A method for preparing a U-shaped closed rib forging for aircraft

Abstract

This invention relates to a method for manufacturing U-shaped closed-rib forgings for aircraft, specifically addressing the problem of flow-through defects in forgings produced by existing processes. The manufacturing method includes: 1. Preparing an aluminum alloy ingot; 2. Heating and extruding the ingot into a strip; 3. Flattening the heated strip; 4. First forging; 5. Etching and milling the ribs; 6. Machining and drilling; 7. Second forging; 8. Etching and repairing defects; 9. Quenching and aging treatment; 10. Full analysis and testing; 11. Acceptance and delivery. This invention, by adding etching and milling, machining and drilling, and controlling the dimensions of the flattened blank, along with subsequent scientifically controlled die-forming process conditions, ensures that the low-magnification microstructure of the forging is free of flow-through defects, thereby improving the load-bearing capacity and service life of the forging. This invention is applicable to the field of forging manufacturing.

Description

Technical Field

[0001] This invention relates to a method for preparing a U-shaped closed rib forging for aircraft. Background Technology

[0002] With the rapid development of my country's aviation industry, the performance requirements for aluminum alloy structural components are becoming increasingly stringent. Every component of a transport aircraft is interconnected and crucial during flight. The U-shaped closed-rib forging is primarily manufactured using Al-Cu-Si aluminum alloys. These alloys are characterized by their compact structure, high strength, heat resistance, and good machinability, and are widely used in the aviation field. However, during the production process, flow-through defects frequently occur at the U-shaped closed-rib area of ​​these forgings. These low-magnification flow-through quality defects increase the probability of structural component cracking during flight, a phenomenon that is absolutely unacceptable and necessitates complete scrapping. Therefore, reducing the probability of engine structural component cracking during flight has broad application value in the aviation industry. Summary of the Invention

[0003] The purpose of this invention is to solve the problem that existing production processes easily produce flow defects in die forgings, and to provide a method for producing a U-shaped closed rib die forging for aircraft.

[0004] The present invention discloses a method for preparing a U-shaped closed rib forging for aircraft, which is carried out according to the following steps:

[0005] I. Based on the mass percentage of elements: Cu 1.8%–2.6%; Mg 0.4%–0.8%; Si 0.7%–1.2%; Fe ≤0.7%; Mn 0.4%–0.8%; Ni ≤0.1%; Zn ≤0.3%; Ti ≤0.15% and the balance Al, aluminum alloy round ingots are prepared, followed by homogenization annealing.

[0006] 2. The aluminum alloy ingot after homogenization and annealing is extruded to obtain a long strip-shaped blank with a specification of 35mm×310mm.

[0007] 3. The long strip-shaped blank is subjected to low magnification and fracture structure testing. After passing the test, it is sawed, forged and drawn, and then placed in a mold for the first die forging. The forging temperature is 440℃~460℃ and the mold temperature is 420℃ to obtain die forging A.

[0008] 4. Use a milling machine to repair the high ribs on the edge of the forging A obtained in step 3, then use a grinding machine to grind the edges and corners, and drill a hole with a diameter of 60-80mm in the center position.

[0009] 5. Heat the forgings processed in step 4, controlling the initial forging temperature to be 440℃~460℃ and the final forging temperature to be 410℃~430℃. After cleaning, perform a second forging to obtain forging B.

[0010] 6. The forging B obtained in step 5 is subjected to etching and repair to obtain the etched forging;

[0011] 7. After quenching, the forged parts are aged to complete the production of the forging parts.

[0012] In this invention, a hole is drilled in the middle of the forging part. After the first forging process removes the intermediate metal, during the second forging, part of the metal fills the cavity, and part flows towards the hole to fill it. Because the metal refills the cavity, there is no resistance in the cavity area, and no resistance at the hole. The metal easily fills the cavity, and the flow lines are completely along the cavity direction, achieving excellent results. When the forging parts produced using this invention are analyzed at low magnification, no flow-through defects are found, thus improving the load-bearing capacity and service life of the forging parts.

[0013] The U-shaped closed rib forging described in this invention can be applied in the actual production of similar rib forgings, solving the problem of low-magnification flow in such forgings. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the U-shaped closed rib high rib die forging in the embodiment;

[0015] Figure 2 The example provided is a high-rib forging with a closed rib in the shape of a square.

[0016] Figure 3 This is a low-magnification microstructure inspection image of a forging with flow defects; the arrows indicate flow defects.

[0017] Figure 4 The image shown is a low-magnification microstructure inspection image of the forged metal obtained in the example. No flow defects are visible at the arrow. Detailed Implementation

[0018] Specific Implementation Method 1: This implementation method describes a method for preparing a U-shaped closed rib forging for aircraft, which is carried out according to the following steps:

[0019] I. Based on the mass percentage of elements: Cu 1.8%–2.6%; Mg 0.4%–0.8%; Si 0.7%–1.2%; Fe ≤0.7%; Mn 0.4%–0.8%; Ni ≤0.1%; Zn ≤0.3%; Ti ≤0.15% and the balance Al, aluminum alloy round ingots are prepared, followed by homogenization annealing.

[0020] 2. The aluminum alloy ingot after homogenization and annealing is extruded to obtain a long strip-shaped blank with a specification of 35mm×310mm.

[0021] 3. The long strip-shaped blank is subjected to low magnification and fracture structure testing. After passing the test, it is sawed, forged and drawn, and then placed in a mold for the first die forging. The forging temperature is 440℃~460℃ and the mold temperature is 420℃ to obtain die forging A.

[0022] 4. Use a milling machine to repair the high ribs on the edge of the forging A obtained in step 3, then use a grinding machine to grind the edges and corners, and drill a hole with a diameter of 60-80mm in the center position.

[0023] 5. Heat the forgings processed in step 4, controlling the initial forging temperature to be 440℃~460℃ and the final forging temperature to be 410℃~430℃. After cleaning, perform a second forging to obtain forging B.

[0024] 6. The forging B obtained in step 5 is subjected to etching and repair to obtain the etched forging;

[0025] 7. After quenching, the forged parts are aged to complete the production of the forging parts.

[0026] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the size of the aluminum alloy ingot in step one is Φ350mm~Φ410mm. Everything else is the same as in Specific Implementation Method One.

[0027] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that step three, milling, is as follows: During extrusion in step two, the ingot is first heated to 480°C. When the ingot is placed in the extrusion cylinder, the ingot temperature is 430–450°C, the extrusion cylinder temperature is 450°C, the extrusion ratio is 11.5–12.7, and the extrusion speed is 1.5 m / s. Everything else is the same as in Specific Implementation Method One or Two.

[0028] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the temperature for extruding the long strip-shaped blank in step two is 430℃. Everything else is the same as in Specific Implementation Methods One to Three.

[0029] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: in step three, the long strip-shaped blank is sawn into blanks measuring 35mm × 310mm × 160mm. Everything else is the same as in Specific Implementation Methods One to Four.

[0030] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step three, the final forging temperature of forging part A is 410℃~430℃, and the under-pressure is controlled to be +2mm~+4mm. Everything else is the same as in Specific Implementation Methods One to Five.

[0031] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the molding speed in step three is 3 mm / s. Everything else is the same as in Specific Implementation Methods One to Six.

[0032] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: during the second die forging in step five, the underpressure is controlled to be +1mm to +2mm. Everything else is the same as in Specific Implementation Methods One to Seven.

[0033] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: Step Six, the etching and cleaning treatment, involves first etching and degreasing the workpiece for 15 minutes in an alkaline bath with a mass concentration of 20% to 30% NaOH at a temperature of 50℃ to 60℃, then washing off the alkaline solution, followed by neutralization and whitening in an acid bath with a mass concentration of 30% HNO3 for 10 minutes, washing off the acid solution, and finally rinsing the forging in a hot water bath at a water temperature of 40 to 50℃. The rest is the same as in Specific Implementation Methods One to Eight.

[0034] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step seven, the quenching temperature is 510℃~516℃, the aging temperature is 153℃~160℃, and the total heating time is 8~14 hours. Everything else is the same as in Specific Implementation Methods One to Nine.

[0035] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0036] The present application will be described in detail below with reference to specific embodiments:

[0037] Example 1

[0038] A method for preparing a U-shaped closed rib forging for aircraft is carried out according to the following steps:

[0039] I. Based on the mass percentage of elements: Cu 1.8%–2.6%; Mg 0.4%–0.8%; Si 0.7%–1.2%; Fe ≤0.7%; Mn 0.4%–0.8%; Ni ≤0.1%; Zn ≤0.3%; Ti ≤0.15% and the balance Al, aluminum alloy round ingots are prepared, followed by homogenization annealing.

[0040] 2. The homogenized annealed aluminum alloy ingot is heated to 480℃ and placed into the extrusion cylinder. The ingot temperature is 430-450℃, the extrusion cylinder temperature is 450℃, the extrusion ratio is 11.5, and the extrusion speed is 1.5 m / s to obtain an aluminum alloy strip blank with specifications of 35×310; ensure that the temperature of the extruded strip is 430℃.

[0041] Third, the strip blank extruded in step two shall be subjected to low magnification and fracture structure testing. Only after passing the testing can it be heated and forged.

[0042] Fourth, cut the strip blank obtained in step three into trapezoidal blanks according to the drawings, and then forge and draw them on a 3000-ton vertical hydraulic press according to the drawings.

[0043] 5. Heat the blank obtained in step 4, control the initial forging temperature to be 440℃~460℃, the die temperature to be 420℃, place the blank in the die for the first forging to obtain forging A, ensure the final forging temperature of the forging to be 410℃~430℃, and control the under-pressure amount to be +2mm~+4mm.

[0044] 6. Using a milling machine, remove the high ribs from the edge of the forging A obtained in step 5. Then, use a grinding machine to grind the edges and corners. Simultaneously, drill a hole with a diameter of 80mm at the location shown in the diagram (e.g., Figure 2 (As shown).

[0045] 7. Heat the forging obtained in step 6, control the initial forging temperature to be 440℃~460℃, and the final forging temperature to be 410℃~430℃. Place the cleaned pre-pressed forging in the mold for a second forging to obtain forging B; control the under-pressurization amount to be +1mm~+2mm.

[0046] 8. The forging B obtained in step 7 is subjected to etching and cleaning treatment and repair to obtain a clean forging after etching.

[0047] 9. After quenching, the forgings obtained in step 8 are subjected to aging treatment. The quenching temperature is 510℃~516℃, the holding time is 90 minutes (metal holding), and the water temperature for quenching is 30℃~50℃. The aging temperature is 153℃~160℃ (metal temperature), and the total heating time is 8~14 hours, completing the production of the forgings (e.g., Figure 1 (As shown).

[0048] 10. The microstructure and properties of the forgings obtained in step 9 are tested. The tensile test results are shown in Table 1.

[0049] 11. After the die forgings obtained in step 10 are hardened to 100%, they are packaged and delivered.

[0050] Table 1

[0051]

[0052] In steps five and seven of the die forging process, when applying lubricating oil to the forging, apply more oil in the middle and use a brush to splash the oil into the cavities on both sides. Do not apply oil directly to the material. During final pressing, two rounds of lubrication and pressing are required, followed by lifting the machine to release air and then pressing again to ensure proper forming. The lubricating oil is a mixture of graphite and spindle oil in a specific ratio. A secondary pressure of 5000 tons is used during pressing. The etching treatment described in step eight involves first etching and degreasing the forging in an alkaline bath with a concentration of 20%–30% NaOH at a temperature of 50℃–60℃ for 15 minutes, then washing off the alkaline solution. Next, neutralize and wash the forging in an acid bath with a concentration of 30% HNO3 for 10 minutes, washing off the acid solution. Finally, rinse the forging in a hot water bath at a temperature of 40–50℃.

[0053] The forged U-shaped closed rib forging obtained in this embodiment was subjected to low-magnification microstructure inspection and comparative analysis, such as... Figure 3 and 4 As shown, the forging in this embodiment does not have low-magnification flow defects, thereby improving the load-bearing capacity, crack resistance, toughness, etc. of the forging, and increasing the service life of the forging.

Claims

1. A method for preparing a U-shaped closed rib forging for aircraft, characterized in that... This method is performed in the following steps: I. Based on the mass percentage of elements: Cu 1.8%–2.6%; Mg 0.4%–0.8%; Si 0.7%–1.2%; Fe ≤0.7%; Mn 0.4%–0.8%; Ni ≤0.1%; Zn ≤0.3%; Ti ≤0.15% and the balance Al, aluminum alloy round ingots are prepared, followed by homogenization annealing.

2. The aluminum alloy ingot after homogenization and annealing is extruded to obtain a long strip-shaped blank with a specification of 35mm×310mm.

3. The long strip-shaped blank is subjected to low magnification and fracture structure testing. After passing the test, it is sawed, forged and drawn, and then placed in a mold for the first die forging. The initial forging temperature is 440℃~460℃, and the mold temperature is 420℃ to obtain die forging A. The final forging temperature of die forging A is 410℃~430℃, and the under-pressure is controlled to be +2mm~+4mm.

4. Use a milling machine to repair the high ribs on the edge of the forging A obtained in step 3, then use a grinding machine to grind the edges and corners, and drill a hole with a diameter of 60~80mm in the center position.

5. Heat the forgings processed in step 4, controlling the initial forging temperature to be 440℃~460℃ and the final forging temperature to be 410℃~430℃. After cleaning, perform a second forging to obtain forging B. During the second forging, control the under-pressure amount to be +1mm~+2mm.

6. The forging B obtained in step 5 is subjected to etching and repair to obtain the etched forging; 7. After quenching, the forged parts are aged to complete the production of the forging parts.

2. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, The dimensions of the aluminum alloy ingot in step one are Φ350mm~Φ410mm.

3. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, In step two, the ingot is first heated to 480℃ during extrusion. When the ingot is placed into the extrusion cylinder, the ingot temperature is 430-450℃, the extrusion cylinder temperature is 450℃, the extrusion ratio is 11.5-12.7, and the extrusion speed is 1.5 m / s.

4. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, The temperature for extruding the long strip-shaped blank in step two is 430℃.

5. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, Step 3: Cut the long strip of blank into blanks of 35mm×310mm×160mm.

6. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, The molding speed in step three is 3 mm / s.

7. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, Step six, etching and washing, involves first etching and degreasing the forgings for 15 minutes in an alkaline bath with a mass concentration of 20%–30% NaOH at a temperature of 50℃–60℃, then washing off the alkaline solution, followed by neutralization and whitening in an acid bath with a mass concentration of 30% HNO3 for 10 minutes, washing off the acid solution, and finally rinsing the forgings in a hot water bath with a water temperature of 40–50℃.

8. The method for preparing a U-shaped closed rib forging for aircraft according to claim 1, characterized in that, In step seven, the quenching temperature is 510℃~516℃, the aging temperature is 153℃~160℃, and the total heating time is 8~14 hours.

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