Babol Noshirvani University of Technology

Mechanical Engineering Design 2 Final Project

Project Title: Helical Gear Design

Under supervision of Assistant Prof.: A . Fathi

Team members:

SeyedAli Mir Mohammad Sadeghi

Reza Safaei

Milad Hosseini

ABSTRACT

Nowadays gears play an important role in the field of engineering since the crucial matter of power

transmission is required. According to their application, gears come in different types and shapes.

Notwithstanding their small size, these ubiquitous components are of such an importance that there might

not exist any industrial company working without them. The diverse variety of them enables engineers to

choose the optimum and the most efficient one due to the associated application. Here in this project the

authors will introduce one specific type of gears briefly and then will continue to design one used in a bevel-

speed reducer. It is to be noted that the calculations are done in MatLab and the designed gear is then drawn

in Solidworks. In addition, the static analysis of the pinion is done in Ansys, whose procedure is shown as

step-by-step photos at last.

Introduction

As mentioned before, for each application there is an optimum choice to use a gear. Therefore, for any case,

every choice of gears have its own pros and cons. Take the example of helical gears. Some advantages of

them are as follow: “1) Since the teeth gradually meet each other, the resulting shocks and vibrations are

less than that of a spur gear,” says Dr. Fathi. “2) During their operation a greater number of teeth are

involved, in comparison to a spur gear, which leads to an increase in power transmission capability and

hence a decrease in the gear size.” He added.

In addition to the specifications required to specify a spur gear, e.g. Pressure Angle, Module, Number of

teeth, etc.; helical gears need more specifications to be specified such as Helix angle, and Normal pressure

angle. In this project we are to design the smallest possible helical pinion of a bevel-speed reducer shown

in Fig. 1 under the input conditions of Power = 30 [hp], n = 1000[rpm] but this given round must be

transmitted to the pinion as we have two bevel gears engaged. Therefore, it becomes n = 620[rpm]

Figure. 1: Industrial 2D drawing of a bevel-speed reducer.

The whole design procedure is introduced briefly down here:

First a preliminary module, though being the reference module, (Normal module) is selected, to which the

two final modules of bending and pitting must approach. Then using the input data in addition to some

assumptions and selections, we embark on finding the design factors required for the process of engineering

a helical gear.

As shown in Fig. 1 the green, yellow, and red rectangulars show the input shaft, the pinion, and the gear,

respectively.

The design procedure is done under some assumptions and some selections as:

Input data 30 [hp] 0.735=22.05[Kw]Power

620 [rpm]

Assumptions 30

2

2 cos( )1 12

sin ( )p

t

kN

36GN

Selections and Calculations

𝐻𝐵 = 450

𝐹. 𝑠 = 1

Thorough-hardened Qrade1

Uncrowned

20 n

91.2 10 [cycles]L

1 tan( )tan 22.7959

cos( )

nt

, 3n predictedm

, .cos( ) 2.5981n n predictedP m

3cos( )

nt

PP

0.9549tt

Pm

310 339.616 [N.m]2

60

PowerT

4p

p

t

Nd

P

3

,

2/3

0.33

1

1

1

1

2(m )( ) 3.671516 10

2 60

0.25(12 Q ) 0.8255

50 56(1 ) 59.773

(A 200 ) 278.81

g

G

p

B

O

f

S

p

n predictrd

v

B

v

J

Nm

N

K

K

C

K

NV

B

A B

K V

0.533 88.3 328.15 [Mpa]

2.22 200 1199 [Mpa]

t

e

S HB

S HB

1 (C ) (C ) (C ) (C ) C 1.206m m c p f p m m a eK

( 0.056)

( 0.0178)

1

2.466 0.7648

1.3558 0.9345

1

H

N

N

T

C

Z L

Y L

K

,

2 2 2 2

0.8 2.4

63.2

200

cos( ) 58.2635

cos( ) 184.3782

(r a) (r a) ( )sin( ) 11.6575

cos( ) 2.4414

0.22040.95

cos( )sin( )0.8499

2 1

n predicted

p

g

pb p t

gb g t

p pb g gb p g t

N n n

NN

t t G

N G

a m

r

r

r r

r r

Z r r r r

P P

Pm

Z

mI

m m

1

1

1

1

1

1

1

191

866

1

1

1.2

F

H

B

z

j

T

H

E

c

w

I

R

S

K

Y

Y

Y

Y K

S

Z

S

Z

Z

Z

3 (1/3)

2 2 (1/3)

((2 10 ) / (10 ))

((2 ) / ( )

13.2281

2.6377( / ( )) )

bending

p

F v o s H B

ittin

B Z p t j N

v o s H R p E H Z c N wg

T S K K K K K Y Y N S Y Y

T K K K K Z N I Z S Y Y S Z

m

Zm

Figure. 2: The final modeled helical pinion in Solidworks.

Figure. 3: The final modeled pinion cross sectional profile drawn in Matlab.

Fig. 2 depicts the final designed helical pinion.

Ansys static analysis

Figure. 4: Stages of simulation.

Figure. 5: Meshing procedure.

Figure. 6: Force implementation followed by defining the pressure angle.

Figure. 7: supporting constraint application

Figure. 8: stress analysis.

.

Figures 4 to 8 depict step-by-step analysis procedure in Ansys.

Results and discussion

In this project the team members were to design a helical pinion at the input of a bevel-speed reducer in

accordance to some input data in addition to some arbitrary assumptions and selections.

The analysis outcome clearly show that to achieve such preliminary Normal module of 3 the pinion must

have an outstanding HB of 4000. Consequently, the question which remains unknown is that “Is there any

material exists with such extreme HB of 4000”. Scientific studies have shown the authors that there are

material, such as Rhenium diboride, with HBs even more than 4000. [1]

The component of interest was drawn in Solidworks as well as analyzed in Ansys for static load

visualization.

Reference : [1] : https://en.wikipedia.org/wiki/Rhenium_diboride

If there is any questions, don’t hesitate to contact me

Email: ali_619_eg@yahoo.com