Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Design a Special Fixture for Tractor Lever

Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology of the lever workpiece,and the workpiece is accurately positioned and tightened under the action of the special fixture.Efficient machining of the workpiece can be achieved by using a drill template.The fixture not only has the advantages of high production efficiency,low cost and high life,but also effectively improves the processing technology of the workpiece,and has certain reference value for the subsequent fixture improvement design.

Flexible Fixture Design for the Top and End Surface Processing of NP2_NP4 Cylinder Heads

This paper focuses on the design of fixtures for NP2 and NP4 cylinder heads on a horizontal machining center of flexible machining automatic lines.It began with an analysis of the diagrams of part processing and working procedure which formed the basis for the design of the processing technology scheme,a selection of suitable machine tools,and the setting of processing parameters.Fixtures tailored to the chosen machine tools were then designed to meet the processing requirements.Additional aspects of the project included the design of part drawings,calculation of working time quota,design of auxiliary guides,support clamping,and hydraulic circuits,all aimed at fulfilling practical production requirements.

Leaky Cable Fixture Detection in Railway Tunnel Based on RW DCGAN and Compressed GS-YOLOv5

The communication system of high-speed trains in railway tunnels needs to be built with leaky cables fixed on the tunnel wall with special fixtures.To ensure safety,checking the regular leaky cable fixture is necessary to elimi-nate the potential danger.At present,the existing fixture detection algorithms are difficult to take into account detection accuracy and speed at the same time.The faulty fixture is also insufficient and difficult to obtain,seriously affecting the model detection effect.To solve these problems,an innovative detection method is proposed in this paper.Firstly,we presented the Res-Net and Wasserstein-Deep Convolution GAN(RW-DCGAN)to implement data augmentation,which can enable the faulty fixture to export more high-quality and irregular images.Secondly,we proposed the Ghost SENet-YOLOv5(GS-YOLOv5)to enhance the expression of fixture feature,and further improve the detection accuracy and speed.Finally,we adopted the model compression strategy to prune redundant channels,and visualized training details with Grad-CAM to verify the reliability of our model.Experimental results show that the algorithm model is 69.06%smaller than the original YOLOv5 model,with 70.07%fewer parameters,2.1%higher accuracy and 14.82 fps faster speed,meeting the needs of tunnel fixture detection.

THE RESEARCH OF MANUFACTURING TOOLS(FIXTURES) PLANNING FOR ARMOURED FLEXIBLE CONVEYOR (AFC) USING CAD TECHNIQUE

The deepth and width of CAD application in coal mining equipments need promote furtherly. The information stream method is applied as the main clue to deal with the related technology and problems in research of manufacturing tools (Fixtures) planning for AFC (mining scraper bars conveyor) using CAD technique.

汽车车门装配用焊接夹具结构的改进设计

汽车车门装配用焊接夹具是为车门零件装配焊接作业提供便利的一种工具。在现阶段汽车制造企业中,焊接夹具在使用过程存在一定问题,其中最为突出的是装配精度、焊接精度不够,因此影响产品质量。所以,本文主要分析汽车车门装配用焊接夹具设计要点、设计需要考虑的影响因素等,进而重点探究汽车车门装配用焊接夹具结构改进设计对策,目的在于提高装配精度、焊接精度,实现高质量、高效生产制造。

基于S7-1200控制的液压焊接夹具控制系统设计

液压焊接夹紧装置在焊接加工中应用广泛。本文设计了一种基于西门子S7-1200PLC为控制核心的液压夹紧装置控制系统。以液压缸、换向阀、储能器为硬件基础设计了夹紧装置,使用位置传感器、光栅尺位置测量反馈搭建了控制系统,在对焊接件稳定夹持的同时,与焊接机械手配合,实现异形件稳定焊接,减小焊接变形,提高生产效率。

加工八分之一球体的夹具设计

针对八分之一球体常规的加工方法中所存在的材料浪费大、加工效率低和加工精度较难控制的缺陷,特设计出专用夹具。专用夹具设计采用与加工工艺流程相匹配的原则,针对不同的加工工艺和在加工过程遇到的难点,分别设计了2个夹具,解决了生产效率低、质量不稳定且材料浪费较大等问题。

附着物担保权冲突之解决方案

传统添附制度中,动产附合于不动产将导致原动产所有权消灭,无法满足动产担保交易的实践需要。根据交易当事人的合理预期,动产担保物权应延伸于附着物,非典型担保亦应同样延续。由此,不动产附着物有必要作为独立分类,以便同时负担动产担保权和不动产担保权。附着物在客观方面需要考察动产移除是否会造成不动产的物理损害,而不考虑整体功能性的影响。附着的主观方面需要探究当事人的意思,综合考虑附着物性质、当事人关系、附着的程度和目的等因素。在动产担保缺乏不动产登记的情况下,有必要平衡交易人信赖与动产担保延伸的需求,允许善意第三人在附着物上取得物权。出于交易稳定性与可预测性的考虑,附着物上延伸的动产担保有必要记载于不动产登记簿。购置物担保权人若在宽限期内登记,其超级优先权可构成登记顺位原则的例外。若是建筑物抵押权人旨在以完工后的建筑物作为抵押物,则其抵押权优先于购置款担保权。

超细长拉紧杆车槽夹具的设计

针对拉紧杆零件的结构特点及空刀槽的加工问题,设计了拉紧杆车槽夹具。介绍了拉紧杆车槽夹具的结构组成及重要部件的详细结构特征,给出了车槽夹具安装、使用方法。应用拉紧杆车槽夹具,可以提高拉紧杆零件表面质量和加工精度,在生产中具有良好的实用性。

航空薄壁零件切削加工技术研究进展

航空薄壁零件的加工精度和效率直接影响飞机的性能和可靠性。本文系统综述了航空薄壁零件切削加工技术,包括夹具技术、加工变形预测与控制方法、颤振预测与控制技术,以及数字孪生技术应用等多个方面。夹具技术详细研究了各种夹具的操作模式、结构特点、功能与应用等方面。变形预测与控制分析了薄壁件加工变形原因,并介绍了相关的控制技术和方法。颤振预测与控制探讨了切削过程稳定性分析技术和颤振控制技术,包括在线监测与识别、主动与被动控制技术和方法。数字孪生技术的应用部分介绍了该技术在薄壁件加工中的实际应用情况。通过对航空薄壁零件加工技术的系统综述,全面深入地介绍了相关内容,可为学者们的研究提供参考与指导。

3D打印膝关节曲面磨粒流抛光数值模拟及实验研究

目的解决磨粒流加工3D打印制造的TC4钛合金膝关节时存在配合端面抛光效率低以及表面质量不均匀的问题。方法运用FLUENT软件并结合非牛顿流体的Carreau-Yasuda方程对有、无仿形工装的磨粒流加工3D打印膝关节进行对比分析,研究仿形工装对磨粒流加工的影响规律,并通过单因素实验确定颗粒直径倍数与流道间隙大小的关系,从而完成最佳仿形工装设计。结果仿真对比分析结果表明,仿形工装有助于减小压力损失,并且膝关节表面的切削量显著提升,最大提升了182.92%。同时,在双向磨粒流工艺下,膝关节表面切削量的不均匀程度平均降低73%,提升了表面质量的均匀性,证实了仿形工装的有效性。加工结果表明,当仿形流道间隙大小为5倍Si C颗粒直径、工作压力为2 MPa、加工时间为45 min、使用双向磨粒流工艺时,3D打印膝关节的整体表面粗糙度显著降低,平均表面粗糙度为0.67μm。主要配合曲面呈现镜面效果,表面粗糙度达0.38μm与0.46μm。结论当仿形工装的流道间隙为5倍SiC颗粒直径时,磨粒流抛光效果最优。采用双向磨粒流工艺,获得了优于单向磨粒流工艺的均匀表面压力,从而有效提升了表面质量的均匀性,为3D打印钛合金人工骨复杂曲端面的光整加工提供了理论参考和实验依据。

直吹管浇注料振动成型夹具的结构优化设计

针对直吹管浇注料振动成型夹具质量过大和动态特性差等问题,建立夹具优化数学模型,采用拓扑优化对夹具结构材料分布进行寻优,并在拓扑优化基础上以灵敏度分析筛选相关性较大的尺寸作为优化变量,基于Kriging法建立响应面模型,采用多目标遗传算法对振动夹具进行尺寸优化,两次优化后的夹具质量共减小了12.7%,1阶固有频率共提高了2.8%。对优化后夹具结构进行扫频振动响应仿真分析,验证了夹具优化设计的有效性及合理性,有效解决了直吹管浇注料振动成型夹具设计中容易出现的试验共振和夹具质量过大等问题。

铝型材冷却初拉伸控制

针对铝型材加工过程中的拉伸夹具及冷却时间度量问题,设计适用于不同型号的拉伸夹具,确定了不同加工参数下的最佳冷却时间。通过优化拉伸夹具的设计和冷却时间的控制,能够提高铝型材的加工质量和生产效率。实验结果表明,该方法能够有效地改善铝型材的性能和形状,具有较高的应用价值。

基于有限元分析多件装夹夹具体结构设计研究

为了研究某汽车制动泵缸体件多件装夹夹具体结构刚性,利用UG软件建立多件装夹夹具体模型,通过ANSYS有限元分析比较无拉杆和有拉杆两种夹具体结构变形情况。结果表明,设置拉杆的夹具体结构变形比无拉杆的夹具体结构变形小,可有效地控制装夹变形量。基于此,设计一种对称式多件装夹夹具体,装夹时无需考虑夹具体变形量,只需关注被装夹工件的变形,简化了夹具体整体结构。在多件装夹夹具中,优先采用对称式夹具体结构设计,其次是拉杆式夹具体结构设计。研究结果可为企业设计多件装夹夹具体结构提供参考。

法兰盘的工艺分析与专用夹具设计

法兰盘是工业产品中常见的连接元件,其典型的加工工艺包括:零件图的分析、毛坯图的设计,机械加工工艺过程的编制、数控加工工序的编制、数控加工刀具的选用和数控加工进给路线图的绘制等。针对工序8中难加工的φ6mm斜孔,设计了一套钻床专用夹具,其中,钻模板设计成可翻转式样,钻套设计成快换式特种钻套。夹具采用一面两销的定位方案,限制了工件的六个自由度,达到了完全定位。最后,对夹具的定位误差进行了计算,验算后,确定该夹具的定位误差控制在图纸的加工精度要求之内,满足加工要求。

基于模糊自适应PID控制器的夹具自适应控制研究

为提高夹具自适应控制的稳定性和响应速度,以电磁无心夹具为研究对象,提出一种基于模糊自适应比例-积分-微分(proportion integration differentiation, PID)控制器的控制方法。首先构建夹具数学模型,然后结合模糊控制和PID控制的优势,构建模糊自适应PID控制器对夹具进行自适应控制,最后通过在MATLAB软件上进行仿真。结果表明,该方法实现了阶跃信号、突加负载、正弦信号输入等不同条件下的夹具控制,且具有优异的控制性能。整个控制过程中,该方法超调量为2.11%,响应时间0.08 s。相较于PID控制器、模糊控制器、自抗扰控制器、模糊滑模控制器,该方法提高了夹具自适应控制的精度和响应速度,且可用于实际夹具自适应控制中,具有一定的实际应用价值。

摇臂连杆加工工艺与钻专夹设计

文章根据摇臂连杆的结构特点和技术要求,制订了该零件的机械加工工艺规程;在对定位装置、夹具装置及夹具体进行分析的基础上,设计并制造了用于第六道工序Φ35孔的钻孔专用夹具。应用结果表明,该夹具做到了加工精度保证、设计方案合理、结构简单实用,能有效提高摇臂连杆的加工质量及效率。

车架纵梁焊接变形控制在生产线中运用

车架总成运用在皮卡、轻卡和非承载式乘用车上,是非常重要的底部骨架件。车架总成质量对整车安全、舒适性影响较大。车架总成中纵梁总成的焊接变形最难控制,传统的控制焊接变形方式已经很难保证纵梁总成变形量,使得车架整体尺寸控制和装配都难达到高品质要求,为了提升车架总成尺寸,降低车架纵梁总成焊接变形量,本文对车架纵梁总成焊后变形进行研究,从夹具设计和机器人焊接布局两方面来保证纵梁总成焊后变形控制在2.3-3.2mm,从而保证车架总成尺寸和生产效率。