JP2009279638A - Rolling mill and method of controlling tension of rolling mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the stability of production by suppressing the width shrinkage or the like of a material to be rolled by properly changing set tension after starting winding. <P>SOLUTION: A method of controlling the tension of the rolling mill which is provided with winding reels (13a, 13b) for winding the material to be rolled respectively on the inlet side and the outlet side of a hot-rolling mill (21, 22), winds the material around mandrels inside the winding reels and repeatedly rolls the material while applying a prescribed tension to the material between the rolling mill and the winding reels, the tension to be applied to the material is set so as to gradually reduce over prescribed distances from the nose part of the material where tension control is started toward the middle part in both end parts of the material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tension control technique for a rolling mill, and more particularly to a tension control technique for a rolling mill that can suppress the width shrinkage of a material to be rolled and increase the production stability.

  As a hot rolling system for heating a metal at a recrystallization temperature or higher, a system using a stickel rolling mill and a system using a tandem rolling mill are known. In the system using the stickel rolling mill, a winder is disposed on the front and rear surfaces of the rolling mill (entrance side and outlet side of the material to be rolled), and the winder disposed on the front and rear surfaces of the rolling mill and the rolling mill, Rolling is repeated in between.

  In rolling, it is very important to set the tension between the rolling mill and the winders disposed on the front and rear surfaces of the rolling mill. If the tension setting is incorrect, the life of the winder is shortened and the quality of the product (rolled material) is deteriorated.

  As an important item among the indexes representing quality, the width reduction of the material to be rolled is specified. There are various types of material to be rolled, for example, hard material to be rolled and soft material to be rolled. In the rolling of a soft material to be rolled, when a large tension is set, the material to be rolled extends in the rolling direction and the width is reduced. In addition, when a large tension is set in rolling a hard material to be rolled, the material to be rolled is broken. Thus, the tension setting has a great influence on the production stabilization.

  Patent Document 1 discloses a hot rolled steel strip in a tandem rolling system in which a steel strip that is hot-rolled and conveyed at a predetermined speed is wound around a mandrel, and the steel strip is wound around the mandrel while applying tension. In the winding method, when the steel strip tip is wound around the mandrel, the tension applied to the steel strip is set to an initial value smaller than the set tension at the steady state, and then until a predetermined winding state is reached (for example, a predetermined number of windings). Until the predetermined time elapses), the tension applied to the steel strip is gradually increased from the initial value to the set tension at the steady state, and thereby the final stand of the finishing mill It has been shown that necking that occurs at a position immediately after exiting (a portion where the temperature is extremely high at 700 to 900 ° C.) is suppressed.

In Patent Document 2, in a tandem rolling system, a material to be rolled by a rolling mill is wound by a winder via a first pinch roll and a second pinch roll disposed downstream thereof. In this case, it is shown that the tension fluctuation at the time when the material to be rolled exits the first pinch roll is eliminated, and good tension control is performed until the end of winding.
JP-A-11-188422 JP-A-7-53101

  Unlike the tandem rolling system, the Steckel rolling system has a lower temperature distribution of the material to be rolled and a higher middle portion. Therefore, if the tension setting for controlling the tension of the material to be rolled is set high, this set value is too high at the intermediate portion of the material to be rolled, and thus extends in the rolling direction of the material to be rolled, so that good rolling cannot be performed. On the other hand, if the tension is set low, the material to be rolled is not stretched between the rolling mill and the winder, and good rolling cannot be performed.

  In the technique disclosed in Patent Document 1, the tension control is performed by paying attention to time, and is controlled by a command that is gradually increased at a constant change rate with respect to time from the start of winding. For this reason, the winding speed is different every time, and the tension command for the winding length is also different every time. Therefore, a great deal of labor is required to adjust the tension command and time setting depending on the magnitude of the winding speed. Moreover, the technique disclosed in Patent Document 2 is a technique that suppresses a change in winding tension that occurs when the material to be rolled passes through the pinch roll, and is not a technique that focuses on temperature changes. For this reason, it is not an effective control means for suppressing the width shrinkage of the material to be rolled.

  The present invention has been made in view of these problems, and by appropriately changing the set tension after the start of winding, it is possible to increase the production stability by suppressing the width shrinkage of the material to be rolled. Provides tension control technology for rolling mills.

  In order to solve the above problems, the present invention employs the following means.

  A winder for winding the material to be rolled is provided on each of the inlet side and the outlet side of the hot rolling mill, the material to be rolled is wound around a mandrel in the winder, and the above-described rolling machine and winder In a tension control method for a rolling mill that repeatedly rolls a material to be rolled while applying a predetermined tension to the material to be rolled, the tension applied to the material to be rolled is started at both ends of the material to be rolled. It set so that it may reduce gradually over the predetermined distance toward the intermediate part from the front-end | tip part of a to-be-rolled material.

  Since this invention is equipped with the above structure, the set tension | tensile_strength after a winding start can be changed appropriately, production | generation stability can be improved by suppressing the width shrinkage etc. of a to-be-rolled material.

  Hereinafter, the best embodiment will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating a rolling system according to the present embodiment. In FIG. 1, 1 is a computer, 2 is a tension control device for controlling the tension of the winder 3, 3a and 3b are tension setting means, and 4a and 4b are temperature results analysis for analyzing the temperature results collected by the temperature results collection means. Means, 5a, 5b are tension results collecting means for collecting the results of tension applied to the material to be rolled, 6a, 6b are temperature results collecting means for collecting the temperature results in the length direction of the material to be rolled, and 7a, 7b are tensions. Control means 8a and 8b are tension command calculation means, and the tension command value is determined based on the tip set tension F1, intermediate set tension F2, tension gradually decreasing part winding length L, and winding length LACT, which will be described later. Calculate. Reference numerals 9a and 9b denote winding length calculation means for calculating the winding length of the material to be processed.

  In addition, 10a and 10b are winding machine driving devices, 11a and 11b are winding length detecting means, 12a and 12b are temperature detecting means for detecting the temperature of the material to be rolled, 13a and 13b are winding machines, and 14a and 14b are winding machines. A mandrel of the winder, 21 is a work roll, and 22 is a backup roll.

  This rolling system includes a rolling mill constituted by a pair of work rolls 21 and a pair of backup rolls 22, and a pair of winders 13a disposed on the front and rear surfaces (the entrance side and the exit side of the material to be rolled) of the rolling mill, 13b. When the material to be rolled is repeatedly rolled between the rolling mill and a pair of winders, the material to be rolled passes through the rolling mill and enters the winder, and further a mandrel in the winder. Then, the winder winds the material to be rolled while appropriately maintaining the tension between the rolling mill and the winder.

  In the present embodiment, in tension control that starts after the material to be rolled is wound around the mandrel, the tension applied to the material to be rolled is directed from the winding tip of the material to be rolled (tension control start point) to the intermediate portion. It is set so as to gradually decrease over a predetermined distance.

  FIG. 2 is a diagram for explaining the relationship between the winding length of the material to be rolled and the tension applied at each winding position. As shown in FIG. 2, the tension applied to the winding tip (tip set tension) is F1, and a predetermined winding length (tension gradually decreasing portion winding length) L from the winding tip is applied from the intermediate portion. The tension applied at the point (intermediate portion set tension) is set to F2. The tip portion set tension F1, the intermediate portion set tension F2, and the tension gradually decreasing portion winding length L are set by the computer 1 in FIG. 1, and the set values are sent from the computer 1 to the tension control device 2. The tip set tension F1, the intermediate set tension F2, and the tension gradually decreasing part winding length L can be set in the computer 1 according to the steel type, sheet thickness, sheet width, and material to be rolled. .

  FIG. 4 is a diagram for explaining the processing of the temperature record collecting means 6a and 6b for collecting the temperature (temperature record) with respect to the winding length of the material to be rolled. First, the actual temperature collecting means 6a, 6b measures and collects the surface temperature of the material to be rolled via the temperature detecting means 12a, 12b (step S4-1). At this time, the temperature record collecting means calculates the winding length at the temperature measurement position via the winding length detecting means and the winding length calculating means provided in the winders 13a and 13b (step S4-2). ). Next, the temperature record collecting means creates a temperature record by arranging the measured temperature value and the winding length of the measured position in time series (step S4-3), and the created temperature record is used as the temperature record analyzing means 4a, 4b. (Step S4-4).

  FIG. 5 is a diagram for explaining the processing of the temperature performance analysis means 4a, 4b. First, the temperature record associated with the winding length is input from the temperature record collecting means 6a, 6b (step S5-1), and the winding length L (when the temperature record is equal to or greater than a predetermined threshold value) The tension gradually decreasing portion winding length L) is obtained. (Step S5-2). Next, the tension gradually decreasing portion winding length L ′ (or L ″) set in the previous processing is replaced with L (step S5-3), and the replaced winding length L is replaced with the tension setting means 3a. 3b.

  FIG. 6 is a diagram for explaining the processing of the tension setting means 3a and 3b. First, the tension command calculation means 8a and 8b acquire the drive current flowing through the winder drive device 10 shown in FIG. 1, and convert the acquired drive current into tension using the equation (1).

T _ACT = K × Gr / D × I _ACT (1)
Here, T _ACT is the tension, K is the current-tension conversion coefficient, Gr is the gear ratio of the winders 13a and 13b, D is the diameter of the mandrel 14, and I _ACT is the drive current. The obtained tension is collected in the tension result collecting means 5 a and 5 b and inputted to the tension setting means 3.

  Next, the tension gradually decreasing portion winding length L is input from the temperature record analyzing means 4 (step S6-2), and then the tip set tension F1 is calculated from the steel type, sheet thickness, sheet width, and tension record of the material to be rolled. , Intermediate portion set tension F2 and tension gradually decreasing portion winding length L are set. Next, the set values (F1, F2, L) are output to the tension command calculating means 8.

FIG. 3 is a diagram for explaining the tension command calculation means 8a and 8b. First, the tip set tension F1, the intermediate set tension F2, and the tension gradually decreasing part winding length L output from the tension setting means 3a, 3b are taken in (step S3-1), and then the winding length calculating means 9a, The winding length _LACT is acquired from 9b (step S3-2), and these data are applied to the equation (2) to calculate the tension control command value _TREF .

T _REF = (L−L _ACT ) × (F 1 −F 2) / L + F 2 Formula (2)
Here, T _REF indicates a tension control command value, and L _ACT indicates a winding length input from the winding length calculation means 9. Next, the tension control command value T _REF is applied to the equation (3) to convert the tension command into a current command I _REF .

I _REF = 1 / K × D / Gr × T _REF Equation (3)
Here, I _REF indicates a current command (step S3-3).

Next, the calculated current command I _REF takes a difference from the current I _ACT flowing through the winder drive devices 10a and 10b, and the tension control means 7a and 7b take the winder drive device based on the difference. Negative feedback control is performed on 10a and 10b.

  The example in which the tip set tension F1, the intermediate set tension F2, and the tension gradually decreasing part winding length L are set, that is, an example in which attention is paid to the tension has been described above. However, as described above, the tension can be converted into the drive current of the drive device. Therefore, the tip setting tension F1 and the intermediate setting tension F2 can be defined in terms of current. The tension can also be defined by the speed difference between the rolling mill and the winder.

  In the stickel rolling system shown in FIG. 1, rolling is repeated between a rolling mill and a winder. For this reason, when the rolling direction is reversed, the rear end of the material to be rolled when rolled in an arbitrary direction becomes the front end of the material to be rolled. For this reason, when rolling in an arbitrary direction, as described above, based on the temperature record, the winding length, and the tension record, the tension setting means causes the tip tension F1, the intermediate tension F2, and the tip winding. The take length L is acquired, and when the rolling in the arbitrary direction is completed and the rolling direction is reversed, the acquired F1, F2, and L can be sent to the tension command calculating means 8. .

Then, the tension command calculation means calculates the tension control command value T _REF and drives the winder 13. As a result, a tension control command focusing on the temperature is given to the portion from the tip winding portion to the intermediate winding portion of the material to be rolled, that is, the command value is intermediate from the tip portion where the tension control is started. It can be set to gradually decrease over a predetermined distance toward the part, and can be set to be constant in the intermediate part.

  As described above, in hot stickel rolling, the temperature of the intermediate part of the material to be rolled is higher than that of the tip part. For this reason, when the tension | tensile_strength appropriate with respect to the front-end | tip part of a to-be-rolled material is applied to an intermediate part, since tension | tensile_strength is too high, width reduction will arise in a to-be-rolled material. On the other hand, when an appropriate tension is applied to the distal end portion with respect to the intermediate portion, the tension is too low and winding failure is likely to occur.

  In the present embodiment, as the tension set value for the material to be rolled, the two for the tip portion and the intermediate portion are provided, and after the material to be rolled has been subjected to tension control by the winder, depending on the winding length, Computation means for applying a tension that gradually decreases from the tip tension setting value to the intermediate tension setting value is provided.

  Further, the winding length L when the intermediate portion tension setting value is set is set according to the detected temperature of the rolled material, and the intermediate portion (high temperature portion) exceeding the winding length L of the rolled material is an intermediate portion. The tension for the tip portion is set at the tip portion (low temperature portion) of the rolled material length L or less, and further, the tension setting value for the tip portion is the temperature change of the material to be rolled or Decrease gradually according to the distance from the tip. Thereby, the tension | tensile_strength of the intermediate part of a to-be-rolled material and the tension | tensile_strength of a front-end | tip part can be set optimally, and the width reduction of a to-be-rolled material, a fracture | rupture, and a winding failure can be prevented.

It is a figure explaining the rolling system concerning this embodiment. It is a figure explaining the relationship between the winding length of a to-be-rolled material, and the tension applied in each winding position. It is a figure explaining the process of a tension command calculating means. It is a figure explaining the process of a temperature performance collection means. It is a figure explaining the process of a temperature performance analysis means. It is a figure explaining the process of a tension | tensile_strength setting means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Computer 2 Tension control apparatus 3 Tension setting means 4 Temperature results analysis means 5 Tension results collection means 6 Temperature results collection means 7 Tension control means 8 Tension command calculation means 9 Winding length calculation means 10 Winding machine drive device 11 Winding length Detection means 12 Temperature detection means 13 Winder 14 Mandrel 21 Work roll 22 Backup roll

Claims (7)

A winder for winding the material to be rolled is provided on each of the inlet side and the outlet side of the hot rolling mill, the material to be rolled is wound around a mandrel in the winder, and the above-described rolling machine and winder In a tension control method of a rolling mill that repeatedly rolls a material to be rolled while applying a predetermined tension to the material to be rolled,
The tension applied to the material to be rolled is set so as to gradually decrease over a predetermined distance from the front end portion of the material to be rolled to the intermediate portion where tension control is started at both ends of the material to be rolled. A tension control method for a rolling mill. A winder for winding the material to be rolled is provided on each of the inlet side and the outlet side of the hot rolling mill, the material to be rolled is wound around a mandrel in the winder, and the above-described rolling machine and winder In a tension control method of a rolling mill that repeatedly rolls a material to be rolled while applying a predetermined tension to the material to be rolled,
The tension applied to the material to be rolled is gradually decreased over a predetermined distance from the front end portion of the material to be rolled to the middle portion where tension control is started at both ends of the material to be rolled, and is constant at the middle portion. A tension control method for a rolling mill, characterized in that it is set to be In the tension control method of the rolling mill according to claim 1,
The predetermined distance for gradually reducing the tension applied to the material to be rolled is a portion where the temperature record for the winding length of the material to be rolled coincides with a preset temperature threshold from the tip of the material to be rolled where tension control is started. A tension control method for a rolling mill, characterized in that In the tension control method of the rolling mill according to claim 1,
The tension applied at the tip and intermediate portions of the material to be rolled is calculated based on the steel type, sheet thickness, sheet width, and actual results of the applied tension of the material to be rolled. Tension control method. A winder that winds up the material to be rolled and a winder drive device that drives the winder are arranged on each of the entry side and the exit side of the hot rolling mill,
The tip of the material to be rolled is wound around the mandrel in the winder, and the tension control device controls the winder driving device to control the tension applied to the material to be rolled between the rolling mill and the winder. In a rolling mill that repeatedly rolls the material to be rolled while adjusting,
The tension controller sets the tension to be applied to the material to be rolled so as to gradually decrease over a predetermined distance from the tip part where tension control is started to the intermediate part at both ends of the material to be rolled, A rolling mill characterized by being set so as to be constant in an intermediate portion. In the rolling mill according to claim 5,
The predetermined distance for gradually reducing the tension applied to the material to be rolled is a distance from the tip of the material to be rolled to a portion where the temperature record for the winding length of the material to be rolled coincides with a preset temperature threshold value. Features a rolling mill. In the rolling mill according to claim 5,
A rolling machine characterized in that the tension applied at the tip and intermediate portions of the material to be rolled is calculated based on the steel type, sheet thickness, sheet width, and actual results of the applied tension, respectively.

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