EP0824981B1 - Process for manufacturing a hollow turbine blade and device used for on-going hot twisting - Google Patents

Description

The present invention relates to twisting equipment hot scalable used in a process for manufacturing a hollow turbomachine blade.

The benefits of using large blades rope for turbomachinery appeared especially in the case of the fan rotor blades of turbojet engines double flow. These blades must meet conditions severe use and in particular have sufficient mechanical characteristics associated with anti-vibration and impact resistance properties of foreign bodies. The objective of sufficient speeds at the end dawn has also led to the search for a reduction in masses. This goal is notably achieved by the use hollow blades.

(b) forgeage sur presse des pièces primaires constituant l'aube par matriçage ;

(c) usinage des pièces primaires ;

(d) dépôt de barrières de diffusion suivant un motif pré-défini ;

(e) assemblage des pièces primaires suivi du soudage-diffusion en pression isostatique ;

(f) gonflage sous pression de gaz et formage superplastique ; (g) usinage final.

EP-A-0 700 738 describes a process for manufacturing a hollow blade for a turbomachine, in particular a blade fan rotor with a large cord. It is known in this case according to a first step (a) to carry out on a computer-aided design and manufacturing / CAD / CAM system a digital simulation, from the geometric definition of a blade to be obtained, consisting of calculating for the parts constituting the blade, on either side of the central fiber, the lengths of the fibers as a function of their position relative to the axis of the part, the parts being laid flat. At this stage, we also carry out a numerical simulation of an operation for shaping parts by twisting to compare with the final result. The known manufacturing process according to EP-A0700 738 provides for the general operating procedure according to the following steps:

(b) forging on the press of the primary parts constituting the blade by stamping;

(c) machining of primary parts;

(d) depositing diffusion barriers according to a predefined pattern;

(e) assembly of the primary parts followed by welding-diffusion under isostatic pressure;

(f) inflation under gas pressure and superplastic forming; (g) final machining.

One of the aims of the invention is to make it possible to carry out course of the operative flow above an operation additional shaping of parts by twisting without risk of causing buckling type ripples according to the central fiber. These ripples are generated by compression stresses induced during elongation of lateral fibers due to differences in length between the starting flat part and the obtained twisted part.

The method of manufacturing a hollow turbomachine blade comprising an operation in accordance with the invention of setting workpiece shape using twisting equipment evolving hot according to the invention avoids the disadvantages of prior known methods and obtaining blades having geometric characteristics and improved and optimized mechanical conditions of use, guaranteeing repetitive quality while facilitating manufacturing conditions at the lowest cost.

The method of manufacturing a hollow turbomachine blade according to the invention includes a twist operation hot-swappable, of an element intended for the manufacture of the blade by the hot twist of said alloy element TA6V type titanium, at a temperature above 700 ° C by the action of several bars animated by a movement of rotation around the twist axis and acting on shackles, previously fixed on the element, distributed according to the predetermined twist law, the distribution and number of shackles are determined so as to obtain between each yoke a linear evolution of the twist.

It is known to obtain a workpiece twist and in particular of a turbomachine blade using means making call for at least one rotating jaw with or without prestressed and hot or cold and in particular by a setting in creep form at 950 ° C, in the case of an alloy blade of titanium of type TA6V, on an impression under the action of masses attached to the ends of the part creating a torque.

These known means however prove to be unsuitable for very progressive twists encountered in the process of manufacture of a hollow turbine engine vane with a high rate of compression in the bottom region of the blade according to the invention.

Hot-swappable twist equipment for manufacture of a hollow turbine engine vane with a high rate of compression in the lower blade area is characterized by metal frame on which is vertically fixed a cylindrical oven with slots allowing the passage of bars, of a circular frame enveloping said oven, of free crowns rotating around the frame on which are fixed the bars acting on clamped shackles on the element to be twisted.

• la figure 1 représente une vue en perspective de l'ensemble soudé de l'aube creuse après vrillage à chaud ;
• la figure 2 représente un exemple de courbe d'évolution du vrillage en fonction de la hauteur de l'aube et la position des carcans ;
• la figure 3 représente selon une vue schématique en coupe d'un équipement de vrillage évolutif à chaud ;
• La figure 4 représente selon une vue schématique une coupe horizontale de l'équipement de vrillage évolutif à chaud ;
• la figure 5 montre un détail de l'équipement de vrillage représenté sur les figures 3 et 4.

Other characteristics and advantages of the invention will be better understood on reading the following description of an embodiment of the invention, with reference to the appended drawings in which:

• FIG. 1 represents a perspective view of the welded assembly of the hollow blade after hot twisting;
• FIG. 2 represents an example of a curve of evolution of the twist as a function of the height of the blade and the position of the shafts;
• Figure 3 shows in a schematic sectional view of a hot twisting twisting equipment;
• Figure 4 shows in a schematic view a horizontal section of the hot twisting twisting equipment;
• FIG. 5 shows a detail of the twisting equipment shown in FIGS. 3 and 4.

We will call element intended for the manufacture of a blade hollow turbomachine fan such as 1, shown in FIG. 1 at an intermediate stage of manufacture, in the preferred application which is made of the invention, either a primary forged skin intended to constitute the dawn pressure surface or pressure surface, a sheet central intended to form the stiffeners connecting the skins intrados and extrados of dawn, a welded assembly comprising the outer skins and at least one central plate of dawn, a welded assembly with a skin lower surface and upper surface skin. In the description that goes follow, the nonlimiting example retained concerns a set welded 1 in a step of manufacturing a hollow blade of large-rope blower for a turbomachine, this example corresponding to advantageous economic conditions of application of the invention.

The process for manufacturing a hollow turbine engine blade 1 comprises in accordance with the invention, an operation remarkable hot twist of the welded assembly 1 made of titanium alloy, of type TA6V consisting of hot twist of the welded assembly at a temperature between 700 and 940 ° C, by the action of several bars, integral with crowns driven by a frame circular with a rotational movement around the axis of the element, said bars acting on shackles flanged on the element.

Depending on the final blade shape result to be obtained depending on the specific applications, the operation of Scalable hot twist can be preceded by a bending operation including the shaping of dawn sections.

According to the same criteria of particular application and final dawn shape results in getting the operation of scalable hot twist can be followed by an operation inflation under gas pressure and superplastic forming ensuring the desired profiles of dawn.

Alternatively, after the scalable hot twist operation a complementary operation of shaping by twisting and calibration may be required.

The hot-swappable twisting equipment shown on the Figures 3 and 4 is used for carrying out the operation twisting of the hollow blade element 1 of a turbomachine in the manufacturing process according to the invention and which comes to be described.

This hot-swappable twisting equipment consists of three separate parts: an upper part mainly intended for blocking one end of the part 1 by two jaws 3, in order to ensure immobilization in rotation and keeping in an upright position, part central unit equipped with an electric oven 2, a frame circular 6 mobile in rotation around the workpiece axis acting on free crowns 7 rotating around the frame, distributed vertically along the height of the element to be twisted and a lower part whose function main is to block the other end of element 1, to ensure during a twist a constant distance between these two ends by a tensile force supplied by means a cylinder 8 limited in its stroke by a ball bearing 9 and the transfer of part 1 from the loading station to inside the oven 2.

Said central part composed of an electric oven circular 2 capable of a temperature range included between 700 and 940 ° C, have slots 24 intended for passage of bars 5 integral with crowns 7 whose purpose is to act on shackles mounted on the part and visible in Figure 4. Metal screens filled with material fibrous seal the oven to the right of the slots. A circular frame 6 of tubular mechanically welded construction is rotated by an electric motor 10 to variable speed by means of a ring gear 11 fixed to the upper end of the frame 6. The frame 6 is connected to the metal structure 12 of the equipment by connections to rollers 13, and has as many crowns 7 as necessary according to the law of evolution of the twist, said free crowns 7 rotating around the frame are connected to it by means of roller connections 14. Frame 6 and the crowns 7 are also fitted with drive stops 1516, positioned to apply the twist value required on each yoke. The upper part of the oven incorporates clamping jaws 3 from one end of the part 1 and also allows the passage of the guide rod 25 connecting the jaws with the metallic structure 12.

The upper part is mainly intended for clamping from one end of part 1 to be twisted. The rod 25 water-cooled ensures the guidance and connection of the jaws of clamping 3 adapted to the shape of the part 1 with the structure 12 of the equipment. A blocking system by corners 22 shown in more detail in Figure 5 allows position and immobilize the part 1 in a fixed position while allowing vertical translation of the part 1 of the oven 2 to the loading / unloading station located under the oven.

A counterweight system allows the balancing of this together in order not to constrain the element to unloading.

The lower part intended for the transfer of the loading / unloading to oven 2 also ensures clamping function of the other end of element 1 to by means of two jaws 4, free to rotate, extended by a rod 20 guided vertically by a sleeve 18 integral with a carriage 17 with vertical translation provided by the jack 19. In addition, the carriage 17 is equipped with a stop system at balls 9 and a jack 8 in order to apply a force of traction to element 1 so as to maintain a distance constant between jaws 3 and 4 high and low. The cylinder 8 also absorbs the effects of expansion of room 1 during heating.

Shackles made up of mechanically welded mechanical parts are clamped on the workpiece in positions defined by law evolution of the twist. A preparation table allows position them perfectly on the element. In an example Figure 2 shows the determined positions A, B, C, D, E of the shafts as a function of the curve evolution of the twist and these positions are reported on Figure 3.

We will now describe the course of an operation of hot-swappable twist of a welded assembly 1 of blade turbomachine, in accordance with the invention.

The electric oven 2 is maintained at a temperature higher than 700 ° C for an application on an alloy of TA6V type titanium, jaws 3 and 4 are in the low position ready to receive a welded assembly with shackles distributed over the height of the welded assembly according to the law of twisting evolution, as indicated above. As soon as the clamping of the assembly is finished, the carriage 17 transfers to oven 2 to an end position predefined stroke, then the jaws 3 are immobilized by a wedge system 22 shown in FIG. 5. At this stage, the oven doors 21 being closed the welded assembly 1 is kept in oven 2 until it reaches the twist temperature. As soon as the twist temperature is reached the motor 10 drives the circular frame 6 which by means of the stops 15 and 16 distributed according to the angle of twisting to be supplied in turn drives the crowns 7 of which the bars 5 acting on the shackles print to the whole welded 1 the desired twist law, then the frame 6 is driven in the opposite direction by bringing in its race the crowns 7 in the cycle start position. At this point the oven doors open and cart 17 transfers assembly 1 welded to the loading / unloading station.

Claims (8)

1. A process for the manufacture of a hollow turboengine blade, more particularly for a large-chord fan rotor blade, comprising the following steps:

   (a) starting from the definition of a required blade, a CAD/CAM study and the making of a digital simulation of the flattening of the constituent parts of the blade;

   (b) press forging of the primary parts by die stamping;

   (c) machining of the primary parts;

   (d) deposition of diffusion barriers in a predetermined pattern;

   (e) assembly of the primary parts followed by diffusion welding at isostatic pressure;

   (f) pressurised gas inflation and superplastic forming, and

   (g) final machining,

   characterised in that it also comprises a continuous hot twisting operation on an element (1) to be used for making the blade by hot twisting of said element (1), which is made of TA6V type titanium alloy, at a temperature above 700°C by means of a number of bars (5) rotating around the twist axis and acting on carcans previously secured to the element (1) in a distribution corresponding to the predetermined twist pattern, the distribution and number of carcans being determined so as to obtain a linear development of the twist between the carcans.
2. A process for manufacturing a hollow blade according to claim 1, wherein the twisting operation is performed on each forged primary part.
3. A process for manufacturing a hollow blade according to claim 1, wherein said twisting operation is performed on a flat assembly consisting of the unwelded constituent parts of the blade.
4. A process for manufacturing a hollow blade according to claim 1, wherein said twisting operation is performed on a flat assembly (1) obtained after assembly of the primary parts followed by the diffusion welding.
5. A process for manufacturing a hollow blade according to claims 1 to 4, wherein said twisting operation is preceded by a cambering operation in the connecting zone between the blade root and the bottom aerofoil zone of the blade.
6. A continuous hot twisting device for manufacturing a hollow turboengine blade by the process of claims 1 to 5, comprising a metal structure (12) on which a cylindrical electric furnace (2) is vertically mounted, the furnace being formed with slots (24) for the passage of bars (5), a circular frame (6) extending around said furnace (2), rings (7) which are freely rotatable around the frame (6) and which carry bars (5) acting on carcans attached onto the element (1)to be twisted, jaws (3, 4) disposed at each end of the element (1) and locating the element (1) in the furnace (2) and exerting a continuous pull along the axis of he element (1) during twisting.
7. A continuous hot twisting device for manufacturing a hollow turboengine blade according to claim 6, wherein a system of wedges (22) locates and immobilises in rotation the clamping jaws (3) of the top part and releases them during transfers.
8. A continuous hot twisting device for manufacturing a hollow turboengine blade according to claim 6, wherein the penetration of the rods (5) into the furnace is adjustable.

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