JPH0573485B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for calculating a torque arm in continuous hot rolling.

(Prior Art) The tension (including compressive force) generated between stands during continuous rolling must be reduced as much as possible.
For this reason, it is common practice to detect the tension between stands and perform feedback control, but in cases where general tension detectors cannot be used, such as those used in section rolling, special measures are taken to detect tension.

That is, in continuous rolling, the relationship between the tension between stands, rolling load, and rolling torque is as follows: G = 2lP + r (Tb - Tf) ... (1) G: rolling torque, l: torque arm, P: rolling load, R : roll radius, Tb: rear tension, Tf: front tension, and this formula is used to calculate the tension.

The rolling load and torque of the steel material in the most upstream rolling stand when there is no tension are detected, and the torque arm of the most upstream rolling stand is determined from these detected values.
Based on this torque arm, changes in the rolling torque and rolling load of the most upstream rolling stand when the steel material bites into the next stage rolling stand are calculated as the inter-stand tension. The torque arm of this next-stage rolling stand is determined from this inter-stand tension, rolling load and torque at the next-stage rolling stand. below,
As it gets stuck in the downstream steel stand,
The tension between the stands one after another, the torque arm of the stand one after the other...the torque arm of the downstream stand is determined in sequence.

(Problem to be solved by the invention) In the conventional method, the torque arm is calculated from the load and torque when the steel material is bitten into the rolling stand. It is said that the temperature difference between the two parts is as much as 40℃ to 70℃.
Calculating the tension using the same torque arm value during this time is considered to include a considerable amount of error, and this will inevitably have an adverse effect on the rolling of the steel material.

(Means for Solving the Problem) The present invention corrects the torque arm by taking into consideration the influence of the temperature difference between the leading and trailing ends of the steel material. That is, the torque arm obtained when the leading end of the steel material bites into the rolling stand and the torque arm obtained when the rear end of the steel material passes through the rolling stand are used. Compare these two types of torque arm values, and if there is a difference between these values, it is assumed that the difference is due to a temperature difference between the steel materials, and the torque arm used for tension calculation in the next pass is adjusted according to the temperature difference. to correct. Correction methods include a method of linearly interpolating this difference, a method of performing curve interpolation, or, if the temperature distribution from the tip to the rear end of the steel material is measured, a method of interpolating it using a table.

FIG. 1 shows an example of the final four stands. Hereinafter, we will explain how to calculate the torque arm when the steel material is biting, how to calculate the torque arm when it breaks through, and how these two types of torque arm values are corrected based on the temperature difference between the tip and rear ends of the steel material. .

The method of detecting the load and torque at the time of biting and calculating the torque arm will be explained. tension between stands,
Equation (1) above holds true between rolling load and rolling torque, but if this is applied to four stands and rewritten with a subscript corresponding to each stand, G ₃ = 2l ₃ P ₃ +R ₃ (T ₃₄ −T ₂₃ ) …(2) G ₂ =2l ₂ P ₂ +R ₂ (T ₂₃ −T ₁₂ ) …(3) G ₁ =2l ₁ P ₁ +R ₁ T ₁₂ …(4 ) G: rolling torque, P: rolling load, T: tension,
l: Torque arm, R: Roll radius. The torque arm of each stand is calculated by setting the tension between the #4 stands of the immediately upstream stand to zero, and the #2 stand, which has bitten into the steel #3 stand, has not yet bit, and no tension T ₂₃ has occurred. In this state, from equation (2), the torque arm l ₃ is 2l ₃ = [G ₃ /P ₃ ] ₃ ...(5) When the torque arm l ₃ is bit into the subsequent #2 stand, (2) , From equation (3), the torque arm 2l ₂ is 2l ₂ = [G ₂ /P ₂ ] ₂ +R ₂ /R ₃ [P ₃ /P ₂ ] ₂ ([G ₃ /P ₃ ] ₂
−2l ₃ ) ...(6) Similarly, when it is inserted into the #3 stand, using torque arms l ₃ and l ₂ , from equations (2), (3), and (4), torque arm l ₁ is 2l ₁ = [G ₁ /P ₁ ] ₁ +R ₁ /R ₂ [P ₂ /P ₁ ] ₁ ([G ₂ /P ₂
] ₁ +2l ₂ ) +R ₁ /R ₃ [P ₃ /P ₁ ] ₁ ([G ₃ /P ₃ ] ₁ +2l ₃ )
......(7) can be calculated respectively. Note that i=3,
2 and 1 indicate the detection values when biting into the stands #3, #2, and #1, respectively.

If the torque arm is determined, the tension between the stands is (2),
From equations (3) and (4), using l ₃ , l ₂ , and l ₃ as parameters, T ₃₄ = G ₃ /R ₃ +2P ₃ l ₃ /R ₃ +T ₂₃ ...(8) T ₂₃ = G ₂ /R ₂ +2P ₂ l ₂ /R ₂ +T ₁₂ ...(9) T ₁₂ =G ₁ /R ₁ +2P ₁ l ₁ /R ₁ ...(10) It can be expressed as follows. i.e. torque arm
If l ₃ , l ₂ , and l ₁ are known, the inter-stand tension can be calculated from equations (8), (9), and (10).

Next, we will explain how to calculate the torque arm when passing through a steel stand. The above equations (2), (3), and (4) hold true among the inter-stand tension, rolling load, and rolling torque. In this method, the torque arm is determined from the load and torque when pulling out from a steel stand. When the #2 stand, which does not generate tension T ₁₂ , is passed through the #1 stand, the torque arm is calculated from equation (4). l ₁ is 2l ₁ = [P ₁ / G ₁ ] ₁ ...(11) Also, while l 1 passes through the #3 stand and is in the #2 and #1 stands, using the torque arm l ₁ , (3), (4 )
From each formula, the torque arm l ₂ is calculated as follows: 2l ₂ = [G ₂ /P ₂ ] ₂ + R ₂ /R ₁ [P ₁ /P ₂ ] ₂ ([G ₁ /P ₁ ] ₂ -
2l ₁ )...(12) Furthermore, pass through the #4 stand and use the torque arms l ₁ and l ₂ while engaging the #3, #2, and #1 stands (2), (3), (4) From each formula, the torque arm l ₃ is: 2l ₃ = [G ₃ /P ₃ ] ₃ +R ₃ /R ₂ [P ₂ /P ₃ ] ₃ ([G ₂ /P ₂ ] ₃ +
2l ₂ )+R ₃ /R ₁ [P ₁ /P ₃ ] ₃ ([G ₁ /P ₁ ] ₃ +2l ₁ )......
(13) can be calculated respectively. Note that i=1 in [ ]i,
2 and 3 indicate stored data that passed through stands #2, #3, and #4, respectively.

In this way, G when the steel material passes through the stand,
After memorizing P and getting through all the stands, the above
Based on the formulas (11), (12), and (13), calculate the torque arms l ₁ , l 2 , and l 3 of each stand #1, # ₂ , and # ₃ .
Note that this torque arm is used to calculate the tension of the steel material in the next pass, and the tension calculation equations used are the equations (8), (9), and (10) obtained earlier.

This invention was developed when the tip of the steel material was bitten.
The torque arm of each stand #3, #2, #1 shown by each formula (5), (6), (7) and (13), (12), ( #3, #2, shown in each formula of 11)
The difference with each stand torque arm of #1 is estimated to be the effect of the temperature difference between the front and rear ends of the steel material, and the torque arm used for calculating the tension of the next pass steel material is corrected taking into account the temperature difference. , is.

(Function) Although there are many possible correction methods such as the linear interpolation and curved interpolation described above, a method using linear interpolation will be described here as an example.

In other words, A is the rolling time for one steel material from #3 to #1 stand, Δli is the difference in torque arm obtained in the previous pass, and t is the elapsed time since the steel material was rolled onto #3 stand. If each stand torque arm obtained at the time of biting of the tip of the steel material shown by equations (5), (6), and (7) is lρi, the torque arm li after correction is li=lρi+△li/A・tK... (14) i=3.2.1, K: can be expressed as a correction coefficient.

This equation (14) is shown in the graph block diagram in Figure 1. Let lei (i = 1, 2, 3) be the torque arm obtained from the stored data at the time of break-through, and △li is (lei -
expressed as lρi).

(Effect of the invention) In this way, the temperature-compensated torque arm _l3 ,
Using l ₂ and l ₁ , calculate the tension of the steel material in the next pass using (8),
(9) and (10) are performed based on each formula, and it improves tension control that allows more accurate tension calculation, which greatly contributes to improving the quality of steel rolling.

[Brief explanation of drawings]

FIG. 1 is a sequence/block diagram for calculating, comparing, and correcting the torque arm when the steel material is bitten into the rolling stand and when the steel material passes through the rolling stand.

Claims (1)

[Claims] 1. G = 2lP + R (Tb - Tf) established between rolling torque, rolling load and tension. G: rolling torque, l: torque arm, P: rolling load, R: roll radius Tb: backward Tension, Tf: In tension control of a continuous rolling mill, where the tension is calculated and controlled using the relational expression of front tension, the torque arm obtained from the load and torque when the tip of the steel material is bitten by the rolling stand, and the torque arm of the rear end of the steel material are calculated and controlled. The load and torque when passing through the rolling stand are memorized and compared with the torque arm calculated when passing through the final rolling stand based on these memorized values, and the difference is determined to be due to the difference in temperature at the tip and rear end of the steel A method for calculating a torque arm in continuous hot rolling, characterized in that the calculation of the torque arm in the next pass steel material rolling is corrected based on the temperature difference.