FR3094080A1 - Method and device for controlling a protective sheet in a turbomachine - Google Patents

Abstract

The present invention relates to a method for checking at least one zone of a bearing support, characterized in that it comprises the steps of: S1: Providing an inspection template, said template having dimensions and shapes corresponding to tolerances maximum of the area, S2: place the template against the area, S3: fix the template on the area, S4: deduce whether the area complies with the manufacturing tolerances. Figure for the abstract: Fig. 3

Description

Method and device for checking a protective sheet in a turbomachine

GENERAL TECHNICAL AREA

The present invention relates to the field of turbomachines, and more particularly bearing supports for low-pressure turbines.

STATE OF THE ART

A turbofan engine generally comprises, from upstream to downstream in the direction of gas flow, a fan, an annular primary flow space and an annular secondary flow space.

The primary flow space passes through a primary body comprising one or more compressor stages, for example a low pressure compressor and a high pressure compressor, a combustion chamber, one or more turbine stages, for example a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle.

A turbomachine generally comprises a low pressure shaft, driven in rotation by a low pressure turbine, generally housed in a high pressure shaft, driven in rotation by a high pressure turbine. Driveshafts are supported and guided by structural parts called bearings. The bearings are generally ball or roller bearings.

The low-pressure shaft is in particular supported by a bearing which can be mounted on the low-pressure shaft and on the inter-turbine casing of the turbomachine (Turbine Center Frame, TCF). This bearing is fixed to a flange of the inter-turbine casing via a bearing support.

The bearing support is subjected to relatively high stresses of thermal origin.

The motor further comprises a seal of the labyrinth seal type, extending close to the bearing support. However, these seals are sensitive to their environment and must be protected from oil splashes. This is why it was proposed to fix protective plates on the bearing support near these labyrinth seals in order to form a physical barrier against these oil splashes. Typically, a first sheet can be fixed at the level of an oil inlet zone and a second at the level of a recovery zone.

Generally, the sheets are obtained by stamping and then machined, generally by milling, to the appropriate dimensions. They are then attached and fixed by screwing on the bearing support. However, the permissible dimensional tolerance for these sheets is low in order to meet assembly criteria, of the order of a few tenths of a millimetre.

This control is generally carried out using a coordinate measuring machine (CMM) configured to feel several points on each boss, typically a dozen points. This check is long, around ten minutes. In addition, in areas with a radius of curvature smaller than that of the probing tool, it is difficult to obtain reliable control so that the control must be carried out in a different way, which increases the control time. overall compliance of the part.

An objective of the invention is to propose a solution to the problems identified, and in particular to improve the control of the conformity of the fixing zones of the protection plates.

The aforementioned objects are achieved by the present invention thanks to a method for controlling at least one zone of a bearing support comprising the following steps:

S1: Provide a control template, said template having dimensions and shapes corresponding to maximum tolerances of the zone,

S2: place the template against the area,

S3: fix the template on the area,

S4: deduce if the zone respects the manufacturing tolerances.

Certain preferred but non-limiting characteristics of the control method described above are the following, taken individually or in combination:

- the zone comprises at least one boss configured to receive a protective sheet, step S2 comprising the placement of the jig resting against said bosses.

- the zone comprises at least one span, configured to receive a protective sheet, step S2 comprising the placement of the jig resting against the span.

- an orifice is formed in each zone of the parlier support, the template comprises associated orifices and in which: step S2 comprises positioning the orifice(s) of the template opposite the orifice(s) of each zone and step S3 comprises inserting a fixing screw into the hole(s) of the template and the hole(s) of each zone.

- the process further includes the inspection of an additional area of the bearing support using an additional inspection gauge in accordance with steps S2 to S4.

- the bearing support area is obtained by milling.

According to a second aspect, the invention also proposes an inspection jig configured to implement a method for inspecting at least one zone of a bearing support, said jig having dimensions and shapes corresponding to maximum tolerances of the zone and comprising a wall configured to be placed and secured against said area.

Certain preferred but non-limiting characteristics of the control template described above are the following, taken individually or in combination:

- orifices are formed in the wall, a dimension, a shape and a position of said orifices corresponding to a dimension, a shape and a position of corresponding orifices formed in the zone.

- the template further comprises a gripping member, for example a handle, so as to facilitate its placement on the zone of the bearing support.

- the wall has a first end forming a shoulder configured to bear against at least one boss of the bearing support and a second end, opposite the shoulder and configured to bear against a bearing surface of said bearing support.

QUICK DESCRIPTION OF FIGURES

Other characteristics, aims and advantages of the invention will appear on reading the detailed description which follows, and with reference to the appended drawings, given by way of non-limiting examples and in which:

: Figure 1 illustrates a top view of an embodiment of a bearing support after machining having several areas to be checked,

: FIG. 2 is a flowchart illustrating the steps of an example of a control method in accordance with the present invention,

: Figure 3 illustrates the fixing of two examples of control jigs on two zones of the bearing support of figure 1.

DETAILED DESCRIPTION OF THE INVENTION

As explained previously, a turbomachine generally comprises at least one structural part, called a bearing support, which supports a bearing inside which rotates a rotating shaft, for example a low-pressure shaft.

Figure 1 shows a top view of a bearing support 1 in an exemplary embodiment.

The bearing support 1 comprises a substantially cylindrical downstream part 2, having on its downstream end a fixing flange configured to be assembled with the bearing, as well as a substantially frustoconical upstream part 3 having on its upstream end a fixing flange 30 configured to be fixed to the inter-turbine casing.

The turbomachine further comprises a seal of the labyrinth seal type configured to provide a seal within an enclosure for the lubricating oil. The enclosure is arranged to hermetically confine the bearings of the bearings that need to be lubricated, and to prevent the lubricating oil from reaching other compartments. The substantially frustoconical upstream part 3 of the bearing support comprises two openings 31, 32. A first opening 31 corresponds for example to a lubricating oil inlet, at which the lubricating oil is injected by an injector onto the bearings of the bearing, and a second opening 32 corresponds for example to a recovery of the lubricating oil, at which the lubricating oil is recovered by a drain.

In order to prevent lubricating oil splashes, generated for example by rotating parts, from reaching the labyrinth seal, protective plates are fixed on an external surface of the bearing support 1, between the bearing support and the labyrinth seal, and are configured to cover at least partially the openings 31, 32 formed in the substantially frustoconical upstream part 3 of the bearing support 1. arrival opening 31 of the floor support 1, and a second sheet, called recovery, fixed at the level of the opening 32 of recovery of the landing support 2.

More specifically, the protective sheet is fixed against the outer surface of the bearing support 1, on either side of each opening 31, 32. For this, the bearing support 1 comprises at least one boss 4, extending near of the downstream part 2, and at least one bearing surface 5 extending close to the fixing flange 30. In the embodiment illustrated in FIGS. 1 and 3, the bearing support 1 comprises two bosses 4 per opening, said bosses 4 extending between the downstream edge of the opening 31, 32 and the downstream part 2, and a bearing surface 5 extending between the upstream edge of the opening 31, 32 and the fixing flange 30.

Each protective sheet is then configured to bear against each boss 4 and each bearing surface 5 of the associated opening 31, 32.

Orifices can also be machined, for example by milling, in the bosses 4 and the bearing surfaces 5 in order to allow the protective sheets to be fixed by screwing.

In order to facilitate the dimensional check of the bosses 4 and of the fixing holes of the protective sheet, there is proposed a method for checking at least one zone of a bearing support 1, characterized in that it comprises the steps of :

S1: provide a control template, said template having dimensions and shapes corresponding to maximum tolerances of the zone,

S2: place the template against the area,

S3: fix the template on the area,

S4: deduce if the zone respects the manufacturing tolerances.

FIG. 2 illustrates the steps of the control method according to this example embodiment. Figure 3 shows a perspective view of an embodiment of a bearing support 1, on which is fixed the control jig 6.

During the first step S1, the inspection template 6 is provided, having the dimensions and shapes which correspond to the maximum tolerances of the zone to be inspected.

The control jig 6 is configured to control at least one zone of the bearing support 1 and has dimensions and shapes corresponding to the maximum tolerances of the zone. For this purpose, the template 6 comprises a wall configured to be placed and fixed against said zone of the bearing support 1, typically against the bosses 4 and the bearing surface 5 of each opening 31, 32.

The zone to be checked can in particular be obtained by milling, typically if the bearing support 1 is formed by casting a metal or a liquid alloy then machined after cooling by milling to form the zone.

The arrival sheet and the recovery sheet having distinct shapes, it will be understood that the process is applied to each corresponding opening 31, 32 with a suitable template 6. In other words, steps S1 to S4 are applied to each opening 31, 32 of the bearing support 1, with a suitable inspection gauge 6, as shown in figure 3.

Typically, the wall of the control jig 6 comprises three portions: a first end configured to bear against the boss(es) 4, a second end opposite the first end and configured to bear against the bearing surface(s) 5 and a intermediate portion extending between the two ends. It will be noted that the bosses 4 and the bearing surfaces 5 are arranged on an outer surface of the bearing support 1. Furthermore, the bearing surfaces 5 are arranged radially outside with respect to the bosses 4. In one embodiment, the template 6 is made in one piece, that is to say completely and in one piece, typically by additive manufacturing.

The first end extends from the intermediate portion and forms a shoulder so as to come opposite the boss(es) 4 of the bearing support 1. In the case where the bearing support 1 comprises two bosses 4, the first end may comprise two portions distinct configured to each come into contact with one of the two bosses 4.

The second end also extends from the intermediate portion, axially opposite the first end.

The first and the second end further comprise as many orifices as there are bosses 4 and bearing surfaces 5, respectively, so as to allow fixing by screwing of the protective sheet. Advantageously, a dimension, a shape and a position of each orifice corresponds to a dimension, a shape and a position of corresponding orifices formed in the bosses 4 and the surfaces 5, respectively, so as to allow the introduction and the attachment of suitable screws or threaded rods.

For example, when the bearing support 1 comprises two bosses 4 and a surface 5, the inspection jig 6 comprises three holes intended to receive fixing means, typically fixing screws 7, in order to be assembled on the area of the support bearing 1 to be checked, two of the orifices being formed in the first end while the third orifice is formed in the second end.

The intermediate portion may have any suitable shape making it possible to rigidly connect the first and the second end in order to guarantee the relative position of the first end and the second end.

In one embodiment, the control template 6 further comprises a gripping member, typically a handle, intended to facilitate the gripping and positioning of the template 6 on the bearing support 1. The gripping member can for example form a protrusion at an outer surface of the template wall 6.

In order to dimension the template 6, the maximum dimensional tolerances of the zones to be checked of the bearing support 1 are determined, typically the maximum dimensional tolerances of the bosses 4, of the surfaces 5 and of the orifices formed in these zones. By maximum dimensional tolerances, we understand here the extreme dimensions admissible for the subsequent mounting of the protective plates.

It will be noted that the template 6 can be made beforehand and simply reused, or alternatively be made specially for step S1, for example by implementation by computer-aided design software.

If necessary, the dimensions of template 6 can be checked using a three-dimensional measuring machine.

During a second step S2, the template 6 provided during the first step S1 is placed against the zone of the bearing support 1 to be checked, typically against the bosses 4 and the bearing surfaces 5.

For this, the first end is placed against the boss(es) 4 while the second end is placed against the bearing surface(s) 5, aligning the holes of the template 6 with those of the bearing support 1, then, during a third step S3, the template 6 is fixed in position by suitable means, typically by screwing.

Advantageously, the assembly of the jig 6 with the bearing support 1 is done by inserting a plurality of fixing screws 7 into the holes of the jig 6, then screwing. Typically, each boss 4 includes a threaded blind hole and each bearing surface 5 includes a through hole. A threaded screw 7 is screwed into the threaded blind hole of each boss 4 and a screw is inserted into the through hole of each bearing 5, then fixed with a nut.

During a fourth step S4, it is deduced therefrom whether the zone complies with the manufacturing tolerances. In particular, the zone is considered to be compliant from the moment it is possible to fix the template 6, whose dimensions correspond to the maximum admissible dimensional tolerances, on the bearing support 1.

In the event that the template 6 cannot be fixed to the zone of the bearing support 1 correctly, typically in the event that at least two holes of the template 6 intended to receive the fixing means cannot be simultaneously aligned with corresponding holes on the area, bearing support 1 is considered non-compliant. The bearing support 1 can then undergo other processing operations, typically a new machining in order to be able to be assembled correctly with the control jig 6, or can be removed from the production line.

Claims (10)

Method for checking at least one zone of a bearing support (1), characterized in that it comprises the steps of:
S1: Provide a control template (6), said template having dimensions and shapes corresponding to maximum tolerances of the zone,
S2: place the template (6) against the area,
S3: fix the template (6) on the area,
S4: deduce if the zone respects the manufacturing tolerances. Method according to claim 1, in which the zone comprises at least one boss (4) configured to receive a protective sheet, the step S2 comprising placing the template (6) in abutment against the said bosses (4). Method according to one of Claims 1 or 2, in which the zone comprises at least one bearing surface (5), configured to receive a protective sheet, the step S2 comprising placing the template (6) bearing against the bearing surface ( 5). Method according to one of Claims 1 to 3, in which an orifice is formed in each zone of the floor support (1), the template (6) comprises associated orifices and in which:
step S2 includes positioning the orifice(s) of the template (6) opposite the orifice(s) of each zone and
step S3 includes inserting a fixing screw (7) into the hole(s) of the template (6) and the hole(s) of each zone. Method according to one of claims 1 to 4, further comprising inspecting an additional area of the bearing support (1) with the aid of an additional inspection gauge (6) in accordance with steps S2 to S4. Method according to one of Claims 1 to 5, in which the area of the bearing support (1) is obtained by milling. Inspection jig (6) configured to implement a method for inspecting at least one zone of a bearing support (1) according to any one of claims 1 to 6, said jig (6) having dimensions and shapes corresponding to maximum tolerances of the zone and comprising a wall configured to be placed and fixed against said zone. A control jig (6) according to claim 7, wherein holes are formed in the wall, a size, shape and position of said holes corresponding to a size, shape and position of corresponding holes formed in the area. Control jig (6) according to one of claims 7 or 8, further comprising a gripping member, for example a handle, so as to facilitate its placement on the zone of the bearing support (1). Control gauge (6) according to one of Claims 7 to 9, in which the wall has a first end forming a shoulder configured to bear against at least one boss (4) of the bearing support (1) and a second end , opposite the shoulder and configured to bear against a bearing surface (5) of said bearing support (1).