JPS6027406A - Control method of slab edging in hot rolling mill - Google Patents

Abstract

PURPOSE:To decrease the crop parts at the front and rear ends of a slab and to improve the yield of material in a hot reversing, and horizontal rolling by edging the front end in the advancing direction of material by only an outlet-side edger and edging a part from the intermediate part of material by an inlet-side edger. CONSTITUTION:In a hot reversing, and horizontal mill equipped with respective sets of edgers at its front and rear sides; the front-end part in the advancing direction of material is edged only by an outlet-side edger after rolling it by horizontal rolls, and a part from the intermediate part of material is edged by an inlet-side edger. At the time of rolling in the reverse direction, the material is rolled reversely to said operation. The dog-bone parts at both ends of the material approach the central part of material width, and the extensibility of material at the central part is improved. Accordingly the crop length is decreased, and the cut-off length of the end part is reduced and the yield of material is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a vertical roll rolling mill (
This article relates to a rolling method for reducing as much as possible the shape defects (crop portions) at the leading and trailing ends of slabs during medium rolling (edging rolling) in slabs that are released into a thermostatic reversible rolling mill equipped with an edger. @ Traditionally, slabs supplied to hot strip mills and plate mills were manufactured using blooming mills, but in recent years, as continuous casting machines have been shut down, the proportion of continuously cast slabs has also increased. It's getting better.

When manufacturing slabs using a conventional blooming mill, it is easy to set the slab dimensions to any desired value, so it is possible to adjust the dimensions of the finished product to the subsequent hot strip mill or thick plate mill. Since the appropriate slab dimensions (width, thickness) had been determined, (the question is, in order to manufacture strips of medium size 1000m, hot strip mills or thick plate mills that supply slabs between medium 1000 and 1010m are required. Both the medium reduction and the reduction in subsequent rolling equipment such as As a result, the amount of intermediate reduction in the binding and subsequent rolling equipment has become significantly larger.

For example, if we collect the medium dimensions of slabs from a continuous casting machine every 50 m and roll a slab from 240 mm thick and 1050 am to 40 mm thick and 1000 fl,
Generally, the reduction amount of approximately X is 9 in the horizontal direction, so the intermediate reduction amount is 1060 + (84G-40)xτ-1000=
100 am, which is an extremely large value compared to the conventional one.In hot rough rolling in a conventional hot strip mill, the vertical roll opening degree is less than C per one rolling. However, in the case of continuous cast slabs,
As the medium reduction sensitivity increases, it becomes clear that the number of defective products at the leading and trailing ends of the material (crop portion) increases, and the yield rate of the final product decreases. This is a diagram showing the shape of the tail end of the rough parr [amount produced after completion of rough rolling] in the hot strip mill used, and the length of the cropped part called a fishtail is 800 as.
This portion was cut off as a clog, resulting in a decrease in yield.

The present invention has been made in order to improve the above-mentioned problems.The present invention has been made in order to improve the above-mentioned problem.Fishtails generated at the cropped portion, particularly at the tail end of the material, are studied from the direction of metal flow at the material end, and the amount of fishtail generated is The object of the present invention is to provide a medium reduction rolling method and a control device for the same.

The purpose of this invention is to study the direction of metal flow at the leading and trailing ends of the material during edge rolling and the amount of crop produced! The results of various experiments have already been reported regarding the amount of crop produced during hot reversible rolling (including etching).

Figure 2 shows the measurement results of the amount of crop produced during hot reversible rolling, and it is clear that the amount of cyclotubule produced is significantly larger at the tail end than at the leading end of the material, and this is confirmed by actual operation data. has also been confirmed.

(N magazine “Tetsu to Hagane” O 1967 No. 15, page 247 Fi
fI1, etc.) This means that at the center in the longitudinal direction of the plate, the roll and pressure f
The deformation at the width end that occurs because the junction length of Tatemura I'+F is shorter than the plate width is mainly dogbone deformation, whereas at the leading and trailing ends, there is no restraint in the longitudinal direction, so A crop is generated by shearing deformation, and the crop at the tail end becomes larger due to the presence of frictional force between the roll and the material and the direction of the shearing force.

Present invention I-i Focusing on the above phenomenon, O's method is used to determine how to use edgers on the front and rear surfaces so that the direction of edge rolling in Somachi reverse rolling does not cause crotches as much as possible.

Furthermore, it has already been reported that the indentation rolling method is effective as a method for reducing cropping during edge rolling.

Fig. 8 is a diagram showing the degree of crop reduction when push rolling is adopted. The portion decreases. However, in the conventional simple edge rolling method, this push rolling can only be applied to the leading edge of the material, and therefore the effect has not been fully demonstrated. Another object of the present invention is to further reduce the cropped portion by combining the back-and-forth edger method described in the above-mentioned object with this push rolling.

Now, the method of the present invention will be explained in detail below using Fig. 4. Fig. 4 shows the amount of intermediate reduction that the material undergoes in the longitudinal direction of the material when performing shearing rolling with a hot reversible rolling mill in the present invention. This is a schematic diagram showing the case where rolling is performed using a reverse rough rolling mill consisting of 12 edgers of 1 ft in the front and back and one horizontal rolling mill, shown at the bottom of the figure. In Fig. 4, ■ indicates medium rolling by the front edger (EII'), ■ indicates medium rolling by the rear edger (CWB), and for convenience of explanation, the case of 8-pass rolling is shown. The number of passes has nothing to do with the essence of the present invention.

In Fig. 4, in pass II (pass No.) noedging rolling, the central part of the material is
However, the leading edge of the material is rolled by the back edger (IB) instead of the # edge edger (IiIyr). This is because the leading edge of the material is subjected to indentation rolling using horizontal rolls and a rear edger, and as shown in FIG. 8, this is effective in reducing the amount of crop produced at the leading edge of the material.

Further, the tail end portion IJ3) of the OL-order KIri material is not subjected to medium pressure. This is because if the tail end fBl of the material is reduced to 1, the generation of the tail end crop amount shown in FIG. 2 cannot be avoided.
is the next pass, that is, the second pass (bus NQ ■ Jth tip (?)
It will be under moderate pressure. (This is possible because it is a reparsing mill.) In the second bus (pass No. Change.

That is, the central part of the material is rolled by the rear edger (EB), and the leading edge (T) of the material is rolled by the horizontal roll (I).
Indentation rolling is performed between ll and the front edger (EF).

Also, for the material tail end (Il), l'lJ of the first bus
Since it is rolled down during rolling, actual rolling is not required in the second pass.

Relationship between medium pressure soaking in the 1st bath and the 2nd bath f! : To explain, the pass schedule is selected so that the leading and trailing ends of the material are rolled down by one push rolling, while the central part of the material is rolled by two rolling passes. Ru.

In the 8th bus, the entire length of the material is V, and the front edger (IR) is used to perform rolling with the I'll reduction dovetail constrained. It is possible to minimize the fluctuation of 1J interest on the bridging portion due to different usage.

Regarding the Olpass and the second pass in the above explanation, (due to their combination) medium-pressure dipping by both baths is equivalent to fully opening the material, so it is possible to repeat this combination further. That is, by replacing the first pass with the maki number pass and the second pass with the 114 number pass, the number of passes can be increased arbitrarily. One pass of medium-pressure dipping and the number of passes can be determined using a method known in the art.

According to the method of Vc book #3 beak, the leading and trailing end portions of the feathers are rolled as the leading end portions of the material in the middle rolling of hot reversible rolling. It is possible to reduce the cropping amount as shown in the figure.

Furthermore, with the method of the present invention, it is possible to simultaneously use indentation rolling with horizontal rolls during this material tip rolling.
As is clear from the figure, it is possible to further reduce the amount of crop produced.

below? A concrete actual JM example of the present invention will be explained in detail using FIG. 6. In Fig. 5, l, 2°8ij town reverse forward and reverse rolling horizontal roll, front edger.

Rear edger roll; 4 is a roll opening positioning device for front and rear edgers; 5, 6. 9.1 is a speed control device that includes the main drive devices for the horizontal rolls and front and rear edgers of each YVi; 8 is a main control device that executes reversible operation control of the reversible rolling mill; 9.1
0 is a pulse transmitter that detects the rotation angle of the front and rear edgers, 11° is a hot metal detector (Hwv) that detects the arrival of Ig Fi material on the front and rear edgers, 20 is a control device according to the present invention, and 80 is a hot reversible device. In the schedule calculation direction for calculating the rolling schedule of rolling, M is the material.

Next, all previous works of the apparatus shown in FIG. 6 will be explained.

When the material M approaches the reversible rolling mill, the schedule calculation calculator 80 determines the yH lower (horizontal, medium reduction) pattern, rolling speed, total number of buses, etc. for the material blade by a known method, and calculates all speed pattern data. The intermediate pressure reduction pattern is transmitted to the master control device 8 and the intermediate pressure reduction pattern is transmitted to the control device 20.The control device for the horizontal reduction pattern is not shown explicitly because it is well known.

The schedule calculation calculator 8o calculates the two positions of the front edger and the rear edger at each pass number shown in FIG. 4, the roll opening degree during rolling and the roll opening degree during release, based on the schedule calculation results. The opening change point of the edger during rolling is also determined (as the material length) and transmitted to the control device 20.

The opening quality modification point can be determined based on the schedule calculation, such as the size of the rolled material.

Now, when the control device SO receives the above data, the first pass rolling of the material M is started. The opening degree of the rolls in the l-th pass front edger is set to the open position iij, and the opening degree of the rear edger 80 roll is set to the rolling position. Material wing is HMDI
When reaching I, the control device 20 uses the PuO2 signal to track the tip opening changing point, and when the changing point arrives at the front edger 2, the opening is changed from the fully open position to the rolling position. . When the leading edge of the material M reaches the rear edger 8, the HMD 1B is changed from the rolling position to the open position.

Also, HMD 11 and pLG9 are exactly the same for the tail end.
The arrival of the roll opening change point at the front edger 2 is tracked, and the roll opening is changed from the rolling position to the open position again.

Further, regarding push rolling, pushing force can be generated by setting a predetermined speed difference between the horizontal roll and the rear edger (set the edger speed to a low value). In the method of the present invention, the control device goIi calculates the speed difference which is also applied to the pushing force, gives it to the main control device 8 in advance as a correction amount of the rear edger speed, and starts rolling in that state to generate the pushing force. I can do it.

When the tip opening change point of material M is detected, the rear edger opening moves to the open position, so the pushing force naturally disappears. It is desirable to set the amount of modification from go to 8 to zero in order to make the roll [for the roll].

The operations of the second and subsequent buses are exactly the same as the previous Onibus series.

In the above embodiment, an HMD and a PLG are used as tracking devices for changing the roll opening degree, but there is no particular problem with the method used.

Also, a schedule calculation computer and a control device g.

In this embodiment, the control function division is only 1jjAJK, and furthermore, the actual number of steps involved in the control device 2o, such as a computer and a/a control device, does not matter.

As described above, according to the method of the present invention, the edge of the material is always rolled as the tip, so the occurrence of single-end flop can be avoided, and the push rolling method can always be used, which has a remarkable effect on reducing flop loss. It has the following.

[Brief explanation of drawings]

Figure 1 is a diagram showing the crop shape of the tail end of the coarse par of a hot strip mill, Figure 18 is a diagram showing the amount of crop generated at the leading and trailing ends of the material, and Figure 18 is a diagram showing the relationship between the pushing force and the leading edge crop. , FIG. 4 is a diagram for explaining the medium rolling method of the present invention, and FIG. 5 is a block diagram showing an embodiment of the present invention. In the figure, l is a horizontal roll, 2 is a front edger, 8 is a rear edger roll, 4 is a roll opening position 1 determining device, 5, 6
．． 7 is a speed control device, 8 is a master control device, 9.10 is a pulse transmitter, tt, tg are hot metal detectors ([MI
) go is the control device according to the present invention, 80 is the schedule calculation calculator, hai is the material, gr is the front edger, BB
is the later edge, ■ is the horizontal roll, T is the tip of the material, B
is the tail end of the material. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Ohatsu Figure 1 Figure 2

Claims (1)

[Claims] (1) When performing reversible multi-pass rolling using a hot reversible rolling mill equipped with a horizontal roll mill and vertical roll mills on its front and rear surfaces, both ends of the material are ) A method for controlling the intermediate reduction of slabs in a hot rolling mill, characterized by controlling the slab to be rolled at the exit edger.
1. A slab intermediate reduction control method for a hot rolling mill according to claim 11, wherein the central part of the material is subjected to intermediate reduction by an inlet edger, and only the tip portion is intermediately reduced by an outlet edger. (31) A special IPF characterized in that when the tip portion of the material is rolled by the edge edger, the speed difference between the horizontal roll and the exit edger is controlled so that the pressure rolling is performed between the two. A method for controlling the slab width reduction of the same rolling mill.