Transcript Slide 1

MACHINE TOOLS
Dept. of Mech & Mfg. Engg.
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A Machine tool
A machine tool may be defined as a power
driven machine which accomplishes the
cutting or machining operations in it.
Examples:
Lathe,
Drilling machine,
Milling machine,
Grinding machine.
Shaping machine
Dept. of Mech & Mfg. Engg.
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Functions of Machine Tools

To hold and support job/work to be
machined
 To hold and support the cutting tool in
position
 To move the cutting tool, work or both in a
desired direction
 To regulate cutting speed and provide
feeding movement.
Working principle of lathe
Chuck
Direction of rotation
of work piece
Work piece
Cutting tool
Direction of cutting tool
Dept. of Mech & Mfg. Engg.
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Working principle of a lathe
• Cutting tool can remove material
Chuck
Direction of
rotation of
work piece
in the form of chips from rotating
work pieces to produce circular
objects
• Work piece is held rigidly by one
of the work holding devices
known as chuck
Direction of
cutting tool
Cutting
tool
• Uses V – shaped cutting tool
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Lathe Basics
Spindle
Nose
Tailstock
Spindle
Clamp
Tool Post
Compound
Rest
HEADSTOCK
TAILSTOCK
Saddle
Feed
Reverse
Lever
Feed
Change
Lever
Lead
Screw
BED
WAYS
APRON
Gear
Box
Carriage
Hand
Wheel
Motor
Drive
Frictionclutch
Control
Cross
Slide
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Bed
Half Nut
Lever
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Explain with neat diagram the principal parts of
an engine lathe.
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LATHE
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MAJOR PARTS
1] Bed
2] Head stock
3] Tail stock
4] Main drive
5] Carriage assembly consisting of
a) Saddle
b) Cross-slide
c) Compound rest
d) Tool post
e) Apron
6] Lead screw
7] Feed rod
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BED
Foundation part of the machine
Supports all other parts
The top of the bed is formed by
two Precession guide ways
i) Outer guide way--- Carriage assembly mounted
and align it with centre line of lathe
ii) Inner guide way--- Head stock and Tailstock
are mounted
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Headstock:
• Housing comprising of
– feed gear box
– stepped cone pulley
• Rigidly mounted on the
inner guide ways of
lathe bed at its left end.
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MAIN DRIVE
Cone pulley
• Cone pulley which drives
the main spindle is
driven by the motor.
• Various spindle speeds
can be obtained by
shifting the belt on
different steps of the
cone pulley.
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Tailstock:
• Movable part of the
lathe that carries the
dead centre in it.
• Used to clamp tools
like: Twist drills
Reamers
For making holes.
• Mounted loosely on
the inner guide ways
of a lathe bed
• Moved and locked in
any position.
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Carriage assembly:
•
To support the tool
•
Moves over the outer
guide ways longitudinally
between headstock
and tailstock.
It is composed of 5 main parts:
1. Saddle
2. Cross slide
3. Compound Rest
4. Apron
5. Tool post
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Lathe Carriage and Apron
Tool Post
Compound
Rest
Cross
Feed
Knob
Cross
Slide
Carriage
Lock
Screw
Apron
Hand
Wheel
Half Nut
Lever
Compound
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Mfg. Engg.
Rest& Knob
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Saddle
• H shaped casting that
slides over set of guide
ways
• Serves as the base for the
cross slide.
Cross slide
• Mounted on the saddle
• Enables the movement
of the cutting tool laterally
across the lathe bed by
means of cross feed hand
wheel.
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Cross Feed Knob
Used to move cutting tool across the
end of the stock - Facing (Cross Feed)
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Compound Rest
•Mounted on the top of the
cross slide
•Supports the tool post.
•Swiveled to any angle in
the horizontal plane
•To facilitate following
operations:
•Taper turning
•Threading operations
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Apron Hand Wheel
Used to move tool along the work - for
Turning (Longitudinal Feed)
Apron
Hand
Wheel
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Apron
•Mounted on the front of the
saddle
• Consists of,
- Carriage
- Cross slide mechanisms
Tool Post
Compound
Rest
Tool post
• Clamps the tool holder in
the proper position for
machining
operations.
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Chuck
Three Jaw Chuck
- For holding cylindrical
stock centered.
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Lead Screw:
• A screw rod which moves longitudinally in front of the
lathe bed.
• Rotation of the lead screw moves the carriage to and
fro longitudinally during thread cutting operation.
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Feed rod:
• A stationary rod mounted in front of the lathe bed
• Facilitates longitudinal movement of carriage during
turning and facing operations.
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Center Drilling
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Turning Between Centers
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