THEORETICAL STUDY OF AN OSCILLATING WAVEFORM FUNCTION AND PARAMETERS FOR CONTROLLING THE NON-SINUSOIDAL OSCILLATION OF A MOLD

A new non-sinusoidal oscillation waveform is constructed for controlling themold oscillation during continuous casting. Casting velocity and oscillation parameters are thenestablished for a computer model of the continuous casting process. The waveform distortioncoefficient ? of waveform function is close to the waveform distortion rate a, so s is taken for awhen the basic parameters are selected initially. The waveform function can be created for the servohydraulic system or the mechanical driving system. Industrial scale experiments show the waveformfunction is effective.

Motion Stability Analysis of Non-sinusoidal Oscillation of Mold Driven by Servomotor

The investments of the electro-hydraulic servo system of the mold non-sinusoidal oscillator are great, the modification ratio of the mechanical type is unable to be adjusted online, and some continuous casters suffer from server resonance during the casting. A mold non-sinusoidal oscillation mechanism driven by servomotor is proposed and the prototype is produced in the lab, the investment is low and the modification ratio is can be adjusted online, and the stability problem is studied. At first the dynamics model of the servomotor non-sinusoidal oscillation is established, and the kinematics differential function is deduced. Furthermore, based on the harmonic balance method, the eigenvalues of the system are solved; the criterion of the stability of the system is put forward. In addition, the eigenvalues and harmonic with different oscillating parameters are analyzed. Analytical results show that the real parts of the eigenvalues are positive, the system will be unstable, and the resonance will occur when the positive real parts of the eigenvalues are extremum. A foundation is established for solving the running smooth problem and next application of this mechanism.

Study on Meniscus Temperature Fluctuation during Mold Oscillation in Continuous Casting by Modeling Experiments

The temperature of the meniscus in continuous casting was measured during mold oscillation by modeling experiments. It is found that the temperature of meniscus varied periodically along with mold oscillation. Based on the above phenomenon, the mechanism of some techniques, such as, hot top mold, high frequency and low amplitude mold oscillation, soft contact mold electromagnetic continuous casting and so on, which can improve the quality of continuous casting billets, was analyzed. The results show that the decrease of the temperature fluctuation of early solidification shell is their common mechanism.

Dynamic Response of Mold Oscillator Interacting with Steel Slabs

A mathematical model to show the dynamic response of the mold oscillator was suggested. The model con- sidered a frictional interaction between the mold oscillator and slab as several connected nodes. The governing equation considered the slab as a multi-degree-of-freedom （DoF） system, and included a hysteresis model to describe elastic-plastic behavior of the slab; the mold oscillator was given two DoF by utilizing pressure and displacement experiment data. Simulations indicate that the mold and slab execute various vibrations, and that mold oscillation marks are caused by a stick-and-slip phenomenon during intervals, in which the slab contacting the mold moves downward compared to the other slab （negative strip time）. The slab shows the formation of mold oscillation marks to previous formation criterion equally when the mold velocity is faster than the casting speed about downward. The oscillation mark will grow up over 2 Hz exciting frequency with constant 4 mm stroke in simulations. Finally, the negative strip time was compared to the frictional force, hysteresis variable, and plastic force to investigate formation mechanism of the oscillation marks.