KR100787584B1 - Method for optimization of bar moving speed by bar situation descaling header division use - Google Patents

Abstract

The present invention prevents scale defects at the tip of the coil by optimizing the use pattern of the descaling header and the moving speed of the bar, which is a facility for removing the oxidation scale generated on the surface of the rolled bar in a rough rolling mill with high pressure cooling water during the hot rolling process. In addition, the present invention relates to a method of optimizing bar progression speed by using a descaling header according to the position of the bar so as to secure the exit temperature of the strip rolling mill to prevent material defects.

In particular, the number of descaling headers used during the rolling of the hot-rolled material is used before and after the front end, and after the front end of the bar passes the follow point, only one row is used. It is characterized by advancing the speed of the descaling header passing through the bar as fast as possible without causing a collision with the first finishing mill.

Bars, Descaling Headers, Bar Cutters

Description

Method for optimization of bar moving speed by bar situation descaling header division use}

1 is a process chart showing the flow chart of the rolling method for the bar speed control and the number of descaling header using the bar progress speed optimization method using the location-specific descaling header classification bar of the present invention,

FIG. 2 is a graph illustrating a speed pattern of bars in a desqueling zone by a method for optimizing bar progression speed by using a descaling header classification for each bar of the present invention; FIG.

Figure 3 is a graph showing the recuperation time of the bar surface temperature after the deskeling injection by the method of optimizing the bar progression speed by using the decelerating header classification according to the position of the present invention,

Figure 4 is a graph showing the distribution of degradation of the bar surface and the direct temperature by the method of optimizing the bar speed through the use of the decelerating header classification according to the position of the present invention,

5 is a graph showing the temperature change of the tip and the tail end on the basis of the deskelling passing time by the bar progress speed optimization method using the location-specific deskeling header classification of the bar ,

6 is a graph showing the temperature change of the tip of the bar according to the number of descaling headers and the bar speed by the method for optimizing the bar progression speed by using the descaling header classification according to the position of the present invention;

FIG. 7 is a graph illustrating an example of a location of a follow point by a method of optimizing bar progression speed by using a decelerating header classification for each bar of the present invention; FIG.

8 is a schematic diagram showing a finishing rolling process during hot rolling;

9 is a photograph showing a width direction temperature distribution of a bar according to the number of descaling headers;

10A, 10B, and 10C are graphs and photographs showing the relationship between the exit temperature and the material during rolling of a thin material.

<Description of the symbols for the main parts of the drawings>

10: bar 13: descaling header

13a, 13b: before and after row 16: bar cutter

19: rolling mill 20: work roll

25: Following point 27: Bar detector

The present invention relates to a method of optimizing bar progression speed by using a descaling header according to the position of the bar. More particularly, the oxidation scale generated on the surface of the rolled bar in the roughing mill during the hot rolling process is removed with high pressure cooling water. equipment of di-scaling by optimizing the process speed of the usage pattern and the bar of the header to prevent the front end scale defects in the coil to secure the spirit mill outlet temperature of the strip by the position of the bar which in order to prevent the leading end material defects di scaling header A method of optimizing bar progression speed through segmentation .

In general, in the hot rolling process, each rolling (rough rolling, finishing rolling) pass process and the process of proceeding to the next pass, as shown in FIG. 8, the scale of oxidation generated on the surface of the bar 10 due to contact with air is shown. The descaling header 13 of high pressure (150 kg / cm 2) is used to remove the pressure, the number of headers, the header height, the width of the nozzle pitch, and the like in the process. It is automatically designed in the upper calculator (not shown) for each characteristic.

At this time, the descaling operation when the rough rolling (not shown) process and the finishing mill (19) pass process is a matter that is directly connected to the quality of the product may be a particularly important process.

In the conventional operation method, however, the number of descaling headers 13 used from the front end to the end of the bar 10 is always used by the front row 13a and the rear row 13b, and the front row and the rear row. It has been used in three kinds.

This means that injecting the descaling header 13, it is determined that steady spraying should always be performed at the same pressure, so that the calculation itself is not displayed, and there is no significant problem in use.

Therefore, using the header pattern selected as the setting of the calculator as it is, the moving speed is increased until the tip of the bar 10 passes through the follow point 25 (an imaginary point set by the calculator to control the speed of the bar). Adjust it. The descaling header 13 completely removes the scale using one or two rows, and at the point of passing through the follow point 25, the speed pattern is rolled in synchronization with the first finishing mill 19a (shown in FIG. 2). We have been operating.

However, this operation method has the fastest speed at which the tip passes through the descaling header 13 when viewed in the longitudinal direction of the bar 10, and thus the moving speed of the bar 10 in a material material or a special material or a part of general steel. Increasing the speed, the oxidized scale was not completely removed, which provided a problem cause to cause scale defects in the product (coil: 22). There was a problem that the temperature is not secured as much as the target temperature.

On the other hand, Figure 9 shows the surface temperature distribution of the bar (10) when using only the heat transfer (13a) and the front and rear heat (13a, 13b) mixed in the state at a constant speed during high pressure desqueling spraying When spraying only the heat transfer 13a, the overlapping portion of the vertical stripe appeared, which caused premature roll wear during the rolling operation, and when spraying the front and rear heats 13a and 13b , the overall temperature was uniform. It shows the distribution but the temperature in the center is extremely low.

FIG. 10A illustrates that the decelerating header 13 uses only one row when rolling the thin material (PO material) and slows down the advancing speed so that the exit temperature is as fast as the exit temperature is not secured (shown in FIG. 10B). It is a comparison of the material of the bar 10 according to the temperature appearing (shown in FIG. 10C).

If the exit temperature is not secured as shown in the figure (Fig. 10b), the processing crack (CRACK) occurred by coarse grains during rolling, but when the exit temperature is secured (Fig. 10c), it can be seen that a normal material can be obtained.

The present invention has been made to solve the above-mentioned problems in view of the above-mentioned problems, and an object thereof is a facility for removing an oxidation scale generated on the surface of a rolled bar in a rough rolling mill with a high-pressure cooling water during a hot rolling process. by optimizing the running speed of the usage pattern and bars of scaling header prevents the front end scale defects in the coil and to ensure the spirit mill outlet temperature of the strip through a location-specific de-scaling header nine minutes using a bar a manner that reduces the leading end material poor It is to provide a method of optimizing bar progression speed .

As a technical idea for achieving the above object of the present invention,

The number of descaling headers used during the hot rolling process of the hot rolled material is used for both front and rear rows, and after the front end of the bar passes the follow point, only one row of front and rear rows is used. An invention of a method of advancing the tip descaling header passing speed as fast as possible without causing a collision with the first finishing mill is presented.

Hereinafter, a method of optimizing bar progression speed by using the descaling header classification of each bar according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a process chart showing the flow chart of the rolling method for the bar speed control and the number of descaling header using the method of optimizing the bar progress speed by using the decelerating header classification according to the position of the present invention, Figure 2 is the present inventor Fig. 3 is a graph showing the speed pattern of the bar in the desqueling zone by the method for optimizing the bar progression speed by using the division of the desqueling header for each bar position. bar and di scaling minutes a graph showing the double row Duration of post-bar surface temperature according to the traveling speed optimization method, Figure 4 is a bar bar surface according to the traveling speed optimization with location-specific de-scaling header nine minutes using the present inventors bar And a graph showing a drop distribution of the temperature directly below, and FIG. 5 shows a bar progression speed through the use of the descaling header according to the position of the bar of the present invention. And one based on the de-scaling passing time by the optimization method shows a temperature change portion distal end and midan graph, and Fig. 6 is a bar di scaling by the traveling speed optimization with location-specific de-scaling header nine minutes using the present inventors bar FIG. 7 is a graph illustrating changes in temperature of the tip of a bar according to the number of headers and bar speed, and FIG. 7 illustrates an exemplary embodiment of a location of a follow point by a method of optimizing bar progression speed by using a descaling header for each bar position of the present invention. It is a graph.

As shown, the upper calculator determines the number of use of the descaling header 13 and the two-row spray material 58 at the distal end. The speed of the bar 10 and the number of the descaling header 13 are determined according to the determination result. To determine and to roll and follow the following points (48, 62 (shown in Figure 1)) is composed of a system that allows to roll at a conventional spray pattern and bar travel speed.

This means that the heat that normally sprays only the tip portion during the operation process stops use after the tip portion, that is, when only the heat transfer 13a or the after heat 13b is continuously sprayed when the high pressure water is sprayed from the descaling header 13. In the case where only one row is used, as shown in FIG. 9, the temperature dropping portion of the bar 10 due to the inter-nozzle overlap of the descaling header 13 causes local wear on the work roll surface of the finishing mill 19. It is to be able to use alternating heat and heat.

In other words, if the first bar 10 is sprayed by the heat transfer, the next second bar 10 is sprayed by the heat transfer so that the cooled part passes through the work roll through the cooled part due to the overlap in the battlefield.

Therefore, in the case where only two rows are designated at the front end portion, it is configured to stop the heat of spraying only the front end portion after the tip portion passes.

According to the present invention configured as described above, when the upper calculator determines the number of use of the descaling header 13 and checks the spray pattern, the amount of spraying is as in the conventional case. Spraying in two rows (44), the speed of the bar (10) proceeds as directed by the calculator (46) to the follow point (48), and then the speed of the bar (10) to the first finishing mill (19a) and the synchronous speed Deceleration (50) is to be rolled, and the injection of the descaling header 13 is terminated (54) and the end of the operation (56) at the time passing through the descaling header (13) of the bar (10).

In addition, when inputting into the first column using material 42 of the descaling header 13 from the upper calculator, it is first determined whether only the front end portion is the second row spraying material (58). When the rolling process is performed, and only the front end portion is a two-row spray material (58), the descaling header 13 is sprayed in two rows while calculating the follow point 66 according to the speed of the bar 10 in the calculator. The progression of the bar 10 proceeds at a maximum speed of 64 within a range capable of preventing a collision with the first finishing mill 19a.

Here, when the bar 10 arrives at the follow point 62, the speed is decreased rapidly to synchronize the traveling speed with the first finishing mill 19a (50), and the descaling header (13) is sprayed in one row (68). Rolling is in progress.

On the other hand, also goes to the illustration (A) looking Conventionally di scaling header 13, the heat transfer (13a) or, if re-used only by post heating (13b) bar cutter 16 is advancing speed 90MPM up front, as in Fig. 2 After cutting the bar, the speed is lowered to about 55 MPM. At this time, the descaling header 13 is sprayed with only one heat to remove the scale, and reaches the follow point 25. The speed is lowered to 32 MPM, which is the first event. It proceeds at the synchronous speed with the rolling mill 19a so that there is no problem when entering the first finishing mill 19a.

◆ Example of use (museum PO material, thickness 1.4 <t <1.9mm material)

In Figure (B) of Figure 2 is a graph showing the working pattern when rolling the material in the Gwangyang 3 hot rolling mill.

Until the bar 10 passes through the cutter 16, the speed is maintained at 90 MPM as in the prior art, and after the bar 10 is cut to the follow point 25, the progress speed of the bar 10 is 68 MPM (conventional speed). 10 to 15MPM speed increase), and the descaling header 13 is sprayed in two rows, and the speed decreases at the time passing through the follow point 25 to synchronize with the speed of the first finishing mill 19a, The descaling header 13 stops the heat of spraying only the front end portion, so that only one heat is sprayed, as in the conventional case, to perform the rolling operation.

In addition, FIG. 3 shows the time when the surface temperature of the bar 10 is recuperated after descaling, and is a graph showing the effect of the two-row spraying of the descaling header 13 .

As shown, the time taken to recover the original temperature after descaling of the rolled bar 10 is about 7 seconds when the bar 10 temperature is 1,000 ° C.

Therefore, the descaling header 13 may be sprayed in two rows, and another heat may be additionally used before the bar 10 temperature is restored and the surface is oxidized, thereby significantly reducing the generation of oxidative scale on the surface.

4 shows the amount of temperature decrease on the surface of the bar 10 after descaling, the higher the desqueling pressure, and the slower the speed of the bar 10 is, the larger the amount of temperature decrease.

Therefore, in order to compensate for the temperature of about 13 DEG C, which is lowered by one more heat injection, the passage speed is increased to relatively reduce the amount of temperature decrease.

Figure 5 shows the temperature difference between the tip of the bar and the tip after passing through the descaling header, and generally the oxidation of iron is much faster at higher temperatures.

Therefore, since the temperature of the bar 10 of the bar 10 is descaled, the temperature is displayed at 1000 ° C. or lower, so that even if only one row of the descaling header 13 is used, scale defects due to surface oxidation can be sufficiently prevented.

Figure 6 shows the change in temperature of the tip and tail end of the bar (10) appearing when rolling by the method according to the present invention and the conventional method, as shown in Figure (C) using a descaling header 13 in a row 10) When the speed is slowed down, the temperature distribution of the bar 10 shows that the temperature before and after the deceleration point of the follow point 25 decreases sharply compared with the target temperature (870 ° C.). As can be seen from the present invention, when the two-stage injection only the front end portion and the speed is faster, it can be seen that the temperature of the bar 10 is approaching the target temperature much more similarly.

FIG. 7 illustrates a follow point 25 position according to the specification of the finishing mill 19 of the Gwangyang 3 hot rolling mill, and the following follow point 25 positions the finishing mill 19 and the bar detector 27 for each plant. It appears different depending on the position of the bar cutter 16, the descaling header 13, and the positions are all calculated and applied automatically by the upper calculator, so there is no problem in using the above-described method.

As described above, the present invention is a material of 1.4 ~ 2.4mm thickness among hot rolled coils, which causes scale flaws in the tip end caused by the scale not peeling off from the descaling header and defects in the material of the hot rolled coil according to the tip temperature exit of the finishing mill. It is effective to prevent.

In particular, the pickling coil is a product in which the normal oxide film of the hot rolled coil is removed, and defects which are not visible in the hot rolled coil state are connected to the defects after passing the pickling process. It is possible to secure the surface quality at the level of cold rolled coil because there is no scale defect, and also to improve the workability by preventing material defects of the processing coil which demands secondary processing by securing the exit temperature of coil at the tip of the coil. .

Claims (3)

To remove the oxidation scale generated on the surface of the bar (10) rolled in the rough mill during the hot rolling process through the high pressure cooling water,  The front end of the bar 10, which is transferred to the first finishing mill 19, is sprayed with coolant on the surface of the bar through two rows of descaling headers 13 to remove the oxidation scale,  After passing through the follow point, which is a virtual point set to control the transfer speed of the bar 10, only one column of the descaling header 13 is operated to remove the oxidized scale, The speed at which the distal end of the bar 10 passes through the descaling header 13 proceeds within a range that does not cause a collision to the first finishing mill 19a. How to optimize bar progression speed. The method of claim 1, The descaling header (13) after the follow point time point is alternately operated, bar progress speed optimization method using the descaling header according to the bar position. The method according to claim 1 or 2, The bar 10, Method for optimizing bar progression speed by using descaling header according to the position of bar, characterized in that the thickness (t) is made of 1.4 mm <t <1.9 mm as the material PO material.

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