基于新型随形工具的SiC自由曲面去除行为研究

发布时间：2018-09-01 18:17

【摘要】：经济社会的迅速进步促进了军事天文的进一步发展,尤其是航空航天各领域,对于任何国家都具有非凡的意义。各种空间反射镜广泛应用于大型宇航望远镜、多种卫星、激光雷达系统、空间望远镜和高分辨率相机等诸多方面。因碳化硅材料在物理化学领域表现良好,很多国家用来制备空间反射镜。碳化硅反射镜多为小批量和单件生产,目前的磨头磨削等加工方式加工效率较低,制造成本大。砂带磨削是一种高效的磨削方式,并且容易获得较好的加工表面,本文结合砂带磨削和多点成形技术研制新型随形工具系统,既能有效的适应各种加工表面,又能提高加工效率,同时,新型随形工具系统可调形成多种曲面类型压磨板,免除了相应模具设计制造环节,减少资源浪费。新型随形工具系统包括磨抛机构、张紧机构和电解机构等,磨抛机构借助多点成形技术,利用二维移动平台和垂直电机控制螺杆的旋转,进而驱动100个接触头的上下独立移动,可调节构成各种自由曲面压磨板;考虑砂带张紧的简洁、快速、高效,利用气缸带动张紧轮伸缩控制砂带的张紧;驱动轮的包角大于200°,加上驱动轮轮毂包橡胶,可有效地防止打滑现象。运用CATIA V5建立新型随形工具系统三维实体建模,并进行虚拟装配和干涉检验。绘制新型随形工具系统零件工程图并装配调试。对比新型随形工具系统串行和并行调形的特点,根据尺寸和调形频率等需求新型随形工具系统选择串行调形方式,分析其耗时、误差等;借助CATIA DMU仿真新型随形工具系统的调形,根据已有自由曲面,建立曲面三维模型,选取特定平面布置点云并投影到三维模型的曲面上,得到点云自由曲面,提取自由曲面上点云的各点坐标,代入电子样机中实现调形仿真。因砂带磨削中磨粒众多,砂带上各磨粒的形状和磨削深度均不相同,分析整体磨削过程难以实现,可借助有限元分析单磨粒磨削行为。建立一系列单磨粒磨削模型,分析不同磨削用量和磨粒各项参数对切向力、法向力、等效应力等影响。并进行划痕实验,砂带磨削宏观成形实验等,测量材料去除率、表面粗糙度等,验证仿真,研究砂带磨削机理。
[Abstract]:The rapid progress of economy and society has promoted the further development of military astronomy, especially in all fields of aerospace, which is of great significance to any country. Various space mirrors are widely used in large space telescopes, satellites, lidar systems, space telescopes and high resolution cameras. Because of the good performance of silicon carbide in physical and chemical fields, many countries used to prepare space mirrors. Silicon carbide mirrors are mostly produced in small batches and single pieces. The current grinding methods such as grinding have low processing efficiency and high manufacturing cost. Belt grinding is an efficient grinding method, and it is easy to obtain better machined surface. In this paper, a new tool system is developed by combining abrasive belt grinding and multi-point forming technology, which can effectively adapt to all kinds of machined surfaces. At the same time, the new tool system can be adjusted to form a variety of curved surface type grinding plate, which eliminates the corresponding die design and manufacturing links, and reduces the waste of resources. The new tool system includes grinding and polishing mechanism, tensioning mechanism and electrolytic mechanism, etc. The grinding and polishing mechanism uses multi-point forming technology to control screw rotation by using two-dimensional moving platform and vertical motor, and then drives 100 contact heads to move independently up and down. Adjustable to form various free-form surface grinding plates; considering the simplicity, rapidity and efficiency of belt tensioning, the cylinder is used to drive the tensioning wheel to stretch and to control the tension of the belt; the angle of the driving wheel is greater than 200 掳, and the driving wheel hub is rubber coated, Can effectively prevent skid phenomenon. Using CATIA V5 to build 3D solid model of a new tool system, virtual assembly and interference test are carried out. Draw the engineering drawing and assemble and debug the part of the new tooling system. Compared with the characteristics of serial and parallel profile adjustment of the new shape following tool system, according to the needs of size and frequency, the new shape following tool system chooses the serial adjusting mode, and analyzes its time consuming, error and so on. With the help of CATIA DMU simulation, according to the existing free-form surface, the three-dimensional model of the surface is established, and the point cloud free-form surface is obtained by selecting the point cloud in a specific plane and projecting it onto the surface of the three-dimensional model. The coordinates of each point cloud on the free form surface are extracted, and the shape adjustment simulation is realized in the electronic prototype. Due to the large number of abrasive particles in belt grinding, the shape and depth of abrasive particles are different, so it is difficult to analyze the whole grinding process, so the behavior of single abrasive grinding can be analyzed by means of finite element method. A series of single abrasive grinding models were established to analyze the effects of different grinding contents and parameters on tangential force normal force and equivalent stress. Scratch test, abrasive belt grinding macro forming experiment, material removal rate, surface roughness, etc., verification and simulation, study of abrasive belt grinding mechanism.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH74

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