Cast Iron And Mineral Cast Applied For Machine Tool Bed - Dynamic Behavior Analysis

Abstract

Cast iron and mineral cast are the materials most often used in the machine structural elements design (bodies, housings, machine tools beds etc.). The materials significantly differ in physical and mechanical properties. The ability to suppress vibration is one of the most important factors determining the dynamic properties of the machine and has a significant impact on the machining capabilities of a machine tool. Recent research and development trends show that there is a clear tendency to move away from the traditional iron casting to the mineral casting, due to better dynamic properties of the latter. However mineral cast as a structural material for the whole machine tools bed turns out to be insufficient due to its poor mechanical strength properties. The best solution should benefit from the advantages of the cast iron and mineral cast materials while minimizing their drawbacks. The paper presents numerical modal analysis of two lathe beds: the first one made of gray cast iron and the second one made of hybrid connection of cast iron and mineral cast. The analysis was conducted in order to determine the dynamic properties of two bodies of similar shapes made in the traditional (cast iron) and innovative hybrid (cast iron and mineral cast) technology. In addition, an analysis of the static structure rigidity of the two beds was performed. During the simulation studies it was found a significant increase in dynamic stiffness and static rigidity of the machine tool body made of hybrid connection of cast iron and mineral cast. The results of numerical simulations have confirmed the desirability of using hybrid construction because the dynamic properties of such a body are more advantageous in comparison with the conventional body made of cast iron.Keywords: cast iron, mineral cast, dynamic properties, modal analysis, machine tool bed Żeliwo oraz odlewy mineralne są materiałami konstrukcyjnymi najczęściej wykorzystywanymi w dziedzinie projektowania elementów strukturalnych maszyn (korpusy, obudowy, łoża obrabiarek). Te materiały znacząco różnią się pod względem zarówno właściwości fizycznych, jak i mechanicznych. Zdolność do tłumienia drgań jest jednym z najważniejszych czynników determinujących właściwości dynamiczne urządzenia i ma znaczący wpływ na możliwości obróbkowe maszyny technologicznej. Najnowsze badania oraz trendy rozwojowe pokazują, że istnieje wyraźna tendencja do odchodzenia od tradycyjnych odlewów żeliwnych w kierunku odlewów mineralnych, ze względu na lepsze właściwości dynamicznych tych ostatnich. Jednakże odlewy mineralne jako materiał konstrukcyjny na całe łoże obrabiarki okazuje się być niewystarczający ze względu na słabe właściwości mechaniczne. Najlepsze rozwiązanie powinno korzystać z zalet żeliwa i odlewów mineralnych, jednocześnie minimalizując wady obu materiałów. W artykule przedstawiono teoretyczną analizę modalną dwóch korpusów obrabiarki: jednego wykonanego z żeliwa szarego oraz drugiego wykonanego z hybrydowego połączenia żeliwa i odlewu mineralnego. Analiza została przeprowa...

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