Journal of Mechanical Engineering 56 (2010) 3

SV-JME-3-2010 in digital form »

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Practical Tracking Control of the Electropneumatic Piston Drive

Corresponding author - Dragan V. Lazić

Abstract

According to the fundamental importance of the tracking theory on technical systems, the main goal of this paper is further development of the theory and the application of tracking, especially on the practical tracking concept.
The plant under consideration is a pneumatic cylinder supplied with pressurized air by an electropneumatic servovalve. This system is often applied as the final control element of the controller in automatic control systems.The correction device for the mentioned plant will be a digital computer. The pure inertial load of the pneumatic cylinder will be time variable. Therefore this plant belongs to the unstationary class of systems. For time varying desired output value the control algorithm will be synthesized.
The control algorithm is based on the self-adjustment principle. Structural characteristic of such a control system is existence of two feedbacks: global negative of the output value and local positive of the control value. Such a structure ensures synthesis of the control without the internal dynamics knowledge and without the measurement of disturbance values. The mentioned control forces the observed plant output to track the desired output value with the prespecified accuracy.
In this paper simulation results produced by the practical tracking control algorithm on an electropneumatic piston drive will be presented.

Keywords - tracking, electropneumatic piston drive, self-adjustment principle

Paper's information

Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,  
UDC

 Practical Tracking Control of the Electropneumatic Piston Drive (pdf)

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Feature Models in Virtual Product Development

Corresponding author - Miodrag Manić

Avtorji - Vojislav Miltenović - Miloš Stojković - Milan Banić

Abstract

The development of new products requires the use of modern tools for design, which make the evasion of errors and the reduction of the number of iterations possible even in the early phases of development. In the concept of simultaneous development of products and technologies, feature-based design enables the creation of product models suitable for various engineering applications. The paper provides an outline of the favorable effects of feature-based design during the development of a virtual product in a digital factory environment. What is emphasized is the manufacturability analysis, which facilitates the adaption of the product to manufacturing conditions and the reduction of manufacturing costs.

Keywords - feature-based design, manufacturability analysis, design for manufacturing, intelligent CAD systems, simultaneous design

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 Feature Models in Virtual Product Development (pdf)

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The Possibility for FMEA Method Improvement and its Implementation into Bus Life Cycle

Corresponding author - Vladimir Popović

Authors - Branko Vasić - Miloš Petrović

Abstract

This paper shows the way FMEA method (Failure Modes and Effects Analysis), which is widely used in motor vehicles industry, can be improved and later used during certain stages of vehicle life cycle. This is illustrated by the example of bus superstructure development. A number of possibilities have been given for the advanced method application during the selection and performance of vehicle maintenance process. A great deal of attention has been paid to risk analysis and the implementation of this parameter into the FMEA method, at the same time insisting on the inconsistencies of the traditional method. The result of our efforts is a new and in our opinion, improved approach to vehicle failure analysis, which gives a new dimension to the entire process. It is evident that this problem is vital from the aspect of high cost of vehicle warranty as well.

Keywords - FMEA method, bus superstructure, risk analysis, new approach

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 The Possibility for FMEA Method Improvement and its Implementation into Bus Life Cycle (pdf)

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Calculations of the Unloading Operation in Liquid Cargo Service with High Density on Modern Product and Chemical Tankers Equipped with Hydraulic Submerged Cargo Pumps

Corresponding author - Andrzej Banaszek

Authors - Radovan Petrović

Abstract

The influence of different liquid cargo density on flow and drive characteristics of hydraulic submerged cargo pumps applied on modern product and chemical tankers is presented in the paper. Main parts of hydraulic structure of a/m system and cargo pump torque controller functions are described. The equation is given for the dependence of discharge rate at service of liquid cargoes (of the same viscosity but different density), based on existing drive and flow characteristics of cargo pumps, prepared for basic cargo.

Keywords - hydraulics, submerged cargo pump, flow and drive characteristics, liquid cargo density, product and chemical tankers

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 Calculations of the Unloading Operation in Liquid Cargo Service with High Density on Modern Product and Chemical Tankers Equipped with Hydraulic Submerged Cargo Pumps (pdf)

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An Experimental Investigation on Effect of Cutting Fluids in Turning with Coated Carbides Tool

Corresponding author - Yahya Isik

Abstract

The major needs in machining are high material removal rate, good work surface finish and low tool wear. These objectives can be achieved by reducing tool wear using proper cooling system of the tool during machining. The work aims to seek conditions in which dry cutting is satisfactory compared with the flood of fluid usually used. The cutting tool used in this research is CVD coated carbide TiC+AI2O3+TiN insert (ISO P25). The type of inserts is DNMG 150608. During the experiments flank wear, cutting force and surface roughness value were measured throughout the tool life. The results have been compared with dry and wet-cooled turning. The results of the present work indicate substantial reduction in tool wear, which enhanced the tool life; this may be mainly attributed to reduction in cutting zone temperature and favorable change in the chip-tool interaction.

Keywords - flank wear, tool life, cooling, cutting forces, tool wear

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

An Experimental Investigation on Effect of Cutting Fluids in Turning with Coated Carbides Tool (pdf)

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Machining of Titanium Alloy Ti-6Al-4V for Biomedical Applications

Corresponding author - Matej Balažic

Authors - Janez Kopač

Abstract

Titanium alloy has properties like outstanding corrosion resistance and very good biocompatibility whicht makes this material very interesting for biomedical applications. Due to its material properties titanium alloy poses a challenge for machining operations. A sound understanding of the alloy behaviour during the machining process is essential to achieve shape and dimensions tolerances of the product with minimum costs and machining times.

Keywords - Ti-6Al-4V, medical implants, coated carbides cutting tool, LENS

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 Machining of Titanium Alloy Ti-6Al-4V for Biomedical Applications (pdf)

 

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Practical Implementation of Load Sharing and Anti Skew Controllers for Wide Span Gantry Crane Drives

Corresponding author - Nebojša Mitrović

Authors - Vojkan Kostić - Milutin Petronijević - Borislav Jeftenić

Abstract
In this paper controlled electrical drives for Rail Mounted Wide Span Gantry Cranes are analyzed. The modern solution considers the application of frequency converters for all drives. Special attention is payed to multi-motor drives of horizontal movement in the sense of load distribution. Although it can be considered that motors are rigid coupled by mechanical construction, they do not need an equal load torque. Presented algorithm provides load sharing proportional to the rated motor power on the simple and practically applicable method on the basis of estimated torques by frequency converters, and controller realized in PLC. For wide span gantry drives efficient method for skew elimination is presented and simultaneous load sharing between the motors is done. The algorithms are experimentally verified on several places in industry and characteristic results are shown in this paper.

Keywords - gantry crane, multi motor drive, frequency converter, load sharing, skew controller

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 Practical Implementation of Load Sharing and Anti Skew Controllers for Wide Span Gantry Crane Drives (pdf)

 

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Integration of Information for Manufacturing Shop Control

Corresponding author - Zdravko Tešić

Authors - Vojin Mitrović - Ilija Ćosić - Danijela Lalić

Abstract
The concept of manufacturing execution system (MES) has acquired a huge importance in modern manufacturing enterprises, especially in low volume and high variety manufacturing industries. The integration between enterprise resources planning (ERP), manufacturing execution systems and shop-floor control (SFC) systems can take a major role in an enterprise control system. Manufacturing execution system is located in the middle, where an enterprise resource planning is located above and shop floor control system is located below. In this paper is presented the part of the automated shop floor control system with possibilities of connecting to the control system on the machine level. Also, possibilities and limitations in communication between existing automatic machine control systems as well as other devices into integral information system of manufacturing enterprise are described.

Keywords - enterprise integration, planning, scheduling, shop-floor control

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 56(2010)3,
UDC

 Integration of Information for Manufacturing Shop Control (pdf)

 

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