Early warning test method for switch rail fracture

Abstract

This invention provides a method for early warning testing of switch rail fracture, belonging to the field of switch rail monitoring technology. It includes the following steps: Step 1: Install multiple sets of sensors at the bottom of the switch rail; Step 2: Train wheels run on the switch rail. When the train wheel reaches point x1 at time t1, the sensors detect the strain value at the rail base and the dynamic strain at point x1; Step 3: When the train wheel reaches point x2 at time t2, the sensors detect the strain value at the rail base and the dynamic strain at point x2. This method can achieve real-time detection of changes in switch rail fracture, timely detection of switch rail cracks, and early warning before fracture. The detection process can be automated, eliminating the need for traditional, inefficient, and costly manual methods.

Description

Technical Field

[0001] This invention belongs to the field of turnout switch rail monitoring technology, and more specifically, relates to a test method for early warning of turnout switch rail fracture. Background Technology

[0002] The switch rail is the core component of the turnout system. Its function is to guide trains to pass straight or laterally. The integrity of the switch rail is the basis for ensuring the safe operation of trains. Since the switch rail is a moving part, if the switch rail breaks while a train is passing, the consequences will be unimaginable. Therefore, the safety requirement for the switch rail is that the train is not allowed to continue to pass after a breakage occurs. Protection against switch rail breakage must be detected and dealt with before the switch rail breaks.

[0003] In practice, the location of switch rail fractures is random. Testing for abnormal changes in the switch rail must cover the entire cross-section to ensure comprehensive monitoring of switch rail fracture damage. Since the development of switch rail and rail cracks is a gradual process, it begins slowly, starting with material yielding, followed by the formation of micro-cracks, further crack propagation, and finally fracture. Crack formation and propagation both occur at the bottom of the rail, and ultimately, the crack first penetrates the bottom and propagates upwards, resulting in switch rail fracture. Switch rail components are structures of finite length, typically between tens of meters. For effective crack detection of the entire switch rail, continuous testing along its entire length at the bottom of the rail is necessary to ensure comprehensive early warning monitoring of switch rail fractures.

[0004] Currently, strain gauge technology is mostly used for strain testing of structural surfaces. However, strain gauges have certain length limitations. For strain gauges used on the bottom of the rail, the length is about 10mm. If they are continuously arranged on the bottom of the rail, on a switch rail that is more than ten meters long, the number of related data testing and acquisition sensors and acquisition channels reaches thousands, making the actual testing equipment huge and complex, with high management and maintenance costs, and no practical application value.

[0005] Currently, monitoring of switch rail fractures mainly relies on ultrasonic testing equipment and manual inspection. Generally, the most common defect in switch rails is cracking due to various reasons. Under train load, cracks can develop into complete switch rail fracture within about one week, with particularly rapid development in the later stages. Therefore, monitoring intervals for switch rail fractures must be controlled within one week to detect them before fracture occurs, preventing adverse effects on train operation. This necessitates maintaining a certain frequency of daily inspections of switch rails. With the continuous development of rail transit, the use of switch rails is increasing rapidly, leading to a corresponding increase in the workload of switch rail fracture detection. Furthermore, existing technologies for switch rail fracture detection have certain uncertainties. Currently, most rail flaw detection uses ultrasonic waves, which frequently result in false positives or missed detections, leading to delayed detection and treatment of rail damage, especially switch rail damage, creating significant safety hazards. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a test method for early warning of switch rail fracture, which solves the technical problems in the prior art where traditional visual inspection has limitations and cannot detect the lower part of the switch rail, while ultrasonic testing often results in false detection or missed detection in actual testing, leading to a decrease in the stability of the switch rail system.

[0007] The purpose and effectiveness of the turnout switch rail fracture early warning test method of the present invention are achieved by the following specific technical means:

[0008] It includes the following steps:

[0009] Step 1: Install multiple sets of sensors at the bottom of the switch rail track;

[0010] Step 2: The train wheels run on the switch rail. When the train wheels reach point x1 at time t1, the dynamic strain at point x1 is detected by the sensor.

[0011] Step 3: When the train wheel reaches point x2 at time t2, the sensor detects the strain value at the bottom of the rail, i.e., the dynamic strain at point x2.

[0012] According to a preferred embodiment, all of the aforementioned sensors are grating strain sensors.

[0013] According to a preferred embodiment, multiple sets of grating strain sensors are arranged and distributed at the bottom of the switch rail, and the multiple sets of grating strain sensors are connected in series via optical fibers.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The sensors at the bottom of the switch rail enable full coverage detection of the strain value at the bottom of the switch rail; multiple sets of sensors can detect the strain changes of the switch rail in real time and convert them into digital signals for processing; regardless of the position of the train wheels, it can accurately measure the strain changes related to the contact with the train wheels, solving the problems that traditional visual inspection cannot detect the lower part of the switch rail, and that ultrasonic testing often results in false detection or missed detection in actual testing. It achieves a comprehensive correspondence between the position of the train wheels and the mileage of the switch rail at any given time, ensuring full coverage detection of the strain value at the bottom of the switch rail and improving stability.

[0016] 2. The sensors are connected in series via optical fibers, which ensures effective communication and data transmission between the sensors, improving the reliability and stability of the system. The optical fiber connection also has the advantages of strong anti-interference ability and long transmission distance, which can effectively transmit the data collected by the sensors and ensure the accuracy and reliability of the data.

[0017] 3. The sensor's detection of the switch rail at time t1 or t2 can monitor stress changes in real time, providing timely warnings of switch rail fracture. Other parts of the switch rail, not bearing the load of the train wheels, have relatively small deformation and strain values, having a smaller impact on the strain changes of the entire switch rail section. Therefore, at any given moment, the train wheels have a unique impact on the strain value of the rail base of the entire switch rail section. By monitoring the stress changes of the switch rail in real time, switch rail fractures can be detected in a timely manner, providing early warnings and enabling corresponding maintenance measures to ensure the safe operation of the turnout. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the test method for early warning of turnout switch rail fracture according to the present invention.

[0019] In the diagram, the correspondence between component names and drawing numbers is as follows:

[0020] 1. Switch rail; 2. Strain sensor with grating distribution; 3. Train wheel. Detailed Implementation

[0021] To further understand the present invention, preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings and examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0022] In the description of this invention, unless otherwise stated, "multiple sets" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] Example:

[0024] Please see as follows Figure 1 As shown, switch rail 1 undergoes bending deformation under train load, with the largest deformation typically occurring at the bottom of the rail, which is also the initial site of fracture. Analysis of actual switch rail fractures has proven that most switch rail fractures begin at the bottom. Before cracks develop under external force, the area where cracks form first undergoes yield deformation, at which point the strain increases significantly. When the yield strain reaches a certain level, a crack will form at that location. If the strain changes at the fracture site can be tested, it is possible to monitor the switch rail before cracks occur and detect them early. Based on the above analysis, by monitoring the strain at the bottom of the switch rail, abnormal strain at the rail bottom can be detected in a timely manner, providing an early warning of cracks at the rail bottom.

[0025] The turnout switch rail fracture early warning test method includes the following steps:

[0026] Step 1: Install multiple sets of sensors at the bottom of switch rail 1. These sensors can accurately measure the strain on switch rail 1, i.e., the degree of deformation of switch rail 1 when train wheel 3 passes over it, to obtain more comprehensive and accurate strain data and better analyze the strain distribution of switch rail 1. This helps to detect strain anomalies in switch rail 1 in a timely manner, warn of the risk of switch rail 1 breakage, and take corresponding maintenance and repair measures to ensure the safe operation of the turnout.

[0027] Step 2: The main function of switch rail 1 is to guide and direct the running direction of train wheel 3. When train wheel 3 runs on switch rail 1, when train wheel 3 runs to a specific position point x1 at a specific time t1, switch rail 1 will bear the load from the train and generate dynamic strain only when train wheel 3 passes through switch rail 1. Therefore, in other parts of switch rail 1, since there is no direct load, the force on switch rail 1 is small and no dynamic strain will be generated. Therefore, what the multiple sets of sensors detect is the dynamic strain at point x1.

[0028] Step 3: Train wheel 3 continues to run for a period of time t2, eventually reaching another position point x2. At this position point, multiple sets of sensors continue to measure the strain value at the bottom of switch rail 1, which reflects the dynamic strain at point x2. Finally, the multiple sets of sensors convert all the measured strain values ​​into digital signals and transmit them to the monitoring system. The monitoring system processes and analyzes these digital signals to assess the health condition of switch rail 1 and predict potential breakage risks. Through the analysis of strain data, the monitoring system can promptly detect abnormalities in switch rail 1 and take corresponding maintenance and repair measures to ensure the safe operation of the turnout system.

[0029] The sensors are all grating-distributed strain sensors 2, with multiple sets distributed on the bottom of the switch rail. These multiple sets of grating strain sensors are connected in series via optical fibers. This grating distribution layout avoids mutual interference between sensor units, ensuring measurement reliability and improving measurement accuracy.

[0030] In actual switch rails, the location of fracture is random. Testing for abnormal changes in the switch rail must cover the entire cross-section to ensure comprehensive monitoring of switch rail fracture damage. To address these technical issues, this invention proposes monitoring the surface strain of the entire switch rail bottom. Sensors installed at the bottom of the switch rail detect the dynamic strain under train load. If the dynamic strain becomes abnormal and exceeds the yield strain of the switch rail material, a crack is considered to have occurred or is about to occur. Since the development of switch rail and rail cracks is a gradual process, initially slow, it begins with material yielding, followed by the formation of micro-cracks, further crack propagation, and finally fracture. The entire process, from crack formation to crack propagation, occurs at the rail bottom. Ultimately, the crack first penetrates the rail bottom and then propagates upwards, resulting in switch rail fracture. Sensors located below the rail bottom cross-section can detect the yield strain generated by crack propagation before fracture at that cross-section. Through these sensors, the dynamic strain of the entire switch rail bottom can be obtained when a train passes. Because the point of impact of a train wheel on the switch rail is unique within a certain time frame, the wheel's movement on the switch rail at any given moment affects the strain value of the entire switch rail section's rail base. Furthermore, the wheel's position at any given moment corresponds to the mileage of the switch rail, enabling comprehensive detection of the switch rail base strain value and achieving blind-spot-free monitoring. This invention addresses the shortcomings of current railway switch rail fracture detection methods by proposing a detection method for switch rail fracture damage. It enables real-time detection of changes in switch rail fracture, timely detection of crack formation, and early warning before fracture. The detection process can be automated, eliminating the need for traditional, inefficient, and costly manual methods.

[0031] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A test method for early warning of switch point rail fracture, characterized in that: It includes the following steps: Step 1: Install multiple sets of sensors (2) continuously along the entire length of the bottom of the switch rail (1) to achieve blind-spot-free detection of the strain value of the bottom of the switch rail; Step 2: The train wheel (3) runs on the switch rail (1). When the train wheel (3) reaches point x1 at time t1, the strain value of the rail bottom and the dynamic strain at point x1 are detected by the sensor. At any given time, the dynamic strain at the section where the train wheel contacts the switch rail is the largest. Other parts of the switch rail have smaller dynamic strains because they are not in the section where the train wheel is under load. The position of the wheel at any given time corresponds to the mileage of the switch rail. Step 3: When the train wheel (3) reaches point x2 at time t2, the dynamic strain at point x2 is detected by the sensor at the rail bottom strain value. Step 4: Compare the dynamic strain detected by multiple sensors with the yield strain of the switch rail material. When the dynamic strain exceeds the yield strain of the switch rail material, it is determined that the switch rail has cracked or is about to crack, and a fracture warning is issued.

2. The turnout switch rail fracture early warning test method according to claim 1, characterized in that: All of the sensors (2) are grating strain sensors.

3. The turnout switch rail fracture early warning test method according to claim 2, characterized in that: Multiple sets of grating strain sensors are set up and distributed at the bottom of the tip rail (1). The multiple sets of grating strain sensors are connected in series by optical fibers.

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