Effects of modeling means on properties of monitoring models o spot welding quality

Analyzing and modeling the relation between monitoring information during welding and quality information of the joints is the foundation of monitoring resistance spot welding quality.According to the means of modeling,the known models can be divided into three large categories:single linear regression models,multiple linear regression models and multiple nonlinear models.By modeling the relations between dynamic resistance information and welding quality parameters with different means,this paper analyzes effects of modeling means on performances of monitoring models of resistance spot welding quality. From the test results,the following conclustons can be drawn:By comparison with two other kinds of models,artificial neural network(ANN) model can describe non-linear and high coupling relationship between monitoring information and quality information more reasonably,improve performance of monitoring model remarkably,and make the estimated values of welding quality parameters more accurate and reliable.     

Effects of modeling means on properties of monitoring models of spot welding quality

Analyzing and modeling the relation between monitoring information during welding and quality information of the joints is the foundation of monitoring resistance spot welding quality. According to the means of modeling, the known models can be divided into three large categories: single linear regression models, multiple linear regression models and multiple non-linear models. By modeling the relations between dynamic resistance information and welding quality parameters with different means, this paper analyzes effects of modeling means on performances of monitoring models of resistance spot welding quality. From the test results, the following conclusions can be drawn: By comparison with two other kinds of models, artificial neural network (ANN) model can describe non-linear and high coupling relationship between monitoring information and quality information more reasonably, improve performance of monitoring model remarkably, and make the estimated values of welding quality parameters more accurate and reliable.     

镁合金电阻点焊接头断裂行为的有限元分析

综合考虑熔核尺寸、工件翘曲变形、电极压痕等因素建立了三维弹塑性有限元模型,分析了镁合金电阻点焊接头的应力、应变场分布特点,以揭示焊点断裂产生的原因.结果显示,由于电阻点焊接头在受力时熔核是主要的承栽部位,在熔核边缘与板缝结合处由于几何非线性和材料的非线性将出现应力集中,这是点焊接头受力时最薄弱的环节,裂纹从这里萌生,沿熔核边缘高应力区扩展.镁合金点焊接头断裂均为沿焊点熔核的纽扣形撕裂,断裂属于韧性断裂.     

汽车焊装车间信息管理数据库的构建

在充分了解汽车焊装车间手工焊生产线工艺流程和特点的基础上,设计了生产过程信息管理系统的总体结构,确定了系统数据的模型和相互之间的关系.利用图形化编程语言LabView作为开发工具,开发了信息管理系统的操作界面,采用ODBC技术实现了操作界面与数据库之间的无缝链接.本系统的开发与实现能够提高企业的生产效率和产品质量,同时...     

基于回归分析理论的点焊质量监测模型

以动态电阻与接头质量参数之间关系为例,用线性回归分析技术,系统地研究了点焊加热过程中的监测信息与点焊接头质量参数之间的一元和多元回归模型关系。结果表明：（1）各种回归模型总体线性关系经统计检验均为高显著,可以用于点焊接头质量监测;（2）一元回归模型的决定系数仅为0．15－0．33,多元回归模型的决定系数则可以提高到0．59－0．79,说明发展多参量综合监测技术是提高点焊质量监控精度的有效途径;（3）点焊过程监测信息与质量参数之间关系也含有较大的非线性,用线性模型去描述这样的关系导致模型误差的增加。     

Effect of welding current on strength and microstructure in resistance spot welding of AZ31 Mg alloy

In this paper, resistance spot welding were performed on lmm-thickness magnesium AZ31B plates. The effect of welding current on the microstructure and tensile shear force was investigated. It was found that the welding current governed the nugget growth, and the nugget could not form if current levels were insufficient. The nugget revealed a homogeneous, equiaxed, fine-grained structure, which consisted of non-equilibrium microstructure of α-phase dendrites surrounded by eutectic mixtures of α and β（ Mg17All2 ） in the grain boundaries. With increasing welding current, the size of grains in nugget would be more smaller and uniform, and the width of plastic rings would be larger. Tensile shear tests showed that tensile shear force of the joints increased with increasing welding current when the welding current was smaller than 17 000 A. The maximum tensile shear force was up to 1980 N.     

大规格电工触头柔性感应加热电源的设计

由于具有加热效率高、速度快、可控性好及易于实现自动化等众多优点,电磁感应加热已在低压电器大规格触头焊接行业得到了广泛的应用。但是目前国内生产使用的大规格触头感应加热电源大多采用连续加热模式,控制模式不够灵活,电流、功率靠电位器手动调节,时间控制只能精确到秒,电流和频率在加热过程中波动比较大,触头加热效果的可控性及重复性极差,焊接质量无法得到保证,不能满足自动化生产要求。针对目前存在的问题,设计了一种柔性感应加热电源,核心部分采用双32位单片机架构的控制器,电流和时间输出精度更高,能量输出可通过修改单片机程序任意调整,加热模式更加灵活。     

转镜参数对送粉式激光熔覆工艺过程的影响

从理论上分析了激光熔覆光源的形成原理及转镜参数对光源能量分布的影响 ,结果表明 ,在其它条件不变的情况下 ,随着转镜棱数m增加 ,激光熔覆光源长度减小 ;而转镜转速n越高 ,激光熔覆光源的能量分布越均匀。通过对不同转速条件下获得试样的金相组织、熔覆层尺寸和熔覆层硬度的分析测试 ,试验结果表明 ,熔覆层不同区域的组织形态随转镜转速的变化均有所变化 ;熔覆层宽度和厚度随转镜转速的增加而增大 ;熔覆层硬度随转镜转速的增加虽略有下降 ,但影响不大。     

建立点焊质量神经网络监测模型时作用函数的选取

多层前向神经网络是最常用,最流行的神经网络模型,其逼近能力和训练算法是其应用的关键。误差反传算法（BP）以诸多的优点而成为多层前向神经网络训练的首选算法,但却存在收敛速度慢的缺点,研究发现,“假饱和”是导致BP算法收敛缓慢的主要原因之一,也是减少点焊质量监测模型误差的主要障碍,为了减少BP算法学习过程中出现“假饱和”的可能性,加快学习速度,提出了选取神经元作用函数类型的原则。     

铝表面磨擦焊镀工艺

通过在铝表面磨擦焊镀锌基稀土焊丝试验,分析了摩擦焊镀技术的摩擦加热过程及焊镀机理;研究了规范参数对摩擦焊镀过程的影响,焊镀层与基体的结合机理及焊镀层的性能特点。试验结果表明：(1)规范参数不仅影响摩擦焊镀过程,而且影响焊镀层尺寸;(2)焊镀层与基体之间为冶金结合;(3)只要选择合适的规范参数,不仅可以获得均匀、牢固的焊镀层,而且可以明显提高材料的表面强度。