脉冲光纤激光修整青铜金刚石砂轮机理研究

发布时间：2018-04-29 12:44

本文选题：激光烧蚀 + 青铜金刚石砂轮　；参考：《湖南大学》2016年博士论文

【摘要】：金刚石砂轮是超硬磨料砂轮的一种,相比于立方氮化硼(CBN)超硬磨料砂轮具有制造成本低,经济效益好等优势。因其进行精密的整形和修锐困难,限制其优异磨削性能的发挥。由于金刚石硬度极高,传统的单一的修整方法是基于“硬碰硬”的加工修整,不适应于青铜金刚石砂轮。激光修整技术集激光技术、材料加工技术、传感器技术、精密磨削技术及计算机技术于一体,是一门多学科交叉的边缘学科和新兴的先进修整技术,具有广泛的应用。该技术其实质是基于脉冲激光烧蚀机理,将聚焦后的高能脉冲激光束辐照于匀速转动的砂轮表面,实现修锐与整形的合二为一,但目前仍有众多问题急需解决。本文在国内外研究的基础上,结合青铜金刚石砂轮的本质特点,采用脉冲光纤激光对青铜金刚石砂轮进行修整,深入的研究其机理,并对修整过程中出现的物理现象包括相爆炸效应、蒸发效应、等离子体特性以及传热效应等进行理论分析,在此研究基础上,提出一种新型单切向液柱流脉冲光纤激光修整工艺方法,为烧蚀青铜金刚石砂轮提供理论指导与工艺优化。首先,在现有的激光修整系统基础上,使用脉冲光纤激光器作为修整中的加热光源,搭建脉冲光纤激光烧蚀青铜金刚石砂轮试验修整平台,阐述脉冲光纤激光修整砂轮系统及运行工作流程,修整系统主要包括脉冲光纤激光器、外光路传输装置、激光器控制器、二维移动平台等组成。其次,脉冲光纤激光具有脉冲时间短、能量强等特点,采用脉冲光纤激光修整青铜金刚石砂轮会出现一些新的物理现象,包括蒸发效应、等离子体屏蔽效应和相爆炸等物理过程,分析相爆炸对激光修整青铜金刚石砂轮产生的不利影响,并对相爆炸进行理论研究；对脉冲光纤激光修整青铜金刚石砂轮表面形成等离子体机制进行理论分析,提出脉冲光纤激光烧蚀青铜材料表面等离子热电离和碰撞电离机制布居概率模型,得到二种电离机制作用下,形成等离子体布居数率,数值结果表明碰撞电离是脉冲光纤激光修整青铜金刚石砂轮形成等离子体的主要机制,电离的铜离子会形成黑色氧化物粒子,覆盖在青铜金刚石砂轮表面；应用等离子体气体方程模型,数值分析等离子体膨胀速度与线度、吸收效应及反冲压力效应,结果表明等离子体吸收效应小、反冲压力低,实际激光修整中可以不考虑其影响,为脉冲光纤激光烧蚀青铜金刚石砂轮提供了理论指导。随后,针对实际烧蚀青铜金刚石砂轮过程中,多脉冲激光修整青铜金刚石砂轮传热模型与单脉冲的基础上建立的传热方程有着本质区别,建立多脉冲光纤激光修整青铜金刚石砂轮传热物理模型,并对烧蚀青铜和金刚石分别进行传热数值计算,得出相关条件下修锐青铜和整形金刚石各自激光功率范围。依据传热数值结果,开展相关试验,观察多脉冲光纤激光修整青铜金刚石砂轮的地形地貌和测量修整后其表面凹坑深度值。理论与试验表明多脉冲光纤激光对青铜金刚石砂轮可实现整形和修锐的合二归一,为多脉冲光纤激光烧蚀青铜金刚石砂轮工艺参数优化提供理论指导。最后,应用多脉冲光纤激光修整青铜金刚石砂轮传热物理模型,得到不同激光功率与青铜金刚石砂轮表面温度演化曲线。试验观察修整后青铜金刚石砂轮地形地貌,并对金刚石磨粒表面进行拉曼光谱检测,数值分析与试验结果一致表明脉冲光纤激光修整青铜金刚石砂轮表面会形成石墨化变质层等缺陷。为克服青铜金刚石砂轮激光修整技术的不足和缺陷,提出一种新型单切向液柱流辅助脉冲激光修整青铜金刚石砂轮方法,在砂轮修整中首次运用液流冷却效果。采用单切向液柱流方法后,能避免脉冲高功率激光修整下金刚石出现热传导产生石墨变质层等缺陷,修整后砂轮表面质量高、地形地貌好,金刚石石墨化变质层程度降低,为脉冲光纤激光修整青铜金刚石砂轮提供指导与工艺优化。
[Abstract]:Diamond grinding wheel is a kind of super hard abrasive wheel. Compared with cubic boron nitride (CBN) super hard abrasive grinding wheel, it has the advantages of low manufacturing cost and good economic benefit. Because of its precision shaping and repairing, it restricts its excellent grinding performance. Because of the high hardness of diamond, the traditional single dressing method is based on "hard collision". The processing and trimming is not suitable for the bronze diamond grinding wheel. Laser dressing technology integrates laser technology, material processing technology, sensor technology, precision grinding technology and computer technology. It is a multidisciplinary interdisciplinary frontier subject and a new advanced trimming technology. The technology is based on pulse laser. The mechanism of ablation is to irradiate the focused high-energy pulsed laser beam to the surface of a uniform rotating grinding wheel to achieve the combination of cutting and shaping, but there are still many problems to be solved at present. On the basis of the research at home and abroad, this paper combines the essential characteristics of the bronze diamond grinding wheel, and uses the pulse fiber laser to carry out the bronze diamond grinding wheel. On the basis of the theoretical analysis of the physical phenomena including phase explosion effect, evaporation effect, plasma characteristics and heat transfer effect, a new single tangent liquid column flow pulse fiber laser dressing technology is proposed, which provides the ablation bronze diamond grinding wheel. Theoretical guidance and process optimization. First, on the basis of the existing laser dressing system, the pulse fiber laser is used as the heating source in the dressing. The experimental dressing platform of the pulsed optical fiber laser ablation of the bronze diamond grinding wheel is set up, and the pulse optical fiber laser dressing wheel system and the operating process are expounded. The dressing system mainly includes the pulse. Fiber laser, external optical path transmission device, laser controller, two-dimensional mobile platform and so on. Secondly, pulsed optical fiber laser has the characteristics of short pulse time, strong energy and so on. Using pulse fiber laser to repair the bronze diamond grinding wheel will appear some new physical phenomena, including evaporation effect, plasma shielding effect and phase explosion. The adverse effects of the phase explosion on the laser dressing of the bronze diamond grinding wheel are analyzed, and the phase explosion is theoretically studied. A theoretical analysis is made on the formation of the plasma mechanism on the surface of the bronze diamond grinding wheel by the pulse fiber laser. The plasma thermal ionization and collision ionization on the surface of the pulse fiber laser ablation of the green bronze material are proposed. The number rate of plasma population is formed by two kinds of ionization mechanisms. The numerical results show that collisional ionization is the main mechanism of shaping the plasma of the bronze diamond grinding wheel with pulse fiber laser. The ionized copper ions will form black oxide particles and cover the surface of the bronze diamond grinding wheel. The plasma gas equation model is used to numerically analyze the expansion velocity and linear degree of plasma, the absorption effect and the effect of the recoil pressure. The results show that the absorption effect of the plasma is small and the recoil pressure is low. The actual laser dressing can not take into account its influence, which provides theoretical guidance for the ablation of bronze diamond grinding wheel with pulse fiber laser. In the process of etching bronze diamond grinding wheel, the heat transfer model of the bronze diamond grinding wheel with multi pulse laser dressing is essentially different from the heat transfer equation established on the basis of the single pulse. The physical model of the heat transfer of the bronze diamond grinding wheel is set up by the multi pulse fiber laser, and the heat transfer of the ablation bronze and the diamond is calculated and the phase is calculated. According to the numerical results of heat transfer, experiments are carried out to observe the topography and geomorphology of the multi pulse fiber laser trimming the bronze diamond grinding wheel and the depth of the surface. The theoretical and experimental results show that the multi pulse fiber laser can be realized for the bronze diamond grinding wheel. The combination of plastic and repair is two, which provides theoretical guidance for the optimization of the process parameters of the multi pulse fiber laser ablation of the bronze diamond grinding wheel. Finally, the physical model of the heat transfer of the bronze diamond grinding wheel is repaired by multi pulse fiber laser. The surface temperature evolution curve of the different laser power and the bronze diamond grinding wheel is obtained. The experimental observation of the bronze after the dressing is made. The diamond grinding wheel is topographic and geomorphic, and the surface of diamond abrasive particles is detected by Raman spectrum. The numerical analysis and experimental results show that the surface of the bronze diamond grinding wheel will form the graphitized metamorphic layer on the surface of the bronze diamond grinding wheel. In order to overcome the defects and defects of the laser dressing technology of the bronze diamond grinding wheel, a new type of single cut is put forward. The liquid column flow assisted pulse laser is used to repair the bronze diamond grinding wheel. The liquid flow cooling effect is first used in the dressing of the grinding wheel. After the single tangential liquid column flow method, the defects of the diamond in the high power laser dressing can be avoided. The surface quality of the grinding wheel is high, the terrain and the geomorphology are good, and the diamond is good. The degree of graphitization deterioration decreases, providing guidance and process optimization for pulse fiber laser dressing of bronze diamond wheels.

【学位授予单位】：湖南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG743

【参考文献】