Mathias Agmell - Academia.edu (original) (raw)

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Papers by Mathias Agmell

Research paper thumbnail of The mystery of missing feed force – the effect of friction models, flank wear and ploughing on feed force in metal cutting simulations

Underestimated feed force is a known systematic error in cutting simulations. It is considered a ... more Underestimated feed force is a known systematic error in cutting simulations. It is considered a consequence of inaccurate friction models, but there are indicators that friction is not the only reason for the error. In some cases, the value of Coulomb friction must be over 1.0 to compensate for the feed force and such values cause overestimated chip thickness for example. In turning, the ploughing force of the tool is affected by the feed velocity, which changes with the work diameter when cutting speed is constant. In addition, the edge geometry of the tool affect the ploughing force. In this paper, friction, edge geometry and the plough force are investigated with experiments and simulations to identify their effect on feed force.

Research paper thumbnail of Too sharp for its own good – Tool edge deformation mechanisms in the initial stages of metal cutting

Metal cutting simulations have become an important part of cutting tool design and the research i... more Metal cutting simulations have become an important part of cutting tool design and the research in the field in general. One of the most important aspects of modeling is the accuracy of the tool geometry. 3D microscopy is used for measuring the tool edge radius with good accuracy. However, especially with sharp tools, i.e. small tool edge radii, the measurements, no matter how accurate, are not much of a use, since the initial wear, or deformation is so fast in the first 1-30 seconds into the cutting, that the tool geometry is significantly different than the one measured from the new tool. The average tool life is often set to 15 minutes. Therefore, the cutting simulations that only predict the tool behavior in the first seconds of its lifetime are not very useful in predicting the process variables throughout the tool life. Simulations with creep and elastic-plastic material model however, can predict the initial deformation of the tool. This tool shape can be then used in rigid tool model to predict the process variables in the steady wear region of the tool life. This paper presents simulation model for predicting the initial tool edge deformation for WC-10%Co tool while machining AISI 304 stainless steel. The novelty in this approach is the simultaneous coupled calculation of contact surface temperature and stress and change of the tool shape.

Research paper thumbnail of The mystery of missing feed force – the effect of friction models, flank wear and ploughing on feed force in metal cutting simulations

Underestimated feed force is a known systematic error in cutting simulations. It is considered a ... more Underestimated feed force is a known systematic error in cutting simulations. It is considered a consequence of inaccurate friction models, but there are indicators that friction is not the only reason for the error. In some cases, the value of Coulomb friction must be over 1.0 to compensate for the feed force and such values cause overestimated chip thickness for example. In turning, the ploughing force of the tool is affected by the feed velocity, which changes with the work diameter when cutting speed is constant. In addition, the edge geometry of the tool affect the ploughing force. In this paper, friction, edge geometry and the plough force are investigated with experiments and simulations to identify their effect on feed force.

Research paper thumbnail of Too sharp for its own good – Tool edge deformation mechanisms in the initial stages of metal cutting

Metal cutting simulations have become an important part of cutting tool design and the research i... more Metal cutting simulations have become an important part of cutting tool design and the research in the field in general. One of the most important aspects of modeling is the accuracy of the tool geometry. 3D microscopy is used for measuring the tool edge radius with good accuracy. However, especially with sharp tools, i.e. small tool edge radii, the measurements, no matter how accurate, are not much of a use, since the initial wear, or deformation is so fast in the first 1-30 seconds into the cutting, that the tool geometry is significantly different than the one measured from the new tool. The average tool life is often set to 15 minutes. Therefore, the cutting simulations that only predict the tool behavior in the first seconds of its lifetime are not very useful in predicting the process variables throughout the tool life. Simulations with creep and elastic-plastic material model however, can predict the initial deformation of the tool. This tool shape can be then used in rigid tool model to predict the process variables in the steady wear region of the tool life. This paper presents simulation model for predicting the initial tool edge deformation for WC-10%Co tool while machining AISI 304 stainless steel. The novelty in this approach is the simultaneous coupled calculation of contact surface temperature and stress and change of the tool shape.

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