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。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to