Wyniki wyszukiwania - Biblioteka Nauki

1

Innovative Design and Machining Verification of a Dual-Axis Swivel Table for a Milling Machine

100%

Lin W.-Z. , Xiao J.-X. , Lin Y.-C. , Chang B.-W. , Hung J.-P.

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tom Vol. 18, no 1

306--319

EN

This study was aimed to develop a dual-axis rotary table for small and medium-sized five-axis milling machines. The rotation and tilting axis of swivel table were respectively driven by servo motor with gear reducer to achieve low speed, high torque, high rigidity and high precision machining capability. Essentially, the dynamic interaction between the work piece and the tool in the cutting process is an important factor that affects the machining performance, which also implies that the structural characteristics of the rotary table with the swiveling angle will affect the cutting performance of the five-axis machine. Therefore, at the design stage of a five-axis machine tool, it is a prerequisite to evaluate change of dynamic characteristics of the rotary module within the desired feeding range. To this purpose, this study employed the finite element method to analyze the dynamic characteristics of the rotary table under different configurations. In order to evaluate the application feasibility of the dual axis module on a milling machine, ISO S-shaped machining tests were carried out. Meanwhile, considering the influence of machining vibration on the surface quality of the work piece, the vibration induced at spindle tool and rotary table were assessed for comparisons and used to evaluate the variation of machining vibration with the milling cycles. Based on various experimental results, it is confirmed that the proposed dual-axis rotary table has good structural dynamic characteristics with stable vibration features during a small batch production tests. Current results clearly demonstrate the potential and capability of the proposed dual axis rotary table in practical application and commercialization.

2

Badania modalne konstrukcji wsporczej pięcioosiowej frezarki zbudowanej na bazie robota równoległego

84%

Bednarz J.

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2014

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tom nr 6

1809-1818

PL

W artykule przedstawiono opis badań i wyniki analiz modalnych konstrukcji wsporczej pięcioosiowej frezarki, zbudowanej na bazie robota równoległego. Celem badań była identyfikacja częstotliwości i postaci drgań własnych układu przy wymuszeniu impulsowym, przed i po modyfikacji konstrukcji. Modyfikacja konstrukcji miała na celu poprawę jej sztywności poprzez wypełnienie profili stalowych kompozytem elastomerowym. Zakres badan obejmował: eksperyment modalny z wykorzystaniem wymuszenia impulsowego, estymacje parametrów modelu modalnego na podstawie wyników przeprowadzonego eksperymentu i opracowanie wyników badań. Układ wzbudzano wymuszeniem impulsowym, za pomocą młotka modalnego. Estymację parametrów modalnych poprzedziła analiza jakości danych pomiarowych, w oparciu o przebiegi zmierzone w punktach i kierunkach przyłożenia wymuszania, we wszystkich przeprowadzonych testach częściowych. Estymacja parametrów została przeprowadzona przy pomocy oprogramowania VIOMA. Zastosowano algorytm LSCF. Przeprowadzono zbiór procedur estymacji, z wyników których wybrano najbardziej reprezentatywne postacie drgań przy pomocy procedury konsolidacji modelu modalnego. Głównym celem prowadzonych badań było sprawdzenie jak zmieniła się sztywność konstrukcji wsporczej frezarki po przeprowadzeniu modyfikacji konstrukcji.

EN

The article presents the description and results of a modal analysis of a five-axis milling machine supporting structure, built on a parallel robot structure. The aim of the study was to identify the frequencies and mode shapes of the system at a forcing pulse, before and after modification of the structure. The modifications were designed to improve its stiffness by filling the supporting structure steel profiles with an elastomeric composite. The scope of research included: modal experiment with the use of force pulse, modal estimates of the model parameters based on the results of the experiment and research results. The system was excited with a force pulse, using a modal hammer. Estimation of modal parameters was preceded by the analysis of data quality, based on the waveforms measured in points and directions touchdowns enforcement in all conducted partial tests. Parameter estimation was carried out using VIOMA software. LSCF algorithm was used. A set of estimation procedures were conducted, the results of which were selected the most representative vibration forms using a consolidation procedures for the modal model. The main objective of the study was to determine stiffness changes of the milling machine supporting structure after the modification of the structure.

3

Investigation of the Dynamic Characteristics and Machining Stability of a Bi-rotary Milling Tool

84%

Hung J.-P. , Lin W.-Z.

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tom Vol. 13, no 1

14--22

EN

Bi-rotary milling head is the primary component of multiple-axis machine tool toward the multiply machining operation. The machining performance is greatly related to the structure characteristics and positioning precisions of the swivel head. This study was aimed at developing a bi-rotary milling head module, which is composed of a direct drive motor, cross roller bearings and motorized spindle unit. In order to evaluate the machining stability at the design phase, the dynamic characteristics of the rotary milling were first analyzed with finite element method. Especially, the variations of the dynamic characteristics of the spindle tool with the changing of the titling configuration of swivel axis were examined. In order to consider the accurate presentation of a spindle tool system and swivel mechanism, the bearings in the rolling components were also included in the finite element model and simulated with surface contact elements with adequate contact stiffness. The dynamic frequency response function of the spindle tool at different swinging positions were predicted for comparisons, which were further used to calculate the machining stability based on the machining mechanics. The current results show that the feeding direction and swinging positions of rotary milling head have a significant influence on the dynamic characteristics and machining ability of the spindle tool. The variations of the cutting depth with the swinging of A axis fall in the range of 11% to 40%, depending on the feeding direction and swinging angle. The analysis results are expected to clearly demonstrate the variation of the machining performance of the spindle tool under different milling configurations. The devised model and modeling approach can be applied to develop a five axis milling machine with desired dynamic and machining performance.