Effets du comportement de la machine et des paramètres d'usinage sur la topographie des surfaces obtenues par fraisage à grande vitesse avec des fraises à bout sphérique monoblocs

L’optimisation des paramètres de coupe en usinage à grande vitesse impose le passage à travers la modélisation des efforts de coupe en intégrant les erreurs d’usinage ainsi que l’analyse de la topographie. La présente étude porte sur l’analyse de l’effet des paramètres de coupe et des erreurs d’usinage sur la topographie des surfaces fraisées avec une fraise à bout sphérique monobloc. Pour y parvenir on a modélisé la géométrie de la fraise en tenant compte des erreurs d’usinage , la zone d’engagement outil-pièce et le calcul de la largeur et de l’épaisseur de coupe en tenant compte de la trace de la dent précédente afin de montrer l’effet des erreurs d’usinage sur les efforts de coupe. Une analyse de la topographie en fonction de tous ces paramètres et des erreurs d’usinage est réalisée en se basant sur une validation expérimentale

Experimental investigation of tool wear and its effect on TiSiN-coated ball-end mill geometry in high-speed milling

International audienceIn this paper, an experimental investigation was carried out in order to identify the tool life of sintered carbide ball-end mill based on spindle speed variation. The used tool is coated with titanium silicon nitride “TiSiN” which is a high-hardened and high heatresistant coat. Experiments were conducted on parallelepiped plane workpieces on AISI 4142 during high-speed milling. Two kinds of tests were realized, the first is a wear experiment using high cutting parameters in order to identify the wear criterion model as a function of the spindle speed. The second one is an accelerated wear experiment to develop an empirical model for the tool life. The research revealed that the tool life and wear criterion value decrease when increasing the spindle speed. It is observed that the wear increases linearly in the normal wear zone. Furthermore, the effect of tool wear on the ball-end mill geometry and the cutting parameters were also investigated. A noticeable variation was found on the effective radius of the tool which affect the tool geometry such as the direction angles of the elementary cutting edge which results in the variation of the cutting parameters. An important effect also of the effective radius variation on the cutting speed was proved

Cutter-workpiece engagement calculation in 3-axis ball end milling considering cutter runout

In order to obtain desired surface quality, the machining parameters such as feed per tooth, spindle speed, axial and radial depth of cut have been selected appropriately by using a process model. The surface quality and the process stability are related to cutting forces which are more influenced by the instantaneous chip thickness and the cutter-workpiece engagement (CWE) region. To reach a high accuracy in cutting forces calculation it is primary to determinate the start and the exit angles on the (CWE) region. Unlike previous studies which calculated the (CWE) numerically. This paper proposes an analytical model to calculate the (CWE) region by determining the cutting instantaneous flute entry and exit angles. These locations are calculated according to the heights of axial depth of cut. The second proposed approach is to calculate the instantaneous undeformed chip thickness. These solutions are used to calculate accurately the cutting forces in the case of the 3 axis milling operations. To validate the model, a mechanistic cutting forces model was simulated and compared to the measured one. A good agreement between them was prove

An approach to modeling the chip thickness and cutter workpiece engagement region in 3 and 5 axis ball end milling

The determination of the chip thickness in 5-axis ball end milling is most fundamental to calculate the cutting force which affects the machining stability and surface quality. In the 5-axis ball end milling, adding to the parameters of the 3-axis milling we have two important parameters which are the tilt and the lead angles. They affect the engagement region and the chip thickness and modify the cutting forces. Based on the true tooth trajectory and the machining surface geometries, this paper presents a new analytical model of the cutter workpiece engagement (CWE) region and the instantaneous undeformed chip thickness in three and five axis ball end milling. To validate the model a mechanistic force model was used, the simulation was compared to the measured one and a good agreement between them was proved

Effects of machine behavior and machining parameters on the surface topography in high-speed ball-end milling

L’optimisation des paramètres de coupe en usinage à grande vitesse impose le passage à travers la modélisation des efforts de coupe en intégrant les erreurs d’usinage ainsi que l’analyse de la topographie. La présente étude porte sur l’analyse de l’effet des paramètres de coupe et des erreurs d’usinage sur la topographie des surfaces fraisées avec une fraise à bout sphérique monobloc. Pour y parvenir on a modélisé la géométrie de la fraise en tenant compte des erreurs d’usinage , la zone d’engagement outil-pièce et le calcul de la largeur et de l’épaisseur de coupe en tenant compte de la trace de la dent précédente afin de montrer l’effet des erreurs d’usinage sur les efforts de coupe. Une analyse de la topographie en fonction de tous ces paramètres et des erreurs d’usinage est réalisée en se basant sur une validation expérimentale.The optimization of the cutting parameters in high-speed machining requires the consideration of the machining errors in the modeling of the cutting forces and the surface topography. Therefore, the present study deals with the analysis of the effect of cutting parameters and machining errors on the surface topography of milled surfaces with a ball-end mill. The tool geometry was modeled taking into account all the machining errors such as runout, bending, vibrations and wear. Then, the Cutter Workpiece Engagement region 'CWE ', the cutting width and the uncut chip thickness were modeled taking into account the trace of the previous tooth. Subsequently, thermomechanical modeling of cutting forces in the milling process with a ball-end tool is made considering these errors. Finally, an analysis of the topography according to all these parameters and machining errors was carried out based on experimental validation

Geometric modeling of the rubbing zone limits in 3-axis ball-end milling

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Effect of ball end mills errors on cutting forces

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