JP2005131692A - Rolling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling method by which the generation of off-gage is minimized by suppressing thickness variation in the joined part after welding, which is caused by the material characteristics such as the thicknesses and the hardness of a preceding material and a succeeding material by automatically detecting the joined part, and the fracture of a sheet is not caused when rolling or at stages after that, in the rolling for continuously rolling a material having the joined part of the preceding material and the succeeding material which are different in the material characteristics from each other. <P>SOLUTION: When rolling the material having the joined part between the preceding material and the succeeding material which are different in the material characteristics from each other in a stage for rolling the sheet 1 by using a rolling stand having at least a pair of rolls 2, by detecting the joined part by providing a means 3 for detecting the joined part before the rolling stand and, controlling the thickness by providing means 7, 8, 9 for controlling the thickness of the sheet 1 at the rolling stand and controlling the thickness by providing means 10, 11 for switching thickness control while tracking a joined position, the rolling is performed so as to have a predetermined thickness by preventing a fluctuation in the plate thickness variation before and after the joined part after rolling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a rolling method in which materials having joint portions of preceding and following materials having different material properties are joined and continuously rolled, and in particular, the position of the joint is determined by a simple equipment configuration and algorithm. The present invention relates to a rolling method in which yield is improved and stable operation can be obtained by automatically determining and controlling the joint portion to a predetermined plate thickness, thereby minimizing the plate thickness variation of the joint portion.

  When an expensive plate material is rolled by a batch mill, it is necessary to minimize off-gauges and quality defects generated at the front and rear ends of the plate material, which are a major factor in yield reduction. For this reason, an inexpensive plate material is joined to the front and rear ends of the plate material by welding, but due to differences in material properties such as plate thickness, hardness, deformation resistance, etc., the rolling conditions such as the rolling position with respect to the preceding material are reduced. On the other hand, when the succeeding material is rolled as it is, there is a problem that the thickness variation of the joint portion due to welding is large, which causes the occurrence of plate breakage at the time of rolling or the subsequent process, and decreases the productivity.

  As a well-known method for preventing the above-described problems of fluctuations in sheet thickness, it is necessary to obtain both rolling schedules before and after the joint in advance and continuously change the rolling schedule while suppressing fluctuations in sheet thickness and tension. There is a technology to change the thickness of the plate. In this case, a method of optically detecting a hole formed in the plate material is generally used as the position detection of the joint portion of the material. This method is widely used in tandem cold rolling mills, but it requires drilling in advance, and requires a huge calculation system for installing a hole detector and changing the rolling schedule, resulting in a large capital investment. It must be made into a thing.

  In addition, regarding the technique for detecting the joint portion of the material in the process of continuously rolling the plate material, for example, in Patent Document 1, for the welded portion where the rear end of the preceding material and the front end of the following material are flash-butt welded Use a two-dimensional distance meter to continuously measure the cross-sectional shape of the welded portion along the weld line, and determine whether or not the welded portion is acceptable by checking the presence or absence of a step caused by the bead residue of the welded portion and the size thereof. However, it is intended to continuously measure the cross-sectional shape, takes a short time but takes a certain time, and is not intended to detect a welded part instantaneously.

  As a technique for controlling the plate thickness, for example, Patent Document 2 discloses a mill constant variable control AGC (Automatic Gauge Control) for detecting a rolling load variation to determine a plate thickness variation and correcting a reduction operation amount, a remaining plate. Roll-down monitor AGC for eliminating thickness deviations, FF (Feed forward) -AGC for correcting rolling roll rotation speed by tracking sheet thickness deviation until just before entering the rolling roll in synchronization with sheet speed In rolling mills using various AGCs such as exit side speed AGC for changing the tension by operating the rotation speed of the roll and eliminating the steady thickness deviation on the exit side, A method for estimating an AGC abnormality is disclosed. As described in Patent Document 2, various types of AGC are arranged for various purposes in the rolling mill, but it suppresses plate thickness fluctuations before and after the joint between the preceding material and the following material. Nothing is arranged for that purpose.

JP-A-10-006029 Japanese Patent No. 3171212

    The present invention automatically detects a joint in a rolling process in which a material having a joint between a preceding material and a succeeding material having different material properties is joined and continuously rolled, and the plate thickness of the material before and after the joint. In addition to minimizing the amount of off-gage generated by suppressing fluctuations in the thickness of the joint after rolling due to material properties such as hardness, a rolling method that does not cause sheet breakage during rolling or in subsequent processes is provided. The purpose is to do.

In order to achieve the object of the present invention, a rolling method of the present invention is a method for rolling a plate material using a rolling stand having at least one pair of rolling rolls, and joining a preceding material and a subsequent material having different material properties from each other. When rolling while continuously conveying a material having a thickness, a means for detecting the joint is provided in front of the rolling stand to detect the joint, and a means for controlling the thickness of the plate material is provided in the rolling stand. By controlling the plate thickness by controlling and controlling the plate thickness while tracking the bonding position, the occurrence of plate thickness fluctuations before and after the joint after rolling is prevented and the predetermined plate thickness is achieved. A rolling method (Claim 1), characterized in that
In the rolling method of the above (Claim 1), a radiation thickness gauge is provided on the entry side of the rolling roll as means for detecting the joining portion of the material to be rolled, and the nominal thickness information on the entry side of the rolling roll before and after the joining portion. (2) and automatically detecting the joint based on the radiation transmittance characteristic information of the plate material before and after the joint portion and the plate thickness measurement value measured by the radiation plate thickness meter. The rolling method according to claim 1 or 2, wherein when the joint portion of the material to be rolled passes through at least the downstream rolling roll, the high mill constant variable control is operated using means for controlling the plate thickness. Therefore, it is possible to prevent the occurrence of sheet thickness fluctuations due to the material properties before and after the joint and control the sheet thickness of the preceding material after rolling and the sheet thickness of the succeeding material to be a predetermined sheet thickness (claims). 3), and the pressure of the above (Claims 1 to 3) In the method, immediately after the joint portion of the material to be rolled passes through the entry side radiation thickness gauge of the rolling roll, at least the AGC operation using the entry side radiation thickness gauge is stopped, and a preset preceding material By automatically switching a set value of the radiation transmittance of the material to a set value of the radiation transmittance of the following material, and automatically performing a series of operations for resuming the AGC operation using the entry side radiation thickness gauge, Minimize fluctuations in the thickness of the preceding material and the following material (Claim 4), or at least immediately after the joined portion of the material to be rolled passes through the exit radiation thickness gauge of the rolling roll, Stop the AGC operation using the thickness gauge, and switch the radiation transmittance setting value of the preceding material set in advance to the radiation transmittance setting value of the following material, then use the exit radiation thickness meter Series to resume AGC operation By performing the operation automatically, characterized by the thickness variation of the preceding material and the following material to minimize (claim 5).

  By using the rolling method of the present invention formed in this way, materials having different material properties due to material thickness, material composition, etc. are joined, and the joint is continuously passed through and rolled. In doing so, plate thickness fluctuations before and after the joint after rolling are suppressed. This improves the plate thickness accuracy in the longitudinal direction over the entire length after rolling, and prevents the occurrence of plate breakage due to plate thickness fluctuations during rolling of the joint or subsequent process plate-through, resulting in continuous high production. It becomes possible to produce board materials with high performance. Moreover, since the rolling method of the present invention can automatically determine the position of the joint portion of the plate material using a radiation plate thickness meter installed on the entry side of the rolling roll, the drilling process for detecting the joint portion and its detection It is not necessary to install a separate vessel, and inexpensive equipment can be realized.

  Hereinafter, as an example of a plate material having different material properties, a low carbon steel plate and a nickel alloy plate having different radiation transmittance due to material components are joined by butt welding, and the joined portion is continuously attached to a rolling roll. The present invention will be described with reference to the drawings on the assumption that the sheet is rolled by rolling.

  FIG. 1 shows a conceptual diagram of a rolling mill to which the present invention is applied. Although the method of the present invention can be applied to a multi-stage stand mill having two or more stands, a case where it is applied to a single stand mill will be described in order to simplify the description. The plate material 1 proceeds from right to left as indicated by an arrow in FIG. An entrance side radiation thickness meter 3 is provided on the entry side of the rolling roll 2, and an exit side radiation thickness meter 4 is provided on the exit side, and the thickness before and after rolling is measured. Here, an example in which an X-ray thickness meter incorporating low carbon steel as a reference plate is used as each of the radiation plate thickness meters 3 and 4 is shown. The rolling roll 2 is provided with a rolling load meter 5 and a hydraulic pressure reducing device 6, and is equipped with a plate thickness control device comprising three types of devices: a mill constant variable control device 7, a feedforward AGC device 8 and a feedback AGC device 9. Has been. Moreover, the material junction determination operation device 10 is an arithmetic device that determines a junction from information on the nominal plate thickness and the radiation transmittance correction coefficient of the material before and after the junction, and information on the plate thickness detection value by the entrance radiation plate thickness meter 3. is there. Further, the command device 11 tracks the position of the joint in the mill, and switches the ON / OFF of the three types of plate thickness control devices 7, 8, 9 and the radiation plate thickness gauges 3, 4 on the input and output sides. This is a device for instructing to change the radiation transmittance setting.

  The sheet material 1 to be rolled is a low carbon steel plate as a preceding material and a nickel alloy plate as a following material, and is continuously butt welded and passed through a rolling roll 2. Here, the nominal thickness of the preceding material and the succeeding material, and the radiation transmittance correction coefficient in the entrance side radiation plate thickness meter 3 and the exit side radiation plate thickness meter 4 for the preceding material and the following material are calculated as a material junction determination calculation device. 10 is entered in advance. The rolling roll 2 is preset with a reduction position for rolling a low-carbon steel plate, which is a preceding material, to a predetermined thickness. The plate thickness before and after the stand for rolling the preceding material is set to the entrance side radiation plate thickness meter 3 and the exit side radiation plate thickness meter 4, and the plate thickness is controlled by the feedforward AGC device 8 and the feedback AGC device 9, When the welded joint with the succeeding material passes through the entry side radiation thickness meter 3 and the exit side radiation thickness meter 4, the nickel alloy plate is less likely to transmit X-rays than the low carbon steel plate. Depending on the radiation thickness gauges 3 and 4 on the entry side and the exit side adjusted to the radiation transmittance for the steel plate, the nickel alloy plate of the succeeding material is detected as a value different from the actual plate thickness. Using this phenomenon, the joint is automatically detected.

Next, an example of this material joint determination algorithm will be described. The actual plate thickness measured with a micrometer or the like of the material to be measured is ha, and the plate thickness measured with the radiation side thickness gauges 3 and 4 calibrated with the built-in reference plate is hm. In this case, the radiation transmittance correction coefficient α of the radiation plate thickness gauges 3 and 4 on the entry side and the exit side is expressed by the following equation (1).
α = {hm / ha-1} (1)
When the nominal thickness of the preceding material A is h (A) and the radiation transmittance correction coefficient of the entrance side radiation thickness meter 3 is α (A), the detected thickness of the preceding material A is hm (A). The relationship is expressed by the following equation (2).
hm (A) = h (A) (2)
Further, with the entrance side radiation thickness meter 3 set with the radiation transmittance correction coefficient α (A) of the preceding material, the succeeding material B with the nominal plate thickness h (B) and the radiation transmittance correction coefficient α (B). Assuming that hm (B) is the plate thickness detection value when measuring, the relationship is expressed by the following equation (3).
hm (B) = h (B). {1 + α (B)} / {1 + α (A)} (3)
In general, since h (A) ≠ h (B) and α (A) ≠ α (B), the relationship of the following expression (4) is established.
hm (A) ≠ hm (B) (4)
When the succeeding material B passes from the preceding material A through the entrance side radiation plate thickness meter 3 set by the radiation transmittance correction coefficient α (A) of the preceding material A, the plate thickness detection value is before and after the joining portion of the material. It changes from hm (A) to hm (B).

Usually, since there is a thickness variation in the longitudinal direction, both the leading material A and the following material B itself are accompanied by a thickness variation. Compared to the variation amount, the thickness of the two materials sandwiching the joint portion When the plate thickness change detected by the radiation plate thickness meter 3 is large due to the difference in level or radiation transmittance, the junction is determined by monitoring the difference in the plate thickness detection value. Is possible. That is, the plate thickness hm [α (A)] detected by the entrance side radiation plate thickness meter 3 set by the radiation transmittance correction coefficient α (A) of the preceding material A and the nominal plate thickness h (A ) Is expressed by the following equation (5).
| Hm [α (A)]-h (A) | (5)
The plate thickness change estimated to be detected when the joint passes through the entrance side radiation plate thickness meter 3 set by the radiation transmittance correction coefficient α (A) of the preceding material A is the following (6). It is shown by the formula.
| H (B) · {1 + α (B)} / {1 + α (A)} − h (A) | (6)
Then, comparing the formulas (5) and (6), the following formula (7) | hm [α (A)] − h (A) |> β · | h (B) · {1 + α (B)} / {1 + α (A)}-h (A) | (7)
The point where the condition indicated by is satisfied is determined as the joint portion of the material.
Β on the right side of the equation (7) is a coefficient, and the amount of change in plate thickness detected when passing through the joint should in principle be the same for the right and left terms when β = 1. However, in reality, there are effects such as the plate thickness variation in the longitudinal direction of the material and the measurement accuracy described above. Therefore, the β value is adjusted in the range of 0 <β <1, and the optimum value for preventing the joint detection error. Set.

  Next, a plate thickness control example for preventing the occurrence of plate thickness fluctuation at the material joint will be described. When the material junction is detected in the entry side radiation thickness meter 3 by the above method, the thickness setting values and radiation transmittance correction coefficients of the radiation side thickness meters 3 and 4 on the entry side and the exit side are measured at the timing shown in FIG. Switching and ON / OFF of each AGC operation by the plate thickness control devices 7, 8, 9 are automatically performed based on a command from the command device 11. The timing at which the material joint passes through the positions of the rolling roll 2 and the exit side radiation thickness meter 4 is determined by being tracked by the command device 11. When the material junction passes through the entrance side radiation thickness meter 3, the feedforward AGC device 8 using the entrance side radiation thickness meter 3 is turned off once, and the radiation transmittance correction coefficient and the plate of the entrance side radiation thickness meter 3 are turned off. The thickness setting value is switched from the value of the preceding material to the value of the following material. At the same time, the high mill constant variable control by the mill constant variable control device 7 is operated. This control must be continued until at least the material joint has passed through the rolling roll 2, and thus the rolling roll 2 generated due to a difference in sheet thickness or deformation resistance between the material before and after the joint is obtained. Minimizes side plate thickness variation. When the delivery side nominal thickness (that is, the target thickness) of the rolling roll 2 is different, the rolling load value associated therewith is obtained in advance, and the lock on of the mill constant variable control is performed at the timing when the material joint passes the rolling roll 2. By changing the load, the leading end of the succeeding material can be controlled to a predetermined thickness.

  The feedback AGC device 9 using the exit side radiation thickness meter 4 is turned off once when the material joint is bitten directly under the rolling roll 2, and the material joint has passed the exit side radiation thickness meter 4. At the timing, the thickness setting value and the radiation transmittance correction coefficient of the outgoing radiation thickness meter 4 are switched from the value of the preceding material to the value of the following material, and the control of the feedback AGC device 9 is resumed. Thus, by operating the apparatus shown in FIG. 1 according to the rolling process and control switching shown in FIG. 2, materials having different material characteristics such as low carbon steel plate and nickel alloy plate are welded and joined. Can be continuously rolled without stopping.

  By applying the rolling method of the present invention, even if materials having different material properties due to material thickness or material composition are joined and rolled by continuously passing the joint, the joint is rolled. It is possible to work without causing plate breakage due to plate thickness fluctuations at the time of passing the plate during or after the process. As a result, high productivity and high yield can be achieved, which is extremely effective for cost reduction.

The conceptual diagram which shows an example of the rolling mill to which this invention is applied The conceptual diagram which shows an example of the usage method of the thickness meter and control apparatus of a rolling mill to which this invention is applied

Explanation of symbols

1: Sheet material 2: Rolling roll 3: Incoming radiation thickness gauge 4: Outgoing radiation thickness gauge 5: Rolling load meter
6: Hydraulic reduction device
7: Mill constant variable control device
8: Feed forward AGC
9: Feedback AGC
10: Material joint determination calculation device
11: Command device

Claims (5)

  In the step of rolling a plate material using a rolling stand having at least one pair of rolling rolls, when rolling while continuously conveying a material having a joining portion of a preceding material and a succeeding material having different material properties, A means for detecting the joint by providing a means for detecting the joint before, a means for controlling the thickness of the plate material at the rolling stand by controlling the thickness, and a means for switching the thickness control while tracking the joining position. A rolling method characterized by rolling the sheet so as to have a predetermined sheet thickness by preventing the occurrence of sheet thickness fluctuation before and after the rolled joint by providing and controlling the sheet thickness.   As a means for detecting the joint portion of the material to be rolled, a radiation thickness meter is provided on the entrance side of the rolling roll, the nominal thickness information on the entrance side of the roll before and after the joint portion, and the radiation transmittance of the plate material before and after the joint portion. The rolling method according to claim 1, wherein the joint is automatically detected based on the characteristic information and a thickness measurement value measured by a radiation thickness meter.   When the joint portion of the material to be rolled passes through at least the downstream roll, the high mill constant variable control is activated using the means for controlling the plate thickness, resulting in the material properties before and after the joint portion. 3. The rolling according to claim 1, wherein the thickness of the preceding material and the thickness of the succeeding material after the rolling are controlled so as to be a predetermined thickness by preventing occurrence of a variation in thickness. Method.   Immediately after the joint of the material to be rolled passes through the entry side radiation thickness gauge of the rolling roll, at least the AGC operation using the entry side radiation thickness gauge is stopped and the radiation transmission of the preset preceding material is stopped. After switching the set value of the rate to the set value of the radiation transmittance of the succeeding material, a series of operations for automatically resuming the AGC operation using the entrance side radiation thickness gauge is performed, The rolling method according to any one of claims 1 to 3, wherein the thickness variation of the following material is minimized. Immediately after the joint of the material to be rolled passes through the exit side radiation thickness meter of the rolling roll, at least the AGC operation using the exit side radiation thickness meter is stopped and the radiation transmission of the preset preceding material is stopped. After switching the set value of the rate to the set value of the radiation transmittance of the following material, a series of operations for automatically resuming the AGC operation using the exit side radiation thickness gauge is performed, The rolling method according to any one of claims 1 to 3, wherein the thickness variation of the following material is minimized.