JPH02173219A - Heat treating apparatus for metal strip coil - Google Patents

Abstract

PURPOSE:To uniformly and efficiently heat and cool the whole coil in good accuracy by arranging divided sections corresponding to cover roof part and coil receiving table in an apparatus and respectively controlling heaters and cooling devices arranged in each section. CONSTITUTION:Upper heaters 10a-10c, upper cooling fluid nozzles 14a-14c and lower heaters 11a-11c, lower cooling fluid nozzles 15a-15c divided into three or more sections, respectively are arranged at inside of the roof part of the inner cover 8 and upper face part of the coil receiving table 7. Each voltage of the upper and lower heaters 10a-10c, 11a-11c is adjusted with variable resistors 12a-12f to heat them so that temp. measured value at each part of the coil 1 becomes the prescribed heat pattern. At the time of cooling, the cooling fluid quantities into the upper and lower nozzles 14a-14c, 15a-15c are adjusted through valves 16a-16f. The side wall of the inner cover 8 is formed with the heat insulating material and the above divided sections are mutually parted with the heat insulating material.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a metal strip coil heat treatment apparatus that can uniformly heat and cool the entire metal strip coil.

<Prior art> In the annealing process of cold-rolled steel strips, etc., steel strips are stacked in a coil shape due to metallurgical requirements, and the metal string coil (
A coil (hereinafter referred to as a coil) is placed on a coil holder inside an inner cover filled with a specific atmospheric gas, and the outer top and sides of the inner cover are heated with a burner or other heating device to indirectly generate heat. was heating the coil.

FIG. 4 shows this conventional heat treatment apparatus. In FIG. 4, 1 is a coil, 2 is a coil holder, 3 is an inner cover, 4 is a furnace in which the inner cover is installed (called an outer cover), 5 is a hearth, and 6 is a burner for heating the inner cover.

<Problems to be Solved by the Invention> However, in the conventional heat treatment apparatus described above, each part of the coil is There was a drawback that the temperature could not be uniformly cooled.

This will be explained in detail with respect to each point of the coil shown in FIG. 2 (+) and (2).

■During the heating period, the rise in temperature at point E is delayed compared to the temperature at points A, B, C, D, and 0. In particular, the temperature at point A was likely to rise, causing deformation of the plate shape and deterioration of quality in this area.

■During the cooling period, the temperature drop at point E is delayed compared to points A, B, C, D, and 0 all at once. In particular, the temperature at point A was prone to drop, causing the same problems as in the heating period.

In this way, in the conventional heat treatment equipment described above, each part of the coil is not heated and cooled uniformly, so the metallurgically required heat pattern (temperature ff to be met in the heating and cooling process)
It is difficult to achieve this (history), so a slow heating and slow cooling method is usually used, and the operation is often carried out so that point E follows a predetermined heat pattern. This was not favorable in terms of efficiency. Moreover, as in the conventional heat treatment apparatus described above, the side surface of the coil (A in the figure)
When heating and cooling is performed from the BC surface, the heat transfer in the radial direction of the coil varies considerably depending on plate thickness, number of turns, contact conditions, etc., so it is difficult to estimate the temperature at each point of the coil, and it is difficult to estimate the temperature at each point of the coil. uniformly heated in a predetermined heat pattern.
It was difficult to cool down. In particular, to measure the temperature at point E, a method of estimating the temperature at point E from another point (for example, point A) is used, but it is extremely difficult to measure for the reasons mentioned above. .

In order to solve this problem, Japanese Patent Publication No. 60-27736 proposes that, in a continuous coil heat treatment furnace in which the hearth moves in increments, a coil holder with a hollowed-out inside like a drainboard is placed inside the inner cover. An electric heater is arranged concentrically on the hearth facing the lower end surface of the coil placed on the ii.
A coil heating device for a continuous coil heat treatment furnace has been proposed, which includes an electric heater temperature control device and a power source connected to the electric heater at each stop position of the hearth.

However, with this device, it is possible to heat the coil from the bottom surface as well, so although it is possible to eliminate the temperature difference between the top and bottom surfaces of the coil, it is difficult to uniformly heat and cool the entire coil.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a heat treatment apparatus that can uniformly heat and cool the entire coil with high precision and efficiency.

<Means for Solving the Problems> The present inventor believes that the causes of the problems with the conventional device are: ■ Heating was performed through the inner cover and was indirect; ■ Heating and cooling were performed due to the height of the coil. This is due to the fact that it was not possible to take proactive measures to control the temperature distribution of the coil because it was carried out two-dimensionally from the direction and the radial direction, and the characteristics of heat transfer in the two directions overlapped and were complicated. I found out.

Therefore, the inventor of the present invention aimed to: (1) Heate and cool the coil mainly through the top or bottom surface of the coil to minimize heat transfer through the side surfaces of the coil; The present invention was completed by directly performing heating and cooling and by ensuring that the control was performed with sufficient precision.

That is, the present invention provides a heat treatment apparatus in which a metal strip coil is placed on a coil holder in a heat treatment furnace, covered with an inner cover, and heated and cooled in a predetermined atmosphere, in which at least three compartments are provided inside the ceiling of the inner cover. An upper heater is provided which individually heats the metal strip coils which are divided concentrically and located directly below the divided sections, and a divided section of the ceiling of the inner cover corresponding to the divided section of the upper heater is provided. An upper cooling device is provided for cooling the coils individually from the outside, and a lower heater is provided for individually heating the metal strip coils, which are divided concentrically into at least three sections on the upper surface of the coil holder and are located directly above the divided sections. At the same time, a lower cooling device is provided that individually cools the divided sections of the coil pedestal corresponding to the divided sections of the lower heater from the lower surface, and the upper heater, the lower heater, the upper cooling device, and the lower cooling device are provided. A control device is provided to control each of the devices for each of the divided sections to heat and cool the temperature of metal strip coils located directly below and directly above the divided sections to a predetermined heat pattern, and the side wall of the inner cover is provided with a heat insulating property. The inner cover is made of a material, and the ceiling part of the inner cover and the divided compartments in which the electric heater of the coil holder is provided are partitioned from each other by a heat insulating material.

<Function> In FIG. 1 showing an embodiment of the present invention, the heaters 10a, b, and C and the lower heater lla.

b, c are variable resistors 12a, b whose respective voltages are controlled by variable resistors 12a, b
.

c, d, e, r, each part A of the coil 1,
Heating is performed so that the measured temperature values of D, G, I, F, and C become a predetermined heat pattern.

At this time, the direction of heat input into the coil 1 from the upper electric heaters 10a, b, c and the lower electric heaters 10a, b, c, d is mainly the longitudinal direction in FIG. 1, that is, the width direction of the strip, and the heat transfer mode is For example, 0 can be considered as one-dimensional, and as a result, the internal points of the coil can be easily estimated with high accuracy.

The temperature at point E can be accurately estimated from the change in temperature at point F, making it easier to achieve a heat pattern during the heating period.

In addition, during the cooling period, the upper cooling fluid nozzle 14a
, b, c and a lower cooling fluid nozzle 15a.

The cooling fluid (e.g. air) supplied from b, c controls the temperature of the upper surfaces G, D, A of the coil and the lower surface I.

Depending on the temperature of F, C, valves 16a, b, c, d.

After the amount is gunned through e and r, it is supplied to the three parts of the ceiling part of the inner cover 8 and the three parts of the coil holder 7, cooling each part, and as a result, each part of the corresponding coil to cool down. Therefore, similarly to the heating period, each part of the coil 1 can be cooled uniformly and accurately according to a predetermined heat pattern.

<Example> An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of the heat treatment apparatus of the present invention, showing one half of the coil for simplicity. In Figure 1,
1 is a coil, 5 is a hearth, 7 is a coil pedestal, 8 is an inner cover, and 9 is an outer cover.

10a, b, and c are upper heaters divided into three concentric circles inside the ceiling of the inner cover 8;
A, b, and c are lower heaters divided into three concentric circles on the upper surface of the coil holder 7.

Further, the upper heaters 10a, b, c and the lower heaters Ila, b, c are connected to each part A, D of the coil I.

The respective voltages are applied to the variable resistors 12a, b, so that the measured temperature values of G, I, F, and C form a predetermined heat pattern.
The amount of heat generated, that is, the heat input to the coil can be adjusted by c, d, e, and f.

Reference numerals 13a, b, c, d, e, and f indicate power sources for the respective electric heaters, but these may be common to each electric heater.

The direction of heat input into the coil 1 from the upper electric heaters 10a, b, c and the lower electric heaters 10a, b, c, d is mainly in the longitudinal direction in FIG. 1, that is, in the width direction of the strip, and the heat transfer mode is as follows. As a result, it is possible to easily and accurately estimate the internal point of the coil.For example, the temperature at point E can be accurately estimated from the change in temperature at point F. It becomes easier to achieve the heat pattern during the period.

Next, 14a, b, and c are upper heaters 10a, b.

These are upper cooling fluid nozzles that individually cool the divided sections of the ceiling of the inner cover 8 corresponding to the divided sections C from the outside, and 15a, b, and c are lower heaters lla, b,
This is a lower cooling fluid nozzle that individually cools the divided sections of the coil holder 7 corresponding to the divided sections of c from the lower surface.

In the cooling period, the upper cooling fluid nozzle 14
a, b, c and lower cooling fluid nozzle 15a.

The cooling fluid (e.g. air) supplied from b, c increases the temperature of the upper surfaces G, D, A of the coil and the lower surface l.

Depending on the temperature of F, C, valves 16a, b, c, d.

After the amount is adjusted via e and f, it is supplied to the three parts of the ceiling part of the inner cover 8 and the three parts of the coil holder 7, cooling each part, and as a result, each part of the corresponding coil to cool down. Therefore, like the heating section, each section of the coil 1 can be cooled uniformly and accurately according to a predetermined heat pattern.

Although this embodiment shows a case in which the heating device and the cooling device are divided into three parts concentrically, if the number of divisions is increased depending on the size of the coil, etc., the temperature can be adjusted with good layer accuracy. Control is possible.

Next, specific examples of the present invention will be further described.

Figure 3 shows a plate thickness of 0.5 mm, a plate width of 1 ounces, an outer diameter of 1540 cm, and an inner diameter of 500 mm using the heat treatment apparatus of the present invention.
2 is a graph showing a temperature measurement chart at point A and point E when a steel strip coil of weight 12) is heated.

Figure 3 shows the same dimensions, using conventional heat treatment equipment.
Points A and E when heating a heavy steel strip coil
A point temperature measurement chart is shown as a comparative example.

From FIG. 3, it can be seen that in the case of the conventional device, it takes 43 hours to reach the target temperature, but in the case of the present invention, it takes only 32 hours, reducing the heating time by more than 20%.

In addition, in the case of the conventional device, point A is heated above the target temperature, but in the case of the present invention, this does not occur and the quality of the steel strip is not adversely affected. In the case of the invention, compared to the case of conventional equipment, points A and E
The temperature difference between points is reduced, and the accuracy is improved (heated evenly).

<Effects of the Invention> As explained above, with the heat treatment apparatus of the present invention, the entire coil can be uniformly heated and cooled in accordance with a predetermined pattern, and the quality of the product can be improved. In particular, the internal points of the coil (
For example, since the temperature at point E) can be estimated with high accuracy, it is only necessary to take the minimum metallurgically necessary time for the heat treatment process, making it possible to improve productivity.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the heat treatment apparatus of the present invention, showing the half side of a coil. FIG. 2 is a diagram for explaining heating and cooling conditions of the coil, with FIG. 2 (1) being a perspective view and FIG. 2 (2) being a sectional view. FIG. 3 is a graph showing a temperature measurement chart of bait strip coils using the heat treatment apparatus of the present invention together with a comparative example. FIG. 4 is an explanatory diagram of a conventional heat treatment apparatus. 7... Coil holder, 9... Outer cover 10a, b, c... Upper heater, 11a, b, c
...lower heater, 1,! a, b, c, d, e, r
- Variable resistor, 13a, b, c, d, e, #... Power supply, 14a, b, c... Upper cooling fluid nozzle, 15a
, b, c...lower cooling fluid nozzle, 16a b,
c, d, e, f - valves. 8...Inner cover

Claims (1)

[Claims] A metal strip coil is placed on a coil holder in a heat treatment furnace, covered with an inner cover, and heated and heated under a specified atmosphere.
In the heat treatment apparatus for cooling, an upper heating heater is provided inside the ceiling of the inner cover to individually heat metal strip coils that are divided into at least three or more sections concentrically and located directly below the divided sections, and the upper heating An upper cooling device is provided that individually cools the divided sections of the ceiling of the inner cover corresponding to the divided sections of the heater from the outside, and the upper surface of the coil holder is divided into at least three or more concentric circles, and the divided sections are a lower heater that individually heats the metal strip coils located directly above the lower heater, and a lower cooling device that individually cools the divided sections of the coil pedestal corresponding to the divided sections of the lower heater from the lower surface, and controlling each of the upper heater, the lower heater, the upper cooling device, and the lower cooling device for each divided section to set the temperature of the metal strip coils located directly below and directly above the divided section to a predetermined heat pattern. A heating/cooling control device is provided, the side wall of the inner cover is formed of a heat insulating material, and the ceiling portion of the inner cover and the divided compartments in which the electric heater of the coil holder are provided are partitioned from each other with a heat insulating material. A heat treatment device for metal strip coils.