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FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
& The Patent Rules, 2003
COMPLETE SPECIFICATION
1. TITLE OF THE INVENTION:
METHOD FOR ASSEMBLING TURBOMACHINE PARTS AND ASSEMBLY USED
DURING SUCH A METHOD
2. APPLICANT:
Name: SNECMA
Nationality: France
Address: 2 boulevard du Général Martial Valin, F-75015 Paris, FRANCE.
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which
it is to be performed:
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DESCRIPTION
TECHNICAL DOMAIN
The invention relates to the domain of assembling turbomachine parts.
Manufacturing of a turbomachine necessarily involves several assembly
steps some of which are particularly time and energy consuming.
Thus the invention relates to a method for assembling turbomachine
parts and an assembly used during this assembling method.
STATE OF PRIOR ART
It is known that vulcanisable elastomers such as silicone that can be
vulcanised at ambient temperature can be used to assemble two turbomachine parts.
Such an assembly is usually obtained by using a method for the
assembly of turbomachine parts comprising steps to:
- assemble the first and the second parts on a support;
- inject a vulcanisable elastomer such as a silicone that can be vulcanised
at ambient temperature, at a chosen injection zone at the junction of the first part and
the second part;
- place the support and the first part and the second part in an drying
oven at 100°C for a duration usually lasting about 1 hour;
- cool the support and the first part and the second part;
- disassemble the assembly of the first part and the second part.
Although such a method can vulcanise the elastomer faster than
vulcanisation at ambient temperature, it has a number of disadvantages.
The use of a drying oven to heat the support and the two parts is
particularly energy consuming when the parts to be assembled are large and particularly
heavy. Moreover, the time necessary to cool this type of heavy part can exceed 2 hours
and even 4 hours. Finally, it should be noted that the operator must put the support and
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all the parts to be assembled in the drying oven and then remove them. These operations
can be particularly difficult for the operator when these parts are heavy and large.
Prior art also includes the method of performing the heating step using
a warm chamber instead of a drying oven. Such a warm chamber is formed by a cover of
the support or a blanket placed on the support. The cover or the blanket includes a
heating system to heat the support and all the parts to be assembled so as to vulcanise
the elastomer.
Nevertheless, although such a warm chamber system limits handling
problems for the support and all the parts to be assembled, problems related to energy
used to achieve this vulcanisation and heating and cooling times remain unchanged.
It should be noted that the problems mentioned above particularly exist
in the case of an assembly of a guide vane from an inner shell and an outer shell on which
the vanes have already been fixed, due to the mass and dimensions of the inner and
outer shells.
PRESENTATION OF THE INVENTION
The invention aims at overcoming these disadvantages.
One purpose of the invention is to disclose an assembly method
including a vulcanisation step with a lower energy consumption than assembly methods
according to prior art that include a vulcanisation step.
Another purpose of the invention is to disclose an assembly method
with a vulcanisation step, for which the duration of the cooling step is shorter than it is
for assembly methods according to prior art that include a vulcanisation step.
To achieve this, the invention relates to a method for assembly of a first
turbomachine part with at least one second turbomachine part, comprising the following
steps:
- injection of a vulcanisable elastomer, preferably a silicone that can be
vulcanised at ambient temperature called an RTV silicone, in an injection zone at the
junction between the first and the second parts,
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- local heating of the injection zone so as to vulcanise the vulcanisable
elastomer.
A « Local heating of the injection zone so as to vulcanise the
vulcanisable elastomer» step is a step in which heating is done so as to provide local
heating in the injection zone and thus prevent overheating of the first part and the
second part.
Thus, due to the use of such an assembly method, all that is necessary is
to provide the energy necessary to heat the injection zone only, without overheating the
first and the second parts. The result is much lower energy consumption than methods
according to prior art, together with shorter heating and cooling times.
The first part and the second parts may be two annular parts that will
form a turbomachine guide vane after assembly.
The first part may be an inner shell of the guide vane, the second part
being formed from an outer shell on which vanes have already been assembled.
The first part may be an inner shell of the guide vane, the second parts
being vanes.
Such methods are particularly advantageous for such parts due to the
particularly large mass of parts used in a guide vane. Therefore, the energy and assembly
time benefits are particularly advantageous.
The local heating step can be implemented using an assembly
comprising a support for the first part and the second parts and a local heating system
comprising a heating zone and that is associated with the support such that the heating
zone is facing the injection zone while the heating step is being performed.
Such an assembly can provide particularly efficient local heating because
the heating zone is directly facing the injection zone.
The assembly can also act as an assembly support used during the
elastomer injection step.
Thus, there is no need to handle the assembly composed of the first part
and the second part after injection. This results in a time saving and elimination of a step
that is particularly difficult for the operator.
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The local heating step may be implemented through the use of a
heating element previously placed on the two parts of the turbomachine close to the
injection zone.
Such a heating element can perform the local heating step directly on a
conventional assembly support used during the injection step, therefore without it being
necessary to disassemble the assembly formed by the first part and the second part.
During the local heating step, the heating element may be in contact
either with the first or the second part of the turbomachine, said part among the first and
the second parts having a surface facing the injection zone.
The local heating step can be implemented using a heating system
external to the support such as a hot air blowing system at the injection zone, laser
radiation or microwave radiation.
With such external heating systems, the local heating step can be
performed with parts that remain in position on a conventional assembly support used
during the injection step, therefore without it being necessary to disassemble the
assembly formed from the first and the second parts.
The invention also relates to an assembly for assembling a first
turbomachine part with at least a second turbomachine part by injection and
vulcanisation of a vulcanisable elastomer in an injection zone at the junction of the first
and the second parts, said assembly comprising a support and a local heating system, the
local heating system comprising a heating zone, said support and said heating system
being associated such that the heating zone faces the injection zone once the first part
and the second part have been assembled.
Such an assembly can provide a means of assembling the first part on
the second part that can be used during the step to inject the vulcanisable elastomer and
the local heating step.
The local heating system includes, for furnishing the heating surface, a
heating means selected among the group comprising a circuit carrying a heating liquid, a
heating resistance, a Peltier effect system and an induction coil.
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Such heating means provide local heating that requires a relatively small
volume for its installation and therefore that can easily be integrated in an assembly
according to the invention.
The heating system may be integrated into the support, for example by
forming an annular centring wall designed and arranged to centre the assembly formed
by the first part and the second part.
The support may comprise a base from which an annular support wall of
the local heating system extends, the local heating system being installed along the
annular wall and being sized and arranged to centre the assembly with the heating zone
facing the injection zone.
The support can include the heating system in a centring wall of the
assembly.
The complete assembly may form a support for the assembly of a
turbomachine guide vane.
BRIEF DESCRIPTION OF THE DRAWINGS
This invention will be better understood after reading the detailed
description of example embodiments given purely for information and that are in no way
limitative, with reference to the appended drawings in which:
- figure 1 shows an assembly used during an assembly method
according to a first embodiment of the invention in which heating is provided by a heat
conveying liquid, the two parts to be assembled being arranged on the assembly;
- figure 2 shows an assembly used during an assembly method
according to a second embodiment of the invention in which heating is provided by a
heating resistance, two parts to be assembled being placed on the assembly;
- figure 3 shows a local heating step of an assembly method
according to a third embodiment in which a heating strip is used;
- figure 4 shows a local heating step of an assembly method
according to a fourth embodiment in which stationary hot air blowing is applied;
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- figure 5 shows a local heating step of an assembly method
according to a fifth embodiment in which rotating hot air blowing is used.
Identical, similar or equivalent parts in the different figures have the
same numeric references to facilitate comparison between the different figures.
The different parts shown in figures are not necessarily all at the same
scale, to make the figures more easily legible.
The different possibilities (variants and embodiments) must be
understood as not being mutually exclusive and they can be combined with each other.
DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
Figure 1 shows an assembly 20 for assembling a turbomachine guide
vane 100 starting from an inner shell 110 and an outer shell 120 on which vanes 130 have
previously been mounted.
Such an assembly 20 is used during assembly of a guide vane 100
comprising steps to:
- install the outer shell 120 on the inner shell 110 with ends of vanes 130
opposite the outer shell 120 housed in the corresponding orifices in the inner shell 110;
- place the inner shell 110/ outer shell 120 assembly on the assembly 20;
- place an injection cover 30 on the assembly 20 to close off an injection
zone 140 at the junction of the inner shell 110 and vanes 130 installed on the outer shell
120;
- inject a silicone 145 that can be vulcanised at ambient temperature,
better known under the term RTV silicone;
- locally heat the injection zone 140 so as to vulcanise the silicone 145
and seal the vanes 130 on the inner shell 110 and seal the junction between the vanes
130 and the inner shell 110.
Such a method of assembling a guide vane 100, except for the local
heating step, is disclosed in French patent FR 2958323. This is why specific features of
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steps other than the local heating step will not be described in more detail in this
document.
Such an assembly method can be used for sealing vanes 130 in the inner
shell 110 while providing an abradable seal function for the rotor/stator assembly of the
turbomachine.
The assembly 20 comprises an assembly support 22 and a centring and
heating ring 25.
The support 22 comprises a base 23 and an annular support wall 24 for
the ring 25. The base 23 is generally in the shape of a disk for which the outside diameter
is greater than or equal to the diameter of the outer shell 120. The annular wall 24 is in
the form of a cylindrical envelope that extends from the base 23 transverse to the base
23 with an outside diameter less than the outside diameter of the inner shell 110.
The ring 25 is adapted to be mounted radially outside the annular wall
24 and to achieve this, it has an inner profile complementary to the outer profile of the
annular wall 24. Thus, the inside diameter of the ring 25 is slightly larger than the outside
diameter of the annular wall 24. The outer profile of the ring 25 opposite the annular wall
24 is adapted as a function of injection constraints in order to apply the required shape
on the silicone 145 when it is injected. The same outer profile of the ring 25 also performs
a guide function for the inner shell 110 so as to centre it during its placement on the
assembly 20. In this way, the ring can centre the inner shell 110 assembly relative to the
outer shell 120 as it is placed on the assembly 20.
It should be noted that according to one possibility of the invention, a
same support 22 may be associated with several rings 25, each ring 25 having an outer
profile corresponding to a type of guide vane 100. Such a possibility makes it possible to
use a single support 22 for the assembly of several types of guide vanes 100.
The ring 25 comprises a heating device 26 consisting of a heat conveying
liquid circuit. The heating device 26 is built into the ring 25 such that it delimits a heating
zone 27 facing the injection zone 140, when the assembly 20 supports the inner shell
110/ outer shell 120 assembly.
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The heating device 26 forms a heating means while the ring 25 forms a
local heating system.
According to one possibility of the invention not shown, the ring 25 may
also include a temperature measurement system such as a thermocouple. Such a
temperature measurement system is particularly advantageous to check that the heating
device 26 applies heat to the injection zone 140 correctly and therefore vulcanises the
silicone 145.
According to one advantageous possibility not shown, the ring 25 may
be formed from two different materials, one being a thermal insulating material that in
particular forms the inner surface of the ring that is in contact with the support 22, the
other being a heat conducting material such that the ring 25 has a heating zone 27 with a
relatively homogeneous temperature.
The injection cover 30 is placed on the assembly 20 after the inner shell
110 and the outer shell 120 have been assembled. In this way, the injection cover 30
closes off the injection zone 140. The injection zone 140 is then delimited by the outside
surface of the ring 25, the inner shell 110 and the injection cover 30. The injection zone
140 and the shape of the seal formed during this injection are perfectly defined.
With such an assembly 20 according to this first embodiment, heat
conveying liquid heated at temperature is circulated in the heat conveying circuit during
the local heating step to bring the heating surface 27 to a temperature and to vulcanise
the injected silicone 145. Thus, in the special case of RTV silicone, the heat conveying
liquid may for example be at a temperature of 60°C and it may be circulated in the heat
conveying liquid circuit for an approximately 30-minute period during the local heating
step.
With such a heating device 26, it is also possible to use the heat
conveying circuit to provide active cooling to the injection zone 140. After circulation of a
heat conveying liquid during the local heating step, a liquid with a temperature lower
than the temperature of the injection zone 140 can be circulated to obtain active cooling.
Figure 2 shows an assembly 20 according to a second embodiment of
the invention in which the heating device 26 is a resistive heating circuit. Such an
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assembly is different from an assembly 20 according to the first embodiment in that the
heat conveying liquid circuit is replaced by a resistive heating circuit.
Such an assembly 20 is also different in its application, since this latter
assembly 20 cannot be adapted to provide active cooling of the injection zone 140 after
the local heating step.
According to other possibilities not shown, the heating device 26 may
also be a Peltier effect system or an induction coil. In a manner similar to the heat
conveying circuit, a Peltier system can be adapted to provide active cooling. In the case of
an induction coil built into the ring 25, an inductive current generator is also necessary to
generate current in the induction coil.
According to one possibility of these first two embodiments, the
assembly may comprise a single support 22, the annular wall 24 being adapted to
perform the guidance and centring function of the inner shell 110/outer shell 120
assembly and comprising the heating device 27 so as to provide the heating zone facing
the injection zone.
Figure 3 shows a local heating step of an assembly method according to
a third embodiment in which local heating is provided by a heating element 40 placed on
the vanes 130 close to the injection zone 140. The heating element 40 must be placed
sufficiently close to the injection zone 140 to provide local heating of the injection zone
140. An assembly method according to this third embodiment is different from a method
according to the first embodiment in that it does not use a ring 25 and in that the heating
step uses a heating element 40 rather than a heat conveying circuit 26 built into a ring 25.
Therefore in this third embodiment, the assembly 20 comprises only the
assembly support 22. The annular wall 24 is configured for guiding and centring the inner
shell 110 so as to centre the inner shell 110/outer shell 120 assembly during its placement
on the assembly 20. Similarly, the profile of the outside surface of the annular wall 24 is
adapted as a function of injection constraints in order to apply the required shape on the
silicone 145 when it is injected.
In this third embodiment, the heating element 40 is a heating strip for
which the temperature is preferably controlled to an appropriate temperature to
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vulcanise the silicone 145. For example, this temperature could be 60°C in the case of an
RTV silicone.
The local heating step according to this third embodiment comprises the
following sub-steps:
- placement of the heating element 40 on the vanes 130 close to the
injection zone 140,
- use of the heating element 40 so as to locally heat the injection zone
140.
During placement of the heating element 40 on the vanes 130, this
heating element is put into contact with the inner shell 110 that has a surface area facing
the injection zone 140. Thus, during placement of the heating element, a large proportion
of the heat transmitted by the heating element 40 to the inner shell 110 is applied to the
injection zone 140 by the surface of the inner shell 110 that is facing the injection zone
140. Application of heat in this way can provides a local heating of the injection zone 140.
Figure 4 shows a local heating step in an assembly method according to
a fourth embodiment in which local heating is provided by blowing hot air 50 onto the
injection zone 140. A method according to this fourth embodiment is different from the
method according to the third embodiment in that it does not use a heating element 40
placed on the vanes 130 and in that the local heating is provided by a remote heating
system not shown.
Such a local heating step may for example be implemented using a
blower hood with a hot air flow 50 blown towards the injection zone so as to vulcanise
the silicone 145. This blower hood may be a permanently installed blower system or it
may be a blower device that the operator places above the assembly support 22 facing
the injection zone.
Figure 5 shows a local heating step in an assembly method according to
a fifth embodiment of the invention in which local heating is provided by blowing rotating
hot air 50 that moves along the injection zone 140. A method according to this fifth
embodiment is different from the method according to the fourth embodiment in that
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the hot air flow 50 during the heating step is a concentrated air flow directed towards the
injection zone 140 and that is free to move so as to cover the entire injection zone 140.
Such a concentrated hot air flow 50 may be provided for example by a
thermal stripper, the operator applying the local heating step by blowing hot air 50
output from the thermal stripper towards the injection zone 140.
Such a concentrated hot air flow 50 may also be provided by a blowing
device fitted with a mobile blowing nozzle. The blowing nozzle of such a device is
designed to be positioned facing the injection zone 140 during the local heating step, with
its hot air flow 50 concentrated towards the injection zone. During this blowing step, this
blowing nozzle is moved along the injection zone 140 so as to cover the entire injection
zone, with a circular movement. Such a movement of the blowing nozzle provides
rotating blown hot air.
According to another possible embodiment, remote heating may also be
provided by laser radiation or microwave radiation instead of a hot air flow 50. The
constraints with such a remote heating means are similar to constraints for a hot air flow
50, and therefore will not be described more precisely in this document.
Obviously, although the first part and the second part are an inner shell
110 and an outer shell 120 of a guide vane 100 in all the embodiments described above,
the use of such methods can obviously be transposed to the assembly of other
turbomachine parts whenever this assembly involves the injection of an elastomer that
can be vulcanised, regardless of whether or not it is a silicone 140.
Thus obviously, the invention covers assembly methods for
turbomachine parts using a vulcanisable elastomer other than RTV silicone.
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We claim:
1. Method for assembly of a first turbomachine part with at least one
second turbomachine part, comprising the following steps:
- injection of a vulcanisable elastomer, preferably a silicone (145) that
can be vulcanised at ambient temperature called an RTV silicone, in an injection zone
(140) at the junction between the first and the second parts,
- local heating of the injection zone (140) so as to vulcanise the
vulcanisable elastomer.
2. Assembly method according to claim 1, in which the first and the
second parts are two annular parts that will form a turbomachine guide vane (100) after
assembly.
3. Method according to claim 1 or 2, in which the local heating step is
implemented using an assembly (20) comprising a support (22) for the first and the
second parts and a local heating system comprising a heating zone (27) and that is
associated with the support (22) such that the heating zone (22) is facing the injection
zone (140) while the heating step is being performed.
4. Method according to the previous claim, in which the assembly (20)
also acts as an assembly support used during the elastomer injection step.
5. Method according to claim 1 or 2, in which the local heating step is
implemented through the use of a heating element previously placed on the two parts of
the turbomachine close to the injection zone (140).
6. Method according to claim 1 or 2, in which the local heating step is
implemented using a remote heating system such as a hot air blowing system (50) at the
injection zone (140), laser radiation or microwave radiation.
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7. Assembly (20) for assembling a first turbomachine part with at least
a second turbomachine part by injection and vulcanisation of a vulcanisable elastomer in
an injection zone (140) at the junction of the first and the second parts, said assembly
(20) being characterised in that it comprises a support (22) and a local heating system,
the local heating system comprising a heating zone (27), said support (22) and said
heating system being associated such that the heating zone (27) faces the injection zone
once the first part and the second part have been assembled (140).
8. Assembly (20) according to the previous claim, in which the local
heating system includes, for furnishing the heating surface (27), a heating means selected
among the group comprising a circuit carrying a heating liquid, a heating resistance, a
Peltier effect system and an induction coil.
9. Assembly (20) according to any one of the two previous claims, in
which the local heating system is integrated into the support (20), for example by forming
an annular centring wall designed and arranged to centre the assembly formed by the
first part and the second part.
10. Assembly (20) according to the previous claim, in which the
complete assembly forms a support for the assembly of a turbomachine guide vane (100).
Dated this 11th day of January, 2016.
(CHETAN CHADHA)
PATENT AGENT
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ABSTRACT
METHOD FOR ASSEMBLING TURBOMACHINE PARTS AND ASSEMBLY USED DURING
SUCH A METHOD
The invention relates to a method for assembly of a first turbomachine part with at least
one second turbomachine part, comprising the following steps: injection of a vulcanisable
elastomer, preferably a silicone (145) that can be vulcanised at ambient temperature
called an RTV silicone, in an injection zone (140) at the junction between the first and the
second parts; local heating of the injection zone (140) so as to vulcanise the vulcanisable
elastomer. The invention also relates to an assembly (20) used during such an assembly
method. Figure 1 is the representative figure.