JP3370808B2 - Hot rolled material cooling system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an apparatus for cooling hot-rolled material such as strip by cooling water sprayed from a spray nozzle, which is installed in hot-rolling lines in the ferrous and non-ferrous industries. More specifically, a cooling device for hot-rolled material, which is provided with a cooling water supply tank facility for improving the flow quality of the cooling water to be supplied and controlling the water pressure and water amount of the cooling water to a constant level to achieve uniform cooling. It is about.

[0002]

2. Description of the Related Art For example, in a hot rolling mill such as an iron mill, a steel slab (commonly called a slab) having a thickness of about 200 to 350 mm is generally heated in a heating furnace to a temperature of about 1250 ° C. The rough rolling mill group and the finishing rolling mill group are rolled to a plate thickness of about 1.2 to 25.4 mm. The rolled steel sheet (usually called steel strip) is provided between the finish rolling mill and the coiler from a temperature of about 900 ° C. to a predetermined temperature (700 to 500 ° C.) before being wound by the coiler. It is cooled by cooling devices arranged above and below the table rollers of the runout table.

This cooling device for injecting cooling water is equipped with a header having a cooling water injection nozzle and has a capacity of 500 to 1000.
A steel strip that moves through the plate at a speed of about m / min,
It is a device that continuously cools it to a predetermined temperature with cooling water sprayed from a spray nozzle, and the total length of the device is approximately 2/3 of the length of a runout table of 100 m or more from the finish rolling mill to the coiler. Extends to The cooling device is divided into dozens of control units, and controls the flow rate and discharge timing of the cooling water based on the data such as the temperature and speed of the material, the cooling speed and the heat transfer coefficient. It is like this.

[0004] Recently, steel materials handled in hot rolling mills are increasingly required to be manufactured in the cooling process and to have uniform quality in the width direction and the longitudinal direction.
Therefore, to cope with this, the cooling control method is changed from the winding temperature control that only the winding temperature immediately before the coiler needs to be a predetermined temperature as in the conventional method to the cooling process control that finely controls the entire cooling process. It has moved.

In response to such a situation, cooling equipment is required to have high controllability. Part 1
As one example, a cooling water supply tank device installed near a cooling device has been proposed. When supplying cooling water to the cooling device from a pump installed in a conventional remote water tank, this tank device has a long piping distance, and a branch pipe is to be branched from a thick main pipe. But,
In recent years, the cooling water supplied from the pump was temporarily stored in a tank installed above the machine side in order to reduce the cooling accuracy due to pressure fluctuations and response delays at the cooling water end. This is a technology that employs a method of supplying cooling water from a water supply pipe having the same diameter and the same length as the shortest distance from there to the header (hereinafter referred to as "Prior Art 1").

According to the prior art 1, the above-mentioned problems are almost solved, but the prior art 1 has a facility problem in the tank device itself.

In view of this, Japanese Patent Laid-Open No. 3-249134 discloses a tank cross-sectional area related to the fluctuation of the water level in the longitudinal direction of the head tank, and a water supply pipe for supplying cooling water to the header of the injection nozzle on the tank outlet side. A technique has been proposed that defines the relationship between the inner diameter of water and the water level in the tank (hereinafter referred to as "prior art 2").

[0008]

However, the device of the prior art 2 has the following problems. That is, generally, the cooling water supplied from the pump is 3 to 4 kg / c.
It has a pressure of m ² and a flow velocity of 1-2 m / s. Therefore, as shown in FIG. 3, the tank 2 having a limited size is used.
When the cooling water 7 directly flows into the tank 2, a large amount of bubbles 8 originally mixed with the fluid and bubbles 8 entrained from the atmosphere when flowing into the tank 2 are generated, as shown in FIG. Bubbles 8 are mixed in up to the header water supply pipe 6. This not only worsens the flow controllability,
This causes the cooling capacity itself to be reduced. Therefore, it is necessary to take measures against this bubble.

Further, in the prior art 2, in the relationship between the inner diameter D of the water supply pipe on the outlet side of the tank and the water level H of the cooling water in the tank,
It is proposed that vortices do not occur if D / H is 0.5 or less. However, while this proposal is certainly correct within a certain flow range, it is significantly affected by flow rate changes. For this reason, it is necessary to organize the relationship considering the change in flow rate, but such an attempt has not been made yet.

Accordingly, an object of the present invention is to provide a cooling device for a hot rolled material arranged on a runout table on the exit side of a finishing rolling mill in a hot rolling line, from the upstream of the rolling line where the device is arranged. It supplies cooling water at a constant pressure to any position downstream, and minimizes air entrainment that causes fluctuations in cooling water pressure loss in the drain pipe and shortens the laminar flow length from the cooling water injection nozzle. (EN) It is possible to provide a cooling device for a hot-rolled material that can be prevented as much as possible.

The present invention comprises a tank for storing the cooling water supplied from the cooling water supply source, and a conduit provided between the supply source and the tank, wherein the tank outlet side is cooled. A cooling device for a hot-rolled material, to which a water supply pipe for supplying cooling water to a header of a water injection nozzle is attached, wherein the outlet of the conduit is provided above the tank, and the outlet is A filter having a plurality of holes is provided, and an interference plate is provided below the discharge port substantially horizontally at a position lower than the water level of the cooling water stored in the tank. is there. The outlet is provided at a position 100 to 200 mm higher than the water level of the cooling water stored in the tank, the interference plate is provided at a position 50 to 100 mm lower than the water level of the cooling water in the tank, and The relationship between the inner diameter D of the water supply pipe on the outlet side and the water level H of the cooling water in the tank is expressed by the following formula (D / H) <-0.005Q + 1.8, where D: inner diameter (mm) H of the water supply pipe on the outlet side of the tank: The water level (mm) of the cooling water in the tank Q: The cooling water is provided so as to satisfy the extraction flow rate (m ³ / hr) of the cooling water.

[0012]

The function of the cooling water supply source, for example, the filter provided at the cooling water discharge port of the conduit from the pump, and the interference plate provided so as to be submerged in the cooling water in the tank, allow the cooling discharged from the discharge port. Even if the water falls into the cooling water stored in the tank, a swirling flow does not occur, and the movement of the water in the tank such as stirring and vortexing is suppressed. In addition, large bubbles entrained in the water disperse and are removed.

By providing the outlet of the conduit at a position higher than the water level of the cooling water in the tank and the interference plate at a position lower than the water level so as to be immersed in the cooling water in the tank, the cooling water supplied from the cooling water supply source is cooled. The pressure of about 3 to 4 kg / cm ^{2 of} water can be reduced to 1/10 or less. The preferred arrangement of the outlet of the conduit and the interference plate is such that the height of the outlet is 100 to 200 mm above the water level of the cooling water stored in the tank.
That is, the interference plate is provided at a high position and at a position 50 to 100 mm lower than the water level of the cooling water in the tank. By arranging in this way, the pressure of the cooling water becomes almost zero, and swirling and turbulence of the cooling water in the tank is significantly suppressed.

Next, the relationship between the inner diameter (the same value as the diameter of the discharge hole from the tank) of the cooling water supply pipe communicating with the header having the cooling water injection nozzle on the outlet side of the tank and the water level of the cooling water in the tank will be described.

Bubbles in the cooling water have a change in flow velocity and
It causes increase and fluctuation of pressure loss in the water supply pipe. Then, this causes the laminar length of the laminar flow emitted from the injection nozzle to be shortened or fluctuate.
The first cause of bubble generation is the generation of vortices. As shown in FIG. 4, the vortex 9 entrains air and causes cooling water having bubbles 8. Therefore, it is necessary to prevent this. The generation of the vortex has a deep relationship with the positional relationship between the inner diameter of the water supply pipe on the outlet side of the tank and the water level of the cooling water in the tank. FIG. 2 shows the flow rate of the cooling water extracted from the tank in the vortex-free region (described as “flow rate” in FIG. 2)
And the inner diameter of the water supply pipe on the outlet side of the tank (in Fig. 2, "Drain port diameter"
Is described) / the water level of the cooling water in the tank (in FIG. 2, described as “tank water level”). As can be seen from FIG. 2, the vortex non-generation condition is expressed by the following equation. Vortex non-generation condition: (D / H) <-0.005Q + 1.8, where D: inner diameter of water supply pipe on the outlet side of the tank (mm) H: water level of cooling water in the tank (mm) Q: extraction flow of cooling water ( m ³ / hr)

By satisfying the above conditions, in the cooling device arranged on the runout table provided on the exit side of the finishing rolling mill of the hot rolling line, the cooling water supplied to the upper and lower headers having the injection nozzles is used. Can be controlled to a constant pressure at any position from the upstream to the downstream of the rolling line where is installed, and the fluctuation of the pressure loss of the cooling water in the water supply pipe and the laminar flow from the injection nozzle The inclusion of air, which causes the shortening of the laminar length, is minimized.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a part of a cooling device for hot rolled material according to the present invention. As shown in FIG. 1, the device of the present invention is a cooling device of a type including a tank 2 for storing cooling water. Above the tank 2, a discharge port of a conduit 4 is provided which is piped from a supply source (not shown). The outlet of the conduit 4 is provided with a filter 5 having a plurality of holes. In the tank 2 below the outlet of the conduit 4, an interference plate 1 is horizontally provided at a position lower than the water level of the stored cooling water 7. Further, a cooling water discharge hole 3 is opened at the bottom of the tank 2, and a water supply pipe 6 leading to a header of a cooling water injection nozzle (not shown) is attached to the discharge hole 3.

The outlet of the conduit 4 is provided at a position 100 to 200 mm higher than the water level of the cooling water 7 stored in the tank 2. The interference plate 1 is provided at a position 50 to 100 mm lower than the water level of the cooling water 7 in the tank 2.

The water pressure of the cooling water discharged from the discharge port of the conduit 4 is greatly reduced by the filter 5. Further, the discharged cooling water that has dropped into the tank 2 collides with the interference plate 1. As a result, the pressure held in the discharged cooling water becomes almost 0 (zero). Further, by colliding with the interference plate 1, the flow direction of the discharged cooling water changes from the vertical direction to the horizontal direction. This prevents the generation of the swirling flow in the tank 2, and contributes to the stability of the flow at the time of discharging from the discharge hole 3.

The position of the interference plate 1 should be 50 to 100 mm lower than the water level of the cooling water 7 in the tank 2 as described above. When the interference plate 1 is higher than the water level of the cooling water 7, the cooling water is scattered outside the tank 2 in the tank 2 having a width of about 1 m. On the other hand, even if the position of the interference plate 1 is too low,
That is, in the case of a position lower than the position 50 to 100 mm lower than the water level of the cooling water 7, not only the desired effect cannot be obtained in the above-mentioned operation, but also a swirling flow occurs in the tank 2.

Further, the following relational expression (D / H) <-0.005Q + 1.8 of the water supply pipe inner diameter and water level of the tank, and the extraction flow rate, where D: water supply pipe inner diameter (mm) H on the tank outlet side : Water level (mm) of the cooling water in the tank Q: By satisfying the condition of the extraction flow rate (m ³ / hr) of the cooling water, the cooling water supplied to the upper and lower cooling water injection nozzles is rolled by the device. It is possible to control at a constant pressure without being affected by any position from upstream to downstream of the line, and to cause fluctuations in cooling water pressure loss in the water supply pipe and shorten the laminar length of the laminar flow from the injection nozzle. The air is prevented from being mixed in to a minimum, and high cooling accuracy is obtained.

[0022]

As described above, according to the present invention, the discharge port of the conduit is provided with the porous filter, the interference plate is provided in the water in the tank, the inner diameter of the water supply pipe of the tank and the height of the water level, and By specifying the extraction flow rate, the generation of swirling flow in the tank is prevented, the pressure of the cooling water approaches almost zero, and the large bubbles mixed in the cooling water are dispersed.
It suppresses the movement of water such as stirring water in the tank and generating vortices.
By removing bubbles in the water, the cooling water supplied to the cooling water injection nozzle is controlled to a constant pressure without being affected by any position from the upstream side to the downstream side of the rolling line where the equipment is installed. It is possible to prevent fluctuations in pressure loss of cooling water in the water supply pipe and to prevent air from entering, which causes the laminar length of the laminar flow coming out of the injection nozzle to be minimized, thus achieving high cooling accuracy, thus, Industrially useful effects are provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a part of a hot-rolled material cooling device of the present invention.

FIG. 2 is an extraction flow rate of cooling water in a tank in a vortex-free region,
6 is a graph showing the vortex generation limit from the relationship between the inner diameter of the water supply pipe on the outlet side of the tank / the water level of the cooling water in the tank.

FIG. 3 is a cross-sectional view schematically showing the behavior of cooling water in the tank when there is no interference plate.

FIG. 4 is a cross-sectional view schematically showing a state in which a vortex is generated near a discharge hole in cooling water in a tank.

[Explanation of symbols]

1: Interference plate 2: Tank 3: Discharge hole 4: conduit 5: Filter 6: Water supply pipe 7: Cooling water 8: Bubble 9: Vortex

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Otomo ▲ Taka ▼ Hiro 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Shozo Ikemune 1-chome, Marunouchi, Chiyoda-ku, Tokyo No. 2 Japan Steel Pipe Co., Ltd. (72) Inventor Akira Miyamoto Ichibanchi, Fukuyama City, Hiroshima Prefecture Fukuyama Kyodo Kiko Co., Ltd. (56) Reference JP-A-52-90506 (JP, A) JP-A-5 -278787 (JP, A) JP-A-3-249134 (JP, A) Actually opened 58-196775 (JP, U) Actually opened 63-70993 (JP, U) Actually opened 63-60703 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21B 45/02 B21B 1/00-11/00 C21D 9/52 C21D 9/573 B65D 90/00 F25D 1/00-9/00

Claims (2)

(57) [Claims] 1. A tank for storing cooling water supplied from a cooling water supply source, and a conduit provided between the supply source and the tank, wherein cooling water is jetted on the outlet side of the tank. A hot rolled material cooling device in which a water supply pipe for supplying cooling water to a header of a nozzle is attached, wherein an outlet of the conduit is provided above the tank, and a plurality of outlets are provided at the outlet. A hot rolled material is provided with a filter having holes, and an interference plate is provided below the discharge port substantially horizontally at a position lower than the water level of the cooling water stored in the tank. Cooling system. 2. The discharge port is provided at a position 100 to 200 mm higher than the level of the cooling water stored in the tank, and the interference plate is 50 to 10 higher than the level of the cooling water in the tank.
The relation between the inner diameter D of the water supply pipe on the outlet side of the tank and the water level H of the cooling water in the tank is 0 mm lower, and the following formula (D / H) <− 0.005Q + 1.8, where D: outlet side of the tank 2. The cooling device according to claim 1, which is provided so as to satisfy an inner diameter (mm) of the water supply pipe H: a water level (mm) of the cooling water in the tank Q: an extraction flow rate (m ³ / hr) of the cooling water.