JP3941209B2 - Steel strip coil support device for annealing furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel strip coil support device for an annealing furnace, and more specifically, at the time of heat treatment of a so-called steel strip coil (hereinafter referred to as a coil) in which a steel strip such as a cold rolled steel plate or an electromagnetic steel plate is wound in a coil shape. The present invention relates to a technique for reducing ear distortion generated at the lower end of an outer winding side of a coil.
[0002]
[Prior art]
The steel strip wound up in a coil shape after the end of rolling is usually annealed discontinuously (hereinafter referred to as a batch type). Therefore, the annealing furnace currently most popular is as shown in FIG. First, a support metal piece 4 is arranged on a floor 6 (hereinafter referred to as a hearth) in a furnace formed of refractory bricks 13, and a steel base plate 3 and a spacer 2 are sequentially stacked, and then a coil is formed thereon. 1 is placed and the whole is surrounded by a cover called an inner cover 5. The coil 1 is heated by a heater 7 disposed on the hearth 6 or a burner 8 provided on the furnace wall. Note that the support metal hardware 4 to the base plate 3 and the spacer 2 are generally called a steel strip coil support device (hereinafter referred to as a support device).
[0003]
By the way, when the coil 1 is heated in the batch annealing furnace 12 in which the members of the support device are arranged as described above, the upper surface of the base plate 3 in contact with the coil 1 which is a large heat absorption source, the furnace With the lower surface of the base plate 3 heated almost directly by the heater 7 of the floor 6, the temperature of the lower surface increases faster. For this reason, the upper surface of the base plate 3 has a smaller amount of thermal expansion than the lower surface, and the base plate 3 slides upward (the upper surface becomes concave). At that time, since the coil 1 supports its own weight only at the outer periphery (outer winding side) portion, the lower end of the coil 1 does not contact the base plate 3 uniformly. Therefore, the part in contact, mainly the lower end on the outer peripheral side, is buckled as shown in FIG. 4 to cause a quality defect called so-called ear distortion 11. A typical state of occurrence of ear distortion 11 observed when the coil 1 is rewound is shown in FIGS.
[0004]
On the other hand, in order to prevent the ear distortion 11 caused by the upper plate of the base plate 3, many studies have been made so far. For example, in Japanese Patent Application Laid-Open No. 6-179926, a spacer having a smaller diameter than the spacer 3 is separately provided between the base plate 3 and the spacer 2 so that the warp of the base plate 3 directly acts on the outer periphery of the coil 1. We are proposing a technology that does not give Japanese Patent Application Laid-Open No. 7-48629 discloses that the base plate 3 is divided into concentric circles, and the concentric circle portion on the outer peripheral side thereof is movable up and down so that distortion caused by the warp of the base plate 3 is generated. It proposes technology to prevent. Japanese Utility Model Laid-Open No. 5-62564 discloses a technique for laying a rug having a hard central portion and a soft outer peripheral portion between the base plate 3 and the spacer 2, and Japanese Patent Laid-Open No. 58-61231 discloses As one of the unsuccessful prior arts, a technique for providing a downward taper on the upper surface of the base plate 3 is introduced.
[0005]
[Problems to be solved by the invention]
However, in the technique of “laying a small-diameter spacer between the base plate 3 and the spacer 2” described in Japanese Patent Laid-Open No. 6-179926, the upper spacer cannot support the weight of the coil 1 as the temperature rises. It was not practical from the viewpoint of the life of the spacer. Further, in the technique of “dividing the base plate 3 concentrically” described in Japanese Patent Application Laid-Open No. 7-48629, a large amount of investment is required for the driving device for the divided base plate 3, and the sealing performance of the driving part is also required. As a result, there has been no practical use. Further, the inventor actually tried the technique described in Japanese Utility Model Laid-Open No. 5-62564. However, the outer peripheral portion of the spacer 2 deforms without supporting the weight of the outer peripheral portion of the coil 1 at the highest annealing temperature. A step is formed between the hard rug 14 and the soft rug 15 and the weight of the coil 1 is substantially supported only on the hard rug 14. There was a problem (see FIGS. 7A and 7B).
[0006]
In view of such circumstances, an object of the present invention is to provide a steel strip coil support device for an annealing furnace that can suppress the occurrence of ear distortions conventionally.
[0007]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventor diligently studied focusing on the inclination from the center of the base plate toward the outer periphery, and completed the result as the present invention.
That is, according to the present invention, a heater is installed on the hearth, and a support metal, a base plate, a buffer member, and a spacer are sequentially stacked, and a steel strip wound in a coil shape is formed on an up-end shape. In the steel strip coil support device of the annealing furnace that heats and cools the coiled steel strip, the upper surface of the base plate is inclined downward from the center toward the outer periphery, The gradient is 1/20 to 1/100, and the (0.6 to 0.8) × outer diameter portion on the center side is a curved surface having a radius of curvature of 300 to 1000 mm that smoothly connects to the gradient on the outer peripheral side. It is a steel strip coil support apparatus of the annealing furnace characterized by these.
[0008]
Further, the present invention is the steel strip coil support device for an annealing furnace, wherein the buffer member is made of a soft material having a Young's modulus at a maximum annealing temperature of 1000 kg / mm ² or less.
According to the present invention, even when the base plate is warped, the warp does not affect the coil. Even if the spacer is warped downward at the highest temperature during annealing, the base plate does not have a steep step, so that the spacer hangs gently and local support of the coil does not occur. As a result, the ear distortion generated at the lower end on the outer periphery side of the coil is remarkably reduced as compared with the prior art.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described, including the background to the invention.
First, as shown in FIG. 2, the inventor reduces the thickness of the base plate 3 where the warpage is severe from the center side, and places a soft kao wool plate 9 at a high temperature and heats the portion. The spacer 2 and the coil 1 are not pushed up even if the base plate 3 warps inside. However, since the base plate 3 having this structure is suddenly thinned, that is, stepped on the center side, if the spacer 2 hangs down during heating, the weight of the coil 1 is concentrated on the stepped portion 10. (Stress concentration). As a result, when the coil 1 after annealing is subsequently flattened and wound into a coil shape, the coil 1 becomes a so-called stepped coil 1 (a state in which the coil edge is raised and wound), resulting in a product. The problem of not becoming frequent occurred.
[0010]
In view of this, the inventor provided an appropriate downward gradient (downward taper) with reference to the base plate described in Japanese Patent Laid-Open No. 58-61231 in order to eliminate the stepped portion 10 and to distribute the stress. I tried the base plate 3. However, it is not sufficient to apply an appropriate downward gradient, and the ear distortion 11 cannot be eliminated. For this reason, the inventor has intensively studied the shape of the downward gradient, and completed the shape of the base plate 3 suitable for suppressing the ear distortion 11 of the coil 1.
[0011]
That is, the upper surface of the base plate 3 is inclined downward from the center toward the outer periphery, and as shown in FIG. 1, the outer peripheral side gradient is 1/20 to 1/100, and the center side (0. The portion of 6 to 0.8) × outer diameter is a curved surface having a radius of curvature of 300 to 1000 mm smoothly connected to the gradient on the outer peripheral side.
Here, the reason why the gradient on the outer peripheral side is set to 1/20 to 1/100 is that stress concentration cannot be relaxed if it is less than 1/20, and if it exceeds 1/100, there is no effect of downward gradient. In addition, the (0.6 to 0.8) × outer diameter portion on the center side is a curved surface having a radius of curvature of 300 to 1000 mm smoothly connected to the gradient on the outer peripheral side. This is because stress concentration may occur due to the level difference, and if it exceeds 1000 mm, there is a problem that processing becomes difficult.
[0012]
Furthermore, in the present invention, the buffer member 9 placed between the base plate 3 and the spacer 2 is made of a soft material having a Young's modulus at the maximum annealing temperature of 1000 kg / mm ² or less, such as kao wool, The effect could be further promoted. In this case, when the Young's modulus exceeds 1000, the function as the buffer member 9 is remarkably lowered. Therefore, in the present invention, 1000 or less is preferable.
[0013]
【Example】
A cold-rolled steel sheet of steel type directional silicon steel was wound around a coil 1 having an outer diameter of 1500 mm and subjected to batch annealing. As for the annealing conditions, the atmosphere is a hydrogen and nitrogen gas atmosphere, the maximum annealing temperature is 1200 ° C., and the annealing time is 10 hours.
There are two types of coil support devices, one according to the present invention (see FIG. 1) and the conventional one used for effect comparison. Incidentally, according to the present invention, the upper surface of the base plate 3 is inclined downward from the center toward the outer periphery, and the outer peripheral gradient is set to 1/40, so that the center side (0.6-0. 8) The outer diameter portion was a curved surface with a radius of curvature of 500 mm that smoothly connected to the gradient on the outer peripheral side. The buffer member 9 was a soft cocoon wool plate having a thickness of 15 mm. On the other hand, the conventional one has a flat upper surface of the base plate 3 and does not use a buffer member.
[0014]
The results of these annealing are shown in FIG. 8 as the distribution of the depth of the ear distortion 11 generated in the longitudinal direction of the coil 1. From FIG. 8, it is clear that when the coil support device according to the present invention is used, a product having a good shape over the entire length of the coil 1 can be obtained as compared with the case of using the conventional one.
[0015]
【The invention's effect】
As described above, according to the present invention, a good cold-rolled steel strip having a shape with little ear distortion can be obtained.
[Brief description of the drawings]
FIG. 1 is a view showing a steel strip coil support device according to the present invention.
FIG. 2 is a view showing a base plate having a stepped upper surface.
FIG. 3 is a longitudinal sectional view showing the entire batch annealing furnace.
FIG. 4 is a diagram showing a relationship between a coil and a base plate.
FIG. 5 is another diagram showing a state of occurrence of ear distortion.
FIG. 6 is a diagram showing the magnitude of ear distortion.
7A and 7B are diagrams showing a situation when the technique described in Japanese Utility Model Laid-Open No. 5-62564 is implemented, in which FIG. 7A shows a coil support situation, and FIG. 7B shows a magnitude of ear distortion.
FIG. 8 is a diagram showing an implementation result of the support device according to the present invention.
[Explanation of symbols]
1 Coil (steel strip coil)
2 Spacer 3 Base plate 4 Support hardware 5 Inner cover 6 Hearth 7 Heater 8 Burner 9 Buffer member (Kao wool plate)
10 Stepped part 11 Ear distortion 12 Batch annealing furnace 13 Refractory brick 14 Hard rug 15 Soft rug

Claims (2)

A heater is installed on the hearth, and a support metal, a base plate, a buffer member, and a spacer are sequentially stacked, and a steel strip wound in a coil shape is placed on the up-end shape, In the steel strip coil support device of an annealing furnace for heating and cooling the coiled steel strip,
The upper surface of the base plate has a downward gradient from the center toward the outer periphery, and the outer peripheral side gradient is 1/20 to 1/100, with the center side (0.6 to 0.8) × outer diameter The part is a curved surface having a radius of curvature of 300 to 1000 mm smoothly connected to the gradient on the outer peripheral side. ^2. The steel strip coil support device for an annealing furnace according to claim 1, wherein the buffer member is made of a soft material having a Young's modulus at a maximum annealing temperature of 1000 kg / mm ² or less.

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