Influence of Profile Modification and Lubricant Viscosity on Scoring of Helical Gears

1974 ◽  
Vol 96 (1) ◽  
pp. 71-77
Author(s):  
T. Matsunaga
Keyword(s):  
Testing Machine ◽  
Normal Pressure ◽  
Helix Angle ◽  
Power Circuit ◽  
Helical Gears ◽  
Profile Modification ◽  
Face Width ◽  
Carburized Steel ◽  
Load Carrying ◽  
Lubricant Viscosity

Scoring limit of helical gears made of carburized steel is investigated experimentally. Gear testing machine used for the tests is a closed power circuit type and designed for operation up to 23,000 rpm. All tests are made with pairs of 14 and 141-tooth gears of 3-module, 20-deg normal pressure angle, 29.066-deg helix angle, and 30-mm face width. The effect of profile modification on the scoring limit is investigated, and the effects of lubricant viscosity and location of oil supply nozzle are investigated in connection with the effect of profile modification. Three kinds of lubricants of various viscosity ordinarily used in a gear system are tested (lubricant viscosity: 32, 53, 70 cSt at 40 C). Load carrying capacity of the lubricant of the highest viscosity is higher by 25 percent than that of the lowest one. But the effect of modification is much larger than that of lubricant viscosity.

On the influence of helix angle and face width on gear windage losses

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1101-1112 ◽  
Author(s):  
Nicolas Voeltzel ◽  
Yann Marchesse ◽  
Christophe Changenet ◽  
Fabrice Ville ◽  
Philippe Velex
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Helix Angle ◽  
Spur Gears ◽  
Power Losses ◽  
Flow Rates ◽  
Helical Gears ◽  
Face Width ◽  
Loss Prediction ◽  
Simulated Flow

This paper investigates the windage power losses generated by helical gears rotating in pure air based on experimental results and a computational fluid dynamic code. It is found that the simulated flow patterns are totally different from those calculated for spur gears and that both tooth face width and helix angle are influential. The windage losses derived from Dawson’s and Townsend’s formulae are critically assessed using computational fluid dynamic results thus highlighting the limits of a unique formulation for accurate windage loss prediction. Finally, an analytical approach is suggested which gives good results providing that the flow rates at the boundaries of the inter-tooth domains can be estimated.

Conformity Factor In Wildhaber-Novikov Circular-Arc Gears

1981 ◽  
Vol 103 (1) ◽  
pp. 134-140 ◽  
Author(s):  
K. Lingaiah ◽  
K. Ramachandra
Keyword(s):  
Carrying Capacity ◽  
Maximum Load ◽  
Helix Angle ◽  
Load Carrying Capacity ◽  
Circular Arc ◽  
Face Width ◽  
Rational Index ◽  
Load Carrying ◽  
The Difference ◽  
Conformity Factor

Conformity factor, which is more rationally defined as the ratio of the area of contact to the active area of the flank of the mating teeth, is theoretically evaluated for Wildhaber-Novikov circular-arc gears, using Hertz’s theory of contact stress, without neglecting the effect of the difference in the profile radii of the pinion and wheel teeth, which is an important factor in fully-hardened gears. The variation of the conformity factor with the helix angle, pressure angle, ratio of the profile radii, module and the number of teeth follows closely the variation of load-carrying capacity per unit face-width of these gears and hence, from this study it is concluded that conformity factor is a more rational index on which the selection of the profile and material parameters should be based. This study of the conformity factor, for the particular profile geometry, indicates 7.5 to 15.0 deg as the suitable helix-angle range for achieving maximum load-carrying capacity per unit face-width.

Effects of Carburized Part, Helix Angle and Face Width on Residual Stresses of Case-Hardened Helical Gears

2004 ◽  
Vol 2004.4 (0) ◽  
pp. 63-66
Author(s):  
Kouitsu MIYACHIKA ◽  
Wei-Dong XUE ◽  
Takao KOIDE ◽  
Satoshi ODA ◽  
Hiroshige FUJIO
Keyword(s):  
Residual Stresses ◽  
Helix Angle ◽  
Helical Gears ◽  
Face Width

Analysis of time-varying friction excitations in helical gears with refined general formulation

2015 ◽  
Vol 229 (13) ◽  
pp. 2467-2483 ◽  
Author(s):  
Hanjun Jiang
Keyword(s):  
Friction Force ◽  
Contact Line ◽  
Sliding Friction ◽  
Helix Angle ◽  
Universal Method ◽  
Time Varying ◽  
Contact Ratio ◽  
Friction Forces ◽  
Helical Gears ◽  
Face Width

Time-varying sliding friction force and friction torque are regarded as non-negligible excitation sources of vibration and noise in gears. The sliding friction force primarily excites the motion along the off-line-of-action direction, which transmits vibration to the housing through shafts and bearings and then radiates noise. Since the contact line intersects with the pitch line, and the directions of the friction forces are opposite on both sides of the pitch line, the calculation of the friction excitations in helical gears becomes more difficult, especially in the high contact ratio helical gears. However, there is no universal method for calculating the friction excitations in helical gears with different range of contact ratio. The changes of friction excitations in helical gears are highly dependent on the geometric parameters such as helix angle and face width among others. Yet, there exist very limited studies on these topics. In this study, a refined general formulation for the calculation of time-varying contact line and friction excitations is proposed by assuming uniform load distribution along the contact lines with time-varying normal force and friction coefficient. Key gear parameters such as modification coefficient, helix angle, and face width are analyzed to illustrate their effects on the time-varying contact line and friction excitations. The results demonstrate that the refined general formulation is effective for the calculation of the friction excitations in helical gears with different range of contact ratio, and the parametric analysis could supply some guidance for choosing gear parameters in the design of helical gears to reduce the friction excitations.

Improving the Characteristics of Gear Pumps: Part A — Discharge

2003 ◽  
Author(s):  
Ahmed M. M. El-Bahloul ◽  
Yasser Z. R. Ali
Keyword(s):  
Correction Factor ◽  
Helix Angle ◽  
Tooth Profile ◽  
Radius Of Curvature ◽  
Circular Arc ◽  
Pressure Angle ◽  
Face Width ◽  
Angle Change ◽  
Number Of Teeth ◽  
Gear Pumps

The main objective of this paper is to study the effect of gear geometry on the discharge of gear pumps. We have used gears of circular-arc tooth profile as gear pumps and have compared between these types of gearing and spur, helical gear pumps according to discharge. The chosen module change from 2 to 16 mm, number of teeth change from 8 to 20 teeth, pressure angle change from 10 to 30 deg, face width change from 20 to 120 mm, correction factor change from −1 to 1, helix angle change from 5 to 30 deg, and radii of curvature equal 1.4, 1.5, 2, 2.5, 2.75, and 3m are considered. The authors deduced that the tooth rack profile with radius of curvature equal 2.5, 2.75, 3m for all addendum circular arc tooth and convex-concave tooth profile, and derived equations representing the tooth profile, and calculated the points of intersections between curves of tooth profile. We drive the formulas for the volume of oil between adjacent teeth. Computer program has been prepared to calculate the discharge from the derived formulae with all variables for different types of gear pumps. Curves showing the change of discharge with module, number of teeth, pressure angle, face width, correction factor, helix angle, and radius of curvature are presented. The results show that: 1) The discharge increases with increasing module, number of teeth, positive correction factor, face width and radius of curvature of the tooth. 2) The discharge increases with increasing pressure angle to a certain value and then decreases with increasing pressure angle. 3) The discharge decreases with increasing helix angle. 4) The convex-concave circular-arc gears gives discharge higher than that of alla ddendum circular arc, spur, and helical gear pumps respectively. 5) A curve fitting of the results are done and the following formulae derived for the discharge of involute and circular arc gear pumps respectively: Q=A1bm2z0.895e0.065xe0.0033αe−0.0079βQ=A2bm2z0.91ρ10.669e−0.0047β

scholarly journals Enhanced application limits for crossed helical gearboxes using new geometries for smaller sliding paths or smaller contact pressures

2019 ◽  
Vol 287 ◽  
pp. 01010
Author(s):  
Christoph Boehme ◽  
Dietmar Vill ◽  
Peter Tenberge
Keyword(s):  
Calculation Method ◽  
Helix Angle ◽  
Helical Gear ◽  
Design Parameters ◽  
Helical Gears ◽  
Positive Effects ◽  
Tooth Stiffness ◽  
Lubrication Condition ◽  
Overlap Ratio ◽  
Helical Gear Pair

Crossed-axis helical gear units are used as actuators and auxiliary drives in large quantities in automotive applications such as window regulators, windscreen wipers and seat adjusters. Commonly gear geometry of crossed helical gears is described with one pitch point. This article deals with an extended calculation method for worm gear units. The extended calculation method increases the range of solutions available for helical gears. In general, for a valid crossed helical gear pair, the rolling cylinders do not have to touch each other. In mass production of many similar gears, individual gears can be reused because they can be paired with other centre distances and ratios. This also allows the use of spur gears in combination with a worm, making manufacturing easier and more efficient. By selecting design parameters, for example the axis crossing angle or the helix angle of a gear, positive effects can be achieved on the tooth contact pressure, the overlap ratio, the sliding paths, the lubrication condition, the tooth stiffness and, to a limited extent, on the efficiency of the gearing. It can be shown that for involute helical gears, in addition to the known insensitivity of the transmission behaviour to centre distance deviations, there is also insensitivity to deviations of the axis crossing angle. This means that installation tolerances for crossed helical gearboxes can be determined more cost-effectively.

scholarly journals Tensile Resistance of GFRP Wrapped Steel-Dowelled Half-Lap Timber Connection

2018 ◽  
Vol 7 (3.11) ◽  
pp. 101
Author(s):  
Amirah Ali Chew ◽  
Nurul Atikah Seri ◽  
Wan Nur Syazni Wan Shaari ◽  
Mohd Hanafie Yasin ◽  
Rohana Hassan
Keyword(s):  
Testing Machine ◽  
Yield Model ◽  
Strength Group ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Load Carrying ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
Group 5 ◽  
Timber Connections

Generally, the use of timber mainly focuses on simple structures or structures that can take small loads. This paper report on tensile resistance of steel dowelled timber connection wrapped with glass fibre reinforced polymer (GFRP). It involved experimental work in laboratory designed to determine the tensile strength behaviour for half-lap timber connections with steel dowel as the mechanical    fasteners. Bintangor species representing strength group 5 and Yellow Meranti species representing strength group 6 were tested in the conditions of with and without the GFRP wrapping. The performances of the connections were observed using the European Yield Model (EYM) as the guideline. The EYM theory is generally used to determine the load carrying capacity of timber-to-timber, panel-to-timber and steel-to-timber connections, reflecting all possible modes of failures. All half-lap connection members were tested at the rate     0.0006 mm/min using the universal testing machine. As a result, it was found that the steel-dowelled half-lap timber connection with GFRP wrapping performed better than the timber connection without the wrapping. The ultimate load of GFRP wrapped connections made of Bintangor and Yellow Meranti species were found increased at 17% and 44% higher compared to the connection without the GFRP wrapping accordingly.  

Tooth wear prediction of crowned helical gears in point contact

2019 ◽  
Vol 234 (6) ◽  
pp. 947-963
Author(s):  
Hongbing Wang ◽  
Changjiang Zhou ◽  
Bo Hu ◽  
Zhongming Liu
Keyword(s):  
Wear Resistance ◽  
Point Contact ◽  
Normal Pressure ◽  
Tooth Wear ◽  
Parameters Optimization ◽  
Operating Parameters ◽  
Wear Depth ◽  
Wear Prediction ◽  
Helical Gears ◽  
Tooth Width

A tooth wear prediction methodology for helical gears in point contact is developed to evaluate their wear resistances using a lead crown. The load distribution coefficient is proposed in accordance with the elastic approach of each contact tooth pair being equal, and contact pressure are determined, and the sliding distance is obtained by adopting a generalized moving distance model. Then, the wear depth is computed in accordance with Archard’s wear equation, and the differences in tooth wear on standard and crowned helical gears are analyzed comparatively. The effects of crowned amount, fundamental geometry, and operating parameters on the wear resistance of the crowned helical gear pair are investigated. The results reveal that the tooth wear is lower on the gear surface with a moderate crowned amount than on the standard one, and that wear depths decrease with the increase in the helix angle, normal pressure angle, normal module, tooth number, or tooth width but increase with input torque rises. Furthermore, the rational lead crown, the geometric, and operating parameters optimization can be applied to wear resistance in the gear design.

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