JPS5847544A - Method and device for synchronous type continuous casting - Google Patents

Abstract

PURPOSE:To improve the surface characteristics of an ingot and to obtain dense solidified structure by connecting one end of a central shaft provided with an ultrasonic oscillation converging body to be supplied with electric power via a slip ring to a rotating drum-like synchronous mold of synchronous type continuous casting device. CONSTITUTION:A casting drum 1 which is a synchronous mold has a diameter and width of prescribed sizes. An ultrasonic oscillation converging body 14 is mounted with a central shaft 16 and a disc 17 intersecting orthogonally therewith, and ultrasonic oscillators 18 are radially screwed 19 to the respective end faces on the outside circumference of the regular polygon thereof. One end of the shaft 16 is screwed to the drum 1. A slip ring 22 having channels 25 for supplying electric power to the oscillators 18 is mounted to the other end of the shaft 16. High frequency electric power is supplied from a generator 27 thereof through these channels to the oscillators 18, the oscillation waves whereof are turned by 90 deg. and converged to the large horizontal oscillations of the shaft 16. Said oscillations are transmitted to the drum 1 whereby the radial oscillations are generated. Thus the lubrication between the drum and the solidified shell is improved, the oscillations are transmitted to the inside of the shell and the purpose is achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronous continuous casting method and apparatus for performing casting using a synchronous mold such as a rotating casting drum.

Recently, synchronous continuous casting methods and apparatus have been developed for casting strip-shaped slabs directly from molten metal using a synchronous mold such as a casting drum that rotates in synchronization with the drawing of the slab.

FIG. 1 is a schematic perspective view showing an example of the above-mentioned synchronous continuous casting apparatus. In the drawing, 1.1' is a pair of casting drums having the same diameter and the same length, and the axes of the pair of casting drums t and t' are arranged parallel to each other on the same horizontal plane.
Moreover, the distance between the casting drums t and t' corresponds to the thickness of the slab to be cast.

The casting drums t and -t' are made of copper, for example, and are water-cooled inside, and are driven by a driving means (not shown) at the same circumferential speed and in opposite directions as shown by the arrows.
It rotates in synchronization with the drawing of slabs.

2 is a tundish placed above the casting drum 1.1' for pouring molten steel between the above-mentioned casting drums 1.1', and the lower part of the tundish 2 improves the gap between the casting drums l and t'. A discharge port 3 is provided on the bottom surface along its length.

Molten steel is supplied into the tundish 2 from a ladle so that the molten steel is always maintained at a constant level in the tundish 2. The molten steel in the tundish 2 flows down between the casting drums 1.1' from the outlet 3 provided at the bottom of the tundish. Casting tram.

The molten steel that has flowed down during 1' is drawn downward in synchronization with the rotation of the casting drums t, t', 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.

5.5' is 1 installed below the casting drum 1.1'.
The slab 4 is pulled out by a pair of pinch rolls 5.5', cooled by a cooling device (not shown), and then wound into a predetermined length or introduced into a rolling mill. It is then directly rolled into a product.

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 ones, and typical examples include diameters of 0.5 to 2 m, The width is 1~2m.

Next, various types of the above-mentioned continuous casting method will be explained with reference to FIGS. 2 to 6. Figure 2 shows a twin-drum type machine having a pair of casting rams 1, '1', which is the same type as the equipment shown in Figure 1. Figure (B) shows a vertical type for pulling out the slab 4. Figure (B) shows a horizontal type for pulling out the slab 4 in the horizontal direction.

Figure 3 shows a single-drum type; -6 is a casting drum partially immersed in the molten metal in tundish 2; 7 is drawn out from inside tundish 2 by 60 revolutions of the casting drum, and is turned into a strip. The guide 90-ra, 8 that guides the cast slab 4 is a winding drum that winds up the strip-shaped slab 4.

Figure 4 shows the multi-V ram type, 6/, 6〃, 6'.
are a plurality of small-diameter auxiliary casting drums installed on the top of the casting drum 6, which have the same functions as the single-drum type.

Figure 5 shows a set of rotary casters, 9 has flanges with a larger diameter than the tram body on both end faces, tl is a casting drum,
Reference numeral 10 denotes an endless belt made of steel that has a width spanning both end surfaces of the casting drum 90 and is closely attached in a semicircular arc shape along a part of its outer periphery, and that moves with the rotation of the casting drum 9. is poured into the gap between the endless belt IO and the casting drum 9, cooled and turned into a slab. 11
are a plurality of days on which the endless belt 10 is suspended.

Figure 6 shows a set of belt casters, which is an endless belt made of steel that has 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 2 is poured into the gap between the endless bells 12 and 12', cooled and turned into slabs. 1λ13' is a plurality of days around which the endless belt 12.12' is suspended.

The above-mentioned synchronous continuous casting method has the advantage of being able to cast strip-shaped slabs directly from molten metal, which greatly shortens the process. There are problems with practical application.

+1) Since it is difficult to maintain uniform contact between the casting drum and the molten metal, the initial solidified shell formed on the surface of the molten metal becomes non-uniform and breakouts are likely to occur.

(2) Since the solidification rate of the molten metal is fast and the cast structure remains, the product has coarse crystal nuclei and it is difficult to obtain a dense solidified structure.

(3) Since the lubrication between the casting drum and the solidified shell is not always good, the solidified shell seizes on the casting drum, making it difficult to separate from the casting drum and damaging the surface quality of the slab.

The present inventors 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 ram and the solidified shell, and can generate a uniform solidified shell. We conducted extensive research to develop a continuous casting method and its equipment.

As a result, if ultrasonic imaging of a constant frequency and amplitude is generated on the surface of the synchronous mold, that is, the casting tram, and the vibration velocity (2π x amplitude x frequency) on the surface of the casting ram is increased, the casting ram At the contact surface between the P ram and the solidified shell, relative sliding occurs at this vibration speed, and this relative slip significantly contributes to improving the lubrication between the P ram and the solidified shell, improving the surface quality, and improving the surface quality between the drum and the solidified shell. It was found that vibrations propagate inside the shell through the contact surface with the solidified shell, resulting in a dense solidified structure.

This invention was made based on the above findings, and
In the synchronous continuous casting method in which strip-shaped slabs are continuously cast using a drum-shaped synchronous mold that rotates in synchronization with the drawing of the slab, at the center of one end surface of the synchronous H, An ultrasonic vibration focusing body connected by the central axis generates ultrasonic vibration waves that vibrate in the horizontal direction on the surface of the synchronous mold, and the vibration waves can pull out the slab from the synchronous mold in an excellent manner. The synchronous continuous casting method is carried out in a lubricated state, the 9-tram-shaped synchronous mold rotates in synchronization with the drawing of slabs, and the casting method uses a synchronous continuous casting method in which multiple ultrasonic vibrators are installed radially on the outer circumferential surface. an ultrasonic vibration focusing body in which one disk is attached to a central axis, one end of the central axis being connected to one end surface of the synchronous mold; It is connected,
The present invention is characterized in that it is a synchronous continuous casting apparatus comprising at least a slip ring having a channel for supplying power to the ultrasonic sensor.

Next, the present invention will be explained with reference to examples and drawings.

FIG. 7 shows an assembly diagram of an example of a device used in the method of the present invention. In the drawings, reference numeral 1 denotes a casting drum which is a synchronous mold, has a predetermined diameter and width, and is partially hollow to reduce weight.

14 is an ultrasonic vibration focusing body, and the ultrasonic vibration focusing body 14 is 1. It consists of a central shaft 16 and a disk 17 (two stages in the illustrated example) mounted perpendicularly to the central shaft 16. The casting drum 1 is horizontally attached to the casting drum 1 by screwing one end surface 16a of the casting drum 16 with a screw 15.

The disk 17 is formed into a regular polygonal shape, such as a dodecagon, with a predetermined thickness, and an ultrasonic transducer 18 is attached to each end surface 17a of the outer circumference of the disk 17 by a screw 19. They are arranged radially.

As the ultrasonic transducer 18, it is preferable to use an electrostrictive type sensor with high electric/acoustic conversion efficiency.As such an electrostrictive type transducer, for example, lead zirconate titanate (PZT) is used.
A bolt-tight L'Ansouven-type vibrator, which is made by sandwiching about four fired vibrating elements between iron or duralumin blocks and tightening them with delts, is suitable for this purpose.

“The number of ultrasonic transducers 18 may be selected appropriately depending on the mechanical load determined by the scale of the casting equipment, such as the size of the slab or casting drum. This can be easily changed by increasing or decreasing the number of stages.The ultrasonic vibration focusing body 14 having such a configuration converts the vibration direction of the ultrasonic vibrator 18, and focuses the vibration waves to generate a powerful wave. It has the effect of creating vibration waves.

A vibration amplitude detection vibrator 20 is horizontally attached to the other end surface 16b of the central shaft 16 with a screw 21. The detection transducer 20 is the same transducer as the above-mentioned ultrasonic transducer 18° installed upright on the outer circumferential surface of the disk 17, and when this transducer is mechanically imaged, the amplitude is proportional to the amplitude. Utilizing the reversible phenomenon that AC voltage is generated, the actual vibration amplitude when the ultrasonic vibration focusing body 14 is vibrated is picked up, and this is measured and controlled.

22 is a slip ring for supplying the necessary power to each ultrasonic transducer 18 of the ultrasonic vibration focusing body 14 and for picking up the vibration amplitude generated from the detection transducer 20, and for preventing the imaging from propagating. It is connected to the other end of the detection vibrator 20 via an elastic material such as rubber.

The slip ring 22 has 4 channels, 2 of which
Channels 22a, 22. b is the ultrasonic vibration focusing body 14
The other two channels 22c and 22d are used to supply power to each ultrasonic transducer 18, and the other two channels 22c and 22d are used to pick up the vibration amplitude generated from the detection imager 20. slip ring 2
The power supply channels 22 a, 22 b of No. 2 and the ultrasonic transducer 18 are connected by a conductive wire 23, and
The amplitude pickup channels 22c and 22d and the detection vibrator 20 are connected by a conductive wire 24. Note that the ultrasonic transducers 18 of the ultrasonic vibration focusing body 14 are connected in parallel by conductive wires.

Reference numeral 25 denotes four brushes that are in sliding contact with the slip ring 22, two of which, brushes 25a and 25b, are connected to the power supply channels 22a and 22 of the slip ring 22.
bK slides into contact with the other two brushes 25c.

25d is the pickup channel 22c, 2
It is in sliding contact with 2d. And the power supply channel”
12a, 22b slide contact plastics 25 a, 25
b is connected by a conductor 26 to a high frequency power generator 27 which is supplied with alternating current at a frequency for the three monks, and brushes 25c and 25d, which are in sliding contact with the channels 22c and 22d, are connected by a conductor 28. It is connected to the controller 29.

The casting drum 1 slowly rotates at a speed of about 0.5 m/see, for example, in accordance with the drawing speed of the slab, and includes an ultrasonic imaging focusing body 14 and a detection transducer 20 connected to the casting drum 1. And the slip ring 22 also rotates together with this.

As described above, power is supplied to each ultrasonic vibrator 18 of the ultrasonic vibration focusing body 14 that rotates through the power supply channels 22 a of the slip ring 22 that rotate at the same time.
Since the brushes 25 a and 25 b connected to the high-frequency power generator 27 by a conductor 26 are in sliding contact with the brushes 22 b, the above-mentioned brushes 25 a, 25 b and the slip ring 22 can be used to easily perform the operation.

The ultrasonic vibrator 18 vibrates due to the high-frequency single-phase alternating current supplied from the high-frequency power generator 27, and the vibration waves are transmitted to the central shaft 16 attached to the axis of the disk 17. The direction is changed by 90 degrees, and the imaging waves of each ultrasonic sensor 18 are focused to form a large vibration wave, vibrating the central shaft 16 in the horizontal direction, and transmitting the vibration wave to the casting drum l. . By setting the diameter of the casting drum l to a dimension that excludes its radially vibrating resonance dimension, horizontal vibrations occur in the casting drum l along its axis.

On the other hand, the amplitude of the vibration wave generated as described above is tracked by the frequency tracking of the controller 29 via the amplitude pickup channels 22c and 22d of the slip ring 22 and the brushes 25c and 25d in sliding contact with the amplitude pickup channels 22c and 22d of the slip ring 22 by the detection vibrator 20. Type constant vibration is fed back to the speed controller input,
The output voltage of the high-frequency power generator is controlled so that a vibration wave of a set amplitude is applied to the casting drum 1 by tracking slight fluctuations in the resonance frequency caused by temperature changes in the vibration system.

In order to apply precise vibrations to the casting drum 1 using the method described above, elements constituting the vibration system such as the casting drum 1, the ultrasonic vibration focusing body 14, the ultrasonic vibrator 18, and the detection vibrator 20 are required. However, it is most important to select the dimensions of each of the above-mentioned elements so that they all produce resonant vibrations at the same frequency. In addition, the coupling surface between the casting drum l and the central axis 16 of the ultrasonic imaging focusing body 14, the coupling surface between the disk 17 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 antinode of the vibration wave is located on each surface.

The vibration frequency of the ultrasonic sensor 18 is about 20 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 sensor 18 is 2 to 4 μ.
In addition, the metamorphic ratio (axial amplitude/
The radial amplitude of the disc) is suitably approximately 3.

If it is desired to further increase the amplitude of the vibration waves at the end surface of the central shaft 16 in the ultrasonic vibration focusing body 14, a filter as shown in the front view in FIG. What is necessary is to sandwich the step horn 30 in the shape shown in FIG. The step horn 30 has equal lengths (d2) on the left and right sides from the longitudinal center thereof, and the metamorphic ratio (=) of the amplitude of the vibration wave is set=2.

Next, an example of the dimensional design values of the vibration system of the present invention is shown in the front view of the casting drum shown in Fig. 9, the front view of the ultrasonic vibration concentrator shown in Fig. ″F4f6.
2 The width W of the casting drum l is 2·n, and its diameter (Dl is the dimension excluding the resonance dimension in which the casting drum l vibrates in its radial direction. Focusing body 1
4, the diameter (dl) of its central axis 16 is 601 Bφ, and two disks 17 and 17' are provided at a predetermined interval on this central axis r6.

The thickness tl of the disk 17.17' is 4011&,
From the end surface 16a of the central shaft 16 that comes into contact with the casting drum l,
The distance to the thickness center position of the disk 17 is λ
λ n+1, - The distance (y) from the thickness center position of the disk 17 to the thickness center position of the other disk l7' is λ The distance to the end surface 16b of the axis 16 (zl is -).

The disks 17 and 17' have a regular dodecagonal shape, and ultrasonic transducers 18 having a length of 11 and a diameter of 40 mm are radially attached to each end face of the outer circumference of the disk. The radial resonance diameter of the disks 17, 17' (approximate by a circle in degrees) A
is expressed by the following formula.

However, f, α: Constant E: Young's modulus ρ: Density σ: Poisson's ratio Here, if the casting drum l and the focusing body 14 are made of iron, then λ is 250 A+17011.

Due to the dimensions of the casting drum 1 and the ultrasonic vibration focusing body 14 as described above, horizontal vibration is generated on the surface of the casting drum 1, and the amplitude thereof is equal to that of the ultrasonic vibrator 1.
If the amplitude at the end face of 8 is 4μ, then 12μ(4μ×
3), and a vibration wave of sufficient amplitude is applied to the casting drum l to improve the lubrication between the casting drum l and the slab. Therefore, the slab can be pulled out from the casting drum with excellent lubrication.

As explained above, according to the present invention, when strip-shaped slabs are continuously cast from molten metal using a rotating P-ram-shaped synchronous mold, the contact state between the molten metal and the synchronous mold is controlled. It is possible to form a homogeneous and uniform initial solidification shell, and by generating a large number of crystal nuclei, a dense solidification structure is obtained, the material quality of the product is improved, and the lubrication between the synchronous mold and the solidification shell is good. As a result, the surface properties of the slab are improved and seizing of the slab is prevented, resulting in excellent industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an example of a synchronous continuous casting device;
Figures 2 to 6 are explanatory diagrams showing various types of synchronous continuous casting methods, Figure 7 is an assembly diagram showing an example of the device used in this invention, and Figure 8 is a front view showing an example of a step horn. Figures 9 to 11 are explanatory diagrams showing examples of dimensional settings of the vibration system of the invention, in which Figure 9 is a front view of the casting drum, and Figure 1O is a front view of the ultrasonic vibration concentrator. 11 are side views of the same. In the drawings, l...cast r ram, 2...tandish, 3...
・Discharge port, 4... Slab, 5... Pinch roll, 14
...Ultrasonic vibration focusing body, 16... Central axis, 17...
Disc, 18... Ultrasonic transducer, 20... Detection transducer, 2゛22 Power device, 29,... Controller, 30
...Step horn. Applicant: Nippon Steel Tube Co., Ltd. Keita Tsutsumi (1 other person)

Claims (2)

[Claims] (1) In the synchronous continuous casting method in which strip-shaped slabs are continuously cast using a drum-shaped synchronous mold that rotates in synchronization with the drawing of the slab, a center is placed at the center of one end surface of the synchronous mold. By actuation of an ultrasonic vibration focuser having at least one disk connected by a shaft and having a plurality of ultrasonic transducers radially provided on its outer circumferential surface, a horizontal A synchronous continuous casting method characterized in that an ultrasonic vibration wave that vibrates in the direction is generated, and the slab is pulled from the synchronous mold in an excellent lubrication state by the vibration wave. (2) A drum-shaped synchronous mold that rotates in synchronization with the drawing of slabs, and at least one disk on which a plurality of ultrasonic transducers are radially provided on the outer circumferential surface are attached to a central shaft, and an ultrasonic vibration focusing body, one end of which is connected to one end surface of the synchronous mold; and at least the ultrasonic vibrator, which is connected to the other end of the central axis of the ultrasonic vibration focusing body. A synchronous continuous casting device comprising a slip ring having a channel for supplying electric power.