Modelling of a process, which causes adhesive seizing (tacking) in precise pairs of hydraulic control devices

Abstract

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...

Model of the rate of flow of hydraulic fluid leaking through precision pairs in the electrohydraulic controller of an automatic transmission

“…At present, mathematical modelling has become a research tool increasingly often used to analyse the working processes that take place in hydraulic systems [22,24,26]. The impact of wear of precision pairs in the AT hydraulic system on the values of the rate of internal ATF leakage may be assessed by analysing the results of testing a model of internal leakage in the electrohydraulic AT controller.…”

Outline of a method for estimating the durability of components or device assemblies while maintaining the required reliability level

“…In the available literature, it is possible to find a number of papers, which demonstrate the problem of the impact of the external environment, ageing and wear processes on the technical system functioning [4,9,13,16,17,21]. Due to technical advancement and a high degree of integration of the devices used on the board of military aircraft, the development of optimal operation models is a complex task.…”