Thermal Analysis of a Crossed Helical Gearbox Using FEM

Overheating of gearboxes with crossed axes, such as crossed helical gearboxes, is one of the greatest disadvantages of these gearboxes in comparison with other drives, such as gearboxes with bevel or cylindrical gears. High friction results in the overheating of the transmission and the occurrence of scuffing. The main cause of the overheating is the generation of heat inside the gearbox due to bearing friction, sealing friction and above all, friction between tooth flanks during engagement. By applying the finite element method, thermal stability of a gearbox was predicted, and this procedure was verified on the case of a crossed helical gearbox with an axial distance of 30 mm. Based on the performed numerical investigation, a new procedure for the prediction of heat generation in the crossed helical gear transmission was proposed

PREDICTION OF TEMPERATURE DISTRIBUTION IN THE WORM GEAR MESHING

Worm gear transmissions have number of advantages over other types of transmission, allowing them a wide scope of applications for the transfer of power and movement. One of the important advantages of this transmission is the possibility of obtaining a large transmission ratio. The lack of worm gear transmission means a relatively low efficiency, especially for the extreme operating conditions primarily related to the high frequency of rotation. Between the flanks of worm and worm gears there is considerable slippage, which results in wear at the worm gear flank and considerable significant power losses that are converted into heat. The amount of energy that is converted into heat to a large extent is determined by the friction coefficient between the flanks. It is therefore very important to take into consideration the process of tribo-system mesh of flanks and lubricant. The paper presents FEM calculated distribution of transmission temperature based on the data about power losses obtained analytically. The resulting temperature distribution is compared to the experimental research

DETERMINATION OF RESIDUAL STRESS IN THE RAIL WHEEL DURING QUENCHING PROCESS BY FEM SIMULATION

Residual stresses of the rail wheels are influenced by heat treatment during the manufacturing process. The quenching process during the manufacturing results in the residual stresses within the rail wheel that may be dangerous for the rail wheel during its operation. Determination of the residual stress in the rail wheel is important for understanding the damage mechanisms and their influence on the proper work of rail wheels. This paper presents a method for determining the residual stresses in the rail wheel during the quenching process by using the directly coupled thermal-structural analysis in ANSYS software

INTELLIGENT MACHINE VISION BASED RAILWAY INFRASTRUCTURE INSPECTION AND MONITORING USING UAV

Traditionally, railway inspection and monitoring are considered a crucial aspect of the system and are done by human inspectors. Rapid progress of the machine vision-based systems enables automated and autonomous rail track detection and railway infrastructure monitoring and inspection with flexibility and ease of use. In recent years, several prototypes of vision based inspection system have been proposed, where most have various vision sensors mounted on locomotives or wagons. This paper explores the usage of the UAVs (drones) in railways and computer vision based monitoring of railway infrastructure. Employing drones for such monitoring systems enables more robust and reliable visual inspection while providing a cost effective and accurate means for monitoring of the tracks. By means of a camera placed on a drone the images of the rail tracks and the railway infrastructure are taken. On these images, the edge and feature extraction methods are applied to determine the rails. The preliminary obtained results are promising

PITTING OF TOOTH FLANKS OF CROSSED HELICAL GEARS MADE OF SINTERED STEEL

Crossed helical gears are used in cars and in many household appliances. The trend towards increased comfort in motor vehicles has led to the utilisation of more than a hundred servo-drives in luxury class automobiles. Important advantages of crossed helical gears are their easy and inexpensive design, low noise performance and high gear ratio that can be realised in one step. Sintered steel is a material with very favourable properties for the manufacture of crossed helical gears. High demands are set on gears made from sintered steel regarding wear and pitting load capacity. This report shows the results of the investigation into pitting resistance of crossed helical gears made of iron-based sintered material Fe1.5Cr0.2Mo that has undergone additional treatment

DETERMINATION OF RESIDUAL STRESS IN THE RAIL WHEEL DURING QUENCHING PROCESS BY FEM SIMULATION

Residual stresses of the rail wheels are influenced by heat treatment during the manufacturing process. The quenching process during the manufacturing results in the residual stresses within the rail wheel that may be dangerous for the rail wheel during its operation. Determination of the residual stress in the rail wheel is important for understanding the damage mechanisms and their influence on the proper work of rail wheels. This paper presents a method for determining the residual stresses in the rail wheel during the quenching process by using the directly coupled thermal-structural analysis in ANSYS software

TOWARDS MACHINE VISION BASED RAILWAY ASSETS PREDICTIVE MAINTENANCE

The main goal of this paper is to present novel technologies that can contribute to safety, competitiveness, efficiency and operational reliability of Railway infrastructure through the development of innovative solutions for measuring and monitoring of railway assets based on machine vision. Measuring the transversal position of the wheels on the rail, as well as identification of the defects of the wheel and the rail (such as deformation of rail head edge, lateral wear, worn wheels, cracks in wheel and rail, rolling contact fatigue, corrugation and other irregularities) can increase reliability and lower maintenance costs. Currently, there is a need on the market for the innovative solution, namely the on-board high-speed stereo camera system augmented with a system that projects custom pattern (fringe scanner system) for measuring the transversal position of the wheels on the rail, robust to environmental conditions and waste along the track that can provide reliable measurements of transversal position of the wheels up to 200 km/h. New trends in Precise Industrial 3D Metrology are showing that stereo vision is an absolute must have in modern specialized optical precision measuring systems for the three-dimensional coordinate measurement

DIGITAL TWIN BASED LIGHTWEIGHTING OF ROBOT UNMANNED GROUND VEHICLES

Battery powered outdoor robot Unmanned Ground Vehicles (UGV) should have minimal mass for designed payload capacity to facilitate their movement on rough terrain and increase their autonomy. On the other hand, stiffness and strength of their mechanical components should be sufficient to sustain operational loads. The paper presents the case study of robot UGV lightweighting based on UGV digital twin data. The process of creation of robot UGV digital twin is described, as well as the type and quantity of data acquired from robot sensors. Based on the data from the digital twin of the robot about operational loads, the worst operational load cases were identified and the structural analysis of the robot chassis for noted load cases was performed. The results of the analysis were used in the topology optimization of the robot UGV mechanical components with a goal to satisfy design requirements and reduce the robot mass. By application of noted procedure the mass reduction of approximately 17 % was achieved

WEAR LOAD CAPACITY OF CROSSED HELICAL GEARS

The paper presents a wear load capacity of crossed helical gears (gear pair consists of a worm and a helical gear). Crossed helical gears are similar to worm gear pairs, and it is logical to extend the load capacity calculation approach of worm gears for the case of crossed helical gears. One of the disadvantages of crossed helical gear sets is very high running-in wear. The paper explains the transition between running-in and steady-state wear and proposes a joint wear calculation model. The paper outlines a proposal to extend the calculation method for wear load capacity from a worm gear pair to the case of crossed helical gears (a worm with a helical gear). This calculation method for determining the wear load capacity of crossed helical gears is verified for the cases when the wheel is of bronze CuSn12Ni2-C-GCB and sintered steel Fe1.5Cr0.2Mo

EXPERIMENTAL AND FEM ANALYSIS OF SINTERED STEEL WORM GEAR WEAR

Crossed helical gears with steel worms and sintered steel wheels are widely used in motor vehicles and household appliances. Besides the experimental study of a prototype transmission, the simulation using the finite element method (FEM) is another possibility to test gears under load in the design phase and to optimize them. As part of this paper, a piece of software was developed that enables calculation of wear-related variables, such as the Hertzian stress σH, the minimum lubrication film thickness hmin and the glide path sg, for every single point of the contact between worm and worm gear