Method for repairing welding thermal stress deformation of arc-shaped side plate of railway wagon

Abstract

The invention provides a method for repairing welding thermal stress deformation of arc-shaped side plates of a railway wagon, which comprises the following steps of: aligning a concave area between two arc-shaped side plates on two sides of a railway wagon body, and transversely supporting the concave area by using a plurality of rod-shaped supporting bodies; the outer side of the welding seam jacked by the supporting body is polished, so that the welding seam is in a flat state; aligning the center of the ground part of the welding seam, and marking a center line; a cutting tool is used for cutting a groove used for welding operation along the center line; welding operation is carried out along the groove from top to bottom; after the welding operation is finished, spraying cooling water to a welding seam and a heat affected zone from top to bottom for accelerated cooling; and after the welding seam and the nearby area are completely cooled, the multiple supporting bodies arranged in the vehicle body are detached. According to the invention, a large-scale upender is not needed to turn the vehicle body on one side, so that the sunken part repairing operation becomes simple and convenient; welding seams in a stress concentration area do not need to be completely cut open for double-face welding, welding equipment does not need to be hoisted to the upper portion of a vehicle body, and the repairing process is simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a method for repairing welding thermal stress deformation of an arc-shaped side plate of a railway freight car. Background Art

[0002] With the continuous development of railway freight, the demand for the diversity of railway freight cars is increasing. Railway freight hopper cars with large carrying capacity and curved side panels for transporting grain or ore are one of the more complex structures. The curved side panels on both sides of the body of this railway freight hopper car are welded together with several 4mm thick ferritic stainless steel curved plates, and the curved side panels are connected to several partitions in the body by welding. The specific operation method is as follows:

[0003] First, the ferritic stainless steel sheet is laid on the curved tire, butted and welded to form a whole curved side panel. The upper and lower ends of the curved side panel must be assembled with the upper and lower side beams and welded. After welding, the curved side panel together with the upper and lower side beams are assembled to the whole vehicle; then it is welded and fixed to the contact surfaces such as the interior partition, the end plates at both ends, and the bottom floor to form the vehicle body. Such a large amount of welding produces excessive welding line energy, resulting in a large amount of stress accumulated inside the ferritic stainless steel curved side panel. This stress cannot be released in a closed state, and eventually causes the curved side panel to be partially dented and deformed. Repairing the local dent is a very complicated process.

[0004] In order to repair the local sunken deformation, the repair method adopted in the prior art is as follows:

[0005] 1. Use a large turning machine to turn the car body sideways, and turn the side of the curved side panel to be repaired to the bottom;

[0006] 2. Use a large number of support rods to lift and fix the sunken curved side panel parts and the welds closest to the sunken areas;

[0007] 3. Use an angle grinder to grind 80% of the length of the weld closest to the inner concave area of ​​the arc-shaped side panel. The purpose is to release the stress along the center of the weld. Then use manual CO2 gas shielded welding to weld the inner weld. After the inner weld is welded, turn the arc-shaped side panel over to the top.

[0008] 4. Use a grinding wheel to grind the weld nodules on the outside of the weld flat and clean the roots;

[0009] 5. Use semi-automatic welding to weld the outer weld;

[0010] 6. After welding is completed, remove all the supports inside the vehicle after the weld has completely cooled.

[0011] The whole process takes 4-5 hours, but there is still a 40% chance that the heat input during welding will cause secondary depression due to the re-constraint stress after welding repair. At this time, the whole process must be repeated.

[0012] From the above description, it can be seen that the prior art has the following defects:

[0013] 1. When repairing dents, a separate site is required, and a large turning machine is used to turn the car body upside down;

[0014] 2. Too many internal supports are used, making operation difficult;

[0015] 3. It is necessary to discard 80% of the length of the weld closest to the depression or at the depression to release the stress, and the discarded weld needs to be turned over and polished on both sides before double-sided welding, which is a complicated process;

[0016] 4. When welding and repairing the front of the curved side plate, the automatic welding and other related equipment need to be hoisted to the upper part of the car body by a crane, which is cumbersome to operate;

[0017] 5. When welding the front of the curved side plate, since the height is nearly 4 meters, the workers need to fasten their safety belts to the hook of the overhead crane to prevent people from falling. The risk factor of high-altitude work is high;

[0018] 6. The post-welding grinding and cleaning of splashes and the dismantling of the internal support of the vehicle body are too large, the labor intensity of the workers is high, and the repair efficiency is low; and it requires a total of 10 welders, grinders, riveters, etc., which consumes a large amount of personnel quota;

[0019] 7. The entire repair process takes 4-5 hours, with high labor intensity and low efficiency.

[0020] 8. The pass rate of one repair is only about 60%, which is low. Summary of the invention

[0021] In view of this, the present invention provides a method for repairing the concave deformation of thinner curved side panels due to the large local welding thermal stress inside during the welding process by using a simple, fast and reasonable method, thereby solving the technical problems of low efficiency and low qualified rate of repairing the concave deformation of the curved side panels.

[0022] To this end, this application provides the following technical solutions.

[0023] A method for repairing welding thermal stress deformation of a curved side plate of a railway freight car, the method comprising:

[0024] S1. Align the concave area between the two curved side plates on both sides of the railway freight car body, and use a plurality of rod-shaped support bodies to laterally support the concave area so that it reaches the original curvature of the curved side plates;

[0025] S2, grinding the outer side of the weld seam raised by the support body to make the weld seam flat, thereby forming a weld seam grinding flat part;

[0026] S3. Align the center of the flattened weld and draw a center line;

[0027] S4, using a cutting tool to cut a groove for welding along the center line;

[0028] S5, performing welding operation from top to bottom along the groove;

[0029] S6. After the welding operation is completed, water is poured from top to bottom on the weld and the heat-affected zone to accelerate the cooling speed of the weld, thereby avoiding the restraint stress caused by the slow cooling and shrinkage process of the weld and causing depression again;

[0030] S7. After the weld and the surrounding area are cooled, remove the plurality of supports placed in the vehicle body.

[0031] Furthermore, during the grinding operation, weld reserved portions not to be ground are respectively left on the upper and lower sides of the weld flattened portion and near the upper beam and the lower beam.

[0032] Furthermore, the length of the weld reserved portion is equal to 300 mm.

[0033] Furthermore, protective stickers are respectively attached to both sides of the groove to prevent metal splashes from contaminating the surface of the arc-shaped side plate during welding.

[0034] Furthermore, the material of the curved side panel is ferritic stainless steel, and the protective sticker is a magnetic sticker that can be magnetically adsorbed on the surface of the curved side panel.

[0035] Furthermore, the distance between the protective film and the edge of the groove is 30 mm.

[0036] Furthermore, during the welding operation, consumable CO2 gas shielded welding is adopted.

[0037] Furthermore, during welding, the welding gun angle is 90° to both sides of the weld, and the angle with the bottom of the weld is between 50° and 55°.

[0038] The beneficial effects of the present invention are as follows:

[0039] 1. There is no need to use a large-scale turning machine to turn the car body over. It only needs to be operated on one side on the outer side of the curved side panel. The weld on the inner side of the curved side panel does not need to be damaged, making the dent repair operation simple and convenient.

[0040] 2. There is no need to perform double-sided welding or hoist the welding equipment onto the upper part of the vehicle body, which simplifies the repair process.

[0041] 3. Operators do not need to perform high-altitude operations, which fundamentally eliminates safety hazards.

[0042] 4. By grinding the weld in the stress area of ​​the arc-shaped side plate, the thickness of the weld is reduced, and welding heating is used again to stretch the weld metal structure and thus achieve stress release.

[0043] 5. After the weld metal structure is heated and stretched, it is quickly cooled and shaped by pouring cold water to prevent the metal structure from shrinking too much due to slow cooling and causing new stress depression and deformation.

[0044] 6. Only 3 people can complete the dent repair work that previously took 10 people, and it only takes 30-40 minutes. While the pass rate is significantly improved, it also improves work efficiency and saves a lot of manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0046] Figure 1 It is a front view of the vehicle body in the present invention.

[0047] Figure 2 yes Figure 1 AA section view of the repair of the curved side panel dent.

[0048] Figure 3 It is a partial schematic diagram of the weld grinding of the repaired part of the arc-shaped side panel when repairing the dent.

[0049] Figure 4 yes Figure 3 Schematic diagram of the center line of the weld.

[0050] Figure 5 Figure 3 Schematic diagram of the grinding groove.

[0051] Figure 6 yes Figure 3 Schematic diagram showing welding direction and welding gun angle.

[0052] Figure 7 yes Figure 6 Schematic diagram showing rapid cooling after welding is completed.

[0053] In the figure: 1. Ferritic stainless steel curved side plate; 2. Weld; 3. Depressed area; 4. Upper side beam; 5. Lower side beam; 6. Side funnel plate; 7. Wheel; 8. Bogie; 9. End plate; 10. Support rod; 11. Weld reserved part; 12. Weld flat part; 13. Steel plate ruler; 14. Center line; 15. Groove; 16. Magnetic tile; 17. Welding gun; 18. Bottled water; 19. Partition. DETAILED DESCRIPTION

[0054] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0057] The present invention provides a method for repairing welding thermal stress deformation of arc-shaped side panels of railway freight cars, such as Figure 1 As shown, the body of the railway freight hopper car mainly includes ferritic stainless steel arc-shaped side plates 1 located on both sides of the car body, the upper ends of the arc-shaped side plates are welded with upper side beams 4, and the lower ends are welded with lower side beams 5; 4mm thick end plates 9 are welded and installed at the front and rear ends of the car body; a side hopper plate 6 is welded and installed at the lower end of the lower side beam; a bogie 8 is respectively provided at the front and rear ends of the side hopper plate and connected to the bottom of the lower side beam; each bogie is equipped with four wheels 7, and the four wheels are connected to the lower end of the bogie through an axle in a group of two.

[0058] In order to enhance the overall strength of the vehicle body, a plurality of partitions 19 are arranged inside the vehicle body, and the two ends of the partitions are respectively welded to the arc-shaped side plates. During the welding operation, due to the thermal stress generated by welding, a local concave area 3 will be generated in the middle of the ferritic stainless steel arc-shaped side plate.

[0059] The repair method for the sunken area adopted by the present invention is divided into four stages, which are described as follows:

[0060] Phase 1, support and sanding.

[0061] S1. Align the concave area between the two ferritic stainless steel arc-shaped side plates, and use 3-5 rod-shaped support bodies 10 to horizontally support the concave area to achieve the original curvature of the arc-shaped side plates (see Figure 2 ), in this process, there is no need to use a turning machine to roll the vehicle body.

[0062] S2, grinding the outer side of the weld 2 raised by the support body with an angle grinder to make the weld flat, thereby forming a weld flattened portion 12 (see Figure 3 ); During grinding, a weld reserved portion 11 with a length of L1, L1≈300 mm is left on the upper and lower sides of the weld flattened portion, close to the upper beam and the lower beam, and the weld reserved portion is not ground to facilitate the joint processing after the weld repair in the later stage.

[0063] The second stage, scribing and cutting.

[0064] S3. Use a longer steel ruler 13 to align the center of the flattened weld and draw a center line 14 (see Figure 4 ).

[0065] S4, using an electric angle grinder equipped with a 2.5 mm thick slice, cut a groove 15 with a depth of H, H≈1.5 mm and a width of B, B≈3 mm along the center line (see Figure 5 ).

[0066] As a preferred embodiment, after cutting, a magnetic tile 16 is pasted on both sides of the groove, and the distance between the magnetic tile and the edge of the groove is L2, L2≈30mm. The purpose is to prevent metal splashes during welding from contaminating the surface of the curved side panel, thereby affecting the appearance quality of the entire vehicle.

[0067] The third stage is welding.

[0068] S5. Use metal arc CO2 gas shielded welding (GMAW) to weld the worn weld from top to bottom along the groove (see Figure 6 ), the heat generated by the welding arc heats the weld in the concave area and releases stress. The height and width of the weld are required to be basically consistent with the original weld. The welding parameters are shown in Table 1.

[0069] Table 1

[0070]

[0071] As a preferred embodiment, in order to make the solder fill the weld evenly, during the welding process, the welding gun 17 is ensured to be at 90° to both sides of the weld and at an angle ɑ with the bottom of the weld, ɑ=50°-55°.

[0072] The fourth stage is cooling and removal of the support body.

[0073] S6. When the weld is completed, immediately use bottled water 18 to pour water from top to bottom on the weld and the nearby heat-affected zone (such as Figure 7 As shown in the figure, speed up the cooling of the weld and avoid the weld from generating large restraint stress due to shrinkage during the slow cooling process, which may cause concave deformation again.

[0074] S7. After 15 minutes of rest, the weld and the surrounding area are completely cooled, and the multiple supports placed in the car body can be removed. At this time, the stress has been completely eliminated, and the sunken area caused by stress will not appear again, and the repair is complete. The overall repair process takes about 40 minutes, and the time for repairing the sunken area is only 1 / 6 of the existing technology. The one-time repair success rate is close to 100%, which is nearly 40% higher than the original repair success rate.

[0075] Using this method, three people can complete the work of repairing the sunken area, two of whom are responsible for the disassembly and assembly of the support rod and the smoothing of the weld and grinding of the groove, and the other is responsible for the preparation before welding and welding and watering and cooling the weld after welding.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for repairing welding thermal stress deformation of curved side panels of railway freight cars, characterized in that: The method comprises: S1. Align the concave area between the two curved side plates on both sides of the railway freight car body, and use a plurality of rod-shaped support bodies to laterally support the concave area so that it reaches the original curvature of the curved side plates; S2, grinding the outer side of the weld seam raised by the support body to make the weld seam flat, thereby forming a weld seam grinding flat part; S3. Align the center of the flattened weld and draw a center line; S4, using a cutting tool to cut a groove for welding along the center line; S5, performing welding operation from top to bottom along the groove; S6. After the welding operation is completed, water is poured from top to bottom on the weld and the heat-affected zone to accelerate the cooling speed of the weld, thereby avoiding the restraint stress caused by the slow cooling and shrinkage process of the weld and causing depression again; S7. After the weld and the surrounding area are cooled, remove the plurality of supports placed in the vehicle body.

2. According to claim 1, a method for repairing welding thermal stress deformation of a curved side plate of a railway freight car is characterized by: During the grinding operation, reserved weld portions not to be ground are respectively left on the upper and lower sides of the ground weld portion and near the upper beam and the lower beam.

3. According to claim 2, a method for repairing welding thermal stress deformation of a curved side plate of a railway freight car is characterized by: The length of the weld reserved portion is equal to 300 mm.

4. According to claim 1, a method for repairing welding thermal stress deformation of a curved side plate of a railway freight car is characterized by: Protective stickers are respectively pasted on both sides of the groove to prevent metal splashes from contaminating the surface of the arc-shaped side plate during welding.

5. A method for repairing welding thermal stress deformation of curved side panels of railway freight cars according to claim 4, characterized in that: The material of the arc-shaped side plate is ferritic stainless steel, and the protective sticker is a magnetic sticker that can be magnetically adsorbed on the surface of the arc-shaped side plate.

6. A method for repairing welding thermal stress deformation of curved side panels of railway freight cars according to claim 4, characterized in that: The length of the protective film from the edge of the groove is 30 mm.

7. The method for repairing welding thermal stress deformation of curved side panels of railway freight cars according to claim 1, characterized in that: During welding operations, CO2 gas shielded welding with a consumable electrode is used.

8. The method for repairing welding thermal stress deformation of curved side panels of railway freight cars according to claim 1, characterized in that: During welding, the welding gun angle is 90° on both sides of the weld and the angle with the bottom of the weld is between 50°-55°.

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