Design improvements of machine tools structures using modal analysis approach

R. Albijanic,

Lola Institute, Belgrade,

M. Kalajdzic

Production Engineering Department Mechanical Engineering Faculty

University of Belgrade / YU

Abstract - The paper presents a practical application of the method of modal analysis and structural modifications for improving dynamic performance of a machining center and its vital units. In order to eliminate inadequacies of the structure, modal parameters of the machining center were obtained by experiment. These parameters include natural frequencies, damping ratios and mode shapes and they are used to determine the directions in which the structural improvements should be made. The measurements included the vertical column of the machining center, since it plays a dominant role in its total dynamic behavior. The column and the bed were modified according to the results. The stiffness of the bed was significantly increased. Using the finite elements method (FEM), a parallel analysis of static and dynamic characteristics of the machining center supporting structure was performed. Capabilities of the existing program for structural modifications were significantly improved.

Key words: Machine tools, modal analysis, structural modification, design improvement




Integrated automation system for machining monitoring and control

Mats Bejhem, Mihai Nicolescu, Bo Lindstrom

Production Engineering, Department of Materials Processing Royal Institute of Technology Stockholm, Sweden

Abstract - This paper presents the concept and practical implementation of an integrated system for machining monitoring and control (MMCS). This system is designed to operate in turning centers, and it represents a powerful extension to existing CAD-CAM systems. In order to improve machining, the system coordinates several functions, such as real time cutting force control and tool condition monitoring. The system is centered around a software core, the technological planning unit (TPU), which is the optimization software operating in a Windows environment. The approach is based on the optimization of cutting conditions according to a performance index. By using on-line process condition monitoring, a self-opti­mization function can be implemented. Experimental results reveal the benefits that can be gained by implementing the system on the shop floor.

Keywords: machining control, technological process planning, tool condition monitoring, machining condition optimization


Determination of optimum location of the reference coordinate system in NC milling, for workpieces with preformed hole features

Prof. Dr. - Ing. habil. K. - D. Bouzakis, Lecturer Dr. - Ing. K. Efstathiou

Laboratory for Machine Tools and Machine Dynamics Department of Mechanical Engineering, Aristoteles University Thessaloniki

Abstract - The setup procedure for finishing of workpieces with many holes in NC boring is time consuming. The workpiece is placed on the machine tool table and must be adjusted, so that the final holes overlap? the corresponding initial ones. This adjustment requires coordinate measurements on the initial holes, and possibly relocation of the final hole positions, considering the specified tolerances. For the end-positions of the holes, the NC-code has to be prepared. In the present paper a computer supported method is presented, which enables the automatic execution of these procedures.  

Key words: NC-boring, workpiece setup, touch probe, coordinate measurements



The magic matrix as a smart resource planning

G. Halevi

Technion - Israel Institute of Technology Dobnov St. 20a Tel-Aviv 64369 ISRAEL Fax. + 972 3 696 2833, Tel. + 972 3 696 2833 


Abstract - An organization for operation is continually undergoing modification and changes in the equipment that it uses. In selection of new equipment considerable judgment must be exercised to assure sound decisions. The equipment must have the capacity and other technical operating characteristics that will enable it to perform the required work, and must be economically justifiable on the basis of the savings possible. Management relies on economic models and techniques (e. g. Total Value Analysis. ROI, etc.) in making its decisions for machine replacement. Different concerns will adopt different economic models. However, no matter what economic model is employed, the decisions are restricted to the engineering data fed into it. Thus, engineering is actually doing the first screening of data that will be considered. Furthermore, engineering transfer decisions and not the reasons, alternatives considered, that make them arrive at that decision. Engineering, no doubt is doing the best they can. However, engineering considera­tion and optimization are not always similar to those of the management. Thus the data fed to the economic model are incomplete, and uneconomical decisions might be reached even by employing advanced economical models. This paper proposes a method that introduces engineering technology into the economical model. By employing a matrix concept, sound engineering data can be supplied to the economic models, and real economic decisions can be made. The concept and use of the matrix in resource planning will be described in this paper.

Keywords: economic models, matrix, process planning, resource planning, decision support systems



Adaptive robotic welding using vision feedback

R. Kovacevic and Z. M. Zhang

Welding Research and Development Laboratory Center for Robotics and Manufacturing Systems University of Kentucky Lexington, Kentucky 40506, USA

Abstract - The weld pool contains abundant information about the welding process. Its observation can generate data for studying the welding process. Its control could provide an entirely new method to reach the desired weld quality. A real-time sensing technique has been developed to sense the 2D shape of the weld pool. Thus, abundant data can be acquired from the weld pool and used to correlate the pool geometrical appearance with the weld penetration. The weld pool is characterized using a few parameters. The desired weld pool can be acquired by controlling these parameters. A number of closed-loop control systems have been developed to control the welding process based on the vision feedback of the weld pool.

Key words: welding, vision, neurofuzzy, image.



Preliminary Study of Ceramic Lapping Using Acoustic Emission

loan D. Marinescu, Ruilin Yeng

Kansas State University, Department of Industrial and Manufacturing System Engineering, 237 Durland Hall, Manhattan, KS, 66506-5112, USA 

Fax: (913) 532-7072

Abstract - Single point scratching and experimental simulated lapping in ceramics using Acoustic Emission (AE) have been carried out as the preliminary study of ceramic real time lapping. Experiments show that AE signals have strong correlation with chipping and cracking in single point scratching. The relationship between AE signals and work parameters such as slide speed, normal force, and abrasive size have been established.

Key Words: Ceramics, Lapping, Acoustic Emission, Scratching



Extended RCA Method To Find A Wire Path In An Automotive Wire Harness Design

Seong-Hzuk Zim and Soo-Hong Lee

Department of Mechanical Engineering Yonsei University 134 Shin-Chon-Dong, Seo-Dae-Moon-Gu Seoul, KOREA 120-749

Kyu-Kap Cho

Department of Industrial Engineering Pusan University

30 San Chang-Chun-Dong, Guem-Jeong-Gu Pusan, KOREA 609-735, September 13,1996

Abstract - This study deals with a development of WIRE PATH SEARCHING MODULE as a part of automobile wire harness design system. WRITE PATH SEARCHING MODULE manages the free space, finds transition locations, and creates bundle paths to dramatically reduce a tedious iterative routing process which results in easy optimization of the bundle paths. A prime policy in the system configuration is to compromise between man's and computer's ability, and make designer's leading role in designing process possible. Human input is indispensable to cope with the special cases which were not considered in the initial design stage of the system. In this study, we improve the previous shortest-path-finding algorithm (VGraph and RCA Method) into a new method called Extended RCA, Bundles, connectors and transitions are handled as objects so one can manage and modify physical properties of objects easily. Therefore a verification is allowed at any desired stage of design. The reuse of previous result is facilitated by using Dependency Structure, which represents the mutual relations among connectors, transitions, and bundles. Dependency Structure makes the elimination of redundant calculating process possible, and consequently routing time shorter.

Keywords: Wiring Configuration, Transition, Extended RCA, Reuse of Previous Results



Knowledge categorization and knowledge transition

Dr Mariana Milacic

Torus Theory - Experiments for Engineering Design Mechanical Engineering Faculty 27 Mart 80,11000 Belgrade The Belgrade University, Yugoslavia

Abstract - Very large scale knowledge base is difficult to design without better understanding of the knowledge categorization and the knowledge transition processes. This paper is a pioneer work in experimenting with a new approach to this problem for engineering design activities. Torus theory is used for experimenting in geometry, topology, automata theory, double pendulum and manufacturing systems design. Knowledge crystalization methodology is performed on Euclid's and Newton's houses of knowl­edge. The main objective of this paper is to provide the new way to build an intelligent expert system for engineering design.

Key words: house of knowledge, topology, automata theory, pendulum, manufacturing system.