JPS6261711A - Method for controlling tension of hot rolling mill - Google Patents

Abstract

PURPOSE:To permit the control of the tension between stands without the need for installing a detector to the mid-way stands by correcting the peripheral speed of rolls so as to apply the stress to negate the calculated tension between the mid-way stands to the adjacent stands. CONSTITUTION:The size and temp. of a material 14 entering the stand 1H on the inlet side of roughing mill 18, the size and the temp. of the material 14 emitted from the stand 4V on the outlet side and the peripheral speed and draft of the rolls of the respective stands are detected. The temp. of the material in the mid-way stands 2V, 3H is estimated by calculation from the sizes and temps. of the materials and the peripheral speeds and drafts of the rolls. The tension between the adjacent stands at such estimated temp. is calculated by using the matrix for the coefft. of influence. The peripheral speed is so corrected as to apply the stress to negate the tension between the mid-way stands calculated by suing the inverse matrix for the part where the roll peripheral speed influences the tension between the adjacent stands in the matrix for the coefft. of influence in the stage of calculating the above-mentioned stand. The tension is thus controlled.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a tension control method for a hot rolling mill that hot-rolls a wire rod by arranging rolling rolls of adjacent stands in tandem so as to cross each other at right angles. In particular, the present invention relates to a method for controlling tension in a rough mill stand of a hot rolling mill for non-ferrous metals such as copper wire.

(Prior Art) Generally, when rolling a steel wire, the tension between stands is controlled to control the shape of the wire. In the tension control method commonly adopted for this purpose, the tension between the stands is detected using a load cell, and this tension signal is input into a computer and converted into stress per cross-sectional area to obtain the predetermined tension. The roll circumferential speed is corrected as follows. However, nonferrous hot rolling mills, especially rough mill stands, are covered with a large amount of rolling oil to cool the rolls, making it difficult to install detectors on intermediate stands. and
In most cases, no detector is actually installed.

In this way, in non-ferrous hot rolling mills, unlike steel hot rolling mills, it is not possible to directly detect the tension between intermediate stands, and therefore the tension cannot be controlled.

(Object of the Invention) An object of the present invention is to provide a tension control method for a hot rolling mill that can control the tension without installing a detector on an intermediate stand.

(Structure of the invention) A method for controlling tension in a hot rolling mill according to the present invention.

In order to control the tension between adjacent stands of a hot rolling mill that hot-rolls wire rods by arranging the rolling rolls of adjacent stands in tandem so that they are perpendicular to each other, the dimensions and temperature of the material entering the stand on the inlet side are controlled. , detect the dimensions and temperature of the material coming out of the exit side stand, as well as the roll peripheral speed and rolling reduction rate of each stand.

The temperature of the material at intermediate stands is estimated by calculation from the material dimensions, temperature, roll circumferential speed, and rolling reduction rate, and the tension between adjacent stands at this estimated temperature is calculated using an influence coefficient matrix. When calculating tension, we use the inverse matrix of the part of the influence coefficient matrix where the roll circumferential speed affects the tension between adjacent stands, and calculate the stress that cancels out the tension between the intermediate stands calculated in this way by applying the stress to the adjacent stands. The feature is that the roll circumferential speed is corrected so as to give the same speed.

It can be seen that by doing this, control can be performed without installing a detector that directly detects tension on an intermediate stand.

(Example) Next, the tension control method of the present invention will be explained in detail with reference to the following. FIG. 1 shows a hot rolling mill 10 to which the method of the present invention is applied.
An example is shown in which this hot rolling mill 10 transfers a copper base material 14 cast from a casting machine 12 to a bar precipitation unit 1.
Several stands, in the illustrated embodiment, four stands IH, 2V, receive the copper base material 14 through the rollers 6 and rough-roll the copper base material 14.

It consists of a coarse mill 18 made of 3H, 4V. Furthermore, i
'Vj indicates a stand with vertical roll, i'Hj
This coarse mill 18 shows a stand with horizontal rolls.
The copper rod 14A thus formed is rolled to a copper rough wire 14B by a finishing mill 20, cleaned by a washer 22, and then wound around a coiler 24.

The tension control method of the present invention includes the dimensions and temperature of the material (copper base material) 14 entering the stand IH on the inlet side of the rough mill 18, the dimensions and temperature of the material 14 coming out of the stand 4V on the outlet side, and the roll circumference of each stand. The speed and rolling reduction rate are detected, and the temperature of the material at intermediate stands 2V and 3H is estimated by calculation from the dimensions, temperature, roll circumferential speed, and rolling reduction rate of these materials.

The tension between adjacent stands at this estimated temperature is calculated using an influence coefficient matrix, and when calculating this tension, the inverse matrix of the part of the influence coefficient matrix where the roll circumferential speed affects the tension between adjacent stands is used. The tension is controlled by modifying the roll circumferential speed so as to apply a stress between adjacent stands that cancels out the tension between intermediate stands calculated in this way.

To describe this in more detail using the flowchart in Figure 2, first, as standard data, the material height H and roll circumferential speed P at each stand under optimal rolling conditions are measured using the detector H.
Also, the material width W and temperature T at the inlet stand IH and the outlet stand 4 are detected by the detectors Ws and Wt, and these are detected by the computer 26.
Enter. Note that the material height H is set to a value that takes into account mill jumps in the roll cap at the time of setting. computer 26
is the influence coefficient matrix (B) shown in Figure 3 from these input values.
is determined by calculation. The influence coefficient is determined as follows. That is, the cross-sectional area of the material coming out of the i-th stand is A
i, width bi, height hi, material speed Ui, roll peripheral speed vi, ψi, tensile stress σi, average deformation resistance k
When i is set, a linear relationship holds true.

[Constant mass flow] AAi/Ai + ΔVi/Vi + Aψi/(1+
LPi) Frost ΔAo/Ao+ΔUo/Do = ---(
1) [Width spread] Δbi/bi−Δhi−+/hi− to −1(Δbi−1/bi−1)−BfΔσi/ki−
BbΔσi/ki-1+CΔT−−−−−−−−1(
2) [Advanced rate] Δψi/(1+ψυ snow Fi(Δbi-+/l)i +l
−Δhi/hi)◆FfΔσi/ki−FbΔσi−1
/ki-1 ÷ GΔ ding−−−−−−−−−−−−−−−
-1 (3) [Cross-sectional area] ΔAi/Ai = αiΔbi/bi+βiΔhi/hi
---In addition, in the above formula, Ki, Bf, Bb, Fi, Ff, F
b, αi, and βl are constants, and f represents the front and b represents the back.
The 4n+1 simultaneous equations in 4) are equations that determine the amount of variation in continuous rolling of n stands.

(3n+2) The original disturbance variable sequence is (h) = (Δbo/bo, Δho/ho
,Δh/h,---Δhn/hn,ΔV,/V,,
---ΔVn/Vn, ΔTl---ΔTn) Also, the 3n response variable sequence is (b) iΔbl/bl, ---Δbn/bn, Δσ
l/kl.

-m-Δσn-1/kn-1, ΔUo/Uo, Δψ1
/(1+$1), −−1Δ%/(1+ψJl)).

The relationship between (b) and (h) is a matrix with 3n rows and 3n+2 columns (
B) can be expressed as follows.

(b) = (B) ・ (h) −−−−−−(5)
Each element of matrix (B) is called an influence coefficient,
If a disturbance is given, the response is calculated, Equation (5) is transformed into Equation (
Since 1) to (4) are simply rewritten using matrices, if each coefficient of equations (1) to (4-) is determined by experiment, matrix (B) can be determined by calculation. Since it is difficult to change the rolling machine due to the mechanism of the rolling mill, the material width and temperature of the stands on the inlet and outlet sides are considered as disturbances. The area surrounded by a square in Figure 3 is the area (B2) where the roll circumferential speed affects the tension between adjacent stands, and the opposite row is (B2). )' becomes as shown in FIG. The computer 26 receives the detected values of the material width and temperature of the stands on the inlet side (first) and outlet side (second), compares them with the standard state, and calculates the fluctuations Δbo and Δb4 in the material width and the temperature. The fluctuations ΔTi and ΔT+ are calculated (second step in FIG. 2), and the increase in the tension between the stands is calculated from the fluctuations and the influence coefficient matrix. Since the temperatures at the second and third stands are unknown, the temperature at the first stand is unknown.
Temperature change of stand 4 and 7. By linear approximation from ΔT2. ΔT3 is determined, and ΔT3 is corrected until Δb4 is located between the calculated value and the actual measurement value with respect to Δbo. The state after this correction is considered to be the actual rolling state, and the tension increase Δσi between the stands is calculated under these conditions (third step in Figure 2). Figure 5 shows an example of changes in rolling conditions. show. In this example, the temperatures of the first and fourth stands increase by o, os, o, o3 (5%, 3χ), respectively,
Also, the material width of the first and fourth stands is 0°05.0.
The second and third stands are 0.0 with an increase of 015.
29.0.024 rise, and the tension between the stands is 0.039.0.2B on the exit side of the first, second, and third stands.
, 0.050, respectively.

In the fourth step of the flowchart of FIG. 2, the roll circumferential speed is corrected so as to eliminate these decreases in tension. In other words, the amount of roll peripheral speed correction required to apply stress that cancels out the tension between the stands is determined using the inverse matrix (B2) in Figure 3. Figure 6 shows this roll peripheral speed correction. Indicate quantity.

The first term on the left side of Figure 6 is the inverse matrix (B2), the second term is (σi), and the right side is the roll correction amount (ΔVt).
This example shows that the roll peripheral speeds of the second, third, and fourth stands are modified to be slower by 0.6%, 0.9%, and 0.14%, respectively.

FIG. 7 shows the result of such correction, and as can be seen from this figure, the tension change Δσi between the stands became zero, but the width spread change Δbi slightly increased.

In the above embodiments, the rolling of copper wire is described where the deformation of the material is largely dependent on temperature, but the present invention can also be applied to other metals that have similar properties by just slightly modifying the coefficients. can.

(Effects of the Invention) According to the present invention, as described above, it is possible to maintain the tension between the stands in the best condition without installing a detector inside the stand, and as a result, the incidence of surface defects due to rolling is reduced. There is a practical benefit of being able to considerably reduce the number of scratches on the rough lines.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of a hot rolling mill to which the present invention is applied;
FIG. 2 is a top view and a front view of the tension control method for a hot rolling mill according to the present invention, and FIG. 3 is a diagram showing an example of an influence coefficient matrix.
FIGS. 4 to 7 are diagrams showing examples of changes in rolling conditions, roll correction values, and correction results, respectively. 10-----1 hot rolling mill, 14-----rough drawing line, 1
8--1--Rough mill. Atsushi Residence '1128

Claims (1)

[Claims] In a method of controlling the tension between adjacent stands of a hot rolling mill in which wire rods are hot rolled by arranging rolling rolls of adjacent stands in tandem orthogonal to each other, the dimensions and temperature of the material entering the stand on the entrance side , Detect the dimensions and temperature of the material coming out of the exit side stand, as well as the roll circumferential speed and rolling reduction rate of each stand, and calculate the temperature of the material at intermediate stands from the material dimensions, temperature, roll circumferential speed, and rolling reduction rate. and calculate the tension between adjacent stands at the estimated temperature using an influence coefficient matrix, and when calculating the tension, calculate the portion of the influence coefficient matrix in which the roll circumferential speed influences the tension between adjacent stands. A hot rolling mill characterized in that the circumferential speed of the rolls is modified to apply a stress between the adjacent stands that cancels out the tension between the intermediate stands calculated in this way using the inverse matrix of Tension control method.