Turnout steel rail flash welding method and welding construction method thereof

Abstract

The invention relates to the technical field of turnout steel rail welding, in particular to a turnout steel rail flash welding method and a welding construction method thereof.The turnout steel rail flash welding method comprises the following operation steps that S1, a steel rail to be welded and a connector are prepared; s2, adjusting the position of the turnout rail; s3, aligning a welding machine; s4, welding is conducted; s5, normalizing the welding head; s6, the welding position is polished; s7, recovering the line; wherein the step S6 comprises the following operation steps: S6.1, rough grinding of a welding head; s6.2, flaw detection is conducted on a welding head; according to the turnout steel rail flash welding method and the welding construction method of the turnout steel rail flash welding method, during construction organization, a welding machine can be preferentially arranged to reversely enter a turnout according to site construction requirements, the alignment frequency is reduced, and the auxiliary operation time is shortened; and if forward entry is required due to the limitation of field conditions, a turning path needs to be planned in advance, so that a welding machine can be quickly positioned, the turnout steel rail with a narrow opening can be welded, and the welding precision and the welding quality are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of turnout rail welding, and particularly to a flash welding method for turnout rails and a welding construction method thereof. Background Art

[0002] As a key control point in railway construction, after investigating the welding of the seamless line in the interval and the geometric dimensions of the turnout, the main difficulties and key points of turnout flash welding are as follows: the space for the frog opening is narrow, and the variable cross-section distance of the AT rail is short. Such a complex construction environment not only increases the welding difficulty but also poses higher requirements for welding quality; the consumption of flash welding joints fluctuates greatly, which may cause deviations in the size, shape or position of the welding joints, making it difficult to meet the high-precision installation requirements of turnout components; the steel parts in the turnout area are short, resulting in a cumbersome padding process for welding operations and difficult shunting at the turnout operation site. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to solve the problems that the existing turnout flash welding has a narrow space for the frog opening and a short variable cross-section distance of the AT rail. Such a complex construction environment not only increases the welding difficulty but also poses higher requirements for welding quality. Now, a flash welding method for turnout rails and a welding construction method thereof are provided.

[0004] The technical solution adopted by the present invention to solve its technical problems is: a flash welding method for turnout rails, with the following operating steps:

[0005] S1. Preparation of the rails to be welded and the joints;

[0006] S2. Adjust the position of the turnout rails;

[0007] S3. Align the welding machine;

[0008] S4. Weld;

[0009] S5. Normalize the welded head;

[0010] S6. Grind the welding position;

[0011] S7. Restore the line;

[0012] Among them, step S2 includes, after the replacement of the extended rail parts is completed, checking the misalignment of the rails, the relative position of the switch rail and the stock rail, the squareness of the tip of the switch rail, and the position of the limiter mother and son blocks. When welding the heel end of the switch rail, it is necessary to perform reset and secondary inspection, consider the melting amount, and confirm the sawing value ΔL according to the measured rail temperature;

[0013] ΔL = rail length × locking rail temperature difference Δt × rail expansion coefficient 0.0118.

[0014] Preferably, in some embodiments, step S1 includes the steps:

[0015] S1.1. Before welding, replace the extended rail parts. When welding the straight and curved tracks before the heel end of the switch rail and the frog, the switch rail assembly needs to be disassembled. It is necessary to re-mark the position of the switch rail and place rollers under the rail so that the rail can move longitudinally for welding.

[0016] S1.2. Before welding, it is necessary to check the perpendicularity of the rail end face and the derusting quality of the conductive surfaces of the rail end face and the rail web.

[0017] S1.3. Grind the contact area between the electrode jaws of the flash welding machine on the rail web. Lift the two rail ends to be welded to a certain height for aligning the welding machine and clamping the rail. The lifting height should be determined according to the type of sleeper and fastener.

[0018] In some preferred embodiments, step S2 is specifically as follows: After replacing the extended rail parts, check the misalignment of the stock rail, the relative position between the switch rail and the stock rail, the misalignment of the tip of the switch rail, and the position of the master and slave blocks of the retainer. Tighten the fasteners at the fixed end of the welded joint according to the construction requirements.

[0019] In some preferred embodiments, step S4 includes the following steps:

[0020] S4.1. According to the welding sequence and the dynamic and static ends of the welding head, adjust the alignment of the rail and the welding head by rotating the welding head 180°. After the rail alignment is completed, start the butting work. It should be noted that the working surface must be used as the reference, and the misalignment deviation of the rail head working surface and the misalignment deviation of the rail bottom edge should be noted.

[0021] S4.2. Operate the welding machine to clamp the rail and weld the rail. According to the welding requirements of the welding machine, promptly re-align the welded curved rail. After welding the rail, immediately check the actual welding parameters of the welding machine. For welded joints with actual parameters deviating from the normal range, they should be sawed and re-welded.

[0022] S4.3. When welding fails, it should be sawed and re-welded, but it must be ensured that the welded joint has cooled to room temperature before welding again. The number of re-welding times shall not exceed 2 times. When cutting the welded head, the weld seam should be centered, and the sawing length on both sides shall not exceed 25 - 30 mm. The rail ends should be re-treated to ensure that the perpendicularity of the end face meets the process requirements.

[0023] S4.4. After welding is completed, the welding machine must be quickly lifted to remove the welding bead. The protruding allowance for the rail head, rail bottom, and the slope of the rail bottom top surface of the welded joint should not be greater than 1 mm, and the protruding allowance for other positions should not be greater than 2 mm. The welding slag should not be squeezed into the base metal, and the welding slag should not scratch the base metal. Check the appearance quality of the long rail welded joint and mark the welded joint. The mark should be at the same side rail web position 1 - 3 m in front of the welded joint, and the mark should be clear and regular.

[0024] S4.5. Fill in the "Field Flash Welding Record Sheet" in a timely manner.

[0025] Preferably, in some embodiments, step S5 includes the steps of:

[0026] S5.1. During electro-normalizing, a pyrometer is used to measure the normalizing temperature. The surface temperature of the rail head during heating should be controlled at 900 ± 20°C, and the surface temperature of the rail bottom should be controlled between 800°C and 850°C. The rail head is preferably cooled naturally.

[0027] S5.2. When fixing the normalizing device assembly, its middle position should coincide with the middle of the welding head to ensure the heating width on both sides of the welded joint.

[0028] S5.3. A dedicated person operates the normalizing machine controller. After ensuring correct installation, turn on the switch.

[0029] S5.4. If a low joint is found after welding the rails, straightening treatment should be carried out. Post-weld straightening should be carried out after the heat treatment of the welded joint. The straightening temperature should be lower than 400°C, and an upward camber should be reserved.

[0030] Preferably, in some embodiments, step S6 includes the following operating steps:

[0031] S6.1. Coarse grinding of the welding head.

[0032] S6.2. Inspection of the welding head by flaw detection.

[0033] S6.3. Fine grinding of the welding head.

[0034] Preferably, in some embodiments, step S6.1 includes:

[0035] S6.11. Before the coarse grinding operation, the excess flash allowance should be measured first. According to the excess flash allowance, the non-working surface of the rail, the rail jaw, and the upper surface of the rail bottom corner in the joint area are ground. For the unevenness of the welded joint caused by the deviation of the rail shape and size, a rounding grinding method can be used for trimming.

[0036] S6.12. After the coarse grinding operation is completed, the grinding allowance for the bottom surface and non-working surface of the joint rail should be 0 to +0.5 mm. The grinding range for the upper surface of the rail bottom corner is that the grinding width from the upper surface of the rail bottom corner inward is more than 45 mm, and the longitudinal weld is centered and the grinding width to both sides is more than 85 mm, and it must not be under-ground.

[0037] S6.13. During grinding, the feed rate should be appropriate, and the surface must not be under-ground, and no blackening or bluing should occur.

[0038] S6.14. After coarse grinding, the grinding surface must be smooth and meet the requirements of flaw detection.

[0039] Preferably, in some embodiments, step S6.2 includes:

[0040] S6.21. The instrument used for joint flaw detection is an ultrasonic flaw detector;

[0041] S6.22. When detecting flaws in the welded joint, the grinding surface should be smooth, free of welding slag. The grinding range should meet the requirements of scanning. The temperature of the weld should be cooled below 40°C. The flaw detection operation technology should comply with the requirements of "Ultrasonic Flaw Detection of Rail Welds in Track Maintenance Operations";

[0042] S6.23. For those that fail the flaw detection inspection, they should be cut and rewelded;

[0043] S6.24. After the flaw detection is completed, fill in the "Ultrasonic Flaw Detection Record of On-site Rail Welded Joints" in a timely manner.

[0044] Preferably in some embodiments, wherein step S6.3 includes:

[0045] S6.31. Before grinding, the temperature of the welded joint and the 1m range at both ends should be below 50°C. The straightness in the horizontal and vertical directions within 500mm on both sides of the weld should be measured to determine the appropriate grinding feed rate, and then the rail top surface and the working edge of the rail head side within a 400mm range on both sides of the weld should be profiled and ground;

[0046] S6.32. When grinding, do not apply excessive force to prevent local overheating and blackening or bluing of the rail surface;

[0047] S6.33. Use a profiled grinding machine to finish the profile of the rail top surface and the working edge of the rail head side of the welded joint, and the rail profile shape should be maintained. The profile finishing should not cause any mechanical damage or thermal damage to the welded joint or the rail. Do not use the profile finishing method to correct the excessive straightness deviation and excessive joint misalignment;

[0048] S6.34. The upper fillets of the rail head and rail bottom should be smooth within 1m. The grinding depth of the base metal should not exceed 0.2mm. The rail welded joint should be ground smoothly within 150mm on both sides of the weld on the upper surface of the rail bottom and within 35mm from the edge of both rail bottom corners on both sides. There should be no obvious defects within 100mm on both sides of the weld.

[0049] A turnout rail welding construction method using a turnout rail flash welding method as described above includes the following operating steps:

[0050] A1. The turnout welding sequence is: first weld the connection part welding points, connection part welding points, connection part welding points, connection part welding points, then weld the switch rail welding points, switch rail welding points, stock rail welding points, stock rail welding points. After the turnout front and rear rails are in place, weld the rear rail welding points, rear rail welding points, rear rail welding points, rear rail welding points, and finally weld the stock rail welding points, stock rail welding points;

[0051] A2. When welding the turnout, strictly follow the "static" end and "dynamic" end. For the fasteners removed at the "static" end, it is sufficient if they meet the welding requirements. During welding, there shall be no displacement at the "static" end. All fasteners and connectors at the "dynamic" end shall be removed and rollers shall be padded to ensure a free state. The rail-road vehicle is equipped with a transverse movement mechanism and a support system. The support system jacks up the flash butt welding machine unit for the rail-road turnout to facilitate the rapid switching between the dynamic and static ends during the construction process.

[0052] A3. Replace the extended guide rails between the tip rail welding point and the connecting part welding point, and between the tip rail welding point and the connecting part welding point, and overlap them at the joints of the tip rail welding point and the tip rail welding point to complete the joint welding at the connecting part welding point and the connecting part welding point.

[0053] A4. Replace the extended guide rails between the stock rail welding point and the connecting part welding point, and between the stock rail welding point and the connecting part welding point, and overlap them at the joints of the stock rail welding point and the stock rail welding point to complete the joint welding at the connecting part welding point and the connecting part welding point.

[0054] A5. Move the tip rail forward towards the switch point to ensure the accurate position between the tip rail and the stock rail after welding, and then saw cut the guide rails between the tip rail welding point and the connecting part welding point, and between the tip rail welding point and the connecting part welding point to complete the joint welding at the tip rail welding point and the joint welding at the tip rail welding point.

[0055] A6. Move the stock rail welding point and the rear rail welding point towards the switch end, and move the stock rail welding point and the rear rail welding point towards the switch end to ensure the accurate position between the tip rail and the stock rail after welding and the full length of the turnout. Then saw cut the guide rails between the stock rail welding point and the connecting part welding point, and between the stock rail welding point and the connecting part welding point to complete the joint welding at the stock rail welding point and the joint welding at the stock rail welding point.

[0056] A7. When welding the turnout outer joint, perform "lap welding" or "bending welding" at one end according to the on-site situation. The welding sequence shall be carried out in accordance with the above steps. The head of the turnout flash butt welding machine can be rotated 180° for welding, which is convenient for switching the clamping direction of the rail web and the rail head.

[0057] The beneficial effects of the present invention are as follows: For a switch rail flash welding method and its welding construction method of the present invention, during construction organization, the welding machine can be preferentially arranged to enter the switch in the reverse direction according to the on-site construction requirements, reducing the number of alignment times and shortening the auxiliary operation time; if it is necessary to enter in the forward direction due to on-site conditions, the turning path needs to be planned in advance to ensure the rapid positioning of the welding machine, ensure that the switch rails with a narrow opening can be welded, guarantee the welding accuracy and quality, and avoid the problems existing in the existing switch flash welding, such as the narrow space of the frog opening and the short variable cross-section distance of the AT rail. Such a complex construction environment not only increases the welding difficulty but also poses higher requirements for the welding quality. Brief Description of the Drawings

[0058] The present invention will be further described below with reference to the drawings and embodiments.

[0059] Figure 1 It is the construction process flow chart in Embodiment 1 of the present invention;

[0060] Figure 2 It is the structural schematic diagram of the switch to be welded in Embodiment 2 of the present invention.

[0061] In the figure: 1. Basic rail welding point, 2. Basic rail welding point, 3. Basic rail welding point, 4. Switch rail welding point, 5. Switch rail welding point, 6. Connection part welding point, 7. Connection part welding point, 8. Connection part welding point, 9. Connection part welding point, 10. Connection part welding point, 11. Rear rail welding point, 12. Rear rail welding point, 13. Rear rail welding point, 14. Rear rail welding point. Detailed Embodiments

[0062] The present invention will be further described in detail below with reference to embodiments:

[0063] The present invention is not limited to the following specific embodiments. Those of ordinary skill in the art can implement the present invention in other various specific embodiments according to the content disclosed in the present invention, or those that adopt the design structure and idea of the present invention and make simple changes or modifications all fall within the protection scope of the present invention. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0064] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0065] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0066] Example 1

[0067] As Figure 1 shown, a flash welding method for turnout rails is characterized by the following operating steps:

[0068] S1. Preparation of the rails to be welded and the joints;

[0069] S1.1. Before welding, replace the extended rail parts. When welding the straight and curved tracks at the heel of the switch rail and in front of the frog center, it is also necessary to disassemble the switch rail assembly, re-mark the position of the switch rail, and place rollers under the rail so that the rail can move longitudinally for welding;

[0070] S1.2. Before welding, it is necessary to check the perpendicularity of the rail end faces and the rust removal quality of the rail end faces and the conductive surfaces of the rail waists;

[0071] S1.3. Grind the contact area of the electrode jaws of the flash welding machine on the rail waist, lift the two rail ends to a certain height for the welding machine to align and clamp the rails, and the lifting height should be determined according to the types of sleepers and fasteners.

[0072] S2. Adjust the position of the switch rail. After the replacement of the rail section is completed, check the misalignment of the stock rail, the relative position between the switch rail and the stock rail, the misalignment at the tip of the switch rail, and the position of the male and female blocks of the retainer. Tighten the fasteners at the fixed end of the welded joint as required during construction. When welding the heel end of the switch rail, it is necessary to reset and conduct a secondary inspection. Considering the melting amount, confirm the sawing value ΔL based on the measured rail temperature;

[0073] ΔL = rail length × temperature difference of the locking rail temperature Δt × coefficient of thermal expansion of the rail 0.0118.

[0074] S3. Align the welding machine. For rail welding, first align the rail welding machine. The vehicle commander gives the order to direct. The distance from the first wheel pair of the flatbed truck carrying the turnout rail welding machine to the welding center line is about 3.5 m;

[0075] S4. Welding;

[0076] S4.1. According to the welding sequence and the dynamic and static ends of the weld head, rotate the welding head by 180° to adjust the alignment of the rail and the welding head. After the rail alignment is completed, start the butting work. It should be noted that the working surface must be used as the reference, and the misalignment deviation of the rail head working surface and the misalignment deviation of the rail bottom edge;

[0077] S4.2. Operate the welding machine to clamp the rail and weld. According to the welding requirements of the welding machine, timely re-align the rail of the curved track that has been shifted. After welding the rail, immediately check the actual welding parameters of the welding machine. For the welded joint where the actual parameters deviate from the normal range, it should be sawed and re-welded;

[0078] S4.3. When the welding fails, it should be sawed and re-welded, but it must be ensured that the welded joint has cooled to room temperature before welding again. The number of re-welding times shall not exceed 2 times. When cutting the weld head, the weld seam should be centered, and the sawing length on both sides shall not exceed 25 - 30 mm. And the ends of the rail should be re-treated to ensure that the end face perpendicularity meets the process requirements;

[0079] S4.4. After welding is completed, the welding machine must be quickly lifted to remove the weld bead. The pushing convex allowance for the rail head, rail bottom, and the slope of the top surface of the rail bottom of the welded joint should not be greater than 1 mm, and the pushing convex allowance for other positions should not be greater than 2 mm. The weld slag should not be squeezed into the base metal, and the weld slag should not scratch the base metal. Check the appearance quality of the long rail welded joint and mark the welded joint. The mark should be at the same side of the rail waist 1 - 3 m in front of the welded joint, and the mark should be clear and upright;

[0080] S4.5. Fill in the "Field Flash Welding Record Form" in a timely manner.

[0081] S5. Normalizing the weld head;

[0082] S5.1. During electric normalizing, a pyrometer is used to measure the normalizing temperature. The surface temperature of the rail head during heating should be controlled at 900 ± 20°C, and the surface temperature of the rail bottom should be controlled between 800°C and 850°C. Natural cooling is preferred for the rail head during cooling.

[0083] S5.2. When fixing the normalizing device assembly, its middle position should coincide with the middle of the welding head to ensure the heating width on both sides of the welded joint.

[0084] S5.3. A dedicated person operates the normalizing machine controller. After ensuring correct installation, turn on the switch.

[0085] S5.4. If a low joint is found after rail welding, straightening treatment should be carried out. Post-weld straightening should be performed after the heat treatment of the welded joint. The straightening temperature should be lower than 400°C, and an upward camber should be reserved.

[0086] S6. Grind the welded position.

[0087] S6.1. Rough grinding of the welding head.

[0088] S6.11. Before rough grinding operation, the excess flash allowance should be measured first. According to the excess flash allowance, the non-working surface of the rail, the rail jaw, and the upper surface of the rail bottom corner in the joint area are ground. For the unevenness of the welded joint caused by the deviation of the rail shape and size, it can be trimmed by a rounding grinding method.

[0089] S6.12. After the rough grinding operation is completed, the grinding allowance for the bottom surface and non-working surface of the joint rail should be 0 to +0.5 mm. The grinding range for the upper surface of the rail bottom corner is that the grinding width is more than 45 mm inward from the upper surface of the rail bottom corner, and the longitudinal weld is centered and the grinding width is more than 85 mm on both sides, and it must not be under-ground.

[0090] S6.13. During grinding, the feed rate should be appropriate, the surface must not be under-ground, and there should be no blackening or bluing phenomena.

[0091] S6.14. After rough grinding, the grinding surface must be smooth and even, meeting the flaw detection requirements.

[0092] S6.2. Flaw detection of the welding head.

[0093] S6.21. The instrument used for joint flaw detection inspection is an ultrasonic flaw detector.

[0094] S6.22. During flaw detection of the welding head, the grinding surface should be smooth, free of welding slag, and the grinding range should meet the needs of scanning. The weld temperature should be cooled below 40°C, and the flaw detection operation technology should meet the requirements of "Ultrasonic Flaw Detection of Rail Welds in Track Maintenance Operations".

[0095] S6.23. For those that fail the flaw detection inspection, they should be cut and re-welded.

[0096] S6.24. After flaw detection is completed, fill in the "Ultrasonic Flaw Detection Record of Welded Rail Joints on Site" in a timely manner.

[0097] S6.3. Finish the fine grinding of the weld head.

[0098] S6.31. Before grinding, the temperature within the welded joint and the 1m range at both ends should be below 50°C. Measure the flatness in the horizontal and vertical directions within 500mm on both sides of the weld seam to determine the appropriate grinding feed rate, and then perform profiling grinding on the rail top surface and the working edge of the rail head side within the 400mm range on both sides of the weld seam.

[0099] S6.32. Do not apply excessive force during grinding to prevent local overheating and blackening or bluing of the rail surface.

[0100] S6.33. Use a profiling grinding machine to perform profile finishing on the rail top surface and the working edge of the rail head side of the welded joint, and maintain the rail profile shape. Profile finishing should not cause any mechanical damage or thermal damage to the welded joint or the rail. Do not use the profile finishing method to correct the excessive flatness deviation and excessive joint misalignment.

[0101] S6.34. The upper fillets of the rail head and rail bottom should be smooth within 1m. The grinding depth of the base metal should not exceed 0.2mm. The rail surface on both sides of the weld seam within 150mm on the upper surface of the rail bottom of the rail weld head and within the range of 35mm from the edge of both rail bottom corners on both sides should be ground smoothly. There should be no obvious defects within 100mm on both sides of the weld seam. The defects include indentations, impact marks, scratches, etc.

[0102] S7. Restore the line.

[0103] Example 2

[0104] Example 2 uses the welding method of Example 1, specifically as follows: As Figure 2 shown, a turnout rail welding construction method using a turnout rail flash welding method as described above includes the following operation steps:

[0105] A1. The turnout welding sequence is: first weld the connection part welding points 8, connection part welding points 9, connection part welding points 7, and connection part welding points 10. Secondly, weld the switch rail welding points 4, switch rail welding points 5, stock rail welding points 3, and stock rail welding points 6. After the turnout front and rear rails are in place, weld the rear rail welding points 11, rear rail welding points 14, rear rail welding points 12, and rear rail welding points 13. Finally, weld the stock rail welding points 1 and stock rail welding points 2.

[0106] A2. When welding the turnout, strictly follow the "static" end and "dynamic" end. For the "static" end, the removed fasteners only need to meet the welding requirements. During welding, there should be no displacement at the "static" end. All fasteners and connectors at the "dynamic" end are removed and rollers are padded to ensure a free state. The rail-road vehicle is equipped with a transverse movement mechanism and a support system. The support system jacks up the flash welding machine unit for the rail-road turnout, facilitating the quick switching between the dynamic and static ends during the construction process, and solving the problem of frequent turning around of the flash welding machine unit for the rail-road turnout.

[0107] A3. Replace the extended guide rails between the switch rail welding point 4 and the connecting part welding point 8, and between the switch rail welding point 5 and the connecting part welding point 9, and overlap at the joints of the switch rail welding point 4 and the switch rail welding point 5 to complete the joint welding at the connecting part welding point 8 and the connecting part welding point 9.

[0108] A4. Replace the extended guide rails between the stock rail welding point 3 and the connecting part welding point 7, and between the stock rail welding point 6 and the connecting part welding point 10, and overlap at the joints of the stock rail welding point 3 and the stock rail welding point 6 to complete the joint welding at the connecting part welding point 7 and the connecting part welding point 10.

[0109] A5. Move the switch rail forward towards the turnout nose to ensure the accurate position between the switch rail and the stock rail after welding, and then saw the guide rails between the switch rail welding point 4 and the connecting part welding point 8, and between the switch rail welding point 5 and the connecting part welding point 9 to complete the joint welding at the switch rail welding point 4 and the joint welding at the switch rail welding point 5.

[0110] A6. Move the stock rail welding point 3 and the rear rail welding point 11 towards the turnout tail, and move the stock rail welding point 6 and the rear rail welding point 14 towards the turnout tail to ensure the accurate position between the switch rail and the stock rail after welding and the full length of the turnout, and then saw the guide rails between the stock rail welding point 3 and the connecting part welding point 7, and between the stock rail welding point 6 and the connecting part welding point 10 to complete the joint welding at the stock rail welding point 3 and the joint welding at the stock rail welding point 6.

[0111] A7. When welding the outside joints of the turnout, perform "lap welding" or "bending welding" at one end according to the on-site situation, and execute the welding sequence in accordance with the above steps. The welding head of the turnout flash welding machine can be rotated 180° for welding, facilitating the switching of the clamping directions of the rail web and the rail head.

[0112] When the above turnout rail flash welding method and its welding construction method are used, by first welding the welding points of the middle turnout part, that is, welding in the order from the middle to both sides, the deviations in size, shape or position of the joints at each welding point are small, meeting the high-precision installation requirements of the turnout rods, ensuring the orderly welding operation in the turnout area, and improving the welding efficiency.

[0113] Based on the inspiration of the ideal embodiments of the present invention described above, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A flash welding method for turnout rails, characterized in that, The following operating steps: S1. Prepare the rail to be welded and the joint; S2. Adjust the position of the turnout rail; S3. Align the welding machine; S4. Weld; S5. Normalize the weld head; S6. Grind the welding position; S7. Restore the line; Among them, step S2 includes that after the replacement of the extended rail parts is completed, check the misalignment of the rails, the relative position of the switch rail and the stock rail, the squareness of the tip of the switch rail, and the position of the male and female blocks of the retainer. When welding the heel end of the switch rail, it is necessary to perform reset and secondary inspection, consider the melting amount, and confirm the sawing value ΔL according to the measured rail temperature; ΔL = rail length × locking rail temperature difference Δt × rail expansion coefficient 0.0118.

2. The flash welding method for turnout rails according to claim 1, characterized in that, Among them, step S1 includes the following steps: S1.

1. Before welding, replace the extended rail parts. When welding the heel end of the switch rail and the straight and curved rails in front of the frog heart, it is also necessary to disassemble the switch rail assembly, re-mark the position of the switch rail, and place rollers under the rail so that the rail can move longitudinally for welding; S1.

2. Before welding, it is necessary to check the perpendicularity of the rail end face and the rust removal quality of the conductive surfaces of the rail end face and the rail web; S1.

3. Grind the contact area between the electrode jaws of the flash welding machine and the rail web of the rail waist, lift the two rail ends to be welded to a certain height for aligning and clamping the rail by the welding machine. The lifting height should be determined according to the type of sleeper and fastener; 3. A switch rail flash welding method according to claim 1, characterized in that, Among them, step S2 is specifically: after the replacement of the extended rail parts is completed, check the misalignment of the stock rail, the relative position of the switch rail and the stock rail, the misalignment of the tip of the switch rail, and the position of the male and female blocks of the retainer. Tighten the fasteners at the fixed end of the welding joint according to the construction requirements; 4. A turnout rail flash welding method according to claim 1, characterized in that, Among them, step S4 includes the following steps: S4.

1. According to the welding sequence and the dynamic and static ends of the weld head, adjust the alignment of the rail and the welding head by rotating the welding head 180°. After the rail alignment is completed, start the butting work. It should be noted that the working surface must be used as the reference, and the misalignment deviation of the rail head working surface and the misalignment deviation of the rail bottom edge; S4.

2. Operate the welding machine to clamp the rail and weld the rail. According to the welding requirements of the welding machine, timely re-align the welded curve rail. After welding the rail, immediately check the actual welding parameters of the welding machine. For the welding joint with the actual parameters deviating from the normal range, it should be sawed and re-welded; S4.

3. When the welding fails, it should be sawed and re-welded, but it must be ensured that the welding joint has cooled to room temperature before welding again. The number of re-welding times shall not exceed 2 times. When cutting the weld head, the weld seam should be centered, and the sawing length on both sides should not exceed 25 - 30 mm. The rail ends should be re-treated to ensure that the perpendicularity of the end face meets the process requirements; S4.

4. After welding is completed, the welding machine must be quickly lifted to remove the weld bead. The protruding allowance of the weld head on the rail head, rail bottom, and the slope of the rail bottom top surface should not be greater than 1 mm, and the protruding allowance at other positions should not be greater than 2 mm. The weld slag should not be squeezed into the base metal, and the weld slag should not scratch the base metal. Check the appearance quality of the long rail welding joint and mark the welding joint. The mark should be at the same side rail web position 1 - 3 m in front of the welding joint, and the mark should be clear and regular; S4.

5. Fill in the "Field Flash Welding Record Table" in a timely manner.

5. A method for flash welding turnout rails according to claim 1, characterized in that Among them, step S5 includes the following steps: S5.

1. During electric normalizing, use a temperature measuring instrument to measure the normalizing temperature. The surface temperature of the rail head during heating should be controlled at 900 ± 20 °C, and the surface temperature of the rail bottom foot should be controlled at 800 °C - 850 °C. The rail head is preferably cooled by natural cooling; S5.

2. When fixing the normalizing fire component, its middle position should coincide with the middle of the welding head to ensure the heating width on both sides of the welded joint. S5.

3. Have a dedicated person operate the normalizing machine controller. After ensuring correct installation, turn on the switch. S5.

4. If a low joint is found after welding the rail, straightening treatment should be carried out. Post-welding straightening should be carried out after heat treatment of the welded joint. The straightening temperature should be lower than 400 °C, and an upward camber should be reserved.

6. A method for flash welding turnout rails according to claim 1, characterized in that, Among them, step S6 includes the following operating steps: S6.

1. Coarse grinding of the welding head. S6.

2. Inspection of the welding head by flaw detection. S6.

3. Fine grinding of the welding head.

7. A turnout rail flash welding method according to claim 6, characterized in that, Among them, step S6.1 includes: S6.

11. Before the coarse grinding operation, the flash allowance should be measured first. According to the flash allowance, the non-working surface of the rail, the rail jaw, and the upper surface of the rail bottom corner in the joint area should be ground. For the unevenness of the welded joint caused by the deviation of the rail shape and size, the rounding grinding method can be used for trimming. S6.

12. After the coarse grinding operation is completed, the grinding allowance for the bottom surface and non-working surface of the joint rail should be 0 to +0.5 mm. The grinding range for the upper surface of the rail bottom corner is that the inward grinding width from the upper surface of the rail bottom corner is more than 45 mm, and the longitudinal weld is centered and the grinding width to both sides is more than 85 mm, and it must not be undercut. S6.

13. During grinding, the feed rate should be appropriate, the surface must not be undercut, and there must be no blackening and bluing phenomena. S6.

14. After coarse grinding, the grinding surface must be smooth and flat, meeting the flaw detection requirements.

8. A turnout rail flash welding method according to claim 7, characterized in that, Among them, step S6.2 includes: S6.

21. The instrument used for joint flaw detection inspection is an ultrasonic flaw detector. S6.

22. When inspecting the welding head by flaw detection, the grinding surface should be smooth, free of welding slag, the grinding range should meet the needs of scanning, the weld temperature should be cooled to below 40 °C, and the flaw detection operation technology should meet the requirements of "Ultrasonic Flaw Detection of Rail Welds in Track Maintenance Operations". S6.

23. For those that fail the flaw detection inspection, they should be cut and re-welded. S6.

24. After flaw detection is completed, fill in the "Ultrasonic Flaw Detection Record of On-site Rail Welded Joints" in a timely manner.

9. A turnout rail flash welding method according to claim 8, characterized in that, Among them, step S6.3 includes: S6.

31. Before grinding, the temperature within the welded joint and within 1 m on both ends should be below 50 °C. The flatness in the horizontal and vertical directions within 500 mm on both sides of the weld should be measured to determine the appropriate grinding feed rate, and then the top surface of the rail and the working edge of the side of the rail head within 400 mm on both sides of the weld should be profiled and ground. S6.

32. When grinding, do not apply excessive force to prevent local overheating and blackening / bluing of the rail surface. S6.

33. Use a profiled grinding machine to perform profile finishing on the top surface of the welded joint and the working edge of the side of the rail head, and the rail profile shape should be maintained. Profile finishing should not cause any mechanical damage or thermal damage to the welded joint or the rail, and the method of profile finishing should not be used to correct the excessive flatness deviation and excessive joint misalignment. S6.

34. The upper fillets of the rail head and rail bottom should be round and smooth within 1 m. The grinding depth of the base metal should not exceed 0.2 mm. The rail bottom surface of the rail welding head within 150 mm on both sides of the weld and within 35 mm from the edge of both rail bottom corners should be ground flat, and there should be no obvious defects within 100 mm on both sides of the weld.

10. A turnout rail welding construction method using a turnout rail flash welding method according to any one of claims 1-9, characterized in that, It includes the following operating steps: A1. The turnout welding sequence is as follows: First, weld the connection part welding points (8), (9), (7), and (10). Secondly, weld the switch rail welding points (4), (5), the stock rail welding points (3), and (6). After the front and rear rails of the turnout are in place, weld the rear rail welding points (11), (14), (12), and (13). Finally, weld the stock rail welding points (1) and (2). A2. When welding the turnout, strictly follow the "static" end and "dynamic" end. For the "static" end, the removed fasteners only need to meet the welding requirements, and there should be no displacement at the "static" end during welding. For the "dynamic" end, all fasteners and connectors are removed and rollers are padded to ensure a free state. The rail - vehicle has a lateral movement mechanism and a support system. The support system jacks up the flash - butt welding machine unit for the rail - vehicle and turnout, facilitating the quick switching between the dynamic and static ends during construction. A3. Replace the extended guide rails between the switch rail welding point (4) and the connection part welding point (8), and between the switch rail welding point (5) and the connection part welding point (9), and overlap at the joints of the switch rail welding point (4) and the switch rail welding point (5) to complete the joint welding at the connection part welding points (8) and (9). A4. Replace the extended guide rails between the stock rail welding point (3) and the connection part welding point (7), and between the stock rail welding point (6) and the connection part welding point (10), and overlap at the joints of the stock rail welding point (3) and the stock rail welding point (6) to complete the joint welding at the connection part welding points (7) and (10). A5. Move the switch rail forward towards the turnout nose to ensure the accurate position between the switch rail and the stock rail after welding, and then saw - cut the guide rails between the switch rail welding point (4) and the connection part welding point (8), and between the switch rail welding point (5) and the connection part welding point (9) to complete the joint welding of the switch rail welding point (4) and the switch rail welding point (5). A6. Move the stock rail welding point (3) and the rear rail welding point (11) towards the turnout tail, and move the stock rail welding point (6) and the rear rail welding point (14) towards the turnout tail to ensure the accurate position between the switch rail and the stock rail after welding and the full length of the turnout, and then saw - cut the guide rails between the stock rail welding point (3) and the connection part welding point (7), and between the stock rail welding point (6) and the connection part welding point (10) to complete the joint welding of the stock rail welding point (3) and the stock rail welding point (6). A7. When welding the turnout outer joint, perform "butt welding" or "bending welding" at one end according to the on - site situation, and execute the welding sequence in accordance with the above steps. The head of the turnout flash - butt welding machine can rotate 180° for welding.

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