Steel rail welding method based on hydrogen-oxygen mixed gas combustion heating

Abstract

The invention discloses a steel rail welding method based on hydrogen and oxygen mixed gas combustion heating. The steel rail welding method comprises a method for providing mixed gas through a gas supply system, a method for heating a steel rail through a composite heating system and a control method. The gas supply system provides mixed gas of hydrogen and oxygen for the composite heating system; the composite heating system comprises a hydrogen-oxygen mixing gun, a composite heater and a swinging device, and the swinging device drives the composite heater to swing back and forth; the control system comprises a method for flexibly adjusting and controlling the flow of hydrogen and oxygen and setting the welding ratio. Through coordination and cooperation of the gas supply system, the composite heating system and the control system, flexible self-adaptive adjustment of all stages is achieved. The system can quickly increase the heating temperature of the to-be-welded steel rail in the initial section, the steel rail can be continuously heated but the surface is not melted through the flexible flow adjusting method, the to-be-welded steel rail can be continuously and stably heated, and the optimal temperature field needed by steel rail air pressure welding is achieved.

Description

Technical Field

[0001] The invention relates to the field of rail welding, and in particular to a rail welding method based on hydrogen-oxygen mixed gas combustion heating. Background Art

[0002] The commonly used rail welding methods in the world are flash welding, gas pressure welding, thermite welding, and narrow gap arc welding. The common methods specified in my country's standards are only flash welding, gas pressure welding, and thermite welding. my country's gas pressure rail welding vehicle is one of the major categories of modern large-scale track maintenance machinery and equipment approved by the National Railway Administration, and has the application advantage of occupying half of the on-site rail welding.

[0003] Rail gas pressure welding uses the heat energy generated by gas fuel to heat the rail ends to a plastic state. The rail atoms have sufficient chemical energy, and the metal atoms on the two rail ends diffuse rapidly across the interface. A certain amount of forging pressure is then applied to form intermolecular metal bonds at both ends, achieving interface reorganization, and finally obtaining a solid rail and completing rail welding.

[0004] Since pneumatic rail welding vehicles currently still use the traditional oxyacetylene mixture to burn chemical energy to heat the rails for welding, gas needs to be consumed continuously during the rail welding operation, which requires frequent loading, unloading and replacement of high-pressure gas cylinders. The labor intensity is high, and the on-site loading and unloading conditions are poor, making manual handling very difficult. In addition, the gas quality in oxygen and acetylene cylinders from gas suppliers across the country varies and is difficult to control, often causing many problems such as sparking and calorific value fluctuations. Because oxygen and acetylene cylinders are both high-pressure dangerous gas cylinders and are subject to national special equipment supervision, there will be certain safety risks when used improperly. These have long been the difficult bottlenecks in the construction of pneumatic rail welding vehicles.

[0005] At present, there is no successful example of hydrogen-oxygen oxygen pressure welding of rails in China. Ryu-ichi YAMAMOTO et al. disclosed a rail welding method using a mixture of hydrogen and ethylene in "Rail Pressure Welding Using Hydrogen and Ethylene Mixed Gas". However, this method not only requires the use of gas cylinders in actual construction, but is also difficult to operate, so the construction practicability is low. Summary of the invention

[0006] In order to solve the problem of low construction practicability in the prior art, a rail welding system based on hydrogen-oxygen mixed gas combustion heating is proposed.

[0007] The embodiment of the present invention is implemented as follows: a rail welding method based on hydrogen-oxygen mixed gas combustion heating, the rail welding method includes a method for a gas supply system to provide a mixed gas, a method for a composite heating system to heat the rail, and a control method; the gas supply system provides a mixed gas of hydrogen and oxygen to the composite heating system; the composite heating system includes a hydrogen-oxygen mixed gun, a composite heater, and a swing device, and the swing device drives the composite heater to swing back and forth; the control system provides a flow control method for controlling the mixed gas, a swing amplitude control method for the swing device, and a swing frequency control method for the swing device; the control system is controlled in three stages: the first stage lasts until the surface temperature of the rail reaches A C1 Phase change temperature, the second stage lasts until the rail surface temperature reaches the upsetting temperature, and the third stage lasts until the welding is completed;

[0008] For the flow control of the mixed gas, the initial flow of the mixed gas is adjusted in the first stage and the initial flow is kept fixed, in the second stage, flexible adjustment is started according to the first flow function, and in the third stage, adjustment is performed according to the second flow function.

[0009] During the heating process, the position of the composite heater changes in a sinusoidal function with time, and the swing amplitude of the composite heater is adjusted according to the swing amplitude function; the composite heating system includes a composite heater, and the composite heater includes a composite heater I and a composite heater II that are used in conjunction and surround the rail to be welded in the middle, and heater I and heater II are respectively provided with fire holes, the number of fire holes for heating the rail head accounts for 37%, the number of fire holes for heating the rail waist accounts for 26%, and the number of fire holes for heating the rail bottom accounts for 37%.

[0010] The inventors of the present invention have discovered that uneven heating of rail welding results in the problem of weld head light spot. The weld head light spot means that the two end faces of the rail are not completely welded together, and the fracture is smooth and grayish white. This not only reduces the effective fracture area of ​​the rail, but also causes serious application concentration, which can easily lead to rail breakage during the service process of the rail and even cause accidents.

[0011] In a preferred embodiment, in the second stage control, the first flow function is L=-k*t+185400, in which the flow L of the second stage mixed gas is L / h, t is time, the unit is second, and the constant k=-3000 to control the smooth heating process of the rail.

[0012] In a preferred embodiment, in the third stage control, the second flow function is L=-a·t2+L0, in which L0 is the mixed gas flow at the end of the second stage; a is the adjustment coefficient, ranging from 0.7 to 1.2; t is time; the hydrogen-oxygen mixed gas flow in the third stage control is L, thereby controlling the smooth heating of the rails.

[0013] In a preferred embodiment, the control system also includes a swinging adjustment method for swing amplitude and swing frequency. The swinging start time is when the surface temperature of the steel rail to be welded reaches A C1 Phase transition temperature.

[0014] In a preferred embodiment, during the heating process, the positions of the composite heater I and the composite heater II change with time in a sinusoidal function, and the functional relationship is y=b·sin(fπt), y is the distance that the heater deviates from the initial heating position, f is the swing frequency, t is the time, b is the swing setting value, b is 5-40, and f is the swing frequency coefficient, and f is 0.1 to 2.

[0015] In a preferred embodiment, the swing amplitude function is D=k d (dT / dt)+b, D is the swing, k d is the swing variation coefficient, k d The value range is 1-4, T is the rail temperature, t is the time, and b is the swing setting value.

[0016] In a preferred embodiment, the control system also includes a temperature sensor for detecting the surface temperature of the rail, a displacement sensor for detecting the swing amplitude of the position composite heater and the position of the rail, and a flow sensor for detecting the air supply system. The control system compares the actual temperature value detected by the temperature sensor, the actual swing amplitude detected by the displacement sensor, the rail position, and the actual flow rate detected by the flow sensor with the corresponding threshold values, and the control system calculates the feedback value based on the measurement values ​​of the corresponding sensors.

[0017] In a preferred embodiment, a gas pipe is disposed inside the composite heater, and a water cooling pipeline and an air cooling pipeline for cooling are also disposed inside the composite heater.

[0018] In a preferred embodiment, in the method for adjusting the swinging fire, the relationship between the position and time of at least one of the heaters I and II is distributed in a specific functional relationship, including a linear function, a parabolic function or a nonlinear function.

[0019] The inventors of the present invention have found that if the hydrogen-oxygen mixed gas of hydrogen-oxygen welding is not burned completely, the welding quality of the steel rail to be welded will be poor.

[0020] In a preferred embodiment, the inert gas is continuously sprayed on the steel rail to be welded to prevent welding defects until the welding is completed. The inventors of the present invention also found that oxides will appear during high-temperature welding. Oxides are impurities that will deteriorate the welding quality of the extruded surface of the steel rail to be welded. Under the protection of inert gas, the generation of oxides on the cross section of the steel rail to be welded is reduced or avoided, thereby improving the welding quality.

[0021] The present invention also proposes an embodiment of a welding device for implementing the above-mentioned rail welding method: it includes a composite heater, a sensor, a welding machine control system, and a hydrogen-oxygen mixed gas supply system. The sensor includes a temperature sensor, a hydrogen concentration sensor, a displacement sensor, and a flow sensor that are electrically connected to the welding machine control system respectively. The hydrogen-oxygen mixed gas supply system directly or indirectly provides gas to the composite heater.

[0022] The beneficial effects of the embodiments of the present invention are:

[0023] The combustion gas is a mixture of hydrogen and oxygen. The heat density is more concentrated during the entire welding process, the welding heat affected zone is narrower, and the quality of the welding joint is better. Through the coordination of the gas supply system, the composite heating system, and the control system, flexible adaptive adjustment is achieved in each stage. This system can quickly increase the heating temperature of the rail to be welded in the initial stage. The flexible flow adjustment method can make the rail continue to heat up but the surface does not melt. It can continuously and stably heat the rail to be welded to achieve the optimal temperature field required for rail gas pressure welding. There is no violent melting and flying on the rail surface and the heat is sufficient to penetrate into the center of the rail. Due to the high thermal efficiency, the quality of the rail welding joint can be improved. The welding gas quality is stable, the welding heat is concentrated, the heat affected zone is small, and it is beneficial to the rail welding organization; due to the flexible flow control method, the heating is stable, not only the swing amplitude is small, but also the normalizing time is saved, which improves the welding efficiency. In addition to hydrogen and oxygen, no other substances need to be added to the mixed gas, and the operation is more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 It is an overall schematic diagram of a rail welding system based on hydrogen-oxygen mixed gas combustion heating according to an embodiment of the present invention.

[0026] Figure 2 Schematic diagram of a composite heating system in an embodiment of the present invention.

[0027] Figure 3 It is a schematic longitudinal section diagram of a swing fire in an embodiment of the present invention.

[0028] Figure 4 It is a top view schematic diagram of the swing fire in the embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram of the relationship between time and position when swinging the fire in an embodiment of the present invention.

[0030] Figure 6 and Figure 7 It is a surface temperature measurement curve of the rail welding method based on hydrogen-oxygen mixed gas combustion heating in an embodiment of the present invention.

[0031] Figure 8 It is the surface temperature measurement curve of the prior art. DETAILED DESCRIPTION

[0032] 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 part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Please refer to Figure 1 The embodiment of the present invention discloses a rail welding system based on hydrogen-oxygen mixed gas combustion heating, including a gas supply system, a composite heating system and a control system 5.

[0034] Gas supply system

[0035] The gas supply system includes an energy storage device 1, an electrolyzer 2 and a hydrogen-oxygen mixed gas supply device 3. It should be understood that the energy storage device 1 can be powered by new energy 4 or other means. The gas supply system can provide a precise proportion of hydrogen-oxygen mixed gas, with a ratio of hydrogen to oxygen of 2:1, so that the hydrogen can be fully burned; no auxiliary agent is required during welding; no high-pressure gas cylinder is used to store gas, and the gas can be used as it is made; according to the requirements of different rail types, the gas supply volume can be selected to be stable in the range of 40,000 to 70,000 L / h, 40,000-60,000 L / h for 60 rails, and 60,000-70,000 L / h for 70 rails; the heating gas flow provided by the gas supply system is controlled by the welding control system 5 PLC, and the total gas supply flow is adaptively adjusted and controlled according to the heating process.

[0036] In one example, a pure water electrolyzer is used to electrolyze hydrogen and oxygen to provide gas to the hydrogen-oxygen mixed gas supply system. In the prior art, gas cylinders are used for welding, and the rolling of gas cylinders during transportation can easily cause danger. In this implementation, hydrogen and oxygen are produced on-site by electrolyzing water. The welding process does not require high-pressure gas cylinders to store gas. Gas can be used as it is produced, which is safe and efficient. In actual construction applications, the safety of welding is improved and construction conditions are also improved.

[0037] Composite heating system

[0038] Please refer to Figure 2 , Figure 2The schematic diagram of the heating hardware system of hydrogen-oxygen oxygen pressure welding is shown. The composite heating system includes a hydrogen-oxygen mixing gun 15, a composite heater, and a swing device. The hydrogen generator 13 prepares hydrogen by hydrolysis, and the hydrogen of the hydrogen generator is transmitted to the hydrogen-oxygen mixing gun 15 through the distributor 14. The air compressor 16 provides compressed air to the hydrogen-oxygen mixing gun 15. The hydrogen-oxygen mixing gun 15 transmits the hydrogen-oxygen mixed gas to the composite heater. The heating hardware system is installed in the welding machine to achieve full-section heating of the rail weld.

[0039] The composite heater 18 is a split-type special-shaped box nested structure. The composite heater 18 includes a matching heater I and a heater II. The rail RL to be welded is placed between the heater I and the heater II. The composite heater 18 is provided with forced air cooling holes with multiple circles and multiple heating fire holes according to the heat input demand ratio of the rail head, rail waist and rail bottom area. A water cooling channel 17 and an air cooling channel are also provided inside. The air cooling channel provides cooling air through an air compressor 16 for cooling the rail welding head and the heater itself, meeting the welding process and the need for stable joint quality. The composite heater is equipped with a mixed gas pipe, an air pipe, a water pipe, etc., and is transmitted to the composite heater. The mixed gas pipe transports hydrogen and oxygen to the hydrogen-oxygen mixing gun 15, the air pipe transports cooling air to the composite heater, and the water pipe transports cooling water to the composite heater.

[0040] The composite heater 18 is connected to a swing device, which can drive the composite heater to swing along the axial direction of the rail through a driving motor and program control, and can make the swing amplitude and frequency match the heating conditions of the hydrogen-oxygen flame. In one example, the swing device includes a motor and a rotating shaft, the motor drives the rotating shaft to rotate, the composite heater is connected to the rotating shaft, and the rotating shaft drives the composite heater to swing back and forth. The composite heater 18 is a part of the rail welding machine head 19.

[0041] Control System

[0042] The hydrogen-oxygen mixed gas heating software system is a special control program that presets and controls welding parameters according to the needs of welding different rail types, including: heating time, airflow size, swing amplitude and frequency and other welding heating parameters, and can automatically switch to achieve control of the entire welding process; the hydrogen-oxygen mixed gas heating system can accurately adjust and control the heat input, heating zone width, heating rate and other process parameters of the head, waist and bottom of the rail to be welded. The welding parameters are stable and reliable, which can ensure consistent and stable welding heating of the entire section of the rail and establish a good welding temperature field.

[0043] The hydrogen-oxygen mixed gas heating hardware and software system accepts the unified control instructions of the welding machine control system. According to the needs of the rail welding temperature field, a control mode of graded adjustment or stepless adjustment of parameters can be adopted. After the rails of different materials and rail types have been debugged and the process parameters have been confirmed, the set of welding process parameters that have passed the type inspection can be written into the control program of the welding machine host computer 6 (industrial computer), and then written into the slave computer (PLC), so as to realize the precise digital centralized control of the main welding process parameters such as the airflow size, swing amplitude and frequency, pressure holding pressure, welding time, upset forging amount, and convex pressure during the whole welding process, so as to ensure the stable and reliable quality of the rail welding joint.

[0044] The heating gas flow provided by the mixed gas supply system is controlled by the welding control system (PLC) to adaptively adjust and control the total gas supply flow according to the heating process. In one example, the mixed gas supply system provides a mixed gas of hydrogen and oxygen, and the volume ratio of hydrogen to oxygen is 2:1.

[0045] The control system also includes a temperature sensor, a hydrogen concentration sensor, a displacement sensor 32, a flow sensor 31, and a pressure sensor 33, which are respectively connected to the controller. The temperature sensor is used to detect the surface temperature of the rail to be welded and transmit the temperature signal to the welding machine control system 5. If the surface temperature reaches a threshold, in one example, the threshold A C1 The phase change temperature enters the second stage control; if the surface temperature reaches the top forging temperature, the third stage control ends. The welding machine control system 5 controls the composite heater to start swinging. The hydrogen concentration sensor is used to detect the hydrogen concentration in the combustion gas. If the hydrogen concentration reaches the threshold, the welding machine control system increases the flow rate of the inert gas in the inert gas injection pipeline to avoid welding defects. The displacement sensor is used to detect the swing amplitude of the composite heater and the displacement of the rail. If the swing amplitude is greater than or less than the preset swing amplitude, the swing device is adjusted according to the feedback value of the control system. If the displacement of the rail changes and the amplitude of the change exceeds the preset value, the welder further fixes the rail according to the feedback value of the control system. The flow sensor is used to detect the hydrogen and oxygen flow rate of the hydrogen and oxygen mixed gas supply system and the flow signal is transmitted to the welding machine control system 5.

[0046] According to the needs of the rail welding temperature field, a control mode of graded adjustment or stepless flexible adjustment of parameters can be adopted. After the rails of different materials and rail types have been debugged through welding process and the process parameters have been confirmed, the set of welding process parameters that have passed the type inspection can be written into the control program of the welding machine host computer 6 (industrial computer), and then written into the slave computer (PLC), so as to realize the precise digital centralized control of the main welding process parameters such as airflow size, swing amplitude and frequency, holding pressure, welding time, upset forging amount, and convex pressure during the whole welding process, so as to ensure the stable and reliable quality of the rail welding joints.

[0047] In this embodiment, a 60-gauge rail is used as an example to illustrate the rail heating method in the embodiment of the present invention. It should be understood that the parameters of a 70-gauge rail are adjusted accordingly according to the cross-sectional quality and profile. The rail heating method includes the following steps:

[0048] S0 Preparation: The rails with end face milling and joint grinding are clamped by rail welding machine.

[0049] S1 sprays a mixed gas including hydrogen onto the rail to be welded.

[0050] S2 adjusts the initial flow rate: controls the initial flow rate of the mixed gas.

[0051] S3 continuous pressure: continuous pressure is applied to the rails to ensure that the rails do not move.

[0052] S4 Heating: Heating the welded rail seam.

[0053] S5 Swinging: The swinging amplitude gradually increases. The small swinging amplitude rapidly increases the heat of the weld, expels air, and protects the joint, preventing water vapor, oxygen, etc. from invading the weld and causing welding defects. In one example, the swinging frequency is fixed. In another example, the swinging frequency is variable. There is a variable swinging amplitude during the welding process. This operation can protect the joint and improve the heating effect, which ultimately reduces the possibility of welding defects and improves the joint structure and performance.

[0054] S6 Flexible reduction of gas flow: gradually reduces the gas flow.

[0055] S7 flameout upsetting.

[0056] S8 pushes the tumor.

[0057] After welding is completed, the temperature is cooled by air, the air cooling pressure is 0.2-0.5Mpa, and the air cooling time is 180-220 seconds.

[0058] In the S0 preparation step, in one example, the S0 preparation step includes S01, clamping the rails after end face milling and joint grinding through a rail welding machine, controlling the rail pulling force of 5-7Mpa to align the rails and ensure that the misalignment of the rails is within 0.1mm.

[0059] In the S0 preparation step, in another example, the S0 preparation step further includes S02, namely, continuously spraying an inert gas, such as argon, to the welding portion. In one example, the spraying of the inert gas continues until the welding is completed.

[0060] The inventors have made further improvements. The first is a method of rapidly raising the temperature, the second is a method of adjusting the gas flow rate, and the third is a method of adjusting the swinging fire. The purpose of adjusting the flow rate and the swinging fire is to control smooth heating.

[0061] In the step of injecting the mixed gas in S1, the injection pressure ranges from 0.1 to 0.3 MPa, and the injection is continuous or intermittent.

[0062] In one example, S2 flow regulation includes:

[0063] S21 adjusts the initial flow rate: controls the initial flow rate of the mixed gas to 48000L / h-50000L / h, and the volume ratio of hydrogen and oxygen gas is 2:1 to ensure complete combustion of hydrogen and oxygen.

[0064] After S22 adjusts the initial flow rate, the hydrogen and oxygen gas at the rail joint position is ignited and heated.

[0065] In this embodiment, the control is carried out in three stages. The first stage lasts until the rail surface temperature reaches A C1 Phase change temperature, the second stage lasts until the rail surface temperature reaches the upsetting temperature, and the third stage lasts until the welding is completed.

[0066] Flexible regulation of mixed gas:

[0067] In the first stage, the initial flow rate of the mixed gas is adjusted, and it is inconvenient to fix the initial flow rate;

[0068] The second stage is adjusted according to the first flow function, the first flow function is L = -k*t + 185400, the unit of flow L in the second stage is L / h, t is time, the unit is second, and the constant k = -3000.

[0069] The third stage is adjusted according to the second flow function, the second flow function is L = -a·t2 + L0, L0 is the mixed gas flow at the end of the second stage; a is the adjustment coefficient, ranging from 0.7 to 1.2; t is time; L is the hydrogen-oxygen mixed gas flow in the third stage, thereby controlling the stable heating of the rail. It should be understood that the flexible reduction method of the flow between the two stages can also be exponential decline, logarithmic decline, inverse proportional decline, stepless decline, parabolic decline, etc.

[0070] In another embodiment of the flexible flow reduction, a step-by-step reduction is adopted. Different types of rails require different hydrogen-oxygen mixed gases, and the flow rate of the hydrogen-oxygen mixed gas is 40,000-60,000 L / h. It should be understood that the gas supply volume can be selected to be stable in the range of 40,000 to 60,000 L / h according to the requirements of different rail types. The flow rate of 60 rails is 40,000-50,000 L / h, and the flow rate of 75 rails is 50,000-60,000 L / h.

[0071] Phase 1

[0072] Use a large flow rate to quickly heat the rail weld position, burn and remove the air around the rail joint, form a protective atmosphere, and prevent impurities from invading the weld and affecting the joint quality. The initial flow rate L1 is 40000-60000L / h.

[0073] Phase II

[0074] Rail temperature to A C1 Above the phase change temperature, the flow rate decreases gently step by step.

[0075] Phase 3

[0076] Entering the temperature maintenance and permeation stage, the flow rate of the mixed gas decreases relative to the initial flow rate. In one example, the flow rate L3 from 120 seconds to flameout is 42000 L / h.

[0077] Please refer to Figure 3-5 In the S5 swinging step, the swinging time is when the surface temperature of the welded rail reaches A C1 Phase transition temperature, in one example, 60 seconds after ignition, the surface temperature of the welded rail reaches A C1 Phase transition temperature. In another example, the flame swinging starts 60 seconds after ignition. That is, the flame swinging starts after 60 seconds of continuous heating and continues until the flame is extinguished. Since the flexible flow control method in this embodiment can provide smooth heating and has higher thermal efficiency, the flame swinging amplitude is smaller than the conventional flame swinging amplitude, and gradually increases from the middle position to 25-40mm.

[0078] Figure 3 It is a longitudinal cross-sectional diagram of the heater heating the rail to be welded. Heater I and heater II are used in combination, and the rail to be welded RL is located between heater I and heater II. When the fire is swinging, heater I rotates around the first axis Z1, and heater II rotates around the second axis Z2.

[0079] Figure 4 It is a top view schematic diagram of the swinging fire of heater I and heater II. Figure 4 (a) is a schematic diagram of the position when there is no fire. Figure 4 (b)-(c) are schematic diagrams of the positions of heaters I and II for staggered heating. The rail RL to be welded is located between heaters I and II. Figure 4 In (b), the heater I first rotates from the O axis to the first direction, Figure 4 In (c), the heater I returns to the O axis and then rotates in the second direction. Figure 4 In (b), the heater II first rotates from the O axis to the second direction, Figure 4 In (c), the heater II returns to the O axis and then rotates in the first direction. The first direction is opposite to the second direction, that is, the heater I and the heater II rotate in opposite directions.

[0080] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the heater position and time. The direction of the vertical arrow is the first direction, and the direction opposite to the arrow is the second direction. Please refer to Figure 4 The maximum swing amplitude of heater I in the first direction and the second direction are D1 and D2 respectively, and the maximum swing amplitude of heater II in the second direction and the first direction are D3 and D4 respectively. In one example, D1, D2, D3 and D4 are 25-27 mm respectively. The figure is a schematic diagram of the relationship between heater position and time in a sinusoidal distribution.

[0081] The total time for heating the rail is 280s-300s, and then the flame is turned off for upsetting. In the S7 flame-off upsetting step, 15-18Mpa upsetting force is applied for upsetting for 3 seconds. In the S8 bump-pushing step, 18-20Mpa bump-pushing pressure is applied for bump-pushing.

[0082] In the S5 swinging step, that is, the heating process of the rail, the position of the composite heater changes with time in a sinusoidal function. The sinusoidal function is y=b·sin(fπt), y is the distance the heater deviates from the initial heating position, f is the swing frequency, t is the time, b is the swing amplitude setting value, and the value of b is 5-40. For example, when b=40, f=0.5, y=40*sin(0.5*πt), that is, at 0.5s, the position of the composite heater is 28mm, and at 1s, the position of the composite heater is 40mm.

[0083] In the swinging step S5, i.e., during the heating of the rail, the swing amplitude of the composite heater is adjusted according to the swing amplitude function. The swing amplitude function is D = -k d (dT / dt)+b, D is the swing amplitude, kd is the swing amplitude variation coefficient, k d The value is 0.1-2, T is the rail temperature, t is the time, b is the swing setting value, f is the swing frequency coefficient, and the value of f is 0.1 to 2. For example, k d =0.5, b=40, (dT / dt)=20, the swing amplitude D=-0.5*20+40=30mm.

[0084] Please refer to Figure 6-8 , Figure 6 , Figure 7 When the oxyhydrogen welding method of this embodiment is used to heat the rail, the surface temperature of the rail to be welded rises faster, reaching 700° C. in 60 seconds and 820° C. in 100 seconds, with higher thermal efficiency. Figure 8 This is a test of the prior art, in which the temperature is 600° C. at 100 seconds, which is 220 degrees lower than the method in the embodiment of the present invention.

[0085] The effective effects of the flexible flow control method of the embodiment of the present invention are:

[0086] First, through the coordinated cooperation of the gas supply system, the composite heating system, and the control system, flexible adaptive adjustment is achieved in each stage. This system can quickly increase the heating temperature of the rails to be welded in the initial stage. The flexible flow adjustment method can make the rails continue to heat up without melting the surface. It can continuously and stably heat the rails to be welded and achieve the optimal temperature field required for rail gas pressure welding.

[0087] Second, stable heating is controlled by controlling the flow rate at each stage. Stable heating means that there is no violent melting and flying on the rail surface and the heat is sufficient to penetrate into the center of the rail, thereby improving the welding heating efficiency. The rail surface temperature rises to 1400-1500°C in about 220 seconds, and then continues to heat for 60-80 seconds, which can make the center of the rail reach above 1150°C, and the rail can be heated to the top forging temperature more quickly. The time from ignition to flameout is 280-300 seconds, which saves construction time and improves welding efficiency. Since the flexible flow control method of this embodiment has high thermal efficiency and a small amplitude when swinging the fire, the welding heat affected zone is narrower and the welding quality is better.

[0088] Third, since the flexible flow control method heats stably, normalizing time is saved and normalizing is not required. Normalizing generally takes 200-300 seconds. Although the oxyhydrogen welding method of this embodiment saves normalizing time and does not require normalizing, the grain refinement and carbide distribution of the rail are still uniform, and the structure on the rail meets the requirements of standard TB / T 1632. Therefore, the welding method in this embodiment further shortens the construction time and improves the welding efficiency on the basis of ensuring the welding quality.

[0089] During construction, without changing the overall structure of the existing welding machine, the hydrogen-oxygen mixed gas heating system can be installed on the existing welding machine to replace the original oxyacetylene heating system, which can easily realize the docking conversion of the gas supply system. Hydrogen can be prepared by delivering water to the hydrogen generator, without the need for heavy and backward loading and unloading of gas cylinders. This traditional construction mode will be completely abandoned and eliminated due to technological progress. Only pure water can be easily carried to continue construction. The most beneficial thing is that green hydrogen welding can truly achieve zero carbon emissions.

[0090] The rail welding system of this invention effectively solves the bottleneck problems that have long plagued the construction of pneumatic rail welding vehicles, such as frequent loading and unloading of high-pressure gas cylinders and fluctuations in gas quality from gas suppliers. It provides key technologies and feasible technical solutions for obtaining higher-quality rail welding joints and ensuring the safety and stability of the operation process. It is suitable for various occasions of on-site rail welding, including long rail welding on mobile bases, on-site welding construction of new lines, and welding construction for repair and maintenance of existing lines. It has the advantages of high operational safety, excellent joint quality, convenient construction, and zero carbon emissions.

[0091] The rail welding system heated by hydrogen-oxygen mixed gas adopts hydrogen-oxygen mixed gas to replace oxyacetylene gas heating method. The rail welding process still maintains the unique advantages and characteristics of the original welding machine's unique constant displacement control process. Its process parameters can be solidified and output according to the set of process parameter results determined by type tests, reliably ensuring stable and consistent on-site rail welding quality.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rail welding method based on hydrogen-oxygen mixed gas combustion heating, the rail welding method comprising a method for a gas supply system to provide mixed gas, a method for a composite heating system to heat the rail, and a control method; the gas supply system provides a mixed gas of hydrogen and oxygen to the composite heating system; the composite heating system comprises a hydrogen-oxygen mixed gun, a composite heater, and a swing device, the swing device drives the composite heater to swing back and forth; the control system provides a flow control method for controlling the mixed gas, a swing amplitude control method for the swing device, and a swing frequency control method for the swing device; The control system is divided into three stages: the first stage lasts until the rail surface temperature reaches A C1 Phase change temperature, the second stage lasts until the rail surface temperature reaches the upsetting temperature, and the third stage lasts until the welding is completed; For the flow control of the mixed gas, the initial flow of the mixed gas is adjusted in the first stage and the initial flow is kept fixed, in the second stage, flexible adjustment is started according to the first flow function, and in the third stage, adjustment is performed according to the second flow function. During the heating process, the position of the composite heater changes as time increases in a sinusoidal function, and the swing amplitude of the composite heater is adjusted according to the swing amplitude function; The composite heating system includes a composite heater, which includes a composite heater I and a composite heater II that are used in combination and surround the steel rail to be welded in the middle. The heater I and the heater II are respectively provided with fire holes, and the number of the fire holes for heating the rail head accounts for 37%, the number of the fire holes for heating the rail waist accounts for 26%, and the number of the fire holes for heating the rail bottom accounts for 37%.

2. The rail welding method according to claim 1, characterized in that: The first flow function is L=-k*t+185400, the unit of the flow L in the second stage is L / h, t is time, the unit is second, and the constant k=-3000.

3. The rail welding method according to claim 2, characterized in that: The second flow function is L = -a·t 2 +L0, L0 is the mixed gas flow rate at the end of the second stage; a is the adjustment coefficient, ranging from 0.7 to 1.2; t is the time, the unit is second; L is the flow rate of hydrogen-oxygen mixture in the third stage, which controls the smooth heating of the rails.

4. The rail welding system according to claim 1, characterized in that: The control system also includes a swinging adjustment method for swinging amplitude and swinging frequency, and the swinging start time is when the surface temperature of the steel rail to be welded reaches A C1 Phase transition temperature.

5. The rail welding method according to claim 1, characterized in that: During the heating process, the sinusoidal function is y=b·sin(fπt), y is the distance the heater deviates from the initial heating position, f is the swing frequency, t is the time, b is the swing amplitude setting value, and the value of b is 5-40.

6. The rail welding method according to claim 1, characterized in that: The swing amplitude function is D=k d (dT / dt)+b, D is the swing, k d is the swing variation coefficient, k d The value range is 1-4, T is the rail temperature, t is the time, b is the swing setting value, f is the swing frequency coefficient, and the value of f is 0.1 to 2.

7. The rail welding method according to claim 1, characterized in that: The control system also includes a temperature sensor for detecting the surface temperature of the rail, a displacement sensor for detecting the swing amplitude of the position composite heater and the position of the rail, and a flow sensor for detecting the air supply system. The control system compares the actual temperature value detected by the temperature sensor, the actual swing amplitude detected by the displacement sensor, the position of the rail, and the actual flow detected by the flow sensor with the corresponding threshold values, and the control system calculates a feedback value based on the measurement values ​​of the corresponding sensors.

8. The rail welding method according to claim 7, characterized in that: A gas pipe is arranged inside the composite heater, and a water cooling pipeline and an air cooling pipeline for cooling are also arranged inside the composite heater.

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