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EFFECT OF GEOMETRICAL PRECISION MACHINING CENTERS ON THE DESIRED CHARAKTERISTICTS OF THE GOODS
Holub, Michal ; Demeč, Peter (referee) ; Hýbner, Břetislav (referee) ; Pernikář, Jiří (referee) ; Marek, Jiří (advisor)
The main subject of this doctoral thesis is the influence of the geometrical accuracy of large CNC machine tools on desired features of produced work pieces. Doe to globalized market environment and competition producers of machine tools have changed their strategy for delivery of their products to customers. The main issue is not only to deliver a machine tool as such; supporting instructions related to the technology of the cutting process on the machine tool are of great importance. When taking delivery, the customer can see a new machine tool that will produce by him specified work piece with a desired accuracy. In the proposed thesis, a development of a novel methodology of measuring vertical lathes for prediction of chosen geometrical parameters of work pieces is introduced. The main goal of this work has been to determine the influence of the geometrical accuracy of selected design groups of a vertical lath on the future geometric accuracy of the work piece. The proposed methodology has been developed and verified on a selected vertical lath SKIQ30 produced by TOSHULIN, a.s. For identification of chosen parameters of the vertical lath a measuring system using latest measuring technologies has been applied. The basic tool for measured data processing has been a set of statistic methods for prediction of behaviour of measured design groups of the machine. The foundation for statistical processing has been calculation of geometrical deviations obtained from algorithms designed for proposed measurement methodology. The proposed measurement methodology for vertical lathes has been divided into two parts. In the first part, the methodology of measurement and evaluation of linear axes is solved, where a measuring system Laser Track has been used. The employment of the system Laser Track turned out to be very suitable. Conclusions related to the accuracy of the measuring device have been drawn in the thesis. The second part of the proposed methodology is represented by observation and description of the rotating disk, where non-contact position transducers have been used. In the course of the doctoral dissertation it has been observed that the studied (with respect to the geometry) behaviour of the machine is significantly affected by the cutting conditions. To these belong the loading of the rotating disc by the mass of the work piece, angular velocity of the rotating disc and the operating time of the machine. Based on these observations it can be stated that for prediction of work piece features it is essential to know the behaviour of the machine tool in the whole range of the operating speeds and loading of the rotating disc. A part of the proposed methodology for measuring vertical lathes seems to be very suitable for a design of a diagnostic system that could be applied on large rotating disc. Furthermore, it is recommended to extend the doctoral thesis in order to develop a unit for compensation of geometrical errors on rotating discs of vertical lathes.
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Problematic of Fast Automatic Tool Change by Working Machinery
Pavlík, Jan ; Marek, Jiří (referee) ; Velíšek,, Karol (referee) ; Demeč, Peter (referee) ; Kolíbal, Zdeněk (advisor)
This dissertation thesis is focused on the problem of the Automatic Tool Change for milling centers, which is recently shown as a very current topic. The content of this work is to conduct a comprehensive research of various types of ATC depending on the type of machine, as well as research of the current tool interface relating closely with these problems. There was made a comprehensive analysis on the basis of data obtained by comprehensive research, from which both the main factors affecting this topic and the area dealed and developed by this work resulted. The most problematic area of machinery used nowdays for the Atomatic Tool Change was detected as manipulator provided the exchange between spindle and tool storage. Kinematic structure and design of individual elements affects very significantly the dynamics of the whole process of exchange of tools. Therefore, the work is focused on problematic of the manipulator. The main results of this thesis are constructional design of several types of manipulators, which were partly realized within the project 1.2.4 of Brno department of RCMT in the form of the testing stands. There was developed simulation models for selected types of manipulators which were verificated by measuring on the real stand. On the basis of abovementioned problem there was identified another key issue related not only to the exchange process but also with complex problem of service life of spindle. It is a grab force in the process of picking tools. The work outlines the possibilities for further research of these forces on the service file of spindle (especially on service life of bering groups of spindle).
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