A high quality rail fixation flash welding device and method

Abstract

The application discloses a high-quality fixed flash welding device and method for steel rails, which comprises a protection device, the protection device comprises a first closed protection cover and a second closed protection cover, the two sides of the first closed protection cover and the second closed protection cover are connected with the first closed protection cover and the second closed protection cover through pneumatic driving mechanisms, and the first closed protection cover and the second closed protection cover form a double-leaf full-closed protection cover through the pneumatic driving mechanisms, the inner cavity profiles of the first closed protection cover and the second closed protection cover are completely matched with the rail head, the rail waist and the rail bottom, the closed gap is less than or equal to 0.5 mm, a sealed protection cavity is formed, the high-temperature welding area is completely wrapped, and annular uniform air hole assemblies are arranged on the inner walls of the first closed protection cover and the second closed protection cover, the annular uniform air hole assemblies extend to the outside of the first closed protection cover and the second closed protection cover through connecting pipes and are connected with inert gas pipelines.

Description

Technical Field

[0001] This invention belongs to the field of rail welding technology, specifically relating to a high-quality fixed flash welding device and method for rails. Background Technology

[0002] Currently, fixed flash welding of rails generally adopts open environment welding, and there is no dedicated inert gas protection device in the high-temperature zone of the joint. This is the core reason for the high incidence of weld defects and unstable mechanical properties. During welding, the molten steel reacts rapidly with O2, N2, and H2O in the air to generate inclusions such as FeO, Fe3N, and MnO. This causes oxygen and nitrogen enrichment in the weld, which easily leads to porosity, slag inclusions, ash spots, and microcracks. Consequently, the impact toughness of the joint decreases and fatigue life is insufficient, which restricts the safe service of high-speed rail and heavy-haul lines.

[0003] Existing technology discloses a railway track welding protection device, relating to the technical field of railway track welding protection devices. It addresses the problem that existing railway track welding protection devices generate molten slag during welding, which accumulates around the rails and affects the normal progress of welding. The device has two side baffles installed on both sides of the rail support base plate, with two water channels on the outer surface of each side baffle. An acrylic protective cover is installed at the upper end of each side baffle, and four fixed bases are installed on one side of each side baffle. One end of each fixed base is equipped with a hydraulically telescopic fixed column base. However, this existing technology lacks a uniform gas distribution and closed-loop gas control structure, does not provide metallurgical protection, and cannot inhibit nitriding.

[0004] Existing technology discloses a railway track welding protection device, including a base plate, a lifting and adjusting rod, and a rail placement plate. Side baffles are symmetrically fixed to both sides of the rail placement plate, and a transparent acrylic protective cover is installed above the side baffles. One end of the acrylic protective cover is rotatably connected to one of the side baffles via a hinge, and the other end of the acrylic protective cover is connected to the other side baffle via a locking mechanism. Telescopic cylinders are symmetrically fixed to both sides of the side baffles along the center, and pressure blocks are fixed to the ends of the cylinder rods. Circular holes are opened on multiple sides of the acrylic protective cover, and arm protective sleeves are fixedly connected to the inner walls of the circular holes. The above-mentioned prior art uses a transparent acrylic cover, emphasizing operational safety and observation. However, it is not resistant to high temperatures, lacks a sealed cavity adapted to the rail profile, and cannot be used for the protection of high-temperature joints in flash welding. Summary of the Invention

[0005] The purpose of this invention is to provide a high-quality fixed flash welding device and method for rails to solve the problems mentioned in the background art.

[0006] The objective of this invention is achieved through the following technical solution: a high-quality fixed flash welding device for steel rails, comprising a protective device, wherein the protective device comprises a first closed protective cover and a second closed protective cover, wherein the two sides of the first closed protective cover and the second closed protective cover are respectively connected to the first closed protective cover and the second closed protective cover by a pneumatic drive mechanism, and the first closed protective cover and the second closed protective cover form a split-type fully enclosed protective cover by the pneumatic drive mechanism.

[0007] The inner contours of the first and second closed protective covers are completely fitted with the rail head, rail web and rail bottom, with a closing gap of ≤0.5mm, forming a sealed protective cavity that completely encloses the high-temperature welding area;

[0008] The inner walls of the first and second closed protective covers are provided with annular evenly distributed air hole assemblies, which extend to the outside of the first and second closed protective covers through connecting pipes and are connected to inert gas pipelines.

[0009] Furthermore, infrared temperature probes are fixedly installed on the first and second closed protective covers. The infrared temperature probes are aligned with the welded joint position at the center of the cavity formed by the first and second closed protective covers, with a temperature measurement accuracy of ±5℃. The temperature signal line of the infrared temperature probe is electrically connected to the PLC controller.

[0010] Furthermore, the first and second closed protective covers are composite materials made of high-temperature resistant alloy lined with heat-insulating ceramic components, with a temperature resistance of ≥1600℃.

[0011] Furthermore, the heat-insulating ceramic component is designed in sections, and the heat-insulating ceramic component is divided into several lining pieces. A 1-2mm thermal expansion gap is reserved between each heat-insulating ceramic component, and the gap is filled with flexible high-temperature resistant ceramic rope.

[0012] Furthermore, the annular uniformly distributed air hole assembly includes spaced high-temperature resistant metal rings. The high-temperature resistant metal rings are made of the same material as the first and second closed protective covers. The surface of the high-temperature resistant metal rings is coated with an MCrAlY high-temperature protective coating with a thickness of 50-80μm.

[0013] Furthermore, the pneumatic drive mechanism includes a cylinder, which is disposed at one end of the linear guide base. The linear guide base is rigidly fixed to the fixed frame of the flash welding machine. The output end of the cylinder is connected to the guide slider. A metal seat is installed on the guide slider. The first and second closed protective covers are mounted on the metal seat through high-temperature resistant heat insulation pads.

[0014] A method for applying a high-quality fixed flash welding device for steel rails includes the following steps;

[0015] During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers.

[0016] During the S2 welding protection stage, after pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 15-25 L / min, continuously supplying gas to maintain a slight positive pressure in the cavity and prevent backflow of external air. The flash welding host is started, and flash melting and upsetting are all carried out inside the cavity of the closed protective cover; infrared thermography continuously collects the weld temperature, the protective cover remains closed throughout the process, and the protective gas is supplied continuously.

[0017] After the welding protection action is completed, the post-protection cooling stage begins. The PLC controller reduces the flow rate to 8-12 L / min for continuous ventilation, and the timing is 25-35 seconds. When the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second closed protective covers, and the rail weldment can be removed.

[0018] A method for applying a high-quality fixed flash welding device for steel rails reduces the oxygen content of the weld by more than 85% and increases the gas utilization rate by 40%.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention forms a closed air-isolated structure through a first closed protective cover / second closed protective cover, reducing the oxygen content of the weld by more than 85%; three layers of annular air holes are set along the rail head, rail web and rail bottom, so that air is discharged evenly in all directions without any protective dead corners; and a three-stage automatic gas control is adopted, which improves the gas utilization rate by 40%.

[0021] This invention enables real-time temperature measurement via an infrared temperature probe using a PLC controller, and controls the inert gas flow rate via a mass flow controller using the PLC controller.

[0022] The pre-charging and venting stage of this invention has a flow rate of 25–35 L / min and a time of 8–12 s, purging the air in the cavity to an oxygen content ≤0.1%. The welding protection stage has a flow rate of 15–25 L / min, with the entire flash and upsetting process completed within the protection cavity. The post-protection cooling stage has a flow rate of 8–12 L / min and a time of 25–35 s, stopping the gas supply when the temperature drops below 600°C, creating an oxygen-free environment within the protection cavity, resulting in a joint free from oxidation, porosity, and slag inclusions. The tensile strength is 1020 MPa, the impact energy is 32 J, and the flaw detection pass rate is 100%. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the connection between the first closed protective cover and the second closed protective cover of the present invention;

[0024] Figure 2 This is a schematic diagram of the PLC controller connection of the present invention;

[0025] Figure 3 This is a schematic diagram of the high-temperature resistant alloy of the first / second closed protective cover of the present invention;

[0026] Figure 4 This is the present invention. Figure 2 Enlarged schematic diagram of the pneumatic drive mechanism;

[0027] Figure 5 This is a schematic diagram of the connection between the pressure reducing valve / mass flow controller / solenoid valve of the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] like Figure 1-5 As shown, a high-quality fixed flash welding device for rails includes a protective device 1. The protective device 1 includes a first closed protective cover 2 and a second closed protective cover 3. The two sides of the first closed protective cover 2 and the second closed protective cover 3 are respectively connected to the first closed protective cover 2 and the second closed protective cover 3 through a pneumatic drive mechanism 4. The pneumatic drive mechanism 4 makes the first closed protective cover 2 and the second closed protective cover 3 form a split-type fully enclosed protective cover.

[0032] The inner contours of the first closed protective cover 2 and the second closed protective cover 3 are completely fitted with the rail head, rail web and rail bottom, with a closing gap of ≤0.5mm, forming a sealed protective cavity that completely encloses the high-temperature welding area;

[0033] The inner walls of the first closed protective cover 2 and the second closed protective cover 3 are provided with annular evenly distributed air hole assembly 5. The annular evenly distributed air hole assembly 5 extends to the outside of the first closed protective cover 2 and the second closed protective cover 3 through a connecting pipe and is connected to an inert gas pipeline.

[0034] The inert gas (argon) pipeline is equipped with a pressure reducing valve 16, a mass flow controller 17, and a solenoid valve 18, which are electrically connected to a PLC controller 7.

[0035] In a further preferred embodiment of the present invention, an infrared temperature probe 6 is fixedly installed on the first closed protective cover 2 and the second closed protective cover 3. The infrared temperature probe 6 is aligned with the welding joint position at the center of the cavity formed by the first closed protective cover 2 and the second closed protective cover 3, and the temperature measurement accuracy is ±5℃. The temperature signal line of the infrared temperature probe 6 is electrically connected to the PLC controller 7.

[0036] In the above embodiment, an infrared temperature probe 6 is used to collect the temperature of the welded joint in real time. The infrared temperature probe 6 is placed between adjacent heat-insulating ceramic components 9.

[0037] In a further preferred embodiment of the present invention, the first closed protective cover 2 and the second closed protective cover 3 are composite materials made of high-temperature resistant alloy 8 lined with heat-insulating ceramic components 9, with a temperature resistance of ≥1600℃.

[0038] In the above embodiments, the durability is improved by setting the first closed protective cover 2 and the second closed protective cover 3 as a composite of high temperature alloy 8 and heat-insulating ceramic component 9.

[0039] In a further preferred embodiment of the present invention, the heat-insulating ceramic component 9 is designed in sections, and the heat-insulating ceramic component 9 is divided into several lining pieces. A 1-2mm thermal expansion gap is reserved between each heat-insulating ceramic component 9, and the gap is filled with flexible high-temperature resistant ceramic rope.

[0040] In the above embodiments, several pieces of heat-insulating ceramic component 9 are provided to release thermal expansion stress and prevent the ceramic from cracking due to heat. During installation, the heat-insulating ceramic component 9 is fixed to the inner wall of the alloy shell by high-temperature screws.

[0041] In a further preferred embodiment of the present invention, the annular uniformly distributed air hole assembly 5 includes high-temperature resistant metal rings 10 spaced apart. The high-temperature resistant metal rings 10 are made of the same material as the first closed protective cover 2 and the second closed protective cover 3. The surface of the high-temperature resistant metal rings 10 is coated with an MCrAlY high-temperature protective coating with a thickness of 50-80μm.

[0042] In the above embodiment, the annular uniformly distributed air hole assembly 5 is fixed to the high-temperature resistant alloy of the protective cover by high-temperature resistant bolts, and does not directly contact the heat insulation ceramic component 9. The annular uniformly distributed air hole assembly 5 is set along the rail head, rail web and rail bottom. The annular uniformly distributed air hole diameter is 0.8-1.2mm, and it is evenly and densely distributed to achieve 360-degree all-round air outlet.

[0043] The high-temperature resistant metal ring 10 is arranged along the inner contour of the first closed protective cover 2 and the second closed protective cover 3. The high-temperature resistant metal ring 10 is configured as a ring structure of different sizes, and air holes are evenly distributed on the high-temperature resistant metal ring 10.

[0044] In a further preferred embodiment of the present invention, the pneumatic drive mechanism 4 includes a cylinder 11, which is disposed at one end of a linear guide base 12. The linear guide base 12 is rigidly fixed to the fixed frame of the flash welding machine. The output end of the cylinder 11 is connected to a guide slider 13. A metal seat 14 is fixedly installed on the guide slider 13. The housings of the first closed protective cover 2 and the second closed protective cover 3 are mounted on the metal seat 14 through a high-temperature resistant heat insulation pad 15.

[0045] In the above embodiments, the first closed protective cover 2 and the second closed protective cover 3 are opened and closed by a pneumatic drive mechanism 4, and heat insulation is performed by setting a high-temperature resistant heat insulation pad.

[0046] A method for applying a high-quality fixed flash welding device for steel rails includes the following steps;

[0047] During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers.

[0048] During the S2 welding protection stage, after pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 15-25 L / min, continuously supplying gas to maintain a slight positive pressure in the cavity and prevent backflow of external air. The flash welding host is started, and flash melting and upsetting are all carried out inside the cavity of the closed protective cover; infrared thermography continuously collects the weld temperature, the protective cover remains closed throughout the process, and the protective gas is supplied continuously.

[0049] After the welding protection action is completed, the post-protection cooling stage begins. The PLC controller reduces the flow rate to 8-12 L / min for continuous ventilation, and the timing is 25-35 seconds. When the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second closed protective covers, and the rail weldment can be removed.

[0050] The above method was applied to 60kg / m rails. The control group was open welding without protective devices. The examples are as follows:

[0051] Specific Example 1: Workpiece: 60kg / m steel rail, material U75V

[0052] During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers.

[0053] During the pre-charge and exhaust phase, the protective gas flow rate is 30L / min and the time is 10s to purge the air from the protective chamber, ensuring that the oxygen content in the chamber is ≤0.1% and eliminating the risk of welding oxidation.

[0054] During the S2 welding protection stage, after pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 20L / min, continuously supplying gas to maintain a slight positive pressure in the cavity and prevent backflow of external air. The flash welding host is started, and flash melting and upsetting are all carried out inside the cavity of the closed protective cover; infrared thermography continuously collects the weld temperature, the protective cover remains closed throughout the process, and the protective gas is supplied continuously.

[0055] After the welding protection action is completed, the post-protection cooling stage begins. The PLC controller reduces the flow rate to 10L / min for continuous air supply, and the timing is 30s. When the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second closed protective covers, and the rail weldment can be removed.

[0056] The cavity is protected to maintain an oxygen-free environment, and the joints are free from oxidation, porosity, and slag inclusions; the tensile strength is 1020MPa, the impact energy is 32J, and the flaw detection pass rate is 100%.

[0057] Comparative Example 1: Severe oxidation in open environment, with many pores and inclusions; tensile strength 860MPa, impact energy 12J; defect rate 32%.

[0058] Specific Example 2: Workpiece: 60kg / m steel rail, material U71Mn

[0059] During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers.

[0060] During the pre-charge and exhaust phase, the protective gas flow rate is 28L / min and the time is 9s to purge the air from the protective chamber, ensuring that the oxygen content in the chamber is ≤0.1% and eliminating the risk of welding oxidation.

[0061] During the S2 welding protection stage, after pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 18L / min, continuously supplying gas to maintain a slight positive pressure in the cavity and preventing backflow of external air. The flash welding host is started, and flash melting and upsetting are all carried out inside the cavity of the closed protective cover; infrared thermography continuously collects the weld temperature, the protective cover remains closed throughout the process, and the protective gas is supplied continuously.

[0062] After the welding protection action is completed, the post-protection cooling stage begins. The PLC controller reduces the flow rate to a low flow rate of 9L / min for continuous ventilation, and the timing is 28s. Once the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second closed protective covers, allowing the rail weldment to be removed.

[0063] The above embodiments provide sealing protection to suppress nitriding, resulting in uniform grain size; tensile strength of 930 MPa, impact energy of 41 J; and a flaw detection pass rate of 99.5%.

[0064] Comparative Example 2: Significantly increased oxygen and nitrogen content, poor toughness, tensile strength 810MPa, impact energy 14J; defect rate 38%.

[0065] Specific Example 3: Workpiece: 60kg / m steel rail, material U75VH

[0066] During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers.

[0067] During the pre-charge and exhaust phase, the protective gas flow rate is 32L / min and the time is 11s to purge the air from the protective chamber, ensuring that the oxygen content in the chamber is ≤0.1% and eliminating the risk of welding oxidation.

[0068] During the S2 welding protection stage, after pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 22L / min, continuously supplying gas to maintain a slight positive pressure in the cavity and prevent backflow of external air. The flash welding host is started, and flash melting and upsetting are all carried out inside the cavity of the closed protective cover; infrared thermography continuously collects the weld temperature, the protective cover remains closed throughout the process, and the protective gas is supplied continuously.

[0069] After the welding protection action is completed, the post-protection cooling stage begins. The PLC controller reduces the flow rate to 11L / min for continuous air supply, and the timing is 32s. When the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second closed protective covers, and the rail weldment can be removed.

[0070] The cavity is protected to maintain an oxygen-free environment, and the joints are free from oxidation, porosity, and slag inclusions; the tensile strength is 1020MPa, the impact energy is 32J, and the flaw detection pass rate is 100%.

[0071] The above embodiment features a sealed cavity that prevents hydrogen-induced cracking and oxidation inclusions; tensile strength is 1180 MPa, and impact energy is 28 J.

[0072] Comparative Example 3: Severe high-temperature oxidation, continuous inclusions, tensile strength 1050MPa, impact energy 13J.

[0073] A method for applying a high-quality fixed flash welding device for steel rails reduces the oxygen content of the weld by more than 85% and increases the gas utilization rate by 40%.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-quality fixed flash welding device for steel rails, characterized in that: The device includes a protective device (1), which includes a first closed protective cover (2) and a second closed protective cover (3). The two sides of the first closed protective cover (2) and the second closed protective cover (3) are respectively connected to the first closed protective cover (2) and the second closed protective cover (3) through a pneumatic drive mechanism (4). The pneumatic drive mechanism (4) makes the first closed protective cover (2) and the second closed protective cover (3) form a split-type fully enclosed protective cover. The inner contours of the first closed protective cover (2) and the second closed protective cover (3) are completely fitted with the rail head, rail web and rail bottom, with a closing gap of ≤0.5mm, forming a sealed protective cavity that completely encloses the high-temperature welding area; The inner walls of the first closed protective cover (2) and the second closed protective cover (3) are provided with annular uniformly distributed air hole assembly (5), which extends to the outside of the first closed protective cover (2) and the second closed protective cover (3) through a connecting pipe and is connected to an inert gas pipeline.

2. The high-quality fixed flash welding device for rails according to claim 1, characterized in that: Infrared temperature probes (6) are fixedly installed on the first closed protective cover (2) and the second closed protective cover (3). The infrared temperature probes (6) are aligned with the welding joint position of the cavity formed by the first closed protective cover (2) and the second closed protective cover (3). The temperature measurement accuracy is ±5℃. The temperature signal line of the infrared temperature probes (6) is electrically connected to the PLC controller (7).

3. The high-quality fixed flash welding device for rails according to claim 2, characterized in that: The first closed protective cover (2) and the second closed protective cover (3) are made of high temperature resistant alloy (8) lined with heat-insulating ceramic components (9) and have a temperature resistance of ≥1600℃.

4. The high-quality fixed flash welding device for rails according to claim 3, characterized in that: The heat-insulating ceramic component (9) is designed in sections. The heat-insulating ceramic component (9) is divided into several lining pieces. A 1-2mm thermal expansion gap is reserved between each heat-insulating ceramic component (9), and the gap is filled with flexible high-temperature resistant ceramic rope.

5. The high-quality fixed flash welding device for rails according to claim 4, characterized in that: The annular uniformly distributed air hole assembly (5) includes high-temperature resistant metal rings (10) spaced apart. The material of the high-temperature resistant metal rings (10) is the same as that of the first closed protective cover (2) and the second closed protective cover (3). The surface of the high-temperature resistant metal rings (10) is coated with MCrAlY high-temperature protective coating with a thickness of 50-80μm.

6. The high-quality fixed flash welding device for rails according to claim 5, characterized in that: The pneumatic drive mechanism (4) includes a cylinder (11), which is located at one end of a linear guide base (12). The linear guide base (12) is rigidly fixed to the fixed frame of the flash welding machine. The output end of the cylinder (11) is connected to the guide slider (13). A metal seat (14) is installed on the guide slider (13). The first closed protective cover (2) and the second closed protective cover (3) are mounted on the metal seat (14) through a high-temperature heat-insulating pad (15).

7. An application method of the high-quality fixed flash welding device for rails according to claim 6, characterized in that: Specifically, the steps are as follows; During the S1 pre-charge and exhaust stage, the rail is aligned and positioned. The pneumatic drive mechanism drives the first and second closed protective covers to close quickly. Once the covers are confirmed to be closed, the PLC controls the mass flow controller to output a large flow of protective gas. The gas is injected into the main cavity of the protective cover workpiece through the annular evenly distributed air hole assembly, establishing a slight positive pressure in the cavity. The original air is displaced and discharged from the gap between the first and second closed protective covers. During the S2 welding protection stage, after the pre-charging and venting are completed, the PLC controller switches the mass flow controller to a medium flow rate of 15-25L / min, continuously supplying gas to maintain a slight positive pressure in the cavity, preventing backflow of external air, and starting the flash welding host. Flash burning and upsetting are all carried out in the cavity inside the closed protective cover. Infrared thermography continuously collects the weld temperature, and the protective cover remains closed throughout the process, with the protective gas supplied continuously. S3 Post-Shielding Cooling Stage: After the welding shielding action is completed, the post-shielding cooling stage begins. The PLC controller reduces the flow rate to 8-12 L / min for continuous ventilation, and times it for 25-35 seconds. Once the temperature drops below 600℃, the air supply is stopped. After the air supply stops, the PLC controller outputs a signal to drive the pneumatic drive mechanism to open the first and second protective covers, allowing the rail weldment to be removed.

8. An application method of the high-quality fixed flash welding device for rails according to claim 7, characterized in that: The oxygen content in the weld is reduced by more than 85%, and the gas utilization rate is increased by 40%.

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