Papers by Keyword: High Speed Milling (HSM)

Abstract: For the purpose of investigating the effect on surface micro-topography of cutting parameters in high speed milling of SiCp/Al Composites, the high speed milling experiments were performed .The machined surface was measured by Taylor Hobson roughness tester and OLS3000 Confocal Laser Scanning Microscope. The acquired surface data was dealt with the three-dimensional roughness method. The three-dimensional root-mean-square deviation of the surface Sq and two-dimensional root-mean-square deviation Rq were compared. The effects of cutting parameters on three-dimensional roughness parameter were also investigated. The results showed that both feed rate and depth of cut have a little effect on the value of three-dimensional roughness parameter，and the cutting speed is the main affecting factor.

Abstract: A method to identify the effect of tool overhang on vibration signal is put forward to study machining process of large hardened steel automobile mold by wavelet energy spectrum. Firstly, collect the machinery vibration signal on milling by displacement sensor, then make a wavelet transform on time signal and calculate the wavelet energy spectrum of each frequency range. Finally, extract energy value of the right frequency by the method of homogenization. It is confirmed by experimental data that this method can recognize vibration feature and abnormal condition of cutting tool in high speed milling process of hardened steel fleetly and efficiently.

Abstract: In this paper, modal analysis of ball end mills is modeled by finite element to work out natural frequency and chatter model in tooling system and to calculate the limit curve of stability in single degree freedom system. The effect of cutter flute length and cutter tooth number on limit curve of stability in single degree freedom system is also discussed. The research results show that steady critical cutting depth of milling system declines while the cutter flute length increases, but the trend is not linear, which shows increase partly. An engineering optimization design is made on milling cutter geometrical parameters based on this conclusion.

Abstract: Aim at the uncertainty of vibration behavior in high speed ball-end milling hardened steel, carried out the experiment of high speed milling hardened steel and modal analysis of cutter, studied vibration behavior of cutter and workpiece, and established vibration behavior sequence of high speed milling hardened steel. Using gray system theory, did gray cluster analysis of vibration characteristics, explored the correlation among cutter vibration, workpiece vibration and surface roughness characteristics, put forward the method of characterizing vibration characteristics in high speed ball-end milling hardened steel. The results show that high frequency vibrations of cutter and workpiece are caused by the interaction of centrifugal and dynamic cutting force, the increase of cutter overhang enhances high frequency vibration of cutter, the characteristic of cutter vibration changes from low frequency vibration to interaction of low frequency vibration and high frequency vibration. Using cutters with different overhang, surface roughness of high speed milling hardened steel has similar characteristics, surface roughness in row spacing direction can characterize low frequency vibration of cutter, and surface roughness in feed can characterize resonance characteristic of cutter caused by high frequency vibrations of cutter and workpiece.

Abstract: Simulation models of both dynamic cutting forces and cutting temperatures considering effects of tool rounded cutting edge are established based on analysis of the influences of rounded cutting edge on high speed milling process. Influence law of tool rounded cutting edge radius on force and heat distribution in high speed milling hardened steel has been obtained according to the simulation results and also the simulation results have been verified by experiments. The results indicate that dynamic performances of high speed milling cutter in cutting hardened steel are directly influenced by rounded cutting edge radius, and the cutting forces fluctuated greatly with the variation of rounded cutting edge radius. Variations of rounded cutting edge radius have greater impact on cutting temperatures when the rounded cutting edge radius is less than 40μm. Cutting temperature rise slowly with the increase of rounded cutting edge radius when the rounded cutting edge radiuses are larger than 40μm. Simulation can precisely predict cutting temperatures and cutting forces considering influences of rounded cutting edge radius. Rounded cutting edge radius should be kept around 40~45μm for optimal cutting performances according to its influences on cutting forces and cutting temperatures in high speed milling hardened steel.

Abstract: High speed milling (HSM) on inclined plane is the basic process of die and mould. The dynamic characteristics of the process are experimentally studied by changing the factors as inclined plane, cutting parameter and feeding mode on the high speed milling machine tool. The angles of inclined plane, spindle speed, feed amount and cutting depth are evaluated by the parameters of cutting forces and vibration. The feeding of projection process limits the milling vibrations mainly from horizontal (X) and (Y) directions. The cutting force reaches the peak value when the angle of inclined plane is 45°. The radial cutting depth shows more effects than the axial cutting depth to cutting force and vibration. However, the axial cutting depth should keep a minimum value when using ball mill.

Abstract: SiCp/Al composites with high volume fraction and large particles are very difficult to machine. In this present study, high-speed milling experiments were carried out on the SiCp/Al composites by the three factors-levels orthogonal experiment method, and multiple linear regression analysis was employed to establish milling force model. The results show that the milling forces decrease with the increasing of the milling speed or increase with the increasing of the feed rate and depth of milling. The influence of milling depth on the milling forces in directions of x, y is the most significant, while the influence of the feed rate on the z-milling forces are the most significant. The calculation values from the milling force model are consistent with the experimental values. The results will provide a reliable theoretical guidance for milling of SiCp/Al composites, and it is feasible to predict the milling force during the milling of SiCp/Al by using this model.

Abstract: Prediction of surface roughness is an important research for machining quality analysis. In order to predict surface roughness in machining, increasing productivity under ensuring milling, the artificial neural network is introduced into milling area. To build high-speed milling surface roughness prediction model using BP neural network. Prediction results are compared with experimental value, which shows that this method can achieve better prediction accuracy. It has certain significance for parameters selection of high-speed milling and quality control of the surface.

Abstract: To compare the effects of different machining parameters on force in milling T10 hardened steel, the features of theoretical forces in up and down milling were analysised, and comparative experiments of milling force were made, whose results showed that the maximum component force in down and up milling was in the direction of radial cutting depth and feed respectively, moreover the maximum force in down milling was significantly greater than in up milling. Further orthogonal experiments of up milling and variance analysis were done, and it was found that the effects of rake angle, velocity, feed, axial cutting depth on milling force were significant at levels of α=0.05~0.0025. This study indicates that selecting milling parameters of up milling, high speed, low feed and axial cutting depth be better. This conclusion can be used as reference in designing milling scheme.

Abstract: High speed milling hardened mould steel (above HRC50) at pocket corner generates the cutting forces increase and vibration gets fiercely because of the sudden change of cutting direction. It will cause serious wear and possible breakage of cutting tool, and poor quality of parts. Hence, the need to select reasonable cutting parameters and adopt appropriate cutting strategies will help them to achieve their goal. In this paper, the effects cutting parameters including cutting speed, pocket corner angle, feed rate per tooth and radial depth of cut on cutting force and vibration are studied. The results show that sharper pocket corner results in the increase of cutting force and makes vibration strong. Cutting force increase with the increase of cutting speeding, feed per tooth and radial depth of cut. The optimum of cutting speed leads to the decrease of vibration. It is proposed that cutting parameters should be optimized to improve tool life and processing efficiency.