No abstract

The tendency to increase the temperature of gases and the desire to extend the service life forces the use of a protective coating on the blade. The publication presents the technology of applying a heat-resistant protective coating onto the jet engine turbine blade by means of plasma thermal spraying, taking into account the process of aluminizing and heat treatment after aluminizing. The paper presents the results of work on the possibilities of shaping the thickness of the protective coating on the blade by changing the parameters of the spraying process, such as spraying distance, amount of hydrogen, amount of argon and the number of torch passes.

Hydraulic pumps are among the most complex and responsible units from the point of view of aircraft flight safety. One of the most important scientific and technical problems in improving the reliability of hydraulic pumps is to understand the physical nature of the cause of damage in them and on this basis to develop measures and recommendations to ensure their reliability. The article discusses the characteristics of hydraulic piston pairs of hydraulic pumps according to the kinematics of their movement and load conditions. Selected actual damages of axial piston pumps are discussed. The paper presents a simplified 3D solid model of the cylinder-piston assembly and the mechanism for adjusting the inclination of the piston cylinder block, the axial hydraulic pump, and the model of breaking loads for selected elements of this pump. The digital solid model and element load analysis were developed in SolidWorks Simulation.

Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionOne of the most important tasks in the complex of activities aimed at increasing the use quality of a hydraulic drive are studies concerning the impact of working conditions of hydraulic precise pairs on their wear process, meaning, the durability of a hydraulic drive [1,6,7,8,13,19,20,23,24]. On the basis of data available in the scientifictechnical literature on the wear processes of precise pairs and hydraulic precise pairs, it can be concluded that the dominating wear process is wear due to oxidation [1,3,4,5,11,13,14,21]. The fact that the wear due to oxidation is dominating during operation of a hydraulic precise pair, guarantees low wear intensity of cooperating pair surfaces [1,4,5,13,14]. Wear due to oxidation is conditioned mainly on maintaining during operation the load (pressure and sliding velocity) of hydraulic precise pair's elements below the critical value ( fig. 1) [21]. Fig. 1 presents the relation the wear and the friction coefficient and the slide velocity for the matching of a hydraulic pair made from 12HN3A (HRC = 60) steel and the EI-928 (HRC =60) steel) in an environment of ASF-41 hydraulic oil, at a temperature of 293 K and loads of P axis = 100 N, 600 N, 1400 N. Under overcritical values of the slide velocity, there is a stepwise and rapid quantitative change of the friction coefficient between the surfaces of the hydraulic pair's elements ( fig. 1b). After reaching the critical slide velocity the adhesive seizing process is initiated and tacking processes of metal surfaces of the hydraulic pair start to dominate on friction surfaces [10,12,18,21]. Though knowledge about wear mechanisms has significantly developed, we still lack a general image of the impact process under specific conditions of cooperation between elements of a precise pair.When studying the damageability of correlated metal surfaces in conditions of contact-vibration displacement, usually all attention was paid to the development of fretting-corrosion, i.e., to abrasiveoxidizing processes and not tacking [3,4,10,11,14]. It is explained by the fact that during vibration friction and an oxidized contact zone, damages are created in the form of pitting, filled with damage prod-UŁANOWICZ L. Modelling of a process, which causes adhesive seizing (tacking) in precise pairs of hydraulic control devices. Eksploatacja i Niezawodnosc - Maintenance and Reliability 2016; 18 (4): 492-500, http://dx.doi.org/10.17531/ein.2016.4.3. Leszek UŁANOWICZ Modelling of a process, which causes adhesive seizing (tacking) in precise pairs of hydraulic control devicesModelowanie procesu wywołującego zacieranie adhezyjne (sczepianie) w parach precyzyjnych hydraulicznych urządzeń regulacyjnych* [4,14,18]. To develop such a process, relative displacements of touching sections of correlated surfaces, measuring a part of a micrometer.There is a view that in the initial stage of the fretting-corro...

Violation of The Steady-State Friction behaviour of A Precise Hydraulic Pair Due To Imbalanced Radial Hydrostatic Force W hat has been presented in the paper is a question of violation of the steady-state friction behaviour of a sliding hydraulic pair due to imbalanced radial hydrostatic force that affects the pair. The origins of hydrostatic radial forces in a sliding pair and the effect of this imbalance have been discussed. Computations have been outlined to illustrate how radial hydrostatic forces affect the cylindrical slide. Reasons for the cylindrical slide getting wedged in the sleeve have also been shown. Qualitative assessment of radial forces on the cylindrical slide located in the sleeve has been carried out, and the amounts of imbalance - shown. The qualitative assessment of radial forces in the precise hydraulic pair included a few characteristic variants of a non-uniform distribution of pressure of the working liquid in the annular clearance between the slide and the sleeve. The ways of reducing the imbalance of radial forces from liquid's pressure that affect the cylindrical slide of the hydraulic pair.