混流汽车总装配线上的零部件优化配送方案研究

配送车每次配送的利用率大小是提高配送效率的主要因素,因此设计一种启发式算法使配送车一次装载的标准塑料周转箱尽可能多,提高配送车空间利用率.最后的仿真实验验证了上述配送方法的实用性,提出的零部件配送管理方法,只需使用较少的配送工人,同时降低了线旁库存,能为企业节省人力,降低生产成本.     

发动机装配生产线平衡问题研究

装配线平衡问题是装配线规划中的重要组成部分,在工作站数量确定的前提下采用人工平衡法进行装配线的规划,得到多个方案,从中选择接近最佳的方案.以某发动机装配线为案例进行了分析,并使用eM-Plant软件对规划的装配线进行了仿真.     

工作研究在汽车仪表机芯装配线中的应用

运用工作研究中的程序分析、操作分析和动作分析方法,对某汽车仪表机芯装配线进行分析。在了解机芯装配工艺的基础上,运用秒表法测定装配线上各个工位的作业时间,找出瓶颈工位;运用5W1H提问技术、ECRS原则和动作经济原则对瓶颈工位进行改善,以提高装配线的生产效率;最后,通过对改善前后方案的对比,以证明改善效果。     

IE技术在发动机装配线作业改善中的应用

从作业时间测定和装配线平衡率的基本概念出发,引入利用动作分析研究提高装配线平衡率,文章以某发动机的装配线为例,首次运用多媒体技术并结合X-σ质量控制图测定装配线各工序的作业时间,并分析了该装配线平衡率,得出了发动机的活塞连杆总成是该装配线的瓶颈工序;其次利用达宝易软件对瓶颈工序活塞连杆总成进行动作分析与优化,使装配线平衡率提高了21个百分点,日产能从81台提高到114台,最后认识到IE技术对提高装配线平衡率方面作用显著。     

基于改进遗传算法的某发动机厂装配线平衡研究

以一条发动机装配线为研究对象,对工序作业元素进行重新划分,建立作业元素优先关系。以装配线的生产均衡指数为目标函数,通过改进遗传算法实现对研究对象的优化方案设计。运用Matlab实现算法获得了最优装配顺序及各工位作业分配结果,使生产线获得更好的平衡状态,从而提高生产效率。     

汽车发动机装配线控制系统研究及应用

介绍了汽车发动机装配线的自动控制系统,简述了分布式I/O在控制系统中发挥的作用,以及系统的网络配置和硬件组成.     

装配输送线的转向装置

产品在装配生产线上被输送的过程中 ,往往需要几次转向 ,有时是因为进入下一工序 ,产品需要掉转方向 ;有时是因为前面某一工序加工不合格 ,需要中途横向下线检修 ;也有时只是用转向装置取代输送线上的过渡弯道。本文介绍 2种在空调器装配线上使用的转向装置。1　升降式转向装置1 1　工作原理转向装置结构及工作原理如图 1所示。它有可以翻转升降的双臂 1,臂上装有输送链 4。不需转向时 ,双臂横于输送线 2之下 ,略低于输送线水平面 ,不妨碍输送线 2上的空调器传送。当有空调器需要转向传送时 ,由气缸活塞杆 (图中未画 )将双臂顶起 ,绕轴 7翻…     

基于RFID技术的动力总成装配线控制系统的设计

为满足动力总成装配线柔性化多机型混线连续生产要求,安徽华菱汽车公司开发和设计了一种基于RFID(Radio Frequency Identification)技术的智能型动力总成柔性装配线的新型自动化控制系统。该系统由RFID、PLC、扫描系统、HMI等组成,通过环网架构形式进行数据传输,实现实时下达生产订单和BOM的功能,满足了生产线多机型连续混线生产的控制要求。     

汽车发动机装配线监控系统的设计与实现

该系统以OPC技术为基础,通过PC与PLC的通讯,实现了对发动机总装线各个工位加工状态的实时监控,显示现场电控设备出现的各种故障及报警,使整个装配线的状态可控,并对发动机装配过程中的数据进行采集,保存到SQL Server数据库中,为数据的后续SPC分析提供依据.设计了上传数据到服务器模块,处理了生产线上的突发事件对生产数据的影响,描述了系统和数据库的详细设计.运行结果表明该系统性能稳定,满足生产需要.     

摩托车发动机装配线在制品控制建模与仿真

针对某摩托车企业新建发动机装配线在制品控制初始方案的不合理问题,提出相应的改进方案,并运用Witness仿真软件建立在制品控制的仿真模型进行了验证.从装配线生产效率和物料缺货率方面进行分析研究,确定了一种最优解决方案,改进了在制品控制的规则.该方案不仅提高了装配线生产物流系统的效率,还降低了生产物流的成本.     

某发动机总装线看板生产系统建模与仿真

针对某发动机车间总装线传统生产系统生产效率低下等问题,研究了该生产线在精益生产模式下看板系统的建模与仿真技术。建立了生产看板系统的Petri网模型,并转换为与其等价的Markov过程,得出绩效指标计算公式。利用工业物流仿真软件Witness进行仿真求解,得出该车间实施看板生产系统后设备利用率提高、在制品库存减少、系统生产率增加和订单平均等待时间减少的结论。进一步分析了安全系数和变异系数变化时对看板生产系统绩效指标的影响,从而掌握看板策略对不同环境的适应性。     

涡轮增压器装配线绩效评估研究

随着全球经济的快速发展,企业需要引入工业工程等先进理论和方法,对生产流水线进行评估与改善。以某厂涡轮增压器装配生产线为例,运用德尔非理论及层次分析方法,根据专家、熟练操作工人问卷调查结果,确定装配线评估因子及其权重,建立了各评估因子的量纲函数,并通过实验得到函数中参数值,从而形成装配线绩效评估模型。最后应用该模型对某厂涡轮增压器装配生产线进行实地评估,得到了评估结果,为该厂改进生产线提供参考。     

大型商用航空发动机科研装配线三维虚拟设计

为解决航空发动机科研装配线二维工艺布置设计存在的局限性,首先通过对大型商用航空发动机科研装配线的实体工艺要素三维建模,基于虚拟现实Unity3D开发平台,对已有二维工艺布置方案进行三维虚拟设计,实现了工艺要素的补充、细化和优化. 然后对新型的总装工艺过程进行了运动学仿真,并开发了人机交互的实时动态漫游程序. 研究成果为后期车间改造、工艺布置调整提供了预演和模拟分析平台,为企业的人员培训和宣传展示提供了重要素材,也为相关的制造厂房或制造单元设计提供了技术参考和借鉴.     

The nanostructure of soot-in-oil particles and agglomerates from an automotive diesel engine

The characteristics of soot particles and agglomerates of particles extracted from samples of lubricating oil drawn from the sump of a diesel engine have been investigated. The engine was a high pressure common rail, direct injection diesel designed for light duty automotive applications. Soot from the samples was prepared for imaging by sample dilution with heptane, followed by washing in diethyl ether and in some cases, sample centrifugation. The size and shape of agglomerates were defined from measurements of projected length and width allowing for chain contortion. When used, centrifugation is shown to alter the size and shape of agglomerates, increasing the proportion of chain agglomerates and reducing clusters. Without centrifugation, roughly half of the soot in oil exists in long-chain agglomerates with average length of 130 nm and 50 nm in width. Clusters with modest branching account for the remaining 46%. The average aspect ratio (L/W) was of 2.9. The diameter of spherical primary particles that form the agglomerates ranges between 10 and 35 nm grouped in a Gaussian distribution with a mean value of 20.2 nm. All primary particles exhibit an inner core and an outer shell. The inner core is composed by several nuclei of around 4 nm diameter. Inner core is of around 8–15 nm in diameter and outer shell 4–12 nm thick.     

Two-sided assembly line balancing using an ant-colony-based heuristic

Two-sided assembly line balancing (ALB) problems usually occur in plants which are producing large-sized high-volume products, such as buses, trucks, and domestic products. Many algorithms and heuristics have been proposed to balance the well known classical one-sided assembly lines. However, little attention has been paid to solve two-sided ALB problems. Moreover, according to our best knowledge, there is no published work in the literature on two-sided ALB problems with zoning constraints (2sALBz). In this study, an ant-colony-based heuristic algorithm is proposed for solving 2sALBz problems. This paper also makes one of the first attempts to show how an ant colony heuristic (ACH) can be applied to solve 2sALBz problems. In the paper, example applications are presented and computational experiments are performed to present the suitability of the ACH to solve 2sALBz problems. Promising results are obtained from the solution of several test problems.     

Redesigning an assembly line through lean manufacturing tools

The implementation of a lean manufacturing strategy represents a robust contribution to the phase sequence that leads to operational excellence and the continuous improvement through the elimination of nonvalue-added activities. Therefore, lean practices contribute substantially to plant operational performance. This paper studies the use of value stream mapping (VSM) as a tool in lean manufacturing implementation and a framework of improvement activities, in particular for an efficient introduction of kanban and milkrun techniques. A case study illustrates VSM use, as well as kanban and milkrun systems application on an assembly line. Finally, the results obtained show the path of improvement, measured through the lean rate (LR) and dock-to-dock time (DtD).     

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines.The linear lumped mass method,which has been universally applied to the dynamic modeling of engine crankshaft assembly,reveals obvious simulation errors.The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness.In this paper,a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method.The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments.The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method.The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method.The simulation results are compared with a lumped mass model and a detailed model using the system matrix method.Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration,and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor.The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia.This research project is aimed at improving nonlinear dynamics theory,and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.     

某发动机转子机油泵总成噪声优化研究

为解决某发动机工作转速范围内所出现的啸叫声问题,对转子机油泵总成噪声进行优化研究。通过分析转子机油泵噪声机理,结合发动机台架试验得到的噪声频谱,分析噪声特征与来源;以降低噪声为优化目标,针对突出的声学缺陷对转子机油泵总成的结构进行优化设计。结果表明,采用优化方案后,该机油泵一阶振动速度降低,且困油区压力最大值平均降低约56%,阶次噪声明显改善,背景宽频能量有所降低,噪声的总声压级降低了2.8 dB。优化方案有效改善了该机油泵总成声学特性,为同类结构声学优化提供了思路。     

Development of automotive engine cradle by hydroforming process

The hydroforming technology may bring many advantages to automotive applications in terms of better structural integrity of the parts, lower cost from fewer part count, material saving, weight reduction, lower springback, improved strength and durability and design flexibility. In this study, the whole process of front sub-frame parts development by tube hydroforming using steel material having tensile strength of 440 MPa grade is presented. At the part design stage, it requires feasibility study and process design aided by CAE (Computer Aided Design) to confirm hydroformability in details. Effects of parameters such as internal pressure, axial feeding and geometry shape in automotive engine cradle by the hydroforming process were carefully investigated. Overall possibility of hydroformable engine cradle parts could be examined by cross sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending, preforming and hydroforming. At the die design stage, all the components of prototyping tool are designed and interference with the press is examined from the point of deformed geometry and local thinning.