金刚石砂轮三维形貌建模及磨削工程陶瓷的数值仿真与实验研究

发布时间：2018-07-23 17:46

【摘要】：工程陶瓷具有高硬度、高强度、耐高温、耐磨损、耐化学腐蚀以及良好的自润滑性等良好性能,在电子、能源技术、化工、航空航天等科学技术领域得到了广泛的应用,但断裂韧度差,使其成为典型的难加工材料。目前工程陶瓷等难加工材料的精密加工主要通过超硬精细磨料的精密磨削及研磨来实现,为了深化和推广工程陶瓷的应用,必须针对工程陶瓷精密磨削开展深入研究。通过单颗磨粒切削加工研究可以更好的认识复杂磨削加工过程,从而可以简化砂轮磨削及表面损伤原理的分析,而通过砂轮表面仿真形貌模型的建立,可从整体上使砂轮磨削行为的研究变的更加直观,进而有助于准确的评价和预测砂轮的磨削性能和结果。综上,本文以氮化硅陶瓷精密磨削加工为研究对象,通过砂轮表面形貌检测的结果分析,利用数值仿真技术建立了单颗磨粒及整体砂轮表面形貌模型,并在此基础上进行了单颗磨粒切削仿真、砂轮整体磨削仿真,最后通过单颗磨粒切削实验、砂轮磨削实验对形貌建模和数值仿真进行了验证分析,具体工作内容包括:(1)对砂轮进行表面形貌测量,通过砂轮磨粒表面面积密度、磨粒平均个数和出刃高度的分析,并结合利用球坐标上平面切割球实体方法,建立了比较接近实际的虚拟单颗磨粒模型,分析研究了磨刃二面角与积分光密度值之间的关系;进一步利用正态随机函数法建立磨粒尺寸、位置、角度随机分布的砂轮表面形貌模型;最终结合砂轮表面面积密度、磨粒平均个数、出刃高度等参数验证了所建立的虚拟多面体磨粒和砂轮整体模型的有效性。(2)选用球坐标方式切割的单颗磨粒几何模型来模拟金刚石磨粒,利用JH-2材料本构模型以及SOLID164实体单元建立单颗磨粒数值仿真模型,通过多种网格划分方法对磨粒-工件数值模型进行了网格划分,并在LS-DYNA中进行了单颗磨粒切削过程数值仿真,分析了工件的应力、切屑、磨削力等微观变化现象。最后进行了单颗磨粒切削实验,验证了所建立模型和数值仿真的有效性。(3)使用DEFORM-3D建立了磨削数值仿真的金刚石砂轮-氮化硅陶瓷工件数值仿真模型,并进行整体金刚石砂轮磨削氮化硅陶瓷的数值仿真,首先分析了磨削过程中滑擦、耕犁、切削3个阶段的形成过程;进一步仿真分析了微观状态下工件材料的切屑去除过程以及其间的磨削力变化,同时研究了不同的砂轮线速度、磨削深度等工艺参数对磨削力、工件的应力的影响。最后进行了金刚石砂轮磨削氮化硅陶瓷实验,验证了数值仿真的合理性。
[Abstract]:Engineering ceramics with high hardness, high strength, high temperature resistance, wear resistance, chemical corrosion resistance and good self-lubricity have been widely used in the fields of electronics, energy technology, chemical industry, aerospace and other scientific and technological fields. However, the fracture toughness is poor, which makes it a typical refractory material. At present, the precision machining of engineering ceramics and other difficult machined materials is mainly realized by precision grinding and grinding of superhard fine abrasives. In order to deepen and popularize the application of engineering ceramics, it is necessary to carry out in-depth research on precision grinding of engineering ceramics. The complex grinding process can be better understood through the research of single abrasive cutting, which can simplify the analysis of grinding wheel grinding and surface damage principle, and establish the surface simulation topography model of grinding wheel. It can make the research on grinding behavior of grinding wheel more intuitionistic, and it is helpful to evaluate and predict the grinding performance and result of grinding wheel accurately. In this paper, the precision grinding process of silicon nitride ceramics is taken as the research object. Through the analysis of the results of grinding wheel surface morphology detection, the surface morphology models of single abrasive particle and monolithic grinding wheel are established by using numerical simulation technology. On the basis of this, the single abrasive cutting simulation and grinding wheel whole grinding simulation are carried out. Finally, the shape modeling and numerical simulation are verified and analyzed by single grain cutting experiment and grinding wheel grinding experiment. The main work includes: (1) measuring the surface morphology of grinding wheel, analyzing the surface area density, the average number of abrasive particles and the height of grinding edge, and combining with the method of cutting ball body in plane on spherical coordinate. A virtual single particle model is established, the relationship between edge dihedral angle and integrated optical density is analyzed, and the size and position of abrasive particles are further established by normal random function method. The surface morphology model of grinding wheel with random distribution of angle, finally combining the surface area density of grinding wheel, the average number of abrasive particles, The effectiveness of the virtual polyhedron abrasive particle model and the whole grinding wheel model is verified by the parameters such as the height of the cutting edge. (2) the geometric model of the single abrasive particle is used to simulate the diamond abrasive particle by using the spherical coordinate cutting method. The numerical simulation model of single particle is established by using the constitutive model of JH-2 material and the SOLID164 solid element. The numerical model of abrasive particle and workpiece is meshed by various mesh generation methods, and the cutting process of single abrasive particle is simulated in LS-DYNA. The microcosmic variation phenomena such as stress, chip and grinding force of workpiece are analyzed. Finally, a single abrasive cutting experiment is carried out to verify the validity of the established model and numerical simulation. (3) the numerical simulation model of diamond wheel and silicon nitride ceramic workpiece is established by using DEFORM-3D. Numerical simulation of silicon nitride ceramics grinding with diamond wheel is carried out. Firstly, the forming process of sliding, ploughing and cutting stages is analyzed. Furthermore, the chip removal process of workpiece material and the variation of grinding force are analyzed by simulation. The effects of different grinding wheel linear speed and grinding depth on grinding force and workpiece stress are also studied. Finally, experiments on grinding silicon nitride ceramics with diamond wheel are carried out, and the rationality of numerical simulation is verified.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.75

【相似文献】