JPH0417953A - High frequency oscillating mold for continuous casting - Google Patents

Abstract

PURPOSE:To prevent sticking between a cast slab and a mold by giving oscillation having the specific amplitude and frequency toward the right angle direction to cast slab drawing direction and setting damping prevention mechanism for self-oscillation of the mold to a mold table. CONSTITUTION:The oscillation having 10-500mum amplitude and 1000-10000cpm frequency is given to the mold 1. The damping prevention mechanism 7 is fitted at between the mold 1 and the mold table 4. In the case the amplitude is less than 10mum, sticking prevention effect by promoting flowing-in of powder is little, and in the case this exceeds 500mum, the mold is oscillated sideward. In order to obtain the oscillating energy needed to reduce coefficient of friction, the above frequency under relation with the amplitude is necessary. By setting the damping prevention mechanism 7 to the oscillation, the oscillation to only the mold 1 is continued and the sticking can be prevented and the stable continuous casting can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high frequency vibration mold used for continuous casting of steel.

(Prior art) When continuously casting steel, lubricant (molten powder) is supplied to prevent seizure between the mold and slab and to continue casting stably without breakouts. Oscillation is carried out to move the mold in the slab casting direction.

By the way, this oscillation is a reciprocating motion parallel to the direction in which the slab is pulled out, and its speed is higher than the withdrawal speed of the slab, so the solidified shell in the meniscus in the mold is pushed and bent, causing the oscillation in the slab. I'll put a mark on it. Depending on the viscosity of the lubricant and the oscillation stroke conditions, the oscillation marks become deeper and cause surface cracks. In addition, air bubbles may be trapped on the inner surface of the pressed and bent solidified shell, and internal defects may remain as pinhole defects.

In order to solve this problem, many proposals have been made to prevent sticking by applying ultrasonic waves to the mold as a method of casting without oscillating the mold.

(Problem to be Solved by the Invention) However, in the method of applying ultrasonic waves to the mold, since the ultrasonic vibration device currently has a small output, it is difficult to attach it to the mold to obtain the required vibration conditions. Many ultrasonic vibration devices must be installed. Therefore, it is necessary to control the vibrations of these many ultrasonic vibration devices so that they do not interfere with each other and cancel each other out (Japanese Patent Application Laid-Open No. 1-122
Publication No. 645). In addition, this method applies high-frequency vibrations to the mold, which causes cavitation in the cooling water in the mold, causing maintenance problems such as damage to the inner surface of the cooling groove.

Furthermore, this method requires a fairly expensive ultrasonic vibration device, and
1-10 μm at a high frequency of 5-50 KHz, although the equipment cost is very high due to the large number required.
There were also problems, such as the fact that such small amplitude vibrations were not very effective in preventing stinking between the slab and the mold.

The present invention solves the problems with conventional ultrasonic vibration molds,
In other words, ■ Requires a large number of ultrasonic vibration devices;
We aim to provide a high-frequency vibration mold for continuous casting that can solve problems such as: ■ It is less effective against stinking; ■ It requires control to prevent interference of ultrasonic vibration between ultrasonic vibrator devices. The purpose is

(Means for Solving the Problems) The present invention has been accomplished based on the knowledge obtained as a result of various experiments and research conducted by the present inventors.

That is, the relationship between the vibration conditions of the mold and the frictional force obtained by the present inventors is shown in Figure 2. When examining the relationship with the coefficient of friction with the amplitude x frequency as vibration energy, this vibration energy is 5 x It was found that the friction coefficient decreased significantly when the position was around 105. Therefore, it has been found that ultrasonic vibrations around l0KI (z), which have been proposed in the past, are not necessary to reduce the coefficient of friction.

Also, the film thickness of the molten powder between the mold and the slab is 500 um to 1. Although it is estimated that the thickness is 5 μm, it is estimated that the thickness of the powder film is 5 μm, as is the case with conventional ultrasonic vibration.
Even when vibrations with a certain amplitude are applied, the inflow of molten powder is not promoted, and the effect of preventing stinking between the slab and the mold is not necessarily clear.

The present invention has been made based on this knowledge, and includes a vibrating mold configured to apply a predetermined vibration to the mold in order to prevent sticking, with an amplitude of 10 to 500 μm.
The mold is equipped with a vibration generator that applies vibrations with a frequency of 1000 to 10000 cpm in a direction perpendicular to the slab drawing direction, and a mold table that supports the mold is equipped with a damping prevention mechanism for the self-vibration of the mold. The gist of this document is to:

In the present invention, the amplitude of the high-frequency vibration to be applied by the vibration generating device constituting the mold of the present invention is set to 10 to 500 μm because an amplitude of less than 10 μm has little effect of preventing sticking by promoting powder inflow.
This is because if it exceeds .mu.m, the lateral wobbling of the mold will cause a misalignment between the slab and the supporting device located below the slab, and there is a risk of breakout occurring. According to experiments and research by the present inventors, a more preferable range is 50 to 200 μm.

Furthermore, the frequency of the vibration generator constituting the present invention is set to 100.
The reason for setting the range from 0 to 110,000 cp is that the vibration energy (amplitude x frequency) must be 5XIO5 or more in order to reduce the friction coefficient according to experiments conducted by the present inventors, and in order to obtain this vibration energy, This is because a range of 1,000 to 10,000 cρm is appropriate in relation to the amplitude.

In addition, in the present invention, the reason why the vibration generator is installed in the mold itself is because the weight ratio of the mold itself and the mold table that supports it is approximately 1:1, so only the mold itself is vibrated. Second, the vibration of the mold of the present invention has an extremely small amplitude compared to oscillation, and there is no need for a large-scale support mechanism to control the movement of the mold due to vibration. This is because it is possible to continue the vibration of the mold by vibrating only the mold itself, which is the minimum block that generates vibration, and by providing only a vibration damping prevention mechanism between it and the mold table that supports the mold.

(Function) In the mold of the present invention having the above configuration, vibration can be effectively applied to the mold by one vibration generator without requiring control to prevent interference between vibration generators. , it is possible to effectively prevent sticking.

(Example) The present invention will be described below based on an example shown in FIG.

FIG. 1(a) is a front view of the mold of the present invention, and FIG. 1(b) is a partially sectional side view. 1 in FIG. 1 is a mold, and this mold l is: For example, a rail 3 provided on the lower surface of a support protrusion 2 provided protrudingly on the side wall on the short side is attached to the upper surface of a roll 5 rotatably provided at a position facing the rail 3 of the mold table 4. By being placed so as to fit together, the slab A is supported by the mold table 4 while allowing movement in the thickness direction and preventing movement of the slab A in the width direction.

Reference numeral 6 denotes a vibration generator fixed to, for example, the outer wall surface of the longer side of the mold 1, which applies vibration in the thickness direction of the slab A with an amplitude of 10 to 100 μm and a frequency of 1000 to 10000 cprn to the mold 1. It is something. This vibration causes the mold 1 to resonate, and high-frequency vibrations are generated on the inner surface of the mold.

7 is a damping prevention mechanism interposed between the mold 1 and the mold table 4 in order to prevent vibrations generated in the mold 1 from being damped; A screw shaft 9 is provided in a protruding manner on the supporting protruding portion 2 of the mold 1 to pass through the supporting block 8.
and a Nand 10 screwed onto this threaded shaft 9, and the nut 1.
0 and a splinter 11 interposed between the support block 8, which supports the mold 1 in a sandwiched manner from the thickness direction of the slab A.

Therefore, by changing the tightening amount of the Nand 10, it is possible to control the pressing force of the spring 11 and control the vibration amplitude of the mold 1, and at the same time, set the center position of vibration, that is, the reference position of the mold 1. .

In principle, the amplitude of the vibration of the mold 1 is adjusted by adjusting the spring force as described above, but it can also be adjusted by adjusting the amplitude of the vibration generator 6.

When the mold of the present invention having the above configuration is vibrated,
As shown in FIG. 3, it was confirmed that vibrations similar to those produced by the vibration generator 6 were generated on the inner surface of the mold 1.

(Effects of the Invention) As explained above, when the mold of the present invention is used, sticking between the slab and the mold can be prevented and stable continuous casting can be performed.

[Brief explanation of drawings]

Fig. 1 is an explanatory view of the mold of the present invention, (a) is a front view, (b) is a partially sectional side view, and Fig. 2 is a diagram showing the relationship between vibration energy applied to the mold and coefficient of friction. , Figure 3 is
FIG. 3 is a diagram showing the relationship between the vibration frequency of the vibration generator and the internal mold vibration frequency. 1 is a mold, 4 is a mold table, 6 is a vibration generator,
7 is a damping prevention mechanism. Figure 2 Figure 3

Claims (1)

[Claims] (1) In a vibrating mold configured to apply a predetermined vibration to the mold to prevent sticking, the amplitude is 10 to 5.
The mold is equipped with a vibration generator that applies vibrations of 00 μm and a frequency of 1,000 to 10,000 cpm in a direction perpendicular to the slab drawing direction, and the mold table that supports the mold is equipped with a mechanism to prevent damping of the self-vibration of the mold. A high-frequency vibration mold for continuous casting, which is characterized by being installed.