JP2013180316A - Method of predicting time in hot rolling, and method of predicting thermal crown of rolling roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise the accuracy of prediction of the thermal crown of a rolling roll in hot rolling.SOLUTION: At the timing when performing the setting of a rolling mill prior to the bite of the tip of a material to be rolled when performing the setting of the rolling mill in hot rolling, a rolling time of a previous material to be rolled is predicted by using: a pitch at which a sensor, which is situated in a position near the rolling mill among sensors which have already passed a corresponding material to be rolled, detects the corresponding material to be rolled and the previous material to be rolled thereof; and the coil length of the previous material to be rolled. Also, an idle time, from the completion of rolling of the previous material to be rolled until the start of the rolling of the corresponding material to be rolled, is predicted by using the rolling time and the pitch, and those times is used for predicting the thermal crown of a rolling roll.

Description

  The present invention relates to a method for predicting the rolling time of a material to be rolled and the idle time after rolling when setting a rolling mill in hot rolling, and a method for predicting the thermal crown of a rolling roll.

  Conventionally, when hot rolling is performed, a thermal crown of a rolling roll is predicted. The thermal crown is a physical quantity related to the thermal expansion of the rolling roll due to heat from the material to be rolled. If this thermal crown can be accurately predicted prior to rolling and the predicted result can be reflected in the control of hot rolling, it is possible to make appropriate settings for the rolling mill, and hot rolling can be performed with high accuracy. It can be carried out. In order to accurately predict the thermal crown, it is necessary to accurately predict the rolling time of the material to be rolled and the idle time after rolling.

  As a conventional technique for predicting a thermal crown, for each rolling roll, one or more of density, specific heat, thermal conductivity, and linear expansion coefficient are reflected in the thermal crown prediction calculation formula (see Patent Document 1). ) And a prediction method (see Patent Document 2) in which a thermal crown after the rolling of the corresponding rolled material is calculated every arbitrary time before rolling is started.

JP 2004-306051 A JP 2009-061484 A

  However, all of the above conventional methods predict the thermal crown of the hot rolling roll prior to the biting of the material to be rolled, and therefore the results of the rolling time of the previous material to be rolled and the results of the idle time after rolling. There was still room to improve the prediction accuracy of the thermal crown.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rolling time and idle time prediction method and a thermal crown prediction method that solve the above-mentioned problems.

  The time prediction method in the hot rolling of the present invention that achieves the above object is applicable at the timing of setting the rolling mill prior to the biting of the tip of the material to be rolled when setting the rolling mill in the hot rolling. Of the sensors that have already passed through the material to be rolled, the pitch at which the sensor located near the rolling mill detects the material to be rolled and the material to be rolled immediately before and the coil length of the material to be rolled immediately before Is used to predict the rolling time of the previous rolled material, and from the rolling end of the previous rolled material to the start of rolling of the rolled material using the rolling time and the pitch. It is characterized by predicting idle time.

  Moreover, the thermal crown prediction method in the hot rolling of the present invention that achieves the above object is the rolling time of the previous rolled material predicted by the time predicting method of the present invention and the previous rolled material. A thermal crown of a rolling roll that hot-rolls the material to be rolled is predicted using an idle time from the end of rolling to the start of rolling of the material to be rolled.

  According to the present invention, since the performance of the sensor close to the rolling mill is used among the sensors capable of acquiring the performance of the material to be rolled, the rolling time and rolling of the material to be rolled immediately before the corresponding material to be rolled are used. The subsequent idle time can be accurately predicted and calculated. And the prediction precision of the thermal crown of a rolling roll can be improved by using the said estimated calculation time.

  In the time prediction method in the hot rolling according to the present invention of the present invention, the rolling mill is the last finishing rolling mill among a plurality of finishing rolling mills, and the sensor is the last rolling mill among the plurality of rough rolling mills. The load relay provided in the rough rolling mill is preferable in terms of equipment cost because an existing load relay is used as a sensor.

Explanatory drawing which shows the thermal crown prediction timing at the time of the rolling start of the said rolling material in one Example of the thermal crown prediction method in the hot rolling of this invention using one Example of the time prediction method in the hot rolling of this invention It is. It is explanatory drawing which shows the prediction method of the idle time based on the rolling time and the sensor on pitch which considered acceleration / deceleration of the rolling speed in the time prediction method of the said Example. It is a relationship diagram which shows the relationship between a rolling order and rolling time by contrasting the prediction rolling time by the time prediction method of the said Example, and performance rolling time. It is a relationship diagram which shows the relationship between rolling order and idle time by contrasting the prediction idle time by the time prediction method of the said Example, and performance idle time. The amount of thermal crown calculated by the thermal crown prediction method of the above embodiment using the predicted idle time by the time prediction method of the above embodiment and the actual idle time and the amount of thermal crown calculation by using the actual time are compared with each other in the rolling order. It is a relationship diagram which shows the relationship with the thermal crown calculation amount.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a hot strip mill (continuous hot rolling mill) in one embodiment of the thermal crown prediction method in the hot rolling of the present invention using the embodiment of the time prediction method in the hot rolling of the present invention. FIG. 2 is an explanatory diagram showing the thermal crown prediction timing at the start of rolling of the material to be rolled in FIG. 2, and FIG. 2 shows the rolling time and sensor-on-pitch considering the acceleration / deceleration of the rolling speed in the time prediction method of the above embodiment It is explanatory drawing which shows the prediction method of the idle time based on.

  Here, the hot strip mill (continuous hot rolling mill) is composed of rough rolling steel strips 2 and 3 having a thickness of several tens of mm that are roughly rolled by five rough rolling mills 1 (only the last one is shown in the figure). As shown by the arrows in the figure, in the figure, the steel strip is sent to the right and finished to a thickness of several millimeters by seven finish rolling mills 4, and the end of the steel strip in the finish rolling mill 4 is bitten during the finish rolling. Crop cutting is performed in the crop shear 5 on the entry side of the finish rolling mill 3 in order to prevent inferior defects and poor quality at the end of the steel strip due to the coil. The last rough rolling mill 1 is provided with a load relay 6. The load relay 6 outputs an ON signal when the rough rolling mill 1 starts rough rolling of the rough rolled steel strip.

  The time prediction method of the above embodiment in this hot strip mill will be described. As shown in FIG. 1, consider a case where the last finish rolling mill 4 is set at the timing when the current material 3 as the material to be rolled passes through the last rough rolling mill 1. In addition, the to-be-rolled material 2 to set is called this material (corresponding to-be-rolled material), and the to-be-rolled material 3 before this material is called a front material.

  When calculating the thermal crown at the start of rolling of the material 2, the rolling time and rolling of the material to be rolled before the front material 3 used for predictive calculation of the thermal crown from the roll change to the start of rolling of the front material 3 Since the actual time can be obtained for the subsequent idle time, the actual time is used. Regarding the rolling time of the front material 3, the rolling speed pattern of the front material 3 in consideration of acceleration / deceleration shown in FIG. Since the time integral of the rolling speed becomes the coil length using the expected coil length based on the dimensional difference from the finished rolled material, the rolling time is calculated so as to satisfy the following equation (1).

但し、Ｌ:前材の予想コイル長、tr:前材の圧延時間、v(t):前材の圧延速度である。

Where L is the expected coil length of the front material, tr is the rolling time of the front material, and v (t) is the rolling speed of the front material.

  The idle time tc from the end of finish rolling of the front material 3 to the start of finish rolling of the current material 2 is usually equal to the time from the end of rolling of the front material 3 in the rough rolling to the start of rolling of the current material 2. The time pitch from the time when the load relay 6 is turned on with respect to the front material 3 to the time when the load relay 6 is turned on with respect to the current material 2 is assumed to be tp and is calculated by the following equation (2).

但し、tc:アイドル時間、tp:センサーオンピッチ、tr:圧延時間である。

However, tc: idle time, tp: sensor on pitch, tr: rolling time.

These are summarized as follows.
(a) The rolling time tr of the front material 3 is obtained from the expected delivery coil length L and the rolling speed v (t).
(b) The sensor on-pitch tp is obtained from the load relay on time of the front material 3 and the load relay on time of the material 2.
(c) The idle time tc is obtained from the sensor on pitch tp and the rolling time tr of the front material 3.

  In the above embodiment, since the case where the final finishing mill 4 is set at the timing when the last rough rolling mill 1 is exited is considered, the finishing mill is a sensor that can acquire the results for the material 2. Since the load relay 6 of the last rough rolling mill 1 was the closest sensor, the load relay 6 was used. However, the present invention is not limited to this, and an HMD that detects a rough rolled material on the entry side of the crop shear 5 ( Hot Metal Detector may be used as a sensor.

  By using the rolling time tr and the idle time tc of the front material 3 thus predicted and calculated, in the thermal crown prediction method in the hot rolling of this embodiment, the rolling time of the material 2 at the start of rolling is as follows. Predict thermal crown.

  The prediction method itself used here is a known method, and details thereof are described in, for example, Patent Document 1, so only a brief description is given here. That is, in this embodiment, the rolling roll is regarded as a cylinder, virtually divided by a cutting plane, divided into three virtual meshes in the radial direction and 46 in the axial direction, and the following (3 ) Is two-dimensionally differentiated, and a representative temperature for each mesh is calculated for each predetermined time increment.

但し、θ：各メッシュ毎の代表温度、tr：圧延時間、tc：アイドル時間、kr：圧延時ロール熱伝達係数、kc：アイドル時ロール熱伝達係数、ρ：ロール密度、c：ロール比熱、r：ロール半径方向座標、x：ロール幅方向座標である。 This equation (3) can be modified as follows.

Where θ: representative temperature for each mesh, tr: rolling time, tc: idle time, kr: roll heat transfer coefficient during rolling, kc: roll heat transfer coefficient during idling, ρ: roll density, c: roll specific heat, r : Roll radius direction coordinate, x: roll width direction coordinate.

  In the formula transformed in this way, the rolling time tr and idle time tc of the front material 3 predicted and calculated in the previous embodiment, and the rolling time and idle time of the previous rolled material that have been found in the actual results, Is applied to obtain the temperature of each part of the rolling roll, and then the difference from the temperature of each part of the rolling roll before incorporation into the rolling mill is obtained. The linear expansion coefficient is added to the temperature difference as shown in the following equation (5). To calculate the thermal crown per radius of the mill roll.

但し、ｕ：半径当りサーマルクラウン、β：線膨張係数、θ_０：圧延機への組み込み前の圧延ロール各部の温度、ｒｗ：圧延ロール半径である。

Where u: thermal crown per radius, β: linear expansion coefficient, θ ₀ : temperature of each part of the rolling roll before incorporation into the rolling mill, rw: rolling roll radius.

  Therefore, according to the time prediction method of the present embodiment, the results of the load relay 6 of the last rough rolling mill 1 that is closest to the last finish rolling mill 4 among the sensors that can acquire the results of the material to be rolled are used. Thus, the rolling time of the material to be rolled 3 immediately before the rolling target 2 and the idle time after rolling can be accurately predicted and calculated. And according to the thermal crown prediction method of the present embodiment, the prediction accuracy of the thermal crown of the rolling roll of the final finish rolling mill 4 can be improved by using the predicted calculated rolling time and idle time after rolling. Can do.

  FIG. 3 is a relationship diagram showing the relationship between the rolling order and the rolling time by comparing the predicted rolling time and the actual rolling time by the time predicting method of the above embodiment, and FIG. 4 is the time predicting method of the above embodiment. FIG. 5 is a graph showing the relationship between the rolling order and the idle time by comparing the predicted idle time and the actual idle time according to the above, and FIG. 5 uses the predicted idle time and the actual idle time according to the time prediction method of the above embodiment. It is a relationship diagram which shows the relationship between a rolling order and a thermal crown calculation amount by contrasting the thermal crown calculation amount by the thermal crown prediction method of the said Example and the thermal crown calculation amount using performance time.

  As shown in FIGS. 3 and 4, it was confirmed that the rolling time and idle time according to this example were not significantly different from the actual values. Further, as shown in FIG. 5, it was confirmed that there was no significant difference between the thermal crown amount calculated using the predicted time according to this example and the thermal crown amount calculated using the actual time. As a result, it was confirmed that the rolling time and the idle time in this example were highly accurate, and as a result, the thermal crown prediction calculation was also highly accurate.

  Although the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described examples, and can be appropriately changed within the scope of the claims as required. The sensor closest to the finish rolling mill among the sensors that can be obtained is not limited to the load relay 6 of the last rough rolling mill 1 or the HMD that detects the rough rolled material on the entry side of the crop shear 5, A sensor provided at a position closer to the finish rolling mill 4 may be used as long as the time required for the above calculation can be secured from the sensor on of the material to the start of rolling in the final finish rolling mill 4.

  Thus, according to the present invention, since the results of the sensor close to the rolling mill are used among the sensors capable of acquiring the results for the material to be rolled, the rolling time of the material to be rolled immediately before the corresponding material to be rolled and The idle time after rolling can be accurately predicted and calculated. And the prediction precision of the thermal crown of a rolling roll can be improved by using the said estimated calculation time.

1 Coarse rolling mill 2 Rolled steel strip (this material)
3 Rolled steel strip (previous material)
4 Finishing rolling mill 5 Crop shear 6 Load relay

Claims (3)

  When setting the rolling mill in hot rolling, at the timing of setting the rolling mill prior to the biting of the rolling material tip, the sensor that has already passed the rolling material is positioned near the rolling mill. A certain sensor predicts a rolling time of the previous rolled material using a pitch at which the corresponding rolled material and the previous rolled material are detected, and a coil length of the previous rolled material. And a time prediction method in hot rolling characterized by predicting an idle time from the end of rolling of the previous rolled material to the start of rolling of the rolled material using the rolling time and the pitch . The rolling mill is a final finishing rolling mill among a plurality of finishing rolling mills,
The time prediction method in hot rolling according to claim 1, wherein the sensor is a load relay provided in the last rough rolling mill among a plurality of rough rolling mills.   The rolling time of the previous rolled material predicted by the time prediction method according to claim 1 or 2 and the idle time from the end of rolling of the previous rolled material to the start of rolling of the rolled material are used. And predicting a thermal crown of a rolling roll that hot-rolls the material to be rolled.

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