corresponds here to an axis of elongation of the first body 22. This first axis XI generally corresponds to a broaching axis of the cell 12 to be checked.

[0059] The first body 22 has a first median plane U1 which passes through the first axis XI and through a virtual axis AX' intended to correspond to the axis of revolution AX of the disc 11. This median plane U1 is preferably a plane of symmetry of the body 22.

[0060] The second body 24 is identical to the first body 22 to be able to be engaged in a second cell 12 of the disc along a second axis X2.

[0061] As for the first axis XI, this second axis X2 here corresponds to an axis of elongation of the second body 24. This second axis X2 generally corresponds to a broaching axis of the cell to be controlled.

[0062] The second body 24 has a second median plane U2 which passes through the second axis X2 and through the virtual axis AX'. This median plane U2 is preferably a plane of symmetry of the body 22.

[0063] The bodies 22, 24 are located next to each other to the extent that they are intended to be engaged in adjacent cells 12 of the disc 11.

[0064] The connecting bridge 26 forms a single-piece assembly with the bodies 22, 24. The template 20 can thus be formed from a single piece. It is for example made of metal, and preferably of hardened steel.

[0065] Advantageously, the bridge 26 is connected to or comprises a gripping element 28 such as a loop or a hook.

[0066] The bridge 26 may have a general parallelepiped shape, possibly curved, and comprise a first surface 26a for connection to the first and second bodies 22, 24, and a second surface 26b opposite the first surface 26a and connected to the gripping element 28.

[0067] The pitch between the bodies 22, 24 is noted P2 in [Fig.4] and corresponds to the angle y2 which is formed between the median planes Ul, U2 and which is measured in a plane perpendicular to the virtual axis AX'.

[0068] The convergence of a body 22, 24 is noted C2 in [Fig.4] and corresponds to the angle a2 formed between the median plane Ul of this cell and a plane perpendicular to the virtual axis AX', this angle a2 being measured in a plane tangent to a circumference centered on the virtual axis AX'.

[0069] The relative convergence between the bodies 22, 24 is noted D2 in [Fig.4] and corresponds to the angle a2' formed between the median planes Ul, U2 and which is measured in a plane tangent to a circumference centered on the virtual axis AX'.

[0070] With regard to the perpendicularity of a body 22, 24, control points are defined as previously, for example two per body. The control points are located in the body and located on a virtual axis AB'.

[0071] The perpendicularity of a body is noted R2 in [Fig.4] and corresponds to the angle [32 formed between the virtual axis AB' and a virtual axis GH' parallel to the axis AX' and belonging to the median plane of this body, this angle being measured in this median plane.

[0072] The relative perpendicularity between the bodies 22, 24 is noted S2 in [Fig.4] and corresponds to the angle b2' calculated by taking the difference between the angles [32 of perpendicularity of the two bodies (therefore the angle calculated between the axes AB' of the two bodies measured in one of the median planes of one of the two bodies.

[0073] The pitch P2 is a control pitch. It is thus understood that, during a method of controlling the pitch between two cells 12 of a rotor disk 11, the template 20 is moved towards the rotor disk 11, as illustrated by the arrows F in [Fig. 3], with a view to inserting the first and second bodies 22, 24 of the template 20 into two adjacent cells 12 of the disk 11.

[0074] The pitch PI between these cells 12 is considered to be compliant if the first and second bodies 22, 24 engage in the cells 12, and is considered to be non-compliant if the bodies 22, 24 do not completely engage in the cells 12. In other words, in a preferred embodiment, PI must be equal to P2 for the pitch between the cells to be considered to be compliant.

[0075] After checking the pitch between the cells 12 of a first pair of adjacent cells, the pitch of all the other pairs of adjacent cells of the disc 11 is checked.

[0076] Other geometric parameters of the cells 12 can be controlled by the template 20 according to the invention. This is the case for the parameters mentioned above, namely in particular the relative convergence D1, the relative perpendicularity SI and the dimensions of each of the cells 12.

[0077] It is understood that if the template 20 engages in the cells 12 to be checked, this means that the relative convergence SI and the relative perpendicularity Dl of these cells 12 are within an authorized tolerance range. It is also understood that the transverse dimensions of the cells are not greater than authorized thresholds.

[0078] It is also understood that if the template 20 does not engage in the cells to be checked, this means that at least one of the following parameters may not be compliant: the relative convergence SI, the relative perpendicularity Dl and transverse dimensions of the cells 12.

[0079] [Fig.5] illustrates a control kit according to the invention, this kit comprising two templates 20, 20' as described above.

[0080] The first template 20 comprises first and second bodies 22, 24 having transverse dimensions el, e2, ..., en, a few microns smaller than those el', e2', ..., en' of the first and second bodies 22, 24 of the second template 20'.

[0081] When checking two adjacent cells 12 of a disk 11, the first template 20 is moved towards the rotor disk 11 with a view to inserting its bodies 22, 24 into the cells 12. The pitch PI between these cells 12 is considered to be correct if the bodies 22, 24 engage without play in the cells 12.

[0082] If the pitch PI is considered non-compliant, the process can be stopped. If it is compliant, the process can be continued by moving the second template 20' towards the rotor disk with a view to inserting its bodies 22, 24 into the cells 12. The pitch PI between the cells is considered to be compliant if the bodies do not engage in the cells 12 and as non-compliant if these bodies engage in these cells.

[0083] The first template 20, if it fits into the two cells 12, can thus make it possible to ensure that the pitch PI between the cells is greater than the minimum authorized by a specification. The second template 20' can make it possible to check whether the pitch PI is not greater than the maximum authorized by this specification. It can thus be verified that the pitch PI is within a predetermined tolerance interval.

[0084] The advantage of the invention is that it allows two cells to be controlled at the same time. The template makes it possible to control the relative position of one cell in relation to another, and in particular the pitch between the cells, or even other geometric parameters such as the relative convergence and the relative perpendicularity between the cells, the transverse dimensions of each of the cells, etc.

Claims

Claims

1. Control kit for controlling the pitch (PI) between two cells (12) of a rotor disk (11), in particular of an aircraft turbomachine (1), this control kit comprising two templates (20, 20') each comprising: - a first body (22) having a predetermined general shape to be able to be engaged in a first cell (12) of the disk (11) along a first axis (XI), this first body (22) having a first median plane (Ul) passing through the first axis (XI) and through a virtual axis (AX') intended to correspond to the axis (AX) of revolution of the disk (11), - a second body (24) identical to the first body (22) to be able to be engaged in a second cell (12) of the disk (11) along a second axis (X2), the second cell (12) being adjacent to the first cell (11), this second body (24) having a second median plane (U2) passing through the second axis (X2) and through said virtual axis (AX'),and - a bridge (26) connecting the first and second bodies (22, 24) and forming with these first and second bodies (22, 24) a single-piece assembly, the first and second median planes (U1, U2) forming a first angle (y2) in a plane perpendicular to the virtual axis (AX'), which corresponds to a control pitch (P2), the first template (20) comprising first and second bodies (22, 24) having transverse dimensions a few microns smaller than those of the first and second bodies (22, 24) of the second template (20').,

2. A control kit according to claim 1, wherein the first and second bodies (22, 24) have a dovetail or fir tree shape.

3. Control kit according to claim 1 or 2, wherein the first and second median planes (U1, U2) are planes of symmetry respectively of the first and second bodies (22, 24).

4. Control kit according to one of the preceding claims, in which the first and second median planes (U1, U2) form a second angle (a2') in a plane tangent to a circumference centered on the virtual axis (AX'), which corresponds to a relative convergence control angle (D2).

5. Control kit according to one of the preceding claims, in which a control axis (AB') is defined for each of the bodies (22, 24) which forms an angle (b2') with another axis (GH') parallel to the virtual axis (AX') and passing through the median plane (Ul, U2) of this body, which corresponds to a control angle of the perpendicularity of the body, this angle being measured in said median plane (Ul, U2).

6. A control kit according to any preceding claim, wherein the bridge (26) is connected to or comprises a gripping element (28) such as a loop or hook.

7. Control kit according to the preceding claim, in which the bridge (26) has a generally parallelepiped shape which may be curved, and comprises a first surface (26a) for connection to the first and second bodies (22, 24), and a second surface (26b) opposite the first surface and connected to the gripping element (28).

8. Control kit according to one of the preceding claims, in which it is made of metal, and for example of hardened steel.

9. Assembly comprising a control kit according to one of claims 1 to 8, and a rotor disc (11), in particular of an aircraft turbomachine (1), this rotor disc (11) having an axis of revolution (AX) and comprising at its periphery cells (12) configured to receive rotor blade roots.

10. Method for controlling at least the pitch (PI) between two cells (12) of a rotor disk (11), in particular of an aircraft turbomachine (1), by means of an assembly according to claim 9, comprising a step of moving the template (20) towards the rotor disk (11) with a view to inserting the first and second bodies (22, 24) into two adjacent cells (12) of the disk (11), the pitch (PI) between these cells (12) being considered as compliant if the first and second bodies (22, 24) engage in the cells (12) and being considered as non-compliant if the first and second bodies (22, 24) do not engage completely in the cells (12).

11. A method according to claim 10, wherein the step is repeated for each pair of adjacent cells (12) around the entire periphery of the rotor disc (11).

12. A method according to claim 11, wherein the first jig (20) is moved towards the rotor disc (11) for insertion of its first and second bodies (22, 24) into two adjacent cells (12). of the disc, the pitch (PI) between these cells (12) being considered compliant if the first and second bodies (22, 24) engage without play in the cells (12).

13. A method according to claim 12, wherein the second template (20') is moved towards the rotor disc (11) for insertion of its first and second bodies (22, 24) into two adjacent sockets (12) of the disc (11), the pitch (PI) between these sockets (22, 24) being considered as conforming if the first and second bodies (22, 24) do not engage in the sockets (12) and as non-conforming if these bodies (22, 24) engage in these sockets (12).

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