JPS5842730A - Cooling roll device for metallic strip - Google Patents

Abstract

PURPOSE:To control cooling of a metallic strip easily over a wide range by hollowing cooling rolls, ejecting cooling water from the nozzles provided in the hollow part and cooling the inside wall surfaces of the rolls. CONSTITUTION:A metallic strip 1 is put on around >=1 piece of cooling roll bodies 2, and cooling water is fed forcibly from a tank 13 by a pump 12 and is ejected through a flow rate control valve 11 and a supply pipe 5 out through spraying nozzles 14 toward the inside walls of the roll bodies. The cooling water stuck on the inside wall surfaces of the body 2 in the form of small water drops evaporates to steam by the heat transmitting through the walls of the bodies 2 through the strip 1 and discharges to the outside through an outlet pipe 7 by depriving the walls of the heat of evaporation. The wall temp. of the bodies 2 is detected with a detecting end 9, and the opening of the valve 11 is controlled with a signal converter 10, whereby the wall temp. is maintained at a required temp. The wall temp. is easily controlled over a wide range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in cooling rolls used in steel sheet cooling devices in continuous annealing furnaces, cooling devices in galvanizing lines, and the like.

One method of cooling metal strips in a continuous annealing furnace or the like is to wrap a steel plate 02 around a water-cooled roll 01 having a structure as shown in FIG. 1(a), as shown in FIG. 1(b).
A method is known in which cooling is performed at the contact portion. The number of water-cooled rolls 01 installed can be increased or decreased according to need, but the cooling water is
The cooling water is supplied and discharged through a sliding fitting member 04 attached to the roller 3, and flows through a spiral cooling water passage 06 on the inner wall of the water cooling roll 01, which is rotatably supported by a bearing 05.

However, a drawback of cooling the strip using a water-cooled roll is that the strip is likely to suffer from deformities such as wilting after cooling. The reason is that strips usually have 0.
It is normal for the roof to elongate by around 1% (edge elongation or mid-elongation), and this causes some parts to be in good contact with the water-cooling roll and cooled quickly, and some parts to be in insufficient contact with the water-cooling roll, resulting in wrinkles. This results in defects in shape such as wilting.

The present inventor has previously published ``Method for cooling steel plate using rolls'' (Japanese Patent Application No. 55-97482, Japanese Patent Application No. 55-97483).
proposed. The feature is that for each strip temperature at the time when the contact between the strip and the cooling roll starts, the temperature difference ΔT between the roll temperature and the strip temperature at the start of the contact is kept within a certain temperature difference, thereby preventing shape defects. The point is that it can be suppressed to a level that does not cause any practical problems. Taking a mild steel plate strip as an example, this temperature difference ΔT is as follows.

Strip temperature Temperature difference ΔT (contact start temperature) 300C225C 400〃 20511 500〃 197〃 600〃 184〃 700// 160/1 800〃 115〃 In the case of a water-cooled roll, the temperature of the cooling water flowing inside the roll is 100C or less. Yes, if the strip temperature is high,
There is a drawback that the temperature difference ΔT exceeds the above-mentioned allowable limit, resulting in shape defects.

The present invention was proposed with the aim of eliminating the drawbacks of this water-cooled roll.The inside of the cooling roll is made hollow, and a nozzle for spouting or atomizing cooling water is provided in the hollow part to supply the cooling water. This method is characterized in that the strip is cooled by removing the heat that has passed through the roll wall from the strip through the evaporation of small water droplets that are ejected from the nozzle and adhered to the inner wall surface of the cooling roll.

The present invention will be specifically explained below with reference to embodiments shown in FIGS. 2 and 6. In FIG. 2, 1 is a strip to be cooled, 2 is a cooling roll body having a hollow interior 2a, 6 is a cooling roll bearing, 4 is a cooling water spray nozzle installed in the hollow interior 2a of the cooling roll body 2, and 5 is a cooling water spray nozzle installed in the hollow interior 2a of the cooling roll body 2. The cooling water supply pipe 6 is a sealing device between the supply pipe 5 and the cooling roll shaft. 7 is an outlet pipe for the cooling water vapor evaporated in the hollow interior 2a of the cooling roll main body 2; 8 is a rotary joint for the exit pipe; 9 is a temperature detection end of the cooling roll main body 2; 10 is a signal converter thereof;
1 is a cooling water supply amount regulating valve, 17 is a pump, and 16 is a cooling water tank, and these members are arranged in the relationship shown. Then, the strip 1 is passed around one or more cooling roll bodies 2 provided in a cooling zone on the heat treatment line, and is cooled by removing heat from the contact surface with the cooling roll bodies 2. Cooling water is pumped from a cooling water tank 1 by a pump 12, passes through a flow rate adjustment valve 11, a supply pipe 5, and is ejected from a spray nozzle 4 toward the inner wall of the cooling roll body 2, turning into small water droplets. The strip adheres to the inner wall surface of the cooling roll body 2, and then evaporates into water vapor due to the heat that penetrates the wall of the cooling roll body 2 from the strip 1. It has become. This water vapor is discharged from the hollow interior 2a of the cooling roll body 2 through the outlet pipe 7 to the outside.

In this case, the wall temperature of the cooling roll body 2 is detected by the temperature detection end 9, and the wall temperature of the cooling roll body 2 is detected by adjusting the opening degree of the cooling water flow rate control valve 11 via the signal converter 10. It is designed to maintain the required temperature. That is, by adjusting the amount of cooling water in this way, the amount of evaporative heat taken by the cooling water from the wall of the cooling roll body 2 can be controlled, and the wall temperature of the cooling roll body 2 can be maintained at a desired temperature. ing.

Although the button is not shown, the hollow interior 2a of the cooling roll body 2
The water vapor generated and discharged to the outside through the outlet pipe 7 can be led into water and recovered as hot water, but a pressure control pulp is installed in the outlet pipe 7 to control the internal pressure of the cooling roll body 2. By increasing the amount of heat and recovering it as high-pressure steam, more effective waste heat recovery becomes possible.

Although it is conceivable to use the cooling water spray nozzle 4 that drips water droplets, it is advantageous to uniformly supply the cooling water to the hollow inner wall of the cooling roll body 2 in order to equalize the wall temperature of the cooling roll body. The water spray nozzle 4 may be a swirling type spray nozzle or a so-called fog nozzle that simultaneously sprays a gas such as air.
It is best to use one that can obtain as fine a group of water droplets as possible.

Further, the nozzle 4 and the supply pipe 5 are connected to the cooling roll body 2.
It is more effective to uniformize the temperature of the roll wall by supporting and fixing it externally.

Since the metal strip cooling roll of the present invention has the above-described configuration and function, according to the present invention, (1) it can easily be used over a wide temperature range by adjusting the amount of cooling water supplied; The cooling roll wall temperature can be controlled. In other words, in conventional water-cooled rolls, since cooling water is circulated inside the roll, the roll wall temperature is dominantly influenced by the temperature of the cooling water, and is practically 1000 or less even if the amount of cooling water is changed. By changing the amount of cooling water, the cooling roll of the present invention can control the temperature up to a maximum temperature equivalent to that of the strip to be cooled.

(2) Only water vapor and water droplets exist in the hollow part 2 p- in the cooling roll, so the structure can be simplified compared to those that allow cooling water to flow, the weight can be reduced, and the bearing load and roll drive can be reduced. Power can be reduced.

(3) More effective waste heat recovery is possible. That is, with the conventional cooling roll, the heat taken from the strip can only be recovered as hot water, but with the roll of the present invention, it is possible to effectively recover waste heat as high-pressure steam.

The following practical effects can be mentioned.

[Brief explanation of drawings]

1(a) and 1(b) are schematic explanatory views of a conventional metal strip cooling roll and cooling method, and FIGS. 2 and 6 are schematic explanatory views of the cooling roll apparatus of the present invention. The figure is a longitudinal sectional view, and FIG. 3 is a sectional view taken along the line 1-11I in FIG. 2. In Figures 2 and 6, 1: metal strip, 2: cooling roll body, 3: bearing,
4: Cooling spray nozzle, 5: Cooling water supply pipe, 6: Sealing device, 7: Steam outlet pipe, 8: Rotary joint, 9: Temperature detection end,
10: Signal converter, 11: Cooling water supply amount adjustment valve, 1
2: Pump, 13: Cooling water tank. Figure 1 (α)

Claims (1)

[Claims] In a cooling roll device that cools an IJ tube by bringing a high-temperature metal strip running at a predetermined speed on a continuous metal strip processing line into contact with the outer peripheral surface of a water-cooled cooling roll body, the cooling roll body is cooled. The metal strip is hollow, and has at least one cooling water spray nozzle connected to a cooling water source disposed within the hollow part, so that the metal strip is cooled by the heat of evaporation of the cooling water spouted from the cooling water spray nozzle. A cooling roll device for a metal strip, characterized in that the device comprises: