JPS6254025A - Method for controlling heating of steel material heating furnace - Google Patents

Abstract

PURPOSE:To heat steel materials under the optimum conditions and to increase efficiency and productivity by correcting the residence time of the steel materials in a heating furnace in accordance with average value calculated from the difference between the actual rolling time of the steel materials and the estimated rolling time. CONSTITUTION:Average value is calculated from the difference between the actual rolling time of a group of rolled steel materials and the estimated rolling time. In accordance with the average value, the residence time of the steel materials in a heating furnace is corrected in succession. The steel materials are heated to the desired temp. during the residence time and taken out. The heating furnace is controlled with a computer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heating control method for a steel heating furnace, and more specifically, a continuous heating furnace and a rolling mill are closely related to achieve high production and
This invention relates to a continuous heating furnace operating method that uses computer control to set and control optimal heating time, which is suitable for increasing production with high efficiency.

) In the heating furnace control, the time during which the steel material to be heated (hereinafter referred to as slab) is charged and the slab exists in the heating furnace (hereinafter referred to as the furnace time) It is very important to accurately understand the temperature and perform stable and good heating control. When a slab is charged into a furnace, heated until it reaches the set WL degree, and then extracted from the furnace, the in-furnace time during which the slab is present in the heating furnace is the time when the slab is already in the furnace when it is charged. Since it is given by the sum of the extraction pitches of all slabs, furnace temperature control is performed after determining the extraction pitch of the slabs.

Conventionally, the extraction pitch is determined by the requirements of the rolling process, and the heating furnace controls the furnace/FA in accordance with this extraction pitch.

Therefore, it is considered that the extracted pitch largely depends on the rolling time and the like in the rolling process. As a prior art that can be referred to regarding this relationship, Japanese Patent Laid-Open No. 57-73129 discloses a heating furnace control device that predicts the furnace time based on the predicted extraction pitch of slabs in a continuous hot rolling line. ing.

Furthermore, Japanese Patent Application Laid-Open No. 59-107715 discloses a method for determining the minimum rolling pitch in continuous rolling equipment.

However, it cannot be denied that these controls are based on predictions and lack correction and learning functions based on actual rolling operations.

Normally, the furnace temperature setting for each furnace zone of a continuous heating furnace that heats steel materials,
In heating furnace control, which involves setting combustion conditions and calculating slab heating temperature, the accuracy of predicting the slab in-furnace time has a considerable influence on the computer control of the heating furnace.

Conventionally, the method for predicting the in-furnace time of slabs from charging to extraction in multiple continuous heating furnaces involves predicting the rolling time required for individual rolling of all slabs located on the extraction side from the target slab to be predicted in the furnace. Therefore, this sum was regarded as the in-furnace time for heating the target slab in the furnace to the target temperature, and the setting was controlled.

This will be explained in more detail based on FIG.

Predicted in-furnace time Tn of the slab Sn on the charging port side of the heating furnace
When predicting the value of the slab Sn near the charging port in the furnace,
(n-,) slabs Sn + located closer to the extraction side
, Sn 2 . . . , tn ++ Δtn 2 . That is, when a thick plate is rolled using the number N of heating furnaces having approximately the same capacity, the predicted furnace use time Tn is expressed as (1).

However, it is preferable to apply this to N>1.

However, there is a difference αi between the predicted rolling time Δti of the target slab and the actual actual rolling time Δti of the target slab. Therefore, in the above equation (1), there is a total difference between the predicted in-furnace time Tn of the n target slabs and the actual actual furnace time Tn of the n target slabs.

[Problem that the invention seeks to solve]

In the heating furnace control that heats the slab in this way, there is a prediction error Σαi between the predicted rolling time predicted before rolling and the actual rolling time when the slab is in the furnace. However, since the rolling time was determined based on the predicted rolling time, it was a source of error in computer control.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned conventional problems, and the rolling mill and continuous heating furnace are organically linked to achieve high efficiency and high productivity, making it possible to obtain optimal operation of steel products. An object of the present invention is to provide a heating control method for a heating furnace.

Furthermore, the difference between the predicted in-furnace time Tn for heating the slab Sn to the target heating temperature in the heating furnace and the actual actual furnace time Tn for heating in the furnace, that is, the difference is predicted and corrected. The purpose of this study is to improve the control accuracy of continuous heating furnaces by computer control.

Structure of the Invention [Means and Actions for Solving Problems] The present invention provides a first method for controlling a heating furnace for heating rope by computer.
As shown in the figure, the time in the furnace until each slab is heated to the target temperature and extracted is calculated as follows: The above object is achieved by successively correcting the furnace time of the slabs on each side in the furnace and heating them using the average value of a group of differences from the total rolling time of the slabs.

In the present invention, the predicted in-furnace time is further corrected sequentially, so that the computer control of the heating furnace can be controlled optimally, that is, the furnace temperature setting, slab heating temperature, combustion condition setting, extraction pitch, etc. I can do it. Therefore, the plate rolling mill and the continuous heating furnace can be operated optimally and in conjunction with each other. The present invention will be explained in detail based on FIG. 1 and with reference to FIG. Step ■ Predicted rolling time of each slab on the extraction side of the target slab Sn to be predicted △
It, △it, △t, ... △t1-3 are determined.

Step (2) The sum Tn of predicted rolling times of individual slabs on the extraction side from the target slab Sn to be predicted is set as the actual furnace time Tn of the slab Sn and heated.

Tn=　Tn−△t1+△t　2　”’△jn−.

Step 2 Heat the slab and roll it at ti to each rolling time.

Step ■Rolled materials SR, SR,... that have already been rolled
Assuming that the actual rolling times of SRn are Δ1+, Δt, . . . , Δtn, the actual rolling times of a group of n rolled materials are determined.

Step ■Predicted rolling time △L1. Differences αR1, αR7 to αR between Δt, ~Δtn and the actual rolling time to ti
n is calculated, and these n rolled materials SR,, SR2 to SRn
The average value αR of the difference between the predicted rolling time and the actual rolling time Δt, to Δtn can be expressed as follows.

Step (2) Correct the predicted rolling time Δti of each slab using the average value αR of the difference between the predicted and actual rolling times of this group of n pieces of completed rolling.

That is, the predicted rolling times Δti to Δkn − of the slab extracted from the heating furnace and rolled are corrected by the average value αR of the differences.

Newly corrected predicted rolling time △ required for rolling the l, 2.3...(n-,)th slab extracted from the heating furnace
L+, △11. △l+, ”'△tn +,
△t1-△t, + aR...(3)-.

△t, -△t, + aR... (3) -2△t
3=△L3+ aR・・・・・・・・・(3)−3△
tn l-△tn ++ aR--...(3)
It becomes n +.

As described above, the predicted rolling times △L+, △L, ... △tn- obtained by sequentially correcting the rolling times of n pieces of a group that were rolled in advance (E) are successively corrected using the average value αR of the difference from the rolling time of E. , to correct the predicted in-furnace time Tn. In other words, for example, the predicted in-furnace time Tn of slab 5n-3n-7 near the furnace charging inlet is corrected.
After the new correction, nt is Tt+ = Tn+
(n −1) aR・−=−−(4) −n −+Tn
t=Tn++(n2)αR--(4)
n tTn-t-Tn -++ (n -3) (2R-
(4) −n −s.

Step ③ Each time the rolled material is rolled, steps ② to ③ are repeated for correction.

Here, when calculating the above-mentioned αR, the number of target slabs is n for each rolling, for example, several tens, and the next rolled material S
Rn++ is the first rolled material SR every time rolling is completed.

is excluded from the target, and the latest next rolled material SRn++ is included in the target, and the average value αR of the difference is constantly updated using the latest data.

To explain this specifically, the rolled material SRn+ after rolling has been completed.
The slab groups for which aR is calculated in the case of +, SRn+, are SRn+ l, SRn, SRn +, □
= −−5R2SRn+ a, SRn+ +, SR
n, --・”SRz.

The above is the flow of how to calculate the in-furnace time.

In addition, in the present invention, the rolling time of the slab and the time in the furnace are made to be the same, but when a constraint time β is required due to the performance of the rolling equipment, such as the set-up of the rolling mill or the thermal crown of the rolling roll, the rolling time Although the time, that is, the time in the furnace is naturally taken into consideration, the description is omitted here to simplify the explanation.

Example In thick plate rolling, 50 slabs of approximately the same size were heated to a target extraction temperature of 1180°C using two continuous heating furnaces, and a thick steel plate of 16×3300× was rolled using one thick plate rolling mill. QOOm
/m was rolled. Predicted average rolling time per rolled material2
The actual average pressure time was 2 minutes and 23 seconds.

Since the average value of the difference per rolled slab was αR = 2 seconds, the correction value αR = 2, and the set in-furnace time of each slab △
Heating was corrected to ti -2 seconds. As a result, by changing the extraction pitch of the slab on the extraction port side from 4 minutes 50 seconds to 4 minutes 46 seconds, production efficiency improved by about 0.5%, fuel consumption improved, and heating furnace control accuracy improved. Ta.

〔Effect of the invention〕

As explained above, according to the present invention, the steel heating furnace and the rolling mill always function organically and in a connected manner, and each slab in the heating furnace is operated with optimum heating time with high efficiency and high productivity. I can do it. Therefore, the fuel consumption rate can be reduced, and the heating furnace can be accurately controlled by computer.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing the gist of a heating (time) control method for a steel heating furnace according to the present invention. FIG. 2 is a plan view illustrating the state of a heated slab in a steel heating furnace and a rolled material rolled in a rolling mill, for explaining the present invention. FIG. 3 is a sectional view illustrating a heating slab in a steel heating furnace illustrating the present invention. Code...S,,S,,S3...Sn-+Sn: Slabs in charging order in the furnace SRn+ 1SRn+ t-3Rn+
n: Slabs in the rolling order in the furnace SR, SR2...SRn: The latest rolled material ΔLl+ΔL2. ...△tn...Predicted rolling time of rolled material (in rolling order) △L++△t2...△tn... Actual rolling time of rolled material (in rolling order) α, R1αR, ... αRn ...Individual difference between predicted rolling time and actual rolling time Patent applicant Kawasaki Steel Corporation Figure 1

Claims (1)

[Claims] When controlling a heating furnace that heats steel materials by computer, the time in the furnace until the steel material to be heated in the furnace is heated to the target temperature and extracted is calculated by comparing the rolling time of a group of rolled materials that have been rolled and the time before rolling. The method is characterized in that the average value of the group is determined from the difference between the predicted rolling time of the group of rolled materials, and the furnace time of each of the steel materials to be heated is corrected sequentially based on the average value. A heating control method for a steel heating furnace.