Railway steel rail heating method

Abstract

The invention relates to a railway steel rail heating method which is characterized in that a power source (1), a control circuit (2) and electrothermal films (3) are included, the electrothermal films (3) are fixed to the two sides of a railway steel rail (5) through fixing frames (4), and the electrothermal films (3) are electrically connected with the power source (1) through the control circuit (2). The control circuit (2) at least comprises a temperature sensor (6), a current transformer (7) and an input and output interface circuit (8) which are electrically connected through an interface, commands are input to the control circuit (2) through the input and output interface circuit (8), and after the control circuit (2) receives the commands for heating the railway steel rail (5), the control switch (9) is switched on, so that the power supply (1) and the electrothermal film (3) are switched on; an alternating current power supply is input to the electric heating film to form a loop, large current is applied to the electric heating film to heat the electric heating film, and the electric heating film covers a railway steel rail to be heated.

Description

Technical Field

[0001] The invention relates to heating control, in particular to a method for heating railway rails. Background Art

[0002] In the natural environment, temperature changes will cause temperature stress inside the rails. If the temperature stress is too large, the rails are prone to expansion and cracking, which will affect the service life of the rails and driving safety. Therefore, when the maintenance personnel are changing the rails, they generally keep the rail temperature around the annual average temperature. In areas with cold winters such as Northeast my country, Tibet and northern Xinjiang, the ambient temperature does not meet the rail temperature requirements for rail changing operations for a long time in a year. Therefore, the rails need to be heated before the rail changing operation. At present, there are several methods for heating rails: Foreign countries usually use mixed gas flame heating method, which uses a flame gun to directly spray flames on the surface of the rails to heat the rails. This method has simple procedures and is easy to operate, but this method is more harmful to the surface of the rails and is prone to uneven stress inside the rails. The domestic stretching machine stretching method and the heating paste heat conduction method are commonly used. The stretching machine starts the hydraulic oil pump station to drive the stretching rod to stretch the rails and change the temperature stress of the rails. This method has the characteristics of accurate rail temperature control and is less affected by construction environment conditions, but it has the disadvantages of relatively complex operation procedures, long construction time, and uneven stress distribution inside the rails. The heat conduction method of heating stickers is to attach a thermal resistance wire to the surface of the rail and heat the rail through heat conduction. This method has the disadvantages of low heat conduction efficiency and uneven temperature distribution. In recent years, the electromagnetic induction heating method has emerged. This method uses an electromagnetic device to generate an alternating magnetic flux, generate an induced electromotive force in the rail, and then generate eddy currents to heat the rail. This method has high heat conversion efficiency, but it has the disadvantages of high cost, easy damage to the electromagnetic head, limited heating distance, and inconvenient operation. Therefore, it has not been widely used in practice. Summary of the invention

[0003] One of the purposes of the present invention is to provide a method for heating railway rails, so as to solve the problems of uneven heating of the railway rails as a whole or complicated operation process in existing heating methods.

[0004] A second object of the present invention is to provide a method for heating railway rails so as to facilitate local heating of the railway rails.

[0005] The object of the present invention is achieved by: relating to a method for heating railway rails, characterized in that: The invention comprises a power supply, a control circuit and an electric heating film. The electric heating film is fixed on both sides of the railway rail through a fixing frame. The electric heating film is electrically connected to the power supply through the control circuit. The control circuit at least comprises a temperature sensor, a current transformer and an input-output interface circuit electrically connected to the interface. A command is input to the control circuit through the input-output interface circuit. After the control circuit receives the command to heat the railway rail, the control switch is turned on to connect the power supply and the electric heating film. The railway rail is heated through the electric heating film. The control circuit detects the temperature of the temperature sensor and the current of the current transformer so that the current flowing to the electric heating film and the detected temperature are within a set range. When the railway rail needs to be heated, an AC power supply is input to the electric heating film so that the group forms a loop, a large current is applied to the electric heating film to make it heat up, and the electric heating film covers the required railway rail heating. After the target temperature is set in the temperature control unit, the actual temperature is compared in real time. When the surface temperature of the heated rail reaches the set target temperature, the work is automatically stopped. When the surface temperature of the heated rail does not reach the set target temperature, the heating is continued, thereby realizing the temperature comparison for work feedback.

[0006] The temperature sensor is a thermocouple, which is distributed on both sides of the railway rail and is wrapped by an electric heating film and the railway rail.

[0007] The fixing frame is a metal alloy elastic frame.

[0008] The fixing frame is a stainless steel elastic frame.

[0009] The switch is a bidirectional thyristor, and the heating temperature is adjusted by the duty cycle of the bidirectional thyristor.

[0010] It also includes a leakage protector, which is electrically connected to the railway rail and the grounding connecting wire. When there is leakage current between the railway rail and the grounding connecting wire, the electric circuit between the power supply and the electric heating film is disconnected.

[0011] The control circuit is supplied by a DC power supply, which is a 5V voltage supplied by a switching power supply through a power supply.

[0012] The power supply may be a low voltage power supply provided by an AC power supply via a switching power supply.

[0013] The advantages of the present invention are: The method for heating railway rails of the present invention utilizes low voltage and high current to heat the electric heating film, which covers the railway rails to be heated, thereby solving the problems of uneven heating or complicated operation in the existing heating method. The heating method is easy to operate, the heating circuit is simple to build, and the equipment cost is low. The input power supply, electric heating film, wires, etc. are easy to disassemble and carry.

[0014] The present invention is a method for heating railway rails. The implementation of this method requires a set of heating devices, namely, an input power supply (AC power supply), a rectifier module, a filter module, a control module and an electric heating film group form a loop. A common AC power supply is used to provide AC power to the rectifier module, and the output DC power is supplied to the electric heating film through the filter module for heating. The electric heating film is covered on the railway rails to be heated. The use of low voltage and high current can ensure the personal safety of on-site construction personnel in electricity use.

[0015] The present invention adopts a method for indirect heating of railway rails. The interior of the railway rails has a certain internal resistance. The railway rails are used as a heat receiving body, a large current is applied to the electric heating film, and the railway rails are heated by the hot compress effect, thereby shortening the heating time and reducing the damage to the railway rail body. A temperature control unit in a control module is used to collect the temperature of the railway rails during the heating process in real time, so that on-site operators can check the real-time temperature of the heated rails. After the temperature control unit sets the target temperature, the actual temperature is compared in real time. When the surface temperature of the heated rails reaches the set target temperature, the rectifier module automatically stops working. When the surface temperature of the heated rails does not reach the set target temperature, the rectifier module continues to heat, thereby realizing temperature comparison for work feedback.

[0016] The present invention will be further described below in conjunction with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the railway rail heating implemented by the present invention; Figure 2 It is a schematic diagram of a railway rail heating temperature control unit implemented in the present invention. DETAILED DESCRIPTION

[0018] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and examples, so as to fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects and implement them accordingly. Example 1

[0019] like Figure 1As shown, the present invention relates to a method for heating railway rails, which is characterized by comprising a power supply 1, a control circuit 2 and an electric heating film 3, wherein the electric heating film 3 is fixed on both sides of the railway rail 5 through a fixing frame 4, the electric heating film 3 is electrically connected to the power supply 1 through the control circuit 2, the control circuit 2 at least comprises a temperature sensor 6, a current transformer 7 and an input / output interface circuit 8 electrically connected to the interface, and a command is input to the control circuit 2 through the input / output interface circuit 8. After the control circuit 2 receives the command to heat the railway rail 5, the control switch 9 is turned on to connect the power supply 1 and the electric heating film 3, and the railway rail 5 is heated through the electric heating film 3. The control circuit 2 detects the temperature of the temperature sensor 6 and the current of the current transformer 7, so that the current flowing to the electric heating film 3 and the detected temperature are within a set range; the temperature sensor 6 is a thermocouple, which is distributed on both sides of the railway rail 5 and is wrapped by the electric heating film 3 and the railway rail 5. The fixing frame 4 is a metal alloy elastic frame. The switch 9 is a bidirectional thyristor, and the heating temperature is adjusted by the duty cycle of the bidirectional thyristor; it includes at least one leakage protector 10, which is electrically connected to the railway rail 5 and the grounding connection line. When there is leakage current between the railway rail 5 and the grounding connection line, the electrical circuit between the power supply 1 and the electric heating film 3 is disconnected. Example 2

[0020] like Figure 2 As shown, the present invention relates to a method for heating railway rails, which is characterized by comprising a power supply 1, a control circuit 2 and an electric heating film 3, wherein the electric heating film 3 is fixed on both sides of the railway rail 5 through a fixing frame 4, the electric heating film 3 is electrically connected to the power supply 1 through the control circuit 2, the control circuit 2 at least comprises a temperature sensor 6, a current transformer 7 and an input / output interface circuit 8 electrically connected to the interface, and a command is input to the control circuit 2 through the input / output interface circuit 8. After the control circuit 2 receives the command to heat the railway rail 5, the control switch 9 is turned on to connect the power supply 1 and the electric heating film 3, and the railway rail 5 is heated through the electric heating film 3. The control circuit 2 detects the temperature of the temperature sensor 6 and the current of the current transformer 7, so that the current flowing to the electric heating film 3 and the detected temperature are within a set range; the temperature sensor 6 is a thermocouple, which is distributed on both sides of the railway rail 5 and is wrapped by the electric heating film 3 and the railway rail 5. The fixing frame 4 is a metal alloy elastic frame. The switch 9 is a bidirectional thyristor, and the heating temperature is adjusted by the duty cycle of the bidirectional thyristor; the control circuit 2 is supplied by a DC power supply 11, and the DC power supply 11 is supplied with a voltage of 5V by a switching power supply via a power supply 1. The power supply 1 is a low-voltage power supply provided by an AC power supply via a switching power supply. Example 3

[0021] The fixing frame 4 of the third embodiment, which is different from the first and second embodiments, is a stainless steel elastic frame.

[0022] In order to make the low voltage and high current output of railway rail heating stable and continuously adjustable, the duty cycle needs to be adjusted and the PWM control principle is used for adjustment.

[0023] The hardware control part itself forms a closed-loop control circuit to adjust the voltage to keep it constant within the accuracy range.

[0024] The design of the railway rail heating described in the present invention is based on the following formula: Set the total energy of railway rail Q Q=C•M•L•T_∆ Where: specific heat capacity of rail C, weight of rail M, length of rail L, temperature difference of rail , The equivalent resistance R of the railway rail R = L / (πr^2 σ) Where: equivalent radius r of railway rail, electrical conductivity of railway rail.

[0025] Rail heating circuit current I I=√(Q / Rt) Where: railway rail heating time t, railway rail resistance R.

[0026] Total energy of railway rail Q Q=C•M•L•T_∆ Where: specific heat capacity of rail C, weight of rail M, length of rail L, temperature difference of rail , The equivalent resistance R of the railway rail R = L / (πr^2 σ) Where: the equivalent radius r of the railway rail, the conductivity of the railway rail;

[0027] Rail heating circuit current I I=√(Q / Rt) Where: railway rail heating time t, railway rail resistance R.

[0028] When the railway rail needs to be heated, the present invention inputs AC power to the electric heating film to form a loop, applies a large current to the electric heating film to make it heat up, and the electric heating film covers the required railway rail heating. After the temperature control unit sets the target temperature, the actual temperature is compared in real time. When the surface temperature of the heated rail reaches the set target temperature, the rectifier module automatically stops working; when the surface temperature of the heated rail does not reach the set target temperature, the rectifier module continues to heat, thereby realizing temperature comparison and working feedback.

Claims

1. A method for heating railway rails, characterized in that: The invention comprises a power supply (1), a control circuit (2) and an electric heating film (3), wherein the electric heating film (3) is fixed to both sides of a railway rail (5) via a fixing frame (4), the electric heating film (3) is electrically connected to the power supply (1) via the control circuit (2), the control circuit (2) at least comprises a temperature sensor (6), a current transformer (7) and an input / output interface circuit (8) electrically connected to the interface, a command is input to the control circuit (2) via the input / output interface circuit (8), and after the control circuit (2) receives the command to heat the railway rail (5), the control switch (9) is turned on to connect the power supply (1) and the electric heating film (3), and the railway rail (5) is heated via the electric heating film (3). The rail (5) is heated on both sides, and the control circuit (2) detects the temperature of the temperature sensor (6) and the current of the current transformer (7), so that the current flowing to the electric heating film (3) and the detected temperature are within a set range; when the railway rail needs to be heated, an AC power supply is input to the electric heating film to form a loop, and a large current is applied to the electric heating film to make it heat up, and the electric heating film covers the required railway rail heating; after the target temperature is set in the temperature control unit, the actual temperature is compared in real time, and when the surface temperature of the heated rail reaches the set target temperature, the work is automatically stopped; when the surface temperature of the heated rail does not reach the set target temperature, the heating is continued, thereby realizing temperature comparison and working feedback.

2. The method for heating a railway rail according to claim 1, characterized in that: The temperature sensor (6) is a thermocouple, which is distributed on both sides of the railway rail (5) and is wrapped by the electric heating film (3) and the railway rail (5).

3. The method for heating a railway rail according to claim 1, characterized in that: The fixing frame (4) is a metal alloy elastic frame.

4. The method for heating a railway rail according to claim 3, characterized in that: The fixing frame (4) is a stainless steel elastic frame.

5. The method for heating a railway rail according to claim 1, characterized in that: The switch (9) is a bidirectional thyristor, and the heating temperature is adjusted by the duty cycle of the bidirectional thyristor.

6. The method for heating a railway rail according to claim 1, characterized in that: The invention comprises a leakage protector (10), which is electrically connected to a railway rail (5) and a grounding connection line. When leakage current occurs between the railway rail (5) and the grounding connection line, the electrical circuit between the power source (1) and the electric heating film (3) is disconnected.

7. The method for heating a railway rail according to claim 1, characterized in that: The control circuit (2) is supplied with a DC power supply (11), and the DC power supply (11) is supplied with a voltage of 5V by a switching power supply via the power supply (1).

8. The method for heating a railway rail according to claim 1, characterized in that: The power supply (1) is a low-voltage power supply provided by an AC power supply via a switching power supply.

9. The method for heating a railway rail according to claim 1, characterized in that: The design of the railway rail heating is based on the following formula: Set the total energy of railway rail Q Q=C•M•L•T_∆ Where: specific heat capacity of rail C, weight of rail M, length of rail L, temperature difference of rail , The equivalent resistance R of the railway rail R = L / (πr^2 σ) Where: equivalent radius r of railway rail, electrical conductivity of railway rail; Rail heating circuit current I I=√(Q / Rt) Where: railway rail heating time t, railway rail resistance R.

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