JP5678581B2 - Walking beam furnace - Google Patents

Description

  The present invention relates to a technique for reducing a skid mark (deviation in the plate width average temperature of a plate thickness average temperature in a heated material) of a heated material such as a slab transported in the furnace in a walking beam type heating furnace.

  When a long material to be heated such as a slab is hot-rolled, the material to be heated is placed in a continuous heating furnace, reheated to a predetermined temperature, extracted, and rolled. As this type of continuous heating furnace, there is a walking beam type heating furnace. A conventional walking beam type heating furnace has a skid button and a fixed beam and a movable beam (walking beam) provided so as to extend along the furnace length direction are alternately provided in the furnace width direction. Then, the movable beam is moved up and down together with the support that supports the movable beam using a cam, and the heated material placed on the beam is conveyed by pulling the support in the furnace length direction with a hydraulic cylinder. ing.

Here, the walking beam heating furnace for heating the material to be heated to the rolling temperature has a furnace temperature exceeding 1000 ° C. For this reason, the fixed beam and the movable beam that support the material to be heated in the furnace are surrounded by a heat insulating material to cool the inside, and on each beam, the height (surface) is approximately 100 to 150 mm. A skid button having a pressure of 15 to 25 kg / cm ² is mounted, and the material to be heated is directly supported by the skid button.

  However, since the temperature of the skid button is affected by the water cooling of the beam, it is much lower than the temperature in the furnace. Therefore, the contact portion of the material to be heated with the skid button is lower in temperature than the other portions, and a so-called skid mark (deviation in the furnace width direction of the plate thickness average temperature in the material to be heated) occurs. And the skid mark generated at the contact portion with the fixed beam causes variations in product thickness and quality due to different deformation resistance during hot rolling.

  Therefore, regarding the elimination of the temperature deviation due to the skid mark between the beams, Patent Document 1 discloses a shape in which the beam (skid) is meandered in the furnace length direction. Further, in Patent Document 2, a method is adopted in which the movable beam is moved straight up from its original position and then translated obliquely forward, and the side wall of the furnace is also formed obliquely along the oblique direction of the movable beam to tilt the slab. There has been proposed a method of transporting in a row. Patent Document 3 discloses a walking beam heating furnace in which a movable beam and a fixed beam are composed of a plurality of beams meandering in the furnace width direction.

JP-A-57-177915 JP-A-3-226518 JP 7-97614 A

  However, regarding the elimination of the temperature deviation of the skid mark between the beams, Patent Document 1 meanders the beam in the furnace length direction. In comparison, the moving distance of the slab per movement by the movable beam is small. Therefore, the same part of the slab may be placed again on the same skid button during operation, and there is a problem that the skid mark cannot be completely eliminated.

  On the other hand, Patent Document 2 proposes a method in which the movable beam is moved straight up from its original position and then translated obliquely forward. In this way, the movable beam is skewed and the furnace body is inclined. Thus, in the method of transferring the material to be heated in an oblique direction, there is a problem that the furnace core becomes distorted, making it difficult to install in the space with the existing existing equipment, which is unrealistic.

  Further, in Patent Document 3, the movable beam and the fixed beam are constituted by a plurality of beams meandering in the furnace width direction. In this case, support columns for supporting the beams exist all over the lower space in the furnace. Therefore, the flame of the burner for heating the billet interferes with the lower support column. Therefore, there is a problem that an appropriate furnace temperature distribution cannot be ensured, and the support is burned by the flame of the burner, resulting in an extremely short life.

  Furthermore, as a problem newly noticed by the inventor, the generation of a skid mark is not only the heat removal by the skid button, but also the influence that the radiant heat from the flame of the burner is blocked by the shadow of the beam (hereinafter referred to as the influence of “shadow”). Strongly called). In particular, when heating a material to be heated in a walking beam heating furnace, the portion where the material to be heated becomes a “shadow” is such that the longer the distance between the beams in the furnace width direction and the more uniform the beams are arranged. It becomes smaller and the skid mark is also reduced. For this reason, when designing the heating furnace, it is important to make the distance between the beams as large as possible.

That is, the skid mark depends on (1) the influence of “shadow” depending on the cross-sectional area of the beam to be water-cooled and the distance between the fixed beam and the movable beam, and (2) heat removal by the skid button, The temperature, the contact width between the heated material and the skid button, and the contact time are also affected.
Therefore, the present invention has been made paying attention to such problems, and can reduce the influence of “shadow” in particular compared with the conventional walking beam, thereby reducing the skid mark. It aims at providing a type heating furnace.

  In order to solve the above-described problems, the present invention alternately places a material to be heated charged in a furnace on a stationary beam and a movable beam that support the material, and toward the extraction port while being heated by a burner. In the walking beam type heating furnace to be transported, the fixed beam is arranged so as to extend along the transport direction (furnace length direction) of the material to be heated, and the movable beam is in a direction orthogonal to the fixed beam (furnace It is arrange | positioned so that it may extend along a width direction).

  According to the walking beam type heating furnace according to the present invention, the fixed beam in the walking beam type heating furnace is arranged so as to extend along the conveying direction (furnace length direction), and the movable beam is arranged in a direction orthogonal to the fixed beam ( By arranging to extend along the furnace width direction, the radiant heat from the burner flame is not easily blocked by the movable beam, and even if the radiant heat from the burner flame is blocked by the movable beam, it is movable. Since the beam is arranged in a direction orthogonal to the fixed beam (furnace width direction), radiant heat from the burner flame is uniformly blocked. As a result, since the deviation in the furnace width direction of the plate thickness average temperature becomes uniform, the influence of “shadow” can be particularly reduced as compared with the conventional case, and thereby the skid mark can be reduced. In addition, it is more preferable to reduce the influence of the “shadow” if the burner is attached to a position between the movable beams adjacent to each other in the furnace length direction on both sides in the furnace width direction.

Here, in the walking beam type heating furnace according to the present invention, if the fixed beam position is shifted by a certain amount in the furnace width direction in the middle of the conveying direction of the material to be heated, the radiant heat from the flame of the burner is caused by the beam. The influence of the “shadow” to be blocked can be further reduced. Therefore, it is possible to further reduce the skid mark, which is extremely effective in practical use.
Further, according to the configuration of the present invention, since only a fixed beam can be arranged in the longitudinal direction of the heating furnace, the distance between the skids contacting the heated material for every stroke of the heated material in the furnace Can be increased to, for example, about twice the conventional value. Therefore, the skid mark can be remarkably reduced as compared with the conventional case.

  As described above, according to the present invention, it is possible to provide a walking beam heating furnace that can reduce the influence of “shadows” as compared with the prior art, and thereby can reduce skid marks.

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view of the walking beam type heating furnace which concerns on this invention, (a) shows the standby state in which a movable beam is located in the last part, (b) is a movable beam in the uppermost part and the foremost part. The moving state which is located is shown. It is a cross-sectional view of the walking beam type heating furnace according to the present invention, (a) shows a standby state in which the movable beam is located at the lowermost part, (b), the movable beam is located at the uppermost part. The moving state is shown. It is a top view of the conventional walking beam type heating furnace, The example of a standard arrangement | positioning of a movable beam and a fixed beam, and the example of a skid shift are shown. In the conventional walking beam type heating furnace, it is the figure (a) which shows the average temperature distribution (qualitative) in the thickness direction of a steel piece, and the schematic diagram (b) of a principal part cross section. It is a figure explaining the definition of a skid mark, and is the figure (a) which shows the average temperature distribution (qualitative) in the thickness direction of a steel piece, and the schematic diagram (b) of a principal part cross section. It is a figure explaining one Example of this invention compared with the conventional walking beam type heating furnace (example of FIG. 5), and is a figure which shows the average temperature distribution (qualitative) in the thickness direction of a steel piece ( It is the typical figure (b) of the conventional principal part cross section, and the schematic diagram (c) of the principal part cross section of the walking beam type heating furnace which concerns on this invention. It is a figure explaining the difference of the influence of the "shadow" of a beam in case a to-be-heated material receives radiant heat from the flame (heat source) of arbitrary positions, The figure (a) is an example in the conventional walking beam type heating furnace. (B) and (c) are examples of the walking beam type heating furnace according to the present invention, and (b) is a state where the movable beam does not block the radiant heat of the burner flame, (c) Indicates a state in which the movable beam blocks the radiant heat of the burner flame.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate.
As shown in FIG. 1, this walking beam heating furnace 1 (hereinafter also simply referred to as “heating furnace”) includes a plurality of fixed beams 3 and a plurality of movable beams each having skid buttons 3a and 2a at the top of the furnace. (Walking beam) 2 is provided. The plurality of fixed beams 3 are arranged so as to extend along the conveyance direction (furnace length direction) of the slab (material to be heated) S, while the plurality of movable beams 2 are orthogonal to the fixed beam 3 (furnace). (Width direction). In the present embodiment, as shown in FIG. 1 (a), the positions of the fixed beam 3 and the movable beam 2 are fixed in the furnace width direction in the middle of the conveying direction of the slab S (upper part in the figure). Combining shifted configurations.

  Around the heating furnace 1, a plurality of burners B are attached at predetermined positions on both sides in the furnace width direction, whereby the slab S to be conveyed is reheated to a predetermined temperature. Here, as the predetermined position, it is preferable that a burner B is attached at a position between the movable beams 2 adjacent in the furnace length direction. Then, the movable beam 2 is moved up and down, and the support of the movable beam 2 is moved forward in the transport direction, so that the slab S placed on the fixed beam 3 is transported forward.

  Specifically, as shown in FIG. 2, the fixed beam 3 of the heating furnace 1 is supported by a fixed beam column 6 erected on the furnace bottom 4 of the heating furnace 1. Further, the movable beam 2 is supported by a movable beam column 11 erected on a plate-like support 5 disposed below the furnace bottom 4 of the heating furnace 1. Both the movable beam 2 and the movable beam support 11 are protected by a refractory material so that they can withstand the high temperature in the furnace (1200 to 1300 ° C.), and the adjacent movable beams 2 are provided with cooling water channels 14, Cooling water is passed through the pipe-shaped inner surface.

  The movable beam 2, the movable beam support 11, and the support 5 are cams fixed to the drive shaft 9 when the motor 12 of the drive unit 7 is driven and the drive shaft 9 rotates via the speed reducer 8. The slab S on the fixed beam 30 is moved up and down by 10. Then, in accordance with the timing when the movable beam 2 lifts the slab S, the slab S is moved forward by pulling the support 5 forward with a hydraulic cylinder (not shown) in the transport direction. It has become. Next, when the cam 10 further rotates from this state, the movable beam 2 is lowered together with the movable beam support 11 and the support 5, and the heated material 31 on the movable beam 2 is lowered onto the fixed beam 3 again. The slab S in the furnace advances while being heated by the radiant heat from the flame F of the burner B while repeating such an operation.

Next, the operation and effect of this walking beam type heating furnace will be described.
In a conventional walking beam heating furnace, as shown in FIG. 3, a plurality of fixed beams 3 and movable beams 102 are arranged such that the longitudinal direction of the fixed beam 3 and the movable beam 102 extend along the furnace length direction, and the mutual mutual Since they are provided alternately in the width direction, as shown in FIG. 4A, there is a temperature difference between the portion of the movable beam 102 and the fixed beam 3 that hits the skid buttons 102a and 3a and the portion that does not hit.

  Here, as shown in FIG. 5, this temperature difference becomes smaller as the distance between adjacent beams in the furnace width direction is longer and in a uniform arrangement, as can be seen in comparison with FIG. (The furnace width direction deviation of the plate thickness average temperature in the material to be heated) is also reduced. Therefore, when designing a heating furnace, it is important to make the distance between beams in the furnace width direction as large as possible, but there is also a limit.

  Moreover, in the conventional walking beam type heating furnace, the fixed beam 3 and the movable beam 102 provided along the furnace length direction are alternately provided in the furnace width direction. Radiant heat is blocked by the conventional movable beam 102. For example, in FIG. 7A, a flame (F1 or F2) located on the left side of the movable beam 102 does not contribute to heating at a position on the right side of the movable beam 102 of the slab S which is a shadow of the movable beam 102. . Furthermore, the shadow range varies depending on the flame position (F1 or F2). Thus, when the radiant heat from the flame F of the burner B is interrupted by the conventional movable beam 102, the slab S is easily affected by the influence, and this temperature difference is caused when hot rolling is performed. Appearing as a difference in deformation resistance, it was a cause of fluctuations in thickness and width of a hot steel strip obtained by rolling.

  With respect to these problems, in the walking beam type heating furnace 1 shown in FIGS. 1 and 2 described above, the fixed beam 3 is arranged so as to extend in the conveyance direction (furnace length direction) of the slab S, while the movable beam 2 was arranged to extend in a direction orthogonal to the fixed beam 3 (furnace width direction). As a result, depending on the positional relationship between the movable beam 2 and the burner B, as shown in FIG. 7B, the radiant heat from the flame F of the burner B is not blocked by the movable beam 2 according to the present invention, so Hard to wake up.

  In addition, as shown in FIG. 7C, when the movable beam 2 is located at a position where the radiant heat from the flame F of the burner B is blocked by the movable beam 2 according to the present invention and is affected by the “shadow”. Even if it exists, since this movable beam 2 is arrange | positioned in the orthogonal direction (furnace width direction) with the fixed beam 3, the radiant heat from the flame F of the burner B will be interrupted | blocked by the movable beam 2 uniformly. Therefore, as a result, the deviation in the furnace width direction of the plate thickness average temperature is uniformly reduced, so that the influence of the “shadow” of the movable beam 2 can be reduced as compared with the conventional case. Skid marks caused by the influence of “shadow” 2 can be reduced.

  Furthermore, by arranging the fixed beam 3 in the heating furnace 1 so as to extend in parallel to the furnace length direction, as shown in FIG. 7B, only the fixed beam 3 is provided in the transport direction (longitudinal direction). Since it can arrange | position, the distance between the skid buttons 3a which contact the slab S for every stroke of the in-furnace transfer of the slab S can be extended to the conventional double. Therefore, the skid mark can be remarkably reduced as compared with the conventional case.

The results of the heat transfer simulation in the walking beam type heating furnace 1 are shown in FIG. 6 and Table 1 in comparison with a conventional walking beam type heating furnace (example of FIG. 5). The table shows the degree of quantitative skid mark reduction by heat transfer simulation.
Here, as shown in FIG. 6, the skid mark refers to the difference between the maximum value and the minimum value of the average temperature distribution in the thickness direction of the slab S between the skid buttons 3 a of the adjacent fixed beams 3. That is, in the figure, the difference between the maximum value C and the minimum value A in the prior art, and the difference between the maximum value C ′ and the minimum value A ′ in the present invention. As can be seen from the results shown in Table 1, by applying the present invention, it is possible to reduce the skid mark by about 20% compared to the prior art.

Further, in the present embodiment, a configuration in which the positions of the fixed beam 3 and the movable beam 2 are shifted by a certain amount in the furnace width direction in the middle of the conveying direction of the slab S is combined, so the skid button 3a of the fixed beam 3 and The position where the temperature is lowered due to contact with the slab S shifts. Therefore, it is possible to further reduce skid marks.
As described above, according to the walking beam heating furnace 1, skid marks can be significantly reduced as compared with the conventional case. The walking beam heating furnace according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, as in the conventional example shown in FIG. 3, the positions of the fixed beam 3 and the movable beam 2 are shifted by a certain amount in the furnace width direction in the middle of the conveying direction of the slab (material to be heated) S. Although described, the present invention is not limited to this, and a configuration shifted by a certain amount may not be adopted. However, in order to further reduce the influence of contact with the fixed beam 3, it is extremely effective in practice to employ such a configuration.

1 Heating furnace 2 Movable beam (walking beam)
DESCRIPTION OF SYMBOLS 3 Fixed beam 4 Furnace bottom 5 Support body 6 Fixed beam support | pillar 7 Drive part 8 Reducer 9 Drive shaft 10 Cam 11 Movable beam support 12 Motor 14 Cooling channel B Burner F Flame S Slab (heated material)

Claims (3)

In the walking beam type heating furnace in which the material to be heated placed in the furnace is alternately placed on the fixed beam and the movable beam that support this, and is conveyed toward the extraction port while being heated by the burner,
The fixed beam is arranged so as to extend along a conveying direction of the material to be heated, and the movable beam is arranged so as to extend along a direction orthogonal to the fixed beam. Beam type furnace.   The walking beam heating furnace according to claim 1, wherein the position of the fixed beam is shifted by a certain amount in the furnace width direction in the middle of the conveying direction of the material to be heated.   The walking beam heating furnace according to claim 1, wherein the burner is attached to a position between movable beams adjacent to each other in both the furnace width direction and the furnace length direction.

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