WO2015035894A1 - Method for producing profile for aircraft wing stringer - Google Patents

Abstract

A method for producing an aluminum alloy profile for a stringer of an aircraft wing comprises: determining the composition of an aluminum alloy, and calculating required quantity of raw materials according to the determined composition of the aluminum alloy; melting and refining the raw materials, to produce a molten aluminum alloy material; performing spray forming in a double-nozzle spray forming device, to form a billet; after the billet is formed, performing backward extrusion on the billet in a backward extruder, to form an aluminum alloy profile.

Description

Method for producing profiles for aircraft wing lengths Technical field

The present invention relates to a method of producing a profile for a long wing of an aircraft wing, and more particularly to a method of producing a long wing of a wing using an aluminum alloy such as 7055 aluminum alloy.

Background technique

The wing long raft is a key load-bearing structural part in the wing of the aircraft. Therefore, there are high requirements for the materials selected for the manufacture of the long wing of the wing. The indicators involved include comprehensive mechanical properties, fatigue properties, and corrosion resistance. Wait.

7055 aluminum alloy is the most strong alloy in the current deformed aluminum alloy, so in many occasions 7055 aluminum alloy is used to produce the long wing of the wing. For the production of wing long rafts, the 7055 aluminum alloy profile is required to have a large thickness. The main features of 7055 aluminum alloy are high strength, good fracture toughness and strong fatigue crack growth resistance, and the alloy has good resistance to intergranular cracking and corrosion.

At present, the production process of the profile for the long wing of the wing is: first, the ingot of the profile is produced by a casting process; and then, the profile having the specified shape and specification is produced by a forward extrusion process.

However, for the 7055 aluminum alloy, since it has a high strength, there is a problem in applying the above production process to the 7055 aluminum alloy.

First of all, from the perspective of the process of casting aluminum ingots, since the content of 7055 alloy is the highest in existing high-strength aluminum alloys, there will be structural defects caused by slow solidification during the casting process, which is prone to severe macrosegregation and coarseness. The grain and alloy phases have a strong tendency to crack. Therefore, the casting difficulty of the 7055 aluminum alloy is the largest among all aluminum alloys. Moreover, defects generated during the casting process may affect subsequent molding processability and mechanical properties;

Secondly, from the viewpoint of the extrusion forming process, there is a large frictional force between the ingot and the extrusion cylinder during the forward extrusion, and this frictional force causes metal flow and deformation unevenness, thereby It is difficult to guarantee the consistency of product organization. At the same time, the surface of the ingot is severely sheared and deformed when the metal is deformed, and a large coarse crystal ring is easily formed.

At present, for the domestic, the composition control, casting process, and type of 7055 aluminum alloy profiles have not yet been mastered. The key technologies in various aspects such as material extrusion and heat treatment process, the profiles produced by the traditional production process can not meet the needs of the long wing of the aircraft. At the international level, only the aluminum industry can produce such aluminum alloy profiles. However, due to the difficulty of casting the 7055 aluminum alloy, there are problems in the yield and stability of the product.

Therefore, in the field of aircraft manufacturing, there is a need for an improved method of producing a long wing of a wing, especially a 7055 aluminum alloy for producing a long wing of a wing.

Summary of the invention

The present invention has been made to solve the above problems in the prior art, and an object thereof is to provide a method for producing a profile for an aircraft wing long raft, in particular to use a 7055 aluminum alloy to produce the profile, which can reduce the casting ingot. The homogenization process of the billet saves production time and cost, and solves the problem of inconsistency of serious coarse crystal ring and mechanical properties brought about by the forward extrusion process, so that the comprehensive performance of the material can meet the technical requirements of the long wing of the wing.

The method for producing an aluminum alloy profile for aircraft wing length according to the present invention comprises the steps of: a. determining the composition of the aluminum alloy, and calculating the amount of the raw material according to the determined aluminum alloy composition; b. melting and refining the raw material to Forming a molten aluminum alloy material; c. performing spray forming in a two-nozzle spray forming apparatus to form a billet; and d. after forming the billet, inverting the billet in a reverse extruder to Forming an aluminum alloy profile.

By optimizing the composition of the alloy and using the spray forming process to produce the billet of the aluminum alloy, the microstructure of the billet is fine and uniform, thereby improving the overall performance of the profile. In addition, by using the reverse extrusion technology, the coarse crystal ring defects of the material structure can be reduced, the surface quality of the profile can be improved, and the consistency of the mechanical properties of the head and the tail of the extruded profile can be improved.

Preferably, the method further comprises at least one of the following steps: e. turning and pre-extruding the ingot between steps c and d; f. after step d, solidifying the aluminum alloy profile Heat treatment and stress relief; g. After step d, the aluminum alloy profile is subjected to two-stage aging treatment; and h. after step d, the aluminum alloy profile is straightened.

In the present invention, the optimized aluminum alloy composition is as follows: Si ≤ 0.08%, Fe ≤ 0.12%, Cu 2.2 to 2.5%, Mn ≤ 0.5%, Mg 1.8 to 2.1%, Cr ≤ 0.4%, Zn 7.8 ～8.2%, Ti≤0.06%, Zr0.10～0.13%, the total amount of other impurities is not more than 0.15%, and the balance is aluminum.

Preferably, the dual nozzle spray forming device comprises: a deposition chamber in which the spin chamber is provided with a rotatable a hoistable collector having a deposition tray; and a leakage pack containing a molten aluminum alloy material, and the leakage package is provided with at least one nozzle; wherein at least one nozzle sprays the molten aluminum alloy material to the deposition tray of the collector, The molten aluminum alloy material solidifies on the deposition disk, and while being sprayed, the collector rotates and descends to form a billet on the deposition tray of the collector.

In the reverse extrusion process, the extruder has a barrel temperature of 380 to 420 ° C and a reverse extrusion speed of 3 to 5 mm/min.

During the injection molding process, at least one of the following parameters may be included: the injection temperature of the molten aluminum alloy material is in the range of 685 to 710 ° C, the drain liquid level is controlled to be 200 to 540 mm, and the diameter of the nozzle opening may be 5 to 10 mm. The spray height of the nozzle is 350-700 mm, the rotation speed of the deposition disk of the collector is 35-200 rpm, the descending speed of the collector is 10-60 mm/min, and the swing angle of the nozzle can be 4-10, and the swing frequency thereof It is 2 to 20 Hz, and the atomization pressure of the aluminum alloy to be ejected is 0.5 to 1.5 MPa.

Preferably, the solution heat treatment comprises: raising the profile blank from room temperature to 400-460 ° C for 2 hours, and then holding the profile for 0.5 hour; then, for 0.5 hour, increasing the profile blank temperature to 460-480 ° C. And the temperature is kept at this temperature for 1 hour; then, the profile blank is subjected to water quenching; finally, the temperature of the billet before entering the water is controlled at 460 to 480 ° C, the quenching water temperature is 40 to 45 ° C, and the quenching time is 0.5 hour.

Preferably, the two-stage aging treatment comprises: heating the profile from room temperature to 110-130 ° C for 1.5 hours, and maintaining the temperature for 6 hours; then, for one hour, raising the profile temperature to 150-170 ° C, and The temperature was kept at this temperature for 6.5 hours. After the end of the holding, the profile was cooled to room temperature.

Through solution heat treatment, two-stage aging treatment and optimization of pre-stretching, material stress can be effectively eliminated and the corrosion resistance of the material can be improved.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view showing a dual nozzle spray forming apparatus for forming an aluminum alloy ingot in the method for producing an aircraft wing long raft profile of the present invention.

Fig. 2A shows the microstructure of a billet formed by spray forming.

Figure 2B shows the microstructure of the ingot formed by the casting process.

Figures 3A and 3B show the flow of billet material flow in two reverse extruders and their extrusion processes, respectively. intention.

Figure 4A is a photograph of a fractured low magnification of a profile produced by reverse extrusion.

Figure 4B is a photograph of a fractured low magnification of a profile produced by forward extrusion.

detailed description

Hereinafter, preferred embodiments of the present invention will be specifically described. It should be understood that those skilled in the art can make various equivalents of the details of the disclosed embodiments, and such equivalent transformations are also within the scope of the claimed invention.

Next, a method of producing an aircraft wing long 桁 profile of the present invention will be specifically described.

<raw material smelting>

First, the amount of the aluminum ingot, the intermediate alloy, and the pure metal alloy is calculated according to the aluminum alloy composition optimization adjustment scheme, and the raw material is smelted in a furnace such as an intermediate frequency furnace. Among them, the calculation of the composition of the aluminum alloy is based on the data of the composition of the 7055 aluminum alloy. The composition of the 7055 aluminum alloy used in the present invention is specifically as follows: Si ≤ 0.08%, Fe ≤ 0.12%, Cu 2.2 to 2.5%, Mn ≤ 0.5%, Mg 1.8 to 2.1%, Cr ≤ 0.4%, Zn 7.8 ～8.2%, Ti≤0.06%, Zr0.10～0.13%, the total amount of other impurities is not more than 0.15%, and the balance is aluminum. The percentages herein regarding the composition of the aluminum alloy refer to the weight percentage.

After determining the amount of each raw material, these raw materials are melted for later refining processes. The melting of the raw material can be carried out in an intermediate frequency furnace, and the melting temperature is, for example, in the range of 680 to 750 °C.

After the melting is completed and before the raw material is further refined, the molten raw material is preferably sampled and analyzed to ensure that the composition of the aluminum alloy meets the requirements. If the analysis results show that the aluminum alloy composition does not meet the requirements, the alloy composition needs to be adjusted until the alloy composition meets the requirements. Thereafter, the molten aluminum alloy is transferred from the intermediate frequency furnace to the tundish. Refine in the tundish, degas and slag. The refining temperature in the tundish is in the range of 680 to 750 °C. The aluminum alloy may be brought to the above refining temperature prior to transferring the molten aluminum alloy from the intermediate frequency furnace to the tundish and subjected to a transfer operation at the refining temperature, or the aluminum alloy may be brought to the refining temperature after transfer to the tundish. The refining time can be 5 to 15 minutes. Then, the heat preservation and standing are carried out, and the heat preservation temperature can be 680 to 730 ° C, and the heat preservation time is 10 to 30 minutes.

<Jet Forming>

After melting, refining or keeping the aluminum alloy raw material, preparing aluminum in the spray forming device Alloy (such as 7055 aluminum alloy) billet.

The structure of a two-nozzle injection molding apparatus is schematically shown in FIG. As shown in Fig. 1, the dual nozzle spray forming apparatus 1 has a leaky pack 2 disposed at the top of the deposition chamber 8, and at the bottom of the leaky pack 2, at least one nozzle is disposed. In the apparatus shown in Fig. 1, an inner nozzle 3 and an outer nozzle 4 are provided which spray a molten aluminum alloy into the deposition chamber 8. Corresponding to the inner nozzle 3 and the outer nozzle 4, an inner nozzle scanning frequency conversion motor 5 and an outer nozzle scanning frequency conversion motor 6 are provided to control the operations of the inner nozzle 3 and the outer nozzle 4. Inside the deposition chamber 8, a liftable and rotatable collector 7 is provided, and the molten aluminum alloy sprayed from the inner nozzle 3 and the outer nozzle 4 will solidify on the collector 7 and form a billet.

The spray forming process is specifically as follows: The refined and insulated molten aluminum alloy is transferred to the leak bag 2. Preferably, the amount of molten aluminum alloy in the leak bag 2 can be controlled by a leak level automatic control system (not shown). The preferred range of the leaking liquid level is 200 to 540 mm. Then, the molten aluminum alloy is sprayed onto the deposition tray of the collector 7 through the inner nozzle 3 and the outer nozzle 4 at the bottom of the leak bag 2. The injection temperature of the molten aluminum alloy to be sprayed may be in the range of 685 to 710 °C. During the spraying, the collector 7 is rotated and simultaneously lowered to form a cylindrical billet on the deposition tray of the collector 7. Further, during the spraying, the inner nozzle 3 and the outer nozzle 4 are oscillated under the action of the inner nozzle scanning inverter motor 5 and the outer nozzle scanning inverter motor 6 to adjust the shape of the formed billet.

The parameters of the dual nozzle spray forming apparatus 1 and its injection forming operation can be optimized. For example, the diameter of the nozzle opening may be 5 to 10 mm, the ejection height of the nozzle is 350 to 700 mm, the rotation speed of the deposition tray of the collector is 35 to 200 rpm, and the descending speed of the collector is 10 to 60 mm/min, and the swing angle of the nozzle It can be 4 to 10°, and its swing frequency is 2 to 20 Hz, and the atomization pressure of the sprayed aluminum alloy is 0.5 to 1.5 MPa. Under this process parameter, the specification of the 7055 round ingot by injection molding is (Φ500±30mm)×1600mm. The above process parameters can be adjusted according to the desired billet specifications.

Compared with the 7055 aluminum alloy formed by casting, the microstructure of the resulting ingot is more uniform by the above optimization of the alloy composition and the spray forming process. The microscopic metallographic structure of the ingots formed by the two forming processes is compared in Figures 2A and 2B. 2A shows the microstructure of the ingot formed by spray forming, and FIG. 2B shows the microstructure of the ingot formed by the casting process (such as semi-continuous casting). By comparison, the microscopic metallographic structure of the aluminum alloy formed by spray forming is finer than that of the cast aluminum alloy, and is equiaxed and has an average grain size. Degree <30 μm. Such metallographic structure is more conducive to solving the defects of thermal cracking and component segregation, and can improve the hot and cold processing properties of the material as well as the comprehensive properties such as strength, toughness and plasticity. It can be seen from inspection that the overall performance of the billet formed by the spray forming process exceeds the requirements of the American Aeronautical Material Standard (AMS4336). The overall performance of the ingots produced in accordance with the present invention is compared to the standard of AMS 4336 in Table 1. It can be seen that the ingot of the present invention meets or exceeds the AMS 4336 standard in terms of various parameters.

Table 1

<Blank turning and pre-extrusion>

After forming the ingot, in order to better reversely compress the ingot, optionally, the ingot can be turned prior to the reverse pressing of the ingot. For example, for the above-mentioned billet having a diameter of Φ500, its outer circumference can be turned to Φ480, and its surface roughness is not more than Ra12.5.

After turning the ingot, the turned ingot can also be heated, for example to 400-450 ° C, and held at this temperature for 2 to 3 hours. The heated pellet was then pre-extruded to Φ 320 mm, the extrusion ratio was 5, and the extrusion temperature was 430-460 °C.

<reverse extrusion>

After forming the ingot, the ingot is reverse extruded by a reverse extruder to form a profile blank for use as a long wing of the wing.

Figures 3A and 3B show schematic views of the two reverse extruders and the flow direction of the billet material during extrusion, respectively. As shown in Figs. 3A and 3B, during the pressing, the pressing shaft 20 pushes the ingot 10 to advance the ingot 10 in the pressing direction A toward the extrusion die 30, thereby forcing the metal from the hole of the extrusion die 30. The flow is made in the opposite direction of the extrusion die 30 to form the extruded article 40.

In the present invention, the reverse extruder used may be a 45 MN double action reverse extruder.

During the extrusion process, the ingot needs to be heated to impart rheological properties. Preferably, In the reverse extrusion process of the present invention, the ingot is first heated to 400 to 460 ° C and held at this temperature for 2 to 3 hours. The heated ingot is then loaded into a reverse extruder and reverse extruded. The various parameters of the extruder can be selected based on the specific product being produced and the specific process requirements. For example, in an application for producing a long wing of an aircraft wing, the extruder has the following process parameters: a diameter of the extrusion cylinder of φ320 mm, a temperature of the extrusion cylinder of 380 to 420 ° C, and a reverse extrusion speed of 3 to 5 mm. /minute. In addition, the working belt width of the extruder die can be ≤ 5 mm.

Compared to forward extrusion, the depth of the coarse ring defect of the profile formed by reverse extrusion is much lower than the depth of the coarse ring of the forward extrusion. Photographs of the fractures of the profiles produced by reverse extrusion and forward extrusion are shown in Figures 4A and 4B, respectively.

In addition, the head and tail properties of the profiles produced by reverse extrusion and forward extrusion were compared in Table 2. It can be seen that the head and tail properties of the profile formed by reverse extrusion are relatively consistent, and it has better overall performance uniformity. It can be seen from Table 2 that the head and tail mechanical properties of the profile of the present invention are consistent by >94%, which satisfies the requirements for use of the aircraft wing.

Table 2

<Solution heat treatment and stress relief>

After forming the blank of the aluminum alloy profile, it is preferably subjected to solution heat treatment and stress relief. The main steps are as follows.

After 2 hours, the profile blank was raised from room temperature to 400 to 460 ° C, and thereafter held for 0.5 hour. Next, the profile blank temperature was raised to 460 to 480 ° C over a period of 0.5 hours, and held at this temperature for 1 hour. Next, the profile blank is subjected to water quenching. The temperature of the billet before entering the water is controlled at 460 to 480 ° C, the quenching water temperature is 40 to 45 ° C, and the quenching time is 0.5 hour.

Next, the profile material is pre-stretched in a length direction of 0.5 to 3% for the permanent deformation of the profile material. Eliminates residual stresses generated during extrusion and quenching. This pre-stretching can be performed using, for example, a 2000T tension leveler.

<Double-level aging treatment>

Additionally, after the process steps disclosed above, the process of the present invention also includes a process of two-stage aging treatment of the profile. The process is as follows: the profile is insulated for 6 hours at a primary aging temperature (110 to 130 ° C). The profile was then held at the secondary effective temperature (150-170 ° C) for 6.5 hours. The specific process of the above two-stage aging treatment is to raise the profile from room temperature to 110-130 ° C for 1.5 hours, and then hold it at this temperature for 6 hours; then, for 1 hour, the profile temperature is raised to 150-170 ° C, and This temperature was kept for 6.5 hours. After the end of the holding, the profile was cooled to room temperature.

<straightening>

Alternatively, the profile blank can be straightened after the pre-stretching and aging treatments have been carried out based on the actual dimensions of the profile. This straightening can also be carried out by the 2000T tension leveler mentioned above.

<effect>

It has been verified that the chemical composition, room temperature stretching, room temperature compression, electrical conductivity, anti-flaking corrosion and other performance indexes of the aluminum alloy (specifically 7055 aluminum alloy) profiles produced by the method of the invention all meet the requirements of AMS4436 material standard and aircraft design. . In addition, the performance data of multi-batch samples were statistically analyzed, and the tensile yield strength, tensile strength, compressive yield strength, and electrical conductivity satisfied that “the coefficient of variation within the same furnace was less than 3%, and the coefficient of variation between furnaces was less than 5”. %" requirement. Therefore, the aluminum alloy profile produced by the method of the present invention meets the requirements of the aircraft wing length.

Claims (9)

1. A method for producing an aluminum alloy profile for an aircraft wing long raft, characterized in that the method comprises the following steps:

   a. determining the composition of the aluminum alloy, and calculating the amount of the raw material according to the determined aluminum alloy composition;

   b. melting and refining the raw material to form a molten aluminum alloy material;

   c. performing injection molding in a dual nozzle spray forming apparatus to form a billet;

   d. After forming the ingot, the ingot is reverse extruded in a reverse extruder to form an aluminum alloy profile.
2. The method of claim 1 wherein said method further comprises at least one of the following steps:

   e. between step c and step d, turning and pre-squeezing the ingot;

   f. after step d, the solution heat treatment and stress relief of the aluminum alloy profile;

   g. after step d, the aluminum alloy profile is subjected to two-stage aging treatment;

   h. After step d, the aluminum alloy profile is straightened.
3. The method according to claim 1, wherein said aluminum alloy composition is as follows: Si ≤ 0.08%, Fe ≤ 0.12%, Cu 2.2 to 2.5%, Mn ≤ 0.5%, Mg 1.8 to 2.1%, Cr ≤0.4%, Zn 7.8 to 8.2%, Ti ≤ 0.06%, Zr 0.10 to 0.13%, the total amount of other impurities is not more than 0.15%, and the balance is aluminum.
4. The method of claim 1 wherein said dual nozzle spray forming apparatus comprises:

   a deposition chamber in which is disposed a rotatable and liftable collector, the collector having a deposition tray;

   Leaking a bag, the leak bag containing the molten aluminum alloy material, and the leak bag is provided with at least one nozzle;

   Wherein the at least one nozzle sprays the molten aluminum alloy material to the deposition tray of the collector, the molten aluminum alloy material solidifies on the deposition tray, and, while being sprayed, the collector Rotating and descending to form the ingot on the deposition tray of the collector.
5. The method according to claim 1, wherein during said reverse extrusion, said extruder has a temperature of 380 to 420 ° C and a reverse extrusion speed of 3 to 5 mm. /minute.
6. The method according to claim 1, wherein at least one of the following parameters is included in step c: the injection temperature of the molten aluminum alloy material is in the range of 685 to 710 ° C, and the drain liquid level is controlled at 200 to 540 mm, the diameter of the nozzle opening can be 5 to 10 mm, the ejection height of the nozzle is 350 to 700 mm, the rotation speed of the deposition disk of the collector is 35 to 200 rpm, and the descending speed of the collector is 10 to 60 mm/min. The swing angle may be 4 to 10°, and the swing frequency thereof is 2 to 20 Hz, and the atomization pressure of the sprayed aluminum alloy is 0.5 to 1.5 MPa.
7. The method according to claim 2, wherein said two-stage aging treatment comprises: heating the profile from room temperature to 110 to 130 ° C for 1.5 hours, and holding at this temperature for 6 hours; and then, for 1 hour, The profile was allowed to warm to 150-170 ° C and held at this temperature for 6.5 hours. After the end of the holding, the profile was cooled to room temperature.
8. The method according to claim 2, wherein the solution heat treatment comprises: raising the profile material from room temperature to 400 to 460 ° C for 2 hours, and then holding the profile for 0.5 hour; and then, for 0.5 hour, using the profile The temperature of the billet is raised to 460-480 ° C, and is kept at this temperature for 1 hour; then, the profile blank is subjected to water quenching; finally, the temperature of the billet before entering the water is controlled at 460-480 ° C, the quenching water temperature is 40-45 ° C, quenching The time is 0.5 hours.
9. The method according to any one of claims 1 to 8, wherein the aluminum alloy is a 7055 aluminum alloy.

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