No description available.

<p>Welded built-up structural steel members are widely used as columns, beams, and beam-columns in various buildings, bridges, industrial complexes, etc. Modern cutting techniques are used in the fabrication of such members. Besides traditional saw cutting and oxy-flame cutting, the modern cutting techniques include plasma cutting, laser cutting, water- jet cutting, etc. The different cutting techniques induce different degrees of Heat Affected Zones (HAZ), which subsequently creates different degrees of geometrical and mechanical imperfections (residual stresses). Therefore, it could be expected that the true behavior of structural steel columns manufactured by such cutting techniques be different.</p><p>The main objective of this investigation was to study the characteristics and behavior of plasma cut-welded H-shaped steel columns at different slenderness ratios. However, this investigation also considered similar flame cut-welded H-shaped steel columns for comparison purposes. The H-shaped column sections were fabricated from plates having specified yield strength of 350MPa. First, the initial plate was cut into plate strips and then the plate strips (flanges and web) were welded together to form the H-shaped section in this investigation. The strength of these columns were established under uni-axial compressive loading with pinned end condition, allowing for minor axis rotation. Moreover, the structural imperfections such as residual stresses and geometrical imperfections were established. The residual stresses distributions were established at various stages of fabrication processes using the "method of section" technique. That is, the residual stresses in initial plate, plate strips (cutting effects), and column sections (cutting and welding effects) were established. Similarly, the geometrical imperfections were established at various stages of fabrication processes in this investigation.The temperature profiles were measured during the cutting and welding processes. As part of the scientific documentation, the mechanical characteristic of virgin steel plates were obtained by standard coupon tensile test.</p><p>Based on the experimental results on column strength, the general behavior of plasma cut columns and flame cut columns were similar. However, it was found that the plasma cut-welded steel columns seemed to carry higher loads than that of flame cut-welded columns for higher slenderness ratios( λ≥1). For lower slenderness ratios (0.5<λ<1), it was found that the flame cut-welded columns had higher strength than plasma cut-welded columns in this investigation. The residual stress distribution of both plasma cut column section and flame cut column section had the same general distribution. However, in general, the flame cut columns had high intensity of tensile residual stresses at their flange tips than the plasma cut columns. Moreover, the out-of-plane imperfections of column sections were within the code limitations. However, it was found that the flame cut-welded H-shaped steel columns seemed to have higher out-of-plane imperfections than the similar plasma cut-welded H-shaped steel columns in this investigation.</p> / Thesis / Master of Applied Science (MASc)

FNsteel i Linköping tillverkar spännlina, en produkt som används av prefab-industrin för tillverkning av förspända betongelement t.ex. håldäck, balkar, bjälklag och järnvägsslipers. Vid tillverkningen drar man valstråd i tråddragningsmaskiner som reducerar valstrådens tvärsnittsarea och ökar längden samtidigt som tråden får en annan metallstruktur. Den dragna tråden slås sedan till tre- eller sjutrådig spännlina. Vid tillverkningen svetsar operatörer ihop valstrådar och hanteringen av valstråden är idag manuell. Företaget vill i framtiden automatisera sin svetsprocess vid skarvning utav valstrådar då det är ett tungt och ensidigt arbete för operatörerna samt för att kunna öka produktiviteten. Examensarbetet är ett produktutvecklingsprojekt som innehåller en analys utav tillverkningen idag och förslag på standardisering för att kunna automatisera samt konstruktionsunderlag för automatisering av vissa moment i processen. Under arbetets gång har det identifierats att processen inte är mogen för att automatiseras utan att företaget först behöver ta fram en standard för hur processen ska se ut för att kunna möjliggöra en automatisering av hela svetsprocessen. Ett antal moment i processen kräver fortsatt arbete för att möjliggöra automatiseringen av processen, samtidigt som det redan idag är möjligt att automatisera vissa delar av processen då dessa enkelt kan standardiseras. Konceptlösningen som tagits fram består av pneumatiska cylindrar, konstruerade trådklämmor och hydraulisk trådklippare. / FNsteel in Linköping manufactures wire rod, a product used by the prefabricated industry for the manufacture of prestressed concrete elements eg. hollow cores, beams, beam joints and railroad slides. In manufacturing, a wire is drawn through a wire drawing machine that reduces the wires cross sectional area and increase the length while the wire is given a different metal structure. The drawn wire is then turned to three or seven-wire wire rod. In manufacturing, operators weld together wire threads and the handling of the wire is today manual. In the future, the company wants to automate its welding process by splicing of wire threads as there is a heavy and one-sided work for operators, and also in order to increase productivity. The thesis work is a product development project that contains an analysis of the manufacturing process today and suggestions for standardization to automate, as well as design documentation for automation of certain elements of the process. During the course of the process, it has been identified that the process is not mature for automation without the company first having to come up with a standard for the process to enable automation of the entire welding process. A number of elements in the process require continued work to enable automation of the process, while it is already possible to automate certain parts of the process as these can easily be standardized. The conceptual solution developed consists of pneumatic cylinders, engineered wire clips and hydraulic wire cutters.

The diploma thesis is focused on simulation of keyhole creation in laser deep penetration welding and on the effect of welding parameters on the geometry of keyhole (weld). With reference to this issue theories of keyhole creation are described. 2D simulation model that is created in mathematical software Matlab is verified pursuant welding results of non-alloy constructional steel 1. 0122 and stainless steel 1.4301. Effect of welding parameters on the geometry of keyhole and on the quality of weld is investigated through the welds in non-alloy steel 1.0122.

In manual control, the welding gun’s moving speed can significantly influence the welding results and critical welding operations usually require welders to concentrate consistently in order to react rapidly and accurately. However, human welders always have some habitual action which can have some subtle influence the welding process. It takes countless hours to train an experienced human welder. Using vision and IMU sensor will be able to set up a system and allow the worker got more accurate visual feedback like an experienced worker. The problem is that monitor and measuring of the control process not always easy under a complex working environment like welding. In this thesis, a new method is developed that use two different methods to compensate each other to obtain accurate monitoring results. Vision sensor and IMU sensor both developed to obtain the accurate data from the control process in real-time but don’t influence other. Although both vision and IMU sensor has their own limits, they also have their own advantage which can contribute to the measuring system.

This thesis deals with modeling and simulation of production process, which consists of a few stationary robots. This model of production process is made in program Tecnomatix Process Simulate. Principle of digital manufacturing and virtual production is described in the first chapter. The second chapter describes how to work with program Tecnomatix Process Simulate and how to make a design of production process of continuous and spot welding. The controlling program of PLC SIMATIC 300 and the program for process visualization are described in the last chapter.

No description available.

In the industrial sector, next generation technologies are being rapidly developed. One of the promising technologies is cyber-physical systems which are being used to revolutionize the welding process. A cyber-physical system can greatly improve the welding processes by taking over the tasks performed by humans, such as analysis, control and sensing which results in increased efficiency, quality, and stability of the welding process. However, integrating cyber-physical systems in the welding process requires a digital transformation strategy that outlines how organizational and technical challenges are intended to be resolved. The aim of the study is to identify the organizational challenges of integrating cyber-physical systems, and how to overcome them with the use of a digital transformation strategy. For this, the study adopts a qualitative case study approach to investigate the organizational challenges of integrating a cyber-physical system in the welding process of a large manufacturing organization. Further, it outlines aspects required in a digital transformation strategy to succeed with the integration.  The findings indicate that common challenges when integrating cyber-physical systems revolve around building secure networks, securing competencies, committing to the integration, and achieving transparency between management and employees. In addition, when formulating a digital transformation strategy, the findings indicate three factors that contribute to the success of the transformation. These are involvement of critical digital skills, undergoing required structural changes and reengineering organizational work processes where the cyber-physical system aims to be integrated.  Besides providing practical implications for the challenges and formulation of a digital transformation strategy for implementing cyber-physical systems in the welding process, the study contributes to the literature on digital transformation strategy and cyber-physical systems in manufacturing organizations.

Tendo em vista a tendência mundial de se buscar a diminuição de peso de estruturas metálicas de veículos, o desenvolvimento de aços de resistência mecânica superior apresenta-se como um importante fator para a competitividade e sustentabilidade da indústria brasileira, além da segurança do usuário. No setor automobilístico, as reduções no peso e no consumo de combustível requerem não somente a pesquisa de novos aços, mas também a utilização de componentes híbridos, resultantes, entre outros, da união entre os aços austeníticos inovadores de alta liga e baixo custo (TRIP) e aços ferríticos comerciais (ARBL). Na presente dissertação foram investigadas as propriedades mecânicas microestruturais, antes e após o processo de soldagem TIG, dos aços TRIP e ARBL utilizados pela indústria automotiva. O principal objetivo do trabalho foi avaliar possíveis estruturas e modificações nas propriedades das juntas soldadas de acordo com parâmetros de soldagem pré-determinados. Primeiramente, verificaram-se as extensões da zona termicamente afetada dos corpos de prova soldados. Os perfis de microdureza indicaram que não houve uma alteração significativa de dureza na zona termicamente afetada do aço de efeito TRIP, enquanto que para o aço ARBL observa-se um considerável aumento. Os limites de escoamento determinados pelos ensaios de tração realizados permitiram a obtenção dos níveis de resistência mecânica das juntas soldadas. Através dos ensaios de microscopia eletrônica de varredura e microscopia ótica foi possível observar a influência do aporte térmico na zona termicamente afetada do aço ARBL. A análise de EDX nas juntas dissimilares permitiu observar a presença de zonas parcialmente diluídas na zona fundida do lado do metal de base ARBL, a caracterização da composição química nas interfaces entre os metais de base e o metal de solda e prever a microestrutura destas regiões. As fases presentes nos metais de base e na zona fundida foram caracterizadas também pela difração de raios x. Por meio da estereologia quantitativa caracterizou-se as fases presentes na zona fundida e determinou-se suas proporções em função do aporte térmico. / In view of the global trend of searching for the weight reduction of metal frames in vehicles, the development of superior mechanical resistance steels presents itself as an important factor for the competitiveness and sustainability of the Brazilian industry, as well as to user safety. In the automotive industry, the reductions in vehicle weight and fuel consumption not only require research of new types of steel but also the use of hybrid components, which result, amongst other things, between the union of austenitic innovative high alloy and low cost (TRIP) with commercial ferritic steels (HSLA). This dissertation analyses the microstructural mechanical properties before and after the TIG welding process, the TRIP steel, and HSLA used by the automotive industry. The main objective of this study was to evaluate possible phase changes in steel structures and transformation in the properties of the welded joints according to pre-determined welding parameters by analyzing extensions of the heat-affected and melted zones of welded specimens. The micro hardness profiles showed no significant changes in hardness in the heat affected HSLA steel, while the TRIP steel showed considerable increase. Additionally, the yield point determined by the traction tests performed, allowed the obtainment of the mechanical resistance levels of the welded joints. Through the tests of scanning electron and optical microscopy was observed the influence of heat input on heat affected zone of HSLA steel. EDX analysis allowed us to observe the presence of molten zones partially diluted in the side of the base metal HSLA, characterization of the chemical composition at the interface of the base metal and weld metal and predicting the microstructure in these regions. The phases present in the base metal and weld zone were characterized too by x-ray diffraction. By quantitative stereology characterized by the phases present in the weld zone and their proportions were determined as a function of heat input.

Le recours à des simulations numériques pour l’étude de l’influence des paramètres d’entrée (matériaux, chargements, conditions aux limites, géométrie, etc.) sur les différentes quantités d’intérêt en soudage (contraintes résiduelles, distorsion, etc.) s’avère trop long et coûteux vu l’aspect multi-paramétrique de ces simulations. Pour explorer des espaces paramétriques de grandes dimensions, avec des calculs moins coûteux, il parait opportun d’utiliser des approches de réduction de modèle. Dans ce travail, d’une façon a posteriori, une stratégie non-intrusive est développée pour construire les abaques dédiées aux études paramétriques du soudage. Dans une phase offline, une base de données (‘snapshots’) a été pré-calculée avec un choix optimal des paramètres d'entrée donnés par une approche multi-grille (dans l’espace des paramètres). Pour explorer d’autres valeurs de paramètres, une méthode d’interpolation basée sur la variété Grassmannienne est alors proposée pour adapter les bases réduites espace-temps issues de la méthode SVD. Cette méthode a été constatée plus performante que les méthodes d’interpolation standards, notamment en non-linéaire. Afin d’explorer des espaces paramétriques de grandes dimensions, une méthode de type décomposition tensorielle (i.e. HOPGD) a été également étudiée. Pour l’aspect d’optimalité de l’abaque, nous proposons une technique d’accélération de convergence pour la HOPGD et une approche ‘sparse grids’ qui permet d’échantillonner efficacement l’espace des paramètres. Finalement, les abaques optimaux de dimension jusqu’à 10 à précision contrôlée ont été construits pour différents types de paramètres (matériaux, chargements, géométrie) du procédé de soudage. / The use of standard numerical simulations for studies of the influence of input parameters (materials, loading, boundary conditions, geometry, etc.) on the quantities of interest in welding (residual stresses, distortion, etc.) proves to be too long and costly due to the multiparametric aspect of welding. In order to explore high-dimensional parametric spaces, with cheaper calculations, it seems to be appropriate to use model reduction approaches. In this work, in an a posteriori way, a non-intrusive strategy is developed to construct computational vademecum dedicated to parametric studies of welding. In an offline phase, a snapshots database is pre-computed with an optimal choice of input parameters given by a “multi-grids” approach (in parameter space). To explore other parameter values, an interpolation method based on Grassmann manifolds is proposed to adapt both the space and time reduced bases derived from the SVD. This method seems more efficient than standard interpolation methods, especially in non-linear cases. In order to explore highdimensional parametric spaces, a tensor decomposition method (i.e. HOPGD) has also been studied. For the optimality aspect of the computational vademecum, we propose a convergence acceleration technique for HOPGD and a “sparse grids” approach which allows efficient sampling of the parameter space. Finally, computational vademecums of dimension up to 10 with controlled accuracy have been constructed for different types of welding parameters (materials, loading, geometry).