JPS62127143A - Ultrasonic vibration continuous casting mold - Google Patents

Abstract

PURPOSE:To prevent a stick of molten metal to a mold wall by converting efficiently an ultrasonic vibration mode inflicted on the mold wall to a lamb wave antisymmetry mode and forming the mold wall to enlarge a vibration displacement in a thickness direction thereof. CONSTITUTION:The mold body 1 consists of one pair of short side mold wall 1b and one pair of long side mold wall 1a. An ultrasonic vibrator fitting members 31, 32, 33..., which are the same material as the mold walls 1a, 1b, are fitted with some distance on the outside wall surface 1c against a meniscus point. The fitting members 31, etc., are formed by the same shape, that is, nearly wedge shape, and fit horns 51, 52, 53... perpendicularly on inclined surfaces 31b, 32b, 33b... thereof, respectively, and the ultrasonic vibrators 41, 42, 43... are fitted on each horn end. An inclination angle theta, which is an angle of the fitting surfaces 31b, etc., for the vibrators 41, etc., to the mold walls 1b, etc., is to be as follows. theta=arcsine (Vl/VL), Vl: propagated speed of ultrasonic longitudinal wave in the fitting member, VL: propagated speed of lamb wave antisymmetry mode, propagated in the mold wall. In this way, the mold walls 1a, 1b are efficiently prevented from the stick of the molten metal.

Description

[Detailed Description of the Invention] C. Industrial Application Field] The present invention relates to a continuous casting mold (hereinafter simply referred to as a mold) to which ultrasonic vibration is applied. The present invention provides an ultrasonic vibration mold which is configured to apply ultrasonic vibrations from different directions and prevents molten metal injected into the mold from sticking to the mold wall.

[Prior art]

In continuous casting, the mold is vibrated at a constant amplitude in order to prevent the molten metal 1 from sticking to the mold wall.

The means to vibrate the mold include a vertical reciprocating mold method (oso-sire-shin method) in which the mold itself moves up and down;
Alternatively, as shown in FIG. 5 (plan view), an ultrasonic vibrator 4 is attached to the outer surface of the mold wall 1a via a horn 5 provided in a direction perpendicular to the outer surface of the mold wall 1a to generate ultrasonic vibrations in the thickness direction of the mold wall 1a. There is an ultrasonic vibration method.

As such an ultrasonic vibration method, Japanese Patent Application Laid-Open No. 54-9G431
No., JP-A-56-11155, JP-A-57-5895
No. 4, JP-A-57-62842, JP-A-59-189
No. 040, JP-A-59-18941, etc. are disclosed. This method utilizes the function of applying the above-mentioned ultrasonic vibration to the mold wall to promote separation of the molten metal from the mold wall and prevent the molten metal from sticking to the mold wall.

[Problem that the invention seeks to solve]

The function described above is to use ultrasonic vibration to vibrate the 6 mold wall parts in the thickness direction when they are in contact with the molten metal, causing the molten metal to be unable to follow the movement of the mold wall and cause instantaneous contact between the mold wall and the molten metal. It is thought that seizure is prevented by creating a space between the two. For this purpose, it is necessary that the vibration displacement in the thickness direction of the mold wall be large.

As a result of intensive studies to increase the vibration displacement in the thickness direction of the mold wall, the inventors found that the vibration displacement is largest in plate waves, not in step waves or transverse waves, and among plate waves. It was found that this is an asymmetric wave mode. In other words, the vibration of the mold in the drawing direction and the vibration in the direction perpendicular to the drawing direction contribute to reducing the frictional resistance between the molten metal and the mold, and for this reason plate waves are more advantageous. Furthermore, when comparing symmetrical waves and asymmetrical waves of plate waves, it has been confirmed that the ratio of vibration displacement in the direction perpendicular to the mold wall to vibration displacement in the direction parallel to the mold wall is larger in the asymmetric wave. .

[Means for solving problems]

The present invention was made based on this knowledge, and the ultrasonic vibration mode 1' imparted to the mold wall is efficiently converted into an asymmetric wave mode of a plate wave, thereby reducing vibration displacement in the thickness direction of the mold wall. It is an object of the present invention to provide a mold that prevents molten metal from sticking to the mold wall by forming the mold wall so as to generate a large amount of vibration and applying ultrasonic vibration.

Such ultrasonic vibration continuous casting according to the present invention is carried out in a continuous casting mold equipped with an ultrasonic wave generator that applies ultrasonic vibration to the wall of the continuous casting mold. An ultrasonic wave having an inclination substantially equal to the following angle θ determined from the propagation velocity V1 of the ultrasonic longitudinal wave determined by It is characterized in that the vibrator mounting surface is formed on the wall.

θ-arcsin (Vn/VL) [Operation] The ultrasonic vibration continuous casting mold of the present invention includes an ultrasonic vibrator attached to the mold so as to apply ultrasonic vibration in a direction that does not coincide with the thickness direction of the mold wall, It efficiently generates an asymmetric wave mode of plate waves, thereby increasing the vibration displacement in the thickness direction of the mold wall and preventing seizure.

〔Example〕

The present invention will be explained below based on the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention, and in the figure, 1 indicates a mold body into which molten metal is poured. 2 long side mold walls 1
a + la are provided opposite each other, and the outer surface portion 1c faces the molten metal upper surface edge of each mold wall, that is, the meniscus portion.
The ultrasonic transducer mounting members 31 and 32 are made of the same material as the mold wall.
．． 33. ... are attached to each other at appropriate lengths apart (the figure shows the attachment members 31 on the short side mold wall 1b and the attachment members 32 and 33 on the long side mold wall 1a, respectively).
.

The mounting members 31 and the like have the same shape and are formed in a substantially wedge shape, and are triangular prisms having a right-angled triangular shape in plan view, and the other two corner portions except for the right angle portion are missing. 2 (one surface 31a of the 111 surfaces) forming the right angle part.

32a, 33a... are glued to the mold wall,
Slanted surfaces 31b, 32b, 33b... facing the right angle portions.
One end of the horn 51, 52, 53... is fixed perpendicular to the surface thereof, and an ultrasonic transducer 41...
42, 43... are installed.

Next, conditions for efficiently generating the asymmetric wave mode of plate waves on the mold wall, which is an important element of the present invention, will be explained. This condition is obtained by providing the wedge-shaped mounting member 31 etc. on the outer surface of the mold wall of the meniscus part where ultrasonic vibration is to be applied, and the angle formed by the two surfaces 31a etc. and 31b etc., that is, the ultrasonic vibrator The inclination angle θ (shown in FIG. 2) of the mounting surface 31b such as 41 with respect to the mold wall is determined by the following equation (1).

θ-arcsin (Vs/VL)
-(1) However, Vl: Propagation velocity of ultrasonic longitudinal waves in the mounting member (eigenvalue determined by the material of the mounting member) VL = Propagation velocity of the plate wave asymmetric wave mode propagating in the mold wall By the way, in the mold wall The circumferential displacement U of the mold body l in the asymmetric wave mode of the plate waves and the displacement W in the mold wall thickness direction of the plate waves are respectively expressed by the following equations (21 and (3)).

U-c l<a・d −5in (ka-x-ω-t
) −(21++V−c °cos (ka−x−ω
・L ) - (31 However, C; Constant ka: Wave number (=2πf/V) d: Thickness of mold wall x: Position in U direction t: Time Therefore, the desired increase in mold wall vibration displacement is Maximum value of W l W I IIIax and maximum value of U l U l
Ratio to max I W 1max / l U 1max
This is possible by increasing l W 1max
/ l U 1max is expressed by the following formula (4).

lWimax l lUlmax ka-d VL 1 2πfd VL VL Vt 2 π [d Vt 2d where d - (27r f/V t) - (d/2)
-151 However, f: Ultrasonic frequency Vt: Propagation velocity of ultrasonic transverse waves in the mounting member (specific determined by the material of the mounting member) Since H is a constant (see equation (5)), in the thickness direction of the mold wall To increase the vibration displacement of l W flax / l U Iraax, increase VL, /Vt.
That is, it is necessary to efficiently generate a plate wave asymmetric wave mode with a large VL/Vt.

By the way, between V L 7 V L and d is shown in Figure 3 (
The lines Ao, A, , A2 represent the conditions under which zero-order, first-order, and second-order asymmetric wave modes occur, and the lines So, S, , S? is 0th order, 1st order,
) shows the conditions under which the second-order symmetrical wave mode occurs, and from this figure, l W 1max / l
The vL that maximizes U 1max is determined as follows.

The above vL is as follows, assuming that the Poisson's ratio of the material of the mold wall is ν.
It is expressed by the following formula (6).

jan (&1 (Vt/VL)2 ・d)ta
n I! ν(Vt/VL) 2・d)(2(Vt
/VL) 2-112 (6) Therefore, multiple solutions can be obtained from equation (6) for ■.

In other words, this indicates that asymmetric wave modes of plate waves having many different propagation velocities propagate in the mold wall depending on the magnitude of 7 as shown by the lines Ao, A, . . . A2 in FIG.

The material of the normal mold wall is copper, and ν is 0.
37, Vt (-&E/C2p (1+y)))
is 2270 m/sec, d is 50 to lOOmm, and the ultrasonic frequency r used is preferably 15 to 25 KII2. Under these conditions, d is 1.0 to 3.46, and the solid line arrow in Fig. 3 The asymmetric wave modes Ao, A within the range indicated by the symbol will propagate. Among them high V
Determine the mode A1 that is l/Vt, and determine the determined mode A
d, V determined from the conditions (shape, material) of the mold wall in 1.
Using t, the propagation velocity {circle around (2)} of the asymmetric wave mode A1 propagating in the mold wall is determined.

Further, the above-mentioned Vl is determined by the material of the mounting member, that is, the density ρ and the Young's modulus E, and can be obtained by the following equation (7).

Vx=VE/ρ...(7) Therefore, the angle formed by the two surfaces 31a and 31b of the mounting member, that is, the inclination angle θ, can be found from the determined values of Vl and ■, and the equation (1) above. By arranging the mounting member with the angle of inclination θ on the outer surface of the mold wall in a fixed direction as in this embodiment, the reflectance of ultrasonic vibration on the mold wall becomes smaller than in the conventional case. , it is possible to concentrate the asymmetric wave mode of the plate wave on the part of the mold wall facing the meniscus part, and to increase the vibration displacement efficiently.

Next, the increase in vibration displacement will be explained by comparison with a conventional example.

Internal dimensions: 150 x 300 m (thickness J!
A 0W ultrasonic vibrator was attached to the mounting member, and the mold wall was ultrasonically vibrated. As a result, it is possible to set the imaging displacement in the thickness direction of the mold wall to 3 to 20 μm, which is 1 to 10IIl11 compared to the conventional case of applying ultrasonic vibration from the thickness direction of the mold wall (see Fig. 5). could be significantly improved.

Thereby, in the case of the present invention, it is possible to effectively prevent the molten metal from sticking to the mold wall.

In addition, in the above embodiment, the wedge-shaped mounting member is made of the same material as the mold wall, but the present invention is not limited to this.

Furthermore, it goes without saying that the present invention may be applied to a mold wall integrally provided with a mounting member.

Further, in the above embodiment, a mock mounting member is attached to the mold wall to form the ultrasonic transducer mounting surface, but the present invention is not limited to this, and as shown in FIG. )
The same effect can be achieved by forming a recess 6 having an ultrasonic transducer mounting surface that is inclined at an angle θ with respect to the above, and mounting the ultrasonic transducer 51 (or 52, 53, . . . ) on the mounting surface.

〔effect〕

As described in detail above, the present invention forms a wedge-shaped ultrasonic transducer mounting surface on the mold wall and attaches the ultrasonic transducer to the mounting surface. The mold wall can be vibrated by a large amount of displacement in the thickness direction, which can effectively prevent the molten metal injected into the mold from sticking to the mold wall, enabling stable continuous casting operations. It has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of mold wall vibration content of the present invention, and Fig. 3 shows the relationship between d and VL/Vt for asymmetric corrugated sheet wave generation. Graph, 4th
The figure is a schematic diagram showing another embodiment of the present invention, and FIG. 5 is a diagram explaining the contents of the prior art. 1...Mold body 1a, lb ・=Mold wall 31
, 32.33... Mounting member 41, 42.43...
・Ultrasonic vibrator 6...Indentation patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono Figure 1 W Leather 20

Claims (1)

[Claims] 1. In a continuous casting mold equipped with an ultrasonic vibrator that imparts ultrasonic vibrations to its wall, ultrasonic vertical vibration determined by the wall material or the propagation medium between the ultrasonic vibrator and the wall. Wave propagation velocity V_l and propagation velocity V_L of asymmetric wave mode of plate waves generated in the wall due to ultrasonic vibration application
An ultrasonic vibrating continuous casting mold, characterized in that an ultrasonic vibrator mounting surface is formed on a wall and has an inclination substantially equal to the following angle θ determined from: θ=arcsin(V_l/V_L)