SE509351C2 - Production esp. of gas turbine engine blades - Google Patents

Abstract

A method of manufacturing hollow articles by superplastic forming and diffusion bonding at least two metal workpieces comprises: (a) defining a series of spaced preselected areas (46) of at least one of the surfaces of at least one of the at least two metal workpieces (12,14) to prevent diffusion bonding at the preselected areas, each preselected area corresponding to the hollow interior of one of a series of hollow articles; (b) assembling the at least two workpieces into a stack; (c) applying heat and pressure across the thickness of the at least two metal workpieces to diffusion bond the at least two workpieces together, in areas other than the series of spaced preselected areas to form an integral structure; (d) heating and internally pressurising the preselected areas to cause the preselected areas to be superplastically formed to produce a series of hollow articles (86) of predetermined shapes; and further (e) parting the integral structure between the series of spaced pre selected areas to provide a series of articles, step (e) occurring between steps (c) and (d) or after step (d).

Description

509 351 in ¿(d) heating and internal pressure saturating the predetermined areas to cause the predetermined areas to be formed superplastically to provide a number of hollow articles of predetermined shape, and a further step of dividing the one-piece construction between said plurality of mutually separated, predetermined areas to produce a number of articles, the further step being performed between steps (c) and (d) or after step (d).

Preferably, step (a) comprises applying an inhibitor material to prevent diffusion binding at each of said fls of mutually spaced, predetermined regions.

Preferably, each of the at least two metal workpieces has at least one flat surface, and the inhibitor material is applied to at least one of the planar surfaces and the at least two workpieces are joined together in a stack relative to each other so that the planar surfaces fit and abut each other.

Preferably, the method comprises machining at least one of the at least two metal workpieces on a number of mutually spaced predetermined areas, the machined areas being on the surfaces located opposite the surfaces to be diffusion bonded, each machined area corresponding to an outer surface one of the. number of hollow articles, the machined areas having a varying mass distribution.

Heating and internal pressurization of the predetermined areas for the purpose of superplastically shaping the predetermined areas to produce the hollow articles of predetermined shape can be performed before dividing the one-piece structure between the plurality of spaced apart predetermined plurals to provide articles. An edge of the one-piece structure can be machined to provide a number of root portions after heating and pressurizing the number of predetermined areas to superplastically form the predetermined areas to provide the hollow articles with predetermined areas. shape and before dividing the one-piece construction between the number of predetermined areas to produce the number of hollow articles. After dividing the one-piece structure to provide the number of hollow articles, the remaining outer surface portion of each of the articles can be machined into a wing profile.

Dividing the one-piece structure to provide the number of hollow articles can be performed simultaneously with machining the remaining outer surface portion of the one-piece structure into a number of wings with a wing profile.

The method may include partial division of the integral structure by providing slits from a first edge of the integral structure between the mutually sealed, predetermined areas, heating the integral structure and applying loads to opposite ends of each of the fl number of articles to rotate one end relative to the other end for the purpose of giving each article a predetermined shape after superplastic shaping of the mutually separated predetermined areas to produce the hollow article shapes with a predetermined shape and before division of the one-piece construction. The edge opposite the first edge of the one-piece construction can be machined to separate the articles and to create a number of root portions. After machining the root portions, the twisted outer surface portion of each of the articles can be machined into a wing profile. The twisted outer surface portion of each of the artillery pieces can be machined into a wing profile. After machining the turned outer surface into a wing profile, the edge opposite the first edge of the one-piece structure can be machined to separate the articles and to form a number of root portions.

The method may include partial separation of the articles by providing slits from a first edge of the one-piece structure between the spaced apart predetermined areas, heating the one-piece structure and applying loads to opposite ends of each of the pieces. The number of articles for rotating one end relative to the other end in order to give each article a predetermined shape after diffusion bonding of the workpieces to form the one-piece structure and before superplastic forming the separated predetermined areas to produce the hollow articles with a predetermined shape and divide the one-piece construction.

Prior to partial separation of the articles, loads are applied to the end opposite the first end of the one-piece structure to arch the end. The edge opposite the first edge of the one-piece construction can be machined to separate the articles and to create a number of root portions.

After machining the root portions, the twisted outer surface portion of each of the articles is machined into a wing profile shape. The twisted outer surface portion of each of the articles can be machined into a wing profile. After machining the turned outer surface of the wing profile, the edge opposite the first edge of the one-piece structure is machined to separate the articles and to provide a number of root portions.

Dividing the integral structure between the av number of spaced, predetermined areas to provide the plurality of articles may precede heating and internal pressurization of the plurality of predetermined areas to cause the predetermined areas to be superplastically formed to produce hollow articles. Each of the number of articles can be heated and loaded at its opposite ends to rotate one end relative to the other end in order to give the article a predetermined shape after dividing the one-piece construction into a number of articles and before heating and pressurizing the tal number of predetermined areas to superplastically shape the predetermined areas to produce the hollow articles of predetermined shape. Before rotating the opposite ends of each article, heat and loads are applied to one end of each article to arch said ends. The curved end of each article can be machined to form a root portion. The remaining outer surface portion of each article can be machined into the wing profile. 10 15 20 25 30 5. 509 351 Machining of the outer surface of the article to the wing profile can be done by electrochemical machining. The electrochemical processing may include trepanation of the electrocellanic processing electrodes.

Preferably, fl the number of separated, predetermined areas is separated in the longitudinal direction of the workpieces. At least some of the majority of separated predetermined areas are separated in the transverse joint of the workpieces.

Preferably, at least one metal block is joined with the at least two metal workpieces into a stack so that said metal block is located at a first edge of the stack, after which said metal block is diffusion bonded to the metal workpieces. Preferably, two metal blocks are applied at the first edge of the stack and on opposite surfaces of the stack. At least one other metal block can be joined to the at least two metal workpieces and said at least one metal block to a stack so that said at least one metal block is located at a first edge of the stack and said at least one other metal block is on the opposite edge of the stack, then the metal blocks diffusion bonded to the metal workpieces. At least one metal block can be joined to the at least two metal workpieces into a stack so that the at least one metal block is located at a central area of the stack, after which the at least one metal block is diffusion bonded to the metal workpieces. Two metal blocks can be applied at the central area of the stack and on opposite surfaces of the stack. The one-piece construction can be machined longitudinally through the center of said at least one metal block.

The present invention will now be described in more detail with the aid of exemplary embodiments and with reference to the accompanying drawings, in which: 10 15 20 25 30 509 551 I 6A fi g. 1 shows a perspective view of a stack of workpieces which are superplastically shaped and diffusion-bonded to form a number of articles according to the invention, fi g. 2 shows a view in the direction of the arrow A in fi g. 1, fi g. 3 shows a cross section B-B in fi g. 2, fi g. 4 shows a view in the direction of the arrow C in fi g. 1, fi g. 5 shows a perspective view of the stack of workpieces after superplastic forming and diffusion bonding to produce the articles, fi g. 6 shows a perspective view of the articles after partial processing, fi g. 7 shows a perspective view of one of the species after complete processing, fi g. 8 shows an alternative perspective view of a stack of workpieces formed superplastically and diffusion bonded to provide a number of articles according to the present invention, fi g. 9 shows a perspective view of the stack of workpieces in fi g. 8 after superplastic forming and diffusion bonding to form the amples, fi g. 10 shows another alternative perspective view of a stack of workpieces formed superplastically and diffusion bound to provide a number of articles according to the invention, fig. 11 shows a perspective view of the stack of workpieces in fi g. 10 after superplastic formation and diffusion bonding to form the articles, fi g. 12 shows a perspective view of the species in fi g. 11 after partial processing, fi g. 13 shows another alternative perspective view of a stack of workpieces formed superplastically and diffusion bound to form a number of articles according to the present invention,, g. 14 shows a perspective view of the stack of workpieces in fi g. 13 after diffusion binding, fi g. 15 shows a perspective view of the articles in fi g. 14 after partial processing, and fi g. 16 shows a perspective view of one of the articles in fi g. 15 after superplastic molding.

I fi g. 3, two plates 12, 14 of titanium alloy are joined together into a stack 10.

The plates 12, 14 have mating surfaces 16, 18 which are flat. Before joining the plates 12, 14 to the stack 10, the surface 20 of the plate 12 opposite the flat mating surface 16 is machined at a number of predetermined areas 24, which are closed longitudinally of the plate 12 by means of webs 26, according to fi g. 1 and 2.

Each of the machined workpieces 24 corresponds to an outer surface of one of a number of hollow articles, Lex. in the form of compressor blades. Each machined area 24 is designed to effect a variation in the mass distribution of the compressor blade from the leading edge to the trailing edge and from the root to the tip by varying the machining depth, e.g. by varying the thickness of the plate 12 over the machined areas 24 in the direction between the ends 28 and 30 and in the direction between the edges 32 and 34 of the plate 12.

Similarly, the surface 22 of the plate 14 opposite the flat mating surface 18 is machined at a plurality of predetermined areas 36 which are longitudinally spaced apart by the plate 14 (not shown). Each of the machined areas 36 corresponds to the second outer surface of one of the fls of hollow articles. Each machined area 36 is also designed to provide a variation in the mass distribution of the compressor blade from leading edge to trailing edge and from root to tip by changing the machining depth, e.g. by varying the thickness of the plate 14 over the machined areas 36 in the direction between the ends 38 and 40 and in the direction between the edges 42 and 44 of the plate 14.

It should be noted that the distance between the machined areas 36 on the plate 14 is substantially the same as the distance between the machined areas 24 on the plate 12, whereby when the plates 12 and 14 are placed in the stack 10, each machined area 24 is substantially inside a corresponding machined area 36. to fi nier the outside of the hollow articles. There is a slight dormant division X between the corresponding features of the machined areas 24, 36 on adjacent articles. 10 15 20 30 509 351 I 8 The machining of the machined areas 24 and 36 on the plates 12 and 14 takes place by milling, electrochemical machining, chemical machining, electrical discharge machining or other suitable machining process.

The flat mating surfaces 16 and 18 of the plates 12 and 14 are then prepared for diffusion bonding by chemical cleaning. One of the mating surfaces 16 and 18, in this example the mating surface 18, has been provided with an inhibitor material.

The inhibitor may consist of powdered yttrium in a binder and solvent, e.g. the inhibitor known as "Stopytt 62A", sold by a US company named GTE Service Corporation, at 100 Endicott Street, Danvers, MA 10923, USA.

The inhibitor material is applied in desired patterns to each of a number of predetermined areas 46, which are spaced apart longitudinally of the plate 14, as shown in fi g. 1 and 4. The inhibitor material in this example is applied as a block to form a completely hollow article. There is a slight division Y between the corresponding points of the inhibitor material 46 on adjacent articles. The divisions Y and X are substantially equal. The inhibitor material is applied to the mating surface 18 so that when the plates 12 and 14 are placed in the stack 10, each predetermined area 46 is located substantially opposite the corresponding machined areas 24 and 36 on the plates 12 and 14 to adorn the hollow interior of the hollow article. The inhibitor material is applied by the known method of screen printing or by other suitable means. The predetermined areas 46 are interconnected by means of inhibitor material 48 extending longitudinally near an edge.

The two titanium alloy plates 12 and 14 are then joined to the stack 10, as shown in fi g. The plate 12 has a pair of guide holes 50 which are axially aligned with the corresponding guide holes 52 in the plate 14 to ensure the correct mutual position between the two plates 12 and 14 in the stack 10. The plates 12 and 14 are maintained in 10 15 20 9 509 351 this mutual position by means of a pair of guide pins (not shown) which are inserted into the axially aligned guide holes 50 and 52.

The plates 12 and 14 in the stack 10 are brought together so that they clamp at one end of a tube 54. In this example, a groove 56 is received in the surface 16 and a groove 58 in the surface 18. The end of the tube 54 fits in the grooves 56 and 58 and protrudes from the stack 10. The end of the tube 54 connects to the inhibitor material 46 and 48 between the plates 12 and 14.

After the construction is completed as above, it is welded around the periphery to weld together the ends and edges of the plates 12 and 14, and to weld the tube 54 around the periphery to the plates 12 and 14. A first sealed construction is obtained, except for the inlet which is formed. of the tube 54.

At this stage, two titanium blocks 60 and 62 are placed on the stack 10. The titanium blocks 60 and 62 are intended to form the platform and root portions of the compressor blades.

The titanium blocks 60 and 62 are placed against the surfaces 20 and 22 on the plates 12 and 14, respectively, right next to the edges 32 and 42, respectively. The titanium blocks 60 and 62 extend along the entire length of the plates 12 and 14, from the ends 28, 38 to the ends 30, 40. One end of a tube 64 is clamped between the plate 12 and the block 60, and the surface 20 and the block 60 have machined grooves. 66 and 68, respectively, intended to accommodate the tube 64. Similarly, one end of a tube 70 is clamped between the plate 14 and the block 62, and the surface 22 and the block 62 have machined grooves 72 and 74, respectively, for the tube 70. The ends and the edges of the block 60 are welded to the plate 12 and the periphery of the tube 64 is welded to the plate 12 and the block 60 to form a second sealed structure, except for the inlet formed by the tube 64. Correspondingly, the ends and edges are welded on the block 62 fixed to the plate 14 and the periphery of the tube 70 is welded to the plate 14 and the block 62 to form a third sealed structure, with the exception of the inlet constituted by the tube 70. The tubes 54, 64 and 70 is then connected to the valc pumps used to evacuate the interior of the three sealed structures, and then inert gas, for example argon, is introduced into the interior of the three sealed structures. This process of evacuating and supplying inert gas to the interior of the three sealed structures can be repeated fl times to ensure that most, or substantially all, traces of oxygen are removed from the interior of the three sealed structures. The smaller traces of oxygen that remain, the better the quality of the later diffusion bonds.

The three sealed structures are then evacuated and placed in an oven. The sealed structures are then heated to a temperature between 250 ° C and 350 ° C to vaporize the adhesive from the inhibitor material. During baking of the adhesive, the first sealed structure is continuously evacuated to remove the adhesive between plates 12 and 14. After the adhesive has been removed, which is determined either by monitoring the adhesive levels in the gas removed from the first sealed structure or by maintaining it. first sealed structure at the temperature between 250 ° C and 350 ° C for a predetermined time, the sealed structure is removed from the furnace and allowed to cool to ambient temperature while being continuously evacuated.

The adhesive is baked out of the first sealed structure at a suitably low temperature to reduce, or prevent, oxidation of the outer surfaces of the sealed structures.

The pipes 54, 64 and 70 are then sealed so that negative pressure prevails in each of the three sealed structures. The three sealed structures, which are fragile and easy to damage, are then carefully transferred to an autoclave.

The temperature in the autoclave is then increased so that the sealed structures are heated to a temperature exceeding 850 ° C and the argon pressure in the autoclave is raised to more than 20 atmospheres, 294 pounds per square inch (10.26 x 105 N / m 2) and maintained at this temperature. and press for a predetermined period of time. Preferably, 350 n 509 351 the sealed structures are heated to a temperature between 900 ° C and 950 ° C and the pressure is between 294 pounds per square inch (20.26 x 105 N / m 2) and 441 pounds per square inch (30, 39 x IOSN / mz). For example, if the sealed structures are heated to a temperature of 925 ° C and the pressure is raised to 300 pounds per square inch (20.67 x 105 N / m 2), the temperature and pressure are kept constant for about two hours. The pressure is then lowered to ambient pressure, diffusion bonding has been performed and the three sealed structures which thereby formed a one-piece structure are removed.

It is also possible to transfer the sealed structures directly to the autoclave, immediately after the pipes 54, 64 and 70 have been sealed without sea to cool the sealed structures to ambient temperature, but some cooling of the sealed structures may occur.

The tubes 54, 64 and 70 are removed from the one-piece structure and an additional tube is placed in the structure to connect to the inhibitor material 46, 48 applied to the flat surface 18 of the plate 14. Argon, or other inert gas, is introduced into the predetermined areas 46 within the one-piece structure to break the retaining grip caused by the diffusion bonding pressure, something known as "cracking". Breakdown is achieved by introducing high pressure argon gas via this additional pipe to the predetermined areas 46.

The breaking-up operation is carried out especially to ensure that the inlet of the further pipe and the gas duct, which are connected by the grooves 56 and 58 to which it connects, provides an open passage and does not prevent pressurization of the interior of the integral structure. The interior of the structure prior to disintegration is of course initiated by the predetermined areas 46 with inhibitor material.

Breakage can be carried out at room temperature, as the metal has normal elastic properties. Care must be taken to ensure that the elongation that occurs due to the pressurization with argon gas does not exceed the elastic limit. The construction consequently regains its shape when the pressure ceases at the end of the operation. This technique is known as "cold breaking".

Alternatively, breaking up can be performed at the temperature required for superplastic molding. This is known as "heat dissipation". In this case, the plastic deformation of the structure caused by pressurization must be insufficient to cause "ballooning" and that the material becomes thin at and near the inlet of the additional pipe. Whether cold breaking or hot breaking is used is the choice of the manufacturer and depends on the degree of control of the expansion of the structure that can be exercised during pressurization. This is partly due to the geometry and material properties of the structures that are pressurized and partly to the available accuracy in the control of the pressurization. These will inevitably to at least some extent be the subject of experiments for each particular design of the structure which it is desired to manufacture.

Of the two techniques, hot breaking is the more convenient because it can be performed inside the superplastic molds as the first step in the superplastic molding procedure. However, it should only be used if the manufacturer is sure that he can control the process so that excessive plastic deformation is avoided when pressurizing the structure, otherwise breakage of one or more of the plates 12, 14 may occur.

In both hot and cold breakdown, argon gas is introduced at the areas 46, 48, within the one-piece structure, containing the inhibitor material to break the retaining grip that the diffusion bonding process has given rise to. Argon is carefully introduced into the areas provided with inhibitor material, and the argon gas penetrates the inhibitor material and finally reaches all the areas covered by inhibitor material. In some interior constructions, the argon can initially be moved between a pair of workpieces. In any case, the argon should preferably be moved along the entire length of inhibitor material to break the retaining grip between the inhibitor material and the workpieces that has occurred during the diffusion bonding step.

Since the breaking operation is important for the successful execution of the superplastic forming process, it is described in more detail below.

In cold breakage, a sequence of "pulses" of argon is introduced into the additional tube. Each pulse contains a standard volume of gas at a high standard pressure and is inserted into the additional tube gig a valve. After each pulse, or after a predetermined number of pulses, the pressure in the further tube is read at regular intervals for a certain period of time, and the pressure drop in the further tube is observed. At the same time, the thickness of the stack at the area of the gas channels 56, 58, 48 is measured to monitor the expansion due to the applied pressure. If the pressure drop and the expansion values during the determined period of time are within predetermined intervals, the breaking process is considered to have been completed satisfactorily.

In the case of hot breaking, the one-piece construction is held between the molds intended for superplastic molding which are used in the subsequent superplastic molding. The mold parts for the superplastic molding are located in an autoclave. The autoclave is evacuated to avoid contamination of the titanium structure, after which the furnaces and the one-piece structure are heated to the temperature for superplastic forming. A predetermined volume of high pressure argon, or other inert gas, is then introduced into the additional tube via a valve and the pressure drop in the additional tube is observed to monitor the expansion due to the applied pressure. A pressure net or other device is used to measure the pressure in the additional pipe. A pressure drop number exceeding a predetermined value indicates that sufficient expansion has occurred in the gas passage 56, 58, 48 to enable subsequent superplastic expansion by applying additional pressure pulses. 10 15 .20 5 Û 9 3 5 1 14 Completion of the shaping of the one-piece construction into a number of components can now be achieved by the superplastic forming process.

If a hot breaking operation has been performed, the superplastic forming step can be started by introducing argon gas into the interior of the integral structure between the adjacent plates 12, 14 to force the plates 12, 14 into respective mold halves, giving rise to a fl number of hollow areas corresponding to the predetermined areas 46.

If a cold break has been carried out, the one-piece construction is placed between suitably shaped mold halves which are placed in an autoclave.

The autoclave is evacuated to avoid contamination of the titanium structure. The one-piece construction is reheated to temperatures for superplastic forming. Argon is introduced into the interior of the one-piece structure between the adjacent plates 12, 14 to force the plates 12, 14 into respective mold halves, giving rise to a number of hollow regions corresponding to the predetermined areas 46.

The magnitude of the movement of at least one of the plates during the deformation is such that superplastic elongation must occur. The term "superplastic" is a standard term in metal forming technology and is not described in more detail here.

To achieve superplastic molding without tearing the thinning metal, argon is introduced in a series of pulses, at a predetermined rate that achieves a desired elongation rate, as described on pages 615-623 of the book "The Science, Technology and Application of Titanium". written by RI Jaffe and N .E. Prannisel, published by Pergamon press in 1970, which is hereby included in the description. The method ensures that metal is subjected to the strain rate that achieves maximum strain rate at each time during the procedure.

The rate of supply and / or volume of the pulses with gas can thus vary during expansion of the plates. After completion of the superplastic molding, the inert gas is maintained inside the one-piece structure while the structure is cooled to ambient temperature.

After the superplastic forming step, the blocks 60, 62 and adjacent portions of the plates 12 and 14 are machined to provide a plurality of platforms 76 and root portions 78, e.g. salmontail shaped according to fi g. After machining the platforms and the root portions, the one-piece structure is divided into separate compressor blades 86 by machining through each of the frames 80 corresponding to the frame 26, and the final wing profile mold 82 is made by e.g. electrochemical processing. Separation of the blades 86 and shaping of the wing profiles 82 are preferably carried out simultaneously by means of electrochemical processing. This is accomplished by placing the root portions 78 of the blades 86 in holders, while the frame 80 still holds the blades 86 together, after which the holder is connected to one pole of the electrochemical machine. The electrochemical machining electrodes separate the individual wing projections 82 from the entire structure as the electrodes meet at the leading edge and the beam edge of the wing projections 82 on adjacent blades 86, i.e. the electrodes are moved longitudinally along the one-piece construction. The sectional plane between adjacent blades 86 is marked with the reference numeral 84 and extends substantially across the one-piece structure. It is known as 360 ° electrochemical processing of the wing problems. Yet another embodiment of the invention is shown in fi g. 8 and 9, where the difference is that each of the predetermined areas 46 is joined by inhibitor material 48, while adjacent predetermined areas 46A, 46B are not joined. Thus, there are two sets 48A and 48B of inhibitor material running longitudinally on plate 14, but located at opposite edges of plate 14. The predetermined areas 46A are interconnected by inhibitor material 48A, and the predetermined areas 46B are associated with inhibitor material 48B. Yet another difference is that two titanium blocks 60B and 62B are located on the stack 10. These should also form platform and root portions on the compressor blades. Blocks 6OB and 62B are located immediately adjacent the edges 34 and 44 of plates 12 and 14. Blocks 60B and 62B are diffusion bonded to plates 12 and 14 in a manner similar to that described above. During breakdown and superplastic molding, both sets of predetermined regions 46A and 46B are provided with argon gas vi; passages 48A and 48B. After superplastic molding, platforms and roots are machined in both sets of blocks 60, 62 and 6OB, 62B. The individual sheets are then preferably sealed by electrochemical processing. Another embodiment of the invention is shown in fi g. 10, 11 and 12, where the difference is that the plate 12 is machined on a first set of predetermined areas 24A longitudinally spaced for the plate 12 and machined on a second set of predetermined areas 24B separated longitudinally on the plate 12. The two sets of machined areas 24A and 24B are separated transversely of the plate 12.

In the same way, the plate 14 is machined at two sets of predetermined areas (not shown). Furthermore, two sets of predetermined areas 46C and 46D of inhibitor material are applied to the plate 14, according to fi g. 10. Further, the predetermined areas of inhibitor material 46A and 46B are joined by inhibitor material 48 extending longitudinally near the center of the plate 14. The two sets of predetermined areas 46C and 46D with inhibitor material are transversely spaced apart and are arranged on each other. sides of the inhibitor material 48. The titanium blocks 60 and 62 are also located near the center of the plates 12, 14 and extend longitudinally. During breakage and superplastic molding, both sets of predetermined areas 46C and 46D are supplied with argon gas from the passageway they are annealed by the inhibitor material 48. After superplastic molding, blocks 60, 62 and plates 12 and 14 are processed longitudinally along the plane 90, as shown in fi g. ll, to divide the one-piece construction into two halves, according to fi g. 12. The roots and platforms are processed from blocks 60, 62 and the individual blades are then preferably separated by electronuclear processing. 10 15 20 30 17 5Ü9 351 According to an alternative method, the stack is prepared in the same way as previously described in connection with ñg. 1-7. The stack is then placed in a vacuum chamber. The vacuum chamber is then evacuated to evacuate the interior of the stack between the plates and to evacuate the areas between the blocks and the plates. The vacuum chamber is then filled with argon to clean the interior of the stack, and then evacuated again to remove oxygen. The vacuum chamber is heated to remove adhesive from the inhibitor material while the vacuum chamber is continuously evacuated to remove the adhesive between the plates and from the vacuum chamber. After the adhesive has been removed, the ends and edges of the plates are welded together, and the edges of the blocks are welded to the plates, for example by means of an electron beam to provide a sealed structure as described in our British Patent No. 2,256,389B, the contents of which are hereby incorporated by reference. .

Then diffusion bonding, superplastic molding and other steps as previously described take place. Another variant of the invention, shown in fi g. 13-16, is suitable for the manufacture of blad sprigs with a long cord. According to this variant, three titanium plates 112, 114 and 116 are joined to a stack 110 together with the blocks 160 and 162. The two outer plates 112, 116 have machined areas 124, while each of the areas 146 is covered with inhibitor material in a certain pattern to allow diffusion along one or fl your lines, at a plurality of circular areas or a combination of lines and circles or other suitable patterns. The process is the same as before until after diffusion bonding, after which the one-piece structure is machined transversely along the plane 130 at the frame 180 as shown in fi g. 14 to separate the individual leaves. Each blade is then placed in a twisting device of the type described in our British Patent No. GB 2,073,631B, the contents of which are hereby incorporated by reference. One end of the blade, e.g. the end with the blocks 160 and 162 is placed between a pair of mutually movable molds. The opposite end of the blade is placed in a slot in a rotatable part. The blade is then heated to 800 ° C and a load is applied to the end of the blade held in the molds to create a curvature at that end. After the curvature has been achieved at one end of the blade, the opposite end of the blade located in the slot is rotated by means of the rotatable part so that the blade is rotated to substantially the desired shape for the molds used for the superplastic the forming process. Thereafter, each of the blades is formed superplastically, and on each blade a root and a platform are processed from the blocks and the wing tip pair is machined to the correct shape. The blades can be shaped superplastically in turn individually or simultaneously in a set with enheter your units. Yet another possibility of producing fl leaflets with little rotation and curvature is to superplastically form the one-piece construction to provide a plurality of hollow areas. The blocked end of the superplastically shaped, integral structure is curved to provide the arch at the root of the spikelets. The one-piece construction is then machined to provide slits extending transversely at the frame between wing profile portions on adjacent spores to separate the wing profile portions, but the roots, i.e. the blocked end of the one-piece structure, on adjacent blad marriage leaves remains in one piece. The ends of the ends of the wing tubes which are located at a distance from the roots, i.e. the blocked ends of the one-piece structure are then rotated. After rotation of the wing tubes, the roots and platforms are processed from the blocks while the individual sprigs are separated, after which the wing tubes are processed electrochemically to the correct shape, or the wing tubes can be processed into the correct shape and then the roots and platforms can be processed from the individual blocks to separate .

Another possibility of producing long cord cords is to vault the blocked end of the one-piece structure to bring about the arching of the roots of the cotyledons. The one-piece construction is then machined to form slits extending transversely at the frame between the wing profile portions on adjacent blad leaf blades to separate the wing profile 10 l- 10 15 20 25 19 509 351 portions, but the blocks on nearby fl entire leaf blades remain. The ends of the wing tubes facing away from the roots, ie. the blocked ends of the one-piece structure are then rotated. After rotation of the wing profile parts, the one-piece construction is formed superplastically to create fl your hollow areas. After superplastic molding of the one-piece structure, the roots and platforms are processed from the blocks while the individual ones are separated, after which the wing profiles are processed into the desired shape by electrochemical means, or the wing profiles can be processed into the desired shape after which the roots and platforms are processed. individual kt marriage leaves.

It would be possible to use another variation of the invention, similar to the one in fi g. 10, 11 and 12, but where each plate has two sets of machined areas separated in the transverse direction of the plate, and two sets of predetermined areas of inhibitor material are applied to one of the plates. But metal blocks are located at both edges of the plates and extend longitudinally.

It would be possible to define the plurality of predetermined spaced apart areas on at least one of the surfaces of at least one of the at least two metal workpieces by providing recesses at these areas, instead of applying inhibitor material, but it is preferred to apply inhibitor material. If recesses are made in the surfaces which fit against each other and abut each other in the stack, it need not be necessary to machine areas on opposite surfaces of the workpieces. The heating and pressurizing step again inflates the hollow interior of the articles to the desired shape rather than superplastically shaping the hollow interior of the articles. Alternatively, inhibitor material may be applied to the recesses to prevent diffusion binding.

It may be possible to turn the workpieces in advance instead of using flat workpieces, and to then follow the same process steps. 10 15 20 509 351 20 The invention produces a number of hollow blades at the same time from a minimum number of metal pieces. The invention also processes the roots of the hollow leaves while the hollow leaves are all interconnected. The invention produces the final wing profile shapes on the compressor blades by simultaneous electrochemical machining of a plurality of hollow blades.

The invention can also be applied to cost-effective mass production of large numbers of identical, or similar, hollow articles by superplastic forming and diffusion bonding of superplastically extensible and diffusion bondable metal workpieces. These workpieces include base metal, metal alloys, antenna metal materials and metal matrix composites. For example, aluminum and stainless steel can be stretched superplastically at appropriate temperatures and pressures.

It is also possible to use more than three plates in a stack, depending on the particular article to be produced.

The invention has been described with reference to metallurgical diffusion bonding, or diffusion bonding in solid form, where the joint between the workpieces effectively disappears, but under conditions where diffusion bonding between the workpieces need not be as strong as in diffusion bonding in solid form it is possible to use activated diffusion bonding. When diffusion binding is activated, an activator is placed, such as e.g. a metal foil, between the surfaces to be bonded.

During the bonding process, the activator material, when it reaches a certain temperature, transiently forms a surface phase which forms an alloy with the workpieces. This solidifies immediately to effect bonding.

The invention is also applicable to the production of hollow compressor guide rails and hollow guide rails at the travel outlet. The invention is also applicable to the production of heat exchanger panels where the heat exchanger panels are separated from the one-piece construction and then stacked and diffusion bonded or bonded together by means of activated diffusion bonding to provide a heat exchanger. The invention can obviously also be used for the production of other articles, components or subcomponents.

Claims (37)

10 15 20 509 351 22 Patentlcrav A method of making hollow articles (86) by superplastic molding and diffusion bonding of at least two metal workpieces (12, 14), comprising the steps (a) defining a number of mutually spaced predetermined areas (46) on at least one of the surfaces ( 18) on at least one of the two metal workpieces (12, 14) to prevent diffusion bonding at the predetermined areas (46), each predetermined area (46) corresponding to the hollow interior of one of a number of hollow articles (86), (b) joining the at least two workpieces (12, 14) to a stack (10), (c) applying heat and pressure over the thickness of the at least two workpieces (12, 14) to diffusion bond the at least two workpieces at areas other than said plurality of spaced apart predetermined areas (46) to provide a one-piece structure, (d) heating and internal pressurization of the predetermined areas (46) to bring the predetermined the areas (46) being formed superplastic to provide a plurality of hollow articles (86) of predetermined shape, and a further step of dividing the integral structure between said plurality of mutually spaced, predetermined areas (46) to provide a fl number of articles (86), the additional step being performed between steps (c) and (d) or after step (d). The method of claim 1, wherein step (a) comprises applying an inhibitor material to prevent diffusion binding at each of said fl number of mutually spaced, predetermined areas (46). A method according to claim 2, wherein each of the at least two metal workpieces (12, 14) has at least one flat surface (16, 18), and wherein the inhibitor material is applied to at least one of the flat surfaces (16, 18) and the at least two workpieces (12, 14) are joined together into a stack (10) relative to each other so that the flat surfaces (16, 18) fit against and abut each other. A method according to any one of claims 1-3, including machining at least one of the at least two metal workpieces (12, 14) on a plurality of mutually spaced predetermined areas (24, 36), the machined areas (24, 36) refers to the surfaces (20, 22) located opposite the surfaces (16, 18) to be diffusion bonded, each machined area (24, 36) corresponding to an outer surface of one of the number of hollow articles (86), the machined areas (24, 36) have a varying mass distribution. A method according to any one of claims 1-4, wherein heating and internal pressurization of the predetermined areas (46) for the purpose of superplastically forming the predetermined areas (46) to produce the hollow articles (86) of predetermined shape is performed before dividing the integral construction between the tal number of mutually spaced, predetermined areas (46) to provide the fl number of hollow articles (86). A method according to claim 5, including machining an edge of the integral structure to provide a plurality of root portions (78) after heating and pressurizing the plurality of predetermined areas (46) to superplastically form the predetermined areas ( 46) to provide the hollow articles (86) of predetermined shape and to divide the integral construction between the fl number of predetermined areas (46) to produce the tal number of hollow articles (86). A method according to claim 6, wherein after dividing the one-piece structure to provide the number of hollow articles (86), the remaining outer surface portion (82) of each of the articles (86) is machined into a wing profile. 10 15 20 509 551 24 A method according to claim 6, wherein dividing the one-piece structure to provide the number of hollow articles (86) comprises simultaneously machining the remaining outer surface portion of the one-piece structure into a number of wings (82) with wing profile shape. . A method according to claim 5, including partial separation of the hollow articles (86) by providing slits from a first edge of the integral structure between the mutually spaced, predetermined areas (46), heating the integral one piece. the construction and application of loads on opposite ends of each of the fl number of articles to rotate one end relative to the other end in order to give each article (86) a predetermined shape after superplastic shaping of the mutually separated predetermined areas (46) for to produce the hollow articles (86) of predetermined shape and before dividing the one-piece construction. The method of claim 9, including machining the edge opposite the first edge of the one-piece structure to separate the articles (86) and to provide a plurality of root portions (78). A method according to claim 10, including after machining the root portions (78) machining the twisted outer surface portion (82) on each of the articles (86) to wing profile shape. The method of claim 9, including machining the twisted outer surface portion of each of the articles (86) into the wing profile (82). A method according to claim 12, including after machining the twisted outer surface into a wing profile (82) machining the edge opposite the first edge of the integral structure to separate the particles (86) and to form a plurality of root portions (78). ). 10 15 20 25 30 25 509 351 A method according to claim 5, including partial stripping of the articles by providing slits from a first edge of the integral structure between the spaced apart predetermined areas (46), heating the integral structure and applying loads to opposite ends of each of the fl number of articles to rotate one end relative to the other end in order to give each article a predetermined shape after diffusion bonding of the workpieces (12, 14) to form the one-piece structure and before superplastic forming of the separate predetermined areas (46) for producing the hollow articles (86) of predetermined shape and dividing the one-piece structure. The method of claim 14, including prior to partial separation of the articles (86) applying loads to the edge opposite the first edge of the one-piece structure to arch the edge. A method according to claim 15 or 15, including machining the edge opposite the first edge of the one-piece structure to separate the articles (86) and to provide a plurality of root portions (78). A method according to claim 16, including after machining the roots (78) machining the twisted outer surface portion (82) on each of the articles (86) to wing profile shape. A method according to claim 14 or 15, including machining the twisted outer surface portion of each of the articles (86) into the wing profile (82). A method according to claim 18, including after machining the twisted outer surface into a wing profile (82), machining the edge opposite the first edge of the integral structure to separate the articles (86) and to provide a number of root portions ( 78). 10 15 20 25 30 509 551 26 A method according to any one of claims 1-4, wherein dividing the one-piece structure between the fls of mutually defined, predetermined areas (46) to provide the plurality of articles (86) precedes heating and internal pressurization of the plurality of predetermined areas ( 46) to cause the predetermined areas to be superplastically formed to provide the hollow articles (86) of predetermined shape. A method according to claim 20, including heating each of the number of articles (86) and applying loads to opposite ends of each of the number of articles (86) to rotate one end relative to the other end to shaping each article (86) into a predetermined shape after dividing the one-piece structure into a plurality of articles (86) and before heating and pressurizing the tal number of predetermined areas (46) to superplastically shape the predetermined areas (46) for to provide the hollow articles (86) of predetermined shape. A method according to claim 21, including prior to rotating the opposite ends of each article (86) heating and applying loads to one end of each article to arch said ends. The method of claim 22, including machining the curved end of each article to form a root portion (78). A method according to any one of claims 21-23, including machining the remaining outer surface portion of each article (86) into a wing profile (82). A method according to claim 7, 8, 11, 12, 17, 18 or 24, wherein machining of the outer surface of the article (86) to wing profile shape takes place by electrochemical means. The method of claim 25, wherein the electrochemical machining includes triangulation of the electrochemical machining electrodes. 10 15 20 25 3-3 27 509 351 A method according to any one of claims 1 to 26, wherein the number of mutually spaced predetermined areas (46) are longitudinally spaced for the workpieces (12, 14). A method according to claim 27, wherein at least some of the fl number of mutually spaced predetermined areas (46C, 46D) are spaced in the transverse direction of the workpieces. A method according to any one of claims 1-28, wherein at least one metal block (60, 62) is joined to the at least two workpieces (12, 14) of metal into a stack (10) so that said metal block (60, 62) is located at a first edge of the stack (10), after which said metal blocks (60, 62) are diffusion bonded to the metal workpieces (12, 14). A method according to claim 29, wherein two metal blocks (60, 62) are applied at the first edge of the stack (10), at opposite surfaces of the stack (10). A method according to claim 29 or 30, wherein at least one other metal block (60B, 62B) is joined to the at least two metal workpieces (12, 14) and said at least one metal block (60, 62) to a stack (10), so the at least one metal block (60, 62) being located at a first edge of the stack (10) and the second metal block (60B, 62B) being located at the opposite edge of the stack (10), after which the metal blocks (60, 60B, 62, 62B) diffusion bonded to the metal workpieces. A method according to any one of claims 1-28, wherein at least one metal block (60, 62) is joined to the at least two metal workpieces (12, 14) into a stack (10) so that said at least one metal block (60, 62) is located at a central area of the stack (10), after which the at least one metal block (60, 62) is diffusion bonded to the metal workpieces (12, 14). A method according to claim 31, wherein two metal blocks (60, 62) are applied to the central area of the stack (10) and to opposite surfaces of the stack (10). 10 509 351 ß A method according to claim 32 or 33, including machining the one-piece structure longitudinally through the center of said at least one metal block (60, 62). A method according to any one of claims 1 to 34, wherein the article (86) is a blade or guide rail of a gas turbine engine. A method according to any one of claims 1-34, wherein the article (86) is a heat exchanger panel for a heat exchanger. A method according to any one of claims 1-36, wherein the diffusion bond is activated diffusion bond.