Papers by Keyword: High Speed Milling (HSM)

Abstract: TI6AL4V is a kind of hard-machining material, which has bad thermal conductivity, good chemical reactivity, little elastic modulus, great friction coefficient, severe work hardening, short cutter life, low machining efficiency and poor machining surface quality. To improve the machining efficiency, reduce machining cost and improve products quality, the cutting tool wear is the key factor affecting machining quality, machining efficiency and production safety. In this paper, a test system which takes TI6AL4V as the research object, and the dynamic milling force during the high speed milling as the detection signal is built for online tools wear prediction. The method of wavelet packet transform and neural network are presented to diagnose and predict the situation of tools wear. The practical example shows that this system has good practicability and could identify the tools wear states exactly through verification tests.

Abstract: Chatter problems occurring during high speed milling affect the quality of the finished workpiece and, to a lesser extent, the tool life and the spindle life. Therefore, the prediction of stable milling regions is a critical requirement for high speed milling operations. In this paper, a dynamic model of a high speed spindle system considering the multi-mode dynamics is elaborated for the purposed of stability prediction. A stability lobes diagram (SLD) shows the boundary between chatter-free machining operations and unstable processes, in terms of axial depth of cut as a function of spindle speed. These diagrams are used to select chatter-free combinations of machining parameters. The proposed method enables a new stability lobes diagram to be established that takes into account the effect of spindle speed on multi-mode dynamic behavior.

Abstract: High-speed milling (HSM) which is characterized as high productivity and low power consumption can be widely used in the manufacture industry. However, while the speed of spindle-tool reach the high speed range, the prediction of its stable milling faces more difficulties, as the gyroscopic effects become prominent. In this paper, a dynamics model of HSM system was set up considering the influence of gyroscopic moment due to high rotating speed of spindle-tool. Then a method was proposed by transforming time-varying stiffness system into fixed-step time invariant one. Finally the stability lobes diagrams (SLD) was elaborated. The results shows that the gyroscopic effects due to high rotating speed have non-negligible impact on the stability limitation, which must be considered for the predicting of stability limit in the high speed milling.

Abstract: Using the theory of axiomatic design, the optimization method of high speed milling cutter was investigated, and the optimization designs of teeth distribution and dynamic balancing were created by means of function decomposition and grey cluster analysis. Results showed that the method solved effectively the problem of parameters interaction and functions coupling in optimization design of cutter, the effects of simplifying design process and improving collaborative design were validated in development of cutter. Experiments indicated that the vibration in high speed machining aluminum alloy was depressed, the cutter held higher cutting stability, and its cutting performance met the optimization design requirement of high speed milling cutter.

Abstract: At present, the lack of the optimal cutting parameters of high speed milling is the obstacle to its widely application. In this paper, the simplified and rapid optimization method is proposed on high speed milling alloy thin-walled workpiece. The normal selection method of cutting tools and cutting conditions is put forward as the precondition of parameter optimization. The acquirement method of optimal parameters is presented. The maximal critical axial depths of cut at the different cutting conditions are achieved according to chatter stability theory. The materials removal rate is selected as the optimal objective. The optimal parameters are filtrated up and validated according to the constraint conditions including machining tool, cutting tools, surface quality and precision of the parts.

Abstract: TA15 (Ti-6.5Al-2Zr-1Mo-1V) is a close alpha titanium alloy strengthened by solid solution with Al and other component. A series of experiments were carried out on normal and high speed milling of TA15. The recommended tools for many years had been the uncoated tungsten carbide grade K. In this work, the tool life of coated carbide tools used in high speed milling of forging and cast titanium alloy was studied. Additionally, the wear mechanism of cutting tools was also discussed. Finally, surface integrity, including surface roughness, metallograph and work hardening, were examined and analyzed. The result shows that the surface quality of forging and cast machined by carbide cutter is similar, but the tool life of carbide in high speed milling of forging TA15 is longer than that in high speed milling of cast TA15.

Abstract: Complex surface mold has been widely used in various industries, and high efficiency and high quality can been achieved through high-speed CNC milling processing. Surface roughness including transverse and longitudinal roughness is an important criterion for mold quality. A high-speed milling experiment was performed in mold steel P20 using cemented carbide ball-end mill to investigate the surface roughness. The effects of process parameters on roughness including spindle speed, feed per tooth and radial cutting depth were examined, and an analysis on the mechanism for two kinds of roughness of different tool paths was finished. The experimental results show that the longitudinal roughness improve obviously while the spindle speed and the feed per tooth increase on the high-speed conditions, and the transverse roughness increase significantly when the radial cutting depth increases. And for a smaller roughness value, the tool path should be selected along the direction in which the curvature changes evidently.

Abstract: A new approach is presented to optimize the tool life of solid carbide end mill in high-speed milling of 7050-T7451 aeronautical aluminum alloy. In view of this, the multi-linear regression model for tool life has been developed in terms of cutting speed and feed per tooth by means of central composite design of experiment and least-square techniques. Variance analyses were applied to check the adequacy of the predictive model and the significances of the independent parameters. Response contours of tool life and metal removal rates were generated by using response surface methodology (RSM). The analysis results show that it is possible to select an optimum combination of cutting speed and feed per tooth that improves metal removal rate without any sacrifice in tool life.

Abstract: According to the theory of axiomatic design, to process function decomposition and grey cluster analysis of high speed milling cutter with indexable inserts, found the design matrix of cutter, and propose the design method of cutter based on high speed milling safety, stability and efficiency. High speed face milling cutter for machining aluminum alloy was developed according to design method and design matrix of cutter, experiment and fuzzy object element evaluation for cutting performance of cutter was accomplished. Results showed that there was not design loop which existed in the development of cutter, design process was simplified effectively, cutting energy of high speed milling cutter using axiomatic design method was dispersed, it held higher safety, cutting stability and efficiency, comprehensive cutting performance met the design requirement of high speed milling cutter.

Abstract: Using grey system theory in axiomatic design of high speed face milling cutter, the structural design method of cutter was investigated. The problem of parameter interaction and function coupling in axiomatic design of cutter was solved using the analysis method of grey cluster, and realized the reconstruction of design matrix and collaborative design planning. Results show that there is not design loop which exists in the development of high speed milling cutter, the effects of simplifying design process, shortening design cycle and improving collaborative design are validated in development of high speed face milling cutter. Results of experiments indicate that cutting vibration of high speed face milling cutter using structural design method is depressed, the cutters with higher safety and cutting stability, and their cutting performance have met the requirement of high speed milling.