Short-process low-cost preparation method of 300M steel undercarriage sleeve forging

Abstract

The invention provides a short-process low-cost preparation method for a 300M steel undercarriage sleeve forging, and belongs to the technical field of forging and pressing. According to the short-process low-cost preparation method for the 300M steel undercarriage sleeve forging, the problems of large material consumption, long process flow and the like in a traditional production process are solved, the urgent requirements of advanced aircrafts on the aspects of product quality, manufacturing cost and the like can be met, and the method has great economic and social benefits. According to the method, single-heating-number one-forging forming is adopted, the sleeve forge piece with an inner hole with a certain depth can be obtained, the machining allowance is small, the material utilization rate is high, the cost is low, and the production efficiency is high; according to the method, flash-free forging is achieved, the risk that a cross section grain streamline of the sleeve forge piece is cut off and exposed is avoided, the stress corrosion resistance and the fatigue resistance of parts are improved, and the service requirements of airplanes for the safety and the reliability of key parts are met.

Description

Technical Field

[0001] The invention provides a short-process and low-cost preparation method for a 300M steel landing gear sleeve forging, belonging to the technical field of forging. Background Art

[0002] As an important safety functional component of an aircraft, the aircraft landing gear is an important support system for aircraft takeoff, landing, ground taxiing and parking, and is a key and important load-bearing component of the aircraft. In order to meet the higher performance requirements of the new generation of aircraft, the aircraft landing gear adopts a large number of advanced ultra-high strength steel forgings, which account for 10% to 20% of the aircraft structure weight. The technical level and reliability of the key components of the landing gear have an important impact on the overall performance and safety of the aircraft. The 300M steel landing gear sleeve die forgings for aircraft are characterized by large size, heavy weight and complex shape. Its shape features include a cylindrical body with a variable cross-section and two pairs of large and small ears on the side wall of the cylindrical body. Traditional sleeve production technology generally adopts ordinary die forging methods, which has large flash and cannot be hollow forged. It is necessary to remove the core metal through subsequent deep hole drilling to obtain a hollow shaft. There are disadvantages such as long forging process and high material consumption. In addition, the streamlines at the flash of the cylindrical body of the sleeve die forging are cut off and exposed, which affects the service fatigue performance of the parts.

[0003] Multi-directional die forging technology is currently an important means of manufacturing hollow special-shaped parts. However, there are great challenges in using multi-directional die forging for 300M steel landing gear sleeve forgings: 300M steel is an ultra-high strength steel with high deformation resistance and high forging forming load; the metal flow is complex, and once the material distribution of the prefabricated blank is unreasonable, it is very easy to produce defects such as insufficient cavity filling and folding, resulting in scrap; the inner hole of the cylindrical main body of the sleeve is long and the aperture ratio is large. 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, easy to cause problems such as die jamming and damage, and also cause product quality problems leading to scrap. The present invention proposes a short-process and low-cost preparation method and die design for landing gear sleeve forgings. The method can realize the precision forging of landing gear sleeve die forgings without blanking and one-fire die forging, and can also realize inner hole forging, greatly reducing material consumption by more than 40%, reducing the amount of deep hole drilling processing, and has the advantages of low cost, good quality and high production efficiency. Summary of the invention

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

[0005] The technical solution adopted by the present invention to solve the technical problem is: a short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging, which mainly includes the following steps:

[0006] Step 1: Design a combined die and a cylindrical blank according to the outer dimensions of the sleeve forging; the combined die includes an upper die, a lower die, a left horizontal die and a right horizontal die; the left horizontal die and the right horizontal die are in a "mushroom shape", wherein the "mushroom head" contacts the blank and is the working section; the "mushroom rod" is the supporting section and does not contact the blank, and the diameter of the working section of the horizontal die is larger than the diameter of the supporting 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°C;

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

[0009] Step 4: The upper mold keeps the pressure and stops, the left horizontal mold and the right horizontal mold join the action, the left horizontal mold moves horizontally to the right to contact the blank, and at the same time, the right horizontal mold moves horizontally to the left to contact the blank, and the left and right horizontal molds move to the specified target positions respectively. 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 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 perform return motions respectively, and the inner hole of the sleeve forging is shaped while demolding, and finally the required landing gear sleeve die forging is obtained.

[0011] In the present invention, the relationship between the cavities of the upper and lower dies and the forging is as follows: the forging is designed first (features such as the ear piece are all features of the forging), and then the die cavity is processed according to the shape of the forging by means of numerical control, so the cavities of the upper and lower dies are derived from the shape of the forging. The upper and lower die cavities contain the features of the ear piece, and when the metal fills the upper and lower die cavities, the ear piece features are formed.

[0012] Preferably, non-blank-forming and fire die forging is adopted to avoid defects such as insufficient cavity filling and folding caused by unreasonable material distribution of the prefabricated blank.

[0013] Preferably, the value range 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 respectively the diameters of the working sections of the left and right horizontal dies.

[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 upper and lower dies, which is 2 to 5 times the diameter of the working section of the horizontal die. 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 upper and lower dies, which is 2.2 to 4.5 times the diameter of the working section of the horizontal die.

[0016] The present invention places a uniform cylindrical blank horizontally in the mold body, an 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, and 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 horizontal die and the right horizontal die adopt a "mushroom-shaped" design, wherein the "mushroom head" is in contact with the blank and is the working section; the "mushroom rod" is the supporting section and does not contact the blank. This can solve the problem of the horizontal die punch being in contact with the inner hole of the forging for a long time during forging, resulting in high punch temperature, easy die jamming, damage and other problems.

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

[0019] The diameter of the working section of the left horizontal mold and the working section of the right horizontal mold of the present invention is the same or different. As a further preference, the diameter of the working section of the left horizontal mold and the working section of the right horizontal mold of the present invention is the same. When working, the working section of the left horizontal mold and the working section of the right horizontal mold are on the same axis; the supporting section of the left horizontal mold and the supporting section of the right horizontal mold are also on the same axis.

[0020] In the present invention, the recommended length of the working section of the left and right horizontal molds is 40 to 80 mm (i.e., the vertical distance from the top of the mushroom head to the position where the working section contacts the supporting section is 40 to 80 mm). If it is too short, it will not work, and if it is too long, it will easily get stuck and damaged. In the present invention, the length of the supporting section of the left and right horizontal molds is greater than the depth of the corresponding left and right inner holes.

[0021] When used in industry, both the left and right horizontal molds are provided with tails, one end of the supporting section is connected to the tail, and the other end is connected to the working section.

[0022] Preferably, the working section and the supporting section of the horizontal mold are designed to be split and made of different materials.

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

[0024] The process designed by the present invention not only has a certain fault tolerance, but also can obtain high-precision products. Even if there is a slight deviation in the axial direction (such as length, depth of the hole), it can be remedied by subsequent simple measures.

[0025] The advantages and beneficial effects of the present invention are as follows: the present invention provides a short-process and low-cost preparation method and die design for a landing gear sleeve die forging, which can prepare a landing gear sleeve forging with an inner hole. Compared with the traditional production method, the present invention mainly has the following innovations: 1) The present invention adopts a single-fire "one-forging forming" for the first time to obtain a sleeve forging with an inner hole of a certain depth, which has the advantages of small processing allowance, high material utilization, low cost, and high production efficiency; 2) By adopting the process designed by the present invention, the material consumption can be reduced by more than 40%, the weight of the forging can be reduced by more than 40%, the number of forging fires can be reduced by more than 50%, and the machining time can be reduced by more than 20%; 3) The present invention can achieve flash-free forging, avoid the risk of the cross-section grain streamline of the sleeve forging being cut off and exposed, improve the stress corrosion resistance and fatigue performance of the parts, and help the aircraft to meet the service requirements for the safety and reliability of key components. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0028] Figure 3 A schematic diagram of a 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 A schematic diagram of a landing gear sleeve forging assembly die of the present invention;

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

[0032] In the figure, 1 is a cylindrical blank, 2 is an upper die, 3 is a lower die, 4 is a left horizontal die, 5 is a right horizontal die, 6 is a landing gear sleeve forging, 7 is a horizontal die supporting section, 8 is a horizontal die working section, 9 is a horizontal die supporting section diameter, and 10 is a horizontal die working section diameter. DETAILED DESCRIPTION

[0033] In order to deepen the understanding of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but it does not constitute a limitation on the scope of protection of the present invention. The following takes a sleeve forging for a certain type of civil aircraft landing gear as an example to explain the manufacturing method of the present invention in detail. The outer contour of the forging is as follows Figure 1 As shown, it is 1020mm long, the left inner hole diameter is 115mm, the left inner hole depth is 390mm, the right inner hole diameter is 115mm, the right inner hole depth is 280mm, the left end (the end with smaller diameter) of the forging has a non-convex part with a central opening cylindrical shape, and its diameter is 152mm; the right end (the end with larger diameter) of the forging has a non-convex part with a central opening cylindrical shape, and its diameter is 165mm; Specific manufacturing steps:

[0034] Step 1: Design the joint molds 2 to 5 and the cylindrical blank 1 (whose material is 300M ultra-high strength steel) according to the outer dimensions of the forging. Among them, the horizontal molds 4 and 5 both adopt a "mushroom-shaped" structure design, and their structural features are: the horizontal mold working section 8 is made of GH4169 alloy material, the diameter of the horizontal mold working section is 10, and its size is 115mm; the horizontal mold support section 7 is made of 5CrMnMo, the diameter of the horizontal mold support section is 9, and its size is 95mm (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); the support section 7 and the working section 8 are connected to each other by surfacing. The outer dimensions of the blank 1 are a cylinder with a diameter of 150mm and a length of 705mm;

[0035] Step 2: Heat the blank 1 (made of 300M steel and in the shape of a uniform straight cylinder) to a forging temperature of 1150°C, and then place the heated blank 1 horizontally in the cavity of the lower die 3;

[0036] Step 3: The upper die 2 moves downward and contacts the blank 1 to complete the pressing action. This step is similar to the conventional forging deformation process, but the diameter Amm of the cylindrical blank is smaller than the minimum diameter Bmm of the cylindrical body of the sleeve forging, BA=2.5mm, so 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 shape part of the left end of the sleeve forging is 152mm, and the diameter of the cylindrical outer shape part of the right end of the sleeve forging is 165mm)

[0037] Step 4: The upper mold 2 keeps the pressure and stops, the left horizontal mold 4 and the right horizontal mold 5 join the action, the left horizontal mold 4 moves to the right and contacts the blank 1, at the same time, the right horizontal mold 5 moves to the left and contacts the blank 1, and the left horizontal mold 4 and the right horizontal mold 5 move 255mm to the target position respectively; in this embodiment, although the structural dimensions of the left and right horizontal molds are the same, the left and right inner cavity diameters of the forging are different, the left side is thin and the right side is thick, so 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, they all move 255mm, but the depth of the left inner hole can be 390mm and the depth of the right inner hole can be 280mm, and the metal flows in the cavity formed by the closure of the upper mold 2, the lower mold 3, the left horizontal mold 4 and the right horizontal mold 5; (when the left and right horizontal molds move, their movement speed is 8mm / s)

[0038] Step 5: The left and right horizontal dies perform return motions respectively, and the inner hole of the sleeve forging is shaped while demolding, and finally the required landing gear sleeve die forging 6 is obtained. The mechanical properties of the obtained landing gear sleeve die forging 6 are shown in the following table:

[0039]

[0040] If the traditional die forging method is used, the weight of the forging is 165Kg, the weight of the feed is 195Kg, and it needs to be made into a blank for 2 times, die forged for 1 time, and the flash needs to be removed after die forging. However, by adopting the technology of the present invention, the weight of the forging can be reduced from 165Kg to 95Kg, a reduction of 42.4%; the feed weight is reduced from 195Kg to 98Kg, a reduction of 49.4%; the number of forging times is reduced from 3 times to 1 time, a reduction of 66.7%; after die forging, only the burrs need to be polished, and there is no need to remove the flash. It can be seen from the above data that the technology of the present invention has significant beneficial results.

Claims

1. A short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging, characterized in that: The following steps are involved: Step 1: Design a combined die and a cylindrical blank according to the outer dimensions of the sleeve forging; the combined die includes an upper die, a lower die, a left horizontal die and a right horizontal die; the left horizontal die and the right horizontal die are "mushroom-shaped", wherein the "mushroom head" contacts the blank and is the working section; the "mushroom rod" is the supporting section and does not contact the blank, and the diameter of the working section of the horizontal die is larger than the diameter of the supporting 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°C; Step 3: The upper die moves downward and contacts the blank to complete the pressing action. The minimum diameter of the cylindrical blank used is smaller than the cylindrical main body diameter of the sleeve forging. The cylindrical minimum main body diameter of the sleeve forging - the cylindrical blank diameter = C. The value range of C is greater than 0 and less than or equal to 5 mm. Step 4: The upper mold keeps the pressure and stops, the left horizontal mold and the right horizontal mold join the action, the left horizontal mold moves horizontally to the right to contact the blank, and at the same time, the right horizontal mold moves horizontally to the left to contact the blank, and the left and right horizontal molds move to the specified target positions respectively. 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 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; Step 5: The left and right horizontal dies perform return motions respectively, and the inner hole of the sleeve forging is shaped while demolding, and finally the required landing gear sleeve die forging is obtained.

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

3. A short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging according to claim 1, characterized in that: The 300M steel landing gear sleeve die forgings were obtained by non-blanketing and fire die forging.

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

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

6. A short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging 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, which is 2 to 5 times the diameter of the working section of the horizontal die. 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 upper and lower dies, which is 2.2 to 4.5 times the diameter of the working section of the horizontal die.

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

8. The short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging according to claim 1 is characterized in that: During operation, the working section of the left horizontal mold and the working section of the right horizontal mold are on the same axis; the supporting section of the left horizontal mold and the supporting section of the right horizontal mold are also on the same axis; the center of the working section of the left horizontal mold and the center of the working section of the right horizontal mold and the two ends of the cylindrical blank are on the same straight line.

9. A short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging according to claim 1, characterized in that: The length of the working sections of the left and right horizontal molds is 40-80 mm; the length of the supporting sections of the left and right horizontal molds is greater than the depth of the corresponding left and right inner holes.

10. A short-process and low-cost preparation method for a 300M steel landing gear sleeve die forging according to claim 1, characterized in that: The working section and the supporting section of the horizontal mold are designed separately and made of different materials, wherein the material of the working section of the horizontal mold is a high-temperature alloy; and the material of the supporting section is a mold steel material.

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