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.

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Journal of Xi'an University of Architecture & Technology

Volume XIII, Issue 6, 2021

ISSN No : 1006-7930

Page No: 486