Intelligent Painting Process Planner for Robotic Bridge Painting

Due to increased government regulations on environment, health, and safety, the cost of on-site bridge painting has quadrupled over the past several years. The construction industry faces a great challenge in how to control the increased costs of bridge painting and meet the regulations at the same time. A possible solution to address this challenge is to develop a robotic bridge painting system. The development of the robotic system can be justified by the potential improvements in safety and productivity. This paper presents the development and testing of an Intelligent Painting Process Planner. The Planner, built based on bridge feature scheme, is the key component for the robotic bridge painting system that integrates the painting process planning, robot path planning, cost optimization, and quality control functions. During the development process, lab experiments were conducted to determine the values of painting process planning parameters and coating thickness distribution functions. Field tests demonstrated that the prototype robotic bridge painting system achieved the specified painting quality using the parameter values provided by the Planner. Areas that need to be improved in the future were also identified.     

Evolution of appearance profile of hot-dip galvanized car-body steel sheet during deformation process

In recent years,the waterborne free intermediate coating process has been widely used in the automotive industry.Because the baking times and coating thickness are decreased,the surface covering capability of the painting process is reduced,which directly affects the appearance quality (long-and short-wave values) of the body paint.Thus,there are correspondingly higher requirements for the white body surface profile prior to painting.The surface profile of the white body is mainly affected by the plate material,the surface profile,and the deformation process.So,the change rule for the surface profile during deformation of the steel plate is a key factor in coating appearance optimization.In this paper,we first analyze the typical deformation of the outer cover of a car body.Then,we examine the change tendency of the surface profile of steel plates with respect to different deformation rates,specifically for a steel plate comprising a hot-dip galvanized bake-hardened steel sheet.Based on our analysis of the influence of the deformation on the coating appearance,we selected 3％,5％,and 8％ deformation rates in this research.We found the roughness (Ra) value in the typical deformation range (3％-8％) of the car body to exhibit a decreasing trend at first and then an increasing trend.The Ra value of the 8％ deformation is not more than the original plate test value.When the Pc value of the original plate is in the lower range (about 60),it exhibits a slight increasing trend in the deformation process (3％-8％).And when the Pc value of the original plate is in the higher range (about 120),it exhibits no increasing trend in the deformation process (3％-8％).In contrast,the waviness (WCA) value in the car body's typical deformation range (3％-8％) shows a significant growth trend.     

冲压“积瘤”对汽车外板涂装影响及对策分析

评价热镀锌汽车外板表面质量的参数包括粗糙度、波纹度和PC值,而评价汽车板涂装后表面质量的重点参数包括桔皮、鲜映性、长波、短波等。冷轧钢板表面粗糙度的波长在油漆前后有明显的差别,油漆前冷轧钢板表面的起伏以短波长的比例占优势,而油漆后短波长的部分几乎消失,长波长部分仍然保留并且占优势。以汽车公司反映最为强烈的影响涂装的表面积瘤缺陷为切入点,全面分析了积瘤的类别及缺陷形成的根本原因,重点制定了包括降低入锌锅板温,优化入锌锅板温与锌锅温度的匹配,通过提高锌锅铝含量来抑制锌锅中的铁,保持铁含量在极低的范围内,从根本上抑制锌粒的形成,从而达到有效降低锌粒缺陷比例,降低汽车公司返修率,满足2C1B涂装工艺要求的目的。     

Variables affecting the wetting of tinplate by Sn-Pb solders

An automated test apparatus has been developed which, for any specific system of tinplate-fluxsolder, enables a very rapid and reproducible direct measurement of four solder wettability parameters;viz., time for initial wetting, wetting rate, equilibrium wetting force, and time to reach this force. These parameters have been measured to determine the effects of the following tinplate soldering variables: three different mild rosin fluxes, solder temperature and composition, tinplate thickness, tin and alloy coating thickness, surface roughness, tin oxide films deposited electrochemically and by baking, and chrome oxide passivating films. In general, wettability data concur with capillary rise measurements but have the advantage of being obtained more rapidly, of being more sensitive to surface state variables, and of being more reproducible. Of the four measured parameters, wetting rate is most sensitive to tinplate surface state and equilibrium force is the best indicator of solder spread.     

Online prediction and monitoring of mechanical properties of industrial galvanised steel coils using neural networks

In galvanising line of cold rolling mill, mechanical properties, i.e. yield strength (YS) and ultimate tensile strength (UTS), are achieved by controlling the key process parameters within specified limits. In this paper, a feed-forward back-propagation artificial neural network (ANN) is proposed to predict the mechanical properties of a coil from its chemical composition, thickness, width and key galvanising process parameters. Principal component analysis is used to avoid redundancy and collinearity effects in input variables for the ANN. The model predicted the YS and UTS with an accuracy of ±10?megapascal (MPa) for 90% of the data. The model was implemented in the continuous galvanising line of Tata Steel, India. An online quality monitoring system was developed to monitor the predicted mechanical properties and process parameters of a galvanised coil. This system helps quality team in decision making.     

Shaping of sheet to produce large-diameter welded pipe

The quality of welded pipe (diameter 508–1420 mm; wall thickness 8–48 mm) of strength class up to K80 (X100) is investigated. Plastic shaping is simulated, with quantitative estimation of the stress–strain state of thick-walled pipe blanks in TESA 1420 presses during edge bending and stepwise shaping. The corresponding computer program permits calculation of the setup of the equipment and determination of the geometric parameters of the pipe blank specified in the standards. Theoretical results are presented for a range of large-diameter pipe produced on the TESA 1420 system.     

Tailored Profiles Made of Tailor Rolled Strips by Roll Forming – Part 1 of 2

To fully exploit the potential of sheet and profiles, various technologies to produce tailored blanks and profiles have been developed [1,2]. In earlier work [3] it has been shown that Strip Profile Rolling (SPR) can be used to produce metal strips with a predefined thickness distribution across the width of the strip. Building upon this knowledge, in two subsequent papers the extended goal of the project is presented. Therein is demonstrated that Strip Profile Rolling can be applied very effectively using a combination of roll forming (part 1) as well as further processing by roll forming (see part 2) to allow for the production of profiles with varying wall thickness in their cross section. To achieve the goal of part 1, a numerical model describing SPR was developed and used to study the influencing process parameters on spread and bulge formation. As a result of this parametric study, an optimized roll design and rolling sequence was developed to produce a demonstrator strip on a 12 stand roll forming mill manufactured by the company Dreistern [4]. Starting with a conventional strip out of DC01 steel (width 170 mm, thickness 2.5 mm), 29 rolling passes were necessary to achieve the desired geometry (width 186 mm, thickness 2.5 mm with a longitudinal groove being 64 mm wide where the thickness is reduced to 1.5 mm). In the second part of the process chain the coils produced by Strip Profile Rolling were successfully roll formed into a circular tube of 60 mm.     

镀层重量控制

钢板热镀层厚度控制精度的镀层质量要求越来越高,西门子公司和ThyseenStahlAG公司共同开发出神经元网络的镀层控制模型就能很好解决这个问题,降低了成本,并取得了明显的经济效益 ,是一项新技术。     

Multi-objective Optimization of Electrodeposition of Ni–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nano Composite Coating on Al6061 Substrate

Response surface methodology based Grey relation analysis has been used to optimize the coating parameters of composite coating on aluminium based alloys. This approach gives the best combination of coating parameters to get maximum coating thickness, adhesive strength, microhardness, and minimum wear rate. For each response, the effect of coating parameters at different levels have been discussed. From Grey relation grade, the optimum parameters for better composite coating performance are found to be: temperature, 34 °C; current density, 1 A/dm²; and percentage of particle loading, 1.2 g/L. At 95% significance level, the Current density shows statistical significance on overall composite coating performance.     

Design of a high-precision twin-roll strip caster

During strip casting,the thickness deviation of casting strip directly affects the quality of the hot-rolled sheet because the casting strip needs to be rolled only once. To accurately control the gap between casting rolls and reduce the thickness deviation of the casting strip,a conceptual design of a prestressed twin-roll caster is proposed herein; this caster involves the setting of a constant pressure balancing cylinder between the chocks of two casting rolls. The balancing cylinder hydraulic system adopts a three-way servo valve that controls the hydraulic cylinder.The parameters of the hydraulic power components are determined using the principle of optimal power matching,and the hydraulic system model of the balancing cylinder is thus established. The dynamic analysis and simulation of the hydraulic system are performed using finite element model to obtain relevant evaluation indexes. Finally,the hydraulic system is corrected using proportional-integral-derivative( PID) correction to achieve a well-controlled effect. Thus,the engineering requirements of the strip casting process can be met.     

航空发动机篦齿类零件耐磨封严涂层的工艺控制

等离子喷涂工艺制备的 Ni-5%Al/Al2O3 -TiO2 耐磨封严涂层广泛应用于航空发动机篦齿封严系统中,涂层厚度对提升发动机效率有着至关重要的作用,随着封严篦齿间隙从 1.0 mm 减小到 0.2 mm,气体实际泄漏流量减小幅度可达 73%。由于篦齿零件形状复杂,主要对批生产中篦齿零件常见的涂层厚度和外观控制进行了研究,通过采用硅橡胶和金属工装共同保护的方式,避免了涂层局部堆积情况并消除了涂层边界的毛刺等缺陷。此外,通过建立试片与篦齿涂层厚度的对应关系,对比了不同测量方式间的差异,实现了批生产过程中对篦齿涂层的间接控制,从而实现了该类零件涂层厚度的高效无损检测。     

CrAlN/VN多层膜调制比对涂层性能的影响

为开发适用于干式切削的既硬又润滑的涂层,采用磁控溅射工艺制备调制周期厚度为20nm的CrAlN/VN多层膜结构涂层,研究不同CrAlN/VN调制比对涂层性能的影响;利用场发式电子探针(FE-EPMA)、掠入射X射线衍射分析仪(GIXRD)、场发式扫描电镜(FE-SEM)、透射电子显微镜(TEM)和X射线光电子能谱仪(XPS)表征涂层的微观结构和化学组成;利用纳米压痕仪表征涂层的纳米硬度和弹性模量;利用Ball-on-disc磨耗试验仪表征涂层的摩擦因数。结果表明:当CrAlN/VN的调制比为1∶2时,涂层具有最高硬度(21.8GPa);涂层与碳化钨合金的摩擦因数最低为0.26。随着CrAlN/VN调制比的增大或减小,伴随着CrAlN或VN子层厚度减薄,涂层的硬度有增强的趋势;随着VN含量的增加,涂层的摩擦因数略有下降。     

冷轧热镀锌镀层厚度控制系统的开发与应用

 在冷轧连续热镀锌生产线上,热镀锌镀层厚度的控制水平将直接影响到热镀锌板的产品质量、成本和市场竞争力。以鞍钢连续热镀锌生产线为背景,对冷轧热镀锌带钢的镀层厚度进行精确控制研究,利用有限元分析软件FLUENT对气刀吹锌过程进行数值模拟,分析影响镀层厚度精度的主要因素,建立镀层厚度自动控制系统的核心模型,提出气刀压力前馈控制和Smith预估补偿反馈控制方法,采用LABVIEW软件开发镀层厚度控制系统,实现镀层厚度精确控制。生产数据结果表明,控制系统的应用降低镀层厚度偏差,取得了较好的控制效果。通过镀层厚度自动控制系统的投入运行,不仅满足企业提高产品表面质量的需求,而且对节约成本、降低镀锌原料消耗具有重要意义。     

In-flight particle characterization and coating formation under low pressure plasma spray condition

Yttria-stabilized zirconia( YSZ) coatings were deposited by low pressure plasma spray( LPPS) in 1.0× 10~4 Pa,1.5 × 10~4 Pa,and 2.5 × 10~4 Pa. Both in-flight particle diagnostic detected by DPV-2000 system and ANSYS-FLUENT software were used to study the connection between the parameters of flying particles and the coating formation,which might help to recognize the relationship between the operation parameters and the coatings quality. The results of simulation showed that particles in a lower spray pressure could achieve a higher velocity. The particle velocity was around 380 m/s at a distance of 35 cm from the nozzle at 1.0 × 10~4 Pa while only 300 m/s at 2.5 × 10~4 Pa in actual measurement.The results showed that the velocity of particles increased with decreasing the spray pressure,which might enhance the flattening rate of coatings and thereby decreased the porosity. The deposited YSZ coating with the lowest porosity can be gained under 1.0 × 10~4 Pa condition.     

武钢一冷轧HC可逆式轧机厚度控制系统分析

厚度精度是冷轧带钢最重要的质量指标之一,为实现对冷轧带钢厚度的自动控制,HC可逆式轧机引入了厚度控制系统,通过多种AGC方式的综合运用,提高了尺寸精度的命中率。本文介绍了武钢HC可逆式轧机厚度控制系统的工作原理和应用效果。     

不粘锅纳米涂层的剖面解析

不粘锅广泛应用于人们日常烹饪中,其耐用性和安全性与人体健康息息相关。不粘锅的使用性能主要取决于表面涂层质量,目前常规涂层测试手段并不能分析涂层的成分和构造,从而难以精确评价涂层的使用性能。实验用剖面金相、波谱和能谱成分分析等技术方法解析了不同厂家纳米锅的涂层。首先用波谱仪分析了涂层表面的成分,然后用剖面金相分析了涂层的构造,结果表明,不同品牌不粘锅的涂层均由外层有机物和内层无机物组成,其中外层有机物均为聚四氟乙烯,厚度约14~30μm,不同品牌锅的内层无机物成分和厚度差异很大,成分为类金刚石或纳米氧化铝颗粒和硅颗粒的混合物,厚度分布在12~100μm之间。不同涂层的差异直接导致涂层表现出不同的硬度和附着牢固性能。实验方法可以分析涂层的构造、缺陷状况、厚度等,进而评定涂层的质量状况,弥补现有标准中规定的实验方法的不足。     

The quality of impressions for crowns and bridges received at commercial dental laboratories

OBJECTIVE: To determine the quality of impressions for crown and bridge work made in general dental practice. DESIGN AND SETTING: All impressions for crown and bridge work which had been sent to four commercial dental laboratories in the UK were assessed by two examiners, each laboratory being visited on two occasions. MATERIALS AND METHODS: 290 cases which had been received by the laboratories on the days of the visits were assessed for a number of factors related to quality. There was no selection or rejection--all impressions received were examined. RESULTS: Flexible plastic trays were used for the majority of working impressions for crown and bridge work in general dental practice (72%), many had been re-used (> 13%), defects in the recording of the prepared teeth were common, and cross infection control was not routine. CONCLUSIONS: Quality standards for impressions for crown and bridge work in general dental practice in the UK are a cause for concern if the sample of cases seen in this study is typical.     

System for In-Service Strain Monitoring of Ordinary Bridges

An in-service bridge monitoring system (ISBMS) has been developed to provide near real-time web-based monitoring of live load strains in a bridge. The monitoring system is small, battery operated, can be rapidly deployed, and is programmed and interrogated via a user-friendly web interface. The ISBMS has been designed to be portable and used on an “as-needed” basis as a diagnostic tool or for health monitoring of ordinary bridges. The system is based on a small single-board computer with analog inputs; it also includes a cellular digital packet data modem for communication via the existing cellular network. Strains are measured using either a full bridge strain transducer or a quarter bridge foil strain gauge. The system has three modes of operation; The peaks program records peak live load strains that exceed a specified threshold, the time history program captures dynamic waveforms that exceed a specified threshold, and the rainflow program counts varying amplitude strain cycles. The selection and setup of the program, and retrieval of data is handled through a custom designed web interface. The system has been tested in the laboratory and in the field on a heavily traveled steel girder bridge. The data obtained from the ISBMS can be used for load rating using site specific data, fatigue investigations, monitoring bridge performance under permit loads, and as part of the biannual inspection of ordinary bridge.     

AASHTO-LRFD Live Load Distribution for Beam-and-Slab Bridges: Limitations and Applicability

This paper presents a comparison between the live load distribution factors of simple span slab-on-girders concrete bridges based on the current AASHTO-LRFD and finite-element analysis. In this comparison, the range of applicability limits specified by the current AASHTO-LRFD is fully covered and investigated in terms of span length, slab thickness, girder spacing and longitudinal stiffness. All the AASHTO-PCI concrete girders (Types I–VI) are considered to cover the complete range of longitudinal stiffness specified in the AASHTO-LRFD. Several finite-elements linear elastic models were investigated to obtain the most accurate method to represent the bridge superstructure. The bridge deck was modeled as four-node quadrilateral shell elements, whereas the girders were modeled using two-node space frame elements. The live load used in the analysis is the vehicular load plus the standard lane load as specified by AASHTO-LRFD. The live load is positioned at the longitudinal location that produced the extreme effect, and then it is moved transversely across the bridge width in order to investigate all possibilities of one-lane, two-lane and three-lane design loads. A total of 886 bridge superstructure models were built and analyzed using the computer program SAP2000 to perform this comparison. The results of this study are presented in terms of figures to be practically useful to bridge engineers. This study showed that the AASHTO-LRFD may significantly overestimate the live load distribution factors compared to the finite-element analysis.     

High Performance Steel: Research Front—Historical Account of Research Activities

This paper provides a summary of the major research studies conducted or being conducted in the U.S., to address design issues related to use of high performance steel (HPS) in bridge construction. Emphasis of the paper is on the work related to HPS-485W steel, which has specified minimum yield strength of 485 MPa (70 ksi). Design issues that are addressed in this paper include (1) flexural capacity of compact and noncompact HPS sections in negative bending; (2) issues related to ductility of HPS composite girders in the positive sections (this section presents a simplified ductility check for composite plate girders); (3) tensile ductility of HPS plates; (4) shear capacity of the hybrid steel plate girders; (5) live load deflections; and (6) brief overview of the work that is underway to develop innovative bridge configurations capable of incorporating the advantages of HPS.