Optimisation of submerged arc welding process parameters in hardfacing

In this paper, a feedforward neural network is used to model submerged arc welding (SAW) processes in hardfacing. The relationships between process parameters (arc current, arc voltage, welding speed, electrode protrusion, and preheat temperature) and welding performance (deposition rate, hardness, and dilution) are established, based on the neural network. A simulated annealing (SA) optimisation algorithm with a performance index is then applied to the neural network for searching the optimal process parameters. Experimental results have shown that welding performance can be enhanced by using this new approach.     

Design of experiment based statistical approaches to optimize submerged arc welding process parameters

Joining of metals is very useful concept which is being utilized since Bronze Age and then gradual advancement gave rise to development of modern welding. And now welding is increasingly used in the fields of fabrication, manufacturing and construction. But productivity is the main concern in many manufacturing and industrial welding applications. Therefore selection of a welding process and its variables/parameters without sacrificing weld quality with respect to productivity and its quality is very important because an optimum blend of parameters which inevitably develop minimum or no defect will result in high productivity. For this study Submerge Arc Welding (SAW) process is selected for optimization because this versatile welding process is the first choice whenever good productivity with high quality requires in fabrication and manufacturing of Marine & pressure vessels, pipelines and offshore structures. Here Signal to noise (S/N) ratio analyses are used to find significant effects of key parameters on selected responses and then for optimization design of experiment based both quality loss function (OFM) and desirability function along with variance analyses by ANOVA are utilized. Moreover codes and standards provide a range for weld process parameters but author experienced that still there is a window to further optimize these parameters to produce the quality weld. Therefore this study is also useful to contribute in welding related research work by enhancing the knowledge of welding process and its analysis by utilizing advance statistical optimization techniques to find optimum zone within the acceptable zone from Code & Standard based tolerance Zone.     

浅谈MAG焊和埋弧焊在箱式井架的应用

从箱式井架的结构形状和焊缝接头形式出发,针对MAG焊和埋弧焊的特点进行了论述,生产结果证明,通过两种优质、高效方法的运用,使焊接质量得到了保障,生产效率得到很大提高.     

气体保护焊烟尘发尘量的测量与成分分析

为了测量与分析气体保护焊焊接烟尘发尘量,根据JIS标准,设计了焊接烟尘采集装置,并对实心焊丝的熔化极气体保护焊和药芯焊丝的CO2焊的烟尘发尘量进行测量试验,分析了工艺方法与焊接参数对焊接烟尘发尘量的影响。采用Philips X30型环境扫描电子显微镜分析焊接烟尘化学成分。试验表明,在不同焊接方法和熔滴过渡方式下的烟尘发尘量和成分具有不同的特点。     

一种模拟控制式埋弧焊设备的数字化升级改造设计

该文设计了一套基于STM32的双单片机控制系统对模拟控制式埋弧焊设备进行数字化改造。该系统包括电源控制系统和过程控制系统,2个系统之间采用串行异步通信方式,实现命令和参数交换。可以实现焊接电源多种外特性输出,满足埋弧焊、焊条电弧焊、气体保护焊、碳弧气刨工艺需要。设计双闭环控制系统对送丝速度进行调节,设计单闭环控制对小车驱动电机进行控制。测试表明,改造后的焊机用途拓宽,人机界面丰富,引弧、焊接、收弧的稳定性和可靠性均大幅提升,具有很好的实用价值。     

基于旋转电弧轮式焊接机器人运动学建模及仿真

旋转电弧轮式焊接机器人的焊炬执行机构由十字滑块和小车左右差速驱动轮两个运动单元构成。针对其机构设计的稳定性以及可控性等问题,根据运动特点推导出焊炬的运动学模型,由旋转电弧焊缝跟踪原理应用Matlab/Simulink进行焊缝跟踪仿真,实现了机构设计以及控制方法对焊缝跟踪的影响。仿真结果证明了该模型的有效性和正确性,为旋转电弧移焊接机器人的机构设计、稳定性分析以及控制器设计提供了理论依据。     

Modeling and estimating for external characteristic of welding power source

A mathematical modeling method, theory and process based on measured data from the dropping external characteristic of a thyristor rectifier for arc welding power source have been introduced in this paper. The instance shows the model structure obtained with this method is simple and it can accurately denote the U–I characteristic for welding power. This model can also predict the self-adjusting performance of electric current and short circuit current parameters on different given conditions. This method can not only handle the post-process problem in measuring data, but it can make the limited measuring message be a more effective application.     

An arc stability evaluation approach for SW AC SAW based on Lyapunov exponent of welding current

Based on the experimental non-linear time series of welding current produced by Square Wave Alternating Current Submerged Arc Welding (SW AC SAW) at different frequency and duty cycle, the largest Lyapunov exponents of the welding system are numerically evaluated by the phase space reconstruction technique and the improved small-data method algorithm. The experimental and calculated results show that the largest Lyapunov exponent can describe the arc stability as a quantitative indicators at the process of Square Wave AC SAW. Further analysis proves that when the duty cycle of welding current is 0.5, the largest Lyapunov exponent reaches small values and the welding processes approach high steady states. When the welding current frequency is larger, the largest Lyapunov exponent reaches small values and the welding processes approach high steady states. When the welding current frequency is smaller, the system is at the unsteady mode and the largest Lyapunov exponent attains large values. Therefore, the welding current frequency is negatively correlated with the welding process stability.     

Fractal modeling method for 3D structure of vitrified-bonded wheel

Our goal is the development of the morphological model faithfully representing the structure of a real vitrified-bonded wheel in order to determine the wheel structure to meet a required wheel grade and derive the wheel composition to form such a wheel structure. This paper describes the two and new morphological model for a vitrified-bonded wheel using fractal modeling techniques. One model is the “agglomerate model of a plastic mixture” representing a plastic mixture before the burning process of a wheel on the basis of the diffusion-limited aggregation algorithm and another is the “morphological model of a burnt wheel” representing the structure of the burnt wheel on the basis of the sandpile algorithm. Both models bear resemblances to the real productions in structure. In particular, the morphological model of a burnt wheel bears resemblances not only in morphology but also in bulk density to real wheel structure, and it provides the structural characteristics such as average grain spacing and number of bond bridges per grain that relate to the tensile strength of wheels. Therefore, our models play an important role in the development of new wheels.     

A fuzzy-neural approach for estimating the monthly output of a semiconductor manufacturing factory

The customer order scheduling problem (COSP) is defined as to determine the sequence of tasks to satisfy the demand of customers who order several types of products produced on a single machine. A setup is required whenever a product type is launched. The objective of the scheduling problem is to minimize the average customer order flow time. Since the customer order scheduling problem is known to be strongly NP-hard, we solve it using four major metaheuristics and compare the performance of these heuristics, namely, simulated annealing, genetic algorithms, tabu search, and ant colony optimization. These are selected to represent various characteristics of metaheuristics: nature-inspired vs. artificially created, population-based vs. local search, etc. A set of problems is generated to compare the solution quality and computational efforts of these heuristics. Results of the experimentation show that tabu search and ant colony perform better for large problems whereas simulated annealing performs best in small-size problems. Some conclusions are also drawn on the interactions between various problem parameters and the performance of the heuristics.     

Half-transient liquid phase diffusion welding: An approach for diffusion welding of SiCp/A356 with Cu interlayer

Aluminum matrix composite SiC_p/A356 was welded by half-transient liquid Phase diffusion welding (HTLPDW) with a Cu interlayer. The effects of welding parameters and interlayer thickness on the properties of the welded joint were investigated, and the optimal welding parameters were subsequently put forward. The relationship between the tensile strength of the joint and the microstructure was studied by analyzing the microstructure of joint using a scanning electron microscope (SEM) and an electron probe micro-analysis (EPMA). Results confirmed the success of welding aluminum matrix composite SiC_p/A356 utilizing HTLPDW method with a Cu interlayer. Shorter welding time was a prominent characteristic of HTLPDW as compared with conventional transient liquid phase (TLP) diffusion welding. Furthermore, its welded joints had a tensile strength almost 72% of its parent matrix composites, evidently signifying the suitable application of half-transient liquid phase diffusion welding in welding composite engineering structures.     

A modeling approach for designing a value chain of virtual enterprise

As the advent of digital economy changes business environment dramatically, virtual enterprise (VE), in general the interactions among business partners in a value chain, has become a key factor to survive under the competitive business environment. VE reveals that more complex and dynamic business processes should be considered as assembled service components in order to integrate the collaborative business processes. Therefore, a formal standard schema for describing and managing the business processes is required. In this paper, we propose a consistent modeling approach that combines enterprise modeling and simulation modeling to design a value chain of a VE. This methodology will provide designers with insight into the business processes of a VE and help identify and resolve unpredictable bottlenecks on the execution of virtual business processes. This paper also illustrates an implemented modeling tool which is based on the generalized model suggested by the working group of the international conference on enterprise integration and modeling technology (ICEIMT) and notations by the object management group (OMG)’s unified modeling language (UML) profile for enterprise distributed object computing (EDOC).     

A network approach for modeling and design of agile supply chains using a flexibility construct

Agility can be viewed as a need to encourage the enterprise-wide integration of flexible and core competent resources so as to offer value-added product and services in a volatile competitive environment. Since flexibility is considered a property that provides change capabilities of different enterprise-wide resources and processes in time and cost dimensions, supply chain flexibility can be considered a composite state to enterprise-wide resources to meet agility needs. Enterprise modeling frameworks depicting these composite flexibility states are difficult to model because of the complex and tacit interrelationship among system parameters and also because agility thrives on many business objectives. In view of this, the modeling framework presented in this paper is based on analytical network process (ANP) since this methodology can accommodate the complex and tacit interrelationship among factors affecting enterprise agility. The modeling framework forms a three-level network with the goal of attaining agility from the perspective of market, product, and customer as the actors. The goal depends on substrategies that address the characteristics of the three actors. Each of these substrategies further depends on manufacturing, logistic, sourcing, and information technology (IT) flexibility elements of the enterprise supply chain (SC). The research highlights that, under different environmental conditions, enterprises require synergy among appropriate supply chain flexibilities for practising agility. In the present research, the ANP modeling software tool Super Decisions™ has been used for relative prioritization of the supply chain flexibilities. We demonstrate through sensitivity analysis that dynamic conditions do require adjustments in the enterprise-wide flexibility spectrum.