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.

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.

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.

Influence of tribofilms on failures and friction of gears with particular focus on running-in

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Andreas Ziegltrum ◽  
Stefan Emrich ◽  
Thomas Lohner ◽  
Klaus Michaelis ◽  
Alexander Brodyanski ◽  
...  
Keyword(s):  
Surface Analysis ◽  
Carrying Capacity ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Load Carrying Capacity ◽  
Friction Behavior ◽  
Content Type ◽  
Load Carrying ◽  
Gear Contact ◽  
Local Pressures

Purpose This paper aims to address the influence of tribofilms and running-in on failures and friction of gears. The operation regime of gears is increasingly shifted to mixed and boundary lubrication, where high local pressures and temperatures occur at solid interactions in the gear contact. This results in strong tribofilm formation due to interactions of lubricant and its additives with the gear flanks and is related to changes of surface topography especially pronounced during running-in. Design/methodology/approach Experiments at a twin-disk and gear test rig were combined with chemical, structural and mechanical tribofilm characterization by surface analysis. Pitting lifetime, scuffing load carrying capacity and friction of ground spur gears were investigated for a mineral oil with different additives. Findings Experimental investigations showed a superordinate influence of tribofilms over surface roughness changes on damage and friction behavior of gears. Surface analysis of tribofilms provides explanatory approaches for friction behavior and load carrying capacity. A recommendation for the running-in of spur gears was derived. Originality/value Experimental methods and modern surface analysis were combined to study the influence of running-in and tribofilms on different failures and friction of spur gears.

The Axial Load-Carrying Capacity of Radial Cylindrical Roller Bearings

1970 ◽  
Vol 92 (1) ◽  
pp. 129-134 ◽  
Author(s):  
H. Korrenn
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Oil Viscosity ◽  
Application Range ◽  
Roller Bearings ◽  
Load Carrying ◽  
Thrust Load ◽  
Cylindrical Roller

Thrust load transmission at the contact areas of roller ends and flanges occurs under conditions of pure sliding. Recent theoretical and experimental investigations showed that with adequately designed roller ends and flanges and with a satisfactory lubricant high thrust loads can be accommodated over a wide speed range with fully hydrodynamic lubrication. The conventional methods used for the determination of the safe thrust load should be revised and supplemented. Oil viscosity should be introduced as an important parameter. Contrary to present opinion the hydrodynamic load-carrying capacity at the flange increases with increasing speed. This new knowledge broadens the application range of radial cylindrical roller bearings.

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 Experimental Investigations of Concrete Filled Battened Steel Columns of Different Slenderness

2019 ◽  
Vol 65 (4) ◽  
pp. 3-19
Author(s):  
M. Siennicki
Keyword(s):  
Carrying Capacity ◽  
Concrete Columns ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Design Standards ◽  
Steel Columns ◽  
Load Carrying ◽  
Bare Steel ◽  
Concrete Filling ◽  
Full Scale Tests

AbstractThe study investigates the axial load behaviour of concrete filled battened steel columns not covered by the design standards. A series of full scale tests on two I-sections connected together with intermediate batten plates and filled with concrete were carried out. The main parameters varied in the tests are length of the members and strength of the concrete filling. One bare steel member was also tested and results were compared with those filled with concrete. The tests results were illustrated by load-strain curves. The main objectives of these tests were twofold: first, to describe behaviour of new steel-concrete columns and second, to analyze the influence of slenderness on load-carrying capacity.

scholarly journals Effect of Use Recycled Coarse Aggregate on the Behavior of Axially Loaded Reinforced Concrete Columns

2019 ◽  
Vol 25 (10) ◽  
pp. 88-107
Author(s):  
Omar Shamal Farhan
Keyword(s):  
Carrying Capacity ◽  
Coarse Aggregate ◽  
Concrete Strength ◽  
Steel Fibers ◽  
Environmental Benefits ◽  
Recycled Aggregates ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Axially Loaded

Nowadays, the use of recycled waste construction materials instead of aggregates is becoming popular in construction owing to its environmental benefits. This paper presents an experimental and analytical campaign to study the behavior of axially loaded columns constructed from recycled aggregates. The latter was used instead of natural aggregates, and they were collected from the waste of previous concrete constructions. Different concrete mixtures made from varying amounts of recycled aggregates ranged from 0 to 50% of the total coarse aggregate were conducted to achieve 28 MPa. The effect of steel fibers is another investigated variable with volumes ranged from 0 to 2% concerning concrete’s mixture. The experimental results showed that the concrete strength is dependent on the amount of recycled aggregates. When the recycled aggregates were less than 30% of the total aggregates, they had a negligible effect on concrete strength and the load carrying capacity of the column models were improved. Also, the presence of steel fibers enhanced the load carrying capacity of the columns constructed from concrete with recycled aggregates of more than 30%. Finite element analysis (using ANSYS 16.1 software program) was conducted to simulate the experimental investigations, and they achieved good agreements with the test results.

On the Use of GB50018 and AISI Specifications to Estimate the Load-Carrying Capacity of Cold-Formed Steel Lipped Channel Columns

2012 ◽  
Vol 166-169 ◽  
pp. 333-337
Author(s):  
De Fa Sun
Keyword(s):  
Carrying Capacity ◽  
Numerical Study ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Effective Width ◽  
Direct Strength Method ◽  
Load Carrying ◽  
Cold Formed Steel ◽  
Experimental Values

This paper addresses the applicability of the provisions of Chinese (GB50018-2002, effective width method) and the AISI Specifications (AISI-DSM, direct strength method) to estimate the load-carrying capacity of cold-formed steel lipped channel columns. It is worth noting that GB50018-2002 and AISI-DSM adopt different approaches to perform this task: while the former is based on the “Effective Width” concept, the latter may adopt the ‘‘Direct Strength Method’’. First, the relevant aspects related to the experimental investigations are briefly presented. Then, an extensive numerical study is performed by them, the estimates provided by them are compared with the experimental values. On the basis of these comparisons, some concluding remarks are drawn concerning the application of the GB50018-2002 and AISI-DSM design approaches.

Efficiency of worm gearboxes

2016 ◽  
Vol 230 (16) ◽  
pp. 2952-2956 ◽  
Author(s):  
Eva-Maria Mautner ◽  
Werner Sigmund ◽  
Johann-Paul Stemplinger ◽  
Karsten Stahl
Keyword(s):  
Experimental Test ◽  
Carrying Capacity ◽  
Worm Gear ◽  
Experimental Investigations ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Research Project ◽  
Worm Wheel ◽  
Load Carrying ◽  
Worm Gears

Within a research project, experimental investigations of large-sized worm gears (pairing steel worm with bronze worm wheel) with centre distance a = 315 mm are carried out. The primary aim is to gain verified knowledge regarding load-carrying capacity and efficiency for this worm gear size. The paper describes the conducted tests in detail and shows basic examples of experimental test results. In the course of these investigations, an overall worm gearbox efficiency of up to η = 96% is measured.

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