JPS6050539B2 - Method for controlling slab thickness in continuous casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling slab thickness in continuous casting equipment.

Naturally, it is desirable that the thickness of the slab cast by continuous casting equipment be constant, and if there is variation in the thickness, it is likely to cause internal cracks in the slab.

However, as a practical matter, variations in the thickness of cast slabs tend to occur. It depends on casting speed, water injection ratio,
This occurs due to changes in casting conditions such as molten steel properties and mechanical conditions such as roll spacing and roll wear. These casting conditions and mechanical conditions change for each casting, and even if the roll spacing is maintained accurately, the rolls will be deflected due to bulging forces during casting, resulting in variations in the thickness of the slab. Therefore, the present invention proposes a slab thickness control method that can keep the thickness of the slab constant.

An embodiment of the present invention will be described below with reference to the drawings. A
is a large number of roll segment groups constituting a slab conveyance path, and among each roll segment group A, slab 26
The slab 26 is placed at the lower position of the three clamp tables al, a2, and a35 near where the final end of the unsolidified portion is located.
A thickness measuring device 25 is provided to measure the thickness of.
This thickness measuring device 25 may be, for example, a device that measures the thickness of the slab 26 by providing two rollers that sandwich the slab 26 and measuring the distance between the axes of both rollers. is possible. The roll segments a1 to A3 will be described with reference to FIG. 2. Reference numerals 1 and 2 are upper and lower frames constituting the roll segments, and four columns 3 pass through them. 4 is a load cell for measuring bulging force connected to the lower end of each column 3; 5 is a spacer ring disposed between the load cell 4 and the lower frame 2; 6 is attached to each column 3 at the upper part of the upper frame 1. 7 is a crown par provided between the upper ends of the two columns 3 facing each other along the slab conveyance path; 8 is a crown par provided between the crown par 7 and each roll spacing adjustment device; This cylinder device is disposed between the housing 9 of the device 6 and presses the upper and lower frames 1 and 2 toward each other against the bulging force.

The roll spacing adjustment device 6 includes a small diameter portion 3 at the upper end of the column 3.
an outer cylinder 10 that fits externally into the outer cylinder 10, a male threaded part 11 formed on the outer periphery of the outer cylinder 10, and a female threaded part on the inner peripheral surface of the external cylinder 10,
a worm wheel 12 which is screwed into the upper frame 1 and is rotatably supported by the upper frame 1;
A worm gear 13 is screwed into the column 3, and the worm gear 13 is fitted into a recess on the outer circumferential surface of the column 3, and is also fitted into a keyway formed on the inner circumferential surface of the outer cylinder 10, so that the outer cylinder 10 can be attached to the longitudinal axis of the column 3. It consists of a key 15 that is movable only in the direction. 16 is a sleeve that fits onto the column 3, and 17 is both frames 1 and 2.
Among these rolls 17, a suitable roll is a drive roll.

18 is connected to the worm gear 13 via a distribution gear 19
20 is a converter that converts the pressing force of the cylinder device 8 into a voltage value; 21 is a hydraulic circuit for supplying pressure oil to the cylinder device 38; 22
23 is a pressure regulating valve interposed in the circuit 21, 23 is an operating motor of the pressure regulating valve 22, and 30 is a control circuit for the motor 23, which is connected to the bulging force voltage value F1 inputted from the load cell 4 and a predetermined value. ΔP plus 4, this F
The pressure regulating valve 22 is controlled by operating the motor 23 so that F1+ΔP is balanced with the voltage value P1 based on the pressing force of the cylinder device 8 inputted from the converter 20, that is, F1+ΔP=P1. be.

In FIG. 1, 24 compares and calculates the measurement signal from the thickness measuring device 25 and the setting signal from the thickness setter 27 of the slab 26 to detect whether or not the thickness of the slab 26 is appropriate. 7 comparator 28 is a rotation direction control circuit that rotates the motor 18 of each of the roll segments a1 to A3 forward or reverse based on the input signal from the comparator 24. The operation of the above configuration will be explained.

During continuous casting 9, the thickness of the slab 26 is measured by the thickness measuring device 25, and a signal of the measured value D1 is input to the comparator 24. Further, the ideal thickness of the slab 26 at the location where the thickness measuring device 25 is installed is determined in advance, and a signal of the thickness setting value D2 is inputted to the comparison calculator 24 by the setting i setter 27. This comparator 24 compares and computes the measured value D1 and the set value D2. For example, if D1<D2, the comparator 24 sends a signal to the rotation direction control circuit 28 to rotate the motor forward (or reverse). ) is input, and the circuit 28 causes the motor 18 of the lower roll segment a1 to rotate forward (or reverse), and the worm gear 13, the worm wheel 12, and the outer cylinder 10 (with screws on the outer periphery) are input. The spacing α between the upper and lower rolls 17 is narrowed through the screw (with a screw) and the column 3. Next, the roll spacing α of the middle roll segment A2 is similarly narrowed, and further the roll spacing of the upper roll segment A3 is narrowed. When α is narrowed and D1=D2, the operation of each motor 18 is stopped.On the other hand, when D1>D2, the lower roll segment a
The roll spacing adjusting device 6 of No. 1 is operated in order to widen the roll spacing α of each roll segment a1 to A3, and when D1=D2, the operation of each motor 18 is stopped and the rolling distance of the slab 26 is increased. The thickness is maintained properly.
In addition, when continuous casting is performed, the column 3 is pulled up and down by the bulging force of the slab 26 via the upper and lower rolls 17, 17 and the frames 1, 2, and a load is applied to the load cell 4, and the bulging force r is measured. Ru.

The output signal from the load cell 4 is input to the control circuit 30, and a predetermined value ΔP is added to the voltage value F1 of the bulging force. Next, F1 + ΔP and converter 2
When the voltage value P1 based on the pressing force of the cylinder device 8 inputted from 0 is compared and calculated, and F1+ΔP<P1 (
That is, if the bulging force becomes small), the motor 23 is immediately activated to throttle the regulating valve 22, and the pressing force of the cylinder device 8 is reduced so that F1+ΔP=P1. On the other hand, when the force becomes F1+ΔP>P1 (that is, when the bulging force increases), the motor 23 is immediately operated in the opposite direction, the regulating valve 22 is opened, and the pressing force of the cylinder device 8 is increased, so that F1+ΔP=
Make it P1. Therefore, as a result, only a force (that is, ΔP) obtained by subtracting the bulging force F1 from the pressing force P1 of the cylinder device 8 is applied to the roll interval adjusting device 6, so that the driving force of the motor 18 may be small. According to the above embodiment, the slabs 26 are sequentially pressed upward from the final end position of the unsolidified portion, so that the slabs 26 that are caused by solidification shrinkage or bulging force are
It is possible to prevent molten steel from flowing into the voids in 6.

In addition, in the above embodiment, three roll segments a1 to
Although the thickness of the slab 26 is controlled by manipulating A3, one, two, or four or more roll segments may be manipulated.

As described above, according to the slab thickness control method in continuous casting equipment of the present invention, it is possible not only to adjust the roll interval α, but also to control the bulging force by the cylinder device 8 against the ever-changing bulging force. It was possible to press the upper and lower frames toward each other with a pressing force that was always slightly larger than that of the bulging force.
As a result, the slab 26 can always be pressed with an appropriate pressure, and quality deterioration inside the slab due to insufficient pressing or excessive pressing does not occur.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, with FIG. 1 being a schematic side view and FIG. 2 being an explanatory view of the main parts. 1, 2... Upper and lower frames, 4... Load cell, 6... Roll interval adjustment device, 8...
...Cylinder device, 13... Worm gear,
17...Roll, 18...Motor, 2
0...Converter, 21...Hydraulic circuit, 22
......Pressure regulating valve, 23...Motor, 2
[4... Comparison calculator, 25... Thickness measuring device, 26... Slab, 27... Setting device, 2
8...Rotation direction control circuit, 30...Control circuit, A...Roll segment group, a1 to A
3...Roll segment.

Claims (1)

[Claims] 1 Among the roll segments constituting the slab conveyance path, the slab 26 is conveyed on the path to the lower position of the plurality of roll segments a_1 to a_3 near where the final end of the unsolidified portion of the slab 26 is located. A thickness measuring device 25 is provided to measure the thickness of each roll segment a_1 to a_3.
A drive motor 18 is provided to operate the roll spacing adjustment device 6 provided at Calculate both values D_
A signal is output until 1 and D_2 match, and each motor 18 is operated by the rotation direction control circuit 28 activated by the output signal to rotate each roll segment a_1 to a_
Adjust the roll interval α of 3, and each roll segment a_1
~a_3 includes a load cell 4 for measuring bulging force, a cylinder device 8 that presses both the upper and lower frames 1 and 2 toward each other against the bulging force, and a conversion that converts the pressing force of the cylinder device 8 into a voltage value. 20 and an operating motor 23 that operates a pressure regulating valve 22 interposed in a hydraulic circuit for supplying pressure oil to the cylinder device 8. The predetermined value ΔP is added to the sum of both values (F_1+
ΔP) is balanced with the voltage value P_1 inputted from the converter 20 (F_1+ΔP=P_1) by operating the operating motor 23 to adjust the pressing force of the cylinder device 8. Control of slab thickness in continuous casting equipment Method.