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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.
21

Разработка технических средств уменьшения температурных погрешностей обработки на высокоскоростных токарных станках : магистерская диссертация / Development of technical means to reduce the temperature errors of processing on high-speed lathes

Оссовская, Е. С., Ossovskaya, E. S. January 2021 (has links)
В начале работы рассматриваются факторы, которые влияют на точность станков, и учитывается роль температурных деформаций для обеспечения точности обработки на металлорежущих станках. Наблюдается, что большое влияние на точность станков оказывают тепловые деформации. После этого познакомились со способами уменьшения температурных деформаций узлов станков, которые используются в данное время, и с техническими средствами их реализации. Рассмотрев существующие системы, мы определили задачу разработки системы термостабилизации с водяным охлаждением электрошпинделя. Для начала мы модернизировали существующую систему термостабилизации шпиндельного узла, в которую включили цепь дифференциала. Потом, обозначив достоинства и целесообразность комбинированного управления, разработали более совершенную систему термостабилизации шпиндельного узла. Далее рассмотрен другой фактор погрешности при обработке – это инструмент, в нашем случае резец для токарной обработки. Для него была разработана система охлаждения с учетом нагрева пластины. / At the beginning of the work, the factors that affect the accuracy of machine tools are considered, and the role of temperature deformations is taken into account to ensure the accuracy of processing on metal-cutting machines. It is observed that thermal deformations have a great influence on the accuracy of machine tools. After that, we got acquainted with the ways to reduce the temperature deformations of machine components that are currently used, and with the technical means of their implementation. Having considered the existing systems, we determined the task of developing a thermal stabilization system with a water-cooled electric spindle. To begin with, we upgraded the existing thermal stabilization system of the spindle assembly, which included a differential circuit. Then, having identified the advantages and expediency of combined control, we developed a more advanced system of thermal stabilization of the spindle assembly. Next, another factor of error in processing is considered – this is a tool, in our case, a cutter for turning. A cooling system was developed for it, taking into account the heating of the plate.
22

Analýza a modifikace tenkých vrstev pomocí iontových svazků / Analysis and modification of thin layers using ion beams

Jonner, Jakub January 2010 (has links)
This diploma thesis deals with analysis and modification of thin layers using ion beams. The first part of this diploma thesis deals with phenomena accompanying ion beam bombardment of solid matter. The second part of this diploma thesis is concerned with Secondary Ion Mass Spectroscopy (SIMS) and Low Energy Ion Scattering (LAIS). This work convey some basic information about these two techniques and it also deals with some benefits result in their connection into parallel depth profiling mode (such as better depth resolution of the LEIS profile, quantification of the SIMS). These benefits are demonstrated on MoSi film measurement. Within the framework of this thesis a new UHV manipulator was designed. This new UHV manipulator is equipped with precise stepper UHV motor and since the proportions are smaller, the manipulation with a sample in a space limited UHV chamber is much more comfortable and more precise. The third part of this diploma thesis deals with ion-beam induced transformation of epitaxially grown Fe films with thickness of 22 monolayer (ML) and 44 ML on Cu(100) single crystal at room temperature. Metastable Fe films of 22 ML thickness were prepared in CO pressure and 44 ML Fe films were prepared by co-evaporation of Fe with Fe64Ni36 (invar). Structural changes are analyzed by scanning tunneling microscopy and low-energy electron diffraction. The aim of this thesis is to discuss the influence of the sputtering parameters such as ion dose and ion energy on the nucleation of bcc nanocrystals, their growth, final shape and size. The influence of different Ni concentration on stability of 44 ML thick Fe films is also discussed.

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