Integration of reconfigurable inspection with stream of variations methodology

This paper describes an advanced closed loop quality control methodology for reconfigurable manufacturing systems. The methodology enables rapid root-cause diagnostics for faster ramp-up of reconfigurable systems through integration of the Reconfigurable Inspection Machine (RIM) and the Stream of Variations (SoV) methodology. The RIM enables reconfigurable, rapid, and accurate inspection using non-contact sensors while the SoV methodology is used to quickly analyze the measurements and identify the root-cause of the errors produced during machining.The feasibility of the industrial concept was experimentally validated. A machining error was introduced during machining of an engine head. Measurement information collected by the RIM was processed and used to locate the root-cause of the error using the SoV methodology.     

基于知识工程的工艺决策方法研究

为了解决集成环境下的复杂零件的工艺决策问题,从问题描述、规则定义和过程控制三个方面出发,提出了以"对象-规则-过程"为核心的知识工程应用方法.分析了包括产品特征信息、工艺过程信息、资源能力信息和加工方法知识信息在内的工艺决策对象信息,提出基于本体和元模型的建模框架.研究了基于规则引擎的工艺决策规则的表达和应用的方法.在分析工艺决策的过程化特点的基础上,结合工作流思想,提出工艺决策的过程化组织模式.开发了工艺设计原型系统,支持工艺决策方法的实施及应用.     

利用消失模铸造技术生产缸体、缸盖的优势

介绍了消失模铸造的近无馀量、精确成形、清洁生产、结构设计灵活等工艺特点,列举了四缸缸盖、四缸缸体以及六缸半片泡沫模样的分片设计,指出了消失模铸造过程的注意事项,最后介绍了消失模铸造发动机缸体、缸盖的趋势,说明了运用消失模铸造工艺生产发动机缸体、缸盖不仅具有成本的优势,还可进一步促进汽车工业的发展.     

发动机进排气导管座圈锪铰专用机床设计

针对企业摩托车发动机缸体现有工艺存在加工精度、合格率低及生产效率跟不上市场需求的问题,在分析现有加工手段优劣的基础上,利用工序集中原则,将缸体进排气座圈孔、导管孔及平面的精加工集中于一台设备上进行加工,提出了两次装夹、多工件、多工位、多刀具复合加工的全新工艺方案。根据工件加工姿态确定了双工位、双夹具,每个夹具装夹两个工件的整体布局方案,工位一、二相互协作完成缸体工序加工内容;最后,根据整体方案对专用夹具、专用刀具及专用主轴箱等关键零部件进行了详细设计及阐述。     

CY4D柴油机缸体、缸盖铸造工艺及缺陷对策

介绍CY4D系列柴油机缸体的铸造工艺特点，试制过程中出现的包括缸盖渗漏、缸体加工尺寸偏差和缸体缸孔穿芯等质量问题，以及相应的解决措施。     

Analysis–synthesis of dimensional deviation of the machining feature for discrete-part manufacturing processes

Dimensional deviation analysis has been an active and important research topic in mechanical design, manufacturing processes, and manufacturing systems. This paper proposes a comprehensive dimensional deviation evaluation framework for discrete-part manufacturing processes (DMP). A generic, explicit, and transmission model is developed to describe the dimensional deviation accumulation of machining processes by means of kinematic analysis of relationships between fixture error, datum error, machine tool geometric error, fixturing force inducing error and the dimensional quality of the product. The developed modeling technology can deal with general fixture configurations. In addition, the local contact deformations of the workpiece–fixture system are determined by solving a nonlinear programming problem of minimizing the total complementary energy of the frictional workpiece–fixture subsystem in machining system. Moreover, the deviation of an arbitrary point on machining feature can be also evaluated based on a point deviation model with prediction dimension deviation from the transmission model. The dimensional error transmission within the machining process is quantitatively described in this model. A systematic procedure to construct the model is presented and validated. This model can be also applied to process design evaluation for complicated machining processes.     

Quality-driven Sequence Planning and Line Configuration Selection for Compliant Structure Assemblies

Assembly sequence planning is an integral part of a new product and process development. However, currently there are very few available approaches to evaluate the impact of assembly sequences on product quality. This paper develops a methodology for Quality-driven Sequence Planning (Q/SP) with consideration to product dimensional quality based on the following three steps: (1) Sequence generation for predetermined line configurations using /(-piece mixed-graph representation of assembly; (2) Dimensional quality model of variation propagation for assembly processes with compliant parts; and (3) Evaluation of sequences based on the multivariate process capability index. The methodology is illustrated using an industrial case study.     

铝缸盖重力铸造

叙述了铝合金缸盖常用的金属型重力铸造技术。对不同的熔化设备、制芯工艺、浇注工艺及设备、清理及粗加工等方面进行了比较，并与国外著名的铝铸造厂进行工艺对比，并展望了２１世纪铝缸盖的铸造技术。     

A Bayesian network approach to root cause diagnosis of process variations

This paper addresses the challenges inherent in root cause diagnosis of process variations in a production machining environment. We develop and present a process monitoring and diagnosis approach based on a Bayesian belief network for incorporating multiple process metrics from multiple sensor sources in sequential machining operations to identify the root cause of process variations and provide a probabilistic confidence level of the diagnosis. The vast majority of previous work in machining process monitoring has focused on single-operation tool wear monitoring. The focus of the present work is to develop a methodology for diagnosing the root cause of process variations that are often confounded in process monitoring systems, namely workpiece hardness, stock size, and tool wear variations. To achieve this goal, multiple sensor metrics have been identified with statistical correlations to the process faults of interest. Data from multiple sensors on sequential machining operations are then combined through a causal belief network framework to provide a probabilistic diagnosis of the root cause of the process variation.     

Parametric process optimization to improve the accuracy of rapid prototyped stereolithography parts

The functional requirements of a rapid prototyping system are speed and accuracy, and they are both functions of vendor defaulted and user selected manufacturing parameters. Accuracy is evaluated by dimensional errors, form errors and surface roughness of manufactured parts. A specially designed specimen with 20 dimensional, geometrical, and surface roughness features has been used in the inspection of RP manufacturing processes. In terms of Taguchi experimental design techniques, an orthogonal array of experiments has been developed which has the least number of experimental runs and desired process parameter settings. Using a 3-D coordinate measuring machine and surface profilometer, a series of measurements in evaluating the SLA parts quality has been conducted to find the functional relationships between the output part quality and input manufacturing process parameters. Two analysis tools, response surface methodology and Analysis of Variance (ANOVA), have been used to evaluate the SLA RP process and to perform the product optimization. The optimal setups of SLA manufacturing parameters for both individual features and a general part with various features have been concluded from this study.     

用系列法编制焊管轧辊重修工艺

分系列修复的原则一般用于汽车行业中的发动机缸体维修。将它应用于焊管轧辊修复,可以简化工艺,减少修复切削量,提高工效。     

Comparison of RSM with ANN in predicting tensile strength of friction stir welded AA7039 aluminium alloy joints

Friction stir welding(FSW) is an innovative solid state joining technique and has been employed in aerospace, rail, automotive and marine industries for joining aluminium, magnesium, zinc and copper alloys. The FSW process parameters such as tool rotational speed, welding speed, axial force, play a major role in deciding the weld quality. Two methods, response surface methodology and artificial neural network were used to predict the tensile strength of friction stir welded AA7039 aluminium alloy. The experiments were conducted based on three factors, three-level, and central composite face centered design with full replications technique, and mathematical model was developed. Sensitivity analysis was carried out to identify critical parameters. The results obtained through response surface methodology were compared with those through artificial neural networks.     

Modeling of process forces with consideration of tool wear for machining of sintered steel alloy for application to valve seat in a combustion engine

The reliable and precise machining of cylinder head components in the combustion engine represents a crucial and complicated step in the production process. In industrial manufacturing processes, disturbances are inevitable and provide a measure of uncertainty in each production step. Increasingly, the influence of such uncertainties is being evaluated using simulation models. To determine the performance quality of the model, a suitable cutting material and the edge geometry must be identified. In this paper, experimental investigation of polycrystalline cubic boron nitride grades for machining valve seats made of powder metallurgy steel in a combustion engine is presented. Then, a mechanistic approach is used to establish a prediction model of the process forces based on the experimentally determined data set.     

封头冲管嘴后冷加工余量借偏方案

介绍封头冲管嘴后的冷加工过程。通过实例对该产品进行分析说明,最后总结出该类封头在实际加工中定心和余量借偏的处理方案。着重阐述用平面向量法解决冲管嘴后管嘴余量借偏问题。     

Effectiveness of continuous workpiece speed variation (CWSV) for chatter avoidance in throughfeed centerless grinding

The continuous rotation speed variation is demonstrated to be an efficient method to avoid regenerative chatter in different machining processes. This paper presents a time-domain dynamic model for throughfeed centerless grinding process that can predict chatter by means of part roundness error evolution. Continuous workpiece speed variation (CWSV) has been implemented in this model to analyze the influence of this disturbing method on the dynamic instability. Experimental results have validated the model and verified the effectiveness of CWSV for chatter avoidance and surface finish and dimensional tolerances improvement. It has been demonstrated that the selection of the optimal variation parameters is an important factor not only for chatter avoidance, but also for the stability of surface finish and dimensional tolerances since workpiece speed variation has a direct influence on throughfeed rate and grinding forces.     

铝合金汽车缸盖低压铸造内浇道设计

基于低压铸造的基础理论,在总结低压铸造浇注系统的设计计算方法基础上,推导出了带砂芯的汽车缸盖金属型低压铸造内浇道截面积的计算方法.并通过AnyCasting软件对利用该计算方法设计的汽车缸盖低压铸造内浇道进行数值模拟,验证了该计算方法的实用性和正确性.     

复杂曲面覆盖件模具CAM技术研究

本文基于UG软件提出了一种复杂曲面覆盖件模具的分区加工方法，并以汽车前盖内板的凸模加工为例，详细介绍了基于该法的模具CAM过程。     

Robust technology chain design: considering undesired interactions within the technology chain

Existing methodologies in technology chain design are used to plan the deployment of manufacturing technologies under consideration of interactions between these technologies and workpiece properties. Present methodologies focus on workpiece characteristics which the technologies are designated to change. However, workpiece properties can also be negatively affected because of interactions between the manufacturing technologies and features which the technologies are not supposed to change. These undesired interactions can cause a lower quality of the produced parts and an increased amount of defective parts. In this paper, a new methodology is presented which enables the user to identify undesired interactions during the technology chain design process. Firstly, the product to be manufactured is analyzed and described as a set of individual features. Secondly, feature-specific technology chains are designed under consideration of possible undesired interactions. Thirdly, the individual feature-specific technology chains are merged to generate a robust technology chain for the manufacturing of the analyzed product. Since undesired interactions usually occur during production ramp-ups for the first time, the methodology is applied to a case study concerning a ramp-up in the automotive industry. In this context, improving the process stability by preventing the occurrence of undesired interactions is of high economic importance.     

Active integration of tool deflection effects in end milling. Part 1. Prediction of milled surfaces

Tools deflection that occurs during machining, and especially when flexible tools such as end mills are used, can result in dimensional errors on workpieces. The study presented here is part one of a two-part paper: it deals with the estimation of cutting forces and the prediction of milled surface. The second part will focus on a methodology that allows to optimize the production rate by compensating the deflection and meeting the part tolerance.Cutting force models have been and are still the subject of a lot of research. The model used is based on Kline and Devor's [5]: a polynomial approximation whose coefficients are obtained by least square methodology is used for the calculation of cutting forces. The machined surface (two axis machining) is determined using the contact point methodology and some experimental tests are done to validate the models.