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.

Investigation and Application of Non-sinusoidal Oscillation Technique of Mold

To improve the slab quality, a kind of non-sinusoidal oscillation technique of mold driven by elliptic gears was developed. The waveform functions of non-sinusoidal oscillation were determined, and the calculation method and curves of technological parameters for non-sinusoidal oscillation were given. At the case of waveform deviation factor a equal to 0.31 and oscillation amplitude h equal to ±2.7 mm, the relationship between oscillation frequency and casting speed is determined, and the technological parameters for non-sinusoidal oscillation are calculated. The testing results of industrial application indicated that this technique could not only improve the Slab surface quality, but also reduce the steel breakout.

Mechanism analysis of non-sinusoidal oscillation of continuous casting mold synchronously driven by double servomotors

Due to the disadvantages of complexity,high maintenance and vast investment of the electro-hydraulic servo oscillator,a new mechanical device synchronously driven by double servomotors was proposed. The working principle of the non-sinusoidal oscillator was analyzed and the model of the oscillator was validated via simulation software.Then,taking advantage of resonance technology,the hinging force and moment were calculated. The results showed that the hinging force and driving moment reduced,which was useful in reducing the impact of the hinge and prolonging the service life of the bearing. Besides,the best initial spring pressure was 0. 9 times the mold gravity,which improved the oscillation system stability and reduced the load fluctuation and servomotor driving power.

Time-Domain Analysis of the Periodically Discontinuously Forced Fractional Oscillators

A new method for the solution of non-sinusoidal periodic states in linear fractionally damped oscillators is presented. The oscillator is forced by a periodic discontinuous waveform and a viscous element is taken into account. The presented method avoids completely the Fourier series calculations of the input and output oscillator waveforms. In the proposed method, the steady-state response of fractionally damped oscillator is formulated directly in the time domain as a superposition of the zero-input and forced responses for each continuous piecewise segments of the forcing waveform, separately. The whole periodic response is reached by taking into account the continuity and periodicity conditions at instants of discontinuities of the excitation and then using the concatenation procedure for all segments. The method can be applied efficiently to discontinuous and continuous non-harmonic excitations equally well. Solutions are exact and there is no need to apply any of the widely up-to-date used frequency approaches. The Fourier series is completely cut out of the oscillator analysis.

连铸结晶器缓振行为分析

连铸结晶器采用8段式非正弦振动波形可使铸坯裂纹更少,裂纹愈合能力更强,但是其对应加速度大,容易产生振动冲击影响结晶器运行.以钢板弹簧和柔性弹簧对结晶器振动过程进行刚性加持和柔性减振,利用钢板弹簧和柔性弹簧的弹簧力平衡振动冲击产生的惯性力,可以达到减小冲击的目的.计算分析发现相同载荷下柔性弹簧比钢板弹簧的应力大,且每增加10%载荷,柔性弹簧最大应力比钢板弹簧多增加21.23 N.通过二分法计算发现,柔性弹簧平衡87.5%的惯性力,钢板弹簧平衡12.5%的惯性力,可以减小90%以上因加速度产生的冲击,为连铸结晶器8段式非正弦振动波形应用提供参考.

构造结晶器非正弦振动波形函数的方法

提出了两种构造结晶器非正弦振动波形函数的方法。所构造的两种波形函数均用于液压伺服系统驱动的结晶器振动试验装置，效果良好。

结晶器非正弦振动波形及参数研究

提出了一种既具有非正弦振动的全部特征，又具有正弦振动优点的非正弦振动波形；给出了确定振动参数的方法。

椭圆齿轮驱动结晶器非正弦振动的研究

开发并应用了椭圆齿轮驱动结晶器非正弦振动装置。在分析非正弦振动产生原理的基础上,给出了振动的位移、速度和加速度函数,并提出了实现机构——椭圆齿轮驱动机构。采用了弹簧缓冲的结晶器谐振技术,提高了振动平稳性,减少了振动冲击和驱动电动机功率。对振动的工艺参数和动力学特性进行了分析。工业应用表明此技术对减少拉漏、减轻振痕、提高铸坯表面质量及提高拉坯速度等方面效果显著。

机械驱动结晶器非正弦振动的开发

采用运动的叠加原理 ,开发出一种机械驱动的非正弦振动装置。生产实践证明 ,它同液压伺服系统驱动的非正弦振动系统相比具有投资省、操作维护方便、可靠性高等优点。现已应用于首钢第一炼钢厂的板坯连铸机 ,并取得显著的效果。

连铸结晶器非正弦振动波形的研究

对目前几种比较有代表性的结晶器非正弦振动波形做了介绍，并提出了一种新的波形。从振动动力学、最大上振速度、最大加速度及主要振动工艺参数值等方面，对各种波形特点进行了全面分析和比较。结果表明，YSU波形、WIS波形要优于其他波形。同时提供了这几种波形的主要振动工艺参数的一种计算方法，为其推广应用提供了便利条件；另外，还对非正弦振动波形偏斜率的取值进行了分析，认为其最佳取值范围为0．25-0．35。

连铸结晶器非正弦振动参数及同步控制模型的研究

给出了一种用于连铸生产的非正弦振动波形，并对其波形参数和振动工艺参数进行了讨论。结果表明：这种非正弦振动波形具有较好的拉坯速度适应范围，能够满足连铸生产的要求。另外，还对其波形参数的选择方法进行了探讨，导出了该非正弦振动的同步控制模型。

高拉速下连铸坯振痕形成机理及振动参数优化

通过分析2.0m/min拉速稳定浇铸时振动周期内弯月面初凝坯壳的受力情况,阐述了高拉速连铸坯表面振痕形成过程,给出振动参数与最大液体摩擦力和最大保护渣渣道动态压力关系;结合振动参数对振动过程参数的影响和实际设备状况,提出了振动参数优化方向,确定了拉速升至2.2m/min时的振动参数值.结果表明.弯月面初凝坯壳在钢水静压力、摩擦力和保护渣渣道压力作用下随凝固进程形成振痕,振痕生成位置取决于初凝坯壳糊状区固相分率;随拉速提高,应降低振频、增大振幅和非正弦振动因子,以改善振动效果和振痕形貌;拉速升至2.2m/min时的适宜振频、振幅和非正弦振动因子分别为145min^(-1),±5.0mm和0.25.

结晶器非正弦谐振技术的开发与应用

研究了非正弦振动发生装置。构造了非正弦振动的波形函数,开发了非正弦振动发生装置和结晶器谐振技术,给出了最佳谐振弹簧力的计算方法。针对首钢大板坯连铸机,优化了非正弦振动的工艺参数,减小了负滑动时间和最大相对速度差,增加了负滑动率、正滑动时间和负滑动量。此技术应用于首钢板坯连铸机,且对采用非正弦振动和正弦振动的两流铸坯进行对比分析。结果表明,此非正弦振动技术在减少粘结性拉漏、减少表面裂纹及减轻表面振痕、提高铸坯表面质量等方面均取得了明显效果。

结晶器的非正弦振动

给出了建立非正弦振动的一般方法，得到了非正弦振动的振幅、振频、波形偏斜率以及拉坯速度所必须满足的关系式，为这一先进技术的应用提供了必要的理论基础。

连铸结晶器非正弦振动波形构造及参数研究

基于最佳振动模式特点构造出连铸结晶器非正弦振动波形,分析了波形动力学特性,给出振动过程参数表达式,讨论了振动基本参数选取原则和确定方法,确定了1.8m/min拉速下振动基本参数值。研究表明,振动波形函数易于工程实现,波形动力学性能良好,振动波形和过程参数解析式为基本参数优化和提高控制精度创造了条件,振动基本参数的选取和确定为最大限度地发挥连铸机潜能提供了指导。

结晶器非正弦高频振动电液伺服控制系统的研究

开发了非正弦振动波形和计算机控制的电液伺服系统 ,用于提高拉坯速度和铸坯的表面质量。利用 C语言和汇编语言编制了界面友好的计算机控制软件 ,推导了液压伺服控制系统的数学模型。在半板簧结晶器振动试验装置上 ,模拟了小方坯连铸机的非正弦振动。研制的液压伺服控制系统响应速度快、控制精度高 。

新型结晶器非正弦振动系统弹性振动响应的研究

针对开发的逆平行四连杆驱动的串接式全板簧结晶器非正弦振动系统,利用集中参数法建立该系统扭振与线振相耦合的动力学模型,并推导其运动微分方程。采用谐波平衡法求出系统的弹性振动响应,时域分析结果表明,在某些工作频率下结晶器运动规律产生畸变,系统发生剧烈弹性振动。频域方面,由FFT分析得出系统发生共振是结晶器运动规律产生畸变的原因,其本质是弹性振动响应的频谱中谐波明显增多,谐波幅值大幅增加。在此基础上分析系统各类激励对弹性振动的影响,结果表明,具有多频性的内激励是系统共振的决定因素,决定了共振的频率,而外激励只影响共振峰值的大小。这些结论为该振动系统的进一步应用及结晶器非正弦振动系统的平稳性研究提供了理论依据。

由补偿法构建封闭非圆齿轮节曲线

由于现有的封闭非圆齿轮设计方法不能满足任意给定的传动要求,提出基于补偿思想的构建封闭非圆齿轮的方法。首先给出该方法的机理与运算步骤,根据曲线的光滑特性和节曲线的封闭条件,推导由传动比函数获得节曲线方程的过程;然后根据连铸机结晶器的非正弦振动形式,构建适用于此运动过程的一对非圆齿轮节曲线,针对传动比范围过大引起的根切或压力角过大的情况,提出由两对非圆齿轮串联组合的方法,并给出两对非圆齿轮节曲线的设计方法。以实际工程应用为例,分别计算由一对和两对非圆齿轮获得非正弦振动方式的节曲线,从而说明该方法的实用性。

高拉速连铸结晶器非正弦振动频率的研究

结合结晶器传热模型、热/应力模型和现场实际,建立了描述结晶器内液体保护渣膜摩擦力的模型,分析了某钢厂1.8 m.min-1拉速下结晶器非正弦振动频率对液体摩擦力的影响,给出了振频选取原则,确定了拉速1.8 m.min-1和升至2.0 m.min-1时的最佳振频。