High Precision Rotary Table Used on Milling Machining Centres

The latest milling machining centres have in their structure a rotary table which is used for machining up to 5 faces of a workpiece using only one set-up. In order to meet the requirements of a workpiece, that are more and more precise, it is recommended to increase the positioning accuracy of the machine tool table and also the number of indexing points. In this paper we present a new rotary, palletizing table which is provided with 360000 indexing positions and at every 4x90 degrees the indexing precision is +/- 1 ''. This solution can be integrated in the structure of milling machining centres which adopt pallets with the nominal size from 400x400 mm to 800x800 mm. The table rotation axis is closed-loop controlled and is actuated by a servomotor with variable speed. The presence of speed and position control in the table's structure assures the obtaining of high quality indices superior to classic feed systems. The kinematic feed chain has in its structure a duplex worm gear which guarantees the transmission without mechanical clearances. Also the table is provided with a high precision pallet positioning and clamp/unclamp mechanism which attains a position repeatability of +/- 2 ''. The advantages of the presented solution find themselves in the general characteristics of the machining centre, providing it with new performances in increasing the precision of the machined workpiece.