Applied Mechanics and Materials Vol. 693

Abstract: The coefficient of friction for the bronze material (CuZn25Al6) with insert graphite beds and other bronze material (CuSn12) are investigated in this paper. Friction coefficient was investigated experimentally by the testing machine Tribotestor`89 which uses the principle of the ring on ring method. The external fixed bushing was exposed to the normal load of the same size in all tests. Process of load was increased from level 50 N to 600 N during run up 300 s, after the run up the appropriate level of load was held. The internal bushing performed a rotational movement with constant sliding speed. The value of sliding speed was changed individually for every sample (v = 0.2 (0.3, 0.4) m.s^-1). The forth test had a rectangular shape of sliding speed with direct current component 0.3 m.s^-1 and the amplitude 0.1 m.s^-1 period 300 s, the whole test took 2100 s. The obtained results reveal that friction coefficient increase with the increase of sliding speed.

Abstract: The beam structures are considered as one of the most fundamental building elements of technical equipment. Many of the machining tools (for example lathe tool) may be also regarded as the beam structures. 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.). Depending on the excitation effects, the machining tool body (beam structure) must have the required dynamic properties. The modification of beam modal properties based on embedding of inner reinforcing core is presented in this paper. The main aim of the modification is to change the modal properties (mode shapes, natural frequencies) of the beam body.

Abstract: Significant development of the new production technologies requires an adequate development of the production systems on which these technologies carried out. It is obvious that those facts affect the structural design of new advanced manufacturing systems and also require both research and development of new drive systems. In this context [1], drive systems have the character of complex dynamic systems with elements, resp. subsystems, which have both the different physical nature and in many cases are characterized by control, i.e. having features of the mechatronic systems. The conception of mechatronic drive systems modelling consists of an integration of knowledge from various technical disciplines (i.e. mechanics, electronics, control) to obtain a product with highest possible technical and economical parameters. In this light, the machine aggregates must be modelled as dynamic systems to drive a plant (mechanical load, mechanical working equipment) and to control the technological process.

Abstract: The paper investigates the issue of the asymetric worms´ profile (Fig. 10) of the spiroid gear comprising the direct line worm surface which occurs by the motion of the constituent direct line u upon the helix regarding the steady-state coordinate system 0 (x,y,z). There are described the characteristic attributes of spiroid gears in the article. Some kinematical inaccuracies caused by mistakes in gearing assembly are analyzed there. A testing stand is supposed to carry out an experimental research of inaccuracies influence on smooth run of machine aggregate.

Abstract: Topography and surface roughness is defined as a set of surface textures formed due to used machining or other production technology. It is a key factor mainly for dynamically stressed components. Greater surface roughness negatively affects the fatigue strength of component or its wear resistance.The paper deals with the visualization and processing of data obtained from a laser confocal microscope Zeiss LSM 700. Data acquired by LSM software ZEN2009 are exported in the text form of 3D coordinates of the image data points and are arranged as a set of 2D profiles with resolution 1.10^-7 m. The aim is to describe an alternative method of evaluating raw data extracted from z-stack of acquired TIFF images in order to achieve higher precision and identify the topography of the scanned sample surface. Different methods of data processing have been tested to eliminate deficiencies located mainly in the parts of the scanned surface with low intensity.

Abstract: The aim of present work is monitoring thermal decomposition tested samples depending on distance of ignition source, subsequent generation of flame and flameless combustion. Tested samples are used to produce biofuel in form of pellets, which can be made of spruce wood (Picea excelsa, L.) and beech wood (Fagus sylvatica) and have a direct effect on the properties of these pellets. Measurements are carried out according to standard STN ISO 871:2010 Determination of ignition temperature using a hot-air furnace. External ignition source (electrically heated spiral of the wire canthal) is used to analyze different conditions of test samples. Distance between external ignition source and tested samples is 10, 50 and 90 mm. The experiments are performed at an air flow rate 38, 25, 12,5 and 0 mm.s^-1. The results show the rate of loss of weight and the flow rates of the material of the test samples at the different test conditions.

Abstract: Nowadays the thin tinplates are the most important material for a wraps production.Predominant majority of these sheets are treated by drawing, by which are made both parts of tin sheets. By reduction of thicknesses of thin steel sheets and by require speed of deformation during the wraps production made by drawing often leads to the loss of stability of plastic deformation and to its localization. This localization of deformation considerably influences the change of thickness of protective tin layer and its integrity. Because of this it leads to the reduction of thin steel sheets resistance towards corrosion.In contribution are therefore dependencies of stress and strain by uniaxial and biaxial tensile test by different levels of deformation of two types of sheets monitored. After plastic deformation were sheets put under the impact of corrosion environment and was evaluating influence of deformation largeness and localization of deformation at the corrosive resistance of thin tinplates sheets. In contribution are also analyzed some of the cases of concrete corrosive damage of lids, so-called twist lids.

Abstract: The real values of plastic properties of steel sheets are basic input parameters for objectification of deep drawing technological processes. The loss of stability of plastic properties is the criterion of evaluation of plastic properties of steel sheets in most cases. The loss of stability of plastic properties depends on stress-strain scheme in real conditions of deep drawing of sheets. In the contribution will be evaluated the loss of plastic properties stability of thin double reduced packaging sheets made from low carbon steels. For evaluation of strength and plastic properties of thin packaging sheets is the tensile test most used at present. The material is stressed by uniaxial tension during this test. In the conditions of technological processes of drawing, which thin packaging sheets are mostly treating, is this way of stress not very objective. In most cases it deals about multiaxial stress of sheet by deformation of sheet to require draw cup. At the present, the biggest problem of thin steel sheets by uniaxial tension test evaluation is the loss of plastic deformation stability (localization of plastic deformation). Therefore, obtained results of plastic deformation during this test do not correspond with real plastic properties of thin steel sheets. In the contribution, will be compared the evaluation of plastic properties of these sheets by uniaxial and biaxial load. Biaxial load is unfavourable from stress point, but less sensitive on loss stability of plastic deformation from conditions test influence point.

Abstract: This paper introduces chosen results from measuring cutting forces when end ball milling as well as combined approach to their evaluation. Such a combined approach involves Taguchi array and Response Surface Methodology while main cutting data as depth of cut and side step and cutting speed and feed rate have been taken into account. Main effects of cutting data mentioned above have been identified by means of statistical formulae expressing testing conditions of ball end milling cutters. Interactions among all the cutting conditions are capable of finding out optimized radial and axial depth of cut which are derived from the measured components of the cutting force.

Abstract: FEM analysis was performed on design of experiment (DoE) according to Taguchi plan L₉ (3⁴). In order to overcome the machinability issues associated with machining of Ti-6Al-4V alloy, an attempt has been made in this study to observe the effect of friction coefficient, cutting speed, feed rate and cutting edge radius and on cutting force, temperature and power in 2D orthogonal cutting process supported through out with Third Wave Systems’ AdvantEdge. The comparison between the predicted cutting force, temperature and power at varying of friction coefficient, cutting speed, feed rate and cutting edge radius are presented and discussed. Evaluation of obtained results was processed by the statistical software Minitab 16.