CN103042055B - Hot-rolled billet steel rough-rolling descaling method - Google Patents

Abstract

The invention discloses a hot-rolled billet steel rough-rolling descaling method. The method includes the steps: subjecting heated billet steel to a first-procedure rolling; and subjecting the billet steel to subsequent-procedure rolling after first-procedure rolling is completed. A high-pressure water descaling nozzle is arranged at an outlet of a rough rolling machine to descale billet steel discharged from the outlet of the rough rolling machine. The pressing rate of a flat roll of the rough rolling machine is zero during first-procedure rolling and is not zero during subsequent-procedure rolling.

Description

Rough rolling and descaling method of hot-rolled steel billet

technical field

The invention relates to a method for rough rolling and descaling of hot-rolled steel slabs, more specifically, the invention relates to a method for rough rolling and descaling of hot-rolled steel slabs which can improve the surface quality of products.

Background technique

The hot rolling of steel billets usually includes multiple processes such as rough rolling and finish rolling. During the rough rolling process, due to the high temperature of the steel billet, its surface easily reacts with oxygen in the air to form oxide scales. Commonly called scales. This scale will be pressed into the surface of the final product by the rolls during the rolling process, thereby reducing the surface quality of the product.

In order to solve this problem, it is usually necessary to remove the scales on the surface of the billet before rolling.

In recent years, methods of descaling using high-pressure water have been developed. The simple mechanism of high-pressure water descaling is as follows: After the billet is released from the heating furnace, the surface of the oxide scale is sprayed with high-pressure water, and the surface of the oxide scale is locally quenched, resulting in great shrinkage and stress, so that the oxide scale is cracked and separated from the billet . After the impact of high-pressure water flow, the iron oxide scale is peeled off from the surface of the billet, and the purpose of removing the iron oxide scale is achieved.

No. CN101618406A Chinese patent application discloses a method for controlling surface color difference of steel for hot-rolled pickling plates. During the production process, high-pressure water descaling can be carried out at the entrance side of the roughing mill for each pass, and further descaling can be carried out between the stands of the finishing rolling mill, so that the landscape pattern on the surface of the hot-rolled pickled strip can be eliminated Chromatic aberration, improve the surface quality of the product.

However, the problem with the above method is that a group of headers are provided before and after rough rolling, and these headers cannot complement each other due to the different installation angles and the different running directions of the strip. In addition, due to the commonly used descaling at the entrance, once the entrance descaling fails, in the production process of hot-rolled products, using this common rolling process, the The surface oxide scale is pressed into the strip, and the descaling water at the exit of the second pass cannot remove the pressed scale, so that the scale pressed in the first pass remains on the surface of the final product, so it cannot meet the high requirements. Production of surface quality products.

Contents of the invention

One aspect of the present invention provides a method for rough rolling and descaling of a hot-rolled billet, the method comprising the following steps: rolling the heated billet for the first pass; The billets are rolled in subsequent passes. Wherein, a high-pressure water descaling nozzle is arranged at the exit of the rough rolling mill to descale the steel billet leaving the exit of the rough rolling mill. Wherein, in the rolling process of the first pass, the reduction rate of the flat roll of the rough rolling mill is zero, and in the rolling process of the subsequent pass, the reduction rate of the flat roll is not zero.

According to another aspect of the present invention, in the rolling process of the first pass, the steel billet may not be descaled, and in the rolling process of the subsequent passes after the first pass, in the even-numbered passes, the The billet is descaled and rolled, and in odd passes only the billet may be rolled.

According to another aspect of the present invention, in the even-numbered passes in the subsequent passes after the first pass, the flat rolls of the roughing mill can be pressed down and the vertical rolls can be opened, and in the subsequent passes after the first pass In odd-numbered passes, the flat rolls of the roughing mill can be pressed down, and the vertical rolls can be pressed down.

According to another aspect of the invention, during the first pass, the vertical rolls of the roughing mill may be depressed.

Description of drawings

The above-mentioned and/or other objects and advantages of the present invention will become more clear through the following description of the embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram showing the principle of descaling with high-pressure water;

Fig. 2 is a flow chart of a rough rolling descaling method for a billet according to an exemplary embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings, however, these embodiments should be understood in an illustrative sense only, and they should not be construed as limiting the present invention. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

FIG. 1 is a schematic diagram showing the principle of descaling using high-pressure water.

Referring to FIG. 1 , when the heated billet 110 is in contact with air, an oxide scale 120 is formed on the surface of the billet 110 . After the billet 110 leaves the heating furnace, due to the rapid cooling of the iron oxide scale 120 on the surface, a plurality of network cracks 121 are generated on the surface of the iron oxide scale due to the shrinkage of the iron oxide scale 120 . When the steel billet passes through the descaling nozzle (not shown), due to the effect of the high-pressure water flow 130 sprayed from the descaling nozzle, the surface of the iron oxide scale 120 is locally quenched, thereby producing greater shrinkage, and the cracks 121 of the iron oxide scale 120 become larger. become larger and cause partial warping. Under the impact of the high-pressure water flow 130, the dynamic pressure of the high-pressure water in the crack 121 becomes the static pressure of the fluid and penetrates into the bottom of the iron oxide scale 120, so that the iron oxide scale 120 is peeled off from the surface of the steel billet 110 to remove the iron oxide scale 120, Therefore, the purpose of descaling can be achieved by high pressure water.

According to an embodiment of the present invention, the high-pressure water descaling method described with reference to FIG. 1 can be used to descale a steel billet. In one embodiment, the first pass of rolling is performed on the heated steel billet, and then, after the first pass of rolling, the steel billet is subjected to subsequent passes of rolling. Wherein, a high-pressure water descaling nozzle is arranged at the exit of the rough rolling mill to descale the steel billet leaving the exit of the rough rolling mill. According to an embodiment of the present invention, during the rolling process of the first pass, the reduction rate of the flat roll of the roughing mill is zero, and during the rolling process of the subsequent pass, the reduction rate of the flat roll is not zero . However, the present invention is not limited thereto. For example, in the rolling process of the first pass, vertical rolls may be used to roll the billet.

More specifically, in one embodiment of the present invention, during the rolling process of the first pass, the billet may not be descaled. In other words, in the rolling process of the first pass, the steel billet is neither rolled nor descaled, but the steel billet is directly passed through the roughing mill.

In the subsequent rolling process after the rolling of the first pass, the steel slab is descaled and rolled in the even-numbered passes, and only the steel slab is rolled in the odd-numbered passes. In one embodiment of the invention, even-numbered rolling can be achieved by passing the billet through the roughing mill in reverse. In this case, the high-pressure water descaling nozzle installed at the exit of the roughing mill can be used to complete the descaling of the billet.

Exemplary embodiments of the present invention will be described in more detail below with reference to specific examples of the present invention. Fig. 2 is a flow chart of a rough rolling descaling method for a billet according to an exemplary embodiment of the present invention.

Referring to FIG. 2 , a rough rolling descaling method for a billet according to the present invention may be performed by using a rough rolling mill provided with a high pressure water descaling nozzle at the exit. When the heated billet enters the roughing mill, the billet is rolled in the first pass. During the rolling process of the first pass, the reduction rate of the flat roll is kept at zero, and the billet is rolled by the vertical roll at the same time. rolling.

Then, the steel billet is rolled for the second pass. Wherein, before the rolling of the second pass, the steel billet is subjected to descaling treatment. The rolling of the second pass can be realized by passing the steel billet through the roughing mill in reverse. In this case, the descaling of the steel billet can be completed by using a high-pressure water descaling nozzle arranged at the exit of the roughing mill. Then, the billet is rolled with flat rolls (that is, the reduction rate of the flat rolls is not zero), while the vertical rolls are opened.

Next, the steel billet is rolled for the third pass. Wherein, in the third pass, the billet is rolled by using the flat roll and the vertical roll simultaneously (that is, the reduction rate of the flat roll and the vertical roll is not zero).

Next, the steel billet is rolled for the fourth pass. Wherein, before the rolling of the fourth pass, the steel billet is subjected to descaling treatment. The rolling of the fourth pass can be realized by making the steel billet pass through the roughing mill in reverse. In this case, the descaling of the steel billet can be completed by using a high-pressure water descaling nozzle arranged at the exit of the roughing mill. Then, the billet is rolled with flat rolls (that is, the reduction rate of the flat rolls is not zero), while the vertical rolls are opened.

Next, the billet is rolled for the fifth pass. Wherein, in the fifth pass, the steel slab is rolled by the flat roll and the vertical roll simultaneously (that is, the reduction rate of the flat roll and the vertical roll is not zero).

Next, the billet is rolled for the sixth pass. Wherein, before the rolling of the sixth pass, the steel billet is descaled. The rolling of the sixth pass can be realized by making the steel billet pass through the roughing mill in reverse. In this case, the descaling of the steel billet can be completed by using a high-pressure water descaling nozzle arranged at the exit of the roughing mill. Then, the billet is rolled with flat rolls (that is, the reduction rate of the flat rolls is not zero), while the vertical rolls are opened.

Next, the billet is rolled for the seventh pass. Wherein, in the seventh pass, the steel slab is rolled by the flat roll and the vertical roll simultaneously (that is, the reduction rate of the flat roll and the vertical roll is not zero).

Although seven passes are included in the slab rough rolling dephosphorization method shown in FIG. 2 , the present invention is not limited thereto. Depending on the properties of the steel and the actual conditions of the final product, more or fewer passes can be used for rolling.

According to the billet rough rolling descaling method of the present invention, the outlet descaling water can be used to knock off the oxidized iron scale produced in the rough rolling descaling box before the rough rolling mill, thereby solving the problem of rough rolling flat due to no inlet descaling The scale is pressed into the billet by rolling down. Utilizing the method of the invention, special products (that is, products with high requirements on surface quality and difficult descaling) can be produced normally, and the surface quality is normal.

Although in the above-mentioned embodiment of the present invention, the high-pressure water descaling nozzle is only arranged at the exit of the rough rolling mill, the present invention is not limited thereto, and those skilled in the art should understand that the present invention can be applied at the entrance and exit of the rough rolling mill In the rough rolling mill equipped with high-pressure water descaling nozzles. In this case, when the high-pressure water descaling nozzle at the entrance of the rough rolling mill is damaged or cannot be opened or is not expected to be opened due to other reasons, the method according to the present invention can be used for descaling and rolling of the steel billet.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, those skilled in the art should understand that various modifications and changes can be made to these methods without departing from the spirit and scope of the present invention. The scope is defined by the claims and their equivalents.

Claims (3)

1. A hot-rolled billet rough rolling descaling method, the method may further comprise the steps: Rolling the heated billet for the first pass; After the first pass of rolling, the steel billet is rolled in subsequent passes, Wherein, a high-pressure water descaling nozzle is provided at the exit of the rough rolling mill to descale the billet leaving the exit of the rough rolling mill, and no descaling is performed at the entrance of the rough rolling mill, Wherein, in the rolling process of the first pass, the reduction rate of the flat roll of the roughing mill is zero, and in the rolling process of the subsequent pass, the reduction rate of the flat roll is not zero, Wherein, in the rolling process of the first pass, the steel billet is not descaled, and in the rolling process of the subsequent passes, the steel billet is descaled and rolled in the even-numbered passes, and descaled in the odd-numbered passes. In this case, the billet is only rolled without descaling. 2. The method for rough rolling and descaling of hot-rolled steel slabs as claimed in claim 1, wherein, in even passes, the flat rolls of the roughing mill are pressed down, and the vertical rolls are opened, and in odd passes, the flat rolls of the roughing mill are pressed Down, the vertical roller presses down. 3. The method for rough rolling and descaling of hot-rolled steel slabs according to claim 1, wherein, in the first pass, vertical rolls of the rough rolling mill are pressed down.