Theoretical Considerations Concerning the Determination of Value for the Critical Speed of the Ball Screws from Numerical Axes Structure
Journal Title: RECENT - Year 2009, Vol 10, Issue 27
Abstract
A servo performance limit of the numerical axes from the numerically controlled machine tool structure is the first natural frequency of their mechanical structure, because this limits the maximum amplification on the system control loops. For this reason, it is very important the appraisal for the critical speed of the ball screws from the numerical axes structure made by a more exactly calculation procedure. Generally, the ball screw manufacturers offer in the instruction manuals, charts for the ball screw critical speed appraisal dependent on dimensions and type of their pillows. This method for the appraisal of the critical speed value is not a very accurate one, so that, while the feed velocities achieved by the numerical axes of the numerically controlled machine tools are increased, a more exactly calculation method is necessary for the optimization of the amplification parameters for the control loops. This paper aims to elaborate a calculation method for the critical speed of the ball screws from the numerical axes structure, as critical bending speed, which corresponds to one of the natural resonant frequencies, the first natural resonant frequency of the assembly consisted of the ball screw and its pillows being considered as significant frequency in this case.
Authors and Affiliations
Dumitru DUMITRU, Eugen STRĂJESCU
Keywords
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