Yağ Çalışma Sıcaklığının Dişli Yüzey Hasarları Üzerine Etkisi (original) (raw)
Related papers
Influence of gear surface roughness on the pitting and micropitting life
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
Pitting and micropitting are the two main gear rolling contact fatigue modes. It is widely accepted that micropitting will lead to pitting; however, the relationship between pitting and micropitting life needs further investigation. In this work, micropitting and pitting tests were performed on an FZG back-to-back test rig using standard FZG PT-C and GF-C gears. The gear tooth profile change due to micropitting and pitting damage was measured in situ in the gearbox using a profilometer after each test. The gear surface roughness parameters were calculated from the measured tooth profile. A Gaussian low pass filter with cut off length [Formula: see text] mm was applied to the measured tooth profile to obtain the waviness. The calculated roughness parameters and the obtained tooth profile with waviness for each test were imported into the KISSsoft software to calculate the contact stress and specific film thickness at the corresponding load stage. Experimental results show that smooth...
One of the main gear damage mechanisms is the formation of pitting and spalling on the tooth flank. Several factors have significant influence on the damage formation, such as: contact stress level; tooth profile type; relative contact speed; surface finish and lubrication conditions. This work comprehends the global observation of all such parameters and was carried out to explain the phenomena related to this wear mechanism. The wear test equipment uses the power recirculation principle and is commonly known as FZG test rig. The gears were made from AISI 8620 steel and had two types of surface finishing (by shaving or by milling). The wear experiments were performed with two torque stages: 135 N.m (running-in) and 302 N.m (steady-state), and two test temperatures: 60°C (running-in) and 90°C (steady-state). The wear level was determined by using image analysis. In order to calculate the specific film thickness and friction coefficient, the roughness of tooth flank was measured at each test stop. After the experiments were completed, it was possible to confirm that, for both manufacturing processes, the boundary lubrication regime was adopted at the tooth flank and the specific film thickness presents a different behavior when compared to addendum, pitch diameter and deddendum regions. The wear on the gear flanks depended on the lubricant film thickness and it was higher for the milled gears.
Detection and Diagnosis of Gear Tooth Wear through Metallurgical and Oil Analysis
Tribology Online, 2010
Gear teeth wear, in most cases, by a smooth process giving initially good contact conditions, followed by a very slow and gradual process. Further, continuous progression of tooth wear may cause unfavorable changes of surface topography, thereby, giving rise to worsened contact situations. The metal removed from the worn teeth surfaces enter into the machine system and can, in turn, cause failure of other components, finally resulting in a severe form of tooth failure. The causes and subsequent prevention of the damage due to wear can be studied by oil/wear particle analysis of lubricants under operating conditions. This paper describes the results of experimental studies performed for evaluation of lubricant film thickness, wear particle analysis based on their morphology, metal composition analysis of lubricants using X-ray fluorescence, atomic absorption spectrometry (AAS) and Energy dispersive spectrometry (EDS). These results have been correlated with wear.
The Appearance of Pitting Wear on Gears and Some of the Factors That Influence It
2018
Abstract: This article aims to evoke some aspects of the fatigue cracks that have the consequence of pitting wear appearance on the spur gears. Different factors acting on the already propagated cracks and opened to the surface of the gear tooth will be considered. The result is the appearance of a pit. The stresses field corresponding to the contact between two cylinders that shape the contact between the teeth flanks was presented. A possible way of forming the cracks that start from the surface of the flanks is also presented. Key words: pitting, fatigue crack, pits, gear, stresses field, rollers, lubricant, voids, inclusions.
Tribology International, 2006
In this investigation, an experimental campaign, dedicated to the tribological characterization of surface treatments for gears, is presented. Wear in gears is herein simulated by means of a Ring-on-Ring test machine, where the ring and the cylinder are chosen in such a way that the kinematic and dynamic conditions are as much as possible similar to those presented in the teeth contact, in one of the two extreme points of the action line. The dynamics is simulated by imposing the same contact stress, while the kinematic conditions are applied by assuming in the two systems the same ratio of the specific slide rather than the same sliding speed. The latter choice is justified by the results shown in a preliminary test phase, which have shown the importance of the specific slide for the prediction of wear in gear profiles. The apparatus has shown a fair prediction capacity and has been used to compare the different wear resistances and typologies of gear pairs having different surface treatments. Results are herein presented and briefly discussed. q
Lubricant Influence on Slow Speed Wear in Gears
2011
In gears running under conditions of high load and low circumferential speed the lubricant film thickness is often not sufficient to fully separate the mating surfaces. Wear of the gear flanks can occur and can even result in total gear failure. For a given gear geometry the main influencing parameters are load, circumferential speed and lubricant. The wear characteristics of lubricants depend on many factors. Viscosity, base oil type and additives have great influence. In slow speed gears mostly lubricants with anti-wear (AW) additives reducing wear by forming chemical and/or physical protection layers are used. For testing the wear capacity of lubricants a suitable test method was developed using a modified FZG back-to-back gear test rig. The FZG slow speed wear test C/0.05/90:120/12 is run under very low circumferential speeds of v = 0.05 m/s and 0.57 m/s and at two different test temperatures oil = 90 °C and 120 °C. The test consists of three parts and is run in several interva...
Tribology International, 2009
Gears are one of the most common mechanisms for transmitting power and motion and their usage can be found in numerous applications. Studies on gear teeth contacts have been considered as one of the most complicated applications in tribology. Depending on the application, the speed and load conditions of teeth may change triggering several types of failures on teeth surface such as wear, scuffing, micro-pitting and pitting. The above-mentioned faults influence changes in vibration and acoustic signals, due to changes in operating conditions such as increase in temperature and decrease in lubricant film thickness and specific film thickness. These abnormal changes result in cumulative effects on localised or distributed faults on load bearing surfaces of gears. Such damages cause reduction in tooth stiffness and severity of damage can be assessed by evaluating the same using vibration-based signals. This paper presents the results of experimental investigations carried out to assess wear in spur gears of back-to-back gearbox under accelerated test conditions. The studies considered the estimation of operating conditions such as film thickness and their effects on the fault growth on teeth surface. Modal testing experiments have been carried out on the same gear starting from healthy to worn out conditions to quantify wear damage. The results provide a good understanding of dependent roles of gearbox operating conditions and vibration parameters as measures for effective assessment of wear in spur gears.
Rolling-sliding-contact fatigue damage of the gear tooth flanks
Engineering review, 2010
During the meshing of involute gears, their teeth flanks are subjected to cyclic contact pressure loading and simultaneous rolling and sliding. The mentioned loading can induce a specific type of material fatigue that is commonly denoted as rolling-sliding-contact fatigue. In this work, individual phases of fatigue occurring due to the cyclic loading are described. Furthermore, different types of fatigue damage of gear teeth flanks are classified and for each type, its causes and features are given. The information presented can be used for prevention or subsequent identification and remedial action in the case of fatigue damage of gears in power transmissions.