JPS63290604A - Method for different thickness rolling - Google Patents

Abstract

PURPOSE:To improve the yield of different thickness rolling by detecting a crop shape by a crop shape recognition device recognizing an effective width position in a crop, and opening or reversely rotating rolls after rolling over a prescribed length measured from the above position. CONSTITUTION:Detection data of a crop shape detecting sensor 4 is inputted into a crop shape recognition device 5 and an effective width position in a crop part at the top of a rolled stock is calculated by the device 5. Then, a rolling length from the mill center having an effective width is found based on an equation; work rolls are stopped, opened or reversely rotated at the time when a rolled length amounts to a prescribed length. Hence, the mill is controlled to bring a rolled length to be highly accurate and the yield of different thickness rolling is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of rolling different thicknesses in which plate materials of different thicknesses are continuously rolled in the same slab.

[Conventional technology]

When manufacturing thick plates, spare slabs are usually prepared in order to meet requests such as emergency supplies and small low/) orders. If these ordered products have different thicknesses, conventionally, a spare slab is rolled over its entire length to the thickness of the ordered product, and if the required length of the ordered product is short, there will be a lot of yield loss. There was a problem.

Recently, different thickness rolling has been carried out in which the same spare slab is assigned to multiple ordered products and the plate thickness is changed during rolling, in an effort to improve yield.

As shown in Fig. 5(a), the method of rolling at different thicknesses includes a method of stopping the rolling rolls in the middle of rolling and opening the rolling at the same time (
(See Japanese Patent Publication No. 52-26223), and a method of reversing the rolling rolls and pulling out the plate while maintaining the same rolling pressure (see Japanese Patent Publication No. 50-36826,
-24892)).

By the way, when a thick plate is rolled, as shown in Fig. 6, irregularly shaped parts a and b called crops are generated on the slab top and slab bottom. The plate thickness changes between the product B and the product B, resulting in a difference in thickness Wc that cannot be used as a product. Such irregularly shaped parts a and b
The length of the differential thickness portion C must be made as short as possible to reduce the yield of the product.

As described above, in order to improve the yield, it is necessary to control the position of the differential thickness portion so that both the thicker and thinner product lengths can be secured. From this perspective, there has been a desire to develop a technology that can detect and control compression extension with high accuracy.

[Problem that the invention seeks to solve]

The conventional method for measuring rolling length is to take advantage of the fact that the plate thickness at the edge of the plate tends to become tapered, and when variations in plate thickness occur, the measurement length is reset using a pulse generator (hereinafter referred to as PLO). Method for measuring plate length of only the part that can be used as a product (Japanese Patent Application Laid-Open No. 51-32658
(see Publication No.) was proposed. However, since the plate crop varies depending on the rolling size and other factors and has large variations, this method has a problem in that the accuracy of detecting the effective width position during plate cutting is poor.

As a method, when the top part of the steel plate is detected by a steel plate detector, the number of rotations of the rolling mill is reduced to zero, and then the rolling mill is reversed to perform biting back to obtain a thin wall part (Japanese Patent Application Laid-Open No. 1986-60- 37201)) Alternatively, a movable detector is set at a predetermined position to detect the rear end of the thicker side of the material to be rolled and stop the rotation of the roll (see Japanese Patent Laid-Open No. 60
-61106).

However, since these methods detect one point on the cropped portion of the board, there is a problem in that changes in the effective width position due to changes in the cropped shape of the board cannot be accurately detected.

Therefore, it is an object of the present invention to accurately detect the effective width position and its change during cropping of a plate, and perform blade thickness rolling with a high yield.

[Means for solving problems]

In order to achieve this objective, the blade thickness rolling method of the present invention, during blade thickness rolling, stops and releases the rolling roll midway through the rolling of the thinner plate, or reverses the rolling roll to produce plates of different thickness. In a rolling method in which sheets are continuously rolled from the same slab, a crop shape recognition device detects the cromp shape of the top of the plate, determines the effective width position in the crop, and starts length measurement from that position to determine the specified width. It is characterized in that the rolling rolls are stopped and opened or reversed after rolling to a length of .

[For f cans]

In the present invention, in order to ensure the product length of the thinner product, the crop shape detection sensor detects the effective width position of the crop part at the tip of the steel plate, and determines the distance from that position to the mill center. , P Correct the length measurement results obtained by a length measuring meter such as LG.

As shown in the front view of FIG. 1, the shape of the cropped portion is imaged by a crop shape recognition device (ACR).

Specifically, for example, an image sensor such as a CCD is used to scan an image in the vicinity of the cropped portion.

Within this ACR scan area, a cropping section.

The image is binarized and its contour is determined by image processing, and this contour is converted into coordinates. Next, the width of the cropped portion is determined by coordinate processing, and as shown in FIG.
The position 1 in the direction of the rolling extension that coincides with is determined using the end of the ACR scan area as a reference. Assuming that the effective width position correction length obtained by this is LX, the PLO count number CL, the advance rate ``, and the pulse increment 1.'', the rolling length with the effective width from the mill center is as follows: It can be calculated using the formula shown below.

L = CL・(1+ f >・I, −LX−・・
・・・・・・・・(1) On the other hand, the rolling length that starts counting from the rolling bite is L14=Cx・(1+f)・Ia, so the difference between Lx and L is Convert to a difference in PLO counts using the following formula.

ΔC=(L−t,)/(1−:f)・Il.

Then, the PLG counter)C is corrected using the following formula.

c' = c + ΔC Using the corrected PLG count C', the compression extension with effective width is C'(1+f)·1. , and when this value reaches a predetermined rolling length, the rolls are stopped or reversed.

In this method, the crop shape recognition device can be fixed at a certain distance from the mill center.

In this way, by recognizing the effective width position of the plate top using the crop shape recognition device, the rolling length having the effective width can be accurately determined, and the timing of stopping and rolling release or reversal of the final rolling roll can be controlled to improve the rolling process. This enables precise rolling control.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained based on examples. FIG. 1 shows the configuration of a finishing mill and control equipment among equipment for carrying out the rolling method of the present invention. In FIG. 1, 1 is a rolled material and 2 is a finishing mill. On the exit side of the finishing mill 2, there is a gamma ray thickness gauge 3. A crop shape detection sensor 4 is installed. The detection data of the sensor 4 is input to the crop shape recognition device 5, where the effective width position of the crop portion at the tip of the rolled material is calculated. In the figure, TM
indicates a table driving motor, MM indicates a mill motor, and P indicates a pulse generator. In addition, MTo is a controller that controls automatic operation of mill motor MM and table, AGC is a process controller for automatic plate thickness control, and AP
C is a process controller for automatic pressure reduction setting control;
These control data are exchanged with the rolling process controller via the data way. The rolling process controller is managed by POL, which manages processes such as logistics and performance within the plate factory, and also controls slab design,
It is managed by a production control system that creates rolling instructions, that is, a batch system.

In this way, the crop shape recognition device 5
The effective width position of the Y-shaped portion is detected, the rolling length having the effective width is determined based on the above-mentioned formula (1), and when the set length is reached, the rolling roll is stopped and opened or reversed.

By the way, there is a time lag between when the stop or reverse command is issued and when the mill motor MM actually stops or reverses, due to a delay in response of the control system, etc., and if this time lag varies, the accuracy of the stop or reverse position decreases.

FIG. 3 shows actual results of variations in stop or reverse positions due to error σDDC in the control system. Due to variations in the response delay of the mill motor, the pressure extension X required from a stop or reverse instruction to an actual stop or reverse rotation is considered to depend on the torque and inertia of the mill motor. FIG. 4 shows the results of measuring the relationship between the rolling extension X, the mill motor current which determines the magnitude of the load torque, and the mill speed which is proportional to inertia. As shown in FIG. 4, it can be seen that there is a correlation between the rolling length X, the mill motor current, and the mill speed. As a result of the regression,
The following formula was obtained.

X = a + b −V2+ c −I ・−・・
-C2) However, V: mill speed ■=mill motor current a, b, c: regression coefficient In rolling the thin section, when the rolling progresses to about 3 m before the roll reversal or stop position, the mill starts.

Start sampling the motor current and rolling speed. Sampling is performed at fixed lengths or time intervals, and when the roll is reversed or rolled to 1 m before the roll stop position, the sampling data is averaged, and then the calculation of equation (2) is performed. Then, when the rolling has progressed forward by the obtained value, an instruction is given to reverse or stop the mill.

Note that the calculation of equation (2) and the processing of the sampling data are performed by the controller MTO for automatic operation of the finishing mill motor and table.

As a result, the error σDDC of the control system was able to be reduced from 60 mm to 13 mm, compared to the actual result when no control was performed.

〔Effect of the invention〕

As explained above, in the present invention, during blade thickness rolling, the crop shape recognition device detects the crop shape of the top portion of the blade, recognizes the effective width position in the blade,
Length measurement is started from that position, and when the roll has been rolled to a predetermined length, the rolling roll is stopped and opened or reversed.

Thereby, the mill can be controlled by determining the rolling length with high accuracy. Therefore, according to the present invention, the yield of blade thickness rolling can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the method of calculating the rolling extension according to the present invention, and Fig. 3 is a graph of the variation in the reverse rotation position due to errors in the control system. , Fig. 4 is a graph showing the actual rolling length required from the reversal instruction to the actual reversal, Fig. 5 is an explanatory diagram showing the method of blade thickness rolling, and Fig. 6 is an explanatory diagram of irregularly shaped parts in blade thickness rolling. . Patent applicant: Nippon Steel Corporation Representative Masu Kobori (and 2 others)
Figure 5 Figure 1 Figure 2 W Existence width Figure 3 (mm) Diagram 4 (Ipm+

Claims (1)

[Claims] 1. Crop shape recognition in the different thickness rolling method in which plates of different thicknesses are obtained from the same slab by stopping and releasing the rolling rolls midway through rolling of the thinner plate or by reversing the rolling rolls. The device detects the crop shape of the top of the plate, recognizes the effective width position in the crop, starts measuring the length from that position, and when the roll is rolled to a predetermined length, the rolling roll is stopped and released or reversed. Features a different thickness rolling method.