JPS5952934B2 - Furnace temperature setting method for continuous annealing equipment heating zone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a continuous annealing equipment heating zone in which the furnace exit loss strip temperature is controlled by changing the set value of the furnace temperature control system for each zone according to the annealing conditions. This invention relates to a furnace temperature setting method for setting the temperature to a target value and varying the furnace temperature for each zone.

Continuous annealing equipment includes, for example, a heating zone 1, as shown in FIG.
A first soaking zone 2, a first cooling zone 3, a second soaking zone 4, and a second cooling zone 5 are provided, and a strip 6 in which the rear end of a thin plate coil and the tip of another coil are welded is attached to a strip 6, as shown in FIG. 2, for example. It provides a continuous thermal cycle.

The heating zone 1 of the continuous annealing equipment is, for example, as shown in FIG. There is one that heats the strip 6 by passing it up and down between seven rows of radiant tubes.

As a conventional strip temperature control method in the continuous annealing equipment heating zone 1, for example, the inside of the furnace is divided into six groups and the furnace atmosphere temperature is adjusted for each zone, and the strip temperature is indirectly controlled by this adjustment. It's in control.

To explain further, a furnace temperature detector 8 is provided for each zone,
Further, a target value of the furnace temperature is set in the furnace temperature setting device 9 in advance, and the furnace temperature controller 10 is set so that the furnace temperature detected by the detector 8 becomes the target value of the furnace temperature setting device 9. It controls the fuel flow rate controller 11.

Due to reasons such as meandering or poor shape of the strip in heating zone 1 as described above, the furnace temperature is varied for each zone to create a temperature difference, and the furnace is operated without changing the loss strip temperature. There are cases.

In this case, conventionally, the furnace temperature setting value was determined based on the operator's experience, but this would complicate the operator's work.
Even if the furnace temperature is set without looking at the detected value, the operator has to rely on his or her experience and intuition, resulting in problems such as poor control accuracy of the sl-IJ tube temperature.

The present invention was made in consideration of these circumstances, and its purpose is to reduce the work of the operator by automatically setting the furnace temperature when the furnace temperature is different for each zone. The present invention aims to provide a method for setting a furnace temperature in a heating zone of continuous annealing equipment, which can eliminate work errors, improve temperature control precision, and improve product quality and uniformity.

That is, the present invention is a method for controlling the heating strip temperature of continuous annealing equipment by changing the set value of the furnace temperature controller installed in each zone according to the annealing conditions, and the present invention provides a method for controlling the temperature of the heating strip of the continuous annealing equipment by changing the setting value of the furnace temperature controller installed in each zone according to the annealing conditions. If desired, use the relational expression A between a constant furnace temperature that does not change for each zone according to the strip temperature and annealing conditions, and the ratio of the amount of change in the strip temperature to the amount of change from the constant value in the furnace temperature of each zone. That is, a relational expression B between the influence coefficient and annealing conditions is determined in advance, a constant furnace temperature is first obtained using the relational expression A, and the above-mentioned relational expression B is used from the constant furnace temperature and the required furnace temperature difference. ) Continuous annealing equipment characterized in that the difference between the constant furnace temperature and the furnace temperature of each zone is determined without changing the IJ tube temperature, and the furnace temperature of each zone obtained from the difference is set on a furnace temperature controller. This is a method of setting the furnace temperature of the heating zone.

In this case, the above-mentioned relational expressions A and B may be determined in advance by sorting out actual data or using a theoretical mathematical model of heat balance.

The method of the present invention will be explained below based on the embodiment shown in FIG.

In this example, the main operations for realizing the present invention are performed by a computer (minicomputer, microcomputer, large computer, etc.).

Symbols a and i in the figure are input signals to the computer 12, and symbols ji (i=1 to 6) are output signals from the computer 12, and the contents of the symbols are as follows.

1) Input a...Detection signal by the heating strip loss strip temperature detector 13...Detection signal by the i-th zone furnace temperature detector 8 (i=1 to 6) C... ...Detection signal d by line speed detector 14
...Plate thickness e...Plate width f...Steel type g...Annealing speed (target value) h...Heating strip loss strip Temperature (target value) i...Memorial furnace temperature temperature difference In this case, d-i is input into the computer for each coil.

2) Outputs 1 to J+...Fifth zone furnace temperature control system set value signal input to furnace temperature setting device 9 Target furnace temperature temperature difference (as shown in the above annealing condition a-41 and FIG. 5) When ΔTz) is input to the computer 12, the computer 12 determines the furnace temperature setting value for each zone in the following manner.

First, relational expressions A and B are input into the calculator 12 in advance.

Relational expression A is expressed by the following expression.

Tzo=fC(ts, W5.V5.Ts) Also, relational expression B is expressed by the following expression.

C1=4. (t59w8.v5.Ts) In these relational expressions A and B, t5: plate thickness 0→Ws: plate width
0→v5 Niline speed
(mpm) T5: Heating zone lost IJ tube temperature (target value) (C) Tzi' i-th zone furnace temperature setting value (0) T2o: Furnace temperature when each zone is constant (C) fo: Each zone is constant Relational formula for determining furnace temperature A(0)ΔT: Target furnace temperature temperature difference
(C) ΔTzi ” l Tzi
−Tzo l (C) (=Oi):
Influence coefficient of i-th zone furnace temperature on heating zone exit (-) Strip temperature (ratio of change in strip temperature to change in furnace temperature in each zone from a constant value) ′i″ ゛wings ±7. .6if!i, a*x + From this relational expression A, enter the annealing conditions input into the calculator 12 to obtain a constant furnace temperature Tzo, and use relational expression B from this constant furnace temperature Tzo and the required furnace temperature difference ΔTz to perform stripping. The difference ΔTzi between the constant furnace temperature Tzo and each zone furnace temperature Tzi without changing the temperature Ts is determined, and from this difference, the furnace temperature Tzi of each zone is determined.
get.

That is, the target furnace temperature temperature difference ΔTz and ΔTzi (Tzi
-TzO), the following simultaneous equations are obtained, and by solving these, the furnace temperature set value for each zone is determined.

-C, ΔTZ1-C2ΔTz2-c3ΔTz3+C4Δ
Tz4+C5ΔTz5+C6ΔTz6= O(1)ΔT
z1-ΔTz2=ΔTz3(2) ΔTz4=ΔTz5-ΔTZ6(3) ΔTz1+ΔTz4-ΔTz (
4) By solving this, ΔTzi can be found.

That is, equation (2). Substituting (3) into equation (1) gives -(C1+C2+C3)ΔTZ1+(C4+C5+C
6)ΔTz4=0
(5) Substituting (4) into (5), we get (C4+C5+C6) (ΔTz-ΔTz4)+(C
4+C5+C6)ΔTZ4-0 −(C1+q0C3)ΔTZ+ (CI+C2+C3+
C4+C5+C6) ΔTz4-0 ΔTz1-ΔTz-ΔTz4(7) ΔTz2-ΔTz1(8) ΔTz3=ΔTz1(9) ΔTz5=ΔTz4(10) ΔTz6=ΔTz4(11) Therefore, the furnace temperature settings for each zone are as follows. It is found by the formula of .

Tzi = Tzo-ΔTzi (i=1-3)Tzi
= Tzo + ΔTzi (i = 4 to 6) As explained above, according to the present invention, in order to prevent strip meandering, etc., it is desired to set the furnace temperature of each zone of the continuous annealing equipment heating zone to a different value without changing the furnace exit loss strip temperature. When a predetermined furnace temperature and temperature difference are given, the furnace temperature setting value for each zone is automatically calculated, and the furnace temperature is controlled based on the set value, eliminating the complicated work of the operator. Since the settings are automatically changed using experimental formulas or theoretical formulas based on heat transfer calculations without relying on experience, fluctuations in the temperature of the heating strip loss strip are reduced, resulting in remarkable effects such as improved product quality and uniformity. .

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of continuous annealing equipment, Fig. 2 is an explanatory diagram showing an example of a thermal cycle for heat treatment in continuous annealing equipment, and Fig. 3 is a strip temperature of the heating zone of conventional continuous annealing equipment. 4 is an explanatory diagram showing a control method, FIG. 4 is an explanatory diagram of a strip temperature control method showing one embodiment of the method of the present invention, and FIG. 5 is an explanatory diagram showing a target furnace temperature temperature difference in each zone. 1... Heating zone, 2... First soaking zone, 3
...First cooling zone, 4...Second soaking zone,
5...Second cooling zone, 6...Strip, 7...Curved radiant tube, 8...Furnace temperature detector, 9...Furnace temperature setting equipment, 1o... Furnace temperature controller, 11... Fuel flow rate controller, 12... Song/calculator, 13... Heating zone loss l-IJ tube temperature detector, 14... ...Zone furnace temperature detector, 15... line speed detector.

Claims (1)

[Claims] 1. In a furnace temperature setting method for a continuous annealing equipment heating zone in which the outlet strip temperature is controlled by changing the set value of a furnace temperature controller installed in each zone according to the annealing conditions, the furnace temperature is changed for each zone according to the strip temperature. A relational expression A between the constant furnace temperature and the annealing conditions, and a relational expression B between the annealing conditions and the ratio of the amount of change in the strip temperature to the amount of change from the constant value of the furnace temperature in each zone are determined in advance. Ok, relational expression A
From the constant furnace temperature and the required furnace temperature difference, find the difference between the constant furnace temperature and each zone furnace temperature that does not change the strip temperature using the relational formula B, and then A method for setting a furnace temperature in a heating zone of continuous annealing equipment, characterized in that the furnace temperature of each zone obtained from the difference is set in the furnace temperature controller.