激光切割系统性能对切割质量的影响研究

主要研究了切割系统性能对切割质量的影响,通过实验数据对比,对光束模式、偏光性、喷嘴和气流等系统参数进行实验研究,总结出了最优系统参数。     

基于提高数控等离子切割件质量的研究

重点介绍国内数控等离子切割技术的现状和数控等离子切割出现的问题与控制措施。通过对割嘴高度、切割速度和工作气压对切割质量的影响与控制,切割热变形的影响与控制,切割系统抗干扰的影响与控制,数控切割软件的影响与控制等四个方面的探讨分析,可以有效避免数控等离子切割出现废品,提高了数控等离子切割件的质量。     

CO2 laser cutting of stained glass

This paper covers the CO₂ laser cutting of stained glass using a Ferranti MF400 CNC laser cutting machine. The report examines the various laser cutting parameters required to generate a cut surface in glass which will require minimal post-treatment to be carried out, and also investigates the degree of geometrical intricacy that can be attempted, together with the associated limitations, in cutting 2D glass components. The experimental procedure used to obtain the necessary information for a preliminary database on the laser cutting of stained glass is also detailed. Finally, the implications and applications of the investigative work are examined for commercial situations through construction of a simple 2D test artefact.Notation f pulse frequency (Hz) - k thermal conductivity (W/mK) - P laser beam power (W) - Pl pulse duration (10^–5 s) - Pr pulse ratio - Ps pulse separation (10^–5 s) - P shield gas pressure (bar) - R _a surface roughness (m) - t _s substrate thickness (mm) - V cutting speed (mm/min) - V _opt optimum cutting speed (mm/min) - w kcrf width (mm) - angle of deviation (deg.) - wavelength (m) - d perforation depth (mm)     

Computer controlled brilliant cutting of flat glass

Brilliant cutting is a grinding process used to cut and polish decorative patterns into flat glass. It is a labour intensive process and essentially requires a skilled cutter to present a sheet of flat glass to a grinding wheel. Manual manipulation of the glass is then used to enable the grinding wheel to cut the desired pattern into the glass. This paper describes a CAD/CAM system which has been developed to replace this manual process. The basic design concept involved allowing a grinding wheel to move whilst keeping the workpiece stationary. Fiveaxis manipulation of the grinding wheel was required to ensure that a wide range of decorative shapes could be successfully generated and CNC part programs were developed from 2D drawing data.     

Dimethicone-aided laser cutting of solar rolled glass

Solar rolled glass, with one micro-structure surface and another roughness surface, can cause diffuse refraction of the focused laser spot, and this phenomenon restricts the application of laser manufacturing. In this study, laser cutting of solar rolled glass with a thickness of 2.5 mm was successfully achieved with the help of dimethicone to ensure laser focusing. Dimethicone was coated on the top surface of the rolled glass processing zone, and a Z bottom–up multilayer increment with the X–Y spiral line was applied to control the cutting path. Different viscosity values of dimethicone were considered. Results showed that surface quality increased as the viscosity increased until a certain threshold was reached; afterward, the surface quality decreased or directly caused the cutting to fail. The minimum surface roughness (3.26 µm) of the processed surface (chipping: Width≤113.64 µm, area 215199 µm²) was obtained when the dimethicone viscosity and laser pulse frequency were 1000 mm²/s and 43 kHz (power 25.4 W), respectively. The micro-defects on the processed surface were few, and the edge chipping width and depth of the laser processed surface were small.     

Influence of glass substrate thickness in laser scribing of glass

The thickness of the glass substrate used in liquid crystal displays continues to be decreased from its original thickness of 1.1 mm for the purpose reducing size and weight. The aim of this study was to clarify the influence of the glass substrate thickness during laser scribing with crack propagation caused by laser heating followed by quick quenching. The laser scribe conditions for soda-lime glass substrates with thickness equal to or less than 1.1 mm were obtained in laser irradiation experiments. Two-dimensional thermal elasticity analysis was conducted with a finite element method based on the scribable conditions obtained in the experiment. The laser scribable conditions can then be estimated by the upper limit of the maximum surface temperature, T_max, and the lower limit of the maximum tensile stress, σ_tmax, in the cooling area, regardless of the glass substrate thickness. There is a substrate thickness with which the maximum tensile stress σ_tmax becomes the largest under each scribe condition. The substrate thickness with which σ_tmax becomes the largest is obtained at a faster scribe velocity for thinner glass substrate and at slower scribe velocity for thicker glass substrate. Owing to these relations, the crack depth also has almost the same tendency as σ_tmax.     

Basic investigation of noncontact transportation system for large TFT-LCD glass sheet used in CCD inspection section

Recently, thin film transistor liquid crystal displays (TFT-LCDs) have been successfully applied to desktop personal computer (PC) monitors and televisions. Higher resolution and larger mother glass sheets have been required for television displays in particular to reduce costs and improve production efficiencies. To handle the increasing resolution and mother glass size, high-speed inspection processes for detecting defects in TFT arrays using charge coupled device (CCD) cameras are becoming very important. Therefore, a noncontact transportation technique for the high-speed inspection section is necessary, to avoid damage to the glass sheet during the inspection process. In addition, high-speed CCD cameras with high resolution, large magnification and shallow focus depth are usually used in the inspection process. Accordingly, it was reported that fluctuations of less than 20 μm in the floating gap of the LCD glass sheet were required. We have used a 240 mm square LCD glass sheet as the first step of this study and an air-pad system using porous metal was investigated to support the glass sheet. The influence on the flatness of design parameters such as the nonuniformity of the permeability of the porous air pads and the appropriate combination of supply and exhaust pressures were investigated numerically for a glass sheet that was quiescently supported by the proposed air-pad system. Moreover, the numerical results are compared with experimental results to verify the validity of the numerical predictions. We found that the flatness of the glass sheet of less than 15 μm could be achieved experimentally with a floating gap of around 30 μm by using the proposed air-pad system.     

旋转电极电解电火花切割玻璃微结构试验研究

针对高深宽比非导电硬脆材料(如石英玻璃和陶瓷)微结构的加工需求,对微细电解电火花切割加工方法进行了深入研究。首先,提出了使用旋转螺旋微工具电极的电化学放电切割方法,并对切割缝宽模型进行了讨论;其次,对旋转螺旋电极电解电火花切割加工工艺进行了深入的试验研究,试验研究了加工电压、脉冲频率、占空比和主轴转速这些关键工艺参数对切割加工精度的影响。实验结果表明,缝宽随着施加电压和占空比的增加而增加,随着频率、主轴转速和进给速率的增加而减小。最后,通过优化后的参数成功加工出缝宽为135μm的微缝阵列、复杂的封闭微结构以及深宽比达6∶1的微图形结构。由此表明该方法是一种可有效加工高深宽比绝缘硬脆材料微结构的新工艺。     

玻璃管数控切割系统设计

介绍了玻璃管生产线中的玻璃管数控切割系统的结构及工作原理。数控系统的设计从控制刀盘旋转周期与拉管速度间的关系入手,实现保证玻璃管长度的目的。解决了玻璃管生产过程中,其切割过程无法适应拉管速度变化而引起玻璃管长度误差较大的问题。     

自动玻璃切割机排样优化算法设计与实现

介绍了在自动玻璃切割机中如何构建一种效率高、计算速度快和效果好的排样优化算法,使玻璃下料利用率得到较大幅度的提高.此外还对玻璃切割优化系统的基本原理进行了详细介绍,并给出了一个排样实例计算玻璃用量.     

Tungsten coating--a method of improving glass microtome knives for cutting ultrathin sections.

Glass knives for ultramicrotomy were considerably improved by coating the cutting edge with a film of evaporated tungsten metal. Knives treated by this method gave up to tem times as many acceptable sections as uncoated glass knives. They could also cut thinner sections and harder tissues than ordinary glass knives, and eliminated some of the cutting artefacts produced by them. No explanation for this improvement was found although several possibilities were examined.     

蓝宝石衬底片精密加工工艺研究

通过对蓝宝石衬底片精密加工的设备、工具、辅料、清洗等方面的研究,优化了衬底片加工工艺,提高了衬底片加工质量,且降低了加工成本.     

High-efficiency and precision cutting of glass by selective laser-assisted milling

As a hard and brittle material, glass is difficult to precisely cut with high efficiency. Although various attempts at ductile cutting of glass with high cutting depth have been reported, the low efficiency of the cutting process remains problematic. In order to achieve high-efficiency and precision cutting of glass, this paper proposes selective laser-assisted milling (SLAM). In this method, a fiber laser that has a wavelength out of the absorption band of glass is absorbed only into the small area where the black-body coating is put, and the selectively heated area is removed with a cutting tool. The experimental results of this study have demonstrated that SLAM reduces the arithmetic average of the roughness profile by 74% compared with conventional cutting. An observational analysis of the generated chips revealed that the application of SLAM changed the morphology of the chips from the crack type to the quasi-continuous type. These results demonstrate the feasibility of the high-efficiency and precision cutting of glass.     

玻璃基板无损剥离的建模与分析

化学机械抛光(CMP)是玻璃基板加工的一道重要工序,目前对玻璃基板的夹持方式普遍采用吸附垫进行吸附,抛光后需要将玻璃基板剥离(或称为卸片)。针对自动化剥离过程中玻璃基板容易碎裂造成经济效益损失,基于断裂力学理论,对玻璃基板的剥离过程进行了建模与分析,揭示了玻璃基板剥离与碎裂之间的竞争机制,并定义了竞争指数R来表征剥离与碎裂的竞争行为。为了量化竞争指数R,1)以宏观能量守恒为依据,设计并开展剥离实验,获得了玻璃基板与吸附垫界面的临界粘结断裂能;2)采用有限元软件ANSYS结合虚拟裂纹闭合技术(VCCT)仿真计算得到界面剥离能量释放率。应用竞争指数R,评估玻璃基板厚度与剥离速度对剥离与碎裂竞争行为的影响,确定了抛光工艺中常用的两种厚度的玻璃基板的临界剥离速度,最后开展玻璃基板的自动化剥离试验,试验结果表明本文提出的竞争机制及临界剥离速度的计算方法对玻璃基板无损剥离的自动化实现具有一定的指导意义。     

机载液晶显示器温度控制技术研究

针对机载TFT-LCD设计,论述温度控制技术所涉及的问题.在研究TFT-LCD特点的基础上,提出了加热电路的设计方法以确保机载TFT-LCD在低温环境下启动和工作;运用热设计的基本方法,提出了加固机载TFT-LCD高温工作的解决方案.对宽温工作的基本方法和自动控制系统给予了分析.     

Experimental investigation on the CO2 laser cutting of soda-lime glass

Journal of Mechanical Science and Technology - This study reports on complete glass cutting using a single CO2 laser beam with a low power of several tens of watts. In this study, the morphological...     

Effect of process parameters on the cutting quality in lasox cutting of mild steel

Samples of mild steel have been cut on a CO₂ laser machine using the principle of laser assisted oxygen cutting (LASOX). The combined effects of input process parameters (cutting speed, gas pressure, laser power and stand off distance) on cut quality (heat affected zone (HAZ) width, kerf width and surface roughness) have been studied. Regression analysis has been used to develop models that describe the effect of the independent process parameters on cut quality. Using the developed model, we attempted to optimize the input parameters that would improve the cut quality (minimization of HAZ width, kerf width and surface roughness), increase the productivity and minimize the total operation cost. We found from the study that the gas pressure and cutting speed had pronounced effect on cut quality. Low gas pressure produces lower HAZ width, lower kerf width and good surface finish whereas increase in speed results in higher HAZ width, lower kerf width and good surface finish.     

线切割加工工件表面质量的改善与提高

讲述了线切割加工工件时表面质量的人为因素的控制与改善。     

Bystronic激光切割机加工质量分析与控制

分析激光切割的加工原理，以及影响加工质量的诸多因素，阐述如何控制提高加工质量的方法。