JPS6310019A - Forced cooling device for thick steel plates - Google Patents

Abstract

PURPOSE:To prevent the generation of a defective shape due to the deflection of a thick steel plate by providing a pair of the upper and lower pressing rolls at least at the specific intervals more than the initial pressing roll of the cooling belt at the upstream side than the cooling belt. CONSTITUTION:The thick steel plate 5 fed by a transfer roll 7 out of a hot rolling mill 6 is fed into a leveller 8 through the cooling belt consisting of the nozzle for jetting a cooling water provided in plural lines in the movement direction and the pressing rolls in plural sets for preventing the deformation. In order to prevent the deflection caused on the thick steel plate 5 of the part abutting to the initial pressing roll 1 a pair of the upper and lower pressing rolls 4 at least to pinch the thick steel plate 5 from the upper and lower parts are provided at the upstream side than a cooling belt 3. The position thereof is taken within the range of 1/8-1/2 of the plate width of the thick plate 5 more than the initial pressing 1a of the cooling belt.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a forced cooling device for thick steel plates for forcedly cooling high-temperature thick steel plates rolled in a hot rolling mill in a germination line without causing distortion. It is related to.

[Prior art and its problems]

Conventionally, as a forced cooling device for high-temperature thick steel plates rolled in a hot rolling mill, the steel plates are guided one by one into a cooling zone.
A simultaneous forced cooling system that sprays water over the entire surface of a thick steel plate to cool it, and a forced cooling system that moves the steel plate at a predetermined speed to a cooling zone and sprays water onto the upper and lower surfaces of the moving steel plate. On-line forced-through cooling devices are known.

Pass-through forced cooling equipment has a shorter cooling zone than simultaneous forced cooling equipment, so the scale of the equipment is smaller, and water can be sprayed intensively onto thick steel plates. , a powerful cooling effect can be obtained. Furthermore, the pass-through forced cooling device has the advantage of being able to control the cooling rate over a very wide range from low to high, thereby providing an appropriate cooling effect.

However, when cooling is performed using a pass-through type forced cooling system, there is a difference in the cooling start time depending on the longitudinal direction of the thick steel plate. The distribution tends to be non-uniform, resulting in distortion of the thick steel plate, resulting in poor shape.

In order to prevent such shape defects that occur during forced cooling using a pass-through forced cooling system, press rolls are installed in the cooling zone to clamp the moving thick steel plate from above and below to prevent deformation. .

FIG. 8 is a side view of a conventional forced cooling device for thick steel plates. As shown in FIG. 8, the conventional device is installed at a predetermined interval in the moving direction of the thick steel plate 5 above and below the high temperature thick steel plate 5, which is installed on the downstream side of the hot rolling mill 6. A plurality of rows of cooling water injection nozzles 2 provided in the plate width direction of the thick steel plate 5, and upper and lower plates provided between the cooling water injection nozzles 2 to sandwich the thick steel plate 5 from above and below to prevent deformation. It has a cooling zone 3 made up of a plurality of pairs of presser rolls 1. 7 is a plurality of transfer rolls provided upstream and downstream of the cooling zone 3 for moving the thick steel plate 5, and 8 is a leveler provided downstream of the cooling zone 3.

The high-temperature thick steel plate 5 rolled by the hot rolling mill 6 is moved in the direction shown by the arrow by the transfer roll 7 and transferred to the cooling zone 3.
guided by. Then, when passing through the cooling zone 3, the upper and lower surfaces thereof are forcibly cooled by water injected from the cooling water injection nozzle 2 while being pressed by the presser roll 1.

The thick steel plate 5 that has been forcibly cooled as described above is guided to the leveler 8, and the strain caused by the forced cooling is transferred to the leveler 8.
corrected by.

However, the large distortion caused by forced cooling cannot be corrected by the leveler 8 alone. Therefore, in order to correct such large distortions, it is necessary to provide a press machine and use the press machine to correct the distortions. This kind of press straightening work takes a long time (2 to 3 hours/
), which causes a decrease in productivity.

Fig. 9 is a side view showing the passing of a thick steel plate in a conventional forced cooling device using pass-through cooling, Fig. 10 is a diagram showing the temperature distribution of a thick steel plate passing through the cooling device of Fig. 9, and Fig. 11 ( A) is a diagram showing the distribution of thermal stress generated in the longitudinal direction of a thick steel plate during cooling, and Figure 11 (b) is a diagram showing the distribution of thermal stress generated in the width direction of a thick steel plate during cooling. It is a diagram.

As shown in FIGS. 9 and 10, the hot steel plate 5 is gradually cooled while passing through the cooling zone 3 and is discharged from the cooling zone 3 at a low temperature. At this time, Fig. 11 (a), (
As shown in b), thermal stress corresponding to the temperature distribution shown in FIG. 10 is generated in the thick steel plate 5. That is, Fig. 11 (
As shown in b), the first presser roll 1a of the cooling zone 3
A certain range of compression occurs at the widthwise central portion of the thick steel plate 5 where it contacts, and a certain range of tension occurs at both sides thereof.

Then, as shown in FIG. 11(b), a certain range of compression occurs in the width direction of the thick steel plate 5 in the portion that contacts the first presser roll 1a.

On the other hand, as shown in FIG. 11(a), a certain range of tension occurs in the center of the thick steel plate 50 in the width direction at the part that contacts the last presser roll 1n of the cooling zone 3, and a certain range of compression occurs on both sides of the thick steel plate 50. occurs. Then, as shown in FIG. 11(b), tension occurs in a certain range in the width direction of the thick steel plate 5 at the portion that contacts the last presser roll 1n.

The above-mentioned length of the compression that occurs at the part that contacts the first presser roll 1a is 1 of the width (W) of the thick steel plate 5, and the length of the tension that occurs at the part that contacts the last presser roll 1n is: It is the same as the width (W) of the thick steel plate 5.

As shown in FIGS. 11(a) and 11(b), the compression that occurs in the thick steel plate 5 in the portion that contacts the first presser roll 1 is caused by the compression that occurs in the portion outside the cooling zone 3 where the presser roll 1 is not provided. This is a major cause of distortion in the thick steel plate 5.

[Purpose of the invention]

Therefore, an object of the present invention is to spray water onto the upper and lower surfaces of a moving thick steel plate to forcibly cool the thick steel plate, without causing deformation of the thick steel plate due to distortion.
The purpose of the present invention is to provide a forced cooling device for thick steel plates.

[Summary of the invention]

This invention includes a plurality of rows of cooling water injection nozzles provided above and below a hot thick steel plate at predetermined intervals in the direction of movement of the thick steel plate in the width direction of the thick steel plate; Force of a thick steel plate having a cooling zone between the water injection nozzles and consisting of a plurality of upper and lower pairs of pressing rolls for holding the thick steel plate from above and below to prevent deformation of the thick steel plate. In the cooling device, at least one pair of upper and lower press rolls that sandwich the thick steel plate from above and below are provided on the upstream side of the cooling zone, and the width of the thick steel plate is 1 of the plate width of the thick steel plate rather than the first press roll of the cooling zone. Further, at least one pair of upper and lower press rolls, which sandwich the thick steel plate from above and below, are provided on the upstream side of the cooling zone. At least one pair of upper and lower press rolls are provided at the beginning of the cooling zone at an interval of 1 length, and on the downstream side of the cooling zone, sandwiching the thick steel plate from above and below. The press rolls are characterized in that they are provided at intervals of a length from - to i of the plate width of the thick steel plate.

[゛Structure of the invention]

From the above-mentioned viewpoint, the present inventors have conducted extensive research in order to develop an apparatus that can forcibly cool a moving, high-temperature thick steel plate without causing shape defects due to distortion. As a result, the present inventors have found that if at least one pair of upper and lower press rolls is installed upstream of the cooling zone within a certain range of distance from the first press roll of the cooling zone, the high temperature thick steel plate can be strained. It has been found that forced cooling can be performed using a cooling zone without causing this. This invention has been made based on the above findings.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a side view showing a first embodiment of the invention.

As shown in FIG. 1, the forced cooling device of the present invention is installed at predetermined intervals above and below a high-temperature thick steel plate 5 in the direction of movement of the thick steel plate 5, which is installed downstream of a hot rolling mill 6. A plurality of rows of cooling water injection nozzles 2 are provided in the width direction of the thick steel plate 5 with space between them, and the thick steel plate 5 is sandwiched between the cooling water injection nozzles 2 from above and below to prevent deformation. A cooling zone 3 consisting of multiple pairs of upper and lower presser rolls 1 for the purpose of It consists of a presser roll 4. 7 is a plurality of transfer rolls provided upstream and downstream of the cooling zone 3 for moving the thick steel plate 5, and 8 is a repeller provided downstream of the cooling zone 3.゛The installation position of the presser roll 4 is determined as follows.

FIG. 2 is a plan view showing the installation position of the pressing roll 4, and FIG. 3 is a plan view showing the area of the compressive stress portion of the thick steel plate 5 in the plate width direction. As shown in FIGS. 1 and 2, the axis Ha of the presser roll 4 installed upstream of the cooling zone 3
r b and the axis c of the first presser roll 1a of the cooling zone 3
The plane a + b + of the thick steel plate 5 surrounded by od and
The area of C+ d is equal to the area of the shaded portion S outside the cooling zone 3 of the compressed portion that occurs in the width direction of the thick steel plate 5 shown in FIG. 3, which prevents the occurrence of distortion. This is a necessary condition for

The distance t1 between the axis a + b of the presser roll 4 installed upstream of the cooling zone 3 and the axis and of the first presser roll 1a of the cooling zone 3 is determined as follows.

The area of a portion S of the compressed portion that occurs in the width direction of the thick steel plate 5, which is outside the cooling zone 3 and is indicated by diagonal lines in FIG. 3, is determined by the following equation.

However, W: Width of the thick steel plate.

A plane a r b t Cr of the thick steel plate 5 surrounded by the axis ayb of the presser roll 4 installed upstream of the cooling zone 3 shown in FIG. 2 and the axis cod of the first presser roll 1a of the cooling zone 3. Since the area of d is t,·W, it follows.

There are necessary conditions to prevent the occurrence of distortion in the board. If tl is less than 1, distortion cannot be prevented from occurring. tl
Even if it is 1 or more, as long as it is within a predetermined range, distortion can be prevented from occurring. The upper limit of such 1t is TW'. When t exceeds =W, the restraint on the thick steel plate 5 is weakened, and strain is likely to occur in the thick steel plate 5. Therefore, t
l needs to be a concave circle of 1 or more and 1 or less.

Therefore, the distance between the position of the presser roll 4 installed upstream of the cooling zone 3 and the position of the first presser roll 1a in the cooling zone 3 is equal to the sheet width W (maximum sheet width under operating conditions). −
It should be greater than or equal to - less than or equal to -.

FIG. 4 is a screen diagram showing a second embodiment of the present invention.

As shown in FIG.
Similar to the apparatus shown in the embodiment, in addition to a pair of upper and lower presser rolls 4a installed upstream of the cooling zone 3, a pair of upper and lower pressers is also installed downstream of the cooling zone 3. A roll 4b is installed.

The installation position of the presser roll 4b is determined as follows. FIG. 5 is a plan view showing the installation position of the presser rolls 4 a + 4 b, and FIG. 6 is a plan view showing the area of the compressive stress portion of the thick steel plate 5 in the longitudinal direction. As shown in FIGS. 4 and 5, the axes g and h of the press roll 4b installed downstream of the cooling zone 3, and the axis e of the last press roll 1n of the cooling zone 3.

The plane of the thick steel plate 5 surrounded by f + h +
The area of e+f is equal to the area of the shaded portion S' outside the cooling zone 3 of the compressed portion that occurs in the longitudinal direction of the thick steel plate 5 shown in FIG. 6, which prevents the occurrence of strain. This is a necessary condition for

The distance t2 between the axes g, h of the presser rolls 4b installed downstream of the cooling zone 3 and the axis elf of the last presser roll 1n of the cooling zone 3 is determined as follows.

The area of the portion S' shown with diagonal lines in FIG. 6, which is out of the refrigeration zone 3 and is out of the compressed portion that occurs in the longitudinal direction of the thick steel plate 5, is as follows:
It is determined by the following formula.゛However, W: Width of the thick steel plate.

A plane g t h of the thick steel plate 5 surrounded by the axes g and h of the presser rolls 4b installed on the downstream side of the cooling zone 3 shown in FIG. 5 and the axis elf of the last presser roll 1n of the cooling zone 3. This is because the area of r e r f is t2·W, and therefore.

That is, t2 is at least one! -W is a necessary condition for preventing the occurrence of distortion in the so-called plate. If t2 is less than 1, the occurrence of distortion cannot be prevented. Even if t2 is greater than or equal to i, as long as it is within a predetermined range, distortion can be prevented from occurring. The upper limit of such t2 is -W. When 4 exceeds 1 W, the restraint on the thick steel plate 5 becomes weaker, and the thick steel plate 5 becomes more likely to be distorted. Therefore, t2 needs to be a concave circle of 1 or more and 1 or less.

Therefore, the distance between the position of the presser roll 4b installed downstream of the cooling zone 3 and the position of the last presser roll 1n of the cooling zone 3 is equal to the sheet width W (maximum sheet width under operating conditions). It should be greater than or equal to i.

Note that the distance between the position of the presser roll 4a installed upstream of the cooling zone 3 and the position of the first presser roll 1a of the cooling zone 3 is the same as that of the presser roll 4 and the presser roll shown in the first embodiment. 1, it should be greater than or equal to i of the plate width W (maximum plate width under operating conditions).

Although the above description has been made regarding the press rolls installed upstream and downstream of the cooling zone, it is desirable that the press rolls installed within the cooling zone are also installed at the same intervals as described above.

The high-temperature thick steel plate 5 rolled by the hot rolling mill 6 is moved in the direction shown by the arrow by the transfer roll 7, and is transferred to the cooling zone 3.
guided by. Then, when passing through the cooling zone 3, the upper and lower surfaces thereof are forcibly cooled by water injected from the cooling water injection nozzle 2 while being pressed by the pressure rolls 1 and 4.

In the above description, one pair of presser rolls 4 are provided on the upstream side or on the upstream and downstream sides of the cooling zone 3, but the number is not limited to one pair, and two or more pairs may be provided.

[Embodiments of the invention]

Next, the present invention will be further explained with reference to Examples.

As shown in a side view in FIG. 7, the apparatus of the second embodiment of the present invention was used to forcibly cool a moving thick steel plate. The maximum plate width W of the thick steel plate 5 is 5 m, and the distance between the axes of the press roll 4a14b and the press roll 1 is (H~-
H) Wm is within the range of 0.625 m to 2.5 m, so this was set to 2 m.

The distance Y from the inlet side to the outlet side of the cooling zone 3 is 20 m.

By the cooling device shown in Fig. 7, the ml to 4 shown in Table 1
A thick steel plate 5 having dimensions of 900° C. was forcibly cooled to 300° C., and the results were investigated. For comparison, Table 1 also shows the results when forced cooling was performed without providing presser rolls 4 on the upstream and downstream sides of the cooling zone 3.

Examples N12, 4 and Comparative Example 1IIl12,4 In the case of thick steel plates with a large ratio of plate thickness to plate width, as in Comparative Example N12.4, it is not possible to force the pressure roll 1 of the cooling zone 3 alone. Shape of thick steel plate 5 after cooling 1st
Although surface defects cannot be prevented, if press rolls 4 are provided upstream and downstream of the cooling zone 3 as in Example Nα2゜4, shape defects of the thick steel plate 5 can be completely prevented. was completed.

〔Effect of the invention〕

As explained above, according to the present invention, when water is injected onto the upper and lower surfaces of the moving thick steel plate to forcibly cool the thick steel plate, it is possible to completely prevent shape defects that occur in the thick steel plate. This brings about industrially useful effects such as improved productivity.

[Brief Description of the Drawings] Figure 1 is a side view showing the first embodiment of the present invention, Figure 2 is a plan view showing the installation position of the presser roll, and Figure 3 is compressive stress in the width direction of the thick steel plate. 4 is a plan view showing the second embodiment of the present invention, FIG. 5 is a plan view showing the installation position of the presser roll, and FIG. 6 is a plan view showing the compressive stress in the longitudinal direction of the thick steel plate. Fig. 7 is a side view showing the embodiment; Fig. 8 is a side view of a conventional forced cooling system for thick steel plates; Fig. 9 is a side view showing the passing of thick steel plates. Figure 10 shows the temperature distribution of the thick steel plate passing through the cooling device in Figure 9, and Figure 11 (a) shows the distribution of thermal stress generated in the longitudinal direction of the thick steel plate during cooling. The figure shown in FIG. 11 (b) is a diagram showing the distribution state of thermal stress generated in the width direction of a thick steel plate during cooling. In the drawings, 1... Holder roll, 2... Cooling water jet nozzle, 3... Cooling zone, 4... Holder roll,
5...Thick steel plate, 6...Hot rolling mill, 7...
...transfer roll, 8...repeller.

Claims (2)

[Claims] (1) A plurality of rows of cooling water injection nozzles provided above and below the high-temperature thick steel plate at predetermined intervals in the direction of movement of the thick steel plate in the width direction of the thick steel plate; Forced cooling of a thick steel plate having a cooling zone provided between injection nozzles and consisting of a plurality of upper and lower pairs of press rolls for holding the thick steel plate from above and below to prevent deformation of the thick steel plate. In the apparatus, at least a pair of upper and lower press rolls that sandwich the thick steel plate from above and below are arranged on the upstream side of the cooling zone so that the width of the thick steel plate is 1 of the width of the thick steel plate, and the width of the press roll is 1. A forced cooling device for thick steel plates, characterized in that the devices are provided at intervals of 1/8 to 1/2 length. (2) a plurality of rows of cooling water spouting nozzles provided above and below the high-temperature thick steel plate at predetermined intervals in the direction of movement of the thick steel plate in the width direction of the thick steel plate; Forced cooling of a thick steel plate having a cooling zone provided between injection nozzles and consisting of a plurality of upper and lower pairs of press rolls for holding the thick steel plate from above and below to prevent deformation of the thick steel plate. In the apparatus, at least a pair of upper and lower press rolls that sandwich the thick steel plate from above and below are arranged on the upstream side of the cooling zone, and the width of the plate is 1 of the width of the thick steel plate rather than the first press roll of the cooling zone. At the end of the cooling zone, at least one pair of upper and lower press rolls are provided at intervals of 1/8 to 1/2 length, and on the downstream side of the cooling zone, sandwich the thick steel plate from above and below. A forced cooling device for a thick steel plate, characterized in that the pressure roll is provided at an interval of 1/8 to 1/2 of the width of the thick steel plate.