JPS5844907A - Controlling method for tension of finishing mill in hot strip mill - Google Patents

Abstract

PURPOSE:To perform a highly accurate tension-controlling, by controlling a tension produced between stands by means of rolling torque and rolling load when the cross-sectional area of a material is larger than the prescribed cross-sectional area, and controlling the tension by a looper device when said area is smaller than the prescribed one. CONSTITUTION:In rolling a material having the cross-sectional area larger than the prescribed one, rolling load of each stand 1, 2,- (i),-(n) is measured by providing a load meter 5 each, and rolling torque is measured by a torque-meter or a main motor 6. The speed of each main motor 6 located at the opposite side of a pivot is operated so as to make each tension produced between the stands coincide with the desired tension by estimating a tension between the stands from said measured value. When the cross-sectional area of the material is small, a small inertial looper-device 4 is provided to perform a PID control against looper angle theta so as to obtain the desired tension without being affected by the inertial force by considering the looper angle theta, thereby operating the speed of the motor 6 located at the opposite side of the pivot.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a tension control method for a hot strip mill finishing rolling mill in which the cross-sectional area of wire material is wide.

The behavior of the strip width during hot strip finish rolling is
Depends on the material tension between the stands.

In order to improve the width accuracy of the holat strip lag coil, tension control has conventionally been performed using a roots amount device as shown in FIG. That is, stand l.

A Roots f roller is provided between the rollers 2 and 2, and the drive torque of the Roots roller motor 4 is controlled so that an appropriate tension is generated on the material M by lifting the material M through the roller 23.

In recent years, it has become common to produce extra-thick and wide Huntrol trawling material (controlled rolling material) for line rolling and rolling using Holatostra lag mills. In order to enable the Lou/Momo p-23 to lift such heavy materials, the rules and equipment have become more powerful, which has caused the following problems.

1) Decreased force controllability due to an increase in the inertia rate of the Roots 9 machine; for example, compared to the conventional rolling mill with a maximum positive arc size of 8 mm thick and a width of 150011 @, the recent maximum rolling size is thick 25m long, 2300m wide! In the 110 rolling mill, the Leu Δ inertia rate increases by nearly 10 times due to mechanical strength. According to the inventors' research, the tension controllability is significantly reduced in this case.

2) Decrease in the signal/noise ratio of the material tension meter: Usually, a load cell is installed under the axis of the looper roller 3 to detect the material tension. This load cell is Roots'P
The material tension is estimated by measuring the sum of the material weight applied to the roller 3 and the vertical component of the material tension. In the inventors' simulation machine, for example, for a material with a thickness of 1.6 ws and a medium length of 700 m, the tension component of the load cell during normal rolling is 70/l), and the tension component that accounts for the main motor current is the motor rating. The current is about 196.

On the other hand, the force applied to a material Noroth cell with a thickness of 25 m and a width of 2300111 m is 7200 Ic9. Therefore 7200
A load cell with an overload capacity that can withstand the load of 7
It is difficult to accurately detect the value of 0 kg.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide tension control that enables high-precision tension control in a hot strip mill finishing rolling mill in which the material cross-sectional area is wide-ranging. It is intended to provide a method.

A feature of the tension control method of the hot stritz mill finishing rolling mill 71''' of the present invention is that when rolling a material whose cross-sectional area is larger than a predetermined cross-sectional area, the tension control method of the hot stritz mill finish rolling mill 71''' is performed by calculation based on rolling torque and rolling load. When rolling a material with a small cross-sectional area other than those mentioned above, the tension between the stands is controlled using a rolling stock device.

An embodiment of the method of this invention will be described below.

A control method for rolling a material whose cross-sectional area is larger than a predetermined cross-sectional area S@ is described in Japanese Patent Publication No. 18538-1983 (
As shown in FIG. 2, each stand 1.2. ...Quantity...nK load cell 5
．． 5. In addition to measuring the rolling load P, a torque meter is provided or the rolling torque G is measured based on the voltage and current of the main motor 6. In this case, the rolling torque G is expressed by the following formula.

G1 = 241・Pi−αf・tfi−αb1−t
bi...(1) Here, Pl; i-stand rolling load Gi; i-stand rolling torque ti; // rolling torque arm tfi;
l/ Front tension tb1; // Back tension αf1. αbi; /l This is a meter that compares to αbi; /l.

Therefore, tb, =0. The inter-stand tensions tf and tb are estimated from the measured values of the rolling load P and the rolling torque G by combining equation (1) for each stand using the property that tf tension=tbl◆l. And this tension between the stands if
, tb are operated to control the speed of the main motor 6 on the opposite side so that the tensions become the target tensions.

This control method uses a powerful rolling device with a high rate of inertia when rolling a material that has a large cross-sectional area and a large rolling torque G, that is, when rolling a material that has a large tension component in the current of the main coil 6. It is possible to control the material tension between the finishing stands with good controllability without using a finishing stand.

Next, the control method when rolling a material with a small cross-sectional area other than the above is to install a low-inertia rooting device as shown in Figure 3, and set the target tension to ignore the inertial force by considering the roof angle θ. In this way, the speed of the main motor 6 on the reverse side is controlled by applying PID control to the zero angle.

In this case, the root/mother roll 3 does not need to lift heavy materials, so it is possible to install a load cell with a small overload capacity, which improves the signal/noise ratio for tension detection and improves the signal/noise ratio of the root 4 device. Combined with the low inertia of , tension controllability can be improved.

In the case of Fig. 3 above, the material tension is not directly measured, but a material tension needle is installed and the actual measured value is adjusted to the roots, motor torque, and speed of 7% - 6 on the anti-bit side. It may be reflected. Also, although an electric motor is used as the actuator for the loop/gun, the same effect can be obtained by using hydraulic pressure.

Next, a method for determining the predetermined cross-sectional area 8c of the material M, that is, the cross-sectional area of the boundary material, will be explained with reference to FIG. As a result of the stain ratio, in the material tension control method that does not use the Roots 9 device, the tension error square value of the control result becomes curve a under normal operating conditions. On the other hand, in a material tension control method using a Lou-Ya device that can lift the island X with the maximum material cross-sectional area, the material becomes curved. Now, roots 4 only if the material cross-sectional area is small.
The tension error square value corresponding to the combination and curved line obtained by using the Roux 9 device with low inertia approaches the X-axis. Then, when the predetermined cross-sectional area Se, that is, the cross-sectional area of the boundary material is set to the Roots 4 device that can be lifted, as shown in curve C, the material tension of the material with the minimum cross-sectional area SMIN is controlled using the Rootsku device, and the predetermined cross-sectional area Se is obtained. There is a predetermined cross-sectional area Se where the square tension error value is the same as in the case where the material tension is controlled without using the Lutsk device. As a result of determining such a predetermined cross-sectional area Sc, that is, the cross-sectional area of the boundary material, Se S 1
．． 5×10'- was obtained.

Therefore, in a hot strip mill finishing mill where the material cross-sectional area is wide, when rolling a material whose cross-sectional area is larger than the predetermined cross-sectional area Sc, tension control without using the looper device shown in Fig. 2 (curve a , >, and when rolling a product with a small cross-sectional area other than the above, tension control is performed using a low-inertia root shear device shown in Fig. 3 (curve C).
By doing so, in both cases, it is possible to suppress the tension error square value to a certain value or less and perform tension control with good controllability.

Since the tension control method of the hot strip finishing mill of the present invention is as described above, it is possible to perform highly accurate tension control when the cross-sectional area of the material is over a wide range.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a tension control method using a conventional Roots 4 device, Figs. 2 and 3 show an embodiment of the method of the present invention, and Fig. 2 is a tension control method without using a Roots device. FIG. 3 is an explanatory diagram of the tension control method using the Lutsk device, and FIG. 4 is an explanatory diagram showing the relationship between each tension control method and the tension error square value. 1,1'L:A Figure 2 g'i Figure 3 Figure 4

Claims (1)

[Claims] When rolling a material whose cross-sectional area is larger than the predetermined cross-sectional area, the tension between the stands is controlled by calculation based on the rolling torque and rolling load, and when rolling a material with a smaller cross-sectional area other than the above, is characterized in that the tension between the distants is controlled by a Roots 9 device. Tension control method for hot strip mill finishing rolling machine.