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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Analyse, modélisation et méthodes de compensation du défaut de suivi de trajectoire pour le parachèvement robotisé : cellule robotisée de parachèvement pour l’usine du futur / Analysis, modelling and compensation methods of path tracking fault for robotized aeronautical part finishing

Ambiehl, Alexandre 04 May 2017 (has links)
Le parachèvement de pièces aéronautiques en aluminium représente une part importante du coût des pièces produites. L’objectif de ces travaux est d’opérer un transfert d’opérations, des opérateurs et machines vers les cellules robotisées, économiquement plus intéressantes. Cette thèse vise à améliorer l’identification d’un modèle elasto-statique des robots industriels et à fournir une méthode de correction hors ligne des trajectoires dans une logique de moyenne série. Le premier chapitre présente un état de l’Art du parachèvement et des procédés que nous avons pris en considération. Il évoque les robots industriels, leur architecture, leur modélisation géométrique et elasto-statique. Il s’intéresse à leurs défauts de suivi de trajectoire et les causes associées. Dans le second chapitre, nous étudions les méthodes d’identification du modèle elasto-statique existantes. Nous critiquons leur mise en oeuvre actuelle et proposons une amélioration des protocoles d’identification. Nous étudions l’influence de la méthodologie de reconstruction géométrique par une étude de la sensibilité des raideurs apparentes. Nous proposons une nouvelle méthode de découplage de l’identification pour apporter plus de robustesse dans la détermination des raideurs articulaires. L’apport de cette méthode se justifie par son application sur un robot à double encodage KUKA KR 300 SE. Le dernier chapitre propose une correction miroir améliorée. Celle-ci intègre la problématique de la dynamique de la commande générée par la méthode miroir. Elle est appliquée sur des trajectoires circulaires, mesurée avec un outil ballbar. / The finishing of aluminium aeronautical parts is a great share of the overall production cost. The aim of this work is to facilitate operation transfert from manual operations and machines operations to robotic cells that are economically more interesting. This thesis seeks to improve the identification of a kinetostatic model for industrial robots and provide an offline correction method for mid-size part production volume. The first chapter is a state of the art in finishing operations and the involved processes, mainly machining, grinding and sanding that we considered in this study. It presents robots architecture and models (kineto-static and geometric). We show example of path tracking errors and the associated causes according to the literature. In the next chapter, we study the existing kineto-static identifications methods. We review the actual implementation of the methods and offer improvements. We study the influence of the geometrical reconstruction methodology applied in those identification methods by a sensibility analysis on the stiffness parameters. We propose a new identification method based on decoupling equations. This method brings more reliable results and robustness in the value of the stiffness parameters. The contribution of this method is justified by its application on a double encoder robot (KUKA KR 300 SE). The last chapter is a proposal for an improvement in the mirror correction method for trajectory correction. This new proposal takes into account the dynamics of the command created by the mirror method. It is applied on circular trajectories and measured thanks to a Ballbar tool.
2

Ekonomisk påverkan av ballbarmätningar i fleroperationsmaskiner : Utforska ballbarmätningars effekter inom förebyggande underhåll / Economic influence of ballbar measurements in multi-operation machines : Explore the effects of ballbar measurements in preventive maintenance

Larsson, Tobias, Jigmalm, Victor January 2019 (has links)
The purpose of this study is to explore the effects of ballbar measurement in preventive maintenance. Volvo GTO in Skövde currently has no model for how they can count on the economic effects that occur when ballbar measurement is carried out as preventive maintenance. The model is needed for the company to be able to make correct decisions on the development of future measurement methods for analyzing the state of machine components. In order to answer the research questions, a case study has been conducted through interviews, conversations, document studies and with the help of literature studies, basic theories relevant to the study area that has been described. The result shows that about half of all breakdowns are avoided due to ballbar measurement being performed on the department concerned. The fact that breakdowns still occur is a future challenge for the company to investigate further. A model that calculates the economic effects has been designed and will serve as a basis for future investments, also the model should be able to be used at other departments within the Volvo GTO in Skövde. The study could not demonstrate that there are quality deficiency costs related to defected ball screw components with the fact collection available. A better work around root cause that points to defective machine components would give the study a better credibility. Based on the results of the study, conclusions can be drawn that quality deficiency costs should be excluded in the economic model since the documentation contains too little information on quality deficiency costs related to defected ball screw components.
3

The identification of geometric errors in five-axis machine tools using the telescoping magnetic ballbar

Flynn, Joseph January 2016 (has links)
To maximise productivity and reduce scrap in high-value, low-volume production, five-axis machine tool (5A-MT) motion accuracy must be verified quickly and reliably. Numerous metrology instruments have been developed to measure errors arising from geometric imperfections within and between machine tool axes (amongst other sources). One example is the TMBB, which is becoming an increasingly popular instrument to measure both linear and rotary axis errors. This research proposes new TMBB measurement technique to rapidly, accurately and reliably measure all position-independent rotary axis errors in a 5A-MT. In this research two literature reviews have been conducted. The findings informed the subsequent development of a virtual machine tool (VMT). This VMT was used to capture the effects of rotary and linear axis position-independent geometric errors, and apparatus set-up errors on a variety of candidate measurement routines. This new knowledge then informed the design of an experimental methodology to capture specific phenomena that were observed within the VMT on a commercial 5A-MT. Finally, statistical analysis of experimental measurements facilitated a quantification of the repeatability, strengths and limitations of the final testing method concept. The major contribution of this research is the development of a single set-up testing procedure to identify all 5A-MT rotary axis location errors, whilst remaining robust in the presence of set-up and linear axis location errors. Additionally, a novel variance-based sensitivity analysis approach was used to design testing procedures. By considering the effects of extraneous error sources (set-up and linear location) in the design and validation phases, an added robustness was introduced. Furthermore, this research marks the first usage of Monte Carlo uncertainty analysis in conjunction with rotary axis TMBB testing. Experimental evidence has shown that the proposed corrections for set-up and linear axis errors are highly effective and completely indispensable in rotary axis testing of this kind. However, further development of the single set-up method is necessary, as geometric errors cannot always be measured identically at different testing locations. This has highlighted the importance of considering the influences on 5A-MT component errors on testing results, as the machine tool axes cannot necessarily be modelled as straight lines.
4

Volumetrická přesnost obráběcích strojů / Volumetric accuracy of machine tools

Máčala, Daniel January 2019 (has links)
The diploma thesis deals with the influence of the volumetric accuracy of the machine tool on the size of the assessed work space. The impact assessment was carried out on the basis of tests of a three-axis vertical CNC machining center. The thesis is divided into two parts, theoretical and practical. The theoretical part is focused on geometric / volumetric accuracy of machine tools, measuring technique for measuring geometric errors and Design of Experiment. In the practical part, there is an analysis of the Design of Experiment according to Shainin, description of the work with the measuring instruments and the measurement of the geometric / volumetric accuracy of the machine including statistical evaluation. The output of the thesis is the description of the influence of volumetric deviation on the size of the measured work space by means of statistical methods.
5

Posouzení geometrické přesnosti obráběcího centra pomocí digitálních inklinometrů / Assessment of geometric accuracy of machining center using digital inclinometers

Únar, Jan January 2021 (has links)
This diploma thesis deals with assessment of geometric accuracy of machining center MCV 754 QUICK. BlueSYSTEM digital inclinometers from WYLER AG, XL-80 laser interferometer from RENISHAW, Ballbar QC20-W from RENISHAW and LaserTRACER self-guiding laser interferometer from ETALON AG were used to measure accuracy. Error of the X straightness in the direction of the Z axis was assessed. The first part of the paper describes the geometric accuracy of the machine, currently available instruments for measuring geometric accuracy and an explanation of straightness. The second part consists of the design of measurements, experiment, evaluation and comparison of results and recommendations for teaching.
6

Zpracování dat z měření na obráběcích strojích / Data processing from measurement on machine tools

Pokorný, Zdeněk January 2018 (has links)
The Master’s thesis deals with the precision of machine tools, especially with the three-axis vertical milling machine. It is structurally divided into a theoretical and practical part. While the theoretical part focuses on problems of geometric errors and measuring devices, the practical one is devoted to the machine tool being tested. In this case, the data processing and the proposed statistical analysis are essential, and at the end of the thesis another possible way of developing the data processing is outlined.
7

Měření obrobků na obráběcích strojích pomocí obrobkové sondy / Measurement of workpieces on machine tools using a touch probe

Velič, Samuel January 2020 (has links)
This diploma thesis deals with the influence of electronic compensation on accuracy of the measurement using the touch probe. The theoretical part concerns touch probes, specifically their classification, principles of working and applications. This part also includes devices used later in the experiment, particularly double ballbar, laser interferometer and LaserTRACER. The Practical part describes an experiment, demonstrating the correlation between the accuracy improvement of the touch probe and the electronic compensation’s level. All measurements were executed in accordance with the norm VDA 5 and were evaluated by the Matlab software. The graphs of reliance tolerance of capability of measurement on the length of the benchmark. At the end of this diploma thesis there are partial conclusions deduced. The deduction is based on generated graphs. The partial conclusions synoptically compare the influence of individual machine´s configurations on the accuracy of the touch probe.
8

Návrh automatického cyklu pro posuzování způsobilosti měření obrobkovou sondou na obráběcím centru / Design of an automatic cycle for assessing the measurement capability of a workpiece probe on a machining center

Mišún, Filip January 2021 (has links)
This diploma thesis describes the procedures of individual electronic compensations for CNC machines used to increase the accuracy of machines. This part is followed by the determining tolerance of the measuring and the influence of individual electronic compensations based on measured data using touch probe and calibrated standards according to VDA 5 norm.
9

Vliv konvenčních kompenzací na volumetrickou přesnost obráběcího stroje / Impact of conventional compensation to the volumetric accuracy of the machine tool

Žák, Zdeněk January 2016 (has links)
This thesis solves the impact of conventional compensation to the volumetric accuracy of the CNC machine. It is therefore a practical research work, where are in the theoretical introduction mentioned requirements for machine tools, the types of errors that can occur on three-axis kinematics, compensation for the control system Siemens Sinumerik 840D sl and devices by means of which are these compensation under the work formed and subsequently verified. In this work can be seen the measured values and graphs from each measurements, a detailed analysis of the results and drawing conclusions from these results.

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