RU2503519C1 - Method of making blower composite blade leading edge strap - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming and can be used for making gas turbine blower blade leading edge strap. Workpiece of titanium alloy is shaped in vertical and horizontal planes. After shaping, workpiece is directly extruded to make strap reinforced front. Note here that metal stock is formed to make strap sidewalls. Then, workpiece is subjected to indirect extrusion to make strap side walls. In both cases used is die block, its male and female dies having the main forming profile in cross-sections. Male and female die profiles in vertical and horizontal planes correspond to workpiece profiles in said planes. Then, V-like profile of sidewalls is formed in strap cross-sections by bending. Then, strap reinforced front and sidewalls are shaped under isothermal conditions at titanium alloy super ductility and strap is twisted in preset spatial curve.

EFFECT: higher hardness and reliability.

6 cl, 18 dwg, 1 tbl, 2 ex

Description

The invention relates to the field of aircraft engine manufacturing and can be used in the manufacture of fan blades for gas turbine engines (GTE) made of materials with a matrix of polymers, in particular carbon fiber, or light alloys reinforced with high-strength fibers, the so-called composite blades.

Composite fan blade from the standpoint of weight reduction while maintaining the strength and reliability of the structure, as well as comparative ease of manufacture is very promising compared, for example, with a hollow blade made by diffusion welding and superplastic molding of titanium alloy.

The disadvantage of the composite blade is the low strength of the edges, especially the front (input) edge, which is most susceptible to external impact during operation when foreign objects: sand, stones, birds, etc., get into the fan's working area. Therefore, the leading edge of the blade is provided with an overlay of high-strength titanium alloy, manufactured in the form of a separate product, which is connected to the composite blade using fasteners or high-strength adhesive (US patent No. 5785498, IPC F04D 29/18, 1998).

At high speeds of the fan rotor and foreign objects with high kinetic energy entering the fan inlet, these objects primarily come into contact with the durable titanium pad on the front edge of the blade, protecting the composite edge from the effects of concentrated impacts.

As a separate product, the patch has a complex spatial shape formed by aerodynamic profiles in cross sections corresponding to the shape of the leading edge of the composite blade. An idea of the complexity of the profile of the blade gives its description (RF patent No. 2354854, IPC F04D 29/32, 2009). The overlay of the leading edge, like the edge itself, has a curved profile in the meridional (vertical) plane and bending in the horizontal plane. The aerodynamic profile of the cross sections of the lining is formed by segments of the lines of rarefaction (part of the back of the scapula) and pressure (part of the trough of the scapula). The pad is spatially twisted in the direction from the paddle lock to its periphery.

The patch has a reinforced front part, which is actually the front edge of the blade and thin side walls covering the front edge of the composite blade, with which the patch is connected to the composite blade.

A known method of manufacturing the lining of the leading edge of the composite fan blades (US patent No. 7640661, IPC B21D 53/78, 01/05/2010). According to this method, the overlay is made of two parts, usually from two sheet blanks having protrusions. The profile of the protrusions in cross section corresponds to the profile of the front of the lining. On the opposite side of the workpieces there are also protrusions that perform a technological function. In the area of protrusions, the workpieces are welded together by diffusion welding, forming an envelope with a sealed cavity. The leading edge gets the final shape by pneumoforming the resulting package in the superplasticity mode in the stamp. At the end of the blow molding process ledges are trimmed with the formation of the side walls of the lining.

The main disadvantage of this method is the presence of a welded joint, which also goes to the most loaded part of the lining during operation, which significantly reduces its reliability.

The known method (US patent No. 7156622, IPC F01D 5/14, 02/02/2007), in which the plate is made of three parts, also using welding and superplastic molding. The reinforced front part of the lining is made of a solid bar by the method of volumetric deformation and machining. The side walls of the lining are cut out and molded from sheet material. The walls are welded to the front using laser or diffusion welding.

This method differs from the previous method in that it provides greater reliability of the front of the lining, since the welded joint is away from the place of application of the load. However, the presence of a welded joint in any case reduces the reliability of the blade, especially since in this case there are two joints. In the case of joining the lining parts by laser welding, the uniformity of the properties of the lining material deteriorates to a large extent, up to the occurrence of dangerous stress concentrators.

As for the connection of the parts of the patch made by diffusion welding in the last two methods, it can be absolutely reliable only when common grains are formed in the joint zone and when the structure of the joint zone does not differ from the structure of the base metal. Such a compound can have toughness, ductility and strength at the level of these indicators for the base metal. However, to obtain such a reliable connection, many factors are necessary - at least, a prepared homogeneous fine-grained structure of the workpieces to be welded, a good pressure application scheme, and the possibility of creating a deep vacuum when welding workpieces made of titanium alloy. In addition, the duration of the stage of full volumetric interaction during diffusion welding is about 1.5-2 hours. Achieving these factors complicates the manufacturing process of the product, increases its duration and, as a result, increases energy costs and the cost of the product.

Closest to the claimed method is the method (US patent No. 5694683, IPC B23P 15/00, 12/09/1997), according to which the pad of the leading edge of the scapula is made of a solid bulk blank. Previously, in the workpiece by milling receive the inner cavity of a V-shaped. All subsequent process steps are carried out by pressure treatment. Through the hood, thin side walls and a reinforced portion of the patch are formed in the stamp. At the same time carry out profiling lining in the vertical and horizontal planes. Next, they carry out profiling of the side walls and the reinforced front part to obtain aerodynamic profiles in the cross sections of the lining and its twisting along the specified shape of the blade edge of the spatial curve. In this case, the formation of a reinforced front part, side walls and profiling of the lining in the vertical and horizontal planes is performed in isothermal conditions, providing a mode of high plasticity (superplasticity) of the alloy when the hood forms the side walls and front part of the lining.

In addition to observing isothermal conditions to ensure high ductility of a hard-to-deform titanium alloy, from which, as noted above, the overlay is made, it is also necessary to comply with certain strain rates and the presence of a prepared, as far as possible fine-grained and substantially homogeneous structure. If at least one of these three conditions is not met, a hard-to-deform titanium alloy is processed in the usual hot deformation mode (B. Bakofen, Deformation Processes. Massachusetts, California, 1972, translation, edited by S.E. Rokotyan, M: Metallurgy, 1977. S.242).

The heterogeneity of the alloy structure leads to heterogeneity in the deformation of the workpiece. In the case under consideration, when very thin lining walls are formed by drawing, deformation heterogeneity can be pronounced even with a slight heterogeneity of the alloy structure. In particular, the heterogeneity of the alloy structure may arise as a result of the previous machining due to the appearance of internal stresses in the surface layers of the workpiece exposed to the cutting tool (Novikov I.I. Theory of heat treatment of metals: textbook for universities. - 4th ed. - M.: Metallurgy, 1986, p.110-118). This inevitably occurs in the considered method when milling in the workpiece an internal V-shaped cavity. Moreover, during milling, the fibers of the lining material break, which extremely negatively affects not only the process of drawing the side walls, but subsequently reduces the reliability of the lining in operation. Annealing can be used to reduce stresses and their negative impact on the performance characteristics of the lining, while rupture of the material fibers, and in the thinnest section of the lining, will retain a negative effect on the properties of the lining during its operation.

It must be added that during deformation not only in the side walls, but also in the front reinforced part of the lining, as well as in the entire lining, various kinds of residual stresses arise. In the strengthened part, residual type II microstresses arise due to the use of small degrees of deformation, despite the fact that the deformation is carried out in isothermal conditions in the superplastic mode (Beckofen V. Deformation processes, p.242). Internal stresses also arise between the side walls subjected to significant deformation and the reinforced front of the lining, deformable with significantly lower degrees of deformation. In addition, stresses occur when profiling the workpiece in the vertical and horizontal planes. In the second and third cases, the residual stresses are zone or type I stresses, which are not completely eliminated by annealing. With the help of annealing, zonal stresses can only be reduced (II Novikov, Theory of Heat Treatment of Metals, p.110). In order to eliminate zonal stresses, subsequent hot deformation of the workpiece with a significant degree of deformation is necessary, but there is no such deformation in the method according to US Pat. No. 5,694,683. Residual stresses affect the behavior of the product during operation and even when stored in a warehouse. In operation, the residual stresses algebraically combined with the operating stresses can significantly reduce the reliability of the product, especially if the product, like the overlay of the leading edge of the composite blade, works in difficult conditions under the influence of shock loads.

The operating conditions of the blades in the gas turbine engine of new generations are becoming more complicated, which, of course, requires increasing the strength and reliability of the lining of the leading edge of the composite blade.

It is known that the strength properties of titanium alloys increase with decreasing grain size. So alloys with a homogeneous submicrocrystalline (SMC) structure (grain size of the order of 1 μm or less) exceed the properties of the same alloys in a coarse-grained state by 20–40% (Muliuk R.R. // Russian Nanotechnologies. T.2, issue 7- 8. 2007, p. 38).

In the method under consideration, a homogeneous fine-grained structure in the initial billet was not carefully prepared, which is necessary, as already noted, to effect deformation in the superplastic mode of a titanium alloy, the structure is lost in the manufacturing process. The use of such a deformation scheme as the hood does not even allow a slight decrease in the deformation temperature and inhibit grain growth. Moreover, at a temperature of deformation, the grains grow unevenly, in the surface layers where internal stresses arose, they grow much faster.

Thus, there is no margin to increase the strength of the patch, especially its reinforced part in the manufacture of the patch according to US Pat. No. 5,694,683.

The disadvantages of this method should also include the complexity of the press equipment and the design of the stamp used to deform the workpiece, and accordingly the complexity of their operation and repair. The complexity of the equipment and the design of the stamp is due to the need to carry out complex movements of the deforming tool simultaneously in several planes. In addition, such a stamp, which is so complex in design, is also cumbersome, which in turn requires prolonged heating to ensure isothermal conditions during deformation of the bulk workpiece, although, in general, combining operations by reducing the number of heatings can save some energy.

The method according to US patent No. 5694683 is selected for the closest in technical essence analogue of the claimed invention, since it, like the claimed method, is based on the use of mainly pressure processing for manufacturing the lining of the leading edge of the blade.

The invention is aimed at solving the problem of creating a method for manufacturing the lining of the leading edge of a composite fan blade of a gas turbine engine, which has the necessary reliability and strength for its operation and operation of the entire engine.

The specified problem allows us to solve the main technical results provided by the invention:

- in the process of carrying out the operations of the method associated with the formation of a reinforced leading edge and side walls of the lining, the occurrence of various kinds of internal stresses, breaking of the fibers of the material, that is, negative factors that can reduce the reliability of the lining in operation, is excluded

- the conditions for carrying out the noted and all other operations of the method contribute to the maintenance of a largely fine-grained and uniform structure in the finished patch, which allows to increase its strength.

The marked technical results cannot be achieved in the manufacture of the lining by the method, which is the closest analogue of the invention.

Compared with the closest analogue, the invention provides another technical result, which consists in simplifying the equipment and tools used in the implementation of the method - dies.

In particular cases, the invention provides the following additional technical results:

- reduces the energy intensity of the method by reducing the number of heatings when combining part of the operations of the method as transitions of one operation, exceeding the level achieved in the closest analogue, since a sufficiently compact and simple stamp design is heated;

- when forming the side walls and the reinforced front of the lining, the low-temperature superplasticity mode is used, and all other operations of the method are carried out at a temperature not higher than the temperature selected for extrusion, therefore, the homogeneous fine-grained structure of the workpiece is maximally preserved, which leads to a significant increase in the strength of the lining. Here, a reduction in the energy intensity of the method and the thickness of the gas-saturated layer is achieved. When combining the operations of the method and using the low-temperature superplasticity mode, a maximum reduction in the energy intensity of the method is achieved in comparison with the closest analogue;

- it becomes possible to perform microrelief on the inner surface of the side walls of the lining, which allows to increase the strength of its connection with the leading edge of the composite blade.

The following are the essential features of the invention, providing basic technical results in all cases of the implementation of the method:

A method of manufacturing a lining of the leading edge of a composite fan blade having a complex spatial shape corresponding to the shape of the leading edge of the blade, formed by aerodynamic profiles in cross sections, with a reinforced front part and side walls by pressure molding of a solid bulk workpiece from titanium alloy, includes profiling the workpiece in vertical and horizontal planes, the formation of a reinforced front of the lining and its side walls, as well as side profiling O walls and the reinforced front portion for airfoils at cross sections laths and its curling at predetermined spatial curve, where the formation of a reinforced front portion and side walls laths operate under isothermal conditions in superplastic alloy mode,

The method differs from the closest analogue in that after profiling the workpiece in horizontal and vertical planes, the process of direct extrusion of the workpiece is carried out with the formation of a reinforced front part of the lining and with the formation of a supply of material for the formation of the side walls of the lining. Then the backward extrusion of the workpiece is carried out with the formation of the side walls of the lining of the U-shaped profile in cross sections, using in both cases extrusion a stamp whose punch and matrix, in addition to the main forming profile in cross sections, have a profile in vertical and horizontal planes corresponding to the lining profile in these planes. Next, a V-shaped profile of the side walls is formed in cross sections by bending in a die, the matrix and punch of which have a corresponding profile in cross sections, and in the vertical and horizontal planes have a profile corresponding to the lining profile in these planes. Then, using a plastic insert, profiling of the reinforced front part and side walls of the lining is carried out to obtain aerodynamic profiles in the cross sections of the lining and twisting the lining along a given spatial curve.

The following are signs that characterize the invention in particular cases, providing additional technical results:

- direct and reverse extrusion is carried out in two transitions of the same operation, using one stamp, the matrix of which in the upper part, designed to form the side walls, and the punch are U-shaped;

- profiling in the vertical plane, direct and reverse extrusion of the workpiece, is carried out in three transitions of one operation, using one stamp, the matrix of which in the upper part, designed to form the side walls, and the punch are U-shaped. At the same time, at the transition of profiling in the vertical plane, the workpiece is placed at the initial moment so that it rests on the highest portion of the shoulders of the U-shaped matrix. The end of the profiling transition in the vertical plane is judged by the moment the workpiece abuts along the entire length of the shoulders of the U-shaped matrix;

- profiling in horizontal and vertical planes, as well as direct and reverse extrusion of the workpiece is carried out in four transitions of one operation, using one stamp with a detachable matrix, which in the closed state in the upper part, designed to form the side walls, has a U-shape. At the same time, at the transition of profiling in the horizontal plane, the workpiece is placed at the initial moment so that it rests on the highest portion of the shoulders of one of the parts of the open U-shaped matrix. Profiling in the horizontal plane of the workpiece is carried out by closing parts of the matrix. Accordingly, at the final moment of profiling in the horizontal plane, the workpiece rests on the highest portion of the shoulders of both parts of the closed matrix. Next, profiling in the vertical plane, direct and reverse extrusion of the workpiece is carried out using the matrix in the closed state and the U-shaped punch. In addition, the end of the profiling transition in the vertical plane is judged by the moment the workpiece rests along the entire length of the shoulders of the U-shaped matrix;

- for the manufacture of pads use a workpiece with a submicrocrystalline structure. In this case, the operation of direct and reverse extrusion is carried out in the regime of low-temperature superplasticity at a specific temperature, selected from a temperature range of 650-750 ° C. All other pressure processing operations are carried out at a temperature selected in the indicated interval, but not higher than that selected for extrusion;

- reverse extrusion is carried out with the formation of at least part of the inner surface of the initially formed side walls of the microrelief in the direction of extrusion through the use of a punch having a corresponding microrelief on the surface.

The above essential features are in a causal relationship with the main technical results, because:

- during the direct extrusion of a volume blank preformed in horizontal and vertical planes with the formation of a reinforced front part of the lining, as well as with the formation of a supply of material for the formation of the side walls of the lining in isothermal conditions in the superplastic mode of the alloy, due to deformation with significant degrees according to the scheme close to comprehensive compression scheme, eliminates the possibility of occurrence in the front reinforced part of the lining of various kinds of residual stresses. This increases the reliability of the front end and the entire lining as a whole. Moreover, the sequence of operations is also important, since when profiling the workpiece in horizontal and vertical planes, as well as in the method according to US patent No. 5694683, zonal stresses occur in the workpiece blank. However, unlike the method of US Pat. No. 5,694,683, in the direct extrusion process, due to the all-round compression scheme and a significant degree of deformation, the zonal stresses are completely eliminated. The direct extrusion process contributes to the preservation of the fibrous structure of the alloy and its favorable orientation in the reinforced front of the lining. The preservation of the fibrous structure and its favorable orientation further increase the reliability of the front part of the lining, as well as increase the strength of the front part and its ability to withstand shock loads. The conditions of comprehensive compression contribute not only to the preservation of the fine-grained structure of the material, but also to its improvement, in particular, they contribute to the elimination of random pores that may be in the original bulk blank, which also increases the strength of the front part and the entire lining as a whole;

- in the process of backward extrusion of a bulk workpiece with the initial formation of the side walls of the U-shaped lining in cross sections in isothermal conditions in the superplastic mode of the alloy, the possibility of zonal stresses between the front part of the lining and its side walls is eliminated, since these parts of the lining are deformed with approximately equal degrees of deformation. In addition, as a result of this operation, the initial U-shaped profile of the walls is obtained without the use of a machining operation, which contributes to the preservation of the fibrous structure and its favorable orientation in the side walls of the lining. If you need additional stretching of the walls of the patch in the manufacture of large blades, the drawing conditions remain favorable, whereas in the method according to US patent No. 5694683, a portion of the workpiece is subjected to hooding, in which the fibers are cut during milling, which can lead to a rupture of the side wall;

- the subsequent formation by bending a preliminary V-shaped profile of the side walls in the cross sections of the lining, where for this they use the simplest design stamp, the matrix and punch of which have the corresponding forming surfaces, allows you to further maintain the fine-grained fibrous structure of the workpiece. Moreover, the deformation scheme during bending by the type of pulling between the walls of the matrix and the punch eliminates the occurrence of internal stresses in the walls. Removing the prefabricated lining from the stamp can be carried out using an ejector and / or a detachable matrix. This operation can be carried out in isothermal conditions in the superplasticity mode or in the hot deformation mode without observing the superplastic deformation rates;

- profiling with the help of a plastic insert of the reinforced front part and the side walls of the lining to obtain aerodynamic profiles in the cross sections of the lining and twisting it along a predetermined configuration of the blade edge of the spatial curve, provides a flawless manufacturing of the lining of the leading edge of the composite fan blade at the final stage of the method. Profiling and twisting can be carried out in one die with a detachable matrix, or twisting can be carried out separately in the device, providing for the capture of the ends of the lining and its twisting. In any case, the use of a plastic liner is mandatory. This operation can be carried out in isothermal conditions in the superplasticity mode or in the hot deformation mode without observing the superplastic deformation rates;

Separate in time the implementation of the operations of the method can greatly simplify the design of stamping tools, as well as simplify the process of their operation and repair.

The features characterizing the invention, in special cases, are in a causal relationship with additional technical results, because:

- combining part of the operations of the method as transitions of one operation allows these transitions to be performed by heating the stamp and the workpiece once. Defects that may occur during repeated removal of the lining from various dies are excluded. Combining part of the operations in the inventive method, unlike the closest analogue, does not entail complications of the press equipment and changes in the design of the stamp. In this case, transitions are carried out in time sequentially one after another. By choosing higher deformation rates, the transitions of profiling the workpiece in the horizontal and vertical planes can be carried out in a mode different from the superplasticity mode, which will reduce the total residence time of the workpiece in isothermal conditions. In addition, the use of a detachable matrix facilitates the removal of the semi-finished lining from its cavity at the end of this operation;

- the use of a workpiece with a QMS structure for the manufacture of plates and direct and reverse extrusion at a temperature selected from a temperature range of 650-750 ° C, and all other pressure treatment operations at a temperature selected in the specified range, but not higher than the selected temperature for extrusion, allows you to deform the workpiece in conditions that contribute to the maximum preservation of its structure in the finished product. In addition, the lower the processing temperature of the billet, the smaller the thickness of the gas-saturated layer formed on the surface of the titanium billet and the smaller the volume of operations for the final finishing of the finished product. When using lower processing temperatures, the energy intensity of the method is reduced;

- in the conditions of operation of the fan, a significant centrifugal force tries to tear the pad off the leading edge of the blade. An obstacle to this is the complex spatial profile of the leading edge of the scapula and the fixing of the lining. Nevertheless, some sections of the lining under the influence of centrifugal forces try to elastically stretch, while other sections, restrained from stretching by the configuration of the scapula, are compressed on the contrary. At the boundary of these sections, a significant voltage drop occurs, which can weaken and even destroy the points of attachment of the patch to the leading edge of the blade. When performing extrusion, it becomes possible to form at least a part of the inner surface of the side walls of a U-shaped cross-section of the profile of the patch in the direction of extrusion of the microrelief through the use of a punch having a corresponding microrelief on the surface. Due to the lack of further pressure processing operations associated with volumetric deformation, the resulting microrelief is stored in the finished product. The microrelief is obtained directed in operation perpendicular to the vector of centrifugal force acting on the blade. The microrelief contributes to the reliable connection of the lining with the leading edge of the composite blade. The microrelief also contributes to damping the elastic stresses arising in the patch.

The invention is illustrated by a detailed description of a method for manufacturing the lining of the leading edge of a composite fan blade with reference to FIGS. 1-18, and specific examples of its implementation, indicating processing modes.

The invention is illustrated graphic materials. Below is a brief description of them:

figure 1 schematically depicts a right view of a vertically located cover plate of the leading edge of the fan blades;

in Fig.2 schematically shows a top view of a vertically located plate of the leading edge of the fan blades in Fig.1;

figure 3, 4 is a top view and in cross section, schematically shows the initial (parts of the matrix are open) the transition moment at which the lining blank is given the desired profile in the horizontal plane;

figure 5, 6 is a top view and in cross section, schematically shows the final (parts of the matrix are closed) transition moment, at which the required profile in the horizontal plane is attached to the lining blank;

7, 8 - front view with the reclined part (half) of the matrix, schematically shows the initial (the workpiece touches only that part of the shoulders of the matrix, which is located above the others) and the final (the workpiece lies along the shoulders of the matrix along the entire length) transition moments, on which the blank blanks give the desired profile in a vertical plane;

Figures 9, 10, 11 schematically depict the initial and final moments of the direct extrusion transition of the reinforced front part and the final moment of reverse extrusion of the side walls of the U-shaped cover plate, respectively, in cross section of the stamp;

on Fig, 13 schematically depicted in the cross section of the stamp, respectively, the initial and final moments of the operation of bending the side walls of the lining with giving them a V-shaped profile;

on Fig, 15 schematically depicted in the cross section of the stamp, respectively, the initial and final moments of the operation of giving the cross sections of the lining of the aerodynamic profile;

on Fig presents a photograph of the finished lining;

on Fig, 18 presents photographs of the microstructure of the VT6 titanium alloy in the areas of the side wall and the reinforced front of the finished lining.

The overlay has the following structural elements (see figure 1, 2):

L is the total height;

l is the height of the side walls;

h is the height of the reinforced front;

t is the width of the reinforced front at the junction with the side walls;

t 'is the thickness of the side wall.

The overlay 1 shown in FIGS. 1, 2 and 16 has an aerodynamic cross-sectional profile formed by pressure lines 2 and rarefaction 3, respectively profiled side thin walls 4, 5 and a reinforced front part 6.

The pad is obtained from a long lengthy workpiece 7 (Fig.3-8).

Figure 3-11 schematically shows the transitions performed as transitions of one profiling operation in horizontal (Fig. 3, 4, 5, 6) and vertical (Fig. 7, 8) planes, as well as forward and reverse extrusion (Fig. 9, 10 , 11) the blank 7. For this, use a stamp with a split matrix 8, consisting of two parts (halves) 9, 10 with shoulders 11, 12 located in the housing 13. Moreover, at the transition of profiling in a horizontal plane (Figs. 3, 4, 5, 6) only a split matrix 8 is used as a tool.

In the closed state, the matrix 8 (Fig.6) forms the upper 14 and lower 15 cavities. The upper cavity 14 due to the shoulders 11, 12 has a U-shaped profile in cross sections. It should be noted here that when backward extrusion naturally only a U-shaped blank profile can be obtained. The lower cavity 15 has a profile corresponding to the profile of the reinforced front of the lining.

At the transitions of profiling in the vertical plane, forward and reverse extrusion (Fig.7-11) also use the punch 16. In Fig.7-11, the matrix body 13 is not shown. At the end of the reverse extrusion transition, a semi-finished lining 17 is obtained (Fig. 11).

At all these transitions, a stamp is used, the punch 16 and the matrix 8 of which, in addition to the main shape-forming profile in cross sections, have a profile in vertical and horizontal planes corresponding to the profile of the lining 1 in these planes.

On Fig, 13 schematically shows the operation of bending the side walls of the semi-finished plate 17 in the stamp with a split matrix 18, consisting of two parts (halves) 19, 20 with a punch 21. The cavity of the matrix 18 and the punch 21 have profiles in cross sections corresponding to the preliminary lining profile 1. In addition, the matrix 18 and the punch 21 have a profile in vertical and horizontal planes corresponding to the lining profile 1 in these planes.

On Fig, 15 schematically shows the initial and final moments of the operation of giving the side walls 4, 5 and the reinforced front part 6 in their cross sections of the aerodynamic profile. In this case, a plastic insert 22 is installed between the side walls 4, 5. Profiling is carried out in a detachable matrix 23, consisting of two parts (halves) 24, 25.

A method of manufacturing a lining of the leading edge of the composite fan blades is as follows.

Given the advisability of combining the operations of the method, as well as to simplify the description, part of the operations, namely profiling of the workpiece in the horizontal and vertical planes, as well as direct and reverse extrusion, will be considered as transitions of the first operation using one stamp. However, all operations of the method, as follows from the list of essential features, can be performed separately using different stamps.

At the first transition, profiling of the bulk workpiece 7 is carried out in the form of a long bar with a prepared homogeneous fine-grained structure in the horizontal plane (Figs. 3, 4, 5, 6) using a die with a split matrix 8 consisting of two halves 9, 10 located in the housing 13.

Half of the stamp matrix 9, 10 has shoulders 11, 12, the main function of which is to participate in the formation of a supply of material for the formation of the side walls of the U-shaped profile at the transition of direct extrusion. At the transition of profiling the workpiece in the horizontal plane, the shoulders 11, 12 are used as an auxiliary means so that the workpiece 7 rests on one of them at the initial moment of profiling. The workpiece rests on the highest portion of the shoulder of half of the matrix. Profiling in the horizontal plane of the workpiece 7 is carried out by closing the halves of the matrix 9, 10, respectively, at the final moment of profiling in the horizontal plane, the workpiece rests on the highest portion of the shoulders 11, 12 of the closed matrix 8.

At the second transition, the workpiece 7 is profiled in the vertical plane (FIGS. 5, 6) using the punch 16 and the upper cavity 14 of the closed matrix 8. The end of the profiling transition in the vertical plane is judged by the moment the workpiece stops along the entire length in the shoulders 11, 12 of the matrix 8 .

At the end of the profiling of the workpiece in the horizontal and vertical planes, the deformation force is increased and the process of direct extrusion (Fig. 9, 10) of the workpiece into the lower cavity 15 of the matrix 8 is carried out by means of a punch 16, thereby forming a reinforced front part 6 of the lining, and a supply of material for forming side the walls. The moment of completion of the direct extrusion process is fixed at the time of filling the cavity 15 of the matrix. Further, the deformation force is increased to the value necessary to effect reverse extrusion into the upper cavity 14 of the matrix 8, thereby forming the side walls 4, 5 of the lining of the intermediate U-shaped profile. The magnitude of the force during forward and reverse extrusion is selected from the condition of ensuring the strain rate corresponding to the conditions of superplasticity. At the final stage of this operation, the semi-finished product 17 of the lining 1 is obtained. The connector of the matrix 8 facilitates the extraction of the semi-finished product 17 from it.

If necessary, the formation of a microrelief (not shown) on the inner surface of the side walls of the lining use a punch (not shown), which differs from the punch 16 by the presence of a microrelief on the forming surface.

The first operation is carried out in isothermal conditions, heating the workpiece 7, the die 8 and the punch 16 to a strain temperature. Moreover, due to the choice of strain rates, transitions of direct and reverse extrusion are carried out in the superplasticity of the titanium alloy. The necessary rate of superplastic deformation is provided by applying a load according to a law determined by computer simulation.

Then, the obtained semi-finished product 17 of the lining 1 is placed in another stamp (Fig. 12, 13) and the operation of bending the walls is carried out to form a V-shaped profile using a punch 21 and a detachable matrix 20, consisting of two halves 18, 19. Here, the matrix connector is intended for in order to also facilitate the removal of the lining from the cavity of the matrix. This operation is carried out in isothermal or close conditions. It is possible to use the superplasticity mode.

At the final stage of the method, the final profile of the lining 1 is formed in cross section by bending and twisting (Fig. 14, 15). To do this, use a plastic liner 22, which can be made of steel, and a detachable matrix 23, consisting of two halves 24, 25. Bending and twisting occur during the closing of the halves of the matrix. This operation is also carried out in isothermal or close conditions. It is also possible to use the superplasticity mode.

Examples of specific performance of the method:

The following examples are not exhaustive in terms of product sizes, their configuration, the alloys from which they are made, as well as the types of equipment used.

Example 1

An overlay of the leading edge of the composite blade was made of two-phase titanium alloy VT6 (Ti-6Al-4V) with dimensions: (Fig. 1) L = 160 mm, (Fig. 2) h = 6 mm; l = 9 mm; t '= 0.3 mm; and size t, where size t varies in different sections from 2.7 to 1.6 mm. The initial bulk billet with a QMS structure with a grain size of 0.3 μm was obtained by multiaxial precipitation with a decrease in temperature to 600 ° C, followed by isothermal rolling at a temperature of 560 ° C and machining. The dimensions of the workpiece in the cross section were calculated based on the area of the corresponding sections of the mathematical model of the lining with the addition of 20% of technological allowance.

Profiling operations in horizontal and vertical planes, direct and reverse extrusion were performed as transitions of one operation using an isothermal stamping unit with a set of forming elements mounted on a hydraulic press DE2428-01 with a maximum force of 630 kN. The main details of this stamp, as well as the stamps used in subsequent operations, were made of 4X4VMF steel. The temperature of this operation was chosen equal to 650 ° C. A pre-release lubricating coating based on boron nitride was previously applied to the workpiece and to the stamp parts.

The profiling of the workpiece in the horizontal and vertical planes was carried out with a deformation force of 5-10% of the maximum press force, while it was not required to comply with the high-speed superplasticity mode. To effect a direct extrusion transition, the deformation force was increased to a value of 30-50% of the maximum press force. To implement the reverse extrusion transition, the deformation force was increased to 70-95% of the maximum press force.

Forward and reverse extrusion transitions were performed in the superplasticity mode, which was ensured by the law of load application obtained by computer simulation. The law of application of the load was chosen so that the strain rate at various points of the cross section of the billet did not go beyond the upper and lower boundaries of the optimal superlastic speed range for a titanium alloy with this structure at a selected temperature. The remaining transitions of this operation were performed under isothermal conditions without observing the high-speed superplasticity regime.

During reverse extrusion, a microrelief was formed in the extrusion direction on the inner surface of the side wall of the patch. The relief has a wavy profile with a height of 20-30 microns with a period of 1-1.5 mm, copying the microprofile of the surface of the punch used for extrusion.

Further, replacing the forming parts of the stamp — the matrix and the punch — carried out the operation of bending the side walls of the prefabricated lining. The stamp and prefabricated were heated to the above temperature. The force during the operation of bending the walls was 5-10% of the maximum press force. This transition was performed under isothermal conditions without observing the high-speed superplasticity regime.

At the final transition, the lining was twisted relative to its longitudinal axis along the specified configuration of the curve of the composite blade edge with simultaneous profiling of the side walls and the reinforced front part to give the cross sections of the lining an aerodynamic profile. The plastic liner installed between the side walls was made of low carbon steel.

The final processing of the lining consisted in the chemical removal of the anti-adhesive lubricating coating, trimming the allowances at the ends and along the edges of the walls, as well as in grinding the outer surface of the lining with an emery cloth.

In this case, the thickness of the gas-saturated layer under the surface of the patch, determined by the microhardness method, before machining did not exceed 10 μm.

As a result of the operations provided for by the method, a lining of the leading edge of the carbon fiber blade was obtained (Fig. 16).

The average grain size determined by transmission electron microscopy in the samples cut from the wall and the reinforced front of the patch was of the same order, namely, 0.3 μm and 0.5 μm, respectively (Fig.17, 18). Thus, the microstructure of the alloy in the entire overlay was homogeneous ultrafine-grained, the microstructure of the alloy was characterized by a low dislocation density and, accordingly, a low level of stresses in the product.

The mechanical properties of witness samples with a similar structure are given in the table.

Example 2

An overlay of the leading edge of the composite blade was made of two-phase titanium alloy VT6 (Ti-6Al-4V) with dimensions (Figure 1): L = 712 mm and (Figure 2) h = 4 mm; l = 60 mm; t '= 0.35 mm; size t varied in different sections from 8.5 to 1.6 mm. An initial billet with a grain size of 3-5 μm was obtained by rolling with a preheating temperature of 890 ° C and machining. The dimensions of the lining blank in the cross section were calculated based on the area of the corresponding sections of the mathematical model of the lining with the addition of 40% of technological allowance. Compared with example 1, the technological allowance is increased taking into account the greater thickness of the gas-saturated layer.

The operations of bending, direct and reverse extrusion were carried out analogously to example 1, using an isothermal die block with a set of forming elements mounted on a hydraulic press PK 12.6.36.09 with a maximum force of 4000 kN. The main parts of the stamp were made of heat-resistant alloy ZhS6U. The stamping temperature was 920 ° C. An anti-adhesive lubricating coating based on EVT-24 glass enamel was previously applied to the workpiece.

The law of application of the load was determined analogously to example 1. All pressure processing transitions were performed according to schemes similar to example 1.

The final processing of the lining consisted in the chemical removal of the anti-adhesive lubricating coating, trimming the allowances at the ends and along the edge of the walls, as well as in grinding the surface with an emery cloth.

The average grain size determined by transmission electron microscopy in the samples cut from the wall and the reinforced front of the patch was of the same order, namely, 4.5-5 microns. Thus, the microstructure of the alloy in the entire overlay, as in Example 1, was homogeneous, but ordinary fine-grained. The microstructure of the alloy was characterized by a low dislocation density and, accordingly, a low level of stresses in the product.

The mechanical properties of witness samples with a similar structure are given in the table.

The average grain size, microns. σ _0.2 , MPa σ _B , MPa δ,% Ψ,% 0.4 1260 1320 6.1 37 4,5 960 1010 16 26

Claims (6)

1. A method of manufacturing a lining of the leading edge of the composite fan blade, which has a spatial shape corresponding to the shape of the leading edge of the blade, formed by the aerodynamic profile in cross sections, and made with a reinforced front part and side walls, by pressure treatment of a solid bulk workpiece of titanium alloy, including profiling said blank in vertical and horizontal planes, the formation of a reinforced front of the lining and its side walls, as well as the covering of the side walls and the reinforced front with obtaining an aerodynamic profile in the cross sections of the lining and its twisting along a predetermined spatial curve, while the formation of the strengthened front and side walls of the lining is performed in isothermal conditions in the superplasticity mode of the titanium alloy, characterized in that after profiling the workpiece in horizontal and vertical planes, the process of its direct extrusion is carried out with the formation of a reinforced front of the lining and with the image By increasing the supply of material for the formation of its side walls, the backward extrusion of the workpiece is carried out with the formation of the side walls of the lining of the U-shaped profile in cross sections, while the processes of direct and reverse extrusion are carried out in a stamp with a punch and a matrix, which are made with the main forming profile in cross sections, and in vertical and horizontal planes - with a profile corresponding to the lining profile in these planes, then in the cross sections of the lining form t V-shaped profile of the side walls by bending in a stamp, the matrix and punch of which are made with cross sections of the corresponding profile, and in the vertical and horizontal planes have a profile corresponding to the lining profile in these planes, then using a plastic insert, profiling of the reinforced front part is performed and the side walls of the lining to obtain an aerodynamic profile in cross sections of the lining and twisting the lining along a given spatial curve. 2. The method according to claim 1, characterized in that the direct and reverse extrusion is carried out in two transitions of the same operation in one stamp, the matrix of which in the upper part, designed to form the side walls of the lining, and the punch are U-shaped. 3. The method according to claim 1, characterized in that the profiling of the workpiece in a vertical plane and direct and reverse extrusion is carried out in three transitions of one operation, using one stamp, the matrix of which in the upper part, designed to form the side walls of the lining, and a punch have a U-shape, while at the transition of profiling in the vertical plane, the workpiece is placed at the initial moment with support on the highest portion of the shoulders of the matrix of a U-shape in the upper part, and about the end of the transition profile Positioning in the vertical plane is judged by the moment of abutment of the workpiece along the entire length into the said shoulders of the matrix. 4. The method according to claim 1, characterized in that the profiling in horizontal and vertical planes, as well as direct and reverse harvesting of the workpiece is carried out in four transitions of one operation, using one stamp with a split matrix, which is in the closed state in the upper part, designed to form the side walls of the lining, has a U-shape, while at the transition of profiling in the horizontal plane, the workpiece is placed at the initial moment with support on the highest portion of the shoulders of one of the parts open split matrix, profiling in the horizontal plane of the workpiece is carried out by closing parts of the split matrix, while at the final moment of profiling in the horizontal plane, the workpiece is supported on the highest portion of the shoulders of both parts of the closed split matrix, then profiling in the vertical plane, direct and reverse extrusion preforms are carried out in a matrix in a closed state using a U-shaped punch, moreover, about the end of the transition milling in the vertical plane is judged by the moment of abutment of the workpiece along the entire length of the shoulders of the matrix. 5. The method according to any one of claims 1 to 4, characterized in that a preform with a submicrocrystalline structure is used, and the forward and reverse extrusion operations are carried out in the low-temperature superplasticity mode at a temperature that is selected from a temperature range of 650-750 ° C, and all the rest of the pressure treatment of the workpiece is carried out at a temperature selected in the specified interval, but not exceeding the temperature selected for the operation of direct and reverse extrusion. 6. The method according to any one of claims 1 to 4, characterized in that the reverse extrusion is carried out with the formation of at least part of the inner surface of the initially formed side walls of the microrelief lining in the extrusion direction by using a punch having a corresponding microrelief on the surface.

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