Wagon swing bolster light-weight aluminum alloy welding structure and technology

Abstract

The invention discloses a railway wagon swing bolster lightweight aluminum alloy welding structure and process. The railway wagon swing bolster lightweight aluminum alloy welding structure comprises a swing bolster body and a mounting base assembly. The swing bolster body is formed by splicing and welding aluminum alloy plates, reinforcing rib plates are arranged in the swing bolster body, and the mounting base assembly is fixed to a key stress part through double-layer welding and local thickening design. MIG and TIG technologies are adopted in the welding process, precise parameter control is combined, and residual stress is eliminated through heat treatment. The aluminum alloy material replaces steel, the weight is remarkably reduced, the strength and the anti-fatigue performance are improved, and the method is suitable for complex working conditions. The purposes of high efficiency, energy conservation, safety and reliability can be achieved, the requirements of modern rail wagons are met, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of rail transit equipment, and specifically relates to a lightweight aluminum alloy welded structure and process for the bolster of a railway freight car. Background Art

[0002] As a core component of the bogie, the structural design and manufacturing process of the bolster of a railway freight car have an important impact on vehicle performance, running safety, and lightweight requirements. At present, most bolsters adopt traditional steel welding or forging structures. Although they perform well in terms of strength and reliability, there are certain limitations in lightweight design and material property optimization, making it difficult to fully meet the requirements of modern railway freight cars for energy efficiency and weight reduction.

[0003] After retrieval, the patent with the publication number CN106696980B relates to a bolster for a railway express freight car bogie, and the publication date is November 30, 2018. This patent uses a forged secondary rubber spring mounting seat instead of a welded structure to improve the strength of key parts, and improves the heat dissipation performance by optimizing the height design of the mounting seat. However, this technical solution still uses traditional steel as the main material and fails to achieve lightweight design from the material level. At the same time, the forging process has a high cost and is limited in application in large-scale production. In addition, this solution does not introduce lightweight materials such as aluminum alloy, and the overall weight reduction is limited, showing a certain gap from the requirements of railway freight cars for weight reduction and energy conservation and emission reduction.

[0004] Another patent with the publication number CN106809233B relates to a railway express freight car bogie, and the publication date is also November 30, 2018. This patent uses a forged secondary rubber spring mounting seat in the bolster design to improve strength, and optimizes the dynamic performance of the bogie through the axle box elastic suspension system. However, this technical solution is still based on traditional steel manufacturing and does not introduce lightweight materials such as aluminum alloy for structural optimization. In addition, this solution mainly focuses on improving the strength of the rubber spring mounting seat and enhancing the heat dissipation performance, and does not fully consider the lightweight design of the overall structure, resulting in high energy consumption of the bolster under complex working conditions, showing a certain gap from the requirements of modern railway freight cars for high energy efficiency.

[0005] The above problems indicate that there is still room for improvement in the existing railway freight car bolster technology in terms of lightweight design, material selection, and manufacturing process optimization, especially the insufficient application research on lightweight materials such as aluminum alloy, which limits the potential of the bolster in weight reduction and performance improvement. Therefore, the present invention provides a lightweight aluminum alloy welded structure and process for the bolster of a railway freight car, aiming to achieve the lightweight design of the bolster by using aluminum alloy materials and optimizing the welding process, while ensuring its strength and reliability, so as to meet the requirements of modern railway freight cars for energy efficiency and safety performance. Summary of the Invention

[0006] The object of the present invention is to provide a lightweight aluminum alloy welded structure and process for the bolster of a railway freight car, so as to solve the problems in the prior art that the bolster is made of traditional steel, resulting in a relatively large weight, high energy consumption, and the lack of full introduction of lightweight materials. At the same time, aiming at the insufficient strength and reliability of the existing bolster during operation under complex working conditions, as well as the possible defects in the aluminum alloy welding process, an optimized welding process is proposed.

[0007] To achieve the above object, the present invention provides the following technical solution: A lightweight aluminum alloy welded structure for the bolster of a railway freight car, including a bolster main body and a mounting seat assembly. The bolster main body is formed by splicing and welding multiple sections of aluminum alloy plates, and the mounting seat assembly is fixed to the key stress-bearing parts of the bolster main body by welding. The cross-section of the bolster main body is in a rectangular frame structure, and multiple reinforcing rib plates are arranged inside it. The reinforcing rib plates are evenly distributed along the length direction of the bolster main body and are welded to the inner wall of the bolster main body. The mounting seat assembly includes a secondary rubber spring mounting seat and a journal box elastic suspension mounting seat. The secondary rubber spring mounting seat is fixed to the bolster main body through a double-layer welding structure, and the journal box elastic suspension mounting seat enhances its anti-fatigue performance through a local thickening design.

[0008] The thickness of the aluminum alloy plate of the bolster main body is T1, and the thickness of the reinforcing rib plate is T2, where T2 is greater than T1 to improve the rigidity of the overall structure. The welding between the reinforcing rib plate and the inner wall of the bolster main body adopts a V-shaped groove form, with a groove angle of α°, and a weld width of W1. The double-layer welding structure between the secondary rubber spring mounting seat and the bolster main body includes a first-layer butt weld and a second-layer fillet weld. The depth of the first-layer butt weld is H1, and the width of the second-layer fillet weld is W2. The thickness of the local thickening area of the journal box elastic suspension mounting seat is T3, the length of the thickening area is L1, and the width is L2.

[0009] This welding process includes the following steps: Step 1: Pretreat the aluminum alloy plate to remove the surface oxide layer and oil stains to ensure the cleanliness of the welding surface; Step 2: Cut the aluminum alloy plates of the bolster main body into multiple sections according to the design dimensions and fix them with jigs to ensure the accurate splicing positions of each section of the plates; Step 3: Use the MIG welding process to splice and weld the aluminum alloy plates of the bolster main body, with a welding current of I1, a welding voltage of U1, and a welding speed of V1; Step 4: Install the reinforcing rib plates inside the bolster main body. After fixing the reinforcing rib plates to the designed positions with jigs, use the TIG welding process to complete the welding between the reinforcing rib plates and the inner wall of the bolster main body, with a welding current of I2, a welding voltage of U2, and a welding speed of V2; Step Five: Perform double-layer welding on the secondary rubber spring mounting seat. First, complete the welding of the first-layer butt weld, and then carry out the welding of the second-layer fillet weld. The welding parameters are I3, U3, V3 and I4, U4, V4 respectively. Step Six: Perform local thickening treatment on the axle box elastic suspension mounting seat, and fix it to the bolster body through the MIG welding process. The welding parameters are I5, U5, V5.

[0010] As a further solution of the present invention, the aluminum alloy plate of the bolster body is selected as 6061-T6 aluminum alloy, its tensile strength is R1, yield strength is R2, and elongation is E1. The material of the stiffening rib plate is the same as that of the bolster body, and the spacing of the stiffening rib plates is S1.

[0011] As a further solution of the present invention, in the double-layer welding structure of the secondary rubber spring mounting seat, the depth H1 of the first-layer butt weld is 70% of the thickness T1 of the bolster body plate, and the width W2 of the second-layer fillet weld is 50% of the thickness T1 of the bolster body plate.

[0012] As a further solution of the present invention, the thickness T3 of the local thickening area of the axle box elastic suspension mounting seat is 1.5 times the thickness T1 of the bolster body plate, the length L1 of the thickening area is 30% of the width of the bolster body, and the width L2 is 20% of the height of the bolster body.

[0013] To solve the above problems, the present invention also proposes a manufacturing method for a lightweight aluminum alloy welded structure of a railway freight car bolster, and this manufacturing method includes the following steps: Step One: Select aluminum alloy plates of corresponding specifications according to the design dimensions of the bolster body, and perform cutting and pretreatment on them. Step Two: Use a special fixture to fix the aluminum alloy plates on the welding platform to ensure the accurate splicing position of each section of the plates. Step Three: Complete the splicing welding of the bolster body through the MIG welding process, and polish the welds to ensure a smooth surface. Step Four: Install stiffening rib plates inside the bolster body, and complete the welding of the stiffening rib plates and the inner wall of the bolster body through the TIG welding process. Step Five: Weld and fix the secondary rubber spring mounting seat and the axle box elastic suspension mounting seat, and adopt a double-layer welding structure and a local thickening design respectively. Step Six: Perform heat treatment on the welded bolster body to eliminate welding residual stress and improve the strength and durability of the overall structure.

[0014] As a further solution of the present invention, the heat treatment process in step six includes solution treatment and artificial aging treatment. The solution treatment temperature is T4, the holding time is t1, the artificial aging treatment temperature is T5, and the holding time is t2.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: By using aluminum alloy materials to replace traditional steel and combining with optimized welding processes, the present invention significantly reduces the overall weight of the bolster while ensuring its strength and reliability under complex working conditions. The design of the rectangular frame structure of the bolster body and the stiffening rib plates effectively improves the structural rigidity, while the double-layer welding structure and the local thickening design enhance the anti-fatigue performance of key parts. In addition, the precise control of welding process parameters and the application of heat treatment processes further improve the welding quality and overall performance. The structural design of the present invention is compact and reasonable, easy to operate, suitable for large-scale production, and can meet the requirements of modern railway freight cars for energy efficiency and safety performance. Brief Description of the Drawings

[0016] Figure 1 It is an overall schematic diagram of the lightweight aluminum alloy welded structure of the bolster of the railway freight car of the present invention; Figure 2 It is a partial enlarged view of the double-layer welding structure of the secondary rubber spring mounting seat; Figure 3 It is a schematic diagram of the local thickening design of the axle box elastic suspension mounting seat.

[0017] In the figure: 1, bolster body; 2, stiffening rib plate; 3, secondary rubber spring mounting seat; 4, axle box elastic suspension mounting seat; 5, first layer butt weld; 6, second layer fillet weld; 7, local thickening area. Detailed Description of the Preferred Embodiments

[0018] The present invention provides a lightweight aluminum alloy welded structure and process for the bolster of a railway freight car. The following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. As Figures 1 to 3 shown, the lightweight aluminum alloy welded structure of the bolster of the railway freight car of the present invention includes a bolster body 1, a stiffening rib plate 2, a secondary rubber spring mounting seat 3, and an axle box elastic suspension mounting seat 4. These components are interconnected through optimized welding processes and structural designs to form an integral structure to meet the strength and reliability requirements of railway freight cars under complex working conditions.

[0019] The bolster body 1 is the core part of the entire structure. Its cross-section is a rectangular frame structure, which is spliced by multiple sections of aluminum alloy plates. The aluminum alloy plates are made of 6061-T6 aluminum alloy. This material has a relatively high tensile strength R1 and yield strength R2, and at the same time has good elongation E1, which can meet the mechanical property requirements of the bolster in actual use. The thickness of the aluminum alloy plate is T1. According to the design requirements, T1 is usually between 8 mm and 12 mm to ensure that the bolster body 1 achieves the goal of lightweight while ensuring strength. During the splicing process, each section of the aluminum alloy plate is fixed on the welding platform by a special fixture to ensure that the splicing position is accurate. Subsequently, the MIG welding process is used to complete the splicing welding. The welding current I1 is set to 180 A to 220 A, the welding voltage U1 is set to 24 V to 28 V, and the welding speed V1 is set to 15 cm per minute to 20 cm per minute. After welding, the surface of the weld needs to be polished to ensure that the surface is smooth and there are no obvious welding defects.

[0020] There are multiple reinforcing rib plates 2 inside the bolster body 1. These reinforcing rib plates 2 are evenly distributed along the length direction of the bolster body 1 and form a welded connection with the inner wall of the bolster body 1. The material of the reinforcing rib plates 2 is also selected as 6061-T6 aluminum alloy, and its thickness is T2. T2 is greater than T1, usually between 10 mm and 15 mm, to improve the rigidity of the overall structure. The welding between the reinforcing rib plates 2 and the inner wall of the bolster body 1 adopts the V-groove form, and the groove angle α° is set to 45 degrees to 60 degrees, and the weld width W1 is 8 mm to 12 mm. Before welding, the reinforcing rib plates 2 need to be fixed at the designed position by fixtures to prevent displacement during the welding process. The TIG welding process is used during the welding process. The welding current I2 is set to 120 A to 160 A, the welding voltage U2 is set to 18 V to 22 V, and the welding speed V2 is set to 10 cm per minute to 15 cm per minute. The spacing S1 of the reinforcing rib plates 2 is determined according to the design size of the bolster body 1, usually between 300 mm and 500 mm, to ensure the overall rigidity and stability of the structure.

[0021] The secondary rubber stack mounting seat 3 is fixed to the key stress-bearing part of the bolster body 1 through a double-layer welding structure. The double-layer welding structure includes the first-layer butt weld 5 and the second-layer fillet weld 6. The depth H1 of the first-layer butt weld 5 is 70% of the thickness T1 of the bolster body 1 plate, that is, when T1 is 10 mm, H1 is set to 7 mm. The width W2 of the second-layer fillet weld 6 is 50% of the thickness T1 of the bolster body 1 plate, that is, when T1 is 10 mm, W2 is set to 5 mm. During the welding process, first, the welding of the first-layer butt weld 5 is completed, and the welding parameters are set as the welding current I3 is 160 A to 200 A, the welding voltage U3 is 22 V to 26 V, and the welding speed V3 is 12 cm per minute to 18 cm per minute. Subsequently, the welding of the second-layer fillet weld 6 is carried out, and the welding parameters are set as the welding current I4 is 140 A to 180 A, the welding voltage U4 is 20 V to 24 V, and the welding speed V4 is 10 cm per minute to 15 cm per minute. Through the design of this double-layer welding structure, the connection strength between the secondary rubber stack mounting seat 3 and the bolster body 1 can be effectively improved, thereby enhancing the anti-fatigue performance of the key part.

[0022] The axle box elastic suspension mounting seat 4 enhances its anti-fatigue performance through local thickening design. The thickness T3 of the local thickening area 7 is 1.5 times the thickness T1 of the bolster body 1 plate, that is, when T1 is 10 mm, T3 is set to 15 mm. The length L1 of the thickening area 7 is 30% of the width of the bolster body 1, and the width L2 is 20% of the height of the bolster body 1. For example, when the width of the bolster body 1 is 500 mm and the height is 300 mm, L1 is set to 150 mm and L2 is set to 60 mm. The local thickening area 7 is fixed to the bolster body 1 through the MIG welding process, and the welding parameters are set as the welding current I5 is 180 A to 220 A, the welding voltage U5 is 24 V to 28 V, and the welding speed V5 is 15 cm per minute to 20 cm per minute. Through the local thickening design, the anti-fatigue performance of the axle box elastic suspension mounting seat 4 under complex working conditions can be significantly improved, thereby extending its service life.

[0023] After welding is completed, heat treatment needs to be carried out on the bolster body 1 to eliminate welding residual stress and improve the strength and durability of the overall structure. The heat treatment process includes solution treatment and artificial aging treatment. The solution treatment temperature T4 is set to 520 °C to 540 °C, and the holding time t1 is set to 1 hour to 2 hours. Subsequently, artificial aging treatment is carried out, the temperature T5 is set to 160 °C to 180 °C, and the holding time t2 is set to 8 hours to 12 hours. Through the application of the heat treatment process, the welding quality and overall performance can be further improved, ensuring the reliability and safety of the bolster in actual use.

[0024] In practical applications, the lightweight aluminum alloy welded structure of the bolster for railway wagons of the present invention is mainly used in the suspension system of railway wagons. The bolster body 1 is connected to the car body through the secondary rubber pad mounting seat 3, and at the same time is connected to the bogie through the axle box elastic suspension mounting seat 4. During the operation of the train, the bolster body 1 bears the loads from the car body and the bogie, and distributes the loads evenly to each component through the reinforcing rib plates 2 and the welded structure. The double-layer welded structure of the secondary rubber pad mounting seat 3 and the local thickening design of the axle box elastic suspension mounting seat 4 can effectively resist the dynamic loads under complex working conditions, thereby improving the fatigue resistance and service life of the overall structure. In addition, due to the use of aluminum alloy material to replace traditional steel, the overall weight of the bolster of the present invention is significantly reduced, which helps to reduce the energy consumption during the operation of the train and improve the transportation efficiency.

[0025] The manufacturing method of the present invention includes the following steps: First, select aluminum alloy plates of corresponding specifications according to the design dimensions of the bolster body 1, and cut and pre-treat them to remove the surface oxide layer and oil stains to ensure the cleanliness of the welding surface. Secondly, use special fixtures to fix the aluminum alloy plates on the welding platform to ensure the accurate splicing positions of each section of the plates. Subsequently, complete the splicing welding of the bolster body 1 through the MIG welding process, and grind the welds to ensure a smooth surface. Then install the reinforcing rib plates 2 inside the bolster body 1, and complete the welding of the reinforcing rib plates 2 and the inner wall of the bolster body 1 through the TIG welding process. Then weld and fix the secondary rubber pad mounting seat 3 and the axle box elastic suspension mounting seat 4, and adopt the double-layer welded structure and the local thickening design respectively. Finally, perform heat treatment on the welded bolster body 1 to eliminate the welding residual stress and improve the strength and durability of the overall structure. Through the above steps, the production of the lightweight aluminum alloy welded structure of the bolster for railway wagons of the present invention can be realized, ensuring its performance and reliability in practical applications.

[0026] In order to better enable the relevant personnel in the technical field to fully understand and implement the present invention, the following further supplements and explains the specific implementation principle of the present invention in combination with a specific application scenario.

[0027] During the actual operation of railway wagons, the bolster body 1 is connected to the car body through the secondary rubber pad mounting seat 3 and forms an integral structure with the bogie through the axle box elastic suspension mounting seat 4. When the train starts or runs, complex dynamic loads will be generated between the car body and the bogie. These loads are transmitted to the bolster body 1 through the secondary rubber pad mounting seat 3, and then evenly distributed to the entire structure by the reinforcing rib plates 2 inside the bolster body 1. The setting of the reinforcing rib plates 2 not only improves the overall rigidity of the bolster body 1, but also effectively reduces the deformation risk caused by local stress concentration. The welding between the reinforcing rib plates 2 and the inner wall of the bolster body 1 adopts the V-groove form, which can increase the effective bearing area of the weld, thereby enhancing the tensile strength and fatigue resistance of the welded joint.

[0028] Under complex working conditions, such as when the train is running at high speed or passing through an uneven track, the secondary suspension rubber stack mounting seat 3 bears large vertical and horizontal loads. The design of the double-layer welded structure plays an important role in this process. The depth of the first butt weld 5 is 70% of the thickness T1 of the bolster body 1 plate, ensuring that the weld can penetrate deep into the base material, thereby improving the shear resistance of the welded joint; the second fillet weld 6 further enhances the tear resistance of the weld through its design with a width of 50% of T1. This double-layer welded structure not only significantly improves the connection strength between the secondary suspension rubber stack mounting seat 3 and the bolster body 1, but also effectively disperses the stress concentration phenomenon at the key stress-bearing parts, thereby extending the overall service life of the bolster.

[0029] The axle box elastic suspension mounting seat 4 mainly bears the dynamic load from the bogie during the train operation. Due to the design of its local thickening area 7, the fatigue resistance of this part has been significantly improved. The thickness of the local thickening area 7 is 1.5 times the thickness T1 of the bolster body 1 plate, the length is 30% of the width of the bolster body 1, and the width is 20% of the height of the bolster body 1. This design enables the axle box elastic suspension mounting seat 4 to effectively resist the fatigue crack propagation of the material when bearing high-frequency vibration or impact loads. At the same time, the local thickening area 7 is fixed to the bolster body 1 by MIG welding process, and the precise control of welding parameters ensures the quality and reliability of the weld.

[0030] In the actual manufacturing process, the pretreatment of the aluminum alloy plate is one of the key steps to ensure the welding quality. First, the surface of the aluminum alloy plate needs to be mechanically polished and chemically cleaned to remove impurities such as oxide layers and oil stains. Subsequently, the cut aluminum alloy plates are fixed on the welding platform by special fixtures to ensure that the splicing positions of each section of the plates are accurate. During the splicing and welding process, the MIG welding process is adopted, the welding current is set to 180 amperes to 220 amperes, the welding voltage is set to 24 volts to 28 volts, and the welding speed is set to 15 cm per minute to 20 cm per minute. After welding, the surface of the weld is polished to eliminate possible welding defects and improve the surface finish.

[0031] The installation process of the stiffening rib plate 2 also requires strict control of welding parameters. Before welding, the stiffening rib plate 2 is fixed at the designed position by fixtures to prevent displacement during the welding process. The TIG welding process is adopted during the welding process, the welding current is set to 120 amperes to 160 amperes, the welding voltage is set to 18 volts to 22 volts, and the welding speed is set to 10 cm per minute to 15 cm per minute. The advantage of the TIG welding process is that it can provide higher welding precision and better control of heat input, thereby reducing the generation of welding residual stress.

[0032] After welding is completed, the bolster body 1 needs to be heat-treated to further improve its mechanical properties and durability. The heat treatment process includes solution treatment and artificial aging treatment. The solution treatment temperature is set at 520 °C to 540 °C, and the holding time is set at 1 hour to 2 hours. This process can fully dissolve the alloying elements in the aluminum alloy, thereby improving the strength and toughness of the material. The artificial aging treatment temperature is set at 160 °C to 180 °C, and the holding time is set at 8 hours to 12 hours. This process can promote the uniform distribution of the precipitation phase, thereby further enhancing the fatigue resistance of the material.

[0033] The lightweight aluminum alloy welded structure of the bolster fabricated through the above steps exhibits excellent performance in practical applications. The rectangular frame structure design of the bolster body 1 achieves a significant lightweight effect while ensuring strength, and the optimized welding process and heat treatment process ensure the overall reliability and durability of the structure. In addition, the selection of aluminum alloy material not only reduces the overall weight of the bolster but also decreases the energy consumption during train operation, thus meeting the requirements of modern railway freight cars for energy efficiency and safety performance.

[0034] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lightweight aluminum alloy welded structure for the bolster of a railway freight car, comprising a bolster body (1) and a mounting seat assembly, characterized in that: The bolster body (1) is formed by splicing and welding aluminum alloy plates, and its cross-section is a rectangular frame structure. A plurality of reinforcing rib plates (2) are arranged inside, and the reinforcing rib plates (2) are evenly distributed along the length direction of the bolster body (1) and are welded to the inner wall of the bolster body (1); the mounting seat assembly includes a secondary rubber stack mounting seat (3) and an axle box elastic suspension mounting seat (4). The secondary rubber stack mounting seat (3) is fixed to the bolster body (1) through a double-layer welding structure, and the axle box elastic suspension mounting seat (4) enhances the fatigue resistance through a local thickening design.

2. The lightweight aluminum alloy welded structure of the bolster of a railway freight car according to claim 1, characterized in that: The thickness of the aluminum alloy plate of the bolster body (1) is T1, and the thickness of the reinforcing rib plate (2) is T2, where T2 is greater than T1; the welding between the reinforcing rib plate (2) and the inner wall of the bolster body (1) adopts a V-shaped groove form, the groove angle is α°, and the weld width is W1.

3. The lightweight aluminum alloy welded structure of the bolster of a railway freight car according to claim 1, wherein: The double-layer welding structure between the secondary rubber stack mounting seat (3) and the bolster body (1) includes a first-layer butt weld (5) and a second-layer fillet weld (6). The depth of the first-layer butt weld (5) is H1, and the width of the second-layer fillet weld (6) is W2.

4. The lightweight aluminum alloy welded structure of the bolster of a railway freight car according to claim 1, characterized in that: The thickness of the local thickening area (7) of the axle box elastic suspension mounting seat (4) is T3, the length of the thickening area (7) is L1, and the width is L2.

5. The lightweight aluminum alloy welded structure of the bolster of a railway freight car according to any one of claims 1 to 4, characterized in that: The aluminum alloy plate of the bolster body (1) is made of 6061-T6 aluminum alloy. The material of the reinforcing rib plate (2) is the same as that of the bolster body (1), and the spacing of the reinforcing rib plates (2) is S1.

6. The lightweight aluminum alloy welded structure of the bolster of a railway wagon according to claim 3, characterized in that: The depth H1 of the first-layer butt weld (5) is 70% of the thickness T1 of the bolster body (1) plate, and the width W2 of the second-layer fillet weld (6) is 50% of the thickness T1 of the bolster body (1) plate.

7. The lightweight aluminum alloy welded structure of the bolster of a railway freight car according to claim 4, characterized in that: The thickness T3 of the local thickening area (7) of the axle box elastic suspension mounting seat (4) is 1.5 times the thickness T1 of the bolster body (1) plate. The length L1 of the thickening area (7) is 30% of the width of the bolster body (1), and the width L2 is 20% of the height of the bolster body (1).

8. A manufacturing method of a lightweight aluminum alloy welded structure for a bolster of a railway freight car, characterized in that It includes the following steps: Step 1: Pretreat the aluminum alloy plate to remove the surface oxide layer and oil stains to ensure the cleanliness of the welding surface; Step 2: Cut the aluminum alloy plates of the bolster body (1) into multiple segments according to the design dimensions and fix them with jigs to ensure the accurate splicing position of each segment of the plate; Step 3: Use the MIG welding process to splice and weld the aluminum alloy plates of the bolster body (1), with the welding current being I1, the welding voltage being U1, and the welding speed being V1; Step 4: Install the reinforcing rib plates (2) inside the bolster body (1). After using the jig to fix the reinforcing rib plates (2) at the designed positions, use the TIG welding process to complete the welding between the reinforcing rib plates (2) and the inner wall of the bolster body (1), with the welding current being I2, the welding voltage being U2, and the welding speed being V2; Step 5: Perform double-layer welding on the secondary rubber stack mounting seat (3). First, complete the welding of the first-layer butt weld (5), and then perform the welding of the second-layer fillet weld (6), with the welding parameters being I3, U3, V3 and I4, U4, V4 respectively; Step 6: Locally thicken the axle box elastic suspension mounting seat (4), and fix it to the bolster body (1) through the MIG welding process. The welding parameters are I5, U5, and V5.

9. The manufacturing method of the lightweight aluminum alloy welded structure of the bolster of a railway freight car according to claim 8, characterized in that: It also includes heat treatment of the welded bolster body (1). The heat treatment process includes solution treatment and artificial aging treatment. The solution treatment temperature is T4, the holding time is t1, the artificial aging treatment temperature is T5, and the holding time is t2.

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