JPH02220706A - Tension controller for rolling mill - Google Patents

Abstract

PURPOSE:To stably control the rolling of continuously cast slabs by operating the unit tension of a material to be rolled between a vertical stand mill and a horizontal stand mill and controlling the speed of the horizontal stand mill so that the deviation between the operated tension and the set tension is zero. CONSTITUTION:The continuously cast slabs are rolled by the vertical stand mill 7 and the horizontal stand mill 8. Then, the rolled load of the vertical stand mill 7 is detected by a detector 10. The unit tension of the material to be rolled between both stand mills 7, 8 is operated by an arithmetic means 15 based on the detected value. The rotational speed of an electric motor 12 of the horizontal stand mill 8 is controlled by a control means 16 so that the deviation between the unit tension and a set value of the preset unit tension is zero. Consequently, the continuously cast slabs can be rolled without passing through a heating furnace to reduce cost.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a rolling mill that directly rolls a slab continuously cast by continuous casting equipment in a vertical mill and then in a horizontal mill. This invention relates to a tension control device.

(Prior art) Generally, in continuous casting equipment, as shown in Fig. 3, molten steel poured from a ladle 1 is received by a dumpster 2.
Casting is started by raising the tandate stopper 3 and pouring the metal into the mold 4.

When the outside of the molten steel poured into the mold 4 solidifies to some extent, it is continuously lowered from below by pinch rolls 5 to perform casting. The cast slab 26 is then cut with a torch cutter 24 and transported to a heating furnace 27 by a roller table 25.

After the slab 26 is reheated in a heating furnace 27 until it reaches a predetermined temperature, it is conveyed to a vertical mill 28 and a horizontal mill 29, rolled, and sent to a downstream process. At this time, the tension of the material to be rolled between the vertical mill 28 and the horizontal mill 29 is controlled by determining the rolling torque based on the rolling load and the current flowing through the electric motor that drives the mill, and controlling the tension so that this rolling torque remains constant. It was controlled.

(Problem to be Solved by the Invention) If the temperature of the material to be rolled on the entry side of the vertical mill 28 is not constant, the rolling torque becomes unstable and cannot be controlled. It was necessary to reheat the slab 26 in a heating furnace and maintain it at a predetermined temperature.For this reason, it was considered impossible to directly roll the continuously cast slab.

The present invention has been made in consideration of the above circumstances, and provides a rolling mill that can perform stable control even when slabs continuously cast by continuous casting equipment are rolled directly without passing through a heating furnace. The purpose of the present invention is to provide a tension control device.

[Structure of the invention]

(Means for Solving the Problems) A tension control device for a rolling mill according to the present invention is a rolling mill in which a slab continuously cast by continuous casting equipment is rolled in a vertical stand mill and then rolled in a horizontal stand mill. a calculation means for calculating the unit tension of the material to be rolled between the vertical stand mill and the horizontal stand mill based on the detected value of the rolling load of the stand mill; and the calculated unit tension and a preset value of the unit tension. and control means for controlling the rotational speed of the electric motor that drives the horizontal stand mill so that the deviation from the horizontal stand mill becomes zero.

(Function) According to the tension control device for a rolling mill of the present invention configured as described above, the unit of the rolled material between the vertical stand mill and the horizontal stand mill is controlled based on the detected value of the rolling load of the vertical mill. Tension is calculated by the calculation means. The rotational speed of the electric motor that drives the horizontal stand mill is controlled by the control means so that the deviation between the calculated unit tension and the set value of the unit tension becomes zero. Thereby, stable control can be performed even if the slab continuously cast by the continuous casting equipment is directly rolled without passing through the heating furnace.

(Embodiment) FIG. 1 shows an embodiment of the tension control device 14 according to the present invention. The tension $i1m device 14 of this embodiment has a calculation means 1
5 and a control means 16, and is used in a rolling mill in which a slab cast by continuous casting equipment is directly rolled by a vertical mill 7 and then rolled by a horizontal mill 8.

In the continuous casting equipment described above, the molten steel poured from the ladle 1 is received by the tundish 2, and when the poured molten steel reaches a specified weight, the tundish stopper 3 is raised, and the molten steel prepared in advance in the mold 4 is raised. Damiba (
Casting begins by pouring molten steel onto the top (not shown).

The level of molten steel poured into the mold 4 is measured by a sensor 18a.
When the level of the molten steel reaches a specified level, the pinch roll 5 pulls out the dummy bar and continues casting.

At this time, the position of the tandate stopper 3 is controlled by the level control device 18b so that the level of molten steel in the mold 4 is at a specified level. The thus cast slab is conveyed via pinch rolls 5 and measuring rolls 6 to a vertical stand mill 7, where it is rolled. Then, it is rolled in a vertical stand mill 7 and then rolled in a horizontal stand mill 8 to become a steel ingot 9.

The unit tension of the material to be rolled (slab) between the vertical stand mill 7 and the horizontal stand mill 8 is based on the detected value of the load detector 10 that is installed below the vertical stand mill 7 and detects the rolling load. (The value obtained by dividing the tension by the cross-sectional area of the slab on the outlet side of the vertical stand) is calculated by the calculation means 15. Based on the calculated unit tension, the rotational speed of the electric motor 12 that drives the horizontal stand mill 8 is controlled by the control means 1.
Controlled by 6. The electric motor 11 that drives the vertical stand mill 7 is controlled so that the circumferential speed of the rolls of the vertical stand mill 7 is approximately equal to the conveyance speed of the slab conveyed from the continuous casting equipment.

A specific example of the calculation means 15 and control means 16 is shown in FIG. The calculation means 15 includes a memory circuit 15a and a tension calculation circuit 1.
5b, unit tension calculation circuit 15c, and switch SWl.
It is equipped with Next, the structure and operation of this calculation means 15 will be explained. The switch SWl, which is normally open, is closed immediately after the tip of the material to be rolled (slab) passes through the vertical stand mill 7 and the horizontal stand mill 8. Then, the output of the load detector 10 at this time is stored as a reference value in the storage circuit 15a via the switch SW1.

That is, the rolling load immediately before the horizontal stand mill 8 starts rolling down and the tension control device 14 starts tension control is stored in the storage circuit as a reference value. Based on this reference value, the dead weight W of the vertical stand mill 7 is calculated in the tension calculation circuit 15b, and the vertical stand mill 7 is calculated based on the calculated dead weight W and the detected value of the load detector 10 (rolling load ff1R). The tension F of the material to be rolled between the horizontal stand mill 7 and the horizontal stand mill 8 is calculated using, for example, the following equation (1).

F-(RφL3-W-L2)/L, (1) where Ll is the distance from the pass line to the support pin, L2 is the distance from the center force of the vertical stand mill 7 to the support pin, L3
represents the distance from the load detector 10 to the support pin.

Based on the calculation output F of the tension calculation circuit 15b, the unit tension T is determined by the unit tension calculation circuit 1 using the following equation (2).
5c.

'r-F/A1v---(2) Here, Alv represents the cross-sectional area of the slab on the outlet side of the vertical stand mill 7.

On the other hand, the $ control means 16 includes a casting speed setting device 16a, a pre-rolling speed standard calculation circuit 16b, a post-rolling speed standard calculation circuit 16c, switches SW2 and SW3, a rate circuit 16d, and a rolling rate circuit 16e. , tension connection device 16
f and P! A control circuit 16g, a limit circuit 16h,
It has a switch SW4, an RPM conversion circuit 16i, and a drive circuit 16j. Casting speed setting device 16 a l;
l: Therefore, the casting speed of the continuous casting equipment shown in FIG. 1 is set, and this set speed becomes the set speed V 1 on the entry side of the vertical stand mill 7.

The pre-rolling speed reference calculation circuit 16b is a vertical stand mill 7.
Based on the cross-sectional area A of the inlet side slab of the vertical stand mill 7, the cross-sectional area A1v of the outlet side slab of the vertical stand mill 7, and the set speed V of the input side of the vertical stand mill 7, the following formula is used to determine the horizontal The speed reference N2° of the stand mill 8 is calculated.

Here, '2c' is a rotational speed correction coefficient, which is determined based on actual results.

SW2 is closed until just before the tip of the slab passes through the horizontal stand mill 8 (that is, just before rolling down), but opens immediately after passing. The rate circuit 16d outputs the current rotational speed reference when increasing the rotational speed of the horizontal stand mill 8 before rolling at a predetermined speed increase rate (also called rate) until it reaches the speed reference N2c.

After rolling down, the speed standard calculation circuit 16c calculates the cross section A of the inlet slab of the vertical stand mill 7, the cross section A1v of the outlet slab of the vertical stand mill 7, and the cross section of the outlet slab of the horizontal stand mill 8. Based on the area A2H and the set speed V on the inlet side of the vertical stand mill 7, the speed reference N2H of the horizontal stand mill 8 after rolling is calculated using the following equation.

Here, '2H is an advanced rate correction coefficient. switch SW
3 is just before the tip of the slab passes through the horizontal stand mill 8 (
In other words, it is open until just before the pressure is lowered, but it is closed immediately after passing.

The rolling down rate circuit 16e first determines the rolling down rate α2H, that is, the speed increase rate of the horizontal stand mill 8, using the following equation C based on the speed standard N2 before rolling and the speed standard N211 after rolling down.

Here, T2!1 indicates the time (set value) from when the slab is started to be rolled down by the horizontal stand mill 8 until the rolling is completed. Then, the current rotational speed reference NREP for increasing the rotational speed of the horizontal stand mill 8 at the determined reduction rate α211 is output.

The tension setting device 16f TR sets the unit tension standard of the slab (rolled material) between the vertical stand mill 7 and the horizontal stand mill.
Set EP. The PI control circuit 16g proportionally integrates the deviation ΔT (−T HEPTυ) between the output of the unit tension calculation circuit 15c and the output of the tension setting device 16f. The limit circuit 16h is based on the current rotational speed of the horizontal stand mill 8 determined by the rate circuit 16d or the reduction rate circuit 16e. Based on IINREP, P! A limit is applied so that the output of the control circuit 16g does not exceed 0.1 times the rotational speed reference NREP, and the output is output as a tension correction amount. That is, the output of the PI control circuit 16g is 0. 1NR
If it is smaller than EP, it is output as is, and 0. IN
When the value exceeds the value, O, INREP1EF is output.

The switch SW4 becomes a front gate when 1 to 2 seconds have elapsed after the start of rolling down of the horizontal stand mill 8, and remains open before that.

The RPM conversion circuit 16i uses the current rotational speed reference NI? determined by the rate circuit 16d or the reduction rate circuit 16e. The corrected current rotational speed reference, which is the sum of EF and the tension correction amount determined by the limit circuit 16h, is converted into a rotational speed (RPM). The drive circuit 16j is
The rotation speed of the electric motor 12 that drives the horizontal stand mill 8 is R
The electric motor 12 is driven to the rotation speed converted by the PM conversion circuit 161.

From the above, until the horizontal stand mill 8 starts rolling down, the rotation speed of the electric motor 12 is set at RPM so as to become the current rotation speed standard determined by the rate circuit 16d.
It is driven by the drive circuit 16j via the conversion circuit 16i, and after starting the reduction, the corrected rotation speed is the sum of the current rotational speed reference obtained by the reduction rate circuit 16e and the tension correction amount which is the output of the limit circuit. The rotation speed of the electric motor 12 is determined by the RPM conversion circuit 16 so that the rotation speed is the reference speed.
It will be driven by the drive circuit 16j via i.

As described above, according to this embodiment, stable control can be performed even if the slab continuously cast by the continuous casting equipment is directly rolled without passing through the heating furnace.

〔Effect of the invention〕

According to the tension control device of the present invention, stable control can be performed even when a slab continuously cast by continuous casting equipment is directly rolled without passing through a heating furnace.

Furthermore, since a heating furnace is not required, costs can be reduced.

7... Vertical stand mill, 8... Horizontal stand mill, 10... Load detector, 11.12... Electric motor, 1
4... Tension control device, 15... Calculating means, 16...
- Control means.

Claims (1)

[Scope of Claims] In a rolling mill in which a slab continuously cast by continuous casting equipment is rolled in a vertical stand mill and then rolled in a horizontal stand mill, the vertical a calculation means for calculating the unit tension of the material to be rolled between the stand mill and the horizontal stand mill; 1. A tension control device for a rolling mill, comprising: control means for controlling the rotational speed of an electric motor that drives the mill.