Analysis of the influence of surface plastic deformation on increasing the wear resistance of machine parts

Matvyeyeva²

2022

The article presents the results of tribological research on the most promising way to restore and increase the wear resistance of engine valves by developing a method of gas nitriding. It is established that with increasing operating time the guide bushings of the outlet connections wear out with the displacement of the axis of the forming surfaces of the hole. Characteristic significant displacement of the axes of the inlet connections is not detected, ie. their wear on the diameter of the hole is 1.5 ... 3 times less than the wear of the exhaust bushings, the values of the displacement of the axes are within the error of the measuring instrument. The average value of ovality is greater in the exhaust seats - the maximum beating values of the intake seats are 0.34 mm, exhaust - 0.22 mm. It is proved that the non-uniformity of the wear of the sleeve hole is determined by the balance of acting forces, which, in turn, are determined by deviations from the optimal ratios μ and e. the side of the rocker arm axis. Distortions of the valve in the longitudinal axis of the engine contribute to an earlier reduction in the tightness of the valve pairs. Redistribution of the valve end material with the formation of a wavy concentric surface, the shape of the contact spot on the rocker arm and the corresponding direction of wear of the saddle chamfer was observed in 43% of the studied connections. Technological means and methods for improving the quality of repair, measuring instruments for accurate study of the parameters of parts and connections of the valve group are given. The results of laboratory and operational tests are presented. A method of gas nitriding with an installation for its implementation has been developed, which provides an environmentally friendly method of low-temperature and high-temperature hardening, obtaining deeper and well-developed layers of the diffusion near-surface zone and reduces training, technological time in the process of strengthening and reducing energy consumption

Section: Research Resultsmentioning

confidence: 80%

Increasing warning resistance of engine valves by gas nitrogenization method

Matvyeyeva²

2022

“…An increase in the effective gap leads to a decrease in the fatigue crack nucleation depth and the exit of the probable fracture point to the surface [13]. This corresponds to the well-known idea that with a further increase in a, there is an accumulation of limit deformations and destruction of the metal surface at the top of the plastic wave already during mechanical processing.…”

Section: A B Fig 1 Interrelationships Of the Accumulated Parameters O...mentioning

confidence: 67%

Study of the Stress-Strain State of the Surface Layer During the Strengthening Treatment of Parts

Matvyeyeva

2022

The paper presents experimental studies and obtained statistical models of the influence of processing modes on the quality of the surface layer and cyclic durability of reinforced machine parts. It was established that the main influence on the strengthening effect, the depletion of the plasticity reserve of the metal and the formation of residual stresses are exerted by the effective gap of the cutter, the effective tension and the profile radius of the roller. The results showed that dimensional combined running-in ensures high cyclic durability of strengthened parts under conditions of multi-cycle fatigue load, which reaches 8 million cycles, which is 3.5 times greater than the durability of a non-reinforced part and 1.5 times - the durability of a part strengthened by surface plastic deformation Studies have shown that the greatest cyclic durability of the part is ensured at the minimum values of the effective cutter gap, the maximum values of the profile radius and the value of the effective roller tension of 0.6 mm, which corresponds to the degree of exhaustion of the plasticity reserve by processing with dimensional compatible rolling Ψ ≈ 0.65. On the basis of the results of theoretical and experimental studies, a methodology and algorithm for the design of processing technology by dimensional combined running-in were developed. A computer program has been developed that allows you to calculate the quality of the surface layer and cyclic durability of the part based on the specified modes, as well as to assign rational processing modes that ensure the specified quality of the surface layer and cyclic durability. Based on the results of research, a technological process of strengthening processing of machine parts by combined dimensional running-in has been developed, which allows forming compressive residual stresses in the surface layer of the processed part, as well as increasing productivity up to 2 times while maintaining or improving the specified quality parameters of the surface layer of the processed part.

“…The optical image of the wear spot of the counterbody (ball) after passes over the investigated surface of the experimental samples (electrospark coatings from BRS and substrate from 30KhGSA steel) is presented in Fig. 8, a-d The optical image of the wear spot showed that when using stainless steel AISI 420 steel as a control (ball) [13], after multiple passes over the tested surface of the experimental samples (electrospark coatings with BRS), the following occurs on the corresponding friction path:…”

Section: Fig 6 X-ray Spectral Microanalysis Of P6m5 Powder At Pointmentioning

confidence: 99%

Increasing the Wear Resistance of Restored Car Parts by Using Electrospark Coatings

Matvyeyeva

2023

The work scientifically substantiates the application of effective technology for the restoration of worn car parts by applying new electrospark coatings based on electroerosion nanomaterials. The developed technology is characterized by technological flexibility, cheapness, simplicity, does not require the use of expensive and scarce materials and equipment, and also meets the requirements of environmental safety. The proposed technology can be used to restore a wide range of parts for cars, tractors and other machines. Experimentally established dependences of the effect of the properties of electroerosive materials on the properties of electrospark coatings of restored car parts. It is shown that the content of nano-sized particles in the electrode material contributes to the improvement of the physical and mechanical properties of electrospark coatings. The dependences of the influence of the properties of electrospark coatings on the resource of restored car parts were experimentally established. It is shown that the resource of the shafts of turbocompressors restored according to the recommended technology is higher than the resource of new shafts by an average of 1.5 times. Experimentally established rational modes of applying wear-resistant coatings to worn shafts of turbocompressors, which provide the necessary complex of physical and mechanical properties of the coating and the given resource of the shafts as a whole (rotation frequency of the part, min - 1 - 50; electrode feed, mm/min - 0.4 ... 0.5). The characteristics of wear resistance of electrospark coatings of turbocompressor shafts, obtained using electroerosion nanomaterials, were studied. It is shown that the average value of the coefficient of friction of the electrospark coating was 0.146 instead of 0.486 without coating, which is 3.3 times lower. According to the results of production tests, it was found that the duration of operation of the turbocharger, with the restored method of electrospark treatment with a nanostructured electrode shaft, increased by 2.1 times compared to a new industrially manufactured shaft. Thus, when abrasive material containing a fraction of 0.1...0.4 mm was introduced, the operating time of the turbocompressor with a restored shaft was 12.8 hours, and the operating time of the turbocompressor with a new shaft without wear of the nominal size was 8.1 hours.