氮化硅陶瓷精密磨削仿真与实验研究

发布时间：2018-03-19 13:31

本文选题：氮化硅陶瓷　切入点：单颗磨粒切削　出处：《湖南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：工程陶瓷材料以其高强度、高硬度、耐磨、耐高温、耐化学腐蚀等优良性能,在航空航天、国防军工和现代医学等重要领域得到广泛的应用。为了达到高质、高效、低成本等要求,目前在工程陶瓷的加工方法中最为成熟、实用,且应用最为广泛的仍是采用超硬金刚石磨料磨具进行磨削加工。磨削加工可视为大量离散分布在砂轮表面的磨粒同时与被加工材料相互作用实现材料去除的过程,而每一个磨粒都存在很多的磨刃,在一定程度上类似于刀具的切削加工,即每一个磨粒都可视为若干车刀的组合。但是磨削加工又比车削复杂很多,因为参与磨削的磨粒数量多,磨粒切削刃形状、尺寸、位置的随机多样性以及磨削工艺参数等多种因素相互影响,使得研究磨削加工材料去除机理异常困难。为深入探讨磨削加工机理,可以从单颗磨粒切削加工研究出发,将单颗磨粒切削结果在磨削加工区域进行有效集成,进而解释磨削加工过程中的各种物理现象,因此单颗磨粒切削加工的机理研究成为认识复杂磨削加工机理的一种重要手段。本文以氮化硅陶瓷精密磨削加工为研究对象,在对砂轮表面磨粒形貌和氮化硅工件表面、亚表面形貌进行检测分析的基础上,建立截角多面体单颗磨粒虚拟模型和含有典型裂纹的工件模型进行单颗磨粒切削仿真,并通过切削实验对仿真结果进行验证。同时根据单颗磨粒模型建立虚拟砂轮模型,基于第一应力理论进行磨削损伤仿真,提出一种基于光照强度的损伤检测方法并对损伤深度进行测量,最后通过实验对仿真结果进行验证、对损伤预测模型进行回归分析和验证。具体研究工作内容包括:1)根据单颗磨粒实际尺寸范围和形状,通过球坐标系对其尺寸进行限制后,运用随机点产生的空间平面再去切分实体和截角多面体相结合的方法建立了截角多面体虚拟磨粒(截面以三到六边形为主)。建立包含Ⅰ型(张开型)和Ⅱ型(滑开型)典型裂纹的工件模型,然后进行单颗磨粒切削仿真,基于第一强度理论对材料去除过程展开分析,并在数控平面磨床上进行单颗磨粒切削加工实验,对仿真模型进行验证。2)基于单颗磨粒切削氮化硅陶瓷的加工路径规划及未变形切屑厚度计算模型,建立各加工参数与表面残留高度之间的数学模型。通过单颗磨粒切削氮化硅陶瓷加工实验,研究加工参数对表面残留高度的影响并以降低残留高度为目标对加工参数进行优化,同时分析了材料去除方式与残留高度的关系。并将优化结果引入到磨削加工中并通过磨削实验对优化结果进行验证。3)结合实验中加工参数与切削力之间的关系,建立各个加工参数与力之间的拟合函数关系式,并根据拟合函数的斜率大小得出在本文设定的加工范围中,进给量对切削力的影响程度最大,工件速度对切削力影响程度最小。在对加工参数与切削力的拟合函数进行无量纲处理的基础上,结合切削力与加工质量成负相关关系这一规律,以切削力为因变量对加工参数的选择范围进行优化,并通过单颗磨粒实验对优化结果进行验证。4)基于金刚石砂轮磨削加工理论基础和砂轮表面形貌建模,以截角多面体磨粒为基础建立优化的局部砂轮仿真模型,并根据第一强度理论对磨削加工亚表面损伤深度进行仿真研究。通过使用角度抛光法对实验工件亚表面损伤深度进行测量后,对损伤预测模型进行回归分析和验证,并根据不同材料和同一材料不同损伤状况对光的反射程度不同,提出一种通过寻找最佳光照强度的新的损伤测量方法对损伤深度进行测量,最后再结合实验结果对加工参数与损伤深度的影响规律展开分析。
[Abstract]:Engineering ceramic materials with high strength, high hardness, wear resistance, high temperature resistance, excellent resistance to chemical corrosion, in the aerospace, widely used in important areas of national defense and modern medicine. In order to achieve high quality, high efficiency, low cost, the processing method in engineering ceramics in the most mature and practical, and the most widely used is made of super hard diamond abrasive tools for grinding. Grinding can be regarded as a discrete distribution in the abrasive and grinding wheel surface and the machined material interaction process of material removal, and each one has a lot of abrasive grinding and cutting tool similar to to a certain extent, each particle can be regarded as a combination of several tools. But the grinding and turning complex many, because in grinding abrasive abrasive cutting edge number, shape, size, position Many factors were diversity and grinding process parameters influence each other, makes the research on grinding mechanism of material removal is very difficult. In order to further explore the mechanism of grinding, from single abrasive grain cutting processing research of the single grain cutting results are effectively integrated in the grinding area, and then explain the various phenomena of grinding in the process, so the single grain cutting mechanism has become an important means for understanding the processing mechanism of complex grinding. The precision grinding of silicon nitride ceramics as the research object, on the surface of abrasive grinding wheel and the workpiece surface morphology of silicon nitride based, detection and analysis of surface topography on workpiece model a truncated polyhedral single particle model and virtual crack were carried out with a typical single grain cutting simulation, and through the cutting experiment of simulation results was verified. At the same time according to the single particle model of virtual grinding wheel model, the first stress theory of grinding damage simulation based on damage detection method is proposed based on light intensity and measure the depth of damage, finally through the experiment to verify the simulation results, the damage prediction model by regression analysis and verification. The research contents include: 1) according to the actual single grain size range and shape, the restriction on the size of the spherical coordinate system, using the method of space plane random point to segmentation entity and combining truncated polyhedra established truncated polyhedra virtual abrasive (section three to hexagonal mainly includes the establishment of type I). (Zhang Kaixing) and type II (sliding type) workpiece model of typical cracks, then single grain cutting simulation, analyzes the first strength theory on the material removal process based on numerical control and The plane grinding machine for single abrasive machining experiments verify the simulation model.2) calculation model of single grain cutting of silicon nitride ceramics machining path planning and undeformed chip thickness based on the mathematical model established between the processing parameters and the surface residual height. Through single grain cutting machining of silicon nitride ceramics experiment research of process parameters on surface residual height influence and to reduce the residual height on the processing parameters were optimized, and analyzed the material removal modes and residual height relationship. And the optimization results are introduced to the grinding processing and the optimization results of grinding experiments to verify the.3) combined with the relationship between machining parameters and cutting in the experiment, the fitting function between the establishment of various processing parameters and force, and according to the result of the slope of the fitting function in the processing of the scope of this set in, Influence of feed rate on cutting force of the maximum, minimum influence of workpiece speed on the cutting force. The fitting function of machining parameters and cutting force based on dimensional processing, combined with the cutting force of this Law and negatively correlated with the processing quality, the cutting force as the dependent variable selection range of processing parameters optimization and particle experiments were performed to validate the.4 results of optimization by single abrasive diamond wheel grinding) theory and grinding wheel surface topography modeling based on the truncated polyhedra abrasive to establish local wheel simulation model optimization as the foundation, according to the first strength theory for simulation research of the subsurface damage measurement of grinding depth. The workpiece subsurface damage depth by using the angle polishing method, the damage prediction model by regression analysis and verification, and according to different materials and different materials of the same The damage degree is different from the light reflection degree. A new damage measurement method based on finding the best light intensity is proposed to measure the depth of damage. Finally, combined with the experimental results, the influence rule of processing parameters and damage depth is analyzed.

【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ174.6

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