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Modelling and Analysis of Herringbone Gears by using ANSYS: A
Case Study
Ruma Roy1, Kalyan Chatterjee
2, Sayanti Banerjee
3, Pranjal Holme Roy4, Ankit Tiriya
5
1,2,3Assistant Professor,
4Student,
5Student
Department of Mechanical & Automation Engineering
Amity University, Kolkata-700135, West Bengal
ABSTRACT
This paper present the case study on Analysis and
modification of herringbone gear design and explain
the design the herringbone gear and dimension
specification. To design the herringbone gear to study
the weight reduction and stress distribution for
Carbon FPR (Carbon Fibre Reinforced Polymer),
Glass(Fibre) Reinforced Plastic and Alloy Steel..
Gearing is one of the most critical components in
mechanical power transmission system, and in most
industrial rotating machinery. Its have a involving
modern design, specific character, specific materials,
with consideration of analysis of force and its
mechanical properties. These approach for modern
spur design developing the tooth profiles with
modified the shape and improving dimension.
herringbone gear is helical shaped gear in which the
teeth makes helix angle to the axis. It is easy to
manufacture and it is mostly used in transmitting
power from one shaft to another shaft up to certain
distance & also used to vary the speed & Torque. the
main purpose of modern spur gear design it increases
the power transmitting capacity and also improves the
efficiency of power transmission.
Keywords:HERRINGBONE GEARS, Carbon FPR
(Carbon Fibre Reinforced Polymer), Glass(Fibre)
Reinforced Plastic and Alloy Steel,ANSYS
1. INTRODUCTION
A gear is a rotating machine part having cut teeth, or
cogs, which mesh with another toothed part in order to
transmit torque. Two or more gears working in tandem
are called a transmission and can produce a mechanical
advantage through a gear ratio and thus may be
considered as a simple machine. Geared devices can
change the speed, magnitude, and direction of a power
source. The most common situation is for a gear to mesh
with another gear, however a gear can also mesh a non-
rotating toothed being operated under different loads part,
called a rack, there by producing translation instead of
rotation. The advantage of gears is that the teeth of a gear
prevent slipping. When two gears of unequal number of
teeth are combined a mechanical advantage is produced,
with both the rotational speeds and the torques of the two
gears differing in a simple relationship. In transmissions
which offer multiple gear ratios, such as bicycles and
cars, the term gear, as in first gear, refers to a gear ratio
rather than an actual physical gear.
Fig.1. Herringbone Gear [14]
A herringbone gear, a specific type of double helical
gear, is a special type of gear that is a side to side (not
face to face) combination of two helical gears of opposite
hands. From the top, each helical groove of this gear
looks like the letter V, and many together form a
herringbone pattern (resembling the bones of a fish such
as a herring). Unlike helical gears, herringbone gears do
not produce an additional axial load.
Like helical gears, they have the advantage of
transferring power smoothly, because more than two teeth
will be in mesh at any moment in time. Their advantage
over the helical gears is that the side-thrust of one half is
balanced by that of the other half. This means that
herringbone gears can be used in torque gearboxes
without requiring a substantial thrust bearing. Because of
this, herringbone gears were an important step in the
introduction of the steam turbine to marine propulsion.
It is commonly known that the total deformation of
each contact point at the same meshing position along the
load direction must be the same to ensure the continuity
of the meshing process. An automatic program to
determine the meshing positions and the coordinates of
each contact point is developed firstly. The flexibility
factors for gear flank are computed by using FEM. The
whole process is implemented by using FEM commands
of ANSYS which are managed by the APDL program
language and macros technique.
In the end, techniques developed in this paper are
used to analyze the meshing stiffness and stresses of
herringbone gears used in encased planetary gear trains
(PGTS). The 3D models of every parts of PGTS are
established and used to assemble the virtual prototype
which simulates the movement of the PGTS. The meshing
Journal of Xi'an University of Architecture & Technology
Volume XIII, Issue 6, 2021
ISSN No : 1006-7930
Page No: 483
stiffness of sun gear wheel with planet gear pairs and
planet gear pairs with ring gear pairs, and the stresses of
sun gears, planet gears and ring gears are calculated to
highlight the capabilities of the developed techniques
2. BASIC TERMS OF HERRINGBONE GEAR
Fig. 2. Helical gear
(nomenclature).
1. Helix angle: It is a constant angle made by the helices
with the axis of rotation.
2. Axial pitch: It is the distance, parallel to the axis,
between similar faces of adjacent teeth. It is the same
as circular pitch and is therefore denoted by pc. The
axial pitch may also be defined as the circular pitch
in the plane of rotation or the diametral plane.
3. Normal pitch:It is the distance between similar faces
of adjacent teeth along a helix on the pitch cylinders
normal to the teeth. It is denoted by pN. The normal
pitch may also be defined as the circular pitch in the
normal plane which is a plane perpendicular to the
teeth. Mathematically, normal pitch, pN = pc cos α
3. DESIGNING OF GEAR
Considering the module =5,
number of teeth = 18 and 20° full depth
Power transmitted = 15 KW
Torque, T = (P x 60) / 2πN
For 10000 rpm ,
T = (15 x 1000 x 60) / (2 x π x 10000)= 143.3 N-m
For m=5
Precision gear error = 0.015
Pitch line velocity v = 20 m/sec
Velocity factor Cv = 0.75 / (0.75 +√v )
= 0.75 / (0.75 +√20 ) = 0.14361
Number of tooth on gear Tg = 3 x Tp = 3x18=54
Diameter of gear Dg = m x Tg = 5 x 54 = 270
mmCircular pitch = (3.14 x D) / T = (3.14 x 270) / 54 =
15.7 mm
Face width b = 4 π m = 4x3.14x5 = 62.8 mm
Tangential force calculation:
Tangential force Wt = 2000 T / Dg
= 2000 x 143.3 / 270
= 1061.41 N
Table 1. Dimensions of machine components
Description Values Unit
No. Of teeth 54
Module 5 mm
Pitch
diameter
270 mm
Pressure
angle
20 degree
Helix Angle 15 degree
Face width 62.8 mm
Addendum 5 mm
Deddendum 6.25 mm
Power 15 kW
Speed 1000 RPM
4. ANALYSIS OF GEAR
Fig 3. Dimension wise Gear
Journal of Xi'an University of Architecture & Technology
Volume XIII, Issue 6, 2021
ISSN No : 1006-7930
Page No: 484
Fig.4. Messing of Gear
Fig.5 Equivalent elastic strain of Gear
Fig.6 Total Deformation of Gear
of Gear
Fig.7. Equivalent Stress of Gear
Fig.8. Total deformation 2nd
stage
Fig.9. Total damage of Gear
of Gear
stage of Gear
of Gear
Journal of Xi'an University of Architecture & Technology
Volume XIII, Issue 6, 2021
ISSN No : 1006-7930
Page No: 485
5. RESULT
Allo
ySte
el
GRP Carbon
FPR
Unit
Deformati
on
0.006 0.034 0.005 mm
Stress 23.34 23.60 23.63
MPa
Strain 0.0001 0.0007 0.0001
Dynamic
Deformati
on
15.28 31.49 32.00
microns
Damage 231 402 403 hrs
6.CONCLUSIONS AND RECOMMENDATION
1. The failure of herringbone gear was caused by
excessive deformation caused by stress on the surface of
gear teeth. The calculated stress is higher than the
allowable stress of gear material.
2. It is found that Allowable stress for the gear material (
Alloy Steel) is less than the calculated bending stress.
Therefore the material having higher value of allowable
stress is to be used for manufacturing of herringbone gear.
3. From the results, it is observed that the allowable
stresses of Alloy Steel are less than that of the other
material.
4. Hence Alloy Steel is best suited for herringbone gears
used in Rolling mill gearbox.
5. The Fracture starts from pitting area at the surface of
gear tooth. The pitting occurred as a result of excessive
stress.
REFERENCES
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Journal of Materials Science and Engineering B 2 (4)
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Journal of Xi'an University of Architecture & Technology
Volume XIII, Issue 6, 2021
ISSN No : 1006-7930
Page No: 486