JPS5847543A - Synchronous type continuous casting method - Google Patents

Abstract

PURPOSE:To improve the surface characteristics of an ingot and to obtain dense solidified structure in the stage of casting the ingot continuously with a casting drum-like synchronous mold which rotates by generating ultrasonic oscillations on the surface of the casting drum. CONSTITUTION:A casting drum 1 rotates in synchronization with the drawing speed of an ingot, and an ultrasonic oscillation converging body 14, an oscillator 20 for detection and a slip-ring 22 connected thereto rotate together. The respective oscillators 18 of the body 14 oscillate when supplied with high frequency electric power through a brush 25 and a ring 22 connected to a generator 27 for high frequency electric power. The oscillation waves are turned by 90 deg. to the central shaft 16 of a disc 17 and are transmitted as the large oscillation waves wherein the oscillation waves of the oscillators 18 are converged. The horizontal oscillations of the shaft 16 are transmitted to the drum 1, and make the diameter thereof to resonance sizes, thereby generating the oscillation waves in a radial direction. Then, the lubrication between the drum and the solidified shell is improved, the oscillations propagate to the inside of the shell, and the purpose is achieved. The oscillation waves of the set amplitudes are applied to the drum in follow up to the fluctuations in resonance frequencies generated on account of a change in the temp. of the oscillating system, by the oscillators 20 and a controller 29.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronous continuous casting method that performs casting using a synchronous mold such as a rotating casting ram. Recently, a synchronous continuous casting method and apparatus have been developed for directly casting IJ-shaped slabs from molten metal using a synchronous mold such as a casting drum that rotates in synchronization with the drawing of slabs. . FIG. 1 is a schematic perspective view showing an example of the above-mentioned synchronous continuous casting apparatus. In the drawing, l, 1' are a pair of casting drums with the same diameter and the same length;
The axes of the casting drums 1.1' are arranged parallel to each other in the same horizontal plane, and there is a distance between the casting drums 1.1' corresponding to the thickness of the slab to be cast. The casting drum 1.1' is made of copper, for example, and has a water-cooled interior, and is used to draw the cast silk at the same circumferential speed and in opposite directions as shown by the arrows, by means of a driving means (not shown). rotates in sync with. Reference numeral 2 denotes a tundish placed above the casting drums t, t' for pouring molten steel between the above-mentioned one-piece drums 1.1'. It is formed so as to be located at the upper part of the gap, and a discharge port 3 is provided on the bottom surface extending along its length. Molten steel is fed into the tundish 2 from a ladle in such a way that the molten steel is maintained in the tundish 2 at a partial level. The molten steel in the tundish 2 flows down between the casting P rams l and 'l' from a discharge port 3 provided on the bottom surface thereof. Casting tram. The molten steel that has flowed down between 11 and 11 is drawn downward in synchronization with the rotation of the casting drums l and 1', and is immediately cooled to form a shell.
Solidification is almost completed at a position slightly below the center of the slab, and a strip-shaped slab 4 having a predetermined thickness and width is formed. 5. DA is a pair of pinch rolls provided below the casting drums 1, 1', and while the slab 4 is being pulled out by the pinch rolls 5 and DA, it is further removed (not shown). A boat that is cooled by a cooling device and then wound up to a predetermined length.
Alternatively, the casting drums 1 and 1' can be rolled directly by being guided into a rolling mill.The casting drums 1 and 1' are of appropriate size depending on the size of the product and casting efficiency, from small scale to large scale. In a typical example, the length is 5 to 2 m, and the width is 1 to 2 m. Next, various types of the continuous casting method described above and FIGS. 2 to 6 will be explained. Figure 2 shows a twin-drum type having a pair of casting drums 1 and 1', which is the same type as the equipment shown in Figure 1. The vertical type shown in the same figure (b) is a horizontal type that pulls out the slab 4 in the horizontal direction, and the vertical type shown in the same figure (/ is the vertical type that pulls out the slab 4 from the bottom to the top. Figure '3) is a single-drum type, and 6 is one casting V, a part of which is immersed in the molten metal in the tamp body 2.
Reference numeral 7 designates a rotating shaft of the casting drum 6, a guide roller guided out from inside the tundish 2 and guiding the strip-shaped slab 4, and 8 a winding sheet ram for winding up the strip-shaped slab 4. . Fig. 4 shows a multi-drum type, and 6', 6', and 6'# are a plurality of small-diameter auxiliary casting drums provided above the casting drum 6, which have the same functions as the single-drum type. Figure 5 shows a set of rotary casters, 9 is a casting drum with flanges larger in diameter than the drum body on both end faces, lO
is made of steel and has a width spanning both end surfaces of the casting drum 90, is closely attached in a semicircular arc shape along a part of its outer periphery, and moves with the rotation of the casting drum 9. With the endless belt, the molten metal in the inshoe 2 is poured into the gap between the endless belt 10 and the casting V ram 9 at the tongue, where it is cooled and becomes a slab. Reference numeral 11 denotes a plurality of f'-IJs around which the endless belt IO is suspended. Figure 6 shows a set of belt casters, and xz and lz' are steel or endless belts that have horizontal parts with a predetermined gap above and below, for horizontally pulling out the molten metal discharged from the tundish 2. The molten metal in the tandy pipe 3-2 is poured into the gap between the endless bells 12 and 42', cooled and turned into slabs. 13°13' is an endless belt 12.
There are multiple days that revolve around 12'. Since it is possible to cast slabs in the form of contact strips, it has the excellent advantage of greatly shortening the process, but on the other hand, from the following points, it is difficult to put it into practical use industrially. !
: #l! kIt114 (!:.!Malitd!. - is difficult to achieve, so the initial solidification shell formed on the surface of the molten metal is uneven and breakout is likely to occur. (2) The solidification speed of the molten metal is fast. , and because the structure remains as cast, the product has coarse crystal nuclei and dense solidification.
l. Since am-tt=a-rb is also not good, the solidified shell is baked onto the casting drum, and peeling from the casting drum is difficult and the surface quality of the slab is impaired. The inventors of the present invention have solved the above-mentioned problems, and have developed a synchronous method that has excellent surface properties, a dense solidified structure, good lubrication between the casting drum and the solidified shell, and is capable of producing a uniform solidified shell. Continuous casting method Ultrasonic vibrations of constant frequency and amplitude are generated, and the vibration velocity (2
πX amplitude It was found that the surface properties of the solidified shell were improved, and vibrations were propagated into the interior of the shell ↑ through the contact surface between the drum and the solidified shell, resulting in a dense solidified structure Q. 1 This invention is based on the above-mentioned findings, and uses a synchronous continuous casting method for continuously casting slabs to draw slabs from the synchronous I type in an excellent lubrication state. Characteristic in what you choose to do:
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u. - Examples are shown in assembly drawings. In the drawings, reference numeral 1 denotes a synchronous molding casting drum, which has a predetermined diameter and width, and is partially hollow to reduce weight. Reference numeral 14 denotes an ultrasonic vibration focusing body, and the ultrasonic vibration focusing body 14 is composed of a central axis 16 and a disk 17 (two stages in the illustrated example) attached perpendicularly to the central axis 16. On one end surface of the drum l, on the same axis as that axis,
It is horizontally attached to the casting drum 1 by screwing one end surface 16& of the central shaft 16 with a screw 15. Ultrasonic transducers 18 are radially erected on each end face 17a of the outer periphery of the cage 17 by screws 19, respectively. , ultrasonic vibration/child 1
8, it is preferable to use an electrostrictive type vibrator with high electro-acoustic conversion efficiency. As such an electrostrictive type vibrator, for example, four fired vibrating elements of lead zirconate titanate (PZT) are used. The degree of iron machining is clamped with duralumin blocks and tightened at the root, and the appropriate number can be selected depending on the mechanical load determined by the size of the casting equipment, such as the size of the root tightening. Normally, this can be easily changed by increasing or decreasing the number of stages of the disks 17 attached to the center shaft 16. It converts the vibration direction of the sound wave vibrator 18 and also focuses the vibration wave into a strong vibration wave.
The above-mentioned ultrasonic transducer 18 is erected on the outer peripheral surface of the
With the same vibrator, when this vibrator is mechanically vibrated,
Utilizing the reversible phenomenon in which an alternating current voltage is generated in proportion to the amplitude, the actual vibration part width fP1-# when the wave vibration focusing body 14 is vibrated is measured and controlled. 22 is a slip ring for supplying the necessary power to each ultrasonic vibrator 18 of the ultrasonic vibration focusing body 14 and increasing the vibration amplitude generated from the detection vibrator 20 by one; It is connected to the other end of the sensing vibrator 20 via an elastic material such as rubber to prevent the transmission of the vibration. The ring 22 has 4 channels, of which 2 channels 22a' and 22b are connected to the ultrasonic vibration focusing body 1.
4 for power supply to each ultrasonic transducer 18, and the other 2
Channels 22c and 22d are Kenchi, Yannel 22a
, 22b and the ultrasonic transducer 18 are connected by a conductor 23, and the amplitude pickup ``Zhao channel 22''
e, 22d and the detection vibrator 20 are connected by the conductor 24!
It is continued. Note that the ultrasonic transducers 18 of the ultrasonic vibration focusing body 14 are connected in parallel by conductive wires. 25 is slip ring 22! 22a of 4 das touching,
The other two brushes 25C and 25d are in sliding contact with the pickup channels 22c and 22d. And power supply channels 22a, 22b
The wires 5a and 25b that are in sliding contact with the conductor 26 are
High frequency power generator 2 to which alternating current of phase commercial frequency is supplied
The brushes 25c' and 25d connected to the pickup channels 22c and 22d in sliding contact with the pickup channels 22c and 22d are
Guide I! 28 is connected to a controller 29 . Ultrasonic vibration focusing wire connected to casting rim “
14, the detection vibrator 20 and the slip ring 22 also rotate together with this. ↓Power is supplied to each ultrasonic vibrator 18 of the ultrasonic vibration focusing body 14 rotating as described above through the power supply channel 22a of the slip ring 22 rotating at the same time.
Since the brushes 25a and 25b, which are connected to the high-frequency power generator 27 by a conductive wire 26, are in sliding contact with the brushes 22b, this can be easily carried out via the brushes 25a, 25b and the slip ring 22. The ultrasonic vibrator 18 is vibrated by high-frequency single-phase alternating current supplied from the high-frequency power generator 27. 900, the vibration waves of each sonic vibrator 18 are focused into a large vibration wave, vibrating the central shaft 16 in the horizontal direction, and transmitting the vibration wave to the casting ram l. The amplitude of the imaging wave generated as described above is determined by the amplitude of the imaging wave generated as described above. The frequency tracking type room vibration speed controller input to the controller 29 via the 25C925d is fed to the fee V pack 5, which tracks slight fluctuations in the resonant frequency caused by temperature changes in the vibration system, and sends vibration waves with a set amplitude to the casting drum l. Control the output voltage of the high frequency power generator so as to give −゛
□In order to apply the A I VCC cutting vibration to the casting r by the method described above, the casting drum l, the ultrasonic vibration focusing body 14. The most important thing is to select the dimensions of the above-mentioned elements so that the elements constituting the vibration system, such as the ultrasonic transducer 18 and the detection transducer 20, all generate resonant vibrations at the same frequency. Also, the coupling surface between the casting drum l and the central axis 16 of the ultrasonic vibration focusing body l"4, the disk 1
7 and the ultrasonic transducer 18, and the coupling surface between the central axis 16 and the detection transducer 20, it is also necessary to design so that the antinodes of the vibration waves are located respectively. It is. The vibration frequency of the ultrasonic vibrator 18 is about 2'0 KHz, which is used for ultrasonic processing such as cutting and drawing, and the amplitude of the vibration wave generated at the end face of the ultrasonic vibrator 18 is 2 to 4 μ.
Furthermore, it is suitable that the transformation ratio (amplitude in the axial direction/vibration in the radial direction of the disk) of the ultrasonic vibration focusing device 14 is approximately 3. If it is desired to further increase the amplitude of the vibration wave at the end surface of the central shaft 16 in the ultrasonic vibration focusing body 14, a filter is placed between the casting drum l and the end surface 16 of the central shaft 16, as shown in the front view in FIG. It is sufficient to sandwich the step horn 30 in the shape of □. The step horn 30 has equal lengths on the left and right sides from its longitudinal center. A front view of the casting drum shown in Fig. 10, a front view of the ultrasound imaging focusing body shown in Fig. 10, the same shown in Fig. 11-,
The side view will be explained.゛The width W of the casting drum 1 is -.n, and the diameter 2) is a resonance dimension in which the casting drum 1 vibrates in its radial direction. The common dimension of the fundamental wave is A, which is obtained by Equation 11 (described later).In general, it is sufficient to select the dimension of the moat larger than A.・The focusing body 14 has its horizontal axis
(7) The diameter 1d) is set to 60mmφ, and two disks 17 and 17' are provided on this central shaft 16 at a predetermined interval. Disc 17. The thickness tl of lτ is 4.0 mlB, and the end surface 16a that comes into contact with the casting drum l of the center axis 1.6
, the distance from the center of the thickness of the disk 17) is the radial deflection diameter of the blocks 17, 17' (approximated by a circle) A is:
It is expressed by the following equation (1). However, f, α: Constant E: Young's modulus ρ: Density σ: Poisson's ratio The step horn 3o, which is sandwiched between the casting drum l and the central axis end face 16a of the focusing body 14, has a central axis end face 16a.
The diameter d on the side in contact with is 60 mm, which is the same diameter as the thin 16, and the diameter dl on the side in contact with the end face of the casting r'um is 40111φ.
and the left and right lengths z', z' from the longitudinal center
is -.゛Casting ram l, focusing body 14 and step horn 30
If the material of is iron, then λ+25.0111. A+ 1
This will be 70 attacks. By dimensioning the casting drum l and the bundle 14 as described above, vibrations are produced in the surface of the casting drum l in its radial direction, ie in the direction towards the surface of the solidified shell;
Assuming that the amplitude at the end face of the ultrasonic vibrator '18 is 4μ, vibration waves of sufficient amplitude to improve the lubrication between the casting drum l and the slab are generated in the casting drum l.
given to. Therefore, the slab can be pulled out from the casting drum with excellent lubrication. As explained above, according to the present invention, when a strip-shaped slab is continuously cast from molten metal using a rotating drum-shaped synchronous mold, a large number of crystal nuclei are generated in the melt, thereby reducing the The material quality of the product is improved by obtaining a dense solidification structure, and the surface quality of the slab is improved due to good lubrication between the synchronous mold and the solidification shell. Excellent industrial effects such as prevention of sticking are brought about.

[Brief explanation of drawings]

Fig. 1 is a schematic and perspective view showing an example of a synchronous continuous casting apparatus, Figs. 2 to 6 are explanatory diagrams showing various types of synchronous continuous casting methods, and Fig. 7 is an apparatus used in this invention. FIG. 8 is a front view showing an example of a step horn, and FIGS. 9 to 11 are explanatory views, FIG. 9 is a front view of a casting drum, and FIG. 1O is an ultrasonic vibration concentrator. front view, 1st
Figure 1 is a side view of the same. In the drawings, l...casting drum, 2... tamp tip, 3...
・Ejection 6.4... Slab, 5... Vinci roll J1
4... Ultrasonic vibration focusing body, 16... Central axis, 17.
... Disk, 18... Ultrasonic transducer, 20... Detection transducer, 2.2 Power generator, 29... Controller,
30...Step horn.
'Demonto, Nippon Steel Tube Co., Ltd., Ai Hirutsutsumi, Keitabe (and 1 other person) Bu' Rei 2 map

Claims (1)

[Scope of Claims] In a synchronous continuous casting method in which strip-shaped slabs are continuously cast by a drum-shaped synchronous mold that rotates in synchronization with the drawing of slabs, one end surface of the synchronous mold The surface of the synchronous mold is controlled by actuation of an ultrasonic vibration focuser having at least one disk in the center of which is connected by a central axis and on the outer circumferential surface of which a plurality of ultrasonic transducers are provided radially. To,
generating an ultrasonic vibration wave vibrating in the radial direction, and drawing the slab from the synchronous mold by the vibration wave;
A synchronous continuous casting method that is characterized by being performed under excellent lubrication conditions.