白车身制造尺寸质量控制中的软测量方法

在白车身制造尺寸质量控制过程中,主要采用样架、三坐标测量机(CMM)、在线三坐标测量机(OCMM)进行检测。比较三者,样架和CMM测得的数据“点多量少”(测点很多,每个测点每天有1到2个数据),而OCMM测得的数据“点少量多”(测点相对较少,每个测点每天有200个左右数据)。采用软测量的方法,可使CMM测量数据和OCMM测量数据进行互补,达到精确评价车身制造质量的目的。     

浅谈激光在线测量系统在焊装线体上的应用

在汽车制造工艺过程中,白车身作为所有装配的载体包括了汽车各系统功能安装点,白车身精度的稳定性是至关重要。目前,各汽车厂普遍采用在线+离线组合的测量方式对白车身质量进行监控,在线测量系统的应用实现100%测量的,实时、动态监控生产线,及时发现质量异常,并报送给质量人员开展分析和处理;同时能够将测量的数据存储,为生产过程中的SPC、MSA等分析工具提供大量的数据支撑,更有效地对误差做出客观性判定和指导生产。     

GPS测量数据处理质量评价与优化方法探述

随着GPS技术的不断成熟与发展,在现代工程测量中得到了广泛应用。在应用GPS技术进行测量定位时,数据处理的质量将直接关系到测量的准确性,因此测量人员应准确掌握GPS测量数据处理的方法,对其处理质量进行准确评价,同时应对GPS测量数据的处理方法不断加以优化改进,进一步提高数据处理的质量,从而提高GPS技术测量定位的精度,为相关领域项目的建设提供更加准确的参考依据。     

数据库技术在车身在线测量系统中的应用

为了提高汽车生产质量 ,逐步实现零废品生产过程 ,需对车身的加工情况进行在线质量控制。要使得整个测控过程更全面、更准确、更具有智能性 ,需要寻求一种合适的数据存储及提取方式 ,以快速、方便地存储和处理在线检测站的大量数据。从这个角度出发 ,研究数据库技术在车身在线测量过程中的作用。研究的侧重点是如何应用最新数据库技术 ,结合Matlab和其它先进的数据处理方法 ,使数据库系统更具方便性、智能性和系统性     

对汽车焊装夹具的设计的探讨

汽车焊装夹具属于汽车车身结构焊装的专用夹具，其设计工作是一项十分复杂的工作。为了更好的确保整个车身的装配精度以及焊接的质量，如何进一步优化汽车焊装夹具的设计工作显得尤为重要。本文主要针对汽车焊装灾具的具体设计情况进行探讨。     

Bootstrap重采样Bayesian方法在白车身制造尺寸不合格率估计中的应用

白车身质量是汽车整车质量控制中的重要环节,针对白车身制造尺寸质量控制中检测数据属于小样本数据、数据处理分析不能采用一般大样本条件下统计分析方法的问题引入Bootstrap重采样Bayesian方法。通过对白车身尺寸质量的不合格率进行定义,分析简单计算、滑动计算、β分布Bayesian计算等3种估计不合格率的方法,引入Bootstrap重采样技术结合Bayesian方法进行不合格率的估计,并通过Matlab软件对4种算法进行仿真比较。仿真结果表明,Bootstrap重采样Bayesian方法的预测精度高于其余3种方法,适用于小样本情况下白车身制造尺寸不合格率的估计。最后通过一个实例演示了Bootstrap重采样Bayesian方法在白车身制造尺寸不合格率估计中的应用流程。     

轿车白车身装配过程的一种模型表达方法

提出一种称为“TRAS”模型的轿车白车身装配过程表达模型,通过车身装配树表达工艺过程,通过零件和总成件装配矩阵表达车身结构和装配关系,并通过基准点、定位点、装配点、检测点等及其他要素特征点及其特征矩阵,来描述装配特征和装配尺寸传递关系。该模型为进一步开展定量偏差分析奠定了数据表达基础,可应用于白车身CMM测量数据分析和尺寸偏差诊断。     

基于XGBoost的车身尺寸装配质量智能预测模型

针对汽车多级制造系统中传统机器学习方法处理多元数据样本时间久、精度低等问题,提出一种基于XGboost的车身尺寸装配质量智能预测模型,解决多级制造系统的车身装配精准预测控制问题。首先,通过对车身多级装配过程的分析,对数据样本进行预处理,建立基于Spearman系数的不同特征要素的绝对相关性矩阵;其次,对生产流程的相关数据实时采集、清洗及挖掘分析,提出数据分析流程与数据处理框架,建立基于XGBoost的车身尺寸装配质量智能预测模型,并通过对模型性能的有效评估实现对车身尺寸装配的精准控制;最后,仿真实例对比分析表明,基于XGboost的质量智能预测模型能精准地解决多级制造系统中的车身装配质量控制问题。     

测量的不确定度 第三讲 数据处理的依据

§3—1 数据处理所谓数据处理,就是运用数学方法,对由测量所取得的数据进行归纳、分析等处理,以找出被测量、影响量和干扰量的相互关系,从而给出正确的测量结果及其评价。数据处理的科学基础是误差理论。由于科学技术的突飞猛进,特别是由于电子计算机的应用,使数据处理在理论上和实用上都得到极大的发展,处理数据的速度在短短的几年内就提高了好几个数量级。现在在测量过程中的实时处理和预处理也已得到广泛的应用,从而推动了自动测量和动态测量工作向更高的水平迈进。     

汽车焊装夹具的优化设计研究

汽车焊装夹具作为汽车车身生产的重要组成部分,其工艺水平是反映汽车生产制造水平的重要因素。夹具质量直接影响汽车生产规模、生产效率和生产质量。近年来,随着我国汽车工业的迅速发展,激烈的市场竞争使汽车产品的更新换代越来越快,汽车车身设计越来越个性化,对汽车焊装线的需求量巨大,必须自行设计适合我国国情的汽车焊装线,努力提高设计和制造能力。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.