超声振动超细粉碎技术的理论与应用研究
发布时间：2018-08-15 12:22
【摘要】：超细粉体以其特有的优良特性迅速受到世界各国的重视。超细粉体技术综合性高，涉及范围广，研究起来比较困难。为了获得粒度更细的粉体，世界各国对超细粉体的研究重点主要集中在超细粉碎设备的更新上，使得超细粉碎理论的发展滞后于粉碎设备的发展，超细粉碎理论的研究有还待于进一步改进和完善。 超细粉体是由大量微小颗粒组成的颗粒群，研究超细粉碎理论就避免不了研究颗粒的力学性能。为了研究简便，本文以单颗粒破碎为理论研究对象，建立粉碎数学模型。根据断裂力学以及损伤力学的基本理论，研究单颗粒在粉碎过程中的应力变化、裂纹扩展条件以及相应的能耗关系。从微观方面研究材料内部导致晶体破碎的依据，以及使材料达到破碎所需要的剪切应力临界值。通过上述研究，为材料的裂纹扩展以及粉碎提供了重要的理论依据。 超声粉碎主要是依靠超声波产生的冲击力作用于粉碎物料，导致材料内部产生损伤和裂纹并进一步扩展，最后达到粉碎的效果。超声粉碎系统的优劣主要取决于其振动位移的大小，因此变幅杆的设计就显得极其重要。本文在进行大量理论研究的基础上，设计并制造了一个圆柱圆锥复合型变幅杆，并计算变幅杆的性能参数。通过ANSYS软件对该圆柱圆锥复合型变幅杆进行有限元分析，分析其纵向振动位移曲线，得到变幅杆的数值模拟参数。通过分析对比，发现理论推导与有限元分析所得到的数据误差不大，验证了理论推导与有限元分析的一致性。 在理论研究的基础上，通过仿真软件ANSYS/LS-DYNA模拟超声波冲击固体颗粒的应力-应变过程。观察固体颗粒的应力变化，通过仿真模拟验证利用超声波进行超细粉碎的可行性。 在理论研究以及仿真模拟的基础上，进行超声粉碎试验。通过改变超声粉碎的工艺条件，验证超声粉碎试验的粉碎效果。得到粉碎粒度与粉碎时间的关系变化曲线。通过改变粉碎时间、超声功率、粉碎物料的粒度，，来验证影响超声粉碎的工艺条件。对数据结果进行分析，确定超声粉碎最佳的粉碎时间、颗粒大小以及超声功率。根据试验结果分析，发现超声粉碎方式与表面积粉碎模型比较类似，微小颗粒逐渐从大颗粒表面脱落，最终均匀形成超细粉体。
[Abstract]:Ultrafine powder has been paid more and more attention all over the world because of its unique excellent properties. Ultra-fine powder technology is highly comprehensive, involving a wide range, difficult to study. In order to obtain finer powder, the research focus of the world on ultrafine powder is mainly on the renewal of ultrafine pulverizing equipment, which makes the development of ultra-fine grinding theory lag behind the development of crushing equipment. The research on the theory of ultrafine grinding still needs to be further improved and perfected. Ultrafine powder is a group of particles composed of a large number of tiny particles. The study of ultrafine pulverization theory can not avoid the study of mechanical properties of particles. In order to be simple and convenient, a mathematical model of single particle breakage was established in this paper. According to the basic theory of fracture mechanics and damage mechanics, the stress change, crack propagation condition and energy consumption relation of single particle during comminution are studied. The basis of crystal breakage in the material and the critical value of shear stress for the material to be broken are studied from the microcosmic point of view. The above research provides an important theoretical basis for crack propagation and comminution of materials. Ultrasonic comminution mainly depends on the impact force produced by ultrasonic wave acting on the comminuted material, which leads to the damage and crack inside the material and further expands, and finally achieves the effect of crushing. The merits and demerits of ultrasonic comminution system mainly depend on the magnitude of vibration displacement, so the design of amplitude-varying rod is very important. Based on a large number of theoretical studies, a cylindrical tapered composite horn is designed and fabricated, and its performance parameters are calculated. The finite element analysis of the cylindrical conical composite horn is carried out by ANSYS software, and the longitudinal vibration displacement curve is analyzed, and the numerical simulation parameters of the horn are obtained. Through the analysis and comparison, it is found that the error between the theoretical derivation and the finite element analysis is small, which verifies the consistency between the theoretical derivation and the finite element analysis. On the basis of theoretical research, the stress-strain process of ultrasonic impact on solid particles was simulated by simulation software ANSYS/LS-DYNA. The stress changes of solid particles were observed and the feasibility of ultra-fine grinding with ultrasonic was verified by simulation. On the basis of theoretical research and simulation, ultrasonic crushing test was carried out. By changing the technological conditions of ultrasonic comminution, the grinding effect of ultrasonic comminution test was verified. The curve of the relation between grinding granularity and crushing time was obtained. By changing the grinding time, ultrasonic power and the particle size of the pulverized material, the technological conditions affecting the ultrasonic comminution were verified. The data were analyzed to determine the best crushing time, particle size and ultrasonic power. According to the analysis of the experimental results, it is found that the ultrasonic comminution mode is similar to the surface area comminution model, and the fine particles gradually fall off from the surface of the large particles and form ultrafine powders uniformly.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.3
本文编号：2184184
[Abstract]:Ultrafine powder has been paid more and more attention all over the world because of its unique excellent properties. Ultra-fine powder technology is highly comprehensive, involving a wide range, difficult to study. In order to obtain finer powder, the research focus of the world on ultrafine powder is mainly on the renewal of ultrafine pulverizing equipment, which makes the development of ultra-fine grinding theory lag behind the development of crushing equipment. The research on the theory of ultrafine grinding still needs to be further improved and perfected. Ultrafine powder is a group of particles composed of a large number of tiny particles. The study of ultrafine pulverization theory can not avoid the study of mechanical properties of particles. In order to be simple and convenient, a mathematical model of single particle breakage was established in this paper. According to the basic theory of fracture mechanics and damage mechanics, the stress change, crack propagation condition and energy consumption relation of single particle during comminution are studied. The basis of crystal breakage in the material and the critical value of shear stress for the material to be broken are studied from the microcosmic point of view. The above research provides an important theoretical basis for crack propagation and comminution of materials. Ultrasonic comminution mainly depends on the impact force produced by ultrasonic wave acting on the comminuted material, which leads to the damage and crack inside the material and further expands, and finally achieves the effect of crushing. The merits and demerits of ultrasonic comminution system mainly depend on the magnitude of vibration displacement, so the design of amplitude-varying rod is very important. Based on a large number of theoretical studies, a cylindrical tapered composite horn is designed and fabricated, and its performance parameters are calculated. The finite element analysis of the cylindrical conical composite horn is carried out by ANSYS software, and the longitudinal vibration displacement curve is analyzed, and the numerical simulation parameters of the horn are obtained. Through the analysis and comparison, it is found that the error between the theoretical derivation and the finite element analysis is small, which verifies the consistency between the theoretical derivation and the finite element analysis. On the basis of theoretical research, the stress-strain process of ultrasonic impact on solid particles was simulated by simulation software ANSYS/LS-DYNA. The stress changes of solid particles were observed and the feasibility of ultra-fine grinding with ultrasonic was verified by simulation. On the basis of theoretical research and simulation, ultrasonic crushing test was carried out. By changing the technological conditions of ultrasonic comminution, the grinding effect of ultrasonic comminution test was verified. The curve of the relation between grinding granularity and crushing time was obtained. By changing the grinding time, ultrasonic power and the particle size of the pulverized material, the technological conditions affecting the ultrasonic comminution were verified. The data were analyzed to determine the best crushing time, particle size and ultrasonic power. According to the analysis of the experimental results, it is found that the ultrasonic comminution mode is similar to the surface area comminution model, and the fine particles gradually fall off from the surface of the large particles and form ultrafine powders uniformly.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.3
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