scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

scholarly journals Tooth Root Bending Strength of Gears: Dimensional Effect for Small Gears Having a Module below 5 mm

2021 ◽  
Vol 11 (5) ◽  
pp. 2416
Author(s):  
Franco Concli
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Size Factor ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Gear Design ◽  
Industrial Sectors ◽  
Load Carrying ◽  
European Standards ◽  
Design Effectiveness

Downsizing is a more and more widespread trend in many industrial sectors, and, among the others, the automotive industry is pushing the design of its components towards increasingly compact, lightweight, efficient, and reliable solutions. In the past, the drivetrains for automotive were designed and manufactured with gears having modules in the range 3 to 10. In this respect, the main actual European standards for gear design such as ISO 6336:2019 (based on the DIN 3990:1987) are validated in the 3 to 10 mm range only. Moreover, it is well known that, by increasing the gear size, the gear size factor for tooth bending YX reduces. However, nowadays the advances in terms of materials and design knowledge have made possible the realization of miniaturized gearboxes with gears having normal modules below 3 mm with comparable (or better) reliability. In this scenario, understanding how the size affects (positively) the load-carrying capacity for tooth root bending for small modules below 5 mm is fundamental to maximize the design effectiveness in case of downsizing of the drivetrains. In this paper an experimental study was performed on small gears made of 39NiCrMo3 having a normal module of 2 mm to verify the load-carrying capacity for tooth root bending. Based on the experimental evidences and additional data from literature and past studies by the author, an extended formula for the size factor YX (according to ISO 6336) is proposed.

A Comparison of Porous Structures on the Performance of a Slider Bearing with Surface Roughness in Couple Stress Fluid Film Lubrication

2015 ◽  
Vol 813-814 ◽  
pp. 921-937
Author(s):  
P.S. Rao ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Type Equation ◽  
Random Variable ◽  
Couple Stress Fluid ◽  
Load Carrying Capacity ◽  
Porous Structures ◽  
Slider Bearing ◽  
Load Carrying

This paper presents the theoretical study and analyzes the comparison of porous structures on the performance of a couple stress fluid based on rough slider bearing. The globular sphere model of Kozeny-Carman and Irmay’s capillary fissures model have been subjected to investigations. A more general form of surface roughness is mathematically modeled by a stochastic random variable with non-zero mean, variance and skewness. The stochastically averaged Reynolds type equation has been solved under suitable boundary conditions to obtain the pressure distribution in turn which gives the expression for the load carrying capacity, frictional force and coefficient of friction. The results are illustrated by graphical representations which show that the introduction of combined porous structure with couple stress fluid results in an enhanced load carrying capacity more in the case of Kozeny-Carman model as compared to Irmay’s model.

Performance analysis of rough surface hybrid thrust bearing with elliptical dimples

2020 ◽  
pp. 135065012093198
Author(s):  
Vivek Kumar ◽  
Satish C Sharma
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Machining Process ◽  
Fluid Film ◽  
Textured Surface ◽  
Stiffness Coefficient ◽  
Load Carrying Capacity ◽  
Power Losses ◽  
Load Carrying ◽  
Film Stiffness

Surface roughness is inherent to all machining processes. Therefore, even a high precision machining process renders micro-roughness to some extent on the surface of conventional materials. The asperities height of many rough engineering surfaces follows Gaussian distribution. The surface roughness on the bearing surface may significantly affect the bearing performance. Surface texturing is emerging as a new technique to improve the tribological behavior of the mating surfaces. Usually dimensions/height of micro-roughness is of order of the depth of surface textures in fluid film bearings. Neglecting micro-roughness while numerically simulating a textured surface bearing may generate inaccurate bearing performance data. In presented work, finite element simulation of textured surface hybrid thrust bearings has been performed. Surface texture is provided over thrust pad in the form of regular arrays of elliptical dimples. A parametric optimization is carried out to determine optimum attributes of elliptical dimple (axis, depth, texture length and orientation) so that the load-carrying capacity and fluid film stiffness should be maximized and film frictional power losses should be minimized. Use of textured surface (with optimum elliptical dimple attributes) results into a significant enhancement in load-carrying capacity (91.3%), film stiffness coefficient (+98.8%) and reduction in frictional power losses (−48.3%). It is also observed that elliptical dimple and micro-roughness (transverse orientation) generate synergistic effects in further enhancing the load-carrying capacity (+101.4%) and film stiffness coefficient (+112%) of the bearing.

Influence of the Case Properties After Nitriding on the Load Carrying Capacity of Highly Loaded Gears

2019 ◽  
Author(s):  
André Sitzmann ◽  
Thomas Tobie ◽  
Karsten Stahl ◽  
Stefan Schurer
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Cost Savings ◽  
High Hardness ◽  
Compound Layer ◽  
Alloy Element ◽  
Case Hardening ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Highly Loaded

Abstract The load carrying capacity of highly loaded gears can be increased by thermochemical surface treatments such as nitriding or case hardening. In contrast to case hardening, the nitriding treatment is carried out at lower process temperatures and therefore creates lower distortion. As a result, grinding after nitriding is usually not necessary. Nitrided gears are ordinarily characterized by a thin, high-hardness, a few micrometers thick compound layer of iron and alloy element nitrides directly on the surface and a subsequent diffusion layer reaching more deeply into the material. Nitriding, therefore, provides an alternative to case hardening for distortion-sensitive components and offers potential for cost savings in the production of highly loaded gears. This publication will focus on the influence of nitriding on the load carrying capacity of highly loaded gears. In addition, this paper summarizes the current state of knowledge of nitrided gears and gives an insight into current research in the field of nitrided gears. In particular, the influence of the compound layer on the tooth root bending strength and the flank load carrying capacity achieved within the research project FVA 386 II is discussed.

Uniform Loading Analysis for Pin-Hole-Output Mechanism of FA Cycloid Drive

2012 ◽  
Vol 479-481 ◽  
pp. 925-931
Author(s):  
Lei Lei ◽  
Ying Tao ◽  
Tian Min Guan
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Deformation Analysis ◽  
Load Carrying Capacity ◽  
Bending Stress ◽  
Uniform Loading ◽  
Force Loading ◽  
Load Carrying ◽  
Stress And Deformation ◽  
Loading Analysis

In order to balance the force loading on the dowel pin , improve the load carrying capacity on pin-hole type output mechanism the FA cycloid drive, we considered to add uniform loading ring on the cantilever end of the pins in this paper. Under the action of uniform loading ring, we did the stress and deformation analysis on the dowel pin; Through the examples comparison we found that, the maximum bending stress of the dowel pin is reduced by 77.86% after adding the uniform loading ring, the dowel pin stress is well-distributed, and the bending strength of output mechanism is improved, thus the load carrying capacity of overall unit is improved.

scholarly journals Deep nitriding—contact and bending strength of gears with increased nitriding hardening depth

2021 ◽  
Author(s):  
André Sitzmann ◽  
Stefanie Hoja ◽  
Stefan Schurer ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Carrying Capacity ◽  
Bending Strength ◽  
Experimental Investigations ◽  
Case Hardening ◽  
Load Carrying Capacity ◽  
Industrial Practice ◽  
Aerospace Applications ◽  
Upper Limit ◽  
Load Carrying ◽  
High Fatigue

AbstractThe load carrying capacity of gears can be significantly increased by nitriding. However, the required nitriding hardening depth depends on the stress level and the gear size. In order to achive a high fatigue resistance and durability of nitrided gears an adequate nitriding hardening depth is necessary. In industrial practice, a nitriding hardening depth (NHD) of about 0.6 mm is currently regarded as the upper limit that can be reached within a reasonable time and cost. This also limits of the load carrying capacity of nitrided gears, in particular with increasing gear sizes. Therefore, case hardening is the main treatment used with increasing gear sizes, although nitriding provides some advantages over case hardening. However, with an increased nitriding hardening depth, a significant increase in the load carrying capacity of nitrided gears for medium and larger gear sizes could be expected, which will be discussed in this publication. In order to evaluate the expected potential of the load carrying capacity of nitrided gears with an increased nitriding hardening depth of NHD ≈ 0.8 to 1.0 mm (deep nitriding heat treatment) made out of the materials 31CrMoV9 (1.8519), 30CrNiMo8 (1.6580) and 32CDV13 (alloy for aerospace applications according to AIR 9160), experimental investigations were carried out, which will be discussed in this publication. Both, the tooth root bending strength and the flank load carrying capacity were investigated.

scholarly journals MULTIGRID METHOD FOR THE SOLUTION OF COMBINED EFFECT OF VISCOSITY VARIATION AND SURFACE ROUGHNESS ON THE SQUEEZE FILM LUBRICATION OF JOURNAL BEARINGS

2017 ◽  
Vol 46 (1) ◽  
pp. 1-8
Author(s):  
Vishwanath B. Awati ◽  
Ashwini Kengangutti ◽  
Mahesh Kumar N.
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Multigrid Method ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Viscosity Variation ◽  
Film Lubrication

The paper presents, the multigrid method for the solution of combined effect of surface roughness and viscosity variation on the squeeze film lubrication of a short journal bearing operating with micropolar fluid. The modified Reynolds equation which incorporates the variation of viscosity in micropolar fluid is analysed using Multigrid method. The governing modified Reynolds equation is solved numerically for the fluid film pressure and bearing characteristics viz. load carrying capacity and squeeze time. The analysis of the results predicts that, the viscosity variation factor decreases the load carrying capacity and squeeze film time, resulting into a longer bearing life. The results are compared with the corresponding analytical solutions.

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