JP2021030241A - Rolling equipment and rolling method - Google Patents

Abstract

To provide rolling equipment and a rolling method that prevent variations in material quality in a plate width direction even with a coil which was self-annealed after hot rolling (a self-annealing coil) to prevent plate breakage caused by subsequent drawing in a cold tandem rolling mill and that are inexpensive and have excellent space-saving property and high efficiency (including workability).SOLUTION: Rolling equipment has a hollow cylindrical sleeve for inserting a coil after hot rolling when the coil is cooled in atmosphere. The sleeve is open at both ends in its axial direction, and at least a part in the thickness direction of an outer peripheral part is formed of a heat insulation material.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rolling facility and a rolling method for cold tandem rolling of a self-annealed coil by self-annealing the wound coil after hot rolling in the cooling process to omit the hot coil annealing step. It is a thing.

The steel type of the self-annealed coil is high alloy steel, and specific examples thereof include high-strength steel sheets (high-tensile steel sheets), stainless steel sheets, and electromagnetic steel sheets. Further, as a manufacturing process of hot-rolled steel strips (hot-rolled steel strips), steel slabs are hot-rolled by a rough rolling mill and a finish rolling mill, wound around a coil, and the coil is further cooled in the atmosphere. There is a manufacturing process, a manufacturing process in which rough rolling is omitted, hot rolling equivalent to finish rolling is performed, the coil is wound around a coil, and the coil is cooled in the atmosphere. In addition, thin-walled slabs (thin-walled slabs) manufactured by the double-roll type continuous casting method or belt-type continuous casting method known as the thin plate continuous casting and rolling method are immediately equivalent to a finish rolling mill without rough rolling. The manufacturing process of rolling down the coil with an in-line mill and then cooling the coil in the air, and the continuous continuous casting, hot rough rolling, and hot finish rolling. There is also a process.

Hereinafter, as an example here, a manufacturing process including a step of hot rolling a steel slab with a rough rolling mill and a finishing rolling mill, winding it around a coil, and then cold rolling a strip coil obtained by cooling the coil in the atmosphere. The case of manufacturing non-directional electromagnetic waves will be described as an example.

For example, Patent Document 1 describes in terms of mass% C ≦ 0.008, 2 ≦ Si + Al ≦ 3, 0.02 ≦ Mn ≦ 1.0, S ≦ 0.003, N ≦ 0.002, Ti ≦ 0.003. , 0.001 ≤ REM ≤ 0.02, and 0.3 ≤ Al / (Si + Al) ≤ 0.5, and heat the non-directional electromagnetic steel plate slab containing the balance Fe and unavoidable impurities. By performing hot finish rolling in a temperature range where the interfinish rolling temperature is 1050 ° C or higher, the subsequent non-injection time is set to 1 second or more and 7 seconds or less, and winding is performed at 700 ° C or lower by water injection cooling. A manufacturing method that replaces the hot rolling annealing step by a cooling process after hot finish rolling is disclosed.

Japanese Unexamined Patent Publication No. 2010-242186 Japanese Unexamined Patent Publication No. 60-46804 JP-A-2002-239617 Japanese Unexamined Patent Publication No. 2003-340510 Japanese Unexamined Patent Publication No. 3-60810 Japanese Unexamined Patent Publication No. 2014-8520 Japanese Unexamined Patent Publication No. 2015-167992

"Illustrated electromagnetic steel plate" (Shin Nihon Steel Co., Ltd., 1994), p.67

However, as shown in Patent Document 1, for example, a self-annealing coil for a non-directional electromagnetic steel sheet wound around a coil by omitting the hot coil annealing step by self-annealing in the cooling process after continuous hot rolling is provided. It was recognized that there are the following problems in continuous cold rolling in a cold tandem rolling mill after pickling.

1) The hot-rolled steel strip that has been hot-rolled is usually wound into a coil at, for example, 700 ° C. or lower, and then cooled in the atmosphere in the state of the coil. In such a cooling process, the cooling rate varies depending on the position of the material in the coil. Specifically, the cooling rate of the outer peripheral portion of the coil is higher than the cooling rate of the inner peripheral portion, and the cooling rate of the end portion (edge portion) in the plate width direction is lower than that of the portion closer to the center portion in the plate width direction. The speed increases.
Due to such variations in the cooling rate in the coil, non-uniformity of the material, especially in the strength, occurs in the coil in the longitudinal direction and the width direction of the plate, and eventually, the deformation resistance in the cold becomes non-uniform. .. Here, such a coil is referred to as a self-annealing coil.

The material (steel type) of the self-annealing coil is not limited to the above-mentioned non-directional electromagnetic plate, and non-uniformity of the material, particularly non-uniformity of strength occurs in the plate longitudinal direction and the plate width direction in the coil, which in turn causes non-uniformity of the material. It means a steel type in which non-uniform deformation resistance occurs in the cold.

Further, the self-annealing coil is not limited to a coil in which a steel slab is hot-rolled by a rough rolling machine and a finish rolling machine and wound around a coil as described above, and the coil is further cooled in the atmosphere. It also includes a coil in which hot rolling equivalent to finish rolling is performed by omitting rolling and winding is performed on a coil, and the coil is cooled in the atmosphere. For example, a thin-walled slab (thin-walled slab) manufactured by a double-roll type continuous casting method or a belt-type continuous casting method known as a thin plate continuous casting method is immediately equivalent to a finish rolling mill without rough rolling. It may be rolled down by an in-line mill, wound around a coil, and then cooled in the air, including such coils.
Further, there is also known a process in which continuous casting, hot rough rolling, and hot finish rolling are performed continuously without interruption. A strip that has been finish-rolled by such a continuous process is wound around a coil, and the process is performed. It shall also include a coil in which the coil is cooled in the atmosphere.

2) As described above, in the self-annealed coil, the non-uniformity of the material in the longitudinal direction and the plate width direction in the coil is near the outer periphery and the edge of the self-annealed coil (the width direction end of the wound hot-rolled steel strip). Although it occurs in the vicinity of the portion), the non-uniformity is remarkable in the region from the end portion (edge portion) in the plate width direction to the inside of 150 mm to 250 mm in 2 to 3 rounds on the outer peripheral side of the self-annealing coil. In this region, the strength of the end portion in the plate width direction of the strip may be about 10% to 20% higher than the strength of the central portion in the plate width direction.

3) When a self-annealed coil having non-uniform material as described above is continuously welded to form a strip, pickled and cold tandem rolled, the above-mentioned is used at the first stand of the cold tandem rolling mill. Since the difference in deformation resistance at the non-uniform material portion, that is, the deformation resistance at both ends in the plate width direction is larger than the deformation resistance at the center portion in the plate width direction, the shape of the rolled plate becomes medium elongation, and therefore, so-called Rolling may occur and plate breakage may occur.

4) If plate breakage occurs due to drawing due to medium elongation, the work roll at the rolling stand in the cold tandem rolling mill is often damaged. In that case, it is necessary to stop rolling and replace the work roll, which greatly reduces the productivity.

5) Furthermore, when the plate breakage due to drawing is severe (in the case of plate breakage due to severe medium elongation), it is necessary to replace not only the work roll but also the intermediate roll or backup roll in contact with the work roll. Become.

6) Especially at the time of high-speed rolling, the plate breakage due to drawing is severe, and it may take a long time of about 10 hours to recover, which causes a significant decrease in productivity.

As described above, with respect to the self-annealed coil, in the subsequent cold tandem rolling, plate breakage due to drawing is likely to occur, and there is a strong possibility that productivity will be hindered.
Therefore, there has been a demand for the development of rolling equipment and rolling methods for obtaining a self-annealed coil that has little variation in deformation resistance in the plate width direction and can prevent the occurrence of plate breakage in cold tandem rolling.

In general, it is known to control the plate shape during cold rolling in order to prevent drawing from occurring during cold rolling. That is, a shape detector is installed on the outlet side of the cold rolling mill stand to measure the rolled plate shape, and the cold rolling mill stand so as to fit in the desired plate shape, for example, not to have a medium elongation shape. It is known to control the shape control end (for example, work roll bender force) of the above (for example, Patent Document 2). Generally, such shape control is performed at the final stand of the cold rolling mill.

Further, Patent Document 3 proposes a method of measuring the rolled plate shape by installing a shape detector on the exit side of the rolling mill at the first stand of the cold tandem rolling mill and controlling the shape. Further, Patent Document 4 proposes a method in which a shape detector is installed on the exit side of the rolling mill in the first stand and the second stand of the cold tandem rolling mill to measure the rolled plate shape and control the shape. ing. Further, Patent Document 5 proposes a method in which a shape detector is installed on the exit side of a rolling mill in all stands of a cold tandem rolling mill to measure the rolled plate shape and control the shape.

On the other hand, Patent Document 6 discloses a shape control method when there is a non-uniform deformation resistance distribution in the plate width direction. That is, in Patent Document 6, the yield stress in the width direction of the hot-rolled steel strip is measured in advance at the positions of the tip portion, the central portion, and the tail end portion in the longitudinal direction of the hot-rolled steel strip, and the deformation resistance distribution pattern is investigated. A method of performing shape presetting of a rolling mill based on the result (different shape presetting is performed at the positions of the tip portion, the center portion, and the tail end portion in the longitudinal direction of the hot-rolled steel strip) is disclosed.

In the shape control method disclosed in Patent Documents 2 to 5, the plate shape is measured by a shape detector installed on the outlet side of any one or more rolling mill stands, and the measured plate shape is the target. This is a method of feedback-controlling the shape control end of the rolling mill stand so as to pass through. Although this method is effective for hot-rolled steel strips in which drawing does not easily occur even if the plate shape changes and relatively gradual changes such as thermal crowns, self-annealing is mainly the subject of the present invention. It is recognized that the coil is not always effective.

The reason is that in the self-annealed coil in which the hot coil annealing step is omitted, the deformation resistance distribution is highly non-uniform and changes rapidly in the longitudinal direction, so that the shape after rolling also changes sharply. However, in the shape control method by feedback control as shown in Patent Documents 2 to 5, the time wasted between the hot-rolled steel strip from a certain rolling mill stand to the shape detector on the exit side of the rolling mill stand. There is. Therefore, when the shape change is large and sudden, the feedback control cannot keep up with the time.

When the present inventors investigated the data of the plate breakage of the first stand due to the drawing of the self-annealed coil, the edge elongation with a steepness of 1% took about 2 seconds at a rolling speed of 200 m / min at the first stand. It has been confirmed that the steepness changes from 2% to medium elongation, and as a result, drawing occurs and the plate may break. In this case, since the shape detector is installed at a location 3 m away from the roll bite outlet of the first stand (it is impossible to make it less than 3 m due to space), it takes about 1 second to detect the shape. However, even if the shape control is started after that, it takes about 1 second, so that it takes about 2 seconds from the roll bite to actually perform the shape control. Therefore, it is difficult to prevent the plate from breaking because it is not in time for the above-mentioned sudden shape change. At this time, if the rolling speed at the first stand is reduced to 100 m / min, the relative rolling length at which shape control is started is shortened by half, but the wasted time until the shape is detected is doubled. Therefore, it is difficult to prevent plate breakage even if the rolling speed is lowered.

On the other hand, the yield stress in the width direction of the material at the tip portion, the center portion, and the tail end portion in the longitudinal direction of the original plate coil, which is disclosed in Patent Document 6, is measured in advance to investigate the deformation resistance distribution pattern, and the investigation result ( The method of performing shape presetting (feed forward control) on the rolling mill stand based on the prediction result) is effective for a material having reproducibility for each coil of the hot-rolled steel strip. However, the self-annealed coil targeted by the present invention has a change in plate shape during cold rolling depending on the plate shape of hot-rolled finish, scale, and coil cooling conditions after winding (coil arrangement position, seasonal factors, etc.). The situation is very different. For this reason, there is a large variation in the prediction results, and it cannot be said that there is practical reproducibility. That is, it is difficult to pattern the deformation resistance distribution over the entire coil length based on the prediction survey. By the way, if an inappropriate pattern is input, there is a risk of promoting medium elongation and inducing plate breakage.

In addition, without predicting the deformation resistance distribution pattern as described above, it is conceivable to preset the rolling mill stand to the edge elongation shape so that the deformation resistance distribution does not become medium elongation even if the deformation resistance distribution changes. In this method, the non-uniformity of the deformation resistance distribution of the hot-rolled steel strip is not so large, the deformation resistance does not change so much in the length direction of the hot-rolled steel strip, and the material does not vary from coil to coil of the hot-rolled steel strip. Is effective to some extent. However, in the self-annealed coil mainly targeted in the present invention, the distribution of the deformation resistance distribution in the plate width direction varies greatly in the length direction of the hot-rolled steel strip. Therefore, if presets are made so that the edge elongation occurs even in places where the deformation resistance distribution is uneven (the plate edge is hard) in order to prevent medium elongation, the edge elongation occurs where the deformation resistance distribution is uniform (the plate edge is hard). May become too large, and conversely, drawing may occur due to excessive edge elongation, which may induce plate breakage.

As described above, conventionally, when cold tandem rolling is performed on a coil having a large non-uniform deformation resistance distribution in the longitudinal direction and the width direction of a hot-rolled steel strip, such as a self-annealed coil, the occurrence of plate breakage is surely prevented. The reality is that the method of doing this has not yet been established.

It is known that the non-uniformity of the material of the self-annealed coil in the plate width direction as described above is caused by the non-uniform cooling of the wound coil after hot rolling. Therefore, for example, Patent Document 7 proposes a method in which a wound coil after hot rolling is surrounded by a box and slowly cooled so as to cool as uniformly as possible. However, this method requires a large amount of equipment and a large space, and although it is effective for low-yield steel grades, there are cost and space problems for high-yield steel grades, and it is low-cost, space-saving, and highly efficient. It is desired to develop rolling equipment and rolling methods having excellent properties (including workability).

The present invention has been made in view of the above problems, and even in a coil self-annealed after hot rolling (self-annealed coil), material variation in the plate width direction can be prevented, and then in a cold tandem rolling mill. To provide rolling equipment and rolling methods that prevent plate breakage due to drawing during rolling, and that are low cost and excellent in space saving and high efficiency (including workability). is there.

Specific aspects of the rolling equipment and rolling method of the present invention are shown below.

The rolling equipment of the basic aspect (first aspect) of the present invention is
In a rolling equipment where a coil that has been hot-rolled and wound is cooled in the atmosphere and then cold-rolled by a cold tandem rolling mill.
A hollow cylindrical sleeve for inserting the coil in cooling the wound coil after hot rolling in the atmosphere is provided.
The sleeve is characterized in that both ends in the axial direction are open and at least a part in the thickness direction is made of a heat insulating material.

Further, the rolling equipment of the second aspect of the present invention is
In the rolling equipment of the first aspect,
The sleeve is characterized in that its axial length L satisfies the following equation (1).
_{L ≧ W + 2 · (D} S -3 · D CO / 4-D CI / 4) tan30 ··· (1)
Here, in equation (1),
W: Coil plate width,
D _CO : Coil outer diameter,
_DCI : Coil inner diameter,
D _S: a sleeve inner diameter, the unit of the angle (30) of tan is a degree, and all other dimensions are mm.

Further, the rolling equipment of the third aspect of the present invention is
In the rolling equipment of the first aspect,
The sleeve is characterized in that a reflective layer is formed on the upper portion of the inner peripheral surface of the sleeve when the sleeve is arranged so that its central axis is horizontal.

The rolling method according to the fourth aspect of the present invention is
In hot rolling by the rolling equipment of any one of the first to third aspects, the coil is wound around a coil, the coil is cooled in the atmosphere, and then cold rolled by a cold tandem rolling mill.
It is characterized in that the wound coil after hot rolling is inserted into the sleeve and cooled in the atmosphere.

In the rolling equipment and rolling method of the present invention, even a coil self-annealed after hot rolling (self-annealed coil) prevents material variation in the plate width direction, and the plate is drawn by drawing during subsequent rolling with a cold tandem rolling mill. It is possible to prevent breakage, and it is excellent in space saving and high efficiency (including workability) at low cost.

It is a schematic diagram which shows the situation of cooling a winding coil after hot finish rolling step by step by using the rolling equipment which concerns on one Embodiment of this invention. It is a longitudinal side view which shows 1st example of the sleeve used for the rolling equipment of this invention. FIG. 2 is a cross-sectional view taken along the line III-III in FIG. It is a longitudinal side view which shows the 2nd example of the sleeve used in the rolling equipment of this invention. FIG. 5 is a cross-sectional view taken along the line VV in FIG. It is a longitudinal side view which shows the 3rd example of the sleeve used for the rolling equipment of this invention. FIG. 6 is a cross-sectional view taken along the line VII-VII in FIG. It is a longitudinal side view which shows the 4th example of the sleeve used in the rolling equipment of this invention. FIG. 8 is a cross-sectional view taken along the line IX-IX in FIG. It is a longitudinal side view which shows the 5th example of the sleeve used for the rolling equipment of this invention. FIG. 8 is a cross-sectional view taken along the line XI-XI in FIG. It is a longitudinal side view of the sleeve for demonstrating the preferable dimensional relationship of the sleeve used in the rolling equipment of this invention. It is a graph which shows the relationship between the angle θ and the intensity ratio by the experiment of the present inventors. It is a longitudinal side view which shows the sixth example of the sleeve used in the rolling equipment of this invention. FIG. 14 is a cross-sectional view taken along the line XV-XV in FIG. It is a schematic diagram which shows an example of the hot rolling equipment part in the rolling equipment of this invention. It is a schematic diagram which shows an example of the cold rolling equipment part in the rolling equipment of this invention.

As an example, the rolling equipment of the present invention comprises the equipment shown in FIGS. 16 and 17, which will be described later.
FIG. 16 is a diagram showing the finish rolling mill and subsequent parts of the hot rolling equipment. Although not shown, the steel slab is heated in a heating furnace, then the width is adjusted by a sizing press, and the steel slab is rolled to a plate thickness in the middle by a rough rolling mill. As shown in FIG. 16, the slab 2 thus stretched to the intermediate plate thickness by the rough rolling mill is rolled to the finished plate thickness by the finish rolling mill 3 and then wound through the cooling zone 4. It is wound into a coil by the machine 5. The wound coil 15 becomes self-annealing coils C1 and C2 by cooling in the atmosphere. After that, the self-annealing coils C1 and C2 are cold-rolled by the cold tandem rolling mill 11 and stretched to a thinner thickness, as shown in FIG. 17, for example.

Here, in the rolling equipment of the present invention, as shown in FIG. 16 as an example, when the coil 15 after hot finish rolling is cooled in the atmosphere, a hollow cylindrical sleeve for inserting the coil 15 is inserted. It has 20. Further, both ends of the sleeve 20 in the axial direction are open, and at least a part in the thickness direction is made of a heat insulating material.

Among such rolling equipment, an example of a situation in which a coil wound by hot rolling is inserted into a sleeve and cooled in the atmosphere is shown step by step in FIG.

In FIG. 1, (a) shows a coil 15 immediately after being wound after hot finish rolling. The coil 15 is still in a high temperature state of about 700 ° C.
The coil 15 is removed from the take-up shaft (mandrel) of the take-up machine (coiler), and an appropriate support shaft 16 is horizontally aligned in the hollow portion on the inner peripheral side thereof as shown in FIG. 1 (b). Is inserted and transferred to the position of the sleeve 20 (near the winder) by the support shaft 16. The support shaft 16 may be, for example, a fork of a forklift or a dedicated cantilever support rod. The sleeve 20 stands by in the vicinity of a winder (not shown) so that its central axis Os is horizontal. Here, the sleeve 20 is made so that its axial length L is larger than the width (width of the wound plate) W of the coil 15.

Then, as shown in FIG. 1C, the coil 15 is inserted into the inner hollow portion of the sleeve 20 along the horizontal direction. Here, the coil 15 is arranged so that the center position Mc in the width direction (width direction of the wound plate) coincides with or is close to the center position Ms of the axial length of the sleeve 20. Is inserted into the sleeve 20.

After that, the support shaft 16 is lowered, and as shown in FIG. 1 (d), the support shaft 16 is allowed to stand on the bottom surface of the inner hollow portion of the sleeve 20 of the coil 15, and then pulled out from the coil 15 (FIG. 1 (d)). Then, while maintaining this state, the coil 15 is allowed to cool in the atmosphere, and self-annealing proceeds. The self-annealed coil (self-annealed coil) is subjected to cold tandem rolling, as will be described later with reference to FIG.

As described above, by allowing the coil 15 to cool (self-anneal) while being inserted into the sleeve 20, the self-annealed coil has a strength difference (non-uniform deformation resistance distribution) in the plate width direction at the outer peripheral side portion. ) Becomes smaller.
The reason is as follows.

That is, in the conventional ordinary self-annealing coil, after hot finish rolling-winding, air cooling is performed without a heat insulating member such as a cover. At this time, in the coil heated during hot rolling, the outer peripheral portion of the coil and the end portion of the coil (end portion in the width direction) have a high cooling rate, so that the temperature drops faster than that of the central portion of the plate. As a result, the growth of crystal grains is suppressed, and the grains are finer and harder than the central part of the plate. As a result, the strength difference (non-uniformity of the deformation resistance distribution) increases in the plate width direction, and as described above, the plate breakage due to drawing is likely to occur in the subsequent cold tandem rolling.

On the other hand, in air cooling using the sleeve as described above, the inner peripheral surface of the sleeve functions as a heat barrier, and the heat radiated from the end of the coil plate is reflected by radiation on the inner peripheral surface of the sleeve. , Come back to the coil side. As a result, the cooling rate of the outer peripheral portion of the coil and the end portion of the plate is slowed down, the growth of crystal grains at that portion is promoted, and the strength difference between the center portion of the plate and the end portion of the plate (deformation resistance distribution is poor). Uniformity) is considered to be smaller.

Further, here, simply by inserting the coil into a sleeve having a simple shape of a hollow cylinder with both ends open, a self-annealed coil having a small variation in deformation resistance distribution can be obtained as described above. It can be said that the rolling equipment and rolling method are excellent in space saving and high efficiency (including workability) at low cost as compared with the case of using a box as shown.

Further, each example of the specific configuration of the sleeve 20 will be described with reference to FIGS. 2 to 11.

The sleeve 20 has a hollow cylindrical shape with both ends open as a whole. At least a part of the sleeve 20 in the thickness direction (radial direction as a cylinder) of the outer peripheral portion (cylindrical portion portion) is made of a heat insulating material. Specifically, for example, as shown in FIGS. 2 and 3 as a first example, ceramic fibers (ceramic wool) are formed on the inner circumference of a hollow cylindrical high-rigidity outer cylinder portion 20a made of a high-rigidity material such as iron. ), Rock wool fiber, or a heat insulating inner cylinder portion 20b made of a heat insulating material such as silica wool may be fitted or attached to form a two-layer structure.

Further, as shown in FIGS. 4 and 5 as a second example, the sleeve 20 is coated with an inner surface coating layer 20c made of the same heat insulating material on the inner peripheral surface of the same high-rigidity outer cylinder portion 20a. It may have a two-layer structure.

Further, as shown in FIGS. 6 and 7 as a third example, the sleeve 20 has a small-diameter hollow cylindrical high-rigidity made of the same high-rigidity outer cylinder portion 20a and a high-rigidity material such as iron. A three-layer structure may be formed in which a heat insulating intermediate cylinder portion 20e made of the same heat insulating material as described above is interposed between the inner cylinder portion 20d.

In addition, although not shown, when sufficient rigidity can be secured only by the heat insulating material (for example, when a hard ceramic sintered body is used), a one-layer structure in which the entire sleeve 20 is integrally formed by the heat insulating material is used. It is also possible to do.
In any case, the axial length of the heat insulating material portion of the sleeve 20 (the length in the direction corresponding to the plate width direction of the self-annealing coil) is preferably equal to the total length L of the sleeve 20. In other words, it is preferable that the heat insulating material portion is formed over the entire length L of the sleeve 20.

Further, in any case, the inner diameter of the sleeve 20 is set to be somewhat larger than the outer diameter of the coil 15, and the length L in the axial direction is set to be somewhat larger than the width (plate width) of the coil 15. As a result, the wound coil 15 after hot finish rolling can be easily inserted into the sleeve 20, and both ends of the coil 15 do not protrude from both ends of the sleeve 20 in the width direction. The coil 15 can be accommodated.

Further, as shown in FIGS. 8 and 9, a protrusion 21 for positioning the coil 15 (or preventing the coil from sliding in the sleeve) is provided on the inner peripheral surface of the sleeve 20. May be good. Further, as shown in FIGS. 10 and 11, a stopper 22 may be provided in order to prevent the sleeve 20 itself from rolling.

In the above description, the case where the coil 15 is inserted into the sleeve 20 after the coil 15 is removed from the winding shaft (mandrel) of the winding machine (coiler) has been described. However, in some cases, the coil 15 is inserted into the winding machine. The sleeve 20 may be attached so as to surround the coil 15 before being removed from the take-up shaft (mandrel) of the (coiler).

Preferred conditions for the dimensions of the sleeve 20 as described above, particularly the length L in the axial direction, will be described with reference to FIG.

It is desirable that the axial length L of the sleeve 20 satisfies the following equation (1).
_{L ≧ W + 2 · (D} S -3 · D CO / 4-D CI / 4) tan30 ··· (1)
Here, in equation (1),
W: Coil plate width,
D _CO : Coil outer diameter,
_DCI : Coil inner diameter,
D _S: a sleeve inner diameter, angular unit of tan is a degree, and all other dimensions are mm. The sleeve inner diameter D _S means the inner diameter of the entire sleeve containing the heat insulating material.

The meaning of equation (1) is as follows.

As shown in FIG. 12, lower surface sleeve state (hence the coil 15 which is placed in sleeve 20 so that coil 15, the longitudinal central position Oc coincides with the plate width direction center position O _S of the sleeve 20 20 is in contact with the bottom of the inner surface).
Further, from the outer peripheral surface 15a of the coil 15 toward the inner peripheral surface 15b of the coil, the end position in the coil width direction at a position 1/4 _{of the outer diameter / inner diameter difference D (= D CO-} D _{CI) of the coil 15 is set.} Let it be P. Further, let Q be the position of the inner peripheral surface of the end portion of the sleeve 20 in the length direction. Then, let θ be the angle formed by the line segment M from the position P to the position Q with respect to the surface N orthogonal to the central axis of the coil 15.

If the horizontal length (the protruding length on one side) at which the end of the sleeve 20 protrudes from the end of the coil 15 is Lp,
_{Lp = (D S -3 · D} CO / 4-D CI / 4) tanθ ··· (2)
Can be expressed as.
The total length L of the sleeve is
L = W + 2 ・ Lp ・ ・ ・ (3)
Therefore, the following equation (4) is derived from the equations (2) and (3).
_{L = W + 2 · (D} S -3 · D CO / 4-D CI / 4) tanθ ··· (4)

Then, if the angle θ is set to 30 degrees or more in the equation (4), the above equation (1) can be obtained. That is, as will be described later, as a result of various experiments conducted by the present inventors, if the above angle θ is 30 degrees or more, the cooling rate at the outer peripheral portion of the coil and at the end of the plate width becomes slow, and at that portion. It was found that the growth of the crystal grains of the above was promoted and the strength difference (non-uniformity of the deformation resistance distribution) between the central portion of the plate and the edge of the plate was reduced.

Here, in order to exert the heat retaining effect of the sleeve, particularly the heat retaining effect on the outer peripheral portion of the coil and both end portions in the plate width direction, the radiant heat from that portion of the coil is transmitted from both ends of the gap between the sleeve and the coil. It is preferable not to escape to the outside as much as possible. As a condition for that, in particular, radiant heat from the outer peripheral portion of the coil and both ends in the plate width direction is reflected by the inner peripheral surface of the sleeve and returned to the coil as radiant heat, so that the heat retention effect of that portion is enhanced. It has been experimentally found that the angle θ is set to 30 degrees or more, that is, it is preferable that the total length L of the sleeve satisfies the above equation (1).

The results of some of the experiments by the present inventors are shown in FIG.
FIG. 13 shows the angle θ that affects the value (strength ratio) obtained by dividing the strength of the plate end portion (proof stress 5 mm inside from the plate edge) by the strength of the plate center portion (proof stress of the plate center portion) in the coil after self-annealing. It shows the result of investigating the influence of. As the coil, a coil having a width of 1220 mm, a unit weight of 15 tons, a coil inner diameter of 51 mm, and a coil outer diameter of 1500 mm was mainly used.
The sleeve has a two-layer structure shown in FIGS. 2 and 3, and the iron high-rigidity outer cylinder portion 20a has a thickness of 50 mm and an inner diameter of 1760 mm, 1860 mm, and 1960 mm. Further, the heat insulating inner cylinder portion 20b on the inner surface (entire area, all circumference) side of the sleeve was formed of a ceramic fiber having a thickness of 30 mm. Therefore, the inner diameter (including the heat insulating material) of the entire sleeve has three levels of 1700 mm, 1800 mm, and 1900 mm.

Self-annealing is performed by setting a sleeve in which the angle θ is variously changed (and therefore the sleeve length L is variously changed) from the one without a sleeve (the angle θ is 0 degrees) to θ = 60 degrees. The strength ratio was investigated. The conditions for self-annealing are that the hot finish rolling end temperature is 1080 ° C and the winding temperature is 680 ° C. After winding is completed, the coil is removed from the winding machine and inserted into the sleeve within 120 seconds to reach room temperature. It was air-cooled.

From the results shown in FIG. 13, from zero to about 30 degrees, the intensity ratio decreases as the angle θ increases, and when the angle θ becomes larger than about 30 degrees, the effect is saturated. I found. Then, it was found that the intensity ratio is less than 5% when the angle θ is about 30 degrees or more. Here, when the strength ratio is less than 5%, in the subsequent cold tandem rolling, although a slight shape change may occur, it does not result in a violent medium elongation that causes drawing, in other words, medium elongation. It was confirmed that the plate breakage due to the above can be avoided.

Further, when the same investigation was carried out by changing the plate width, the coil unit weight, the coil inner diameter and the outer diameter in various ways, the results shown in Tables 1A and 1B were obtained. In Tables 1A and 1B, ◯ in the non-uniformity evaluation column indicates an intensity ratio of less than 5%, and × indicates an intensity ratio of 5% or more.

From Tables 1A and 1B, it is clear that the strength ratio can be suppressed to less than 5% by setting the sleeve length L so that the angle θ is 30 degrees or more.

In the above, as shown in FIGS. 14 and 15, the sleeve 20 has a reflective layer 23 on the upper portion of the inner peripheral surface of the sleeve 20 in a state where the sleeve is arranged so that its central axis is horizontal. It may be formed. If such a reflective layer 23 is formed, the radiant heat from the end portion in the plate width direction of the outer peripheral portion of the coil can be effectively reflected by the reflective layer 23. As a result, the sleeve length can be shortened by about 5 to 20% as compared with the case where the reflective layer is not provided. The reflective layer 23 may be formed of, for example, a metal plate having a metallic luster or formed by coating, and the range in which the reflective layer 23 is formed is as shown in FIG. It is preferable to set the angle range α with respect to the central axis position O to be 100 degrees or more, more preferably 110 degrees or more.

<Embodiment of rolling equipment>

Further, a suitable example of the overall configuration of the rolling equipment when the rolling method of the present invention is applied to a manufacturing line of an electromagnetic steel sheet will be described with reference to FIGS. 16 and 17.

FIG. 16 is a diagram showing an example of a portion of the rolling equipment of the present invention after the finish rolling mill in the hot rolling equipment.
In FIG. 16, the slab 2 is rolled by the finish rolling mill 5 so as to have a plate thickness of, for example, about 2 to 5 mm, and the strips from the finish rolling mill 5 pass through the cooling zone 4 and pass through the cooling zone 4. It is continuously wound by the winder 5 to become the coil 15.

The wound coil 15 is removed from the winder 5 and inserted into a sleeve 20 arranged in the vicinity of the winder 5. At this time, the coil 15 immediately after winding may be moved by a crane, for example, and attached to the sleeve 20 by using a forklift. Further, although not shown, equipment for automatically mounting the sleeve may be provided.
The coils self-annealed by being air-cooled while being inserted into the sleeve as described above (self-annealed coils C1 and C2) are sent to a cold tandem rolling facility as shown in FIG. 17 to be described later.

As an example of the present invention, C ≤ 0.008%, 2% ≤ (Si + Al) ≤ 3.0% by mass. It contains 02% ≤ Mn ≤ 1.0%, S ≤ 0.003%, N ≤ 0.002%, Ti ≤ 0.003%, 0.001% ≤ REM ≤ 0.02%, and further. Satisfy the relationship of 3% ≤ Al / (Si + Al) ≤ 0.5%, and use a slab for non-directional electromagnetic steel plate containing the balance Fe and unavoidable impurities so that the hot finish rolling temperature is 1050 ° C or higher. Hot finish rolling is performed in a temperature range, the subsequent non-injection time is set to 1 second or more and 7 seconds or less, winding is performed at 700 ° C or less by water injection cooling, and the wound coil is inserted into a sleeve for air cooling. It is preferable to use the self-annealing coils C1 and C2.

The self-annealing coils C1 and C2 obtained by the hot rolling equipment shown in FIG. 16 are sent to the cold rolling equipment shown in FIG.
In FIG. 17, the self-annealing coils C1 and C2 are supplied to the coil dispenser 7. The plate dispensed from the self-annealing coils C1 and C2 by the coil dispenser 7 is a continuous strip in which the tail end of the plate from the leading coil and the tip of the plate from the trailing coil are welded by the welding machine 8. (Self-annealed strip) becomes S and is sent to the looper 9. In the following. The self-annealed strip S dispensed from the self-annealed coils C1 and C2 and continuous is sometimes referred to simply as a strip or a self-annealed plate.
The looper 9 is controlled so that there is no stagnation in the supply of strips in the downstream process even when there is no payout during coil joining in the welding machine 8 (that is, when the strips are stopped running). The self-annealing coils C1 and C2 supplied to the coil dispenser 7 may be preheated to a temperature of 60 ° C. or higher in a hot bath or the like.

The self-annealed strip S that has passed through the looper 9 is supplied to the pickling facility 10. In this pickling facility 10, the surface scale of the self-annealing coil is removed (melted). In order to increase the melting efficiency before pickling, a rolling mill that cracks the surface of the self-annealed strip S, a leveler or tension leveler, a shot blast (dry or wet), or a grinder may be installed.

The self-annealed strip S, which has been pickled to remove surface scale, is sent to a cold tandem rolling mill 11 and rolled to a thinner plate thickness.

In the present embodiment, the cold tandem rolling mill 11 is composed of five rolling mill stands 11a to 11e arranged in series, and the first stand 11a to the fifth stand 11e are, for example, quadruple rolling mills, respectively. It is composed of (4 Hi mill).
Further, in the cold tandem rolling mill 11, although not shown, rolling lubricating oil that is made into an emulsion by mixing rolling lubricating oil called coolant with water is supplied on the inlet side and the outlet side of each stand. .. The supplied coolant is collected in a tank (not shown), and resuscitation lubrication is performed again to be supplied to each stand.

In the cold tandem rolling mill 11, for example, a self-annealed strip for non-oriented electrical steel sheets having a plate thickness of 2.3 mm and a plate width of 1200 mm is rolled to a plate thickness of 0.3 mm. As the coolant, for example synthetic ester (hindered complex esters) based oil and the rolling lubricant concentration of 2% at a temperature 60 ° C., in each stand 1 to 3 m 3 / ^min supply (inlet side and outlet side of the (Total), rolling lubrication and work roll cooling are performed.

The work roll diameters of the rolling mill stands 11a to 11e are, for example, 500 mm to 700 mm, the backup roll diameter is, for example, 1300 mm to 1600 mm, and the body length is, for example, 2000 mm.

Downstream of the cold tandem rolling mill 11, a cutting machine 12 for cutting continuous and rolled self-annealed strips is provided, and downstream of the cutting machine 12 for winding continuous and rolled self-annealed strips. The roselle reel 13 is deployed. Although not shown, the coil wound and cut by the roselle reel 13 is discharged from the roll, placed on a conveyor, and carried out to a factory or the like in the next process.

Hereinafter, examples (examples of the present invention) and comparative examples (conventional techniques) relating to the rolling method of the present invention will be described.
Both Examples and Comparative Examples were carried out in a rolling equipment having the configurations shown in FIGS. 16 and 17.

The strips subjected to tandem cold rolling in Examples and Comparative Examples are self-annealed strips for non-oriented electrical steel sheets having a plate thickness of 2.3 mm and a plate width of 1200 mm, and have a mass% of C: 0.007%, ( Si + Al): 2.5%, Mn: 0.5%, S: 0.001%, N: 0.001%, Ti: 0.001%, REM: 0.01%, and further, Al / (Si + Al): Using a slab for non-oriented electrical steel sheets that satisfies the relationship of 0.4% and contains the balance Fe and unavoidable impurities, hot finish rolling is performed so that the hot finish rolling temperature becomes 1090 ° C. And wound on a coil at 680 ° C.

Then, in the embodiment, the wound coil was inserted into the sleeve and air-cooled to room temperature as it was to self-anneal. The wound coil (hot-rolled finished coil) has a plate thickness of 2.3 mm, a plate width of 1220 mm, a coil inner diameter of 508 mm, a coil outer diameter of 1500 mm, and a coil unit weight of 15 tons. As the sleeve, a sleeve having an inner surface (entire area, all circumference) provided with a heat insulating material (ceramic fiber) having a thickness of 30 mm, an inner diameter (including the ceramic material) of 1600 mm, and a sleeve length of 1622 mm (angle θ = 30 degrees) was used. ..

On the other hand, in the comparative example, the coil after hot finish rolling (each dimension and weight are the same as in the example) is air-cooled to room temperature (without inserting it into the sleeve) and self-annealed without doing anything, and the self-annealed coil is used. did.

Further, in both Examples and Comparative Examples, the strips dispensed from the self-annealing coil were made continuous by welding and rolled as self-annealing strips by the above-mentioned cold tandem rolling mill to a plate thickness of 0.3 mm. The rolling speed of the final stand at the time of coil switching was 250 m / min, and the maximum rolling speed of the final stand was 1100 m / min. Further, as shown in Table 2 below, the tension between the stands was set to 50 to 250 MPa.
The self-annealed strips were rolled for 100 coils each according to Examples and Comparative Examples, and the above-mentioned strength ratio and the occurrence of plate breakage were examined.

According to Examples and Comparative Examples, the self-annealed strips were rolled for 100 coils each, and the above-mentioned strength ratio and the occurrence of plate breakage in the cold rolling mill were examined.
The results are as follows.

In the comparative example (conventional technique), the strength ratio was 1.1 to 1.2, and the probability of plate breakage was 89%.
On the other hand, in the examples (examples of the present invention), the strength ratio was 1.0 to 1.04, and no plate breakage was observed.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical idea described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

For example, in the above embodiment, a self-annealed material of non-oriented electrical steel sheet is targeted, but the present invention is not limited to such an example. For example, directional electromagnetic steel sheets, other high-strength steels, stainless steel sheets, etc. may be targeted, and not only self-annealed hot-rolled strips, but also large non-uniform deformation resistance in the strip length direction and plate width direction. If there is, it can be applied to prevent plate breakage during cold tandem rolling.

Further, the configuration of the portion upstream of the hot finish rolling mill in the rolling equipment of the present invention is not particularly limited. That is, in general, a hot rough rolling mill is often installed upstream of the hot finish rolling mill, but it is manufactured by a double roll type continuous casting method or a belt type continuous casting method known as a thin plate continuous casting rolling method. When hot-rolling a thin-walled slab (thin-walled slab), it is usual to immediately roll it with an in-line mill corresponding to a finish rolling mill without performing rough rolling, and this case is also included in the present invention.

Although the preferred embodiments and experimental examples of the present invention have been described above, these embodiments and experimental examples are merely examples within the scope of the gist of the present invention and do not deviate from the gist of the present invention. It is possible to add, omit, replace, and make other changes to the configuration. That is, the present invention is not limited by the above description, but is limited only by the scope of the appended claims, and of course, it can be appropriately modified within the scope.

C1, C2 Self-annealed coil S Self-annealed strip 2 Steel slab 3 Finishing rolling mill 5 Winding machine 7 Cold tandem rolling mill 15 Coil 20 Sleeve

Claims (4)

In a rolling equipment that is hot-rolled, the coil wound around the coil is cooled in the atmosphere, and then cold-rolled by a cold tandem rolling mill.
A hollow cylindrical sleeve for inserting the coil in cooling the wound coil after hot rolling in the atmosphere is provided.
The sleeve is a rolling equipment characterized in that both ends in the axial direction are open and at least a part in the thickness direction is made of a heat insulating material. In the rolling equipment according to claim 1,
The sleeve is a rolling equipment whose axial length L satisfies the following equation (1).
_{L ≧ W + 2 · (D} S -3 · D CO / 4-D CI / 4) tan30 ··· (1)
Here, in equation (1),
W: Coil plate width,
D _CO : Coil outer diameter,
_DCI : Coil inner diameter,
D _S: a sleeve inner diameter, angular unit of tan is a degree, and all other dimensions are mm. In the rolling equipment according to claim 1,
The sleeve is a rolling equipment characterized in that a reflective layer is formed on the upper portion of the inner peripheral surface of the sleeve in a state where the sleeve is arranged so that its central axis is horizontal. In hot rolling with the rolling equipment according to any one of claims 1 to 3, winding around a coil, cooling the coil in the atmosphere, and then cold rolling with a cold tandem rolling mill.
A rolling method characterized by inserting a wound coil after hot rolling into the sleeve and cooling it in the atmosphere.

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