Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/10—Cores; Manufacture or installation of cores
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
  • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
  • F01D5/12—Blades
  • F01D5/14—Form or construction
  • F01D5/18—Hollow blades, i.e. blades with cooling or heating channels or cavities; Heating, heat-insulating or cooling means on blades
  • F01D5/187—Convection cooling
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2230/00—Manufacture
  • F05D2230/20—Manufacture essentially without removing material
  • F05D2230/21—Manufacture essentially without removing material by casting
  • F05D2230/211—Manufacture essentially without removing material by casting by precision casting, e.g. microfusing or investment casting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2260/00—Function
  • F05D2260/60—Fluid transfer
  • F05D2260/607—Preventing clogging or obstruction of flow paths by dirt, dust, or foreign particles

Definitions

• the present invention relates to the general field of turbomachine turbine blades, and more particularly to turbine blades provided with integrated cooling circuits produced by the lost-wax casting technique.
• a turbomachine comprises a combustion chamber in which air and fuel are mixed before being burned.
• the gases from this combustion flow downstream of the combustion chamber and then feed a high pressure turbine and a low pressure turbine.
• Each turbine has one or more rows of stationary blades (called distributors) alternating with one or more rows of moving blades (called moving wheels), circumferentially spaced around the rotor of the turbine.
• These turbine blades are subjected to very high temperatures of the combustion gases, which reach values much higher than those which can bear without damage these blades which are in direct contact with these gases, which necessarily implies to ensure their cooling continuously by an integrated cooling circuit which, when it wishes to ensure efficient and precise cooling without significantly increasing the air flow and without penalizing the engine performance, has multiple cavities.
• the hollow vanes thus formed are manufactured by the so-called "lost wax” foundry process which requires the use of a model piece or core whose outer surface corresponds to the internal surface of the finished blade, as described in patent application FR2961552. filed in the name of the plaintiff.
• the air necessary for the operation of the engine generally contains various dusts (in particular fine sand) which can accumulate in the cooling circuits of the turbine blades causing the closing of the outflow orifices at the outlet of the cavities and thus threatening the integrity of the dawn.
• the blades of turbine are equipped at the top of the cavity with calibrated dust extraction holes, obtained by high-precision machining or from connecting rods of alumina or quartz inserted in the ceramic core, and whose role is to generate these holes and to guarantee evacuation of these particles after their stall (that is to say their dissolution).
• the use of these connecting rods poses certain problems.
• the alumina rods are very difficult to remove by the basic solutions (or in the standard unsteady conditions of the ceramic cores) and require a high residence time, a very high concentration of sodium hydroxide or potassium hydroxide and temperatures and pressures. very high likely to be aggressive vis-à-vis the alloy (stress corrosion).
• the quartz rods have a low mechanical strength thus penalizing their use in a lost wax casting process or the core which has a different coefficient of thermal expansion (CTE) and is also often of different composition, undergoes several mechanical stresses .
• CTE coefficient of thermal expansion
• the use of rods is not applicable in all core manufacturing processes.
• the rods can not be embedded in the core during manufacture (in contrast to the injection molding process).
• the use of rods is not applicable to all core geometries including those using thin plates whose rods must then marry the shape.
• the present invention therefore aims to overcome the aforementioned drawbacks by proposing a geometric layout of the core to simply obtain dust collection holes more reliably than currently and in particular without harming the strength of this core. Another purpose is to eliminate the final drilling operation of the bath of the prior art to obtain these holes.
• a ceramic core used for the manufacture of a turbomachine hollow turbine blade according to the lost wax foundry technique, said blade having calibrated dusting holes emanating from a vertex of at least one embodiment. at least one cavity and opening into a bath of said blade, characterized in that each of said calibrated dust removal holes is formed in a core portion of a determined height sufficient to guarantee the mechanical strength, said core portion having a through hole an axis perpendicular to a longitudinal axis of said calibrated dust removal hole and defining on either side of said through orifice on the one hand a core cylinder of a determined diameter corresponding to said dusting hole to be formed and on the other hand a remaining core volume to be closed after casting, so that said calibrated dust removal hole is obtained without drilling and without use of connecting rods.
• the dedusting holes can be obtained directly from the foundry by injection, additive manufacturing or machining ceramic cores without drilling or use of connecting rods. Any possible source of differential thermal expansion is suppressed, the mechanical strength of the core is improved and correlatively the mechanical properties of the blade are thus maintained. With this core, the machining operation of the prior art to take into account constraining uncertainties and can adversely affect the geometry of the plates of a multi-cavity circuit is also removed.
• said core portion may form a portion of a side column for creating a cavity lateral of said blade or an inter-cavity connection zone between said at least one cavity and said bath.
• a recessed area to allow a centering of said through hole in said connecting zone, so as to ensure a better holding of said core portion during the casting.
• said remaining core volume comprises at least one lateral stiffener (two stiffeners giving it a quadrilobed shape) dimensioned so as to guarantee better holding of said core portion during casting.
• the invention also relates to the method of forming calibrated dust removal holes in a turbomachine hollow turbine blade produced by the lost-wax casting technique by means of a ceramic core as explained above and any turbomachine turbine equipped with a plurality of cooled vanes made from such a method.
• FIG. 1 is a partial view of a turbine blade core according to the invention
• FIG. 2 is a view of a portion of the core of FIG. 1 at a side plate
• FIGS. 2A and 2B are respectively views after casting and after machining once the core portion of FIG. 2 has been removed
• FIG. 3 is a view of part of the core of FIG. 1 at a connection with the bath
• FIG. 1 represents, at the level of its head assembly, a ceramic core intended for the production of a turbomachine hollow turbine blade.
• the ceramic core 10 in the example illustrated, comprises seven parts or columns.
• the first column 12 which is intended to end up on the side of the arrival of the combustion gases, corresponds to a leading edge cavity which will be created after foundry, while the second column 14 corresponds to a central cavity which it is adjacent. The latter receives a flow of cooling air through a pipe resulting after foundry, the presence of a first column foot of the core.
• the core further comprises sixth and seventh lateral columns 22, 24 corresponding to lateral cavities created after casting and separated one and the other of the second and third columns 14, 16 by a determined spacing necessary for the creation of a solid inter-cavity wall during casting of the molten metal.
• the first and second columns 12 and 14 are connected to each other by a series of bridges 26, to which will correspond, after casting, air supply ports for cooling the leading edge cavity.
• other bridges 28 vertically inclined forming core thinned regions can create stiffened blade regions.
• the size of the various bridges is determined to prevent them from breaking when handling the core 10, which would render it unusable.
• the bridges are, in the example considered, distributed spaced substantially regularly over the height of the core, particularly at the first column of the core.
• the dedusting holes of the turbine blades necessary for the evacuation of dust (in particular fine sand) which can accumulate in the cooling circuits are obtained by a geometric arrangement of a part of core, directly raw foundry, without drilling and without the use of connecting rods that they are holes in the side cavities of the core than those ensuring the connection with the bathtub.
• the manufacturing process at The lost wax of the dawn once this core is made is conventional and consists first of all in forming an injection mold in which is placed the core before injection of the wax.
• the wax model thus created is then dipped in slips consisting of ceramic suspension to make a casting mold (also called shell mold). Finally, the wax is removed and the shell mold is baked into which the molten metal can then be cast.
• Final machining (however simplified compared with those of the prior art) described above will then allow to get the finished dawn.
• This geometry can be obtained conventionally by integrating a stirrup-type disturbance into the mold of the plate (at a through-orifice of longitudinal axis delimiting in a direction perpendicular to this axis the cylinder 30 and the remaining volume 33) for the case of ceramic injection or without additional stress for the case of additive manufacturing or machining of cores.
• the ceramic cores made by injection to be demolded it must of course be ensured that these cores have sufficient remains relative to a demolding axis technical. Indeed, if this demolding axis is not well oriented, the plate can be greatly weakened.
• FIG. 2A illustrates the upper part of the dawn (bath) obtained at the end of the casting (foundry blank) with the two cavities 32, 34 corresponding to the two lateral columns and the excess material which surrounds them due to the assembly of these columns.
• FIG. 2B there is the same bath after machining this excess material and it is found that with the invention, two holes 36A, 38A; 36B, 38B are formed at each cavity (instead of only one in the prior art).
• One of them 36A, 36B having the dimension of the core cylinder 30 will provide the dust removal function, the other hole 38A, 38B which has no particular function and the size of the remaining core volume 33, is intended to be plugged.
• connection with the tub is illustrated in FIG. 3.
• a local geometrical arrangement of the connection is provided, forming on either side of the through-hole 41 on the one hand a core cylinder 40 of a determined diameter corresponding to the diameter of the dedusting hole to be made and, on the other hand, the remaining core volume 43 intended to be closed after casting.
• the core cylinder also has a smallest possible height to ensure the good behavior of the core and prevent the formation of cracks.
• the through orifice may be formed by the use of a bridge-type interferer integrated in the foundry mold.
• FIG. 3A illustrates the upper part of the dawn (bath) obtained at the end of the casting (foundry blank) with the extension 42 resulting from the removal of the core from the space d.
• FIG. 3B there is the same bathtub after machining of this riser and it is found that with the invention, two holes 44, 46 are formed at the bath.
• stiffeners 48A, 48B giving a quadrilobed shape to the second hole (corresponding to a section of the volume 43) and dimensioned to ensure the strength of the core.
• this also makes it possible to increase the section and to guarantee a better filling and in the cases of an additive manufacturing and a machining of cores, the stiffeners stiffen the connection and prevent the deformation of the elements. nuclei.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Supercharger (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=55650568

Family Applications (1)

Country Status (8)

Families Citing this family (5)

Family Cites Families (11)

• 2016
  • 2016-02-12 FR FR1651134A patent/FR3047767B1/fr not_active Expired - Fee Related
• 2017
  • 2017-02-10 CA CA3014022A patent/CA3014022C/fr active Active
  • 2017-02-10 EP EP17709141.0A patent/EP3414031B1/de active Active
  • 2017-02-10 RU RU2018132349A patent/RU2745073C2/ru active
  • 2017-02-10 US US16/077,171 patent/US10537935B2/en active Active
  • 2017-02-10 CN CN201780011177.3A patent/CN108698117B/zh not_active Expired - Fee Related
  • 2017-02-10 BR BR112018016416-0A patent/BR112018016416B1/pt not_active IP Right Cessation
  • 2017-02-10 WO PCT/FR2017/050310 patent/WO2017137709A1/fr not_active Ceased

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