A method for retrofitting a corrugated roof of a rail transit vehicle to maintain air tightness

Abstract

The application discloses a rail transit vehicle corrugated plate roof transformation method which maintains air tightness. The corrugated plate covers a plurality of main cross beams on the roof, and a mechanical interface is welded on a wave trough of the corrugated plate and a welding position overlapping the main cross beam by TIG or MAG welding.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, specifically to a method for modifying the corrugated roof of a rail transit vehicle to maintain airtightness. Background Technology

[0002] Lightweight design of rail transit vehicles is crucial for reducing axle load and saving energy, and is also a key development direction for rail transit vehicles. To minimize vehicle weight, the stainless steel roof design typically uses a combination of 3mm main crossbeams and 0.6mm stainless steel corrugated plates. The main crossbeams support the corrugated plates and roof equipment, and are spaced apart along the vehicle's transverse direction. The corrugated plates provide airtightness, isolating the vehicle from external elements. The main crossbeams and corrugated plates are connected by resistance spot welding. Therefore, airtightness is one of the key indicators of the roof, making it a critical factor in design, manufacturing, modification, and maintenance.

[0003] During the project renovation, it is inevitable that various mechanical interfaces of equipment will be welded onto the roof. However, due to the limitations of the resistance spot welding equipment, the resistance spot welding method used in the new construction phase is no longer permitted. Tungsten inert gas (TIG) or gas metal arc welding (MAG) must be used. However, both of these welding methods have a large heat input, which can easily burn through the corrugated plate and cause the roof's airtightness to fail, seriously affecting the rail transit vehicle.

[0004] Therefore, during the renovation, it is necessary to comprehensively consider various requirements such as equipment needs, mechanical interface design, roof structure, welding process, and failure prevention to design an airtight solution suitable for thin corrugated plate roofs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for modifying the corrugated roof of rail transit vehicles to maintain airtightness, and its structure solves the problems in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for modifying the corrugated roof of a rail transit vehicle to maintain airtightness, wherein the corrugated sheet covers several main crossbeams on the roof, and mechanical interfaces are welded to the troughs of the corrugated sheet and the welding positions that overlap with the main crossbeams using TIG or MAG welding.

[0008] As a preferred technical solution, the two ends of the mechanical interface are welded to the overlapping troughs of the adjacent two main crossbeams and corrugated plates.

[0009] As a preferred technical solution, the mechanical interface is folded and bent into a gate-shaped structure at both ends; the folded ends of the mechanical interface are provided with several notches to avoid the crests of the corrugated plates.

[0010] As a preferred technical solution, reinforcing ribs are provided at the middle of both ends of the mechanical interface fold.

[0011] As a preferred technical solution, the following processes are also included: after welding, the weld is subjected to flaw detection and air tightness test; after the flaw detection and air tightness test are passed, the weld is de-blackened and passivated.

[0012] Compared with existing technologies, this method offers the following advantages: the mechanical interface is welded to the overlap between the corrugated plate and the main crossbeam, specifically at the trough of the corrugated plate. Because the trough of the corrugated plate overlaps with the main crossbeam, it fits snugly against the main crossbeam. Therefore, compared to other areas of the corrugated plate, the constraint of the main crossbeam reduces the likelihood of burn-through and air leakage when using TIG or MAG welding, thus ensuring the airtightness of the roof. Attached Figure Description

[0013] Figure 1 This is a top view of the vehicle's roof;

[0014] Figure 2 This is a side sectional view of the roof.

[0015] The attached diagram is labeled as follows: 1-Mechanical interface, 2-Main crossbeam. Detailed Implementation

[0016] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for modifying the corrugated roof of rail transit vehicles to maintain airtightness. The invention will be further described in detail below with reference to embodiments.

[0017] Example 1

[0018] In this embodiment, the purpose of the roof modification is to install monitoring equipment to monitor the pantograph status. This equipment needs to be installed on the top of the vehicle, with an outline dimension of length: width: height = 251:143:112. The mounting point size is 173*143mm.

[0019] Before the modification, the roof structure of the vehicle used for equipment installation consisted of a 3mm main crossbeam at the top, with several other main crossbeams evenly distributed at intervals of 350-450mm. 0.6mm corrugated plates were connected to the main crossbeams using resistance spot welding, with each corrugated plate covering the main crossbeams as a single piece.

[0020] In this embodiment, all equipment installation points are located in the corrugated plate area.

[0021] The modification method described in this embodiment is as follows:

[0022] Step S1: Use TIG or MAG welding to weld the mechanical interface to the welding position on the corrugated plate. The location of the welding position must simultaneously meet the following conditions:

[0023] (1) Located between two adjacent main beams;

[0024] (2) Located at the trough of the corrugated plate;

[0025] (3) Located at the overlap of the corrugated plate and the main beam.

[0026] Step S2: Perform flaw detection on the weld after welding. The flaw detection results should meet the requirements of ISO10042-B. Perform an airtightness test after welding.

[0027] Step S3: After passing the flaw detection and airtightness test, the weld is de-blackened and passivated.

[0028] After the mechanical interfaces are welded, the minimum distance from the crest of the corrugated plate is 55mm, and the height of the mechanical interfaces from the rail surface remains consistent throughout the entire vehicle.

[0029] In this embodiment, the mechanical interface is made of 3mm steel plate bent into a gate-shaped structure at both ends. Since the two ends of the folded mechanical interface are in contact with and welded to the corrugated plate, the two ends of the folded mechanical interface are provided with several notches at intervals to avoid the crests of the corrugated plate.

[0030] Because the span between two adjacent main beams is large, the bending resistance of the middle area of ​​the mechanical interface is insufficient. Therefore, reinforcing ribs are provided at the middle of both ends of the mechanical interface to improve the rigidity of the mechanical interface.

[0031] In this embodiment, the mechanical interface is welded to the overlap between the corrugated plate and the main crossbeam, and is located in the trough of the corrugated plate. Because the trough of the corrugated plate overlaps with the main crossbeam and fits snugly against it, compared to other areas of the corrugated plate, the main crossbeam restricts the flow, making it less likely for the corrugated plate to burn through and leak air when using TIG or MAG welding, thus ensuring the airtightness of the roof.

[0032] To ensure a secure connection between the mechanical interface and the roof, while avoiding damage to the roof corrugated sheet, the connection between the mechanical interface and the roof is located at main crossbeam 1 and main crossbeam 2. The main crossbeams are made of 3mm cold-formed steel, providing sufficient strength.

[0033] The present invention can be well implemented according to the above embodiments. It is worth noting that, based on the above structural design, even if some non-substantial modifications or refinements are made to the present invention to solve the same technical problem, the essence of the technical solution adopted is still the same as that of the present invention, and therefore it should also be within the protection scope of the present invention.

Claims

1. A method for retrofitting a corrugated roof of a rail transit vehicle to maintain air tightness, the corrugated roof covering a plurality of main beams of the roof, characterized in that, The welding position of the mechanical interface is the position where the TIG or MAG welding is performed on the trough of the corrugated plate and overlaps with the main beam; The welding position satisfies the following conditions simultaneously: Located between two adjacent main beams; located at the trough of the corrugated plate; located at the overlapping position of the corrugated plate and the main beam; The two ends of the mechanical interface are welded at the overlapping positions of the trough of the corrugated plate and the two adjacent main beams respectively; The two ends of the mechanical interface are folded into a door-shaped structure; a plurality of gaps for avoiding the corrugated plate peaks are arranged between the two ends of the mechanical interface; A reinforcing rib is arranged at the middle part of the two ends of the mechanical interface.

2. A method of retrofitting a corrugated roof of a rail transit vehicle maintaining air tightness according to claim 1, characterized in that, The process further comprises the following steps: after welding, the weld is subjected to flaw detection and air tightness test; after the flaw detection and air tightness test, the black passivation of the weld is removed.

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