JP2018114535A - Heating method and heating equipment for continuous casting slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous casting slab heating method and heating equipment which enable a continuous casting slab to be heated uniformly in a width direction edge part over the full length and is economical.SOLUTION: Heating equipment 20 is provided in a transportation passage of continuous casting slabs S from the outlet side of the continuous casting equipment to the inlet side of hot-rolling equipment. The heating equipment 20 has a plurality of induction heating devices 22 arranged at equal intervals in the transportation direction of continuous casting slabs S to heat the width direction edge part of the continuous casting slab S, and the heating length Lc of induction heating device 22 is almost equal to the interval Ld between the induction heating devices 22. The continuous casting slab S in the heating equipment 20 is heated by a plurality of induction heating devices 22 while being moved by reciprocation in a forward direction and in a reverse direction by a distant equivalent to odd-numbered times of the heating length Lc.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heating method and a heating equipment for a widthwise edge portion of a continuous casting slab (hot piece) cast by a continuous casting equipment, and in particular, reheating the continuous casting slab cast by the continuous casting equipment in a heating furnace. The present invention relates to a heating method and heating equipment for a continuous cast slab suitable for direct feed rolling (HDR).

  Direct feed rolling is a direct connection between continuous casting equipment and hot rolling equipment, and uses the sensible heat of continuous cast slabs (hereinafter also simply referred to as “slabs”) cast by continuous casting equipment to save energy and greatly It is a technology that enables shortening of the process.

  Since the speed of continuous casting is several meters per minute and it takes several minutes for one slab to finish casting, the temperature of the edge portion in the width direction of the slab (hereinafter also simply referred to as “edge portion”) decreases during this time. In some cases, direct temperature rolling without passing through a heating furnace may require some temperature compensation.

  In this regard, Patent Document 1 proposes providing a heating device that heats the end surface of the slab in the vicinity of the cutter of the continuous casting machine.

  Patent Document 2 proposes that an apparatus for heating the edge portion in the width direction of the slab with a burner is installed in the vicinity of the slab heating furnace for hot rolling.

  Non-Patent Document 1 discloses a method of induction heating a width direction edge portion of a slab.

  Non-Patent Document 2 discloses a method of heating a billet that is smaller than a slab while the billet is housed in an induction heating coil.

Japanese Patent Laid-Open No. 60-18201 JP-A-55-41902

Steelmaking Research No. 313 (1984) 6 Nippon Steel Corporation Hitachi review June 1967 issue 17

  However, in the heating apparatus of Patent Document 1, the conveying direction of the slab being heated is one direction, and the edge portion on the tip side of the slab that has been heated first starts to dissipate and the heating of the tail end ends. The temperature at the edge part on the tip side is greatly reduced. In the embodiment shown in FIG. 3 of Patent Document 1 where a heating device is installed in the vicinity of the cutter of the continuous casting machine, the slab once exceeds the Al-N resolution temperature while the slab is transported to the roughing mill. The temperature of the edge portion of the steel sheet has fallen again to about 1000 ° C. (see FIG. 2 of the same document). When rolling in that state, the center in the width direction is rolled at about 1200 ° C. from the viewpoint of strict quality control in recent years. There is a concern about the influence on the quality of the edge portion as compared with the portion.

  Moreover, in the heating apparatus of patent document 1, since the conveyance speed of the slab at the time of a heating is dependent on the speed of the continuous casting by a continuous casting machine, it cannot heat at the speed independent of the casting speed. Therefore, the heating time becomes as long as about 10 minutes (see FIG. 2 of the same document), and the temperature at the center portion in the width direction of the slab continues to decrease during about 10 minutes for heating the edge portion. When the temperature drop becomes large, there is a problem that the temperature is lower than the Al-N solid solution temperature or the temperature required for rough rolling, and there is a problem in terms of energy saving if large heat input is performed considering the temperature drop.

  In Patent Document 2, the edge portion heating device is arranged on the conveyance table for sending the slab to the roughing mill and the temperature compensation of the edge portion in the width direction of the slab is performed immediately before rolling, but the heating is performed by the burner. It takes about 10 minutes to heat a large heat capacity such as a slab, and has the same problem that the temperature in the central portion in the width direction decreases while the edge portion is heated. Yes.

  In this way, the heating by the burner takes a long time, but the method by induction heating as described in Non-Patent Document 1 can heat at a conveyance speed of about 4 m / min, for example, a length of 10 m. If the slab has, the heating is completed in about 2.5 minutes, the heat dissipation loss can be remarkably reduced, and the heating process can be prevented from becoming the rate-limiting step of production.

  By the way, in order to hold and transfer the slab, a large number of holding and conveying rollers are installed, and an induction heating coil for heating the edge in the width direction of the slab must be installed between them. Arranged to be empty. In the case of slab heating, the holding / conveying roller is highly rigid and has a heat resistance function, so that the interval between the induction heating coils along the slab conveying direction is equal to or longer than the heating length of the coil. Become. For this reason, when the slab is stopped and heated, a heated portion and a non-heated portion are generated, resulting in uneven heating over the entire length. Therefore, it is necessary to heat the slab while moving it. Further, since the heating length of the induction heating coil is shorter than the moving distance of the slab, the slab must be moved at a low speed in order to give sufficient heat.

  However, when heating while moving the slab using an induction heating device, the induction section of the slab that has passed through the induction heating device and has been heated only by setting the section of the induction heating device to be approximately the same as the length of the slab. The edge portion is dissipated for a long time until the tail end side finishes heating, and uniform heating is not possible under the influence. That is, it has the same problem as Patent Document 1 in that the temperature of the edge portion on the front end side that has been heated first decreases while the slab is heated over its entire length. On the other hand, if temperature compensation is performed in consideration of heat dissipation on the tip side of the slab, a part that is heated to a higher temperature than necessary is generated, which is not economical, and the temperature at the time of rolling becomes uneven, and deformation resistance Becomes uneven and adversely affects the thickness accuracy.

  For this reason, in order to perform uniform heating, it is necessary to arrange the induction heating device in a range equal to or longer than the length of the slab, and in order to apply heat uniformly over the entire length, it is usually twice that of the slab. A large number of induction heating devices must be arranged in a range corresponding to the length, which is uneconomical.

  On the other hand, when heating a relatively short material to be heated such as a billet, as described in Non-Patent Document 2, the material to be heated is housed in a coil of an induction heating device, and the whole is all at once. It is possible to heat to However, it is not practical to simultaneously induction heat the entire length of a long slab. Further, there is a problem that a mechanism for holding the slab of 30 tons and moving the slab in some cases cannot be accommodated inside the coil.

  The present invention provides a heating method and heating equipment for a continuous casting slab that solves the above-described problems of the prior art, can uniformly heat the edge in the width direction over the entire length of the continuous casting slab, and is economical. The purpose is to do.

  In the present invention, when a continuous cast slab cast by a continuous casting facility is directly rolled by a hot rolling facility, the continuous casting slab is heated continuously at the edge in the width direction before hot rolling the continuous cast slab. A plurality of induction heating devices for heating a width direction edge portion of a continuous casting slab in a conveying path of the continuous casting slab from the exit side of the continuous casting facility to the entry side of the hot rolling facility. Heating equipment that is arranged at equal intervals in the conveying direction and each induction heating device has a heating length that is substantially equal to the interval between the induction heating devices is provided, and the continuous casting slab in the heating equipment is only a distance corresponding to an odd multiple of the heating length. A widthwise edge portion of the continuous cast slab is heated by a plurality of induction heating devices while reciprocating in the forward direction and the opposite direction.

  In the heating method of the continuous cast slab according to the present invention, the continuous cast slab is reciprocally moved in the forward direction and the reverse direction by a distance corresponding to one time of the heating length in the heating facility by a plurality of induction heating devices. It is preferable to heat the edge in the width direction of the continuous cast slab.

  Further, in the method for heating a continuous cast slab according to the present invention, among the induction heating devices that operate when at least some of the plurality of induction heating devices operate, the most downstream from the induction heating device located at the most upstream. When the length of the heating section to the induction heating device located at L is L, the length of the continuous casting slab is Ls, and the interval between the induction heating devices is Ld, heating is performed so as to satisfy the relationship of Ls ≦ L ≦ Ls + Ld It is preferable to determine the length L of the section.

  Furthermore, in the heating method of the continuous casting slab of the present invention, the conveying speed of the continuous casting slab from the continuous casting equipment to the heating equipment and the conveying speed of the continuous casting slab from the heating equipment to the hot rolling equipment are It is preferable to make it larger than the reciprocating speed during heating of the continuous casting slab by.

  In addition, the present invention is arranged in a continuous casting slab conveyance path from the exit side of the continuous casting facility to the entry side of the hot rolling facility, and the continuous casting slab cast by the continuous casting facility is directly sent by the hot rolling facility. When rolling, the continuous casting slab heating equipment that heats the edge in the width direction of the continuous casting slab before hot rolling the continuous casting slab, arranged at equal intervals in the conveying direction of the continuous casting slab, A plurality of induction heating devices that heat edge portions of the continuous casting slab in the width direction; and a moving means that reciprocates the continuous casting slabs heated by the plurality of induction heating devices. The heating means has a heating length that is substantially equal to the interval of, and during the heating of the continuous casting slab by a plurality of induction heating devices, the moving means moves the continuous casting slab forward by a distance corresponding to an odd multiple of the heating length of the induction heating device. And vice versa are those adapted for reciprocating.

  In the continuous casting slab heating facility of the present invention, the moving means is a distance corresponding to one time the heating length of the induction heating device while the continuous casting slab is heated by the plurality of induction heating devices. It is preferable to be configured to reciprocate only in the forward direction and in the opposite direction.

  Further, in the heating equipment for continuous cast slabs of the present invention, among the induction heating devices that operate when at least some of the plurality of induction heating devices operate, the most downstream from the induction heating device located at the most upstream. When the length of the heating section to the induction heating device located at L is L, the length of the continuous casting slab is Ls, and the distance between the induction heating devices is Ld, the length L of the heating section is Ls ≦ L It is preferable to satisfy the relationship ≦ Ls + Ld.

  Furthermore, in the heating apparatus for continuous cast slabs according to the present invention, it is preferable that the moving means has a pusher that reciprocates by directly pressing the tip and tail ends of the continuous cast slab.

  According to this invention, the plurality of induction heating devices are arranged at intervals in the transport direction, and the edge portion is heated while reciprocating the slab in the section where the induction heating device is arranged. It is possible to prevent the tip portion from being cooled before the heating of the tail end portion is completed, and it is possible to greatly reduce the number of installed induction heating devices. Moreover, since it is possible to heat in a short time compared with the case where it heats with a burner, the temperature fall of the center part of the width direction of a slab while heating an edge part can be suppressed. Furthermore, the induction heating devices are arranged at equal intervals, the heating length of each induction heating device is made substantially equal to the interval of the induction heating devices, and the slab is forwarded by a distance corresponding to an odd multiple of the heating length in the heating equipment. Since the slab edge portion is heated by a plurality of induction heating devices while reciprocating in the opposite direction, the variation in the amount of heat generated by the slab direction change is offset, and the accumulated heat amount of the slab is extended over the entire length. Almost uniform.

FIG. 1 schematically shows a hot-rolled steel sheet manufacturing facility equipped with a continuous casting slab heating facility according to an embodiment of the present invention, wherein (a) is a side view and (b) is a plan view. FIG. 2 shows the heating equipment for the continuous cast slab of this embodiment, where (a) is a side view and (b) is a front view. FIGS. 3A to 3E are explanatory views showing the positional relationship in the transport direction between the slab and the induction heating device in each heating stage when the edge portion of the slab is heated while transporting the slab. is there. FIG. 4 is a side view showing a continuous casting slab heating facility according to another embodiment of the present invention. 5 (a) to 5 (e) respectively show the slab heating equipment and heating method of Comparative Example 1 when the slab is reciprocated by a distance corresponding to twice the heating length of the induction heating device to perform heating. It is explanatory drawing which showed the positional relationship in the conveyance direction of the slab of a heating step, and an induction heating apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a hot-rolled steel sheet manufacturing facility equipped with a continuous casting slab heating facility according to an embodiment of the present invention, (a) is a side view, (b) is a plan view, FIG. 2 shows the heating equipment for the continuous cast slab of this embodiment, where (a) is a side view and (b) is a front view.

  The hot-rolled steel sheet manufacturing facility 10 shown in FIG. 1 is hot without heating a continuous cast slab (hereinafter also simply referred to as “slab”) S cast in a continuous casting facility 12 in a heating furnace. This is a direct feed rolling (HDR) equipment that is directly sent to the rolling equipment 14, reduced in thickness to a predetermined thickness and wound in a coil shape.

  In the continuous casting facility 12, the molten steel poured into the mold 12b from the tundish 12a is cooled by the mold 12b to become a slab, and continuously from below the mold 12b along a plurality of rolls (not shown) provided below the mold 12b. Pulled out. The slab is cooled with cooling water while passing through the roll, and eventually solidification to the inside is completed. The slab that has been solidified is cut into a predetermined length by a cutter 12c such as a gas cutter to form a slab S.

  The slab S manufactured by the continuous casting facility 12 is transported to the hot rolling facility 14 by the transport roller 16. The slab sent to the hot rolling facility 14 is rolled to a predetermined thickness by the roughing mill 14a and the finishing mill 14b, and the rolled steel sheet is made into a predetermined material by the water cooling facility 18 and then wound in a coil shape. Taken into a hot rolled coil product.

  The quality of the slab S manufactured by the continuous casting facility 12 is improved when the temperature of the edge portion in the width direction (hereinafter also simply referred to as an “edge portion”) is lowered until the slab S is conveyed to the hot rolling facility 14. Is concerned about the impact of Therefore, in this hot-rolled steel sheet manufacturing facility 10, a heating facility 20 is provided in the transport path of the slab S from the exit side of the cutter 12c to the entrance side of the hot rolling facility 14 to compensate the temperature of the edge portion of the slab S. It is configured to do.

  Specifically, the heating equipment 20 of this embodiment heats the left and right edge portions of the slab S, and as shown in FIG. 2 (a), a plurality of heaters 20 are arranged at equal intervals Ld in the transport direction. The induction heating device 22 is provided. Each induction heating device 22 includes a pair of left and right core members 24a and 24b made of iron, ferrite, or the like, which are substantially C-shaped when viewed in the conveying direction, as shown in FIG. 24b and a coil conductor 26 wound around the outer periphery of the core 24b. The core members 24a and 24b are arranged opposite to each other so that the edge portion of the slab S is located in the opening, and a high-frequency current is applied to the coil conductor 26. A high frequency magnetic flux is generated inside the core members 24a and 24b by energization, and the edge portion of the slab S is heated by an eddy current generated by the magnetic flux. Each induction heating device 22 has a heating length Lc substantially equal to the interval Ld between the induction heating devices 22. The heating length Lc indicates the length of the core material 24a, 24b where the coil conductor 26 is wound along the transport direction. Here, “substantially equal” means that uniform heating can be performed when the slab S is reciprocated by a distance corresponding to an odd multiple of the heating length Lc of the induction heating device 22 in the heating equipment 20 as described later. Therefore, in practice, the heating length Lc only needs to be within a range of ± 20% with respect to the interval Ld of the induction heating device 22, and is within a range of ± 10%. More preferred.

  The induction heating device 22 is disposed between the adjacent conveyance rollers 16, and the pitch of the induction heating device 22 is preferably the same as the pitch of the conveyance rollers 16. Further, since the pitch of the induction heating device 22 is approximately twice the heating length Lc of the induction heating device 22, the conveyance roller 16 that supports the slab S is sufficiently separated from the induction heating device 22 to be protected from the thermal effect. Can do.

  The transport roller 16 is connected to a drive motor 32 via a free joint 30 and is configured to be able to rotate forward and reverse. Thereby, in the section where the plurality of induction heating devices 22 are arranged, the slab S is reciprocated in the forward direction from the continuous casting facility 12 toward the hot rolling facility 14 and in the reverse direction by the plurality of induction heating devices 22. The edge part of the slab S can be heated. Thus, the conveyance roller 16 constitutes a moving means for reciprocating the slab S during heating by the induction heating device 22.

  The conveying roller 16 as the moving means is configured to reciprocate the slab S in the heating facility 20 by a distance corresponding to an odd multiple of the heating length Lc in the forward direction and in the opposite direction. Thereby, since the different part of the slab S is heated by the induction heating device 22 when the slab S is substantially stopped due to the direction change of the slab S, the slab S can be heated uniformly over the entire length. In a more preferred form, the transport roller 16 is configured to reciprocate the slab S in the heating facility 20 in the forward direction and in the opposite direction by a distance corresponding to one time the heating length Lc. The reciprocating distance of the slab S is small, and the time required for heating the edge portion of the slab S can be shortened.

  Moreover, in the heating equipment 20 of this embodiment, as shown in FIG. 2, among the induction heating devices that operate when operating at least a part of the plurality of induction heating devices 22, the induction heating that is located at the most upstream in the conveying direction. When the length of the heating section from the device to the induction heating device located on the most downstream side is L, the length of the slab S is Ls, and the interval between the induction heating devices is Ld, the length L of the heating section is: It is preferable to set it as the range of Ls <= L <= Ls + Ld. In the case where there is only one type of slab S that performs edge heating in the heating facility 20, the number of induction heating devices 22 is determined so as to satisfy Ls ≦ L ≦ Ls + Ld with reference to the length Ls of the slab S. Further, the number of installed induction heating devices 22 can be minimized while achieving uniform heating over the entire length of the edge portion of the slab S. Alternatively, when performing edge heating of a plurality of types of slabs S having different lengths in the heating facility 20, the induction heating device 22 satisfies Ls ≦ L ≦ Ls + Ld based on the length Ls of the longest slab S. When the slab S shorter than the longest slab S is heated, the number of induction heating devices 22 used so that Ls ≦ L ≦ Ls + Ld is satisfied with reference to the length Ls of the slab S ( By determining the number of operating units), it is possible to minimize the power used while achieving uniform heating over the entire length of the edge portion of the slab S.

  With reference to FIG. 3, the heating method of the continuous casting slab of one Embodiment according to this invention using the heating equipment 20 of this embodiment is demonstrated. 3 (a) to 3 (e) each show a positional relationship in the transport direction between the slab and the induction heating device in each heating stage when the edge portion of the slab S is heated while transporting the slab S. FIG.

  As described with reference to FIG. 1 and FIG. 2, the slab heating method of this embodiment has a plurality of induction heating devices 22 between the continuous casting equipment 12 and the hot rolling equipment 14 at equal intervals in the conveying direction. Ld is disposed, and the slab S is reciprocated in the section of the heating equipment 20 in which the induction heating device 22 is disposed to heat the edge portion of the slab S. This is performed by a conveyance roller 16 that is arranged between adjacent induction heating devices 22 and that can be driven forward and backward.

  The conveyance of the slab S from the continuous casting facility 12 to the heating facility 20 and the conveyance of the slab from the heating facility 20 to the hot rolling facility 14 are performed at a speed faster than the reciprocating movement of the slab S during heating by the heating facility 20. Preferably, according to this, the temperature drop of the slab during conveyance from the continuous casting equipment 12 to the heating equipment 20 and from the heating equipment 20 to the hot rolling equipment 14 can be suppressed.

  In the slab heating method of this embodiment, first, the slab S cast by the continuous casting facility 12 is caused to enter the heating facility 20 as shown in FIG. The slab S is transported from the continuous casting facility 12 to the heating facility 20 at a relatively high speed (for example, 120 mpm), and the slab S is transported at a heating speed (for example, 3 mpm) until the slab S reaches a predetermined heating start position. To slow down. The shorter the time required for this deceleration is, the better. In this way, the temperature drop during conveyance can be suppressed. The time required for deceleration is preferably within 10 seconds, for example. In the illustrated example, the heating start position is a position where the leading end of the slab S coincides with the upstream end of the induction heating device 22 located on the most downstream side in the transport direction, and when the leading end of the slab S reaches this upstream end position or Immediately before that, the induction heating device 22 is energized, and the edge portion is heated while moving the slab S in the forward direction at a low speed (for example, 3 mpm).

  FIG. 3B shows a state in which the slab S is moved from the heating start position in FIG. 3A in the forward direction (downstream) by a distance corresponding to one time the heating length Lc of the induction heating device 22. Yes. Thereafter, the slab S is turned in the reverse direction (upstream side). With this change of direction, the slab S temporarily stops. At this time, the amount of heat generated in the portion of the edge portion of the slab S facing the induction heating device 22 becomes larger than that in the other portions.

  FIG. 3C shows a state in which the slab S is moved from the position shown in FIG. 3B to the upstream side by a distance corresponding to one heating length Lc of the induction heating device 22, that is, to the original heating start position. Show. Thereafter, the slab S is turned to the downstream side. With this change of direction, the slab S is temporarily stopped. At this time, the amount of heat generated in the portion of the edge portion of the slab S facing the induction heating device 22 is larger than that in the other portions. Since the slab S is not heated when the slab S is substantially stopped due to the change of direction, the variation in the amount of heat generated by the slab S due to the change of direction is offset, and the accumulated heat amount of the slab S becomes substantially uniform over the entire length. .

  Subsequently, as shown in FIGS. 3 (d) and 3 (e), the slab S is equivalent to one heating length Lc of the induction heating device 22 in the same manner as FIGS. 3 (b) and 3 (c). Inductive heating is performed by reciprocating the distance. The reciprocating speed (low speed conveyance speed) V and the number of reciprocations m of the slab S during heating by the heating equipment 20 are the heating time required to heat the edge portion of the slab S to a predetermined temperature, which is obtained in advance by actual measurement or the like. It can be determined so as to satisfy m × 2 × Lc ÷ V = t in relation to t. FIG. 3 (e) shows a state where the induction heating of the edge portion of the slab S is completed in the heating facility 20, and at this time, the heating is completed almost simultaneously over the entire length of the slab S. Is output to zero, and the slab S is withdrawn from the heating equipment 20 and conveyed to the hot rolling equipment 14 in the next step. At this time, the conveying speed of the slab S toward the hot rolling facility 14 is preferably larger than the reciprocating speed of the slab S being heated, and can be set to 120 mpm, for example.

  According to the slab heating equipment 20 and the heating method of this embodiment, a plurality of induction heating devices 22 are arranged at intervals in the transport direction, and the slab S is reciprocated in a section where the induction heating devices 22 are arranged. Since the edge portion is heated, it is possible to prevent the tip portion from being cooled until the heating of the tail end portion of the slab S is completed, and the necessary number of induction heating devices 22 to be installed. Can be reduced, and it is economical. In addition, by using the induction heating device 22, heating in a shorter time is possible as compared with the case of heating with a burner, and the temperature of the center portion in the width direction of the slab S decreases while the edge portion is heated. Can be suppressed. Further, the induction heating devices 22 are arranged at equal intervals Ld, the heating length Lc of each induction heating device 22 is made substantially equal to the interval Ld of the induction heating devices 22, and the slab S is heated to the heating length Lc in the heating facility 20. Since the edge portion of the slab S is heated by the plurality of induction heating devices 22 while reciprocating in the forward direction and the opposite direction by a distance corresponding to an odd multiple, the variation in the amount of heat generated due to the change of direction of the slab S is caused. By offsetting, the accumulated heat amount of the slab S can be made substantially equal over the entire length.

  Further, according to the slab heating equipment 20 and the heating method of this embodiment, the induction heating device 22 that is in the most upstream of the induction heating devices 22 that operates when at least a part of the plurality of induction heating devices 22 operates is used. When the length of the heating section from the apparatus 22 to the induction heating apparatus 22 located on the most downstream side is L, the length of the slab S is Ls, and the distance between the induction heating apparatuses 22 is Ld, the length of the heating section Since L is configured to satisfy the relationship of Ls ≦ L ≦ Ls + Ld, it is possible to minimize the number of installed or used induction heating devices 22 while realizing heating over the entire length of the edge portion of the slab S. it can.

  Furthermore, according to the heating equipment 20 and heating method of the slab of this embodiment, the conveyance speed of the slab S from the continuous casting equipment 12 to the heating equipment 20 and the conveyance speed of the slab S from the heating equipment to the hot rolling equipment 14 are as follows. In addition, since the reciprocating speed during heating of the slab S by the heating equipment 20 is set to be larger, the temperature drop of the slab S during conveyance other than during the heating of the slab S is suppressed, and the slab S is kept hot at a high temperature. It becomes possible to roll with the rolling equipment 14, and a high quality steel plate can be manufactured.

  FIG. 4 shows a slab heating facility 20 and a heating method of another embodiment according to the present invention. The slab heating facility 20 of this embodiment is a pusher in which the moving means reciprocates the slab S in the heating facility 20. 34. A pair of pushers 34 are arranged so as to sandwich the heating equipment 20 back and forth, and are configured to be able to advance and retract up and down via an elevating mechanism. When the slab S enters the heating equipment 20, the pushers 34 are retracted upward. The lower end of the slab S and the tail end of the slab S are directly pressed to repeatedly move the slab S back and forth by a distance corresponding to an odd multiple of the heating length Lc of the induction heating device 22 and retract upward after heating. Thus, the slab S can be carried out. The pusher 34 can be driven by, for example, a hydraulic cylinder, but the drive type is not limited to this. By using such a pusher 34, the direction of the slab S can be changed at an accurate position, so that the edge portion of the slab S can be heated more uniformly over the entire length. Moreover, the stop time of the slab S when switching the moving direction can be shortened, and the time required from the start to the end of heating can be shortened. During operation of the pusher 34, the slab S may be reciprocated by using the conveyance roller 16 connected to the drive motor 32 and capable of rotating in the forward and reverse directions. In this case, the pusher 34 and the transport roller 16 capable of rotating in the forward and reverse directions constitute a moving means of the present invention.

  Next, examples of the present invention will be described.

  In the first embodiment, the edge portion in the width direction of the slab S is heated by the plurality of induction heating devices 22 while reciprocating the slab S using the heating equipment 20 shown in FIG.

  In Example 1, the slab S has a thickness of 280 mm, a width of 1500 mm, and a length of 8000 mm. Immediately before entering the heating facility 20, the surface temperature of the center portion in the width direction of the slab S is 1100 ° C. The surface temperature was 950 ° C. The surface temperature was measured with a radiation thermometer.

  The heating equipment 20 was composed of nine induction heating devices 22 arranged at equal intervals in the transport direction. The pitch of the induction heating device 22 is the same as the pitch of the conveying rollers 16 and is 1000 mm. The interval Ld between the induction heating devices 22 was 500 mm. The induction heating device 22 has an effective heating length of a length Lc in the transport direction, and in this embodiment, the induction heating device 22 is set to 500 mm which is equal to the interval Ld of the induction heating device 22. Therefore, the length L of the heating section, which is the distance from the induction heating device 22 located on the most upstream side in the conveying direction to the induction heating device 22 located on the most downstream side, is 8500 mm and satisfies Ls ≦ L ≦ Ls + Ld.

  Each induction heating device 22 is obtained by winding a coil conductor 26 around the portions of the C-type iron cores 24a and 24b in which the portions facing the edge portion of the slab S are separated by about 350 mm, the drive frequency is 300 Hz, and the slab S The pair of two coil conductors 26 that heat the edge in the width direction is taken as one, the output of each is 1 MW, and the total of the pairs is 2 MW.

  In the first embodiment, the slab S is transported at a high speed of 120 mpm from the continuous casting facility 12 to the heating facility 20, and the leading end of the slab S is in the heating facility 20 at the heating start position (upstream of the induction heating device 22 at the most downstream in the transport direction). The speed was reduced to 3 mpm before reaching 300 mm to 0 mm on the front side of the side end), and the time required for this deceleration was within 10 seconds.

  When the slab S reaches the heating start position, the coil conductors 26 of the induction heating devices 22 are energized, and the slab S is forwarded by 500 mm corresponding to one time the heating length Lc of the induction heating device 22 and its reverse direction. The edge in the width direction of the slab S was heated while reciprocating to each other. In Example 1, the heating was completed by two forward feeds (forward feed) and two reverse feeds (back feed). The conveyance speed V (maximum value) during heating was 3 mpm.

  After the heating of the edge portion of the slab S in the two forward feeds and the two reverse feeds is completed, the induction heating device 22 is stopped, the speed is increased to 120 mpm, and the slab S is transferred to the hot rolling facility 14 in the next process. sent. It was 1100 degreeC when the surface temperature of the width direction edge part of the slab S immediately after completion of a heating was measured.

  And when the slab S was hot-rolled to the plate | board thickness of 3 mm with the subsequent hot-rolling equipment 14, and the hot-rolled coil was manufactured, since the temperature of the width direction edge part of the slab S was kept high, it was hot-rolled. No material abnormality occurred at the edge of the coil, and there was no difference in quality compared to a conventional hot rolled coil produced by rolling a slab heated in a slab reheating furnace before hot rolling.

  The second embodiment is different from the first embodiment only in that the heating equipment 20 shown in FIG. 4 is used and the slab S is reciprocated by the pusher 34 driven by the hydraulic cylinder regardless of the conveying roller 16 when the slab S is heated. .

  By using the heating equipment 20 of Example 2, the positioning accuracy at the time of changing the direction of the slab S becomes ± 10 mm, and the temperature distribution in the length direction of the edge portion of the slab S after heating by the heating equipment 20 is from Example 1. The thickness variation of the manufactured hot rolled coil was reduced to two thirds of the conventional hot rolled coil manufactured by rolling a slab heated in a slab reheating furnace before hot rolling. .

  FIG. 5 shows Comparative Example 1. Although the comparative example 1 manufactured the rolling coil using the same installation as Example 1, the reciprocation distance of the slab S at the time of the heating in the heating equipment 20 is twice the heating length Lc (500 mm) of the induction heating device 22 (1000 mm). In Comparative Example 1, when the same part was heated at the time of substantial stop accompanying the change of direction of the slab S, the part became a higher temperature than the other parts, and scale defects were generated at the edge part of the manufactured rolled coil. occured.

  By this invention, it became possible to provide the heating method and heating equipment of the continuous casting slab which can heat the edge part of the width direction uniformly over the full length of the continuous casting slab, and is economical.

DESCRIPTION OF SYMBOLS 10 Manufacturing equipment of hot-rolled steel sheet 12 Continuous casting equipment 14 Hot rolling equipment 16 Conveying roller 18 Water cooling equipment 20 Heating equipment 22 Induction heating device 24a, 24b Core material 26 Coil conductor 28 Output adjustment means 30 Free joint 32 Drive motor 34 Pusher

Claims (8)

A method for heating a continuous cast slab in which when a continuous cast slab cast by a continuous casting facility is directly fed and rolled by a hot rolling facility, the edge in the width direction of the continuous cast slab is heated before hot rolling the continuous cast slab Because
In the continuous casting slab transport path from the exit side of the continuous casting facility to the entrance side of the hot rolling facility, a plurality of induction heating devices that heat the edges in the width direction of the continuous casting slab are arranged at equal intervals in the transport direction. In addition, each induction heating device is provided with heating equipment having a heating length substantially equal to the interval between the induction heating devices,
In the heating facility, the widthwise edge portion of the continuous casting slab is heated by the plurality of induction heating devices while the continuous casting slab is reciprocated in the forward direction and the opposite direction by a distance corresponding to an odd multiple of the heating length. A method of heating a continuously cast slab characterized by the above.   In the heating facility, the widthwise edge portion of the continuous casting slab is heated by the plurality of induction heating devices while reciprocating the continuous casting slab in the forward direction and the opposite direction by a distance corresponding to one time the heating length. The heating method of the continuous casting slab of Claim 1 characterized by the above-mentioned.   Of the induction heating devices that operate when at least some of the plurality of induction heating devices are operated, the length of the heating section from the induction heating device located at the most upstream to the induction heating device located at the most downstream is L The length L of the heating section is determined so as to satisfy the relationship of Ls ≦ L ≦ Ls + Ld, where Ls is the length of the continuous casting slab and Ld is the interval between the induction heating devices. The heating method of the continuous casting slab of 1 or 2.   The continuous casting slab conveyance speed from the continuous casting equipment to the heating equipment and the continuous casting slab conveyance speed from the heating equipment to the hot rolling equipment should be larger than the reciprocating speed during heating of the continuous casting slab by the heating equipment. The heating method of the continuous casting slab as described in any one of Claim 1 to 3 characterized by these. When continuous casting slabs placed in the continuous casting slab transport path from the continuous casting equipment delivery side to the hot rolling equipment entry side are directly fed by the hot rolling equipment, the continuous A heating equipment for a continuous casting slab that heats a widthwise edge portion of the continuous casting slab before hot rolling the casting slab,
A plurality of induction heating devices that are arranged at equal intervals in the conveying direction of the continuous casting slab and heat the edge in the width direction of the continuous casting slab;
Moving means for reciprocating the continuous casting slab heated by the plurality of induction heating devices,
Each induction heating device has a heating length substantially equal to the interval between the induction heating devices,
The moving means is configured to reciprocate the continuous cast slab in the forward direction and the opposite direction by a distance corresponding to an odd multiple of the heating length of the induction heating device during heating of the continuous cast slab by the plurality of induction heating devices. Heating equipment for continuous cast slabs, characterized in that it is configured.   During the heating of the continuous casting slab by the plurality of induction heating devices, the moving means reciprocates the continuous casting slab in the forward direction and the opposite direction by a distance corresponding to one time the heating length of the induction heating device. It is comprised, The heating equipment of the continuous casting slab of Claim 5 characterized by the above-mentioned.   Of the induction heating devices that operate when at least some of the plurality of induction heating devices are operated, the length of the heating section from the induction heating device located at the most upstream to the induction heating device located at the most downstream is L And the length of the continuous casting slab is Ls, and the distance between the induction heating devices is Ld, the length L of the heating section satisfies the relationship Ls ≦ L ≦ Ls + Ld. 6. The continuous casting slab heating equipment according to 6.   The said moving means has a pusher which directly presses the front-end | tip and tail end of a continuous casting slab, and reciprocates, The heating apparatus of the continuous casting slab as described in any one of Claim 5-7 characterized by the above-mentioned.

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