CAD/CAM, CNC TECHNOLOGY APPLIED IN THE FIELD OF ENGINEERING, SECURITY TECHNOLOGY AND MECHANICAL ENGINEER TRAINING I.

In the last decades the spectacular results of each developmental stages of computer-aided design, were considered as great magic of computer use. Professionals were shocked by the impressive building of engineer works and their more and more realistic appearance. It was hard to believe and for many people it still is that this technology becomes indispensable in everyday engineering work. By now, in front-rank product development, it is impossible to do a competitive designer work without applying the most up-to- date design technology. This all leads to the fact that an engineer student of our days, in his design practice, is definitely going to work with the momentarily most up-to-date technology, which will be out-of-date in a couple of years. | A számítógépek alkalmazásának nagy varázslatai közé számított az elmúlt évtizedekben a számítógépen végzett tervezés egy-egy fejlıdési szakaszának látványos eredménye. Szakembereket is meghökkentett a mérnöki alkotások látványos építése és mind valósághőbb megjelenítése. Nehezen hitték, sıt sokan ma is nehezen hiszik azt, hogy a mérnöki munka mindennapjaiban is nélkülözhetetlenné válik ez a technika. Mára az élvonalbeli termékfejlesztésben a mindenkori legjobb tervezési technika igénybevétele nélkül képtelenség versenyképes tervezımunkát végezni. Ennek következtében napjaink mérnökhallgatója tervezıi gyakorlatában minden bizonnyal a ma legkorszerőbbnek számító, de néhány év alatt elavuló módszert leváltó technikával fog dolgozni. Keywords/kulcsszavak: computer aided design, CAD1/CAM2, CNC3 ~ számítógépes tervezés, CAD/CAM, CN

A multi-perspective dynamic feature concept in adaptive NC machining of complex freeform surfaces

This paper presents a new concept of feature for freeform surface machining that defines the changes in feature status during real manufacturing situations which have not been sufficiently addressed by current international standards and previous research in feature technology. These changes are multi-perspective, including (i) changes in depth-of-cut: the geometry of a feature in the depth-of-cut direction changes during different machining operations such as roughing, semi-finishing and finishing; (ii) changes across the surface: a surface may be divided into different machining regions (effectively sub-features) for the selection of appropriate manufacturing methods for each region such as different cutting tools, parameters, set-ups or machine tools; and (iii) changes in resources or manufacturing capabilities may require the re-planning of depth-of-cuts, division of machining regions and manufacturing operations (machines, tools, set-ups and parameters). Adding the above dynamic information to the part information models in current CAD systems (which only represent the final state of parts) would significantly improve the accuracy, efficiency and timeliness of manufacturing planning and optimisation, especially for the integrated NC machining planning for complex freeform surfaces. A case study in an aircraft manufacturing company will be included in this paper

Machinability assessment and tool selection for milling.

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A knowledge-based approach for the extraction of machining features from solid models

Computer understanding of machining features such as holes and pockets is essential for bridging the communication gap between Computer Aided Design and Computer Aided Manufacture. This thesis describes a prototype machining feature extraction system that is implemented by integrating the VAX-OPS5 rule-based artificial intelligence environment with the PADL-2 solid modeller. Specification of original stock and finished part geometry within the solid modeller is followed by determination of the nominal surface boundary of the corresponding cavity volume model by means of Boolean subtraction and boundary evaluation. The boundary model of the cavity volume is managed by using winged-edge and frame-based data structures. Machining features are extracted using two methods : (1) automatic feature recognition, and (2) machine learning of features for subsequent recognition. [Continues.

Machine planning in a product model environment

The aim of this research was to understand and solve problems associated with the integration of a Machine Planner within a product model environment. This work was carried out in conjunction with other researchers, pursuing parallel integration issues related to pre-production proving and product data representation. Product data representations of component level planned, processes and feature level process data have been explored as sub-sets of -a product data model to aid integration. Geometric queries on a cell decomposition solid, model. have been explored as a means of providing feature geometric interaction data, while the dimensional interactions between features have also been addressed. Product data representations have been modelled using a prototype software tool, providing an environment for the exploration of the integration of a Machine Planner using a feature based design approach. Necessary Machine Planning functions have been implemented, using the ADA programming language, to explore the integrating capability of the product model environment, concentrating on the use of a prismatic benchmark component. Using the experimental implementation, setup and operation plans have been produced and machining part programs generated from product model representations of variants on the benchmark component. These have been successfully machined using a3 axis vertical machining centre. Such experiments, as well as others in conjunction with co-researchers, have shown that a product data model can provide a common base of data for the integration of a range of design and manufacturing activities

Resource selection and route generation in discrete manufacturing environment

When put to various sources, the question of which sequence of operations and machines is best for producing a particular component will often receive a wide range of answers. When the factors of optimum cutting conditions, minimum time, minimum cost, and uniform equipment utilisation are added to the equation, the range of answers becomes even more extensive. Many of these answers will be 'correct', however only one can be the best or optimum solution. When a process planner chooses a route and the accompanying machining conditions for a job, he will often rely on his experience to make the choice. Clearly, a manual generation of routes does not take all the important considerations into account. The planner may not be aware of all the factors and routes available to him. A large workshop might have hundreds of possible routes, even if he did know it all', he will never be able to go through all the routes and calculate accurately which is the most suitable for each process - to do this, something faster is required. This thesis describes the design and implementation of an Intelligent Route Generator. The aim is to provide the planner with accurate calculations of all possible production routes m a factory. This will lead up to the selection of an optimum solution according to minimum cost and time. The ultimate goal will be the generation of fast decisions based on expert information. Background knowledge of machining processes and machine tools was initially required, followed by an identification of the role of the knowledge base and the database within the system. An expert system builder. Crystal, and a database software package, DBase III Plus, were chosen for the project. Recommendations for possible expansion of and improvements to the expert system have been suggested for future development

Feature based workshop oriented NC planning for asymmetric rotational parts

This thesis describes research which is aimed at devising a framework for a feature based workshop oriented NC planning. The principal objective of this thesis is to utilize a feature based method which can rationalize and enhance part description and in particular part planning and programming on the shop-floor. This work has been done taking into account new developments in the area of shop floor programming. The importance of the techniques and conventions which are addressed in this thesis stems from the recognition that the most effective way to improve and enhance part description is to capture the intent of the engineering drawing by devising a medium in which the recurring patterns of turned components can be modelled for machining. Experimental application software which allows the user to describe the workpiece and subsequently generate the manufacturing code has been realized

A CAD/CAM concept for High Speed Cutting compatible rough machining in die, mould and pattern manufacturing

Die, mould and pattern manufacturing plays a central role in the production of capital and consumer goods. Ever-shorter product life cycles and the expanding diversity of features require continued cuts in production lead times. Recently, these developments in the market, accompanied by a simultaneous demand for improved quality at a lower cost, are becoming clearly noticeable. Along with the streamlining of organizational structures and advanced technological developments, it is above all the introduction of CAD/CAM software that offers great potential for reducing lead times for components with free surfaces. The role of milling in the integrated process chain of die, mould and pattern manufacturing is steadily gaining importance. This is due to the ongoing further development of milling-machine technology, the cutting tools and their coatings, and of the CAD /CAM systems themselves. Generally speaking, the milling process is divided into the operations of roughing and finishing. For rough milling, efficient machining means high stock-removal rates together with close contour approximation and low tool wear. Rough milling is normally carried out layer by layer, i.e. in a 2.SD machining operation with constant depth per cut because the rate of material removal and process reliability are usually highest when this method is used. High-speed cutting (HSC), which has been the subject of extensive university research for far more than ten years, has meanwhile become established as a finishing process in many companies. However, the application of HSC demands the observance of geometric and, above all, technological constraints. A considerable degree of optimization can be achieved when these constraints are applied to rough milling. In the integrated process chain, the CAD/CAM system performs the task of calculating NC programs based on CAD data which meet the requirements posed by rough and finish machining operations. While general interest was focused on the development of CAM strategies for HSC finish machining, advanced development of technology-oriented CAM modules for upstream roughing operations was neglected. The paper at hand deals with the development of a CAM module for rough-machining complex components in die, mould and pattern manufacturing. It provides an insight into the process-technological demands made on HSC operations and their application in rough machining, from which guidelines and requirements on technologically oriented NC functions for CAM software were derived. These encompass both the complete development of an interactive, dialogue-based user guidance function and the algorithmic conversion of the calculation routines. The concept at hand was almost entirely implemented and integrated in the CAD/CAM system developed by Tebis AG, Germany, which was conceived especially for die, mould and pattern manufacturing and is scheduled for introduction to the free market starting in April 2001

A distributed decision support system for turning and milling operations using the internet

The machine tool industry is highly dependent on the tooling which is needed to machine the components used to make the range of products seen in today's society. The range of tooling available to machinists is prolific and subject to continual growth. Those engineers faced with the task of process planning require advanced systems to support the decisions that need to be made for the production process to operate smoothly. The tooling data made available by these systems is a key factor in defining the efficiency with which the production processes can be carried out. This research examines the technical decision support systems made available to industrialists and highlights the scope to provide tooling engineers with up-to-date tooling performance and use data that can be used both in the planning stages as well as dealing with problems encountered during production. Specifically, this research identifies the role performed by widespread tool trials, associated with new tools or new materials, and goes on to show how the information obtained from tool trials can be collated in a structured manner and used to enhance the provision of data with which to carry out the process planning task. The goal of this research was to develop and implement a framework capable of collecting and disseminating data related to tool trials in a coherent and supportive fashion using distributed methods. This target resulted in the deployment of a system named JadeT, which is capable of receiving and analysing data from tool trials and subsequently enhancing the process planning task by basing cutting parameter selection on a combination of fundamental cutting parameter algorithms in parallel with using the approved data generated from tool trials. The JadeT system was tested via the creation of a database using actual tool trial reports, and the manner in which this data was used to provide cutting parameters was analysed. The JadeT system has been developed, deployed and evaluated. The opportunity to use data contained within tool trial reports to support process planning tasks has been identified and exploited. The testing of JadeT indicates that the system fulfils the initial goals and was able to provide suggestions for further research in this area