MACHINE TOOLS

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• MACHINE TOOLS

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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

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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.

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Working principle of lathe
Chuck
Direction of rotation of work piece
Work piece
Cutting tool
Direction of cutting tool
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Working principle of a lathe

• Cutting tool can remove material 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
• Uses V shaped cutting tool

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Lathe Basics
Spindle Nose
Tailstock Spindle Clamp
Tool Post
Compound Rest
HEADSTOCK
TAILSTOCK
Saddle
Feed Change Lever
Feed Reverse Lever
Lead Screw
BED WAYS
APRON
Bed
Half Nut Lever
Friction-clutch Control
Gear Box
Carriage Hand Wheel
Motor Drive
Cross Slide
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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
• Saddle
• Cross slide
• Compound Rest
• Apron
• Tool post

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Lathe Carriage and Apron
Tool Post
Compound Rest
Carriage Lock Screw
Cross Feed Knob
Cross Slide
Apron Hand Wheel
Half Nut Lever
Compound 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