基于合成规则的相似性推理及其在焊接参数设计中的应用

焊接过程是典型的复杂过程,应用模糊逻辑建立焊接参数推理系统可快速实现焊接工艺参数设计.近似推理机制是模糊系统研究和开发中的一个重要组成部分,在现有的相似性推理方法的基础上,融合经典的合成规则推理技术,提出一种新的基于合成规则的相似性推理方法.以CO_2保护焊焊接规范参数设计为背景介绍模糊推理在焊接领域的应用,运行结果表明,采用方法建立的模糊推理模型具有较高的推算精度,能够满足焊接工艺参数设计的要求.     

机器人焊缝中心三维定位的解析方法

机器人焊接过程中焊缝三维空间中心位置的确定是焊缝自动跟踪系统重要的一环.由于多数焊缝为直线,且实际的焊缝在小范围内可近似为直线,因而特征点的空间坐标确定以后如何确定直线是问题的关键所在.在焊缝特征点确定以后,根据空间解析几何的定位原理,结合最小二乘法,首先给出了焊缝中心线的确定原则,其次,按直线的点向式方程,利用焊缝特征点的全息,给出了中心直线的点和方向向量确定的解析方法.     

机器人圆形焊缝三维定位方法

自动化寻迹焊接过程中有许多焊缝为圆形,在焊缝特征点的坐标确定以后如何确定圆形焊缝的中心轨迹线是至关重要的.利用空间解析几何的原理,结合最小二乘法,既利用焊缝的已知信息又利用了实时监测点的信息,给出了圆形焊缝三维空间中心位置的确定方法.实验表明,该方法具有较高的精度和较强的实用性.     

利用回归分析对正交试验结果进行修正

本文以纱线上浆率工艺参数正交试验为实例 ,利用回归分析的方法加以验证和修正 ,使工艺参数更符合实际情况 ,说明两种方法有较好的互补性 .     

用正交试验方法优化IC工艺条件

本文用正交试验方法，对某种汽国专用ＩＣ工艺进行试验，找到良好的工艺条件．在做重复性试验之后，用单因素方差分析方法，找到最佳工艺条件．并从理论上分析器件参数随工艺条件变化的规律．使该电路在大批量生产过程中，成品率提高３０％以上，产生了较大的经济效益．     

利用回归分析对正交试验结果进行修正

本以纱线上浆率工艺参数正交试验为实例，利用回归分析的方法加验证和修正，使工艺参数更符合实际情况，说明两种方法有效较好的互补性。     

正交试验设计法在配制磷化液中的应用

本文运用正交试验设计法 ,在配制磷化液时选定各工艺参数 ,保证了磷化质量 ,而且生产成本较低 ,具有实用、高效、经济等特点     

运用正交试验优选细纱机的工艺参数

细纱是纺部的最后产品.造成细纱条干不匀的原因很多,除了原材料(粗纱)的质量外,细纱机各部位的工艺参数也起很大作用.要降低细纱的条干不匀率,除了改善粗纱的质量外,优化细纱机的各个工艺参数也是不可忽视的途径.细纱机的工艺参数很多,如钳口隔距、罗拉隔距、皮辊直径和位置、皮辊压力、牵伸倍数等都可能对细纱的条干不匀率有影响.至于哪些工艺参数的影响是重要的,哪些是不重要的,过去没有明确的结论.我们试图通过正交试验来探索这个问题的答案,并对纺32支针织用纱的主要工艺参数进行优化.实践经验表明:细纱的中长片断不匀和部分长片断不匀…     

浆纱工艺的优化和控制

应用微机现场检测、显示、采集浆纱生产过程工艺参数，采用ＳＮ比正交试验优化浆纱工艺，并对最佳工艺实施控制和生产工序进行科学管理，从而提高布机织造质量和效率，取得显著经济效益。     

K型管状接头随机疲劳强度和裂纹扩展规律的研究

分析了K型焊接管状接头受轴向和面外弯曲载荷作用下的随机疲劳问题,通过将焊趾处的表面裂纹的初始尺寸和材料常数作为随机变量处理,并计及焊缝的影响,共产生500个随机样本,最终得到裂纹扩展寿命和裂纹形状变化影响的统计计算结果,并与有关实验数据比较,给予了回归分析,同时,也考察了裂纹扩展规律。     

Scheduling for an arc-welding robot considering heat-caused distortion

This paper focuses on an arc-welding robot scheduling problem, which is the problem of determining the sequence of welding operations while avoiding heat-caused distortion for the objective of minimizing the time required to complete a given set of welding operations. Each welding operation is specified by a weld line with two end points, each of which can be a possible starting point of the welding operation for that weld line. Because of the heat-caused distortion, there must be a certain period of time (delay) between welding operations associated with weld lines near each other. We develop several heuristic algorithms, in which heuristics for the travelling salesman problem are modified to cope with characteristics of the problem considered here. To show the performance of the heuristics suggested in this paper, computational experiments are performed on a number of randomly generated test problems and results are reported.     

Some characteristics of the failure of heat-sealed polyethylene film

It is shown that weld failure most often occurs in the inner weld zone. The mode of failure and deformation of the weld in uniaxial tension depends on the welding conditions. For severe welding conditions the _t-T curve has a certain maximum.Institute of Physicotechnical Problems of Power Engineering, Academy of Sciences of the Lithuanian SSR, Kaunas, Kaunas Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 537–538, May–June, 1971.     

Numerical and experimental study of mitigation of welding distortion

Welding stresses and deformations are closely related phenomena. During the heating and cooling cycles thermal strains may occur in the weld and adjacent area. The strains produced during the heating stage of welding are always accompanied by plastic deformation of the metal. The stresses resulting from these strains combine and react to produce internal forces that cause a variety of welding distortions. Welding deformation needs to be minimized and also the designer should know before hand the extent of deformation so that it can be accounted for in the design as well as in the construction stages.In this paper, heat sinking as a method of distortion mitigation has been studied. Heat sinking has been affected by circulating water through channel clamped at the bottom surface of the plates undergoing welding. The pseudolinear equivalent constant rigidity concept has been used in this investigation for thermo-mechanical analysis of plates undergoing welding with simultaneous heat sinking. The initial nonlinear problem with varying modulus dependent on temperature is transformed into a pseudolinear equivalent system of constant rigidity that is solved by linear analysis.The numerical results compared very well with those of the experimental ones. The proposed concept is found to be computationally more efficient and simpler to model compared to FEM for solving similar thermo-elasto-plastic nonlinear problems. The procedure presented in this work and the results thus obtained, holds a great promise for determining the heat sinking parameters for effectively controlling welding distortion.     

Multi response simulation and optimization of gas tungsten arc welding

In the fabrication of a pressure vessel, the successful bending operation (after welding) demands higher tensile strength of weld bead. Therefore, to achieve typical tensile strength and hardness is the primary objective of this paper. Stainless steel 304 is widely used material in almost all the industrial applications, hence it is selected as a candidate material for study of tungsten inert gas (TIG) welding process. In order to produce, a high quality and reliable welding, the welding process needs to be robust in performance. A recently developed popular experimental approach known as definitive screening design (DSD) is used for process improvement. These optimum variable settings necessary for consistent welding are obtained through the application of simulation by using central composite design. The typical values of tensile strength and hardness are obtained at a low value of purging gas flow rate, filler rod dia.; intermediate values of root gap, plate thickness; and at high values of electrode dia., current, and gas flow rate.     

Micro-mechanical analysis of creep behavior in a multipass weld

A method of evaluating creep response of the multipass weld based on the micro-macro mechanics approach is introduced. Multipass weld microstructure that consists from columnar, coarse and fine grained zones is considered. Materials of these constituents assumed to be isotropic. Weld metal properties of inelastic behavior have general type of symmetry and are described by the anisotropic creep constitutive model. To model the microstructure of the multipass weld metal the representative volume element (RVE) is created for CAE Abaqus. Material properties of weld metal grain type zones are taken from the experiments. Numerical tests on uniform loading of the RVE are performed. Creep material properties for equivalent weld material are found for welds with different number of passes. The symmetry type of the creep material properties of multi-pass weld are evaluated for the equivalent weld material. As an example of macro model analysis of the welding, the creep calculation of the cylindrical shell with the welding under the uniform inner pressure is performed. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A desktop computer model of the arc,weld pool and workpiece in metal inert gas welding

A sophisticated computational model of metal inert gas arc welding of aluminium alloys is presented. The arc plasma, the wire electrode and the workpiece are included in the computational domain self-consistently. The flow in the arc plasma and in the weld pool are calculated in three dimensions using equations of computational fluid dynamics, modified to take into account plasma effects and coupled to electromagnetic equations. The formation of metal vapour from the wire electrode and workpiece is considered, as is the mixing of the wire electrode alloy with the workpiece alloy in the weld pool. A graphical user interface (GUI) has been developed, and the model runs on standard desktop or laptop computers.The computational model is described, and results are presented for lap-fillet weld geometry. The importance of including the arc in the computational domain is shown. The predictions of the model show good agreement with measurements of weld geometry and weld composition. The GUI is introduced, and the application of the model to predicting the thermal history of the workpiece, which is the input information that is required for predicting important weld properties such as residual stress and distortion and weld microstructure, is discussed. Initial predictions of residual stress and distortion of the workpiece are presented.     

Modeling of MIG/MAG welding with experimental validation using an active contour algorithm applied on high speed movies

This paper investigates some issues in physical modeling of metal inert gas/metal active gas (MIG/MAG) welding process in the short arc mode. In this mode, a metal supply is molten in the arc state and then transferred to the weld pool during the short-circuit state. A hybrid model having two distinct continuous states whose switchings are controlled by two guard conditions is proposed. Due to the complexity of the physical phenomena involved in the welding process, simplifications are used to obtain a model accounting for the main physical contributions but simple enough to yield an efficient, fast and numerically tractable simulator which can be used intensively for evaluating different control strategies. In an attempt to validate the proposed model, different measurements have been made including supply voltage and current sampled synchronously with high speed digital video. In order to extract some relevant quantities representative of the metal transfer from image sequences, an active contour algorithm is developed and tested. The effectiveness of the proposed model in the prediction of major tendencies of a welding process, especially in the arc state, is shown using experimental data. Some limitations of the model during the metal transfer are also stressed and possible remedies are then proposed.     

A shape optimization formulation of weld pool determination

In this paper, we propose a shape optimization formulation for a problem modeling a process of welding. We show the existence of an optimal solution. The finite element method is used for the discretization of the problem. The discrete problem is solved by an identification technique using a parameterization of the weld pool by Bézier curves and Genetic algorithms.