Оптимізація виробничої програми підприємств методом математичного моделювання

oating is one of the innovative approaches used to improve the wear resistance and load-carrying capacity of surfaces in rolling-sliding contact, such as gears and rolling element bearings. In this study, the tribological performance of standard gear material (16MnCr5) and two kinds of powder metallurgy (PM) gear material (Distaloy AQ + 0.2% C and Astoloy 85Mo +0.2% C) with and without tribofilms formed by a pre-treatment were evaluated. Specimens treated with the pre-treatment and the substrate is subjected to pin-on-disc tests under boundary lubrication conditions. The friction and wear performance of the two different PM gear materials with the pre-treatment formed tribo-film were compared to RS-RS (16MnCr5 material disc and pin combination) for reference. It was found that the pre-treatment lowers the friction coefficient and enhances the wear resistance of pins because of the tribo-film formed. The tribo-film caused good running-in due to the existing of  and Fe and W oxides. Mo-Mo (Astoloy 85Mo + 0.2% C material disc and pin combination) and Mo-RS (Astoloy 85Mo + 0.2% C disc and 16MnCr5 pin combination) showed statistically significant higher wear resistance.QC 20160523</p

Towards real time automated early gear failure detection

The ability to stop a gear fatigue test before catastrophic failure has many advantages. However, today, a widely accepted approach is not available. This case study applies a vibration-based condition monitoring methodology to detect early gear failures. The gear studied takes part in an all-wheel-drive drivetrain system. Vibration signals from four run-to-failure fatigue tests at two constant torque-speed combinations were used as input to time-synchronous averaging and autoregression model generation. The applied methodology shows promising results for early failure detection, and the process is feasible for implementation in an automated environment. Real time analysis is also possible since the autoregression model generates a healthy state TSA signal during the early testing stages. However, the time to failure detection varies with operating conditions, with low sensitivity at high-speed and low-torque conditions

Nanoparticle emissions from the transport sector: health and policy impacts - the nPETS concept

Road, rail, air, and sea transport generate a major fraction of outdoor ultrafine particles. However, there is no common methodology for comparable sub 100 nm particle emissions measurement. This paper presents the nPETS (grant agreement No 954377) concept to understand and mitigate the effects of emerging non-regulated nanoparticle emissions. This paper presents the concept and selected results. For example, nucleation and condensation mechanisms occur more frequently in the urban background site, leading to new particle formation, while mostly fresh emissions are measured in the traffic site.This work is part of nPETS, a project that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 954377Peer reviewe

On tribological design in gear tooth contacts

The correct tribological design will have a considerable effect on a gear’s service life and efficiency. The purpose of this thesis is to clarify the impact of variation in the gear tooth flank tribological system on the gear contact load capacity – to increase the understanding of how surface topography and lubricant interact. In this thesis the variation in surface topography inherent in the manufacturing method has been shown, by experimental work and computer simulations, to be an important factor for the contact condition in the early life of gears. Surface analysis revealed that the formation and composition of surface boundary layers depends strongly on the chemical composition of the lubricant, but also on pre-existing surface boundary layers. Additionally, surface boundary layers play a major role in frictional behaviour, wear and in allowing the lubricant to react properly with the surfaces. Paper A presents the current ISO 6336 calculation of surface durability. A robust design approach was used to investigate the extent to which the current standard for calculation of surface durability allows for manufacturing variations and the choice of lubricant. Paper B investigates the extent to which a logarithmical profile modification can increase gear contact pressure robustness compared to traditional lead profiles for gears. Paper C compares different gear manufacturing methods and their as-manufactured (fresh unworn) surface topographies, using measured surface topographies as input to a contact simulation program. Paper D examines surface boundary layer formation and the corresponding wear in relation to different anti-wear additives in an environmentally adapted base oil. Papers E and F make use of specimens with surface topographies imitating two gear manufacturing methods (grinding and superfinishing) to be used in a twin-disc and barrel-on-disc machine respectively. The contacts are analysed by friction measurements and simulations combined with methods for surface analysis.QC 20120925</p

Influence of gear surface roughness, lubricant viscosity and quality level on ISO 6336 calculation of surface durability

QC 2012021

Influence of gear surface roughness, lubricant viscosity and quality level on ISO 6336 calculation of surface durability

QC 2012021

Virtual Hobbing

Hobbing is a widely used machining process to generate high precision external spur and helical gears. The life of thehob is determined by wear and other surface damage. In this report, a CAD approach is used to simulate the machiningprocess of a gear tooth slot. Incremental removal of material is achieved by identifying contact lines. The paper presentsan example of spur gear generation by means of an unworn and a worn hob. The two CAD-generated gear surfaces arecompared and showed form deviations.QC 2012020

Influence of gear surface roughness, lubricant viscosity and quality level on ISO 6336 calculation of surface durability

QC 2012021

Influence of surface topography and lubricant design in gear contacts

The purpose of this thesis was to study the influence of manufacturing variations on gear performance. The manufacturing variations inherent in different manufacturing methods were studied to include the effect of real surfaces. Real surfaces have surface irregularities at least on some scale, which can significantly influence how loads are transmitted at the gear contact. To some extent, the lubricant design can help to prevent contact that could lead to tooth failures by forming a protective surface boundary layer. An experimental study was used to consider the compositions of these layers with a surface analysis method. In Paper A a robust design approach was used to find out to what extent the current standard for calculation of surface durability treats manufacturing variations and the choice of lubricant. The results show that the simplest calculation method used is not enough to predict the effect of these on surface durability. Additionally, the standard quality levels are poorly incorporated in the standard calculating procedures for surface durability, and the quality of the gear tooth is restricted to include only a few parameters. In Paper B a pin-on-disc machine was used to evaluate the tribofilm formation by the additives and the corresponding wear occurring in the boundary lubrication regime in environmentally adapted lubricants. Studies of the additive and base fluid interaction were carried out using glow discharge-optical emission spectroscopy. It was found that the chemically reacted surface boundary layers played an important role in terms of wear. More specifically, the oxide layer thickness had significant influence on wear. The findings also demonstrate the complexity of lubrication design formulations coupled to these layers. For example, it was found that the pre-existing surface boundary layer (before any lubricant had been added) played an important role in allowing the lubricant to react properly with the surfaces. The aim of Paper C was to contribute to the knowledge of how different surface topographies, tied to manufacturing methods, influence the early life contact conditions in gears. Topographical measurements of differently manufactured tooth flanks were used as data input to a contact analysis program. The variation in surface topography inherent in the manufacturing method was found to have a strong influence on the contact area ratio