This thesis focuses on the application of case based reasoning (CBR) to welding fixtures in a computer aided design (CAD) environment. Modular fixtures have become more popular in previous years due to the creation of flexible manufacturing systems. Modular fixtures, since they are composed of many standardized parts, require much iteration to produce a full fixture design. This process is made more complicated when it is applied to more complex parts such as welding assemblies. In an effort to simplify fixture design for such complicated parts, researchers have been working on integrating fixture design into CAD packages. These efforts, generally known as computer aided fixture design (CAFD), do not focus on the transition of experience from more experienced designers but only provide a structure and a virtual environment to create fixtures. The research presented in this thesis will apply to this area. Case based reasoning (CBR) is a method of using previous cases to help aid the development of solutions to new problems. Applied to CAFD, this method is reduced to the application of a database and a retrieval and adaptation system. Current research on CAFD and CBR is limited to only proposing systems for machining fixtures. This thesis presents a methodology of a CAFD and CBR system that is dedicated to welding assemblies and fixtures. The focus is on creating an indexing system that adequately represents the workpiece and fixture, a retrieval system that accurately recovers the previous cases, and a method that integrates designer feedback in each process. The results of this thesis will be shown in a case study using an automobile muffler fixture assembly to define each idea of the methodology and to provide an example.

"Concepts in manufacturing such as CIMS (Computer Integrated Manufacturing Systems), JIT (Just In Time), Lean Production, Virtual Manufacturing, and Flexible Fixturing have been proposed to meet the fundamental requirements of manufacturing - decrease the cost and satisfy the needs of customers. Fast fixture generation and fixture reusability are essential in the current manufacturing environment. The dissertation focuses on the models, methods, and algorithms for fixture synthesis and variation that satisfy the functional requirements specified by on-site industrial engineers. With the reusability of a fixture base combined with variation of other fixture components, fixture configuration can be rapidly adapted and accommodated to the new workpiece. The dissertation presents methods and algorithms for fixture base synthesis, which directly result in fixture reusability. Optimization functions are derived based on engineering requirements due to the mass production nature of automotive parts. Specific optimization algorithms are developed and their complexities, compared to other alternatives, are comprehensively evaluated according to different optimization functions. The fixture variation and reusability provide an engineering tool to rapidly generate and validate fixtures in production planning stage. It applies scientific reasoning methodology in combination with best knowledge of fixture designs, which heavily relies on designers' manufacturing knowledge and experience. It also provides means to bridge the gap between CAD and CAM integration and therefore reduces the new product and production development cycle time and cost while maintaining the quality of fixtures."

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Syftet med detta projekt är att utvärdera ModFix som verktyg och arbetsmetoden för att skaps fixturer med ModFix. ModFix är ett verktyg som är integrerad i Siemens simuleringsmiljön Process Simulate och används för att skapa modulära fixturer. Målsättningen med arbetsmetoden där fixturer skapas med ModFix är att ledtiden och mantimmarna för att skapa fixturer ska reduceras med 50 % i jämförelse med Volvo Cars nuvarande arbetsmetod där fixturer skapas med Catia V5. ModFix-verktyget består av tre funktioner. Dessa funktioner är; Configuration Administrator, Fixture Designer och Modular Fixture Mapping Report. Configuration Administrator är ModFix´s administrationsverktyg och används för att skapa de fixturbaser och fixturkonfigurationer som senare används för att skapa modulära fixturer med Fixture Designer. Fixture Designer används för att skapa kompletta modulära fixturer. Modular Fixture Mapping Report är den funktion som används för att generera en rapport som specificerar mappningen mellan de fixturenheterna och de referenspunkter (PLPs/”frames”) där produkten fixeras. Fördelarna med arbetsmetoden där fixturer skapas med ModFix i jämförelse med den nuvarande arbetsmetoden är bland annat att fixturen hela tiden befinner sig i samma utvecklingsmiljö och den extra frihetsgraden att roboten simuleras parallellt med att fixturen skapas för att kunna undvika kollisioner. Även att ModFix automatiskt ger förslag på fixturkonfigurationslösningar för att fästa fixturelementen mot fixturbasen och att fixturer som skapas med ModFix är moduluppbyggda av standardkomponenter är två andra fördelar med arbets­metoden där fixturer skapas med ModFix jämfört med då fixturer skapas med den nuvarande arbetsmetoden. Resultatet av detta projekt visar att ModFix kan reducera mantimmarna betydligt mer än 50 % för att skapa fixturer jämfört med att skapa fixturer med den nuvarande arbetsmetoden. Ledtiden för att skapa fixturer med ModFix reduceras ännu mer än mantimmarna jämfört med då fixturer skapas med den nuvarande arbetsmetoden där fixturer skapas med Catia V5. / The aim of this project is to evaluate ModFix and its work method used to create fixtures with ModFix. ModFix is integrated in the simulation environment Process Simulate, provided by Siemens. ModFix is used to create modular fixtures. The objective with the work method where fixtures are created in ModFix is to reduce lead-time and man-time with 50 % in comparison with the current work method at Volvo Cars where fixtures are created in Catia V5. The tool ModFix consists of three functions. These functions are; Configuration Administrator, Fixture Designer and Modular Fixture Mapping Report. Configuration Administrator is the administration tool in ModFix and is used to create the fixture bases and the fixture configurations as subsequently are used to create modular fixtures with Fixture Designer. Fixture Designer is used to create complete modular fixtures. The Modular Fixture Mapping Report function is used to create a report that specifies the mapping between the fixture units and the reference points (PLPs/frames) where the product is fixed. The benefits with the work method where fixtures are created with ModFix in comparison with the current work method includes that the fixture constantly stays in the same development environment and the possibility to simulate the robot in parallel with creating the fixture to avoid collisions. That ModFix automatic gives suggestions of fixture configuration solutions to attach the fixture element to the fixture base and that fixtures created with ModFix are modular built up of standard components are two other benefits with the work method where fixtures are created with ModFix in comparison with the current work method. The result of this project shows that ModFix can reduce the man-time significant more than 50 % to create fixtures with ModFix in comparison with the current work method where fixtures are created in Catia V5. The lead-time can be reduced even more than the man-time when using ModFix to create fixtures in comparison with the current work method.

<p>Syftet med detta projekt är att utvärdera ModFix som verktyg och arbetsmetoden för att skaps fixturer med ModFix. ModFix är ett verktyg som är integrerad i Siemens simuleringsmiljön Process Simulate och används för att skapa modulära fixturer. Målsättningen med arbetsmetoden där fixturer skapas med ModFix är att ledtiden och mantimmarna för att skapa fixturer ska reduceras med 50 % i jämförelse med Volvo Cars nuvarande arbetsmetod där fixturer skapas med Catia V5.</p><p>ModFix-verktyget består av tre funktioner. Dessa funktioner är; Configuration Administrator, Fixture Designer och Modular Fixture Mapping Report. Configuration Administrator är ModFix´s administrationsverktyg och används för att skapa de fixturbaser och fixturkonfigurationer som senare används för att skapa modulära fixturer med Fixture Designer. Fixture Designer används för att skapa kompletta modulära fixturer. Modular Fixture Mapping Report är den funktion som används för att generera en rapport som specificerar mappningen mellan de fixturenheterna och de referenspunkter (PLPs/”frames”) där produkten fixeras.</p><p>Fördelarna med arbetsmetoden där fixturer skapas med ModFix i jämförelse med den nuvarande arbetsmetoden är bland annat att fixturen hela tiden befinner sig i samma utvecklingsmiljö och den extra frihetsgraden att roboten simuleras parallellt med att fixturen skapas för att kunna undvika kollisioner. Även att ModFix automatiskt ger förslag på fixturkonfigurationslösningar för att fästa fixturelementen mot fixturbasen och att fixturer som skapas med ModFix är moduluppbyggda av standardkomponenter är två andra fördelar med arbets­metoden där fixturer skapas med ModFix jämfört med då fixturer skapas med den nuvarande arbetsmetoden.</p><p>Resultatet av detta projekt visar att ModFix kan reducera mantimmarna betydligt mer än 50 % för att skapa fixturer jämfört med att skapa fixturer med den nuvarande arbetsmetoden. Ledtiden för att skapa fixturer med ModFix reduceras ännu mer än mantimmarna jämfört med då fixturer skapas med den nuvarande arbetsmetoden där fixturer skapas med Catia V5.</p> / <p>The aim of this project is to evaluate ModFix and its work method used to create fixtures with ModFix. ModFix is integrated in the simulation environment Process Simulate, provided by Siemens. ModFix is used to create modular fixtures. The objective with the work method where fixtures are created in ModFix is to reduce lead-time and man-time with 50 % in comparison with the current work method at Volvo Cars where fixtures are created in Catia V5.</p><p>The tool ModFix consists of three functions. These functions are; Configuration Administrator, Fixture Designer and Modular Fixture Mapping Report. Configuration Administrator is the administration tool in ModFix and is used to create the fixture bases and the fixture configurations as subsequently are used to create modular fixtures with Fixture Designer. Fixture Designer is used to create complete modular fixtures. The Modular Fixture Mapping Report function is used to create a report that specifies the mapping between the fixture units and the reference points (PLPs/frames) where the product is fixed.</p><p>The benefits with the work method where fixtures are created with ModFix in comparison with the current work method includes that the fixture constantly stays in the same development environment and the possibility to simulate the robot in parallel with creating the fixture to avoid collisions. That ModFix automatic gives suggestions of fixture configuration solutions to attach the fixture element to the fixture base and that fixtures created with ModFix are modular built up of standard components are two other benefits with the work method where fixtures are created with ModFix in comparison with the current work method.</p><p>The result of this project shows that ModFix can reduce the man-time significant more than 50 % to create fixtures with ModFix in comparison with the current work method where fixtures are created in Catia V5. The lead-time can be reduced even more than the man-time when using ModFix to create fixtures in comparison with the current work method.</p>

With growing demands on improved product quality and shorter time to market, there is need for rigorous but practical tools to support the fixture design and analysis process. Computer-aided fixture design (CAFD), with predictable fixture stiffness, becomes a means to provide an appropriate solution in fixture design. The effectiveness of previous CAFD systems is not fully satisfactory partially because analysis of fixture stiffness has not kept pace with the development of CAFD. The dissertation research provides a model of fixture unit stiffness analysis and an experimental method of identifying contact stiffness parameters. The model and the method offer the potential for a more realistic analysis of fixture stiffness properties of a fixture-workpiece system, based on a fixture unit description. An FEA model of fixture unit stiffness is developed with contact elements for solving contact problems encountered in the study of fixture unit stiffness. The penalty function method is used to model the contact conditions in the energy equation of the general FEA and to describe the nonlinearity of connection shown in previous experiments. The contact and friction conditions are represented mathematically in the FEA model. The FEA model and the analysis procedure are validated by numerical simulation. An experimental study on contact parameters is carried out to identify contact stiffness, including normal contact stiffness and tangential contact stiffness, by both static and dynamic approaches. For normal contact stiffness, a static identification procedure is developed to estimate the contact parameters, using experimental data. Four factors - testing environment, contact area, surface finish of the specimen, and normal loads, - are examined to see how they affect the behavior of the contact interface. A dynamic method is also used to identify normal contact stiffness. A scheme of eigenvalue analysis is developed to test the contact structure to estimate contact stiffness. The dynamic test results are compared with the results of static test under the same experimental condition and a reliable correspondence is presented. Similar to methods devised to identify normal contact stiffness, a frequency-domain identification system is developed to estimate tangential contact stiffness, using FEA and experimental data. A simulation study on vibration data from tangential contact model is presented in this study. The experimental study is carried out and tangential contact stiffness is estimated based on numerical simulation and experimental data. This research establishes the finite element model of fixture unit stiffness and develops the experimental approaches to identify contact stiffness. Based on this study, the database of fixture stiffness can be built up, and further used in CAFD

<p>The unchangeable need of securing and locating parts during different manufacturing processes turned the fixtures to key elements in many part production industries. The iterations between design engineers and manufacturing planners because of late collision detection of the part/fixtures with robots cost a lot of time and money. The lead-time can be reduced by developing tools and/or methods for early verification of the fixtures during the simultaneous engineering phase. Different aspects of fixture designing, modeling and simulating is investigated as a base step to recognize the best practice work to do fixture planning in Process Simulate integrated PLM environment. The aim of the project is to use Process Simulate to design and validate modular fixtures at the same time and in a single environment. It also aims to investigate the possibility of adding kinematics, sensors, and actuating signals to the fixtures and utilize them to model the fixture behavior in a larger simulation study. The project narrows down its focus on the fixtures designed for robotic applications specifically in Automotive Body in White lines without losing generality. The document type stated at the title page and in the header of this page is master thesis work.</p>

The unchangeable need of securing and locating parts during different manufacturing processes turned the fixtures to key elements in many part production industries. The iterations between design engineers and manufacturing planners because of late collision detection of the part/fixtures with robots cost a lot of time and money. The lead-time can be reduced by developing tools and/or methods for early verification of the fixtures during the simultaneous engineering phase. Different aspects of fixture designing, modeling and simulating is investigated as a base step to recognize the best practice work to do fixture planning in Process Simulate integrated PLM environment. The aim of the project is to use Process Simulate to design and validate modular fixtures at the same time and in a single environment. It also aims to investigate the possibility of adding kinematics, sensors, and actuating signals to the fixtures and utilize them to model the fixture behavior in a larger simulation study. The project narrows down its focus on the fixtures designed for robotic applications specifically in Automotive Body in White lines without losing generality. The document type stated at the title page and in the header of this page is master thesis work.

<p>U disertaciji se prikazuje razvoj sistema za<br />projektovanje i optimizaciju konstrukcije pribora za<br />ma&scaron;insku obradu. Analizirani su različiti prilazi u<br />projektovanu pribora. Prikazana je koncepcija i<br />funkcionisanje razvijenog sistema. Validacija sistema<br />je izvr&scaron;ena na konkternim radnim predmetima za<br />operacije obrade bu&scaron;enja i glodanja. Na kraju su dati<br />odgovarajući zaključci i mogući pravci budućih<br />istraživanja</p> / <p> The dissertation shows the development of<br /> system for fixture design and layout<br /> optimization for machining processi. Different<br /> approaches were analyzed in fixture design.<br /> The concept and functioning of the developed<br /> system is presented. Validation of the system<br /> is made with specific workpieces for drilling<br /> and milling process operations. At the end the<br /> appropriate conclusions and possible<br /> directions for future research are given.</p>

<p>U doktorskoj disertaciji je prikazana nova metodologija za projektovanje<br />i optimizaciju konstrukcije elemenata pribora. Projektovani su i<br />realizovani uređaji koji omogućavaju ispitivanje nosivosti i<br />popustljivosti kontakta između elemenata pribora i radnog predmeta u<br />statičkim i dinamičkim uslovima opterećenja. U istraživanjima je<br />simuliran proces stezanja elementima sa specijalno projektovanim<br />završetkom i praćena je nosivost i popustljivost spoja između<br />elemenata pribora i radnog predmeta. Utvrđeno je da standardni<br />elementi za stezanje sa ravnim čelom u odnosu na specijano<br />projektovane elemente imaju značajno manju nosivost i popustljivost.<br />Pozitivni efekti primene elemenata za stezanje sa specijalno<br />projektovanim završetkom ogledaju se u povećanju pouzdanosti, tačnosti<br />i produktivnosti mašinske obrade.</p> / <p>Presented in this doctoral dissertation is a new methodology for the design and<br />optimization of fixture elements. Special device is designed and manufactured<br />to test load capacity and interface compliance between fixture elements and<br />workpiece under static and dynamic loads during machining. The research<br />process is simulated by specially designed clamping elements and monitored<br />for load capacity and interface compliance between fixture elements and<br />workpiece. It was found that the standard clamping elements with flat clamping<br />surface have a significantly lower load capacity and interface compliance in<br />comparison with the specially designed clamping elements. Application of the<br />specially designed clamping elements results in increased reliability, accuracy<br />and machining productivity.</p>