JP2006205201A - Rolling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling method capable of reducing the quantity of impairment of the production efficiency as much as possible when passing through a weld part including productivity impairment caused by occurrence of breakage of a plate by adequately controlling the rolling rate when passing the weld part in a rolling mill. <P>SOLUTION: The rolling rate when passing through a weld part in a continuous rolling mill is controlled based on the experienced data during the welding of the weld part and the steel kind data. The rolling rate v when passing through the weld part is preferably controlled so that the quantity F of impairment of the production expressed by the formula (1) is minimized where the probability of breakage of the weld part calculated based on the experienced data during the welding and the steel kind data is denoted as p(v). The formula (1): Quantity F of impairment of production = quantity j(v) of production caused by breakage of plate × probability p(v) of breakage + quantity k(v) of impairment of production caused by deceleration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling method when passing a welded portion by a continuous rolling mill.

  Conventionally, in continuous cold rolling, when the steel plate weldment passes through a rolling mill, the rolling is performed at a low speed, so that rapid tension fluctuations due to the difference in thickness at the welded portion and the strength at the welded portion. The damage caused by the plate breakage due to the shortage was kept low. Here, the speed at which the steel plate welded portion passes through the rolling mill has been determined empirically depending on the welding conditions of the steel plate, for example, the thickness command values of the preceding and succeeding plates, the steel type, and the like.

Furthermore, we also propose a technology to measure the fluctuation of the steel strip surface and the step in the width direction position of the welded part, perform the welded part diagnosis, and control the rolling speed and tension of the welded part based on the diagnosis result. (See Patent Document 1).
JP 2003-136106 A

  In the conventional method of determining the weld passage speed based on the steel sheet thickness command value and steel type information, for example, considering the fact that there is an off-gauge area at the leading end of the steel sheet, it is more than necessary to ensure safety. It had to be decided to roll at a low speed, which significantly hindered production efficiency.

  Patent Document 1 describes that the height of the strip surface of the welded portion and the step in the width direction are measured, and the measurement data is reflected in the control of the rolling speed and tension as welded portion information. However, if only the strip surface height and the step in the width direction are reflected in the rolling speed as the welded part diagnosis result, it is possible to prevent fracture if the rolling speed is sufficiently slowed, but the reduction allowance is reduced. In order to improve the efficiency, it was not sufficient to use only the height difference in the strip surface and the step in the width direction as the result of the weld diagnosis, and there was a limit to improving the production efficiency.

  Further, the above-mentioned Patent Document 1 does not specifically disclose a method for determining the rolling speed of the welded portion, and details are necessary for rolling the welded portion at a sufficiently high speed within a range where the welded portion does not break. There was room for consideration.

  Furthermore, if the rolling speed is sufficiently slow, fracture of the weld can be avoided, but the production efficiency decline due to the reduction of the rolling speed becomes too great. If the speed is increased, the productivity efficiency may be improved in consideration of the total decrease in productivity due to fracture and the decrease in productivity due to reduction in rolling speed.

  Therefore, the present invention can minimize the amount of production efficiency hindrance when passing the weld including the productivity hindrance due to the occurrence of plate breakage by appropriately controlling the rolling speed when passing the weld in the rolling mill. An object is to provide a possible rolling method.

In order to achieve the above object, the present invention has the following features.
[1] A rolling method at the time of passing a welded portion in a continuous rolling machine for steel plates,
A rolling method characterized by controlling a rolling speed when passing through a welded portion in a continuous rolling mill based on actual data and steel type data at the time of welding in the welded portion.
[2] In the above [1], when the rolling speed control is p (v) where the fracture probability of the weld calculated based on the actual data and the steel type data at the time of welding is expressed by the following equation (1): The rolling method characterized by controlling the rolling speed v at the time of passing a weld so that the production inhibition amount F expressed is minimized.

Production inhibition amount F = Production inhibition amount j (v) due to plate breakage × Fracture probability p (v) + Production inhibition amount k (v) due to deceleration (1)
[3] The rolling method according to [2], wherein the fracture probability p (v) is calculated by the following equation (2).

p (v) = (1 + α1) × (1 + α2) × p0 (v) (2)
Here, α1 is a probability correction coefficient determined from the plate thickness and butt level difference of the steel sheet, α2 is a probability correction coefficient determined from the bead height of the weld, the position of the bead of the weld and the welding current, p0 (v ) Represents the fracture probability reference value determined from the steel type data.

  According to the present invention, by appropriately controlling the rolling speed at the time of passing a welded portion in a rolling mill, the production efficiency inhibition amount at the time of passing the welded portion including the productivity hindrance due to the occurrence of plate breakage can be reduced as much as possible. A possible rolling method is provided.

  Hereinafter, an example of the best mode for carrying out the present invention will be described.

  FIG. 1 is a diagram showing an example of a configuration of a continuous rolling line to which the rolling method of the present invention is applied. In FIG. 1, a coil 2 from the upstream side, a welding machine 3, and a looper 4 are sequentially arranged on the inlet side of the rolling mill 1, and the rolled steel plate is used as the outgoing coil 5 on the downstream side of the rolling mill 1. It is wound up.

  In the welding machine 3, steel plates having different materials and plate thicknesses are welded to each other, and the steel plates are continuously fed into the rolling mill 1. At this time, a steel plate is stored in the looper 4, and the steel plate is always fed into the rolling mill 1 at a predetermined speed.

  FIG. 1 shows a case where a tandem rolling mill in which five rolling stands from 1 to 5 are sequentially used is used as the rolling mill 1, but the rolling method according to the present invention is applied. The rolling mill is not limited to this case, and other types of rolling mills can be similarly applied.

  In the vicinity of the welding machine 3, a performance data collecting means 6 for collecting performance data at the time of welding is installed. Here, in the performance data collecting means 6, when the butt welding of the leading plate tail end portion and the trailing plate tip portion is performed in the welding machine 3, the difference in the plate thickness and butt level of each steel plate, that is, the preceding plate plate Amount of positional deviation in the thickness direction between the center of thickness and the thickness of the succeeding plate, the bead height of the welded portion, and the position of the bead of the welded portion (deviation amount of the bead position from the intermediate position between the preceding plate and the succeeding plate) Collect actual data such as welding current. The plate thickness of the steel plate can be measured by, for example, a plate thickness meter 7 provided in the vicinity of the welding machine 3, and the welding current can be measured by, for example, a welding ammeter provided in the welding machine 3. The butt level difference, the bead height at the time of welding, and the position of the bead at the time of welding, for example, as shown in FIG. It is possible to measure by using a method of measuring by image analysis with the image analysis device 10 from an image obtained by photographing the reflected light with the CCD camera 9, that is, a shape measuring technique by a light cutting method. Information on the butt level difference, the bead height at the time of welding, and the position of the bead at the time of welding obtained by image analysis by the image analysis device 10 is collected and stored by the result data collecting means 6.

  In such an apparatus configuration, the rolling method according to the present invention controls the rolling speed when passing through the welded part in the continuous rolling mill based on the actual data and steel type data at the time of welding in the welded part.

  FIG. 3 shows an example of a processing flow for determining the rolling speed in the rolling method according to the present invention. As shown in FIG. 2, first, in the fracture probability calculation step 20, the fracture probability p (v) at the weld is calculated based on the actual performance data and steel type data collected by the actual performance data collecting means 6. The steel grade data refers to data relating to the material of each of the preceding plate and the following plate, such as the plate width and the steel grade, for example, data given as command information from the master controller 11 or the like that controls the rolling line. Can be used.

  Here, as the fracture probability p (v), a value calculated by the following equation (2) can be used.

p (v) = (1 + α1) × (1 + α2) × p0 (v) (2)
Here, α1 is a probability correction coefficient determined from the plate thickness and butt level difference of the steel sheet, α2 is a probability correction coefficient determined from the bead height of the weld, the bead position of the weld and the welding current, p0 (v ) Represents the fracture probability reference value determined from the steel type data, and is set as a function of the rolling speed v.

  The probability correction coefficients α1 and α2 are set to 0 (zero) in the case of the reference welding state in which the fracture probability reference value p0 (v) is determined, and the reference welding state and the actual welding state are determined during the welding. Judgment is made by comparing actual data and steel type data, and the value is determined by plus or minus. Note that the probability correction coefficients α1 and α2 are values that can be appropriately changed depending on the equipment configuration, operation conditions, and the like, and are preferably updated as appropriate depending on the operation results.

  Next, in the welded part rolling speed determination step 30, the production inhibition amount F expressed by the following equation (1) is minimized by using the fracture probability p (v) calculated in the fracture probability calculation step. Next, the rolling speed v when passing through the weld is determined.

Production inhibition amount F = Production inhibition amount j (v) due to plate breakage × Fracture probability p (v) + Production inhibition amount k (v) due to deceleration (1)
Here, the production inhibition amount j (v) due to plate breakage and the production inhibition amount k (v) due to deceleration are functions that vary depending on the rolling speed v, and the production inhibition amount j (v) due to plate breakage is determined by the rolling speed v. The value increases as the speed increases, and the production inhibition amount k (v) due to the deceleration is a value that increases as the rolling speed v decreases. That is, the first term on the right side of the above equation (1) increases as the rolling speed v increases, and the second term increases as the rolling speed v decreases.

  Thus, in this weld zone rolling speed determination step, if the fracture probability p (v) is given, the production efficiency hindrance when passing through the weld zone can be determined from the above equation (1) while preventing the occurrence of plate fracture. It becomes possible to determine the passing speed of the welded part in the rolling mill so as to reduce it as much as possible.

  In the above-described method, the fracture probability p (v) and the rolling speed v when passing through the weld are determined by calculating the above formulas (2) and (1). The relationship between the actual data and the steel type data at the time of welding may be obtained, and each may be obtained by a table lookup method.

  When the rolling speed of the welded part is determined by the welding part rolling speed determining step, the value is transmitted to a master control device that controls the rolling line, and the rolling speed is reached immediately before the welded part reaches the rolling mill. Thus, the rolling speed of the weld is controlled. Here, the position in the rolling line of the welding part of a steel plate can be grasped | ascertained by tracking of a welding point. Further, the master controller 11 creates a speed pattern in each rolling stand of the rolling mill 1 on the basis of the rolling speed determined value of the welded portion, and controls the number of rotations of the driving motor of each rolling stand, etc. Control is performed so as to achieve a predetermined rolling speed.

  Thus, the present invention is not only based on the command information such as the steel type data, but actually determines the rolling speed when passing the weld based on the actual data and the steel type data at the time of welding, so the welding quality is good. In some cases, that is, when the risk of breakage is small, rolling can be performed at high speed, and operation can be performed without impeding efficiency. Moreover, when welding quality is bad, generation | occurrence | production of a fracture | rupture can be reduced by making the rolling speed at the time of a welding part passage slower, and also it becomes possible to improve efficiency and a yield.

It is a figure which shows an example of a structure of the continuous rolling line to which the rolling method of this invention is applied. It is a figure which shows an example of the measuring method of the butt level difference in a welding part, the bead height at the time of welding, and the position of the bead at the time of welding based on this invention. It is a figure which shows an example of the processing flow for determining the rolling speed in the rolling method which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling machine 2 Supply side coil 3 Welding machine 4 Looper 5 Outlet coil 6 Result data collection means 7 Plate thickness meter 8 Laser beam irradiation apparatus 9 CCD camera 10 Image analysis apparatus 11 Master controller

Claims (3)

It is a rolling method at the time of passing a weld in a continuous rolling machine of a steel plate,
A rolling method characterized by controlling a rolling speed when passing through a welded portion in a continuous rolling mill based on actual data and steel type data at the time of welding in the welded portion. When the rolling speed control is p (v), where the fracture probability of the weld is calculated based on the actual data and steel type data at the time of welding, the production inhibition amount F expressed by the following equation (1) is minimum. The rolling method according to claim 1, wherein the rolling speed v at the time of passing through the welded portion is controlled so that
Production inhibition amount F = Production inhibition amount j (v) due to plate breakage × Fracture probability p (v) + Production inhibition amount k (v) due to deceleration (1) A rolling method, wherein the fracture probability p (v) is calculated by the following equation (2).
p (v) = (1 + α1) × (1 + α2) × p0 (v) (2)
Here, α1 is a probability correction coefficient determined from the plate thickness and butt level difference of the steel sheet, α2 is a probability correction coefficient determined from the bead height of the weld, the position of the bead of the weld and the welding current, p0 (v ) Represents the fracture probability reference value determined from the steel type data.

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