JPH08174031A - Method for passing strip through hot run table of hot rolling line - Google Patents

Abstract

PURPOSE: To suppress the initial camber and the rear camber by controlling the volume and pressure of the air blown from a nozzle header on the first stage, and controlling the volume and pressure of the air blown from the nozzle header on the second and subsequent stages according to the bound height at the tip part as the metallic strip is advanced. CONSTITUTION: The thickness, the temperature and the shape of the strip 1 are measured on the outlet side of a finish rolling mill 2 by a material sensor 12, and compared with the preset values to output the initial command on the air blowing to an ON/OFF control valve 11a. When the strip 1 is advanced and the bound is detected by a distance meter 13b or 13c on the second or subsequent stage, the volume and pressure of the air blown are determined according to the bound height, and the ON command is outputted to the corresponding ON/OFF control valve 11b or 11c of an air header 7b or 7c to achieve the air blowing. The disturbance to the strip passing quality is suppressed to the minimum to suppress the camber without affecting the temperature of the strip 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip passing method on a hot run table of a hot rolling line.

[0002]

2. Description of the Related Art Generally, in a hot rolling line, as shown in FIG.
As shown in FIG. 1, the metal strip (hereinafter, simply referred to as “strip”) 1 rolled by the finish rolling mill 2 moves on the pinch roll 5 while being cooled to a predetermined temperature on the hot run table 3 including a plurality of table rollers 4. It is generally taken up by the down coiler 6 via the. In the case of a so-called thin material having a plate thickness of 1.8 mm or less, water is not injected about 50 m at the tip of the strip 1 so as not to impair the plate passing property. Further, in the case of an extremely thin strip 1 having a plate thickness of 1.4 mm or less, waving is likely to occur due to the action of air resistance or the like even when no water is injected, and the strip passing speed is limited.

FIG. 3 shows such a defective phenomenon of the strip 1. FIG. 3 (a) shows a tip warp (hereinafter, bound) in which the tip 1a floats up when the plate thickness is thin, for example, 1.8 mm or less. (B) shows a so-called head-breaking phenomenon in which the bound increases and bends in two. Further, (c) shows a so-called waving phenomenon in which the strip 1 is corrugated due to a speed difference between the tip portion 1a and the middle portion 1b of the strip 1.

For this reason, there is a problem that the rolling efficiency is impaired because the strip 1 is decelerated and threaded as described above until the tip portion 1a of the strip 1 is wound up by the down coiler 6. In addition, it is the fact that even if the vehicle is decelerated and passed through the plate, it is not possible to completely eliminate head breaks and waving. Therefore, various proposals have been made in the past as measures against such bouncing, head breakage, and waving. That is, for example, JP-A-4-
Japanese Patent No. 84617 discloses a method in which cooling water is poured from a side spray nozzle in front of a strip passing plate so as to be along the traveling direction of the strip, thereby cooling while preventing waving and head breakage.

Further, in Japanese Patent Application Laid-Open No. 50-7762, a nozzle for blowing a blown horizontal flow and / or blown diagonal flow consisting of a gas or liquid or a mixture thereof to a strip, and a gas or liquid A plate passing device including a supply device for supplying the mixture is disclosed. Further, JP-A-56-33119 discloses that
JP-A-56-567 discloses a method in which the strip is processed and deformed to a shape that enhances the rigidity in the traveling direction by a predetermined length, and the strip is passed.
Japanese Patent No. 15 discloses a strip transport device provided with a traveling vehicle that runs along a hot run table in synchronism with the strip and is equipped with a clamp device that clamps the tip of the strip.

Further, Japanese Patent Laid-Open No. 2-55610 discloses a hot run table having rollers provided with permanent magnets or electromagnets, and Japanese Laid-Open Patent Publication No. 5-123733 discloses a method for sucking and transporting a strip above the roller table. A strip transport device provided with a linear motor is disclosed.

[0007]

Normally, a sensor for controlling the quality of strip thickness, temperature, shape, etc. is arranged on the exit side of the finishing rolling mill. Most of them use a laser, which may cause malfunction due to the influence of cooling water. Therefore, in order to prevent malfunctions, it is common practice not to pour water from the exit side of the finishing mill to the sensor installation location. As a result, the tip portion is bent as described above, and the middle portion is bent due to the duplication. Also, in order to prevent such bouncing and waving, if the spray discharge pressure is increased, overcooling will occur and cooling failure will occur, or the amount of water riding on the strip will increase and impede stripability. There is a drawback of.

However, among the above-mentioned conventional techniques,
When a gas or liquid is uniformly sprayed on the strip as in JP-A-4-84617 and JP-A-50-7762, the effect varies depending on the difference in plate thickness, temperature difference, etc. There is also a problem that problems tend to occur and the effect cannot be exhibited when the plate thickness increases. In addition, JP-A-56-33119
In the case of No. No., if air is constantly blown to the tip of the strip, the tip of the strip that does not bounce is pressed between the table rollers by the force of the air, and the tip of the strip collides with the roller side face and warps and breaks. There is a problem that it occurs. Also, if the air blowing amount is reduced, the effect will not be obtained for the strip that has bounced, and even if the air is blown before the cooling on the delivery side of the rolling mill to suppress the warp, new bounce will occur during cooling. It is impossible to prevent a head break.

In Japanese Patent Laid-Open No. 56-56715, it is difficult to clamp a strip running at a high speed, and if a bouncing has already occurred on the rolling mill exit side, a so-called clamping device is struck. May generate cold coils. Further, in Japanese Patent Laid-Open No. 55610/1990, it is difficult to generate a magnetic force sufficient to attract the bound to the table roller when the bound is already generated on the delivery side of the rolling mill, and a magnetic force sufficient to attract the roller is generated. And there is a drawback that impedes the threading performance when no bounce has occurred.

In the case of Japanese Unexamined Patent Publication No. 5-123733, it is not economical to dispose a linear motor over the entire length above a hot run table of several hundred meters, and it also hinders the maintenance of the line. is not. It is an object of the present invention to provide a strip passing method on a hot run table of a hot rolling line, which solves the problems of the above-mentioned conventional techniques.

[0011]

According to the present invention, when a metal strip is threaded on a hot run table of a hot rolling line, a nozzle header provided with a plurality of nozzles in the width direction of the metal strip is provided in a longitudinal direction of the hot run table. Direction, the air volume and pressure of the air blown from the nozzle header of the first stage is controlled according to the thickness, temperature, shape and bounding height of the metal strip on the exit side of the finishing rolling mill to control the metal strip. The method of passing a hot run table on a hot run table in a hot rolling line is characterized in that the flow rate and the pressure of the air blown from the nozzle header of the second and subsequent stages are controlled according to the bounce height of the tip end of the hot run table. .

[0012]

[Operation] As a result of intensive investigations and studies on the cause of warpage in order to solve the above problems, the present inventor found that the bound of the strip was the initial warpage that occurred near the exit side of the finish rolling mill and the exit of the finish rolling mill. The present inventors have found that there are two types of rearward warpage that occur on the downstream side of the rear side, and have completed the present invention.

That is, the initial warpage occurs in relation to the material temperature, the plate thickness, and the shape, and the rearward warpage occurs due to the tip of the strip colliding with the table roller and bouncing. It has been found. Also, it was found that bounce does not occur due to the relation with the material temperature about 100 m or more from the exit side of the finish rolling mill, so the position where the bounce occurs can be specified to some extent.

4, 5 and 6 show the plate thickness in the initial warp,
The relationship between temperature, shape, and head breakage occurrence rate is shown. First, as can be seen from FIG. 4, with respect to the plate thickness, the smaller the value, the more the head breakage tends to occur. In addition, it has been found that, especially at a plate thickness of about 2.5 to 3.0 mm or more, almost no head breakage occurs. As for the temperature, as can be seen from FIG. 5, the higher the temperature of the strip, the more the head breakage tends to occur, but the frequency is lower than in the case of the plate thickness. Further, as to the shape, as shown in FIG. 6, the better the shape, the more the head breakage tends to occur, but the frequency is lower than the frequency of temperature.

FIG. 7 shows the relationship between the height of the bounce and the air pressing force capable of suppressing the bounce. Here, it has been confirmed from the results of experiments that the relationship between the bounce height and the air pressing force is almost constant for each plate thickness. For example, when the bound height is a, the air volume and / or pressure of the air blown to the strip is increased so as to correspond to that height, and when the bound height is b, the air volume and / or the pressure of air blown are lowered. To do.

The air pressing force is determined by the air volume and pressure of the air, and the pressing force can be adjusted by controlling either one or both, but the adjustment is performed mainly by pressure control. It is easy to do and is preferable.
When the pressing force is adjusted by controlling the air volume, it is easier to control the number of nozzles to be operated, and both may be combined.

As described above, according to the present invention, the nozzle header for spraying a plurality of stages of air provided in the longitudinal direction of the hot run table is selected according to the position of the tip of the strip, and the strip thickness, Temperature, shape,
The amount and / or pressure of the air blown from the nozzle header of the first stage is controlled according to the bound height, and then the nozzles of the second and subsequent stages are controlled according to the bound height of the tip as the strip advances. By controlling the air volume and / or pressure of the air blown from the header, it is possible to suppress the initial warp and the backward warp without affecting the quality of the strip.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention, and the same members as those in the conventional example are designated by the same reference numerals. In this figure, 7a to 7c are air headers arranged on the outlet side of the finish rolling mill 2, and are in the traveling direction of the strip 1, that is, the down coiler 6 of the hot run table 3.
A plurality of stages are arranged toward the side. Although the number of the air headers 7a to 7c is three in this example, it can be increased or decreased depending on the length of the hot run table 3. However, it is not necessary to install it after 100 m according to the above-mentioned findings.

A plurality of nozzles 8 for blowing air to the upper surface of the strip 1 are attached to the air headers 7a to 7c in the width direction of the strip 1, and air supply pipes 9a to 9c.
Air is supplied from the air source 10 via the. Reference numerals 11a to 11c denote on / off control valves attached to the air supply pipes 9a to 9c, respectively, for turning on / off the air supplied to the air headers 7a to 7c.
Turn off or control air volume. The angle of spraying of the nozzle 8 onto the upper surface of the strip 1 is preferably in the range of 0 to 60 ° with respect to the traveling direction of the strip.

Reference numeral 12 is a conventionally used material sensor for measuring the plate thickness, temperature and shape of the strip 1 arranged on the exit side of the finish rolling mill 2, and is a plate thickness gauge, thermometer or width gauge. A combination is used. Reference numerals 13a to 13c are rangefinders for measuring the bounding height of the strip 1. For example, a displacement meter or a combination of a plurality of width meters is used.

Reference numeral 14 is an arithmetic and control unit for preventing the strip 1 from bouncing, which sets preset values for the plate thickness, temperature and shape of the strip 1 in advance, and the material sensor 12
Input the measurement signals of the plate thickness, temperature, and the plate width from the distance meter 13 and the measurement signal of the bounce height of the strip 1 from the distance meter 13, and calculate the air blowing air volume according to the size of those measured values. The on / off control valve 11 is controlled.

Reference numerals 15a to 15c are guides arranged between the table rollers 4 near the air blowing portion, and are strips 1
It has a function of preventing the tip portion 1a of the above from hitting the lower portion of the table roller 4 and bouncing. Therefore, a procedure for controlling the bound of the strip 1 by the arithmetic and control unit 14 will be described below. First, the material sensor 12 measures the strip thickness, temperature, and shape of the strip 1 on the exit side of the finishing rolling mill 2, compares the set values in the following order, and turns on the initial command for blowing air. Output to the off control valve 11a.

A. If the plate thickness is less than 3.0 mm, the initial command for blowing on is output to the on / off control valve 11a of the first stage air header 7a based on the plate thickness information. That is, when the plate thickness is thin, the temperature is high, the shape is good, and head breakage is likely to occur, the bounding height is measured with the first stage distance meter 13a, and the air pressure determined by the relationship in FIG. The amount of air blown and / or the pressure is controlled so as to give force. When the bound height is considerably high, the on / off control valves 11a and 11b of the first-stage and second-stage air headers 7a and 7b are simultaneously turned on to blow a large amount of air at high pressure. And the second rangefinder 13
If the bound height measured in b is 0, the on / off control valve 11c of the air header 7c at the third stage is turned off so that no disturbance is given to the tip portion of the strip 1. If the second range finder 13b detects the bounce height even a little, the on / off control valve 11c of the third stage air header 7c is turned on, and the air volume and pressure corresponding to the height are set. Spray the air.

B. If the plate thickness is 3.0 mm, even if the temperature is high, the shape is good, and head breakage is likely to occur, the blow-off is output to the on / off control valve 11a of the first-stage air header 7a. Next, when the strip 1 advances and the bounce is detected by the rangefinder 13b or 13c at the second stage and thereafter,
The amount and pressure of air blown are determined according to the bound height, and an on command is output to the on / off control valve 11b or 11c of the corresponding air header 7b or 7c to blow air.

Thus, in the non-water-filled region immediately after the exit side of the finish rolling mill 2, the strip thickness, temperature,
The air blowing is controlled according to the shape and the bounce height, and the air blowing is controlled on the downstream side according to the bounce height, so that the temperature of the strip 1 is not affected, and Distortion to the plate property can be minimized to suppress warpage and prevent head breakage.

Nozzle header with 6 nozzles installed
Arranged in 4 stages of 10m, the amount of air blown from each nozzle header is 100 to 300 Nm ³ / min, and the pressure is 0.5 to 1.5 kgf / cm ²
Adjustable to a thickness of 0.5 to 15 mm and a width of 700 to 15
When the method of the present invention was applied to the rolling of 10000 strips of 00 mm / month, the number of head breakages, which had conventionally occurred 700 times / month, could be reduced to about 100 / month.

[0027]

As described above, according to the present invention, it is possible to select a nozzle header, which is provided in the longitudinal direction of the hot run table of the hot rolling line and blows a plurality of stages of air, according to the position of the tip of the strip. The air flow rate and pressure of the air blown from the nozzle header of the first stage is controlled according to the strip thickness, temperature, shape, and bounce height of the strip. The air flow rate and pressure of the air blown from the nozzle headers of the second and subsequent stages is controlled according to the above, so that the initial warp and the rear warp can be suppressed without affecting the quality of the strip. It is possible to prevent the yield from decreasing due to head breakage and increase the strip running speed, which contributes to improving the operating rate of equipment.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram showing a conventional example.

3A and 3B are explanatory views showing (a) bound phenomenon, (b) head breakage phenomenon, and (c) waving phenomenon of the strip, respectively.

FIG. 4 is a characteristic diagram showing the relationship between the plate thickness and the rate of head breakage in the initial warp.

FIG. 5 is a characteristic diagram showing a relationship between a temperature and a head-breakage rate in an initial warp.

FIG. 6 is a characteristic diagram showing the relationship between the shape and the occurrence rate of head breakage in the initial warp.

FIG. 7 is a characteristic diagram showing the relationship between the bound height and the air pressing force.

[Explanation of symbols]

 1 strip (metal strip) 2 finishing rolling mill 3 hot run table 4 table roller 5 pinch roll 6 down coiler 7a to 7c air header 8 nozzle 9a to 9c air supply pipe 10 air source 11a to 11c on / off control valve 12 material sensor 13a to 13c Distance meter 14 Arithmetic control device 15a to 15c Guide

Claims (1)

[Claims] 1. When passing a metal strip on a hot run table of a hot rolling line, nozzle headers having a plurality of nozzles in the width direction of the metal strip are arranged in a plurality of stages in the longitudinal direction of the hot run table, The thickness of the metal strip on the exit side of the finishing rolling mill,
The amount and pressure of the air blown from the nozzle header of the first stage is controlled according to the temperature, shape, and bound height, and the nozzles of the second and subsequent stages are controlled according to the bound height of the tip as the metal strip advances. A strip passing method on a hot run table of a hot rolling line, characterized in that the flow rate and pressure of air blown from a header are controlled.