JPS6240962A - Oscillation device for continuous casting device - Google Patents

Abstract

PURPOSE:To improve the quality of an ingot surface by detecting the rotating angular position of an eccentric body connected to a casting body and changing the revolution of a hydraulic motor by a servocontrol valve via a control until thereby applying saw tooth oscillation waveform to a casting mold. CONSTITUTION:The revolution of the hydraulic motor 20 is transmitted by a shaft 21 to the eccentric body 22 and the oscillation formed by the body 22 is transmitted via an oscillation rod 23 to the casting mold. A detector 24 is attached to the other end of the shaft 21 to detect the rotating angular position of the shaft 21. The information on the rotation angular position detected by the same is transmitted to the control unit 27. The command for the revolution of the motor 20 is applied from the unit 27 to the servocontrol valve 28 in accordance with such information on the rotating angular position to change the revolution of the motor 20 at the one cycle period of the generated oscillation, thereby applying the saw tooth oscillation waveform to the casting mold. The lubricating agent supplied to the casting mold is thereby admitted uniformly between the casting mold and the surface of the ingot solidifying on shrinkage. The quality of the ingot surface is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oscillation device for a continuous casting machine.

(Prior Art and Process of the Present Invention) As is well known, in a continuous casting apparatus, for example, when the surface of molten steel reaches a predetermined level in a mold, pinch rolls are activated to pull the slab downward together with a dummy bar. At the same time, vibration, or oscillation, is applied to the mold.

This oscillation operation is to prevent the cast slab from sticking to the inner surface of the mold, that is, to improve peeling, and also to improve the surface quality of the cast slab. done in order to Therefore, in this operation, it is necessary to adjust the vibration conditions to appropriate values depending on the steel type, the size and shape of the slab, etc. As oscillation devices, mechanical oscillation devices using an eccentric body and hydraulically operated oscillation devices are known. As introduced in the publication, a proposal has been made to change the vibration frequency by interposing a continuously variable transmission to drive the eccentric body and controlling the rotation speed of the continuously variable transmission. Regarding the latter, an example of its improvement is introduced in Japanese Patent Publication No. 51-48129.

By the way, attempts have been made to adapt mechanical oscillation devices to casting conditions by focusing on the frequency of vibration (that is, focusing on the waveform of vibration) during vibration conditions. For example, according to Japanese Patent Publication No. 51-2053, in the early days of continuous casting technology, anharmonic vibration,
In other words, a sawtooth waveform has been proposed to prevent heat transfer reduction, and in this case, the time distribution between the downward stroke (stroke from top dead center to bottom dead center) and the upward stroke in mold vibration is 3:
It is said that a ratio of 1 is good. However, the device for forming such a sawtooth waveform has the disadvantage that the acceleration is large and an unfavorable impact is generated in the casting process, so recently, an oscillation device for forming the sawtooth waveform has not been used. Therefore, in recent years, most molds have been made to vibrate at a rate that varies sinusoidally.

However, according to the research of the present inventors, for example, in a slab CC, the mold lubricant (powdered additive) supplied to the mold is flowing between the mold and the surface of the slab that has been solidified and shrunk. After observing the above, it was found that the oscillation device that forms the sawtooth waveform (although, of course, the purpose and time distribution of the sawtooth waveform formation are different) is effective, and after trial and error, The following invention has been completed and is presented here.

It is known that in the above-mentioned hydraulic oscillation device using a hydraulic servo cylinder, vibrations of any waveform can be obtained by appropriately controlling the operation of the hydraulic servo cylinder. Hydraulic servo cylinders are disadvantageous in that they are expensive and lack durability and repairability.

[Means for solving problems]

The present invention was created in an attempt to overcome the drawbacks of oscillation devices that form sawtooth waveforms while also avoiding the disadvantages of hydraulic oscillation devices that use hydraulic servo cylinders. The purpose of the present invention is to provide an oscillation device that can form a desired sawtooth waveform at any time during a casting operation while using an oscillation eccentric, which is a technique developed by the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be explained in detail below with reference to embodiments shown in the accompanying drawings. FIG. 1 is a model diagram showing an embodiment of the present invention;
Figure 2 is the 1st T! ! FIG. 3 shows a graph showing the vibration waveform obtained by changing the rotation speed in the apparatus of J, and FIG. 3 shows the vibration waveform obtained by changing the rotation speed in FIG.

FIG. 1 schematically shows the oscillation device of this embodiment, in which the rotation of a hydraulic motor 20 is controlled by an eccentric body 2
2 and the vibrations formed by the eccentric body 22 (e.g. frequency 260 cycles/min, stroke 4) are:
The oscillation rod 23 transmits the signal to a mold (not shown).

A detector (such as a rotary encoder or a pulse pip-up device) 24 is attached to the other end of the shaft 21, and detects the rotational angular position of the shaft 21 (that is, of the eccentric body 22). . Note that the shaft 21 has bearings 25.25
The position is held by

The rotation angle position information of the shaft 21 detected by the detector 24 is transmitted to the control unit 27, and based on this rotation angle position information, the control unit 27 controls the servo valve 28.
, a rotation command for the hydraulic motor 20 is given. Note that depending on the relationship between the rotational speed of the hydraulic motor 20 and the oscillation rotational speed, a speed increaser or a speed reducer may be interposed between the hydraulic motor 20 and the eccentric body 22. Further, 29 indicates a hydraulic pressure source.

Since the oscillation device of this embodiment has the above-described configuration, for example, the number of rotations n to the hydraulic motor 20 is
To give an example of how to give , as shown in FIG.
1, and then rapidly rotated at a high rotation speed n2 between the top dead center and the bottom dead center. The time distribution is preferably 3:1, but such a distribution can be easily formed by controlling the servo valve 28. In this way, hydraulic motor 2
0, the vibration waveform of the mold can be obtained as a sawtooth waveform as shown in FIG. Therefore, by variously combining the time ratios of tl and t2 within one period T of the eccentric body 22, various arbitrary waveforms can be created at any time during the casting operation, from a sine waveform to a sawtooth waveform. Obtainable.

Please note that the casting operating conditions may change during casting.
This often occurs, and in particular, the casting speed usually decreases at the beginning of casting, at the end of casting, and when the current casting is connected to the next casting, but if such information on the casting speed is given to the control unit 27, It can also be linked to casting operation conditions. Further, in the case of this embodiment, it is desirable that the descending speed of the mold vibration be slightly higher than the casting speed of the slab.

In summary, the present invention has the following effects by adopting the configuration described in the claims.

〔Effect of the invention〕

■ Since the vibration waveform that vibrates the mold is formed into a sawtooth shape, the mold lubricant supplied to the mold can evenly flow between the mold and the surface of the slab that has been solidified and shrunk. Good surface quality can be achieved. In particular, the mold lubricant flows uniformly between the mold and the slab surface.
Heat transfer is also performed evenly, making it possible to prevent vertical cracks on the surface of the slab and avoid briefouts. Of course, this phenomenon occurs due to various factors, so it is not possible to uniformly determine the best shape of the sawtooth, but the optimum value of the sawtooth waveform is determined by actual operation at the equipment site. According to the present invention, since the vibration waveform can be changed arbitrarily during operation, the optimum value of the waveform can be easily obtained by controlling the vibration waveform.

■ To obtain an arbitrary sawtooth waveform, we chose a hydraulic motor to rotate the eccentric body, so it is possible to easily obtain arbitrary non-harmonic vibrations with large accelerations, and the frequency can also be adjusted using continuous casting technology. The impact force can be kept small because it is quite large compared to the initial stage, and when an electric motor was tested to obtain anharmonic vibration, it was found that the acceleration was large. Therefore, the electric motor requires a large torque, and as a result, it is necessary to further increase the inertia of the motor.With a normal electric motor, if one cycle is 0.2 seconds, the up stroke takes 0.05 seconds and the down stroke takes 0. It was found that an electric motor could not be used to drive the rotation of the oscillation eccentric because it was not possible to control the rotation time to .15 seconds.

■ Since the present invention uses an eccentric body to vibrate, the eccentric body has been used as a mechanical oscillation device for many years, so the oscillation device of the present invention is highly reliable and can be operated by a hydraulic motor. Above all, it can be arbitrarily controlled and convenient. - ■ Since it is a hydraulic motor, it is inexpensive, and is far superior to hydraulic servo cylinders in terms of repair and durability.

[Brief explanation of the drawing]

Fig. F is a model diagram showing an embodiment of the present invention, and Fig.
FIG. 3 shows a time-stroke graph showing the vibration waveform obtained by changing the rotation speed in the apparatus shown in FIG. 2. FIG. 20... Hydraulic motor, 22... Eccentric body, 23...
Oscillation rod, 24...Detector, 27...
Control unit, 28... Servo valve, 29... Hydraulic power source.

Claims (1)

[Claims] The end of an oscillation rod connected to a mold is connected to an eccentric body, and the eccentric body is rotationally driven in an oscillation device of a continuous casting machine that applies vibration to the mold and adds mold lubricant. A hydraulic motor is installed for
The hydraulic motor is provided with a servo valve that communicates with a hydraulic power source, and rotational angular position information from a detector that detects the rotational angular position of the eccentric body is provided to the servo valve via a control unit. An oscillation device for a continuous casting machine, characterized in that the rotation of a hydraulic motor is varied in one cycle of generated vibrations to give a sawtooth vibration waveform to a mold.