RU2477191C2 - Method of making hollow blower blade - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of aircraft engines and may be used in making gas turbine blower blade composed of shin titanium alloy and filler. In compliance with this method, diffusion welding is used to joint skins and filler together while superplastic forming is used to form hollow root and stiffness ribs. Note here that adhesion between skins and filler and protective coating is broken before making aerofoil of one-piece structural blank. Note also that adhesion is broken in arranging said blank so that adjacent surfaces of skin and filler blanks stay in horizontal plane. Prior to making aerofoil of one-piece structural blank, its cavities are subjected to evacuation and filling with inert gas to remove oxygen therefrom. Then, said cavities are sealed.

EFFECT: expanded machining performances, higher quality due to application of blanks with sub micro crystalline or nano crystalline structure.

8 cl, 5 dwg, 2 ex

Description

The invention relates to the field of metal forming, and more particularly, to methods for manufacturing a hollow fan blade of a gas turbine engine (GTE), consisting of casing and aggregate made of a titanium alloy. The method involves the use of diffusion welding to connect the skin and aggregate and superplastic molding to form a hollow pen and stiffeners.

The inventive method can find application in aircraft engine manufacturing. Including the inventive method can be successfully used for the manufacture of a hollow blade of a high-speed axial fan having a complex aerodynamic profile, which is described in the description given in [1]. The profiles of the cross sections of the scapula are located along its height so that the centers of gravity of the profiles in the meridional plane are on a curved line that has a forward extension in the peripheral part and a bulge in the middle part. In this case, the leading edge of the blade has a reverse sweep in the peripheral part and balancing its bulge in the middle part of the leading edge of the blade, eliminating the appearance of a bending-twisting flutter at the calculated rotational speed of the impeller. The shape of the curve of the position of the centers of gravity of the profiles of the cross sections of the scapula in the meridional plane is determined by the cubic polynomial:

where C ₁ is a constant for a member of the third degree and is in the range equal to -2.08 ÷ -1.78; C ₂ is a constant for a term of the second degree and is in the range equal to 2.95 ÷ 3.05; C ₃ is a constant for a term of the second degree and is in the range equal to -1.21 ÷ -1.11; r _W is the radius of the sleeve of the working blades; r _per - the radius of the periphery of the working blades; r _ct is the radius of the center of gravity of the profile of the current flat section of the working blade; X _ct is the coordinate of the center of gravity of the current profile of the flat section of the scapula; X _W is the coordinate of the center of gravity of the sleeve profile of the working blade, and the aerodynamic profile of the cross section of the working blade is formed by a rarefaction line and a pressure line covering the middle line of the profile of the working blade, curved from the input structural angle β ' _{1 of the} profile of the working blade to the output structural angle β' ₂ profile of the working blade, and is determined by the ratio

where β ' ₁ is the structural angle of the midline of the profile of the working blades; β ' ₁ - input structural angle of the profile of the working blades; β ' ₂ - output structural angle of the profile of the working blades; l is the length of the midline of the profile of the working blade; m is the exponent at the ratio (Δl / l) determines the position of the maximum deflection of the midline of the blade profile and is selected from the condition of ensuring a smooth increase in the pressure gradient on the surface of the working blade, for m> 1.0.

In accordance with the shape of the curved midline of the blade profile, the rarefaction line of one blade and the pressure line of the adjacent blade form the configuration of the flow path of the interscapular channel, which ensures smooth braking of the supersonic flow in the system of weak oblique shock waves with the formation of a closing shock wave in the output part of the interscapular channel. As a result, pressure loss during braking of the supersonic flow is reduced, the efficiency of the fan and the margin of its gas-dynamic stability are increased.

The line of rarefaction and the line of pressure lie on surfaces called the back and trough of the scapula, respectively.

The difference between the input structural angle β ′ _{1 of the} profile of the working blade and the output structural angle β ′ _{2 of the} profile of the working blade is provided during manufacture by twisting the pen [1].

The blade in question has a number of undeniable advantages regarding aerodynamic performance. But when trying to manufacture a hollow blade having such a complex aerodynamic profile, problems arise that are discussed in detail below, which can be solved using the present invention.

In addition, in the manufacture of a hollow blade, there has been a tendency toward the use of initial blanks, at least aggregate blanks with as finely grained structure as possible, namely with a submicrocrystalline (SMC) or nanocrystalline (NC) structure [2]. The use of blanks with QMS or NK structure will improve the operational characteristics of the blades. The operational characteristics of the blades are largely determined by the quality of the connection of the aggregate with the casing obtained by diffusion welding. The use of at least a filler blank with NK or SMK structure will significantly improve the quality of the connection of the filler with the casing. Currently, the grain size in the filler blank varies within 5 ... 10 microns [3].

However, when trying to use a filler blank with a QMS or NK structure in the manufacture of a hollow blade, problems also arise which, along with the problems associated with the profile of the blade, can be solved using the present invention.

Thus, an object of the present invention is a method for manufacturing a hollow fan blade having a complex aerodynamic profile, characterized by relations of type (1) and (2). Further, for brevity, we will call such a blade an improved hollow blade.

Another object of the invention is a method for manufacturing a hollow blade, including an improved hollow blade, using a filler blank with a QMS or NK structure.

One of the main technological operations in the manufacture of a hollow blade, as already noted, is diffusion welding. In this case, the blanks of the skin are connected to the pre-shaped part intended for fastening the blades on the disk of the impeller, in particular in the form of a lock, and a sheet blank of the filler. The blanks are connected in strictly defined areas so that during molding a given configuration of stiffeners is obtained. A protective coating is applied to other sections of the workpieces, which prevents the connection of the workpieces during diffusion welding. Another main operation of the method for manufacturing a hollow blade is superplastic molding, as a result of which stiffening ribs and the final profile of the hollow feather of the blade are formed. Equally important is the operation to give the blanks an aerodynamic profile, carried out under conditions of hot plastic deformation, including the formation of a back and trough of the blade and twist of the blade feather [4, 5, 6].

Consider the known methods in more detail.

A method of manufacturing a hollow fan blade of a gas turbine engine [4] includes the following operations:

- hot stamping of the blanks of the skin and aggregate with the preliminary formation of the lock and feather of the blade, as well as giving the blanks an aerodynamic profile, including the formation of the back and trough of the blade and twist of its feather;

- machining by cutting the blanks of the casing with the design of the sections to be joined in the form of protrusions with a flat surface in cross section and the sections not to be joined in the form of grooves, while at least part of the surface of the grooves opposite in assembled for diffusion welding the package protrusions, perform in a flat cross section;

- assembly of the sheathing and filler preforms into a bag and diffusion welding of the sheathing and filler preforms, with a protective coating being applied to the surface of the sections of the sheathing blanks not being joined, that is, into the grooves;

- the formation of a hollow pen and stiffeners by superplastic molding by supplying a working medium under pressure into the internal cavities of an integral structural billet obtained by diffusion welding.

In combining the methods of forming the necessary supply of material in the area of the paddle blade and giving each blank individually an aerodynamic profile, there is a certain technological expediency, which consists in eliminating the need to have special equipment for performing the operation of imparting an aerodynamic profile to an integral structural blank obtained by diffusion welding.

However, the combination of these operations entails the complexity of the method, in particular the application of a protective coating on the curved surfaces of the blanks of the skin, despite the presence of grooves, is a rather time-consuming operation. The time-consuming is also the mechanical processing of the curved surfaces of the blanks of the skin to form grooves and protrusions on them.

A method of manufacturing a hollow fan blade [5] allows to a certain extent to eliminate the disadvantages inherent in the method [4], since in the method [5] the aerodynamic profile is already attached to an integral structural blank.

Accordingly, the method [5] includes the following basic operations:

- machining by cutting the blanks of the casing with a pre-formed lock and feather, in which on the flat surface they form the areas to be joined in the form of protrusions with a surface flat in the cross section and the parts not to be connected in the form of grooves, with at least at least, the part of the grooves surface, opposite to the protrusions assembled for diffusion welding, is performed in a flat cross-section;

- assembly of the sheathing and filler preforms into a bag and diffusion welding of the sheathing and filler preforms, with a protective coating being applied to the surface of the sections of the sheathing blanks not being joined, that is, into the grooves;

- giving the integral structural blank an aerodynamic profile by applying a deforming load to it, including the formation of the trough and back of the scapula and the twist of the feather of the scapula;

- the formation of a hollow pen and stiffeners by superplastic molding by supplying a working medium under pressure into the internal cavities of the integral structural billet.

In addition, in both known methods [4, 5], a separate operation is also necessary to break the adhesive bond between the protective coating and the workpieces that occurs during diffusion welding under the influence of applied pressure. It is erroneous the opinion noted in the method [5] that the adhesion bond can be broken at the initial stage of superplastic forming, since there is a risk of damage to the whole structural workpiece. The possibility of the risk of damage to the integral structural preform is noted in the description of the method for manufacturing a hollow fan blade [6], and its causes are disclosed and explained later in this description when analyzing the features of the method [6].

Since in the method [5] machining by cutting to form grooves and protrusions undergoes the flat surfaces of the skin blanks, the complexity of the method is somewhat reduced, but nevertheless remains at a sufficiently high level, which does not significantly reduce economic costs. In addition, in both known methods [4, 5], if isostatic pressure is applied to the billet package during diffusion welding, wave-shaped folds are formed on the outer surface of the skin blanks, the depth of which depends on the height of the protrusions / depth of the grooves. It is recommended to apply pressure to the bag only from the side of the sheathing blank forming the back of the blade. In this case, the folds can be smoothed out during molding [5].

A known method of manufacturing a hollow product [6], at least two workpieces, while at least one of the workpieces must be made of metal or alloy having the ability to superplastic deformation, also involves the use of diffusion welding to connect the workpieces and superplastic molding for the formation of stiffeners.

In the manufacture according to the method [6] of a hollow fan blade of a gas turbine engine, the blanks of two skins and a filler are made of a titanium alloy. A protective coating is applied to the surface of the sections of the skin blanks and / or aggregate blanks that are not subject to bonding during diffusion welding. Collect the blanks of skin and aggregate in a bag, seal the bag at the edges, excluding the installation location of at least one tube, then connect the tube to obtain a sealed bag. The cavity of the package is successively evacuated and filled with an inert gas to remove oxygen from them. By heating the packet, the binder of the protective coating is removed (evaporated) from its cavities by continuously evacuating the cavities of the packet. Next, heat the bag and carry out diffusion welding of the workpieces. The aerodynamic profile, including the formation of the trough and the back of the blade and the twisting of the feather of the blade, is imparted to the integral structural billet obtained after welding by means of hot deformation. After giving the integral structural preform an aerodynamic profile, a working medium is fed into its cavity for the operation of breaking the adhesive bond between the preforms of the skin and the filler and the protective coating, which is formed during diffusion welding in areas not subject to connection, by creating a pressure in the cavity sufficient for elastic deformation of the preforms . The whole structural billet is heated and a working medium is fed into its cavity to create the pressure necessary for superplastic molding to obtain a hollow blade pen and formation of stiffeners. Before the operation of superplastic forming, the cavities of the whole structural billet are also successively evacuated and filled with an inert gas to remove oxygen from them.

In other words, the sequential evacuation and filling with inert gas of the cavities of the package or of the integral structural preform is intended for their purification from oxygen.

In addition, before diffusion welding and superplastic forming operations, sequential evacuation and filling with inert gas of the cavities of the package and the integral structural billet, respectively, to remove oxygen from them is carried out repeatedly.

Inert gas is filled in the cavities of the bag and the integral structural blanks under pressure that reaches atmospheric pressure. At least one tube mounted on the edge of the bag is used to perform evacuation and supply of inert gas in the cavity of the bag and the integral structural blank. More than one tube may be required. In particular, two tubes can be installed for each pair of adjacent surfaces of the workpieces to be joined. In addition, for supplying an inert gas used as a working medium in the cavity of an integral structural preform during superplastic molding or for breaking the adhesive bond between the preforms and the protective coating, as well as for cleaning the cavities, various tubes may be required. At the end of the manufacturing process of the blade, all tubes are dismantled, and the holes remaining after this are sealed.

In this method, diffusion welding is carried out under conditions when the surfaces of the skin blanks adjacent to the surface of the aggregate blank are flat over the entire area. The absence of the need to perform protrusions on the surface of the blanks of the skin significantly increases the efficiency of the method [6]. In the absence of protrusions, diffusion welding can easily be

carried out under isostatic pressure, for which it is most expedient to use a gas thermostat, which also increases the efficiency of the method [6]. To carry out the operation of imparting an aerodynamic profile to a solid structural blank, a special device can be used, which is described in the patent description [7]. In some cases, it may be necessary to complete the spin process with correcting the shape of the bent solid structural workpiece in accordance with the given shape of the stamp used in the superplastic molding process. In this case, a stamp of a hot plastic deformation press is used, which contacts a solid structural billet only in technological zones, that is, in those zones that will be removed in the future. Alternatively, the final spinning step can be carried out using a die intended for superplastic forming.

The known method [6] for a long time has been quite successfully used for the manufacture of a hollow fan blade, so it is selected for the prototype of the proposed method.

Here it is necessary to avenge that the method [6] was created during the existence of the previous generation gas turbine engine with a fan, the blades of which, in contrast to the improved blade, are characterized by a rather simple aerodynamic profile [6, Fig. 1]. In this case, the grain size in the filler blank varies within 5 ... 10 microns [3].

When trying to use the prototype method for the manufacture of an improved hollow blade, as noted above, a number of problems arise. Problems also arise when using a filler blank with a QMS or NK structure. To clarify the causes of these problems and ensure the possibility of their resolution, a deep study of each of the operations of the prototype method was carried out [6]. In addition, tests and comprehensive control were carried out, including destructive testing after diffusion welding and superplastic molding operations, prototypes of blade simulators made by known methods, including the prototype method, as well as the claimed method.

As a result of studies, it was found that in the manufacture of an improved hollow blade, as well as when using a filler blank with NK or QMS structure, the conditions for the operation of breaking the adhesive bond between the workpieces and the protective coating in areas that are not subjected to bonding after imparting an integral structural blank are unfavorable aerodynamic profile. However, in the description of the prototype method, it is noted that the implementation of the rupture of the adhesive bond before giving the integral structural blank an aerodynamic profile can lead to a violation of the structural integrity of the product.

First of all, it is necessary to find out why in the manufacture of a hollow blade, a separate operation for breaking the adhesive bond between the workpieces and the protective coating is necessary and what is the reason for the strength of this bond. On the one hand, as noted in the description of the prototype method, the integrity of the protective coating after removal of the binder from it can be easily violated. Violation of the integrity of the protective coating before diffusion welding can lead to the connection of the blanks of the skin and aggregate in areas where there should not be a connection between them. The ingress of particles of the protective coating on the joints can lead to the appearance of lack of penetration in the joint zone. In both cases, irreversible defects occur in the manufacture of the blade. Therefore, the assembled package of blanks is transferred to the gas thermostat with great care. Moreover, as an alternative, it is even proposed to leave in the protective coating a predetermined amount of a binder. In this case, the protective coating will be less fragile, so that the assembled package can be transferred to the gas thermostat without violating the integrity of the coating. In addition, during the application of pressure for diffusion welding, the initial uniformity of the thickness of the protective coating may be violated due to the possibility of movement of the coating particles. Moreover, in the gas bath the assembled package can be placed in a vertical position.

On the other hand, which is also noted in the description of the prototype method, if you try to break the adhesive bond between the protective coating and the workpieces at a superplastic molding temperature, there is a serious risk of progressive local plastic deformation of the workpieces. In such cases, a break in the whole structural billet often occurs. The noted circumstance testifies in favor of the strength of the adhesive bond. Given the fragility of the protective coating and the possibility of a slight violation of its integrity, the strength of the adhesive bond can be explained by only one reason. Namely, due to the application to the workpieces of a significant pressure during diffusion welding in areas where the workpieces of filler and sheathing cannot be joined, an inevitable violation of the integrity of the protective coating and microscopic size exposure of the workpieces occur at the vertices of individual microprotrusions. As a result, separate microscopic “bridges” also arise, connecting the blanks of the skin and the aggregate. And even if these “bridges” are micron in cross section, elastic deformation of the workpieces becomes necessary to break the adhesive bond between the workpieces and the protective coating. Thus, the bond in question can only conditionally be called the adhesive bond between the workpieces and the protective coating.

The fact that individual microscopic “bridges” appeared during diffusion welding connecting the skin blanks and aggregate in areas not subjected to joining was confirmed by destructive testing of a simulator made by the prototype method after diffusion welding.

The adhesion bond is broken in the prototype method under the influence of a fixed pressure of the working medium, argon, supplied to the internal cavities of the whole structural billet at room temperature after giving it an aerodynamic profile. At the same time, argon is carefully introduced from one end of the integral structural billet into those zones where there is a protective coating. Argon seeping through the protective coating reaches the opposite end of the solid structural billet. You can skip argon first between the blanks of one sheathing and aggregate, then he, having reached the opposite end of the integral structural blanks, will return to the input, passing between the blanks of another shelling and aggregate. This operation is performed at room temperature, since the deformation of the preforms taking place does not extend beyond the elastic region. From the same considerations, a fixed value of the argon pressure supplied to the internal cavities of the integral structural billet is also selected. Since the blanks of the skin in the part undergoing elastic deformation have a variable thickness, decreasing from the lock to the periphery of the pen, the pressure value is selected taking into account the maximum thickness of the blanks of the skin.

When using both argon transmission schemes, the skin blanks, elastically deformed, diverge to the sides relative to each other, being released from the adhesive bond with the protective coating. In this case, the thin filler blank is subjected to elastic bending and stretching. Here it is necessary to note the fact that the elastic deformation of the sections of the sheathing preform forming a trough, where the convexity is opposite to the direction of the acting forces, turns out to be noticeably smaller than the deformation of the corresponding sections of the sheathing preform forming the back of the scapula. From the standpoint of elasticity theory, the stability of the marked sections of the sheathing blank forming the trough of the blade under the influence of argon pressure can be considered as the stability of a shallow shell under the influence of an external uniformly distributed load [8]. Due to the stability of the marked sections of the sheathing blank forming the trough of the blade, the elastic deformation may not be sufficient to break the adhesive bond, and there is a need to increase argon pressure. Under such conditions, it is more expedient to use the second scheme for passing argon through the cavities of the whole structural billet, which makes it possible to more objectively judge how fully the process of rupture passes and more accurately determine the amount by which it is necessary to increase the argon pressure.

In the manufacture of an improved hollow blade after twisting the pen by a rather significant angle required to ensure the difference between the output and input structural angles of the aerodynamic profile of the blade (2), a kink of the pen occurs, in the area of which the sections of the skin blanks and the filler acquire a pronounced convexity / concavity. Due to the stability of the sections of the workpieces, convex with respect to the direction of the forces acting at break, their elastic deformation becomes almost impossible. From the standpoint of elasticity theory, the stability of the marked sections of the workpieces under the influence of argon pressure can be considered as the stability of the elliptical shell under the influence of uniformly distributed external pressure [9]. As a result, there is a need to increase the pressure created in the cavity of the integral structural preform in order to break the adhesive bond in the marked areas due to the sufficient deformation of the sheathing preform, which has a concavity with respect to the direction of the forces acting at break, and the aggregate preform. As for the sections of the sheath blank that are convex with respect to the direction of the force acting at break, at any increase in pressure, their stability can only be overcome by changing the shape of the bend [9].

With increasing pressure, the degree of elastic deformation of the sheath blanks and the thin aggregate blanks everywhere increases, and at least in separate sections in separate layers of the aggregate blank, the strain can be transferred from the elastic region to the plastic region. Such a transition during elastic deformation of the filler preform by bending and stretching becomes possible due to a sharp decrease in the yield strength of individual layers of the filler preform, previously subjected to bending in the opposite direction and compression during hot plastic deformation by bending and torsion. The effect of a sharp decrease in the yield strength with respect to stresses of the opposite sign is widely known in the art as the Bausinger effect [8, 10, 11, 12, 13]. On average, for metals and alloys, a decrease in the yield strength due to the manifestation of the Bausinger effect reaches 50% [8]. The influence of the Bausinger effect must be taken into account when processing metals by pressure, especially when performing sheet stamping processes [12, 13]. In addition, this effect is manifested the stronger, the smaller the grain size in the workpiece [11]. Titanium alloys are most affected by the Bausinger effect. A decrease in the yield strength in a preform of a titanium alloy with a fine-grained structure can reach 80% [10].

In accordance with the last noted circumstance, when using a sheet blank of aggregate with SMC or NK structure, the Bausinger effect can manifest itself even at lower degrees of bending and stretching than those observed in the manufacture of an improved hollow blade, that is, in the process of manufacturing a conventional blade [6 , Fig.1].

The physical nature of the Bausinger effect is explained by the phenomenon of elastic hysteresis due to the presence of residual stresses in the sample after its preliminary plastic deformation [8, 14]. Here objections are possible regarding the formation of residual stresses during hot deformation processing, by means of which the operation of imparting an aerodynamic profile to the blade is carried out. As is known [15], during hot deformation processing, the process of dynamic hardening is followed by the processes of dynamic softening (recrystallization and recovery). However, it is also known that the structure obtained as a result of hot deformation processing depends on at what point in the stress – strain curve the deformation process is terminated. The stress-strain curve has three sections characterized by corresponding degrees of deformation. The first section, characterized by small degrees of deformation (relative deformation up to 10%), reflects an increase in the dislocation density and the formation of the substructure necessary for further deformation. The third section, characterized by degrees of deformation of more than 50%, corresponds to stabilization of the structure. The transitional second section is characterized by voltage fluctuations [15]. When forming the profile of the blade, the degree of deformation of the workpieces, including the workpiece of the aggregate and its individual layers, do not go beyond the first section of the stress-strain curve.

After the operation of imparting an aerodynamic profile to the integral structural billet, there is no heat treatment operation for the time required to relax the stresses and reduce the influence of the Bausinger effect [8, 16]. In addition, the implementation of heat treatment before the operation of superplastic forming from the standpoint of excessive grain growth, energy costs and increase the complexity is inappropriate.

It should be noted that in the manufacture of an improved hollow blade, the growth of shear stresses during elastic bending can bring a thin preform of a filler or its individual layers to a state “at the yield strength” [17] even without taking into account the Bausinger effect.

Further, as a result of recrystallization during heating under superplastic molding in the local area of the aggregate preform, where at least its individual layers underwent cold plastic deformation, a structure is formed that differs in grain size from the structure of the aggregate preform as a whole. At low strain rates used for superplastic deformation, the flow stresses are largely dependent on the grain size. Therefore, in superplastic molding, the heterogeneity of the structure in terms of grain size will lead to localization of deformation during the formation of individual stiffeners and a violation of the uniformity of the thickness of these ribs, which, in turn, will lead to a loss of their safety margin and bearing capacity. Even the slightest loss of margin of safety and bearing capacity of stiffeners is completely unacceptable for a product such as a hollow fan blade. The presence of such stiffeners was detected during destructive testing of the simulator after the superplastic molding operation, which has a simpler aerodynamic profile than the blade [1], in the manufacture of which a filler blank with a grain size of 0.6 μm was used.

Due to its smallness, the considered defect may go unnoticed, but at the same time it does not become less dangerous.

Thus, in the manufacture of an improved hollow blade according to the prototype method when the adhesive bond is broken after giving the whole structural workpiece a complex aerodynamic profile, there is a risk of the deformation of the layers of the thin filler workpiece from the elastic region to the plastic region due to the Bausinger effect. The Bausinger effect when breaking the adhesive bond can also be manifested in the manufacture of a blade simpler in design using a filler blank with a QMS or NC structure. The end result in both cases there is a risk of the formation of weakened stiffeners in the finished blade. In the manufacture of an improved hollow blade using a filler blank with a QMS or NK structure, the noted risks are summarized.

It should also be noted that there is a large-scale effect, indicating a greater likelihood of technological difficulties or any defects in a larger volume of material [17].

In the method of manufacturing a hollow fan blade, a large-scale effect is manifested with an increase in the chord of the blade.

However, in the description of the prototype method, as already mentioned, it is noted that an attempt to break the adhesive bond before giving the whole structural blank an aerodynamic profile can lead to a violation of the structural integrity of the product. The description of the prototype method does not explain the reasons for a possible violation of the structural integrity of the product, but detailed studies have allowed to open them. The protective coating may include yttrium powder dispersed in a binder, and

solvent. After removing the binder, as already noted, the particles of the protective coating can move even before diffusion welding, which is prevented by careful handling of the package of blanks.

When the adhesive bond is broken, the particles of the protective coating, moving along the surface of areas that are not subjected to diffusion welding, can group and form local clusters, which is facilitated by the location of the workpiece in the process of breaking. In particular, when the whole structural workpiece is positioned vertically when the adhesive bond is broken, this is the most unfavorable case, such accumulations of particles of the protective coating become inevitable. During hot deformation, by bending and twisting, accumulations of particles of harder yttrium will be introduced into plastic preforms, primarily into the aggregate preform. Subsequently, during superplastic molding, sharp local thinning of the aggregate blank and, accordingly, stiffeners will develop in this place, which can lead to its rupture, that is, to the violation of the structural integrity of the finished product noted in the description of the prototype method.

After diffusion welding, the powder of the protective coating is somewhat compacted and is sandwiched between the blanks of the skin and the aggregate, which makes the conditions for the swirling favorable. In the subsequent breakdown of the adhesive bond due to the fact that the protective coating is on surfaces that already have an aerodynamic profile, some movement of its particles occurs, despite the careful introduction of argon into the cavity of the integral structural blank. But this movement, due to its insignificance, which is due to the rather simple shape of the blade pen, in the prototype method is not critical during subsequent superplastic molding, accompanied by the opening of the cavities of the whole structural blank.

In the manufacture of an improved hollow blade in the process of rupture carried out after twisting, the particles of the protective coating due to the presence of pronounced kink of the pen at any location of the integral structural workpiece, despite the careful introduction of argon in its cavity, are actively moving, pouring like in a bowl, to the corresponding sections of the workpieces skins and aggregate. Having coalesced in this way, the particles of the protective coating form a large accumulation of volume, which, after relieving the argon pressure necessary to break the adhesive bond, bulges the skin and aggregate blanks in the elastic region. Such buckling in the elastic region before the superplastic forming operation is now becoming very critical, especially for the filler blank. Firstly, at the initial stage of molding, until the cavities of the whole structural blank are opened, and they open slowly, in the place where there is, it is necessary to emphasize again, a significant accumulation of particles of the protective coating, local plastic deformation of the filler blank will also occur, which in the future, it can also lead to rupture of the stiffeners in the blade. Secondly, during the heating process as a result of recrystallization in the local area of the aggregate preform, where a noticeable largest elastic energy was stored, a structure is formed that is different from the structure of the aggregate preform as a whole. The effect of elastic energy on the recrystallization process in a titanium alloy billet, taking into account the unified nature of metals and alloys, can be judged from the source [18], where the influence of elastic energy on the structure formation during recrystallization in silicon steel is estimated. The fact that the inhomogeneous structure of the aggregate preform leads to a violation of the uniform thickness of the stiffeners and to the loss of its safety margin and load-bearing capacity was discussed in detail above.

Thus, from the considered position, as well as from the point of view of the undesirable manifestation of the Bausinger effect, in the case of manufacturing an improved hollow fan blade using the method [6], the risk of finished product of dangerous defects.

The objective of the invention is to expand the technological capabilities of the method of manufacturing a hollow fan blade, which allows to produce both a blade having a fairly simple aerodynamic profile, and an improved blade characterized by a complex aerodynamic profile.

The objective of the invention is also to improve the quality of the hollow blade due to the use of at least a filler blank with a submicrocrystalline or nanocrystalline structure.

The problem is solved by a method of manufacturing a hollow fan blade of a gas turbine engine, consisting of casing made of titanium alloy and a filler, using diffusion welding to connect the casing and filler and superplastic molding to form a hollow feather and stiffeners, according to which the operations are performed in the sequence noted below consisting in the fact that on the surface of the sections of the blanks of skin and / or blanks of aggregate, not subject to the connection n and diffusion welding, a coating preventing the connection is applied, the blanks of the skin and aggregate are collected into a bag, the bag is sealed at the edges, excluding the installation location of at least one tube, the tube is connected to the bag, the cavities of the bag are successively evacuated and filled with an inert gas to remove from the cavities of the oxygen packet, heat the packet to the temperature necessary for evaporation of the binder from the coating, which prevents the compound, while continuing to evacuate the packet to remove evaporating of a poisonous substance, completely seal the bag by sealing the tube, heat the bag to the temperature of diffusion welding, apply pressure to the bag and perform diffusion welding of the workpieces, perform the operation of breaking the adhesive bond between the workpieces of the skin and the filler and the protective coating formed during diffusion welding in areas not exposed the connection, by creating in the cavities of the integral structural billet pressure sufficient for the elastic deformation of the blanks of skin and spare parts a filler; moreover, during the operation of breaking the adhesive bond, the integral structural preform is positioned so that the adjacent surfaces of the sheathing and aggregate preforms are in a horizontal plane, they are evacuated sequentially and the cavities of the entire structural preform are filled with inert gas to remove oxygen from them, they again completely seal the bag, they heat it and, through hot deformation, attach it to a solid structural billet obtained after diffusion welding, the aerodynamic profile, including the formation of the trough and back of the blade and the twist of the feather blade, heat the whole structural billet to the temperature of superplastic molding, feed the working medium into its cavity to create the pressure necessary for superplastic molding, and carry out superplastic molding to obtain a hollow feather of the blade and formation of stiffeners.

The task is also solved in the following cases when:

- sequential evacuation and filling with inert gas the cavities of the whole structural billet to remove oxygen from them before the operation of giving the integral structural billet an aerodynamic profile is carried out repeatedly;

- use a filler blank with a grain size of less than 1 μm;

- diffusion welding is carried out in two stages, while at the first stage pressure is applied at a temperature below the temperature of the second stage, close to the lower boundary of the temperature range, providing a deformation rate corresponding to the conditions of superplasticity of the aggregate preform, for a time sufficient to form a physical contact between the joined preforms lining and aggregate, and the second stage is carried out at a temperature and for the time necessary for development between the connected workpieces about lazy interaction;

- when using a filler blank with a grain size of 0.6 ... 0.8 μm, the first stage of diffusion welding is carried out at a temperature of 650 ... 700 ° C for 30 minutes, the second stage of diffusion welding is carried out at a temperature of 900 ... 950 ° C for 2 hours;

- use skin blanks whose surfaces adjacent to the surface of the aggregate blank are flat over the entire area;

- on the surface of the sheathing blanks, the sections to be bonded are formed in the form of protrusions, the flat surface of which is adjacent to the surface of the filler blank, and the sections not to be bonded in the form of grooves, in addition, when removing the binder of the protective coating, the package of blanks is placed in this way so that the adjacent surfaces of the blanks of the skin and the filler are in the horizontal plane, maintaining this position of the package before and during diffusion welding;

- pressure during diffusion welding is applied from the side of the skin forming the back of the blade.

The combination and sequence of the above operations of the method provides a solution to the problem and obtain a technical result, which consists in expanding the technological capabilities of the method of manufacturing a hollow fan blade, allowing to produce both a blade having a fairly simple aerodynamic profile and an improved blade characterized by a complex aerodynamic profile described by the relations type (1), (2). The method also allows the manufacture of a blade using at least a filler blank with a QMS or NK structure. The methods of the proposed method can completely prevent the manifestation of physical effects, such as the Bausinger effect or the growth of shear stresses when bending a thin preform aggregate, as well as the movement and pouring of particles of the protective coating with the formation of clusters when the adhesive bond is broken.

The manifestation of the Bausinger effect is prevented, since the operation of breaking the adhesive bond between the blanks of the skin and the filler and the protective coating, accompanied by elastic stretching and bending of the workpieces, is carried out before the operation of giving the whole structural workpiece an aerodynamic profile, and accordingly there is no previous plastic deformation of the workpieces, especially the filler workpiece, the opposite sign.

At the same time, due to the absence of curved surfaces and the location of a solid structural billet when the adhesive bond is broken so that the adjacent surfaces of the skin and filler blanks are horizontal, the particles of the protective coating can be moved and poured off to form their clusters. Directly in the process of breaking the adhesive bond, the particles of the protective coating can move somewhat, however, after depressurization, they will again be distributed fairly evenly, without pronounced accumulations, on the surface of the sections of the workpieces that are not subject to bonding.

When performing the operation of breaking the adhesive bond, argon in the cavity of an integral structural blank must be entered very carefully. The last condition is also observed in the method [6]. In this case, it is possible, as in the method [6], the use of two schemes for transmitting argon through the cavity of a solid structural billet. According to the first scheme, argon is simultaneously introduced into all areas where there is a protective coating. According to the second scheme, argon can be skipped first between the blanks of one sheathing and aggregate, and then between the blanks of another sheathing and aggregate.

When using any scheme in the inventive method, in contrast to the method [6], the blanks of both skins are deformed in the absence of a convex counter to the direction of the acting forces, which is one of the factors preventing the growth of tangential stresses when bending a thin filler blank.

The operation of breaking the adhesive bond, as in the method of [6], is performed at room temperature, since the deformation of the preforms taking place does not extend beyond the elastic region. From the same considerations, the value of the fixed argon pressure supplied to the internal cavities of the integral structural billet is also selected. It should be noted that in the inventive method, the pressure value can be chosen significantly lower than in the method [6], due to the lack of bending of the workpieces counter to the direction of the acting forces, which is also a factor preventing the growth of tangential stresses when bending a thin filler blank.

After carefully breaking the adhesive bond at the required location of the integral structural preform, evacuating and sealing the cavities of the whole structural preform, the protective coating is again sandwiched between the skin and filler blanks. As a result, the conditions for the operation of imparting an aerodynamic profile to the integral structural billet actually become the same as in the method [6]. And, which is especially important, in the manufacture of an improved blade due to the absence of an adhesive bond breaking operation immediately before the superplastic molding operation, the protective coating particles are not able to move and poured into areas where there is a pen bend, which eliminates the inhomogeneous deformation of the filler blank during stiffening in the process of superplastic molding.

In the inventive method, as in the method [6], before the diffusion welding operation, vacuum evacuation and filling with the inert gas the cavities of the bag and the integral structural blank for repeatedly removing oxygen from them followed by vacuum sealing of the cavities are repeatedly performed.

In the inventive method, the noted operation is also carried out before the operation of imparting an aerodynamic profile to the integral structural blank. The latter circumstance, of course, lengthens the technological cycle of manufacturing the product, but it is necessary in order to prevent oxidation of the surfaces of the workpieces during their hot deformation, that is, in general, to solve the problem posed by the invention.

Alternatively, it is possible to reduce the number of operation transitions or the entire operation of sequential evacuation and filling with inert gas the cavities of the whole structural preform before the superplastic forming operation.

During the cleaning process, the cavities of the whole structural billet when filling with inert gas are no longer revealed, since the pressure of the inert gas does not exceed atmospheric pressure. Therefore, the particles of the protective coating are not able to move.

Also, the techniques of the proposed method due to preventing the manifestation of the Bausinger effect will allow the use of a filler blank with QMS and NK structure. This will significantly improve the quality of the connection obtained by diffusion welding, due to a significant difference in the yield strength of the skin and filler blanks. In order to more fully use the advantages of the noted difference in the properties of the workpieces, it is recommended that diffusion welding be carried out in two stages. At the same time, at the first stage of welding, it is recommended to apply pressure at a temperature close to the lower boundary of the temperature range of the superplasticity of the filler preform, for a time sufficient to form physical contact between the joined surfaces of the casing and filler preforms. In the process of physical contact formation at the indicated temperature of the first stage, it becomes possible to slow down and even prevent grain growth in the aggregate preform, and, therefore, to preserve the number and extent of grain boundaries that determine the relaxation ability of the aggregate preform during physical contact formation, as well as to save the noted significant difference in the yield strength of the skin and aggregate blanks and, due to all these factors, significantly reduce the degree of strain hardening Preparations aggregate in formation of physical contact and as a result, improve the quality of the connection.

The second stage is carried out at the temperature and for the time necessary for development when the volumetric interaction between the blanks of the skin and the aggregate is combined. The time of the second stage should be sufficient for the relaxation processes to occur in the workpieces and in the junction zone: recrystallization, equilibration of grain boundaries, formation of common grains in the junction zone, and removal of internal stresses [19].

Also, due to the significant relaxation ability of the numerous grain boundaries of the aggregate preform with SMC and especially with the NK structure, which allows to avoid strain hardening during the formation of physical contact during diffusion welding, it becomes possible to slightly reduce the surface cleanliness of the welded blanks of the skin and aggregate. In the inventive method, this effect, given the significant surface area of the blanks of skin and aggregate, subjected to grinding and polishing, can be considered very significant.

When using a filler blank with a grain size of 0.6 ... 0.8 μm, it is recommended to carry out the first stage of diffusion welding at a temperature of 650 ... 700 ° C for 30 minutes, and the second stage at a temperature of 900 ... 950 ° C for 2 hours. The noted modes were used in the manufacture of scapula simulators. The results obtained in this way confirmed the high quality of the compound obtained by diffusion welding.

When using a filler blank with an even smaller grain size, the recommended modes should be reviewed taking into account the experimental data.

In science and technology, solutions are known [20], involving the use of gaskets with an average grain size of less than 1 μm to improve the quality of the connection obtained by diffusion welding, workpieces with an arbitrary structure. It is also known that when using such a gasket, it is advisable to carry out diffusion welding in two stages [21]. At the same time, at the first stage of welding, it is recommended to apply pressure at a temperature close to the lower boundary of the temperature range of the superplasticity of the aggregate preform, for a time sufficient to form physical contact between the connected surfaces of the preforms. The second stage is carried out at the temperature and for the time necessary for development when the volumetric interaction between the blanks of the skin and the aggregate is combined.

However, in the manufacture of a hollow fan blade, known techniques can only be used in conjunction with the main techniques of the proposed method. At the same time, the effect that is significant and new for the proposed method is that, despite a slight increase in the total time of diffusion welding, the grain size in the filler blank due to its very small initial value at the time of the start of the superplastic molding operation increases to lower values than in method [6]. The aforementioned circumstance makes the conditions of superplastic molding more favorable for shaping by increasing the ductility resource.

From the point of view of the efficiency of the method, due to the exclusion of excessive machining by cutting, as well as the possibility of using a gas bath during diffusion welding, it is preferable that the surfaces of the skin blanks mating with the surface of the core blank, as in the method [6], be flat over the entire area.

However, in the case when there is still a need on the surfaces of the skin blanks to form the areas to be joined in the form of protrusions and areas not to be connected in the form of grooves, in particular, in the absence of technology for applying a protective coating by screen printing, the methods of the proposed method also can be used effectively.

If there are protrusions / grooves on the surfaces of the skin blanks when removing the binder of the protective coating, it is recommended that the package of blanks be placed in such a way that the surfaces of the protrusions are in a horizontal plane, maintaining this position of the bag before and during diffusion welding. This technique is aimed not to damage the protective coating before the operation of breaking the adhesive bond between the protective coating and the workpieces.

Subject to the conditions noted and when using the basic techniques of the proposed method, despite the presence of protrusions / grooves on the surfaces of the blanks of the skin, the possibility of moving particles of the protective coating is excluded.

A finished product made by the claimed method can be any hollow fan blade, even a fairly simple shape, such as a blade, presented in the description of the method [6] [6, Fig. 1].

Particularly successfully claimed method can be used in the manufacture of advanced hollow blades.

It is advisable to use the inventive method in the manufacture of any shape of a hollow blade using the initial blank of aggregate with SMK or NK structure.

In conclusion, it should be noted that in the method [6], if it is necessary to manufacture an improved hollow blade and / or use a filler blank with a QMS or NK structure, it is impossible to prevent the manifestation of physical effects, such as the Bausinger effect or the growth of shear stresses when bending a thin filler blank. Also, in the method [6], if it is necessary to manufacture an improved hollow blade, it is impossible to prevent the inevitable pouring of the particles of the protective coating when the adhesive bond is broken into sections of the workpieces located in the area of the pen bend.

The inventive method of manufacturing a hollow fan blade is illustrated by graphic materials.

Figure 1 presents a schematic illustration of a package of blanks in the process of its assembly before the diffusion welding operation.

Figure 2 shows the cross section of the package of blanks in the case when on the surface of the blanks of the skin made protrusions and grooves.

Figure 3 schematically shows the feather of the scapula after twisting it.

Figure 4 presents the cross section of the pen blades after the operation of superplastic forming and machining.

Figure 5 presents a photo of a simulator of a hollow scapula with a cross section in cross section.

Figure 1 shows the image of a package of preforms during its assembly before the diffusion welding operation in the case when the surfaces of the preforms of the casing 1, 2 are adjacent to the surface of the preform of the filler 3 over the entire area, that is, the surfaces of the preforms of the casing 1, 2 are flat.

On the opposite surface of the blanks of the skin 1, 2 there are pre-formed protrusions 4, 5 under the lock of the blade. In addition, on the same surface of the sheath blanks there are technological protrusions 6, 7 from the side opposite to the one where the protrusions 4, 5 for the paddle lock are formed. Technological protrusions 6, 7 are intended for fixing an integral structural billet obtained after diffusion welding during bending to obtain the trough and back of the blade and twist its feather. Holes 8 for mounting pins 9, 10 are made in the blanks of the skin and the filler. Grooves 11, 12 are made in the blanks of the skin in the part where the padlock will be locked. Slot 13 is made in the blank of the filler, also in the part where the padlock will be locked. Grooves and the slot serve to install the tube 14. Sections 15 of the surface of the blank of filler 3 and the corresponding surface sections (not shown in FIG. 1) of the skin blank 1, as well as sections 16 of the surface of the blank of skin 2 and their corresponding surface sections (in FIG. 1 shown) ovki filler 3 to be joined by diffusion welding. A protective coating is applied to the sections 17, 18 of the surfaces of the blanks of the casing 2 and the aggregate 3 by means of silk-screen printing. The protective coating prevents the marked areas from joining during diffusion welding. The grooves 11, 12 and the slot 13 are made in such a way that they connect the areas that are not subjected to connection on the surfaces of the blanks of both skins and aggregate.

Figure 2 shows the cross section of the package of blanks of the skin 19, 20 and aggregate 21 in the case when adjacent to the surface of the workpiece aggregate are only the surfaces of the protrusions 22, 23, made on the surfaces of the skin 19, 20. A protective coating is applied to the grooves 24, 25. The rest of the package of blanks does not differ from the package of blanks shown in figure 1.

An explanation of how the method is implemented is given in full for the case when the blanks of the skin are flat (Fig. 1), since this case is the most common.

The initial blanks of cladding are taken, which are used as plates or sheets of sufficient thickness for the design of the castle part. The initial blank for the aggregate is a thin sheet.

The initial blanks of the skin and the filler are subjected to machining in order to obtain a predefined shape in the meridional plane, in particular, determined by the cubic polynomial (1). Also, by machining, protrusions 4, 5 are obtained for locking the blades and technological protrusions 6, 7. The surfaces of the blanks of the skin and the aggregate are prepared for diffusion welding by grinding and polishing. Immediately before welding, the surfaces to be welded are chemically cleaned. A protective coating is applied to predetermined sections 17, 18 of the blanks. The protective coating may include yttrium powder dispersed in the binder and a solvent. The protective coating is applied by screen printing. The blanks 1, 2, 3 are collected in a bag and fixed relative to each other using the mounting pins 9, 10. Next, the tube 14 is connected to the bag. The tube 14 is mounted so that the sections of all the blanks which are not to be joined are interconnected. As already noted above, if necessary, you can install several tubes in such a way that each of them will connect areas that are not subjected to connection, on the adjacent surfaces of the blanks of each of the skin and filler. In addition, the tube 14 is installed so that it protrudes beyond the contour of the bag, since then a pipe (not shown in FIG. 1) will be connected to the protruding end of the tube to connect the tube 14 to either a vacuum pump or an inert gas supply system. All three workpieces 1, 2, 3 at the edges are interconnected by argon arc welding. The tube 14 is also fixed by means of argon-arc welding. A sealed assembly unit is created, with the exception of the inlet of the tube 14. The cavities of the bag are evacuated. Then, an inert gas, argon, is supplied to the bag cavities. After feeding argon, the bag cavities are again evacuated, then argon is again fed into the bag cavity. Argon is fed into the cavity of the packet under pressure reaching atmospheric pressure. It is recommended to control the oxygen level in the argon removed during the vacuum process. Repeated sequential evacuation and supply of argon must be carried out until the complete removal of oxygen from the cavities of the package. The specific number of evacuation and argon filling operations depends on the size of the product.

Next, the package is installed in an oven, where it is heated to a temperature of 250 ... 350 ° C to evaporate the binder from the protective coating with continuous evacuation of the cavity of the package. The bag is removed from the oven and cooled, continuing continuous evacuation. The presence of binder residues is detected by monitoring its level in the gas removed during evacuation. Next, the tube 14 is sealed. The bag is carefully transferred to a gas bath. Also, as in the prototype, it is possible to carry out the final removal of the binder and sealing the tube 14 when the package is already in the gas bath. In any case, the binder is removed at the temperature indicated above.

Next, diffusion welding of the workpieces is carried out, choosing the necessary temperature and pressure. The temperature can increase stepwise for the implementation of stepwise diffusion welding.

At the end of the diffusion welding operation, the obtained integral structural blank is set so that the adjacent surfaces of the skin and aggregate blanks are located strictly in the horizontal plane. Argon is carefully introduced into the cavity of the integral structural preform to effect elastic deformation of the preforms of the skin and the aggregate and to break the adhesive bond between the protective coating and the preforms. The operation of breaking the adhesive bond is carried out at room temperature. After relieving the pressure, the cavities of the integral structural preform are vacuumized and sealed.

Before the operation of giving the integral structural blank an aerodynamic profile, its cavities are subjected to repeated successive evacuation and filling with argon to remove oxygen from them. After removing oxygen from the cavities of the integral structural preform, the cavities are evacuated and sealed.

Next, the integral structural blank is installed in a device similar to that described in [7], and subjected to bending and twisting by means of hot deformation. At the final stage of the twist, the shape of the bent solid structural billet is corrected in accordance with the given shape of the stamp used for superplastic molding. In this case, a stamp directly intended for superplastic molding can be used. The split halves of the stamp are in contact with the integral structural blank along the edge portion, which will then be removed. It is advisable to perform the operation of imparting an aerodynamic profile to a solid structural billet in an inert gas environment in order to avoid intense oxidation of the external surfaces of the billet.

Figure 3 shows the feather 26 of the blade, having a complex aerodynamic profile in accordance with the ratio (2).

For the implementation of superplastic forming, an integral structural preform is installed between the already mentioned split die halves having the desired shape. The workpiece is heated and subjected to superplastic deformation. It is advisable to also carry out this operation in an inert gas environment in order to avoid intensive oxidation of the outer surface of the whole structural billet. The deformation is carried out due to the pressure of argon supplied to the cavity of the whole structural billet so as to provide a strain rate in the superplastic range of the aggregate billet. As a result of deformation of the blank of the skin, they take the form of a working cavity of the stamp, and the blank of the filler forms inclined stiffeners. At the same time, two parabolas having an inflection point at the location of the maximum thickness of the profile are formed on the sheath blank forming the trough of the scapula [1].

Figure 4 shows the cross section of the scapula, where item 27 indicates the casing forming the back of the scapula; Pos. 28, the lining forming the trough of the scapula is indicated. Pos.29 indicates the mentioned inflection point. Pos. 30 stiffeners are indicated.

After the superplastic forming operation, the semifinished product of the blade is subjected to machining by which the process zones are removed, the edges of the blade feather, the peripheral part of the feather and the blade lock are finally formed. In addition, all tubes are dismantled, and the holes remaining after them are sealed.

The following briefly explains how the method is carried out when there are protrusions and grooves on the surface of the skin blanks. The protrusions and grooves are formed by machining (figure 2). The protective coating is applied in the grooves 24, 25, after which the blanks of the skin and aggregate are collected in a bag. When removing the binder of the protective coating, the package of blanks is positioned so that adjacent surfaces are in a horizontal plane, maintaining this position of the package before and during diffusion welding. In addition, the pressure during welding is applied from the side of the sheathing blank forming the blade back.

In all other respects, the method is carried out in the same way as described above for the case when the surfaces of the skin blanks are flat over the entire area.

The hollow fan blade is made of titanium alloy. The most common titanium alloy used for the manufacture of such products is VT6 (Ti-6Al-4V) alloy in Russia and abroad. However, this does not exclude the use of other titanium alloys for manufacturing the blades. As a working medium, argon is usually used.

Examples of specific performance.

Example 1

According to the inventive method, a hollow fan blade was made having a complex aerodynamic profile designed in accordance with its description presented in [1].

Plates with an average grain size of 6 μm were used as the initial blanks of the skin. As the initial filler blank, a sheet 1 mm thick with an average grain size of 2 μm was used. The surfaces of the sheathing and filler blanks were flat over the entire area.

Given the average grain sizes in the blanks of the skin and aggregate, the following diffusion welding modes were selected:

welding temperature 920 ° C;

isostatic pressure applied to the package of blanks, 3 MPa;

welding time 2 hours.

The operation of breaking the adhesive bond between the blanks of the skin and aggregate and the protective coating was carried out at room temperature, while the argon pressure was chosen taking into account the maximum thickness of the blanks of the skin.

The operation of imparting a structural blank to the aerodynamic profile was performed at a temperature of 800 ° C.

Superplastic molding was carried out at a temperature of 920 ° C, argon was supplied under pressure according to a special schedule, ensuring the rate of deformation of the aggregate preform in the superplasticity mode.

Example 2

According to the claimed method were made simulators of the blades having an aerodynamic profile close to the profile of the working blades. In the manufacture of several simulators used blanks of skin with flat surfaces. In the manufacture of several other simulators, protrusions and grooves were performed on the surfaces of the skin blanks.

Sheets with an average grain size of 6 μm were used as the initial blanks of the skin. A sheet with a thickness of 0.8 mm with an average grain size of 0.6 μm was used as the initial filler blank. Diffusion welding was carried out in two stages:

the first stage was carried out at a temperature of 650 ... 700 ° C for 30 minutes, the second stage was carried out at a temperature of 900 ... 950 ° C for 2 hours.

The operation of imparting an aerodynamic profile to the integral structural blank was carried out at a temperature of 800 ° C.

Superplastic molding was carried out at a temperature of 920 ° C.

For comparative research and testing, several simulators were made from the same blanks by the method of [6].

Imitators were subjected to comprehensive control.

Three simulators, two of which were manufactured by the claimed method (one with protrusions on the surface of the skin blanks, the other with a flat surface of the skin blanks) and one - according to the method [6], were subjected to destructive testing after the diffusion welding operation. On all three simulators, microscopic “bridges” were identified connecting the blanks of the skin and the aggregate in areas that were not exposed to connection.

In addition, on the outer surface of the sheathing blank, forming the back of a blade simulator made according to the claimed method, having protrusions and grooves on the surfaces of the sheathing blanks, wave-like folds formed after diffusion welding, since pressure was applied to the bag from the side of the sheathing blank forming the back.

After superplastic molding, the simulators were subjected to holographic control. According to the results of holographic control of simulators made by the method of [6], preliminary assumptions were made about the deviation of the stiffness values of some ribs from a given value.

Three simulators, two of which were also manufactured by the claimed method (one with protrusions on the surface of the skin blanks, the other with a flat surface of the skin blanks) and one - according to the method [6], were subjected to destructive testing after the operation of superplastic forming.

In the simulator manufactured by the method [6], unevenness in thickness was detected in individual stiffeners. In the simulators manufactured by the claimed method, this drawback was absent.

In addition, in the simulator, which had protrusions on the surface of the sheath blanks, during superplastic molding, wrinkles on the outer surface of the sheath forming the back of the blade were eliminated.

Figure 5 presents a photo of a simulator of a hollow scapula with a cross section in cross section;

For the manufacture of the blades and blade simulators, the initial blanks of the skin and aggregate were used, manufactured by the metallurgical enterprise OJSC VSMPO-AVISMA Corporation (Russian Federation, Verkhnyaya Salda). For the blade simulators, special experimental filler blanks with an average grain size of 0.6 μm were made. At present, VSMPO-AVISMA Corporation OJSC produces sheet metal with a grain size of 1-3 microns, but in the future it is possible to produce sheet metal with a grain size of less than 1 micron. Such sheets are supposed to be used for the manufacture of a filler blank for the serial production of blades.

Serial production of blades is supposed to be carried out at OJSC “Ufa Engine-Building Production Association” (RF, Ufa).

Information sources

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Claims (8)

1. A method of manufacturing a hollow fan blade of a gas turbine engine, consisting of sheaths and aggregate made of titanium alloy, using diffusion welding to connect the sheaths and aggregate and superplastic molding to form a hollow feather and stiffeners, which consists in the following: operations according to which a coating is applied to the surface of sections of skin blanks and / or aggregate blanks not subjected to bonding during diffusion welding, Hindering the connection, collect the blanks of skin and aggregate in a bag, seal the bag at the edges, excluding the place of installation of at least one tube, connect the tube to the bag, the cavities of the bag are successively evacuated and fill with inert gas to remove oxygen from the cavities of the bag, heat the bag to the temperature required for evaporation of the binder from the coating, which prevents the bond, while continuing to evacuate the bag, completely seal the bag by sealing the tube, heat the bag to the temperature of diffusion welding, apply pressure to the bag and perform diffusion welding of the workpieces, then perform the operation of breaking the adhesive bond between the blanks of the skin and the filler and the protective coating formed during diffusion welding in areas that are not subjected to connection by creating a solid structural workpiece in the cavities, sufficient for elastic deformation of the blanks of the skin and aggregate, moreover, during the operation of breaking the adhesive bond, an integral structural the preparation is arranged in such a way that the adjacent surfaces of the sheathing and filler blanks are in a horizontal plane, they sequentially evacuate and fill the cavities of the whole structural blank with inert gas to remove oxygen from them, again completely seal the bag, heat it and give it the whole structural blank by hot deformation, obtained after diffusion welding, the aerodynamic profile, including the formation of the trough and back of the blade and the twist of the pen l patki heated integral structural preform to superplastic forming temperature, fed to its cavity a working environment for creating the pressure required for superplastic forming and superplastic forming is carried out to obtain a hollow blade leaf and forming stiffeners. 2. The method according to claim 1, characterized in that the sequential evacuation and filling with inert gas the cavities of the whole structural billet to remove oxygen from them before the operation of giving the whole structural billet an aerodynamic profile is carried out repeatedly. 3. The method according to claim 1, characterized in that they use a filler blank with a grain size of less than 1 μm. 4. The method according to claim 3, characterized in that the diffusion welding is carried out in two stages, while in the first stage the pressure is applied at a temperature below the temperature of the second stage, close to the lower boundary of the temperature range, ensuring the deformation rate corresponding to the conditions of superplasticity of the workpiece aggregate a sufficient time for the formation of physical contact between the joined blanks of the skin and the aggregate, and the second stage is carried out at a temperature and for the time necessary to develop I surround the interaction of connected blanks. 5. The method according to claim 4, characterized in that when using a filler blank with a grain size of 0.6 ... 0.8 μm, the first stage of diffusion welding is carried out at a temperature of 650 ... 700 ° C for 30 minutes, the second stage of diffusion welding is carried out at temperature 900 ... 950 ° C for 2 hours 6. The method according to claim 1, characterized in that they use blanks of skin, the surfaces of which are adjacent to the surface of the workpiece aggregate, are flat over the entire area. 7. The method according to claim 1, characterized in that on the surface of the skin blanks, sections to be bonded are formed in the form of protrusions with a flat surface and sections not to be bonded in the form of grooves, while in the process of removing the binder of the protective coating, the bag of blanks positioned so that the adjacent surfaces of the blanks of the skin and the filler were in a horizontal plane, maintaining this position of the package before and during diffusion welding. 8. The method according to claim 7, characterized in that the pressure during diffusion welding is applied from the side of the skin forming the back of the blade.

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