UNIT-3SHAPING , SLOTTING & PLANING MACHINES
By
D. Kanaka RajaDepartment of mechanical engineering,
AITS
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Shaping Machine is also called Shaper
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What is a shaper ? A Machine which
produces flat surfaces
A Ram holding the Tool reciprocates
Work is fed perpendicular to the tool
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Shaper - working principle
WORK
TOOL
B
A
In the shaper, the cutting tool has a reciprocating motion, and it cuts only during the forward stroke.
Cutting Tool repeatedly travels along line A B
Work is fed a small distance each time
Feed of work & line of tool motion are in same plane but perpendicular
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Working principle – Contd.
The tool line eventually reaches position C D
Combination of two movements results in the flat plane ABCD being machined B
A
D
C
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Classification of shapers
Basic types:
Horizontal Shaper
Vertical Shaper
Traveling head Shaper
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Horizontal shaper: Ram holding the cutting tool moves In horizontal
plane
Vertical shaper: The cutting tool moves in vertical plane
Traveling head shaper: Cutting tool reciprocates & moves cross wise
simultaneously.
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Detailed classification
M305.23 9
a) Push Type Shaper 1. Acc. to Cutting Stroke action b) Draw Type Shaper
a) Standard Shaper 2. Acc. to the Table Design:
b) Universal Shaper a) Crank type 3. Acc. to Driving Mechanism: b) Geared type c) Hydraulic
Shaper
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Push type shaper
Metal is removed when the ram moves away from column
Most common type used in practice
Unless otherwise specified, the term shaper refers to Push type Shaper
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Draw type shaper
Metal is removed when the tool is drawn towards the column
Allows heavier cuts to be made
Less vibration during cutting
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Standard shaper Work Table can be moved Vertically & Horizontally. it cannot swivelled or tilted.
Universal shaper Table can be moved Horizontally Vertically Swivelled & Tilted This is mostly used in Tool Rooms
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Crank type shaper: Driving mechanism is by crank and a slotted lever quick return
motion mechanism is used to give reciprocating motion to the ram. The crank is adjustable and is arranged inside the body of bull gear.
Geared type shaper: Driven by Rack & Pinion mechanism
Hydraulic shaper:• Driven by oil pressure developed by a pump, which is run by an
electric motor.• It is more efficient than the crank and geared type shapers.
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SHAPING MACHINE - Working
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SHAPING MACHINE - PARTS
BASE
COLUMN
RAM
CROSS RAIL
TABLE
TOOL
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Main parts of a shaping machine
1. BASE 5. CROSS RAIL
2. COLUMN 6. SADDLE
3. RAM 7. TOOL HEAD
4. TABLE 8. CLAPPER BOX
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Constructional details of a shaper
BASE
TABLE
CROSS RAIL
RAMTOOL HEAD RAM CLAMP
CLUTCH
COLUMN
TOOL POST
BASE
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Parts - functions
1. Base Bottom most part Supports other parts of the machine Acts as a reservoir of lubricating oil Made of Cast Iron
BASE
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2. Column
Vertically mounted on the base
Houses Driving Mechanism of Ram
Has guide ways on which Ram slides
Made of Cast Iron
COLUMN
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3. Ram
The main moving
part of a Shaper It carries Tool Head Connected to Driving
Mechanism
R A M
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4.Table
A box like casting with T-slots on its top
Shaper vice is fitted in the T-slots
Work is fixed in the vice
TABLE
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5. Cross rail
Used to move the Table Up & Down
Upward movement is controlled by an Elevating Screw
Side movement is controlled by lead screw
CROSSRAIL
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6. Saddle
It is mounted on cross rail
It supports the Table Moves across the
cross rail left to right Movement obtained
by a cross feed screw SADDLE
CROSS RAIL
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7. Tool head
It is attached to the front end of Ram
Carries Clapper box & Tool post on it
Can be swiveled at any angle on either side
TOOL HEAD
TOOL POST
CLAPPER BOX
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8. Clapper box
It is hinged to the tool head
It houses clapper block
Swings outward in return stroke
Tool post mounted on clapper block
CLAPPER BOX
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Specifications of Shaping Machine
• Max. length of Stroke of Ram• Type of Drive• Power input• Floor Space required• Weight of the Machine• Cutting to Return Stroke ratio• Feed • Size of table• Maximum horizontal and vertical travel of the table
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Working of shaper
Shaper drive Mechanism changes rotary motion of power source (Electric motor) to reciprocating motion of Ram.
Material removal (cutting) of work piece takes place in the forward stroke of ram.
The return stroke of the ram does no cutting, hence is called Idle stroke.
The Ram with cutting tool has to move slowly in cutting stroke.
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•Since return stroke does no cutting the ram should move faster during return stroke.•The shaper drive system incorporates quick return mechanism. So that the ram moves faster during return stroke•Thus minimizing the (idle time) Quick Return time.
Working of shaper
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Shaper Operations
Machining Horizontal Surfaces
Machining Vertical Surfaces
Machining Angular Surfaces
Cutting Slots, Grooves & Key ways
Machining irregular surfaces
Machining Splines / Cutting Gears
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Steps for Machining
Work is properly held in a vice Table is raised to a gap of 25 to 30 mm between
tool & work The length & position of stroke are adjusted The length of stroke should be nearly 20 mm
longer than the work
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Steps for Machining The approach & over run should be 10 & 5 mm
respectively.
Depth of cut is adjusted by rotating down the feed screw of tool head
Feed is adjusted about half the width of cutting edge of tool
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Machining Horizontal Surfaces
Fix the work properly on the table Adjust the length of stroke Set the required cutting speed Give required feed of the table Fix an appropriate tool in the tool head Give suitable depth of cut for rough cuts Finishing the job by giving less depth of cut
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Machining Horizontal Surfaces
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Machining Vertical Surfaces
Fix up the job on the table firmly Align the surface to be machined properly Fix up a side cutting tool in the tool head Set the vertical slide exactly at zero Swivel the apron away from the job Switch on the machine Rotate down feed screw by hand to give down
feed Feed in about 0.25 mm
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Machining Vertical Surfaces
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Machining Angular Surfaces
Angular shaping is carried out to machine inclined surfaces, bevelled, dove tail etc.,
Set the work on the table Swivel the vertical slide of tool head to the
required angle ( to the left or right) Set apron away from work Give down feed as per requirement
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Machining Angular Surfaces
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Cutting Rack or Splines
Fix up a square nose tool in tool head Adjust the length & position of stroke Reduce the cutting speed Give suitable depth of cut Feed the work properly to get equal splines
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Cutting Rack or Splines
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Cutting Key ways
Fix up the job between two centres Cut first spline similar to a key way Move / Rotate work by the required amount Use index plate for this purpose
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Cutting Key ways (At the end)
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Cutting Key ways (Midway)
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Machining irregular surfaces
Fix up a forming tool in tool post Give cross feed in conjunction with down feed Swivel the apron suitably according to the
contour required
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Machining irregular surfaces
WORK
TOOL
Advantages and limitations of shaper Advantages The set up is very quick and
easy and can be readily changed from one job to another.
The work can held easily. The single point tools used are
in inexpensive; These tools can be easily
grounded to any desired shape. Lower first cost. The cutting stroke has a definite
stopping point. Because lower cutting forces,
thin and fragile jobs can be conventionally machined on shapers.
Limitations By nature is a slow machine
because of its straight line, forward and return stroke. The single point tool requires several strokes to complete a work.
The cutting speeds are not usually very high speeds of reciprocating motion due to high inertia forces developed in the motion of the units and components of the machine. Owing to these reasons the shaper does not find ready adaptability for assembly and production line.
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Shaper Driving Mechanisms
• Whitworth quick return mechanism• Slotted link quick return mechanism• Hydraulic quick return mechanism
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Quick Return Mechanism
Q.R.M
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Whitworth Quick Return Mechanism
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Whitworth Quick Return Mechanism
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Whitworth Quick Return Mechanism
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Whitworth Quick Return Mechanism
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Crank BC revolves at a uniform speed. During cutting stroke point C travels from Y to X through Z. Ram returns at high speed as the crank rotates from X to Y through T. Then: Time for cutting stroke 360 - Ø Time for return stroke Ø Since Ø is smaller than 360 – Ø, the time for cutting is more than the
idle time. Stroke length can be changed by varying the radius AE
=
Whitworth Quick Return Mechanism
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Crank & Slotted Link
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Crank & Slotted Link QRM
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Main Parts of the Mechanism
BULLGEAR
BULLGEAR
SLIDING BLOCK
CRANK PIN
BULLGEAR
SLIDE
LEAD SCREWBEVEL GEARS
ROCKER ARM
SLIDING BLOCK
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Line diagram ofCrank & Slotted lever Mechanism
Driving Pinion
Slotted Lever
Crank pin
Lead Screw
Clamping lever
Ram
Ram Block
Bevel Gears
Bull gear Sliding block
Lever Sliding block
Bull Gear
Bull gear Slide
Pivot
Bevel Gears
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Elements of the Mechanism
Crank pin(11) is fitted in the slotted link(9)
Bottom end of slotted link (rocker arm) is attached to frame of column(15)
Its upper end is connected to ram(2).
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Working Principle
Electric motor drives pinion (1) Pinion (1) drives the bull gear(14) A Radial slide (16) is bolted at the centre of bull gear. Radial slide carries a sliding block(12) & a crank pin (11) As the bull gear 14 rotates, crank pin 11 rotates. So sliding block 12 also rotates on the crank pin circle. Simultaneously crankpin will move up & down in the slot of
the slotted link 9.
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Working Principle - concluded
As the crank pin11 moves, slotted link 9 gets rocking movement.
This rocking movement is communicated to the ram.
Thus the rotary motion of the bull gear is converted to reciprocating motion of the ram.
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PRINCIPLE OF Q.R.M.
P
M N
K
O
L
C2C1
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Principle - Explained
When the link is in the position PM, ram will be at the extreme backward position.
When it is at PN, ram is at extreme forward position.
P
M N
K
O
L
C2C1
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Principle - Continued
PM&PN are tangents drawn to the crank pin circle.
Forward cutting stroke takes place through the angle C1K C2
Return stroke takes place through the angle C2 L C1 of the crank.
It is evident that angle C2K C1
is greater than C2 L C1 P
M N
K
O
L
C2
C1
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Principle - Concluded
P
M N
K
O
L
C2C1
• Angular velocity of crank pin is constant.• So Return stroke is completed in a shorter time.• Therefore it is known as quick return motion.
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Ratio between cutting time & return time.
Cutting time : Return stroke = Angle C1KC2 : Angle C2LC1 Cutting time : Return time ratio usually varies bet 2 : 1. Practical limit is 3 : 2
M N
K
O
L
C2C1
Hydraulic drive
Quick return in the hydraulic shaper is accomplished by increasing the flow of hydraulic oil during the return stroke.
In the hydraulic shaper the ram is connected to the hydraulic cylinder which is controlled by means of a 4 way valve.
The hydraulic fluid is pumped to the hydraulic cylinder through 4 way valve; this valve is connected to the sump.
The 4 way valve controls the direction of high pressure fluid into the cylinder and controls the direction of motion, either the cutting stroke or return stroke.
Hydraulic drive
The flow control valve controls the flow rate of the hydraulic fluid thereby controlling the speed at which ram moves.
Since the power available remains constant throughout, it is possible to utilize the full capacity of the cutting tool during the cutting stroke
The starting and stopping of the machine is achieved by through a finger operator lever.
An adjustable trip dog operated lever controls the operation of 4 way valve to control the ram reversible.
The return or idle stroke is faster than the cutting stroke because of the smaller area in the return side of the cylinder if constant volume pump is used.
Hydraulic drive
The cutting stroke has a more constant velocity and less vibration is induced in the hydraulic shaper.
The cutting speed is generally shown on an indicator and does not require calculation.
Both the cutting stroke length and its position relative to the work may be changed quickly without stopping the machine.
The hydraulic feed operates while the tool is clear of work. More strokes per minute can be achieved by consuming less
time for reversal and return strokes.
Advantages of hydraulic drive
The stopping point of the cutting stroke in a hydraulic shaper can vary depending upon the resistance offered to cutting by the work material.
It is more expensive compared to the mechanical shaper.
Disadvantages
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Clamping the Work on a Shaper
Work should be properly & firmly fixed on the Shaper table
Work is fixed on the table by 3 methods.• Using a Swivel Vice• Using T bolts & Clamps• Using Angle plate & C Clamps
Work holders
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Using a Swivel Vice
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Using T bolts & Clamps
Cutting speed is defined as the average linear speed in stroke in m/mm, which depends on the number of ram stokes(or ram cycles) per minute and the length of stroke.
The number of double strokes or cycles of the ram/min N= the number of double strokes or cycles of the ram L=length of the ram stroke, mm K= return stroke time Where k=2/3, 3/4
Cutting speed
Vc = NL(1+k)/1000 m/mm
The feed is the relative motion of the work piece in a direction perpendicular to the axis of reciprocating of the ram.
Feed is given to the work piece. Depth of cut d is the thickness of the material removed in
one cut,in mm.
Feed
The machining timethe time required to complete one double stroke, from cutting speed Vc is given by
With a feed of f mm/double stroke, number of strokes required to machine a surface of width B will be Ns=B/f
Machining time
t = L(1+K)/1000Vc
Hence total machining the surface of width B will be
In terms of ram strokes N, the time for machining the surface is given by
Ns=B/fN minMachine time tm = B/f ((L/Vc*1000)+(L /Vr *1000)Where B= width of the job mm f = feed mm/ stroke l = length of stroke, mm Vc = Cutting speed Vr = return stroke speed mm/min
t = LB(1+K)/1000Vcf
Machining time
Slotting machine
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Slotting machine
Slotting machine is also called as Slotter
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Line diagram of slotter
SADDLE
CROSSSLIDE
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Slotters
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Slotter
• A Machine which produces flat surfaces
• A Ram holding the Tool reciprocates
• Ram reciprocates in vertical direction
• Work is fed perpendicular to the tool
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Slotter - working principle
WORK
TOO
L
B
A Cutting Tool repeatedly travels
along line A B Work is fed a small distance
each time Feed of work & line of tool
motion are in same plane but perpendicular
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WORKING PRINCIPLE – contd.
The tool line eventually reaches position C D
Combination of two movements results in the flat plane ABCD being machined
BA
DC
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WORKING PRINCIPLE – contd.
Work is supported on a rotary table.
Table can have longitudinal and rotary movements
Straight and rotary cuts can be produced.
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CLASSIFICATION
According to design and purpose the slottersare classified into two types
1. Puncher Slotter2. Precision tool room Slotter
Puncher slotter: Intended for removing large amount of metal from heavy
works. heavy and rigid machine Ram driven by rack and spiral pinion mechanism used for machining large castings and forgings
Production slotter
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Precision tool room slotter:• Used for tool room work, where accuracy important• Lighter in construction• Fitted with quick return mechanism• Operates at high speeds and designed for light cuts• Gives accurate finish• Suitable for small to medium size work pieces
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Difference between vertical shaper and Slotter
• in vertical shaper the tool holding ram can tilt by about 100 with respect to vertical axis• In slotter ram cannot tilt at all.• In all other aspects vertical shaper and slotter are similar
M305.30 100
Slotting machine Introduction
Having known the Working Principle we will now look at :
The Constructional Details of a slotting Machine Function of each part Specifications of a slotter
M305.30 101
Slotting machine -construction
BASE
CIRCULAR TABLE
COLUMN
RAM
CROSS SLIDE
SADDLE
T-SLOTS
TOOL HEAD
M305.30 102
Slotting machine
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Line diagram of slotter
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Main parts of a slotter
1. Base 5. Cross slide
2. Column 6. Saddle
3. Ram 7. Tool head
4. Table
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Parts - functions 1. Base
Bottom most part Supports other parts of the machine Acts as a reservoir of lubricating oil Made of Cast Iron
Contd..
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Base Rigidly built to take up cutting forces Top of bed is accurately finished Guide ways are provided for saddle Guide ways are perpendicular to column face
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Column
Vertically mounted on the base
Houses Driving Mechanism of Ram
Has guide ways on which Ram slides
Made of Cast Iron Also houses feeding
mechanism
COLUMN
M305.30 108
Ram Reciprocating vertically up
and down of a slotter Mounted on guide ways of
column It carries Tool Head / cutting
tool Connected to Driving
Mechanism An arrangement is provided
on the body of ram to change length of stroke
R A M
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Table It holds the work
piece. A circular casting with
T-slots on its top Movement of table
can be linear or rotary Table is graduated in
degrees so indexing can be done
Slotter vice may be fitted in the T-slots
Work may be fixed in the vice
Operated manually or by power
TABLE
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Saddle
It is mounted on guide ways of bed It can be moved towards or away from bed Using saddle longitudinal feed is given Top is accurately finished to provide guide ways
for cross slide These guide ways are perpendicular to the guide
on the base Operated either manually or by power
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Cross slide Circular work-table is mounted on the top.
Mounted on guide ways of saddle
Moves parallel to the face of the column
Using cross slide cross feed is given
Operated either manually or by power
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Tool head
It is attached to the bottom end of Ram
Carries Tool post on it
Tool is fixed in position
No swiveling along verticle axis or horizontal axis
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Specifications of Slotting machine Max. length of Ram Stroke Diameter of work table in mm. Type of Drive Maximum table travel. Power input Floor Space required
Specification
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Slotter driving mechanism A Slotting machine produces flat surfaces The Ram holding the Tool reciprocates vertically up
and down Cuts the material only in down stroke There should be some mechanism to move the ram
in reciprocating motion It is called as slotter driving mechanism The mechanism commonly used is slotted disc
mechanism
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Slotted disc mechanism
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Quick return mechanism (QRM) A Mechanism makes the ram to move slowly
during cutting stroke.
During return stroke ram moves at a faster rate.
To reduce the idle time,It Should return quickly .
The mechanism adopted is known as QRM
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Methods to obtain Q.R.M. in slotter
1. Whitworth Q.R.M. Mechanism2. Variable speed reversible motor drive
mechanism3. Hydraulic drive Mechanism The mechanisms for QRM in slotter are similar to
QRM in shaper
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Feed in Slotter In Slotter feed is given by table Feed movement is intermittent Feed is given at the beginning of the cutting
stroke Feed may be given either manually or by power Table will have three types of feed movements
a. longitudinalb. cross and c. circular feeds.
Contd…
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Types of feed in Slotter
Longitudinal feed:• Table is fed perpendicular to the column• Table moves towards or away from the
column
Cross feed:• Table is fed parallel to the face of the column
Circular feed:• table is rotated with respect to
verticle axis
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Feed mechanism of a Slotter
Feed shaft
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Uses a ratchet and pawl mechanism Feed shaft engaged with cross, longitudinal /
rotary feed screws has the ratchet mounted on it. Ratchet is moved by small amount in one
direction only with the help of a connecting rod, lever.
The roller moves in the cam groove cut on the face of the bull gear of slotting machine.
Feed mechanism of a Slotter
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Operations on slotter
1. Machining flat surfaces
2. Machining Circular Surfaces
3. Machining internal surfaces
4. Machining grooves or key ways
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Setup for Machining
Work is properly held in a vice
Table is raised to a gap of 25 to 30 mm between tool & work
The length & position of stroke are adjusted The length of stroke should be nearly 20 mm
longer than the workContd…
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Setup for Machining
The approach & over run should be 10 & 5 mm respectively.
Depth of cut is adjusted by rotating down the feed screw of tool head
Feed is adjusted about half the width of cutting edge of tool
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Machining Flat Surfaces Fix the work properly on the table Adjust the length of stroke Set the required cutting speed Give required feed of the table Tool is held in the tool head of ram Ram reciprocates up and down
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Machining Flat Surfaces
Feed has to be given at the beginning of cutting stroke Both internal and external surfaces can be machined Give suitable depth of cut for rough cuts Finishing the job by giving less depth of cut
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Machining flat surfaces
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Machining circular surfaces
Tool is set radially on the work Work piece is placed centrally on the rotary table Feed is given by the rotary table feed screw Feed screw rotates the table through an arc Adjust the length of stroke Set the required cutting speed Finishing the job by giving less depth of cut
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Machining internal surfaces
Fix up a tool in tool post Cross, longitudinal and rotary feed are combined Any contoured surface can be machined Mostly done manually Good skill is required from operator
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Machining grooves or key ways
Slotter is specially intended for cutting internal grooves
External or internal gear teeth can be machined Fix up the job between two centers Cut first a key way Move / Rotate work by the required amount Indexing can be done by using graduations on rotary
table
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Cutting Key ways
Fix up the job between two centres Cut first spline similar to a key way Move / Rotate work by the required amount Use index plate for this purpose
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Cutting Key ways
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Work holding devices
Work should be properly & firmly fixed on the Slotter table
Work is fixed on the table by 3 methods.
1. Using a Swivel Vice 2. Using T bolts & Clamps 3. Using Angle plate & C Clamps
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Clamping the work on a Slotter is depicted in the following Slides, one by one
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1. Using a Swivel Vice
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2. Using T bolts & Clamps
Planing machine
139
Planing machine
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Another view of Planer
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Table Movement in Planer
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Table Movement in Planer- another view
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What is a planer ?
A Machine which produces flat surfaces
Consists a stationary housing for holding the tools
A table holding the work reciprocates
Large works, that con not be accommodate on shapers
The tool is stationary but the work moves
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Planer - working principle
The table on which work is clamped is imparted a reciprocating movement
Cutting takes place during the forward stroke of table
During return stroke the cutting tool is slightly lifted
Tool is fed for each forward stroke
WORK
TOOL
Work is fixed on Table
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WORKING PRINCIPLE – contd.
Table is driven by an electric motor
Length of table stroke can be adjusted
Speed of return stroke is also regulated
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Principle of operation of a planer
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Classification of planers
1. Double housing Planer 2. Open side Planer 3. Pit type Planer 4. Edge Planer or Plate Planer 5. Divided Table Planer
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It is the Standard model & most widely used Very heavy and robust Has a bed and two vertical housings are fixed Table moves along the guide ways of the bed Housing supports cross rail & tool heads. Cross rail carries two tool heads Tool head carries tools
Double housing planer:
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A double housing planer
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Open side planer
It has only one supporting column (housing) Area larger than the table can be planed Cross rail is mounted as a Cantilever Tool holders are mounted on Cross rail Stroke length of bed is controlled by adjustable dogs
Open side planer
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PIT Planer
Columns and cross rail carrying tool head move longitudinally on massive rail above the work table
Bed is recessed in the floor Loading and unloading of jobs is easy Used for Planing heavy & large jobs Table and work piece resting on it are stationary
and the tool reciprocates
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Edge / plate planer
Specially designed for squaring or beveling the edges of heavy steel plates for pressure vessels
Carriage supporting the tool is moved back and front direction
Cutting can take place during both directions of carriage travel
Operator stands on the platform & operates
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Divided table planer
Also known as Tandem planer Planer has two tables on the bed Table may be reciprocated together or separately Each table reciprocates under different tool head For continuous production, small work pieces
clamped on one table are being machined, another is stationary and can be used for setting up fresh works
Used for quick & continuous production
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Planing machine - parts
BED
TABLE
CROSS RAILCOLUMN
TOOL HEADS
Feed Mechanism
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Main Parts of Planing machine
1. Bed 2. Table 3. Housing or Column 4. Cross rail 5. Tool heads 6. Driving Mechanism 7. Feed Mechanism
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Constructional details of a planer
TOOL HEADS
CROSS RAIL
TABLE
COLUMN
BED
CROSS MEMBER
COLUMN
Feed Mechanism
158
Parts of planer
159
Parts of planer
160
1. Bed Large box like casting Length is nearly twice the table length Consists guide ways on which table moves Houses the driving mechanism of table Made of Cast Iron
161
2.Table
Also called Platen Large rectangular casting mounted on bed ways Holds the work & reciprocates along bed ways Top surface has T slots Work is clamped on T slots
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3.Housing or Column
Large vertical structures on each side of the bed
Supports cross rail on which tool heads are mounted
Also supports the mechanism for operating the tool heads
Made of Cast Iron
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4. Cross rail
A rigid casting mounted horizontally on the column Can be moved up & down by elevating screw Carries two slides with tool heads Tool heads can be moved horizontally on the guide
ways of cross rail
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5. Tool heads
Contains tool posts for holding the tools Tool post (clapper block) is hinged to the head During return stroke cutting tool will be lifted Tool heads can be swiveled through 60º on either
side of its vertical position
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Specifications of a Planer
1. Distance between the two housings
2. Height between Table & cross rail at its uppermost position
3. Maximum length of table travel
4. Number of Speeds & feeds available
166
Specifications of a Planer- contd.
5. Power input
6. Floor space required
7. Type of Drive
8. Net weight of the Machine
167
Mechanism Introduction A Planing Machine produces flat surfaces
The Table holding the Work reciprocates
There should be some mechanism to move the Table in reciprocating motion, and
Table to move quick during idle stroke
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Mechanisms to drive the Table (QRM)
1. Open & Cross belt drive
2. Reversible motor drive
3. Hydraulic drive
169
1.Open & Cross belt drive MechanismLoose Pulley
Fast Pulley
17. Belt shifter lever
Pulleys on Shaft
Open beltCross beltBelt shifter
Counter Shaft
Loose PulleysFast Pulleys
9,12
10,11
13 - Bull gear shaft14 - Bull gear
Rack
18. Trip dog19 - Table
Change gears
Feed disc
170
Open & Cross belt drive Mechanism Used for smaller capacity machines
Table is moved by gears & rack attached under the table
Counter shaft at the top of housing has 2 pulleys
These Pulleys transfer power to main shaft(Driving)
Main shaft drives the table by rack & pinion
171
Open & Cross belt drive Mechanism 2 Sets of fast & loose pulleys are mounted on driving
shaft at one end and pinion is on another endRETURN STROKE: Smaller fast pulley is used for backward motion of table
(Quick motion) It is connected by open belt drive The open belt passes over small fast pulley to get
Quick return The Cross belt is on loose pulley so it will not drive
172
Open & Cross belt drive Mechanism FORWARD STROKE: Bigger fast pulley is driven by cross belt drive It is used to drive the table during cutting stroke Open belt is on loose pulley At the end of cutting stroke, cross belt is shifted from fast
pulley to loose pulley Simultaneously open belt is shifted from loose pulley to fast
pulley This is achieved by trip dog which operates belt shifting
lever Thus the direction of movement is automatically reversed
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Rack & Pinion used to move Table
174
2. Reversible Motor Drive Mechanism
Electric motor drives the bull gear through gear trains
Motor is coupled to D.C. generator
When motor is started, generator supplies power to reversible motor
175
Reversible Motor Drive Mechanism Reversible motor causes the planer table to move
At the end of stroke, trip dog operates the switch which reverses the direction of table
Speed of cutting stroke is reduced by regulating the field current of the generator
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Reversible Motor Drive Diagram
Exciter
A.C.driving motor Generator
Reversible motor Motor field
resistance
Motor field
Generator field
Reversing switch
177
3.Hydraulic Drive of Planer
TABLE
Operating Cylinder
Speed Control
178
Forward Stroke of Table
During cutting stroke, oil is pumped into LHS of cylinder
As the area is less due to presence of piston rod, less force acts
So the table moves slowly in cutting stroke
At the end of each stroke trip dog operates a lever
Lever actuates the control valve of circuit
TABLE
179
Return Stroke of Table
Oil is pumped into the Operating cylinder
Cylinder contains piston & piston rod
The other end of piston rod is connected to the Table
During return stroke, oil is pumped into RHS of cylinder
More force acts on the piston & it moves quickly
TABLE
180
Cycle Repeated
Flow of oil is changed from one side to the other side of cylinder
The length of stroke can be varied by adjusting the distance between trip dogs
181
Planer Operations
1.Planing Horizontal Surfaces
2. Planing Vertical Surfaces
3. Planing Angular Surfaces / Dovetails
4. Planing Curved surfaces
5. Planing Slots, key ways & Grooves
182
Planing Horizontal Surfaces
Fix the work properly on the table
Set the required cutting speed
Give required feed of the tool
Give suitable depth of cut for rough cuts
Finishing the job by giving less depth of cut
183
WORK
PLANER TABLE
Planing Horizontal Surfaces
TOOL
CLAPPER BLOCK
184
Planing Vertical Surfaces
Fix the job on the table firmly Align the surface to be machined properly Vertical side is adjusted perpendicular to the
table Swivel the apron away from the job Switch on the machine Rotate down feed screw by hand to give down
feed
185
Planing Vertical Surfaces
PLANER TABLE
WORK
186
Planing Angular Surfaces
Main angular planing is to make dove tails & V grooves
Set the work on the table Swivel the tool head to the required angle Set apron away from work Give down feed as per requirement
187
Planing Angular Surfaces
188
Planing Formed Surfaces Fix up a square nose tool in tool head
Required form is obtained by feeding the tool simultaneously in both hor. & ver. Directions
Give suitable depth of cut
This can also be done with the aid of a special fixture
189
TOOL
WORK
PLANER TABLE
Planing Formed Surfaces
190
Planing Slots & Grooves Fix up the job on the table suitably
Fix Slotter tools in tool heads
Give feed using down feed screw
Move the tool by the required amount to get uniform slots / grooves
191
Cutting Rack or Splines
PLANER TABLE
WORK
1. Heavier, more rigid costlier machine.
2. Requires more floor area.
3. Work reciprocates horizontally.
4. Tool is stationary during cutting.
5. Heavier cuts and coarse feeds can be employed.
6. Work setting requires much of skill and take longer time.
7. Several tools can be mounted and employed simultaneously, usually four as a maximum facilitating a faster rate of production.
8. Used for machining large size work pieces.
1. A comparatively lighter and cheaper machine.
2. Requires less floor area.
3. Tool reciprocates horizontally
4. Work is stationary during cutting.
5. Very heavy cuts and coarse feeds cannot be employed.
6. Clamping of work is simple and easy.
7. Usually one tool is used on a shaper.
8. Used for machining small size work piece comparatively
Comparison between planer and shaperShaperPlaner
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