KR101054383B1 - Hot Rolling Process Equipment and Hot Rolling Method for Shape Correction of Hot Rolled Steel Sheets - Google Patents

Abstract

The present invention relates to a hot rolling process device, and more particularly, a hot rolling process device for correcting a shape defect caused by widthwise cooling imbalance of a hot rolled steel sheet, a rolling unit for rolling a slab into a hot rolled steel sheet, and the rolled hot rolled steel sheet. Hot rolling comprising a cooling section for cooling the cooling zone and a roofing section formed in the central portion of the cooling zone, a temperature sensing unit for measuring the widthwise temperature distribution of the hot-rolled steel sheet, and a winding machine for winding the cooled hot-rolled steel sheet. In the processing apparatus, the shape correction for re-rolling the cooled hot rolled steel sheet is arranged between the cooling unit and the winder and adjusts the rolling roll in accordance with a control signal, and the measured width direction temperature distribution and preset standard temperature distribution The shape correction control unit for generating a control signal for correcting the shape of the deformed hot-rolled steel sheet using the difference of.

According to the present invention, since the hot-rolling processing apparatus and the hot-rolling method can correct the shape defects caused by the nonuniform cooling rate in the steel sheet at high speed in the hot state, the shape, material, and productivity of the hot-rolled steel sheet are improved at the same time. The deformation can be prevented. In addition, according to the feedback cooling control signal for adjusting the temperature distribution of the steel sheet to be wound, there is an excellent effect of continuously controlling the shape correction by correcting the difference between the exit temperature distribution of the roofing section and the cooling temperature exit temperature distribution.

Hot rolled steel sheet, hot shape correction, cooling stand, roofing section, high speed cooling, target transformation fraction

Description

Hot Rolling Apparatus and Method for Leveling Hot Strip with High Speed

The present invention relates to a hot rolling process and a hot rolling method for correcting a shape at a high speed against a shape defect caused by widthwise cooling unevenness while securing a target material of a hot rolled steel sheet.

In general, during hot rolling, the slab (slab), which is a hot rolled steel, is rolled, cooled, and wound into a coil to prepare a general coil. In producing such a hot rolled steel sheet, the coil should usually be cooled to a suitable temperature.

1 is a view showing a general hot rolling process system. As shown in the figure, in the hot rolling process system is required to cool the steel sheet 240 to a predetermined temperature while passing through the run out table 200 after the steel sheet 240 is rolled in the finish rolling mill 110 After the mechanical properties are imparted, it is produced as a hot rolled coil type product in the down coiler 300 to complete the hot rolling work.

That is, the hot rolled steel sheet heated in the heating furnace is changed in thickness and width through the final rolling process, and finally cooled in the cooling table 200, and then manufactured in the form of a coil in the winding machine 300.

By the way, the quality of the hot rolled steel during hot rolling is mainly determined by the cooling system, and in order to secure the designed mechanical properties of the steel sheet 240, the transformation phase of the designed steel sheet 240 should be cooled to have an appropriate fraction. A cooling system for cooling the steel plate 240 at a suitable temperature is disposed along the cooling table 200, and in the cooling system, the entrance thermometer 210a and the cooling table 200 exit to measure the temperature of the steel sheet to be cooled at the system inlet. An exit thermometer (e) for measuring the temperature of the steel plate 240 after cooling in the is installed. The cooling system is disposed above and below with the cooling table 200 interposed therebetween, and each part cools the steel plate 240 with air and a water cooling unit 220 for cooling the steel plate 240 by pouring water on the steel plate 240. The air cooling unit 230 is composed of. The water cooling unit 220 and the air cooling unit 230 disposed on the upper and lower portions of the cooling system are respectively divided into cooling banks, and each cooling bank may control a cooling capacity for cooling the steel plate 240. In addition, the cooling system may be configured to include a looper 270, a plurality of thermometers (210b, 210c, 210d) for measuring the intermediate temperature of the looper 270 is arranged, and measures the intermediate temperature of the looper 270 The feedforward or feedback cooling control may be performed, and the roofing section of the steel sheet 240 may be adjusted based on the transformation time required to achieve the transformation fraction of the steel sheet.

After cooling is finished, the steel sheet 240 is produced in the form of a coil in the winder 300, and the coil in the hot state moves to the coil stockyard and is cooled at room temperature, and then uses a shape corrector in the cold state for the coil having a poor shape. Shape correction can be performed.

As described above, in the hot rolling process, cooling unevenness occurs in the width direction due to the difference in the width direction of the cooler in the hot rolling process, and for this reason, a difference occurs when the transformation occurs in the width direction. As such, when the non-uniform transformation occurs in the width direction, the shape defect of the hot-rolled steel sheet occurs due to the transformation organic plasticity (TRIP) phenomenon.

Therefore, in the conventional hot rolling process, since the shape defect is corrected by using a shape corrector in the cold state, it takes 30 hours or more to cool to room temperature in the production process, and a large load is applied when the shape corrector is used after cooling. There is.

Accordingly, an object of the present invention is to provide a hot rolling apparatus capable of correcting a shape of a hot rolled steel sheet in a hot state while satisfying a target transformation fraction of a steel sheet.

In addition, another object of the present invention is to provide a hot rolling apparatus capable of correcting a shape of a hot rolled steel sheet capable of continuously controlling shape correction by correcting a difference in transformation speed.

According to an aspect of the present invention, there is provided a hot rolling apparatus including a rolling unit for rolling a slab into a hot rolled steel sheet, a cooling unit configured to cool the rolled hot rolled steel sheet, and a roofing section formed at a central portion of the cooling stage, and the hot rolled sheet. A hot rolling process apparatus comprising a temperature sensing unit for measuring a temperature distribution in a width direction of a steel plate and a winding machine for winding the cooled hot rolled steel sheet, wherein the rolling roll is disposed between the cooling unit and the winding machine and adjusts a rolling roll according to a control signal. Shape correction unit for re-rolling the cooled hot-rolled steel sheet and a shape correction control unit for generating a control signal for correcting the shape of the deformed hot-rolled steel sheet by using a difference between the measured width direction temperature distribution and a preset standard temperature distribution. do.

The hot rolling method according to another aspect of the present invention is a hot rolling method for winding up by correcting a shape defect of a cooled hot rolled steel sheet, the widthwise temperature distribution of the hot rolled steel sheet measured from the first temperature sensor disposed on the exit side of the roofing section and Generating a control signal for correcting the shape of the deformed steel sheet by using a difference of a preset standard temperature distribution, the temperature distribution measured by the first temperature sensor and the temperature measured by the second temperature sensor disposed at the cooling stand outlet side Compensating the control signal using the distribution to generate a final control signal, and receiving the final control signal to adjust the roll gap size and bender force of the rolling roll to roll the steel sheet.

As described above, the hot-rolling process apparatus and the hot-rolling method according to the present invention can correct the shape defects caused by the non-uniformity in the cooling direction of the steel sheet at high speed in a hot state, thereby preventing permanent deformation, and forming a separate cold shape. The calibration process is unnecessary, saving cost and time, and simultaneously improving the shape, material, and productivity of the hot rolled steel sheet. In addition, there is an excellent effect that can perform a reliable shape correction by correcting the control signal in consideration of the influence of the transformation speed difference.

Hereinafter, a hot rolling apparatus and a hot rolling method according to the present invention will be described in detail with reference to the accompanying drawings.

The hot rolling apparatus according to the present invention includes a rolling unit for rolling the slab into a hot rolled steel sheet, a cooling unit configured to cool the rolled hot rolled steel sheet, and a roofing section formed at the center of the cooling stage, and the width of the hot rolled steel sheet. A hot rolling apparatus comprising a temperature sensing unit for measuring a directional temperature distribution and a winder for winding the cooled hot rolled steel sheet, the hot rolled process apparatus being disposed between the cooling unit and the winder and cooled by adjusting a rolling roll according to a control signal. A shape correction unit for re-rolling the hot rolled steel sheet and a shape correction control unit for generating a control signal for correcting the shape of the deformed hot rolled steel sheet by using a difference between the measured width direction temperature distribution and a preset standard temperature distribution.

2 is a view showing a hot rolling process apparatus according to an embodiment of the present invention. As shown in Figure 2, the hot rolling process of the steel sheet is a rolling unit 100, cooling unit 200, temperature sensing unit 210a ~ 210f, winding machine 300, shape correction 400, shape correction It is configured to include a control unit 500.

First, the rolling unit 100 refers to a slab, which is a rolled material slab heated at a temperature suitable for rolling in a heating furnace (for example, 1100 to 1200 ° C.), as a rough rolling mill and a finish rolling mill (or 'thin rolling mill'). (110, 120) using a hot rolled steel strip (strip) of the desired thickness and width. The rolling mills 110 and 120 are provided with work rolls and back up rolls on both sides, respectively, and adjust the roll gap size by operating a scroll-shaped vertical movement unit using hydraulic pressure. The bender force and the facecross angle of the rolling roll are adjusted. Bender force refers to the force applied to both ends of the work roll in a direction perpendicular to the advancing direction of the steel plate, and the fair cross angle refers to the angle formed by the work rolls rotating up and down of the steel plates placed in parallel and adjusting the bender force. The size of the roll gap is adjusted. That is, the parameter which adjusts the roll gap and bender force of a rolling roll is determined according to the thickness and width of the steel plate preset.

In addition, the cooling unit 200 provides mechanical strength by cooling the steel sheet 240 at a predetermined temperature while passing through a run out table. The cooling method includes a water-cooling cooling method for cooling the steel sheet by supplying water and an air-cooling cooling method for cooling the steel sheet by circulating air to determine the quality of the steel sheet. Therefore, the steel sheet passed through the cooling unit 200 should satisfy the target transformation fraction. The cooling unit 200 includes a cooling zone that performs both a water cooling method and an air cooling method and a roofing section that performs only an air cooling method. The roofing section is formed at the center of the cooling table, and the position of the looper 270 according to the target transformation fraction. Can be adjusted. That is, in the roofing section, the steel sheet passing through the cooling zone, which is the front cooling section, is cooled by the air cooling method, and then the cooling is completed by passing through the cooling section, which is the rear cooling section.

However, in the cooling process, cooling nonuniformity occurs in the width direction due to the difference in the width direction of the cooler, and for this reason, a difference occurs when the transformation occurs in the width direction. As such, when the non-uniform transformation occurs in the width direction, the shape defect of the hot-rolled steel sheet occurs due to the transformation organic plasticity (TRIP) phenomenon. Depending on the shape defect and the shape of the steel sheet passed through the cooling unit 200 has a large three quality. That is, a good quality product with a constant thickness and width satisfying the standard target transformation fraction, a center buckle type in which the center portion of the steel sheet is increased more than the edge, and the center buckle type wrinkles in the center portion, and the edge portion of the steel sheet is the center portion. There is an edge wave type that is relatively more stretched and wrinkled at the edges. In the case of a good product, it is not necessary to correct the shape, but the center buckle type or the edge wave type needs to correct the shape of the steel sheet by rolling a relatively unexpanded portion, which will be described in detail later in the shape correction unit 400.

In the hot rolling process, the cooling method controls the cooling temperature and the cooling rate by analyzing the widthwise temperature distribution of the steel sheets measured by the temperature sensors 210a to 210f. That is, feedforward or feedback cooling control is performed according to the temperature distribution measured by the temperature sensing units 210a to 210f installed at the entrance, exit, and intermediate points of the cooling zone and the roofing section. Accordingly, the shape transformation rate of the steel sheet also becomes different.

The shape correction unit 400 is a device for correcting a bad shape of the steel plate 240 that has been cooled, and is operated according to a control signal of the shape correction control unit 500. Shape correction control unit 500 is formed on the exit side of the roofing section, the first temperature sensor 210d for measuring the widthwise temperature distribution of the steel sheet passed through the roofing section, and formed on the exit side of the cooling stand, the steel sheet passed through the cooling stand The shape correction unit 400 is controlled using the width direction temperature distribution of the steel sheet measured by the second temperature sensor 210f for measuring the width direction temperature distribution of the steel sheet. Here, the second temperature sensor 210f formed on the cooling stand exit side is located in front of the shape corrector 400.

The shape calibration controller 500 controls the roll gap size and the bender force of the rolling roll by using the difference between the width direction temperature distribution measured by the first temperature sensor 210d and the preset standard temperature distribution. The control signal is generated by using the widthwise temperature distribution measured by the second temperature sensor 210f, the widthwise temperature distribution difference measured by the first temperature sensor 210d, and a time delay according to the moving speed of the steel sheet. Is corrected to generate the final control signal. The temperature distribution measured by the first temperature sensor 210d and the second temperature sensor 210f is at least one of a temperature at both edges of the steel sheet and an area from both edges to a quarter of the width of the steel sheet. The temperature of the point is included, and preferably the temperature measured at both edges of the steel sheet, at 1/4 point in width and at 3/4 point. Measuring the temperature distribution at both edges and the temperature distribution at one point each between the two edges and the quarter point of the steel sheet width is shown in FIGS. 3A, 3B, 4A, and 4B, as shown in FIGS. The temperature distribution from the central portion of the steel sheet to the quarter of the steel sheet width is kept constant, while the temperature change from the quarter point of the steel sheet width to the edge of the steel sheet is rapidly changed. It is necessary to select and measure the temperature. When the control signal is generated by adjusting only the temperature distribution measured by the first temperature sensor 210d to adjust the shape correction, precise shape correction is difficult because the influence of the cooling history difference and the transformation history difference of the hot-rolled steel sheet cannot be considered. Therefore, by correcting the control signal in consideration of the distance between the first temperature sensor 210d and the second temperature sensor 210f and the delay time of calculating the moving speed of the hot-rolled steel sheet, the difference in the transformation history of the hot-rolled steel sheet can be corrected. Can be.

3A and 3B illustrate widthwise temperature distributions measured from a first temperature sensor and a second temperature sensor when the shape of the hot rolled steel sheet is a good material.

When the shape of the hot rolled steel sheet is good, the widthwise temperature distribution of the hot rolled steel sheet measured by the first temperature sensor 201d is 90 degrees between the 1/4 and 3/4 points of the width of the steel sheet and the temperature difference between the two edge points. The temperature distribution measured from the second temperature sensor 210f is maintained at a temperature of about 1/4 and 3/4 of the width of the steel sheet and the temperature difference between both edges is about 90 ° C.

4A and 4B illustrate widthwise temperature distributions measured from a first temperature sensor and a second temperature sensor when a shape of a hot rolled steel sheet is a bad material.

If the shape of the hot-rolled steel sheet is poor, the widthwise temperature distribution of the hot-rolled steel sheet measured by the first temperature sensor 201d has a difference in temperature between 1/4 and 3/4 of the width of the steel sheet and between the two edges. The temperature distribution measured from the second temperature sensor 210f is about 占 폚, and the temperature difference between the temperature at the 1/4 and 3/4 points of the width of the steel sheet and the edge points is reduced to about 120 占 폚.

From the experimental results of FIGS. 3A, 3B and 4A, 4B, whether the shape of the hot rolled steel sheet is good or bad and the degree of the defect can be predicted to some extent using the widthwise temperature distribution measured from the first temperature sensor 210d. However, when comparing the difference of the temperature distributions measured from the first temperature sensor 210d and the second temperature sensor 210f (compare FIGS. 3A and 4A), the history of cooling as well as the deviation of the widthwise temperature distribution of the hot-rolled steel sheet are compared. And metamorphosis history can be predicted.

Therefore, precise shape correction is required only by using the widthwise temperature distribution difference measured from the first temperature sensor 210d, the widthwise temperature distribution difference measured from the second temperature sensor 210f, and the delay time according to the moving speed of the steel sheet. Can be.

The shape correction unit 400 adjusts the roll gap size and the bender force of the rolling roll using hydraulic pressure in accordance with the final control signal of the shape correction control unit 500 to roll the steel sheet. In general, since the aspect ratio of the hot rolled steel sheet by rolling is about 1/1000, the ratio of stretching in the longitudinal direction by rolling is large, so that a portion that is relatively less stretched may be increased in the longitudinal direction.

In addition, the hot rolling method according to the present invention is a hot rolling method for winding up by correcting a shape defect of a cooled hot rolled steel sheet, the widthwise temperature distribution of the hot rolled steel sheet measured from the first temperature sensor disposed on the exit side of the roofing section and a predetermined standard Generating a control signal for correcting the shape of the deformed steel sheet using the difference in temperature distribution, using the temperature distribution measured from the first temperature sensor and the temperature distribution measured from the second temperature sensor disposed at the cooling stand outlet side Generating a final control signal by correcting the control signal, and rolling the steel sheet by receiving the final control signal and adjusting a roll gap size and a bender force of the rolling roll.

As described above, the transformation rate of the hot rolled steel sheet passing through the roofing section is adjusted, and the widthwise temperature distribution of the steel sheet measured from the first temperature sensor 210d on the exit side of the roofing section becomes a reference temperature distribution for determining the shape defect. . However, for precise shape correction, the shape correction control signal is corrected in consideration of the temperature measurement time-delay according to the distance between the first temperature sensor 210d and the second temperature sensor 210f and the moving speed of the steel sheet. Thus, the final control signal may be generated in consideration of the influence on the transformation history value and the cooling history difference of the hot rolled steel sheet. That is, the temperature distributions of both edges, one quarter of the width, and three quarters of the hot rolled steel sheets measured from the first temperature sensor 210d and the second temperature sensor 210f are set as variables, respectively. After that, the delay time of both sensors for measuring the temperature of the same point of the steel sheet from the distance between the first temperature sensor 210d and the second temperature sensor 210f and the moving speed of the hot-rolled steel sheet is calculated, and the delay The final control signal is generated by comparing the difference in the widthwise temperature distribution of the steel sheet according to the time difference, correcting the control signal, generating the final control signal, determining the roll gap size of the rolling roll, and adjusting the bender force. Here, the size of the roll gap of the rolling roll is adjusted by moving the vertical position of the rolling roll, and the bender force can be adjusted by differentially applying the force acting on the center portion and the edge portion of the rolling roll.

The embodiments of the present invention are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions. Should be considered to be within the scope of the following claims.

In addition, the drawings shown as an embodiment is reduced or simplified in order to explain the contents of the present invention, the present invention can be variously modified and changed without departing from the spirit or the scope of the present invention.

1 is a view showing a general hot rolling process system.

2 is a view showing a hot rolling process apparatus according to an embodiment of the present invention.

3A and 3B illustrate widthwise temperature distributions measured from a first temperature sensor and a second temperature sensor when the shape of the hot rolled steel sheet is a good material.

4A and 4B illustrate widthwise temperature distributions measured from a first temperature sensor and a second temperature sensor when a shape of a hot rolled steel sheet is a bad material.

[Description of Drawings]

100: rolling section 110: finishing rolling roll

200: cooling unit 210a to 210f: temperature sensing unit

270: looper 300: winder

400: shape correction 500: shape correction control unit

Claims (9)

A cooling unit including a rolling unit for rolling the slab into a hot rolled steel sheet, a cooling unit for cooling the rolled hot rolled steel sheet, and a roofing section formed at a center portion of the cooling unit, and a temperature sensing unit for measuring a temperature distribution in the width direction of the hot rolled steel sheet In the hot-rolling process apparatus comprising a unit, and a winding machine for winding the cooled hot-rolled steel sheet, A shape correction unit disposed between the cooling unit and the winder and re-rolling the cooled hot rolled steel sheet by adjusting a rolling roll according to a control signal; And And a shape correction control unit configured to generate a control signal for correcting a shape of the deformed hot rolled steel sheet by using a difference between the measured width direction temperature distribution and a preset standard temperature distribution. The method of claim 1, And the temperature distribution comprises at least a temperature at both edges of the steel sheet and a temperature at each one of the regions from both edges to a quarter of the width of the steel sheet. The method of claim 1, The shape correction unit adjusts the roll gap size by moving the rolling roll up and down in accordance with a control signal, and adjusts the bender force by varying the magnitude of the force applied to the center portion or the edge portion of the rolling roll to adjust the shape of the hot rolled steel sheet. Hot rolling process characterized in that for calibration. The method of claim 1, wherein the temperature sensing unit A first temperature sensor formed at an exit side of the roofing section; And And a second temperature sensor formed at an exit side of the cooling stand. 5. The method of claim 4, The shape correction controller generates a control signal for adjusting the roll gap and the bender force of the rolling roll by using a difference between the width direction temperature distribution measured by the first temperature sensor and a preset standard temperature distribution, 2. The hot rolling process apparatus of claim 2, wherein the final control signal is generated by correcting the control signal in consideration of the difference in width direction temperature measured by the temperature sensor and the difference in width direction temperature measured by the first temperature sensor. The method of claim 5, The shape correction control unit calculates a delay time of both sensors for measuring the temperature of the same point of the steel sheet from the distance between the first temperature sensor and the second temperature sensor and the moving speed of the hot-rolled steel sheet, the difference of the delay time Hot rolling process characterized in that for generating a final control signal after correcting the control signal by comparing the difference in the width direction temperature distribution of the steel sheet. In the hot rolling method for winding up by winding the shape defect of the cooled hot rolled steel sheet, Generating a control signal for correcting the shape of the deformed steel sheet by using a difference between a width direction temperature distribution of the hot rolled steel sheet measured from the first temperature sensor disposed at the exit side of the roofing section and a preset standard temperature distribution; Generating a final control signal by correcting the control signal using a temperature distribution measured by the first temperature sensor and a temperature distribution measured by a second temperature sensor disposed at a cooling stand outlet; And Rolling a steel sheet by adjusting the roll gap size and the bender force of the rolling rolls by receiving the final control signal. The method of claim 7, wherein generating the final control signal And a distance between the first temperature sensor and the second temperature sensor and a delay time for calculating a moving speed of the hot rolled steel sheet. 8. The method of claim 7, wherein generating the final control signal And a temperature distribution measured from the first temperature sensor and the second temperature sensor includes temperature at both edges, one quarter of the width, and three quarters of the hot rolled steel sheet.

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