p. 63-68

 

Profiling of the planing tool for cycloidal worms machining

– CAD method versus analitycal method 

 

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Gabriel FRUMUŞANU^1,*, Silviu BERBINSCHI², Nicolae OANCEA³

 

¹⁾ PhD, Prof., Manufacturing, Robotics & Welding Engineering Department, “Dunărea de Jos” University, Galaţi, Romania

²⁾ Assistant Prof., Manufacturing, Robotics & Welding Engineering Department, “Dunărea de Jos” University, Galaţi, Romania

³⁾ PhD, Prof., Manufacturing, Robotics & Welding Engineering Department, “Dunărea de Jos” University, Galaţi, Romania

 

 Abstract: Cycloidal worms are helical-cylindrical surfaces, having a constant pitch. They are used in helical pumps construction, usually as driving screws. This paper introduces a new method for profiling a helical-cylindrical surface, reciprocal enwrapped to the cycloydal worm flanks, developed under CATIA graphical environment. New method quality is assessed by comparing the results of its application to the ones obtained in same purpose by using a numerical method, grounded on the fundamental theorems of the enwrapped surfaces. The comparison is illustrated through numerical examples.

 

Key words: planning tool profiling, CAD method, analytical method, cycloidal worm machining, helical cylindrical surface.

 

p. 69-76 

 

KNOWLEDGE BASED ENGINEERING AND MODERN CAE FOR SORTING SYSTEMS

 

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Christian LANDSCHÜTZER^1,*, Matthias FRITZ², Dirk JODIN³

 

¹⁾ Ass.Prof. Dipl.-Ing. Dr.techn., TU Graz, Institute of Logistics Engineering, Graz, Austria

²⁾ Dipl-Ing., PhD candidate, TU Graz, Institute of Logistics Engineering, Graz, Austria

³⁾ Univ.-Prof. Dr.-Ing. habil., head of Institute, TU Graz, Institute of Logistics Engineering, Graz, Austria

  

Abstract: Focusing on modern engineering technologies – as known from automotive sector – the authors will present two promising approaches to straighten (CAD)-development tasks for sorting systems.

As sorting systems are highly customized products, there are lots of repeating tasks, which steal creativity potential from the design engineer for so called “donkey work”. Here the KBE approach is presented as a powerful instrument in the use of system design, without automating every single detail, but interconnecting available parametric models with layout planning. Different views on engineering task automation are made to make accurate biddings in an early design stage. The authors introduce their KBx approach and will bring insights in ongoing research, to handle KBE and KBx tasks with software, using the xKBE-methodology, that brings together data, information and knowledge from various sources in the desired quality at the right stage in the developing process.

To boost sorting capacity the exact knowledge of the physical behaviour of sorting goods is essential. Sorting system development is highly empiric and therefore time consuming and expensive. CAE techniques offer a wide range of parameter variations within a validated model, to search for optimization potentialities such as minimizing the distance between the good, ensuring correct handling anyway. The authors will present a Multibody Simulation of a tilt-tray sorter which is used for improved unloading point design. An overview over CAE techniques complements the paper.

 

Key words: Knowledge-based engineering, CAE, Multi Body Simulation, sortation system, tilt tray sorter.

 

p. 77-82 

 

MEMS MANUFACTURING AND RELIABILITY 

 

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Titu-Marius BĂJENESCU^1,*, Marius BÂZU²

 

¹⁾ Prof., Reliability Consultant, C. F. C., La Conversion, Switzerland

²⁾ PhD, Head of Reliability Laboratory, IMT-Bucharest, Romania

  

Abstract: The Micro Electro Mechanical Systems (MEMS) are among the most promising areas in future computer and machinery, the next logical step in the silicon revolution. But the MEMS industry is currently at a much more vulnerable position than it appears, regardless of how wonderful its future may looks like. A full understanding of the physics and statistics of the defect generation is required to investigate the ultimate reliability limitations for MEMS. Biggest challenge: cost effective, high volume production. Within MEMS technological expansion, device manufacturing costs, failure and long-term performance reliability are critical issues that have to be resolved using basic probabilistic design methodologies which are largely unexploited by industrial companies at the mature innovation level. There are a number of factors that contribute to the reliability of MEMS: packaging (in particular, in bonding and sealing), material characterization relating to operating and environmental conditions, credible design considerations, the techniques for mitigating intrinsic stresses/strains induced by fabrications and testing for reliability are a few of these factors. The reliability aspect includes both the electronic and the mechanical parts, complicated by the interactions. Reliability is a critical issue in any industrial and consumer product development. MEMS devices are becoming essential components of modern engineering systems and their reliability is of particular importance in applications where their failure can be catastrophic and devastating.

 

Key words: fabrication, failure mechanisms, failure analysis, MEMS, packaging, reliability.

 

p. 83-88 

  

NUMERICAL STUDY ON DYNAMIC BEHAVIOR OF BORING BAR OF UNEQUAL BENDING STIFFNESS

 

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Abdelghafour BOURDIM^1,*, Abed MEGHDIR², Abdelkrim BOUIZEM³

 

¹⁾ Doctor, EOLE Laboratory, department of mechanical engineering, faculty of technology, University of Tlemcen, Algeria

²⁾ Doctor, Institute of Maintenance and industrial security, University of Oran Es-senia, Algeria

³ Doctor, EOLE Laboratory, department of mechanical engineering, faculty of technology, University of Tlemcen, Algeria

  

Abstract: The effects of tool tip orientation with respect to principal axis of non circular boring bar, on the stability of self-excited regenerative chatter vibration are numerically and experimentally investigated. The principal formulation of the problem is based on the finite element method and the resolution of the differential equations governing the vibratory movement of the boring bar use “Theta Wilson” method.  The superposition of relative displacements of the cutting tool tip, obtained for various orientations of the tool with respect to their principal axes, in curves of lissajoux characterizes the elliptic trajectory of the  cutting tool tip while machining. It is clearly shown that there exist a couple of frequency and orientation angle of the boring bar making  it possible to delay considerably the appearance of the phenomenon of  chattering, there also  existed other couples of angles and  dangerous frequencies corresponding to the proper modes of the bar. Results of the numerical simulation of the boring bar motion are successfully confirmed by experimental investigations.

 

Key words: chatter vibratio, regenerative chatter, dynamic stability, boring process, wedging angle.

 

p. 89-92 

 AUGMENTED REALITY TECHNOLOGY APPLICATIONS

 

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Jozef NOVAK-MARCINCIN^1,*, Miroslav JANAK², Jozef BARNA²

 

¹⁾ Prof., Ing., PhD., professor, Faculty of Manufacturing Technologies, Technical University of Kosice, Presov, Slovakia

²⁾ Ing., PhD., assistant, Faculty of Manufacturing Technologies, Technical University of Kosice, Presov, Slovakia

 

 Abstract: Augmented Reality (AR) is a growing area in virtual reality research. The world environment around us provides a wealth of information that is difficult to duplicate in a computer. This is evidenced by the worlds used in virtual environments. Either these worlds are very simplistic such as the environments created for immersive entertainment and games, or the system that can create a more realistic environment has a million dollar price tag such as flight simulators. An augmented reality system generates a composite view for the user. It is a combination of the real scene viewed by the user and a virtual scene generated by the computer that augments the scene with additional information.

 

Key words: Augmented Reality, Virtual Reality, Augmented Reality applications.

 

 

p. 93-98 

 

OPTIMIZATION OF THE ROBOT SPACE TRAJECTORY BY USING KINEMATICS, DYNAMICS, INTELLIGENT DAMPER AND PROPER NEURAL NETWORK

 

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Adrian OLARU^1,*

 

¹⁾ Prof., PhD, Machines and Manufacturing Systems, University POLITEHNICA of Bucharest, Bucharest, Romania

 

Abstract: In the robotics field one of the more important is the optimization of the space trajectory of the tool center point (TCP) without the undesired frequencies of the vibrations. The paper shows one new optimizing method by controlling the robots space trajectory by using the direct and inverse kinematics, direct and inverse dynamics, desired optimal Fourier spectrum and proper neural network. The proper neural network was established after the assisted research of the dynamic behavior, by trying to use some known networks type. The better solution of the neural network design, for solving the inverse kinematics and direct dynamics problems with the final goal of obtaining quickly the convergence process of the space trajectory and the Fourier target spectrum with the minimum errors without some of the frequencies of the spectrum was established by using the LabVIEW proper instrumentation, after the assisted research of all network parameters like the hidden layer data, amplifier gain, time delay and position in the network structure, recurrent links and number of neurons in each of all three used layers. The Sigmoid Bipolar Hyperbolic Tangent with Time Delay and Recurrent Links SBHTNN (TDRL) neural network type was proposed and used. The complex controlling of the space trajectory was made by using three neural networks of the same type: the first one to solve the inverse kinematics problem, the second for the direct dynamics problem by using some output data from the first one and the third one to establish the magnetorheological damper current intensity. All obtained results were verified by applying the simulation with LabVIEW instrumentation. Finally we obtained one optimal complex controller that can optimize the kinematics, dynamics and vibrations with trajectory errors smaller than 2%. The proper neural network, the controller design, the results and the virtual LabVIEW instrumentation could be used in many other mechanical applications.

 

Key words: space trajectory, inverse kinematics, direct dynamics, intelligent damper, neural network, virtual LabVIEW instrumentation. 

 

 

p. 99-104 

 

Gait analysis in cerebral palsy using VICON system

 

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Raluca Dana TUGUI ^1,*, Dinu ANTONESCU², Mircea Iulian NISTOR^3, Doina BUCUR⁴, Sorin KOSTRAKIEVICI⁵

 

¹⁾ Emergency Hospital Professor Agrippa Ionescu, Bucharest, Romania

²⁾ PhD.,Prof. Hospital of traumatology and orthopaedics Foisor, Bucharest, Romania

³⁾ assist., Department of Mechatronics & Precision Mechanics, University “Politehnica” of Bucharest, Romania

⁴⁾ lector., Department of Mechatronics & Precision Mechanics, University “Politehnica” of Bucharest, Romania

⁵⁾ PhD, Assoc. Prof., Department of Mechatronics & Precision Mechanics, University “Politehnica” of Bucharest, Romania

  

Abstract: Gait is a cyclical event, and Perry described it for the first time. The gait has two phases: stance (60%) and swing (40%), each divided, so stance phase includes pre swing, terminal stance, mid stance, loading response and initial contact, and swing phase includes terminal swing, mid swing and initial swing (Fig. 1). The stance phase allows body support while swing phase allows limb movement. During the researching we used Vicon system with MX Camera and MX Ultranet HD Cemra. The MX Ultranet HD provides the following functions in an MX system: supplies power, synchronization, and communications for up to 10 connected MX Cameras, supplies direct synchronization out (sync out) functionality for up to eight third-party Gigabit Ethernet cameras, and supplies power.

 

Key words: gait analysis, VICON, kinematics, cerebral palsy.

 

 

p. 105-110 

Manufacturing Technology for a New Type of Profiled Rotor Used by a Rotating volumetric pump

 

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Daniel Besnea¹, Nicolae Băran^1,*, Antonios DETZORTZIS², Antoaneta BĂRĂSCU²

 

¹⁾ Prof., Department of Mechanical Engineering and Mechatronics, POLITEHNICA University of Bucharest, Bucharest, Romania

²⁾ PhD, Department of Mechanical Engineering and Mechatronics, POLITEHNICA University of Bucharest, Bucharest, Romania

 

Abstract: The paper presents the sketch and the functioning principle of the rotating volumetric pump; a computation relation is established for the theoretical volumetric flow transported by the pump. The paper presents a mathematical model that establishes the coordinates (x_i, y_i) of the outline of a profiled rotor. A software that computes these coordinates is developed for a series of rotor dimensions. Based on these coordinates, the 3D model of the rotor is built using the software package CATIA V5. An appropriate post-processor generates a NC Code program written in ISO language, in order to manufacture the rotor on a vertical CNC center. Finally, the operation sheet regarding the design and manufacturing of the profiled rotor is presented. The demonstration model of the profiled rotor will integrate the construction of a rotating volumetric pump.

 

Key words: rotating piston, profiled rotors, rotating pump.

 

 

p. 111-114 

 

BRAYLLE SCREEN FOR VISUALLY IMPAIRED

 

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Dimitar KARASTOYANOV^1,*, Stanislav SIMEONOV², Todor PENCHEV³

 

1Assoc. Prof., Ph. D., Head of Dept., Institute of Inform. and Commun. Technologies, Sofia, Bulgaria

2Assoc. Prof., Ph. D., Head of Dept., Burgas Technological Unuversity, Burgas, Bulgaria

3Assoc. Prof., Ph. D., Head of Dept., Technical University-Sofia, Sofia, Bulgaria

 

Abstract. The graphical interfaces based on visual representation and direct manipulation of objects made the adequate use of computers quite difficult for people with reduced sight. The main scientific aim here is: a concept for development, design and manufacture prototype of combined tactile-voice interface facilitating and allowing visually impaired people work with computers regardless of the user interface or operation system and oriented to graphical surfaces. Static force characteristics of recently developed permanent magnet linear actuator for driving a needle in Braille screen are presented.

 

Keywords: Actuators, permanent magnets, tactile-voice interface, protoype, Braille screen.

 

 

p. 115-120  

 

DESIGN AND RAPID MANUFACTURING OF PATIENT-SPECIFIC SPINAL SURGICAL GUIDES: A SURVEY

 

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Diana POPESCU^1.*, Dorel Florea ANANIA², Cătălin Gheorghe AMZA³, Dumitru Titi CICIC⁴

 

¹⁾ Lecturer, PhD, Machine and Production Systems Department, University Politehnica of Bucharest, Bucharest, Romania

²⁾ Lecturer, PhD, Machine and Production Systems Department, University Politehnica of Bucharest, Bucharest, Romania

³⁾ Assistant Prof, PhD, Materials Technology and Welding Department, University Politehnica of Bucharest, Bucharest, Romania

⁴⁾ Lecturer, PhD, Materials Technology and Welding Department, University Politehnica of Bucharest, Bucharest, Romania

 

Abstract: The approach of customizing the surgical instrumentations and using them along with computer-aided surgical planning and advanced imagining techniques for increasing the accuracy and reliability of surgical procedures represents a trend in the medical field. It implies cooperation between engineers and medical specialists (radiologists, surgeons, etc.) for all the process steps: computer tomography/magnetic resonance imaging (CT/MRI) scanning of the patient, medical modelling of the anatomical areas of interest, planning surgery and designing the guide, choosing the material and manufacturing process, building the guide, sterilizing and using it in the operation room. Patient-specific guides can mach exactly patient bone structures and help materializing the planned trajectory for drilling, tapping or cutting. Therefore, these guides improve accuracy of the surgical procedure, helping the surgeons to better orient during intervention, decreasing the surgery time, costs and risks of infections. The main objective of the current paper is to present a review of different patient-specific guides used for pedicle screws insertion in human spine. The paper investigates the design criteria (anatomical landmarks system, stability, precision, unique placement, etc.), material and Rapid Manufacturing issues related to this application field and presents critical views on different surgical guides designs. Based on this analysis, several proposals for improving the spinal drill guides placement accuracy are presented.

 

Key words: rapid prototyping, design, surgical guides, survey, accuracy, pedicle screws, spine.