Wyniki wyszukiwania - BazTech

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On-machine measurement systems for high-precision workpieces, produced on five-axis milling machines

Zeleny J., Janda M.

Journal of Machine Engineering

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2008

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Vol. 8, No. 1

11--18

EN

The paper describes control systems for measuring of complex workpieces machined on numerically controlled machine tools. The area is called "on-machine measurement" (OMM) and means measuring of workpieces still placed in the working space of the NC machine immediately after the NC machining operation. Measuring is performed by a touch probe inserted into the machine spindle and the movements of the probe are programmed to touch the workpiece in pre-selected points of machined surface. This makes it possible to compare the measured points with corresponding points of the CAD model and thus evaluate deviations in the normal direction between the ideal and real surfaces. In the RCMT - Research Center of Manufacturing Technology in Prague, the research of on-machine measurement methods has been performed with the aim to apply this technology for measuring of very precise and complex workpieces, produced on five-axis milling machines. Different types of control systems for three-axis, five-axis and "three and two" axis on-machine measurements have been analysed, verified and tested. The task has been solved as a part of the HARDPRECISION European project with the aim to verify possibilities in replacing application of conventional coordinate measuring machines (CMM) by on-machine measurements methods even for very complex parts with hardly accessible measured surfaces.

2

Analysis and simulation of nonlinear self-excited vibrations in turning

Zeleny J., Repak T., Fojtu P.

Journal of Machine Engineering

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2008

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Vol. 8, No. 4

68--79

EN

Commonly applied theories of self-excited vibrations in machine tools are prevailingly based on frequency domain analysis of linear models and are devoted in most cases only to evaluation of stability limits of strictly linear systems. In this way, the behaviour of more stable or more unstable systems cannot be studied and analyzed. Certain important nonlinear effects cannot be studied as well for limitations connected with classical representation of systems only in the frequency domain. Evaluation of stability by analysis of nonlinear systems in time domain has not been applied until now. The paper shows a new approach based on interpretation of the self-excited vibration systems as nonlinear servo-systems. With this approach, linear and nonlinear systems of any degree of stability can be studied by combination of frequency and time-domain methods. This can considerably contribute to better understanding of complex phenomena in various regimes and special situations.

3

Automatic on-machine measurement of complex high-precision parts

Zeleny J., Janda M.

Inżynieria Maszyn

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2008

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R. 13, z. 3/4

83-90

EN

Milling spindle with inserted 3D tensometric touch probe were applied for on-machine inspection of highly precise parts produced on three- and five-axis milling machines equipped with linear motors and direct rotary drives. New methods of CNC control of angular NC axes during measurement were developed for parts containing hardly accessible surfaces. In-process calibration of multi-directional accuracy of probes has resulted in submicron sensitivity and highest absolute accuracy of on-machine measurements.