ELID磨削试验电解参数对光学玻璃表面质量的影响研究

随着国防尖端技术的迅速发展,许多具有独特性能的新材料得到了日益广泛的应用,如光学玻璃、硬质合金.但采用传统磨削工艺加工这些材料很难得到良好的表面质量.在线电解砂轮修整(ELID)磨削技术是一项新的、高效的磨削方法,它有效实现了许多难加工材料的超精密加工和高效加工.针对光学玻璃的特性,将ELID磨削方法应用于光学玻璃的精密加工,通过试验研究ELID磨削中电解参数对加工表面的影响规律,找到了在一定条件下优化的电解参数.试验结果表明,在ELID中,工艺参数对磨削质量及磨削效率有着显著影响,优化工艺参数对ELID镜面磨削有着重要的意义.     

铸铁基金刚石砂轮磨削LHG8光学玻璃表面质量研究

利用ELID磨削技术时光学玻璃LHG8的磨削性能进行了试验研究,通过试验分析磨削工艺参数及砂轮粒度对磨削性能的影响,讨论了磨削中磨削力的变化规律.结果表明,磨削力随着磨削深度的减小而减小,表面质量随着磨削深度的减小与磨粒的减小而提高.在ELID磨削中,能够使用微细砂轮得到较高的表面质量.     

ELID磨削工艺参数优化对光学玻璃表面质量影响的试验研究

在线电解砂轮修整(ELID)磨削技术是一项新的、高效的磨削方法,它有效地实现了许多难加工材料的超精密加工和高效加工.本文针对光学玻璃的特性,将ELID磨削方法应用于光学玻璃的精密加工,通过实验研究了ELID磨削中工艺参数对加工表面的影响规律,找到了在一定条件下优化的工艺参数.     

石榴石铁氧体的ELID高效磨肖

铁氧体、光学玻璃、陶瓷等硬脆材料已经在许多领域获得了广泛的应用.因此有必要研究这类材料的高效磨削方法.本文在平面磨床上采用铸铁结合剂金刚石砂轮在线电解修整方法(ELID)进行了高效磨削实验.分别采用铸铁结合剂金刚石砂轮ELID磨削技术与树脂结合剂金刚石砂轮对石榴石铁氧体工件进行了加工.实验结果表明在同样的磨削条件下,采用ELID磨削技术时的磨削力约为使用树脂结合剂砂轮磨削力的2/5～3/5.实验结果说明采用ELID磨削技术可以提高加工效率,同时保证加工后的表面质量.     

光学玻璃非球面延性域磨削研究

文章利用相关公式计算光学玻璃的临界磨削深度,以及工件速度、砂轮速度、磨粒粒度、磨削深度等对它的影响,分析利用MK9025曲线磨床在延性域状态下加工非球面或者球面的可能性.然后,采用金属基金刚石微粉砂轮,选择合适的磨削用量,利用MasterCAM自动生成加工程序,在MK9025数控光学曲线磨床上进行椭球面磨削实验,得到了较高的工件尺寸精度和较光洁的表面质量,通过实验验证了利用MK9025数控光学曲线磨床进行非球面光学零件精密磨削的可能性,为实际生产提供了现实依据.     

石榴石铁氧体的ELID高效磨削

铁氧体、光学玻璃、陶瓷等硬脆材料已经在许多领域获得了广泛的应用。因此有必要研究这类材料的高效磨削方法。本文在平面磨床上采用铸铁结合剂金刚石砂轮在线电解修整方法（ELID）进行了高效磨削实验。分别采用铸铁结合剂金刚石砂轮ELID磨削技术与树脂结合剂金刚石砂轮对石榴石铁氧体工件进行了加工。实验结果表明在同样的磨削条件下，采用ELID磨削技术时的磨削力约为使用树脂结合剂砂轮磨削力的2/5-3/5。实验结果说明采用ELID磨削技术可以提高加工效率，同时保证加工后的表面质量。     

我国光学玻璃加工用磨削液的现状和发展趋势

本文简介了我国光学玻璃加工用磨削液的现状和发展趋势,指出发展方向和研究重点应该是水基型的磨削液。     

碳纤维复合材料铣削与磨削加工对比研究

使用单层钎焊金刚石磨头和金刚石涂层玉米铣刀对T800碳纤维增强环氧树脂复合材料层压板进行切边加工，研究铣削加工和磨削加工工艺对碳纤维增强复合材料(carbon fiber reinforced plastics，CFRP)表面质量的影响。通过对加工表面微观形貌的观察和表面粗糙度的测量对比，讨论2种加工方式下表面质量差异和缺陷形成的原因。结果表明:磨削加工的表面质量优于铣削加工的表面质量，铣削加工后CFRP表面会出现凹坑和树脂涂覆等缺陷，但磨削加工的表面纤维断口清晰可见，无明显缺陷。铣削工艺下的凹坑是纤维集束断裂而形成的，树脂涂覆是由刀具后刀面与工件材料的频繁挤压、摩擦而形成。在表面质量和加工缺陷要求严格的条件下，应优先选用磨削加工工艺。      

旋转超声磨削加工技术研究进展

旋转超声磨削加工是一种通过将金刚石砂轮复合超声频振动,从而提高对硬脆材料加工能力的特种加工方式,相比于传统磨削具有切削力小、切削热低等特点,已成功应用到光学玻璃、陶瓷及其复合材料的加工生产中。在简要概述了旋转超声磨削的基本原理和发展历程的基础上,主要总结了国内外学者及企业对旋转超声磨削加工装备的研究成果,并对未来旋转超声磨削的研究趋势进行展望。     

基于钛合金砂带磨削的磨削率、表面质量及砂带寿命性能试验研究

针对钛合金磨削加工磨削率低,砂带使用寿命短以及表面质量差等问题,文章分别用正交实验和单因素实验对砂带磨削钛合金的磨削率及表面质量进行了一系列的性能实验研究,得到了十分有用的结论。论文的研究不但可以改善钛合金的表面质量,提高钛合金的磨削率,而且有助于扩大钛合金的应用范围,延长砂带的使用寿命,对生产实践有理论指导意义。     

Application potential of coarse-grained diamond grinding wheels for precision grinding of optical materials

Fine-grained resin bonded diamond tools are often used for ultra-precision machining of brittle materials to achieve optical surfaces. A well-known drawback is the high tool wear. Therefore, grinding processes need to be developed exhibiting less wear and higher profitability. Consequently, the presented work focuses on conditioning a mono-layered, coarse-grained diamond grinding wheel with a spherical profile and an average grain size of 301 µm by combining a thermo-chemical and a mechanical-abrasive dressing technique. This processing leads to a run-out error of the grinding wheel in a low-micrometer range. Additionally, the thermo-chemical dressing leads to flattened grains, which supports the generation of hydrostatic pressure in the cutting zone and enables ductile-mode grinding of hard and brittle materials. After dressing, the application characteristics of coarse-grained diamond grinding wheels were examined by grinding optical glasses, fused silica and glass–ceramics in two different kinematics, plunge-cut surface grinding and cross grinding. For plunge-cut surface grinding, a critical depth of cut and surface roughness were determined and for cross-grinding experiments the subsurface damage was analyzed additionally. Finally, the identified parameters for ductile-machining with coarse-grained diamond grinding wheels were used for grinding a surface of 2000 mm² in glass–ceramics.     

使用雾化液的K9光学玻璃化学机械磨削

根据K9光学玻璃的物理化学特性,在干式化学机械磨削（chemical-mechanical grinding,CMG）的基础上,用超声雾化方法产生NaHCO₃雾化液参与磨削,研制了适合湿式CMG的磨具,对K9光学玻璃试样进行了化学机械磨削试验,得到了雾化环境下磨削结果最优的CeO₂型磨具。在此基础上,采用正交试验法,对比分析工件转速、磨具转速以及雾化液的pH值对K9光学玻璃表面粗糙度和材料去除率的影响。结果表明:工件表面粗糙度受雾化液的酸碱度的影响最强,磨具转速次之,工件转速最弱;对材料去除率的影响,雾化液的酸碱度最强,工件转速次之,磨具转速最弱。使用适量的雾化液可提高加工质量和速度,消除干式CMG产生的粉尘污染,这种方法适于对K9光学玻璃的精加工。      

Relationship between surface roughness and subsurface crack depth during grinding of optical glass BK7

Subsurface damages induced by grinding strongly influence the mechanical strength and optical quality of optical glasses. It is meaningful to rapid evaluate the depth of subsurface cracking through the measurement of surface roughness under different grinding parameters. Based on the features of surface and subsurface cracks as well as the kinetic analysis of surface grinding, the relationship between surface roughness and subsurface crack depth was established. Surface grinding experiments for optical glass BK7 were conducted. Utilizing optical microscope, optical profiling system and polishing-etching technique, the dependence of surface roughness and subsurface crack depth on grinding parameters was systematically analyzed. The predicted model of the relationship between surface roughness and subsurface crack depth was compared with experimental results. It was found that the relationship between surface roughness and subsurface crack depth is influenced by the half apex angle of abrasive grain as well as the magnitude of extra grain extrusion.     

Investigation of grinding modes in horizontal surface grinding of optical glass BK7

Grinding is one of the most important processes to manufacture hard-brittle materials such as optical glass. It is often desired to increase the material removal rate while maintaining the desired surface quality. The success of this approach relies on the better understanding of the relationship between the grinding modes and the characteristics of surface and subsurface integrities. Based on the kinematic analysis of horizontal surface grinding as well as the features of grinding-induced cracks, four grinding modes were proposed. They are brittle mode, semi-brittle mode, semi-ductile mode and ductile mode. The horizontal surface grinding of optical glass BK7 has been studied using diamond grinding wheel. The four different grinding modes have been investigated with the characteristics of surface morphologies before and after etching, surface roughness, subsurface damages as well as indentation depth. It was found that the level of surface roughness and depth of subsurface damage were strongly dependent on grinding mode. This study provides valuable insights into the material removal mechanism and the dependence of surface and subsurface integrities on grinding mode.     

窥视镜热流道注射模设计

窥视镜制品要求具有良好的表面质量及优异的光学特性。介绍了窥视镜注射模实用结构,论述了模具结构特点和工作过程。该模采用热流道注射成型,1模1腔,定距拉杆带动推管落料。模具结构紧凑、工作可靠,可实现全自动操作,具有较高的生产效率。     

Analysis of chatter in contour grinding of optical materials

Chatter that limits ground surface finish has been observed in the deterministic microgrinding of brittle optical materials. In this article, the classical single degree of freedom model for chatter, accounting for both work and tool regenerative effects, is adapted for contour grinding optical surfaces. A linearized expression for the cutting stiffness is developed for the contour grinding geometry based on Preston’s law. Techniques developed to measure the machine frequency response function (FRF) and the Preston coefficient, needed as inputs to the simulations, are described. Numerical simulations based on this model are used to predict the grinding system behavior and to investigate process parameters affecting chatter stability. The stability limits observed during grinding experiments on optical glasses are in good agreement with the simulation results.     

Surface and subsurface integrity in diamond grinding of optical glasses on Tetraform ‘C’

In order to investigate the surface and subsurface integrity of diamond-ground optical glasses, a Tetraform ‘C’ machine tool featuring high close-loop stiffness was used to conduct the ultra-precision machining of fused silica and fused quartz assisted with electrolytic in-process dressing (ELID). An acoustic emission (AE) sensor and a piezoelectric dynamometer were used to monitor the grinding process to correlate the processing characteristics with the generated surface and subsurface integrities, which were characterized by atomic force microscope (AFM), scanning electronic microscope (SEM), and nano-indentation technique. Experimental results showed that for optical glasses the fracture toughness value can be used to predict the machinability while its bigger value always means a better surface and subsurface integrity. During the grinding process of optical glasses, the smaller amplitude and RMS values of AE signal, as well as the smaller grinding forces and the ratio of normal force to tangential force, correspond to a better surface and subsurface integrity. With selected machining parameters and a 6–12 μm grain-sized diamond-grinding wheel, nanometric quality surfaces (Ra<5 nm) with minimal subsurface damage depth (< 0.5 μm) can be generated for fused quartz on Tetraform ‘C’.     

YAG laser cutting soda-lime glass with controlled fracture and volumetric heat absorption

As a volumetric heat source, YAG laser can penetrate through the glass, and has many advantages in cutting of glass with controlled fracture compared with CO₂ laser cutting of glass. This work lays great emphasis on studying the technique of YAG laser cutting of multi-layer glasses. This paper indicates the experiments of YAG laser cutting of two-layer and four-layer soda-lime glasses with controlled fracture. Optical microscope photographs of the separation surface are obtained to examine the surface quality. The impact of laser power, scanning speed and laser beam size on the cutting quality is studied and the optimum processing parameters are presented in the paper. A theoretical model of a thermal laser shock method for separation of two-layer glasses is developed, and the fracture propagation mechanism is studied by examining the temperature and stress fields using finite element software ANSYS. In YAG laser cutting of multi-layer glasses, the temperature distribution is uniform across the thickness of the glass and the fracture propagates from the top and bottom surface to middle so that better separation surface quality can be acquired and multi-layer glasses can be cut simultaneously.