JP6357666B2 - Rail manufacturing equipment - Google Patents

Description

  The present invention relates to a rail manufacturing apparatus that forcibly cools at least the head of a high-temperature rail having an austenite temperature or higher.

  In general, in the manufacturing process of rails for railroads, etc., after the steel material is heated and hot-rolled to a predetermined shape above the austenite temperature, or after reheating above the austenite temperature, the rail head is required. Forced cooling is performed to ensure desired quality such as hardness. Forced cooling (heat treatment) is performed by injecting a cooling medium (air, water, mist, etc.) onto the rail while controlling the temperature history, and the rail head has a fine pearlite structure to improve wear resistance and toughness. It is possible to obtain a high hardness rail. For example, in rail transport in natural resource mining sites such as coal, the load is heavy compared to passenger cars, etc. Since it is used until the central part (inside) of the part is worn, improvement in wear resistance and toughness of the rail head including the inside is particularly required.

  Here, in order to make the rail head a stable pearlite structure, it is necessary to appropriately increase the cooling rate during forced cooling. However, since the inside of the rail head is cooled by heat conduction after the temperature of the surface (the top surface and the side surface of the head) is lowered, it is difficult to increase the cooling rate of the inside having a long distance from the surface. Therefore, if the surface cooling rate is increased in order to increase the internal cooling rate, a supercooling part is generated on the surface of the rail head, and this supercooling part does not become a uniform pearlite structure, but martensite transforms. Or bainite transformation. Here, bainite has low wear resistance and martensite has low toughness. Therefore, in order to achieve both high wear resistance and high toughness at the same time, especially for the rail head surface, the bainite transformation and martensitic transformation of the rail head are prevented by slow cooling before pearlite transformation. In addition, it is necessary to stably make the entire rail head a pearlite structure.

  Normally, forced cooling of the rail is performed from both sides of the head surface and the back surface of the foot with the rail head upright with the rail head up and the foot down. That is, as described above, the head is cooled in order to ensure the quality of the rail head, and the vertical warping of the rail due to the thermal stress generated due to the temperature difference between the head and the foot is reduced. To prevent this, the foot is cooled. In that case, a technique for reducing the thermal stress generated due to the temperature difference between the head and the foot and the abdomen and suppressing an increase in bending and residual stress is further known. For example, Patent Document 1 discloses a technique for cooling the abdomen surface in addition to the head surface and the foot sole surface. Patent Document 2 discloses a technique for cooling each part by providing a guide so that air (cooling medium) from the head side cooling header for cooling the head side surface flows from the lower jaw surface toward the abdominal surface and the foot part. Is described.

JP 2002-105538 A JP-A-8-295938

  However, in the technique described in Patent Document 1, the abdominal cooling header that cools the abdominal surface has a high cooling efficiency directly under the nozzle, but has a low cooling efficiency with respect to the refracted portion, so the lower surface of the chin cannot be cooled, and the head The effect of increasing the internal cooling rate is small. Further, in the technique described in Patent Document 2, the head side cooling header has a high cooling efficiency with respect to the side of the head that is directly under the nozzle, but the head lower surface and the abdominal surface are only indirectly cooled by a cooling medium, and cooling is performed. Efficiency is low. In addition, in the technique described in Patent Document 2, since the guide is heated by radiation of the lower jaw surface and the abdominal surface, an effect of keeping the rail warm is generated, and the cooling efficiency of the lower jaw surface and the abdominal surface is reduced. The internal cooling rate does not increase and the hardness decreases.

  The present invention has been made in view of the above, and an object thereof is to provide a rail manufacturing apparatus capable of increasing the hardness of the entire rail head including the inside.

In order to solve the above-described problems and achieve the object, the rail manufacturing apparatus according to the present invention is at least the head of a high-temperature rail that is hot-rolled at an austenite temperature or higher or heated to an austenite temperature or higher. A rail manufacturing apparatus for forcibly cooling a head part, the head head cooling head for injecting air as a cooling medium to each of the top surface of the head of the rail, the side of the head, the lower surface of the chin, and the bottom of the foot of the rail foot A side cooling header, a submaxillary cooling header, and a sole cooling header, and the submaxillary cooling header, the parietal cooling header, the head side cooling header, and the sole cooling header are separated from each other and have a gap. is disposed, the outlet of the cooling medium into the gap between the cooling header set only are the submandibular cooling header, the width direction of the rail than the head side of the rail head It characterized that you made are disposed such that the side.

  The rail manufacturing apparatus according to the present invention is characterized in that, in the above invention, the submandibular cooling header injects a cooling medium onto the lower jaw surface of the rail head and the abdominal surface of the rail abdomen.

  According to the present invention, the entire rail head including the inside can be increased in hardness.

FIG. 1 is a schematic diagram showing a main configuration of a manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining a forced cooling portion of the rail by the manufacturing apparatus of the present embodiment. FIG. 3 is a schematic diagram showing a main configuration of a manufacturing apparatus according to another embodiment. FIG. 4 is a schematic diagram showing a main configuration of a manufacturing apparatus according to another embodiment. FIG. 5 is a schematic diagram illustrating a main configuration of a manufacturing apparatus used in Comparative Example 1. FIG. 6 is a schematic diagram illustrating a main configuration of a manufacturing apparatus used in Comparative Example 2. FIG. 7 is a schematic diagram illustrating a main configuration of a manufacturing apparatus used in Comparative Example 3.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. Moreover, in description of drawing, the same code | symbol is attached | subjected and shown to the same part.

  FIG. 1 is a schematic diagram illustrating a configuration example of a main part of a manufacturing apparatus 2 for a rail 1 according to the present embodiment. FIG. 2 is a diagram for explaining a forced cooling portion of the rail 1 by the manufacturing apparatus 2. As shown in FIG. 1, the rail 1 manufacturing apparatus 2 performs forced cooling (hereinafter simply referred to as “cooling”) on a rail 1 having a product cross-sectional shape under predetermined cooling conditions corresponding to required quality such as desired hardness. ) And is installed along with a heating furnace, a rolling mill, and the like along the conveying path of the rail 1 formed by a conveying device or the like in the production line. In the manufacturing apparatus 2, a high-temperature rail 1 that has been hot-rolled at a temperature higher than the austenite temperature in a rolling mill or heated to a temperature higher than the austenite temperature in a heating furnace is carried into a processing position. The manufacturing apparatus 2 forcibly cools the head portion 11 and the foot portion 12 of the loaded rail 1.

  The rail 1 may be cooled by being carried into the manufacturing apparatus 2 with a rolling length of, for example, about 100 m, or may be cut (saw cut) to a length of, for example, about 25 m. There are cases where it is carried into the manufacturing apparatus 2 and cooled later. As a manufacturing apparatus 2 that uses the sawn rail 1 as a cooling target, there is a device in which a cooling zone is divided according to the length after sawing.

  The manufacturing apparatus 2 includes a crown cooling header 21 for cooling the head 11 of the rail 1, a head side cooling header 22, a sub-chin cooling header 23, and a sole cooling for cooling the foot 12 of the rail 1. And a header 24.

  These parietal cooling header 21, head side cooling header 22, sub-chin cooling header 23, and sole cooling header 24 (hereinafter collectively referred to as “cooling headers 21, 22, 23, 24” as appropriate). Each is connected to a cooling medium source via a pipe, and a cooling medium (air, spray water, mist, etc.) is sprayed from a plurality of nozzles (spout ports) (not shown). Specifically, the nozzle of the parietal cooling header 21 is arranged along the longitudinal direction of the rail 1 above the head 11 of the rail 1 at the processing position, and is cooled toward the parietal surface 111 of the head 11 shown in FIG. The medium is ejected (arrow A11 in FIG. 1). Further, the nozzles of the head side cooling header 22 are arranged along the longitudinal direction of the rail 1 on both sides of the rail 1 at the processing position, and jet the cooling medium toward the head side surface 112 of the head 11 shown in FIG. (Arrow A12 in FIG. 1). The nozzles of the submandibular cooling header 23 are arranged along the longitudinal direction of the rail 1 on both sides of the rail 1 at the processing position, and spray the cooling medium toward the lower jaw surface 113 of the head 11 shown in FIG. (Arrow A13 in FIG. 1). Further, the nozzle of the sole cooling header 24 is arranged along the longitudinal direction of the rail 1 below the rail 1 at the processing position, and jets a cooling medium toward the sole 121 of the foot 12 shown in FIG. Arrow A14 in FIG.

  Each of the cooling headers 21, 22, 23, and 24 is configured to be able to adjust the discharge amount, discharge pressure, temperature, and moisture amount of the cooling medium. The adjustment of the discharge amount, discharge pressure, temperature, and moisture amount of these cooling media is for controlling the cooling rate of the front surface of the head 11 and the back surface of the foot 12, for example, the cooling headers 21, 22, 23, In the case of a configuration in which air or spray water is used as the cooling medium 24, it is sufficient that at least any one of the discharge amount, discharge pressure, and temperature of the cooling medium can be adjusted. The cooling headers 21, 22, 23, and 24 are configured to be capable of adjusting at least one of the discharge amount, discharge pressure, temperature, and moisture amount in the case of using mist as the cooling medium. It only has to be.

  Each of the cooling headers 21, 22, 23, and 24 is separated from each other, and a cooling medium discharge port is provided in a gap between the headers. This prevents the cooling medium from staying in each of the cooling headers 21, 22, 23, 24, thereby reducing the cooling efficiency.

  Further, the nozzle of the submandibular cooling header 23 is arranged so as to be inside the width direction of the rail 1 from the head side surface 112 of the rail 1 head 11. This is because when the nozzle of the submandibular cooling header 23 is disposed outside the head side surface 112 of the rail 1 head 11 in the width direction of the rail 1, the cooling medium sprayed from the head side cooling header 22 is applied to the head side surface 112. This is to prevent the momentum of the cooling medium that flows in the direction of the foot 12 after the collision and is sprayed from the submandibular cooling header 23.

  Moreover, the manufacturing apparatus 2 includes a pair of clamps 25 at positions facing each other on both sides of the foot 12 of the rail 1 at the processing position. The clamp 25 clamps the foot 12 of the rail 1 at the processing position on both sides and restrains the displacement of the rail 1 so as not to move in the vertical direction during cooling. The longitudinal direction of the rail 1 at the processing position A plurality of sets are arranged at appropriate positions along the line. For example, the clamps 25 are installed at intervals of approximately 5 m along the longitudinal direction of the rail 1 at the processing position.

  In addition, the manufacturing apparatus 2 is provided above the head 11 of the rail 1, and measures a surface temperature of the head 11 (for example, one location in the top surface 111) and a foot of the rail 1. 12, and a foot thermometer 262 that measures the surface temperature of the foot 12 (for example, one location in the foot back surface 121). These head thermometer 261 and foot thermometer 262 are connected to a control unit (not shown), and output measured values to the control unit as needed.

  In order to make the head 11 of the rail 1 not only the surface but also the inside (center) high hardness having high wear resistance and high toughness, it is important to transform the entire head 11 into pearlite. Therefore, in the process of forced cooling from the start to the end of forced cooling, the control unit keeps or raises the temperature of the head 11 at least during the transformation of the surface of the head 11. Controls the surface cooling rate or heating rate (cooling efficiency). In the present embodiment, the control unit controls the cooling rate or the heating rate of the surface of the head 11 by controlling the ejection of the cooling medium from the cooling headers 21, 22, 23, and 24. Here, the timing of starting the injection of the cooling medium from the nozzles of the cooling headers 21, 22, 23, and 24 may be simultaneously performed or may be shifted from each other as necessary.

  In addition, when the abdominal part 13 of the rail 1 is high temperature, since the cooling rate inside the head 11 falls by heat conduction, it is preferable to cool the abdominal part 13 together with the chin lower surface 113 of the head 11. Therefore, the manufacturing apparatus 2 may be configured to further include an abdomen cooling header 27 for cooling the abdomen 13 of the rail 1 as illustrated in FIG. Or you may comprise so that the submaxillary cooling header 23 may cool the abdominal part 13 of the rail 1 so that it may illustrate in FIG. In this case, the nozzle of the abdomen cooling header 27 or the submaxillary cooling header 23 injects the cooling medium toward the abdomen surface 131 of the abdomen 13 (arrow A15 in FIGS. 3 and 4).

  According to the manufacturing apparatus 2 of the present embodiment configured as described above, the submandibular cooling header 23 cools the chin lower surface 113, so that the cooling rate inside the rail 1 head 11 can be increased. Thereby, the whole rail 1 head 11 including the inside can be made hard.

  In addition, the cooling nozzles 21, 22, 23, 24, and 27 are separated from each other and arranged with a gap, and the cooling medium is discharged from the discharge port provided in each gap. In 23, 24 and 27, it is possible to prevent the cooling medium from staying and the cooling efficiency from being lowered.

  Further, since the nozzle of the submandibular cooling header 23 is disposed on the inner side in the width direction of the rail 1 from the head side surface 112 of the rail 1 head 11, the cooling medium sprayed from the head cooling header 22 is the submandibular cooling header. It is possible to prevent the momentum of the cooling medium ejected from 23 from being hindered.

  Moreover, when the submandibular cooling header 23 or the abdominal part cooling header 27 cools the hot abdominal part 13, it can prevent that the cooling rate inside the head 11 falls by heat conduction.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these, and various modifications according to the specifications and the like are within the scope of the present invention. It is obvious from the above description that various other embodiments are possible within the scope of the above.

(Example)
The rail 1 that has been hot-rolled at 900 ° C. and then sawn to 100 m is carried into various manufacturing apparatuses 2 shown below, restrained by a clamp 25, and forcedly cooled for 180 seconds with air as a cooling medium. It was. The cooling rate during forced cooling is 3 ° C./second on the surface of the head 11 (the top surface 111, the head side surface 112), and 2 ° C./second on the foot back surface 121 of the foot portion 12. The cooling efficiency by the top cooling header 21, the head side cooling header 22, and the sole cooling header 24 was controlled. In addition, the submandibular cooling header 23 and the abdomen cooling header 27 were adjusted to have the same discharge pressure as the head side cooling header 22. After forced cooling, the injection of air from each of the cooling headers 21, 22, 23, 24, 27 was stopped, the rail 1 was removed from the clamp 25, carried out from the manufacturing apparatus 2, and naturally cooled on the cooling floor. And about the rail 1 used as normal temperature, the hardness of 25 mm depth position from the center of the width direction of the parietal surface 111 was measured.

  In Examples 1, 2, and 3, the manufacturing apparatus 2 shown in FIGS. Moreover, in the comparative example 1, as shown in FIG. 5, the conventional manufacturing apparatus 2 which does not have any of the submaxillary cooling header 23 and the abdomen cooling header 27 was used. In Comparative Example 2, as shown in FIG. 6, for example, the conventional manufacturing apparatus 2 described in Patent Document 1 that includes the abdomen cooling header 27 but does not include the submandibular cooling header 23 is used. In Comparative Example 3, as shown in FIG. 7, for example, a conventional manufacturing apparatus 2 described in Patent Document 2 is used, in which a guide 28 is provided to indirectly cool the chin lower surface 113 and the abdominal surface 131.

  Table 1 shows the measurement results of the hardness (Brinell hardness) inside the head 11 of the rail 1 measured in Examples 1 to 3 and Comparative Examples 1 to 3. As shown in Table 1, according to the manufacturing apparatus 2 of Examples 1 to 3, it was found that a Brinell hardness of 370 or more was achieved, and the inside of the rail 1 head 11 was increased in hardness.

DESCRIPTION OF SYMBOLS 1 Rail 11 Head 111 Head top surface 112 Head side surface 113 Jaw lower surface 12 Foot part 121 Foot back surface 13 Abdominal part 131 Abdominal surface 2 Manufacturing apparatus 21 Head top cooling header 22 Head side cooling header 23 Submandibular cooling header 24 Foot cooling header 27 Abdominal cooling header

Claims (2)

A rail manufacturing apparatus that performs forced rolling of at least a head of a high-temperature rail that is hot-rolled at an austenite temperature or higher, or heated to an austenite temperature or higher,
Parietal cooling header, head side cooling header, submaxillary cooling header, and sole cooling header that injects air as a cooling medium to the parietal surface, head lateral surface, chin lower surface of the rail head, and the sole of the foot of the rail foot. With
The submaxillary cooling header, the parietal cooling header, the head side cooling header, and the sole cooling header are separated from each other and arranged with a gap,
Outlet of the cooling medium into the gap between the cooling header set only being,
The submandibular cooling header rail of the manufacturing apparatus characterized that you made are arranged such that the inner side of the width direction of the rail than the head side of the rail head. The rail manufacturing apparatus according to claim 1 , wherein the submandibular cooling header sprays a cooling medium onto the lower jaw surface of the rail head and the abdominal surface of the rail abdomen.

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