JP5526648B2 - Metal slab heating method - Google Patents

Description

  The present invention relates to a method for heating a metal slab for charging a metal slab (for example, a steel slab) before hot rolling into a heating furnace and heating it.

  Conventionally, in a steel hot rolling process, a continuously cast steel slab (steel slab) is cooled to room temperature, charged in a heating furnace, and heated to a temperature suitable for rolling.

  On the other hand, in recent years, in order to reduce the basic unit of fuel, DHCR (Direct Hot Charge Rolling) or HCR (HCR), which continuously heats a continuously cast steel slab into a heating furnace without cooling to room temperature, is cooled. Hot Charge Rolling is being implemented.

  However, the furnace slab charging temperature of the steel slab in this case has a difference (variation) of approximately 300 ° C. to 900 ° C. When a steel slab having such a large variation in the charging temperature is charged into the heating furnace as it is. Therefore, it is necessary to heat the low temperature steel slab from the steel material to a preset target temperature, and at the same time, the high temperature steel slab in the furnace is heated for a long time after reaching the target temperature. Deterioration of the unit is inevitable.

  Therefore, in order to cope with this problem, in Patent Document 1, the temperature of the steel slab before being charged into the heating furnace is measured, and the steel slab is classified according to the range of the target temperature based on the measured temperature value. However, only the steel slabs within the target temperature range are charged into the designated heating furnaces, thereby reducing the fuel consumption rate.

JP-A-1-294820

  However, as in Patent Document 1, individual steel slabs are classified into target temperature ranges based on temperature measurement values, and only steel slabs within the target temperature range are charged into designated furnaces. In the technology, steel slabs deviating from their target temperature range had to be allowed to cool and wait until they were close to room temperature, then charged in a heating furnace and heated, and had a temperature of several hundred degrees Celsius. There is a problem in that the amount of heat of the steel slab cannot be effectively utilized and the amount of heat to be heated again to an appropriate temperature is required, leading to deterioration of the fuel consumption rate. In addition, the productivity of the hot rolling line is lowered by causing some of the steel slabs to stand by until they reach room temperature.

  The present invention has been made in view of the circumstances as described above, and in the hot rolling line, when a metal slab (for example, a steel slab) is heated in a heating furnace, the reduction of the fuel consumption rate and the hot rolling line are achieved. It is an object of the present invention to provide a method for heating a metal slab capable of improving the productivity.

  In order to solve the above problems, the present invention has the following features.

  [1] When the metal slab is heated in the heating furnace, a preheating device for preheating the metal slab is installed, and the temperature of the metal slab to be charged in the heating furnace is set in advance from the material of the steel material. When the temperature is outside the target temperature range, the temperature of the metal slab is set within the target temperature range by the preheating device and then charged into the heating furnace.

  [2] The method for heating a metal slab according to [1], wherein the range of the target temperature is a temperature range within ± 100 ° C. with respect to a preset target temperature.

  [3] The method for heating a metal slab according to [1] or [2], wherein the preheating device is an induction heating device.

  [4] The method for heating a metal slab according to any one of [1] to [3], wherein the metal slab is a steel slab.

  In the present invention, when the temperature of the metal slab to be charged into the heating furnace is out of the preset target temperature range, the temperature of the metal slab is set within the target temperature range by the preheating device. After that, the metal slab that is out of the target temperature range as in Patent Document 1 is allowed to cool and stand by until it reaches room temperature, and then charged into the heating furnace. Therefore, it is possible to reduce the fuel consumption rate and improve the productivity of the hot rolling line.

It is a top view of the heating furnace vicinity for demonstrating one Embodiment of this invention.

  In the present invention, when a metal slab (for example, a steel slab) is heated in a heating furnace, a preheating device for preheating the metal slab is installed, and the temperature of the metal slab to be charged in the heating furnace is set. When the temperature is outside the target temperature range, the metal slab is heated by the preheating device to be within the target temperature range, and then charged into the heating furnace.

  An embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view of the vicinity of a heating furnace in one embodiment of the present invention. In FIG. 1, 1 is a preheating device, 2 is a steel slab, 3 is a transfer table, 4 is a loader, 5 is a charging table, 6 is an extraction table, and 7 is a heating furnace. Here, the heating furnace 7 includes three units of a first heating furnace 7a, a second heating furnace 7b, and a third heating furnace 7c.

  As a result, the high-temperature steel slab 2 conveyed from the continuous casting machine (not shown) or the like via the conveyance table 3 is weighed by the loader 4 and then via the charging table 5 to the heating furnace. 7 (first heating furnace 7 a, second heating furnace 7 b, third heating furnace 7 c), heated to an appropriate temperature, extracted from the heating furnace 7, and hot rolling mill via the extraction table 6 (Not shown).

  In addition, in this embodiment, for each of the first heating furnace 7a, the second heating furnace 7b, and the third heating furnace 7c, the target value (target charging temperature) of the charging temperature of the steel slab 2 and its allowable value are set. A temperature range is defined in advance, thereby defining a temperature range in which charging can be performed in each of the heating furnaces 7a, 7b, and 7c.

  For example, for the first heating furnace 7a, the target charging temperature is 400 ° C. and the allowable temperature range is ± 100 ° C., and for the second heating furnace 7b, the target charging temperature is 600 ° C. and the allowable temperature range is ± 100 ° C. In the third heating furnace 7c, the target charging temperature is 800 ° C., and the allowable temperature range is ± 100 ° C.

  Thereby, the temperature range in which the first heating furnace 7a can be charged is 400 ° C. ± 100 ° C. (that is, 300 ° C. to 500 ° C.), and the temperature range in which the second heating furnace 7b can be charged is 600 ° C. ± It becomes 100 ° C. (that is, 500 ° C. to 700 ° C.), and the temperature range that can be charged into the third heating furnace 7c is 800 ° C. ± 100 ° C. (that is, 700 ° C. to 900 ° C.).

  And the temperature of the steel slab 2 conveyed from a continuous casting machine etc. is measured, and the estimated charging temperature to the heating furnace 7a, 7b, 7c of the said steel slab 2 is outside the above-mentioned charging possible temperature range. In this case, the steel slab 2 is heated by the preheating device 1 so that the charging temperature of the steel slab 2 to the heating furnaces 7a, 7b, 7c is within the above-described charging possible temperature range. The furnaces 7a, 7b and 7c are charged.

  As a result, in this embodiment, the steel slab that is outside the range of the target temperature, as in Patent Document 1, is allowed to cool and wait until it is close to room temperature, and then is not charged into the heating furnace. Thus, it is possible to always effectively use the heat quantity of the continuously cast steel slab, and it is possible to reduce the fuel consumption rate and improve the productivity of the hot rolling line.

  In the above, if the allowable temperature range of the charging temperature to the heating furnaces 7a, 7b, 7c is too wide, the variation in the charging temperature becomes too large to prevent the deterioration of the fuel consumption rate. Although it is desirable to make it narrow, if too narrow, the steel slab which will remove | deviate from the charging possible temperature range will increase, and the heating expense of the preheating apparatus 1 will increase.

  In view of the above, the allowable temperature range of the charging temperature to the heating furnaces 7a, 7b, 7c is preferably within ± 100 ° C.

  Moreover, the heating furnace target charging temperature is not limited to 400 ° C., 600 ° C., and 800 ° C., respectively, but may be overlapped by adding an allowable temperature range, or may be a remote temperature. For example, 300 degreeC, 550 degreeC, and 800 degreeC may be sufficient.

  The preheating device 1 may be a burner heating device or the like, but an induction heating device may be used for efficient heating in a short time.

  Further, in this embodiment, the heating furnace 7 is constituted by three units of the first heating furnace 7a, the second heating furnace 7b, and the third heating furnace 7c, but the present invention is not limited to this, The case where the furnace is comprised by 1 unit | set, 2 units | sets, or 4 units | sets or more may be sufficient.

  And this invention is not limited to a steel slab, It can apply also to another metal slab.

  As Example 1 of this invention, the steel slab 2 was heated using the heating furnace 7 shown in FIG.

  At that time, as an example of the present invention, the steel slab 2 was heated based on the above-described embodiment of the present invention. That is, the temperature range that can be charged into the first heating furnace 7a is 400 ° C. ± 100 ° C., the temperature range that can be charged into the second heating furnace 7b is 600 ° C. ± 100 ° C., and the temperature can be charged into the third heating furnace 7c. The temperature range is set to 800 ° C. ± 100 ° C., and the estimated charging temperature to the heating furnaces 7a, 7b, 7c is out of the above-described charging temperature range for each steel slab 2 conveyed from a continuous casting machine or the like. In this case, the steel slab 2 is heated by the preheating device 1 so that the charging temperature of the steel slab 2 to the heating furnaces 7a, 7b, 7c is within the above-described charging possible temperature range. The furnaces 7a, 7b and 7c were charged.

  On the other hand, as a comparative example, the steel slab 2 was heated based on the technique described in Patent Document 1. That is, for each steel slab 2 conveyed from a continuous casting machine or the like, the steel slab 2 is classified according to the target temperature range based on the temperature measurement value of the steel slab 2 before charging into the heating furnace 7, Only the steel slab 2 within the target temperature range is charged into the designated heating furnaces 7a, 7b, and 7c, respectively, and the steel slab 2 outside the target temperature range is allowed to cool and stand by until it reaches near room temperature. After that, they were charged into the heating furnaces 7a, 7b and 7c and heated.

  Further, as a conventional example, each steel slab 2 conveyed from a continuous casting machine or the like was charged in a heating furnace 7 as it was and heated. Accordingly, the charging temperature of the steel slab 2 has a difference (variation) of approximately 300 ° C. to 900 ° C.

  As a result, when the fuel intensity of the conventional example was 1, the fuel intensity of the comparative example was 0.87, whereas the fuel intensity of the example of the present invention was further reduced to 0.80.

  Thereby, the effectiveness of the present invention could be confirmed.

1 Preheating device 2 Steel slab (steel slab)
DESCRIPTION OF SYMBOLS 3 Conveyance table 4 Loader 5 Loading table 6 Extraction table 7 Heating furnace 7a 1st heating furnace 7b 2nd heating furnace 7c 3rd heating furnace

Claims (4)

For more than 2 groups furnace having different charging possible temperature range, leave installed preheating apparatus 1 group for preheating the metal slab, the temperature of the metal slab, the heating furnace to charging try When the temperature of the metal slab is outside the chargeable temperature range, the temperature of the metal slab is set within the chargeable temperature range by the preheating device and then charged into the heating furnace. Heating method.   The method for heating a metal slab according to claim 1, wherein the range of the target temperature is a temperature range that is within ± 100 ° C. with respect to a preset target temperature.   The method for heating a metal slab according to claim 1, wherein the preheating device is an induction heating device.   The said metal slab is a steel slab, The heating method of the metal slab in any one of Claims 1-3 characterized by the above-mentioned.

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