scholarly journals Effect of Helix Angle on the Gear Design Parameters in Helical Gears

2019 ◽  
Vol 8 (10) ◽  
pp. 887-890
Keyword(s):  
Helix Angle ◽  
Contact Stresses ◽  
Design Parameters ◽  
Screw Compressor ◽  
Bending Stress ◽  
Contact Ratio ◽  
Helical Gears ◽  
Gear Design ◽  
Overlap Ratio ◽  
Lower Noise

Screw compressor demands quite operation. For getting lower noise it is important to have higher contact ratio. Contact ratio can be increased by increasing the Helix angle i .e. indirectly increasing overlap ratio. The paper represents the effect of change in design parameters with respect to helix angle with the keeping same module and same centre distance. Higher helix angle leads lower bending and contact stresses. The study was conducted for screw electrical compressor. Gear was design for fixed parameters except helix angle. Also the contact stresses are analyzed (FEA) on ANSYS. The result from the calculation and FEA are compared for contact stress as well as bending stress.

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.

Comparative study of stress analysis of gears with different helix angle using the ISO 6336 standard and tooth contact analysis methods

2016 ◽  
Vol 230 (7-8) ◽  
pp. 1350-1358 ◽  
Author(s):  
Layue Zhao ◽  
Robert C Frazer ◽  
Brian Shaw
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Helix Angle ◽  
Contact Analysis ◽  
Bending Stress ◽  
Contact Ratio ◽  
Tooth Contact Analysis ◽  
Tooth Contact ◽  
Iso Standard ◽  
Analysis Methods

With increasing demand for high speed and high power density gear applications, the need to optimise gears for minimum stress, noise and vibration becomes increasingly important. ISO 6336 contact and bending stress analysis are used to determine the surface load capacity and tooth bending strength but dates back to 1956 and although it is constantly being updated, a review of its performance is sensible. Methods to optimise gear performance include the selection of helix angle and tooth depth to optimise overlap ratio and transverse contact ratio and thus the performance of ISO 6336 and tooth contact analysis methods requires confirmation. This paper reviews the contact and bending stress predicted with four involute gear geometries and proposes recommendations for stress calculations, including a modification to contact ratio factor Zɛ which is used to predict contact stress and revisions to form factor YF and helix angle factor Yβ which are cited to evaluate bending stress. The results suggest that there are some significant deviations in predicted bending and contact stress values between proposal methods and original ISO standard. However, before the ISO standard is changed, the paper recommends that allowable stress numbers published in ISO 6336-5 are reviewed because the mechanisms that initiate bending and contact fatigue have also changed and these require updating.

Investigating the effect of helix angle and pressure angle on bending stress in helical gear under dynamic state

2018 ◽  
Vol 15 (4) ◽  
pp. 478-488
Author(s):  
Prashant Jaysing Patil ◽  
Maharudra Patil ◽  
Krishnakumar Joshi
Keyword(s):  
Gear Tooth ◽  
Helix Angle ◽  
Helical Gear ◽  
Dynamic State ◽  
Load Carrying Capacity ◽  
Bending Stress ◽  
Content Type ◽  
Gear Design ◽  
Pressure Angle ◽  
Load Carrying

Purpose The aim of this paper is to study the effect of pressure angle and helix angle on bending stress at the root of helical gear tooth under dynamic state. Gear design is a highly complex process. The consistent demand to build low-cost, quieter and efficient machinery has resulted in a gradual change in gear design. Gear parameters such as pressure angle, helix angle, etc. affect the load-carrying capacity of gear teeth. Adequate load-carrying capacity of a gear is a prime requirement. The failure at the critical section because of bending stress is an unavoidable phenomenon. Besides this fact, the extent of these failures can be reduced by a proper gear design. The stresses produced under dynamic loading conditions in machine member differ considerably from those produced under static loading. Design/methodology/approach The present work is intended to study the effect of pressure angle and helix angle on the bending stress at the root of helical gear tooth under dynamic state. The photostress method has been used as experimental methods. Theoretical analysis was carried out by velocity factor method and Spott’s equation. LS DYNA has been used for finite element (FE) analysis. Findings The results show that experimental method gives a bending stress value that is closer to the true value, and bending stress varies with pressure angle and helix angle. The photostress technique gives clear knowledge of stress pattern at root of tooth. Originality/value The outcomes of this work help the designer use optimum weight-to-torque ratio of gear; this is ultimately going to reduce the total bulk of the gear box.

Computer-Aided Design of Compact Helical Gear Sets

1989 ◽  
Vol 111 (2) ◽  
pp. 285-289 ◽  
Author(s):  
C. S. Jog ◽  
S. S. Pande
Keyword(s):  
Computer Aided Design ◽  
Design Strategy ◽  
Helix Angle ◽  
Helical Gear ◽  
Optimization Techniques ◽  
Design Parameters ◽  
Gear Design ◽  
Computer Aided ◽  
Bending Stresses ◽  
Aided Design

This paper presents the design strategy for the Computer-Aided Design (CAD) of compact helical gear sets. Using optimization techniques, fundamental gear design parameters such as the number of teeth on the pinion, helix angle, and diametral pitch (or module) are selected subject to constraints on bending stresses, contact stresses, and involute interference limits for both standard and nonstandard gearing. The CAD procedure is illustrated with the help of a design example.

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.

Optimisation of Geometric Parameters of Gears under Variable Loading Condition

2012 ◽  
Vol 445 ◽  
pp. 1005-1010 ◽  
Author(s):  
Mehmet Bozca ◽  
Ferhat Dikmen
Keyword(s):  
Contact Stress ◽  
Loading Condition ◽  
Helix Angle ◽  
Geometric Parameters ◽  
Design Parameters ◽  
Bending Stress ◽  
Variable Loading ◽  
Face Width ◽  
Matlab Program ◽  
Tooth Modification

Optimisation of geometric parameters of gears under variable loading condition is studied. Bending stress is considered as objective function and contact stress is considered as constraint function. Bending stress and contact stress are calculated depending on zero tooth modification, positive tooth modification and negative tooth modification by using developed MATLAB program respectively. Obtained results are compared and presented graphically. It is concluded that tooth modification is effective parameter for optimisation of geometric parameters of gears under variable loading condition. By optimising the geometric parameters of the gears, such as, the module, number of teeth, helix angle, and face width, it is possible to obtain a light-weight-gears structures. All optimised geometric design parameters also satisfy all constraints.

Parametric vibration of split gears induced by time-varying mesh stiffness

2014 ◽  
Vol 229 (1) ◽  
pp. 18-25 ◽  
Author(s):  
Dongsheng Zhang ◽  
Shiyu Wang
Keyword(s):  
Parametric Vibration ◽  
Design Parameters ◽  
Time Varying ◽  
Contact Ratio ◽  
Mesh Stiffness ◽  
Rotational Model ◽  
Helical Gears ◽  
Multi Scale ◽  
Rotational Vibration ◽  
The Relationship

Time-varying mesh stiffness is a significant excitation source within gear systems. Split gear (or laminated gear, phase gear) is an interesting design using equally phased gear-slices, which can remarkably reduce the mesh stiffness fluctuation like helical gears but completely avoid the axial force. This work examines a split gear pair to address the suppression of the mesh stiffness fluctuation and rotational vibration thereof, especially the relationship between the key design parameters including the number of slice, contact ratio, and damping, and the parametric vibration. For these aims, this work develops a purely rotational model, based on which the multi-scale method is employed to determine stability boundaries. The results imply that the unstable zones are related to the mesh phase determined by the number of slices and contact ratio, and these zones can be diminished by the damping. The analytical predictions are numerically verified by Floquet theory.

Parameter Optimization Design and Stress Analysis of ANSYS in Inclined Gear Transmission System of Wind-Turbine

2013 ◽  
Vol 694-697 ◽  
pp. 109-114
Author(s):  
Zhi Bang Yang ◽  
Yue Feng Zhu ◽  
De Lin Chen
Keyword(s):  
Wind Turbine ◽  
Optimization Design ◽  
Maximum Stress ◽  
Design Parameters ◽  
Bending Stress ◽  
Operating Life ◽  
Gear Design ◽  
Gear Transmission System ◽  
Gear Box ◽  
Parameter Optimization Design

ncreasing speed Gear-box is one of the most important components of wind-turbine. Gear design directly affect the operating life and reliability of gear-box. Based on the 1.5MW wind-turbine as the research object in this paper, we optimized the design parameters of Inclined gears, analysed its bending stress reliability, further verified the gear maximum stress and stress position, to provide a scientific reference for making Inclined gears later.

Contact Stress Analysis of a Helical Gear

2015 ◽  
Vol 766-767 ◽  
pp. 1070-1075 ◽  
Author(s):  
R. Devaraj
Keyword(s):  
Stress Analysis ◽  
Contact Stress ◽  
Gear Tooth ◽  
Element Model ◽  
Helix Angle ◽  
Helical Gear ◽  
Bending Stress ◽  
Helical Gears ◽  
Modeling Software ◽  
Main Factors

The main factors that cause the failure of gears are the bending stress and contact stress of the gear tooth. Out of these, failure of gears due to contact stress is high compared to bending stress. Stress analysis has been a key area of research to minimize failure and optimize design. This paper gives a finite element model for introspection of the stresses in the tooth during the meshing of gears. Specifically, helix angle is important for helical gears. Using modeling software, 3-D models for different helix angles in helical gears were generated, and the simulation was performed using ANSYS 12.0 to estimate the contact stress. The Hertz equation and AGMA standard was used to calculate the contact stress. The results of the theoretical contact stress values, using Hertz and AGMA are compared with the stress values from the FEA for different helix angles and the results are tabulated and discussed.

scholarly journals Revised Lewis Bending Stress Capacity Model

2020 ◽  
Vol 14 (1) ◽  
pp. 1-14
Author(s):  
Edward. E. Osakue ◽  
Lucky Anetor
Keyword(s):  
Stress Concentration ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Gear Tooth ◽  
Shear Stresses ◽  
Bending Stress ◽  
Moment Arm ◽  
Contact Ratio ◽  
Helical Gears ◽  
Cylindrical Gears

Background: During operation, cylindrical gearset experiences tangential, radial, and axial (helical gears only) force components that induce bending, compressive, and shear stresses at the root area of the gear tooth. Accurate estimation of the effective bending stress at the gear root is a challenge. Lewis was the first person who attempted estimating the root bending stress of spur gears with some reasonable accuracy. Various gear standards and codes in use today are modifications and improvements of the Lewis model. Objective: This research aims at revising the Lewis model by making adjustments for dynamic loads, shear stresses, axial bending stress for helical gears, and stress concentration factor that is independent on the moment arm of tangential or axial force component. Methods: An analytical approach is used in formulating a modified formula for the root bending stress in cylindrical gears starting with the original Lewis model. Intermediate expressions are developed in the process and works from many previous authors are reviewed and summarized. The new model developed is used to estimate the root bending stress in four example gearsets of 0o to 41.41o helix angle and the results are compared with those of AGMA (American Gear Manufacturers Association) formula. Results: Analysis from the examples shows that neglecting the radial compressive stress over-estimated the root bending stress by 5.27% on average. When shear stresses are ignored, the root bending stress is under-estimated by 7.49% on average. It is important, therefore, to account for both compressive and shear stresses in cylindrical gear root bending stress. When the root bending stress estimates from the revised Lewis model were compared with AGMA results, deviations in the range of -4.86% to 26.61% were observed. The stress estimates from the revised Lewis formulae were mostly higher than those of AGMA. Conclusion: The new root bending stress model uses stress concentration factors (normal and shear) that are independent of the point of load application on the gear tooth. This decoupling of stress concentration factor from the load moment arm distinguishes the new model from AGMA formula and brings bending stress analysis in gear design in line with classical bending stress analysis of straight and curved beams. The model can be used for both normal contact ratio and high contact ratio cylindrical gears.

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