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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.
291

Příprava vzorků pro tahovou zkoušku z tvarově složitého dílu s využitím technologií Reverse Engeneering a CAD/CAM systémů / Sample preparation for tensile test from a form-complex part using Reverse Engineering and CAD/CAM systems

Okřina, Lukáš January 2019 (has links)
The Master's thesis deals with the proposition of a suitable methodology to produce test specimens intended for tensile testing. Considering the irregular geometries of the parts and deformations in previous tests, reverse engineering was used to obtain a CAD model that was used to control dimensions and create a machining strategy. This thesis also includes an analysis of current technologies in the field of reverse engineering.
292

Development of a Variational Part Model Using In-Process Dimensional Measurement Error

Carlson, Shane A. 15 June 2006 (has links)
To improve the geometric accuracy of CNC machined parts, dynamic machining errors due to on-line disturbances (tool deflection, tool wear, heat deformation, etc.) should be accounted for in some manner. Unless these on-line disturbances are properly handled, it is obvious that a high degree of geometric accuracy is difficult to achieve. Many attempts have been made to compensate for these on-line disturbances such as the development of engineering models; however, the models are not adequate enough for reflecting the real phenomenon and are dependent on continuous process monitoring using a variety of sensors. Closed-loop process control is a scheme for manufacturing parts and compensating for on-line disturbances and machine tool inaccuracies using error feedback. The goal has been to develop a system that automatically provides dimensional error feedback to the process machine. Closed-loop process control can be achieved before, during (in-process) or after the machining cycle. In-process control is achieved by measuring the part prior to finishing cuts while the part is fixtured to the machine tool. Although the theory behind an automated closed-loop, in-process control system would significantly reduce manufacturing costs, at the present time, machining errors typically are compensated through manual error feedback. This thesis presents a systematic approach for automatically compensating for dynamic machining errors based on a new closed-looped machining scheme. The new scheme incorporates these errors, found through in-process inspection, into a modified CAD model or "Variational Part Model". As a result, the Variational Part Model inherently contains the online disturbances associated with machining. It is important to note that this new scheme assumes the machine tool's static error (ball screw error, joint misalignment, perpendicularity error, etc.) has been addressed by some other compensating method and this scheme only addresses the dynamic machining error. To create the Variational Part Model, the machined part is measured on the machine and compared to the CAD model's theoretical data. The data is then used in conjunction with modeling functions contained in NX's Application Programming Interface (API) to interact with the CAD model and modify its feature geometry. The validity and effectiveness of the methods are presented as well as results from experimental testing. This thesis also presents the methods necessary for automatic CAM process updating to ultimately close the loop between machining and inspection.
293

Využití CAD/CAM technologie pro výrobu formy čerpadlového kola / Utilization of CAD/CAM technology for the casting mould manufacturing of an impeller wheel

Kafka, Lukáš January 2010 (has links)
The master thesis deals with design for casting mould of an impeller wheel for investment casting lost wax and machining technology with utilization CAD software SolidWorks 2008 and CAM software PowerMill 9. Subsequent verification of machining on vertical machining center MCV 1210. At the end, techno-economic evaluation is done.
294

Komplexní využití konstrukčních podkladů pro CNC programování turbínových skříní. / Total usage of design dates for CNC programming of turbine casing

Matejková, Monika January 2010 (has links)
This thesis aims at designing a solution to the comprehensive use of construction underlying documents for the CNC programming of turbine casings. The introductory part of the thesis contains a description of the CNC programming and CAD/CAM systems. The following is mapping of the current state of the construction underlying documents, and mapping of the situation in the department of technology in Siemens Industrial Turbomachinery, s.r.o., Brno. The further section presents an analysis of the problem that arose when processing and sharing the construction underlying documents with the aim of streamlining the CNC programming process. The closing part presents the evaluation and conclusions for implementation of the proposed solutions.
295

Návrh a výroba příruby náboje zadního kola formule pomocí technologie CAD/CAM a dílenského CNC programování / Design and machining of the flange hub rear wheel of the formula by using CAD/CAM technology and CNC workshop programming

Lučaník, Aleš January 2013 (has links)
This master's thesis deals with design and machining of the flange hub rear wheel of the formula by using CAD/CAM technology and CNC workshop programming. The introductory part provides theoretical description and characteristic of turning and milling technology. Further work describes aluminium alloys with focus on material which was used as a blank for machined workpiece. The practical part deals with design of flange in CAD software Autodesk Inventor, design of turning strategies in system ShopTurn and design of milling strategies in software PowerMILL. The final part of this thesis specifies realization of manufacturing on CNC lathe and CNC machining center in company BOSCH DIESEL s.r.o. in Jihlava. Last chapter is focused on techno-economic aspects of manufacturing.
296

Výroba složitých tvarových ploch pomocí CNC/Heidenhain iTNC 530 / Production of sculptured surfaces with CNC/Heidenhain iTNC 530

Břínek, Martin January 2014 (has links)
The diploma thesis is focused on the milling strategies and their suitability for the production of complicated sculptured surfaces using a three-axe milling center and the operation system Heidenhain iTNC 530. The behavior of the tools and the results of the individual milled samples were monitored under changing milling strategies during the experiment. The outcomes of the experiment were seven milled samples and an assessment of the effect of the Machine – Tool – Workpiece system toughness. In addition, the suitability of the milling strategies were evaluated in consideration to the quality of the milled surface and the production time.
297

Aplikace víceosového frézování na obrábění tvarové součásti / Application of the multi-axis milling of a shaped part

Klíma, Jiří January 2015 (has links)
This diploma thesis focuses on the design and production technology of making pattern and core box by milling. The theoretical part summarizes the issue of production models, CAD / CAM technology and milling technology. The practical part is elaborates engineering design of machined parts focused on the specific requirements for application in the foundry. For designing of milling technology was used CAM system. This milling technology was programmed and optimized. Parts are finally produced on 3-axis milling machine. In the end there is technical-economic evaluation of production and discussion of results.
298

Návrh na zefektivnění procesu obrábění ozubení pastorku / Efficiency Improvement Proposal of Machining Process of Pinion Gearing

Pangrác, Pavel January 2016 (has links)
This diploma thesis deals with the machining process of pinion gearing in the company Šmeral Brno a.s. The first part aims at the basic description of the thesis subject – the pinion. General gear machining technologies and its inspection is processed in the second part. The third part is focused on the description of the current machining process, its weaknesses and strengths. The main part consists of the machinery and tool choice, of the proposal of the gearing technological process for five-axis machining center and of the production time calculations. In conclusion, technological and economic impacts of the proposal are evaluated.
299

Effet de l’irradiation laser sur les couronnes céramiques usinées en CFAO : propriétés chimiques et mécaniques et étanchéité bactérienne / Effect of laser irradiation on CAD/CAM ceramics crowns : chemical and mechanical properties and bacterial microleakage

El Gamal, Ahmed 19 December 2017 (has links)
Objectifs : Le but de travail est d'étudier les possibles variations des propriétés physiques et chimiques en rapport avec l’usinage et les effets de l’irradiation avec des lasers CO2 et Nd:YAP. Il s’agit d’évaluer l’étanchéité de cet assemblage par micro-infiltration d’un biofilm mono bactérien par une technique FISH. Méthodes : Les tests d’évaluation ont été : la micro dureté, le cisaillement, la rugosité, la mouillabilité et l’EDS. 60 échantillons de 2 céramiques (les disilicates de Lithium et les Zircones) ont été soumises aux différents test. Pour le test d’étanchéité : Six couronnes de chacune des céramiques ont été exposées à biofilm de Streptococcus Salivarius pendant 10j. FISH a été appliquée pour marquer les infiltrations bactériennes observées en microscopie confocale. La résistance au cisaillement (p.=0,014 S) est significativement différente entre les échantillons irradiés et non irradiés. La mouillabilité superficielle partielle est bonne pour les 2 types de céramique. Les surfaces irradiées au Laser CO2 sont plus rugueuses pour les deux céramiques. La micro dureté de Li irradiée au CO2 a augmenté (6,32 GPa). Aucune élévation notable de température sur les 2 types de céramique. Le test d’étanchéité s’est avéré positif à la jonction cervicale couronne /dent. Conclusion : Les lasers CO2 et Nd: YAP modifient les forces de cisaillement et les surfaces des céramiques sans en modifier la composition chimique. L'irradiation au laser CO2 semble augmenter la résistance au cisaillement, la rugosité de la surface, la micro dureté et la mouillabilité des 2 types de céramique. L'irradiation des couronnes usinées au laser CO2 semble amélioré l’étanchéité de l’assemblage collé. / The purpose is to study the physical and chemical properties of CAD/CAM ceramics irradiated with CO2 and Nd:YAP lasers and to evaluate surface adhesion of ceramic crowns by microleakage test with a mono bacterial biofilm and a FISH technique. Methods : Evaluations tests were: Micro hardness, roughness, surface wettability, shear bond strength and EDS. 60 samples Two ceramics used: lithium disilicate and zirconia ceramics were prepared for different test. For microleakage test:Six ceramics crowns of different ceramics were contaminated with a Streptococcus salivarius biofilm for 10 d. Fluorescence in situ hybridization technique was applied samples were examined with confocal laser microscope. Results: Shear bond test showed significant difference between irradiated and non irradiated (p. value= 0,014 S). Partial superficial wettability was observed for the two ceramics. In micro hardness test, CO2 at 5 W increased micro hardness of lithium disilicate ceramics with significant value (6,32 GPa). SEM showed rough surface in all groups. EDS did not modify the chemical composition of tested ceramics. No significant rise in temperature could be recorded on both types of ceramic.The micro leakage test of a mono-bacterial biofilm was positive at the crown / tooth cervical junction. Conclusion: CO2 and Nd: YAP lasers modify CAD/CAM ceramic surfaces without chemical composition modifications. CO2 irradiation increase shear bond strength, surface roughness, micro hardness and made CAD/CAM ceramics hydrophilic. Irradiation with CO2 laser seems to improve surface adhesion and decrease bacterial microleakage.
300

Effect of cyclic fatigue on the failure load of screw and cement-retained CAD/CAM implant crowns

Ali, Rasha 26 July 2018 (has links)
OBJECTIVE: The aim of this in-vitro study is to assess the effect of cyclic loading fatigue on failure load of CAD/CAM cement-retained implant crowns and screw-retained implant crowns with screw access holes sealed with composite or Enamic inlay. MATERIALS AND METHODS: For the screw-retained implant crowns, Ivoclar e.max and Vita Enamic CAD/CAM (n=44 for each material) and Enamic inlays (n=44) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared e.max and Enamic crowns were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. The access holes were sealed either by using composite or and Enamic inlay (n=22 for each group). For cement-retained implant crowns, Ivoclar e.max, Vita Enamic, and Vita Mark II CAD/CAM (n=20 for each material) and Enamic and Zirconia abutments (n=40 for each group) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared zirconia and Enamic abutments were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. Then, all prepared Ivoclar e.max, Vita Enamic, and Vita Mark II crowns were cemented to the abutments using Multilink Automix cement. After cementation, 10-12 specimens from each group (both screw and cement-retained) were subjected to a static load to failure test in a universal mechanical testing machine (Instron 5566A). The mean failure load for each group was calculated. The other 10 specimens for each group were subjected to cyclic loading fatigue under 40% of static failure load for 50,000 and 100,000 cycles. After cyclic loading, the surviving specimens were tested for static failure load. The comparison of failure load between tested groups was analyzed by one-way ANOVA using JMP Pro 13 with α=0.05. RESULTS: For IPS e-max CAD screw-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles, but no significant difference between static and after cyclic fatigue for 100,000 cycles. For Vita Enamic crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles and 100,000 cycles. There was a significant difference in the failure load between screw-retained implant crowns sealed with composite and those sealed with Enamic inlay. For IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. For Vita Enamic /Zr abutment cement-retained implant crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. CONCLUSION: The screw-retained implant crowns sealed with composite had higher failure load than those sealed with Enamic inlay. The cyclic fatigue has an effect on IPS e.max CAD screw-retained implant crowns, IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns. The cyclic fatigue has no effect on Vita Enamic screw-retained implant crowns and Vita Enamic/ Zr abutment cement-retained implant crowns.

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