Identification of optimal process parameters in twin-spindle machining

为了提高生产能力，双主轴加工中心在工业中得到广泛应用。这样的机器配置在经济上是有利的，因为在近似相同的占地面积下生产率增加，并且仅可以实现适度更高的投资成本。然而，在实践中，去除率受到铣削过程的动态不稳定性的限制。在以前的研究项目由DFG在实验室机床（WZL）在RWTH亚琛大学的一个显着的影响，两个主轴的角度位置对彼此的过程稳定性可以被识别和证明。最佳的角度位置，使一个稳定的过程中，最大的切削深度取决于机器的结构和工艺参数的铣削过程。最佳角度位置的确定可以通过模拟加工过程或在机床上进行一系列实验性切削测试来完成。参数化模拟模型以及通过实验测试系列运行的努力是相当大的。由于确定稳定性图表或最佳角位置的高成本，在工业实践中通常不确定当前切割过程的稳定性极限。如果在批量生产的设置过程中发生再生包租，机器操作员通常会尝试通过改变过程参数来稳定过程。如果该过程在几次尝试中不能引起稳定的过程，则切削深度和生产率将降低。为了利用不同主轴角位置的潜力，必须开发一种过程，该过程允许根据当前过程自动确定刀具1和刀具2的最佳角位置。该研究项目的目标是开发一种方法和一种带有分析软件的测量设置，允许操作员在不了解机床动力学或颤振理论的情况下确定有效的工艺参数。因此，必须开发软件，用于分析发生的振动在相关频率范围内的振幅。与相应的角位移之间的切削工具，其中最低的振动振幅可以观察到在相关的频率范围内的过程中，被确定为有效的。

To increase the production capacity, twin-spindle machining centers are widely used in industry. Such a machine configuration is economically advantageous as productivity increase at approximately the same floor space and only moderately higher investment costs can be achieved. However, in practice, the removal rate is limited by the dynamic instability of the milling process. In a previous research project funded by the DFG at the Laboratory for Machine Tools (WZL) at RWTH Aachen University a significant influence of the angular position of the two spindles to each other on the process stability could be identified and demonstrated.The optimum angle position which enables a stable process with a maximum cutting depth is dependent on the machine structure and process parameters of the milling process. The determination of an optimal angle position can be done either through simulation of the machining process or series of experimental cutting tests on the machine. The effort to parameterize a simulation model as well as to run through the experimental test series is considerable. Due to the high cost for determination of stability charts or optimal angular positions, the stability limits for the present cutting processes are usually not be determined in industrial practice. If regenerative chartering occurs during the setup of series production, the machine operator usually tries to stabilize the process by varying the process parameters. If this procedure does not induce a stable process in a few tries, the cutting depth and thus the productivity will be reduced.To use the potential of the different spindle angular positions a procedure has to be developed that allows an automatic determining of the optimal angular position of tool 1 and tool 2 depending on the current process. The goal of this research project is to develop a methodology and a measurement setup with an analysis software, which allows an operator without knowledge of dynamics of machine tools or chatter theory to determine efficient process parameters. Therefore software has to be developed for analysing the occurring vibrations regarding their amplitudes in the relevant frequency range. The process with the corresponding angular displacement between the cutting tools, in which the lowest vibration amplitude can be observed in relevant frequency ranges, is identified as efficient.