JPH0318965B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling plate thickness during sheet passing in a continuous hot rolling mill, and particularly for passing a rolled material through a hot continuous rolling mill, which is suitable for application to a continuous hot rolling mill. This paper relates to improvements in the method for controlling plate thickness during production.

[Conventional technology]

In order to obtain a good sheet thickness from the tip of the coil when passing through a hot continuous rolling mill, such as a hot continuous finishing rolling mill, it is necessary to set up the rolling position of each stand to an appropriate value in advance. There is. Traditionally, the rolling reduction setting for each stand was done by analogy with past rolling data, operator experience, etc., but recently rolling theory formulas (rolling load formula, deformation resistance formula, rolled material temperature formula, etc.) have been used. Increasingly, this is being done by computers, making full use of this. However, even if the reduction of each stand is set by theoretical calculations, it is difficult to say that they are actually the optimum values, and it is not always possible to obtain a good plate thickness from the tip of the coil. it is,
There are problems with accuracy in the theoretical formula used for setup calculations, and the temperature of the rolled material at the entrance of the finishing mill, detected by a radiation thermometer, etc., or gauge, which is necessary as an input condition for calculations. This is because there is a detection error in the plate thickness calculated using a meter formula or the like. Of these, the former theoretical formula can be improved by collecting actual rolling data, but it is currently difficult to measure the temperature and plate thickness of the rolled material at the entrance of the finishing mill with high precision. It is. In particular, when it comes to temperature measurement, not only are there many discrepancies between the measured value and the actual value due to problems such as the surface properties of the rolled material or water riding, but also the average value in the thickness direction is required for setup calculations. The only way to estimate this was from the measured surface temperature. From the above points, in order to obtain a good plate thickness from the tip of the coil, it is necessary to correct the rolling position of each stand to an appropriate value during threading. As a countermeasure for this, a gauge meter that has almost no delay in detecting plate thickness is used.
It is possible to use AGC (Automatic Gauge Control) from the time of sheet threading, but since it is feedback control, the responsiveness of the rolling down device becomes a problem, making it difficult to obtain a good sheet thickness from the tip of the coil. Another method is to detect the rolling load deviation of the front stage stand, calculate the deformation resistance deviation from this, and, assuming that the deformation resistance deviation is the same at the rear stage stand, change the rolling position of the rear stage stand within a short time. A method of correcting this has been proposed (Japanese Patent Publication No. 51-2061). However, deformation resistance is a complex function of rolled material temperature, reduction rate, and chemical composition.
It was difficult to predict the deformation resistance of the rear stand from the deformation resistance of the front stand. On the other hand, the inventors have already proposed in Japanese Patent Application No. 58-156044 to solve the above problem that when passing the material through a continuous rolling mill, the tip of the material to be rolled is placed in the i-th stand from the upstream. At the time of biting, the rolling load deviation and rolling position deviation of the i-th stand are detected, and the temperature deviation and input of the material to be rolled at the next stage i+1 stand are determined based on the detected values of the rolling load deviation and rolling position deviation. The side plate thickness deviation is predicted, and the correction amount of the rolling position of the i+1st stand is calculated based on the temperature deviation and the predicted value of the entrance side plate thickness deviation, and the rolling position of the i+1th stand is calculated before the tip of the material to be rolled is bitten by the i
We have proposed a method for controlling sheet thickness during sheet threading in a continuous rolling mill, which is characterized by correcting the rolling position of the +1 stand. This method quickly corrects the rolling position of the i+1st stand using only the rolling load deviation and rolling position deviation when the tip of the material to be rolled is bitten by the i-th stand. This is a very effective control method when there is no position detection error, and has the advantage of quick response, reliable reduction correction, and the ability to obtain the target thickness from the tip of the coil. has. However, if there is a detection error in the rolling load or the rolling position, there is a problem in that the control becomes unstable.

[Problems to be solved by the invention]

The present invention has been made to solve the above-mentioned conventional problems, and is capable of quick response, reliable correction of rolling reduction, and stable control even when there is a detection error in rolling load or rolling position. It is an object of the present invention to provide a method for controlling plate thickness during rolling in a continuous hot rolling mill, which can reliably obtain a target plate thickness from the tip of a coil.

[Means to solve the problem]

As shown in FIG. 1, when the material to be rolled is passed through a continuous hot rolling mill, the tip of the material to be rolled is placed in the j-th (1≦j≦i) stand from the upstream. At the time when the j-th stand is bitten, the rolling load deviation and rolling position deviation of the j-th stand are detected, and the j-th stand is calculated from the detected values of the rolling load deviation and rolling position deviation.
The temperature deviation and outlet side plate thickness deviation of the rolled material at the stand are calculated, and the i+th
The temperature deviation and entry side plate thickness deviation of the rolled material at one stand are predicted, and the rolling position correction amount of the i+1th stand is calculated from the predicted values of the temperature deviation and entry side plate thickness deviation, and the tip of the rolled material is The above object is achieved by correcting the lowering position of the i+1st stand before it is caught in the i+1st stand.

[Effect]

The present invention was made based on the fact that the main cause of plate thickness variation in continuous hot finish rolling is temperature variation, and that this temperature variation can be recognized as rolling load variation. The plate pressure control method according to the present invention when the tip end 10A is bitten by the roll 12i of the i-th stand will be described with reference to FIG. That is, immediately after the tip 10A of the material to be rolled 10 is bitten by the roll 12 _j of the j-th stand (1≦j≦i), the rolling load deviation ΔP _j representing the deviation from a predetermined target value is also reduced. The positional deviation ΔS _j is
Detected by a roll down position detector (not shown) provided in the load cell 14 _j and roll down position control device 16 _j of the j-th stand, respectively, and the computer 20
etc., a predetermined calculation is performed to calculate the reduction correction amount ΔS _i+1 ^* of the i+1st stand, and the reduction position control device 16 _{i+1 of the i+1st stand adjusts its roll before the tip of the i+1st stand bites into the i+1st} stand. 12 Change the lowering position of _i+1 . In the figure, 22 is a looper. Specifically, the rolled material temperature deviation ΔT _i ^C immediately after the tip 10A of the rolled material 10 is bitten by the i-th stand is the rolling position deviation ΔS _i and the rolling load deviation ΔP _i
It is calculated from the detected value using the following formula. ΔT _i ^C = [ΔP _i − {(∂P/∂H)i ×Δh _i-1 ^G + (∂P/∂S)i ×ΔS _i }]/(∂P/∂T)i ……(1 ) Here, the subscript i is the stand number, (∂P/∂H),
(∂P/∂S) and (∂P/∂T) are rolling load P
The influence coefficient of the entry side plate thickness H, the rolling position S, and the temperature of the rolled material T, Δh ^G is the gauge meter plate thickness deviation. In order to obtain the reduction correction amount ΔS _i+1 ^* , it is necessary to predict the temperature deviation ΔT _i+ 1 ^P of the rolled material and the thickness deviation ΔH i+1 ^P on the entrance side when the tip of the rolled material is bitten by _{the i+1st} stand of the next stage. be. Of these, the temperature deviation ΔT _i+1 ^P of the i+1st stand can be predicted only from the temperature deviation ΔT _i ^C of the i-th stand, but the temperature deviation ΔT i+1 P of the i-th stand
It can also be predicted from each of the temperature deviations ΔT ₁ ^C to ΔT _i-1 ^C between the first stand and the i-1 stand, which have already been calculated when the tip is bitten into the i-1 stand. That is, the temperature deviation ΔT _i+1 ^P of the i+1th stand can be predicted by the following equation. ΔT _i+1 ^P =α ₁・f _T1・ΔT ₁ ^C ＋α ₂ ×f _T2・ΔT ₂ ^C +……+α _i・f _Ti・ΔT _i ^C ……(2) f _T1 =T ₁゜/T _{i +1}゜f _T2 = T ₂゜/T _i+1゜ ...(3) f _Ti = T _i゜/T _i+1゜ Here, T゜ is the temperature of the rolled material in the standard rolling schedule, α is a weighting constant that satisfies the relationship α ₁ +α ₂ +...+α _i =1. For example, rolling load deviation ΔP _i and rolling position deviation ΔS _i
If _there ^is no _error in _the detection ^of =α ₂ =…=α _i-1 =0, α _i =1 (Japanese Patent Application No. 58-156044). however,
If there is a large possibility of detection error of rolling load deviation ΔP _i and rolling position deviation ΔS _i ,
Using all of the stand temperature deviation ΔT ₁ ^C ~ ΔT _i ^C ,
Predicting the temperature deviation ΔT _i+1 ^P of the i+1th stand is more stable in terms of control. That is, when predicting the temperature deviation ΔT _i+1 ^P of the i+1st stand,
Which of the temperature deviations ΔT ₁ ^C to _{T i} ^C to use from stand to i-th stand is determined by the operating conditions of the target continuous hot finishing rolling mill (especially the detection accuracy of rolling load deviation ΔP _i and rolling position deviation ΔS _i) ) should be determined by On the other hand, the entrance side plate thickness deviation ΔH _i+1 of the i+1st stand
Since ^P is equal to the thickness deviation Δh _i ^G on the exit side of the gauge meter of the i-th stand, it can be determined by the following equation. ΔH _i+1 ^P =Δh _i ^G =ΔS _i +ΔP _i /M _i (4) Here, M is Mill's constant. Based on the temperature deviation ΔT _i+1 ^P of the i+1th stand and the inlet thickness deviation ΔH _i+1 ^P of the i+1st stand predicted in this way, the exit side plate thickness deviation Δh _i+1 ^P of the i+1st stand is calculated by the following formula. calculated. Δh _i+1 ^P = {(∂P/∂T)i・ΔT _i+1 ^P +(∂P/∂H)i・ΔH _i+1 ^P }/M _i+1 ……(5) Therefore, The reduction correction amount ΔS i+ ₁ ^* to make the outlet side plate thickness deviation Δh _i+1 ^P of the i+1th stand zero is determined by the following equation. ΔS _i+1 ^* = − [{M _i+1 − (∂P/∂h) _i+1 } /M _i+1 ]×Δh _i+1 ^P ……(6) Here, (∂P/∂h) h) is the influence coefficient of the exit plate thickness h on the rolling load P. In summary, the present invention detects the rolling load deviation ΔP _i and rolling position deviation ΔS _i when the tip 10A of the material to be rolled 10 is bitten by the i-th stand, and The material temperature deviation ΔT _i+1 ^P is predicted from the above equations (1) to (3), the entrance plate thickness deviation ΔH _i+1 ^P is predicted from the above equation (4), and then the above (5), (6)
Using the formula, the reduction correction amount ΔS _i+1 ^* of the i+1-th stand is determined, and the reduction of the i+1-th stand is corrected before the tip 10A is bitten by the i+1-th stand.

【Example】

In the 7-stand continuous hot finishing rolling mill, the weighting constant α ₁ =α ₂ =…=α _i = in the above equation (2)
1/i (hereinafter referred to as the method of the present invention), the plate thickness accuracy (standard deviation of the final exit side plate thickness deviation) at the tip of the coil is compared with the conventional method without control and α ₁
=…=α _i-1 = 0, α _i = 1.0 Patent application 1984-156044
Table 1 below shows the results of a comparison of the plate thickness accuracy at the tip of the coil using the method proposed in (hereinafter referred to as the comparative method).

[Table] As is clear from Table 1, according to the present invention,
Compared not only to conventional methods but also to comparative methods, this method is particularly effective for thin materials, and thickness defects at the tip of the coil are significantly improved, making it possible to perform rolling with a good yield.

【Effect of the invention】

As explained above, according to the present invention, the response is quick and the reduction can be reliably corrected, and furthermore,
Stable control can be performed even if there is a detection error in the rolling load or rolling position. Therefore, there is an excellent effect that the target plate thickness can be reliably obtained from the tip of the coil.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the method for controlling plate thickness during sheet passing in a hot continuous rolling mill according to the present invention, and FIG. 2 is a flowchart showing a hot continuous finishing rolling mill for explaining the principle of the present invention. FIG. 2 is a block diagram showing the configuration of the plate thickness control device of FIG. 10... Material to be rolled, 10A... Tip, 14 _i ...
...Load cell, ΔP _i ...Rolling load deviation, 16 _i ...
Rolling position control device, ΔS _i ... Rolling position deviation, 20
... Calculator, ΔS _i+1 ^* ... Rolling correction amount, ΔT _i ^C ...
Temperature deviation of rolled material (calculated value), Δh ^G ... Gauge meter exit plate thickness deviation (calculated value), ΔT _i+1 ^P ... Temperature deviation of rolled material (predicted value), ΔH _i+1 ^P ...Input Side plate thickness deviation (predicted value).

Claims (1)

[Claims] 1. When passing a material to be rolled through a hot continuous rolling mill, the leading end of the material to be rolled is the jth point from the upstream (1≦j≦
At the time when it is bitten by the stand of i),
Detect the rolling load deviation and rolling position deviation of the stands, calculate the temperature deviation and outlet side plate thickness deviation of the rolled material at the j-th stand from the detected values of the rolling load deviation and rolling position deviation, Predict the temperature deviation and entry side plate thickness deviation of the rolled material at the i+1st stand from the calculated values of the stand temperature deviation and exit side plate thickness deviation of the i-th stand, and predict the temperature deviation and entry side plate thickness deviation of the rolled material at the i+1th stand, and i
During sheet rolling in a hot continuous rolling mill, the rolling position correction amount of the +1 stand is calculated, and the rolling position of the i+1st stand is corrected before the tip of the material to be rolled is bitten by the i+1st stand. thickness control method.