JP3389358B2 - Hot run table passing method for hot finished rolled steel strip - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot run table passing method for a hot finished rolled steel strip. [0002] A steel strip after hot finish rolling is cooled by spraying cooling water onto the steel strip while passing the sheet through a hot run table, controlled to a winding temperature, and transferred to a winding machine. The tip of the steel strip coming out of the rolling mill is deformed to an upward angle, and when the hot strip is cooled and passed at a passing speed of 600 to 800 m / min, the tip of the steel strip is The upward deformation of the portion generates lift due to air resistance, and the steel strip rises above the hot run table, so that propulsion is lost and a flying phenomenon occurs. When the flying phenomenon occurs in the steel strip in this manner, there is a possibility that flaws are generated, and the sheet passing speed is reduced, and flaws are generated due to occurrence of a defective winding shape due to narrowing in the winding machine. It can be difficult. [0003] In view of the above, a steel strip discharged from a hot finishing mill is passed through while being pressed against a hot run table by spraying water from above, thereby suppressing the occurrence of a flying phenomenon. Japanese Patent Application Laid-Open No. 3-226306 discloses that the above-mentioned drawbacks can be solved by winding on a winding machine. However, in the hot run table passing method for a steel strip after hot finish rolling as described above, the steel strip is subjected to water injection pressure over substantially the entire length of the hot run table. Because it passes through the sheet while pressing it upward, it becomes difficult to control the temperature of the steel strip after hot finish rolling.
Variations occur in the coiling temperature of the steel strip, and the quality of the product obtained from the steel strip is adversely affected, such as the occurrence of variations in the material such as strength and formability and the occurrence of distortion. In addition, the hot run table is generally composed of a roller table, and the tip of the steel strip protrudes between the rollers during threading, and the length of the steel strip undulates, damaging the sprinkler on the hot run table. However, there is a problem that the operation may be stopped by jumping out of the table.
The method of the present invention has been made to solve such problems advantageously, and corrects the tip of a steel strip after hot finish rolling so that it does not stick between the rollers of a hot run table. An object of the present invention is to provide a hot run table passing method for a steel strip that can increase the speed and increase the productivity. [0005] To solve the above-mentioned problems,
The present invention has been made, between the final rolling stand for hot finish rolling and the hot run table connected to the exit side, a steel strip angle correction table that prevents the plunge of the steel strip tip is interposed , The tip of the rolled steel strip protruding from the rolling stand is provided on the steel strip angle correction table by an injection nozzle.
Press by the fluid pressure from the upper ejected downward from nozzle
In addition, the tip angle is corrected to be within 15 degrees upward , and the hot run table is passed while controlling the cooling. For example, when a steel strip having a thickness of 1.2 mm (final temperature: about 900 ° C.) after hot finish rolling is passed through a hot run table, flying occurs in about 50% of the steel strip. The board is unstable. That is, as shown in FIG.
When rolling on a hot run table (not shown) after rolling on the final rolling stand 2 of the hot finishing mill, the higher the sheet passing speed, and the more the projecting angle θ of the steel strip 1 from the final rolling stand 2 becomes. As the resistance increases, the air resistance increases, and the lift and the drag of the steel strip 1 increase. [0007] From the above, the present inventors have conducted various studies through actual operations and the like, and as a result, in the hot-rolled steel sheet (band),
Even when a relatively thin steel strip with a thickness of 1.2 mm is used and the threading speed is about 600 m / min, safe threading is possible when the steel strip pop-out angle θ of the final rolling stand is within 15 degrees upward and the thickness is 1.2 mm.
The rigidity gradually increases as the thickness increases, or the hot deformation resistance of the steel strip increases due to an increase in the C content in the steel strip, so that flying becomes less likely to occur and the passing speed is increased. Confirmed that it can be quick. Further, if the steel strip pop-out angle θ is set to an upward angle of 15 degrees or less as required to suppress the drag and suppress the occurrence of flying, the sheet passing speed can be further improved. If the steel strip projection angle θ is corrected horizontally, it will pass through while colliding with the roller of the hot run table, and will bend downward and thrust between the rollers. It is necessary to correct upward the steel strip projection angle θ because it is not preferable because the upper limit of the steel strip projection angle θ is upward.
Must be within 15 degrees. The reason for this is that if the angle exceeds 15 degrees upward, the flying phenomenon is likely to occur when the strip speed exceeds about 650 m / min, and the strip becomes unstable and the strip speed is reduced. This is because productivity is lowered, which is not preferable. [0008] A steel strip of a material that easily causes flying, that is, a steel strip whose pop-out angle θ tends to exceed 15 degrees upward, has a finishing temperature of about 800 ° C. in hot finish rolling, and a high temperature finish. There are C-Nb-Ti steel strips with a thickness of 2.8 to 3.2 mm, thin steel strips with a thickness of 0.8 to 1.6 mm and low C-Al-K steel strips, etc. It does not reach the angle at which flying occurs. Therefore, for example, a hot run table is passed through a steel strip of a material that easily causes the above-described flying by a means such as described later, and the flying is prevented, whereby the operation management of the entire hot rolling process can be reliably performed. . Means for correcting the projecting angle of the final rolling stand in hot finish rolling upward to within 15 degrees is, for example, a final rolling stand for hot finish rolling and a hot run connected to the exit side thereof. About 5m between the table
A steel strip angle correction table is provided in the part, and the upward end of the steel strip protruding from the final rolling stand is corrected upward from the upper part by 15 degrees on the steel strip angle correction table by fluid pressure, Thereafter, the sheet may be passed to the winding machine while performing cooling control on the hot run table without performing correction by fluid pressure. If the steel strip angle correcting table is longer than about 5 m, it may be difficult to adjust the material by controlling the cooling of the steel strip in the hot run table, which is not preferable. Steel strip temperature after hot finish rolling (finish temperature) is 700
To 950 ° C. and have been softened by the red heat state, adding the above as the final rolling stand delivery fluid within about 5m from the side pressure, such as water, fluid impact pressure of the fluid at 7 to 20 kg / cm ² of steam etc. Thus, the tip portion of the steel strip can be easily straightened upward within 15 degrees. The straightening distance of the steel strip tip by the fluid pressure on the final stand exit side of the hot finishing mill may be appropriately set according to the chemical composition of the steel strip, the size of the steel strip, and the fluid pressure. It is desirable that the length be 1 m or more. [0010] As described above, the steel strip angle straightening table interposed between the exit side of the final rolling stand of the hot finish rolling and the hot run table within about 5 m, upward of the tip of the steel strip running out of the final rolling stand and running. Angle correction is performed by pressing down with fluid pressure from the top and correcting it.
Instantly, the tip of the steel strip is pressed by the roller of the steel strip angle correction table and deforms horizontally, and when the pressing by the fluid pressure is released, it can be corrected upward within 15 degrees by elasto-plastic deformation. it can. As described above, the tip of the steel strip is pressed from above with the fluid pressure and straightened, so that the tip of the steel strip is momentarily pressed against the rollers of the steel strip angle correction table. It is difficult to hot run the steel strip between the rollers if it is located at
As described above, the distance between the exit of the final rolling stand and the hot run table is about 5 m or less, for example, as a steel strip straightening table having a structure in which the distance between rollers of a plate-shaped table, a disc roll table or a hot run table is narrowed. Between the rollers. Next, an example of the method of the present invention will be described with reference to the drawings. In FIG. 1, a steel strip straightening table 4 composed of a disc roll is provided within about 5 m immediately downstream of a final rolling stand 3 of a hot finishing rolling mill. The tip of the rolled steel strip 1 protruding from the steel strip 1 is sprayed with a fluid 6 such as water by a downward spray nozzle 5 to correct the upward angle of the tip of the steel strip 1 upward within 15 degrees, and then moved to the hot run table 7. Then, the hot run table 7 is passed while being cooled. Next, examples of the method of the present invention will be described together with comparative examples. [Table 1] Note 1: Rolling temperature is hot finishing rolling temperature. Note 2: Straightening distance is the straightening distance of the tip of the steel strip due to fluid pressure on the exit side of the final stand in hot finish rolling. Note 3: Fluid pressure is the steel strip collision pressure when water is injected from the top of the steel strip tip. Note 4: Steel strip component AC: 0.003%, Si: 0.01%, Mn: 0.35%, P: 0.008%, S: 0.0
02%, Ti: 0.008%, Nb: 0.02%, Al: 0.035%, N: 0.003
%, Remaining Fe and unavoidable impurities. Steel strip component B C: 0.04%, Si: 0.02%, Mn: 0.36%, P: 0.009%, S: 0.004
%, Al: 0.077%, N: 0.0056%, remaining Fe and unavoidable impurities. Note 5: Correction angle is upward angle. Note 6: The pop-out angle is the upward angle of the tip of the steel strip that protrudes after rolling the final stand of the hot finishing mill. Note 7: The passing condition is determined to be good if there is no flying on the hot run table and there is no trouble in passing, and the winding is normally performed.
Since the speed was reduced from 800m / min to 600m / min, it was determined to be defective. According to the method of the present invention, since the angle of the tip of the steel strip after hot finish rolling can be accurately corrected, the steel strip can be passed without flying with a hot run table. In addition, the tip portion can be properly wound during winding, and can be wound normally, and the yield and quality of the hot-rolled steel strip can be improved. Further, since it is possible to reliably prevent biting or the like at the time of flying or winding, an excellent effect such as an improvement in productivity by increasing a sheet passing speed in a hot run table can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of the method of the present invention. FIG. 2 is a schematic side view showing a flying phenomenon of a steel strip.

Continuation of the front page (56) References JP-A-50-7762 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 39/12 B21B 15/00 B21B 39/00

Claims (1)

(57) [Claims] [Claim 1] A steel strip tip is provided between a final rolling stand for hot finish rolling and a hot run table connected to the exit side thereof.
With the steel strip angle correction table preventing the end plunging interposed , the leading end of the rolled steel strip protruding from the final rolling stand is lowered from the injection nozzle provided on the steel strip angle correction table.
The hot run table is pressed down by a fluid pressure from the upper part which is jetted in the right direction, the tip angle is corrected to be within 15 degrees upward , and the hot run table is passed while controlling the cooling. Hot run table passing method for finished rolled steel strip.