JPH06527A - Method for starting injection of cooling water of strip coolant - Google Patents

Abstract

(57) [Summary] [Purpose] Even if water sprinkling is started from a water sprinkling nozzle of a strip coolant during rolling by a hot finish rolling mill, temperature unevenness is prevented from occurring on the surface of the strip. [Structure] An opening / closing control valve 7 having an adjustable opening / closing speed is arranged in a supply pipe 5 for supplying cooling water to a water spray nozzle 4 for strip coolant provided between hot finish rolling mills 2.
Simultaneously with the acceleration of the strip after the tip of the strip 1 is wound around the winder, the opening / closing control valve 7 is opened / closed at a slow opening / closing speed of 5 to 10 seconds in accordance with the acceleration or a set time. [Effect] Since the flow rate of the cooling water gradually increases, it is possible to prevent strip temperature unevenness at the start of cooling water injection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for starting injection of cooling water for strip coolant provided between stands of a hot finish rolling mill.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
In order to maintain the quality of the strip 1 that is the material to be rolled, the strip 1 is provided with a water sprinkling header in order to control the temperature by cooling the strip 1 on the inlet side or the outlet side of the hot finish rolling mill 2. Coolant equipment is installed.

A cooling water supply pipe 5 is connected to each sprinkler header 3, and an on / off valve 6 for turning on and off is arranged in each of the cooling water supply pipes 5. When cooling the strip 1 finish-rolled by the hot finish rolling mill 2, the on-off valve 6 was controlled to spray water from the water spray nozzle 4 provided in the water spray header 3. Watering header for strip coolant 3
When the strip 1 is cooled by spraying water from the water sprinkling nozzle 4 provided in, the strip coolant is used from the tip of the strip 1 to cool the strip 1, and the strip coolant is used from the middle of the strip to cool the strip 1. There is. Particularly recently, there has been a tendency to increase the rolling speed of the strip 1 by the hot finish rolling mill 2 after the tip of the strip 1 is wound around the winder in order to improve the hot rolling efficiency. In this case, naturally, in order to increase the cooling capacity of the strip 1 as the rolling speed increases, the on / off valve 6 is controlled to be opened / closed to increase the cooling capacity from the middle of the strip 1.

[0004]

Conventionally, an on-off valve 6 arranged in the cooling water supply pipe 5 for supplying cooling water to the sprinkler sprinkler header 3 of the strip coolant is turned on / off due to the characteristic of the valve. Since the opening and closing by the method is performed instantly for 1 to 2 seconds, the amount of water sprayed from the water spray nozzle 4 suddenly changes, causing a rapid temperature unevenness on the surface of the strip 1 and causing a thickness deviation, which necessitates the stripping of the strip due to tolerance fluctuations. Is
The yield was being reduced.

Japanese Patent Laid-Open No. 56-114521 discloses a technique of tracking the change between the stands at the time of changing the rolling condition such as changing the plate thickness and changing the strip speed and the water injection amount. . This conventional technique does not change the water injection amount relatively slowly, and cannot be applied to the rapid start-up of water injection, which the present invention is directed to. The present invention has been made in view of the circumstances as described above, and provides a method for initiating cooling water injection of strip coolant capable of gently varying the cooling water supplied to a water spray nozzle provided in a water spray header. The purpose is.

[0006]

Means for Solving the Problems The present invention for achieving the above object includes a method for starting injection of cooling water for strip coolant provided between stands of a hot finish rolling mill,
An opening / closing control valve with an adjustable opening is installed in the strip coolant piping path, and after the strip is wound around the mandrel of the winder and stabilized, the strip is accelerated and an opening command is output to the opening / closing control valve. The method for initiating cooling water injection of strip coolant is characterized by gradually increasing the opening degree of the opening / closing control valve so that the required amount of water is predetermined in accordance with the acceleration of No. 1 or set time.

[0007]

In the present invention, in the strip coolant pipe path,
The on / off control valve is installed with the characteristic that the opening of the valve and the flow rate of the cooling water are almost proportional, and the opening / closing speed of the control valve is set to 5
By controlling to 10 seconds, it is possible to gradually open and close the strip coolant and prevent a rapid temperature change of the strip, which is the material to be rolled.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1. As shown in FIG. 1, the facility of the present invention is mainly different from that of the conventional example shown in FIG. In addition to the opening / closing valve 6, an opening / closing control valve 7 whose opening can be adjusted by adjusting the flow rate of hydraulic pressure is provided in the cooling water supply pipe 5 for supplying water. That is, the opening / closing speed of the opening / closing control valve 7 arranged in the cooling water supply pipe 5 is set to 5 to 10 seconds. The on-off valve 6 that has been conventionally installed is used as usual. The opening / closing control valve 7 can be operated not only by hydraulic operation but also by electric or pneumatic operation.

In the control method according to the present invention, the tip of the strip is wound around a mandrel (not shown) in FIG. 1 to be stable, and an acceleration command is issued to the winder and the hot finish rolling mill 2 while at the same time opening and closing by hydraulic pressure. An ON command is issued to the control valve 7. The opening speed of the opening / closing control valve 7 by gradually increasing the opening may be preset to the required opening in 5 to 10 seconds as described above, or the opening may be controlled in accordance with the acceleration of the strip 1. You may go. The amount of the strip coolant cooling water after the speed increase is determined in advance from the rolling conditions such as finish temperature and rolling speed.

[0010]

As described above, according to the present invention, even if the strip coolant is used to start the sprinkling cooling of the strip during the rolling by the hot finish rolling mill, a sharp temperature on the surface of the strip as in the prior art is used. The unevenness does not occur, and one of the factors causing the sheet thickness deviation is eliminated, and the sheet thickness accuracy and rolling efficiency are improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

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

[Explanation of symbols]

 1 Strip 2 Hot Finishing Rolling Machine 3 Sprinkling Header 4 Sprinkling Nozzle 5 Cooling Water Supply Pipe 6 Open / Close Valve 7 Open / Close Control Valve

Claims (1)

[Claims] 1. A method of injecting cooling water for strip coolant provided between stands of a hot finish rolling mill, wherein an opening / closing control valve having an adjustable opening is provided in a pipe path of the strip coolant, and a strip tip is wound up. At the same time as the strip accelerates after it has been wound around the mandrel of the machine and becomes stable, an open command is output to the on-off control valve to match the strip acceleration or to reach the preset required water amount according to the set time. A method of injecting cooling water for strip coolant, characterized in that the opening degree of the opening / closing control valve is gradually increased.