BE1026006B1 - VARIABLE TIMING AUB SYSTEM FOR TURBOMACHINE COMPRESSOR - Google Patents

Abstract

The invention relates to a turbomachine such as an aircraft turbojet, comprising a compressor with a system (34) of adjustable vanes (32) in inclination, or blades with variable timing type "VSV". The booster system includes an outer shell (30) with an annular groove (52). An adjustable blade (32) has an outer journal (38) radially extending through the outer shell, and an outer disk radially disposed in the annular groove. The system further comprises a one-piece seal (70) with a sealing plate (72) disposed in the annular groove of the outer shell (30) and a tube around the journal. The plate having a circular aperture (74) cooperating with the outer disk to form a sealed pivot connection.

Description

VARIABLE TIMING VANE SYSTEM FOR TURBOMACHINE COMPRESSOR

Technical area

The invention relates to the sealing of a system of variable-pitch blades - or adjustable blades - for an axial turbomachine. More specifically, the invention relates to a turbomachine, in particular an aircraft turbojet or an aircraft turboprop. The invention also provides a method of assembling an adjustable vane system.

Prior art

In order to increase the stability zone of a compressor, it is common to equip it with piloted vanes in order to form a system of variable pitch vanes, also known by the acronym "VSV" corresponding to the expression Anglo-Saxon "Variable Stator Vane". Such blades have actuating rods passing through their support casing, which forms a fault therein in terms of sealing.

Document US2010 / 0232936 A1 discloses a turbomachine with a system of variable pitch vanes. An outer ferrule includes an annular groove receiving the outer platforms of the variable pitch vanes. The annular wall of the outer shell has orifices receiving the pins of the blades in order to form pivot connections. Seals are inserted into the holes to guide the blades, and to ensure seals at the pins. However, this seal remains perfectible.

Summary of the invention

Technical problem

The object of the invention is to solve at least one of the problems posed by the prior art. More specifically, the invention aims to improve the sealing of an adjustable vane system. The invention also aims to optimize aerodynamics. The invention also aims to provide

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BE2018 / 5083 a simple, resistant, light, economical, reliable, easy to produce, and convenient maintenance solution.

Technical solution

The subject of the invention is a turbomachine, in particular an aircraft turbojet engine, comprising a compressor with a system of blades adjustable in inclination relative to the axis of rotation of the compressor, said system comprising: an external shroud with an annular groove around the axis of rotation, and an adjustable blade with: a blade, an external journal passing radially through the external ferrule, an external disc disposed radially in the annular groove, remarkable in that the system also comprises a seal with a sealing plate disposed in the annular groove of the outer shell, said sealing plate having a circular aperture cooperating with the outer disc so as to form a sealed pivot connection.

According to advantageous modes of the invention, the turbomachine can comprise one or more of the following characteristics, taken in isolation or according to all the possible technical combinations:

- The annular groove has an internal annular surface oriented radially inwards, and the sealing plate has an external surface radially in contact with the entire internal surface.

- The annular groove has an upstream shoulder and a downstream shoulder which are straight and in contact with the sealing plate in order to ensure sealing.

- Between the blade and the external disc, the adjustable vane has a radius of connection in contact with the circular aperture.

- The seal crosses radially the outer shell, and / or surrounds the outer disc in a sealed manner.

- The outer shell comprises an annular wall and a boss projecting radially relative to the annular wall, the boss comprising an orifice in which the pin is pivotally mounted; the radial thickness (E) of the annular wall being equal to the height

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BE2018 / 5083 radial (H) of the boss, and / or the height (H) representing once to twice the radial thickness (E).

- The outer shell includes an annular wall with an orifice which passes through it and which receives the outer journal of the blade, the seal further comprising a tube mounted in the interface between the journal and the orifice.

- The system includes a sealing sleeve disposed at the interface between the tube and the orifice, the sealing sleeve possibly being free from contact with the adjustable blade.

- The adjustable blade includes a trailing edge and the sealing plate includes an angular clearance axially extending the circular aperture in which the trailing edge is disposed, the trailing edge of the adjustable blade possibly touching the radial bottom and / or a downstream edge of the angular clearance.

- The sealing plate has a downstream end, and an axial separation between the downstream end and the angular clearance.

- The sealing plate includes an upstream edge and a downstream edge axially spaced from the external disc.

- The adjustable blade comprises means for driving in rotation, in particular a control lever, the outer shell being arranged between said drive means and the sealing plate.

- The external disk completely fills the circular hole.

- The adjustable blade is a first blade, the system having an annular row of identical adjustable blades of which the first blade is a part, the circular aperture is a first circular aperture, the sealing plate being in one piece and having a row d '' circular openings each receiving an external adjustable blade disc.

- The annular groove is a first annular groove, the outer shell further comprising a second annular groove with an annular layer of abradable material capable of cooperating by abrasion with the compressor rotor, and an annular rib axially separating the first annular groove from the second annular groove, possibly the sealing plate is flush with the annular layer.

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- The sealing plate is made of a composite material with an organic matrix, and / or the shell is made of metallic material, in particular titanium or aluminum.

The disc is arranged at the interface between the journal and the blade.

- The radial thickness of the external disc is fully integrated into the radial thickness of the plate.

- The sealing plate has an upstream edge and a downstream edge that are substantially straight and in contact with the annular groove in order to ensure sealing, in particular against the upstream shoulder and the downstream shoulder.

- The annular groove forms an area of less radial thickness in the outer shell.

- The annular groove has a constant radial depth along the circumference.

- The plate completely fills the space between the groove and the blade, especially between the groove, the journal and the disc.

- The system has a circular contact between the aperture and the disc, the contact being radial and / or around the disc.

- The tube has a cylindrical passage communicating with the hole and mechanically adjusted to the diameter of the journal.

- The socket surrounds the tube.

- The bosses are spaced from each other according to the circumference.

- The seal, in particular the plate, is in one piece and / or made of one piece.

A subject of the invention is also a method of assembling a system of blades adjustable in inclination for a turbomachine compressor, said system comprising: an external shroud with an annular groove and orifices, and an annular row of blades orientable, each with a blade, an external pin pivotally fixed in one of the orifices, an external disc arranged in the annular groove, remarkable in that the system comprises a seal with tubes and a curved sealing plate having openings, and in that the method comprises the following stages: (a) modification of the curvature of the curved plate; (e) mounting

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BE2018 / 5083 of the curved plate in the annular groove of the shell, the turbomachine being in particular according to the invention.

According to advantageous modes of the invention, the process can include one or more of the following characteristics, taken in isolation or according to all possible technical combinations:

- The method further comprises a step (b) radial insertion of the tubes into the orifices.

- The method further comprises a step (c) insertion of the external pins in the tubes.

- The method further comprises a step (d) insertion of the external discs in circular openings of the plate, preferably at the end of step (d) insertion at least four discs are in contact with the sealing plate.

In general, the advantageous modes of each object of the invention are also applicable to the other objects of the invention. Each object of the invention can be combined with the other objects, and the objects of the invention can also be combined with the embodiments of the description, which in addition can be combined with one another, according to all possible technical combinations, unless the opposite is not explicitly mentioned.

Benefits

The invention optimizes the sealing of the adjustable vane system by acting on different interfaces, while grouping these interfaces on the same block of material - in this case the seal. Furthermore, the seal has upstream and downstream ends which are distant from the blades, and therefore from the orifices. Thus the path that a leak should take is lengthened, thereby improving the seal.

In the radial thickness of the annular wall, the plate directly forms the sealed interface with the blade disc. The presence of the tube prolongs this tightness, which is all the more critical when the available height of the boss decreases in order to make the system compact due to the proximity to a defrosting system and / or a wall of separation spout. .

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The invention facilitates manufacturing because the finest and most complex shapes are made on the joint which can be molded. The cost of the shell decreases. Also, the flexibility of the joint is used to facilitate assembly.

Brief description of the drawings

FIG. 1 represents an axial turbomachine according to the invention.

FIG. 2 is a diagram of a turbomachine compressor according to the invention.

FIG. 3 illustrates a system of adjustable blades according to the invention.

Figure 4 sketches a sealing plate according to the invention.

FIG. 5 is a diagram of the method of assembling the adjustable blade system according to the invention.

Description of the embodiments

In the following description, the terms "internal" and "external" refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are in reference to the main flow direction of the flow in the turbomachine.

Figure 1 shows a simplified axial turbomachine. In this case, it is a double-flow turbojet engine. The turbojet engine 2 comprises a first level of compression, called a low-pressure compressor 4, a second level of compression, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power from the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor blades associated with rows of stator blades. The rotation of the rotor around its axis of rotation 14 thus makes it possible to generate an air flow and to gradually compress the latter until the inlet of the combustion chamber 8.

An inlet fan commonly designated as a fan or blower 16 is coupled to the rotor 12 and generates an air flow which is divided into a primary flow 18 passing through the various above-mentioned levels of the turbomachine, and into a flow

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BE2018 / 5083 secondary 20 passing through an annular duct (partially shown) along the machine and then joining the primary flow at the turbine outlet.

Reduction means 22, such as a planetary reduction gear, can reduce the speed of rotation of the blower and / or of the low pressure compressor relative to the associated turbine. The acceleration of the secondary flow generated a thrust reaction useful in the flight of an aircraft. The primary flow 18 and secondary flow 20 are annular coaxial flows and fitted one into the other.

Figure 2 is a sectional view of a compressor of an axial turbomachine such as that of Figure 1. The compressor can be a low pressure compressor 4, also called a booster. The rotor 12 comprises several rows of rotor blades 24, in this case three. It can be a bladed monobloc drum, and / or comprise dovetail-fixing vanes.

The low-pressure compressor 4 comprises several rectifiers, in this case four, each containing a row of stator vanes 26. The rectifiers are associated with the fan or a row of rotor vanes to straighten the air flow, so as to convert the speed of the flow into pressure, in particular into static pressure.

The stator vanes 26 extend essentially radially from an outer casing 28 forming a support. The external casing 28 can be formed from one or more external ferrules 30. At least one or each external ferrule 28 can be produced from metallic material, in particular from titanium or aluminum.

In order to modify the geometry of the compressor, the stator vanes 26 may include adjustable vanes 32, that is to say which can pivot on themselves, along a radial axis. Consequently, the blade of each adjustable blade 32 can extend more or less through the primary flow 18. The circumferential width of the primary vein occupied by the blade can be adjusted by adapting the orientation of the adjustable blade 32 , ie by modifying the inclination between its mean chord and the axis of rotation 14. Thus, the primary flow 18 is more or less deflected. A separation spout 21 can be fixed to an external ferrule 30, and can separate the primary flow 18 from the secondary flow.

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The adjustable blades 32 can belong to a system 34 which modifies the geometry of the compressor 4 so as to increase its stability.

The compressor 4 can be mixed, in the sense that it can also include one or more rows of stator vanes with fixed orientation 36, or single orientation 5, relative to the axis of rotation 14.

The adjustable vanes 32 can be fixed and articulated by means of external journals 38 passing through the external casing 28, and therefore the external ferrule 30. The external journals 38 are mounted to rotate relative to the external ferrule 30 in order to form rotary bearings .

In order to transmit a coherent control movement to the orientable blades 32, control levers 40 are connected to a synchronization ring 42 and to the pins 38. The synchronization rings 42 surround the external casing 28.

The internal ends of the stator vanes 26 can be rotatably connected to suitable internal ferrules thanks to their internal journals (not shown).

FIG. 3 shows a system 34 of adjustable blades, in particular such as that presented in FIG. 2.

The outer shell 30 may have an annular wall 46 which may have a fixing flange 48 at one end. The lever 40 can be parallel to the wall 46. A boss 50 can extend radially from the external surface of the annular wall 46. The radial thickness E of the annular wall 46 can be equal to the radial height H of the boss 50 By equal, it can be understood that the radial height H of the boss 50 represents at most 125%, preferably

110%, more preferably 105% of the radial thickness E of the annular wall 46.

This configuration tends to reduce the radial height of the boss 50, and adds a constraint on the seal between the blade 32 and the ferrule 30.

The outer shell 32 has an annular groove 52 facing the axis of rotation 14. The annular groove 52 can be formed in the radial thickness E of the annular wall 46. It can be continuous all around the axis, and in particular have a constant axial width. It may have an annular surface 54 forming its bottom and connecting its upstream shoulder 56 to

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BE2018 / 5083 its downstream shoulder 58. These shoulders (56; 58) may be straight. They can each describe a circle around the axis 14, in particular according to straight planes and perpendicular to the axis 14.

The outer shell 32 may include an orifice 60 passing through the ferrule 30, and in particular the wall 46. The orifice 60 may communicate towards the outside. It can extend radially from the groove 52. It can extend partly in the wall 46, and pass through the boss 50.

The adjustable blade 32 has a blade 62 extending in the annular flow of the compressor. The blade 62 can have a leading edge 64 and a trailing edge 66. Its lower surface and its upper surface can link the leading edge 64 to the trailing edge 66.

The adjustable blade 32 includes an external disc 68, also called a button, which separates the blade 62 from the external journal 38. The disc 68 has an outline describing a circle. It can be flat. Its radial thickness is completely integrated into the thickness of the wall 46 and / or into the depth of the groove 52.

The system 34 includes a seal 70, in particular a one-piece. The seal 70 can be made of polymer, for example with an organic matrix composite material.

The seal 70 comprises a sealing plate 72 which radially fills the annular groove 52. The radial thickness of the sealing plate 72 can be equal to the radial depth of the groove 52. Thus the wall 46, the disc 68 and plate 72 are flush, and in particular form a smooth surface for the primary flow.

The seal 70 comprises a circular aperture 74 of a shape complementary to that of the disc 68. The materials and the correspondence of the shapes make it possible to produce a sealed bearing, that is to say a sealed pivot mechanical connection. In particular, the periphery of the opening 74 can be in circular contact with the contour of the disc 68. The pivot can have three sealed circular interfaces of different shapes: two tubular interfaces and a disc-shaped interface joining these previous ones.

The seal 70 can comprise a tube 76. The tube 76 can extend radially from the plate 72. It can be adjusted in a sealed manner to the

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BE2018 / 5083 diameter of the pin 38, which contributes to sealing and guiding the blade in rotation.

The plate 72 can be pressed radially against the internal surface 54 of the groove 52. Its external surface 78 can be in contact with all or substantially all of the internal surface 54. The upstream edge 80 and the downstream edge 82 of the plate 72, respectively forming its upstream end and its downstream end, and can be in axial contact with the shoulders (56; 58) so as to provide upstream and downstream seals. This strengthens the tightness of the system 34.

At the radial junction of the blade 62 and the disc 68, the adjustable vane 32 may include a connection radius 84 in contact with the aperture 74. The circular aperture 74 may include a surface 86 forming a portion of a torus, by example at the edge of the angular clearance 90 as presented below. The connecting radius 84 can be in contact and / or follow said surface 86. This surface 86 can mark an increase in radius of the edge which surrounds the opening 74.

The system 34 may comprise a sealing sleeve 88 disposed in the orifice 60. The sleeve 88 can be adjusted in leaktight manner to the tube 76 and / or to the orifice 60. The sleeve 88 can be physically separated from the pin 38 by tube 76. It blocks, stiffens and seals the system.

The circular aperture 74 may have an angular clearance 90 downstream. The latter can receive the trailing edge 66 and offer it a track for the pivoting of the blade 32. The trailing edge 66 can be flush with the angular clearance 90, in particular its radial bottom which may be plane. This proximity reduces leaks while allowing blade 32 to operate.

The wall 46 may have a second annular groove 92 downstream of the adjustable vane 32, and may be filled with a layer of abradable material 94 cooperating sealingly with the rotor of the compressor. The wall 46 may have an annular rib 96 axially separating the grooves (52; 92), and / or in axial contact with the plate 72 and the abradable layer 94. The latter two can be flush with the rib 96.

Although only one adjustable blade 32 is shown, the present teaching can apply to its entire annular row of identical blades 32, and in particular to all the entities of the system 34. In particular, the

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BE2018 / 5083 compressor can have annular rows of 50 identical bosses, 60 identical holes, 68 identical discs, 74 identical openings, 76 identical tubes, 88 identical sockets. The seal 70, like the plate 72 may be common to several blades 32, for example at least four. Optionally, they can each form a one-piece loop around the axis 14.

FIG. 4 represents a seal 70. The seal 70 may correspond to that presented in FIG. 3. It is here seen in plan, radially from the inside. The axis of rotation 14 is present.

By way of example only, two adjustable blades 32 are associated with the same plate 72.

Each adjustable blade 32, in particular its outer end, is in the grip of the circular aperture 74. The leading edges 64 remain and pivot in the aperture. The trailing edges 66 are cantilevered downstream, and can oscillate in the angular clearances 90, and for example flush with the downstream edges 98. The toric surfaces 86 touch the clearances 90.

The downstream edge 82 of the plate 72 can be separated from the aperture 74, in particular from the recess 90, by an axial separation 44. This axial separation 44 can form a strip reflecting the fact that the profile of the blade 32 is completely contained in plate 72.

FIG. 5 is a diagram of the method for assembling a system of adjustable turbomachine blades. The system like the turbomachine can be in accordance with those presented in relation to one of, or Figures 1 to 4.

The process can include the following stages, in particular carried out in the following order:

(a) modification 100 of the curvature of the curved plate by bending it further so as to present the external ends of the tubes facing the inlets;

(b) radial insertion 102 of the tubes into the orifices from the inside;

(c) insertion 104 of the external pins into the tubes from the inside;

(d) insertion 106 of the external disks, for example of at least four disks, into circular openings in the plate;

(e) fitting 108 of the curved plate into the annular groove of the ferrule;

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BE2018 / 5083 (f) fitting 110 of the sockets around the joint tubes, and in the orifices of the outer shell.

Later, the levers can be mounted on the trunnions, then be fixed to the synchronization ring. Step (d) insertion 106 of the external discs can be carried out without contact between the blade and the ferrule.

Claims (20)

claims 1. Turbomachine (2), in particular an aircraft turbojet, comprising a compressor (4; 6) with a system (34) of adjustable vanes (32) in inclination relative to the axis of rotation (14) of the compressor (4; 6), said system (34) comprising: - an outer ferrule (30) with an annular groove (52) around the axis of rotation (14), and - an adjustable blade (32) with: o a blade (62), o an external journal (38) passing radially through the external ferrule (30), o an external disc (68) disposed radially in the annular groove (52), characterized in that the system (34) comprises in addition to a seal (70) with a seal plate (72) disposed in the annular groove (52) of the outer shell (30), said seal plate (72) having a cooperating circular aperture (74) with the external disc (68) so as to form a sealed pivot connection. 2. Turbomachine (2) according to claim 1, characterized in that the annular groove (52) has an internal annular surface (54) oriented radially inwards, and the sealing plate (72) has an external surface ( 78) radially in contact with the entire internal surface (54). 3. Turbomachine (2) according to one of claims 1 to 2, characterized in that the annular groove (52) has an upstream shoulder (56) and a downstream shoulder (58) straight and in contact with the sealing plate (72) to ensure watertightness. 4. Turbomachine (2) according to one of claims 1 to 3, characterized in that between the blade (62) and the external disc (68), the adjustable blade (32) comprises in connection radius (84) in contact with the circular aperture (74). 2018/5083 BE2018 / 5083 5. Turbomachine (2) according to one of claims 1 to 4, characterized in that the seal (70) passes radially through the outer shell (30), and surrounds the outer disc (68) in a sealed manner. 6. Turbomachine (2) according to one of claims 1 to 5, characterized in that the outer shell (30) comprises an annular wall (46) and a boss (50) projecting radially relative to the annular wall (46 ), the boss comprising an orifice (60) in which the pin (38) is pivotally mounted; the radial thickness (E) of the annular wall (46) being equal to the radial height (H) of the boss (50), and / or the height (H) representing from once to twice the radial thickness (E ). 7. Turbomachine (2) according to one of claims 1 to 6, characterized in that the outer shell (30) comprises an annular wall (46), and an orifice (60) passing through it and receiving the outer journal (38) adjustable blade (32), the seal (70) further comprising a tube (76) mounted in the interface between the pin (38) and the orifice (60). 8. Turbomachine (2) according to claim 7, characterized in that the system (34) comprises a sealing sleeve (88) disposed at the interface between the tube (76) and the orifice (60), the sleeve seal (88) being free from contact with the adjustable blade (32). 9. Turbomachine (2) according to one of claims 1 to 8, characterized in that the adjustable blade (32) comprises a trailing edge (66) and the sealing plate (72) comprises an angular clearance (90 ) extending the circular aperture (74) axially, and in which the trailing edge (66) is arranged, the trailing edge (66) of the adjustable blade (32) touching the radial bottom and / or a downstream edge ( 98) of the angular clearance (90). 10. Turbomachine (2) according to claim 9, characterized in that the sealing plate (72) has a downstream end, and an axial separation (44) between the downstream end and the angular clearance (90). 2018/5083 BE2018 / 5083 11. Turbomachine (2) according to one of claims 1 to 10, characterized in that the sealing plate (72) comprises an upstream edge (80) and a downstream edge (82) axially spaced from the external disc (68 ). 12. Turbomachine (2) according to one of claims 1 to 11, characterized in 5 that the adjustable blade (32) comprises rotation drive means, in particular a control lever (40), the external ferrule (30) being disposed between said drive means and the sealing plate (72) . 13. Turbomachine (2) according to one of claims 1 to 12, characterized in that 10 that the external disk (68) completely fills the circular aperture (74). 14. Turbomachine (2) according to one of claims 1 to 13, characterized in that the adjustable blade (32) is a first blade, the system (34) having an annular row of identical adjustable blades of which the first dawn, the circular aperture (74) is a first circular aperture, the 15 sealing plate (72) being in one piece and having a row of circular openings each receiving an external disk (68) of adjustable blade (32). 15. Turbomachine (2) according to one of claims 1 to 14, characterized in that the annular groove (52) is a first annular groove, the outer shell (30) further comprising a second annular groove (92) with An annular layer (94) of abradable material capable of cooperating by abrasion with the rotor (12) of the compressor, and an annular rib (96) axially separating the first annular groove from the second annular groove (92), the plate sealing (72) is flush with the annular layer (94). 25 16. Turbomachine (2) according to one of claims 1 to 15, characterized in that the sealing plate (72) is made of a composite material with an organic matrix, and the ferrule (30) is made of metallic material, especially titanium or aluminum. 2018/5083 BE2018 / 5083 17. A method of assembling a system (34) of blades adjustable (32) in inclination for a compressor (4; 6) of a turbomachine (2), said system (34) comprising: an external shroud (30) with a annular groove (52) and orifices (60), and an annular row of adjustable vanes (32), each with a blade (62), an external journal (38) pivotally fixed in one of the orifices (60), an external disc (68) disposed in the annular groove (52), characterized in that the system (34) comprises a seal (70) with tubes (76) and a curved sealing plate (72) having openings (74), and in that the method comprises the following steps: (a) modification (100) of the curvature of the curved plate (72); (e) mounting (108) of the curved plate (72) in the annular groove (52) of the ferrule (30); the turbomachine (2) being in particular according to one of claims 1 to 16. 18. The method of claim 17, characterized in that it further comprises a step (b) radial insertion (102) of the tubes in the orifices. 19. Method according to one of claims 17 to 18, characterized in that it further comprises a step (c) insertion (104) of the external pins (38) in the tubes (76). 20. Method according to one of claims 17 to 19, characterized in that it further comprises a step (d) insertion (106) of the external discs (68) in openings (74) of the plate (72), preferably at the end of step (d) insertion (106) at least four discs (68) are in contact with the plate.