JPS5813454A - Method and device for controlling thickness of ingot in continuous casting - Google Patents

Abstract

PURPOSE:To obtain an ingot of stable internal quality in continuous casting by measuring the thicKness of the ingot, operating the average thicKness and fluctuating amplitude of the ingot, and controlling the rolling reduction of rolls, the flow rate of secondary cooling water, the drawing speed for the ingot, etc. according to the result. CONSTITUTION:A thickness detector 10 which measures the thickness of a continuously drawn ingot 3 having an extremely high correlation with the internal quality of said ingot 3 is provided. A thickness converter 30 operates and determines the thickness of the ingot 3 from the value detected by said detector and outputs the signal to a process computer 60. The computer 60 operates the average thickness and fluctuating amplitude of the ingot 3 and outputs the signal of the size determined by casting sizes and components properly to a controller 70 for roll screw down, a controller 90 for secondary cooling water, and a controller 80 for drawing speed (all these are not shown), thereby controlling the thickness and amplitude of the ingot to specified values. If the detection and control of the thickness are executed in segment units, the precision in the control of the internal quality is more improved.

Description

Detailed Description of the Invention The present invention relates to a method for measuring the thickness of a slab continuously drawn from a mold in slow continuous casting of bath melted metal (hereinafter referred to as Co), and a method for measuring the thickness of a slab continuously drawn from a mold. It is related to the device.

Generally, as shown in FIG.
is press-fitted and continuously pulled out as slab 6 from below. It is well known that the inside of the slab 6 pulled out from the mold 2 remains unsolidified and gradually solidifies as a whole.

It is well known that bulging occurs in the scallop piece 6 in the fixed position of the PJT due to static pressure. It is also known that the bulging weight affects the quality of the inner cylinder S of the slab 6 (circular cracks, segregation). As shown in the second example, if the roll spacing is 1, L2 and the slab thickness is V, the amount of bulging △ condolence △ (1” = (D - (L1 + L2)
Defined as 72/2. In other words, the amount of bulging is
It becomes a bulge from the 5th side of the roll.

Methods for measuring the amount of bulging include a method using a differential transformer, a method using Micro V2, and a method disclosed in Patent Application Publication 1982-
Various proposals have been made, such as in Publication No. 6822, but there are problems as described below.

1) As shown in FIG. 3, the roll 5 expands and bends due to the heat C2 of the slab 6.

2) Roll yarn is common (consisting of two segments,
The distance between the rolls is kept constant using hydraulic pressure, but due to static pressure, the thickness of the slab 3 is reduced to ash, plastic deformation of the slab 3, and thermal distortion of the rolls (2), which causes a reaction force and The interval is changing.

3) Measurement setup (measurement errors also occur due to thermal expansion.

As mentioned above, it is difficult to accurately measure the amount of bulging due to the behavior of the cast iron and slab, and errors in the measuring device.

As shown in FIG. 4, when the roll 5 changes from the dotted line to the solid line depending on the static pressure and operating conditions, the bulging amount Δd hardly changes.

Therefore, there is a large error in evaluating and predicting the quality of the semi-circular portion based on the amount of bulging.

As a result of thorough investigation based on the actual situation C2, it was found that there is an extremely high correlation between the thickness D of the slab and the internal quality (two), as shown in Figure 5C2, in evaluating the internal quality of the slab.

That is, the present invention proposes to measure the thickness of the slab, and to perform roll reduction control, secondary cooling water control, and drawing speed control based on the results.

Introversion will be explained in detail below.

As shown in FIG. 6, the concentrated acid of the present invention has a thickness detector of 1υ,
Control device 25, J enjoyment replacer 60, CC control device 401
．． , display note 1 # display 50, process calculator 60, mouth 1,
- Le compression control A 111 table straightness 70, extraction speed control j device 80
．． It is composed of 9υ of secondary G water usage rigidity.

The thickness detector 10 is arranged symmetrically with respect to the slab to be measured as shown in FIG.
-Therefore, the thickness detector operates intermittently.A cross-sectional view of the thickness detector is shown in FIG.

The thickness detector 10 is manufactured as a device that is durable under four adverse conditions such as commercial temperature and humidity inside a Co machine, secondary disposal water, and slab scale. The measurement box 12 is double-layered and internally cooled with water 19 to avoid silent influence.The metering rod 11 and the detection rod 171 are connected by a joint, , 17) It is cooled in the direction of the 'r' arrow to prevent thermal expansion.In addition, the touch roll 26 that contacts the intermittent FI on the slab 6 is held by a pivot mechanism (which is The measuring box 12 is used to prevent water from entering from outside. The internal pressure is made positive using 20C of compressed air.

When the Ti piece 6 is pulled out, the detection rod 17 is pulled in the pulling direction at regular intervals of 1flJ, and may come into contact with the roll 5. For this reason, a metal 18, such as copper or aluminum, which is softer than the material of the roll 5, is attached to the measuring rod so as not to cause flaws in the roll 5. The measuring rod 11 is connected to the drive motor 16 in a rank and pinion relationship.
, a clutch 14, a reducer 21, and a control table 25.
It works by

The amount of displacement of the measuring rod 11 is detected with greater precision than the positional relationship between the measuring rod (2) and the attached Magnescale head 16 and the Magnescale 15.The thickness detector 10 is
As mentioned above, the same measures have been taken for durability and heat resistance, and since the thickness of the slab 6 is Oy<accurate (264I
I can be determined.

A signal is input to the control device 25C2 from the CO system #thorn system 40. When operating the thickness detector 10, the thickness detector 10 can be started, stopped, dummy bar, etc. depending on the position of the two pieces 6 at the beginning of casting and at the end of casting. Interlock signal to prevent contact accidents,
A signal is taken in from the Co control device 40 to the control table 25 so that measurement can be performed automatically without operator intervention.

The thickness detectors 10 arranged opposite to each other operate until the finger C2 of the control device 25 comes into contact with the slab B. Contact with the slab 6 is detected by the g-speed machine 21 (contact detector 22 installed adjacent to the thickness detector 10), which detects gear slippage and detects it as slab contact.This detection signal The distance from the position before operation to the contact position is calculated by Magnescale (1
1, 12) and is detected by the thickness converter 60.

Upon detection of the slab contact, the measuring rod 11 returns to the measurement starting point by switching the clutch 14 and starts measurement. This position is also detected at Magnescale City (11, 12).

Since the two thickness detectors 10 are pressed in front with a piece of standard thickness, the thickness converter 60 calculates the slab thickness D from the measured value of the 2' hanging thickness detector 10, and calculates the thickness. D
Recording device bO and process computer 6 display signals proportional to
It is given to 0.

The display/recording device 50 displays and records the measured slab thickness. The slab thickness determination results are retained until the start of the next measurement. The control device 25 measures the thickness of the returned slab.
The results are shown in Figure 8.

Figure 8 (B) (2) also shows the results of changes in the roll 5. The period of fluctuation of the slab thickness D is proportional to one rotation of the roll 5, and is due to the deformation of the roll 5 due to thermal stress. C occurs.

The process computer 60 calculates the average thickness and fluctuation amplitude of the fishing piece 6, and based on these results, the roll reduction control device 707 performs the roll reduction control device 707 to obtain a predetermined piece thickness and amplitude. It is controlled by sending a signal 7 to the front straight 90 drawing speed control side j to the front straight 80. Each control device 70,80.90
The magnitude of the signal given to C is determined by the control size and components.

4 (If the fluctuation in width does not fall below a predetermined level, the roll 5 is deflected from the outside to prevent the roll from bending due to the δ force.Thermal expansion of the roll 5 Controllability is improved by measuring the bending condition, roll spacing, and controlling the thickness of the slab as an auxiliary input signal.

In addition, as shown in Fig. 9, multiple pieces of thickness detectors are installed, and for example, the thickness of the slab on the input side and the thickness of the slab on the river mouth side are measured in roll 5 segment units. It is effective to measure and control the roll reduction based on the thickness of the slab on the input side, and to correct the roll reduction control based on the thickness of the slab at the outlet 1JIIu. Furthermore, by controlling the secondary cooling water and controlling the drawing speed, the internal quality of the slab 6 can be improved.

Applying the measurement results of slab thickness to ape (compression casting control) and performing OPO is effective in further improving internal quality.

As mentioned above, since the invention measures the thickness of one piece and controls the thickness to a predetermined value based on the result, it has the following characteristics.

1) Measuring the thickness of one piece that shows the condition of the breast 8- Therefore, the internal quality of the slab can be predicted.

2) The controllability is good because the thickness of the slab is controlled taking into account periodic changes in the thickness of the slab.

3) As a certain segment love lock of a roll system, the thickness sound of the two collar pieces on the input and output side is measured, and based on this, the slab j enjoyment control 7 is performed by feed, forward 14jlJ 11] and feedback control. Control 7 can be carried out effectively.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of slow rail shavings, Diagram 2 is an explanatory diagram of the amount of bulging, Figure 3 is an explanatory diagram of the roll gap, No. 4 is an explanatory diagram of the occurrence of rolls and bulging, and Section 5 is an explanatory diagram of the slab. Thickness and crack rating,
Graph with segregation score, Figure 6 is an explanatory diagram of uninvention, Figure 7 is an auxiliary diagram of thickness detector of uninvention, Figure 8 is slab thickness deviation I
A) Roll deviation (BJ measurement time, the 9th example is an explanatory diagram of another practical example of the non-invention. 1u; hook thickness 4 ejector 25; control table 60; thickness changer 40 ; CC control control table 50; display record table 60; process calculator 70; roll pressure F control table 80; drawing speed i'blJ control table ν0; cooling water control ([Il] table 11-7 2nd session 4th session 5th session (o-) (b) -D -D 7th session Figure 8 □ 9th Amendment to Liquor Procedures (voluntary) August 5, 1980 Japan Patent Office Commissioner Shimada Haruki Tono 1 Display of the case 1981 Patent Application No. 108115 3 Person making the amendment Relationship to the case Patent applicant Location 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (665)
Nippon Steel Stock Food Coloring Representative Takeshi 1) Toyota 4th generation Osamu Address 4F Kato Building, 3-3-3 Nihonbashi, Chuo-ku, Tokyo Name (6193) Patent attorney Tatsuo Chanoki 5゜Date of amendment order Showa Year, month, date (shipment date) Number of inventions increased by 6 amendments

Claims (1)

[Scope of Claims] l Measure the thickness of the slab during slow casting of molten metal, and determine the amount of roll reduction and secondary cooling for rolling the slab by 17g based on the measurement results. A method for controlling slab thickness in continuous casting characterized by controlling at least one of the following: water flow rate and section drawing speed to maintain the round part quality of the slab at a level 7. 2. A continuous casting machine for bath molten metal is equipped with a slab thickness measuring device, and based on the output signal from the measuring device, the reduction amount of the rolls that support and guide the slab, the amount of secondary cooling water, and the slab drawing speed are determined. A process calculator that calculates at least one of the required changes, and pressure from the process computer (2). Continuous casting characterized by the provision of a control table (a control table for controlling slab thickness in two places).