JP2011058014A - Skid button for skid beam of walking beam furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for reducing a situation in which a temperature lowers than a portion of a beam other than a skid beam because a bloom which is a material to be heated in contact with the skid beam in a walking beam type heating furnace is not sufficiently heated locally. To do.
SOLUTION: In a structure in which a periphery of a skid beam 2 of a walking beam type heating furnace is covered with a refractory 5, a height 4c of a skid button protruding upward from the skid beam 2 is made higher than a height of a conventional skid button 4b. In accordance with this heightened shape, the skid button 4a of the present invention corresponding to the position of the height 4b of the conventional skid button out of the height from the side of the horizontal line 6 passing through the center of the skid beam to the skid button 4 is shown. The skid button 4 in the skid beam 2 of the walking beam type heating furnace in which the periphery of the height position is covered with the refractory 5 as an inclined surface.
[Selection] Figure 2

Description

  In the present invention, when the bloom which is a cast slab is heated in a walking beam heating furnace in order to hot-roll, the local of the bloom which is a material to be heated in the skid beam of the walking beam heating furnace is obtained. The present invention relates to a structure of a skid button that reduces a decrease in temperature.

  When the cast bloom is heated by a walking beam furnace in order to hot-roll, the heated bloom heat is taken away by the cooling water flowing in the skid beam through the skit button of the walking beam furnace. For this reason, the temperature of the bloom contacting the skid button is locally reduced. Due to this temperature drop, a skid mark is generated in the low temperature part, and this skid mark is one of the causes of flaws in the next hot rolling. Therefore, the skid mark generated in the bloom was an important problem in quality assurance of the obtained steel material.

  In order to investigate and study the conventional blooming habits of the bloom, the surface temperature of the bloom extracted from the walking beam furnace was compared with that of the skid that was in contact with the bloom. The temperature of the bloom that was in contact with the bloom was about 96 ° C. lower than the temperature of the bloom that was in contact with the other part, and the billet wrinkle generation position after hot rolling of the extracted bloom was As can be seen in FIG. 1, it was concentrated on the part that was in contact with the skid portion of the bloom and was not sufficiently heated. The bloom surface temperature was measured with a radiation thermometer, and the occurrence of billet surface flaws was obtained by visual observation.

  From the results of the above investigations and examinations, for example, the following (1) can be taken as a reduction measure for solving the shortage of bloom heating in the low temperature part due to the temperature drop of the bloom part contacting the skid part of the walking beam type heating furnace. Although (3) can be considered, there are respective problems.

  (1) A method of further heating after extracting an object to be heated from a walking beam type heating furnace. However, this method causes a reduction in production capacity and increases costs.

  (2) A method of changing the holding time for the temperature rise of the object to be heated during conveyance in the walking beam type heating furnace. However, this method has little effect.

  (3) A method of reducing the cooling capacity in the walking beam heating furnace. However, if the cooling capacity is reduced, there is a problem of shortening the life of the refractory around the skid button and the beam.

  On the other hand, there is a method of adjusting the time during which the object to be heated is placed on the walking beam as a countermeasure for reducing the insufficient heating of the object to be heated such as bloom in the low temperature part of the skid part of the conventional walking beam furnace ( For example, see Patent Document 1.) Furthermore, a method has been proposed in which a burner that locally heats the lower surface of the material to be heated of the walking beam heating furnace is installed to heat the low temperature portion of the material to be heated (see, for example, Patent Document 2).

JP 59-96214 A JP 7-216443 A

  The problem to be solved by the present invention is that the bloom, which is a material to be heated in contact with the skid beam in the walking beam heating furnace, is not sufficiently heated locally, so that the temperature is lower than that of the beam portion other than the skid beam. It is to provide a means to reduce the situation.

  The means of the present invention for solving the above-mentioned problem is that, as shown in FIG. 2, the invention of claim 1 is a refractory covering the periphery of a skid beam having a skid button on the upper surface of a walking beam type heating furnace. In the structure. In this structure, the shape of the refractory formed below the horizontal line passing through the center of the skid beam is formed on the lower half of the periphery of the skid beam following the shape of the skid beam. Further, an inclination angle of the refractory formed continuously above the refractory and above the horizontal line passing through the center of the skid beam is formed at an angle of 60 ° with the horizontal line, and the periphery of the skid beam toward the upper end of the skid button. The refractory is to be formed on the upper half side. Furthermore, the skid button in the skid beam of the walking beam heating furnace is characterized in that the height of the upper end surface of the refractory formed in the upper end direction of the skid button is set to a half height position of the skid button. .

  In the invention of claim 2, the height of the upper end of the skid button is twice the height of the upper end of the conventional skid button. The skid in the skid beam of the walking beam type furnace of the means of claim 1 Button.

  According to a third aspect of the present invention, the inclination angle of the refractory is formed at an angle of 60 ° above the horizontal line passing through the center of the skid beam. It is a skid button in the beam.

  By adopting the above structure means, as shown in FIG. 3, the scale deposited on the skid beam is only thinly coated on the upper end side of the skid button in a thin annular shape, making it difficult to deposit in a wide annular shape. . By modifying the shape of the refractory in this way, the amount of radiant heat radiated from the burner below the skid button was increased by reducing the heat removal due to the cooling zone in the beam. That is, since the radiant heat from the burner to the lower part of the bloom is less affected by the scale accumulated around the refractory and the skid button, the scale is formed on the refractory as shown in FIG. It becomes difficult to deposit and the amount of radiant heat increases, and as a result, the temperature of the skid button increases.

  By using the above-mentioned means, the scale deposited on the beam is only thinly coated on the upper end side of the skid button in an annular shape, making it difficult to deposit thickly. As a result, the scale deposited around the refractory and the skid button By reducing heat removal due to the cooling zone in the beam, the amount of radiant heat from the burner to the skid increases, and the temperature of the bloom, which is the heated object of the skid button, increases. As a result, the occurrence of wrinkles on the billet, which is a product after rolling, at the contact portion of the skid beam is reduced.

It is a figure which shows the relationship between the generation | occurrence | production position of the wrinkles in the contact part of a bloom and a skid beam, (a) shows the relationship between the contact part of a bloom and a skid beam, (b) is the frequent occurrence of wrinkles on the lower surface side of the bloom. It is a figure which shows a part typically. 1 shows a skid beam and a skid button coated with a refractory, wherein (a) shows a conventional skid beam and skid button, and (b) shows a skid beam and skid button according to the present invention. It is a figure which shows the relationship of the scale deposited on the skid beam and the skid button shown in FIG. 2, (a) is a conventional relationship, (b) is the relationship of this invention. It is a figure which shows the relationship between the contact part of a bloom and a skid beam.

  Embodiments of the invention will be described below with reference to the drawings and tables. The height 4c of the skid button 4 of the means of the present invention shown in FIG. 2B is increased to 140 mm from the height of the conventional skid button 4 shown in FIG. The shape of the surrounding refractory 5 for heat insulation is set to a refractory forming angle 5a from the position of the refractory 5 on the side of the lower end of the skid button 4 which is the conventional shape shown in FIG. As shown in FIG. 2 (b), the present invention is formed around the skid beam 2 on the horizontal line 6 passing through the center of the skid beam. The refractory formation angle 5a was modified from the position of the refractory 5 for heat insulation to 60 °. As a result of this modification, compared with the top deposition width 7a of the scale 7 deposited around the top of the skid button 4 of the conventional skid beam 2 shown in FIG. 3 (a), the present invention shown in FIG. The top deposition width 7a of the scale 7 deposited around the top of the skid button 4 of the skid beam 2 is narrowed.

  As described above, the height of the skid button 4 of the present invention is increased, and the shape of the heat-insulating refractory 5 around the skid beam 2 is improved as shown in FIG. And the skid button 4 in the relationship between the (A part) of the non-beam part 2c that is between the two fixed skid beams 2b on the left and right (part B) and the movable skid 2a (part C). As shown in the Bloom temperature distribution in the cross-sectional average of Table 1, the temperature drop of the bloom 1 in the skid beam 2 is caused by the temperature difference between (A part) and (B part) of the skid beam 2 having the conventional skid button 4b. 64 of the improved extraction temperature, which is the temperature difference between (A part) and (B part) of the skid beam 2 having the raised skid button 4a of the present invention from the pre-improvement extraction temperature of 96 ° C. Up to ℃ Was Hesi.

  As described above, the temperature difference between (A part) and (B part) of the improved extraction temperature of the skid beam 2 having the skid button 4a was reduced to 64 ° C. as described above. As a result, the number of billets after rolling obtained by further rolling one bloom at the skid mark portion of this portion was five. When observing the surface flaws for each of the five billets, as shown in Table 2, the average flaw occurrence rate is 2.45 to 1.46 in the case of SCr case-hardened steel as defined in JIS. The average of the flaw occurrence rate is reduced from 1.38 to 0.81 in the case of SCM case-hardened steel specified in JIS, that is, about 41%, in S53C specified in JIS. The average wrinkle generation rate decreased from 0.54 to 0.24, that is, about 56%. In addition, the surface temperature of said bloom was measured with the radiation thermometer, and the generation | occurrence | production number of surface flaws was obtained visually.

DESCRIPTION OF SYMBOLS 1 Bloom 1a Abutting part with the moving beam of Bloom 1b Abutting part with the fixed beam of Bloom 1c Non-contacting part with the beam of Bloom 2 Skid beam 2a Movable skid beam (C part)
2b Fixed skid beam (part B)
2c No-beam part (A part)
3 Slowly-occurring part 4 Skid button 4a Skid button 4b of the present invention 4b Conventional skid button 4c Skid button height 5 Refractory 5a Refractory formation angle 6 Horizontal line passing through the center of the skid beam 7 Scale 7a Scale top accumulation width

Claims (3)

  In a structure where the periphery of the skid beam having a skid button on the upper surface of the walking beam type furnace is covered with a refractory, the shape of the refractory formed below the horizontal line passing through the center of the skid beam is imitated with the shape of the skid beam. Formed on the lower half of the periphery of the beam, and formed by inclining the refractory above the horizon passing through the center of the skid beam, and in the periphery of the skid beam toward the upper end of the skid button. Walking beam type heating characterized in that the refractory is formed on the upper half side, and the height of the upper end surface of the refractory formed in the upper end direction of the skid button is set to a half height position of the skid button. Skid button in furnace skid beam.   The skid button in the skid beam of the walking beam furnace according to claim 1, wherein the height of the upper end of the skid button is twice the height of the upper end of the conventional skid button.   The skid button in the skid beam of the walking beam type heating furnace according to claim 1 or 2, wherein an inclination angle of the refractory is formed at an angle of 60 ° above a horizontal line passing through a center of the skid beam.

Images