Evolution of Residual Stress Through The Processing Stages in Manufacturing of Bore-Chilled Sand-Cast Aluminum Engine Blocks With Pressed-In Iron Liners

The cumulative global emissions produced by the automotive industry over the last decade has put a tremendous strain on the environment. Consequently, automotive engineers and manufacturers have been forced to improve the efficiencies of their automobiles which is frequently accomplished by increasing the operating pressure, and therefore temperature, of the combustion engine. Unfortunately, in addition to the rise in operational pressures and temperatures, large tensile residual stresses often accumulate in the cylinder bridges during the casting process of aluminum engine blocks due to the use of cast-in iron cylinder liners, leading to combined stress magnitudes above the strength of the currently used aluminum alloys. Thus, the present study aims to characterize the evolution of residual stress, with application of neutron diffraction, at several critical stages of the manufacturing process of sand-cast aluminum engine blocks that have eliminated the iron cylinder liners from the casting process and replaced them with cylinder bore chills that are pressed-out after the thermal sand reclamation process. The replacement of the iron liners shifted the stress mode from purely tension to purely compression until the bore chills were removed. Following removal of the bore chills, the maximum tensile stress at the top of the cylinder bridge was ~70% lower than the engine’s predecessor which was produced with iron liners. Moreover, in the production-ready state (i.e., T7 heat treated, machined and press-fit liners inserted), the stress mode maintains the partially compressive nature with low magnitudes of tension, thereby lowering the material’s susceptibility to crack growth and propagation.

Influence of operating conditions on changes in wear parameters of ICE mating

Regularities of wear of mating of internal combustion engines operated in different conditions are discussed and analyzed. Regularities of wear of part mating in the process of technical operation of a motor vehicle are obtained. The correlation coefficients and the correspondence of the obtained regularities of wear to the experimental data have been determined. According to the research results, it was determined that during intercity transportation compared to transportation in settlements, the wear rate was lower by 47.7 % for cylinder liners, by 45.8 % for piston rings, by 40.12 % for connecting rod bearings and by 39.2 % for crankshaft necks. The research results can be applied when calculating connection resources in assembly units of machines.

INCREASING THE CURRENCY RESISTANCE OF CYLINDER-PLASTING OF PYSTON PUMPS BY PLASMA METHOD

The article examines the study of increasing the wear resistance of the cylinder-sleeve of a piston pump using the developed technology of plasma spraying. Wear-resistant and durable coatings of nickel, chromium, molybdenum and tungsten were obtained on the surface of the piston pump cylinder-sleeve. A graph of the dependence of the coating thickness depending on the surface hardness of the cylinder-sleeve is presented. According to the graph, depending on the hardness, you can determine the wear resistance of the coating surface of the cylinder-sleeve. Keywords: piston pump, cylinder liners, plasma method, nickel, chromium, molybdenum, tungsten, wear resistance, coating thickness, hardness, graphical dependence

Effects of alloy compositions on mechanical properties of as-cast banite iron materials for cylinder liners

The cylinder liner is a key part of an internal combustion engine. It always exposes at the worst conditions in the engine room: high temperatures, high pressures, large frictions, and large applying forces. Therefore, excellent physical properties such as surface hardness, tensile strength, heat resistance, and pressure resistance are essentially required as a cylinder liner material. Among them, the surface hardness and tensile strength are the most important properties which play decisive roles in producing a good cylinder liner. Researches on the development of new cast materials with different contents of alloying elements used in cylinder liners, which may exhibit high surface hardness as well as tensile strength, consistently draw much attention. In this regard, this study aims to experimentally investigate the effects of alloy compositions on the mechanical properties of ASBC materials for cylinder liners. Besides, we also replace the traditional-used high-price Ni with low-price Cu in order to reduce the production cost of cylinder liner materials. Results show that the best contents of C, Mo, and Cu for an as-cast banite iron (ACBI) material are found around 2.7%, 0.6–0.8%, and 0.82–1.0%, respectively, in which the highest hardness occurs. Those are found around 2.7%, 0.7–0.8%, and 0.94–1.0%, respectively, in which the highest tensile strength occurs. At the same time, without any reductions in performances of hardness and tensile strength, we successfully adopt Cu as a substitute for Ni as an important composition of ACBI material for cylinder liners.

The Effect of Surface Topography Feature Size Density and Distribution on the Results of a Data Processing and Parameters Calculation with a Comparison of Regular Methods

In this paper, the influence of occurrence of surface texture features on the values of surface topography parameters calculated after the application of various data processing techniques was presented. Different types of surface topographies were considered, as follows: cylinder liners, some with additionally burnished dimples, turned, ground, milled, laser-textured, composite, ceramic, or isotropic in general. The effects of feature size on the areal form removal, noise suppressions, or end-effect reducing in surface texture measurements were studied. The variations of the ISO 25178 standard surface topography parameters were taken into consideration in detail. It was assumed that some of the feature sizes, distributions, and densities have a substantial impact on the values of surface topography parameters calculated after applications of regular (commonly used) algorithms and procedures, defined as basic operations, provided for raw surface texture data obtained directly from the measurement process. In the end, some of the practical applications for receiving the relevant values of surface topography parameters were proposed.

About Determing the Microhardness of Composite Coatings

One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.