JPS5992111A - Controlling method for cooling thick steel plate - Google Patents

Abstract

PURPOSE:To perform uniform cooling of a thick steel plate with good accuracy in the stage of accelerated on-line cooling of the thick steel plate by determining the remaining cooling time for the thick steel plate in a cooling zone and correcting the succeeding travel speed of the plate from said time and the distance for accelerated cooling. CONSTITUTION:A fix point P is provided in the position of a distance L1 from the end at the inlet of a cooling zone in the stage of cooling a thick steel plate 1 with an accelerated on-line cooling device 2. The movement of the plate 1 from the start of cooling up to the point P is traced by a pulse generator (PLG) attached to a table motor M, and the arrival of the plate 1 at the point P is detected from the number N of pulses. The time t1 elapsed from the start of cooling till the arrival at the point P is determined by the product of the time DELTAt in one pulse of PLG and N. If there is a change in the actual speed from the start of cooling up to the point P, the residual cooling time is determined by subtracting t1 from the cooling time (t), and the succeeding travel speed is corrected to a specified speed V, whereby the accuracy in the position of the steel plate is considerably improved and the cooling of the steel plate is uniformly accomplished.

Description

[Detailed Description of the Invention] The present invention provides an online accelerated cooling force υ of a thick steel plate.
Regarding the cooling control method for thick steel plates, please refer to the following for more details. The present invention relates to a cooling control method when high precision trunking is required.

Regarding the uniform cooling of thick steel plates, which is one of the important control points in the online accelerated cooling method for steel plates, the present inventors have developed a method for uniform cooling of thick steel plates in the running direction. A cooling method 7 in which the leading end and tail end of the No. 41 thick steel plate in the running direction are offset by predetermined lengths from the cooling device is Lk'M. The outline will be explained with reference to Figure 1.

(a) Start cooling by aligning the tail end 5 of the thick steel plate 1 with the end 7 of the Ore Line accelerated cooling device 2, (b) Next, move the thick steel plate 1 back by ΔL8 to offset the After that, the thick steel plate 1 is moved forward and transferred through the accelerated cooling device 2. Protrude from J end 8 by ΔΣτ and offset i・.

(d) Next, the thick steel plate 1 is retreated until the light end 6 of the thick steel plate 1 coincides with the outlet end 8 of the online accelerated cooling device 2, and the cooling is completed.

In the case of the above cooling horn method, the offset length Δje and Δ
You can rest assured that you can control the particles accurately. 1; The simplest way to implement the above cooling method is to set the conveyance distance A of the thickness≦11 plate by accelerating the cooling device length jk L, the length of the rolled thick steel plate, the offset length ΔlB of the front and rear ends of the thick steel plate, Obtained from Δχ by the following formula, A=L−(cross−2(Δb+Δlikes))...(1) Next, phantom cooling 11. 'p 1lil t・■・°Level threading speed V = A /1 (rn/5ec) is calculated, and by controlling the speed of the table at this constant threading speed, the above cooling power /, I: It can be realized. However, with this kind of control, the accuracy of the knob at the end of cooling of the steel plate deteriorates due to the low precision of the control of the threading speed, and it is difficult to uniformize the 1.5 Hi min 4i in the running direction of the thick steel plate. It was a disturbance that hindered this.

The present invention provides a method for the online accelerated cooling power υ of thick steel plates,
Aiming at realizing the uniform cooling method mentioned above with high accuracy, the present invention provides a cooling control method that significantly improves the steel plate position control accuracy and achieves uniform cooling.

The details of the present invention for achieving the above-mentioned χTl7) accuracy improvement -1- will be explained with reference to the drawings. First, as shown in FIG. 1(a), cooling is started by aligning the tail end of the thick steel plate 1 with the end 11 of the accelerated cooling device. Note that the tracking of the copper plate before cooling is corrected using a laser T.

The immediate time t (sec) is determined from the cooling rate and the cooling stop temperature, which are determined by material requirements. This cooling time E
The conveyance distance A of the thick steel plate l conveyed within the above-mentioned (
It is determined from equation 1), and when the constant speed v (m/5ec) is determined, it becomes as shown in equation (2).

v - A / L (2) Here, for the sake of simplicity, the time required to change the running direction of the J'X 1ili board will be ignored.

If the thick steel plate 1 is conveyed at v (m/5ee), as shown in Fig. 1 (a)
Cooling is started from the state shown in FIG. 1(d), and when the thick steel plate reaches the state shown in FIG. 1(d), the cooling period of r degrees is completed.

It is required that the timing of this thick steel plate position control and the timing of completion of cooling coincide. However, in reality, even if there is no slip between the thick steel plate and the table during cooling, the table speed control system has a
Since there is a 1t°1 difference of 0.~30%, the positional accuracy of the thick steel plate in the cooling chamber r in the state shown in Fig. 1(d) deteriorates by that much, and for the purpose of uniform cooling, the tip is offset The approximation of the thick steel plate is lost, and an uneven part of the temperature distribution in the running direction of the thick steel plate appears at the tip. 1-If the steel plate is not transported in a cooling zone with a poor atmosphere, use optical sensors!・It is possible to perform racking repair IF, but it is impossible in a cooling system.

Therefore, in the present invention, a fixed point P is provided at a predetermined position in the cooling zone, for example, at a distance from the population end of the cooling zone, as shown in FIG. The movement of the steel plate is followed by a pulse generator (PLO) attached to a table motor (M), and it is detected that the thick steel plate has reached P based on the number of pulses N when the steel plate moves from the start of cooling to Ll. Elapsed time from the start of cooling until reaching p 1H, < + 1. teeth,
The time of one pulse of the pulse georator is Δt(see)
Then, it can be found by t+ = NXΔt.

When the actual speed from the start of cooling to point P becomes (V-ΔV), calculate the required speed V for the remaining cooling time (1-1+) from the following equation (3) and calculate the subsequent threading speed. By correcting to V, it is possible to improve the accuracy of the thick steel plate tip when the cooling is stopped after t(see).

・・・・・・・・・(3) , n stiffness: (v-ΔV) is (T, + + 2f, s
, Q) / t +.

Note that the pulse generator is usually a thick steel plate with a tail end on the front table, and only in the case of a short thick steel plate shorter than the table length, a table with a tail end is used.

The method of the present invention can be applied not only to the case shown in the first factor, but also to the position control of a thick steel plate in a cooling zone in any cooling power method.

According to the method of the present invention, 1'/:
Self-cooling of the +i plate can be realized, material unevenness can be prevented, and the two-layer retention can be improved, resulting in excellent effects.

Example A steel plate with a thickness of 20 nm, a width of 3500 mm, and a length of 20 m was cooled for 26 seconds by the cooling method shown in Fig. 1.
The operation was carried out with ΔB = 2 m and Δ17 = 1 m. The length of the accelerated cooling equipment is 40 m.

In the conventional method, the steel plate conveying pressure #A = 26 m and the speed setting was v = 26 m726 sec = l m/see, and when 4S was performed with this, the speed was deviated by 110% by 0.9
m/sec. At this time, 26 seconds later, the sound of the thick steel plate being transported was heard, and the distance became 23.4 m, and the cooling stop occurred at the position shown in Figure 3, so the tip of the thick steel plate became supercooled. . The cooling temperature distribution and tensile strength 41 at this time are shown in No. 412. The material was uneven due to uneven cooling, and a defective portion of 0.9 m was generated at the tip. The material unevenness shows a difference of 7 to 8 kg101 m' in tensile strength.

FIG. 5 shows the results of controlling an embodiment of the present invention using trunking by a pulse generator. Cooling zone person [Trunking f + li + was performed using a pulse generator at a position 30 m from the J end. The cooling elapsed time 1111 up to this point was 15.4 seconds. Therefore, the conveyance speed for the remaining accelerated cooling distance was determined using the above equation (3), and the result was that the tip of the thick steel plate came out of the cooling zone at the end of cooling, as shown in Fig. 5. A steel plate conveyance accuracy of 0.1 m deviation from one end was obtained. The temperature distribution and tensile strength distribution of the steel plate at this time are shown in FIG. 6, and there was little temperature unevenness in the running direction of the steel plate, and the tensile strength was within a difference of 2 kg/mm', and it was possible to collect products up to the ends of the thick steel plate.

[Brief explanation of drawings]

Fig. 1 is a process diagram showing an example of a table-controlled cooling method for offsetting the leading and trailing ends of a thick steel plate in the online accelerated cooling force method for thick steel plates; Fig. 2 is an explanatory diagram of the method of the present invention;
The figure shows cooling stop J1 in conventional table speed-loop control.
Fig. 4 is a graph showing the end-of-cooling temperature distribution and tensile strength Ilj of the thick steel plate in Fig. FIG. 6 is a graph showing the final cooling temperature (A) and tensile strength distribution of the thick steel plate according to the invention. DESCRIPTION OF SYMBOLS 1... Thick steel plate to be cooled, 2... Online acceleration cooling bag 7i'i, 3... Pass line, 4... Thick steel plate running direction, 5... Thick steel plate tail end, 6... Thick steel plate tip, 7...
・λ of the cooling device 1 end, 8... Output 1 summer end of the cooling device,
ΔPa +ΔIT...offset length, P...fixed point,
L...Full length of the cooling device, ]71...Distance M from the first end of the cooling device at a fixed point, M...Table motor,
PLO...Pulse Generator Special Applicant Jl + Saki Steel Co., Ltd. Agent Patent Attorney 1- Yosuo Kosugi Figure 1 Figure 2 Figure 3 Figure 4 Obi J Sho (4 Okamoto Anti-Nagayokata City) Mitsubato Hiroshi ode

Claims (1)

[Claims] 1. In the online accelerated cooling method for 11-thick steel sheets, a fixed point is provided in the cooling zone of the accelerated cooling device, and from the elapsed time from the start of accelerated cooling 2J1 of the thick steel plate until the i-end of the thick steel plate passes the fixed point. A method for controlling the cooling of a thick steel plate, characterized in that the remaining cooling time is determined, and the subsequent threading speed is corrected based on the remaining cooling time and the remaining accelerated cooling distance.