EP2573194B1 - Method and device for heat treating rails - Google Patents

Description

Field of engineering

The invention relates to the field of iron metallurgy, in particular to methods for heat treating rails, including railroad tracks.

State of the art

A method for cooling a rail is known (Patent RU 2266966 C21D9 / 04, C21D11 / 00, C21D1 / 02), which comprises passing the heated rail through a cooling section having an inlet and an outlet section, and cooling to forming the microstructure of the rail into a perlite or ferrite-perlite microstructure and characterized in that the rail is passed through a cooling section consisting of individual, independent, in the length of the cooling section successively arranged cooling modules with independently controllable cooling parameters and with intermediate regions which are arranged to receive structural stresses between the cooling modules with Means for determining the actual temperature of the rail head. Depending on the corresponding value of the actual temperature of a component, the parameters of the cooling intensity are controlled in an intermediate region, at least according to the following cooling module, to obtain a predetermined temperature of the rail head during the entire passage of the cooling section, which exceeds the critical temperature for the formation of a bainite structure ,

A disadvantage of this method is the limited range of cooling rate control in the process of cooling down. Furthermore, the temperature reduction on the surface of the rail head reaches during 4-5 s of the cooling process 350 ° C-450 ° C, which may lead to the formation of bainite structures in the microstructure of the surface layers of the rail. As a result, the particular drawback of this process is the large variations in temperature at the surface of the railhead (from 350 ° C to 100 ° C), which can lead to a nonuniform macrostructure.

Another disadvantage is the nonuniformity of the heat treatment in the length of the rail, since in the heat-transfer passage of the heat treatment, while controlling the cooling intensity in the individual independent modules, the various sections of the rail go through different cooling processes.

There is known a method and apparatus for differential hardening by cooling the rail head and foot by compressed air through a system of orifices (nozzles) ( Patent US 4913747 , international class C21D 9/04). This patent was chosen as the closest prior art to the apparatus for heat treatment of rails.

The device consists of:

Loading, unloading and positioning means, a holding device for fixing the rail so that the rail head is arranged above (on the foot), a turbine compressor, a system of air ducts and manifolds with openings (nozzles) for the coolant delivery to the rail, positioning for the upper, lower and side collectors with an air supply pipe part, an air supply control system and a temperature monitoring system.

This method and apparatus enables a heat treatment to be carried out only on rails of alloyed or high-carbon steels (hypereutectoid steels having a carbon content of 0.9 to 1.2% by mass).

The major drawback of the method and apparatus is the small control interval of cooling rates which allows heat treatment of the rails at speeds up to 4.5 ° C / s, since the coolant is air, which does not heat treat carbonaceous, non-alloyed rails Steel allows, as this much higher cooling rates are required (10 ° C / s and more).

A further disadvantage of the device is the use of powerful drives and complex metal structures, since the heat treatment of each rail requires the construction of upper and side headers to be raised and lowered to cool the rails with the air supply duct portion.

Another method for heat treatment of rails is known (Patent RU 2280700 C21B9 / 04), which comprises the continuous cooling of a rail head with controlled after-cooling of rail profile components and is characterized in that the rail is cooled from a rolling heat to a temperature of 820-870 ° C and cooled in two ways: First at the surface the rail head with compressed air for a period of 20-30 s with an air volume of 3000-4000 m ³ / h at an air temperature of 10-25 ° C and a pressure of 0.55 MPa, followed by a cooling of the rail head with a water Air mixture with a quantity of water of 25-30 l / min, a water temperature of 10-30 ° C and a pressure of 0.3-0.4 MPa, simultaneously with a cooling of the rail head is a cooling of the rail foot with the water Air mixture at a water temperature of 10-30 ° C, in an amount of 6-7 l / min and a pressure of 0.08-0.09 MPa.

This method is applicable to the heat treatment of unalloyed carbonaceous (hypoeutectoid) steels but is limited to the heat treatment of hypereutectoid and alloy steels, which is its major drawback.

Other disadvantages of this method include: the sharp change in the cooling rate of the rail after supplying the water-air mixture with a quantity of water of 25-30 I / min on the rail profile, which runs counter to the principle of uniform cooling and to form a nonuniformity of Macro and microstructures can lead. Furthermore, the use of air at the high pressure of 0.55 MPa at said air volumes draws the need to use very powerful compressors and very large pressurized gas container by itself, which makes the device complex and energy consuming.

From the DE 195 03 747 A1 For example, a method and apparatus for cooling hot rolled profiles from the rolling heat is known. The required task quantity of cooling media is determined and calculated using the metrological means in cooperation with a computing unit with the aid of a computer program, wherein the temperature of different profile parts is measured. The cooling capacity of the coolant is changed by adjusting the intensity of the coolant jet. The cooling of the different profile parts is controlled in such a way that they convert with the least possible time offset in ferrite and / or pearlite with the release of the heat of transformation.

The WO 2008/077166 A2 describes a method and apparatus for the continuous heat treatment of metallic long products such as profiles, rails, strip material. The long products are transported by way of example by means of an infeed roller table and centering units as well as an optional transverse conveyor. Already in the curing section, the multistage, direct or indirect spray cooling with single-phase media or two-phase media mixtures for targeted cooling of the material surface is used, the intensity of the cooling is changed by angle of attack of the nozzles. The cooling can optionally be combined with heating steps.

The objects of the method according to the invention and the device according to the invention are: the control of the cooling capacity of the gas coolant, both pulse-like and continuous, increasing the range and steplessity of the control of the cooling rate, shortening the duration of the heat treatment of the rails, the possibility of heat treatment of rails of unalloyed and alloyed steels, the achievement of a high hardness along the tread, the improvement of the plasticity and resistance properties of the heat-treated steel, the simplification of the device and the reduction of energy consumption.

• Regeln der Kühlleistung des Gaskühlmittels sowohl impulsartig quasikontinuierlich als auch kontinuierlich nach einem durch ein Programm vorgegebenen Ablauf.
• Durchführen einer Wärmebehandlung von Schienen aus kohlenstoffhaltigen unlegierten (untereutektoiden und übereutektoiden) und legierten Stählen.
• Durchführen einer Abkühlung der Schienen mit Abkühlungsgeschwindigkeiten im Bereich von 2 bis 20°C/s.
• Die Abkühlungsgeschwindigkeiten beim Wärmebehandlungsvorgang in verschiedenen Abkühlungsphasen quasikontinuierlich stufenlos oder scharf zu ändern.
• Den Druck im Gaskühlmittelzufuhrsystem zu senken.
• Durch Intensivierung der Kühlleistung des Gasmittels beim Abkühlungsvorgang eine einheitliche, feindisperse Perlitstruktur (gehärtetes Sorbit) in einer Tiefe von mehr als 22 mm von der Oberfläche zu erzielen.
• An der Lauffläche eine Härte bis zu 401 HB zu erzielen und die Plastizitäts-und Beständigkeitseigenschaften des wärmebehandelten Stahls zu verbessern, indem die Dispersität des Perlits verringert wird.
• Die Gesamtzeit der Wärmebehandlung der Schiene zu verringern, die Vorrichtung zu vereinfachen und den Energiebedarf zu senken.

The technical result is to provide a method and a device which enable:

• Controlling the cooling performance of the gas coolant both pulse-like quasi-continuous and continuously following a predetermined by a program flow.
• Conducting a heat treatment of carbon-containing unalloyed (hypoeutectoid and hypereutectoid) and alloyed steel rails.
• Perform a cooling of the rails with cooling rates in the range of 2 to 20 ° C / s.
• The cooling rates in the heat treatment process in different cooling phases quasi-continuously stepless or sharp change.
• Reduce the pressure in the gas coolant supply system.
• By intensifying the cooling performance of the gas medium during the cooling process, to obtain a uniform, finely dispersed perlite structure (hardened sorbitol) at a depth of more than 22 mm from the surface.
• To achieve a hardness up to 401 HB on the tread and to improve the plasticity and resistance properties of the heat treated steel by reducing the dispersity of the pearlite.
• To reduce the total time of heat treatment of the rail, to simplify the device and to lower the energy requirement.

The technical result is achieved by a method for heat treatment of rails, comprising a continuous cooling of a rail head with a controlled aftercooling of rail profile components, wherein the rail is cooled from a rolling heat first with compressed air and then with a water-air mixture, simultaneously with the cooling of the rail head, the cooling of a rail foot takes place, according to the invention, the cooling of the rail of carbonaceous unalloyed (hypoeutectoid, hypereutectoid) or alloyed steel from the rolling heat and / or after reheating with a temperature not less than the Austenitisierungstemperatur, with a gas medium is performed, wherein the gas medium is an air bath with a controllable during the heat treatment humidity level and pressure, wherein the control of the cooling capacity of the agent by a quasi-continuous pulse injection of the water in the air flow after a predetermined schedule by a program.

Furthermore, the control of the cooling capacity of the agent is carried out continuously according to a predetermined by a program flow.

Further, depending on the chemical composition of the rail steel, the supply of the gas agent is controlled at a consumption of 10 to 60 m ³ / min by a running rail meter, whereby the consumption of the injected water is changed to 12 l / min by running rail meter.

Furthermore, the supply of the gas medium in dependence on the initial temperature of the rail, the humidity and the temperature of the outlet air and the water temperature is controlled.

Furthermore, the water content in the gas medium is up to 0.2 liters of water per cubic meter of air.

Furthermore, the pressure of the gas medium is controlled in the range of 0.005 to 0.1 MPa.

Furthermore, the cooling rate is controlled in the range of 2 to 20 ° C / s.

The technical result of the method for heat treatment of rails is performed by an apparatus comprising: loading, unloading and positioning means, a rail mounting fixture, a turbine compressor, a system of air ducts and manifolds with nozzle openings for conveying coolant to the rail profile components, positioning means for air ducts and collectors with nozzle openings, a coolant control system and a temperature monitoring system, characterized in that the loading, unloading and positioning, the rail mounting support with a possibility of arranging the rail in the "head down" position are executed, in addition a system is provided for quasi-continuous pulse injection of the water into the gas stream, comprising: a water tank, a water pipe system, water flow and pressure regulators, control valves valves, controlled control valves, impulse injectors, and a control system enabling the quasi-continuous impulse injection of the water according to a program predetermined procedure.

Furthermore, the water injection is carried out continuously according to a predetermined by a program sequence.

Furthermore, the consumption and the pressure of the gas refrigerant and the injected water are regulated according to a predetermined by a program flow.

Further, the control system determines the rail temperature, the temperature and the humidity of the original gas, and the water temperature, and the cooling down process is corrected based on the obtained data.

Furthermore, the device is equipped with displacement mechanisms for moving the rails and / or the collector with respect to the vertical and / or the horizontal axis.

Furthermore, rails with different profiles are cooled by varying the distance from rail profile components to nozzle openings.

Furthermore, the control system monitors the pressure and the consumption of the gas medium and determines the operating mode of the turbine compressor.

Brief description of the drawings

Fig. 1:

Beispiel eines Injektorsteuerungsdiagramms.

Fig. 2:

Grundschema der Wärmebehandlungsvorrichtung.

Fig. 3:

Grundschema der Wärmebehandlungsvorrichtung mit Angabe der überwachten technischen Parameter.

Fig. 4:

Beispiel der Vorrichtung zur Wärmebehandlung von Schienen. Gesamtansicht.

The practice of the invention is illustrated by the drawings below.

Fig. 1:

Example of an injector control diagram.

Fig. 2:

Basic scheme of the heat treatment device.

3:

Basic diagram of the heat treatment device with indication of the monitored technical parameters.

4:

Example of the device for heat treatment of rails. Overall view.

Implementation of the invention

In the process of heat treatment of rails is in the initial phase of cooling for a period of 1 to 90 s. the temperature of the surface of the rail head steplessly lowered to the minimum resistance temperature of austenite in a perlite transformation, this duration does not exceed the length of the incubation time. Subsequently, in the second phase, the cooling rate required to form a finely dispersed perlite structure in the surface layer is set, and a cooling rate is set at which the formation of a finely dispersed perlite structure corresponding to progress of pearlite transformation in the depth of the rail head is enabled.

The cooling is carried out in the heat treatment process by the gas refrigerant with the controllable cooling capacity. By injecting water into the air stream and changing the gas medium pressure, the cooling capacity of the gas medium is controlled, whereby the predetermined cooling rate of the rail is achieved. The water injection is carried out in a pulse-like, quasi-continuous sequence with change of the pulse length of 20 to 10000 ms and more and with a pulse ratio of 1 to 10,000.

wobei

• T_Pause die Pause zwischen den Impulsen ist;
• T_Impuls die Impulslänge ist.

The pulse ratio is the ratio of the sum of the length of the pause between the pulses and the pulse length to the pulse length. $$\mathrm{Q}=\left({\mathrm{T}}_{\mathrm{Break}}+{\mathrm{T}}_{\mathrm{pulse}}\right)/{\mathrm{T}}_{\mathrm{pulse}.}\mathrm{in\; which}$$

in which

• T _{break is} the break between the pulses;
• T _{pulse is} the pulse length.

An example of an injector control diagram is in Fig. 1 shown.

The pulse-like water supply and the fast air outlet in the device produce a uniform gas coolant with controllable cooling power, which allows a change in the cooling rate of the rail in the range of 2 to 20 ° C / s. The temperature of the injected water can be changed in the range of 10 to 45 ° C.

The temperature of the outlet air can be changed in the range of minus 30 ° C to plus 50 ° C and the humidity in the range of 40 to 100%. At a minimum moisture content of 10 g / m ³ , at 1 pulse of 50 ms, 0.008 g / m ^{3 of} water is added, ie less than 0.1%. At a maximum moisture content of 200 g / m ³ , with 1 pulse of 1000 ms, 3.33 g of water is added, ie less than 1.7%. With a pulse for the injection of water into the air stream, 0.008 to 3.33 g / m ^{3 is} supplied, resulting in a stepless, quasi-continuous change in the moisture content in the air (less than 1.7%), thereby the steplessity of the change reached the cooling rate.

Table 1 shows the experimentally obtained data on the dependence of the cooling rate of the rail head on the pressure of the gas medium. Table 1 Data on the dependence of the cooling rate of the rail head on the pressure of the gas medium Coolant / pressure in the collectors gas resources Pressure 0.005 MPa Pressure 0.015 MPa Pressure 0.025 MPa Pressure 0.04 MPa Pressure 0.05 MPa Pressure 0.1 MPa Initial cooling rate, ° C / s 2.0 4.34 4.55 4.82 4.91 4.99 The pressure of the gas refrigerant is determined according to the chemical composition of the rail steel in the range of 0.005 to 0.1 MPa.

With an increase of the air pressure to more than 0.1 MPa cooling rate does not increase significantly, a further increase is not economically useful.

The lower portion of the cooling rate of 2 ° C / s is achieved by the supply of the gas medium with a pressure of 0.005 MPa without injection of water.

Table 2 shows the experimentally obtained data on the dependence of the cooling rate of the rail head on the air consumption and the injected water quantity. Table 2 Dependence of the cooling rate on the gas medium pressure and the injected water quantity Gas medium pressure, MPa 0.005 0,015 0,025 0.04 0.05 0.1 Gas consumption, m ³ / min to 1 Ifd. Schienenm. 8th 20.0 35.0 45.0 50.0 60.0 Water consumption, I / min to 1 Ifd. rail yards --- 0.2-4.0 0.35 to 7.0 0.45 to 9.0 0.5-10.0 0.6 to 12.0 Cooling rate, ° C / s 2 4.5 to 10.0 4.7 to 15.0 4.9 to 17.0 5.6 to 18.0 6.0 to 20.0

Rails from a rolling heat or reheating are cooled by differentiated supply of the gas medium to various rail profile components up to an austenitizing temperature: on the running surface of the rail head, the side surfaces of the rail head and the rail foot.

The heat treatment operations are set on the basis of the experimental data according to the chemical composition of the rail steel, the required physical-mechanical properties, the initial temperature of the rail before cooling, the temperature and the humidity of the starting gas medium and the water temperature by a program.

It is selected to achieve the least possible bending of the rail required sequence of cooling the rail foot, depending on the expiration of the cooling of the rail head.

The cooling is carried out to a temperature of 150 to 500 ° C, depending on the chemical composition of the rail steel.

1.

Schiene

2.

Unterer Sammler in Form eines Behälters mit Düsenöffnungen zur Abkühlung der Lauffläche des Schienenkopfes

3.

Seitliche Sammler in Form von Behältern mit Düsenöffnungen zur Abkühlung der Seitenflächen des Schienenkopfes

4.

Oberer Sammler in Form eines Behälters mit Düsenöffnungen zur Abkühlung des Schienenfußes

5.

Turbinenkompressor

6.

Druckminderungsventil zum Aufrechterhalten des vorgegebenen Drucks des Gasmittels oder des Wassers

7.

Drucksensoren

8.

Regelungsventile zum Regeln des Verbrauchs an Wasser oder Gasmittel

9.

Injektor

10.

Wasserzufuhrvorrichtung

11.

Behälter mit Wasser

12.

Steuerungssystem

13.

Positionier- und Halteeinrichtung

14.

Luftvorbereitungssystem

15.

Filtersystem

16.

Wasserleitung

17.

Gasmittelleitung

I

Abkühlungsbereich der Lauffläche des Schienenkopfes (LFS)

II

Abkühlungsbereich der Seitenflächen des Schienenkopfes

III

Abkühlungsbereich der Fläche des Schienenfußes

This method of heat treatment of rails is carried out with a device whose basic scheme in Fig. 2 is shown, wherein are shown:

1.

rail

Second

Lower collector in the form of a container with nozzle openings for cooling the running surface of the rail head

Third

Side collectors in the form of containers with nozzle openings for cooling the side surfaces of the rail head

4th

Upper collector in the form of a container with nozzle openings for cooling the rail foot

5th

turbine compressor

6th

Pressure reducing valve for maintaining the predetermined pressure of the gas or the water

7th

pressure sensors

8th.

Control valves for controlling the consumption of water or gas

9th

injector

10th

Water supply device

11th

Container with water

12th

control system

13th

Positioning and holding device

14th

Air preparation system

15th

filter system

16th

water pipe

17th

Gas medium line

I

Cooling area of the tread of the rail head (LFS)

II

Cooling area of the side surfaces of the rail head

III

Cooling area of the surface of the rail foot

18

- Gasmitteldruck

19

- Wasserdruck

20

- Gasmittelverbrauch

21

- Wasserverbrauch

22

- Gasmitteltemperatur

23

- Wassertemperatur

24

- Schienentemperatur

25

- Gasmittelfeuchtigkeit

In Fig. 3 the basic scheme of the heat treatment apparatus is shown by indicating the monitored technical parameters, wherein is shown:

18

- Gas medium pressure

19

- water pressure

20

- Gas consumption

21

- Water consumption

22

- Gas temperature

23

- water temperature

24

- Rail temperature

25

- Gas humidity

26

- Greifeinrichtung

27

- Beschickungseinrichtung

28

- Entnahmeeinrichtung

13

- Halteeinrichtung zur Schienenbefestigung

29

- Positioniereinrichtung für den oberen Sammler

30

- Positioniereinrichtung für den unteren und die seitlichen Sammler

31

- Schienenaufnahmerollgang

32

- Schienenabgaberollgang

In Fig. 4 an example of a device for heat treatment of rails is shown in the overall view, wherein is shown:

26

- Gripping device

27

- Feeding device

28

- Removal device

13

- Holding device for rail fastening

29

- Positioning device for the upper collector

30

- Positioning device for the lower and side collectors

31

- Rail receiving gangway

32

- Rail unloading gangway

This process is carried out in the apparatus described as follows:

After the rail has reached a lateral position from the rolling heat or rewarming, the gripping device 26 (FIG. Fig. 4 ) on the take-up wheel 31 ( Fig. 4 ). The loading device 27 places the rail in the positioning and holding device 13, wherein the positioning of the upper collector 29 lifts the upper collector. After mounting the rail in the "head down" position, the upper collector is lowered and cooling of the rail is performed.

When converting to different types of rails, the lower collector positioner 30 and the side collector control the distance from the surface of the rail head to the collectors.

The air entering the gas compression system passes through a filter system 15 (FIG. Fig. 2 ) and an air preparation system 14 for preventing the influence of seasonal fluctuations in the temperature of the output air.

Furthermore, the air from the turbine compressor 5 (FIG. Fig. 2 ) is supplied through the pressure reducing valve 6 and the control valves 8 in the collector 2, 3, 4. The control system 12 regulates the pressure and the consumption of the gas medium with the aid of the valves 6 and 8.

Water from the container 11 or from any other source is directed by means of the water supply device 10 through the control valves 8 to the injectors 9. By the water injection by means of the injectors 9 in the gas flow, the cooling capacity of the gas medium is changed.

Subsequently, the gas is supplied to the headers 2, 3, 4 and directed into the rail surface cooling sections I, II and III. In this case, the control system 12 automatically gives the operating mode of the valves 8 so that the injectors 9 in pulse-like quasi-continuous and / or continuous operation, whereby the change in the cooling capacity of the gas medium is infinitely variable.

The control system 12 ( Fig. 2 ) controls the heat treatment of the rail after correcting the process according to the monitored parameters 18-25 (FIG. Fig. 3 ).

After completion of the cooling process, the positioning of the upper collector 29 ( Fig. 4 ) is lifted to the upper position, the removal device 28 moves the rail on the discharge roller 32nd

The experiments were carried out at the in Fig. 2 . Fig. 3 and Fig. 4 cooling device performed on solid profile samples of an R65 rail with a length of 1200 mm. The samples were taken from steels having the chemical compositions listed in Table 3. Table 3: Chemical composition of rail steel samples No. C Mn Si P S al V Cr Ni Cu Ti Not a word N 1 0.78 0.97 0.37 0,010 0.009 0,004 0.056 0.277 0.115 0.009 <0.005 2 0.76 0.95 0.37 0,012 0.005 0.005 0,052 0.037 0,107 0,013 0.0034 <0.005 0.0086

According to the results of the experiments, each cured sample was subjected to laboratory tests. The study examined the hardness, the microstructure and the physical-mechanical properties of the rail.

Table 1 shows the experimental data on the dependence of the cooling rate of the rail on the pressure of the gas medium.

Table 2 shows the experimental data on the dependence of the cooling rate of the rail on the air pressure and the injected water quantity.

From Table 1 and Table 2, the technical parameters and the cooling rate intervals were selected for track specimens of chromium alloy steel having chemical composition No. 1 and carbon steel No. 2 of Table 3.

The data on the technical heat treatment parameters of the samples of the steel R65 rails having the chemical composition No. 1 and No. 2 of Table 3 and the results of the physical-mechanical experiments and microstructure studies are shown in Table 4 and Table 5. Table 4: Technical heat treatment parameters of the samples of steel R65 rails with the chemical composition no. 1 from Table 3 and the results of the physical-mechanical tests and investigations of the microstructure Ser. No. Gas medium pressure, MPa Gas consumption, m ³ / min to 1 Ifd. Schienenm. Water consumption, l / min to 1 Ifd. Schienenm. Cooling rate, ° C / s Cooling time, s Microstructure d. hardened rail head Hardness d. Rail cross-section, HB σ _B , N / mm ² LFS 10 mm 22 mm 1 0,025 30 0.35 4.7 150 Hardened sorbitol 363 351 331 1210 2 0,025 30 0.45 4.8 140 Hardened sorbitol 375 363 341 1280 3 0,025 30 0.55 5.0 120 Hardened sorbitol 388 375 363 1320 4 0,025 35 0.65 5.1 110 Hardened sorbitol 401 388 378 1350 nearest prior art of the process Heat treatment of rails with this chemical composition is not possible Table 5: Technical heat treatment parameters of the samples of steel R65 rails with the chemical composition no. 2 from Table 3 and the results of the physical-mechanical tests and investigations of the microstructure Ser. No. Gas medium pressure, MPa Gas consumption, m ³ / min to 1 Ifd. Schienenm. Water consumption, l / min to 1 Ifd. Schienenm. Cooling rate, ° C / s Cooling time, s Microstructure d. hardened rail head Hardness d. Rail cross-section, HB σ _B , N / mm ² δ% Ψ% LFS 10 mm 22 mm 1 0.04 45 2.5 8.3 90 Hardened sorbitol 363 351 330 1250 12 43 2 0.04 45 5 10.4 80 Hardened sorbitol 375 363 345 1290 12 40 3 0.04 45 7 13.1 70 Hardened sorbitol 390 383 375 1350 13 38 4 0.04 45 12 14.9 60 Hardened sorbitol 401 395 388 1380 14 37 5 0.04 45 13 15.3 60 Hardened sorbitol + bainite 415 400 388 1410 10 32 nearest prior art of the process 0.55 44.5 20 140 Hardened sorbitol 388 388 375 1340 12 34

As a result, the method according to the invention makes it possible to carry out a heat treatment of rails of both alloyed and unalloyed (carbon-containing hypoeutectoid and hypereutectoid) steels at different predetermined cooling sequences.

The method and apparatus for heat treatment of rails enable the achievement of a structure of fine-grained hardened sorbitol at a great depth, the improvement of the physical-mechanical properties of the steel and thereby an increase in the resistance of the rails during operation.

Claims (14)

1. A method for rails heat treating, comprising continuous cooling of a head followed by controlled cooling of rail profile elements, wherein a rail from rolling heat is initially being cooled with compressed air, and then with water-and-air mixture; cooling a rail foot is performed simultaneously with cooling a rail head, characterized in that the cooling of a rail made of hypoeutectoid non-alloyed carbon steel, hypereutectoid non-alloyed carbon steel or alloyed steel, from rolling and/or repeated heat, begins at temperature no lower than austenization temperature, using a gas medium being an air medium with controlled air humidity change and pressure being controlled during the heat treating process; wherein the water-and-air mixture is prepared by pulse quasicontinuous water injection into air flow according to a programmed regime with a pulse length change within the range from 20 to 10 000 ms and a pulse ratio from 1 to 10 000, wherein the ratio is a relation of the sum of a pause time between pulses and a pulse duration to the pulse duration; thereby controlling the cooling ability of the gas medium.
2. The method according to claim 1, characterized in that the pulse length is within the range from 50 to 1000 ms, and one water injection pulse injects from 0.008 to 3.33 g/m³ of water into the air flow resulting in a smooth, quasicontinuous change of air humidity less than 1.7%.
3. The method according to Claim 1 or 2, characterized in that gas medium feeding is regulated depending on chemical composition of rail steel at a flow rate of 10÷60 m³/min per running meter of a rail; wherein the flow rate of the water being injected is changed up to 12 l/min per one running meter of a rail.
4. The method according to claim 1 or 2, characterized in that gas medium feeding is regulated depending on initial rail temperature, humidity and temperature values of initial air and water temperature.
5. The method according to claim 1 or 2, characterized in that water content in the gas medium is up to 0.2 liter of water per one cubic meter of air.
6. The method according to claim 1 or 2, characterized in that gas medium pressure is regulated within the range of 0.005÷0.1 MPa.
7. The method according to claims 1 or 2, characterized in that cooling rate is regulated within the temperature range of 2÷ 20°C/s.
8. A device for embodiment of the method according to Claims 1-7, comprising mechanisms of charging, discharging, positioning and fixation of a rail, a turbo-compressor, a system of air-ducts and chambers with nozzle orifices for feeding of cooling medium to rail profile elements, positioning mechanisms for air pipework and chambers with nozzle orifices, a system of cooling medium feeding control, a temperature control system, where the cooling medium is an air or water-and-air mixture, characterized in that the mechanisms of charging, discharging, positioning and fixation of a rail set it up in head-down position, and a system for air medium preparation is further integrated that is configured to provide pulse quasicontinuous injection of water into gas flow and comprises a water tank, a water pipework, water flow rate and pressure regulators, controlled valves, controlled regulating valves, pulse injectors as well as a control system that allows water injecting in pulse quasicontinuous mode on a programmed regime with change of pulses duration within the range from 20 to 10 000 ms and pulse ratio within the range from 1 to 10 000, wherein the pulse ratio is a relation of sum of a pause time between pulses and pulse duration to pulse duration, thereby controlling the gas medium cooling ability.
9. The device according to claim 8, characterized in that the pulse lengths are within the range from 50 to 1000 ms, and one water injection pulse injects water into air flow in a volume from 0.008 to 3.33 g/m³, resulting in the smooth quasicontinuous change of air humidity less than 1.7%.
10. The device according to claims 8 or 9, characterized in that the flow rate and pressure of the gas medium and the water being injected are regulated according to the programmed regime.
11. The device according to claims 8 or 9, characterized in that the control system determines temperature of the rail, initial temperature and humidity of the gas medium, and temperature of water, and adjusts the cooling mode based on the obtained data.
12. The device according to claims 8 or 9, characterized in that the device is provided with mechanisms for moving the rails and/or chambers relative to the vertical and/or horizontal axis.
13. The device according to claims 8 or 9, characterized in that cooling of rails of different profiles is performed by means of change the distance from surface of rail profile elements to the nozzle orifices.
14. The device according to claims 8 or 9, characterized in that the control system checks the pressure and flow rate of the gas medium, and assigns an operating mode of the turbo-compressor.

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