JP2655991B2 - Cold rolling method for grain-oriented silicon steel sheet and roll cooling device for cold rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silicon-oriented grain-oriented silicon steel sheet, and more particularly to a technique for producing a material having a high magnetic flux density.

[0002]

BACKGROUND ART oriented silicon steel sheet is used in, the iron core for transformers and generators, (indicated by the value B ₈ in the strength of the magnetic field of 800A / m) flux density as the magnetic properties of iron Loss (50Hz AC iron loss value W at the maximum magnetic flux density of 1.7T)
_17/50 ) is required to be low.

Various efforts have been made to reduce the iron loss of this material, including (1) reducing the thickness of the steel sheet, (2) increasing the Si content, and (3) reducing the crystal grain size of the final product. As a result of the improvement, a material having a core loss of 0.90 W / kg at W _17/50 with a plate thickness of _0.23 mm can be obtained. However, it is not easy to reduce iron loss more than the current situation. That is, if the thickness of the steel sheet is made thinner than the current state, a secondary recrystallization defect described later is caused, and iron loss is adversely deteriorated. If the Si content is increased, cold rolling becomes difficult, and a method of reducing the crystal grain size is used. Also, if the average particle diameter is reduced to 4 to 8 mm or more, secondary recrystallization failure occurs and iron loss deteriorates.

However, in recent years, a significant improvement in iron loss has been made possible by a so-called magnetic domain segmentation technique for locally introducing strain or forming a groove on the surface of a steel sheet. That is, the aforementioned W
_{17/5 0} if iron loss material 0.90W / kg in by introducing a plasma jet or the like appropriate local distortion on the surface of the steel sheet, 0.
It has become possible to reduce the value to 80 W / kg. In order to obtain a material with excellent iron loss by such a method, unlike the conventional method, it is not necessary to reduce the crystal grain size of the final product, but exclusively reduce the thickness, increase the Si content, and increase the magnetic flux density It is necessary. Since it is difficult to further increase the Si content, improvement of iron loss depends on solving the technical problem of how to improve the magnetic flux density of a material having a small thickness.

In order to improve the magnetic flux density of a grain-oriented silicon steel sheet, it is necessary to highly integrate the crystal grain orientation of the product in the (110) [001] orientation, so-called Goss orientation. In the final finish annealing, the goss-oriented grains of the grain-oriented silicon steel sheet
Obtained by the secondary recrystallization phenomenon. In order to cause the secondary recrystallization, only the crystal grains close to the (110) [001] orientation are grown to suppress the growth of the crystal grains in other orientations, that is, the so-called selective growth is performed. It is necessary to add an inhibitor (inhibitor) for suppressing the growth of crystal grains having the orientation of. That is, the inhibitor forms a precipitated dispersed phase in the steel, and exhibits a function of suppressing grain growth.

As inhibitors, those having the strongest inhibitory effect have a stronger selective growth effect and can provide a material having a high magnetic flux density. Therefore, much research has been carried out so far. AlN. That is, as disclosed in JP-B-46-23820, Al
In steel sheets containing, a quenching treatment and a reduction ratio of final cold rolling in the final cold rolling prior to annealing by a high pressure ratio of 80% to 95%, with B ₁₀ high magnetic flux density material 1.92~1.95T is obtained Have been. However, in this method, since the rolling reduction is high, the frequency of appearance of (110) [001] oriented crystal grains, which are the nuclei of secondary recrystallization, is low, and the secondary recrystallization is unstable.
Even after the next recrystallization, the magnetic characteristics are also unstable, and there remains a problem that it is difficult to surely obtain good magnetic characteristics.
On the other hand, Japanese Patent Publication No. 63-11406 discloses a technique in which Sn and Cu are added to steel and the steel is manufactured by a single cold rolling method. Here, Sn is required to stabilize the secondary recrystallization and reduce the crystal grain size of the product, and Cu is required to counteract the harmful effect on the coating film due to the addition of Sn. However, with this technique, the secondary recrystallization was certainly stabilized, but on the contrary, the magnetic flux density was reduced, and the fluctuation of the magnetic properties in the longitudinal direction of the steel sheet remained unresolved.

The present inventors have found that the variation in the magnetic properties in the longitudinal direction of such a steel sheet depends on the method of cold rolling, and have researched and developed effective means for preventing this, and completed the present invention. I let it. By the way, with regard to the rolling technology for grain-oriented silicon steel sheets, Japanese Patent Publication No. 50-37130 discloses a technique for reducing the roll diameter of at least the final cold rolling to 300 mmφ or less, and Japanese Patent Application Laid-Open No. 2-80106 discloses a technique for tandem rolling. 1
Although a technique using a work roll having a roll diameter of less than 250 mm is disclosed for the stand, even if the roll diameter is reduced, the magnetic properties in the longitudinal direction of the steel sheet cannot be stabilized.

Further, Japanese Patent Publication No. 54-13846 and Japanese Patent Publication No. 54-29182 disclose a technique of performing a heat treatment for giving an aging effect between rolling passes, but also by aging between these passes. However, the phenomenon of instability of the magnetic properties in the longitudinal direction of the steel sheet was not eliminated. The present inventors have conceived of the present invention by focusing on the temperature of the steel sheet during rolling.
No. 493 discloses that the duration of the thermal effect from cooling to the start of cold rolling in high-temperature sintering before cold rolling is controlled, and that the steel sheet temperature is in the range of 50 to 350 ° C as the cold rolling temperature. Although the technology is disclosed, prior to performing cold rolling, both are subjected to a heat effect treatment by heating, and according to the study of the present inventors, this is because of the instability of the magnetic properties in the longitudinal direction of the steel sheet. It was one of the factors.

In Japanese Patent Publication No. 3-23607, the temperature of the first rolling pass in cold rolling is given as (x-3.0) ² × 100 according to the Si amount xwt% as the lower limit.
The upper limit is 200 × log depending on the strain rate y sec ^-1 of rolling.
Although a technique for controlling the temperature range given by y has been disclosed, since the temperature range is set by heating before cold rolling, according to the study of the present inventors, the magnetic field in the longitudinal direction of the steel sheet was also determined. This was one of the causes of the unstable characteristics.

[0010]

That is, the change of the roll diameter and the aging treatment between passes are effective for eliminating the instability of the magnetic properties in the longitudinal direction of the steel sheet due to the cold rolling at a high reduction ratio. No Japanese Patent Publication No. 50-26493 and Japanese Patent Publication No. 3-2360
The provision of the heat treatment effect before rolling disclosed in Japanese Patent No. 7 conversely increases the fluctuation of the magnetic properties in the longitudinal direction of the steel sheet,
It was the opposite effect.

Further, the cold rolling at a high reduction rate causes severe deterioration of the shape of the steel sheet, and there is a problem that the thickness of the central part of the steel sheet greatly changes particularly when the rolling speed changes. The present invention suppresses the variation of the magnetic properties in the longitudinal direction of the steel sheet and the variation of the thickness of the steel sheet, and provides a method for manufacturing a grain-oriented silicon steel sheet having excellent magnetic properties and a steel sheet shape, particularly a cold rolling method and an advantage thereof. It is an object of the present invention to provide a roll cooling device for a cold rolling mill that can be used.

[0012]

Means for Solving the Problems In cold rolling of a silicon steel sheet, the present inventors have found that controlling the exit side temperature rather than the entry side steel sheet temperature of the rolling can reduce the magnetic properties in the longitudinal direction of the steel sheet. The present invention has been found to be extremely effective for high-level stabilization and plate thickness shape, and has completed the present invention. That is, the present invention relates to a method for producing a grain-oriented silicon steel sheet, wherein when the steel sheet is cold-rolled, the temperature of the steel sheet after rolling out from the roll bite portion of the work roll is measured, and the measured value of the steel sheet temperature is measured. Controlling the oil amount of any one or more of the coolants of a work roll, a backup roll, a bearing roll, an intermediate roll and a wiper roll in a cold rolling mill so as to keep the steel sheet temperature constant based on A cold rolling method for grain-oriented silicon steel sheet,
The present invention provides a temperature sensor for measuring the temperature of the upper surface or lower surface of a steel sheet coming out of a roll bite portion of a work roll, and a negative signal such that the signal becomes a designated constant value with respect to a measurement signal of the temperature sensor. A roll cooling device for a cold rolling mill, comprising a temperature controller for transmitting a feedback signal and a flow controller for controlling the flow rate of the roll coolant based on the signal transmitted from the temperature controller.

[0013]

First, an experiment which led to the idea of the present invention will be described in detail. Si: 3.0%, C: 0.07%, Mn: 0.07%,
A hot rolled coil containing Al: 0.02% and having a thickness of 1.90 mm was subjected to hot rolled sheet baking at 1150 ° C. for 60 seconds with 4 coils, and then cooled at a rate of 40 ° C./sec using a mist.

These four coils have the following (a):
Cold rolling was performed under the four conditions (b), (c) and (d) to obtain a final thickness of 0.30 mm. First, as the condition (a), the first coil was set at 200 ° C. in a coil heating BOX furnace.
After the first pass, a Sendzimer rolling mill with a work roll diameter of 80 mmφ was used. The first pass 1.90 → 1.40 mm (26% reduction) The second pass 1.40 → 1.00 mm (29% reduction) The third pass 1.00 → 0.70mm (30% reduction) 4th pass 0.70 → 0.50mm (29% reduction) 5th pass 0.50 → 0.38mm (24% reduction) 6th pass 0.38 → 0.30mm (21% reduction) Was rolled to a sheet thickness of 0.30 mm.

At the time of rolling, the amount of the coolant oil to the wiper roll and the work roll was reduced to adjust the flow rate to a constant value. As a result, the temperature at the work roll tool inlet side is 185 to 206 ° C in the first pass and 215 to 225 in the second pass.
℃ 232 ~ 246 ° C in the third pass, 241 ~ 253 in the fourth pass
℃ 216-223 ℃ in the 5th pass, 186-193 ℃ in the 6th pass
It became.

The second coil was finished under condition (b) to a sheet thickness of 0.30 mm on a Sendzimer rolling mill having a work roll diameter of 80 mmφ in the same rolling pass schedule as in condition (a). During rolling, the oil amount of the coolant to the wiper roll and the work roll was reduced in the same manner as in the condition (a), and was adjusted to a constant flow rate. As a result, the temperature at the exit side of the work roll bite was 135-
167 ℃, 188 ~ 203 ℃ in the second pass, 198 ~ 2 in the third pass
23 ° C, 184-218 ° C in the fourth pass, 178-197 in the fifth pass
In the sixth pass, the temperature became 103 to 146 ° C.

The third coil is a condition (c) which is a Sendzimir mill having a work roll diameter of 80 mmφ, and has a rolling pass schedule of 0.30 mm in the same rolling pass schedule as the condition (a).
It finished to the thickness of. During rolling, the surface temperature of the steel sheet on the work roll tool exit side was measured, and the flow rate of coolant oil to the wiper roll and the work roll was controlled so that the temperature was constant. As a result, the temperature at the work roll tool exit side is 154 to 155 ° C in the first pass, 192 to 193 ° C in the second pass, 193 to 194 ° C in the third pass, 202 to 203 ° C in the fourth pass, and the fifth pass. At 196-197 ° C and 140-141 ° C in the sixth pass.

The fourth coil was finished under condition (d) to a sheet thickness of 0.30 mm on a Sendzimer rolling mill having a work roll diameter of 80 mmφ in the same rolling pass schedule as in condition (a). During rolling, the surface temperature of the steel sheet on the work roll tool entry side was measured, and the flow rate of the coolant oil to the strip coolant and the wiper roll was controlled so that the temperature was constant. as a result,
The temperature at the work roll tool input side is 25-26 ° C in the first pass,
136-137 ° C in the second pass, 198-199 ° C in the third pass, 4
The temperature could be controlled in the range of 198 to 199 ° C in the pass, 203 to 204 ° C in the fifth pass, and 168 to 169 ° C in the sixth pass.

Under these four conditions (a) to (d),
FIG. 1 shows the values of the sheet thickness deviation at the center of the sheet width after cold rolling.
As shown in Fig. 1, steel plate on the work roll tool exit side
The thickness deviation under the condition (c) in which the temperature is controlled is extremely good,
It can be seen that the shape of the steel sheet is much better. Then this
After degreasing these 4 coils, the dew point is 60 ° C, H_Two 55%, N_Two rose
Carbide annealing at 850 ° C for 2 minutes in a wet hydrogen atmosphere
Was. After this, TiO_Two5%, Sr (OH)_Two・ 8H_TwoContains 2% O
MgO to be applied as an annealing separator and wound into a coil
Afterwards, N at 840 ° C_Two Medium 40 hours, then 15 ° C / hr heating rate
Up to 1200 ° C in degrees_Two 25%, H _Two Secondary in 75% atmosphere
Recrystallization annealing, followed by H 2 at 1200 ° C. for 5 hours_Two Purification in
A final finish annealing consisting of annealing was performed. After this, unreacted
After removing the annealing separator, apply a tension coating and flatten
Baking treatment at 800 ℃ for 1 minute to serve as tanning baking
Was. Measurement of continuous iron loss value in the longitudinal direction of steel sheet of these coils
The results are shown in FIG.

As shown in the condition (a) of FIGS. 1 and 2, when a special heat effect treatment is performed before the start of rolling, the thickness deviation of the steel sheet is large and the variation of the magnetic characteristics is large. . On the other hand, when the amount of coolant oil for cooling the rolling rolls is controlled so that the temperature on the rolling exit side is constant in each rolling pass, the deviation of the sheet thickness is small, the fluctuation of the iron loss is small and the stability is good. Magnetic material is obtained. It is considered that the reason why such a good result was obtained was that the temperature of the steel sheet on the rolling-out side was controlled to be constant in each pass. Incidentally, under the condition (d) in which the temperature of the steel sheet on the rolling entry side is kept constant, the deviation of the sheet thickness and the fluctuation of the iron loss are large, and the desired effects cannot be obtained.

The present inventors conducted the following experiment in order to find out why the plate shape and the magnetic properties of the steel sheet were highly stable by the rolling at a constant temperature of the steel sheet on the rolling-out side. That is, C: 0.06% of thickness of 0.75 mm, Si: 3.2
%, Mn: 0.07%, Al: 0.02%, N: 0.008% A tensile test was performed while maintaining a constant temperature at a constant temperature. The result at this time is shown in FIG.

As shown in FIG. 3, as the temperature at the time of deformation rises from the ordinary temperature, the tensile strength (Tensile Strength) decreases rapidly up to 200 ° C. and increases again from 200 ° C. or more. This means that the deformation resistance of the material in the rolling process changes greatly depending on the rolling temperature. Normally, the control of the thickness of the steel sheet is performed by continuously measuring the thickness of the steel sheet on the rolling-out side and controlling the load on the rolling rolls assuming a certain material deformation resistance. It is considered that the deformation resistance of the material greatly fluctuates due to the fluctuation of the thickness, so that the thickness of the rolled sheet cannot be sufficiently controlled by the ordinary load control.

The reason why the high-level stabilization of the magnetic characteristics was obtained can be considered as follows. That is, as shown in FIG. 3, the change in the tensile strength due to the change in the processing temperature means that the mode of the slip deformation of the material changes if the temperature during the processing changes. That is, when the strength generally decreases due to the increase in temperature, it means that the modes of the slip deformation increase and multiple slips occur. The change in the deformation mode of the material changes the rolling texture due to rolling deformation, and eventually the recrystallization texture, and eventually changes the magnetic properties. Therefore, in order to stabilize the magnetic characteristics, it is necessary to control the rolling temperature to be constant.

The feature of the present invention lies in that it has been found that the method of adjusting the amount of coolant oil of various rolls is most effective in keeping the rolling temperature constant, and has a feature of the present invention. The second feature of the present invention is that it is useful to keep the temperature of the steel sheet on the rolling-out side constant. That is, the temperature at the time of rolling deformation is determined by factors such as the material temperature on the rolling entry side, the surface temperature of the contacting work roll, and the temperature rise due to processing heat.

Here, the most contributing factor to the variation in the rolling temperature is not the variation in the material temperature on the entry side of the rolling or the variation in the calorific value of the processing, but the variation in the amount of heat removal from the surface of the work roll. It was clarified in the experiment. Therefore, the most effective way to keep the temperature on the rolling-out side constant is to adjust the amount of coolant oil of each roll. In other words, the temperature control on the material roll-in side makes little sense when the amount of heat removal from the surface of the work roll is large.

The present inventors have completed the present invention based on such findings. Next, the slab component of the oriented silicon steel targeted by the present invention will be described below. C is required to be 0.02% or more in order to improve the hot rolled structure by utilizing the γ transformation.
On the other hand, if it exceeds 0.09%, decarburization will be poor, so 0.02 to 0.09%
Is preferable. Si needs to be 2.5% or more in order to increase electric resistance and improve iron loss. On the other hand, if it exceeds 5.0%, brittleness becomes so severe that cold rolling becomes difficult, so the range of 2.5 to 5.0% is preferable.

In addition to the above, Al,
One or more components selected from S and Se are required. In order to function as an inhibitor, Al needs to be 0.01% or more, but if it exceeds 0.04%, on the contrary, the suppressing power deteriorates. S and Se are required to be 0.005% or more, but if it exceeds 0.03%, it becomes difficult to dissolve the inhibitor.
03% is preferred.

Although the high magnetic flux density aimed at by the present invention is achieved by the inhibitor of AlN, the scope of application of the present invention is not limited to this range, and generally, the shape of the steel sheet after rolling is improved and the magnetic properties are stabilized. Is valid on Mn is an element necessary to prevent cracking during hot rolling.
0.02% or more is required, and it is also used as an inhibitor component such as MnS and MnSe. However, if it exceeds 0.3%, it becomes difficult to dissolve these MnS and MnSe.
It is preferable to set it to 0.3%.

N is a basic component for AlN precipitation,
It is also possible to replenish by the nitriding treatment in the cold rolling step, so that the lower limit is not required. However, if it exceeds 0.011%, it is gasified at the stage of slab heating, and swelling of steel is generated. Therefore, 0.011% or less is preferable. In addition, Sb, P, Sn, Bi, which are conventionally known as inhibitor reinforcing elements,
Of course, As, B, Ge, V, Nb and the like may be contained. In addition, to prevent cracking during hot rolling specific to silicon steel
Mo can be contained.

Next, a method of manufacturing a grain-oriented silicon steel sheet to be subjected to cold rolling in the present invention will be described. Silicon steel slabs containing the above components include those cast by ordinary continuous casting, thin slabs cast by sheet bar casters, etc., and slabs formed by re-rolling ingots. And then hot-rolled.

The coil after hot rolling is subjected to hot rolled sheet annealing as necessary, and the final sheet thickness is obtained by one cold rolling or a plurality of cold rollings sandwiching the intermediate ingot. The cold rolling method of the present invention can be applied to any of such rollings, and a certain effect can be obtained, but the effect is most remarkable especially when applied to final rolling. In addition, in applying the cold rolling of the present invention, aging treatment between passes, low lubrication rolling, small roll diameter rolling, etc., together with a known cold rolling method does not impair the effects of the present invention, but rather an additive effect. Can be expected.

The feature of the cold rolling method of the present invention is to continuously measure the temperature of the steel sheet after rolling, which has come out of the roll bite portion of the work roll. For the measurement, a calibrated radiation thermometer or a roll contact thermometer can be used. A predetermined temperature is set in advance with respect to the measured temperature of the steel sheet, and each coolant of a work roll, a backup roll, a bearing roll, an intermediate roll, and a wiper roll of a cold rolling mill is set so that the difference between the two becomes zero. Is to control at least one of the oil amounts by a negative feedback system. As a result, the temperature of the steel sheet on the rolling-out side can be maintained at a constant value, and thus the temperature of the material during rolling can be maintained at a constant value.

Here, controlling the temperature of the steel sheet before rolling is effective for keeping the material temperature during rolling constant, but it does not make a significant contribution, and it is not possible to measure the material temperature during rolling. It is possible. Therefore, it is necessary to measure the temperature of the steel sheet coming out of the roll bite portion and to make it a constant value in order to improve the shape of the steel sheet and stabilize the magnetic properties to a higher degree according to the present invention.

For controlling the rolling temperature, it is effective to control the roll temperature. For this purpose, the coolant of the work roll, backup roll, bearing roll, intermediate roll and wiper roll of the cold rolling mill is used. Adjusting the amount of oil is effective. Here, the work roll is a roll that directly rolls the material in contact with the material, and the backup roll is a work roll that corrects the deformation based on the rolling process of the work roll by applying a load. Is a roll provided on the outside of the machine or via an intermediate roll. The intermediate roll is a roll installed between the work roll and the backup roll to transmit the correcting force. The bearing roll is a kind of backup roll often used in a Sendzimir rolling mill and is composed of a plurality of rolls divided in the roll axis direction. The wiper roll is a roll that is provided on the entrance side and the exit side of the steel sheet to and from the work roll to remove foreign substances and the like attached to the steel sheet surface. These rolls are constantly cooled and washed with coolant.However, each roll coolant is not limited to each roll, but flows down or is caught by the rotation of the rolls. Will be involved. Therefore, by controlling at least one or more oil amounts of these roll coolants, the temperature of the work roll can be controlled, and thus the rolling processing temperature can be controlled. As means for controlling the rolling temperature,
A method of controlling the flow rate of the strip coolant between the rolling passes is also conceivable, but a large change in the flow rate of the strip coolant greatly changes the lubricity in rolling, so that the rolling load and the rolling texture vary. In this case, the thickness deviation and the magnetic characteristics are changed, which is not preferable. Therefore, it is recommended that the technique of controlling the flow rate of the strip coolant be used as an auxiliary means in addition to the technique of the present invention.

Generally, in the rolling process, the processing temperature is largely determined by the balance between the amount of heat generated and the amount of heat removed from the roll.
When the rolling speed is changed, it changes greatly accordingly.
However, if the cold rolling in the present invention is adopted,
Since the rolling temperature can be automatically kept constant, the shape and magnetic properties of the steel sheet do not change even if the rolling speed changes.

As equipment for realizing such a cold rolling method, as shown in FIG.
Temperature sensor 1 for measuring the temperature of the steel sheet 5 coming out of the roll bite portion, and a temperature at which a negative feedback signal is transmitted in response to a measurement signal of the temperature sensor 1 so that the signal has a specified constant value. Controller 2 and such temperature controller 2
Characterized in that a flow controller 3 for controlling the amount of oil in the roll coolant 4 based on the signal generated by the controller is provided. Reference numeral 6 denotes a work roll.

Here, the temperature sensor 1 is for measuring the temperature of the steel sheet, and a contact-type thermometer or a radiation thermometer is generally used. The installation location is set to measure the temperature of the upper surface, the lower surface, or both of the steel plates coming out of the roll bite portion. Next, the temperature controller 2 may be used for controlling the temperature of various heat treatments. The coolant oil flow controller 3 is also effective in any of the electric, magnetic, and mechanical systems used for ordinary fluid control.

Next, as the cold rolling mill to which the present invention is applied, any known cold rolling mill is applicable.
As shown in (a), a work roll pair only (2Hi type), a backup roll pair shown in (b) is provided (4Hi type), and an intermediate roll shown in (c) is provided. (6Hi type), a planetary type having a plurality of pairs of backup rolls (d), and a sendzimer type (e). Also, the rolling stand can be applied from a single stand of a reverse type to a tandem type that performs unidirectional rolling.
However, in the case of the reverse type, it is needless to say that the temperature sensors of the steel plate need to be installed on both the exit side and the entrance side.

The cold rolling method of the present invention is intended for cold rolling of grain-oriented silicon steel sheets. The cold rolling equipment is not limited to steel rolling, but may be steel, aluminum, or the like. Widely applicable to roll processing of metals such as titanium. The steel sheet after the final cold rolling is generally subjected to decarburization firing or primary recrystallization firing. The decarburization baking is performed at 750 to 900 ° C. for 60 to 180 seconds in a known wet hydrogen atmosphere.

After that, the steel sheet is subjected to secondary recrystallization and sintering by continuous sintering, or after applying a sintering separating agent, wound up in a coil shape, and subjected to final finish sintering. After the final finishing firing, if it is necessary to increase the insulation resistance, it is coated with an insulation coating to make the product.

[0041]

【Example】

Example 1 A slab of ingot symbol A shown in Table 1 was soaked at 1420 ° C. for 15 minutes, and then formed into a 1.8 mm hot-rolled coil according to a conventional method. The hot-rolled coil was subjected to hot-rolled sheet baking at 1130 ° C. for 60 seconds, pickled, and cold-rolled to a sheet thickness of 0.30 mm by a Sendzimer rolling mill having a work roll diameter of 120 mmφ.

The rolling pass schedule is the first pass 1.35
mm (25% reduction), 0.95mm (30% reduction) in the second pass,
0.65mm on 3rd pass (32% reduction), 0.45mm on 4th pass
(The rolling reduction was 31%), the fifth pass was 0.30 mm (the rolling reduction was 33%), and the sheet was finished to a thickness of 0.30 mm. The coil is divided into two parts, e and f. For the coil of e, an optical fiber radiation thermometer is installed on the roll-out side as an example, and the temperature of the steel sheet is continuously measured so that it matches the set temperature with a temperature controller. A negative feedback signal was sent to the coolant oil flow meter.

The coolant keeps the wiper roll constant,
The flow rate of the coolant to the work roll, intermediate roll and bearing roll was automatically adjusted by a flow controller. At this time, the temperature setting on the rolling exit side in each pass was 155 ° C in the first pass, 185 ° C in the second pass, 201 ° C in the third pass,
The fourth pass was at 215 ° C and the fifth pass was at 95 ° C. Also,
After each rolling pass, while being wound in a coil at a high temperature, the temperature was kept until natural aging until the next reverse rolling pass. In rolling, the rolling speed was gradually increased from 50 mpm to 500 mpm, and when the maximum speed reached 500 mpm, the rolling speed gradually increased.
Rolling was completed by reducing the speed to 0 mpm.

As a comparative example, an optical fiber type radiation thermometer was installed on the entry side of the rolling, the temperature of the steel sheet was continuously measured, and the coolant oil flow rate was adjusted to match the set temperature by a temperature controller. A negative feedback signal was sent to the meter. The amount of the coolant was automatically adjusted by a flow controller with respect to the coolant to the wiper roll, and the amount of the coolant to other work rolls, intermediate rolls, and bearing rolls was reduced as much as possible to be constant. At this time, the temperature setting on the rolling entry side in each pass is 25 ° C. in the first pass and 25 ° C. in the second pass.
146 ° C., 185 ° C. in the third pass, 205 ° C. in the fourth pass, and 195 ° C. in the fifth pass.

After each rolling pass, it is wound into a coil at a high temperature.
Keep it warm until the next reverse rolling pass
Aged naturally. Rolling gradually from 50mpm
Rolling speed increased to 500mpm, reached maximum speed 500mpm
Rolling is completed by gradually reducing the speed to 50 mpm
I let it. After degreasing, these two coils are 850
Decarburization baking for 2 minutes at ℃, Sr (OH)_Two・ 8H_TwoO to 1
%, TiO_TwoOf MgO containing 5% as a separating agent for baking
Then, it was wound in a coil shape and subjected to final finish baking. Last
Finish baked at 840 ° C for 25 hours _Two After holding in, 15 ℃ / h
The temperature was raised to 1200 ° C at the speed of_Twotwenty five %,
H_Two 75% atmosphere, from 1150 ℃ to 1200 ℃ and 1200
H for 10 hours _TwoAtmosphere.

After the final finish firing, the unreacted separating agent is removed,
A tension-imparting insulating coating was baked at 800 ° C. for 1 minute also for flattening and sintering. Each coil is divided into 20 parts in the longitudinal direction, and the magnetic properties, the average thickness (ta) and the thickness difference in the width direction (Δt: the thickness at the center of the coil is subtracted from the thickness at the coil edge 100 mm). Are shown in Table 2.

[0047]

[Table 1]

[0048]

[Table 2]

As shown in Table 2, in the embodiment in which the temperature of the steel sheet on the roll-out side is controlled to be constant for each rolling pass, the magnetic properties and the shape of the steel sheet are extremely excellent, and the improvement effect is remarkable. Example 2 After heating a slab of ingot symbol B shown in Table 1 at 1400 ° C. for 30 minutes, a 4-coil 1.9 mm in accordance with a conventional method.
Hot rolled coil. Each hot-rolled coil was subjected to hot-rolled sheet baking at 1000 ° C. for 60 seconds, pickled, and rolled to 0.62 mm by a four-stand tandem rolling mill.

The first pass of the rolling pass schedule is 1.
40 mm (26% reduction), 1.05 mm for the second pass (25 reduction)
%), 3rd pass 0.80mm (24% reduction), 4th pass
0.62 mm (23% reduction). Of the four coils, the coils g and h are equipped with an optical fiber radiation thermometer on the work roll exit side of each stand, and continuously measure the steel plate temperature,
The temperature controller sent a negative feedback signal to the coolant oil flow meter to match the set temperature. Each coolant keeps the oil amount of strip coolant constant, and the work roll,
The flow rate of the coolant to the intermediate roll and the backup roll was automatically adjusted by a flow controller. At this time, the temperature setting on the rolling-out side in each pass is 95 ° C. in the first pass, 97 ° C. in the second pass, 115 ° C. in the third pass, and 1 in the fourth pass.
26 ° C. The rolled steel sheet was coiled at a high temperature and kept warm to allow natural aging.

Of the four coils, the remaining two coils, i and j, were rolled to 0.62 mm with a constant amount of coolant oil, and the rolled steel sheet was similarly coiled at a high temperature, kept warm, and naturally cooled. Aged. At this time, the temperature on the rolling exit side in each pass is 65 to 107 ° C. in the first pass, and 65 to 115 ° C. in the second pass.
℃, 104-126 ℃ in the third pass, 122-15 in the fourth pass
It fluctuated between 4 ° C.

Next, the four coils g, h, i and j are degreased.
After the intermediate sintering at 1050 ° C. for 40 sec, the second cold rolling was carried out to a final thickness of 0.22 mm by a tandem rolling mill also comprising four stands. The rolling pass schedule is 0.49mm (reduction 21%) for the first pass, 0.38mm (reduction 22%) for the second pass, 0.30mm (reduction 21%) for the third pass, and the fourth pass The eye was 0.22 mm (27% reduction).

Out of the four coils, the coils g and i were installed on the work roll exit side of each stand by installing an optical fiber type radiation thermometer to continuously measure the temperature of the steel sheet and to adjust the temperature to the set temperature by a temperature controller. A negative feedback signal was sent to the coolant oil flow meter. For each coolant, the oil amount of the strip coolant was kept constant, and the flow rate of the coolant to the work roll, intermediate roll and backup roll was automatically adjusted by a flow controller. At this time, the temperature setting on the rolling-out side in each pass was set to 85 ° C. for the first pass, 93 ° C. for the second pass, 102 ° C. for the third pass, and 122 ° C. for the fourth pass. The rolled steel sheet was coiled at a high temperature and kept warm to allow natural aging.

Out of the four coils, the remaining two coils h and j are rolled to 0.22 mm under a constant oil amount of various coolants, and the rolled steel sheet is similarly coiled at a high temperature, kept warm and naturally heated. Aged. At this time, the temperature on the rolling exit side in each pass is 64 to 92 ° C. in the first pass, and 60 to 103 ° C. in the second pass.
℃, 3rd pass 82 ~ 118 ℃, 4th pass 105 ~ 133
It fluctuated between ° C.

After the coil after rolling was degreased, it was subjected to decarburization baking at 820 ° C. for 2 minutes in a humid hydrogen atmosphere to reduce SrSO ₄ to 1%.
%, And TiO ₂ containing 7% of MgO was applied as a refining agent, wound up in a coil shape, and subjected to final finish refining. After final finish ShoJun is held 50 hours at 850 ° C. in N _2, H ₂ 75
%, After raising the temperature to 1200 ° C. in N ₂ 25% atmosphere, with H ₂
It was kept at 1200 ° C. for 5 hours.

After the final finish baking, the unreacted separating agent was removed, and a tension-imparting insulating coating was baked at 820 ° C. for 1 minute also for flattening baking. Each coil is divided into 20 parts in the longitudinal direction, and the magnetic properties, the average thickness (ta), and the thickness difference in the width direction (Δt: the thickness at the center of the coil is subtracted from the thickness at the coil edge 100 mm). Value) was measured. Table 3 shows the average value and the standard deviation.

[0057]

[Table 3]

As shown in Table 3, g, h, and i employing the cold rolling of the present invention have superior magnetic properties and steel sheet shapes as compared with j in the conventional method. In both of the second and third rounds, the coil of g to which the cold rolling of the present invention was applied obtained remarkably excellent results. Example 3 A slab of ingot symbol C shown in Table 1 was heated at 1410 ° C. for 20 minutes, and then formed into a 2.2 mm hot-rolled coil according to a conventional method. After pickling the hot rolled coil, 1.
After rolling to 50mm, soak at 1100 ℃ for 60sec and 45 ℃ / sec
After performing intermediate sintering consisting of mist cooling at a cooling rate of
It was rolled to a final thickness of 0.22 mm by a Sendzimir rolling mill.

The rolling pass schedule for the first pass is 1.
00mm (rolling rate 33%), 0.75mm in the second pass (rolling rate 25
%), The third pass is 0.55mm (reduction rate 26%), the fourth pass is 0.40mm (reduction rate 27%), and the fifth pass is 0.30mm (reduction rate)
25%) and the sixth pass was 0.22 mm (27% reduction). At the time of rolling of the Sendzimer rolling mill, the temperature of the steel sheet on the exit side of the rolling mill is continuously measured by installing a fiber optic radiation thermometer, and the temperature is adjusted with the coolant oil flow meter so that the temperature matches the set temperature with the temperature controller. A return signal was sent. For each coolant, the oil amount of the wiper coolant was kept constant, and the flow rate of the coolant to the work roll, intermediate roll and bearing roll was automatically adjusted by a flow controller. At this time, the temperature setting on the rolling exit side in each pass was 153 ° C in the first pass,
The second pass was 185 ° C, the third pass was 207 ° C, the fourth pass was 226 ° C, the fifth pass was 192 ° C, and the sixth pass was 124 ° C. The steel sheet after rolling in each pass was wound into a coil at a high temperature, kept warm, and naturally aged.

After cold rolling, degreasing is performed under a wet hydrogen atmosphere.
Decarburization baking was performed at 40 ° C. for 2 minutes, and MgO containing 1% of SrSO ₄ and 5% of TiO ₂ was applied as a baking separation agent, wound up in a coil shape, and subjected to final finishing baking. The final finish is 8
After holding in N ₂ at 40 ° C. for 20 hours, 1200 at a rate of 15 ° C./h
It was heated to ℃, N ₂ 25% up to 1150 ° C., an atmosphere of H ₂ 75%, while the retention of and 1200 ° C. 10 hours to 1200 ° C. from 1150 ° C., and an atmosphere of H _2.

After the final finish baking, the unreacted separating agent was removed, and a tension-imparting insulating coating was baked at 800 ° C. for 1 minute also for flattening baking. Then, it is divided into 20 in the longitudinal direction, and the average value and the standard deviation of the measured values of the magnetic properties, the average plate thickness (ta) and the plate thickness difference (Δt) in the plate width direction are shown in Table 4.

[0062]

[Table 4]

[0063]

According to the cold rolling method and the roll cooling apparatus of the cold rolling mill of the present invention described above, a oriented silicon steel sheet having stable and excellent longitudinal magnetic properties and steel sheet shape can be obtained. It becomes possible to manufacture.

[Brief description of the drawings]

FIG. 1 is an actual measurement diagram showing a variation in a thickness of a coil in a longitudinal direction of a coil in various types of cold rolling.

FIG. 2 is an actual measurement diagram showing a change (continuous iron loss) in an iron loss value in a coil longitudinal direction in various types of cold rolling.

FIG. 3 is a graph showing the relationship between tensile strength and material temperature in a tensile strength test.

FIG. 4 is an explanatory view showing one embodiment of the device of the present invention.

FIG. 5 is an explanatory view showing an example of a cold rolling mill to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Temperature controller 3 Flow controller 4 Coolant 5 Workpiece 6 Work roll 7 Intermediate roll 8 Backup roll 9 Bearing roll 10 Wiper roll

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Masataka Yamada 2-88 Wakihama Kaigandori, Chuo-ku, Kobe City, Hyogo Prefecture Kawasaki Steel Corporation Hanshin Works (56) References JP-A-61-132205 (JP, A)

Claims (2)

(57) [Claims] 1. A method for producing a grain-oriented silicon steel sheet, comprising:
When the steel sheet is cold-rolled, the temperature of the steel sheet after rolling out of the roll bite portion of the work roll is measured, and based on the measured value of the steel sheet temperature, cold rolling is performed so as to keep the steel sheet temperature constant. A cold rolling method for a grain-oriented silicon steel sheet, comprising controlling an amount of oil of at least one of a coolant of a work roll, a backup roll, a bearing roll, an intermediate roll, and a wiper roll in a machine. 2. A temperature sensor for measuring the temperature of an upper surface or a lower surface of a steel sheet coming out of a roll bite portion of a work roll, and a signal measured by the temperature sensor so that the signal has a specified value. And a temperature controller for transmitting a negative feedback signal and a flow controller for controlling the flow rate of the roll coolant based on the signal transmitted from the temperature controller.