4 research outputs found
Finite element analysis on double-telescopic prop of hydraulic support
No full textAccording to Chinese coal industry standard MT313-1992 and European standard EN 1804-2-2001, using the modern CAE technology, based on the coupling meshing technology of structured grids and unstructured grids, the finite element strength analysis on 360-type double-telescopic prop is carried out under axial 1.5 times, axial 2.0 times rated load and off-center 0.3R 1.1 times rated load. The stability of the prop is studied using the buckling analysis. The results show that without regard to the dynamic load, the prop can bear 2.0 times axial pressure and 1.1 times off-center 0.3R pressure, and the stress distribution is even. Except the guide sleeve-I and the middle cylinder, other parts have high safety coefficient and can be optimized. The critical buckling load coefficient of the prop is 2.764, and the buckling instability of the type of prop will not happen if used under the rated working condition set by Chinese coal industry standard MT313-1992 and European standard EN 1804-2-2001. The paper can provide the basis for setting new related technology standard. DOI: http://dx.doi.org/10.11591/telkomnika.v11i1.189
Model-based Chatter Stability Prediction and Detection for the Turning of a Flexible Workpiece
No full textMachining long slender workpieces still presents a technical challenge on the shop floor due to their low stiffness and damping. Regenerative chatter is a major hindrance in machining processes, reducing the geometric accuracies and dynamic stability of the cutting system. This study has been motivated by the fact that chatter occurrence is generally in relation to the cutting position in straight turning of slender workpieces, which has seldom been investigated comprehensively in literature. In the present paper, a predictive chatter model of turning a tailstock supported slender workpiece considering the cutting position change during machining is explored. Based on linear stability analysis and stiffness distribution at different cutting positions along the workpiece, the effect of the cutting tool movement along the length of the workpiece on chatter stability is studied. As a result, an entire stability chart for a single cutting pass is constructed. Through this stability chart the critical cutting condition and the chatter onset location along the workpiece in a turning operation can be estimated. The difference between the predicted tool locations and the experimental results was within 9% at high speed cutting. Also, on the basis of the predictive model the dynamic behavior during chatter that when chatter arises at some cutting location it will continue for a period of time until another specified location is arrived at, can be inferred. The experimental observation is in good agreement with the theoretical inference. In chatter detection respect, besides the delay strategy and overlap processing technique, a relative threshold algorithm is proposed to detect chatter by comparing the spectrum and variance of the acquired acceleration signals with the reference saved during stable cutting. The chatter monitoring method has shown reliability for various machining conditions
