Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
  • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
  • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
  • B22D13/101—Moulds
  • B22D13/102—Linings for moulds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
  • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
  • B22D13/101—Moulds

Definitions

• the present invention relates to a mold for manufacturing by centrifugal casting of metal parts, in particular turbomachine blades. More specifically, the turbine wheel vanes of a turbojet or an airplane turbo-prop.
• turbomachine blades by machining a blank obtained by casting by casting of a metal alloy.
• the blank is typically a rod of generally elongated solid shape and is machined in the mass to achieve the final geometry of the blades.
• One of the techniques for obtaining the blank consists, as in EP992305, of using a rotatable mold around an axis (A), for the centrifugal casting process, of an alloy, the mold comprising:
• a (first) problem to be solved concerns the control of the cooling rate in order to favor obtaining a controlled microstructure, such as a level of homogeneous aluminum in the part, especially if the alloy is based on TiAl.
• the present invention overcomes at least some of the aforementioned drawbacks simply, efficiently and economically. For this purpose, it proposes that, transversely to the radial direction (B) according to which each liner extends, a space exists peripherally between said liner and the surrounding exoskeleton.
• the mold will comprise a central block presenting ducts through which the alloy will flow and which will communicate with the inside of the shirts, a removable fastener then being established between each jacket and / or the surrounding exoskeleton and the central block.
• the shirts can be changed at a lower cost, while the rest of the mold structure, particularly the exoskeleton (s), can be preserved.
• the exoskeleton (s) and the shirts be designed so that the mold is permanent, the shirts thus having to hold several castings in succession (for example approximately 25).
• the mold liners which then contain such cast metal TiAl alloy, be steel, metal alloy and / or ceramic, and are therefore suitable for that there is centrifugally cast said molten alloy.
• At least one thermally insulating structure extends peripherally between each liner and the surrounding exoskeleton.
• each exoskeleton may have a very simple shape, not or little worked for this desired control of thermal inertia, and all the more so if said thermally insulating structure is alveolar.
• thermal inertia if said thermally insulating structure is alveolar.
• such a solution by its structure in boxes, typically will promote the resistance to mechanical forces, and in particular the retention of shirts during centrifugation.
• the structure in question defines at least part of said centering means which therefore position the shirt in relation to the exoskeleton.
• the modular nature of the molds will be favored, so that the jacket, the honeycomb and / or thermally insulating structure surrounding it and the exoskeleton surrounding said structure are three separable elements between them, the jacket and the thermally insulating structure being engaged in the exoskeleton, concentrically.
• FIG. 1 is a schematic front view of a solid cylindrical bar of the prior art, in which are intended to be machined turbomachine blades,
• FIG. 2 is a schematic view of a mold of the prior art
• FIG. 3 is a diagrammatic view from above of a shirt and exoskeleton mold in which bars having less segregation will be molded
• FIGS. 4,5,6,7,8,9,10,11,12,13,14,15 schematize folders and exoskeletons according to various embodiments, in front view (FIGS.
• FIG. 4 longitudinal schematic sections (one of the radial axes B; FIGS. (FIG. 5 - view along V- and FIGS. 8, 9, 10), FIG. 13 being a detail of an alternative embodiment of zones identical to that referenced XIII FIG. 12.
• Figure 1 shows a rod 11 made of metal foundry and wherein are intended to be machined at least one blade, here two blades, 12 of a turbomachine turbine.
• the bar 11 may have a cylindrical shape and is full. It is obtained by casting a metal alloy in a mold.
• FIG. 2 shows a conventional device for manufacturing bars or blanks 11, by successive operations of casting, casting and molding.
• the device 10 comprises a closed and sealed enclosure 120 in which a partial vacuum is applied.
• the mold 13 makes it possible to cast the alloy by centrifugation, in order to obtain bars 11. For this, it is rotated about a vertical axis A.
• the mold 13 comprises several housings 17, for example cylindrical of circular section, which extend radially (axes B1, B2, FIGS, 2, 3) about the axis A, preferably via a motor 18. These cavities are preferably regularly spaced angularly about the axis A which is here vertical. The centrifugal forces generated by the rotation of the mold force the molten alloy into these dwellings and fill them. Thus, the casting alloy, brought to the center of the mold, is distributed to the cavities.
• the mold 13 is disassembled and the molded bars 11 are extracted.
• the walls of the mold surrounding the recess 17 of the metal have significant thicknesses to withstand centrifugal forces, typically more than 10 g.
• the invention makes it possible to provide a solution to the cited problem of segregations and, if necessary, to meet the requirements of resistance to centrifugal forces and rapid and frequent change of at least part of the mold.
• FIGS. 4 to 15 show embodiments of a mold 130 according to the invention, it being specified that FIG. 5 and following schematize variants of shirts and exoskeletons that can replace those shown in FIG. 4 around the central block 131.
• FIG. 5 As to all the functional means of which these mold embodiments are preferably provided, they have not been illustrated or systematically taken into account in all the variants described below, so as not to overload the figures or make the following tedious. Nevertheless, the particularities of these embodiments can be combined and applied from one mode to another.
• the mold 130 differs from the mold 13 in the realization of some of its structural means, in particular its radial receiving housing of the alloy. Specifically, around the central block 131, by the bent inner ducts 132 from which the alloy is caused to be distributed radially around the central vertical axis A, are regularly spaced shirts 135 (or for example 135a, 135b Figure 4) which together define the aforementioned dwellings.
• the ducts 132 open respectively into radial ducts 133 which receive the alloy through an opening 133a and each extend inside one of the jackets, in a radial direction B.
• the opening 133a of each jacket is thus located in the radially inner end portion 134a of the duct concerned.
• the shirts which are thus hollow, are arranged in at least one exoskeleton 137, and preferably in as many exoskeletons as there are shirts, each exoskeleton then containing a jacket 135 defining one of said housings.
• the exoskeleton (s) retain the jackets with respect to the centrifugal forces generated by the rotation of the mold. Preferably, they will promote (or at least do not hinder) a limitation of the thermal inertia.
• the central axis A of rotation of the mold is vertical and both the shirts 135 and the exoskeletons 137 each extend along a horizontal longitudinal axis (axis B).
• each duct 133 has a solid bottom 135c.
• each exoskeleton 137 has, at its radially inner end, an opening 137a through which, for example, a liner 135 can pass and, at its radially outer end, a bottom 137b which can participate in the radial retention of the liner.
• FIG. 4 also shows that removable fasteners, such as 141 a, 141 b, are provided between each jacket (and / or the surrounding exoskeleton, references 142a, 142b) and the central block 131.
• the removable fasteners established between shirts and exoskeleton (s) and / or between the central block 131 and shirts and / or exoskeleton (s) may form thermal break zones.
• the exoskeleton (s) is / are made of mild steel, steels or alloys that are more or less refractory and the sheaths are made of mild steel, steels or alloys that are more or less refractory and / or ceramic.
• peripheral wall is referenced 135d and there is seen in the center, the molded bar (blank) 110 from the casting.
• FIG. 8 illustrates a solution where the schematized exoskeleton 137a is provided with a movable door 143a which, in the open position, releases an opening 145 allowing it to pass therethrough (here laterally with respect to the radial axis B ) the shirt considered here 135a.
• Hinges such as the one identified 147a, may facilitate the operation of each mobile door and thus for example the extraction from its exoskeleton of a used shirt and the introduction of another, in better condition, replacing.
• a void space 155 exists peripherally (around the axis B) between each jacket, such as 135a, and the exoskeleton, such as 137a, which surrounds it.
• Centering means 157 position, in a fixed manner during the centrifugation, the liner in question relative to the exoskeleton, for casting (see FIG. 5).
• FIGS 9.1 0 illustrate yet another solution where the shirts are individually formed of several shells, such as 150a, 150b for the shirt 135a schematically.
• the respective inner surfaces of the shells define at least the major part of the cast bar 110.
• these shells open and close along a joint surface of the shells, such as the joint plane 152.
• one of these shells can constitute a movable or removable door vis-à-vis the other, to unmold the piece.
• a separable attachment 153 such as a latch, is established between the shells for, once the shells are separated, to be able to pull the bar 110 from the inside of the liner, here 135a, considered, through the opening 154 released.
• a honeycomb structure 159 which extends peripherally between each jacket, such as 135a, and the surrounding exoskeleton, such as 137a, plays this role and thus defines at least part of said means centering 157 above.
• the honeycomb structure 159 may be annular. It can occupy a space between the bottom 135c of the shirts and that 137b of the exoskeleton considered ( Figure12).
• FIG. 13 shows that the jacket considered and the honeycomb structure, such as 159, are in contact by discrete zones, such as 159a, 159b, Rather than in separate rooms, one could provide to realize the liner and the honeycomb structure in one piece ( Figure 13), so that they meet by these discrete zones located at the radially inner end of the walls 161 separating two by two the recesses 163 of the cells, equivalent, in their entirety, to the space 155 above.
• each jacket such as 135a
• said structure 159 which surrounds it
• the exoskeleton such as 137a
• this structure in three distinct elements, dissociable between them, the jacket and the structure being engaged in the exoskeleton, concentrically, thus following a radial B to the axis A.
• the / the exoskeleton (s), such as 137a comprises (individually) a radially outer end 134b (FIG. 14,) towards which the liner 135 is radially supported against a transverse surface 165 of the exoskeleton.
• the transverse surface 165 will preferably be an internal shoulder of the exoskeleton.
• the radially outer end 134b can be opened, the exoskeleton then resembling a structure traversed from one side to the other by at least one passage, where the / each relevant sleeve is received.
• An attached plug 167 (which may be removable) will then plug this radially outer end 134b, in the manner of the aforementioned bottom 135a.
• the / each plug 167 will not penetrate the exoskeleton beyond the transverse surface 165.
• the shirt will not come to bear against it, which is preferable during centrifugation.
• the outer structure, in particular that exoskeleton (s), of the mold may be cylindrical tubular (structure). It will favorably be made of mild steel. Y will thus be slipped axially an insert (the aforementioned folder) of metallic material or ceramic more or less refractory, which may include shells (such as two half-shells) as mentioned above.
• the outer structure ensures the positioning of the mold on the centrifugal casting assembly and the mechanical strength of the assembly.
• a slope of a minimum degree will preferably be provided between the structure and the insert. This will allow the shirt to come in / out along the exoskeleton, along the B axis, while concentrating them coaxially, in contact with each other.
• a detachable fastener will be made (by tightening) between the jacket and the surrounding exoskeleton.
• the interior volume of the shirts 135 can be of simple geometry (cylinder, rectangle, cone or combination) or complex. In general, any demoldable shape according to the closure plane of the half-shells is a priori acceptable.
• the shirts each have at least one thickness which varies along said radial direction (length L) and which is, at least globally, smaller towards at least one of the radially inner and outer ends, 134a, 134b, than in the intermediate part, as shown in FIGS. 14 ,; see also thicknesses e1, e2 and e3.
• Figure 14 show the interest in having a mold where, individually, the radially inner end 133a of the central duct 133 of casting of the alloy of all or part of the shirts 135 would have a shape 169 thus narrowing in section towards the center of the jacket, along the radial direction B, according to which the corresponding jacket extends.
• the form 169 can thus be single or double funnel (head to tail).
• a truncated cone might be suitable.
• this funnel / chute shape will not necessarily have a symmetry of revolution.
• the funnel / chute shape may correspond to the heel area of this blade and the end portion 133b enlarged to the zone of the blade. extended foot.
• individually all or part of the shirts 135 may have, transversely to the radial direction B along which they extend, a radial peripheral surface 170 at least locally (or partially) machined, as shown schematically in FIG. 15.
• longitudinal reinforcements 171 may be provided to ensure the rigidity, centering and / or guiding of the liner 135 concerned in the peripheral structure 137.
• the reinforcements are radially protruding relative to the rest of the concerned shirt.
• the reinforcements 171 are radial to the axis of the schematized sleeve and define therebetween several free spaces, or secondary cavities, such as 155a, 155b.
• each liner 135, 135 a. length L or axial dimension (axis B) of between 10 and 50 cm, an outer section (such as an outer diameter) between 5 and 20 cm, an inner section (such as an inner diameter) between 4 and 10 cm and a radial thickness e, e 1. .. between 1 and 10cm, on average at the location of a given section.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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• 2014
  • 2014-01-31 FR FR1450799A patent/FR3017061B1/fr active Active
• 2015
  • 2015-01-29 CA CA2938286A patent/CA2938286C/fr active Active
  • 2015-01-29 BR BR112016017708-8A patent/BR112016017708B1/pt active IP Right Grant
  • 2015-01-29 CN CN201580006754.0A patent/CN106132591B/zh active Active
  • 2015-01-29 JP JP2016549440A patent/JP6495308B2/ja active Active
  • 2015-01-29 EP EP15708562.2A patent/EP3099438B1/de active Active
  • 2015-01-29 RU RU2016131338A patent/RU2687320C2/ru active
  • 2015-01-29 US US15/115,148 patent/US9764381B2/en active Active
  • 2015-01-29 WO PCT/FR2015/050208 patent/WO2015114262A1/fr active Application Filing

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