JPH0510169B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for rolling a rolled material between two adjacent rolling stands of a tandem rolling mill that sequentially and continuously rolls a rolled material using a plurality of rolling stands arranged in series. The present invention relates to a speed compensation method for a tandem rolling mill to compensate for tension changes due to changes in mass flow.

[Technical background of the invention and its problems]

Generally, when the tension applied to the rolled material in a tandem rolling mill changes, the thickness and width of the rolled material change.
Since it is not possible to produce products with consistent quality, a looper 4 is installed between the rolling stands 1 and 2 to give a deflection to the rolled material 6, as shown in Fig. 3, and the height and pushing force of the looper 4 are controlled to improve rolling. Either the tension applied to the material 6 is kept constant, or nothing is provided between the rolling stands 1 and 2 as shown in Fig. 4, and the rolling torque of the rolling mill is proportional to the tension applied to the rolled material. Tension control is performed to keep the tension applied to the rolled material 6 constant by controlling the rolling torque of the rolling stand. In response to such high-frequency disturbances that tension control cannot respond to, mass flow compensation control (hereinafter referred to as MFC) is performed, which detects changes in the smear flow balance between adjacent rolling stands and compensates for the rolling speed. (Unexamined Japanese Patent Publication No. 1983-
(See Publication No. 81506).

Here we will briefly explain the principle of MFC.

The tension t in the rolled material between two adjacent rolling stands, namely the i stand and the (i+1) stand, is (1)
It is expressed by the formula.

t=E/L∫〓 ₀ (V _ei+1 −V _pi )dτ ……(1) Here, E: Young's modulus of rolled material L: Distance between stands V _ei+1 : (i+1) Material speed on entrance side of stand V _pi : Speed of material on exit side of i stand τ : Time As is clear from equation (1), the tension t does not vary when V _ei+1 = V _pi holds. MFC is a control method based on this idea.

Input side material speed V _ei+1 and exit side material speed V _pi in equation (1)
are expressed by equations (2) and (3), respectively.

V _ei+1 = V _i+1 (1−b _i+1 ) ...(2) V _pi =V _i (1+f _i ) ...(3) Here, V _i+1 : (i+1) Stand roll circumferential speed V _i : i-stand roll circumferential speed b _i+1 : (i+1) stand backward rate f _i : i-stand advance rate Also, since the mass flow on both sides of the inlet and outlet is equal in the (i+1) stand, for example, hot strip mill finish rolling Assuming that changes in the width of the rolled material at the entrance and exit side of the machine can be ignored, equation (4) holds true.

H _i+1・V _ei+1 =h _i+1・V _pi+1 ...(4) Here, H _i+1 : (i+1) Stand entry thickness h _i+1 : (i+1) Stand exit thickness V _{pi +1} : (i+1) Stand exit side material speed (i+1) Stand advance rate f _i+1 and backward rate b _i+1
Expressing equation (4) using , we get equation (5).

H _i+1・V _i+1 (1−b _i+1 )= h _i+1・V _i+1 (1+f _i+1 ) ……(5) Above (2), (3), (5 ) using the formula V _ei+1 = V _pi
Find the i-stand roll circumferential speed V _i that satisfies the following: V _i =h _i+1・V _i+1 (1+f _i+1 )/H _i+1・(1+f _i )...
(6) becomes.

In equation (6), each parameter is considered as a variable,
Taking the total differential, dv _i =v _i+1 (1+f _i+1 )/H _i+1 (1+f _i )dh _i+1 +h _i+1 (1+f _i+1 )/H _i+1 (1+f _i )dv _i+1 +h _i+1 v _i+1
/H _i+1 (1+f _i )df _i+1 −h _i+1 v _i+1 (1+f _i+1 )/H _i+1 2(1+f _i dH _i+1 −h _i+1 v _i+1 (1+f _i+1 )/H _i+1 (1+f _i )2df _i ……(6A
) If the minute changes in each variable are expressed as Δv _i , Δh _i+1 , ..., etc., approximately, dv _i = Δv _i , dh _i+1 = Δh _i+1 , dv _i+1 = Δv _i+1 df _i+1 = Δf _i+1 , dh _i+1 = ΔH _i+1 , df _i = Δf _i ...(6B) Substitute equation (6B) into equation (6A), and replace both sides with equation (6). Dividing by Δv _i /v _i =Δh _i+1 /h _i+1 +Δv _i+1 /v _i+1 +Δf _i+1 /1+f _i+1 −ΔH _i+1 /H _i+1 −Δf _i /1+f _i ...
(6C) In equation (6C), h _i+1 , H _i+1 , f _i , f _i+1 are the reference values of each parameter, and h ^* _i+1 , H ^* _i+1 , f _i
If we write ^* , ^* _i+1 and change the order of the terms on the right side, we get
Equation (6) was reexpressed as a rate of change from the standard rolling state.
Equation (7) is obtained. Δv _i /v _i =Δv _i+1 /v _i+1 +Δh _i+1
/h ^* / _i+1 −ΔH _i+1 /H ^* / _i+1 +Δf _i+1 /1+f ^* / _i+1 −Δf _i /1+
f _i ^* ...(7) Δv _i : i stand roll peripheral speed change Δv _i+1 /v _i+1 : (i+1) stand roll peripheral speed change rate h ^* _i+1 : (i+1) stand protrusion thickness standard Value H ^* _{i + 1} : (i + 1) Stand insertion thickness standard value f ^* _{i + 1} : (i + 1) Stand advanced rate standard value f _i ^* : i stand advancement rate standard value Here, (i + 1) Stand exit thickness, insertion The amount of change Δh _i+1 , ΔH _i+1 , Δf _i+1 in the thickness and advance rate, and the amount of change Δf _i in the advance rate of i-stand are determined as follows.

Δh _i+1 ＝h _i+1 −h ^* _i+1 ……(8) h _i+1 ＝S _pi+1 ＋P _i+1 ／M _i+1 ……(9) ΔH _i+1 ＝H _{i +1} −H ^* _i+1 ……(10) H _i+1 =h _i・e ^-td

Claims (1)

[Scope of Claims] 1. To compensate for tension changes due to changes in mass flow of rolled material between two adjacent rolling stands of a tandem rolling mill that sequentially and continuously rolls rolled material using a plurality of rolling stands arranged in series. In the tandem rolling mill speed compensation method, the amount of change from each target value in the rear tension and front tension of the downstream stand of the two adjacent stands is determined as the rear tension change amount and the front tension change amount, and the downstream stand rolling load is calculated. Add the rolling load change amount due to the rear tension change amount and the front tension change amount to the detected value to find the downstream stand rolling load with no rolling load change due to the rear tension and front tension, and calculate the calculated rolling load and the downstream stand roll. The downstream stand protrusion thickness of the rolled material is determined using the gap detection value, and the downstream stand protrusion thickness change rate with respect to the downstream stand protrusion thickness immediately after the rolled material bites into the downstream stand,
Similarly, the rate of change in the thickness of the downstream stand with respect to the thickness of the rolled material immediately after it is bitten by the downstream stand, the rate of change of the downstream stand advance rate with respect to the advance rate of the downstream stand, and the rate of change in the downstream stand advance rate with respect to the advance rate of the downstream stand, and the rate of change of the downstream stand advance rate with respect to the advance rate of the downstream stand, and the rate of change of the downstream stand advance rate with respect to the advance rate of the downstream stand, and the rolling material in the upstream stand of the two adjacent stands. The roll circumferential speed correction amount of the upstream stand or downstream stand is calculated from the change rate of the upstream stand advance rate with respect to the upstream stand advance rate immediately after the material is bitten, and the roll circumferential speed of the upstream stand or downstream stand is A speed compensation method for a tandem rolling mill, characterized in that tension changes due to changes in the mass flow of the rolled material between two adjacent stands are eliminated by correcting the speed.