JPH0741295B2 - Mill pacing control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for rolling a steel strip using a rolling facility having a cooling bed for natural cooling and a cold cutting machine in its conditioning line.

[Prior Art] Normally, in a strip rolling mill, a natural cooling, for example, a Rechen type cooling bed and a downcut, for example, a cold cutting machine are provided in a conditioning line after a rolling mill train including a running cutting machine. Have.

Fig. 3 is a block diagram of a cold cutting line using a natural cooling cooling floor and a down-cut type cold cutting machine. 1 is a heating furnace, 2 is a rolling mill train, 3 is a hot cutting machine, and 4 is a chen. Type cooling floor, 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, and 9 is a groove on which a rolling material is placed on the cooling floor. Reference numeral 10 denotes a tracking device for holding and outputting information on whether there is any, and a cold cutting machine cutting control device.

Bearing steel, alloy steel, and other materials called warm cutting materials must have a temperature of 300 ° C or higher when cutting with the cold cutting machine 5, and cut at temperatures below that. If this is done, cracks will occur in the cut surface, leading to poor quality.

Therefore, conventionally, (1) the number of pieces that can be cut lively by the cold cutting machine 5 is converted into the number of billets (normal billets are divided into several pieces by the rolling cutting machine 3 after rolling), and the converted number of billets is extracted. The extraction is interrupted at the specified stage.

(2) Divide all of the extracted billets with the cutting machine 3
After all the divided steel materials have been taken into the cooling bed 4, the cooling bed 4 is fast-forwarded in order to prevent a temperature drop as much as possible.

(3) After the taken-in steel material leaves the cooling floor 4 or the cooling floor 4
When reaching near the exit side, the operator starts extraction of the steel material of the next cutting group.

I am dealing with such a method.

[Problems to be Solved] However, the above-described operation method has some problems. That is, (1) When the maximum number of pieces that can be cut by the cold cutting machine 5 is taken in, the cutting temperature of the leading member of the cutting group may fall below 300 ° C. and end face cracking may occur even if fast-forwarding is performed.

(2) If the extraction timing of the next cutting group is too early, the steel material of the next cutting group reaches the cooling floor exit side during the cutting of the preceding cutting group,
Since waiting occurs, the cutting temperature may drop below 300 ° C, leading to end face cracking.

(3) If the next cutting group is extracted after the preceding cutting group leaves the cooling bed in order to avoid the above-mentioned trouble, rolling loss time may occur between the next cutting group and the next cutting group, which may lead to a decrease in productivity. is there.

Since the cooling pattern and optimum extraction timing differ depending on various steel material sizes and rolling conditions, the above trouble cannot be avoided by operator judgment.

The present invention is intended to solve the above problems, and an object of the present invention is to provide a mill pacing control method capable of cold-cutting a warm-cut material without causing cracks while minimizing a decrease in productivity. .

[Means for Solving the Problems] A mill pacing control method of the present invention is a time T during which a steel material falls in temperature from the time when a cooling bed is taken up to a cold cutting target temperature, and the time when the steel material is extracted from a heating furnace to a rolled material. To reach the cooling bed inlet, the cooling bed intake time Ai, the number of grooves Et of the cooling bed, the rapid feed time b per groove of the cooling bed, and the cooling bed After it is confirmed from the transport time Ci from the outlet to the cold cutting machine and the cutting time Di of the cold cutting machine that the following formula (1) is satisfied,
The next extraction reference cooling floor groove position E is calculated by the equation (2), and when the tail position of the (i-1) th rolled material on the cooling floor becomes the next extraction reference cooling floor groove position E, i It is characterized in that the steel material for the sixth rolling is extracted from the heating furnace.

[Operation] When a plurality of processes are connected in series, it is important to fully operate the process with the smallest capacity (rate-controlling step). In a rolling cutting line, a cold cutting machine is often the rate-determining step.

The present invention is intended to optimize the time when the rolled material is taken into the front cooling bed next time so that the cold cutting machine is fully operated. First, the rolled material reaches the cooling bed inlet before cold decision is made. The allowable cooling time T up to is determined, and if there is a margin time difference between the allowable cooling time T and the transportation time when the cooling bed is fast-forwarded, the next time the rolled material is extracted and rolled before the completion of cold cutting The next instruction is to extract the heating furnace for the steel material using the position on the cooling floor at the end of the rolled material as a guide.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.
Note that the reference numerals described above indicate the same parts, and a description thereof will be omitted.

FIG. 1 is a block diagram of a mill pacing control device according to a mill pacing control method according to an embodiment.
Is a radiation thermometer that measures the temperature of the rolled material reaching the cooling floor and outputs a signal to the cooling time calculation device 12. Reference numeral 12 is an expected temperature (12a), a target cutting temperature (12b), and a steel material size (12c) obtained by an input (not shown). ), And a cooling time calculation device for estimating and calculating a time (which may be referred to as an allowable cooling time) T from the arrival of the rolled material to the cooling floor to the temperature of 300 ° C. by the signal 11a of the radiation thermometer 11 Reference numeral 13 is a mill pacing device that calculates the next extraction timing and commands the extraction control device 6 of the heating furnace 1 to extract the steel material.

Here, the calculation process of the equations (1) and (2) will be described.
The following variables are set as related characteristic values.

T: The time between the temperature of the cooling bed 4 expected to be taken in (predicted from the extraction temperature and the rolling schedule) to the target temperature at the time of cutting by the cold cutting machine 5 (sometimes called the allowable cooling time). Fig. 2 shows the cooling curve when the intake temperature of the cooling bed 4 is 1000 ° C. The obtained intake temperature (12a) and the target at the time of disconnection were obtained by obtaining it in the cooling time calculation device 12 that stores the data that approximated the broken line. Temperature (12b) and steel size (12
If you enter c), the allowable cooling time is calculated. Further, if a temperature measuring device (radiation thermometer 11) is installed at either or both of the rolled material intake portion of the cooling floor 4 and the cold cutting machine 5 inlet side, the allowable feedback of the prediction accuracy of the allowable cooling time can be realized by the temperature feedback. It is possible to improve.

Ai: 1 cutting group uptake time. This is the time required for the cooling bed 4 to take in a group of rolling materials that have arrived onto the floor. More detailed definition is Ai = ai (number of captured steel) × [capture time per steel] + [number of extracted steel materials−1] × [inter-pitch time].

Bi: 1 cutting group fast-forward time. This is the transport time from immediately after the intake of the cooling bed 4 until the rolled material reaches the outlet of the cooling bed 4 by the fast-forwarding performed when the cooling in the cooling bed 4 is minimized.

Bi = Et × b 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 floor 4 during fast-forwarding (fast-forwarding time per groove).

Ci: 1 cutting group transportation time. It is a transportation time of one group of rolled material from the outlet of the cooling floor 4 to the cold cutting machine 5.

Di: 1 cutting group cutting time. It is the time for cold cutting the first group rolled material.

Di = [number of cuts] × [cutting time per cut] The number of cuts is determined by the length of the incorporated material and the cold cut length.

Fio: Working time from steel material extraction to reaching the cooling floor 4. It is the time from when the steel material is taken out of the heating furnace 1 to when it reaches the inlet of the cooling bed 4 through rolling and cutting during running.

Subscript i: Indicates the order of rolling and cutting group (i = 1,2,3 ...).

Subscript io: Indicates the first steel in the i-th rolled and cut group.

Below, consideration will be given to what kind of each characteristic value allows cold cutting without cracking.

In case of IA ₁ + B ₁ + C ₁ + D ₁ > T Warm cutting is not possible. The cold cutting machine 5 basically cuts the number of cuttable pieces into one cutting group.

A ₁ + B ₁ + C ₁ + D ₁ is the total time from the arrival of the first cooling bed 4 inlet to the completion of cold cutting, which is 300 ° C of the rolled material.
Since it is longer than the cooling time T, it becomes a condition for crack generation. As a countermeasure, the number of extracted lines, that is, the number of taken lines, ai is changed to reduce A ₁ , and the number of extracted lines satisfies A ₁ + B ₁ + C ₁ + D ₁ ≦ T.

II. When A ₁ + B ₁ + C ₁ + D ₁ ≤T Warm cutting is possible. In this case, since warm cutting is possible, the possibility of further shortening the waiting time will be examined.

(A) In the case of A ₁ + B ₁ + C ₁ + D ₁ + A ₂ > T It is impossible to incorporate the cooling bed 4 in the next cutting group. There is not enough time (A ₂ ) to take the next cutting group into the cooling floor 4. However, assuming that the time from the extraction of the heating furnace 1 of the next steel material group to the arrival of the cooling bed 4 is F ₂₀ , the last material of the preceding cutting group is {Et- (F ₂₀ / b)} of the cooling bed 4.
When the second groove is reached, the next steel material may be extracted from the heating furnace 1. However, (F ₂₀ / b) is rounded down to the nearest whole number. At this time, if A ₂ + B ₂ + C ₂ ≧ C ₁ + D _1, then C ₂ ≈C ₁ , so A ₂ + B ₂ ≧ D ₁ , and there is no waiting for disconnection in the next disconnection group.

If A ₂ + B ₂ + C ₂ <C ₁ + D _1, then C ₂ ≈C ₁ , so A ₂ + B ₂ <D ₁ , and waiting for cutting occurs in the next cutting group. It does not matter if the last material of the preceding cutting group reaches the {Et− (F ₂₀ / b)} th groove of the cooling floor 4.

(B) In the case of A ₁ + B ₁ + C ₁ + D ₁ + A ₂ ≤T ...... (3), the next cutting group can be incorporated. For the preceding truncation group, the uptake of the next truncation group is irrelevant wherever it occurs. In this case, the B ₁₂ as prior cutting group rapid traverse time since completion next cutting group _{incorporation, B 2 + C 2 ≧ B} 12 + C 1 + D 1 _{if, B 2 ≧ B 12 + D} 1 for the C ₂ ≒ C ₁
Therefore, there is no waiting for disconnection in the next disconnection group.

If B ₂ + C ₂ <B ₁₂ + C ₁ + D _1, then C ₂ ≈C ₁ , so B ₂ <B ₁₂ + D ₁
Therefore, waiting for disconnection occurs in the next disconnection group.

Further, when A ₂ + B ₂ + C ₂ + (B ₁₂ + D ₁ −B ₂ ) + D ₂ > T, the hot cutting of the next cutting group becomes impossible due to the temperature decrease of the rolled material, and A ₂ + B ₂ + C ₂ + (B ₁₂ + D ₁ −B ₂ ) + D ₂ ≦ T, warm cutting of the next cutting group is possible.

Examine the value of B _{12 that} satisfies the above conditions for warm cutting.
Under the boundary condition, since A ₂ + C ₂ + B ₁₂ + D ₁ + D ₂ = T, B ₁₂ = T−A ₂ −C ₂ −D ₁ −D ₂ B ₁₂ cannot take a physically negative value, so T−A _{2 -C 2 -D 1 -D 2 ≧} 0 ...... (4) needs to be.

The next steel material extraction timing is Et-[(F ₂₀ / b) when the preceding cutting group final material is the cooling floor 4 considering the processing time F ₂₀ such as rolling from the extraction to the arrival of the cooling bed 4 in addition to the above B ₁₂ hours. ＋ (B ₁₂ / b)] …… (5) It can be calculated that the groove is reached. However, (F ₂₀ / b) + (B
₁₂ / b) is rounded down to the nearest whole number.

Further, when the calculated value is less than 1, for the sake of convenience, it is immediately after the import.

The rolling times 1 and 2 in the above equations (4) and (5) are generalized to i−1, i to obtain equations (1) and (2).

The mill pacing control device of this embodiment is configured in this way and operates as follows.

The cooling time calculation device 12 receives inputs of the expected temperature (12a), the cutting target temperature (12b), and the steel material size (12c), and applies the standard cooling curve stored in advance to calculate the allowable cooling time T. The mill pacing device 13 has the above-mentioned cases I and II.
Determine whether it belongs to a or II b, and if possible,
Adjust the number of captured ai to be the case of II b.

In case IIb, the mil pacing device 13 uses the number of intakes if necessary so that the formula (1) is satisfied.
Then, ai is readjusted, and then the next extraction reference groove position E is calculated by the equation (2).

When the next extraction reference groove position E is determined, the mill pacing device 13 monitors the movement of the preceding rolled material on the cooling floor 4 by the signal of the tracking device 9, and the end of the rolled material reaches the next extraction reference groove position E. At that time, the extraction control device 6 is instructed to extract the steel material for the next rolling.

In case IIa, the uptake of the next rolled material into the cooling bed during cold cutting is not permitted. At this time, the mill pacing device 13 issues an instruction to extract the steel material for rolling next time before the rolling cutting work time Fio time at the scheduled cold cutting end time.

In this way, the mill pacing control device of the present embodiment prevents the occurrence of cracks by setting the rolled material temperature during cold cutting to 300 ° C. or higher, while minimizing the waiting time of the cold cutting machine, The productivity of can be improved.

[Effects of the Invention] The mill pacing control method of the present invention, the time T during the temperature drop of the steel material from the time of taking in the cooling bed to the cold cutting target temperature, and from the heating furnace extraction of the steel material to the rolled material. Working time Fio to reach the cooling bed inlet, uptake time Ai of the cooling bed, number of grooves Et of the cooling bed, and 1 of the cooling bed
From the rapid feed time b per groove, the transport time Ci from the cooling floor outlet to the cold cutting machine, and the cutting time Di of the cold cutting machine, it was confirmed that the following formula (1) was satisfied. later,
The next extraction reference cooling floor groove position E is calculated by the equation (2), and when the tail position of the (i-1) th rolled material on the cooling floor becomes the next extraction reference cooling floor groove position E, i It is designed to extract the steel material for the second rolling from the heating furnace, which maximizes the operating rate of the cold cutting machine while preventing the occurrence of cracks in response to various changes in the rolling and cutting conditions such as the steel material size. It is possible to secure the quality of the cut material, improve the productivity, and stabilize the extraction pitch, resulting in great economic benefits.

[Brief description of drawings]

FIG. 1 is a block diagram of a mill pacing control apparatus according to a mill pacing control method as one embodiment, and FIG. 2 is a graph of a temperature cooling curve when a rolled material having a cooling bed intake temperature of 1000 ° C. is allowed to cool, and FIG. The figure is a block diagram of a conventional cold cutting line. 1 ... Heating furnace, 2 ... Rolling mill train, 3 ... Running cutting machine, 4
…… Cooling floor, 5 …… Cold cutting machine, 6 …… Extraction control device,
7 ... Rolling machine control device, 8 ... Running cutting machine cutting control device, 9 ... Tracking device, 10 ... Cold cutting machine cutting control device, 11 ... Radiation thermometer, 12 ... Cooling time calculation device ,
13 …… Mill pacing device.

Claims (1)

[Claims] 1. A steel material heated from a heating furnace is extracted, hot-rolled into a rolled material, naturally cooled in a cooling floor having a plurality of rolled material mounting grooves, and cold-rolled in a cold cutting machine. In a mill pacing control method of adjusting a steel material extraction time interval of a rolling cutting line for cutting, a time T during which the temperature of the steel material falls from a time of taking in the cooling bed to a cold cutting target temperature, and a heating of the steel material. Working time Fio from the furnace extraction until rolled material reaches the cooling bed inlet, the cooling bed uptake time Ai, the number of grooves Et of the cooling bed, and the rapid feed time b per groove of the cooling bed b After it is confirmed that the following expression (1) is satisfied from the transportation time Ci from the cooling floor outlet to the cold cutting machine and the cutting time Di of the cold cutting machine,
The next extraction reference cooling floor groove position E is calculated by the equation (2), and when the tail position of the (i-1) th rolled material on the cooling floor becomes the next extraction reference cooling floor groove position E, i A mill pacing control method comprising extracting a steel material for a rolling operation 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 fractional part of E is rounded up. , When E <1, E =
1.