JP3250818B2 - Operating method of heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace having two series of heating steps, in which a material to be rolled (hereinafter simply referred to as a heating piece) having a small heating load is charged into both heating steps in parallel heating treatment. After that, the present invention relates to a method of operating a heating furnace when a material to be rolled having a large heating load (hereinafter, simply referred to as a cold piece) is continuously subjected to parallel heating treatment.

[0002]

2. Description of the Related Art In recent steelworks, energy saving, labor saving, and high efficiency have been promoted by making each process continuous, and a slab cast by a continuous casting machine has a high temperature (hereinafter, referred to as a heating piece). The rate of charging into the heating furnace as it is is increasing. However, cast slabs that cannot be charged with hot slabs are cooled to cold slabs and loaded into a heating furnace as before.

[0003] As a method of operating a heating furnace for heating a cast piece in which a hot piece and a cold piece are mixed, for example, Japanese Patent Application Laid-Open No.
There is a proposal by JP-A-83228. This is because the processing capacity of the heating process using a heating furnace having two heating zones is ≧
In the case of the processing capacity of the rolling step, the operation is performed in only one series of heating zones, and in the case of the processing capacity of the rolling step> the processing capacity of the heating step, the operation is performed in both series of heating zones.

[0004]

However, Japanese Patent Application Laid-Open No.
According to the proposal of JP-A-3-83228, there is an energy saving effect, but a predetermined temperature (1250 ° C. to 950 ° C.) at the time of transition from a material having a small heating load such as a heating piece to a material having a large heating load such as a cold piece. The time difference of heating in (1) results in a loss of opportunity, and the effect of increasing the efficiency is not necessarily large. In other words, in the heating step in the hot rolling line, it is necessary to alternately heat the hot piece and the cold piece, and the processing capacity is inconsistent with the rolling step in which the processing capacity is relatively stable, and the following loss occurs. Produces.

[0005] That is, when the processing capacity of the heating step is lower than that of the rolling step, the processing capacity of the entire hot rolling line is limited by the heating capacity, and an opportunity loss occurs. In addition, when processing cold pieces continuously after processing the hot pieces, if the furnace temperature is set according to the cold pieces, the hot pieces will be overburned, and energy loss and adverse effects on quality are likely to occur. To avoid this, if the furnace temperature is lowered, a material delay in the rolling process occurs due to a time delay until the cold piece is heated to a predetermined temperature.

[0006]

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and has the following features. (1) The heating step of heating the material to be rolled is a first heating step and a first heating step. In a hot rolling line provided with two systems in two heating steps and a rolling mill for rolling a material to be rolled heated to a predetermined temperature in both heating steps, a material having a small heating load in both heating steps is followed by a furnace gap. When the rolled material having a large heat load is continuously subjected to the heat treatment, the material to be rolled having a large heat load is placed behind the material to be rolled having a small heat load previously inserted into the second heating step. Starting the loading, extracting the material to be rolled with a small heating load heated to a predetermined temperature from both series in accordance with the rolling pitch of the rolling mill, and the process of extracting the material to be rolled with a small heating load on the second heating step side. When the extraction is completed, the charged heating load The rolled material having a large heating load is retained in a furnace and heated, and the material to be rolled having a small heating load on the first heating step side is extracted according to the rolling pitch of the rolling mill, and the material to be rolled having a small heating load is extracted. Charging and the first
When the charging of the material to be rolled with a small heating load to the heating step is completed, the charging of the material to be rolled with a large heating load is started, and the extraction of the material to be rolled having a small heating load in the first heating step is performed. In addition, when the step of sequentially charging the material to be rolled having a large heating load and the extraction of the material to be rolled having a small heating load on the first heating step side are completed, the loaded material having a large heating load is removed. The step of holding and heating, and starting the extraction of the material to be rolled having a large heating load heated to a predetermined temperature on the side of the second heating step and charging the material to be rolled having a large heating load, the first heating A step of continuing until a predetermined number of rolled materials having a large heating load on the process side is heated to a predetermined temperature, and a second step when the predetermined number is heated to a predetermined temperature.
A method for operating a heating furnace, comprising a step of stopping extraction of a material to be rolled having a large heating load on a heating step side and starting extraction of a material to be rolled having a large heating load from the first heating step side.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 2, reference numeral 1 denotes a heating furnace, which is divided into a first heating step A and a second heating step B, each of which has heating zones C1 to C3 and D1 to D3, each of which can be independently controlled in temperature. The transport of the piece is controlled. Reference numeral 2 denotes a rolling mill that rolls the extracted slabs closer to the first heating step A and the second heating step B of the heating furnace 1.

In FIG. 1, a is 80 when charged into the heating furnace 1.
A heating piece having a temperature of 0 ° C. to 500 ° C., b is a cold piece having a temperature of 200 ° C. or less when charged into the heating furnace 1. In the figure, the right side of the heating furnace 1 is the extraction side, and the left side is the charging side. The heating furnace 1 in the heating step of the hot rolling line in which the cold pieces b and the hot pieces a coexist as described above uses the heating capability of the rolling mill 2 based on the cold pieces b having a large heat load. Designed to match the ability. For this reason, when heating the heating piece with a high heating furnace charging temperature, the heating capacity of the heating furnace is designed to have a large margin compared to the rolling capacity of the rolling mill.

Next, in both of the first heating step A and the second heating step B, the parallel heating treatment of the heating piece a
The operation of the heating furnace 1 at the time of shifting to the parallel heating process will be described. After the heating pieces a were charged into both the first heating step A and the second heating step B of the heating furnace 1 and subjected to parallel heating treatment, the slabs heated to a predetermined temperature were alternately extracted and rolled into a rolling mill 2.
[FIG. 1 (A)].

In order to load the cold piece b from this state, first, the cold piece b1 is rolled by the rolling mill 2 in order to compensate for the difference in the furnace time required for heating the cold piece b1 and the hot piece a to a predetermined temperature. The in-furnace time H required for heating to a predetermined temperature from the scheduled rolling time is calculated by the following equation (1). H = K × H ₀ × (t ² / t ₀ ² ) + α (1) where H _{0 is} the time required to heat the steel sheet having the reference plate thickness t ₀ to a predetermined temperature for each heating pattern, K: constant, t: plate thickness of cold piece b to be charged into the heating furnace, α: required retention time for quality (for soaking / diffusion). Then, the cold flakes b
The charging is started at a time retroactive to the above calculation time from the scheduled time at which the final heating piece a to be rolled to the heating step B is charged into the heating furnace 1. At this time, an appropriate in-furnace gap G1 (8 m corresponding to one zone length of the fuel control zone in the furnace length direction) is set to avoid interference between the heating conditions of the preceding heating piece a and the cooling piece b1 on the second heating step side B. Take [Fig. 1 (B)].

Further, the heating pieces a heated to a predetermined temperature are alternately extracted from both heating process sides A and B in accordance with the rolling pitch of the rolling mill. Then, the cold pieces b1 are alternately charged into the second heating step side B [FIG.
(C)]. The number of the hot pieces a and the cold pieces b1 to be charged alternately is limited by the material supply capacity on the loading side.
In this example, the charging table and the like are common, and the number is three every three because of the supply cycle time of the crane and the like. .

Further, when the heating piece a on the second heating step side B is extracted, and the heating piece a is only on the first heating step side A, the second heating step a is performed.
The transport control of the heating step B is stopped, the cold piece b1 is kept in the heating furnace 1 and heated to a predetermined temperature, and only the first heating step A extracts the hot piece a in accordance with the rolling pitch. [FIG. 1 (D)]. At this time, since the heating capacity of the heating furnace 1 is designed to have a large margin as compared with the rolling capacity of the rolling mill 2 as described above, there is almost no rolling waiting.

When the loading of the final heating piece a to be rolled into the first heating step A is completed, the second heating step B
In the same manner as described above, an appropriate in-furnace gap G2 is taken, and a cold piece b2 is charged from the charging side of the heating furnace 1 in accordance with the extraction of the hot piece a (FIG. 1, (E) (F)). At this time, the cold piece b1 charged in the third heating zone D3 on the second heating step side B at the scheduled extraction time of the final heating piece a on the first heating step side A at the scheduled extraction time from the first heating step side A. Is heated to a predetermined temperature.
Heating control is performed in the heating zone D3.

Thus, when the extraction of the final heating piece a on the first heating step side A is completed, the transport control on the step side A is stopped and the cold piece b2 is kept in the heating furnace 1 to reach a predetermined temperature. At the same time as the heating, the extraction of the cold pieces b1 on the second heating step side B is started, and the cold pieces b3 are charged without gaps in the furnace in accordance with the extraction [FIG. 1 (G)].

Next, the extraction of the cold pieces b1 only on the second heating step side B is performed in accordance with the rolling pitch [FIG. 1 (H)]. At this time, at least the third heating zone C of the first heating step A is set at the scheduled extraction time of the last cold piece b1 of the second heating step B.
The heating control is performed so that the cold piece b2 in FIG. 3 is heated to a predetermined temperature.

When the extraction of the cold pieces b1 of the second heating step B is completed, the extraction of the cold pieces b2 of the first heating step A is started in accordance with the rolling pitch. When the extraction of the cold flakes b2 is completed, the extraction is stopped (FIGS. 1, (I) and (J)).

Subsequently, the extraction of the cold pieces b3 of the second heating step B is started. When the cold pieces b2 of the third heating zone D3 are extracted, the extraction is stopped. b
2 and the cold flake b2 in the third heating zone C3 was started.
When extraction is completed, the extraction is stopped [Fig.
(K), (L)]. At this time, the cold pieces b4 to b7 are alternately charged from the charging side of the heating furnace 1 in accordance with the extraction of the cold pieces b2 and b3 heated to the predetermined temperature.

Then, the three heating zones D on the second heating step side B
The extraction of the cold flake b3 in 3 starts. Thereafter, the cold pieces b2 to b7 are alternately and repeatedly extracted from both the heating process sides A and B, and the operation shifts to the parallel operation of the cold pieces b9 (FIG. 1, (M),
(N), (O)]. In this way, both heating process sides A and B
When only the cold pieces b9 are obtained, the pieces are alternately extracted from the heating step sides A and B one by one as in the case of the warm pieces a.

In FIG. 1 (I) and thereafter, the cold pieces b 2,
In b3, the order of loading and the order of extraction have been switched,
Even if the order of extraction is changed within several ranges in a rolling lot of one piece of cold flake material, there is no major problem in rolling.

[0020]

As described above, according to the present invention, when the hot flakes are shifted to the cold flakes, the heating flakes and the cold flakes are not excessively burned and the burning is not delayed, and stable heating is performed according to the rolling pitch of the rolling mill. It is possible to extract from the furnace and supply it to the rolling mill, so that there is almost no need to wait for the material in the rolling process, and there are great effects such as effective rolling in terms of energy and quality. It is.

[Brief description of the drawings]

FIG. 1 is a simplified diagram showing a relationship between charging and extracting of a hot piece and a cold piece as one embodiment of the present invention.

FIG. 2 is a simplified diagram showing a relationship between a heating furnace and a rolling mill.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Rolling mill a Heating piece b Cold piece C1-C3, D1-D3 Heating zone G Furnace gap

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masakazu Shishido 1 Nishinosu, Oita, Oita City, Oita Prefecture Nippon Steel Corporation Oita Works (56) References JP-A-59-6324 (JP, A) 52-73110 (JP, A) JP 44-15047 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 9/00 101 C21D 1/00 112 C21D 11/00 105

Claims (1)

(57) [Claims] 1. A hot-rolling machine comprising two heating steps for heating a material to be rolled, a first heating step and a second heating step, and a rolling mill for rolling a material to be rolled heated to a predetermined temperature in both heating steps. In the line, when the rolled material having a large heating load is continuously heated by taking a gap in the furnace after the material to be rolled having a small heating load in both heating steps, the material is charged before the second heating step. Began loading of the material to be rolled having a large heat load behind the material to be rolled having a small heating load, and the material to be rolled having a small heating load heated to a predetermined temperature from both systems in accordance with the rolling pitch of the rolling mill. When the extraction process and the extraction of the material to be rolled having a small heating load on the side of the second heating step are completed, the charged material to be rolled having a large heating load is retained in a furnace and heated, and the first material is heated. Rolling mill for rolling material with small heating load on the heating process side The process of extracting the material to be rolled having a small heating load and extracting the material to be rolled having a small heating load upon completion of the charging of the material to be rolled having a small heating load to the first heating step is completed. Starting the charging of the material, sequentially charging the material to be rolled having a large heating load in accordance with the extraction of the material to be rolled having a small heating load in the first heating step; When the extraction of the material to be rolled having a small heating load is completed, the process of holding and heating the loaded material having a large heating load and heating the material to a predetermined temperature on the second heating step side have a large heating load. a process continued until charged with larger the rolled material of the heating load starts the extraction of the material to be rolled, a large predetermined number of the rolled material of the heating load of the first heating step side is heated to a predetermined temperature The predetermined number is heated to a predetermined temperature Heating, wherein the extraction of the material to be rolled having a large heating load on the side of the second heating step is stopped and the extraction of the material to be rolled having a large heating load is started from the side of the first heating step. How to operate the furnace.