电动缸非正弦振动在板坯连铸机上的应用

介绍了酒钢炼钢一工序的板坯振动台结晶器正弦及非正弦振动技术,对非正弦振动与正弦振动的特点进行了比较。通过对非正弦振动参数进行优化调整,降低负滑脱时间,明显减少了振痕深度和改善了铸坯表面质量,同时增加正滑脱时间,降低了粘连漏钢的风险。     

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。     

基于液压振动的结晶器非正弦振动

 基于宝钢板坯连铸的实测数据,对液压振动装置下结晶器非正弦振动模型相关特性进行了测试和分析。探讨了不同偏斜角度下非正弦振动波形的特点及振动装置驱动力的变化趋势,同时对拉速-振频反向控制模型下,正弦与非正弦振动方式的负滑脱等参数计算结果进行了分析,并对结晶器摩擦力的实测结果进行了讨论。结果表明,结晶器非正弦振动进一步优化了工艺参数,比传统的正弦振动更适合高速板坯连铸生产。     

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变形；给出了确定振动参数的方法。     

非正弦振动技术在连铸生产中的应用

介绍了正弦振动参数及非正弦振动参数的确定方式,结合电炉炼钢厂对非正弦振动控制系统的应用,及不断优化调整工艺参数的实践,期望能以最佳振动方式逐步提高铸坯表面质量。     

板坯连铸结晶器液压振动系统状态监测试验研究

基于板坯连铸试验平台结晶器液压振动装置,检测不同振动参数下液压缸位移等参数,分析了液压缸位移偏差、相位差随振动参数的变化规律,并讨论了非正弦振动波形的特征。结果表明,液压振动装置实现的结晶器正弦和非正弦振动,具有较高的振动精度,显示出其在结晶器振动方面具有明显的优势。     

伺服电动机驱动的连铸结晶器非正弦振动控制系统

伺服电动机驱动的连铸结晶器非正弦振动控制系统采用伺服电动机及相应的驱动控制器代替原工业现场的普通交流电动机,进而通过偏心轴连杆机构驱动连铸结晶器实现非正弦振动。由于伺服电动机按单方向、变角速度规律连续转动,因而具有节能降耗的优点。该控制系统采用S7-400 PLC+FM458高速高性能控制模块作为控制核心,以实现连铸结晶器非正弦振动波形的准确输出和跟踪。结晶器实时跟踪曲线和酸洗试验结果的比较表明,所设计的连铸结晶器振动控制系统运行平稳,铸坯表面质量得到显著改善。该控制系统适用于普通交流电动机通过偏心轴连杆机构实现的正弦振动到非正弦振动的技术改造,且保留了正弦振动的功能。     

高拉速连铸结晶器非正弦振动同步控制模型

 结晶器非正弦振动是实施高拉速连铸和提高铸坯质量的关键技术。提出了结晶器非正弦振动波形及振动工艺参数的确定方法和基本参数的选取原则,并结合高拉速连铸机的特点,分析了振动基本参数对工艺参数的影响规律,建立了拉速与振动基本参数间的同步控制关系,为改善工艺参数、最大限度地发挥非正弦振动技术优势、满足高效连铸生产要求提供了依据和指导。     

结晶器振动技术的发展

介绍了连铸机结晶器振动技术的发展历史和现状,分析了正弦和非正弦振动的形式。     

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。     

非正弦振动在板坯连铸机上的应用

分析了结晶器非正弦振动的振动特性,介绍了安钢引进的VAI板坯连铸机液压振动的振动特点,讨论了非正弦反向振动的各项振动参数,降低结晶器摩擦阻力、提高保护渣耗量,而且可以在低拉速下保证较低的振痕深度,又能在高拉速下保证操作的安全性。并结合生产实践,指出该振动形式对防止粘结漏钢和改善铸坯表面质量有明显作用。     

机械实现的非正弦振动装置在方坯铸机上的应用

通过测试结晶器的振动位移曲线，分析了非正弦振动的波形失真率，该结构验证了振动装置设计的有效性，实验结果表明采用非正弦振动后，能够减少铸坯表面纵裂的发生率，降低铸坯表面的振痕深度，改善铸坯的表面质量。     

包钢薄板坯连铸机结晶器振动台的改进

包钢薄板坯连铸连轧厂连铸机的结晶器振动台改造后的液压式振动台与机械式振动台相比较,具有结构简单、精度高、响应快,可以实现正弦或非正弦振动等优点,通过振动检测进行分析,适时调整结晶器,提高连铸机的作业率和经济效益。     

连铸振动结晶器内液态保护渣消耗机理

通过引入材料学中变截面悬臂梁理论,计算了连铸结晶器弯月面以下初凝坯壳受力,分析了结晶器正弦振动条件下初凝坯壳变形行为,并阐明液态保护渣消耗机理.结果表明,保护渣消耗于正滑脱中后期至下一个正滑脱前中期,包括整个负滑脱时期,负滑脱中期渣道宽度是保护渣消耗的限制性因素.通过增大黏度、振频和振幅使负滑脱时期内保护渣消耗量降低,从而增大了正滑脱时期内渣耗占整个周期内渣耗的比重,使正滑脱时期成为保护渣的主要消耗期.反之,负滑脱时期为保护渣主要消耗期.     

连铸结晶器瞬态摩擦阻力的实验研究

应用连铸结晶器凝固结构模拟装置,研究了结晶器瞬态摩擦阻力随结晶器振的变化规律。结晶显示：在结晶器上部,连铸坯与结晶器之间以粘性摩擦为主,摩擦阻力的主烨规律与结晶器振动的速度波形一致。     

The formation of oscillation marks in the continuous casting of steel slabs

The formation of oscillation marks on the surface of continuously cast slabs has been studied by metallographically examining slab samples and by performing a set of mathematical analyses of heat flow, lubrication, and meniscus shape in the meniscus region of the mold. The metallographic study has revealed that, in agreement with previous work, the oscillation marks can be classified principally according to the presence or absence of a small “hook” in the subsurface structure at the base of individual oscillation marks. The depth of the oscillation marks exhibiting subsurface hooks varies with the carbon content, reaching a maximum at about 0.1 pct carbon, while the oscillation marks without hooks show no carbon dependence. The analysis of heat flow at the meniscus, which is based on a measured mold heat-flux distribution, indicates that depending on the level of superheat, the meniscus may partially freeze within the period of a typical mold oscillation cycle. Lubrication theory has shown that, owing to the geometry of the mold flux channel between the solidifying shell at the meniscus and the straight mold wall, significant pressure gradients capable of deforming the meniscus can be generated in the flux by the reciprocating motion of the mold relative to the shell. A force balance on the interface between the steel and the mold flux has been applied to compute the shape of the meniscus as a function of the pressure developed in the lubricating flux at different stages in the mold oscillation cycle. This has demonstrated that the “contact” point between the meniscus and mold moves out of phase with (by π/2), and has a greater amplitude than, the mold displacement so that just at, or near, the end of the negative strip time molten steel can overflow at the meniscus. From these studies a reasonable mechanism of oscillation-mark formation emerges which involves interaction between the oscillating mold and the meniscusvia pressure gradients in the mold flux, meniscus solidification, and overflow. The mechanism is consistent with industrial observations. E. TAKEUCHI, on study leave from Nippon Steel Corporation     

Depth of oscillation marks forming in continuous casting of steel

The surface of continuously cast slabs is characterized by the presence of oscillation marks. Direct linkage of the continuous casting process and hot rolling process requires that cast slabs should be free of surface defects. In the present work, a mechanical model has been developed for the prediction of the depth of oscillation marks of the depression type. It is based on the beam bending theory and on viscoplastic material behavior. The downward movement of the strand is taken correctly into account, which has not been done in previous models. Auxiliary parts of the model are the models for the determination of the temperatre field and of the fluid flow and pressure in the meniscus region and in the gap between strand and mold. The deflection of the shell is computed as a function of time and distance from the shell tip. The retained deflection, which corresponds to the depth of oscillation marks observed on the slab surface, is determined for different values of stroke, frequency, and casting velocity. The theoretical data are compared with the measured data as available in the literature.     

Optimization of Oscillation Model for Slab Continuous Casting Mould Based on Mould Friction Measurements in Plant Trial

Lubrication and friction between the mould and strand are strongly influenced by mould oscillation, and play an important role in slab quality and operating safety during continuous casting processes. Investigation of mould oscillation is therefore essential for getting a better online control of the mould processes. A feasible approach for the development and optimization of mould oscillation was put forward, which combined online measurement of mould friction, design of negative oscillating parameters and evaluation for powder consumption. Three different control models including sinusoidal and non-sinusoidal oscillation for mould oscillations were developed to investigate and evaluate the effects of oscillation on mould friction and powder lubrication. For the purpose of investigating mould friction between mould and strand, online measurement was carried out on a slab continuous caster equipped with a hydraulic oscillator. Also the comparison of the mould friction in sinusoidal and non-sinusoidal mould oscillation was made for subsequent analysis. The industrial experiment result shows that the combination of inverse control model and non-sinusoidal oscillation mode will contribute to the proper powder consumption, leading to a suitable effect of friction force on strand surface, especially for high speed continuous casting. The proposed method provides reliable basis for guiding and optimizing mould oscillation among control models, sinusoidal oscillation and non-sinusoidal oscillation.