JPH04168232A - Plate temperature control method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the temperature of a strip at the furnace outlet of a continuous annealing furnace.

[Conventional technology]

In a heating furnace of a continuous annealing furnace, various strips having different strip specifications such as plate thickness and width, and target plate temperatures at the outlet of the heating furnace are successively threaded by welding. The heating furnace has a plurality of heating zones, and these heating zones are configured to be individually temperature controlled. In a heating furnace configured in this way, the outlet plate temperature of each strip is controlled by setting the temperature of each heating zone based on the information of each strip specification and the target plate temperature at the outlet of the heating furnace. There is.

However, with only the preset control described above, the actually measured outlet plate temperature does not match the target plate temperature, so feedback control is performed to change the set temperature of each heating zone based on these plate temperature deviations.

FIG. 4 is a flowchart showing the process of conventional plate temperature control. First, information on the strip specifications and the target plate temperature at the outlet of the heating furnace is taken in (step SL). Next, the temperature of each heating zone is set based on this information (step S2).

Then, the plate temperature at the outlet of the heating furnace is actually measured and the information is taken in (step S3).

The deviation of the measured plate temperature from the target plate temperature is calculated (step S4). Based on the deviation obtained in step S4, the amount of change in the temperature setting value for each heating zone is calculated (step S5). Then, the set temperature of each heating zone is changed (step S6).

[Problem to be solved by the invention]

However, the response to changes in the heating furnace's set temperature is slow;
Especially near the welding point of strips with different specifications (unsteady region)
Therefore, if the above control method is implemented, the deviation of the actually measured plate temperature from the target plate temperature will become wider. Therefore, the above control method should be implemented only in the steady region excluding the unsteady region, and Only preset control was used to set the furnace temperature.

Therefore, in order to reduce the deviation in plate temperature over the entire length of the strip, it has been desired to develop a method for controlling the plate temperature over the entire length of the strip, including the unsteady region.

The present invention has been made in view of the above circumstances, and the present invention is based on the temperature of each heating zone and the sample points measured when a plurality of sample points defined in the longitudinal direction of the strip pass through each heating zone of the heating furnace. The plate temperature of the sample point at the outlet of the heating furnace is calculated from the residence time of each heating zone, and the deviation of the actually measured outlet plate temperature of the sample point from the calculated plate temperature is calculated to calculate the amount of change in the temperature set value, and the temperature setting value is set for each heating zone. It is an object of the present invention to provide a sheet temperature control method that reduces sheet temperature deviation over the entire length of the strip and improves the yield and quality of finished products by changing the temperature.

[Means to solve the problem]

The strip temperature control method according to the present invention changes the temperature setting values of a plurality of heating zones that are individually temperature-controlled in the heating furnace of a continuous annealing furnace that continuously anneales the strip, thereby increasing the temperature of the strip at the outlet of the heating furnace. In a plate temperature control method for controlling the temperature of a strip, heating is determined from the temperature of each heating zone measured when a plurality of sample points defined in the length direction of the strip pass through each heating zone and the time the sample points stay in each heating zone. While calculating the plate temperature at the sample point at the furnace outlet, measure the outlet plate temperature at the sample point, find the deviation of the actual plate temperature from the calculated plate temperature, and calculate the amount of change in the temperature setting value of each heating zone from the deviation. death,
It is characterized by changing the set temperature of each heating zone.

[Effect]

In the present invention, the temperature of each heating zone measured when a sample point defined in the length direction of the strip passes through each heating zone of the heating furnace of a continuous annealing furnace and the residence time of each heating zone of the sample point are used. Since the amount of change in the temperature setting value for each heating zone is calculated, it is possible to appropriately correct the setting temperature in consideration of the actual heating conditions of the IJ tube, and the response to changes in the setting temperature becomes faster.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, and in the figure, 1 is a heating furnace of a continuous annealing furnace. A plurality of hearth rolls are arranged above and below in the heating furnace 1, and a rack is passed between these hearth rolls, and the strip S is run back and forth in the vertical direction as shown by the arrow, and is heated to heating zones 1a, 1b. and 1c are sequentially threaded.

The temperatures of the heating zones 1a, lb and 1c are individually controlled by signals output from the arithmetic and control unit 4. In addition, thermometers 2a, 2b and 2c are installed in heating zones 1a, lb and 1c.
are provided, and sample points A, B, defined at regular or non-uniform intervals in the length direction of the strip S are provided.
The temperature of the heating zones 1a, lb, and 1c when ... passes through a predetermined position in the heating zones 1a, lb, and lc is measured by the thermometer 2.
a, 2b, and 2c, and the arithmetic and control unit 4 takes in the information. A plate thermometer 3 is provided at the outlet of the heating furnace 1, and the plate thermometer 3 measures the plate temperature when the sample points A, B, ... pass through the measurement area of the plate thermometer 3. , the information is taken in by the arithmetic and control unit 4. Note that the arithmetic and control device 4 determines the position starting from the time when the two coil materials were integrated by welding, and the transport distance of the strip S detected by the roll rotation speed detector 5 provided in the heating zone 1a. sample point A
, B, . . . , and when it is determined that the sample points A, B, .

FIG. 2 is a flowchart showing the process of plate temperature control according to the present invention. First, the arithmetic and control unit 4 determines the specifications of the strip S and the target plate temperature T at the outlet of the heating furnace. (Step Sl). Next, heating zones 1a, lb and 1
The set temperature TFPi of c is determined from the following equation (11) (step S2).

Tvp= = f Ci (Tso) −(1
1 However, fci: a function determined by each heating zone Next, sample points A, B, . . . determined in the length direction of the strip S
The temperatures of the heating zones 1a, lb and 1c measured when passing through the heating zones 1a, Ib and 1c are taken in, and the residence time of the sample points A, B, ... in the heating zones 1a, lb and 1c is calculated. (Step 7 S3).

Then, the plate temperature T'sc at the outlet of the heating furnace is sampled at point A.

B, . . . are determined from the following equations (2) and (3) (step S4).

However, G: Feedback gain Ts And finally, the set temperatures of the heating zones 1a, lb and IC are changed based on the temperature set value change amount TFF of the heating zones 1a, lb and 1c (step S8).

FIG. 3 is a graph showing the target plate temperature and the measured plate temperature when the coils α, β, and T are integrated by welding and the temperature is controlled by the conventional method and the method of the present invention. Figure 3 (a
) Steady part FB (feed hack) control, mountain) Full length FB
! II? Il and (e) Plate temperature deviation is a graph when the plate temperature is controlled by the conventional method, Fig. 3 (fd) is a graph showing the calculated plate temperature calculated by the method of the present invention, Fig. 3 (e) Full length FB control and (f) Plate temperature deviation shows a graph when the plate temperature is controlled by the method of the present invention. In addition, in the figure, the comparative example shows the actually measured plate temperature when only the preset control for setting the furnace temperature in advance is performed.

FIG. 3(a) is a graph showing the plate temperature when conventional feedback control is performed only in the steady region excluding the vicinity of the weld. In this case, since control is performed only in the steady range, the range in which the actual plate temperature matches the target plate temperature is short.

Figure 3 (b) is a graph showing the plate temperature when conventional feedback control is performed over the entire length of the strip, and Figure 3 (C) is a graph showing the deviation of the measured plate temperature from the target plate temperature in this case. This is a graph showing At this time, the vicinity of the weld (
The deviation of the measured plate temperature from the target plate temperature in the unsteady region is large, and this causes a further delay in response to changes in the furnace temperature setting, resulting in a hunting phenomenon in which the measured plate temperature is relative to the target plate temperature.

Fig. 3 (dl is a graph showing the plate temperature calculated by the method of the present invention. Fig. 3 (e) is a graph showing the plate temperature when the feedback control of the present invention is performed over the entire length of the strip. Figure 3 (C) is a graph showing the deviation of the measured plate temperature from the calculated plate temperature in this case. Figure 3 (el) shows that application of the method of the present invention reduces plate temperature deviations and increases the It can be seen that the plate temperature can be controlled over almost the entire length.

〔effect〕

As described above, in the present invention, the temperature of each heating zone measured when a plurality of sample points defined in the length direction of the strip pass through each heating zone of the heating furnace and the residence time of each heating zone of the sample points are determined. Calculate the plate temperature at the sample point at the outlet, find the deviation of the actually measured outlet plate temperature at the sample point from the calculated plate temperature, and calculate the amount of change in the temperature setting value for each heating zone.
Since the set temperature of each heating zone is changed, it is possible to appropriately correct the set temperature in consideration of the actual furnace condition.

As a result, the present invention exhibits excellent effects, such as reducing plate temperature deviation over the entire length of the strip and improving product yield and quality.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the implementation state of the method of the present invention, Fig. 2 is a flowchart showing the process of plate temperature control of the present invention, and Fig. 3 is the target when plate temperature is controlled by the conventional method and the method of the present invention. A graph showing the plate temperature and the measured plate temperature, and FIG. 4 is a flowchart showing the process of conventional plate temperature control. 1... Continuous annealing furnace 2a, 2b, 2c... Thermometer 3... Plate thermometer 4... Arithmetic control device S.
...Strip patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono S Figure 1 Figure 2 <Conventional method> (a) (b) (c) Method of the present invention> (d) ( e) Figure 3 Figure 4

Claims (1)

[Claims] 1. Control the plate temperature of the strip at the outlet of the heating furnace by changing the temperature setting values of a plurality of heating zones whose temperatures are individually controlled in the heating furnace of a continuous annealing furnace that continuously anneales the strip. In the plate temperature control method, the heating furnace outlet temperature is determined based on the temperature of each heating zone measured when a plurality of sample points defined in the length direction of the strip pass through each heating zone and the residence time of each heating zone of the sample points. While calculating the plate temperature of the sample point at the sample point, measure the outlet plate temperature of the sample point, find the deviation of the actual plate temperature from the calculated plate temperature, and calculate the amount of change in the temperature setting value of each heating zone from the deviation, A plate temperature control method characterized by changing the set temperature of each heating zone.