Investigation of surface roughness in machining by single and multi-point tools

Zusatztext

The goal of the dissertation is to determine the expected roughness of surfaces cut by tools with various geometry; the description of the differences of the necessarily existing unevenness on a given surface, and the determination of the minimal and maximal value of the surface roughness. br> In order to achieve the above mentioned goals, one part of the work was to develop models and computer programs for the prediction of the surface roughness indexes for turning and face milling operations. The main basis for the calculations is the general mathematical model of the single-point: cutting tools. Three different methods are introduced in the dissertation based on this model: one which is based on pure analytical calculations, one which uses numerical methods, and one which is based on CAD modelling. In-depth description of the methods is provided together with the introduction of the developed software. The main emphasis is placed on the determination oftheoretical roughness on surfaces machined by face milling. The worked-out method allows taking the run-outs of the multi-point cutting tools into consideration, and the application ofvarious insert geometries is also possible. After that, the developed CAD-based modelling is introduced which allows the calculation of 3D theoretical roughness indexes in face milling. Cutting experiments were performed for dual purpose: in one hand to show the differences between the calculated theoretical values and measurement data, and on the other hand to formulate the relations between these two datasets. Thus the expected value of the roughness can be calculated with the given cutting conditions. The experimental conditions are introduced and then the results of the practical investigations are presented. The comparisons of the obtained results have proven that the modelIed and the measured surfaces are in good correlation with each other. Finally the calculated regression constants and coefficients are presented wh ich allows the prediction of the expected value of the surface roughness.

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