4. Introduction
• Drilling is a metal cutting process carried out
by a rotating cutting tool to make circular
holes in solid materials.
• Tool which makes hole is called as drill bit or
twist drill.
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5. Drilling machine
• A power operated machine tool which holds
the drill in its spindle rotating at high speeds
and when actuated move linearly against the
work piece produces a hole.
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8. Bench drilling machine
• These are light duty machines used in small
workshops.
• Also called Sensitive drilling machines because of
its accurate and well-balanced spindle.
• Holes of diameter 1 mm to 15 mm.
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10. PRINCIPAL PARTS OF THE DRILLING MACHINE
1. Head: Head contains the electric motor, v pulleys and v belt which
transmit rotary motion to the drill spindle at a no. of speeds.
2. Spindle: spindle is made up of alloy steel. It rotates as well as moves up
and down in a sleeve.
3. Drill chuck: It is held at the end of the drill spindle and in turn it holds
the drill bit.
4. Adjustable table: It is supported on the column of the drilling machine
and can be moved vertically and horizontally. It also carries slots for bolts
clamping.
5. Base: It supports the column, which, in turn, supports the table, head
etc.
6. Column: It is a vertical round or box section, which rests on the base
and supports the head and the table
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11. working
• Work piece with the exact location marked on it
with the center punch is clamped rigidly on the
worktable.
• spindle axis and center punch indentation are in
same line.
• Machine is started and drill bit is lowered by
rotating feed handle.
• Drill bit touches the work and starts removing
material.
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12. Radial drilling machine
• These are heavy duty and versatile drilling machine
used to perform drilling operate on large and heavy
work piece.
• Holes up to 7.5 cm.
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14. working
• Work piece is marked for exact location and
mounted on the worktable.
• Drill bit is then located by moving the radial arm
and drill to the marked location.
• By starting drill spindle motor holes are drilled.
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15. Upright drilling machine
• These are designed for
handling medium sized work
pieces.
• In construction it is similar to
sensitive drilling machine but
it is heavier than sensitive
drilling machine.
• In this large number of
spindle speeds and feeds are
available.
• But it is heavier than sensitive
drilling machine
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16. Gang drilling machine
• When a number of single spindle drilling machine columns are placed side
by side on a common base and a common work table , the machine is
known as gang drilling machine.
• In a gang drilling machine 4 to 6 spindles may be mounted side by side.
• The speed and feed of the spindles are controlled independently.
• Each spindle may be set up properly with different tools for different
operations.
• A series of operations may be performed on the work by simply shifting
the work from one position to the other on the work table.
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17. Multiple spindle drilling
machines
• Used to drill a number of
holes in a piece of work
simultaneously and to
reproduce the same
pattern of holes in a
number of identical pieces
in a mass production work.
• In this several spindles are
driven by a single motor
and all the spindles holding
drills are fed into the work
simultaneously.
• Feed may be obtained by
raising the table or lowering
the drill head.
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20. 1. Drilling: it is an operation of producing a circular hole in a work piece by
forcing a drill in the work piece.
2. Boring: it is an operation of enlarging a hole that has already been drilled.
Single point cutting tool is used in boring.
3. Reaming: Reaming is done with reamers. It is done to generate the hole of
proper size and finish after drilling
4. Tapping: It is an operating of producing internal threads in a hole by means of
a tap.
5. Counter Boring: It is an operation of enlarging the entry of a drilled hole to
accommodate the bolt head etc. Counter boring tool does it.
6. Spot Facing: It is an operation done on the drilled hole to provide smooth
seat for bolt head.
7. Counter Sinking: It is an operation to bevel the top of a drilled hole for
making a conical seat. A counter sunk drill is used in this operation.
8.Trepanning
Trepanning is the operation of producing a hole in sheet metal by removing
metal along the circumference of a hollow cutting tool. Trepanning operation is
performed for producing large holes
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35. Introduction
• It is reciprocating type of machine tool used for
producing flat surfaces.
• Surfaces may be horizontal, vertical or inclined.
• Modern shapers can produce contoured surfaces.
• It uses reciprocating straight line motion of the tool
and a perpendicular feed of the job or the tool.
• By moving the work piece across the path of the
reciprocating tool, a flat surface is generated
regardless of the shape of the tool.
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38. Principle
• On a shaper, job is fixed on the work table (i.e. job
remains stationary) and the tool cuts while
reciprocating over the job. The tool is mounted on a
reciprocating ram and the table which supports the job
is fed normal to the tool motion at each stroke of the
ram.
• The tool cuts in the forward stroke generally, only in
case of a draw-cut shaper the tool cuts in backward
stroke of the ram.
The other stroke in both the cases remains idle as
there is no cutting action in that stroke.
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51. • A shaper is a reciprocating machine tool intended primarily to produce
horizontal, vertical or inclined flat surfaces.
• The bull gear receives its rotation from the motor through the pinion.
• The rotation of the crank causes oscillation of the link and thereby
reciprocation of the ram and hence the tool in straight path.
• The cutting motion provided by the reciprocating tool and the
intermittent feed motion provided by the slow transverse motion of
the work at different rate by using the ratchet - pawl system along with
the saddle result in producing a flat surface.
• The vertical in-feed is given either by descending the tool holder or
raising the cross rail or both.
• The work piece is clamped directly on the table or clamped in a vice
which is mounted on the table.
• The changes in length of stroke and position of the stroke required for
different machining are accomplished respectively by:
– Adjusting the crank length by rotating the bevel gear mounted
coaxially with the bull gear.
– Shifting the ram block nut by rotating the lead screw.
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53. Principal Parts
• Base: Shaper base is a heavy structure of cast iron. It supports
all the other parts and assemblies (described in the following).
It resists vibration and high compressive loads being of cast
iron. Base is bolted down to the shop floor through foundation
bolts .
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54. • Column: It is a box structure of cast iron and houses the
operating mechanisms of the machine. It also provides
support for other parts of the machine, such as ram, cross-
rail, etc. Column consists of two vertical walls which are
supported on the shaper base.
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55. • Cross-rail: The cross-rail block is mounted on the front two
vertical guide ways of the column .The cross-rail block has
two parallel horizontal guide ways(K) in the vertical plane
and perpendicular to the axis of ram.
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56. • Saddle: The saddle moves on the cross-rail block and
carries the table (or work table) on it such that crosswise
movement of the saddle by rotating the cross feed screw by
hand or by power makes the table to move sideways.
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57. • Table: The table is firmly connected on to the saddle. It gets
its crosswise and vertical movements from the saddle and
cross-rail, respectively (as explained above in case of
saddle). Table is a box structure casting having T-slots both
on top and sides for clamping the job.
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58. • Ram: It is the reciprocating member with tool head mounted on its
front face. Ram is semi-cylindrical in form with rigid structure
heavily ribbed inside. It slides on two accurately machined guide
ways (dovetail type) made on the top of column walls. The ram is
connected to the reciprocating mechanism (quick return) housed
inside the hollow of the column. the ram is housed the mechanism for
altering the ram positions with respect to the job.
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59. • Tool head or shaper head: It is mounted at the front end of
ram and has the provision of being swiveled in any direction
for shaping angular surfaces. The tool is held in tool post.
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66. QUICK RETURN MECHANISM OF A SHAPER
• In a shaper, rotary movement of the drive is converted into
reciprocating movement of the ram by the mechanism contained
within the column of the machine.
• In a standard shaper metal is removed in the forward cutting stroke
and during the return stroke no metal is removed. To reduce the total
machining time it is necessary to reduce the time taken by the return
stroke.
• Thus the shaper mechanism should be so designed that it can allow
the ram to move at a comparatively slower speed during the forward
cutting stroke and at a faster rate during the return stoke to reduce
the idle return time. This mechanism is known as quick return
mechanism.
• The reciprocating movement and the quick return of the ram are
usually obtained by using any one of the following mechanisms:
• Crank and slotted link quick return mechanism(mechanical)
• Whitworth quick return mechanism(mechanical)
• Hydraulic drive quick return mechanism
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67. CRANK AND SLOTTED LINK QUICK RETURN MECHANISM
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86. AUTOMATIC FEED
MECHANISM OF
SHAPER MACHINE
• The automatic feed
mechanism of the table
is very simple. This is
done by rotating a
ratchet wheel, mounted
at
the cross feed screw.
This enables a
corresponding equal
rotation of the cross-feed
screw after each stroke
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87. • This arrangement helps the power feed to operate in
either direction, but the same should be set to
operate
during the return stroke only. If otherwise, the
mechanism will be subjected to severe stress. In
some latest
types of shapers, can driven feed mechanisms are
provided which are more efficient and provide a
wider range
of feed.
Variation in the feed can be provided by varying the
distance R between the disc centre and the centre of
the
adjustable pin. Larger the said distance greater will
be the feed and vice versa. The amount of feed to
be given
depends upon the type of finish required on the job.
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88. • For rough machining, heavier cuts are employed,
and thus, a coarse feed is needed. Against this, a
finer feed is employed in finishing operations.
The slotted disc at its back carries a spur gear
which is driven by the bull gear. As the disc rotates
through this
gear the adjustable pin, being eccentric with the
disc centre.
• This causes the connecting rod to reciprocate. This,
in turn, makes the rocker arm to swing about the
screw C to move the pawl over one or more teeth.
Thus transmit an intermittent motion to the
crossfeed screw which moves the table.
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91. PLANNING MACHINE (or) PLANER
• Like shapers, planers are also basically used for producing flat surfaces.
But planers are very large and massive compared to the shapers.
• Planers are generally used for machining large work pieces which cannot
be held in a shaper. The planers are capable of taking heavier cuts.
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98. Construction: The main parts of the double
Housing Planer machine is Bed and table,
Housings, Cross rail, , Tool heads, Driving and
feed mechanism.
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100. • MAJOR PARTS OF A PLANER
• Bed:
• It is box like casting having cross ribs. It is a very large in size and heavy in weight
and it supports the column and all other moving parts of the machine.
• The bed is made slightly longer than twice the length of the table so that the full
length of the table may be moved on it.
• It is provided with precision ways over the entire length on its top surface and the
table slides on it.
• The hollow space within the box like structure of the bed houses the driving
mechanism for the table.
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101. Table:
• It supports the work and reciprocates along the ways of the bed.
• T-slots are provided on the entire length of the table so that the work
and work holding devices may be bolted upon it. Accurate holes are
drilled on the top surface of the planer table at regular intervals for
supporting the poppet and stop pins.
• At each end of the table a hollow space is left which acts as a trough for
collecting chips. Long works can also rest upon the troughs.
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102. • Housing:
• Also called columns or uprights, these are rigid box like vertical
structures placed on each side of the bed and are fastened to the
sides of the bed.
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103. • Cross rail:
• It is a rigid box like casting connecting the two housings. This construction
ensures rigidity of the machine.
• The cross rail may be raised or lowered on the face of the housing and can
be clamped at any desired position by manual, hydraulic or electrical
clamping devices.
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105. • Driving and feed mechanism: The tool heads may
be fed either by hand or by power in crosswise or
vertical direction. The motor drive is usually at one
side of the planer near the centre and drive
mechanism is located under the table.
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106. TYPES OF PLANER
• Standard or double housing planer.
• Open side planer. • Pit planer.
• Edge or plate planer. • Divided or latching table planer.
Standard
or
double
housing
planer.
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108. WORKING PRINCIPLE OF A DOUBLE HOUSING PLANER
• The w/p is mounted on the reciprocating table and the tools,
on the tool heads.
• The tool heads holding the cutting tools are moved horizontally
along the cross rail by a screw-nut system.
• The cross rail is moved up and down along the vertical rails by
another screw-nut pair.
• The kinematic system of the planer enables transmission and
transformation of the main motor into reciprocating motion of
the large work table and slow traverse feed motions
(horizontal and vertical) of the tool heads.
• The reciprocation of the table, which imparts cutting motion to
the work piece, is attained by rack and pinion (bull gear)
mechanism.
• The rack is fitted with the table at its bottom surface and the
pinion is fitted on the output shaft of the speed gear box. The
feed to the tool is given at the end of the return stroke.
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130. SLOTTER TOOLS
• • A slotter tool differs widely from a shaper tool as the tool in a slotter
removes metal during its vertical cutting stroke.
• • This changed cutting condition presents a lot of difference in the tool
shape.
• • In a shaper tool the cutting pressure acts perpendicular to the tool
length, whereas in a slotter tool the pressure acts along the length of the
tool.
• • The rake angle α and clearance angle γ of a slotter tool look different
from a shaper tool.
• • The slotter tools are robust in cross section and are usually of forged
type: of course, bit type tools fitted in heavy tool holders are also used.
• • Keyway cutting tools are thinner at the cutting edges.
• • Round nose tools are used for machining contoured surfaces.
• • Square nose tools are used for machining flat surfaces.
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