JPS6289821A - Line speed controlling method for continuous annealing equipment - Google Patents

Abstract

PURPOSE:To operate many kinds and sizes of continuous annealing equipments under optimum condition, by estimating thermal crown quantity or roll crown quantity of roll at calculating line speed and correcting controlled line speed to the value enabling stable operation. CONSTITUTION:From the formula relating to each capacity in each heating, soaking and cooling zone of continuous annealing equipment, annealing condition and characteristic of strip, and max. capacity line speed LS, respective speeds LS of the respective zones corresponding to strip characteristic are calculated. Simultaneously, line speed is controlled while using min. value in these speeds LS is standard. By the method, e.g. thermal crown quantity of hearth roll under the controlled line speed is calculated and the calculated value is in range of the aimed quantity or not is decided. If it is in controlled range, min. value in the speed LS is determined as the prescribed line speed. If it is out of controlled range, upper limit value of line speed where thermal crown quantity in the prescribed range is attained at <= min. value of the speed LS of the each zone is obtd., and line speed is controlled by setting this as prescribed value.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a line speed control method for continuous annealing equipment for metal strips, especially copper strips, and is useful when continuously annealing strips of various types and sizes. Maximum production while preventing strip meandering and heat buckling! We will propose an effective method for driving with (ability).

(Conventional technology) In recent years, with the diversification of products, it has been desired to develop continuous annealing technology to produce strips of various types and sizes at low cost and with high yield. Equipment has become available that has a wide control range and can arbitrarily change operating conditions for heating, soaking, cooling, etc. according to material constraints.

However, when continuously annealing strips of various types and sizes, it is necessary to perform annealing under optimal conditions for each strip and at the maximum capacity of the equipment in terms of production costs and production yields. Therefore, it becomes complicated to make judgments regarding operation matters, constraint conditions, etc. for a given strip, and to calculate the line speed for the maximum production amount, making it difficult to operate using conventional control methods. ' In other words, in order to continuously annealing six strips of each steel type and size to achieve the desired uniform quality, the optimal one is selected from a variety of heat patterns, and the soaking temperature and cooling rate are calculated for each strip i. Furthermore, after calculating these, it is necessary to calculate the line speed and operate the continuous annealing equipment in order to maximize the production of strips, but there are many points that are difficult to judge by the operator alone, especially the material etc. In strips, etc., where there are large restrictions, operation cannot be performed by an operator.

Various improvement methods have already been proposed to address these problems of the conventional technology, for example,
There is one proposed as No.-52937.

(Problems to be Solved by the Invention) However, the conventional method described above has the disadvantage that it does not take into consideration strip meandering or heat buckling, which are essential for stable operation in a continuous annealing furnace. This left a problem that needed to be resolved, that is, production could not be carried out at the maximum capacity line speed.

In short, the purpose of the present invention is to estimate the thermal crown amount or roll crown amount of the roll when calculating the line speed and correct the control line speed to a line speed that allows stable operation. An object of the present invention is to provide a line speed control method for continuous annealing equipment that can control the line speed to suit each optimum condition.

(Means for Solving the Problems) In order to solve the problems described above, the present invention aims to improve the heating, soaking, and cooling capacities (capacities) of the heating zone, soaking zone, and cooling zone in continuous annealing equipment. , the annealing conditions such as the furnace temperature, the strip characteristics such as the strip width, thickness, and temperature, and the relational expressions between the maximum capacity line speed are determined in advance, and from these relational expressions, the Assuming that the maximum capacity line speeds for each of the above-mentioned Nayoro lines are calculated, the minimum value of these maximum capacity line speeds is determined and this is the control target, and appropriate line speed control is performed, the above control line speeds are calculated. Calculate the original thermal crown amount or roll crown amount of the hearth roll, compare and determine whether the calculated value is within the target thermal crown amount or roll crown amount, and determine the thermal crown amount or roll crown amount within the control range. In this case, the minimum value of the above maximum capacity line speed is set as the set line speed, and if the thermal crown amount or roll crown amount is outside the control range, the line speed is set below the minimum value of the maximum capacity line speed of Nayoro and within the predetermined range. We propose a method in which the upper limit value of the line speed that results in the amount of thermal crown or roll crown is determined, and the line speed is controlled using the upper limit value as a set value.

(Example) A preferred embodiment of the method of the present invention, that is, a specific method for achieving stable running (no meandering or heat buckling) will be described below with reference to the drawings.

As shown in Fig. 2, strips 1 of various types and sizes are heated by radiant tubes, electric heaters, etc., heated by a heating zone 2 and soaking zone 3 for uniform temperature maintenance, and cooled by cooling tubes, plenum chambers, electric heaters, etc. It passes through the primary cooling zone 4, the secondary cooling zone 5, and the tertiary cooling zone 6 to be continuously annealed. In this continuous annealing, various heat patterns (X3.-・-Xt-
Select the optimal one for each strip from Xn),
Continuous annealing of strips of various types and sizes is possible by calculating the soaking water temperature, cooling rate, etc., and operating according to the heating pattern.

In the present invention, a process computer automatically selects the heat pattern for each strip, calculates the soaking temperature, cooling rate, etc., and calculates the optimum line speed for effectively using the continuous annealing equipment.

First, to obtain the heat pattern Xi shown in Figure 3, various strip data (standards, steel type, chemical composition, material, plate size, coil weight, etc.) managed by the host computer are transmitted to the process computer. This calculator calculates the heat pattern based on the standard, steel type, etc. Once the heat pattern is determined, the soaking temperature TS% cooling rate CR of the strip is calculated from the chemical composition and material.

Once the annealing conditions such as the heat pattern Xi, soaking temperature Ts, and cooling rate CP of a predetermined strip are calculated in this way, the maximum capacity line speed in each section of the continuous annealing equipment is determined.

The maximum capacity line speed LSIMAX of the heating zone 2 is calculated from equation (1).

Ls+ +Axf I(Q+ + W, o, T I
+Tsi) −°−−−−(1)Q: Heating capacity W of radiant tube or electric heater, etc. Nistrip width D Nistrip plate thickness T,: Strip temperature on the exit side of the heating zone Tz+: Furnace temperature of the heating zone The maximum capacity line speed LSzMAx of heating zone 3 is as follows (2
) is calculated from the formula.

LSzHax=fz(Qz+W+D41.Tz, TZz
+ t) ・−・・・・・・= (2) i12: Heating, soaking capacity of radiant tube or electric heater, etc. - Nistrip width D Nistrip plate thickness T,: Strip temperature on the soaking area input side T2: Soaking area output Side strip temperature TZ! : Furnace temperature L in soaking zone : Soaking time Maximum capacity line speed LS:1MAX-LS5MAX in each of primary to tertiary cooling zones 4 to 6 is as follows (3) to (5)
) Calculated from 2.

LSzqax=f+(Q*J+D+Tz+T3+TZz
+CR+t) "-' (3) LS414AX = f
a(qt+ w, o, T3 + Ta, Tza +
CR, t) −(41LSssax=fs(Q5.W
, D+T4+Ts+Tzs+CR+t)-(5)031
Cooling and heat retention capacity for ports, 9 ports, cooling tubes, plenum chambers, or electric heaters, etc. Strip width D Cost strip thickness T2. T:1. T,,,, TS: Strip temperature on the exit side of each cooling zone CR: Cooling rate t: Retention time Therefore, it is limited by the maximum capacity line speed LSIM□~LSS□8 of the name book (section) calculated above and the mechanical and electrical system. From the maximum line speed LS of the equipment to be used, the maximum capacity line speed LS for the specific strip is calculated as follows (6)
It can be obtained from the formula.

LS-gate IN (LSIM^x, LSz□X, LS3M
A, LS4MAX, LSS□×.

LS, ) −
・(6) In order to calculate the maximum capacity line speed, (1
) to (5) are calculated theoretically by heat transfer calculations,
It can be obtained by an empirical method based on experimental data or a combination of both methods.

The LS calculated by the above equation (6) becomes the capacity limit value of the annealing furnace, but in the present invention, the amount of thermal crown of the hearth roll in the furnace when calculating the LS calculated by the equation (6) is set as follows (
It is calculated in advance using the formula 7), and the calculation method is based on the strip temperature TS at each hearth roll position and the furnace temperature.

ΔT++t = f(Ls, W, D, Tsi, Tzi)
----(7) ΔTR1: Temperature difference ΔTR of the hearth roll calculated using the temperature difference Tsi: between the center and edge of the i-th roll as the strip temperature at the roll position (7)
If I is within the specified temperature deviation (±30°C), (6
) Control is performed by using the LS obtained by the equation as it is as the setting value of the line speed.

On the other hand, ΔTl11 calculated by equation (7) is within the predetermined temperature deviation ±
When it is higher than 30°C, correct LS to below the minimum value (L
S=αx LS) (α<1), then recalculate using equation (7) to obtain LS so that ΔTli is within a predetermined temperature deviation, and control this LS as the set value of the line speed.

The control flow during this period is shown in FIG.

In the above embodiment, the thermal crown amount of the roll is determined to determine LS, but the roll crown amount may be calculated and determined based on the thermal crown amount.

(Effects of the Invention) As explained above, according to the method of the present invention, by calculating the maximum capacity line speed at Nayoro and simultaneously calculating and controlling the amount of thermal crown of each hearth roll, meandering of the strip can be prevented. Since the line speed is controlled at a line speed that does not cause heat buckling, the operation of continuous annealing equipment of various types and sizes can be controlled under optimal conditions (stable and maximum production).

[Brief explanation of drawings]

FIG. 1 is a flow diagram of a line speed control method in an embodiment of the present invention, FIG. 2 is an explanatory diagram of continuous annealing equipment, and FIG. 3 is an explanatory diagram showing a heat pattern in continuous annealing equipment. 1 - Strip 2 - Heating zone 3 - Soaking zone 4 - 6 - Primary or tertiary cooling zone Figure 2 Figure 3

Claims (1)

[Claims] 1. Based on the annealing conditions in each heating, soaking, and cooling zone of the continuous annealing equipment obtained in advance, and the relational expression between the strip characteristics and the maximum capacity line speed, each of the above conditions corresponding to the strip characteristics is determined. In the method of calculating each maximum capacity line speed in the belt and controlling the line speed based on the minimum value of these maximum capacity line speeds, the thermal crown amount or roll of the hearth roll under the above control line speed is Calculate the crown amount, compare and judge whether the calculated value is within the range of the target thermal crown amount or roll crown amount, and if the thermal crown amount or roll crown amount is within the control range, set the maximum capacity line speed above. The minimum value of these is the set line speed, and if the thermal crown amount or roll crown amount is outside the control range, the thermal crown amount or roll crown amount will be within the predetermined range below the minimum value of the maximum capacity line speed of each band. A line speed control method for continuous annealing equipment, comprising determining an upper limit value of the line speed and controlling the line speed using the upper limit value as a set value.