JP2622457B2 - Heating furnace for endless rolling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heating furnace for endless rolling.

[0002]

2. Description of the Related Art Conventionally, when hot rolling a slab, slabs extracted from a heating furnace are rolled one by one to form a strip. However, the leading end and the trailing end of the strip are liable to cause line trouble. It is known that the truncation of the leading end and the trailing end due to a product defect occupies a large ratio with respect to the stationary part and lowers the yield. In order to solve this, for example, Japanese Patent Application Laid-Open No. 55-22465,
As disclosed in Japanese Patent Application Laid-Open No. 3-13896, so-called endless rolling is employed, in which a rear end of a preceding material to be rolled and a front end of a subsequent material to be rolled are sequentially joined and rolled.

On the other hand, reduction of calorific value per unit in the heating furnace,
In order to improve the yield, a so-called direct-feed rolling technique is employed in which a high-temperature slab supplied from a continuous casting line is charged into a heating furnace within a short time, or is directly used for rolling. This is described in, for example, “Iron and Steel Association, 2nd Edition, Recent Hot Strip Manufacturing Technology in Japan (P.42).
-) S62 / 8 ". Simultaneously carrying out the endless rolling technology and the direct rolling technology,
Reduction of heat intensity, improvement of product yield, improvement of product quality,
Or, it is preferable in all aspects such as reduction of line trouble.

[0004]

SUMMARY OF THE INVENTION In a heating furnace that operates in combination of direct rolling and endless rolling, a slab supplied from a continuous casting line is immediately received.
On the other hand, to match very high efficiency endless rolling,
The slab must be extracted from the furnace so that the slab can be quickly supplied to the rolling line according to the rolling pitch. In a heating furnace corresponding to such a requirement, the in-furnace transfer device is divided into a heating zone and an extraction zone so that the largest possible endless batch can be stored in the extraction zone. Can operate independently.

However, if endless rolling and direct-feed rolling are simultaneously performed in a heating furnace having a two-piece in-furnace transfer device, a situation may arise in which any of the conditions is not satisfied. This means that while extracting the preceding endless batch for rolling, the trailing endless batch is stopped, and the trailing end of the trailing endless batch can enter the heating zone during its downtime And heating time is insufficient.

In order to solve this inconsistency, the present inventors divided the in-furnace transfer device into two in the longitudinal direction of the furnace and divided it into a slab heating zone and a high-speed slab extraction zone. At least equal to the length of the high-speed extraction zone. Even in this case, a charging beam stopping time occurs on the charging side, during which time the slab supplied from the continuous casting line cannot be charged into the heating furnace. As a result, there is a problem that the temperature of the high-temperature slab decreases while waiting for charging outside the furnace, and the fuel consumption rate of the heating furnace deteriorates.

The present invention is applied to a heating furnace for slab rolling, which receives a direct-feed slab from a continuous casting line, divides a walking beam into multiple parts, and performs batch heating in an extraction zone for each endless rolling lot. It is an object of the present invention to solve the above problems.

[0008]

The present invention has the following technical means to solve the above problems.
That is, in the above heating furnace, the stroke in the furnace of the slab charging machine is set to L in the following equation. L ≧ (τ + (E−ΣW) / V) × N × W where τ: Rolling time for one endless rolling (Hr) E: Length of extraction zone (m) ΣW: Total slab width for one endless rolling (M) W: slab width (m) V: slab transfer speed (m / Hr) N: number of slabs supplied from continuous casting line (lines / Hr).

[0009]

The slab supplied from the continuous casting line can be charged into the furnace when the walking beam on the charging side is stopped by extending the in-furnace stroke of the slab charging machine of the heating furnace. The required stroke at this time is the total width of the slab supplied within the walking beam stop time. The charging-side walking beam stop time (T) is: T = (endless rolling time τ) + (time t from when the last slab of the next lot reaches the extraction zone to when the most advanced slab reaches the extraction end). . This t becomes t = (E−ΣW) / V. Here, E: length of extraction zone (m) ΣW: total slab width per endless rolling (m) V: slab conveyance speed (m / Hr)

The required stroke (L) is as follows: L ≧ loading side walking beam stop time (T) × number of slabs supplied per unit time (N) × slab width (W) = (τ)
+ (E−ΔW) / V) × N × W By setting the stroke of the slab charging machine to L or more,
The slab supplied from the continuous casting line can be charged into the furnace while the charging side walking beam is stopped,
The temperature drop of the slab is eliminated, and deterioration of the fuel consumption rate can be prevented.

[0011]

EXAMPLE An example of the present invention shown in FIG. 1 was operated under the following conditions. FIG. 1 is a schematic longitudinal sectional view of the heating furnace of the embodiment. The heating furnace 1 has a heating device 2, and the slab 4 is charged from a charging end 6 into a heating zone 11 by a charging machine 7. The walking beam 3 is divided into an extraction zone side walking beam 3a and a charging zone side walking beam 3b. Walking beam 3 on the extraction zone side
In a, a slab is loaded with one lot of continuous rolling, that is, one endless batch, and the heated one endless batch is quickly discharged.

Extraction zone length E: 16.1 m (maximum size of endless batch) ΣW: 16.1 m V: 1.5 mm / min = 90 m / Hr W: 1.28 m τ = (16.1 m / 1. 28m) × 0.214Hr =
0.27Hr N: 25.2 pieces / Hr (continuous casting line 480 tons / H
Then, the required stroke (L) is 8.7 m.

A charger is used as a charging machine, and the stroke is 9 m. 1, the length E of the extraction zone 10 was 16.1 m, the length F of the heating zone 11 was 16.1 m, and the charger stroke 1 was 1. As shown in FIG.
The stroke L of No. 2 was 9 m. The charging side 9m in FIG.
Normally, an empty furnace was used, and the slab was charged to the front by a charger when the charging-side walking beam was stopped. According to the embodiment, there was no slab charging waiting time.

In the furnace shown in FIG. 1, when the stroke in the charger furnace was 1.3 m (stroke capable of loading only one slab into the first inlet), the holding time outside the furnace was 0.27 hr. Inevitably, at this time, the slab temperature drop is about 90 ° C, and the unit fuel consumption is 13 × 10 ³ kca
Although this was worsened by 1 / ton, it could be reduced to zero in the embodiment.

[0015]

According to the present invention, the slab supplied from the continuous casting line can be charged into the furnace during the time when the charging-side walking beam stops, and the slab temperature can be prevented from lowering due to air cooling outside the furnace. Fuel intensity is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a heating furnace according to an embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Heating device 3 Walking beam 4 Slab 5 Extraction side 6 Charging side 7 Charger 10 Extraction zone 11 Heating zone 12 Charger stroke

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuaki Nomura 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Corporation Chiba Works (72) Inventor Toshisada Takechi 1 Kawasaki-cho Chiba-shi Kawasaki Steel Corporation Chiba Works (56 References JP-A-1-200189 (JP, A) JP-A-3-223415 (JP, A)

Claims (1)

(57) [Claims] 1. A heating furnace for slab rolling, which receives a direct-feed slab from a continuous casting line and batch-heats in an extraction zone for each endless rolling lot, wherein a heating beam is divided into a plurality of walking beams. A heating furnace for endless rolling, wherein a stroke in the furnace is represented by L in the following formula. L ≧ (τ + (E−ΣW) / V) × N × W where τ: Rolling time for one endless rolling (Hr) E: Length of extraction zone (m) ΣW: Total slab width for one endless rolling (M) W: slab width (m) V: slab transfer speed (m / Hr) N: number of slabs supplied from continuous casting line (pieces / Hr)