JPS60124411A - Control method of finishing temperature of rolling mill - Google Patents

Abstract

PURPOSE:To control uniformly a temperature of material at the outlet side of finishing rolling by operating and setting a finishing rolling-speed by using a target finishing temperature of material and a measured temperature of material at the inlet side of the finishing rolling, and changing a soaking temperature in a heating furnace in accordance with the deviation of the measured temperature from a set value. CONSTITUTION:In a rolling installation furnished with a coil box 10 between a roughing mill 8 and a finishing mill; a control device 1 inputs a material temperature TS at the inlet side of a finishing rolling from a thermometer 7b, and calculates a finishing rolling-speed VF to set it to a speed control device 9 so as to achieve a target finishing temperature TFO of material given by a computor 14. Next the device 1 makes a sampling of the material temperature at the outlet side of finishing rolling by using a thermometer 11, and outputs a water-flow-rate changing command to a spray-cooling- water control device 20 when the temperature deviates from an allowable tolerance of target temperature, and outputs a soaking-time changing command to the combustion control device 2 of a heating furnace 3 when a long-term learning control is required after finishing the rolling. In this way, the whole length of material is controlled to a desired temperature at the outlet side if finishing rolling, without changing the finishing rolling-speed.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a finishing temperature control method for a hot finishing rolling mill.

[Background of the invention]

Regarding finishing temperature control in hot finishing rolling mills, conventionally, the finishing exit temperature is set lower than the finishing entry temperature or the roughing mill exit temperature, and "During rolling, control is performed by changing the speed or using cooling water sprayed between stands." The idea here is that the finishing rolling speed, the amount of cooling water sprayed between stands, and the finishing inlet temperature (or roughing mill outlet temperature) are input information, and the finishing target is Finish rolling speed is a parameter to be controlled to achieve the desired temperature!
These included the acceleration rate of the rolling stock, the amount of cooling water sprayed between stands, and the waiting time at the entrance of the finishing mill.

Recently, the steel manufacturing process has been forced to shift from mass production to small-variety, small-lot production, and more energy-saving rolling and commodity material production are being sought than ever before. A coil box has been newly developed in recent years in the hot rolling process to meet these demands. This principle is based on a type of coil winding device, as shown in 10 in Figure 1, which is installed between a rough rolling mill 8 and a finishing mill 6, and winds the coil into this coil box while being rolled by the rough rolling mill. It is something. After the rolling in the rough rolling mill is completed and the material is wound up, rolling is started in the finishing mill as shown in FIG. The effects of this coil box are as follows. In other words, firstly, the distance between the roughing mill and finishing mill is shorter than in the conventional process, resulting in lower equipment costs;
What is very important in this process is that the temperature be constant over the entire length of the material entering the finishing mill, or in other words, that the finishing temperature be constant. This will be explained in Figure 3.

FIG. 3 shows the relationship between the material temperature at the entrance of the finishing mill and the temperature at the exit of the roughing mill in the conventional process. Normally, the rough rolling mill outlet temperature TR is approximately the same temperature over the entire length of the material. However, the finishing entry temperature decreases as the rolling of the material progresses. The reason for this is that heat radiation from the material surface and heat conduction into the air reduce armpit temperature. That is, the thickness H
When the material is left at the entry side of the finishing mill for t hours, the material temperature decreases as expressed by the following equation.

Ts'Material temperature at the finishing input side Tn'Material temperature at the exit side of the rough rolling millIn the case of the finishing input side temperature in Figure 3, the time to reach from the exit side of the rough rolling mill to the finishing input side (tl-1I1 minute already The temperature is dropping and after another (4'2) hours all the material enters the finishing mill.

Figure 4 shows the temperature curve for the coil pock case. In the case of a material wound into a coil box, in addition to the heat insulation effect of the box, the coiled material warms itself, so the entire coil is kept at a constant temperature, and even when finishing rolling is performed, the temperature at the finishing input side remains constant. It is possible to maintain almost the initial value.

This is because the amount of heat that is radiated and transferred into the air is small, and because it is coiled, even if it is unwound, the temperature of the last part of the material will not drop much due to its heat retention effect.

As described above, the important effect of the coil box is that the finishing entrance temperature can be kept constant over the entire length.

The first three effects are energy saving features. As explained in the second effect, the coil box has a heat retention effect. This means: That is, assuming that the finishing input side temperature is not changed, the coil box output side temperature may be low, and the heating furnace extraction temperature thereof may be low.

It is necessary to control a finishing rolling mill that takes advantage of the functions of a coil box that has many of these features. When the finishing inlet temperature is constant, the finishing outlet temperature can be rolled at a constant value, and it is expected that the spray cooling water on the hot run table can be controlled easily and accurately, resulting in high quality. can produce rolled material.

[Purpose of the invention]

The present invention takes advantage of the constant material temperature, which is a feature of the coil box, and controls the entire length of the material so that it reaches a predetermined finishing exit temperature without changing the finishing rolling speed, thereby saving energy and producing high-quality materials. There is K.

[Summary of the invention]

The feature of the present invention is that in a rolling equipment in which a coil box is provided between a rough rolling mill and a finishing rolling mill, the finishing rolling temperature is set, the speed of the rolling mill on the entry side from the coil box to the finishing rolling mill is detected, A finish rolling speed is calculated and set from the converted temperature value, the soaking time of the heating furnace is completely changed according to the deviation between the finish rolling temperature set value and the finish rolling mill exit temperature, and the finishing rolling speed is set at the finishing rolling mill exit side. The purpose is to control the temperature.

[Embodiments of the invention]

First, the basic matters of the present invention will be described.

The finish rolling speed is determined as follows.

In the conventional control device, the input information was given from material specifications, etc., but in the present invention, in order to control the finishing temperature to a predetermined value, the control device side inputs the finishing exit temperature Ty and finishing rolling speed V'y.
Determined by a k-th order relational expression.

As a result, Vv is calculated, where Tr is the predetermined finishing exit temperature and H is the material thickness. Further, control during rolling is performed by changing the inter-stand spray flow rate of the finishing rolling mill to 1 when the finishing outlet temperature during rolling does not fall within an allowable tolerance centered on a predetermined value.

Periodic sampling of the finishing exit temperature TF is performed during rolling, and the temperature stability is confirmed by determining the average value of %TF+ and the root mean square value of the deviation from the target value Tro, where the sampled temperature data is kTr+. Ru.

The average value of unselected Ty 〒r is n; the number of samplings. Next, calculate the root mean square value of the deviation from the target value.The idea of learning control is as follows.

I 'I' when the difference between TF and TPO exceeds the allowable tolerance
vo TF l =IΔTrl>ΔTPO−・・−−
-(6) That is, at this time, β number x ΔTy is fed back to the finish rolling speed formula (3) to perform short-term learning control for the next material. Next, when 72 is larger than a certain value γ, 72≧
γ・・・・・・・・・・・・・・・・・・・・・・・・
Group... Old... (7) At this time, as a long-term study, feed back to the furnace combustion control device to lengthen the time the material is in the furnace, maintain a uniform heat state, and eliminate temperature unevenness within the material.

An overview of the present invention described above is shown in the flow diagram of FIG.

Next, an example of the present invention? It is shown in FIG. In Figure 6, l
A computer or the like is used in the rolling mill control device according to the present invention. 2 is a heating furnace combustion control device, and 3 is a heating furnace. 8 is a rough rolling mill, IO is a coil box, and 6 is a finishing mill. 7a is a rough rolling mill exit side thermometer, 71) is a finishing inlet side thermometer, 9 is a finish rolling speed control device, and 20 is an inter-stand spray cooling water control device. 11 is the finish exit side thermometer, 1
2 is a run-out table spray cooling water system, and 13 is a down coiler system.

In FIG. 6, the rolling mill control device l is a finishing entry side thermometer 7.
Enter the actual finish entry temperature Tsk from b, calculate the finish rolling speed Vvk using equation (3) to achieve the target finish temperature Trok given by the business computer 14, and set all finish rolling speeds to the finish rolling speed control device 9. do. Rolling is started and the material is finished 1i111 The speed control device 9 is not a special device and may be any speed control device commonly used, and its details are omitted. After the rolling is interrupted and the material reaches the exit thermometer 11, the rolling mill control system #1 samples the actual finishing exit temperature.

At this time, if the target temperature deviates from the allowable tolerance, a water amount change command sound is output to the inter-stand spray cooling water control device io. After the rolling is finished, the rolling mill control device l (4)
(5) and (6) are used in the learning control 'i11. If long-term learning control is required, a soaking time change command is sent to the heating furnace combustion control device 2, and if short-term learning control is insufficient, it is sent to the In response, a feedback command is issued to the next material.

In this way, we perform control that takes advantage of the characteristics of the coil box, resulting in a constant finishing exit temperature and a high quality material. Obtainable.

〔Effect of the invention〕

According to the present invention, it is possible to efficiently control the finishing temperature in a rolling equipment equipped with a coil box.

[Brief explanation of drawings]

Is Figure 1 an example of rough rolling using a coil pox? show. FIG. 2 shows a complete example of finish rolling using a coil box. FIG. 3 is a diagram showing changes over time in the rough rolling mill outlet temperature TR and the finishing input side temperature Ts in conventional hot rolling. Figure 4 shows the width and summer T of rough rolling when using a coil pox.
It is a figure which shows the time change of R and finishing entry side temperature Ts. FIG. 5 is a diagram illustrating the principle of the present invention. 6th
The figure shows an embodiment of the invention. l...Calculator, 3...Heating furnace, 9...Rolling speed control device, grass 1 eye 3 eyes 4- eyes 'Iy5 mouth

Claims (1)

[Claims] 1. In a finishing temperature control method for a rolling equipment that has a coil box between a rough rolling mill and a finishing mill, finish rolling is performed using a given finishing target temperature and the measured rough rolling mill exit temperature or finishing entry temperature. All speed calculations are set, and depending on the deviation between the measured finishing outlet temperature and the set value, the soaking time is changed in the heating furnace combustion control device, and the finishing side temperature is controlled to a predetermined target value. A method for controlling the finishing temperature of a rolling mill, which is characterized by the smell.