JPH07116720A - Method for improving sheet shape precision by steel sheet tail end detection - Google Patents

Abstract

PURPOSE:To especially improve the sheet profile's symmetry between the top end part and the tail end part of a slab and to improve the final shape's precision of the slab in a sheet shape precision improving method by the steel sheet's tail end detection. CONSTITUTION:In a rolling to locally change the final sheet thickness profile of a slab 1, the tail end of the slab 1 is detected by a tail end detecting sensor 7, its signal output is inputted in a controlling system 4, and the calculated rolling length value is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the plate shape accuracy by detecting the tail end of a steel plate, and more particularly, to improve the symmetry of the plate thickness profile at the tip and tail ends of the slab to improve the final shape accuracy of the slab. The purpose is to improve.

[0002]

2. Description of the Related Art A conventional rolling apparatus is shown in FIG. In FIG. 5, the slab 1 is rolled via the rolling roll 2. Rolling is performed in several times, and is repeated until the final plate thickness reaches a value set between about 60 mm and 300 mm.

The hydraulic pressure reduction device 3 can control the plate thickness of the slab 1 by changing the pressure applied to the rolling rolls 2 according to the command value issued by the control system 4 and changing the size of the roll gap by about 18 mm. .

The control system 4 receives the pulse signal output from the PLG 5 and calculates the rolling length of the slab 1. A command value of the reduction amount is calculated from the relationship between the rolling length and the rolling length-reduction amount issued by the command system 6, and the hydraulic pressure reduction device 3 is driven.

The PLG 5 generates a pulse signal when the rolling roll 2 rotates.

The command system 6 calculates the plate thickness, plate length, plate width, etc. of the slab 1 after rolling, sets the amount of reduction necessary to realize it, and transmits it to the control system.

[0007]

In the conventional rolling apparatus as described above, the shape of the steel sheet after completion of rolling is not a perfect rectangle when viewed from the upper surface, but the shape of four corners is W.
S and DS are different. This is because the thickness profile at the leading end and the tail end of the steel sheet is asymmetric in the rolling in the previous stage, and it is necessary to make this symmetrical.

[0008]

SUMMARY OF THE INVENTION The present invention advantageously solves the problems of the prior art, and in the rolling that gives a local change in the final thickness profile of the slab 1, a tail end detection sensor. The tail end of the slab 1 is detected by 7, and the output signal thereof is input to the control system 4 to correct the calculated rolling length value.

[0009]

According to the present invention, the tail end of the slab is detected by detecting the tail end of the slab by the tail end detection sensor 7 and the output signal thereof is input to the control system 4 to correct the calculated rolling length value. And the symmetry of the plate thickness profile at the tail end is improved.

[0010]

FIG. 1 is a diagram showing an embodiment of the present invention.

The slab 1 is rolled through the rolling rolls 2, the rolling is performed in several times, and the final plate thickness is about 6
It is repeated until it reaches a value set between 0 and 300 mm.

The hydraulic pressure reducing device 3 can control the plate thickness of the slab 1 by changing the pressure applied to the rolling rolls 2 according to the command value issued by the control system 4 and changing the size of the roll gap by about 18 mm. .

The control system 4 receives the pulse signal from the PLG 5 and calculates the rolling length of the slab 1. The command value of the reduction amount is calculated from the relationship between the rolling length and the rolling length-reduction amount set by the command system 6, and the hydraulic reduction device 3 is driven.

The PLG 5 generates a pulse signal when the rolling roll 2 rotates.

The command system 6 calculates the plate thickness, the plate length, the plate width, etc. of the slab 1 after rolling, sets the amount of reduction necessary to realize it, and transmits it to the control system.

A feature of the present invention is that the tail end detecting sensor 7 is used as a tail end detecting sensor 7 at a distance (about 10 m) from the back of the rolling roll 2 during the rolling that locally changes the final thickness profile of the slab 1. Imaging device 71 for photographing the slab 1
Is provided to obtain a two-dimensional image of the side surface of the slab, the image is captured by the image capturing means 72, A / D-converted, and the intra-image window setting means 73 is used to detect a tail end (referred to as a window). The image is extracted and the slab end position detecting means 7
The position of the tail end of the slab in the window is detected by 4, and a signal is output by the detection signal output means 75 when the tail end of the slab reaches a predetermined position in the window, and the output signal is input to the control system 4. Then, by correcting the calculated rolling length value, the symmetry of the plate thickness profile of the tip end portion and the tail end portion of the slab 1 is improved, and the final shape accuracy of the slab 1 is improved.

Here, each function in the tail end detection sensor 7 will be described in detail with reference to FIGS. 6 and 7.

FIG. 6 is a view showing an image photographed by the image pickup device 71. The slab 1 emitting heat radiation light is photographed brightly, and the light reflected by the heat radiation light on the roll cooling water is also photographed simultaneously. To be done. The in-image window setting means 73 sets a detection window in a portion excluding the portion where the light reflected from the roll cooling water is less affected and the light from the slab 1 is blocked by the rolling mill. FIG. 7 is a diagram for explaining the function of the slab tail end position detection means 74. By calculating the sum of the vertical luminance in the window over the entire horizontal direction, the light from the slab and the light from the cooling water Can be clearly separated, and when viewed from the left end of the window, the position where the luminance sum signal first becomes lower than the set threshold value can be regarded as the slab tail end.

FIG. 2 is a control flow of rolling according to an embodiment of the present invention.

FIG. 3 shows the relationship between rolling length and reduction amount set by the command system 6.

At the same time when the rolling is started, the PLG 5 rotates, and the control system 4 calculates the rolling length 1. Reduction amount ΔS = S at this time
_{1 is} constant.

Rolling length recognized by the control system 4 l = L ₁
When (L ₁ is about 100 mm), the hydraulic pressure reduction device 3 is driven to change the reduction amount with a constant inclination α. And l =
This change is continued until L ₂ (L ₂ is about 300 mm) is reached. That is, when L ₁ <l <L ₂ , ΔS = S ₁ =
It becomes α (l-L ₁ ).

When L ₂ <l <L ₃ , rolling is performed with a reduction amount ΔS = S ₂ constant. At this time, the slab 1 is detected by the tail end detection sensor 7.
When the tail end of is detected, the output signal is input to the control system 4,
Correct the rolling length l. The concrete correction method is as follows. And it was rolled length l = L _B at the tail end detection.
It is assumed that the length of (L ₅ −P) is obtained by rolling the part that has not been rolled at the time of detecting the tail end. (L ₅ is rolled length instruction system 6 is set - a rolling length full length in the rolling reduction of relations), the control system 4 modifies simultaneously rolling the length l and the tail end detection to L _B → P , The length calculation is continued thereafter.

When the rolling length l = L ₃ (L ₃ is about 300 mm from the tail end of the slab 1), the hydraulic pressure reduction device 3 is driven to change the reduction amount with a constant inclination α. This change is l =
Continue until L ₄ (L ₄ is about 100 mm from the tail end of slab 1). That is, ΔS when L ₃ <l <L ₄
= S ₂ + α (l-L ₃ ).

When L ₄ <l <L ₅ , the reduction amount ΔS = S ₁
Roll at a constant rate.

When the metal is finally turned off, the rolling is completed.

FIG. 4 shows the effect of the invention.

The relationship between the rolling length and the reduction amount set by the command system 6 is determined by using the predicted slab length obtained by calculation. When the actual slab length is different from this, the conventional system uses the slab 1 The thickness profile of the front and tail ends of the plate is asymmetric, but this time it is made symmetrical.

For example, in (a), the predicted slab length = 500
The end point of the inclined portion of the tail end is 4900 mm. If the actual slab length = 4950 mm,
Conventionally, as in (1) and (b), the tail end inclination end point is 4900 mm, which is the same as in (a), so the tail end flat portion is only 50 mm. However, in the present method, as shown in (1) and (c), the tail end inclination end point moves to 4850 mm, so the tail end flat portion is 1
It becomes 00 mm. Similarly, actual slab length = 5050 mm
Then, in the conventional method, as in (2) and (b),
The flat part of the tail end reaches 150 mm, but in this method, as shown in (2) (c), the tail end inclination end point = 4950 mm.
Therefore, the tail flat portion becomes 100 mm.

When the tip and tail profiles of the slab 1 are symmetrical, the shape of the final steel sheet after finish rolling becomes close to a rectangle when viewed from the upper surface, and the shape accuracy can be improved.

[0031]

As described above, the tail end of the slab 1 is detected by the tail end detection sensor 7 at the time of rolling in which the final thickness profile of the slab 1 is locally changed, and its output signal is used as a control system. By improving the symmetry of the thickness profile at the tip and tail ends of the slab by having the configuration to correct the calculated rolling length value entered in 4, the final shape accuracy of the slab 1 is improved. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a rolling apparatus that is an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a process of the rolling apparatus that is an embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between rolling length and reduction amount set by the command system of FIG.

FIG. 4 is a diagram showing a slab thickness profile in one embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of a conventional rolling apparatus.

6 is an image photographed by the image pickup device 71 of FIG. 1. FIG.

FIG. 7 is a diagram for explaining the slab tail end position detection means in FIG.

[Explanation of symbols]

 1 Slab 2 Rolling roll 3 Hydraulic reduction device 4 Control system 5 Pulse generator (PLG) 6 Command system 7 Tail end detection sensor

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Claims (1)

[Claims] 1. An image pickup device 71 for picking up an image of the slab 1 during rolling for locally changing the final thickness profile of the slab 1, and an in-image window setting for extracting an effective portion from the image. A tail provided with means 73, slab tail position detecting means 74 for detecting the slab tail position within the window, and detection signal output means 75 for outputting a signal when the slab tail end reaches a predetermined position. A method for improving the strip shape accuracy by detecting the tail end of a steel plate, which comprises detecting the tail end of the slab 1 by the end detection sensor 7, inputting a signal output thereof to the control system 4, and correcting the calculated rolling length value.