JP3701740B2 - Induction heating coil and bending method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating coil that induction-heats these members in order to perform hot working such as bending on a strip or plate having a thin-walled portion, and particularly induction heating suitable for heating of H-shaped steel. It relates to coils. The present invention also relates to a hot bending method using the induction heating coil.
[0002]
[Prior art]
Conventionally, as a method for bending a steel pipe, an annular induction heating coil set so as to surround the steel pipe is annularly heated in a narrow area in the longitudinal direction of the steel pipe, and the induction heating coil is moved in the longitudinal direction of the steel pipe. The heated part is moved by relative movement, and the steel pipe is bent by applying a bending moment. At the same time, cooling water is blown downstream of the heated and bent part by the induction heating coil for cooling. A hot bending method for solidifying is known.
[0003]
[Problems to be solved by the invention]
Recently, applications of H-section steel curved to a certain curvature have been developed. Therefore, the present inventors believe that a curved H-section steel can be manufactured by applying a bending process to the straight H-section steel by applying the bending method for the steel pipe described above, and FIG. As shown in FIG. 8, an induction heating coil 2 having a shape surrounding the H-section steel 1 and having a hollow rectangular shape was created, and a bending test was performed using the induction heating coil 2. That is, the induction heating coil 2 is fixed at a fixed position, the H-section steel 1 is passed through it, and the H-section steel 1 is moved in the arrow X direction while being heated by the induction heating coil 2. A bending moment is applied to the tip of 1 by a swivel arm 3, and at the same time, cooling water 5 is injected into the H-section steel 1 from a cooling water injection hole 4 formed at one end corner of the induction heating coil 2. The rear end of the portion 6 heated by 2 and causing bending deformation was cooled, and the H-section steel 1 was continuously bent.
[0004]
However, it has been found that there is a problem in heating the H-section steel with the induction heating coil 2. That is, although the H-section steel 1 has a central web portion 1A and flange portions 1B at both ends, the web portion 1A is usually thin, for example, the height x width (H x B) of the cross section. In the H-section steel 1 of 250 mm × 250 mm, the thickness of the web portion 1A is about 9 mm while the thickness of the flange portion 1B is 14 mm. Moreover, even if it is larger H-shaped steel than this, although the thickness of the flange part 1B becomes thick, the thickness of the web part 1A does not increase so much. When the induction heating coil 2 is arranged on both sides of the thin web portion 1A and induction heating is performed, the web heating portions 2A and 2B located on both sides of the web portion 1A of the induction heating coil 2 interfere with each other to increase the heating efficiency. It will decrease. For example, when 2.4 KHz is used as the frequency applied to the induction heating coil 2, the penetration depth of the induction current is about 10 mm. Therefore, the induction current generated by the web heating unit 2A located above the web unit 1A is generated by the web unit 1A . This also occurs considerably on the lower surface, which cancels a part of the induced current generated by the web heating unit 2B positioned below, and eventually reduces the heat generation efficiency. For this reason, it is difficult to raise the temperature of the web portion 1A, the balance with the flange portion 1B having a large thickness and high heating efficiency is deteriorated, and the temperature balance cannot be maintained unless the processing speed is slowed down. I had to make it low.
[0005]
Further, as can be seen from FIG. 6, when the H-shaped steel 1 is bent in a direction perpendicular to the flange portion 1B, the thin web portion is obtained despite the bending process taking a temperature balance between the web portion and the flange portion. There was also a problem that 1A was deformed into a wave shape, resulting in a defective shape.
[0006]
The present invention has been made in view of such problems, and can efficiently heat an H-section steel having a web portion that is thin and has an interference heating coil that is arranged on both sides. It is an object to provide a simple induction heating coil.
[0007]
Another object of the present invention is to provide a bending method that makes it possible to bend H-shaped steel without causing a web-like deformation in the web portion.
[0008]
[Means for Solving the Problems]
1st invention of this application is the induction heating coil located in each side in order to avoid interference with the 1st web heating part and the 2nd web heating part of the induction heating coil which are each located in the both sides of the web part of H-section steel The heating region by the first web heating unit and the second web heating unit is configured to be shifted in the longitudinal direction. With this configuration, even if the web portion is thinner than the penetration depth of the induction current, the induction current due to the induction heating coil portion located on one side of the web portion and the induction current due to the induction heating coil portion located on the opposite side cancel each other. There is almost no such thing and it becomes possible to heat efficiently.
[0009]
The second invention of the present application is to lower the temperature of the central portion of the web portion in the region heated to bend and deform in order to prevent the wavy deformation that occurs in the web portion during the bending of the H-section steel. is there. Thus, if the temperature of the center part of a web part is made low, the part will become difficult to deform | transform, and it will not become a wave shape when bending-deformed, but a favorable bending process will be attained. Since the central portion of the web portion is the neutral surface at the time of bending and its vicinity, the amount of deformation is small, and even if the rigidity of this portion is high, there is no problem with bending deformation.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[0011]
The induction heating coil according to the first aspect of the present invention is for heating an H-shaped steel, and includes a coil body having a shape along the entire circumferential surface over the front and back surfaces of the H-shaped steel. A first web heating unit disposed opposite to one surface of the steel web portion, a second web heating portion disposed opposite to the other surface of the web portion, and a flange disposed opposite to the flange portion of the H-shaped steel While having a heating part, it is the composition which the 1st web heating part and the 2nd web heating part heat the position which shifted in the longitudinal direction of the web part, and the 1st web heating part and the 2nd web heating part, longitudinal direction of the heating region of the H-shaped steel by the, some wherein the flange heating portion is configured to nearly coincide with the longitudinal direction of the heating region of the H-shaped steel according to.
[0012]
With this configuration, it becomes possible to efficiently heat the thin web portion, the thin web portion can be heated in the same manner as the thick flange portion, and the flange portion of the H-shaped steel and the web portion in the longitudinal direction can be quickly moved in the same direction. And it can heat evenly.
[0013]
The induction heating coil having the above configuration can be suitably used for heating for bending a strip or plate material such as H-shaped steel, but in addition to this, it heats a partial region in the longitudinal direction of the strip or plate material. It can be used for applications that need to be performed, for example, heating for heat treatment, heating for compressive deformation, and the like.
[0014]
In the bending method according to the second aspect of the present invention, the induction heating coil having the above-described configuration is set so as to surround the H-shaped steel, and the H-shaped steel is locally heated by the induction heating coil while the induction heating coil is The heated part is moved in the longitudinal direction of the H-shaped steel by moving it relatively in the longitudinal direction of the section steel, and at the same time, the entire circumference on the downstream side of the heated part is cooled and the upstream side The central portion of the web portion is cooled, and at the same time, a bending moment is applied to the portion heated by the induction heating coil to perform bending.
[0015]
With this configuration, the flange portion and the web portion in a partial region in the longitudinal direction of the H-shaped steel can be bent relatively uniformly and quickly, and the central portion of the web portion is heated before heating. Since it is cooled, the temperature is lower than that of the other parts and it is difficult to be deformed, so that it is not deformed into a wave shape when bent and deformed, so that it can be bent in a good shape.
[0016]
【Example】
Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing a state in which an H-shaped steel is bent using an induction heating coil according to an embodiment of the present invention, FIG. 2 is a schematic view taken along line AA in FIG. 1, and FIG. Fig. 4 is a schematic view taken along the line CC of Fig. 2, Fig. 5 is a schematic perspective view of the induction heating coil, 1 is an H-section steel, and 1A is a web of the H-section steel. 1B is a flange part. 3 is a swivel arm for applying a bending moment to the H-section steel 1, and 12 is an induction heating coil that also serves as a cooling means for heating a small area in the longitudinal direction of the H-section steel 1 and cooling one end of the heated area. Yes, in this embodiment, it is provided at a fixed position.
[0017]
As can be clearly seen from FIG. 2, the induction heating coil 12 includes a coil body 13 having a shape along the entire peripheral surface of the H-shaped steel 1 and the coil body 13 is made of a conductive material and has a hollow structure. The end portion is located at a position facing the center of the web portion 1A of the H-section steel 1 and is connected to the connecting conduits 14A and 14B. The connection conduits 14A and 14B are connected to a power supply device and a cooling water supply source ( not shown), and supply current and cooling water to the coil body 13. An insulator is disposed between the connecting conduits 14A and 14B.
[0018]
The coil body 13 includes a first web heating section 13A located on one side of the web section 1A, which is a thin wall section, a second web heating section 13B located on the opposite side, and a flange heating surrounding the flange section 1B. Part 13C. As can be clearly seen from FIG. 3, the first web heating unit 13 </ b> A located on one side of the web portion 1 </ b> A of the H-section steel 1 has the first web 13 a facing the web portion 1 </ b> A and the second web located on the opposite side. The heating unit 13B has a second flat surface 13b that faces the web 1A. The widths W ₁ and W ₂ of the first flat surface 13a and the second flat surface 13b are set to be slightly smaller than half of the maximum width W of the coil body 13, and the first flat surface 13a and the second flat surface 13b. The surface 13b is arranged so as to be displaced in the longitudinal direction of the H-section steel 1. More specifically, the first flat surface 13 a is disposed close to one end side of the coil body 13, and the second flat surface 13 b is disposed close to the other end side of the coil body 13. Thereby, the heating area of the web part 1A by the first web heating part 13A and the heating area of the web part 1A by the second web heating part 13B are shifted in the longitudinal direction of the H-section steel 1, and the thin web Even if the part 1A is induction-heated from both sides, it hardly interferes with each other.
[0019]
The flange heating unit 13 </ b> C has a rectangular cross section as can be clearly seen from FIG. 4, and has a third flat surface 13 c that faces the flange of the coil body 13. The width of the third flat surface 13c is set to be equal to the maximum width W of the coil body 13, and therefore the heating region in the longitudinal direction of the H-section steel 1 by the flange heating portion 13C is substantially equal to the maximum width W of the coil body 13. It is substantially equal to the heating region in the longitudinal direction of the H-section steel 1 by the first web heating unit 13A and the second web heating unit 13B. With this configuration, the coil main body 13 can heat the same region in the longitudinal direction of the web portion 1A and the flange portion 1B of the H-section steel 1 to a substantially constant width.
[0020]
The first web heating section 13A and the flange heating section 13C of the coil body 13 are each formed with an injection hole 15 at a corner on one end side, spraying cooling water 16 onto the H-section steel 1, and the H-section steel 1 is heated. The end portion of the portion 17 (the end portion on the downstream side with respect to the traveling direction of the heated portion 17 with respect to the H-section steel 1) is cooled. Further, a water cooling jacket 20 is provided at a position adjacent to the second web heating unit 13B, and the end of the heated portion 17 is cooled by spraying the cooling water 16 from the injection holes 21 formed at the corners. It is supposed to be. With this configuration, the H-section steel 1 is cooled by the injected cooling water 16 over the entire circumference.
[0021]
A pre-cooling jacket 25 is provided on the side of the coil body 13 opposite to the side where the injection holes 15 are provided, and cooling water 27 is supplied from the injection holes 26 provided in the jacket to the region before the H-section steel 1 is heated. Precooled by spraying. The preliminary cooling jacket 25 is disposed so as to cool only the central portion of the web portion 13A, for example, so as to cool a central region having a width of about 100 to 150 mm with respect to a web length of about 600 mm.
[0022]
Next, a method for bending the H-section steel 1 using the induction heating coil 12 having the above configuration will be described. With the induction heating coil 12, the H-section steel 1 is locally heated to a temperature at which plastic deformation is easy, for example, in a red-hot state, and the cooling water 16, 27 is sprayed before and after the heated portion. Is pushed in the direction of the arrow X (see FIG. 1), and a bending moment is applied to the H-section steel 1 by the swing arm 3. As a result, the portion 17 heated locally by the induction heating coil 12 is bent, and immediately after that, the portion 17 is cooled and solidified by the cooling water 16 and continuously bent. During this bending process, the first web heating unit 13A and the second web heating unit 13B disposed on both sides of the web unit 1A induction heat the thin web 1A. As can be seen from FIG. Since they are displaced in the longitudinal direction of the H-section steel 1, they hardly interfere with each other, and can be heated efficiently. Accordingly, the web portion 1A and the flange portion 1B can be heated promptly and evenly, the bending process can be performed at a high speed, and the power consumption can be reduced. For example, when the H-section steel 1 having a cross-sectional height × width (H × B) of 250 mm × 250 mm is bent using the induction heating coil 2 shown in FIGS. Although it was about 0 to 1.5 mm / s, in this example, processing at about 3.0 mm / s was possible, and power consumption could be reduced by about 20%.
[0023]
Next, the pre-cooling jacket 25 cools the H-section steel 1 by spraying cooling water 27 on the area before the H-section steel 1 is heated and on the central portion of the web portion 1A. For this reason, only the central portion of the web portion 1A is cooled by the cooling water 27, the temperature becomes lower than other portions, and plastic deformation is difficult. For this reason, an unstable deformation | transformation is prevented at the time of a bending process, a wavy deformation | transformation does not arise in the web part 1A, and a good-shaped product can be obtained.
[0024]
In the above embodiment, the cooling water 16 and 27 is sprayed to cool the H-section steel 1, but another cooling medium such as cooling oil or cooling gas may be sprayed instead of the cooling water. . Moreover, in the said Example, although the cooling water 27 is sprayed on the center part of the web part 1A, and the temperature of a center part is made low compared with another part, instead of this, as the induction heating coil 12, the center of a web is used. heating heat portions used as small again, whereby it may be configured to lower the temperature of the central portion of the web.
[0025]
Further, in the above embodiment, the case where the H-section steel 1 is bent in a direction perpendicular to the flange portion 1B has been described, but the induction heating coil 12 according to the embodiment of the present invention has the H-section steel 1 perpendicular to the web portion 1A. It can also be used when bending. Furthermore, it goes without saying that the induction heating coil 12 can be used not only for bending the H-shaped steel but also for heating for other processing or processing.
[0026]
【The invention's effect】
[0027]
As described above, the induction heating coil of the present invention has a coil body having a shape along the entire peripheral surface of the H-section steel, and is disposed across the H-section steel web portion of the coil body. The first web heating unit and the second web heating unit are configured to heat the position shifted in the longitudinal direction of the web unit, so that the first web heating unit and the second web heating unit are used as the web unit. The generated induced current is mainly generated in a region shifted in the longitudinal direction, and even if the wall thickness is thin, the induced currents hardly cancel each other. Therefore, the thin web portion can be efficiently heated, and the thick flange It is possible to heat uniformly and quickly in the same manner as the section, and in addition, the heating area in the longitudinal direction of the H-section steel by the first web heating section and the second web heating section is used to heat the flange section. Flange With the construction in which almost coincides with the longitudinal direction of the heating region of the H-beam by the heat unit, that can heat the longitudinal direction substantially the same region of the flange portion and web portion of the H-shaped steel quickly and evenly Has an effect.
[0028]
The bending method of the present invention is heated by moving the induction heating coil relatively in the longitudinal direction of the H-shaped steel while heating a partial region in the longitudinal direction of the H-shaped steel with the induction heating coil having the above configuration. The part was moved in the longitudinal direction of the H-shaped steel, and at the same time, the entire circumference of the downstream side of the heated part was cooled and the central part of the web part on the upstream side was cooled and simultaneously heated by the induction heating coil. By adopting a configuration in which the bending moment is applied to the portion, the web portion and the flange portion of the H-shaped steel can be heated uniformly and efficiently, and the web portion can be quickly bent. The center part can be bent at a lower temperature than other parts, and can be bent in a state where it is difficult to deform, and it is possible to prevent a web-like deformation from occurring and obtain a product bent into a good shape. The effect It is.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a state where an H-shaped steel is bent using an induction heating coil according to an embodiment of the present invention. FIG. 2 is a schematic view taken along the line AA in FIG. Fig. 4 is a schematic view taken along the line B-B of Fig. 2. Fig. 4 is a schematic view taken along the line C-C of Fig. 2. Fig. 5 is a schematic perspective view of the induction heating coil of the embodiment of Fig. 1. Fig. 6 Fig. 7 is a schematic cross-sectional view showing a state where the H-shaped steel is bent using the induction heating coil manufactured in Fig. 7. Fig. 7 is a schematic view taken along the line DD in Fig. 6; Figure [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 H-section steel 1A Web part 1B Flange part 2 Induction heating coil 3 Turning arm 12 Induction heating coil 13 Coil main body 14A, 14B Connection conduit | pipe 13A 1st web heating part 13B 2nd web heating part 13C Flange heating part 13a 1st flat surface 13b Second flat surface 13c Third flat surface 15 Injection hole 16 Cooling water 17 Heated portion 20 Water cooling jacket 20
21 Injection hole 25 Preliminary cooling jacket 26 Injection hole 27 Cooling water

Claims (2)

A coil body having a shape along the entire circumferential surface of the H-section steel, the coil body being disposed opposite to one surface of the H-section steel web section; A second web heating unit disposed opposite to the other surface, and a flange heating unit disposed opposite to the flange portion of the H-shaped steel, and the first web heating unit and the second web heating unit It is the structure which heats the position shifted | deviated to the longitudinal direction, and the heating area of the longitudinal direction of the H-section steel by the said 1st web heating part and the 2nd web heating part is the longitudinal direction of the H-section steel by the said flange heating part An induction heating coil for heating an H-section steel, characterized in that it has a configuration that substantially matches the heating region of The induction heating coil according to claim 1 is set so as to surround the H-shaped steel, and the induction heating coil is relatively heated in the longitudinal direction of the H-shaped steel while locally heating the H-shaped steel with the induction heating coil. At the same time, the entire circumference of the downstream side of the part heated by the induction heating coil is cooled and the central part of the upstream web part is cooled, and at the same time, a bending moment is applied to the part heated by the induction heating coil. A bending method for H-section steel, wherein bending is performed .

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