JPS59101259A - Casting mold for continuous casting machine - Google Patents

Abstract

PURPOSE:To make heat extraction uniform and to prevent the nonuniformity in the quality of a steel material in a curved type continuous casting machine by making the radius of arc on the inside wall surface of a casting mold in contact with the top surface side of a billet smaller than the difference between the radius of arc on the inside wall surface of the casting mold in contact with the bottom surface side of the billet and the casting thickness of the billet. CONSTITUTION:The arc AB and arc CD on the inside wall surface of a casting mold are respectively part of the circle having the radius RL of curvature on the top surface side (surface L) and the radius RF of curvature on the bottom surface side (surface F), and is the radius RL of curvature is so set as to be equal to the radius R'L of curvature smaller than the size determined by subtracting the casting thickness of a billet, as designated as (d), from the radius RF of curvature. For example, a fresh center E of curvature is set on the bisector of an angle AOB and the arc of the radius R'L running the point A and the point B is considered, then the restricting amt. between the inside wall of the casting mold is set about r/l=0.3-0.5% where said restricting amt. is designated as (r) and the length of the arc AB having the radius RL shown by the soild line as (l).

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a 7" 3-curved continuous casting machine, particularly a machine height of 6 m.
This article relates to the improvement of molds in the following low-head continuous casting machines.

In recent years, continuous gate casting machines (hereinafter referred to as continuous casting machines) have been shifting from vertical and vertical bending molds to curved molds. The top side and 1st side of the piece (hereinafter referred to as L side and F 11 respectively)
(abbreviated as TQ)), and if n is also 几, then the shape has the following relationship with the casting thickness d.

RF −RL = d ・・・・・・・・・fi
It has the relationship shown in the above equation, and F and RL are small, 6
When continuously casting molten steel with a curved mold for a low machine height (low head) of less than m, the difference in heat extraction ability from the mold wall surface between the L side and F@11 is due to Compared to the case of a curved mold with a large nL, it is remarkable that L
It was learned that the heat removal ability of the side was extremely low, and that the contact between the slab and the inner wall of the mold was poorer on the T side than on the F side. It was also learned that thermal stress on the surface layer of the slab caused by these causes deterioration of the quality of the slab, such as surface cracking, and in severe cases, breakout.

In the casting process, the sensible heat held by the slab is not dissipated after the casting process, and the slab is supplied to the rolling process at a high temperature, thereby reducing or omitting heating energy for rolling. 8Yru,
The so-called continuous casting-direct rolling process has been trending in recent years, but deterioration in the quality of slabs during the continuous casting process does not directly manifest itself. This will determine the success or failure of the continuous casting-rolling process.

This invention was made with the aim of solving the above-mentioned problems in continuous casting of molten steel using a low-height continuous casting machine. The arc radius of the inner wall surface of the mold that is in contact with the upper surface side (5th side) is less than the radius of the arc radius of the inner wall surface of the slab that is in contact with the lower surface side (F side) of the slab minus the slab casting thickness. This is a mold for a continuous casting machine that is characterized by:

The present invention will be explained in detail below.

The inventors conducted research involving many experiments on the shape of curved molds in low-height continuous casting machines, and found that (
1) The arc radius (radius of curvature) of the L-side inner wall surface of the mold shown by the formula RL also shows that using a curved mold having a small L-side arc radius is effective in solving the above problem. I found out.

FIG. 1 is an explanatory diagram of mold pieces on the L side and F side of the curved mold of the present invention.

In Figure 1, line segment AO represents the meniscus, !
LU, T, (1111 cast W ai?,・z゛ha, F
1111 n type i-r 6ru.

In Fig. 1, the inner wall surface of the mold piece is shown by the solid line.
L-side radius of curvature FLL% is a part of the circle with F-side radius of curvature RF, and the relationship RF − of the equation (1) already mentioned is established between this arc radius RL and RIF and slab casting thickness d.
There is RL = d.

Now, a new center of curvature E is set on the bisector of the angle 4AOB, and an arc with radius B L / that passes through points A and Bt is considered. In this case, the reduction amount r between the mold inner wall surfaces at the center point in the casting direction, the length a of the line segment OE, the radius of curvature RT,
The relationship with ' is given by the following equations +21 and +31, assuming that the length of the arc AB with radius FLL shown by the solid line is 2t.

tt4. α+β RL α+β α is an amount related to the length of the template, and β is an amount related to the amount of narrowing.

The determination of the reduction amount r depends on the type of pot to be cast, the casting temperature, the lubrication state between the inner wall surface of the mold and the slab during casting, the mold material, and the arc radius RLl, but according to experiments, -r/l=
It is preferable to take the force I to about o.3 to ().5%.

In the curved mold of the present invention, which is equipped with an L-side mold piece having an arcuate surface that satisfies the above conditions, the radius of curvature of the L-side inner wall surface is
(1) is smaller than that shown in equation (1), and the reduction amount r K is set in accordance with the casting conditions, so by using the six-curved mold of the present invention in a continuous casting machine with a low machine height, The contact state between the mold inner wall surface and the slab is closer on the L side than in the conventional @JIN ν, and the amount of heat removed from the mold inner wall surface is equalized on the L side and F side, making it easier to operate the chestnut. Trouble can be avoided and deviations in the thickness direction during the solidification process can be prevented.
Furthermore, deviation in the thickness direction of the slab does not occur. Thus, all the above problems can be solved.

In the above example, the curved surface with a smaller radius of curvature of the inner wall surface of the L-side mold to obtain the reduction amount r is defined as A in FIG.
Although the curved surface passing through point B is used, it may be an arcuate surface with a radius of curvature that is parallel to the inner wall surface of the elongating mold F or that gradually increases from point G, where the reduction amount r is maximum, toward the downstream side in the casting direction. By adopting such a structure, the contact state between the L side mold inner wall surface and the slab is improved, the heat removal ability of the L side is improved, and the L side can be brought closer to the F side.

According to this invention, since the inner surface of the mold piece on the L side has the radius of curvature or curved surface described above, a curved continuous casting machine with a low machine height, particularly a low machine height curved continuous casting machine with a machine height of 6 m or less. In continuous casting for each melt, it is possible to equalize the heat removal from the inner wall surface of the vJ type on the L side and F side.
It is possible to achieve effects such as preventing non-uniformity of the steel material due to the difference in the amount of heat removed on the F side.

[Brief explanation of drawings]

FIG. 1 is an explanatory view of the L side and F side mold pieces of the curved mold of the present invention. ■-...L detail mold piece of the mold, 2...F (In mold piece) of the mold. Agent: Patent Attorney Masaaki Akizawa, 2 outside parties, Director General of the Patent Office, Sent on November 30, 1981. Patent application (1) 2, name of the invention consecutively 1a fishing mold for machine building 3, amended each "1'11 connection with cattle [related] Client 11: Location (residency) 2-chome, Otemachi, Chiyoda-ku, Takumoto 6 examination 3
No. Name (Name) (61'+5) @1 Nippon Jiitetsu Co., Ltd. 4, Representative Residence 1, Honkyo Kabuto-cho, 12-1 Hirohiru r+li, +l (6□7'7 Contents 1 of the Vii Niji Amendment of the Invention Increased by Ura 11 Mo, the scope of the claims of the present patent application is corrected as follows. (1) In the mold VC for a curved continuous casting machine, the arc radius of the mold inner wall surface in contact with the upper surface side (L surface) of the slab - public - 1
A mold for a continuous casting machine, characterized in that it has a curved portion with a radius less than the arc radius of the inner wall surface of the slab in contact with the lower surface side (side 2) of the foil strip minus the casting thickness of the slab. ” 2 Specification J, page 3, line lO “...The arc radius is
``1 piece below'' is changed to ``...the radius of the arc is below the slab.'' 3 Douga 3 members line 12 “...is the radius” “・
1 - To have a curved part with a radius. 4. 2nd line at the bottom of page 3: ``The radius of the arc on the L side...''
Rina "Curved part of L-side arc radius ml" Maro 5, same page 315, lines 5-4 from the bottom, "The above curved mold of the present invention..." was changed to "The curved mold of the present invention satisfies the above conditions. The curved mold of the present invention having a curved portion on the mold piece on the side of the arcuate surface IL is amended as ". 6 Second line from the bottom of page 6 [or because it is a curved surface,” 7
is changed to ``or because it has a curved part with a curved surface.''

Claims (1)

[Claims] (1) In the mold for a curved continuous casting machine, the upper surface f of the slab
The radius of the arc of the inner wall of the mold in contact with ill (L side) is less than the radius of the inner wall of the slab in contact with the lower surface of the slab (side 1) minus the thickness of the cast slab. Characteristic molds for continuous casting machines.