During the latest years, the robots<strong> </strong>that include mechanisms with Delta 3DOF parallel structure attracted the attention of the university research centers due to their unexploited potential. Besides the advantages given by the Delta 3DOF parallel structure, there is a series of disadvantages too. A significant disadvantage is the fact that the workspace is limited. Under these conditions, the studies on determining and improving the workspace got intensified lately. This work is presenting a study on determining the workspace of a parallel structure Delta 3DOF, by using a method that digitizes the angular position parameters of the active kinematical couplings.
Within the last years, the robots with parallel structure Delta 3DOF are used more and more in applications that require: transporting objects at high speed, transporting heavy objects, at a high accuracy. Because the parallel structures have a limited workspace, researches on the workspace amplified lately. This work is approaching the study of determining the workspace for a parallel structure Delta 3DOF. The method being used allows the numerical determining of the workspace shape, as well as its limits. At the same time, this method helps with establishing the methods for optimizing the workspace so that the largest possible workspace is provided.
In the field of manufacturing processes it is observed that the trend is to produce more and more faster, efficiently parts with high complexity, which involves using a high number of tools in the machining process. One of the main solutions for high speed and efficient manufacturing is based on the full automation of the entire manufacturing process. The automatic changing of the tools involved in the manufacturing process is carried out by the automatic tool changing mechanism, thus the auxiliary non-productive time consumed with the tool change is highly minimized. In this paper we present a novel automatic tool changer which is both simple and compact, and any milling machining center provided with chain or disc tool magazine can be equipped with. Also by adopting the use of this tool changing mechanism other subassemblies of the tool changing system, such as the tool transfer mechanism and the waiting position, are substituted by this changing mechanism. The auxiliary movements needed to bring the tool from the magazine into the waiting position are overlapped with the machining time, so that the total time for exchanging the tool in the spindle with the tool from the magazine is minimized.
The latest milling machining centres have in their structure a rotary table which is used for machining up to 5 faces of an workpiece using only one set-up. In order to meet the requirements of an 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° 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.
The increase of manufacturing accuracy on the machine tools depends mainly on the motion accuracy of the mobile elements as: rams, mobile tables, pads, etc., the accuracy that can be achieved, firstly, by minimization of the friction in the guide ways. Nowadays, this problem is solved by replacing the sliding friction with the rolling friction buy especially by using the hydrostatic guide ways, where the contact surfaces are separated by a continuos film of fluid supplied by a pressure. In this paper such recent constructive solutions of guide way are presented. The presented guide ways have as principal components made by porous materials. The use of the porous restrictors becomes a practical necessity due to the fact that the advantage of its applying are multiple as: reduction of the friction force, reduction of the required energy necessary to moves the mobile elements the wear reduction and the improvement of the working conditions. The paper presents a simple guide way system that contains a porous restrictor that may be successfully applied in multiple applications in the field of machine tool.
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