Applied Mechanics and Materials Vol. 474

Abstract: The various excitation effects are affecting the machining tools during the machining process. Cutting speeds, cutting forces, chip-making manner, the stiffness of MTW (machine-tool-workpiece) system are predominant effects affecting the dynamics of MTW system and also influencing the machining process (roughness of the machined surface, tool wear, tool or workpiece damage, noise generated by the machining process, etc.). In many cases, to achieve of adequate dynamic properties of the tool, the change of modal properties (mode shapes, natural frequencies) of the body tool must be performed using structural modification. The main objective of this paper will be to formulate, analyse and evaluate the proposed methods and procedures for structural modifications of the tool, represented as a beam. A modification of modal properties by insertion of non-uniform cross-section reinforcing core into body tool is studied and the effect of material properties and geometrical parameters of core on modal properties is analysed. The applications of structural modifications of tool body are leading to better conditions in the cutting process.

Abstract: Change the deformation mechanism in metallic materials may be detectable using infrared thermography and acoustic emission. For samples of mild steel is the creation of Lüder’s bands presented in the infrared spectrum. Follow-number increase of these bands is also presented. In the system of acoustic emission is for this deformation mechanism described signal, which allows detection of the deformation process of these technologies.

Abstract: The article is focused to the temperature measurement and methodology of computer modeling of laser cutting process on stainless steel plate. Microstructure of stainless steel and dimension of the kerf width was obtained. The temperature was measured with two K-type thermocouples by digital convertor NIUSB9211. Obtained temperature dependences were used for simulation 2D and 3D models creation by ANSYS software. The results of the model application with SHELL and SOLID elements are shown. Numerical simulation showed effect of nitrogen gas on heat dissipation and is also one of the reason why isn't total energy received in the material. Author considered 3D model with impinging jet flow whose proposal is in the article as the model closest to reality.

Abstract: Professional paper shows the general characteristics of graded materials, their previous industrial use and potential use of graded materials in the future. In any case, today the use of graded materials is increasing and moving from the laboratory environment into everyday use. However, the subsequent processing of the graded material remains the big unknown, and represents a major challenge for researchers and industry around the world. It could be said that the study of machinability of these materials is in its infancy and in this area are many unanswered questions. Machinability problem of graded materials was undertaken at the Faculty of Mechanical Engineering in Maribor. After a radical study of the literature and potential machining processes of graded materials, we started with the implementation of cutting processes on the workpiece. This professional paper presents the first results of the analysis, which will be used for further research and machinability study of graded materials.

Abstract: This article presents the examination of cutting performance of a low CBN content cutting tool in the case of hard turning of 100Cr6 hardened bearing steel. One of the indicators of cutting performance is the wear rate, which can be calculated as a ratio of a measurable geometric parameter of a wear form and some technological parameters (cutting time, cutting length or removed material volume). The wear of CBN cutting tools is characterized by the extent of flank wear hence the wear rates related to cutting time and removed material volume are calculated based on the measured flank wear during the cutting experiments. The alteration of wear rates as a function of flank wear and cutting speed was examined.

Abstract: Properties of the surface layer after cutting or sliding burnishing depend mainly on type of process and its performance conditions. For its comprehensive analysis is necessary to develop an adequate mathematical model and numerical methods of solving it. A common feature of both processes is moving the tool edge on elastic/visco-plastic workpiece. However, these processes are different i.e. the chip formation or chipless forming, therefore, different properties of surface layer depend mainly on: the geometry of the tool edge and its workpiece relative and depth of process. Therefore, this article is about the application of an incremental modelling and numerical solution of the contact problem between movable rigid and elastic/visco-plastic bodies developed in [ to the numerical simulation of physical process of moving a rigid tool on the workpiece.

Abstract: This article deals with hard turning using wiper and conventional geometry of cutting tool. The aim of this paper is to compare surface roughness when using different feeds and different cutting speeds when turning with different cutting tool ́s geometries. For the experimental research was used hardened steel 100Cr6 with Rockwell hardness 62 HRC. There is a possibility to use two different cutting tool materials for finish machining of hardened steels with hardness 45 65 HRC: PCBN and mixed ceramics. Aluminum oxide plus TiC was used in this experiment.

Abstract: Assessment of a process capability is an important area of the quality management. Quality of produced outputs depends on the quality of the process, in which product characteristics are formed. In considering the capability of the process, the ability of the process should be determined to provide the required quality of products. The required product quality has to meet customer requirements and expectations. For determination of process capability are used methods, which are based on comparing variability of selected product quality characteristics. The smaller the variability of the input factor is, the better is the process capability and therefore a better quality of product is produced. Improvement of process capability and reducing the variability of the product quality characteristics can be achieved by means of applying of statistical methods. Standards for the quality management system require the need of statistical methods application as well as other tools and techniques for improvement in business practice. It is necessary to use statistical methods in measuring, monitoring and process improvement. So can be determined the process variability, identified common and special causes of variability and in consequence to propose corrective actions. The paper describes first theoretical characteristics of capability assessment methods and tools in continuous improvement in industry praxis. With application of chosen statistical methods has been improved capability of the riveting process of clutch disk.

Abstract: The paper deals with the calculation and examination of the mechanical effects on the stop screw in the axial hydrostatic motor. It includes the preparation and the setup of virtual prototypes, as well as the simulation and the processing results of the rigid-body and flexible virtual prototypes using MSC. Adams software. The paper deals with transient analysis of the housing of hydromotor too. Analysis was calculated in software ANSYS.

Abstract: The paper deals with computational analysis of contact stress distribution of rolling elements of roller bearing with regards to the effect of slewing bearing ring at intervals from 0 to 8 and load rate variety at intervals from 25% to 100% of its basic static radial load capacity. The main goal is to present changes in contact ellipse and changes in contact stress for the logarithmic profile of rolling element. Analyzed effect is expressed by functional dependence which can be used in technical application.