JPH07258751A - Device for controlling temperature of coil in furnace - Google Patents

Abstract

PURPOSE:To secure a desired constant quality and to improve the productivity by making the temp. gradient variable according to the thickness of a coil, at the time of heating the coil in a continuous annealing furnace. CONSTITUTION:In the case of continuously heating the coil 5 in the annealing furnace 1, when the sheet thickness data (d) of coil 5 is outputted to an optimum heating temp. arithmetic part 13 from a coil data part 11 at the time of controlling the temp. of the coil 5, based on a reference temp. T1 as an aimed temp. at the time of the max. sheet thickness, the arithmetic part 3 transmits the higher optimum heating aimed temp. T1' to an annealing pattern generating part 12 as the sheet thickness (d) is made smaller. As a result, in the case of the max. sheet thickness, the annealing temp. pattern shown by a solid line is generated from an annealing pattern generating part 12 and in the case of the min. sheet thickness, the annealing temp. pattern shown by a broken line is generated, and in the case of the thin coil 5, the heating aimed temp. is changed so that the temp. raising rate at the front step zone becomes high. By this method, the heating aimed temp. is set to the optimum state according to the thickness of the coil 5 and the desired fixed quality can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil temperature control device used in various furnaces such as steel and metal processing plants, and more particularly to a coil target when a temperature control pattern and a plate passing capacity in the furnace are used. The present invention relates to a furnace coil temperature control device having improved temperature setting means.

[0002]

2. Description of the Related Art Generally, a coil temperature controller for a continuous annealing furnace or the like is constructed as shown in the block flow of FIG. In the figure, 1 is a continuous annealing furnace,
This is composed of, for example, four zones Z1 to Z4, heaters 2 are installed in these zones Z1 to Z4, respectively, and a PI for controlling the temperature of each heater 2 individually.
A D adjustment calculator 3 is provided. Each PID adjustment calculation unit 3 obtains the temperature operation signal of each zone based on the deviation between the furnace temperature target value SV and the temperature PV detected by the temperature detector 4 for each zone, and then determines the heater 2 corresponding to each zone. By heating, the annealing temperature of the coil 5 that continuously passes through the inside of the annealing furnace 1 is controlled.

By the way, conventionally, the setting of the furnace temperature target value SV for each PID adjustment calculation unit 3 is performed in the first zone Z1.
An annealing pattern generation unit 6 that generates an annealing temperature pattern that gradually increases the target temperature of the coil 5 in the order of the fourth zone Z4, a coil data unit 7 that outputs various data necessary for controlling the temperature of the coil 5, and A zone-specific target temperature calculation unit 8, which determines a furnace temperature target value SV for each zone, ...
Is provided.

Then, from the annealing pattern generating section 6, the coil heating target temperatures T _i-1 , T _i (T _i-1 :
Temperature at each zone entrance, T _i : outlet temperature of each zone), and coil data x such as plate thickness d, plate width w, specific gravity ρ, specific heat Cp, and thermal conductivity α is generated from the coil data section 7. It is output and introduced into the zone-specific target temperature calculation unit 8 together with the line speed v.

Therefore, each target temperature calculating section 8 uses the signals T _i-1 , T _i , x, v obtained from the annealing pattern generating section 6, the coil data section 7 and the like to obtain various conventionally known heat loads. The furnace temperature target value TFi (T _F1 ~
T _F4 ) is determined and supplied to the PID adjustment calculation unit 3 corresponding to the zone as the furnace temperature target value SV.

[0006]

By the way, the above-mentioned annealing temperature gradient of the coil, and hence the gradient between T _{i-1 and} T _{i of the} annealing temperature pattern, is usually the wall thickness produced most in the corresponding equipment. It is determined based on the heating capacity of the furnace in the so-called common use thickest coil 5 and the operation target line speed.

Therefore, in obtaining the same annealing quality, the coil 5 having a thickness larger than the usual maximum thickness is operated at a lower line speed. This is addressed by lowering the furnace temperature without changing the operation line speed due to the capacity of equipment.

As a result, in the case of the thin-walled coil 5, since the line speed cannot be increased due to the equipment capacity, the furnace temperature must be lowered while the heating capacity of the furnace is sufficient. Becomes worse, and the smaller the plate thickness of the coil, the more noticeable the effect.

The present invention has been made in view of the above circumstances. By varying the temperature gradient according to the wall thickness of the coil, the line speed can be varied while effectively utilizing the heating capacity of the furnace. An object of the present invention is to provide a furnace coil temperature control device capable of improving productivity while ensuring desired constant quality.

[0010]

In order to solve the above-mentioned problems, the invention according to claims 1 and 2 uses a data and a temperature pattern related to a coil which is continuously threaded. In a coil temperature control device for a furnace for determining a furnace temperature target value and heating the coil, a temperature pattern variable for varying a temperature gradient of a temperature pattern based on at least a coil plate thickness of a plate thickness and a plate width of the coil. It is a coil temperature control device of a furnace provided with means.

When varying the temperature gradient of this temperature pattern, a predetermined reference temperature pattern is used at the maximum plate thickness, while the thinner the coil plate thickness, the higher the temperature rise rate on the inlet side of the furnace. The temperature gradient of the reference temperature pattern is changed.

[0012]

Therefore, according to the inventions corresponding to claims 1 and 2, by taking the above-mentioned means, it is possible to increase the temperature rise rate of the inlet side zone inside the furnace as the plate thickness of the coil becomes thinner. By changing the temperature gradient of the pattern, the temperature range that greatly affects the quality of the product can be reached quickly, and by increasing the line speed in this state, the product of the desired quality can be obtained regardless of the change in the wall thickness. Can contribute to the improvement of productivity.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a control device according to the present invention. In addition, in FIG.
Since 5 and 8 have substantially the same configuration as that of FIG. 5 described in the prior art, the description of the functions and the like related to such reference numerals will be omitted, and the different points will be described below.

In addition to the coil data section 11, this control device
An annealing pattern generator 12 and an optimum heating temperature calculator 13 are newly provided as temperature pattern changing means. Here, the coil data unit 11 introduces the coil data x such as the plate thickness d, the plate width w, the specific gravity ρ, the specific heat Cp, and the thermal conductivity α to the target temperature calculation unit 8 corresponding to each zone, as described above. Of the coil data x, especially plate thickness data d
Is output to the optimum heating temperature calculation unit 13.

The optimum heating temperature calculation unit 13 obtains the optimum heating target temperature Ti 'after using the plate thickness data d from the coil data unit 11 and the coil heating target temperature reference value Ti input from the outside, It is supplied to the annealing pattern generator 12.

The annealing pattern generating section 12 includes the coil 5
It has a function of creating and outputting an annealing temperature pattern that changes so that the temperature gradient of the front-stage zone of the furnace becomes larger as the plate thickness becomes thinner, and introduces it into the target temperature calculation unit 8 corresponding to each zone.

Therefore, according to the control device of the above embodiment, when the temperature of the coil 5 is controlled, the plate thickness data d of the coil 5 is output from the coil data unit 11 and input to the optimum heating temperature calculation unit 13. In the operation unit 13, for example, the first
The zone Z1 of FIG. 2 will be described. As shown in FIG. 2, the polygonal line is based on the reference temperature T ₁ which is the target temperature at the maximum plate thickness, and the optimum heating target temperature T ₁ ′ becomes higher as the plate thickness d becomes smaller. Since it is set as a function, a large optimum heating target temperature T ₁ ′ is output in the case of a thin coil and sent to the annealing pattern generating unit 12.

As a result, if the horizontal axis represents the zone NO and the vertical axis represents the heating target temperature Ti, the annealing pattern generating section 12 produces an annealing temperature pattern as shown by the solid line at the maximum sheet thickness as shown in FIG. However, on the other hand, at the minimum plate thickness, the annealing temperature pattern as shown by the broken line is generated. That is, in the case of the thin-walled coil 5, the heating target temperature is changed so that the rate of temperature rise in the preceding zone becomes large. This means that the temperature gradient of the annealing temperature pattern changes between the solid line and the broken line depending on the plate thickness d.

In the prior art, since the annealing temperature pattern is a fixed temperature pattern such as a solid line, the line speed cannot be increased when the thin-walled coil enters the annealing furnace at the line speed at the limit of the facility capacity. The furnace temperature was controlled to be lowered because it was a fixed temperature pattern assuming the maximum plate thickness.However, in this control method, annealing was performed based on the optimum heating temperature according to the plate thickness under an appropriate line speed. The heating target temperature of the temperature pattern can be set to an optimum state.

Incidentally, comparing the annealing temperature pattern of the conventional apparatus and the annealing temperature pattern of the embodiment according to the present invention at the minimum plate thickness, the soaking temperature range ΔT which affects the quality of the product is shown by the conventional solid line. In the annealing temperature pattern of No. 1, the zone length L ₁ for almost one zone is included, but in the annealing temperature pattern of the broken line according to the present invention, the zone length L ₂ for _two or more zones can be included.

This means that in the case of the device of the present invention, in order to obtain the same soaking temperature, it becomes possible to operate at a line speed more than twice that of the prior art, and it is possible to greatly improve the operation rate and hence the productivity. .

Next, another embodiment of the device of the present invention will be described with reference to FIG. In this embodiment, the coil data unit 11 outputs the plate thickness d and the plate width w and introduces them into the optimum heating temperature calculation unit 13. The calculation unit 13 uses the plate thickness d × the plate width w as a variable factor of the horizontal axis x, and obtains the optimum heating target temperature Ti ′ based on the coil heating target temperature reference value Ti input from the outside.

Therefore, according to this embodiment of the control method,
The target heating temperature of the coil can be output based on the annealing temperature pattern with a more appropriate temperature gradient, the heating capacity of the furnace is effectively used, and the line speed is reduced during normal operation. Therefore, productivity can be improved while ensuring stable quality.

Further, in the above embodiment, the optimum heating temperature calculation unit 13 uses the polygonal line function as shown in FIG. 2, but the optimum heating target temperature Ti 'is obtained by the following calculation formula, for example. Good.

[0025] Ti '= Ti · {k · (d x / d 0) n + (1 + k)} However, Ti in the above equation: target temperature at the maximum thickness, k:
Coefficient (0 <k ≦ 1), d _x : plate thickness at that time, d ₀ : maximum plate thickness, ⁿ : power multiplier (0 <n).

When the plate width w is used in this arithmetic expression, d _x may be d _x × w _x and d ₀ may be replaced with dw ₀ . Here, w _x is the plate width at that time, and dw ₀ is the maximum value of plate thickness × plate width.

Although the above embodiment is applied to the continuous annealing furnace, the present invention can be similarly applied to the temperature control of the coil passing through another furnace. In addition, the present invention can be modified in various ways without departing from the scope of the invention.

[0028]

As described above, according to the present invention, the heating capacity of the furnace can be effectively utilized by varying the temperature gradient in accordance with the wall thickness of the coil, and the production can be performed by increasing the line speed. The ability can be increased, and the productivity can be increased while ensuring the desired constant quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a coil temperature control device for an annealing furnace according to the present invention.

FIG. 2 is an explanatory diagram of an optimum heating temperature calculation unit in FIG.

FIG. 3 is a diagram showing an example of an annealing temperature pattern of an annealing temperature pattern generating portion in FIG.

FIG. 4 is a block diagram showing another embodiment of the coil temperature control device for the continuous annealing furnace according to the present invention.

FIG. 5 is a block diagram showing a conventional control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Annealing furnace, 2 ... Heater, 3 ... Adjustment calculation part, 4 ... Temperature detector, 5 ... Coil, 8 ... Target temperature calculation part, 11 ... Coil data part, 12 ... Annealing pattern generation part, 13 ... Optimal heating temperature Arithmetic section.

Claims (2)

[Claims] 1. A coil temperature control device for a furnace, which determines a furnace temperature target value by using data and temperature patterns related to the coil for continuously passing the coil, and comprising: A coil temperature control device for a furnace, comprising temperature pattern changing means for changing a temperature gradient of a temperature pattern based on at least a coil plate thickness among a plate thickness and a plate width. 2. The temperature pattern uses a predetermined reference temperature pattern at the maximum plate thickness, and the temperature gradient of the reference temperature pattern is such that the temperature increase rate on the inlet side in the furnace increases as the coil plate thickness decreases. 2. The coil temperature control device for a furnace according to claim 1, wherein