JPS5991328A - Method and apparatus for measuring stress of continuously cast piece - Google Patents

Abstract

PURPOSE:To grasp the behavior of the cast piece in casting processes accurately, by bonding one or more stress detecting element to the side end surface of the continuously cast piece, and detecting one or more stresses in the thickness direction and the longitudinal direction of the cast piece. CONSTITUTION:A stress detecting element 1 is bonded to the side and surface of a cast piece 10. The output signal from said stress detecting element 1 is amplified by an amplifier 2. Based on the output, at least one of the stress data in the thickness direction and the longitudinal direction of the cast piece 10 is analyzed and computed in a signal processing device 3. The result is displayed on a display device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is for measuring stress in the thickness direction and longitudinal direction of a slab, which occurs in a slab during a continuous casting process, for example, in which molten steel is continuously cast to continuously obtain slabs. METHODS AND APPARATUS.

What is the latest continuous casting operation (hereinafter referred to as CC operation)?

In order to effectively utilize the sensible heat possessed by the slab to save or omit the heating energy in the rolling process, direct connection between the CCI and the rolling processes is carried out. Therefore, there is a trend toward high-speed casting in order to supply hot slabs to the rolling process.

One of the problems that arise when CC operation is performed at high speed is quality.

Horizontal cracks on the surface impair the quality of slabs.

There are internal cracks, etc.

Horizontal cracks on the surface of the slab are caused by the lubrication condition between the mold inner wall surface and the slab in the mold, and in curved CC machines.

It is said to be determined by the tension level when bending the slab back straight. Internal cracks in slabs are caused by i! l! It is said that it is determined by the roll alignment state of the casting machine, the drawing tolerance conditions in CC operation, and the cooling conditions.

Conventionally, as a means to reduce internal cracks in slabs, roll consistency (roll spacing) has been adjusted before PF forming to stabilize CC operating conditions.

In addition, in the operation using a bent type continuous casting machine, as shown in Fig. 1, the curved slab (lO) is bent back and straightened in the first part of amben (the process of bending the curved slab back to straight). Make it. At this time, the -1-blood (12) side (hereinafter referred to as F, L side) of the slab has tensile stress (indicated by arrow A), and the lower surface (13)
Compressive stress (indicated by arrow B) is generated on the side (hereinafter referred to as F-plane), causing internal cracks. In order to prevent internal cracks in the slab and horizontal cracks on the surface, the molten metal is cast so that the cross-sectional shape of the slab is, for example, an inverted trapezoid, and then rolled from both end faces of the slab. Cast J (
Combination control or compression casting (hereinafter referred to as CPC) is performed in which compressive force is generated on the L side of the slab by reducing it in the width direction to reduce tensile stress.

However, with the current CC operation technology, it is not possible to completely prevent internal cracks, surface horizontal cracks, etc., and they even tend to occur frequently due to high-speed casting.

In order to prevent internal cracks, surface horizontal cracks, etc., and improve the quality of slabs, it is important to accurately understand the state of stress generated in slabs.

However, conventional stress conditions due to bulging and unbending of continuously cast slabs at curved parts
At the time, no means had been found to directly and continuously detect the stress state on one side (upper surface) and F side (lower surface) of a slab.

The inventor of the book believes that the stress that acts on the slab during the continuous casting process is the stress that occurs on the slab surface and F side when it is unbent straight from a curved state, and the stress that occurs in the thickness direction of the slab due to bulging. It was discovered that the stresses generated in the slab are combined, resulting in surface cracks and internal cracks at the solidification interface.In order to improve the quality of slabs, we developed a strain gauge that can be used at high temperatures. strain-gage
), we have invented a method and device for directly detecting the stress state on both sides of slab glue and F during the continuous casting process. That is, the present invention provides (1) a process in which molten metal is continuously cast to continuously obtain slabs, in which one or more stress detection elements are bonded to the side end surfaces of the slab, and the stress detection elements are bonded to the side end surfaces of the slab to determine the length and thickness of the slab; A method for measuring stress in a continuous cast slab characterized by detecting stress in any one or more of directions, and (2) a process for continuously obtaining slabs by continuously casting molten metal. A device for detecting stress in either the thickness direction or the length direction of the tube, comprising: a stress detection element bonded to the end face of the casting side;
an amplifier that amplifies the output signal from the stress detection element; and a signal processing device that calculates at least one of stress in the thickness direction and length direction of the slab based on the signal from the amplifier. There is a stress measuring device for a continuous slab, characterized in that:

This invention will be described in detail below.

As mentioned above, FIG. 1 explains the state of the unbend portion in a curved continuous casting machine. The slab (tO) is the velocity V
C is pulled out between the Tyrol (11), and tensile stress is generated on the first surface (12) side as shown by arrow A, and compressive stress is generated on the F side (13) side as shown by arrow B, causing internal cracks.

FIG. 2 illustrates a state in which bulging occurs between the rolls (11). When bulging occurs, in the thickness direction of the slab, tensile stress occurs between the rolls (11) as shown by arrow C, and compressive stress occurs between rolls (11) as shown by the arrow. Therefore, the slab experiences both tensile stress and compressive stress. will be repeated alternately.

FIG. 3 shows an embodiment of the slab stress measurement system of the present invention. In Fig. 3, a stress detection element (υ) is glued to the side end surface of the slab (lO). Stress detection element (1)
The output signal from the amplifier (2) is manually amplified, and based on the output signal from the amplifier (2), the signal processing device (
In 3), data on at least one of stress in the thickness direction and length direction of the slab is analyzed and calculated. The results are displayed on the display device (4).

FIG. 4 shows an example of the detailed configuration of the detection element U), that is, the detection element (U) consists of stress detection elements (1-2), (1-3), (1-4) arranged in various directions. ) is glued to Pol) (1-1)7. (a)
)'J is a top view, and (b) is a plan view.

This detection element U) is connected to the instantaneous welding gun (
It is easily attached to the tip of the instant welding gun (5), and is pressed against the side end surface of the slab (lO) by the instant welding gun (5).
Welding is instantaneously performed by a welder (6) connected to 5). The detection element port welded to the slab (lO) is connected to the amplifier (2) by a signal line (7).

FIG. 6 shows the situation when various stresses in the slab are being measured by the detection element Ω). Stress detection element (1
-4), the stress detection element (1-2) measures the tensile stress on the first side of the slab, the stress detection element (1-2) measures the compressive stress on the F side of the slab, and the stress detection element (1-3) measures the thickness of the slab. Detects tensile or compressive stress in the direction, and these detection signals are
A signal line (7) powers the amplifier (2). The amplified signals are input to a signal processing device (3), and the respective compressive stress or tensile stress is calculated.

Furthermore, the accuracy level can be increased by measuring the surface temperature of the slab (lO) and inputting it manually to the signal processing device (3).

The various stress values calculated by the signal processing device (3) are displayed and recorded by the display device (4), and at the same time are input into a process calculator (not shown) to control roll spacing, roll bending amount, and cooling control. , used as basic information for optimal control of CPC, etc.

As detailed above, this invention 1) It is possible to accurately understand the behavior of slabs during the casting process.

2) Accurately understanding the stress state of slabs makes it possible to elucidate the mechanisms of internal cracks, etc.

3) Roll interval control, roll bending control, secondary cooling control,
Optimal CPC provides excellent effects such as preventing internal cracks, surface horizontal cracks, etc.

[Brief explanation of drawings]

Fig. 1 is an elevational view illustrating the stress state of the slab in the unbend section, Fig. 2 is an elevational view illustrating the stress state of the slab due to palzinc, and Fig. 83 is the stress crystal measurement system of the present invention. FIG. 4 is an explanatory diagram of the detailed configuration of the detection element, FIG. 5 is an explanatory diagram of the method of welding the detection element to the slab, and FIG. 6 is an explanatory diagram of the method of welding the detection element to the slab. FIG. 3 is an explanatory diagram of stress conditions on a detection element. l11. detection element, 208. amplifier, 311. signal processing device, 4069 display device, 580. Instant welding gun, 600
．． welder, 794. Signal line, 10. ,, slab, 11.
, , roll. Patent applicant Shin 11 Wooden Iron Co., Ltd.

Claims (2)

[Claims] (1) In the process of continuous casting of molten metal to continuously obtain slabs, a stress detection element of 1 or more -L is applied to the side end face of the slab!
- A method for measuring stress in a continuous slab, characterized in that at least one of the stress collapses in the thickness direction and the length direction of the slab is detected. (2) A device for detecting stress in either the thickness direction or the length direction of a slab in the process of continuously obtaining slabs by continuously casting molten metal,
A stress detection element bonded to the end face of the casting side, an amplifier that amplifies the output signal from the stress detection element, and a stress detection element in the thickness direction and length direction of the slab based on the signal from the amplifier. 1. A stress measuring device for a continuous slab, comprising: a signal processing device that calculates at least one of the following: