A SKILL-FORMATION MODEL FOR GRINDING OPERATIONS

A good part of grinding operations is still dependent on skilled operators. Against such a background, this study takes up cylindrical plunge grinding, and presents a skill-formation model based on the learning process similar to that in which a grinding operator acquires skills through trial and error. The model repeats learning by giving only the total grinding stock and initial infeed rate, changing infeed rate, and evaluating the size and the removal rate in the process end. The simulation result has proved that the model shows a skill-formation process similar to that of an operator and generates desirable infeed processes.     

外圆切入磨削加工精度的研究

在考虑砂轮磨损和磨削能力变化的情况下,建立了磨削过程中工艺系统弹性变形微分方程式。分析了磨削过程中基本尺寸参数及工件原始形状误差的变化规律。并对磨削过程基本尺寸参数的变化及工件原始形状误差的纠正进行了试验研究。同时,带考察了切入进给速度对工件残余形状误差的影响。     

快速点磨削周边磨削层模型及参数

为深入研究快速点磨削机理及工艺,根据快速点磨削的技术与几何学特征,建立点磨削周边接触层及参数的数学模型,对砂轮和工件的等效速度和直径、磨削参数进行理论分析。在已建立快速点磨削接触层及参数的理论模型基础上,推证计及点磨削变量角度和磨削深度的砂轮周边理论接触宽度的计算公式,并对超薄快速点磨 削砂轮周边理论接触宽度和表面粗糙度进行数值仿真。结果表明：与普通外圆磨削不同,砂轮周边与工件实际接触宽度并不恒等于砂轮宽度,点磨削变量角度和磨削深度显著影响砂轮周边的实际接触宽度与工件表面粗糙度 数值。     

FORCE ANALYSIS FOR GRINDING WITH SEGMENTAL WHEELS

This paper describes a force model for grinding with segmental wheels. Both experimental and analytical results show that average grinding force decreases and peak force increases using segmental wheels as compared to conventional wheels. Larger spaces between segments further reduce the average force and increase the peak force. The reduction in average force is due to the size effect whereby the specific energy decreases at higher instantaneous material removal rates. An investigation of surface roughness and wheel wear reveals that modest amounts of segmentation reduce average force without increasing surface roughness or wheel wear.     

FORCE ANALYSIS FOR GRINDING WITH SEGMENTAL WHEELS

This paper describes a force model for grinding with segmental wheels. Both experimental and analytical results show that average grinding force decreases and peak force increases using segmental wheels as compared to conventional wheels. Larger spaces between segments further reduce the average force and increase the peak force. The reduction in average force is due to the size effect whereby the specific energy decreases at higher instantaneous material removal rates. An investigation of surface roughness and wheel wear reveals that modest amounts of segmentation reduce average force without increasing surface roughness or wheel wear.     

超硬磨粒CBN砂轮的磨削性能

本研究的目的是评价三种砂轮在磨削高速工具钢时的磨削性能。采用ABWOOD平面磨床,在不同磨削条件下对材料去除率,比磨削能和磨削表面的热损伤进行了实验研究,同时借助专用装置采集了磨削过程中砂轮的动态磨损数据。研究结果表明,超硬磨粒CBN砂轮磨削M2高速钢时磨性能最佳,这种砂轮在硬铁族金属加工领域具有良好的应用前景。     

A NEW TECHNOLOGY ON ENHANCING HEAT TRANSFER AT GRINDING ZONE THROUGH JET IMPINGEMENT DURING CREEP FEED GRINDING

This paper presents a jet-impingement technology to enhance heat transfer at the grinding zone. The jet-impingement technology uses a new apparatus developed to spray grinding fluid onto the workpiece surface at the grinding zone from the radial holes of an electroplated CBN wheel. Because the fluid is sprayed normally on the workpiece surface at the grinding zone, the heat transfer to the fluid is significantly improved as compared to the conventional fluid delivery methods. Experimental results, obtained under both imitated grinding tests and actual creep-feed grinding of titanium alloys, show that the jet-impingement technology lowers grinding temperature significantly. Much higher material removal rates are possible with jet-impingement without workpiece burn.     

Automated operation sequencing in intelligent process planning: A case-based reasoning approach

This paper addresses the methodology development for achieving one of the important functions in automated process planning: automated determination of sequence of machining operations for prismatic parts containing various types of form features. A framework of using the case-based reasoning approach to support learning capability in operation sequencing is first proposed. The methodology to accomplish various issues in case-based operation sequencing is then discussed. In particular, the following issues are considered: 1. Representation of operation sequencing cases. 2. Indexing and retrieval of operation sequencing cases. 3. Adaptation of operation sequencing cases. Finally, the implementation issues are addressed and the learning functions of the intelligent operation sequencing system are demonstrated.     

基于优先工序序列实例的CAPP策略研究

为了提高工艺规范性与标准化，实现计算机辅助快速工艺设计，提出了一种基于优先工序序列实例的CAPP策略。介绍了此方法的基本思想，应用面向对象技术建立零件和工艺信息的表达模型，同时研究了工序的编码方式，在此基础上详细讨论了基于优先工序序列实例的CAPP系统的决策方法。此策略既可根据典型工艺路线为新零件的工艺路线提供整体参考，又能应用优先工序序列段对工艺路线进行局部优化。     

企业集成的三层模型

本文介绍了企业集成的三层模型，即宏观集成层，中观集成层和微观集成层。宏观集成是以金融为中心的一群企业的集成；中观集成是以产品为中心的一群企业的集成；而微观集成则是以企业的内部行为为中心的单个企业内各个部分间的集成。文中分别对这三层集成的概念，结构和方法学需求框架进行阐述，给出国外的典型实例，并对中国的企业集成问题提出了建议。     

粘接点焊单搭接头的静力分析

建立了粘焊单搭接头的力学分析模型，得到了粘焊结构中粘接剂层内的剪应力和剥出应力分布，并由此确定了粘接层的人效判据。同时，对粘焊结构进行了数值分析，所得到的粘接剂层内的应力分布与理论值吻俣得较好，从而证实了所建理论模型的合理性。     

质量功能配置的多目标规划模型

提出了一个质量功能配置的多目标规划模型，它能够辅助产品开发人员作出有效的决策，使所设计的产品在有限的资源约束下能最大限度地满足顾客需求。该模型充分利用了质量屋中各个组成部分的信息，能够权衡、优化质量屋中存在的各种矛盾和冲突。实例研究表明，该模型是可行的和有效的     

拉伸筋阻力的一种简便解析模型

采用平面应变假设,通过对板料在拉伸筋处变形过程的分析,并考虑了材料的各向异性、应变速率敏感与包辛格效应,推导出一种计算拉伸筋阻力的简便计算解析模型。将计算结果与有关试验结果进行了对比,证明了该计算方法的有效性。     

A GRINDING-BASED MANUFACTURING METHOD FOR SILICON WAFERS: DECOMPOSITION ANALYSIS OF WAFER SURFACES

It is difficult for the lapping-based manufacturing method currently used to manufacture the majority of silicon wafers to meet the ever-increasing demand for flatter wafers at lower costs. A grinding-based manufacturing method for silicon wafers has been investigated. It has been demonstrated that the site flatness on the ground wafers (except for a few sites at the wafer center) could meet the stringent specifications for future silicon wafers. The generation mechanisms of the dimples and bumps in the central areas on ground wafers have also been studied. This paper reports another study on the grinding-based method, aiming to reduce the cost of chemical-mechanical polishing - the final material removal process in manufacturing of silicon wafers. Using design of experiments, investigations were carried out to understand the influences of grinding process variables on the peak-to-valley values of the polished wafer surfaces. It was found that the peak-to-valley values over the entire wafer surfaces did not show any relationship with grinding process variables. However, after analyzing the surface profiles by decomposing them into different frequencies, it was observed that there is a correlation between grinding process variables and certain surface feature components. Based on this finding, it is recommended to optimize the grinding process variables by minimizing the peak-to-valley values for each surface feature component, one at a time. This methodology has not been published for wafer grinding and is of practical use to the wafer industry.     

可修复系统的局部故障变化率与劣化模型

提出可修复系统局部故障变化新概念,运用数理统计方法,建立了可修复系统的劣化度最新模型。最后介绍了新模型的应用实例。     

A THRESHOLD MODEL FOR LASER CLEANING OF LARGER SILICON WAFERS

High cleaning quality for silicon wafers without damage is a challenge in laser cleaning technologies. Laser cleaning of Al₂O₃ micro-particles, which are the main contaminants of silicon wafer lapping and polishing solutions used in industry, from silicon wafers was studied for determining laser energy for high efficient particle removal while not causing damage to the wafers. As the cleaning force is generated from laser-energy absorption and conduction of the wafer, heat-conduction model on silicon wafer was developed during laser irradiation using a finer finite element method, from which cleaning force exerting on the particles greater than the adhesion force between the particle and the substrate, but less than the wafer damage energy of laser input was determined. Calculations of the laser energy threshold values for both particle cleaning and wafer damage were conducted for silicon wafers of 200 mm in diameter and 0.2 mm in thickness, and they were found to be about 60 mJ/cm² and 320 mJ/cm², respectively. The laser energy threshold model was finally verified experimentally using a KrF Excimer laser and found to be in good agreement with the experimental data. With the cleaning parameters from the model, the cleaning efficiency of as high as 98% has been achieved.     

A SIMPLIFIED CUTTING FORCE MODEL FOR LIGHT-CUT BALL-END MILLING APPLICATIONS

In light-cut milling operations, specific correlations have been identified empirically between the maximum cutting force on a cutter and its associated cutting parameters, and a series of ball-end milling tests for P20 tool steel has been conducted to establish the nature of these correlations. The experimental results indicate that the maximum cutting force on a cutter can be expressed as a logarithmic function of the associated cutting parameters. This paper describes the structure and testing of a simplified cutting force model for planar milling based on these results.     

一种轧机动力分析有限元模型

提出一种四辊轧机动态性能分析的平面有限元模型,该模型由梁单元、杆单元、刚度单元和质量单元等组成。根据该理论,可计算得到轧机容易激发的固有频率。用试验检验了所提模型的正确性。     

A GRINDING-BASED MANUFACTURING METHOD FOR SILICON WAFERS: DECOMPOSITION ANALYSIS OF WAFER SURFACES

It is difficult for the lapping-based manufacturing method currently used to manufacture the majority of silicon wafers to meet the ever-increasing demand for flatter wafers at lower costs. A grinding-based manufacturing method for silicon wafers has been investigated. It has been demonstrated that the site flatness on the ground wafers (except for a few sites at the wafer center) could meet the stringent specifications for future silicon wafers. The generation mechanisms of the dimples and bumps in the central areas on ground wafers have also been studied. This paper reports another study on the grinding-based method, aiming to reduce the cost of chemical-mechanical polishing – the final material removal process in manufacturing of silicon wafers. Using design of experiments, investigations were carried out to understand the influences of grinding process variables on the peak-to-valley values of the polished wafer surfaces. It was found that the peak-to-valley values over the entire wafer surfaces did not show any relationship with grinding process variables. However, after analyzing the surface profiles by decomposing them into different frequencies, it was observed that there is a correlation between grinding process variables and certain surface feature components. Based on this finding, it is recommended to optimize the grinding process variables by minimizing the peak-to-valley values for each surface feature component, one at a time. This methodology has not been published for wafer grinding and is of practical use to the wafer industry.     

A DECISIONAL MODEL FOR ESTIMATING RELIABILITY CURVE AND MAINTENANCE INTERVALS OF INSTRUMENTATION

Instrumentation is calibrated at appropriate intervals according to specific maintenance schedules. Metrologists have to deal with this important issue. In this report, a decision-based approach is proposed to improve the choice of calibration intervals. The reliability curve of the tested instrument is estimated to maintain control of its performance. Consequently, the next calibration is scheduled in order to guarantee reliability. The reported model provides metrologists with a procedure to establish optimal maintenance intervals in compliance with current standards. The model is based on general hypotheses, and therefore it is applicable for maintenance of any measurement system.