Locomotive coupler crack welding repair method

Abstract

The invention relates to the technical field of welding, in particular to a locomotive coupler crack welding repair method which comprises the following steps: S1, selecting a corresponding welding material according to a coupler material; s2, marking the position of a coupler crack, and determining the type of the coupler crack according to the crack depth; s3, determining a corresponding groove type according to the crack type and the crack position of the car coupler, and machining a groove; s4, a single-face through groove is welded firstly, then a double-face through groove is welded, then a deep non-through groove is welded, and finally a superficial non-through groove is welded; s5, the welding stress is released; s6, postweld heat treatment; and S7, flaw detection after cooling to room temperature for 24 hours. According to different crack states of the car coupler, a reasonable welding groove and a reasonable welding sequence are designed, through preheating and postweld heat treatment, welding stress is reduced, welding cracks are avoided, the car coupler crack welding repair efficiency is high, and the repair effect is good; and the quality is qualified through flaw detection after welding.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding technology, in particular to a locomotive coupler crack welding repair method. BACKGROUND

[0002] In the locomotive traction, the intermeshing between the couplers is used to realize the locomotive hitch traction, and the coupler is a safety component of the locomotive. If a fault occurs, it will at least affect the train operation efficiency, and in serious cases, it may cause train derailment, collision and other accidents, threatening the safety of train operation. During the locomotive hitch traction, the coupler is subjected to cyclic impact load, which often causes cracks in the coupler. The traditional repair method is direct repair welding or welding repair after grinding and removing the cracks. Since the material of the coupler is ZG25MnCrNi-Mo, the carbon equivalent is about 0.6%, and the weldability is poor. After welding repair, delayed cracks or crack area expansion often occur, which brings great distress to the welders, and multiple repairs are still unqualified. At the same time, multiple welding repairs bring high weld heat input and increased stress concentration. Finally, the coupler has to be replaced to meet the locomotive repair requirements, greatly increasing the repair cost and repair cycle. In order to solve the above technical problems, a coupler welding repair process method is designed. SUMMARY

[0003] In view of the problems pointed out in the background art, the present application aims to provide a locomotive coupler crack welding repair method to ensure that the quality of the coupler after welding repair meets the requirements, avoids welding cracks, and meets the coupler assembly and application process requirements.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: A locomotive coupler crack welding repair method, comprising the following steps: S1. Selecting a suitable welding material according to the coupler material; S2. Marking the coupler crack position and determining the coupler crack type according to the crack depth; the crack type includes through crack, superficial non-through crack and deep non-through crack; S3. Determining the corresponding groove type according to the coupler crack type and crack position, and processing the groove; the groove type includes superficial non-through groove, deep non-through groove, single-sided through groove and double-sided through groove; the superficial non-through groove corresponds to the superficial non-through crack, the deep non-through groove corresponds to the deep non-through crack, the single-sided through groove corresponds to the through crack in the non-open area of the coupler body, and the double-sided through groove corresponds to the through crack in the open area of the coupler body; S4. Select the corresponding welding path according to the groove type, and weld in the following order: first, weld the single-sided through groove, then weld the double-sided through groove, next weld the deep non-through groove, and finally weld the shallow non-through groove; the interpass temperature of each groove needs to be preheated to 300-350℃ before welding, and the electrode is baked at 300-350℃ for 1-2h and placed in the electrode storage barrel so that the temperature of the electrode before use is 100-150℃; S5. After welding, hammer the weld and the two sides of the weld to release the welding stress. S6. Post-weld heat treatment to eliminate internal stress in the weld. S7. After cooling to room temperature for 24 hours, perform flaw detection, and polish the weld after the flaw detection is qualified.

[0005] In the step S1, the material of the coupler is ZG25MnCrNi-Mo, and the corresponding selected welding material is J857CrNi alkaline flux high-strength steel electrode.

[0006] In the step S2, the shallow non-through crack and the deep non-through crack are divided according to the following method: use a polishing device to polish the crack until the crack disappears, and the polishing depth is the crack depth; when the crack depth is within 3mm, it is a shallow non-through crack, and when the crack depth is greater than 3mm, it is a deep non-through crack.

[0007] In the step S3, the included angle of the two sides of the shallow non-through groove, the deep non-through groove, the single-sided through groove and the double-sided through groove is not less than 20°, the included angle of the single-sided slope with the horizontal is not more than 80°, the width of the groove bottom is not less than 6mm, the depth of the shallow non-through groove is within 3mm, and the depth of the deep non-through groove is greater than 3mm.

[0008] In the step S4, before welding each groove, the following method is used for preheating: using oxyacetylene flame welding to heat the groove and the surrounding 100mm within the groove to 300-350℃, and using an infrared temperature gun to detect the temperature during the heating process.

[0009] In the step S4, the shallow non-through groove is welded with a single layer, and the electrode selected is φ3.2mm; the deep non-through groove, the single-sided through groove and the double-sided through groove are all welded with multiple layers and multiple passes, the first layer of weld is selected with φ2.5mm or smaller electrode, the welding current is 70-90A, the remaining welds are welded with φ3.2mm electrode, and the welding current is 90-120A.

[0010] When multiple layers and multiple passes are used, after each layer of weld is completed, the method of hammering the weld is used to release the stress before starting the next layer of weld.

[0011] In the step S4, the same type of groove is welded in the following sequence: according to the groove depth, the deep groove is welded first, and then the shallow groove is welded; according to the groove length, the long groove is welded first, and then the short groove is welded.

[0012] In the step S6, the specific method of post-weld heat treatment is as follows: the weld and the peripheral area of the weld are heated to 600-650 DEG C tempering treatment by using oxygen acetylene flame, and the peripheral area of the weld is the area within 100 mm around the weld.

[0013] The present application has the following advantages: according to the different crack states of the coupler, the present application designs a more reasonable welding groove and welding sequence, reduces the welding stress through preheating and post-weld heat treatment, avoids the occurrence of welding cracks, and makes the coupler crack welding repair efficiency high and the repair effect good; after welding, the quality is qualified through flaw detection inspection. The present application also provides a better process method for welding repair of similar cast steel parts. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The flowchart of the present application.

[0015] Figure 2 The schematic diagram of the shallow non-penetrating groove.

[0016] Figure 3 The schematic diagram of the deep non-penetrating groove.

[0017] Figure 4 The schematic diagram of the single-sided penetrating groove.

[0018] Figure 5 The schematic diagram of the double-sided penetrating groove.

[0019] Figure 6 The welding sequence top view of parallel welding.

[0020] Figure 7 The welding sequence section view of parallel welding.

[0021] Figure 8 The welding sequence top view of spiral welding.

[0022] Figure 9 The welding sequence section view of spiral welding.

[0023] Figure 10 The curved surface area of the inner side of the coupler hook body.

[0024] In the figure: D is the groove bottom width, d is the groove opening width, alpha is the included angle of the single-sided slope with the horizontal, beta is the included angle of the two sides of the groove, B is the groove bottom distance of the double-sided penetrating groove, and h is the crack depth. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are described in further detail below with reference to the accompanying drawings and examples. Example 1

[0026] Crack repair of locomotive coupler 100E steel

[0027] As shown in Figure 1 , the locomotive coupler crack welding repair method provided by the present application in Example 1 includes the following steps: S1. Welding material preparation; select appropriate welding materials according to the coupler material; in Example 1, the material of the 100E steel coupler is ZG25MnCrNi-Mo, and J857CrNi alkaline flux high-strength steel electrode with a diameter of φ2.5 (for backing) and φ3.2 (for facing) is selected; S2. Mark the position of the coupler crack, and determine the type of the coupler crack according to the crack depth; the crack type is divided into through cracks, superficial non-through cracks and deep non-through cracks; the crack depth is determined by the following method: use a grinding wheel or a rotary file to polish the defect site to remove the crack, and when the crack is removed, the depth of the removed site is the crack depth; S3. Determine the corresponding groove type according to the type and position of the coupler crack, and process the groove; the groove type includes superficial non-through groove, deep non-through groove, single-sided through groove and double-sided through groove; the superficial non-through groove corresponds to the superficial non-through crack, the deep non-through groove corresponds to the deep non-through crack, the single-sided through groove corresponds to the through crack in the non-open area of the coupler body, and the double-sided through groove corresponds to the through crack in the open area of the coupler body; specifically, as shown in Figure 10 , the non-open area of the coupler body refers to the curved surface area (the two lead lines corresponding to the letter M in the figure indicate the range of the curved surface area) on the inner side of the coupler body, and the remaining area is the open area of the coupler body; In Example 1, the groove processing can be implemented after the crack depth is determined, and a mechanical method is still used, that is, a grinding wheel or a rotary file is used to process the corresponding type of groove according to the crack depth; when the crack depth h is within 3mm, it is a superficial non-through crack, and when the crack depth h is greater than 3mm, it is a deep non-through crack; the shape of the superficial non-through groove is as shown in Figure 2 , the shape of the deep non-through groove is as shown in Figure 3 , the shape of the single-sided through groove is as shown in Figure 4 , and the shape of the double-sided through groove is as shown in Figure 5The angle β of the two side slopes of each type of groove is not less than 20°, the angle α of the single side slope and the horizontal is not more than 80°, the width D of the bottom of the groove is not less than 6mm, and the opening width d of the groove should be not less than 20mm; for the double-sided through groove, the distance B between the two groove bottoms is not less than 3mm, and the groove bottoms are connected by sanding to avoid hidden cracks; when the groove is processed, the metal color of each groove surface should be exposed, the transition between the groove bottom and the side wall should be smooth, and the scale, oil, moisture, rust and other impurities within the range of 20cm around the groove should be removed, and after the defects are eliminated, the magnetic particle inspection can be performed to determine whether the defects are completely eliminated before entering the next step; S4. According to the type of the groove, the corresponding welding path is selected and welded in the following order: the single-sided through groove is welded first, the double-sided through groove is welded second, the deep non-through groove is welded third, and the shallow non-through groove is welded last; the interpass temperature of each groove needs to be preheated to 300-350℃ before welding, and the electrode is baked at 300-350℃ for 1-2h and placed in the electrode storage barrel so that the temperature of the electrode before use is 100-150℃; before welding each groove, the following method is used for preheating: the groove and the area within 100mm around the groove opening are heated to 300-350℃ by using the oxyacetylene flame welding, and then the temperature is detected by using the infrared temperature gun during the heating process, and then the temperature is slowly cooled to the interpass temperature; the welding of embodiment 1 adopts the direct current reverse connection method, the welding position is in the flat welding position, the shallow non-through groove is welded by single-layer welding, and the electrode with a diameter of 3.2mm is selected; the deep non-through groove, the single-sided through groove and the double-sided through groove are all welded by multi-layer and multi-pass welding, the first layer of weld is selected by using the electrode with a diameter of 2.5mm, the welding current is 70-90A, the remaining welds are selected by using the electrode with a diameter of 3.2mm, and the welding current is 90-120A; such a welding method can reduce the weld fusion ratio and prevent the generation of hot cracks; when the multi-layer and multi-pass welding is performed, after each layer of weld is completed, the stress is released by hammering the weld before the next layer of weld is started, and the welding slag is completely removed (if new cracks or other defects are found, they should be removed in time); when welding, in order to prevent the arc from damaging the surface of the casting, the arc should not be introduced on the non-welding surface of the workpiece; The same type of groove is welded in the following order: according to the depth of the groove, the deep groove is welded first, and then the shallow groove is welded; according to the length of the groove, the long groove is welded first, and then the short groove is welded.

[0028] The welding path of the single-layer welding of the shallow non-through groove can be parallel welding or spiral welding; for the deep non-through groove, the single-sided through groove and the double-sided through groove, the welding path is multi-layer and multi-pass welding, and each layer of welding path can be parallel welding or spiral welding; the order of parallel welding and spiral welding is the prior art, the welding order of parallel welding is as shown in Figure 6 、 Figure 7 , and the welding order of spiral welding is as shown in Figure 8 ,Figure 9 When welding, short arc, narrow welding bead welding and small sawtooth type welding gun should be used as much as possible to reduce the line energy and realize small heat input welding. After each layer of welding, the welding slag is removed in time, and the repair welding area is uniformly hammered along the center of the defect outward. It should be noted that the force should not be too strong to avoid causing new cracks. Figure 7 In the figure, the numbers 1-7 represent the sequential numbering of the welds when parallel welding is performed. Figure 9 In the figure, the numbers 1-8 represent the sequential numbering of the welds when spiral welding is performed. S5. After welding, hammer the weld and the two sides of the weld to release the welding stress. In Example 1, a round head hammer or a pneumatic rust remover is used to hammer the weld and the two sides to release the welding stress. S6. Post-weld heat treatment to eliminate internal stress in the weld; in Example 1, the weld and the surrounding area of the weld are heated to 600-650 DEG C tempering treatment using oxyacetylene flame, and the surrounding area of the weld is the area within 100 mm of the weld; after tempering and holding, wrapped with asbestos for slow cooling (if conditions permit, it can be placed in a heating furnace for slow cooling with the furnace); S7. After cooling to room temperature for twenty-four hours, detect by flaw detection, and after the flaw detection is qualified, polish the weld. After polishing, the weld can be detected again to ensure that there is no crack.

[0029] The present application marks the defect position, adopts different forms of welding groove preparation, preheats and knocks before welding, fully releases the original cracks and internal stress of the car coupler, then welds the crack defect according to a certain welding sequence and operation skill, which can effectively avoid the problems of delayed cracks and stress concentration caused by the traditional repair welding method, the design of the welding groove facilitates welding and improves the strength of the weld. After welding, the quality is qualified after flaw detection.

[0030] The part of the present application not described in detail is prior art.

Claims

1. A method of crack weld repair of a locomotive coupler, characterized by: It comprises the following steps: S1. Selecting the appropriate welding material according to the material of the coupler; S2. Marking the location of the coupler crack, and determining the type of coupler crack according to the crack depth; the crack type is divided into through cracks, superficial non-through cracks and deep non-through cracks; S3. Determining the corresponding groove type according to the type of coupler crack and the location of the crack, and processing the groove; the groove type includes superficial non-through groove, deep non-through groove, single-sided through groove and double-sided through groove; the superficial non-through groove corresponds to the superficial non-through crack, the deep non-through groove corresponds to the deep through crack, the single-sided through groove corresponds to the through crack in the non-open area of the coupler body, and the double-sided through groove corresponds to the through crack in the open area of the coupler body; S4. Selecting the corresponding welding path according to the groove type, and welding in the following order: first welding the single-sided through groove, then welding the double-sided through groove, then welding the deep non-through groove, and finally welding the superficial non-through groove; the interlayer temperature of each groove needs to be preheated to 300-350℃ before welding, and the electrode is baked at 300-350℃ for 1-2h and placed in the electrode heat preservation barrel, so that the temperature of the electrode before use is 100-150℃; S5. Hammering the weld and the two sides of the weld after welding to release the welding stress; S6. Post-weld heat treatment to eliminate the internal stress of the weld; S7. After cooling to room temperature for twenty-four hours, perform flaw detection, and polish the weld after the flaw detection is qualified.

2. The method of claim 1, wherein the method further comprises: In step S1, the material of the coupler is ZG25MnCrNi-Mo, and the corresponding selected welding material is J857CrNi alkaline flux high-strength steel electrode.

3. The method for welding repair of locomotive coupler cracks according to claim 1, characterized in that: In step S2, the superficial non-through crack and the deep non-through crack are divided according to the following method: using a polishing device to polish the crack until the crack disappears, and measuring the polishing depth as the crack depth; when the crack depth is within 3mm, it is a superficial non-through crack, and when the crack depth is greater than 3mm, it is a deep non-through crack.

4. The method of claim 1, wherein: In step S3, the included angle of the two side slopes of the superficial non-through groove, the deep non-through groove, the single-sided through groove and the double-sided through groove is not less than 20°, the included angle of the single-sided slope with the horizontal is not more than 80°, the width of the bottom of the groove is not less than 6mm, the depth of the superficial non-through groove is within 3mm, and the depth of the deep non-through groove is greater than 3mm.

5. The method of claim 1, wherein the method further comprises: applying a filler material to the crack; and applying a laser to the filler material to weld the crack. In step S4, before welding each groove, the following method is used for preheating: using oxyacetylene flame welding to heat the groove and the surrounding area within 100mm to 300-350℃, and using an infrared temperature gun to detect the temperature during the heating process.

6. The method of claim 1, wherein: In step S4, the superficial non-through groove is welded with a single layer, and the electrode is selected to be φ3.2mm; the deep non-through groove, the single-sided through groove and the double-sided through groove are all welded with multiple layers and multiple passes, the first layer of weld is selected to be φ2.5mm or smaller, the welding current is 70-90A, the remaining welds use φ3.2mm electrodes, and the welding current is 90-120A.

7. The method of claim 6, wherein the method further comprises: When multiple layers and multiple passes are used, after each layer of weld is completed, the stress is released by hammering the weld before starting the next layer of weld.

8. The method of claim 1, wherein: In the step S4, the same type of groove is welded in the following sequence: according to the groove depth, the deep groove is welded first, and then the shallow groove; according to the groove length, the long groove is welded first, and then the short groove.

9. The method for welding repair of locomotive coupler cracks according to claim 1, characterized in that: In the step S6, the specific method of the post-weld heat treatment is as follows: the weld and the peripheral area of the weld are heated to 600-650 ℃ tempering treatment by using oxygen-acetylene flame, and the peripheral area of the weld is within 100 mm of the peripheral area of the weld.

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