Katarina Monkova

ON-LINE MONITORING OF TECHNOLOGICAL PROCESS OF MATERIAL ABRASIVE WATER JET CUTTING

Original scientific paper The paper deals with the indirect ways of on-line monitoring of technological processes of cutting. The objective of the study is a design of on-line monitoring system for the cutting technology through an abrasive water jet. In cutting by the abrasive water jet two parallel phenomena are formed. The phenomena are represented by generated surface and vibrations. For the purpose of proving of the hypothetical assumptions on dependence of generated surface quality on vibrations the experiments utilizing stainless steel AISI 304 were performed. The experiments were realized at four diverse settings of cutting head traverse speed. The material vibrations were collected by means of two independent accelerometers PCB IMI 607 A11. One of the accelerometers was oriented towards the cutting direction and the other in direction perpendicular to cutting. Sampling frequency was of 30 kHz. The generated topography of the material was measured by an optical profilometer FRT MicroProf. The collected data were evaluated by a virtual tool developed in LabView 8.5 in the form of vibration analyses being consequently mutually compared. Both phenomena proved to be dependent on common technological cause, i.e. on cutting head traverse speed. At the same time the study offers a theoretical design of the on-line monitoring system and of the future heading of the research in this field.

Inverse Processing of Undefined Complex Shape Parts from Structural High Alloyed Tool Steel

The paper deals with the process of 3D digitization as a tool for increasing production efficiency of complex shaped parts. Utilizes the concept of reverse engineering and new the model of NC program generation STEP-NC, for the of templates production for winding the stator coil of electromotors that is for electric household appliances. The manual production of prototype was substituted by manufacturing with NC machines. A 3D scanner was used for data digitizing, CAD/CAM system Pro/Engineering was used for NC program generation, and 3D measuring equipment was used for verification of new produced parts. The company estimated that only due to the implementation of STEP NC standard into production process it was allowed to read the 3D geometry of the product without problems. It helps the workshop to shorten the time needed for part production by about 30%.

Newly Developed Software Application for Multiple Access Process Planning

The purchase of a complex system for computer aided process planning (CAPP) can be expensive for little and some middle sized plants, sometimes an inaccessible investment, with a long recoupment period. According to this fact and the authors experience with Eastern European plants, they decided to design a new database application which is suitable for production, stock, and economic data holding as well as processing and exploitation within the manufacturing process. The application can also be used to process a plan according to the selected criteria, for technological documentation and NC program creation. It was based on the theory of a multivariant approach to computer aided plan generation. Its fundamental features, the internal mathematical structure and new code system of processed objects, were prepared by the authors. The verification of the designed information system in real practice has shown that it enables about 30% cost and production time reduction and decreases input material assortment variability.

Vibrodiagnostics and its Application in Manufacturing Practice

The article deals with the problems that originated at the testing of electromotors after their assembling. The laser inspection station for several types of electromotors was built as the part of assembly line for mass production of electromotors. At the testing, relatively frequent failures of the station were observed. As the inspection method for problems definition was used the vibrodiagnostics. It showed that errors were caused by the deficient fixing of motors during the testing. On the bases of vibration analyses results it was realized the station frame strengthening and so the improvement of operating mode of station.

Surface and topographical parameters investigation at abrasive waterjet machining by means of optical measurement

The paper deals with an application of a shadow method which enables monitoring and checking a state of surface geometry. The data obtained from the measurement of the surface topography are analysed and simultaneously interpreted with the view of a quality increase. Data analysis from the surface enables us to formulate our ideas on the mechanism of the surface establishment created by a hydroabrasive division. It offers as well the analysis possibilities of wider connections dealing with next technology development of materials hydroabrasive dividing. Further, it emphasised the creation of parameters database of surface geometry irregularities. The utilisation of the database leads to an objective projection and a technology control of materials hydroabrasive dividing so that this technology produces more efficient and simultaneously more quality final production. New knowledge about dividing mechanism should support abstractedly an option of cutting parameters which are optimal for a given material and for required parameters concerning the quality, power and general dividing economy.

Qualitative parameters of complex part produced by additive approach

Considering the expansion of new trends in production technologies, it is necessary to know as much as possible effects that influence quality of produced component. Sintering of metal powder brings many problems which is necessary to identify and consequently to solve. It is more important, if the parts are complex with thin walls and it is supposed that it will be used in the equipment with high safety factor, e.g. in aerospace industry. The article deals with the base study of qualitative parameters of complex part produced from steel by additive approach. Within the research, a complex component was designed so to include many specific geometrical units that represent the most used features of technical parts. During preliminary research, two observed parameters were investigated: surface roughness and precision. From the beginning of the study it was clear that the surface will not be smooth with low surface roughness due to the principle of technology. In accordance with this prediction, the results also showed relative big differences between parameters measured in various points of the investigated areas.

Rationalization of manufacturing of plastic injection moulds by abrasive waterjet

The article deals with a proposal and a theoretical solution for the rationalization of manufacturing of parts of plastic injection moulds by abrasive waterjet cutting. On the basis of experimental tests and by the application of advanced abrasive waterjet technology to the process of manufacturing of plastic injection moulds, it has been found that there is a possibility of considerable time saving, i.e. a marked shortage in time period from product ordering to dispatching. In such a way it is possible to increase the competitiveness of a company and to ensure its stable position on the market even in the time of global crisis.

The Research of the High Speed Steels Produced by Powder and Casting Metallurgy from the View of Tool Cutting Life

High speed steels have a leading position in the group of tool materials today in regard to their special properties. The article deals with the cutting life of tools, which cutting tips were produced from high speed steels. The test were realized at Faculty of Manufacturing Technologies TU Kosice with the seat in Presov, in collaboration with Institute of Material Research of Slovak Academy of Sciences in Kosice. As the method for tool-life investigation was selected the simple radial lathe-turning test. The measured values were statistically processed and submitted to the remoteness testing according to Grubbs. The results of the experiments are graphically presented as a dependence of cutting life on the cutting speed for five types of high speed steels. The base material for four of them was high speed steel STN 19 830 produced via powder metallurgy. It was modified by additional alloying elements, so in this way originated next variations of this steel listed above. Measured data were compared with the fifth type of high speed steel with similar chemical composition, but this type was produced via classical approach - by casting metallurgy. The know-how of the investigated relation will enable to the producers to make a good decision about what type of tool material should be used at the machining in specific conditions in order to achieve good quality of machined surface while achieving the required level of energy consumption.

Some Aspects Influencing Production of Porous Structures with Complex Shapes of Cells

The article deals with some aspects influencing Direct Metal Laser Sintering (DMLS) technology. The 3D printing method is used in production of metal parts, at which a product is built layer by layer. The main advantage of this method is the ability to produce parts which have a very complex geometry and which are produced by classical conventional methods in very complicated way. To be 3D printing technology included in the industrial production of the real components it is required to achieve high mechanical properties of produced parts. The final properties of produced parts are strongly dependent on each individual laser produced track and layer. Impacts of individual factors on the quality of product are described in the article. There is also presented preliminary study related with the modelling and manufacturing of porous structures. It comes to geometrically defined structure with complex shapes that allows weight reduction with sufficient toughness.

NUMERICAL AND EXPERIMENTAL MODAL ANALYSIS OF GEAR WHEEL

The paper deals with the theoretical and practical aspects that are necessary for identifying of modal parameters of the gear wheel as a component of the planetary gear mechanism, which are basic for the dynamic analysis. The paper presents thematically integrated part of the results of numerical and experimental modal analysis conducted on a particular gear wheel. The paper aimed to create experimental and computational model and subsequent verification of selected theories in defining the modal parameters, comparing results obtained numerical and experimental modal analysis and assessment of dynamic characteristics of the component with respect to its operating conditions. Numerical analysis was carried out in a computer CAD/CAM program PTC Creo, which works on the Finite Element Method. The results obtained by experimental modal analysis were evaluated by measuring system PULSE.Experimental measurements have shown that the values of natural frequencies along with the natural shapes are adequate and that no natural frequency is not the same or close to the gear frequency, so the component can be used in the real practice.