Peter Monka

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.

Experimental in-vitro bone cements disintegration with ultrasonic pulsating water jet for revision arthroplasty

The paper deals with the study of using the selective property of ultrasonic pulsating water jet for the disintegration of the interface created by bone cement between cemented femoral stem and trabecular bone tissue as a potential technique for revision arthroplasty. Six types of commercial bone cements based on Polymethyl Methacrylate were used for investigation. The cements were mixed using the DePuy - SmartMix® CTS / vacuum mixing bowl. Mechanical properties of hardened bone cements were determined by nanoindentation. The bone cement samples were disintegrated using the pulsating water jet technology. The water pressure varied between 8÷20 MPa. A circular nozzle with an orifice diameter of 0, 7 mm was used for water jetting. The stand-off distance from the target material was 2 mm and the traverse speed 1 mm/s. The volume of material removal and depth of created traces were measured by MicroProf FRT optical profilometer. The results positively support an assumption that pulsating water jet has a potential to be a suitable technique for the quick and safe disintegration of bone cement during revision arthroplasty.

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.

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.

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.

INFLUENCE OF FOCUSING TUBE WEAR ON VIBRATIONS AND SURFACE ROUGHNESS

Original scientific article The paper deals with the study of the focusing tube wear influence on surface quality and vibrations produced by abrasive waterjet by means of experiments design. The experiments deal with evaluation of the influence of focusing tube wear on surface quality and parameters of vibration generated by abrasive waterjet cutting. The main task of the first experiment was to study the significance of four selected factors of independent variables (focusing tube wear, traverse rate, abrasive mass flow rate and pressure) by full factorial analysis at two levels. The aim of the second experiment was to study the influence of focusing tube wear on the vibration parameters. It has been observed that focusing tube wear has a significant negative influence on surface quality and parameters of vibration.

Fundamental Requirements for CAPP Software Design Focusing on Industry 4.0 Specific Features

The article deals with the basic requirements imposed on software applications for Computer Aided Process Planning (CAPP) with respect to specific features of Industry 4.0. There are described two basic steps in the article that preceded the design of a new information system created by authors in the way to be suitable for enterprises that operate in the period of industrial revolution “Industry 4.0”. The first step was in analysis of European and Slovak industrial market, where the composition of enterprises from several points of view were investigated. The second step was focused on specification of basic requirements that have to be kept by information system applied into plant within Industry 4.0. On the basis of realized analyses and on the multivariant theory, it was designed new information system that has been successfully applied into real company conditions.

Investigation of Chip Dimensional Characteristics Created by the Specific Cutting Tool at the Machining of 12 050 Steel

The article deals with the investigation of chip dimensional characteristics that are created by the tool with linear cutting edge nonparallel to the workpiece axis. It is the tool with special geometry that was designed by authors in order to improve product quality and shorten the time of its production. Aim of the research has been focused on the obtaining of dependencies of the chip dimensions on both feed per revolution and setting of tool corner height in relation to the workpiece axis during machining of 12 050 steel. Measured data were processed statistically and they were evaluated by means of regression analysis in matrix expression. Measured data have indicated that with the increasing of feed per revolution, the chip width and chip thickness are increasing, too. As for the depth of cut, if it is increasing, the width of chip is also increasing, but chip thickness is not changing. The experiments have shown that the shape of chips at the machining by tool with linear cutting edge is not suitable for usage in production without direct control by operator. Therefore, when considering usage of this tool, it will be necessary to design the tool with chip breaker.