JP2003082414A - Equipment and method for continuous heat treatment of cold-rolled plate of non-oriented silicon steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line and a method for stably performing the continuous heat treatment of a strip of a non-oriented silicon steel subjected to various kinds of cold rolling with excellent quality. SOLUTION: In the continuous heat treatment line of the cold rolled sheet of the non-oriented silicon steel, a cold rolling mill for performing the cold rolling or the skin-pass rolling of the annealed strip passed through a furnace part is added to the annealing line comprising the furnace part for annealing the cold-rolled strip. Various kinds of non-oriented silicon steel sheets are manufactured by one set of cold-rolled sheet heat treatment line with high productivity and high quality.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to various non-oriented silicon steels, so-called full-process low-medium grade non-oriented silicon steel sheets, full-process high-grade non-oriented silicon steel sheets, and semi-process non-oriented silicon steel sheets. The present invention relates to a continuous heat treatment equipment and a continuous heat treatment method which can be manufactured by one set of heat treatment equipment for cold rolled sheets.

[0002]

2. Description of the Related Art There are various product types of anisotropic individual silicon steel sheets, and the main ones are (1) medium-lower full-process non-oriented silicon steel sheets (Si <1.8% by weight), (2) ) High grade full process non-oriented silicon steel sheet (Si ≧ 1.8 by weight%)
%), (3) Semi-processed non-oriented silicon steel sheet.

Although these products are conventionally manufactured by different processes (lines), the latest manufacturing processes are described below for each of them. The product (1) is manufactured by the following simplest process. Steelmaking-Continuous casting-Hot rolling-Continuous pickling-Tandem cold rolling-Cold rolled sheet annealing-Insulating film coating ... Although it contains Si, Al, etc., the α-γ transformation disappears, and due to this, ridging occurs in the continuous casting method. As a means for avoiding this, electromagnetic stirring immediately below the mold is required during continuous casting. Further, since a large amount of components such as Si and Al are contained and the magnetic flux density is reduced, hot-rolled sheet annealing is necessary as a means for avoiding this. As a result, the manufacturing process is as follows. Steelmaking-Continuous casting (with electromagnetic stirring) -Hot rolling-Continuous hot-rolled sheet annealing / pickling-Tandem cold rolling-Cold-rolled sheet annealing-Insulation coating ... Process II-1 It is also manufactured by the so-called double cold rolling method, which is the process of. Steelmaking-Continuous casting-Hot rolling-Continuous pickling-Tandem intermediate cold rolling-Intermediate cold rolled sheet annealing-Reverse mill finishing cold rolling-
Cold Rolled Sheet Annealing-Insulating Film Coating ... Process II-
2 Normally, the reverse mill finish cold rolling is a 2-pass finish using a monoblock type 20-high rolling mill with a work roll having a small diameter. The product of (3) is annealed after being processed into a final product, but from the viewpoint of improving iron loss (grain growth) after annealing, after cold rolling,
It is necessary to carry out skin pass rolling with a rolling reduction of 5 to 15%. As a result, the manufacturing process is as follows. Steelmaking-Continuous casting-Hot rolling-Continuous pickling-Tandem cold rolling-Cold rolled sheet annealing-Skin pass rolling-Insulation coating ...
・ ・ ・ Process III Normally, in skin pass rolling, the work roll has a large diameter of 4
A Hi rolling mill is used. In addition, a pickling / cold rolling direct connection line in which continuous pickling and tandem cold rolling are combined may be used.

[0004]

There are several drawbacks to these approaches. That is, in order to manufacture various non-oriented silicon steel sheets, many kinds of equipment are required and a reverse mill cold rolling mill is required, which significantly lengthens the manufacturing process and impairs productivity. As described above, manufacturing various types of non-oriented silicon steel sheets requires a large number of facilities and a long manufacturing period, and in reality, it is difficult to manufacture various products ideally. There was no choice but to substitute a substitute.

The present invention provides a cold rolling process capable of both cold rolling under large pressure and skin pass rolling with a single cold rolling mill downstream of the conventional annealing process for cold rolled sheets. To provide continuous heat treatment equipment and method for cold-rolled sheet, which manufactures non-oriented silicon steel sheet of the above with minimum equipment and ideal process, and has high quality, high productivity and short production period With the goal.

[0006]

Means for Solving the Problems The gist of the present invention is as follows: (1) In a continuous heat treatment equipment for cold-rolled sheets of non-oriented silicon steel, a pay-off reel for unwinding a cold-rolled coil, and a cold-off reel. Furnace part for annealing the rolled strip, cold-rolled annealed strip exiting the furnace part, or, skin pass rolling, a rolling part performing the same rolling mill, the annealed, or And an insulating film coating portion for applying and baking an insulating film to the strip that has been skin-pass-rolled after annealing, and a tension reel for re-winding the coil coated with the insulating film. Continuous heat treatment equipment for cold-rolled oriented steel sheets. (2) In the continuous heat treatment equipment for cold-rolled non-oriented silicon steel according to (1), the rolling mill is selected from the class consisting of a split-type 20-high rolling mill or a 12-high rolling mill. Characteristic continuous heat treatment equipment for cold-rolled sheets of non-oriented silicon steel. (3) In the continuous heat treatment equipment for cold rolled sheet of non-oriented silicon steel according to (1) or (2), an equipment for applying rolling oil to the surface of the strip is arranged upstream of the rolling mill. Continuous heat treatment equipment for cold-rolled sheets of non-oriented silicon steel, characterized in that (4) In the continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel, a step of unwinding a cold-rolled coil in one continuous processing line, and annealing the cold-rolled strip. And a step of cold rolling the annealed strip, or a cold rolling step for performing skin pass rolling in the same rolling mill, and the annealed, or after annealing, skin pass rolled, to the strip A continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel, comprising: a step of applying and baking an insulating film; and a step of rewinding a coil coated with the insulating film. (5) In the continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel according to (4) above, the cold rolling step comprises a split mold 20.
A continuous heat treatment method for cold-rolled strips of non-oriented silicon steel, which comprises rolling with a multi-stage rolling mill or a 12-high rolling mill. (6) In the continuous heat treatment method for cold-rolled non-oriented silicon steel sheet according to (4) or (5), rolling oil is applied to the surface of the strip upstream of the cold rolling step in the line. A continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel, comprising a step of applying. (7) In the continuous heat treatment method for cold-rolled non-oriented silicon steel sheet according to any one of (4) to (6), α-γ
A continuous heat treatment method for a cold-rolled strip of non-oriented silicon steel, which comprises passing a cold-rolled strip of non-oriented silicon steel twice in a composition system having no transformation. Is.

[0007]

1 is a semi-schematic isometric view of a typical prior art continuous heat treatment facility for annealing and insulating coating a cold rolled sheet of non-oriented silicon steel. It should be understood that such lines are actually much more complicated than shown. For example, furnace section 12 generally comprises a heating zone, a soaking zone, and a cooling zone. The insulating film coating device 16 is composed of a coater, a coating liquid circulating device, a coating liquid producing device, and the like, and the insulating film baking device 17 also has a heating region, a soaking region, and a cooling region.

The main elements of such a line are to load a coil of cold-rolled non-oriented silicon steel, payoff reel 1 for unwinding from it, and to cut the end of the coil. Input shear 2 to prepare for welding
Welder 3 for continuously joining the ends of the coil, welding preparation for the coil, and inlet side cleaning device 11 / furnace part 1 during welding
2. Inlet side storage looper 4 that stores strips that enable stripping without slowing down or stopping the outlet side cleaning device 15, insulating film coating device 16 and insulating film baking device 17, the surface of the strips, and rolling oil An inlet side cleaning device 11 for removing dirt such as iron and iron, a furnace part 12 including heating, soaking and cooling regions used for annealing the strip, and an annealed strip surface discharged from the furnace part , The outlet side cleaning device 15 for removing the dirt in the furnace, the insulating film coating device 16, the insulating film baking device 17, and the coil is turned on when the outlet shearing machine 8 is operating when the rewinding of the coil is completed. Side cleaning device 11, furnace part 12, outlet cleaning device 15, insulating film coating device 16, insulating film baking device 17
It comprises an outlet storage looper 7 for storing strips that can be passed through without decelerating and stopping, an outlet shearing machine 8, and a tension reel 9 for rewinding a coil.

The tension of the strip 60 before and after the furnace portion 12 is measured by the tension meters 41 and 42, and the tension of the strip 60 in the insulating film baking device 17 is measured by the tension meter 44 and passes through the bridle roll 21.
a, 21b, 22a, 22b, 23a, 23b, 24
a, 24b, 28a, 28b, 29a, 29b, 30
The strip tension before and after the bridle is secured by being fed back to a and 30b.

FIG. 2 is a quasi-schematic isometric view of a continuous heat treatment equipment for annealing / insulating coating of a cold rolled sheet of non-oriented silicon steel, which is one embodiment of the present invention. Top 2
Although separated into stages, they are actually continuous lines. Compared to the conventional line of FIG. 1, at a position between the bridle rolls 24a and 24b downstream of the furnace section 12 in the line and the outlet side cleaning device 15, the central storage looper 5, the tension meter 43, and rolling oil on the strip surface are provided. Pre-coating device 13 for applying the, cold rolling mill 14, tension meter combined shape meter 51, central storage looper 6, and bridle rolls 25a, 25b, 25
c, 25d, 26a, 26a, 26b, 26c, 26
The difference is that d, 27a, and 27b are installed.

At a position between the entry-side storage looper 4 and the central sledge looper 5, the strip 60 is heat-treated without stopping the line even when the entry-side welding machine 3 is operating, and The work rolls and the like of the cold rolling mill 14 are replaced when the rolls are worn or scratched, and at this time, the heat treatment can be performed without stopping the line or decelerating. Similarly, at a position between the central sledge looper 6 and the outlet storage looper 7, the strip 60 is applied with an insulating film and baked without stopping even when the outlet shear 8 is operating. Further, even when the work rolls of the cold rolling mill 14 are replaced, the insulating film is applied and baked without stopping the line or decelerating. Further, in the position between the central storage looper 5 and the central storage looper 6, the strip 60 is continuous both when the inlet welding machine 3 is operating and when the outlet shearing machine 8 is operating. Therefore, cold rolling is possible.

The tension meters 43 and 51 are installed before and after the cold rolling mill 14 to control the tension of the strip 60 before and after the cold rolling mill 14. Also, the shape meter 51
Is installed downstream of the cold rolling mill 14 and is used to control the strip shape of the cold rolling mill 14. Further, the other parts of the line shown in FIG. 2 are similar to the line of FIG. 1, and the same parts or devices are designated by the same reference numerals.

The conditions for the cold rolling mill 14 are: (i) It is possible to reduce the plate thickness of the annealed plate by 40 to 60% in the double cold rolling method of high-grade full-process silicon steel plate,
(Ii) In the semi-processed material, the annealed plate can have a good shape and can be skin-pass-rolled to reduce the plate thickness by 5 to 15%. (Iii) The plate thickness fluctuation value after cold rolling is small. iv) Rolls should be easy to replace.

In order to efficiently satisfy (i), the work roll diameter of the rolling mill is preferably in the range of 60 to 120 mm. If the work roll diameter is less than 60 mm, wear of the work roll of the rolling mill occurs in a short time, and the work roll is replaced every several coils, which is not realistic. On the other hand, if the work roll diameter exceeds 150 mm, the capacity of the rolling mill becomes large and it is difficult to obtain a high pressure reduction ratio, and it becomes difficult to roll with one cold rolling mill, which is inefficient. To efficiently satisfy (ii), the work roll diameter of the rolling mill is preferably 90 mm or more. If the work roll diameter is less than 90 mm, the cold-rolled shape becomes unstable because it is easily affected by the offset of the upper and lower work rolls. The most effective way to improve (iii) is a cold rolling mill with high mill rigidity. Desirably, the mill rigidity is 300 tons / mm or more. This is because if it is less than 300 ton / mm, it is not possible to eliminate the variation in the thickness of the original plate, for example, the influence of the skid mark of hot rolling, and it becomes impossible to make the plate thickness uniform over the entire length of the coil. As a cold rolling mill satisfying (iv), a split type cold rolling mill in which at least one of the upper housing and the lower housing is large and which can be moved in the vertical direction when the work roll is replaced is effective.

From the above, the cold rolling mill 14 is
A split type 20-high rolling mill or 12-high rolling mill having a wide range of work roll diameters and high mill rigidity is desirable. Further, in order to enable the number of cold rolling mills 14 to be one, in the double cold rolling method, in order to improve the lubricity during cold rolling, upstream of the cold rolling mill 14 is It is desirable to install a precoat device 13 for applying rolling oil to the strip surface. The rolling oil used in the precoating device 13 desirably has higher lubricity than the rolling oil of the cold rolling mill 14, and the rolling oil having a high oil content is
Particularly preferred. In addition, a work roll diameter of 60 to 150 is used to manufacture a non-oriented silicon steel sheet having a plate thickness of 0.20 to 0.70 mm.
A split type 20-high cold rolling mill of mm is preferable.

By using the continuous heat treatment equipment for cold-rolled non-oriented silicon steel sheet according to the present invention, the various non-oriented silicon steel sheets described above can be used as follows without electromagnetic stirrer in continuous casting equipment. Can be manufactured. The items enclosed in [] are the continuous heat treatment equipment for non-oriented silicon steel sheets according to the present invention. (1) Medium-Low Full Process Non-oriented Silicon Steel Sheet (Si <1.8% in wt%) Steelmaking-Continuous casting-Hot rolling-Continuous pickling-Tandem cold rolling- [Cold rolled sheet annealing-Insulating coating ] ...
Process I (2) High-class full-process non-oriented silicon steel sheet (S by weight%
Steelmaking-continuous casting-hot rolling-continuous pickling-tandem intermediate cold rolling- [intermediate cold rolled sheet annealing-intermediate cold rolling]-[cold rolled sheet annealing-insulating coating]- --- Process II-2 (3) Semi-process non-oriented silicon steel sheet steel-continuous casting-hot rolling-continuous pickling-tandem cold rolling- [cold rolled sheet annealing-skin pass rolling-insulating film coating ] ・
.... Process III

As described above, the number of manufacturing steps and the number of lines of various non-oriented silicon steel sheets are as follows: (1) Medium / Lower full process non-oriented silicon steel sheet 3 steps / 3 lines → 3 steps / 3 lines (2) High-grade full-process non-oriented silicon steel sheet 3 steps / 3 lines or 5 steps / 4 lines → 4 steps
3 lines (3) Semi-process non-oriented silicon steel plate 5 steps ・ 4 lines → 3 steps ・ 3 lines To produce all the above products, 5 or 6 lines → 3 lines, especially continuous heat treatment equipment is 1 line At the same time, it became possible to eliminate cold rolling of batch rolling by a reverse mill. in this way,
With the single set of continuous heat treatment equipment for cold-rolled sheets according to the present invention, various non-oriented silicon steel sheets can be manufactured with high quality and efficiency.

[0018]

EXAMPLES [Example 1] (1-1) Production mass% of low-intermediate grade full process non-oriented silicon steel sheet: C: 0.002%, Si: 1.65%, M
n: 0.40%, P: 0.020%, S: 0.0025
%, Al: 0.160%, and N: 0.0020%
The non-oriented silicon steel containing slab was heated at a low temperature of 1150 ° C. to obtain a hot rolled coil having a plate thickness of 2.3 mm.

This hot-rolled coil was tandem cold-rolled to a plate thickness of 0.50 mm and then treated in the continuous heat-treatment equipment for cold-rolled sheets according to the present invention shown in FIG. After annealing at 950 ° C., the product was passed through a cold rolling mill without any use, a semi-organic insulating film was applied to the strip surface, baked, and rewound with a tension reel to obtain a final product.
The product quality was the same as that produced by conventional equipment.

(1-2) Production mass% of high-grade full-process non-oriented silicon steel sheet: C: 0.002%, Si: 3.05%, M
n: 0.20%, P: 0.015% S: 0.0018
%, Al: 0.560%, and N: 0.0015%
The non-oriented silicon steel containing slab was heated at a low temperature of 1150 ° C. to obtain a hot rolled coil having a plate thickness of 1.8 mm.

This hot-rolled coil was tandem cold-rolled to a plate thickness of 0.70 mm, and then subjected to the first treatment in the continuous annealing equipment for cold-rolled sheets according to the present invention shown in FIG. 100
After annealing at 0 ℃, high-concentration rolling oil (oil content 30%) is pre-coated, and the work roll diameter is 65mm.
With a table (rolling oil / oil content 10%), the plate thickness is reduced to 0.35 mm (plate thickness reduction rate 50%), passed through the insulating film coating device / baking device without being used, and rewound on the tension reel. Did. The mill rigidity was 320 tons / mm.

After that, the second treatment was performed again in the continuous treatment equipment for cold-rolled sheets according to the present invention shown in FIG. 1050 ° C
After being annealed, it was passed through a cold rolling mill without any use, a semi-organic insulating film was applied to the surface of the strip, baked, and rewound with a tension reel to obtain the final product. Product quality has no ridging and magnetic characteristics are
The maximum properties were the same, but the average properties were improved, as compared with the case where the finish rolling was performed in two passes with a reverse mill.
In addition, the amount of off-gauge became small and the number of manufacturing days after hot rolling was halved.

(1-3) Production of semi-processed non-oriented silicon steel sheet: C: 0.002%, Si: 1.05%, M
n: 0.50%, P: 0.150%, S: 0.0050
%, Al: 0.105%, and N: 0.0035%
A slab of non-oriented silicon steel containing slab was heated at a low temperature of 1150 ° C. and then used as a hot rolled coil having a plate thickness of 2.8 mm.

This hot-rolled coil was tandem cold-rolled to a sheet thickness of 0.55 mm, and then treated in a continuous heat treatment facility for cold-rolled sheets according to the present invention shown in FIG. After annealing at 800 ℃, reduce the sheet thickness to 0.50mm with a split-type 20-high rolling mill with a work roll diameter of 150mm (sheet thickness reduction rate 10
%), A semi-organic insulating film was applied to the surface of the strip, baked, and rewound with a tension reel to obtain the final product. Product quality, magnetic characteristics,
Compared with skin pass rolling rolled by a reverse mill,
The highest characteristics were the same, but the average characteristics were improved. In addition, the amount of off-gauge was reduced and the number of manufacturing days after hot rolling was halved.

[Brief description of drawings]

FIG. 1 is a quasi-schematic isometric view of a typical prior art continuous heat treatment equipment for annealing / insulating coating of a cold-rolled sheet of non-oriented silicon steel (upper and lower rows are continuous).

FIG. 2 is a quasi-schematic isometric view of continuous heat treatment equipment for annealing and insulating film coating on a cold-rolled sheet of non-oriented silicon steel, which is one embodiment of the present invention (upper and lower rows are continuous. Exist).

[Explanation of symbols]

1 Payoff reel 2 Entry side shearing machine 3 Welding machine 4 Entry side storage looper 5 Central storage looper I 6 Central storage looper II 7 Exit side storage looper 8 Exit side shearing machine 9 Tension reel 11 Entry side cleaning device 12 Furnace part 13 Precoat device 14 Cold Rolling Mill 15 Outlet Cleaning Device 16 Insulating Film Coating Device 17 Baking Device 21a, 21b, 22a, 22b, 23a, 23b, 2
4a, 24b, 25a, 25b, 25c, 25d, 26
a, 26b, 26c, 26d, 27a, 27b, 28
a, 28b, 29a, 29b, 29c, 29d, 30
a, 30b Bridle roll 41, 42, 43, 44 Tension meter 51 Tension meter combined shape meter 60 Strip

Claims (7)

[Claims] 1. A continuous heat treatment facility for cold-rolled strips of non-oriented silicon steel, a pay-off reel for unwinding a cold-rolled coil, and a furnace section for annealing the cold-rolled strip. Cold-rolled annealed strips from the furnace section, or, or skin pass rolling, a rolling unit that performs the same rolling mill, and the annealed, or after the annealing, skin-pass rolled, strips an insulating film A continuous heat treatment facility for cold-rolled sheets of non-oriented silicon steel, comprising: an insulating film coating portion for coating / baking; and a tension reel for rewinding a coil coated with the insulating film. 2. The continuous heat treatment equipment for cold-rolled non-oriented silicon steel sheet according to claim 1, wherein the rolling mill is a split die 20.
A continuous heat treatment facility for cold-rolled strips of non-oriented silicon steel, which is selected from the class consisting of a multi-roll rolling mill or a 12-high rolling mill. 3. The continuous heat treatment equipment for cold-rolled non-oriented silicon steel according to claim 1, wherein equipment for applying rolling oil to the surface of the strip is provided upstream of the rolling mill. A continuous heat treatment equipment for cold-rolled non-oriented silicon steel. 4. A method of continuously heat treating a cold-rolled sheet of non-oriented silicon steel, the step of unwinding a cold-rolled coil in one continuous processing line, and the cold-rolled strip. A step of annealing, cold rolling the annealed strip, or, a cold rolling step for making the skin pass rolling performed in the same rolling mill, and the annealed, or after the skin pass rolling after annealing, A continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel, comprising: a step of applying and baking an insulating film to a strip; and a step of rewinding a coil coated with the insulating film. 5. The continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel according to claim 4, wherein the cold rolling step is performed by a split type 20-high rolling mill or a 12-high rolling mill. A method for continuously heat treating a cold-rolled sheet of non-oriented silicon steel, which is characterized. 6. The continuous heat treatment method for cold-rolled non-oriented silicon steel sheet according to claim 4 or 5, wherein rolling oil is applied to the surface of the strip upstream of the cold rolling step in the line. A continuous heat treatment method for a cold-rolled sheet of non-oriented silicon steel, comprising the step of: 7. A continuous heat treatment method for a cold-rolled sheet of a non-oriented silicon steel sheet according to claim 4, wherein:
A continuous heat treatment method for cold-rolled strips of non-oriented silicon steel, which comprises passing a cold-rolled strip of non-oriented silicon steel twice in a component system having no α-γ transformation.