JPH0275406A - Method for controlling mill pacing - Google Patents

Abstract

PURPOSE:To keep the quality of warm cut stock good and to improve the productivity by extracting a steel stock to be rolled from a heating furnace at a moment when all of a steel stock cooling time, rolling operation time, and plural conditions related to cooling satisfy specific relations. CONSTITUTION:A steel stock extracted from a heating furnace 1 is rolled by a rolling mill group 2. After rolling, the stock is cooled on a cooling bed 4 and is cut by a cold shear 5. The formula I is satisfied by a dropping time T of a temp. on the bed 4 to a cutting target temp., a rolling operation time Fio, an uptake time Ai of the bed 4, the number of grooves Et of the bed 4, a quick carrying time Ci per groove, and a cutting time Di. After then, a cooling bed groove position E as a guideline for the succeeding extraction is calculated by the formula II. At the time when the rear end of an (i-1)th rolled stock on the bed 4 arrives at the groove position E, an (i)th rolled stock is extracted from the furnace 1. Hence, the good quality of a warm cut steel stock is kept and the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a long steel rolling method using a rolling equipment having a natural cooling cooling bed and a cold cutting machine in its finishing line.

[Prior Art] Normally, in long steel rolling equipment, a natural cooling cooling bed, such as a Lechen type cooling bed, and a down cut type cold cutting machine, for example, are installed in a finishing line after a row of rolling mills including a running cutting machine. has.

FIG. 3 is a block diagram of a cold cutting line using a naturally cooled cooling bed and a down-cut type cold opening cutting machine, in which 1 is a heating furnace, 2 is a rolling mill row, 3 is a running cutting machine, and 4 is a lechen cutting machine. 5 is a down-cut type cold cutting machine, 6 is an extraction control device, 7 is a rolling mill control device, 8 is a running cutting machine cutting control device, 9 is a groove on the cooling bed where the rolled material is placed. A tracking device 10 is a cold cutting machine cutting control device 6. Materials called isothermal cutting (worm shear) materials such as bearing steel and alloy steel are cut by the cold cutting machine 5. When cutting, a temperature of 300° C. or higher must be maintained; if cutting is performed at a temperature lower than that, cracks will occur on the cut surface, resulting in poor quality.

Therefore, conventionally.

(1) Convert the number of billets that can be cut at once with the cold cutting machine 5 into the number of billets (normally billets are divided into several pieces by the running cutter 3 after rolling), and extract the number of billets when the converted number of billets is extracted. interrupt.

(2) Divide the entire number of extracted billets using a running cutter 3,
After all of the divided steel materials are taken into the cooling bed 4, the cooling bed 4 is rapidly moved in order to prevent temperature drop as much as possible.

(3) After the introduced steel leaves the cooling bed 4 or
When reaching near the exit side, the operator begins extracting steel for the next cutting group.

This is how we deal with it.

[Problems to be Solved] However, the above-mentioned operating method has several problems. Namely.

(1) When the maximum number of pieces that can be cut by the cold cutter 5 is taken in, even if fast forwarding is carried out, the temperature at the time of cutting of the leading material of the cutting group may fall below 300°C, leading to end face cracking.

(2) If the extraction timing of the next cutting group is too early, the steel material of the next cutting group will reach the cooling bed exit side during the cutting of the preceding cutting group,
Because of the waiting time, the cutting temperature may drop below 300"C, leading to end face cracking.

(3) In order to avoid the above trouble, if the next cutting group is extracted after the preceding cutting group has left the cooling bed, rolling loss time will occur between the preceding cutting group and the next cutting group, which may lead to a decrease in productivity. be.

Since the cooling pattern and optimal extraction timing differ depending on the various steel material sizes and rolling conditions, the above-mentioned troubles cannot be avoided by the operator's judgment.

The present invention aims to solve the above-mentioned problems, and aims to provide a mill paging control method that can cold-cut warm-cut materials without cracking while minimizing the decrease in productivity. .

[Means for Solving the Problems] The mill paging control method of the present invention has the following advantages: the time T during which the temperature of the steel material falls from the time of intake into the cooling bed to the cold cutting target temperature, and the time T during which the temperature of the steel material falls from the heating furnace extraction to the rolled material. Then, the working time Fio until reaching the cooling bed inlet, the intake time Ai of the cooling bed, the number of grooves Et of the cooling bed, and the fast-forwarding time per groove of the cooling bed, the cooling bed After confirming that the equation (1) described below is satisfied from the transport time Ci from the outlet to the cold cutting machine and the cutting time Di of the cold cutting machine, the next extraction standard is determined by the equation (2). Cooling bed groove position E
is calculated, and when the trailing position of the (i-1)th rolled material on the cooling bed becomes the next extraction target cooling bed groove position E, the steel material for the jth rolling is extracted from the recordable heating furnace. It is a feature.

[Operation] When multiple processes are connected in series, it is important to fully operate the process with the smallest capacity (rate-determining stage). In a rolling cut line, the cold cutter is often the rate-limiting step.

The present invention attempts to optimize the next time when the rolled material is taken into the front cooling bed so that the cold cutting machine can operate at full capacity.The rolled material is first cold cut after reaching the cooling bed inlet. If there is a margin of time between that and the transport time when the cooling bed is moved rapidly, extraction rolling of the next rolled material will be performed before the cold cutting is completed, and during the cold cutting The next time the next steel material is extracted from the heating furnace, the position on the cooling bed at the end of the rolled material is used as a guide.

[Example] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

Note that the reference numerals already mentioned indicate the same parts, and the explanation will be omitted.

FIG. 1 is a block diagram of a mil paging control device according to a mil paging control method as an embodiment,
1 is a radiation thermometer that measures the temperature of the rolled material arriving at the cooling bed and outputs a signal to the cooling time calculation device 12; 12 is a predicted temperature (12a) input manually (not shown); a cutting target temperature (
12b) According to the steel material dimensions (12c) and the signal 11a of the radiation thermometer 11, the temperature of the rolled material is 300°C from the time it arrives at the cooling bed entrance.
A cooling time calculation device that estimates and calculates the time T (sometimes referred to as allowable cooling time) until the air is cooled down.

13 is a mill paging device that calculates the next extraction timing and instructs the extraction control device 6 of the heating furnace 1 to extract steel material.

Here, the calculation process of the above formulas (1) and (2) will be explained.

Set the related characteristic values and dimensions as well as the following variables.

T: Time required for the temperature to drop from the expected intake temperature of the cooling bed 4 (predicted from the extraction temperature and rolling schedule) to the target temperature at the time of cutting in the cold cutting machine 5 (sometimes referred to as allowable cooling time). Fig. 2 shows a cooling curve when the intake temperature of the cooling bed 4 is set to 1000°C, and the above predicted intake temperature (12a) and the cutting target temperature are manually input into the cooling time calculation device 12 which stores data obtained by approximating the curve to a broken line. (12b) and the steel material size (12c), the allowable cooling time is calculated. Furthermore, if a temperature measuring device (radiation thermometer 11) is installed at either or both of the rolling material intake point of the cooling bed 4 or the cold cutting l'5 person side, the temperature feedback will improve the accuracy of predicting the allowable cooling time. It is possible to improve the

Ai: 1 cutting group uptake time. This is the time required for the cooling bed 4 to take in a group of arriving rolled materials onto the bed. To define it in more detail, Ai = ai (number of images captured) x [time taken per image]
+ [Number of extracted steel materials - 11 x [interval pitch time].

Bi: 1 cutting group fast forward time. This is the conveyance time from immediately after intake of the cooling bed 4 until the rolled material reaches the exit of the cooling bed 4 due to the rapid feed performed when cooling in the cooling bed 4 is minimized.

Bi=EtXb Et: Total number of grooves in the cooling bed 4.

b = Time required for the rolled material to pass through one groove of the cooling bed 4 during rapid traverse (rapid traverse time per groove).

Ci: Transport time for one cutting group. This is the transportation time of one group of rolled materials from the outlet of the cooling bed 4 to the cold cutting machine 5.

It's time to cut it off.

Di=[number of cuts]×[cutting time per time] The number of cuts is determined from the length of the material taken in and the cold cutting length.

Fio: Working time from oil extraction to reaching cooling bed 4.

This is the time from when the steel material is extracted from the heating furnace 1 until it reaches the cooling bed 4 population through rolling and running cutting.

Subscript i: Rolling, cutting group order (i = 1.2.3...
...) is shown.

Subscript io: Indicates the first steel material in the i-th rolling and cutting group.

Below, we will consider when each characteristic value allows cold cutting without cracking.

1. Warm cutting is not possible in the case of A work + B work + C1 + D work> T.

The cold cutting machine 5 basically cuts the number of pieces that can be cut into one cutting group.

A□10B work + C□+D work is the total time from the first cooling bed 4 rows to the completion of cold cutting, which is longer than the 300℃ cooling time T of the rolled material, so cracks will occur. It is a condition. As a countermeasure, change the number of extracted lines, that is, the number of captured lines ai, and make A to smaller, so that A1+B1+C-work+D-work≦T
tI - the number of extractions to satisfy.

11. Warm cutting is possible when A + B work + C, + D work ≦T. In this case, since warm cutting is possible, the possibility of further shortening the waiting time will be investigated.

(a) A, + B 1+ C, + D □+
If A2>T, cooling bed 4 of the next cutting group cannot be taken in. There is no time (A2) to take the next group of cuts into the cooling bed 4.

However, if F2o is the time from extraction of the next steel material group to the arrival at cooling bed 4, then the final material of the preceding cutting group will reach cooling bed 4.
When the (Et-(F, ./b))th groove is reached, the next steel material may be extracted from the heating furnace 1. However, CF2゜/b
) rounds down to an integer after the decimal point. At this time.

If A2+B2+C2≧C1+D1, then A2,000B,≧D□ because C2≠C, and there is no waiting for cutting in the primary cutting group.

If A, +B, +C2<C work + D work, then A2 + B2 < D work because of the C2 valve C8, and a cutting wait occurs in the next cutting group.

However, because of A, +B, )D, the cold cutting machine usually does not operate at full capacity, and this [Ia condition is undesirable.

(b) A work + B1 + C work + D, +A, ≦T...
In the case of (3), the next cutting group can be imported. For the preceding cutting group, it is irrelevant where the next cutting group is taken. At this time, B1□ is the fast-forwarding time of the preceding cutting group after the completion of importing the next cutting group, and if B2+C2≧B-work2+C>+D 1, then C2
Since C1 is given, B2≧Bi, +D, and there is no waiting for cutting in the next cutting group.

If B2+C2<Bi2+C work+D8, then B2<B work 2+D because of C2 slope C work, and a cutting wait occurs in the next cutting group.

Furthermore, A20BZ+C2+ (BL, +D□-B2) +
When D z > T, warm cutting of the next cutting group becomes impossible due to a decrease in the temperature of the rolled material,
-1A, +B, +C, +(B,, +D, -B2)+D,
If ≦T, warm cutting of the next cutting group is possible.

A value of B1□ that satisfies the above-mentioned conditions for warm cutting is carefully investigated. In boundary conditions.

A, +C, +B, +D, +D2 = T, so B1□ = T-A, -C, -D, -D2 Since B□2 cannot physically take a negative value, T-A, -C
, -01-D, ≧0 (4).

The next steel material extraction timing is determined by considering the processing time F20 such as rolling from extraction to arrival at cooling bed 4 in addition to the above B1□ time. (B, /b))-””'
(5) It can be calculated as when the second groove is reached. Just F2゜/
b)+(B□2/b) is rounded down to an integer after the decimal point.

Furthermore, when E becomes less than 1, for convenience, it is assumed that E=1 (immediately after import).

The rolling numbers 1 and 2 in the above equations (4) and (5) are generalized to i-1°i to form equations (1) and (2).

The mill paging control device of this embodiment is configured as described above and operates as follows.

The cooling time calculating device 12 receives input of the expected temperature (12a), the target cutting temperature (12b), and the steel material size (12c), and calculates the allowable cooling time T by applying it to a standard cooling curve stored in advance. The mil paging device 13 includes the case 1. It is determined by calculation whether it belongs to Ila or IIb, and the number ai to be taken in is adjusted so that it is in the nb case as much as possible.

In case IIb, the mill paging device 13 readjusts the intake number ai if necessary so that the formula (1) holds true, and then determines the next extraction target groove position E using the formula (2). calculate.

When the next extraction target groove position E is determined, the mill paging device 13 monitors the movement of the previously rolled material on the cooling bed 4 using the signal from the tracking device 9, and determines when the tail of the rolled material reaches the next extraction target groove position E. At this time, the extraction control device 6 is commanded to extract the steel material for next rolling.

In case Ila, the next rolling material is not allowed to be taken into the cooling bed during cold cutting. At this time, the 5 mil paging device 13 issues a command to extract the steel material for next rolling at a time Fio time before the rolling cutting operation time Fio of the scheduled end time of cold cutting.

In this way, with the mill paging control device of this embodiment, the temperature of the rolled material during cold cutting is set to 300°C or higher to prevent the occurrence of cracks, and the waiting time of the cold cutting machine is minimized, allowing the rolling cutting line to productivity can be improved.

[Effects of the Invention] The mill paging control method of the present invention is characterized by the time T during which the temperature of the steel material falls from the time of intake into the cooling bed to the cold cutting target temperature, and the time T from when the steel material is extracted from the heating furnace until it becomes a rolled material and is cooled. The working time Fio until reaching the bed inlet, the intake time Ai of the cooling bed, the number of grooves Et of the cooling bed, and the fast-forward time per groove of the cooling bed, After confirming that the equation (1) described below is satisfied from the transport time Ci to the cutting machine and the cutting time Di of the cold cutting machine, the next extraction target cooling bed groove position is determined by the equation (2). W.E.
is calculated, and when the trailing position of the (i-1)th rolled material on the cooling bed reaches the next extraction standard cooling bed groove position fiE, the i-th rolled steel material is extracted from the heating furnace. In response to various changes in rolling cutting conditions such as steel material size, it prevents the occurrence of cracks and maximizes the operation rate of the cold cutting machine, ensuring the quality of warm-cut materials, improving productivity,
It becomes possible to stabilize the extraction pitch, and a large economic benefit can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a mill paging control device according to a mill paging control method as an embodiment, Fig. 2 is a graph of a temperature cooling curve when a rolled material with a cooling bed intake temperature of 1000''C is left to cool; Figure 3 is a block diagram of a conventional cold cutting line. 1... Heating furnace, 2... Rolling mill row, 3...
....running cutting machine, 4..cooling bed, 5..
...Cold cutting machine, 6...Extraction control device, 7.
....Rolling mill control device, 8 ....Tracking machine cutting control device, 9 ....Tracking device, 10
...Cold cutting machine cutting control device, 11...
・Radiation thermometer, 12... Cooling time calculation device, 1
3... Mil paging device. Patent applicant Kobe Steel Co., Ltd. Representative Patent attorney Fu Kobayashi

Claims (1)

[Claims] (1) Extract the heated steel material from the heating furnace, hot-roll it into a rolled material, cool it naturally on a cooling bed with multiple rolling material placement grooves, and then cold-cut it with a cold cutting machine. In a mill paging control method for adjusting the extraction time interval of the steel material in a rolling cutting line, the time T during which the temperature of the steel material decreases from the time of intake of the cooling bed to the cold cutting target temperature;
The working time Fio from the extraction of the steel material into the heating furnace until it becomes a rolled material and reaches the cooling bed inlet, the intake time Ai of the cooling bed, the number of grooves Et of the cooling bed, and per groove of the cooling bed. , the transport time Ci from the cooling bed outlet to the cold cutting machine, and the cutting time Di of the cold cutting machine.
After confirming that the equation (1) described below is satisfied, the next extraction target cooling bed groove position E is calculated using the equation (2), and the position E of the (i-1)th rolled material on the cooling bed is calculated. When the trailing position reaches the cooling bed groove position E as the guideline for next extraction,
A mill paging control method characterized by extracting steel material for i-th rolling from the heating furnace. T-Ai-Ci-Di-Di_-_1≧0...
(1) E=Et-(Fio+T-Ai-Ci-Di-Di_-
_1)/b・・・(2) However, the decimal places of E are rounded up, and when E<1, E=1
.