JP6743606B2 - Cleaning method of temper rolling equipment for hot dip galvanized steel sheet - Google Patents

Description

The present invention relates to a temper rolling equipment and a method for cleaning the temper rolling equipment, which can prevent the occurrence of defects in the steel sheet during the temper rolling.

In a continuous hot-dip galvanized steel sheet production line (CGL), after galvanizing, temper rolling is carried out for the purpose of providing pre-strain, surface adjustment, and shape correction. One of the problems during temper rolling is that the foreign material such as dust gets caught between the roll and the steel plate, causing the roll to dent and the rolled steel plate to have a convex There is a flaw defect that causes a flaw. Conventionally, sprays (spray nozzles) are installed on the inlet side and outlet side of the temper rolling mill to constantly inject water into the rolls of the temper rolling mill to prevent foreign matter from entering between the rolls and to the rolls. A defect countermeasure is performed by preventing foreign matter from adhering (for example, Patent Document 1).

JP, 2003-285114, A

Conventional defect countermeasures are effective against foreign substances that enter from the outside. However, the conventional defect countermeasures against the problem that the flow rate of the spray decreases due to the dirt accumulated inside the spray piping and the problem that the foreign substances mixed in the spray piping are sprayed onto the steel plate. Cannot be applied. When such a problem occurs, there is a concern that the ability to remove foreign substances is lowered and the probability of defects is increased, or that defects caused by foreign substances sprayed are generated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a temper rolling equipment and a method for cleaning the temper rolling equipment that can prevent the occurrence of defects in the steel sheet.

As a result of a study conducted by the present inventors, it is possible to remove dirt inside the spray piping by sending compressed air into the spray piping, which reduces foreign material removal capability and sprays foreign materials onto the steel sheet. As a result, it has been found that the occurrence of defects in the steel sheet can be prevented.

The present invention has been completed based on the above findings, and its gist is as follows.
[1] A temper rolling equipment characterized in that a valve for feeding gas is provided in a pipe for spraying a fluid onto the surface of a work roll.
[2] The method for cleaning a temper rolling equipment according to [1], wherein the flow rate of the fluid is measured with a flow meter, and when the flow rate of the fluid decreases, the valve is opened to spray the fluid. A method for cleaning a temper rolling facility, which comprises feeding gas into a pipe.

According to the present invention, it is possible to prevent the occurrence of defects in the steel sheet.

FIG. 1 is a schematic diagram of a temper rolling equipment which is an embodiment of the present invention. FIG. 2 is an image diagram for determining a threshold value for feeding gas.

The configuration of the present invention will be described below.

FIG. 1 shows a schematic diagram of the temper rolling equipment of the present invention. The temper rolling equipment 1 is equipment for temper rolling the steel sheet S, and includes an upper work roll 2 and a lower work roll 3, an upper backup roll 4 and a lower backup roll 5, and water (fluid) injection. It is composed of sprays 6 and 7.

Further, the sprays 6 and 7 are connected to water for injection (filtered water) via a pipe 8. A flow meter 9, a valve 10, a strainer 11, and a pressure gauge 12 are arranged in this order in the pipe 8. Normally, water that has passed through the strainer 11 is sprayed from the sprays 6 and 7 to the upper work roll 2 and the lower work roll 3 to prevent foreign matter from entering between the rolls and preventing foreign matter from adhering to the roll surface. It works.

The valve 10 is connected to gas. By opening/closing the valve 10, gas can be appropriately fed into the pipe 8.

When dirt accumulates inside the pipe 8, the flow rate of the sprays 6 and 7 decreases. In the present invention, the valve 10 may be opened and the gas may be fed into the pipe 8 when the flow rates of the sprays 6 and 7 decrease. By feeding the gas, it is possible to remove the dirt inside the pipe. As a result, it is possible to prevent the flow rate of the sprays 6 and 7 from decreasing. Therefore, it is possible to prevent the occurrence of defects in the steel sheet without deteriorating the foreign matter removing ability.

The gas fed into the pipe 8 is not particularly limited, and for example, air (compressed air) or an inert gas is preferable.

The flow rate of the spray may be appropriately checked with the flow meter 9. The flow rate of the spray when the valve 10 is opened and the gas is introduced may be appropriately determined according to the equipment specifications. As shown in FIG. 2, it is preferable that the threshold value of the flow rate of the gas is set between the maximum flow rate of the spray and the flow rate at which the foreign matter removing ability is insufficient. The reason why the threshold value is set between the maximum flow rate and the flow rate at which the foreign matter removing ability is insufficient is to reduce the gas feeding frequency as much as possible and to secure a spraying flow rate that constantly satisfies the foreign matter removing ability. Further, the flow rate range of the spray that satisfies the foreign matter removing ability may be appropriately determined according to each equipment.

Note that the flow rate of the spray is reduced and the gas is introduced into the pipe when the product that does not require high surface quality is manufactured. Further, when the gas is sent in, the flow rate of water passing through the strainer 11 is not changed.

Further, in the present invention, the gas may be fed in when the pressure is not adjusted, such as when the roll is replaced. The gas can be fed into the pipe 8 at a stage where the accumulation of the stain in the pipe 8 is slight, and as a result, the stain in the pipe 8 can be removed.

From the viewpoint of removing the dirt in the pipe 8, it is preferable to feed the gas for about 5 to 10 minutes. Since the inside of the pipe 8 is bubbled by the gas, the dirt inside the pipe 8 can be further removed.

Examples of the present invention will be described below.

In a continuous hot-dip galvanized steel sheet production line (CGL), temper rolling was performed on a galvanized steel sheet (sheet thickness: 0.60 to 1.0 mm, sheet width: 800 to 1800 mm).

What was temper-rolled using the temper-rolling equipment shown in FIG. 1 was made into this invention example. The spray flow rate was usually 70 l/min, and when the flow rate was lower than 50 l/min, the valve 10 was opened and compressed air was fed. The compressed air was introduced for 10 minutes.

A comparative example was a case where temper rolling was performed using a conventional temper rolling facility that does not send compressed air.

With respect to the steel sheets obtained in the examples of the present invention and the comparative examples, the downgrading rate (ratio of defective products) was obtained and compared. Specifically, the presence/absence of occurrence of a flaw on the convex skin pass roll pitch was evaluated by a visual inspection on the CGL exit side, and a pass/fail judgment was made. As a result, the rating rate was reduced by 40% in the example of the present invention as compared with the comparative example in which compressed air was not fed.

1 Temper rolling mill 2 Upper work roll 3 Lower work roll 4 Upper backup roll 5 Lower backup roll 6 Spray 7 Spray 8 Piping 9 Flowmeter 10 Valve 11 Strainer 12 Pressure gauge S Steel plate

Claims (1)

A tempering rolling for hot dip galvanized steel sheet, in which a flow meter for measuring the flow rate of the fluid and a valve for feeding gas into the spray piping are provided in the spray piping for spraying the fluid onto the work roll surface. A method of cleaning equipment, characterized in that the flow rate of the fluid is measured by the flow meter, and when the flow rate of the fluid decreases, the valve is opened to introduce gas into the pipe of the spray. Cleaning method of temper rolling equipment for hot-dip galvanized steel sheet.

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