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ME1001
-
BASIC MECHANICAL
ENGINEERING

SYLLABUS

UNIT I


MACHINE ELEMENTS


I



(5
hours)



Springs
:

Helical and leaf springs


Springs in series and parallel.



Cams
:

Types of cams and followers


Cam profile.



UNIT II
-

MACHINE ELEMENTS


II



(5 hours)


Power
Transmission:

Gears (terminology, spur, helical and bevel gears,
gear trains). Belt drives (types). Chain drives. Simple Problems.



UNIT III
-

ENERGY





(10 hours)


Sources
:

Renewable and non
-
renewable (various types, characteristics,
advantages/disadvantages
).



Power Generation:

External and internal combustion engines


Hydro,
thermal and nuclear power plants (layouts, element/component description,
advantages, disadvantages, applications). Simple Problems.



SYLLABUS

UNIT IV
-

MANUFACTURING PROCESSES
-

I


(5
hours)


Sheet Metal Work:

Introduction


Equipments


Tools and
accessories


Various processes (applications, advantages /
disadvantages).



Welding:

Types


Equipments


Tools and accessories


Techniques employed
-
applications, advantages / disadvantages


Gas cutting


Brazing and soldering.



UNIT V
-

MANUFACTURING PROCESSES


II

(5 hours)


Lathe Practice:

Types
-

Description of main components


Cutting
tools


Work holding devices


Basic operations. Simple Problems.

Drilling Practice:

Introduction


Types


Description


Tools.
Simple Problems.



MACHINE ELEMENTS
-

I


CHAPTER
-
1

SPRINGS


A spring is an elastic body, which deflects under load
and recover to its original shape upon release of the
load.


It is also resilient member which stores energy once
deflected and releases the same as it recovers to its
original shape.



APPLICATIONS OF SPRINGS

1.
Applying forces and controlling motions, as found
in brakes and clutches.

2.
Measuring force, as in the case of spring balance. Ex
weighing machine (Analogue).

3.
Storing energy, as in the case of clock springs &
springs used in toys.

4.
Reduce the effect of shock loading, as in the case of
vehicle suspension ring.

5.
Changing the vibration characteristics of machine
mounted on foundation beds.

CLASSIFICATION OF SPRINGS

1.
Helical tension and compression spring:


The helical springs are made up of a wire coiled
in the form of a helix and are primarily intended
for compressive or tensile loads
.


The cross
-
section of the wire from which the
spring is made may be circular, square or
rectangular
.


Helical compression springs have applications to
resist applied compression forces

CLASSIFICATION OF SPRINGS


The major stresses produced in helical springs are
shear stresses due to twisting. The load applied is
parallel to or along the axis of the spring.


CLASSIFICATION OF SPRINGS

Helical compression spring

CLASSIFICATION OF SPRINGS

2.
Helical torsion springs:


The principal stress
induced are tensile and
compressive due to
bending.


These are similar to the
helical tension and
compression springs.


In these springs, the load is
subjected to torsion about
its axis.



CLASSIFICATION OF SPRINGS

Helical torsion springs

CLASSIFICATION OF SPRINGS

3.
Spiral Springs:


The principal stress
induced are tensile and
compressive due to
bending.


These are made of flat strip,
wound in the form of spiral.


This is subjected to torsion
about its axis.

CLASSIFICATION OF SPRINGS

Spiral Spring

CLASSIFICATION OF SPRINGS

4.

Leaf or laminated Springs :


The principal stresses are tensile and compressive de
to bending.


These are made of flat strips of varying lengths ,
clamped together.


These may be cantilever, semi
-
elliptic or full elliptic
in form.

CLASSIFICATION OF SPRINGS

Leaf Springs

CLASSIFICATION OF SPRINGS

5.
Belleville springs:


The principal stress are
tensile and compressive de to
bending.


These are made in the form
of coned discs which may be
stacked so as to give the
required spring load
-
deflection characteristics.

CLASSIFICATION OF SPRINGS

Belleville springs

MATERIALS OF SPRINGS


Commonly from alloy steels, High carbon
steel (0.7


1 % C) or carbon alloy steel.


The most common spring steels are music
wire, oil tempered wire, silicon, Chrome
vanadium.


Stainless steel, Spring brass, Phosphor bronze,
monel

& titanium are used for corrosion
resistance spring.

TERMINOLOGY IN SPRINGS

TERMINOLOGY IN SPRINGS


Solid Length

:When the compression spring is
compressed until the coils come in contact with each
other, then the spring is said to be solid. The solid
length of a spring is the product of total number of coils
and the diameter of the wire.

Solid length, L

s

= n x d

Where, n = number of coils


Free Length (L
o
)
: The free length of a compression
spring is the length of the spring in the free or
unloaded condition.

Free length, L
o

= Solid Length + Maximum Compression
deflection + Clearance between adjacent coils (1mm).



TERMINOLOGY IN SPRINGS


Spring Index (C):

The ratio of mean coil diameter to
wire diameter. A low index indicates a tightly wound
spring (a relatively large wire size wound around a
relatively small diameter mandrel giving a high rate).

C=d/D


Spring rate(K)
: The Spring rate is defined as the force
required to produce unit deflection of the spring. It can
also be said as stiffness or spring constant.

K =F/


Where F is the load applied,

is the deflection of the spring.


TERMINOLOGY IN SPRINGS


Pitch (P) :
The distance from
center

to
center

of the wire in adjacent active coils. The pitch
of the coil is defined as the axial distance
between adjacent coils in uncompressed
state.

P = Free length / (n
-
1)

SPRING COMBINATIONS


Parallel arrangement
: In parallel the spring are
arranged side by side. The deflection in spring
combination is equal to individual spring.

K
e


= K
1

+ K
2

+ ...... +
K
n


SPRING COMBINATIONS


Series Arrangement
: When the spring are
arranged in series, the total deflection of the
spring combination is equal to sum of the
deflection of individual springs.

1/
K
e


= 1/ K
1

+ 1/ K
2

+...

+ 1/
K
n

CAM


CAM is a device used to convert one simple
motion such as rotation to any other motion.


A CAM mechanism consist of two moving
elements, the cam and the follower which is
mounted on
the frame.