Papers by Keyword: Vertical Machining Center

Abstract: Taking a vertical machining center as an example, thermal characteristics of the spindle system were researched by finite element simulation and experimental test. Firstly, temperature field and thermal deformation of the spindle system were simulated considering boundary conditions of the finite element model, such as heat sources, convective heat transfer coefficients and thermal contact resistances between joints. Accuracy of the simulation was verified compared with test. The results shows that key areas of temperature rise locate at spindle bearing; thermal deformation of Y and Z directions are large; thermal characteristics of the spindle system has little influence on other parts. Thermal characteristics of the spindle system were optimized by changing structures and sizes of the cooling passage located at the headstock, and effectiveness of the optimization was verified by finite element simulation. The research results provide guidance for thermal characteristic simulation and optimization of a machining center.

Abstract: The effect of geometric error on machining accuracy was researched by multi-body system theory, as well as homogeneous coordinate transformation method. Taking a vertical machining center as example, topological structure of the machine tool was described by lower body array. Lower body array of the machining center, motion freedom between adjacent bodies and geometric errors of the vertical machining center were analyzed. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having influence on the machining accuracy were identified. The research results provide guidance for analyze of geometric errors on machining accuracy.

Abstract: This paper presented a real-time measuring method of temperature fields and thermal deformations in vertical machining center. And a FEA model including the thermal contact resistance at interface for evaluating the temperature distribution and tools deformation in vertical machining center (VMC) was established. Compared with the experiment results, it is shown that the new model is much more accurate than the traditional model without considering thermal contact resistance at interface.

Abstract: A new evaluation system based on the optimal degree evaluation method and combined with the comprehensive optimal degree evaluation method and the extensible optimal degree evaluation method is put forward in this paper, as an effective means in conducting the comprehensive multi-expert optimal degree evaluation to eliminate the convergences or conflicts that may occur in other evaluation methods while choosing measurement conditions. Meanwhile, the on-line optimal degree evaluation system developed on this theory is discussed in this paper too and proves its correctness by an application example of vertical machining centers.

Abstract: According to the new profiling characteristic of carbide pinion cutter with convex curved rake face, the verifying experiment for principle of processing method is done on the four axis vertical processing center. According to the experiment result, special machining equipment of convex curved rake face of pinion cutter is designed and developed, position of each axis and motion relationship is ascertained, tool path position of CNC machining is solved, path fitting of grinding wheel machining is done, machining experiment of pinion cutter with convex curved rake face is done by using the developed processing machine, The experiment result shows that the designed machining method and developed machine are proper for machining requirements, changed tendency curve of surface roughness is obtained, the range of cutting parameters is ascertained for getting better surface roughness.

Abstract: — High speed machine tool is one of the basic needs in catering to a wide range of machining parameters with tight tolerance band. In high speed machine tool many key factors like geometric, cutting force and thermal errors decides the performance of the machine. However amongst these three, error due to thermal deformation is an important factor in influencing the accuracy level of component produced. A survey amongst Indian machine tool manufacturers reveals that there is a strong need to infuse recent technological developments in thermal error prediction and derive methodologies to minimize the same in high speed machine tool. This paper attempts snapshots of a review relating to the errors causing thermal deformations and the modeling techniques developed by researchers and practitioners globally in present scenario. The conclusions made at the end of this paper may not give the full solutions to the problems relating to thermal error but, gives a broad perspective for the Indian machine tool manufacturers’, practitioners as well researchers in India to look in to the research relating to thermal error modeling, analysis and corrective measures.

Abstract: Stiffness analysis plays an important role in the optimization of the machine tool. By analyzing the static stiffness, dynamic stiffness and natural frequency of the key components, we discussed how to improve static and dynamic performance of the whole machine. Through the finite element analysis method, weak parts of the vertical machining center are firstly identified based on static stiffness analysis. Due to the purposes of increasing the stroke in Y-direction, improving the whole machine stiffness and without increasing the whole machine weight, optimal designs are carried out mainly on the structures of the spindle box and the column. And the performance of the parts and the whole machine before and after optimization is compared by testing whether the stiffness is improved or not. We also conducted experiments, and the results are consistent with the results of finite element analysis.