Solid State Phenomena Vol. 199

Abstract: The problem of software creation for the analysis of transient temperature field in cold rolling of metals is under consideration. Firstly, the mathematical model of the process of heating the strip and rolls at cold rolling it is proposed. This model assumes that the generation of heat during the rolling takes place due to friction on the contact surface of the rolls and the strip as well as plastic deformation of the strip material. Next, some fragments of created application for the purpose of an overall numerical analysis of heat partition ratio between the rolls and a strip as well as the temperature in any point of these elements are presented.

Abstract: This paper presents the results of studies which characterize the dynamic viscosity changes of ferrofluid in terms of changes of selected physical conditions of its work. Knowledge of the variation of the ferrofluids density, lubricity, and especially viscosity depending on the concentration of Fe₃O₄ magnetic particles, temperature, deformation speed and impact direction, type and value of magnetic induction, it is necessary to analyze the changes of operating conditions of the slide journal bearing ferrofluids lubricated. This theme is the broader context of the authors interests and his research. In this article has been briefly characterized the viscous properties of the tested ferrofluid. There also has been shown an analysis of the impact of changes in temperature and velocity of deformation on the change of ferrofluids dynamic viscosity. The paper has been summarized the observations and conclusions reached on the basis of analysis results.

Abstract: In the paper, graph-based models of planetary gears are presented. Especially, compound planetary gear boxes are analyzed. The rules of assignment of particular graphs are shortly described. Based upon these models, ratios for consecutive drives are calculated. Graph transformations are introduced aiming for presentation of every single drive separately. Kinematic equations are generated in algorithmic way based on the adequate subgraphs as well as their codes. Compatibility of results - obtained by means of different methods - was achieved. The presented method is simple and effective, moreover it can be used for other design tasks as e.g. optimization and further analyzes i.e. evaluation of effectiveness.

Abstract: On the basis of the experiment, the changes in the moment of friction in the double-row ball bearing were estimated. The experimental data indicated the presence of significant differences between the average values of the moment of friction in the whole spectrum of the rotational speeds that were examined. At the same time it was observed that there exist certain characteristic rotational speeds at which the given bearing is informed by a greater working resistance. It may indicate the presence of both optimal and unfavourable working conditions for these bearings; the conditions during which there occur minimal or, respectively, maximal resistances (in a given situation). The results of the examination were analyzed statistically; the after-examination samples were closely observed and this further visual scrutiny proved that during the work of the bearing, the lubricant was displaced.

Abstract: One of the main surface coating quality indexes of details of mechatronic systems is surface roughness. And the surface roughness is described by surface roughness parameters. Nowadays characterization of surface roughness using three-dimension (3D) methods and parameters become more and more important. This type of surface quality characterization, unlike the two-dimension (2D) methods, provide a more complete view on the surface qualities, since the surface roughness is viewed as a spatial object. Within the last ten years intensive work is being carried out on the development of 3D roughness standards, therefore it is necessary to agree on a unified approach in the assessment of surface roughness 3D parameters. To make possible application of the ISO/DIS 25178 standard being developed one needs information on the determination of 3D surface roughness parameter precision, such as number of measurements, dimensions of measurement areas and their disposition on the measured surface.

Abstract: Commonly used as a finishing operation, lapping has been used for achieving ultra-high finishes and close tolerances between mating pieces. Its carried out by applying loose abrasive grains between work and lap surfaces, and causing a relative motion between them resulting in a finish of multi-directional lay. The grains activity (sliding and rolling) in the working gap causes not only the material removal but also the temperature rise of lap plate. This work presents the results of lapping plate temperature rise research. The investigation has been conducted to check the influence of grains size on. It was made during flat lapping with use of ABRALAP 380 lapping machine and infrared camera Thermo Gear G100. The lapping machine executory system consisted of three working conditioning rings. Plate temperature was measured during ceramic (Al2O3) elements lapping. The elements were valve sealing parts. After grinding they were processing with three abrasive grains sizes: F400/17, F800/6.5 and F1200/3. The abrasive mixture was boron carbide powder mixed with kerosene and machine oil with grain concentration 0.25. Other lapping parameters remained constant during process. The wheel speed was 60 rev/min and lapping pressure 0.04 MPa. In the next step the statistical analysis was conducted. It was analysed if the plate temperature is influenced by the grains size. A hypotheses testing method was use. Results were calculated for temperature rise values measured after 300 minutes of machine working. According to them the influence of abrasive grains size on plate temperature rise is statistically insignificant, what is not consisted with the model.

Abstract: This paper presents a method of determining the reliability function of rolling bearings operating under conditions of assembly error. Both the random nature of the assembly errors and the hour-by-hour durability of the bearing in question were considered. The perturbation method of second moments was used to solve the problem. This method allows for determining the moments of first and second order of the probability distribution of the safety coefficient, which is understood as the ratio of the actual durability in hours to the predetermined bearing durability in hours. As an example, the method of determining the distribution of the durability coefficient of a rolling bearing was presented for a situation of angular misalignment of coupled shafts.

Abstract: With the appliance of the development of modern technologies in the areas of surface engineering and related applications, the definition of the term hard coatings can be extended by the Plasma Assisted Chemical Vapor Deposition (PACVD) method. This is a cost-effective plasma deposition process, which can be used to improve surface layer properties, e.g. hardness and wear resistance of aluminium, but also magnesium alloy parts by creating a resistant thick coating on the component surface. In this paper there have been presented results of the structure and mechanical properties investigations of crystalline diamond-like carbon gradient/monolithic coatings (Ti/DLC/DLC) deposited onto magnesium alloy (Mg-Al) and aluminium alloy (Al-Si-Cu) substrate by Plasma Assisted Chemical Vapor Deposition (PACVD). A thin metallic layer (Ti) was deposited prior to deposition of gradient coatings to improve adhesion. Microstructure investigation was performed using scanning electron microscopy and transmission electron microscopy. Tests of the coatings adhesion to the substrate material were made using the scratch test. As an implication for the practice a new layer sequence can be possible to develop, based on PACVD technique. Wear test were performed using the ball-on-disk method.

Abstract: In presented paper are elaborated the preliminary problems of thermo-hydrodynamic theory of lubrication for dependences between temperature, adhesive forces, and oil dynamic viscosity, in micro-scale inside super thin cylindrical boundary layer arising between two cooperating grooved cylindrical surfaces. In cylindrical micro-bearings are visible the large gradients of temperature changes and adhesion changes in very thin gap height direction. Hence the oil dynamic viscosity changes significantly in gap height direction. This fact implies the visible oil flow velocity changes and friction forces and the hydrodynamic pressure changes during the micro-bearing exploitation. Up to now the influence of adhesion forces simultaneously with temperature on oil viscosity changes and next on hydrodynamic pressure and load carrying capacity changes in cylindrical micro-bearing gap were not considered in analytical and numerical way.

Abstract: The report includes results of the study on the change of viscosity and lubricity of engine oil used in the two HEROS' harbour tug Caterpillar CAT3516DITA main engines, both with the similar amount of working hours. Each of the engines has a nominal power of 1421kW and usually works between 650 and 1800rpm. The examinated oil is a product of the Fuchs Oil Corporation, named Titan Truck Plus 1540, which meets the requirements of SAE 15W-40. The ageing of engine oil causes the change of its dynamic viscosity value. That change has effect on the process of lubrication and the wearing of slide journal bearings. The aim of this work is to evaluate the changes of viscosity and lubricity values of engine oil in the time of its exploitation. The changes of the viscosity and lubricity of engine oil were observed at specified intervals, between the oil changes. The results of the study are presented as the characteristics of viscosity and time in various temperatures and the shear rates. The measurements of the viscosity were made on the Haake Mars III rheometer, with the shear rates up to 200 1/sec and in the range of temperatures between-10°C to +120°C. This paper also includes information on the analysis of wear products, contaminants and additives in the investigated oil was made with the rotating disc electrode atomic emission spectrometer Spectro Incorporated Spectroil Q100. The Spectroil Q100 spectrometer can detect up to 22 different chemical elements that most often occur in the motor oil additives, contaminants and wear products. The lubricity of the examinated was measured on the T02-U four-ball tester.