Journal of Mechanical Engineering 53 (2007) 6

 

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Optimization of the Characteristic Parameters in Milling Using the PSO Evolution Technique

Corresponding author - Uroš Župerl

Authors - Franci Čuš - Valentina Gecevska

Abstract

The selection of machining parameters is an important step in process planning; therefore, a new evolutionary computation technique has been developed to optimize the machining process.  In this paper, Particle Swarm Optimization (PSO) is used to efficiently optimize the machining parameters simultaneously in milling processes where multiple conflicting objectives are present. First, an artificial neural network (ANN) predictive model is used to predict the cutting forces during machining and then the PSO algorithm is used to obtain the optimum cutting speeds and feed rates. The goal of the optimization is to determine the objective function maximum (the predicted cutting-force surface) by considering the cutting constraints. During optimization the particles 'fly' intelligently in the solution space and search for optimal cutting conditions according to the strategies of the PSO algorithm.The results showed that an integrated system of neural networks and swarm intelligence is an effective method for solving multi-objective optimization problems. The high accuracy of the results within a wide range of machining parameters indicates that the system can be practically applied in industry. The simulation results show that compared with genetic algorithms (GAs) and simulated annealing (SA) the proposed algorithm can improve the quality of the solution while speeding up the convergence process. The new computational technique has several advantages and benefits and is suitable for use when combined with ANN-based models where no explicit relation between the inputs and the outputs is available. This research opens the door for a new class of optimization techniques that are based on evolution computation in the area of machining.

Keywords - cutting, end-milling, cutting parameters, neural networks

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 354-368
UDC 621.914:004.89

Optimization of the Characteristic Parameters in Milling Using the PSO Evolution Technique (pdf)

 

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Quality Improvement - PDCA Cycle vs. DMAIC and DFSS

Corresponding author - Mirko Soković

Authors - Duško Pavletić

Abstract

To achieve continuous quality improvements every organization needs to use an appropriate selection of tools and techniques. The fundamental requirements for success are a clear understanding, both of the tools and techniques as well as the process by which they should be applied. In this paper we provide an overview and the fields of application of the PDCA, Six Sigma and DFSS techniques for the continuous quality improvement of products, processes and services. The PDCA cycle is a simple-to-understand concept of continuous quality improvement; the Six Sigma DMAIC methodology is a systematic and fact-based project-management approach; while DFSS methodology is a systematic approach to product or process design that includes all organization functions.

Keywords - product quality, quality improvement, PDCA cycle, DMAIC, Six Sigma, DFSS

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 369-378
UDC 005.6

Quality Improvement - PDCA Cycle vs. DMAIC and DFSS (pdf)

 

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The Effects of a Tool's Chemical Composition on Its Performance when Turning Inconel 718 with Ceramic Inserts

Corresponding author - Abdullah Altin

Authors - Ahmet Taskesen - Muammer Nalbant - Ulvi Seke

Abstract

The effects of a cutting tool's chemical composition on wear and tool life are investigated. A series of experiments was carried out using silicon-nitrite-based (Si, Al, O, N) and whisker-reinforced ceramic tools (Al2O3+SiCw) that have two different geometries (square and circular) and three different ISO qualities. For the ceramic tools, a high level of aluminum and germanium caused built-up edge (BUE) formation, while notch wear is considered as a cause of high copper and oxygen levels in whisker-reinforced ceramic tools. Four different tools with two qualities showed the best performance at a cutting speed of 200 m/min. The fact that the whisker-reinforced square-type ceramic tools are subjected to plastic deformation is attributed to the high oxygen level in the cutting tool's structure.

Keywords - cutting tools, chemical properties, superalloys, tool wears

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 379-385
UDC 621.941.025:620.178.16

The Effects of a Tool's Chemical Composition on Its Performance when Turning Inconel 718 with Ceramic Inserts (pdf)

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Vibrations of a 3-Dimensional Piping System

Corresponding author - Matej Tadina

Authors - Miha Boltežar

Abstract

This paper briefly presents the transfer-matrix method (TMM) for the vibration analysis of a 3-dimensional piping system. The transfer matrix of a curved pipe with fluid was derived based on the exact solution of the governing equations, where the axial deformability was also taken into account. Only the steady-state response for the case of harmonic excitations was analyzed.  With the formulation of the transfer matrix for a straight pipe and for a curved pipe, a 3-dimensional complex piping system can be easily modeled. The inviscid fluid-dynamic forces were derived according to the plug-flow approximation and the slender-body theory. As shown in a numerical example of a 3-dimesional piping system the comparison of the transfer function obtained with the finite-element method (FEM) and the TMM is quite good. On the basis of a comparison of the experimental results and the results obtained with the TMM, the correctness of the method was confirmed. It was also shown that the TMM is significantly faster than the FEM.

Keywords - piping systems, vibration analysis, modeling, transfer-matrix method

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 386-398
UDC 534.12:519.61/.64

Vibrations of a 3-Dimensional Piping System (pdf)

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The Influence of the Housing on the Noise Emitted by a Reciprocating Compressor

Corresponding author - Anže Jerič

Authors - Janez Gradišek - Igor Grabec - Edvard Govekar

Abstract

The influence of the housing on the noise emitted by a typical reciprocating compressor for domestic appliances is analyzed. Sound-pressure and sound-intensity measurements were conducted to analyze the properties of the noise emitted by the compressor with and without the housing. The experimentally determined elastic properties of the compressor housing were compared with calculations based on a finite-element model. The results show that the dominant noise frequencies correspond to the eigen frequencies of the housing. Simple stiffening of the housing is shown to reduce the amplitude and modify the frequency content of the noise recorded outside the compressor.

Keywords - domestic appliances, reciprocating compressors, noise, sound intensity

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 399-408
UDC 534.83:621.512

The Influence of the Housing on the Noise Emitted by a Reciprocating Compressor (pdf)

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The Dynamic Response of a Cylindrical Tube under the Action of a Moving Pressure

Corresponding author - Bahador Saranjam
Authors - Kambiz Bakhshandeh - Mohammad-Hassan Kadivar

Abstract

In this study the dynamic response of cylindrical tubes subjected to an internal moving pressure, travelling at a constant velocity, has been investigated with the finite-element method. In this paper the tube's wall thickness is considered to be uniform throughout and small compared to the mean radius of the tube. The intensity of the moving pressure as well as the velocity of the front is constant. The dynamic behaviour of various cylinders with different length-to-diameter ratios is calculated. Based on this study, we believe a dynamic analysis is essential for a high pressure velocity. In this study, two new concepts are defined: the radial dynamic magnification factor and the long member. We show that the value and behaviour of the radial dynamic magnification factor are dependent on the length-to-diameter ratio and can be divided into two or three regions. For a long cylinder the behaviour of the radial dynamic magnification factor is divided into the under-critical, transition and overcritical regions. According to this study, the radial dynamic magnification factor changes from 1.8 to 2.55, depending on the length of the cylinders. The Msc/Nastran software package was used for the finite-element analysis.

Keywords - moving pressure, finite element analysis, dynamic magnification factor, cylindrical tube

Paper's information
Strojniški vestnik - Journal of Mechanical Engineering 53(2007)6, 409-419
UDC 532.58

The Dynamic Response of a Cylindrical Tube under the Action of a Moving Pressure (pdf)

  

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