JPH01123032A - Method for finish-annealing grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To prevent the occurrence of lateral strain in the lower part of a coil of a grain-oriented silicon steel sheet when the coil is finish-annealed by interposing silica sand, etc., between the coil and a coil holder in the form of a layer of a specified thickness and carrying out finish annealing. CONSTITUTION:A coil 1 of a grain-oriented silicon steel sheet is coated with MgO, put on a coil holder 5 in an inner cover 4 with the coiling shaft upright and finish-annealed by heating from the outside of the cover 4. At this time, one or more 7 among silica sand, zircon sand and ceramic powder are interposed between the coil 1 and the coil holder 5 in the form of a layer 8 of 10-50mm thickness and finish annealing is carried out. The occurrence of lateral strain in the coil 1 is remarkably suppressed to increase the yield and commodity value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a box annealing method for a strip plate coil, and more particularly, to a method for preventing lateral strain from occurring at the coil side edge in contact with a coil holder. .

[Prior Art] A cold-rolled strip, such as a thin steel sheet, is coiled into a box in order to remove strain caused by cold rolling, remove impurities such as decarburization and denitrification, or adjust crystal grains. Annealed.

Box annealing of a band-shaped plate coil is performed by placing the coil in one or more stages in an annealing furnace with the winding direction of the coil being vertical.

In conventional annealing in a box annealing furnace, as shown in FIG. The roll is placed vertically on top of the inner cover 4, and is annealed by receiving heat from a furnace body installed outside the inner cover 4 in an atmospheric gas supplied from the bottom through an air supply pipe 6.

In the thin steel plate coil 1 box-annealed in this manner, buckling strain called lateral strain occurs at the lower end in contact with the coil pedestal 5.

This buckling strain is said to be due to the difference in expansion and contraction during the thermal cycle of heating, soaking, and cooling during annealing of the thin steel coil 1 and the coil pedestal 5.

The degree of occurrence of this buckling strain increases as the plate thickness decreases, and is particularly noticeable in thin steel plates of 0.35 mm or less.

Such buckling strain (lateral strain) occurring at the lower end of the thin steel coil reduces the commercial value and also has an adverse effect on the quality of the material, so it must be removed, resulting in a decrease in yield.

Preventing or reducing such lateral distortion is an extremely important issue, and various methods have been used in the past.

For example, in Japanese Patent Publication No. 52-13109, prior to box annealing, when winding a steel plate into a coil shape, the side edges are rolled up so as to form an uneven shape, and the protruding edges are used as coil holders. A method has been proposed in which the material is placed in contact with the material and annealed.

Furthermore, Japanese Utility Model Application No. 56-123860 discloses that a bottom plate made of the same material as the steel plate coil to be annealed is placed on the coil pedestal, and the steel plate coil is placed on top of the bottom plate to prevent the generation of distortion at the lower end of the steel plate coil. 11- It's completely amazing.

Although these efforts have attempted to reduce distortion to a certain extent, the reality is that it cannot be said that this has been achieved to a sufficient degree. In particular, grain-oriented silicon steel coils that are finish annealed at high temperatures of 1000° C. or higher for long periods of time often experience distortion, and it is necessary to reduce this.

[Problems to be Solved by the Invention] The present invention provides a method for finish annealing a grain-oriented silicon steel sheet that can suppress the occurrence of distortion due to thermal distortion, etc. due to the difference in thermal expansion and contraction between the coil pedestal and the lower end of the coil in contact therewith. U to provide
target

[Means for Solving the Problems] The gist of the present invention is that the grain-oriented silicon steel coil after decarburization annealing is
After applying O, the strip plate coil is placed on the coil holder inside the inner cover with the winding axis h' perpendicular to the finish annealing h.
In this method, one or more of silica sand, zircon sand, and ceramic powder is placed between the coil and the coil pedestal.
A method for finish annealing a grain-oriented silicon steel sheet, which comprises laying and annealing the sheet to a thickness of 0 to 50 mm.

EMBODIMENT OF THE INVENTION Below, this invention is demonstrated in detail based on one Example with reference to drawings.

The grain-oriented silicon steel coil 1 coated with MgO is subjected to finish annealing with the coil axis placed perpendicularly to the coil holder 5. During this final annealing, silica sand 7, zircon sand,
Alternatively, one or more types of ceramic powder are laid down.

The laid material does not sinter even at high temperatures of, for example, 1100° C. or higher, and has the effect of imparting good sliding properties to the grain-oriented silicon steel coil 1 facing the coil pedestal 5.

In addition, in order to prevent strain from occurring at the lower end of the grain-oriented silicon steel coil 1, the thickness of the installation is important;
0m+s or less.

The lower limit is set to IOm+s in order to prevent the occurrence of buckling strain, thermal strain, etc. that conventionally occurs at the lower end of the grain-oriented silicon steel coil 1, and to ensure slipperiness. be.

On the other hand, if the thickness of the installation becomes thick, the heat input from the coil pedestal 5 will be suppressed, and the lower end of the grain-oriented silicon steel coil will delay the heat rise, which will have a negative effect on the temperature distribution, so the thickness is set to 501 or less.

In order to make the laying thickness of the material 10 to 50 mm, it is preferable to provide a saucer or enclosure 8 made of steel, ceramic, refractory material, etc. in order to improve workability or to stably obtain a predetermined thickness.

Thus, the directional silicon coil 1 is subjected to final annealing through one thermal cycle. During annealing, the coil 1 and the coil pedestal 5 thermally expand and contract according to temperature changes during the annealing process, but since they are interposed with silica sand, zircon sand, and ceramic powder at lo to 5 o, the coil pedestal 5
The lower end portion 1-1 of the coil in contact with the coil holder 5 can move freely without being pulled by the coil holder 5, and no distortion occurs.

In addition, as ceramic powder, S L C, S t a N
A material that does not harm grade 4 grain-oriented silicon steel is suitable, and its shape is preferably spherical.

By the above annealing method, a grain-oriented silicon steel plate having a good shape without buckling the lower end of the coil can be obtained.

[Example] A grain-oriented silicon steel sheet was cold-rolled to a final thickness of 0.3 in order of 0.3 and decarburized and annealed by a known method, and water was added to an annealing separator mainly composed of MgO to form a slurry. The coating was applied using a roll coater or the like, heated in a drying oven until the steel plate temperature reached 150°C to remove moisture, and then wound into a coil.

Next, the coil was placed on the coil holder in a steel dish on which 30 mm of white silica sand had been laid in advance so that the axis of the coil was perpendicular to the coil holder, and the coil was placed in a box at a temperature of 1100°C. Annealed.

On the other hand, as a comparative example, a similar grain-oriented silicon steel coil was placed directly on a coil stand and subjected to box annealing under the same conditions.

After annealing, the length of the side strain that occurred at the lower end of the coil in the sheet width direction was investigated.

The results are shown in Table 1.

Table 1 We also measured the length of the force isotropic silicon steel strip where lateral strain occurred, whereas in the method of the present invention, the length was 50 m for the outer coil winding.
The comparative method was 5(1(lm) on the outer coil side.

[Effects of the Invention] According to the present invention, as described above, the occurrence of side strain is significantly reduced, and there are effects such as an improvement in yield and an improvement in the product fdli value.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of conventional box annealing. 5: Coil pedestal 7: Silica sand 8: Enclosure

Claims (1)

[Claims] In a finish annealing method for a grain-oriented silicon steel sheet, in which a grain-oriented silicon coil is coated with MgO, the coil is placed on a coil cradle in an inner cover with the coil winding axis perpendicular, and then annealed. A method for finish annealing a grain-oriented silicon steel sheet, characterized in that one or more selected from silica sand, zircon sand, and ceramic powder is laid down to a thickness of 10 to 50 mm during the annealing process.