JPH0892660A - Annealing method for metal strip coil and its annealing apparatus - Google Patents

Abstract

(57) [Summary] [Objective] A method of annealing a metal strip coil that can reduce the temperature gradient in the coil during annealing when annealing using an inner case and reduce the occurrence of ear elongation, and an annealing apparatus for the same. Offer. [Composition] When the metal strip coil is placed in the inner case in an up-end shape and annealed, a plurality of ring-shaped cavities divided in the radial direction of the coil are formed on the upper surface of the inner case and the inner case. At least one of a plurality of ring-shaped cavities that are divided in the vertical direction of the coil is provided on the side surface, and a predetermined ring-shaped cavity is filled with a heat insulating material or a heat transfer enhancing material according to the progress of annealing, Further, the filled heat insulating material or heat transfer promoting material is recovered, and the thermal conductivity of the predetermined portion of the inner case is changed independently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing method using an inner case of a metal strip coil such as a steel strip coil, and an annealing apparatus therefor.

[0002]

2. Description of the Related Art When a metal strip coil is placed in an inner case in an up-end shape and annealed, the coil is not uniformly heated and cooled, so that thermal stress is generated in the coil due to a temperature difference. Of the thermal stresses, the thermal stress in the radial direction of the coil generated between the plates is considered to be one of the causes of the shape defect of the plate during annealing.

[0003] In particular, the ear extension, which is a shape defect occurring from the middle winding to the outer winding of the coil during cooling in the annealing process, is a radial compressive stress generated between the middle winding and the outer winding of the coil during cooling. It is thought that the cause is the mutual relationship of the thermal expansion difference in the direction (plate width direction).

It is considered that the compressive stress in the radial direction is generated because the middle winding has a higher temperature during cooling than the outer winding of the coil and the middle winding tends to expand outward from the outer winding. The difference in thermal expansion in the coil height direction is due to the fact that the temperature distribution in the coil height direction is high and low in the coil height direction during cooling. Therefore, the ear extension defect can be reduced by reducing the compressive stress in the coil radial direction and the thermal expansion difference in the coil height direction. That is, it is considered that the ear extension can be reduced by making the temperature inside the coil uniform during cooling.

As a measure for reducing the temperature difference in the coil, there has been proposed a method of inserting a device for heating, cooling, and heat insulating into the inner diameter of the coil.

[0006]

However, since this method requires the step of inserting a device for heating, cooling and heat insulation, there is a problem that the operational load becomes large and there is a heat insulating material inside the coil inner diameter. Therefore, there is a problem that heat input from the inner diameter portion of the coil is hindered and heating failure of the coil occurs.

The present invention solves the above problems and provides a method for annealing a metal strip coil and an annealing apparatus for the same, which uses an inner case capable of reducing the temperature gradient in the coil during annealing. It is intended.

[0008]

According to the present invention, when a metal strip coil is placed in the inner case in an up-end shape and annealed, the plurality of metal strip coils are divided on the upper surface of the inner case in the radial direction of the coil. At least one of a ring-shaped cavity and a plurality of ring-shaped cavities divided in the vertical direction of the coil is provided on the side surface of the inner case, and a heat insulating material is provided in a predetermined ring-shaped cavity according to the progress of annealing. Alternatively, the metal band coil is characterized in that it is filled with a heat transfer enhancing material, and further, the filled heat insulating material or heat transfer enhancing material is recovered to independently change the thermal conductivity of predetermined portions of the inner case. The present invention is also an annealing method in which the metal strip coil is placed in the inner case as an up-end shape and the coil is mounted on the upper surface of the inner case. A plurality of ring-shaped cavities that are divided in the radial direction and at least one of the plurality of ring-shaped cavities that are divided in the vertical direction of the coil are provided on the side surface of the inner case, and An annealing device for a metal strip coil, comprising: a heat insulating material or heat transfer promoting material filling means and a filled heat insulating material or heat transfer promoting agent recovery means.

As the heat insulating material which can be advantageously used in the present invention, there are granular ceramics (mullite balls and the like), fibrous heat insulating materials (ceramic fibers such as Kao wool blanket (trade name)) and the like. Of course, you may mix and use these. Further, as the heat transfer accelerator that can be advantageously used in the present invention, metal particles having a melting point of 1000 ° C. or higher are typical, and there are metal particles such as stainless steel powder, copper powder, iron powder and steel powder. . Of course, you may mix and use these.

[0010]

FIG. 9 shows a general temperature distribution of the coil cross section during cooling when the steel strip coil 4 is annealed by using the conventional inner case 1 shown in FIG. The outer winding and the inner winding have a low temperature in the upper part of the coil, and the middle winding has a relatively high temperature. This is the cause of the radial stress from the middle winding to the outer winding.

The temperature is lower toward the top in the coil height direction.
This is the cause of the difference in thermal expansion in the coil height direction. By reducing these temperature gradients, ear extension defects can be reduced. In the present invention, a plurality of ring-shaped cavities that are divided into at least two in the radial direction of the coil can be provided on the upper surface of the inner case, and each ring-shaped cavity can be independently filled with a heat insulating material. In addition, the outer winding portion on the upper surface of the inner case is thermally insulated, the heat radiation from this portion is suppressed to reduce the temperature decrease, and the temperature difference from the inner winding is reduced, so that the radial stress can be reduced.

Further, according to the present invention, a plurality of ring-shaped cavities which are divided into at least two in the vertical direction of the coil can be provided on the side surface of the inner case, and each ring-shaped cavity can be independently filled with a heat insulating material. Therefore, during cooling, the upper part of the side surface of the inner case is insulated, the heat radiation from this part is suppressed to reduce the temperature drop, the temperature difference between the upper and lower sides can be reduced, and the thermal expansion difference can be reduced.

As a result, ear extension defects can be reduced. Further, at the time of heating or soaking, the heat insulating material can be removed or further the heat transfer promoting material can be filled, so that the heating of the coil is not hindered. Further, in the present invention, since the heat insulating operation can be performed in the inner case, the problem of operational load such as mounting a new device on the coil does not occur.

In the present invention, the ring-shaped cavity may be provided only on the upper surface of the inner case, only on the side surface, or on both the upper surface and the side surface, depending on the size, shape, material and the like of the metal strip coil.

[0015]

EXAMPLE FIG. 1 shows an example of an annealing apparatus using an inner case of a metal strip coil according to the present invention. 1A is a sectional view showing the left half thereof, FIG. 1B is a sectional view taken along the line AA of FIG. 1A, and FIG. 1C is a sectional view taken along the line BB of FIG. On the upper surface of the inner case 1, there are provided ring-shaped cavities 2 which are divided into three in the radial direction of the coil, and on the side surfaces, ring-shaped cavities 3 which are divided into three in the vertical direction are provided. Independent powder transport systems 5 and 6 are connected to these ring-shaped cavities, and valves 5a: are provided in predetermined ring-shaped cavities 2 and 3, respectively.
By operating 6a to 5f: 6f, the heat insulating material can be filled or recovered independently of the other ring-shaped cavities. Further, when heating, all the ring-shaped cavities 2 and 3 are emptied, or in a temperature range where convective heat transfer is dominant, the predetermined ring-shaped cavities 2 and 3 are filled with a heat transfer accelerator such as metal particles. It is also possible to secure an appropriate amount of heat transfer to the coil 4. At the time of cooling, in the case of the present embodiment, an outer wound ring-shaped cavity 2 on the upper surface of the inner case 1
-3, by filling the ring-shaped cavity 3-1 on the side surface with a heat insulating material, it is possible to reduce the ear extension defect as described in the section of the action.

FIG. 2 is an explanatory view showing an example of the operation of filling and recovering the heat insulating material in the ring-shaped cavities 2 and 3.
When filling the ring-shaped cavities 2 and 3 with the heat insulating material, first, the valves V1, 5V, 6V and V2 are opened and V3 is closed, and air or nitrogen gas is blown from Y to fill the inside of the tank 9. The heat insulating material is pumped into the ring-shaped cavities 2 and 3. 1
Reference numeral 0 is a filter, and blown gas is exhausted from C. Next, when recovering the heat insulating material, first, the valve V1,
5V, 6V and V3 are opened and V2 is kept closed. Air or nitrogen gas is blown from Z to insulate the heat insulating material in the ring-shaped cavities 2 and 3 to the tank 9. Reference numeral 11 denotes a filter, and the blown gas is exhausted from Y.

The quantitative effect of the embodiment will be described below. FIG. 7 is a cross-sectional view showing the left half of the annealing apparatus using the inner case of the present invention, in which the upper surface of the inner case 1 has a sectional height T1 of 3 divided in the radial direction of the coil.
A ring-shaped cavity 2-1 having a width of 0 mm and a width W1 of 120 mm,
2-2 and 2-3, and ring-shaped cavities 3-1, 3-2, and 3-3 having a sectional height T2 of 400 mm and a width W2 of 20 mm, which are vertically divided into three, are formed on the side surface. It is provided.
The inner case 1 has an inner diameter of 1700 mm, a thickness of 30 mm, a height of 2200 mm, and a material of SUS3.
Built in 10S. The coil 4 is mounted on the base plate 7 on the mounting table 8.

On the other hand, FIG. 8 is a sectional view showing the left half of an annealing apparatus using a conventional inner case. The inner case 1 has an inner diameter of 1700 mm and a height of 2200 m.
m, and the material is constructed of SUS310S. The coil 4 is mounted on the base plate 7 on the mounting table 8. The cold rolling steel strip coil 4 having a plate thickness of 0.2 mm, a plate width of 1000 mm and a weight of 10 t was directly raised to 1000 ° C. for 50 hr and then cooled to 300 ° C. for 50 hr using the annealing apparatuses shown in FIGS. In this case, when the annealing apparatus of FIG. 7 was used, all the ring-shaped cavities were filled with stainless steel particles by pneumatic transportation before the start of annealing.
Then, when the temperature reached 1000 ° C. in 50 hours, all the stainless particles were collected by air transportation, and immediately the top ring-shaped cavity 2-3 and the side ring-shaped cavity 3 of the inner case 1 were collected.
-1 was filled with mullite grains by pneumatic transportation.

FIG. 3A shows the temperature difference in the radial direction of the coil upper portion during cooling at that time, comparing the embodiment and the conventional example. FIG. 3B is a cross-sectional view of the left half of the coil, in which the temperature measurement points on the upper part of the coil are indicated by crosses. Measuring point X1
Is at a position H1 from the coil upper end in the radial direction L1 from the coil side end, and the measuring point X2 is at a distance H1 from the coil upper end in the radial direction L2 from the coil side end. And H1 is 50mm, L1 is 50mm, L2 is 450mm
And the radial thickness L3 of the coil is 900 mm.

Further, FIG. 4A shows the temperature difference in the coil height direction at the time of cooling in comparison between the embodiment and the conventional example. FIG. 4B is a cross-sectional view of the left half of the coil, in which the temperature measurement points inside the coil are indicated by crosses. Measurement point X3
Is at a distance H2 from the coil upper end in the radial direction L4 from the coil side end, and the measurement point X4 is at a distance H3 from the coil lower end in the radial direction L5 from the coil side end, and L
4, L5, H2, and H3 are each 50 mm, and the radial thickness L6 of the coil is 900 mm.

Further, FIG. 5 shows the ear depth corresponding to the length from the coil end after cooling in comparison between the embodiment and the conventional example. In addition, FIG. 6A shows a transition of the temperature of the cold point (CP) of the coil during heating, comparing the embodiment and the conventional example. 6B is a cross-sectional view of the left half of the coil, in which the temperature measurement points at the cold points (CP) of the coil are indicated by crosses. Measurement point C. P is located at a distance H4 from the lower end of the coil and at a position in the radial direction L7 from the inner end of the coil, and the thickness L8 in the radial direction of the coil is 900 mm.

From the comparison between the above-described embodiment and the conventional example, when the inner case of the present invention is used, the temperature difference in the radial direction of the coil upper part is reduced to about 1/2 from FIG.
From this, it is understood that the temperature difference in the height direction is also reduced to about 1/2, and as a result, the ear extension defect is reduced to 1/3 of that in the conventional case, as shown in FIG. At that time, as shown in FIG. 6, the temperature of the cold point of the coil at the time of heating is slightly lower than the conventional temperature,
There were no quality problems. In addition, since it only covers the inner case, there is almost no increase in operational load when inserting the coil.

[0023]

As described above, according to the present invention, it is possible to independently insulate a predetermined place on the inner case or to stop the heat insulation, and reduce the ear extension defect generated during cooling by about 70%. I was able to. Moreover, since the heat insulation can be stopped at the time of heating, the heat input to the coil is not hindered. Furthermore, since the ring-shaped cavity is provided integrally with the inner case, it is sufficient to cover the coil with the inner case as usual, without increasing the operational load.

[Brief description of drawings]

FIG. 1 is an annealing device 1 using an inner case of the present invention.
An example is shown, (a) is a sectional view showing the left half thereof, (b)
Is a sectional view taken along the line AA of (a), and (c) is a sectional view taken along the line BB of (a).

FIG. 2 is an explanatory diagram showing an example of a filling and collecting operation of a heat insulating material in a ring-shaped cavity.

FIG. 3 is a graph showing a temperature difference in a radial direction of a coil upper portion during cooling.

FIG. 4 is a graph showing a temperature difference in the coil height direction during cooling.

FIG. 5 is a graph showing the ear extension depth corresponding to the length from the coil end after cooling.

FIG. 6 is a graph showing the temperature transition of the cold point of the coil during heating.

FIG. 7 is a cross-sectional view showing the left half of the annealing apparatus using the inner case of the present invention.

FIG. 8 is a cross-sectional view showing the left half of an annealing device using a conventional inner case.

FIG. 9 is a left half cross-sectional view showing a temperature distribution of a general coil cross section during conventional coil annealing cooling.

[Explanation of symbols]

 1 Inner case 2 Cavity 3 Cavity 4 Coil 5 Powder transportation system 6 Powder transportation system 7 Base plate 8 Mounting table 9 Tank 10 Filter 11 Filter T1, T2 Cavity cross section height W1, W2 Cavity cross section width X1-X4 Coil Internal temperature measurement point C. P Coil cold point L1 to L8 Coil radial direction position H1 to H4 Coil height direction position

Claims (2)

[Claims] 1. A plurality of ring-shaped cavities which are divided in the radial direction of the coil on the upper surface of the inner case when the metal strip coil is mounted in the inner case as an up-end and annealed, and the inner case. At least one of a plurality of ring-shaped cavities that are divided in the vertical direction of the coil is provided on the side surface of the coil, and a predetermined ring-shaped cavity is filled with a heat insulating material or a heat transfer enhancing material according to the progress of annealing. A method for annealing a metal strip coil, further comprising recovering the filled heat insulating material or heat transfer enhancing material and independently changing the thermal conductivity of a predetermined portion of the inner case. 2. An annealing apparatus in which a metal strip coil is mounted in an inner case in an up-end shape, and a plurality of ring-shaped cavities divided in a radial direction of the coil are provided on an upper surface of the inner case, and At least one of a plurality of ring-shaped cavities that are divided in the vertical direction of the coil is provided on the side surface, and a heat insulating material or a heat insulating material filled in each ring-shaped cavity is filled with a heat insulating material or a heat transfer accelerator. An annealing device for a metal band coil, characterized in that it is provided with a means for collecting a heat transfer accelerator.