基于PolyWorks虚拟匹配间隙面差测量规范研究

随着智能制造的不断发展,人们对汽车品质的要求也越来越高,间隙面差作为评价白车身装配制造质量的一个重要因素越来越受到汽车制造业的关注.传统的间隙面差测量存在着损伤被测零件、效率低、可重复性差、易受人为因素影响等问题,已经越来越不能满足企业的需求.本文基于PolyWorks工业软件,以传统间隙面差测量为基础,对常见的间隙面...     

一种基于测点生成的间隙面差名义值算法

本文提出一种白车身装配CAD模型间隙面差名义值的算法,该算法基于UG二次开发测点生成,在零件需要保证精度的匹配关键位置生成测点,并由点生成截面,获得两个匹配零件该截面处信息,该信息包括测点坐标、截面线,从而计算的出该匹配零件间隙面差的名义值。该名义值将用于实际测量真实值的比对,来判断两匹配零件匹配实际信息是否合格。由于实际零件扫描测量点云已经和CAD模型配准,计算名义值过程中所提取截面测点坐标等信息,将转化为截面位置信息来测量实际零件这些重要位置的间隙面差。     

液体垫片对复合材料装配结构应力和应变的影响

复合材料较复杂的成型工艺导致其构件的制造精度偏低。装配时,偏差会使配合面间产生装配间隙,当间隙超过一定的大小时,需要采取补偿措施,即用垫片填补间隙。基于一种简化装配模型,通过实验和有限元分析方法,研究了液体垫片对复合材料装配结构应力和应变的影响。通过比较强迫装配和液体垫片补偿两种情况下施加螺栓预紧力时构件表面的应变,分析了复合材料构件的变形。进行应力分析时,通过提取单元积分点应力分量计算构件的安全裕度,研究液体垫片对复合材料装配结构应力的影响。得出如下结论：强迫装配时,处在装配间隙边缘的区域受间隙影响相对严重,该区域发生较大的弯曲变形,构件中间部分由于局部贴合反而使装配间隙的影响相对较小;液体垫片在改善间隙边缘危险区应变状态的同时,也使构件中间贴合部位的螺栓头挤压区和部分非挤压区的应变增大,但总体而言,液体垫片的引入使应变分布趋于均匀;当装配间隙大于0.7 mm后,液体垫片补偿对于构件安全裕度的提升作用明显下降。     

夹片螺母装配失效分析

对汽车总装线上装配螺栓的过程中被撕裂的夹片螺母进行了理化检验和失效原因分析。结果表明:夹片螺母是由于受到了较大的外力而发生一次性过载撕裂;还原并分析装配现场发现,夹片螺母及与其相连的两个钣金件之间的相对位置出现了错配,从而导致装配时因未对正而发生夹片螺母过载撕裂失效。     

焊前装配精度对 5083 铝合金 FSW 工艺的影响

搅拌摩擦焊属于精密的加工技术,对焊前装配精度要求比较高,装配精度的高低会直接影响焊缝性能的优劣。基于这一背景,研究了装配过程中对接间隙和板厚差对铝合金搅拌摩擦焊焊缝表面成形、内部成形以及力学性能的影响。研究表明:FSW工艺对对接间隙存在1.1 mm的容限,在0~1.1 mm的对接间隙内,焊接接头与无缺陷接头的力学性能比较接近,当对接间隙高于这个值时,接头性能就会由于缺陷的出现而显著降低;FSW工艺对板材板厚差也存在一定的容限,当板厚差低于容限,所得接头的力学性能差距不大,当板厚差高于容限,焊接质量就会显著下降。     

薄板件多工位装配尺寸误差建模与仿真

为保证薄板件装配尺寸精度,分析了两种主要误差源夹具尺寸误差和零件尺寸误差,尤其是定位销误差与零件孔间隙对装配尺寸误差的影响.采用状态空间法建立了薄板件多工位装配尺寸误差传递模型,并以某汽车地板薄板样件为例,运用所建立的尺寸误差模型对薄板样件进行仿真计算,仿真结果与实际测量结果进行对比,验证了模型的正确性和实用性.该模型可应用于多工位装配尺寸误差源诊断、装配过程夹具优化设计和装配过程稳定性分析等.     

钣金件模态分析及设计优化

采用ANSYS有限元分析软件进行钣金件的模态分析,计算钣金件的自然频率及模态振型,并由自然频率和模态振型进一步讨论如何提高钣金件的结构刚性,最终设计出合适的钣金件结构.     

钣金件弯曲回弹的机理分析及补偿校正措施探讨

钣金件以其自身强度高、质量轻、导电性好、成本低廉等优点,被广泛应用于通信、汽车制造业、电子电器、医疗器械等多个领域当中。近年来,随着钣金件的应用越来越广泛,其设计成为了相关产品开发的重要环节之一,而在钣金件生产加工的过程中,往往需要对其进行弯曲处理,以此来满足不同产品的需求。在对钣金件进行弯曲的过程中,弯曲回弹是最为常见的一类缺陷,同时也是钣金件弯曲加工中的技术难点之一,一旦钣金件发生弯曲回弹会对其成形件的质量造成严重影响。以往针对这一问题基本都是采取多次重复修模和试模等方法予以解决,但实际效果并不理想,从而导致了钣金件生产效率较低。想要进一步提高钣金件的生产效率就必须采取有效途径解决弯曲回弹问题,这也是本文研究的重点之所在。基于此点,本文首先对钣金件弯曲回弹的机理进行详细分析,并在此基础上提出钣金件弯曲回弹的补偿校正措施。     

改进的圆柱面接触热阻模型及其应用

在惯性约束核聚变冷冻靶系统中,硅冷却臂与封装套的装配面会产生显著的接触热阻。为了预测该热阻,提出了一种改进的适用于柱面接触且有胶粘剂填充装配间隙的接触热阻计算模型,该模型计算了通过材料接触部分和接触间隙的传热。用柱面裸接触的实验数据对模型进行了验证。分析结果表明采用较光滑的接触面和导热系数较大的胶粘剂可有效降低接触热阻,而装配应力及胶在固体上的接触角对接触热阻影响不大。     

基于点云三维重构的配合面装配间隙分析方法研究

在大型航空复合材料零部件装配过程中难免出现装配对接间隙,由于间隙较小,当构件固定之后内部间隙不可达,难以测量。因此,为了克服这一难题,完成装配体小间隙的测量,本文提出了利用逆向重建和虚拟装配的方式进行装配间隙测量的方案。本文基于大型航空复合材料零部件测量的背景,结合双目视觉测量原理,采用视觉与激光相结合的测量方式,研究从点云获取至装配仿真模型的逆向重建技术,在CATIA的虚拟环境下完成装配间隙的测量。     

轿车后围板成形过程数值模拟及参数优化

为提高轿车后围板零件的成形质量和设计效率,采用单向拉伸试验,测定了板料的力学性能参数,并对测量参数的有效性进行了验证;基于测量的参数,对该零件的冲压成形过程进行了数值模拟,改进了拉延筋的受力并优化了工艺和模具参数;对零件成形之后的回弹进行了研究,并对回弹变形进行了补偿.研究结果表明:采用测定的参数能有效地提高数值模拟的精度;优化拉延筋的受力及成形参数,可以提高成形件的质量;利用补偿法可以有效的补偿零件的回弹变形;经验知识与数值模拟相结合的优化方法是提高产品质量及工艺设计效率的有效途径.     

Developing a selective assembly technique for sheet metal assemblies

Applying the concept of Digital Twin in production processes supports the manufacturing of products of optimal geometry quality. This concept can be further supported by a strategy of finding the optimal combination of individual parts to maximise the geometrical quality of the final product, known as selective assembly technique. However, application of this technique has been limited to assemblies where the final dimensions are just function of the mating parts' dimensions and this is not applicable in sheet metal assemblies. This paper develops a selective assembly technique for sheet metal assemblies and investigates the effect of batch size on the improvements. The presented method utilises a variation simulation tool (Computer-Aided Tolerancing tool) and an optimisation algorithm to find the optimal combination of the mating parts. The approach presented is applied to three industrial cases of sheet metal assemblies. The results show that using this technique leads to a considerable reduction of the final geometrical variation and mean deviation for these kinds of assemblies. Moreover, increasing the batch size reduces the amount of achievable improvement in variation but increases the amount of achievable improvement in the mean deviation.     

A novel approach to include sustainability concepts in classical DFMA methodology for sheet metal enclosure devices

Nowadays sustainable design is a mandatory requirement in the product development process. For this reason, design methodologies are addressed to establish a close relationship between environmental, social and economic impact indicators and product features from early design stages, especially in those features related to its manufacturing. In this paper, the design for manufacturing and assembly—DFMA methodology is adapted to sheet metal enclosure devices, integrating functional and component relationships to minimize particular sustainability indicators such as energy consumption, carbon footprint, number of parts, required amount of material, assembly time and manufacturing costs. Savings with the proposed method are achieved following specific sub-tasks oriented to define new simplified product components, considering changes in manufacturing processes and re-defining mechanical connections between parts. Traditional DFMA approaches consider manufacturing and assembly issues related to a reduction of product complexity and economic savings. The proposed method aims to examine the benefits in life cycle stages such as raw material consumption, service, maintenance, upgrading and end of life—EOL. The methodology is validated through a redesign of a sheet metal industrial clock, in which the sustainability impacts are calculated from a comparison of an existent product vs. a new product development. The implementation of the method in the case study demonstrate reductions of more than 25% in product mass, consumed energy and CO₂ footprint, and more than 50% in theoretical assembly time and product complexity. Sustainability indicators of the proposed method are selected from literature analysis and taking into account attributes of sheet metal enclosure devices.     

汽车车身钣金加强肋隔声性能实测与计算分析

研究了汽车车身钣金加强肋隔声性能实测与计算分析,利用SEA方法和FE-SEA方法建立薄板隔声量计算模型,并与测试值进行对比验证。以车身钣金加强肋高度、宽度、加强肋开孔及钣金加强肋布置密度等因素为变量,设计并制造出不同方案的车身钣金加强肋,然后在混响室-全消室中测试了不同方案钣金加强肋隔声量。试验结果表明,钣金加强肋宽度增加,隔声量在全频段上增大;在钣金加强肋上开孔,隔声量下降;钣金加强肋布置密度增大,隔声曲线峰值、谷值增多。基于试验与计算对比结果,对汽车车身钣金加强肋隔声量计算影响因素进行了分析。     

Quality design of tolerance allocation for sheet metal assembly with resistance spot weld

Tolerance directly influences the functionality of the products and the related manufacturing costs, and tolerance allocation is of great importance for improving the assembly quality. However, the information required to allocate tolerances for complex 3D assemblies is generally not available at the initial design stage. In this paper, a new quality design methodology is developed, which makes use of both original design data obtained by the response surface methodology and the extra interpolation data obtained by the Kriging method. The finite element modelling is presented for the sheet metal assembly process as no explicit relationship of the variations for key characteristic points are available. The robust tolerances can be allocated based on the quality design model. A case study with the typical assembly process of the rear compartment pan and the wheelhouse is carried out in the paper, the tolerance allocation results show that the developed quality design methodology is capable of determining the robust manufacturing tolerance before assembly, which satisfies the product requirements. This method enables a robust tolerancing scheme to be used in the sheet metal assembly process.     

Experimental and numerical evaluation of multilayer sheet forming process parameters for light weight structures using innovative methodology

Being light weight and superior in characteristics, hybrid materials such as fiber metal laminate (FMLs) and functionally graded structures (FGS) are becoming increasingly popular in aeronautical, automobile and military industries. In the present work, an innovative methodology which hereafter will be named as “3A method” has been proposed to replace complex shaped, monolithic, metallic sheet parts with hybrid parts. This method is based on simultaneous forming of any number of multiple metallic blanks in required shape by applying hydroforming (HF) technology. Based on numerical simulations, forming limit diagrams (FLDs) are established for three types of blanks forming hemispherical shaped parts using Barlat 2000 yield criteria/DYNA Form/LS Dyna. To validate the simulation results, experimental study is accomplished and optimal process parameters are determined by varying the cavity pressure under constant die-binder gap. Effects of number of layers and thickness of blanks on thinning, wrinkling and punch force have been well studied for three types of blanks and a comparative analysis is made to investigate various failure modes. To achieve a composite layered structure, post forming procedure has been devised and implemented to get a final hybrid part. Furthermore, limitations of the 3A method in terms of final shape of parts are discussed. Good agreement can be found between numerical and experimental research. The new methodology is capable of employing any types of resins and composite materials at any required place in parts for desired characteristics. Elimination of repeated heating and solidification of blank assembly as well as precise punch force and speed requirements make this multilayer blank forming method more efficient, economical and user friendly for manufacturing of FMLs and FGSs at commercial scales.     

A WWW-based integrated product development platform for sheet metal parts intelligent concurrent design and manufacturing

This paper presents a WWW (World Wide Web) based integrated product development platform for intelligent concurrent design and manufacturing of sheet metal parts. In order to achieve this platform, several major modules are discussed. These modules mainly include the structure of the WWW-based integrated product development platform, an information integration framework, a RTCAPP (real time computer aided process planning) module, a customer interface module, and a design/manufacturing knowledge-based module for supporting product design and manufacturing. This paper gives the structure of the information integration framework for concurrent design and manufacturing of sheet metal parts. An information integration framework, called 'step structure information framework' is proposed. The principles, called 'zero thickness and zero bend radius' are put forward, which can be used to abstract the geometric entities of sheet metal parts in order to facilitate product design and modelling. Finally, case studies are given.     

Maximising manufacturing system efficiency for multi-characteristic linear assembly by using particle swarm optimisation in batch selective assembly

Quality of an assembly is mainly based on the quality of mating parts. Due to random variation in sources such as materials, machines, operators and measurements, even those mating parts manufactured by the same process vary in their dimensions. When mating parts are assembled linearly, the resulting variation will be the sum of the mating part tolerances. Many assemblies are not able to meet the assembly specification in the available assembly methods. This will decrease the manufacturing system efficiency. Batch selective assembly is helpful to keep the assembly requirement and also to increase the manufacturing system efficiency. In traditional selective assembly, the mating part population is partitioned to form selective groups, and the parts of corresponding selective groups are assembled interchangeably. After the invention of advanced dimension measuring devices and the computer, today batch selective assembly plays a vital role in the manufacturing system. In batch selective assembly, all dimensions of a batch of mating parts are measured and stored in a computer. Instead of forming selective groups, each and every part is assigned to its best matching part. In this work, a particle swarm optimisation based algorithm is proposed by applying the batch selective assembly methodology to a multi-characteristic assembly environment, to maximise the assembly efficiency and thereby maximising the manufacturing system efficiency. The proposed algorithm is tested with a set of experimental problem data sets and is found to outperform the traditional selective assembly and sequential assembly methods, in producing solutions with higher manufacturing system efficiency.     

曲面柔性轧制装置设计与成形工艺分析

采用曲面柔性轧制方法可以实现三维曲面板类件的连续、柔性成形,为了验证该方法的可行性,本文基于曲面柔性轧制原理,设计出成形装置并研究了装置关键部件工作辊的驱动方式,驱动方式可以分为单端与双端两种;进行相关成形实验并对曲面柔性轧制成形工艺进行了分析,探讨了成形过程.结果表明:一次调形成形工艺适用于小变形量情况,成形质量好,效率高;渐进调形成形工艺,以小的压下量逐渐使板料成形,在一定程度上可以消除板料边缘皱褶,减小回弹,利于板料成形;理论上讨论了实时调形成形工艺,该种工艺将会提高成形自动化与效率.对成形件进行了成形精度与厚度分布研究,表明成形效果良好,验证了曲面柔性轧制成形方法的可行性与实用性.     

Numerical modelling,validation and analysis of multi-pass sheet metal spinning processes

Conventional sheet metal spinning is an incremental forming process which typically involves the cost-effective and high-quality manufacturing of axissymmetric parts. The process is usually executed by highly skilled and experienced personnel which is able of optimizing the process parameters during production. Numerical simulation of the process can substantially help discovering systematic methodologies for optimal parameter determination and thus enable the full automation of the process using CNC machines. The present work aims to assess the quality of numerical modelling techniques by a direct comparison with metal spinning experiments. Based on the geometry and thickness distribution of intermediate and final stages of a spinned component, which are measured using the Optical 3D Digitization technique, the quality and validity of different numerical modeling approaches are assessed. Subsequently, deformation mechanisms occurring during process are identified, analysed and discussed.