Method of manufacturing an aircraft landing gear die forging
By designing an initial blank with a circular cross-section and using arc-shaped flattening technology, combined with the opposing forging method, the problems of cross-damage and folding in the manufacturing process of aircraft landing gear forgings were solved, achieving high-quality and stable forging production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA NAT ERZHONG GRP DEYANG WANHANG DIE FORGING CO LTD
- Filing Date
- 2023-12-08
- Publication Date
- 2026-05-29
AI Technical Summary
In the existing technology, aircraft landing gear forgings are prone to defects such as cross-scratches and folds during the manufacturing process, and the quality stability is difficult to guarantee.
The initial blank is designed with a circular cross-section based on the principle of constant volume. It is then transitioned through a truncated cone and combined with the methods of flattening the arc surface and forging in opposite directions to produce a pre-forged part with a rhomboid cross-section. The deformation amount and mold temperature of each forging are controlled to ensure the uniformity and quality of the forging process.
This effectively avoids material folding and clamping damage, improves the quality stability and microstructure uniformity of pre-forged parts, and ensures the high quality and consistency of aircraft landing gear forgings.
Smart Images
Figure CN117483636B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of forging, specifically a method for manufacturing aircraft landing gear die forgings. Background Technology
[0002] Landing gear forgings are among the most complex-shaped forgings in aerospace components and are also one of the most critical parts of an aircraft. They are devices used to support the aircraft's weight and withstand complex loads during parking, taxiing, takeoff, and landing. Aircraft landing gear has a circular cross-section and is generally made of high-strength steel, such as A-100 steel. The mechanical properties, fatigue, and streamlines of the forgings are closely related to the amount and method of deformation during the forging process.
[0003] Chinese patent application number 201711473737.5 discloses a forging method and pre-forging design method for A-100 steel die forgings for aircraft landing gear. It discloses a method for forging pre-forgings with a rhomboid cross-section, where the forging direction aligns with one diagonal of the rhomboid cross-section to ensure uniform deformation and microstructure at different locations throughout the forging process from pre-forging to final forging. In this method, the pre-forging is generally forged from a square-section blank. However, due to the complex structure of aircraft landing gear, the forging difficulty coefficient is generally the most complex S4 level, with drastic changes in cross-sectional area, often exceeding four times. Using square cross-sections for the blank results in significant steps between different sections. Large steps can easily lead to folding during subsequent die forging. Using long inclined planes for transitions is difficult and cannot avoid defects such as cross-cutting damage and folding caused by repeated hammering.
[0004] In addition, due to the complex structure of forgings, there is a great difficulty in controlling the temperature uniformity during the manufacturing process, making it difficult to guarantee the quality stability of forgings. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing aircraft landing gear forgings to solve defects such as cross-scraping and folding that occur in the process from blank to pre-forging.
[0006] The technical solution adopted by this invention to solve its technical problem is: a method for manufacturing aircraft landing gear forgings, comprising the following steps:
[0007] Based on the cross-sectional changes of the aircraft landing gear forging, the aircraft landing gear forging is divided into regions with the abrupt change in cross-section as the dividing line. Then, using the principle of constant volume, the cross-sectional area and length of each region of the initial blank are designed. The cross-section of each region of the initial blank is a circular cross-section, and the adjacent regions are smoothly transitioned by a frustum of a cone.
[0008] The initial rough blank is obtained by drawing and elongating the billet.
[0009] The initial blank is flattened from one side to obtain a final blank with two opposite sides being curved and the other two opposite sides being flat.
[0010] The final blank is placed in a pre-forging mold and forged from opposite sides with arc surfaces in the forging direction to obtain a pre-forging part with a rhomboid cross section.
[0011] The pre-forged part is placed in the final forging mold, and the pre-forged part is forged in a manner in which the forging direction is consistent with one diagonal of the rhomboid cross section of the pre-forged part, so as to obtain the aircraft landing gear die forging.
[0012] Furthermore, it also includes the step of forging the two curved sides of the final blank into positioning parts that cooperate with the pre-forging die, so as to fix the final blank when performing the step of placing the final blank into the pre-forging die.
[0013] Furthermore, during the process from the pre-forged part to the aircraft landing gear die forging, the deformation amount of each part per forging is greater than 20%, and the maximum deformation amount at the die fillet is less than 75%.
[0014] Furthermore, in the rhomboid cross-section of the pre-forged part, the length of the diagonal parallel to the forging direction when the aircraft landing gear die forging is H, and the length of the diagonal perpendicular to the forging direction is W, and H and W satisfy the following relationship:
[0015] 1.4≤H / W≤1.8.
[0016] Furthermore, in the process of obtaining the initial blank, the blank heating temperature is 1150-1200℃, the heating time is calculated at 0.4-0.6min / mm, and the deformation per firing is 30%-50%.
[0017] Furthermore, the operating temperature of the pre-forging die and the final forging die is greater than 300℃, and the heating temperature of the forging during die forging is 1150~1200℃, the heating time is calculated at 0.4-0.6min / mm, and the forging pressing speed of the forging is 5-10mm / s.
[0018] The beneficial effects of the present invention are as follows: The method for manufacturing aircraft landing gear forgings of the present invention adopts an initial blank with a circular cross-section obtained by first drawing and then flattening it, and with a smooth transition between adjacent areas. Then, the initial blank is flattened from one side to obtain a final blank with two opposite curved sides. The final blank is then placed in a pre-forging mold and forged from opposite sides with curved surfaces to obtain a pre-forging with a rhomboid cross-section. This method can effectively avoid material folding, pinching, and other situations that occur during the process from blank to pre-forging. The resulting rhomboid cross-section pre-forging has high quality and better quality stability. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the area division and initial blank structure of the aircraft landing gear die forging;
[0020] Figure 2 This is a schematic diagram of the final unfinished structure;
[0021] Figure 3 yes Figure 2 Cross-sectional view along BB;
[0022] Figure 4 This is a schematic diagram showing the contact between the final blank and the upper and lower dies of the pre-forging mold;
[0023] Figure 5 This is a schematic diagram showing the contact between the pre-forged part and the upper and lower dies of the final forging die;
[0024] Figure 6 This is a forging diagram of the positioning part;
[0025] Figure 7 This is a map showing the locations of each testing point;
[0026] The figure shows: aircraft landing gear forging 1, initial blank 2, final blank 3, pre-forging die 4, pre-forging part 5, final forging die 6, area I, area II, area III, area IV, area V, and U-shaped structure die 7. Detailed Implementation
[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0028] like Figures 1 to 5 As shown, the method for manufacturing aircraft landing gear forgings of the present invention includes the following steps:
[0029] Step 1: Based on the cross-sectional changes of the aircraft landing gear forging 1 (final forging), the aircraft landing gear forging 1 is divided into regions with the abrupt change in cross-section as the dividing line. In this embodiment of the invention, it is divided into five regions: region I, region II, region III, region IV, and region V. Then, using the principle of constant volume, the cross-sectional area and length of the corresponding five regions of the initial blank 2 are designed. The cross-section of each region of the initial blank 2 is a circular cross-section, and the adjacent regions are smoothly transitioned by a frustum of a cone.
[0030] Step 2: Lengthen the billet to obtain the initial rough billet 2;
[0031] Step 3: Flatten the initial blank 2 from one side to obtain the final blank 3, which has two curved sides and two flat sides (see...). Figure 2 and Figure 3 );
[0032] Step 4: Place the final blank 3 into the pre-forging mold 4, and forge the final blank from opposite sides with arc surfaces in the forging direction to obtain a pre-forging part 5 with a rhomboid cross-section.
[0033] Step 5: Place the pre-forged part into the final forging mold 6, and forge the pre-forged part in a manner in which the forging direction is consistent with one diagonal of the rhomboid cross section of the pre-forged part, to obtain the aircraft landing gear die forging.
[0034] The aircraft landing gear forging manufacturing method of the present invention employs an initial blank 2, which is first drawn and then flattened to obtain a circular cross-section with smooth transitions between adjacent areas. Then, the initial blank 2 is flattened from one side to obtain a final blank 3 with arc-shaped opposing sides. Finally, the final blank 3 is placed in a pre-forging mold 4 and forged from opposite sides with arc surfaces to obtain a pre-forging part with a rhomboid cross-section. This method effectively avoids material folding and pinching during the process from blank to pre-forging, resulting in a high-quality rhomboid cross-section pre-forging part with better quality stability. This method not only facilitates the production of rhomboid cross-section pre-forging parts, but also, in conjunction with step five, increases the deformation amount of the aircraft landing gear forging part while ensuring more uniform deformation.
[0035] In this invention, the material used for the aircraft landing gear forgings is A-100 steel, as an example. In some embodiments, materials with similar properties to this steel are also used.
[0036] To facilitate the positioning of the final blank 3 in the pre-forging mold 4, the present invention further includes the step of forging the two curved sides of the final blank 3 into positioning portions that mate with the pre-forging mold 4. The positioning portions are approximately V-shaped to facilitate mating with the cavity of the pre-forging mold 4 when the final blank is placed into the pre-forging mold 4, thereby fixing the final blank 3. The forging of the positioning portions can be carried out using methods such as... Figure 6 The method described is as follows: the final blank 3 is placed in the U-shaped mold 7 for forging. The mold opening of the U-shaped mold 7 has a certain rounded corner, the shape of which is similar to the shape of the flattened final blank 3. Combined with a large draft angle, it can automatically correct the position of the final blank 3 in the mold cavity, prevent the blank from tipping over, and ensure product quality.
[0037] To ensure the uniformity of the microstructure and grain size of the forging, the deformation of each part in each forging process from the pre-forging to the aircraft landing gear die forging is greater than 20%, and the maximum deformation of the forging at the die fillet is less than 75% during the die forging process.
[0038] In the rhomboid cross-section of the pre-forged part, the length of the diagonal parallel to the forging direction when the aircraft landing gear forging is made is H, and the length of the diagonal perpendicular to the forging direction is W. To ensure that the deformation is relatively uniform in the pre-forging and final forging stages, the ratio of the two needs to be controlled within a certain proportion. Ideally, H and W satisfy the following relationship:
[0039] 1.4≤H / W≤1.8.
[0040] Through simulation, using the above method, even the core of the forging, which has the smallest deformation, can achieve a deformation of about 30% to 50%, effectively improving the uniformity of the forging's microstructure. Figure 7 This is a schematic diagram of the locations of each inspection point on the final forging. Table 1 shows the grain size of each inspection point on the final forging.
[0041] Table 1: Grain size at various test points of the final forging
[0042]
[0043] The grain size of the final forging formed by the method of the present invention is 6.5 to 8, and the grain size difference level of the final forging is controlled at about 1.5.
[0044] In this embodiment of the invention, in order to ensure that the metal has good fluidity while maintaining the mechanical and structural properties of the material, the billet heating temperature is 1150-1200℃ during the initial billet preparation process, the heating time is calculated at 0.4-0.6 min / mm, and the deformation per forging is 30%-50%; the operating temperature of the pre-forging die and the final forging die is greater than 300℃, and the forging temperature during die forging is 1150-1200℃, the heating time is calculated at 0.4-0.6 min / mm, and the forging pressing speed is 5-10 mm / s.
Claims
1. A method for manufacturing aircraft landing gear forgings, characterized in that, Includes the following steps: Based on the cross-sectional changes of the aircraft landing gear forging, the aircraft landing gear forging is divided into regions with the abrupt change in cross-section as the dividing line. Then, using the principle of constant volume, the cross-sectional area and length of each region of the initial blank are designed. The cross-section of each region of the initial blank is a circular cross-section, and the adjacent regions are smoothly transitioned by a frustum of a cone. The initial rough blank is obtained by drawing and elongating the billet. The initial blank is flattened from one side to obtain a final blank with two opposite sides being curved and the other two opposite sides being flat. The final blank is placed in a pre-forging mold and forged from opposite sides with arc surfaces in the forging direction to obtain a pre-forging part with a rhomboid cross section. The pre-forged part is placed in the final forging mold, and the pre-forged part is forged in a manner in which the forging direction is consistent with one diagonal of the rhomboid cross section of the pre-forged part, so as to obtain the aircraft landing gear die forging.
2. The method for manufacturing aircraft landing gear forgings as described in claim 1, characterized in that, It also includes the step of forging the two curved sides of the final blank into positioning parts that cooperate with the pre-forging die, so as to fix the final blank when performing the step of placing the final blank into the pre-forging die.
3. The method for manufacturing aircraft landing gear forgings as described in claim 1, characterized in that, During the process from the pre-forged part to the aircraft landing gear die forging part, the deformation amount of each part per forging is greater than 20%, and the maximum deformation amount at the die corner is less than 75%.
4. The method for manufacturing aircraft landing gear forgings as described in claim 1, characterized in that, In the rhomboid cross-section of the pre-forged part, the length of the diagonal parallel to the forging direction when the aircraft landing gear forging is made is H, and the length of the diagonal perpendicular to the forging direction is W, and H and W satisfy the following relationship: 1.4≤H / W≤1.
8.
5. The method for manufacturing aircraft landing gear forgings as described in claim 1, characterized in that, In the process of obtaining the initial blank, the blank heating temperature is 1150-1200℃, the heating time is calculated at 0.4-0.6min / mm, and the deformation per firing is 30%-50%.
6. The method for manufacturing aircraft landing gear forgings as described in claim 4, characterized in that, The operating temperature of the pre-forging die and the final forging die is greater than 300℃, and the heating temperature of the forging during die forging is 1150~1200℃, the heating time is calculated at 0.4-0.6min / mm, and the forging pressing speed of the forging is 5-10mm / s.