JPS5918128B2 - Tension control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a tension control method for a hot finishing rolling mill, and particularly to a tension control method that takes into account the bending difficulty of a rolling mill.

[Background of the invention]

Conventionally, tension control in hot finish rolling has been performed by a looper type tension control device (hereinafter simply referred to as a looper) shown in FIG.

In Fig. 1, 1 is the rolled material, 2 is the rolling work roll of the i-th stand, 3 is the rolling work roll of the i-th +1 stand, 4 is the motor for the first stand, 5 is the motor for the i-th +1 stand, and 6 is the looper roll. , 7 is the looper arm, 8
9 represents a louver driving morph, and 9 represents a looper control device.

The looper generates tension in the rolled material, which is applied by a looper control device, and when a disturbance is applied, the height of the looper changes to absorb tension fluctuations caused by the disturbance.

That is, since fluctuations in tension can be estimated from changes in the height of the looper, if abnormal tension occurs, it is possible to easily prevent an increase in the abnormality by manual intervention.

On the other hand, in recent years, hot finish rolling has begun to roll considerably thick rolled materials of 30 to 60 mvt, and to roll low-temperature materials such as chondrol drawlift materials (CR materials).

When a looper is applied to such a special rolled material, problems arise such as not being able to form a loop in the rolled material as shown in Figure 1, and the power of the looper motor having to be extremely large. There is.

That is, there is a problem of difficulty in bending the rolled material.

Here, the parameter η1 representing the bending difficulty is defined as follows.

η, −(PW+Py) / P□
(1) However, Pw=C, BiHiLiγ (gravitational torque of rolled material) (2) 8 2M=C2・−EiI iQi −8i (
3) No. L (torque required for bending when the rolled material is considered as an elastic body) PO: 100% motor torque, B1: plate width, Hl:
Plate thickness, γ: Specific gravity, Li: Distance between stands, Ei: Young's modulus of rolled material, i: Second moment of area of rolled material), Si
: Louver arm length, Qi: Height of the louver from the rolling pass line, C1, C2: Conversion coefficients, ηi indicates the ratio of the torque required to raise the louver and 100% motor torque, ηi
is large, it becomes difficult to raise the louver.

For example, as the thickness of the rolled material increases, Pw increases in proportion to the thickness, and the moment of inertia in the PM rapidly increases in proportion to the cube of the thickness, resulting in a larger ηi.

Further, when the temperature of the rolled material becomes low or the material is hard, the Young's modulus E in PM increases and the value of ηi increases.

When performing tension control using a louver, the louver motor is P
A torque of W0PM (=η1Po), acceleration torque and tension torque for controlling the angle of the louver are supplied.

Since the maximum torque of the louver motor is limited to twice the phase of PO, if ηi becomes large, the louver motor will not be able to supply sufficient torque.

In this case, the tension accuracy of the louver decreases.

Furthermore, if the capacity of the louver motor is determined in consideration of such a case, a large capacity motor must be used, which becomes expensive and the response of the continuous tension control for thin plates deteriorates.

Such problems - Tension control method (hereinafter referred to as HTFC)" is a control method using an arithmetic formula that calculates the tension and controls the calculated tension so that it becomes the target tension (i.e. Method without using a louver, below HT
FC) was developed (Japanese Patent Application No. 66903/1983).

This HTFC calculates the tension from the torque generated by the main motor and the detected value of the rolling load, and corrects the speed of the main motor according to the deviation from the target tension.

Figure 2 shows an outline of an HTFC, where the same symbols as in Figure 1 indicate the same things, and 20 is an HTFC.

Reference numeral 21 indicates a tension calculation section, and 22 indicates a speed correction amount calculation section.

As is clear from the control method of this HTFC (P
Torque for bending rolled materials such as W1PM) is not necessary, and tension torque or acceleration torque for tension control is supplied by a rolling motor with a much larger capacity than a louver motor. The tension can be controlled even in low-temperature rolled materials.

Therefore, it is suitable for rolling thick materials and low-temperature rolled materials.

However, since tension changes cannot be visually observed when an abnormality occurs, it is difficult to deal with the abnormality by manual intervention.

Particularly when rolling a thin product, this delay is undesirable because if the tension becomes excessive due to this delay, an accident of plate breakage may occur.

In this way, louvers can be used to control the tension of rolled materials that are easy to bend.
On the other hand, loopless rolling can be said to be suitable for tension control of rolled materials having a large stiffness ηi, such as thick materials.

[Purpose of the invention]

An object of the present invention is to provide a tension control method that can perform optimal tension control for any type of rolled material.

[Summary of the invention]

The present invention uses HTFC to control tension for rolled materials that are difficult to bend, such as thick or low-temperature rolled materials, and uses louvers to control tension for rolled materials that are less difficult to bend, such as thin materials. By switching to perform this, it is possible to achieve good tension control and tension for any rolled material.

[Embodiments of the invention]

In order to simplify the explanation, Figure 3 shows a hot finishing mill of 5.
This is an embodiment of the present invention in the case of a stand.

In the figure, the same symbols as in FIGS. 1 and 2 represent the same things, and 30 is a bending parameter calculation device;
31 is a tension control selection device, 100 is a work roll, 10
1 is a main motor, 102 is a louver, 103 is a louver motor, and 104 is a louver control device.

The bending parameter calculation device 30 calculates the plate thickness preset value H11.
Input the plate width Bi1, the Young's modulus of the rolled material Ei1, the moment of inertia of the rolled material cross section) Ii, and the planned height of the louver Qi.

The bending parameter calculating device 30 calculates a parameter η1 representing the bendability of the rolled material using equation (1).

The tension control selection device 31 inputs the parameter ηi and determines whether it exceeds a predetermined value η0.

11 When the parameter ηi between the 1st + 1st stands exceeds η0, the tension control device is selected such that an HTFC is used as the tension control device upstream from the 1st + 1st stand, and a louver is used downstream from the 1st + 1st stand.

The louver and HTFC control the tension between the studs according to this command.

For example, in the embodiment shown in FIG. 3, the rolling bending resistance parameter η2 between the second and third stands is the reference value η.

In this case, the louvers between stands 1 and 2 and between stands 2 and 3 are not activated.

Further, the control output of the HTFC for the motors from the third stand onwards is masked and not output.

Therefore, on the upstream side where the plate thickness is thicker, and on the downstream side where the HTFC1 is more bendable, control is performed by a louver.

According to this embodiment, optimal tension control can be performed for any type of rolled material.

In this example, the parameters representing the difficulty of bending are the torque related to gravity, the torque related to bending, and the motor's tensile strength.
Although the ratio ηi of 0% torque was used, the preset value of plate thickness and the value of rolled material temperature are directly used as parameters, and depending on the size of the parameters, it is possible to use a louver or HTFC.
You may decide whether to use

In addition, in this embodiment, as a control method that does not use a louver, H
Although TFC is shown as an example, any other method may be used as long as it calculates the tension by some means and corrects the speed of the main motor according to the deviation from the target tension.

For example, there are many known methods for detecting tension, such as a method for determining tension from changes in rolling current, a method for determining from changes in rolling torque, and a method for determining tension from changes in rolling load.

〔Effect of the invention〕

According to the present invention described above, optimal tension control can be performed for special rolled materials such as thick materials, low temperature materials, and high hardness materials, as well as ordinary hot rolled materials.

[Brief explanation of drawings]

FIG. 1 shows a louver-type tension control device, FIG. 2 shows an explanatory diagram of a control method using an arithmetic expression (a method that does not use a louver), and FIG. 3 shows an embodiment of the present invention. 1... Rolled material, 2, 3... Work roll, 6... Louver roll 7... Louver arm 20... HTFC, 30・・・・・・
...Bending resistance parameter calculation device.

Claims (1)

[Scope of Claims] 1. In hot finish rolling equipped with a tension control device that controls the tension between stands by a method that does not use a looper and a looper type tension control device, a parameter representing the difficulty of bending of the rolled material between the stands is determined. If the parameter is larger than a preset value, a tension control device that does not use the looper is used, and if it is smaller, a looper-type tension control device is used to reduce the tension between the stands. A tension control method characterized by controlling. 2. Tension control according to claim 1, characterized in that the ratio of the torque required to raise the looper to a predetermined height and the torque of the looper motor is used as the parameter representing the difficulty of bending. Method.