Digital Twin Modeling and Simulation Optimization of Transmission Front and Middle Case Assembly Line

As the take-off of China’s macro economy,as well as the rapid development of infrastructure construction,real estate industry,and highway logistics transportation industry,the demand for heavy vehicles is increasing rapidly,the competition is becoming increasingly fierce,and the digital transformation of the production line is imminent.As one of themost important components of heavy vehicles,the transmission front andmiddle case assembly lines have a high degree of automation,which can be used as a pilot for the digital transformation of production.To ensure the visualization of digital twins(DT),consistent control logic,and real-time data interaction,this paper proposes an experimental digital twin modeling method for the transmission front and middle case assembly line.Firstly,theDT-based systemarchitecture is designed,and theDT model is created by constructing the visualization model,logic model,and data model of the assembly line.Then,a simulation experiment is carried out in a virtual space to analyze the existing problems in the current assembly line.Eventually,some improvement strategies are proposed and the effectiveness is verified by a new simulation experiment.

Advances in Compact Manufacturing for Shape and Performance Controllability of Large-scale Components-A Review

Research on compact manufacturing technology for shape and performance controllability of metallic components can reanze the simplification and high-reliability of manufacturing process on the premise of satisfying the requirement of macro/micro-structure. It is not only the key paths in improving performance, saving material and energy, and green manufacturing of components used in major equipments, but also the challenging subjects in frontiers of advanced plastic forming. To provide a novel horizon for the manufacturing in the critical components is significant. Focused on the high-performance large-scale components such as bearing rings, flanges, railway wheels, thick-walled pipes, etc, the conventional processes and their developing situations are summarized. The existing problems including multi-pass heating, wasting material and energy, high cost and high-emission are discussed, and the present study unable to meet the manufacturing in high-quality components is also pointed out. Thus, the new techniques related to casting-rolling compound precise forming of rings, compact manufacturing for duplex-metal composite rings, compact manufacturing for railway wheels, and casting-extruding continuous forming of thick-walled pipes are introduced in detail, respectively. The corresponding research contents, such as casting ring blank, hot ring rolling, near solid-state pressure forming, hot extruding, are elaborated. Some findings in through-thickness microstructure evolution and mechanical properties are also presented. The components produced by the new techniques are mainly characterized by fine and homogeneous grains. Moreover, the possible directions for fin＇ther development of those techniques are suggested. Finally, the key scientific problems are first proposed. All of these results and conclusions have reference value and guiding significance for the integrated control of shape and performance in advanced compact manufacturing.

A Novel Attribute-Based Encryption Approach with Integrity Verification for CAD Assembly Models

Cloud manufacturing is one of the three key technologies that enable intelligent manufacturing.This paper presents a novel attribute-based encryption(ABE)approach for computer-aided design(CAD)assembly models to effectively support hierarchical access control,integrity verification,and deformation protection for co-design scenarios in cloud manufacturing.An assembly hierarchy access tree(AHAT)is designed as the hierarchical access structure.Attribute-related ciphertext elements,which are contained in an assembly ciphertext(ACT)file,are adapted for content keys decryption instead of CAD component files.We modify the original Merkle tree(MT)and reconstruct an assembly MT.The proposed ABE framework has the ability to combine the deformation protection method with a content privacy of CAD models.The proposed encryption scheme is demonstrated to be secure under the standard assumption.Experimental simulation on typical CAD assembly models demonstrates that the proposed approach is feasible in applications.

3D Microdisplacement Monitoring of Large Aircraft Assembly with Automated In Situ Calibration

Three-dimensional(3D)microdisplacement monitoring plays a crucial role in the assembly of large aircraft.This paper presents a broadly applicable high-precision online 3D microdisplacement monitoring method and system based on proximity sensors as well as a corresponding in situ calibration method,which can be applied under various extreme working conditions encountered in the aircraft assembly process,such as compact and obstructed spaces.A 3D monitoring model is first established to achieve 3D microdisplacement monitoring based only on the one-dimensional distances measured by proximity sensors,which concerns the extrinsic sensor parameters,such as the probe base point(PBP)and the unit displacement vector(UDV).Then,a calibration method is employed to obtain these extrinsic parameters with high precision by combining spatial transformation principles and weighted optimization.Finally,calibration and monitoring experiments performed for a tailplane assembly process are reported.The calibration precision for the PBP is better than±10 lm in the X and Y directions and±2 lm in the Z direction,and the calibration precision for the UDV is better than 0.07°.Moreover,the accuracy of the 3D microdisplacement monitoring system can reach±15 lm.In general,this paper provides new insights into the modeling and calibration of 3D microdisplacement monitoring based on proximity sensors and a precise,efficient,and low-cost technical means for performing related measurements in compact spaces during the aircraft assembly process.

Decomposition Methods for Manufacturing System Scheduling:A Survey

Manufacturing is the application of labor, tools,machines, chemical and biological processing, to an original raw material by changing its physical and geometrical characteristics, in order to make finished products. Since the first industrial revolution, to accommodate the large-scale production,tremendous changes have happened to manufacturing through the innovations of technology, organization, management, transportation and communication. This work first reviews the highvolume low-mix process by focusing on the quantity production,transfer line and single model assembly line. Then, it reviews the high-volume high-mix process. For such a process type,mixed/multi model assembly line is usually adopted. Hence,two main decisions on them, i.e., balancing and, sequencing are reviewed. Thereafter, it discusses the low-volume high-mix process in detail. Then, technology gap and future work is discussed, and at last, conclusions are given.

CONCURRENT PRODUCT PORTFOLIO PLANNING AND MIXED PRODUCT ASSEMBLY LINE BALANCING

Reconfigurable products and manufacturing systems have enabled manufacturers to provide ＂cost effective＂ variety to the market. In spite of these new technologies, the expense of manufacturing makes it infeasible to supply all the possible variants to the market for some industries. Therefore, the determination of the right number of product variantsto offer in the product portfolios becomes an important consideration. The product portfolio planning problem had been independently well studied from marketing and engineering perspectives. However, advantages can be gained from using a concurrent marketing and engineering approach. Concurrent product development strategies specifically for reconfigurable products and manufacturing systems can allow manufacturers to select best product portfolios from marketing, product design and manufacturing perspectives. A methodology for the concurrent design of a product portfolio and assembly system is presented. The objective of the concurrent product portfolio planning and assembly system design problem is to obtain the product variants that will make up the product portfolio such that oversupply of optional modules is minimized and the assembly line efficiency is maximized. Explicit design of the assembly system is obtained during the solution of the problem. It is assumed that the demand for optional modules and the assembly times for these modules are known a priori. A genetic algorithm is used in the solution of the problem. The basic premise of this methodology is that the selected product portfolio has a significant impact on the solution of the assembly line balancing problem. An example is used to validate this hypothesis. The example is then further developed to demonstrate how the methodology can be used to obtain the optimal product portfolio. This approach is intended for use by manufacturers during the early design stages of product family design.

Multi-objectives and Simulation Models for Develop Production Line in Automobiles Manufacturing System

Automotive manufacturing is complex and includes the coordination of design in the manufacturing system. The manufacturing approaches over the past few years, disassembly have been a key issue, and it seems that simulation models are usually tailored to address a narrow set of industrial issues. This paper describes the development of the production line in the automobile manufacturing system through design, operation, and maintenance, based on multi-objectives of Algorithm and Simulation Model called MOA-SM. The both models are being developed at three different levels： the production line in the body and assembly shop, supply chain, and the production plan. The optimization tries to involve more objectives to solve the issues in manufacturing system. A solution that may optimize one performance measure may deteriorate since other performance solutions are difficult. The resulting algorithms are comparable to the simulation and multi-object in terms of success rate, assembly times, peak forces, moments, and have assembly times superior to those of a benchmark blind search algorithm.

Minimizing Products Rates Variation in Just-in-Time Mixed-Model Manufacturing

Mixed-Model assembly lines are often used in manufacturing based on just-in-time techniques. The effective utilization of these lines requires a schedule for assembling the different models be determined. The objective is to minimize the total deviation of actual production rates from the desired production rates. Mathematical method with the optimization algorithm is proposed here to solve this problem. To prove the efficiency of the proposed algorithm, a number of test problems are solved. The results show that the proposed algorithm is an efficient and effective algorithm which gives better results with the large problem sizes. This paper presents a practical procedure to minimize total product variation rates, and easy to use by practitioner.

Solving Level Scheduling in Mixed Model Assembly Line by Simulated Annealing Method

This paper presents an application of the simulated annealing algorithm to solve level schedules in mixed model assembly line. Solving production sequences with both number of setups and material usage rates to the minimum rate will optimize the level schedule. Miltenburg algorithm (1989) is first used to get seed sequence to optimize further. For this the utility time of the line and setup time requirement on each station is considered. This seed sequence is optimized by simulated annealing. This investigation helps to understand the importance of utility in the assembly line. Up to 15 product sequences are taken and constructed by using randomizing method and find the objective function value for this. For a sequence optimization, a meta-heuristic seems much more promising to guide the search into feasible regions of the solution space. Simulated annealing is a stochastic local search meta-heuristic, which bases the acceptance of a modified neighboring solution on a probabilistic scheme inspired by thermal processes for obtaining low-energy states in heat baths. Experimental results show that the simulated annealing approach is favorable and competitive compared to Miltenburg’s constructive algorithm for the problems set considered. It is proposed to found 16,985 solutions, the time taken for computation is 23.47 to 130.35, and the simulated annealing improves 49.33% than Miltenberg.

产品制造和装配过程认证DMAIC方法

本文以扶梯梯级链制造和装配过程为例,提出了一套基于DMAIC的系统化和结构化过程认证方法,以减少过程变异,确保过程受控和有足够能力。主要方法是先通过流程图、SIPOC、PFMEA等分析,识别关键产品特性(KPC);然后针对各个KPC进行MSA、控制图、过程能力分析,了解当前过程的能力水平;针对过程能力不达标的KPC,进行根源分析和改进,确保过程能力达到1.33以上;最后更新质量文件,制定过程控制和过程能力定期跟踪计划。

基于热泡喷墨技术制备均匀细胞球的创新方法

细胞球在药物发现、生理病理学研究和组织工程等多个领域发挥重要作用。然而,传统的制造细胞球的方法限制了其应用。本文提出了一种基于热泡喷墨打印技术的系统性方法,称为聚集打印,它可以快速、高通量且低成本地产出均匀尺寸的球体。聚集打印可以在16 min内产出864个直径均匀的细胞球。本文以CHO细胞作为研究对象,仔细分析了打印后的细胞活性。同时,为了提高细胞球体尺寸的均匀性,提出3种优化方法,分别可以将细胞球体直径的变异系数(CV值)降低17.04%~48.38%不等,最后研究了打印后的细胞球培养0、1、4、7 d的生长情况。实验结果充分证明了聚集打印方法在细胞球体制造方面的优势性,本方法也为类器官的制备提供参考。

基于价值流的棉纺车头机械装配精益优化

伴随着市场供需结构变化,离散型制造业迫切需要进行市场化改革。以T公司为例,运用精益生产理论,以VSM为工具对棉纺机车头机械装配进行分析发现:工序间排产不均衡、瓶颈工序换模周期长、现场精益化水平低以及加工工艺存在浪费等缺陷。基于此,利用看板拉动、SMED快速换模、ESCR法则以及工艺改进等IE技术进行优化并绘制价值流未来图。创新性地将精益生产理论引入棉纺车头机械装配,实现降本增效的目的,对离散型机械装配制造与优化具有一定的借鉴意义。

汽车前底盘装配视觉检测系统设计与应用

为解决汽车底盘混流装配错装、漏装和人工检测效率低的问题,设计了基于YOLOv3-Tiny的在线检测系统。该检测系统利用4套光源-相机组合的成像系统,从多角度获取前底盘模块的全貌图像,利用基于差分统计的条纹识别算法剔除低质量图像;根据检测目标特性,简化非极大值抑制算法,优化检测过程。实验和现场运行结果表明:检测系统目标无遮挡检出率达到100%,综合识别准确率达到99.95%,平均检测时间3.5 s,较之前人工检测效率提升94.55%,检测系统具有较高的准确度和检测效率,在汽车工业中实现了柔性化和智能化的目标检测应用。

The joint knowledge reasoning model based on knowledge representation learning for aviation assembly domain

Knowledge graph technology is widely applied in the domain of general knowledge reasoning with an excellent performance.For fine-grained professional fields,professional knowledge graphs can provide more accurate information in practical industrial scenarios.Based on an aviation assembly domain-specific knowledge graph,the article constructs a joint knowledge reasoning model,which combines a named entity recognition model and a subgraph embedding learning model.When performing knowledge reasoning tasks,the two models vectorize entities,relationships and entity attributes in the same space,so as to share parameters and optimize learning efficiency.The knowledge reasoning model,which provides intelligent question answering services,is able to reduce the assembly error rate and improve the assembly efficiency.The system can accurately solve general knowledge reasoning problems in the assembly process in actual industrial scenarios of general assembly and component assembly under interference-free conditions.Finally,this paper compares the proposed knowledge reasoning model based on knowledge representation learning and the question-answering system based on large-scale pre-trained models.In the application scenario of system functional testing in general assembly,the joint model attains an accuracy rate of 95%,outperforming GPT with 78%accuracy and enhanced representation through knowledge integration with 71%accuracy.

协作机器人在发动机装配线中的应用介绍

发动机装配线是自动化技术发展中典型的技术转换成果。随着制造业的不断发展,尤其发动机装配线对智能化以及柔性化提出了更高的要求。协作机器人则是智能制造发展趋势下诞生的新一代智能化机器人产品,更好的解决了人机协同作业的应用需求,大大提高了人机协同作业的安全性,极大提高了生产线的智能化、柔性化。于此同时,协作机器人体积小,占地少,也使得装配线更加高效的利用场地。文章分析了智能制造环境下发动机装配线的发展方向和协作机器人应用在发动机装配线的特点及优势,并详细介绍了某汽车发动机装配线的协作机器人应用案列,为汽车发动机装配线智能化建设提供参考。

熔体黏弹特性对模内微装配成型制造精度影响

针对微细万向球形转动运动副的功能自润滑液膜辅助模内微装配成型,明晰其微装配界面直径制造公差—黏弹性热流固耦合冲击载荷、连续相变演化区厚度、热黏弹塑性应力—熔体黏弹弹性的多场协同耦合演化规律,是实现精密调控其制造精度的关键技术问题。结果表明,微装配界面直径制造公差受控于二次注射成型充填熔体的黏弹特性,当参考黏度由2267 Pa·s增至15000 Pa·s时,微装配界面直径制造公差由11μm增至19μm,增幅为72.7%;而当松弛时间由0.05 s增至0.25 s,则由31μm减至19μm,减幅38.7%;为了满足行业规范的尺寸制造公差技术指标≤30μm的要求,不宜采用松弛时间小于0.05 s的高弹性熔体进行其功能自润滑液膜辅助模内微装配成型。

基于GP-PS的分布式加工与装配多级车间调度规则自动设计方法

分布式加工与装配多级制造系统由多个用于加工零件的作业车间和用于装配产品的一般流水车间组成。动态到达的订单涉及多层产品结构,零件需齐备之后才可装配。该类多级车间的管控涉及订单分配、加工和装配任务调度联合决策问题,其关键在于实现两级生产的精准化协同目的。针对分布式加工与装配多级车间调度问题,提出了一种基于GP-PS的分布式加工与装配多级车间调度规则自动设计方法。首先,以最小化订单拖期率为目标,建立了订单分配、加工和装配任务调度联合决策的数学模型;然后,提出了一种改进型遗传规划算法,用以集成进化多级调度规则,设计了一类种群优化机制来避免算法陷入局部收敛,同时嵌入了并行仿真技术,有效减少了训练时间;最后,进行了仿真实验,对改进型遗传算法的性能进行了验证。研究结果表明:人工规则组、标准遗传规划算法及改进型遗传算法得到的订单拖期率分别为6.44%、5.65%、2.67%。基于并行仿真优化的改进型GP算法较数十个优选的人工规则组及标准GP算法生成的最优规则组,能取得更明显的综合性能优势。使用该算法针对DPAMW调度问题自动设计一体化调度的多级规则是可行的、有效的。

新的直升机复合材料涵道制造技术

为了实现AC332民用直升机复合材料涵道结构的高质量、低成本、敏捷快速制造,针对结构特点和各项设计要求,开展正向工艺设计,提出一种新的直升机复合材料涵道制造技术。新的直升机复合材料涵道制造技术包括零件的精准制造技术、涵道结构胶接装配技术、精加工技术,对直升机复合材料涵道制造技术展开论述,介绍直升机复合材料涵道制造技术的应用情况;与传统直升机的涵道制造技术从产品质量、工装需求、操作性、制造成本方面进行对比。结果表明:新的直升机复合材料涵道制造技术达到了降低成本、缩短制造周期、简化工装、提升质量、保证接口精度的效果,对其他直升机大部件的精准制造具有参考价值。

集装箱船分段制造无修割装配数据关联分析与应用

以集装箱船分段制造修割数据为研究对象,进行数据采集和关联关系提取。精准发掘分段制造中的修割位置、修割数量、修割长度、修割原因、修割耗时和间接影响平台周期等关键数据的关联逻辑。根据数据的完备性、精准性和创造性,为集装箱船分段制造无修割装配精度控制提供可行的管理目标,并确定无修割装配技术优化方案,可增强集装箱船分段制造精度控制策划的综合水平。

模块化装配式钢结构在港口工程中应用要点浅析

以某海外工程实例为依托,简要介绍了项目背景条件,阐述了模块化装配式钢结构在港口工程项目中的应用。浅析了模块化装配式钢结构设计、加工制作、焊接工艺、防腐涂装、吊运安装过程中的关键点,详细介绍了模块化钢结构在应用关键点上需要注意的细节,对模块化装配式钢结构的应用做了总结与展望,可为后续类似的海工项目提供参考。