POST-WELD HEAT TREATMENT DEVICE

Abstract

Provided is a post weld heat treatment apparatus for performing heat treatment on a welded rail, the post-heat treatment apparatus comprising: an induction heating coil that covers the entire periphery of the rail; and a magnetic body that is disposed so as to cover the inner surface of the induction heating coil at a portion of the rail corresponding to a heating suppression location where heating is required to be suppressed.

Description

1 / 27 POST-WELD HEAT TREATMENT DEVICE TECHNICAL FIELD

[001] The present invention relates to a post-weld heat treatment device for welded rails. PRECEDENT TECHNIQUE

[002] It is known to perform post-weld heat treatment after welding rail joints for the purpose, for example, of reducing residual stress in the rails.

[003] As a document describing post-weld heat treatment, as mentioned above, for example, Patent Literature 1 is known. Patent Literature 1 describes a post-weld heat treatment device positioned at a distance of 20 mm or more and 300 mm or less from the welding center of a rail in the longitudinal direction and includes an induction heating coil that heats at least the web part of the rail.

[004] In addition, as a related technique, for example, Patent Literature 2 is known. Patent Literature 2 describes a post-weld heat treatment device that detects and reheats the welded joint of rails connected by welding and removes residual stress in the welded joint. LIST OF QUOTES Patent Literature Patent Literature 1: Japanese Patent Publication JP 5477452 Patent Literature 2: document WO 2018 / 020872 SUMMARY OF THE INVENTION Technical Problem

[005] However, even employing the techniques described in In Patent Literature 1 and Patent Literature 2, it has been difficult to obtain rails that satisfy properties such as wear resistance and fracture resistance. Petition 870250080298, dated 08 / 09 / 2025, page 10 / 56 2 / 27

[006] Thus, the present invention aims to solve the task of obtaining rails that satisfy various required properties, such as the aforementioned wear resistance and fracture resistance. Solution to the Problem

[007] In devising the aforementioned task, the present inventors discovered that by conferring the necessary properties to each part of a rail, it is possible to manufacture rails that maintain high levels of properties, such as wear resistance and fracture resistance. Specifically, for example, wear resistance or similar is conferred to a rail head. In addition, fracture resistance or similar is conferred to a rail web. Furthermore, fracture resistance or similar is conferred to a rail foot. For example, by conferring at least some of the aforementioned properties to each part, it becomes possible to create a rail with more suitable properties.

[008] However, it is difficult to impart the aforementioned properties to each part using a known technique. Consequently, as a result of investigations, the present inventors have discovered that applying appropriate heating to each part, through the following configuration, allows imparting suitable properties to each part.

[009] To be specific, a post-weld heat treatment device, as an aspect of the present invention, is a post-weld heat treatment device that performs heat treatment on a welded rail and includes: an induction heating coil that covers the entire periphery of the rail; and a magnetic body arranged so as to cover an inner surface of the induction heating coil in a portion that corresponds to a heat suppression location of the rail, where heat suppression is required. Petition 870250080298, dated 08 / 09 / 2025, page 11 / 56 3 / 27 Advantageous Effects of the Invention

[0010] With the configurations described above, the present invention can allow adequate heating in a rail after welding and properly impart the necessary properties to the rail. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a diagram showing an example of a configuration of a post-weld heat treatment device in a first exemplary embodiment of the present invention.

[0012] Figure 2 is a diagram to describe an example of the parts that make up a rail.

[0013] Figure 3 is a diagram to describe an example of a part of a bill of exchange.

[0014] Figure 4 is a diagram to describe an example of a distance.

[0015] Figure 5 is a diagram showing an example of a post-weld heat treatment device configuration.

[0016] Figure 6 is a diagram showing an experimental example and a comparative example.

[0017] Figure 7 is a diagram showing an example of a graph summarizing the experimental example shown in Figure 6, and so on.

[0018] Figure 8 is a diagram showing an experimental example and a comparative example.

[0019] Figure 9 is a diagram showing an example of a graph summarizing the experimental example shown in Figure 8, and so on.

[0020] Figure 10 is a diagram showing an experimental example.

[0021] Figure 11 is a diagram showing an example with Petition 870250080298, dated 08 / 09 / 2025, page 12 / 56 4 / 27 comparative. DESCRIPTION OF EXEMPLARY MODALITIES First Exemplary Modality

[0022] In a first exemplary embodiment of the present invention, as illustrated in Figure 1, a post-welding heat treatment device 100 will be described that performs heat treatment on a welded rail 200, thereby reducing the residual stress present in the welded joint of the rail 200 and in the periphery of the welded joint. As illustrated in Figure 1, the post-welding heat treatment device 100 has an induction heating coil 110 that covers the entire periphery of the rail 200. In addition, a magnetic body for flux shielding and a magnetic body for flux concentration are positioned at predetermined locations on the induction heating coil 110.

[0023] As illustrated in Figure 2, rail 200 is composed of a head section 210 located above and in contact with a wheel and similar components when rail 200 is installed, a foot section located below and in contact with a sleeper and similar components, and a web section 220 that connects the head section 210 and the foot section. Furthermore, the foot section is composed of a base section 230, a tip section 240, and a end section 250. Additionally, as illustrated in Figure 3, the head section 210 can be further divided into an upper head section 211, which is located higher up and is a flat portion, side head sections 212 and 213 located on the side faces, and corner sections 214 and 215 that connect the upper head section 211 with the side head sections 212 and 213.

[0024] In designing the aforementioned task, the present inventors discovered that conferring the necessary properties to the respective parts of track 200 in a distributed manner makes it possible to manufacture the track. Petition 870250080298, dated 09 / 08 / 2025, p. 13 / 56 5 / 27 200 with high levels of properties, such as wear resistance and fracture resistance. To be specific, for example, wear resistance and so on are conferred to the billet part 210. In addition, fracture resistance and so on are conferred to the web part 220. Furthermore, fracture resistance and so on are conferred to the foot part, including the base part 230 and the end parts 240 and 250. For example, by conferring at least some of the properties described above to the respective parts, it is possible to enable the rail 200 to have more appropriate properties.

[0025] Furthermore, as a result of the analysis, the present inventors have found that heating under suitable conditions for the respective parts makes it possible to confer appropriate properties to the respective parts, as described above.To be specific, for example, to impart fracture resistance to the 220 web section, it is necessary to ensure a reduction in residual stress and avoid excessive softening. Therefore, during heating, it is desirable to heat to approximately 600 to 700 °C. Furthermore, to ensure the reduction of residual stress to a minimum and also ensure the wear resistance of the 210 foot section, it is desirable to heat to around 250 to 600 °C. Additionally, for the foot section, including the 230 base section and the 240 and 250 tip sections, in order to impart residual stress and inhibit plastic deformation due to wheel load, it is necessary to avoid a decrease in fracture resistance while ensuring the reduction of residual stress to a minimum. Therefore, during heating, it is desirable to heat to around 250 to 650 °C.For example, as described above, heating to temperatures suitable for the respective parts allows the appropriate properties to be imparted to those parts. Furthermore, according to the conditions described above, it can be observed that the heating of the part... Petition 870250080298, dated 09 / 08 / 2025, p. 14 / 56 6 / 27 of the 210 rail and the slip section is preferably more inhibited than the heating of the 220 web section. In other words, when heating the 220 web section to a target temperature of 600 to 700°C, it is desirable that the 210 rail and the slip section are not excessively heated. Thus, from the point of view of the required properties, it can be concluded that, in track 200, the 220 web section is a location that requires heating, while the 210 rail and the slip section are locations that suppress heating.

[0026] Next, an example of a configuration of the post-weld heat treatment device 100 that has a configuration to allow the aforementioned heating condition will be described in more detail. In the following description, as illustrated in Figure 4, a distance h, which is the shortest distance between the corner part 214 of the billet part 210 and the induction heating coil 110, is used as a representative of the distance between the billet part 210 and the induction heating coil 110. Furthermore, a distance f, which is the shortest distance between the tip part 240 and the induction heating coil 110, is used as a representative of the distance between the skid part and the induction heating coil 110.As a result of an experiment by the present inventors, it was discovered that when heating is performed using an existing coil without using a magnetic body, the corner parts 214 and 215 of the billet part 210 and the tip parts 240 and 250 are more likely to be heated. Therefore, to more adequately control the heating state, distance h and distance f are used as representative of the distance between the billet part 210 and the induction heating coil 110, and a representative of the distance between the skid part and the induction heating coil 110. Furthermore, a distance n, which is the dis... Petition 870250080298, dated 09 / 08 / 2025, p. 15 / 56 7 / 27 The shortest distance between the most restricted location of the core part 220 and the induction heating coil 110 is employed as representative of the distance between the core part 220 and the induction heating coil 110. It should be noted that, according to the experiment of the present inventors, it has been confirmed that, in a case where a magnetic body for flux shielding is not used, even if the distance between the skid part and the coil, such as the distance f, is greater than or equal to twice the distance in the existing post-weld heat treatment device 100, it is difficult to maintain the temperature of the end parts 240 and 250 at a temperature that corresponds to the required property when the core part 220 is heated to the required temperature. Furthermore, the aforementioned distances are examples, and distances may be determined at locations other than those illustrated above.

[0027] Figure 1 is a front view showing an example of a configuration of the post-welding heat treatment device 100. As shown in Figure 1, the post-welding heat treatment device 100 has the induction heating coil 110 covering the entire periphery of the rail 200. Furthermore, as shown in Figure 1, the first magnetic bodies 120 and 130, which are magnetic bodies for flux shielding, are arranged in predetermined locations facing the billet part 210, which is the heating suppression location of the induction heating coil 110. For example, in the case illustrated in Figure 1, the first magnetic body 120 is arranged in a location facing the corner part 214 of the billet part 210 and the first magnetic body 130 is arranged in a location facing the corner part 215.Furthermore, the second magnetic bodies 140 and 150, which are magnetic bodies for flux shielding, are arranged in predetermined locations facing the skid part, which is the location of the supply. Petition 870250080298, dated 08 / 09 / 2025, page 16 / 56 8 / 27 are heating elements relative to the induction heating coil 110. For example, in the case illustrated in Figure 1, the second magnetic body 140 is positioned facing the tip part 240 of the slip part, and the second magnetic body 150 is positioned facing the tip part 250. Furthermore, the third magnetic bodies 160 and 170, which are magnetic bodies for flux concentration, are positioned in predetermined locations facing the core part 220, which is a location that needs to be heated by the induction heating coil 110.

[0028] Furthermore, Figure 5 shows an example of the post-weld heat treatment device 100, viewed from the side direction. With reference to Figure 5, the post-weld heat treatment device 100 has, for example, an induction heating coil 110 with the configuration described above positioned to interpose the welded joint of the rail. In other words, the post-weld heat treatment device 100 described in this exemplary embodiment has an induction heating coil 110 on each side of the welded joint of the rail. For example, in the case illustrated in Figure 5, the post-weld heat treatment device 100 has an induction heating coil 110-1 located on the left side of the welded joint of the rail and an induction heating coil 110-2 located on the right side of the welded joint of the rail.For example, induction heating coil 110-1 is arranged so that the distance between the center of the welded rail joint and induction heating coil 110-1 is 50 mm, and induction heating coil 110-2 is arranged so that the distance between the center of the welded rail joint and induction heating coil 110-2 is 50 mm. Furthermore, the post-weld heat treatment device 100 may have a plurality of induction heating coils 110 to interleave the welded joint. Petition 870250080298, dated 09 / 08 / 2025, p. 17 / 56 9 / 27 of the track. Furthermore, the distance between the center of the welded joint of the track and the 110-1 induction heating coil, the 110-2 induction heating coil, and so on, may differ from that illustrated above.

[0029] Furthermore, the induction heating coil 110-1 and the induction heating coil 110-2 are arranged in such a way that, for example, the flowing currents have opposite directions. The induction heating coil 110-1 and the induction heating coil 110-2 can be arranged in such a way that the flowing currents have the same direction. The respective components will be described in more detail below.

[0030] The induction heating coil 110 is a coil that heats the rail 200. For example, the induction heating coil 110 is connected to a high-frequency power supply or similar that provides high-frequency current and heats the rail 200 by receiving high-frequency current from the high-frequency power supply or similar. For example, the induction heating coil 110 may be powered with electrical current at a frequency ranging from 1 kHz to 20 kHz from the high-frequency power supply or similar. The electrical current flowing through the induction heating coil 110 may be different from that illustrated above.

[0031] As described above, the induction heating coil 110 covers the entire periphery of the rail 200 when viewed from the front. For example, the induction heating coil 110 can be divided into two or more coil elements, as shown in Patent Literature 2, and it is possible to cover the entire periphery of the rail 200 by joining the divided coil elements. The induction heating coil 110 can cover the entire periphery of the rail 200 by means of a method different from that illustrated above. Petition 870250080298, dated 08 / 09 / 2025, page 18 / 56 10 / 27

[0032] Furthermore, the induction heating coil 110 can cover the entire perimeter of the rail 200 in such a way that the ratio between the distance between the web part 220 and the induction heating coil 110 and the distance between the head part 210 and the induction heating coil 110 is within a predetermined range. To be specific, the induction heating coil 110 can cover the entire perimeter of the rail 200 in such a way that the value of (distance n) / (distance h) is 0.2 or greater and 1.5 or less. As will be described later, it is possible, by adjusting the distance n and the distance h to achieve the aforementioned value, to heat each part to a more desirable state. That is, by adjusting to the above range, it is possible to heat more appropriately, according to the properties of each part.

[0033] Furthermore, as a result of an experiment conducted by the present inventors, it was confirmed that heating can be carried out more efficiently since the distance between the induction heating coil 110 and the rail 200 is smaller. Therefore, by covering the entire periphery of the rail 200 so that the distance between the web part 220 and the induction heating coil 110 is smaller than the distance between the billet part 210 and the induction heating coil 110, it is possible to obtain more efficient heating of the web part 220. To be specific, from the point of view of more efficient heating of the web part 220, it can also be stated that it is more desirable that the value of (distance n) / (distance h) be greater than or equal to 0.2 and less than 1.

[0034] Furthermore, the induction heating coil 110 can cover the entire perimeter of the rail 200 in such a way that the ratio between the distance between the web part 220 and the induction heating coil 110 and the distance between the foot part and the induction heating coil 110 is within a predetermined range. Petition 870250080298, dated 08 / 09 / 2025, page 19 / 56 11 / 27 To be specific, the 110 induction heating coil can cover the entire periphery of the 200 rail in such a way that the value of (distance n) / (distance f) varies from 0.2 to 2.0. As will be described later, it is possible to achieve the aforementioned value by adjusting the distance n and the distance f to reach the aforementioned value to heat each part to a more desirable state. That is, by adjusting to the above range, it is possible to heat more appropriately according to the properties of each part.

[0035] Furthermore, as in the case of the rail part 210 described above, by covering the entire perimeter of the rail 200 in such a way that the distance between the web part 220 and the induction heating coil 110 is less than the distance between the foot part and the induction heating coil 110, it is possible to obtain more efficient heating of the web part 220. To be specific, from the point of view of more efficient heating of the web part 220, it can also be said that it is more desirable that the value of (distance n) / (distance f) be 0.2 or greater and less than 1.

[0036] As illustrated in Figure 1, in this exemplary embodiment, the induction heating coil 110 does not cover the rail 200 in a shape similar to that of the rail 200, but covers the head 210, the web 220 and the foot 200 of the rail in a substantially rectangular shape, respectively. That is, the induction heating coil 110 has a shape that combines polygonal shapes corresponding to the head 210, the web 220 and the foot, respectively. In other words, the induction heating coil 110 has a shape in which a rectangular shape corresponding to the head 210 and a rectangular shape corresponding to the foot are connected by a linear shape corresponding to the web 220. By covering the rail 200 in this way, it is possible to further ensure the distances between Petition 870250080298, dated 09 / 08 / 2025, p. 20 / 56 12 / 27 between the induction heating coil 110 and the portions corresponding to the R parts of the rail 200, such as the corner parts 214 and 215 and the end parts 240 and 250. However, the induction heating coil 110 may cover the rail 200 in a shape similar to the shape of the rail 200.

[0037] Furthermore, in the case illustrated in Figure 1, the induction heating coil 110 covers the rail 200 in such a way that, from a portion covering the head 210 of the rail 200, a portion located below the head 210 gets closer to the head 210 as it gets closer to the web 220. That is, the shape of the portion below the head 210 of the rectangular shape that corresponds to the head 210 is an inverted V shape when viewed from the front. By forming the induction heating coil 110 below the billet part 210 in an inverted V shape, it is possible to separate the induction heating coil 110 from the side billet parts 212 and 213, from the corner parts 214 and 215, and so on, as much as possible, bringing the induction heating coil 110 as close as possible to the core part 220.Furthermore, in the case illustrated in Figure 1, the induction heating coil 110 is formed in such a way that a portion facing the base part 230 projects towards the rail 200 below the slide part. Similarly, according to the shape described above, it is possible to separate the induction heating coil 110 from the tip parts 240 and 250, while bringing the induction heating coil 110 closer to the base part 230.

[0038] The first magnetic bodies 120 and 130 are magnetic bodies for flux shielding installed in predetermined locations facing the billet part 210. For example, the first magnetic bodies 120 and 130 are arranged in predetermined locations facing the corner parts 214 and 215 of the billet part. Petition 870250080298, dated 08 / 09 / 2025, page 21 / 56 13 / 27 210. For example, the first magnetic bodies 120 and 130 are polyiron cores, metallic silicon plates, or similar. The first magnetic bodies 120 and 130 may be other known magnetic bodies.

[0039] In this exemplary embodiment, the first magnetic bodies 120 and 130 are arranged in predetermined locations of the induction heating coil 110 so as to cover the inner surface of the induction heating coil 110. According to this arrangement, the first magnetic bodies 120 and 130 shield the magnetic flux at the locations of the arrangement, thus suppressing overheating of the rail 200 at these locations. In other words, the first magnetic bodies 120 and 130 are arranged in predetermined locations of the induction heating coil 110 so as to cover at least the inner periphery facing the rail 200.

[0040] It is desirable that the first magnetic bodies 120 and 130 be arranged in the induction heating coil 110 so as to satisfy a predetermined internal surface coverage ratio of the entire internal surface of the induction heating coil 110 facing the billet part 210. To be specific, it is desirable that the first magnetic body 120 be arranged on the internal surface of the induction heating coil 110 such that a coverage ratio C2, which is the ratio of a portion covered by the first magnetic body 120 to the entire portion facing the corner part 214 of the induction heating coil 110, is greater than 0% and equal to or less than 65%. By arranging such a ratio, the first magnetic body 120 can suppress the heating of the billet part 210 more appropriately.Furthermore, it is even more preferable that the first magnetic body 120 be arranged on the inner surface of the induction heating coil 110 in such a way that the ratio. Petition 870250080298, dated 09 / 08 / 2025, p. 22 / 56 14 / 27 of C2 coverage is greater than 0% and equal to or less than 30%. By arranging such a proportion, the first magnetic body 120 can suppress the heating of the billet part 210 even more adequately.

[0041] Similarly, it is desirable that the first magnetic body 130 be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C2, that is, the ratio of a portion covered by the first magnetic body 130 to the whole portion facing the corner part 215 of the induction heating coil 110, is greater than 0% and equal to or less than 65%. By arranging such a ratio, the first magnetic body 130 can suppress the heating of the billet part 210 more appropriately. Furthermore, it is more preferable that it be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C2 is greater than 0% and equal to or less than 30%. By arranging such a ratio, the first magnetic body 130 can suppress the heating of the billet part 210 even more appropriately.

[0042] Provided the arrangement ratio is satisfied, the arrangement locations of the first magnetic bodies 120 and 130 may differ from those illustrated in Figure 1. For example, the arrangement locations of the first magnetic bodies 120 and 130 may be shifted up or down relative to the centers of the corner parts 214 and 215 illustrated in Figure 1, and may cover the top of billet 211 and the side parts of billet 212 and 213.

[0043] The second magnetic bodies 140 and 150 are magnetic bodies for flux shielding installed in predetermined locations facing the skid part. For example, the second cor Petition 870250080298, dated 08 / 09 / 2025, page 23 / 56 15 / 27 magnetic bodies 140 and 150 are installed in predetermined locations facing the tip parts 240 and 250 of the skid part. For example, like the first magnetic bodies 120 and 130, the second magnetic bodies 140 and 150 are polyiron cores, metallic silicon plates or similar. The second magnetic bodies 140 and 150 may be other known magnetic bodies.

[0044] In this exemplary embodiment, in the same way as the first magnetic bodies 120 and 130, the second magnetic bodies 140 and 150 are arranged in predetermined locations of the induction heating coil 110 so as to cover the inner surface of the induction heating coil 110. According to this arrangement, the second magnetic bodies 140 and 150 shield the magnetic flux at the locations of arrangement, thus suppressing overheating of the rail 200 at these locations. In other words, the second magnetic bodies 140 and 150 are arranged in predetermined locations of the induction heating coil 110 so as to cover at least the inner circumferential surface facing the rail 200.

[0045] Similarly to the first magnetic bodies 120 and 130, it is desirable that the second magnetic bodies 140 and 150 be arranged in the induction heating coil 110 to satisfy a predetermined internal surface coverage ratio of the entire internal surface of the induction heating coil 110 facing the skid part. To be specific, it is desirable that the second magnetic body 140 be arranged on the internal surface of the induction heating coil 110 such that a coverage ratio C1, which is the ratio of a portion covered by the second magnetic body 140 to the entire portion facing the skid part 240 of the induction heating coil 110, is 5% or more and less than or equal to 95%. By means of the dis Petition 870250080298, dated 09 / 08 / 2025, p. 24 / 56 16 / 27 position of such proportion, the second magnetic body 140 can suppress the heating of the skid part 240 more appropriately. Furthermore, and even more preferably, it is desirable that it be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C1 is 8% or more and 60% or less, and it is even more desirable that it be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C1 is 10% or more and 30% or less. By means of the above proportion arrangement, the second magnetic body 140 can suppress the heating of the tip part 240 even more adequately.

[0046] Similarly, it is desirable that the second magnetic body 150 be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C1, that is, the ratio of a portion covered by the second magnetic body 150 to the whole portion facing the tip part 250 of the induction heating coil 110, is 5% or more and less than 95%. By arranging such a ratio, the second magnetic body 150 can suppress the heating of the tip part 250 more appropriately. More preferably, it is desirable that it be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C1 is 8% or more and less than 60%, and it is more desirable that it be arranged on the inner surface of the induction heating coil 110 in such a way that the coverage ratio C1 is 10% or more and less than 30%.By arranging the proportions above, the second magnetic body 150 can suppress the heating of the tip part 250 even more effectively.

[0047] Provided that the arrangement ratio is satisfied, the arrangement locations of the second magnetic bodies 140 and Petition 870250080298, dated 08 / 09 / 2025, page 25 / 56 17 / 27 150 may differ from those illustrated in Figure 1. For example, the arrangement locations of the second magnetic bodies 140 and 150 may be above or below the tip parts 240 and 250.

[0048] The third magnetic bodies 160 and 170 are magnetic bodies for flux concentration, installed in predetermined locations facing the core part 220. For example, in the same way as the first magnetic bodies 120 and 130 and the second magnetic bodies 140 and 150, the third magnetic bodies 160 and 170 are polyiron cores, metallic silicon plates or similar. The third magnetic bodies 160 and 170 may be other known magnetic bodies.

[0049] In this exemplary embodiment, the third magnetic bodies 160 and 170 are arranged in predetermined locations of the induction heating coil 110 so as to cover the outer surface of the induction heating coil 110. According to this arrangement, the third magnetic bodies 160 and 170 concentrate the magnetic flux at the locations of arrangement and heat the rail 200 at the corresponding locations more efficiently. In other words, the third magnetic bodies 160 and 170 are arranged in predetermined locations of the induction heating coil 110 so as to cover the outer periphery, excluding the surface of the inner circumference facing the rail 200.

[0050] With reference to Figure 1, the third magnetic bodies 160 and 170 are arranged on one side facing the core part 220 and on the other side facing the core part 220 so as to interleave the core part 220 with the rail 200. The proportion of portions covered by the third magnetic bodies 160 and 170 in relation to the entire portion facing the core part 220 of the induction heating coil 110 can be any proportion, such as 5% or Petition 870250080298, dated 09 / 08 / 2025, p. 26 / 56 18 / 27 plus and 100% or less.

[0051] For example, the post-weld heat treatment device 100 has the configuration described above. The configuration of the post-weld heat treatment device 100 may differ from that illustrated above. For example, the post-weld heat treatment device 100 may have the first magnetic body 120 and 130 or the second magnetic body 140 and 150. In addition, the post-weld heat treatment device 100 may have only one of the first magnetic bodies 120 and 130 and may have only one of the second magnetic bodies 140 and 150. Furthermore, the post-weld heat treatment device 100 may not have the third magnetic bodies 160 and 170. In addition, the post-weld heat treatment device 100 may have one of the second magnetic bodies 160 and 170.

[0052] As shown in Figure 5, rail 200 is pre-welded to the other rail 200. Rail 200 can be welded to the other rail 200 at only one end or it can be welded to the other rail 200 at both ends. For example, rail 200 can be welded by any means, such as flash butt welding or thermit welding.

[0053] Thus, the post-weld heat treatment device 100 has the induction heating coil 110 and also has the magnetic body for flux shielding in a portion that corresponds to the heating suppression location. According to this configuration, the post-weld heat treatment device 100 can suppress heating at the heating suppression location while ensuring heating of the core part 220, which is the location requiring heating of the rail 200. As a result, it is possible to impart appropriate properties to the respective Petition 870250080298, dated 08 / 09 / 2025, page 27 / 56 19 / 27 parts and it is possible to properly confer the necessary properties to the rail 200. Furthermore, as described above, the post-weld heat treatment device 100 can ensure heating conditions that respond to the necessary properties more appropriately by adjusting the arrangement ratio of each magnetic body to an appropriate range.

[0054] Furthermore, the induction heating coil 110 of the post-welding heat treatment device 100 covers the entire periphery of the rail 200 after adjusting the distance between the location requiring heating and the rail 200 and the distance between the location providing heating and the rail 200, according to the heating requirement, and so on. Consequently, it is possible to heat under more suitable heating conditions, allowing for more suitable properties to be conferred.

[0055] Furthermore, the post-weld heat treatment device 100 has a magnetic body for flux concentration at a location that corresponds to the core part 220, which is the location requiring heating of the rail 200. According to this configuration, the post-weld heat treatment device 100 can more appropriately heat the core part 220, which is the location requiring heating of the rail 200. Example of Implementation

[0056] Next, an example of implementation of the present invention and a comparative example will be presented to describe the content of the present invention. It should be noted that the content of the present invention is not limited to the implementation example.

[0057] Firstly, the present inventor compared the temperature of each part of the rail after the temperature increase, obtained with a real coil created, with the temperature of each part of the rail after the temperature increase obtained through simulation performed. Petition 870250080298, dated 08 / 09 / 2025, page 28 / 56 20 / 27 using a general-purpose electromagnetic field analysis software (JMAG® from JSOL Corporation). The simulation was conducted under the following conditions: a current value of 1000 A, a frequency of 18 kHz, a magnetic permeability of the track of 1.3 χ 10“4H / m, a magnetic permeability of the magnetic body of 5.0 x 10“3H / m, a thermal conductivity of the track of 47.2 W / mK, a specific heat of the track of 474 J / kgK and an electrical resistivity of the track of 2.1 χ 10“7Ω·m (all physical properties are values ​​at 25 °C) and the simulation was conducted so that the temperature in the core part was 600°C or more and the temperature rise rate was 2.8 °C / s.As shown in Table 1 below, a comparison was made between the actually measured values ​​and the simulation at two levels, and it was found that the difference between the heating temperatures of the respective rail parts, calculated by the simulation, and the actually measured values ​​were kept within 10% of the actually measured values. As a result, it was found that the rate of temperature increase in each rail part caused by the coil can be predicted through simulation. It should be noted that the clearances listed in Table 1 below refer to the distances between the respective parts and the coil. Table 1 Table: Maximum temperature reached by each part of the track by the coil / °C Position actual measurement of coil 1 simulation of coil 1 actual measurement of coil 2 simulation of coil 2 Φ top of billet 215 219 330 318 @ corner of billet part 226 218 354 334 O core 629 624 600 605 @ slip 226 249 384 380 Petition 870250080298, dated 08 / 09 / 2025, page 29 / 56 21 / 27 Coil 1: Clearance (Bill: 15 mm. Slide: 15 mm. Core: 10 mm (n / f: 0.7. n / h: 0.7)) Coverage Ratio (Bill C2: 43%. Slide C1: 59%. Core: 59%) Coil 2: Clearance (Bill: 15 mm. Slide: 15 mm. Core: 10 mm (n / f: 0.7. n / h: 0.7)) Coverage ratio (Bill C2: 0%. Slide C1: 16%. Core: 59%)

[0058] Subsequently, using the above simulation, the present inventor examined an appropriate range of each parameter while altering the coverage ratio C1, the coverage ratio C2, (distance n) / (distance f) and (distance n) / (distance h) described in this exemplary embodiment. Implementation Example 1

[0059] First, the simulation was conducted by altering the condition for the rail foot portion with a fixed condition for the rail head portion. Thus, a strip that satisfied both the necessary properties of the rail web portion and the rail foot portion was examined. It should be noted that the determination criteria for the implementation example and the comparative example are those shown below.

[0060] When the temperature of the core is raised to a reference temperature (600 to 700°C): Double circle: the temperature of the slip or billet section is within the reference temperature range and the heating efficiency is optimal; Circle: The temperature of the slip or billet section is within the reference temperature range, and the heating efficiency is favorable; Triangle: the temperature of the slip or billet section is close to the upper or lower limit of the reference temperature range, and the heating efficiency is low; and Petition 870250080298, dated 09 / 08 / 2025, p. 30 / 56 22 / 27 cross: the temperature of the slip or tailpipe is greater than or equal to the upper limit of the reference temperature range or equal to or less than the lower limit.

[0061] Figure 6 shows an example of the implementation example and the comparative example. Furthermore, when the implementation example and the comparative example from Figure 6 are summarized in a graph, it is illustrated as shown in Figure 7. Referring to Figures 6 and 7, it can be understood that when the coverage ratio C1 is 5% or more and 95% or less, and the value of (distance n) / (distance f) is 0.2 or more and 1 or less, it will be determined as a double circle or circle according to the determination criteria. That is, according to the implementation example and the comparative example above, it can be observed that the coverage ratio C1 is preferably in the range of 5% or more and 95% or less. Furthermore, according to the implementation example and the comparative example above, it can be understood that the value of (distance n) / (distance f) of 0.2 or more and 1 or less is a desirable range.Furthermore, although heating efficiency decreases, for example, in terms of reduced rate of temperature increase, it should be understood that if the permitted range does not exceed the permitted heating temperature of the skid part (the range that can be considered permitted under the criteria where a triangular judgment is applied), then the value of (distance n) / (distance f) is also permitted in the range greater than 1 up to and including 2. Implementation Example 2

[0062] Subsequently, a simulation was performed by altering a condition for the rail head. With this, an examination was carried out of a strip that meets the required properties of both the rail web and rail head. It should be noted that the determination criteria for the implementation example and Petition 870250080298, dated 08 / 09 / 2025, page 31 / 56 23 / 27 the comparative example are the same as implementation example 1.

[0063] Figure 8 shows an example of the implementation example and the comparative example. Furthermore, when the implementation example and the comparative example from Figure 8 are summarized in a graph, it is illustrated in Figure 9. Referring to Figures 8 and 9, it can be understood that when the coverage ratio C2 is 0% or more and 60% or less, and the value of (distance n) / (distance h) is 0.2 or more and 1 or less, it is determined as a circle according to the determination criteria. That is, according to the implementation example and the comparative example above, it can be understood that the coverage ratio C2 is preferably 0% or more and 60% or less. Furthermore, according to the implementation example and the comparative example above, it can be observed that it is desirable for the value of (distance n) / (distance h) to be 0.2 or more and 1 or less.Thus, it can be understood that it is desirable that a magnetic body not be disposed in the billet part or, when a magnetic body is provided, the coverage ratio C2 is 60% or less. Furthermore, although the heating efficiency is reduced, such a reduced temperature rate increases, when including the range that does not exceed the permitted heating temperature of the skid (the triangle range based on the determination criteria), it should be understood that a coverage ratio C2 between more than 60% and up to 65%, as well as a value of (distance n) / (distance f) greater than 1 and up to 1.5, are also admissible. Implementation Example 3

[0064] Subsequently, an analysis was carried out of a more desirable heat treatment range that would meet all the required properties of the web, end, and billet. It should be noted that the determination criteria for the example Petition 870250080298, dated 08 / 09 / 2025, page 32 / 56 24 / 27 of implementation and the comparative example are the same as implementation example 1. Furthermore, in implementation example 3, a simulation was performed assuming that a magnetic body placed in the web part and a magnetic body placed in the billet part do not affect each other, and that the magnitude of the distance between the web part and the billet part is not affected.

[0065] Figures 10 and 11 show an example of the implementation example and the comparative example. Referring to Figures 10 and 11, it can be observed that preferential heating is activated when the mentioned ranges are satisfied and adequate heating of each part becomes difficult when the ranges are exceeded. Additional Note

[0066] All or part of the exemplary embodiments described above may be described in the supplementary notes below. An overview of a post-weld heat treatment device and the like, according to the present invention, will be described below. However, the present invention is not limited to the following configurations. Supplementary Note 1

[0067] A post-weld heat treatment device that performs heat treatment on a welded rail, the post-weld heat treatment device comprising: an induction heating coil covering the entire periphery of the rail; and a magnetic body arranged so as to cover an inner surface of the induction heating coil in a portion that corresponds to a heat suppression location on the rail where heat suppression is required. Supplementary Note 2

[0068] The post-weld heat treatment device according to supplementary note 1, wherein: Petition 870250080298, dated 08 / 09 / 2025, page 33 / 56 25 / 27 The magnetic body is a first magnetic body disposed on a portion corresponding to a portion of the rail where heating suppression is required; and the first magnetic body is disposed on the inner surface of the induction heating coil in such a way that the coverage ratio, which is the ratio of a portion covered by the first magnetic body to a whole portion facing the rail part of the induction heating coil, is greater than 0% and equal to or less than 65%. Supplementary Note 3

[0069] The post-weld heat treatment device according to supplementary note 1 or 2, wherein: The induction heating coil covers the entire perimeter of the rail in such a way that, when the distance between the induction heating coil and a part of the rail web is n and the distance between the induction heating coil and a part of the rail head is h, the value of n / h is either 0.2 or more or 1.5 or less. Supplementary Note 4

[0070] The post-weld heat treatment device according to any of supplementary notes 1 to 3, where: The induction heating coil covers the entire perimeter of the rail in such a way that the distance between the induction heating coil and a part of the rail web is less than the distance between the induction heating coil and a part of the rail head. Supplementary Note 5

[0071] The post-weld heat treatment device according to any of supplementary notes 1 to 4, where: the magnetic body is a second magnetic body arranged Petition 870250080298, dated 08 / 09 / 2025, page 34 / 56 26 / 27 in a portion that corresponds to a tip portion which is the heating suppression portion of the rail where heating suppression is required; and the second magnetic body is arranged on the inner surface of the induction heating coil in such a way that the coverage ratio, which is a ratio of a portion covered by the second magnetic body to a whole portion facing the tip portion of the induction heating coil, is 5% or more and 95% or less. Supplementary Note 6

[0072] The post-weld heat treatment device according to any of supplementary notes 1 to 5, wherein: The induction heating coil covers the entire perimeter of the rail in such a way that, when the distance between the induction heating coil and part of the rail web is n and the distance between the induction heating coil and part of the rail end is f, the value of n / f is 0.2 or more and 2.0 or less. Supplementary Note 7

[0073] The post-weld heat treatment device according to any of supplementary notes 1 to 6, where: The induction heating coil covers the entire perimeter of the rail in such a way that the distance between the induction heating coil and a part of the rail web is less than the distance between the induction heating coil and a part of the rail end. Supplementary Note 8

[0074] The post-weld heat treatment device according to any of supplementary notes 1 to 7, the post-weld heat treatment device comprising: a third magnetic body arranged to cover a Petition 870250080298, dated 09 / 08 / 2025, p. 35 / 56 27 / 27 outer surface of the induction heating coil in a portion that corresponds to a part of the core, which is a portion of the rail that requires heating where heating is needed.

[0075] Although the present invention has been described above with reference to the exemplary embodiments described above, the present invention is not limited to the exemplary embodiments described above. The configuration and details of the present invention may be altered in various ways that may be understood by those skilled in the art within the scope of the present invention. LIST OF REFERENCE SIGNS 100 post-weld heat treatment device 110 induction heating coil 120 first magnetic body 130 first magnetic body 140 second magnetic body 150 second magnetic body 160 third magnetic body 170 third magnetic body 200 rail 210 part of the payment slip 211 top part of the ticket 212 side part of bill 213 side part of bill 214 corner part 215 corner part 220 part of soul 230 base part 240 tip part 250 tip part Petition 870250080298, dated 08 / 09 / 2025, page 36 / 56

Claims

1 / 3 CLAIMS 1. Post-weld heat treatment device that performs heat treatment on a welded rail, characterized in that it comprises: an induction heating coil covering the entire periphery of the rail; and a magnetic body arranged so as to cover an inner surface of the induction heating coil in a portion corresponding to a heat suppression location of the rail where heat suppression is required.

2. Post-weld heat treatment device according to claim 1, characterized in that: the magnetic body is a first magnetic body disposed on a portion corresponding to a billet part that is the heating suppression location of the rail where heating suppression is required; and the first magnetic body is disposed on the inner surface of the induction heating coil in such a way that the coverage ratio, which is a ratio of a portion covered by the first magnetic body to an entire portion facing the billet part of the induction heating coil, is greater than 0% and equal to or less than 65%.

3. Post-weld heat treatment device, according to claim 1 or 2, characterized in that: the induction heating coil covers the entire periphery of the rail in such a way that, when a distance between the induction heating coil and part of the rail web is n and a distance between the induction heating coil and part of the rail head is h, a value of n / h is 0.2 or more and 1.5 or less.

4. Post-weld heat treatment device, of Petition 870250080298, dated 09 / 08 / 2025, page 37 / 56 2 / 3 according to any of claims 1 to 3, characterized in that: the induction heating coil covers the entire periphery of the rail in such a way that a distance between the induction heating coil and a part of the rail web is less than a distance between the induction heating coil and a part of the rail head.

5. Post-weld heat treatment device, according to any one of claims 1 to 4, characterized in that: the magnetic body is a second magnetic body disposed in a portion corresponding to a tip portion which is the heating suppression portion of the rail where heating suppression is required; and the second magnetic body is disposed on the inner surface of the induction heating coil in such a way that the coverage ratio, which is a ratio of a portion covered by the second magnetic body to a whole portion facing the tip portion of the induction heating coil, is 5% or more and 95% or less.

6. Post-weld heat treatment device, according to any one of claims 1 to 5, characterized in that: the induction heating coil covers the entire periphery of the rail in such a way that, when a distance between the induction heating coil and a part of the rail web is n and a distance between the induction heating coil and a part of the rail end is f, a value of n / f is 0.2 or more and 2.0 or less.

7. Post-weld heat treatment device, according to any one of claims 1 to 6, characterized by the fact that: the induction heating coil covers the entire periphery of the rail in such a way that a distance between the induction heating coil and a part of the rail web is less than a distance between the induction heating coil and a part of the rail end.

8. Post-weld heat treatment device, according to any one of claims 1 to 7, characterized in that it comprises: a third magnetic body arranged so as to cover an outer surface of the induction heating coil in a portion corresponding to a core portion that is a portion of the rail requiring heating where heating is necessary. Petition 870250080298, dated 09 / 08 / 2025, p. 39 / 56

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