Contact Surfaces Of Parts Research Articles

Resurfacing the exhaust valve by plasma spraying versus electric arc and gas flame methods

In modern conditions of economic instability in various sectors of industry for the national economic complex, it is important to improve the technology for repairing parts of power units, while the development of modern technological methods for restoring the contact surfaces of parts should be carried out in the conditions of enterprises and be accessible. The article compares the most common methods of surface parts restoration, such as flame, plasma spraying and electric arc surfacing. Studied experience of various specialists working in this direction made it possible to implement these reduction methods using a charge based on a mineral tungsten-containing concentrate, boron and carbon. The process of alloying the resulting coatings was investigated, where tungsten is in the form of tungsten trioxide (WO3) and calcium tungstate (CaWO4). A comparative analysis of the methods for restoring the surface of the exhaust valve cone of the D49 diesel engine has been carried out. The article presents results of microand macroanalysis of the structures of the obtained coatings and the base metal of the restored part, the results of the analysis of the chemical composition, the evaluation of the microhardness and adhesive strength of the adhesion of the obtained coatings to the surface of the base metal. Authors substantiated the prospect of applying the methods of gas-thermal restoration of the surface of parts in relation to the method of electric arc surfacing. Subsequent studies will focus on the installation of remanufactured parts in the internal combustion engine of the locomotive, their operation in real conditions, and the assessment of reliability and durability. Research in this direction will improve the quality indicators of the restored surfaces of power unit parts of rolling stock.

Взаємодія рослинних олій з робочими контактними поверхнями деталей паливної апаратури дизельних двигунів

Взаємодія рослинних олій з робочими контактними поверхнями деталей паливної апаратури дизельних двигунів

Обеспечение надежности высокотехнологичных сборочных узлов

A procedure is considered for technological support of reliability parameters required in sub-assemblies taking into account the analysis of parameter accuracy changes in operation dimensions at operation stages. There are presented recommendations on updating tolerances and size limit deviations in contact surfaces of parts in assembly units taking into account their formation at machining stages.

The functional and mechanical possibilities of surface alloying by shape memory materials for producing demountable couplings

The possibilities of using the surface alloying by shape memory materials for producing reliable demountable coupling of machine parts and the estimation of functional and mechanical capabilities both surface layers and demountable couplings are described. Design and development solutions of producing these couplings are analyzed. The special attention to development of the tolerances and fits system is given. A necessary condition of developed technique is producing the intermediate layer of shape memory alloy between contact surfaces of parts. Thermoelastic properties of this layer ensure the interference fit in coupling. The argon-arc fusing technique for alloying the contact surfaces of parts is suggested and the same technique for coating of steel by NiTi-alloy is considered. Some technological peculiarities of heat treatment and training of fused layer by means rolling are described. The practical using of suggested technique for producing the built-up crankshafts is offered.

WEAR OF THE SURFACES OF PARTS OF OIL-FIELD EQUIPMENT OPERATING IN AN ABRASIVE MEDIUM

The results of numerous studies show that surfaces treated by different methods deviate from the specified shape and degree of roughness, regardless of the manufacturing technology employed. These errors have a significant effect on the wear of the contact surfaces of parts that comprise friction couples. Thus, they also have a significant effect on the durability of machines in general. The actual area of contact of surfaces depends mainly on their microscopic and macroscopic geometry and the loads applied to them. To a large extent, the wear that the surfaces of parts undergo is caused by the cutting of microscop ic scallop-shaped projections that remain on the surface after the treatment. The quantitative values obtained to characterize wear are a reflection of a volumetric change in the surfaces of parts. The results of the studies in [1] show that metallic su rfaces have roughness at the atomic level and that their highest protuberances are the parts of the roughness that make contact with other surfaces. For metals in air at room temperature, those protuberances may be dust particles. Dust particles can take up most or all of the loads on the surface when those loads are small. An examination of parts that had been machined established that small particles of the material of the tool are almost

Diamond grinding of hard-faced contact surfaces of parts of blast-furnace charging apparatuses

Diamond grinding of hard-faced contact surfaces of parts of blast-furnace charging apparatuses