300m steel landing gear sleeve forging short process low cost preparation method

Abstract

This invention proposes a short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings, belonging to the field of forging technology. This method solves the problems of high material consumption and long process flow inherent in traditional manufacturing processes, meeting the urgent needs of advanced aircraft in terms of product quality and manufacturing cost, and offering significant economic and social benefits. This invention employs a single-forging process, obtaining sleeve forgings with a certain depth of inner hole, resulting in small machining allowances, high material utilization, low cost, and high production efficiency. Furthermore, this invention achieves flash-free forging, avoiding the risk of exposed grain lines in the cross-section of the sleeve forging, improving the stress corrosion resistance and fatigue performance of the parts, and contributing to the operational requirements of aircraft for the safety and reliability of key components.

Description

Technical Field

[0001] This invention proposes a short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings, belonging to the field of forging technology. Background Technology

[0002] As a crucial safety component of aircraft, the landing gear is a vital support system for takeoff, landing, taxiing, and parking, and is a key load-bearing structure. To meet the higher performance requirements of next-generation aircraft, landing gear extensively utilizes advanced ultra-high-strength steel forgings, accounting for 10% to 20% of the aircraft's structural weight. The technological level and reliability of these key landing gear components have a significant impact on the overall performance and operational safety of the aircraft. Aircraft 300M steel landing gear sleeve forgings are characterized by their large size, heavy weight, and complex shape. Their shape features include a variable cross-section cylindrical body with two pairs of large and small lugs on the side walls. Traditional sleeve production technology generally uses ordinary die forging methods, resulting in significant flash and the inability to achieve hollow forging. Subsequent deep-hole drilling is required to remove the core metal to obtain a hollow shaft, which has disadvantages such as a long forging process and high material consumption. Furthermore, the streamlines at the flash of the cylindrical body of the sleeve forging are cut off and exposed, affecting the part's service fatigue performance.

[0003] Multi-directional forging technology is currently an important method for manufacturing hollow, irregularly shaped parts. However, multi-directional forging of 300M steel landing gear sleeve forgings presents significant challenges: 300M steel is an ultra-high-strength steel with high deformation resistance and high forging load; the metal flow is complex, and improper material distribution in the precast blank can easily lead to defects such as incomplete cavity filling and folding, resulting in scrap; the cylindrical body of the sleeve has a long inner hole with a large diameter ratio, and the horizontal die punch is in contact with the inner hole of the forging for a long time during forging, resulting in high punch temperature and problems such as die jamming and damage, which can also lead to product quality issues and scrap. This invention proposes a short-process, low-cost preparation method and die design for landing gear sleeve forgings. This method can realize precision forging of landing gear sleeve forgings through one-fire forging without precast blanks, and can also realize inner hole forging, significantly reducing material consumption by more than 40%, reducing deep hole drilling, and has the advantages of low cost, high quality, and high production efficiency. Summary of the Invention

[0004] This invention patent discloses a short-process, low-cost manufacturing method for 300M steel landing gear sleeve forgings, which solves the problems of high material consumption and long process flow in traditional production processes. It can meet the urgent needs of advanced aircraft in terms of product quality and manufacturing cost, and has significant economic and social benefits.

[0005] The technical solution adopted by this invention patent to solve its technical problem is: a short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings, mainly including the following steps:

[0006] Step 1: Design a combination mold and a cylindrical blank according to the outer dimensions of the sleeve forging; the combination mold includes an upper mold, a lower mold, a left horizontal mold, and a right horizontal mold; the left horizontal mold and the right horizontal mold are "mushroom-shaped", wherein the "mushroom head" contacts the blank and is the working section; the "mushroom stem" is the support section and does not contact the blank, and the diameter of the working section of the horizontal mold is larger than the diameter of the support section;

[0007] Step 2: Heat the 300M steel billet to the forging temperature, and then place the heated billet in the lower die cavity; the forging temperature is 1150±15℃;

[0008] Step 3: The upper die moves downward and contacts the billet, completing the pressing action. This step is similar to the conventional forging deformation process, but the minimum diameter of the cylindrical billet used is smaller than the diameter of the cylindrical body of the sleeve forging. The minimum diameter of the cylindrical body of the sleeve forging - the diameter of the cylindrical billet = C. The value of C is greater than 0 and less than or equal to 5mm. Therefore, after the upper and lower dies are closed, no flash will be formed at the horizontal die opening.

[0009] Step 4: The upper mold remains stationary under pressure. The left and right horizontal molds begin to move. The left horizontal mold moves horizontally to the right and contacts the blank, while the right horizontal mold moves horizontally to the left and contacts the blank. The left and right horizontal molds move to their designated target positions. Under the extrusion of the left and right horizontal molds, the metal flows in the cavity formed by the upper and lower molds and the closing of the left and right horizontal molds. The horizontal movement speed of the left and right horizontal molds is 7-9 mm / s, preferably 8 mm / s.

[0010] Step 5: The left and right horizontal dies return to their original positions, shaping the inner hole of the sleeve forging while demolding, ultimately obtaining the required landing gear sleeve forging.

[0011] In this invention, the relationship between the cavities of the upper and lower molds and the forging is as follows: First, the forging (features such as the lugs are characteristics of the forging) is designed. Then, the mold cavities are machined according to the shape of the forging using CNC machining. Therefore, the cavities of the upper and lower molds originate from the shape of the forging. The lugs are contained within the cavities of the upper and lower molds. When the metal fills the cavities of the upper and lower molds, the lugs are formed.

[0012] Preferably, one-time die forging without preform preparation is adopted to avoid defects such as incomplete filling of the cavity and folding caused by unreasonable material distribution of preforms.

[0013] Preferably, the value of C is greater than 1 and less than or equal to 4 mm.

[0014] Preferably, the diameters of the left and right inner holes of the sleeve forging are the working sections of the left and right horizontal dies, respectively.

[0015] Preferably, the depth of the left and right inner holes of the sleeve forging is the depth of the cavity formed by the left and right horizontal dies extending into the closed upper and lower dies, which is 2 to 5 times the working section diameter of the horizontal dies. More preferably, the depth of the left and right inner holes of the sleeve forging is the depth of the cavity formed by the left and right horizontal dies extending into the closed upper and lower dies, which is 2.2 to 4.5 times the working section diameter of the horizontal dies.

[0016] In this invention, a uniform cylindrical blank is placed horizontally in the mold body. The upper mold driven by a hydraulic cylinder is used to apply force to the top of the blank. The end of the left horizontal mold extends into the left opening of the mold body and is used to apply force to the left side of the blank. The end of the right horizontal mold extends into the right opening of the mold body and is used to apply force to the right side of the blank.

[0017] Preferably, the left and right horizontal dies adopt a "mushroom-shaped" design, wherein the "mushroom head" contacts the blank and is the working section; the "mushroom stem" is the supporting section and does not contact the blank. This can solve the problem that the punch of the horizontal die is in contact with the inner hole of the forging for a long time during forging, which leads to high punch temperature and easy problems such as die jamming and damage.

[0018] Preferably, the diameter of the working section of the horizontal mold is 5 to 10 mm larger than the diameter of the supporting section.

[0019] The working sections of the left and right horizontal molds of this invention have the same or different diameters. Preferably, the working sections of the left and right horizontal molds have the same diameter. During operation, the working sections of the left and right horizontal molds are on the same axis; the support sections of the left and right horizontal molds are also on the same axis.

[0020] In this invention, the recommended length of the working sections of the left and right horizontal molds is 40–80 mm (i.e., the vertical distance from the top of the mushroom head to the contact point between the working section and the support section is 40–80 mm). If the length is too short, it will not function effectively; if it is too long, it may cause jamming or damage. In this invention, the length of the support sections of the left and right horizontal molds is greater than the depth of the corresponding left and right inner holes.

[0021] In industrial applications, both the left and right horizontal molds are equipped with tail sections, with one end of the support section connected to the tail section and the other end connected to the working section.

[0022] Preferably, the working section and the support section of the horizontal mold are designed separately and made of different materials.

[0023] Preferably, the working section of the horizontal mold is made of a high-temperature alloy material with excellent high-temperature performance, such as GH4169; the supporting section is made of ordinary mold steel material, such as 5CrMnMo.

[0024] The process designed in this invention not only has a certain degree of tolerance for errors, but also produces high-precision products. Even if minor deviations occur in the axial direction (such as length or hole depth), they can be remedied through simple subsequent measures.

[0025] The advantages and beneficial effects of this invention are as follows: This invention provides a short-process, low-cost manufacturing method and mold design for landing gear sleeve forgings, which can produce landing gear sleeve forgings with inner holes. Compared with traditional production methods, this invention has the following main innovations: 1) This invention is the first to adopt a single-forging process to obtain sleeve forgings with inner holes of a certain depth, which has the advantages of small machining allowance, high material utilization, low cost, and high production efficiency; 2) Using the process designed in this invention, material consumption can be reduced by more than 40%, forging weight can be reduced by more than 40%, forging times can be reduced by more than 50%, and machining can be reduced by more than 20%; 3) This invention can achieve flash-free forging, avoiding the risk of exposed grain lines in the cross-section of the sleeve forging, improving the stress corrosion resistance and fatigue performance of the parts, and contributing to the aircraft's service requirements for the safety and reliability of key components. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the landing gear sleeve component;

[0027] Figure 2 Schematic diagram of a traditional landing gear sleeve forging;

[0028] Figure 3 Schematic diagram of the landing gear sleeve forging of the present invention;

[0029] Figure 4 A schematic diagram of the manufacturing process of the landing gear sleeve forging of the present invention;

[0030] Figure 5 Schematic diagram of the landing gear sleeve forging assembly mold of the present invention;

[0031] Figure 6 A schematic diagram of the horizontal mold structure for the landing gear sleeve forging of the present invention.

[0032] In the figure, 1 is a cylindrical blank, 2 is the upper mold, 3 is the lower mold, 4 is the left horizontal mold, 5 is the right horizontal mold, 6 is the landing gear sleeve forging, 7 is the horizontal mold support section, 8 is the horizontal mold working section, 9 is the diameter of the horizontal mold support section, and 10 is the diameter of the horizontal mold working section. Detailed Implementation

[0033] To enhance understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and embodiments, but this does not constitute a limitation on the scope of protection of the present invention. The manufacturing method of the present invention is described in detail below using a forged sleeve for landing gear of a certain type of civil passenger aircraft as an example. The outer contour of the forging is as follows... Figure 1 As shown, it is 1020mm long, with a left inner hole diameter of 115mm and a left inner hole depth of 390mm. The right inner hole diameter is 115mm, and the right inner hole depth is 280mm. The non-protruding portion of the left end (the smaller diameter end) of the forging is a cylindrical shape with a central opening, and its diameter is 152mm. The non-protruding portion of the right end (the larger diameter end) of the forging is also a cylindrical shape with a central opening, and its diameter is 165mm. Specific manufacturing steps:

[0034] Step 1: Design molds 2-5 and cylindrical blank 1 (made of 300M ultra-high strength steel) according to the forging dimensions. Horizontal molds 4 and 5 both adopt a "mushroom-shaped" structure design, characterized by: the working section 8 of the horizontal mold is made of GH4169 alloy material, with a diameter of 10 mm and a dimension of 115 mm; the support section 7 of the horizontal mold is made of 5CrMnMo material, with a diameter of 9 mm and a dimension of 95 mm (the length of the support section of the left and right horizontal molds is greater than the depth of the corresponding left and right inner holes); the support section 7 and the working section 8 are connected by welding. The blank 1 is a cylinder with a diameter of 150 mm and a length of 705 mm.

[0035] Step 2: Heat the billet 1 (made of 300M steel and shaped as a uniform straight cylinder) to a forging temperature of 1150℃, and then place the heated billet 1 horizontally in the cavity of the lower mold 3;

[0036] Step 3: The upper die 2 moves downward and contacts the billet 1, completing the pressing action. This step is similar to the conventional forging deformation process, but the diameter Amm of the cylindrical billet is smaller than the minimum diameter Bmm of the cylindrical body of the sleeve forging, BA = 2.5mm. Therefore, after the upper die 2 and the lower die 3 are closed, no flash will be formed at the horizontal die opening; (In this embodiment, the diameter of the cylindrical outer part at the left end of the sleeve forging is 152mm, and the diameter of the cylindrical outer part at the right end of the sleeve forging is 165mm)

[0037] Step 4: The upper mold 2 remains stationary under pressure. The left horizontal mold 4 and right horizontal mold 5 begin to move. The left horizontal mold 4 moves to the right and contacts the billet 1. Simultaneously, the right horizontal mold 5 moves to the left and contacts the billet 1. The left and right horizontal molds 4 and 5 each move 255mm to the target position. In this embodiment, although the structural dimensions of the left and right horizontal molds are the same, the diameters of the left and right inner cavities of the forging are different; the left side is thinner and the right side is thicker. Therefore, under the same movement conditions, the left side will be longer than the right side. That is, in this embodiment, although the movement speed of the left and right horizontal molds is the same, both moving 255mm, the depth of the left inner hole is 390mm and the depth of the right inner hole is 280mm. The metal flows in the cavity formed by the closing of the upper mold 2, lower mold 3, left horizontal mold 4, and right horizontal mold 5. (The movement speed of the left and right horizontal molds is 8mm / s.)

[0038] Step 5: The left and right horizontal dies perform their return strokes, simultaneously shaping the inner hole of the sleeve forging during demolding, ultimately obtaining the required landing gear sleeve forging 6. The mechanical properties of the obtained landing gear sleeve forging 6 are shown in the table below:

[0039]

[0040] Using traditional die forging methods, a forging weighing 165 kg and a raw material weight of 195 kg requires two forging passes and one die forging pass, followed by the removal of flash. However, using the technology of this invention, the forging weight can be reduced from 165 kg to 95 kg (a reduction of 42.4%); the raw material weight from 195 kg to 98 kg (a reduction of 49.4%); the forging passes from three to one (a reduction of 66.7%); and only burr removal is required after die forging, eliminating the need for flash removal. These figures demonstrate the significant advantages of this invention.

Claims

1. A short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings, characterized in that, Includes the following steps: Step 1: Design a combination mold and a cylindrical blank according to the outer dimensions of the sleeve forging; the combination mold includes an upper mold, a lower mold, a left horizontal mold, and a right horizontal mold; the left horizontal mold and the right horizontal mold are "mushroom-shaped", wherein the "mushroom head" contacts the blank and is the working section; the "mushroom stem" is the support section and does not contact the blank, and the diameter of the working section of the horizontal mold is larger than the diameter of the support section; Step 2: Heat the 300M steel billet to the forging temperature, and then place the heated billet in the lower die cavity; the forging temperature is 1150±15℃; Step 3: The upper die moves downwards and contacts the billet, completing the pressing action. The minimum diameter of the cylindrical billet used is smaller than the diameter of the cylindrical body of the sleeve forging. The minimum diameter of the cylindrical body of the sleeve forging - the diameter of the cylindrical billet = C, where C is greater than 0 and less than or equal to 5 mm. Step 4: The upper mold remains stationary under pressure. The left and right horizontal molds begin to move. The left horizontal mold moves horizontally to the right and contacts the blank, while the right horizontal mold moves horizontally to the left and contacts the blank. The left and right horizontal molds move to their designated target positions. Under the extrusion of the left and right horizontal molds, the metal flows in the cavity formed by the upper and lower molds and the closing of the left and right horizontal molds. The horizontal movement speed of the left and right horizontal molds is 7~9 mm / s. Step 5: The left and right horizontal dies return to their original positions, shaping the inner hole of the sleeve forging while demolding, ultimately obtaining the required landing gear sleeve forging.

2. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The cavities of the upper and lower dies are derived from the shape of the forging; the cavities of the upper and lower dies contain the features of the lugs.

3. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: A 300M steel landing gear sleeve forging was obtained by one-time die forging without preform preparation.

4. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The value of C is greater than 1 and less than or equal to 4 mm.

5. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The diameters of the left and right inner holes of the sleeve forging are the working sections of the left and right horizontal dies, respectively.

6. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The depth of the left and right inner holes of the sleeve forging is the depth of the cavity formed by the left and right horizontal dies extending into the upper and lower dies and closing, which is 2 to 5 times the diameter of the working section of the horizontal die.

7. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The depth of the left and right inner holes of the sleeve forging is the depth of the cavity formed by the left and right horizontal dies extending into the upper and lower dies and closing, which is 2.2 to 4.5 times the working section diameter of the horizontal die.

8. The method for short-process, low-cost preparation of 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The diameter of the working section of the horizontal mold is 5-10 mm larger than the diameter of the supporting section.

9. A short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings according to claim 1, characterized in that: During operation, the working sections of the left horizontal mold and the right horizontal mold are on the same axis; the support sections of the left horizontal mold and the right horizontal mold are also on the same axis; the center of the working section of the left horizontal mold, the center of the working section of the right horizontal mold, and the centers of both ends of the cylindrical blank are on the same straight line.

10. A short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The length of the working section of the left and right horizontal mold is 40~80mm; the length of the support section of the left and right horizontal mold is greater than the depth of the corresponding left and right inner holes.

11. A short-process, low-cost method for manufacturing 300M steel landing gear sleeve forgings according to claim 1, characterized in that: The working section and support section of the horizontal mold are designed separately and made of different materials. The working section of the horizontal mold is made of high-temperature alloy, while the support section is made of mold steel.

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