The degree projects purpose is to explore, analyze and explainwhat quality improvements robotic welding can bring to a company’soperations. The study was carried out as a qualitative case studywith an inductive approach. Together with established theoriesfrom TQM and change management, research of manually performed andautomated welding technology, and requirements from ISO standardshas been used to corroborate the requirements and changes that thewelding company are facing. As method for data collectioninterviews, document studies and benchmarking has been conductedin order to analyze the possible quality improvements the companycan achieve by changing parts of their manufacturing system frommanually to automated welding processes. The result of the studyshows that the company is experiencing inefficiency as aconsequence of the workflow in the existing workshop. The companyare at the planning stage of building av new workshop, where thenew workshop together with implementation of automated weldingprocesses can raise new opportunities and simplify the work forthe coworkers which also can reduce safety hazards. The conclusionof the degree project show that the employees who will be affectedby the implementation are aware of, and they have a positiveattitude to the change process as they will get better knowledgeand expertise due to courses required to operate the robot. Thecompany’s management system must be revised in order to adapt tothe new working methods. In relation to the installations that thecompany delivers, the installations may experience improvedwelding quality and the installations lead time will be reduced.The degree project highlights the importance of planning and thatboth the change and implementation process require structure andcontrol. / Examensarbetets syfte är att utforska, analysera och förklara vilka kvalitetsförbättringarrobotsvetsning kan tillföra ett företags verksamhet. Undersökningen utfördes som en kvalitativfallstudie med en induktiv ansats, vilket innebär att utifrån undersökningens datainsamling somligger till grund, har lämpliga teorier och tidigare forskning och arbeten tagits fram. Teoriernagrundar sig på förändringsledning och offensiv kvalitetsutveckling där kärnan vilar påhörnstensmodellen och PAV-modellen, men även teorier kring kvalitetsbristkostnader ochprocesser har varit viktiga för att belysa de möjliga kvalitetsförbättringar som företaget kan uppnåmed implementering av robotsvetsning. Tillsammans med de etablerade teorierna inom offensivkvalitetsutveckling har forskning och kunskaper om både manuell och automatiserad svetstekniksamt krav från olika ISO-standarder tagits fram för att bättre belysa vad som krävs av ettsvetsföretag och vilka förändringar företaget står inför.Datainsamlingen omfattas av intervjuer med vd och medarbetare i företaget för att etablera nulägetoch undersöka vilka förutsättningar och krav de har till implementeringen av robotsvetsning.Intervjuer har även genomförts med näringslivskontoret i kommunen där företaget villvidareutveckla verksamheten. En leverantör av robotsvetsar har också valts ut för intervjuer för attbättre analysera vilka kvalitetsförbättringar som kan uppnås med att gå från manuell tillautomatiserade svetsmetoder. I tillägg till intervjuer har benchmarking genomförts hos ett annatsvetsföretag som använder svetsrobot i produktionen.Resultatet från studien visar att företaget upplever ineffektivitet som orsak av svåra arbetsflöden iden befintliga verkstaden. Företaget kommer inom kort tid att flytta tillverkningen som omfattasav prefabricering av rörinstallationer till en ny, egen verkstad som ger möjligheter för attimplementera ny teknik som kan förenkla arbetsvardagen för medarbetarna som innebär mindresäkerhetsrisker. Slutsatserna i examensarbetet visar att medarbetarna som påverkas avimplementeringen känner till, och är positiva till förändringen vilket förenklar processen. Underförändringsprocessen kommer medarbetarnas kompetens och kunskaper utökas med utbildning.Företagets ledningssystem måste revideras för att anpassas till nya arbetssätt och utifrånerfarenheter från tidigare forskning och arbeten kommer svetskvaliteten att förbättras och ledtidervid prefabricering kommer att reduceras för företaget. Examensarbetet synliggör vikten avnoggrann planering och styrning av förändringsprocessen.

Tungsten Inert Gas (TIG) welding is extensively used in aerospace applications, due to its unique ability to produce higher quality welds compared to other shielded arc welding types. However, most TIG welding is performed manually and has not achieved the levels of automation that other welding techniques have. This is mostly attributed to the lack of process knowledge and adaptability to complexities, such as mismatches due to part fit-up. Recent advances in automation have enabled the use of industrial robots for complex tasks that require intelligent decision making, predominantly through sensors. Applications such as TIG welding of aerospace components require tight tolerances and need intelligent decision making capability to accommodate any unexpected variation and to carry out welding of complex geometries. Such decision making procedures must be based on the feedback about the weld profile geometry. In this thesis, a real-time position based closed loop system was developed with a six axis industrial robot (KUKA KR 16) and a laser triangulation based sensor (Micro-Epsilon Scan control 2900-25).

The diploma thesis deals with the design of a workplace with robots designed for spot welding of wire reinforcement of the car seat. After analyzing and description of the given task, the workplace concept is chosen based on the input parameters. Subsequently, sub-systems of the production cell are designed and selected for this concept. For example the design of clamping fixtures, rotary table, input and output storage magazines or the selection of welding guns and robots are solved. The workplace is designed to ensure operator safety and protection. The production cycle of the designed workplace is simulated in Siemens Process Simulate to verify functionality and required productivity of the production line. Technical and economic evaluation of the proposed solution is also included in this diploma thesis.

An experimental program was developed to test various unreinforced RHS-to-RHS 90° T-connections subject to branch in-plane bending moment with the objective of determining the effectiveness of the welded joint. Twelve unique test specimens were designed to be weld-critical and the results from the full-scale tests revealed that the current equation for the effective elastic section modulus for in-plane bending, S_ip, given in Table K4.1 of ANSI/AISC 360 (2010) is conservative. A modification to the current requirements that limit the effective width of the transverse weld elements is proposed, resulting in a safe and more economical weld design method for RHS-to-RHS T-, Y- and X- connections subject to branch axial load or bending moment. It is also concluded that the fillet weld directional strength enhancement factor, (1.00 + 0.50sin1.5Ө), should not be used for strength calculations of welded joints to square and rectangular hollow structural sections.

An experimental program was developed to test various unreinforced RHS-to-RHS 90° T-connections subject to branch in-plane bending moment with the objective of determining the effectiveness of the welded joint. Twelve unique test specimens were designed to be weld-critical and the results from the full-scale tests revealed that the current equation for the effective elastic section modulus for in-plane bending, S_ip, given in Table K4.1 of ANSI/AISC 360 (2010) is conservative. A modification to the current requirements that limit the effective width of the transverse weld elements is proposed, resulting in a safe and more economical weld design method for RHS-to-RHS T-, Y- and X- connections subject to branch axial load or bending moment. It is also concluded that the fillet weld directional strength enhancement factor, (1.00 + 0.50sin1.5Ө), should not be used for strength calculations of welded joints to square and rectangular hollow structural sections.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-25T22:19:38Z No. of bitstreams: 1 SIDERLEY FERNANDES ALBUQUERQUE – TESE (UAEMa) 2015.pdf: 14115544 bytes, checksum: 11822f51a2dc681dc362498cb6b9d1c7 (MD5) / Made available in DSpace on 2018-06-25T22:19:38Z (GMT). No. of bitstreams: 1 SIDERLEY FERNANDES ALBUQUERQUE – TESE (UAEMa) 2015.pdf: 14115544 bytes, checksum: 11822f51a2dc681dc362498cb6b9d1c7 (MD5) Previous issue date: 2015-02-27 / No Brasil, a soldagem de tubulações ainda emprega processos manuais com eletrodo revestido, porém, tem crescido as pesquisas com o objetivo de implementar processos mais produtivos, e que atendam às exigências requeridas por normas específicas. Processos de soldagem robotizados estão sendo largamente utilizados em vários países, com ganho considerável na produtividade, como também na qualidade superficial. A utilização de processos de soldagem automatizados possibilita, além da maior produtividade, um maior controle dos parâmetros de soldagem, podendo favorecer positivamente as transformações microestruturais, e consequentemente, em melhores propriedades mecânicas da junta soldada. O objetivo deste trabalho foi avaliar a tenacidade à fratura de juntas soldadas em chapas aço API 5L X80 com 19 mm de espessura, utilizados para transporte de petróleo e gás, quando submetidos à soldagem robotizada nas posições plana e vertical ascendente, utilizando processo de soldagem a arco elétrico com arame maciço para o passe de raiz (ER 120S-G), e processos de soldagem com arame tubular para os passes de enchimento e acabamento, utilizando arame do tipo flux-cored e proteção de gás externa (E101T-1), e arame do tipo autoprotegido (E91T8-G); o gás de proteção utilizado foi Ar+25%CO2. Foram realizadas análises de microdureza e microestrutural na ZTA das juntas soldadas, utilizando microscopia óptica e microscopia eletrônica de varredura; para avaliação da tenacidade na ZTA das juntas soldadas, foram usinados corpos de prova do tipo SE(B) para ensaio CTOD. A análise microestrutural na ZTA para todos os procedimentos indicam a presença de bainita e ferrita acicular, com exceção do procedimento de soldagem na posição plana utilizando arrame autoprotegido que apresentou ferrita primária. Os resultados de tenacidade a fratura obtidos indicam que os procedimentos de soldagem robotizados na posição plana apresentaram a maioria dos valores de CTOD superiores aos procedimentos de soldagem na posição vertical ascendente. Os procedimentos de soldagem robotizados na posição plana usando arame autoprotegido apresentaram o melhor resultado em termos de crescimento da pré-trinca de fadiga, com perfil na região central de forma arredondada, diferente do procedimento de soldagem na posição plana com RP- G que apresentou a forma plana. / In Brazil, the welding pipes still uses manual processes with coated electrodes, however, research has grown to implementing more productive processes, and complying with the requirements of specific rules. Robotic welding processes are in use in Sweden, USA, Canada, Russia and China, with a considerable increase in productivity, and higher quality welds surface. The use of automated welding processes increase the productivity, and promote better control of the welding parameters, and microstructural changes, and consequently, better mechanical properties of the welded joint. The objective of this study was to evaluate the fracture toughness of API 5L X80 steel welded joints with thickness for 19 mm, used for oil and gas transmission, when subjected to robotic welding in the flat and vertical upward positions using arc electric welding process with solid wire for the root pass (ER 120S-G), and tubular wire for the filler passes and finishing, using flux- cored wire (E101T-1) and Ar + 25% CO2 as shielding gas and self-protected wire (E91T8-G). For this, CTOD specimens with all notched located in HAZ were prepared and submitted to metalographic and microhardness test were also done to observe the resulting microstructure and hardness value in the region of the crack, using optical and scanning microscopy analysis. The microstructural analysis in the ZTA of the specimen for all procedures indicated the presence of Bainite and Acicular Ferrite, except those obtained in flat position using the Flux-Cored Self-Shielded welding process which also presented Primary Ferrite. The results of fracture toughness test indicated that the welding in a flat position presented the most superior CTOD values. The robotic welding procedures in the flat position using Flux-Cored SelfShielded welding process showed the best result in terms of the fatigue pre-crack growth, with profile in the central region of rounded shape, unlike flat shape in the robotic welding procedures in the flat position using Flux-Cored and Ar + 25% CO2 as shielding gas.