automation for patching butyl tubes - My Campus Placements

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5 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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1


A

PROJECT REPORT ON


“AUTOMATION FOR

PATCHING

BUTYL TUBES”


SUBMITTED BY
:

Mr. QUAID VOHRA

Mr. KIRAN MOKAL

Mr. APOORVA RAUT

Mr. ISHWAR PADALKAR


UNDER THE GUIDANCE OF

Prof. M.R.PARDESHI





DEPARTMENT OF MECHANICAL

ENGINEERING

K. K. WAGH INSTITUTE OF
ENGINEERING EDUCATION AND

RESEARCH, NASHIK.

UNIVERSITY OF PUNE

YEAR 2012
-
2013


2


K.K WAGH INSTITUTE OF ENGINEERING EDUCATION AND RESEARSH
NASHIK
-
3

DEPARTMENT OF MECHANICAL ENGINEERING

YEAR 2012
-
2013


CERTIFICATE

This is to certify that

Mr. KIRAN MOKAL





Mr. ISHWAR PADALKAR

Mr. APOORVA RAUT




Mr. QUAID VOHRA

have successfully completed the
ir project on

“AUTOMATION FOR PATCHING

BUTYL TUBES”

Sponsored by

Art Rubber

Industries

Pvt Ltd, Nashik

In the partial fulfilment of
the requirements of B
achelors Degree in Mechanical
Engineering as prescribed by

University of Pune for academic year 2012
-
13



Prof.M.R.Pardeshi


Prof.M.B

Murugkar

Dr.K.N.Nandurkar

Project guide


H.O.D







Principal



Examiner

3


ACKNOWLEDGEMENT


I gives us immense pleasure to express our gratitude to all those who have helped and
encouraged us in completing this project. The amount of knowledge and experience
gained has left us feeling
of joy and satisfaction.


We shall remain indebted to Prof. M.R. Pardeshi and
Mr.

A.S.Tidke &


Mr.

Naikwade
,
for their guidance and valuable
suggestions
,

using their
exhaustive knowledge

of mechanical and electrical systems
. Our gratitude for
them is never

ending.


We would also like to thank our Head of Department Prof.

M.
B
.

Murugk
ar

Sir

and staff members who directly or indirectly supported us

in completion of our
project.

Last but not least, we are grateful to our pare
nts for their moral support
and
cons
tant encouragement we received from them.




Yours truly,

Kiran Mokal

Apoorva Raut

Ishwar Padalkar

Quaid Vohra








4


SYNOPSIS


Butyl tubes are manufactured by extrusion
.
The place where valve is to be fitted is
marked by a plastic patch.
At Art Rubber Industries Ltd Nasik, patching is being done
manually by sticking the patch on hot rubber tube and then rolling over it with a roller



Manually putting patches makes the process inaccurate and tiring for the worker.
Automation

will result in saving of material and reduction of rework. Human effort
will be minimized and inaccuracies will be reduced, making the process time saving
and cost effective.


Our project aims at
designing and developing an automatic patching machine to
be used for all sizes of tubes and all different patch positions.

We intend to use a combination of a pneumatic and electronic system for the machine.


Key words: patching, rolling, automatic, pneu
matic














5


CONTENTS


1.

INTRODUCTION

9

1.1

Company profile
…………………………………………………………9

1.2

Manufacturing process of Butyl tubes
……………………………
..


10

1.3

Need of automation
………………………………………………

….10

1.4

Objectives
………………………………………………
.
………………11

1.5

Design
requirements.,…………………………………………
….
…….11


2. LITERATURE SURVEY

12

2.1 Automation
…………………………………………………

…………12

2.2 Pne
umatic control
…………………………………………
.

..
………..12

2.3 Principles of circuit design for automation system
…………
...
........
……12

2.4
B
asic principle of pick and p
lace devices
……………
….
………
..

.
….14

2.5
G
ripper design consideration
……………………………

……
.


…15

2.6
S
uction cups
………………………………………………

……
.
……16

2.7
S
uction cups selection and design
…………………………


………17


3
.

PROPOSED SOLUTION








20

3.1
P
rinter mechanism
………………………………
………
………
..
………20

3.2
T
ransfer devices for flat work
p
ieces one cylinder


and suction gripper
………………………………………………
.
..........
.
….21

3.3
L
inear unit with two cylinder and suction gripper
…………
..…
……

.
..22

3.4
O
verhead swivel motion feed mechanism
………………………
.............
23

3.5
F
eeding machine from two magazines
……………………………
..
.
…..23

3.6
R
otary arm using two cylinders
…………………………………
..
.
…….24


4. CIRCUIT DESIGNING AND SELECTION OF COMPONENTS

25

4.1 Objectives
……………………………………………………
….

.
……25

4.2
Co
mponents
………………………………………………
..
……

......
.
..26

4.3
W
orking
……………………………………………………………
…..
..27


6



4.4
S
election of components

4.4.1
S
election of
suction cups
……………………………
……

.
.
…..28

4.4.2
S
election of main cylinder
…………

……………………
.

.
…30

4.4.3
S
election of

vertical

cylinder
……………………………
.

….
…31

4.4.4 S
election of
directional
control valve
………………………
..
…..
.31


5. DESIGN AND ANALYSIS OF MACHINE STRUCRURE


34

5.1

Analysis

of shafts
………………………………………………
……….
34

5.2
D
esign of bearing
………………………………………………
.

.
……36

5.3
Analysis
of welded joints
…………………………………
….

.


…38

5.4
A
ssembly drawing
…………………………………………

……
..
……41


6. COST ANALYSIS

42

6.1
C
ost of
manufacturing

and the components
…………………
..


……42

6.2
C
ost of rework

……………………………………………………
..
….…43


7. BENEFITS AND FUTURE DEVELOPMENT





44


8. REFERENCES










45












7


LIST OF FIGURES


Figure 1 Motion sequence for pick
-
and
-
place device

................................
..................

16

Figure 2 Types of Grippers

................................
..........

Error! Bookmark not defined.

Figure 3 Functions of suction cups.
...............................................
.....
....................
..
17

Figure 4
Types of suction cups..............................
....................
...............
..
............
19


Figure 5 Transfer device for flat work pieces..............
.........
........
...........23


Figure 6 Linear unit with two
cylinders..................................
.24


Figure 7 Overhead swivel motion feed mechanism........................................
25


Figure 8 Feeding a machine from two magazines
..
.........................................
....26

Figure 9 Rotating arm using two cylinders.........................................................

Figure 10
.

Assembly...............................................................................


Figure 11 Circuit
d
iagram..................................................................


Figure 12 Force conditions with suction cups................................................


Figure 13 Cycle of operations..............................
.................

Figure 14 Forces on the Assembly...........................................................

Figure 15 Force analysis of the bearing........................................

Figure 16 Welded joint.........................................
...................................


Figure 17 Assembly Drawings......................................................................













8


LIST OF PHOTOGRAPHS


Photograph.1
Main Cylinder

................................
................................
........................

34

Photograph.2 3/2 DCV
................................
................................
................................
.

34

Photograph.3 Proxymity Sensor

................................
................................
..................

34

Photograph.4 2/2 DCV
................................
................................
................................
.

34

Photograph.5 Suction Cup

................................
................................
...........................

3
4

Photograph.6 PU Tube

................................
................................
................................
.

34

Photograph.7 Assembly

................................
................................
...............................

35





















9


LIST OF TABLES




























10


1. INTRODUCTION


1.1 Company Profile:

Art Rubber
Industries Pvt. Ltd

Art Rubber Industries Pvt. Ltd, H1

Ambad, Nashik.



Art rubber is a specialized agency in the field of tyre tube manufacturing with an
ISO/TS 16949 Certified company. It is located in a prime industrial area of MIDC
Nashik. The company
was incorporated in the year 1995. What started as a small
enterprise with only one staff member, 6 workers and with a turnover of Rs

XX

has
today grown into an organization with a total strength of 70 members and a turnover
of
Rs XX

servicing both nationa
l and international clients.




Vision



Art rubber industries limited, emerging as the leader in its existing line of
business in the country.



Leadership in our respective product range



Move up the value chain and provide our customers ready to use products



Be the preferred supplier in our product range



The company builds up its own brand equity with its operational horizon
widened. The company achieves efficienc
y level for others to benchmark
against.





Mission



Art rubber industries limited achieves and
maintain No. 1 position among the
tube vendors for CEAT

Tyres

and exporting its product.



Harness all the company’s assets


men, machine, material & money


to
continuously enhance stakeholder’s satisfaction.



Continuously improve product and process parame
ters and performance.



Continuously improve cost effectiveness of every organizational activity.


11


1.2 Manufacturing process of butyl tubes:




Natural rubber is the raw material for manufacturing butyl tubes. Specified
chemicals like sulphur are mixed with na
tural rubber in quantities specified by the
customer.



In this plant at
Ambad, Nashik

a total of 18 different types of tubes are
manufactured.



These include tyre tubes for cars, buses, trucks, scooters, autos, etc. After proper
mixing of chemicals to give the tubes the required strength, the rubber is filtered
and then weighed and is
sent to a mill where further mixing takes place.



After mixing t
he rubber is passed through an extruder which converts rubber into
tubes.



A patch is placed where valve is to be fitted. This is done by manually measuring
the length of the tube.



After patching, the tubes are passed through a special powder. Then the tube
s of
required length are cut by an automatic cutting machine.



After cutting valves are fitted to the place where patches were placed.



Both ends of the tubes are the joined by heating.



Steam is filled in the tubes.



The tubes are then evacuated by vacuuming
them.



The tubes are then checked manual inspection for defects.



Valve pins are inserted in the valves and the tubes are sent for packing.


1.3

Need of Automation
:


1. Patching is done manually so distance between two patches is not correct and
generally workers keep this distance slightly more. Automation is
necessary

to reduce
rework
.

2. To reduce workers fatigue due to repeated work.

3. To increase productivi
ty and

reduce time for processing a batch
.



12


1.4
. Objectives:



The

main objective of machine

is to automate the process of patching thereby
increasing productivity. Following are some of the other objectives:


1)

Increasing P
roductivity:

About 60mm rubber is left
for rework

per tube
,

this wastage increases processing time
an
d cost
. Hence we can increase productivity by reducing wastage.


2)

Reducing Human Effort

Fatigue is caused due to repeated measurement of patching distance so automation
will reduce human effort.


3)

Less Operational Cost


The patching machine will reduce the rework required and hence reduce rework cost.


4)

Economic Criteria

The cost of system should be low and also the operating and maintenance cost should
be within economical limits.

The payback period should be less.



1.5


Design Requirements
:





Pick patch one at a time.



Patch should stick to the tube.



Machine should be able to patch every type of tube.



Machine should be e
asy to operate.






13


2. LITERATURE SURVEY

2.1 Automation:

Automation is defined as a technology that is concerned with the use of mechanical,
electronic, and computer
-
based systems in the operation and control of production.
This technology includes transfer lines, mechanized assembly machines,
feedback
control systems, and robots. There are three broad classes of industrial automat
ion:
fixed automation, program
mable automation, and flexible automation. Of these three
types, robotics coincides most closely with programmable automation. The robot
can
be programmed to move its arm through a sequence of motions in order to perform
some useful task. It will repeat that motion pattern over and over again until
reprogrammed to perform some other task. Hence the programming feature allows
robots to be us
ed for a variety of different industrial operations, many of which
involve the robot working together with other pieces of automated or semi

automated
equipment. These operations include machine loading and unloading,

spot welding,
and spray painting.


2.2

Pneumatic Controls:

The primary requirement of an automatic machine is to develop a control system
capable of functioning independently with or without direct human
participation. A

control system may be defined as an integrated complex device that govern
s or
regulates a process or an operation. Pneumatic control is one of the control devices
used in modern industries for automation and rationalization. Air energy is one of the
oldest known
forms

of potential energy and at the beginning of the second half
of this
century;

it has come as a unique source for rationalization and automation programme
of the modern industrial plant. Almost any mechanical task that we come across can
be achieved pneumatically. Compressed air, though used for most type of producti
on
processes, is at its best in assembly line, machine shop, foundry shop, wood and
timber processing shop, etc. to tackle the problems of work handling, feeding and
manipulating. However, it may well be said here that at its present
level of

development,
pneumatics can cater to a wide range of any possible industrial
requirement. It is only the designer’s imagination and ability to find out where
pneumatics can prove advantageous and hoe best it can be employed.

14


Pneumatic power may well be applied to its
fullest advantage in the following
industrial and technological fields:

Assembly

For screwing, press fitting, hammering,
riveting, etc.

Automatic Machines

Either full pneumatic or combination of
traditional & pneumatic or other energy
sources for holding,

gripping, feeding, &
other auxiliary application

Foundry Machinery

Full & semiautomatic moulding
machines, fettling, transporting, etc.

Packaging industries

Special machines for packing every kind
of product, folding, etc.

Food & beverage

For
bottling, wrapping, etc.

Table no.1

Some of the specific advantages in using pneumatic system are as follows.

1.

Are not subjected to overheating or sparking due to electrical faults.

2.

Are relatively unaffected by extreme conditions.

3.

Are not influenced by
stray electromagnetic fields and electrical interferences.

4.

Will safely tolerate considerable variations in supply pressure and still
function effectively.

5.

Can provide a positive holding power for long periods of time.


Air performs the work functions as we
ll as control function and does not require any
additional equipment to convert its energy into motive power.

One of the greatest problems in pneumatics is the difficulty of miniaturization. That is
the reason why microprocessors are
favoured

for mobile eq
uipment in non
-
inflammable areas. Also, the complex plumbing required with many traditional
pneumatic systems can be off
-
putting to the designer as well as introducing potential
unreliability into the system. Of course, in this respect, manifolding of valv
es has
reduced the pipe work and hence the number of potential leakage points.

15


2.3
Principle of circuit design for automatic system.

Each pneumatic control consist
s

of control chain


A control chain of several control
members. These members could be class
ified as:

1. Signalling

Members
-

They delivers when force is exerted on them. This force could
be a manual or pressure force. Some
examples are

push
button,

limit
switch,

pressure
switch, etc.

2. Controlling Members
-

The main function of controlling
members is to combine the
various signals to the combine logic so that the same could be used to change the
position of positioning members as per the preconceived logic. Some examples of
controlling members are auxiliary contactors logic gates, etc.

3.
Positioning Members
-

The positioning members are
ultimately responsible for
changi
ng the position of the driving member by controlling the flow of
energy. Some

examples are direction control valves main contactors
, etc
.

4. Driving Members
-
They are the ener
gy converters in the pneumatic system. They
change the position of the working unit. Common examples are cylinder, pneumatic
motor,

etc. the driving unit ultimately controls working unit such as spindle unit, feed
unit, clamping unit, etc.

2.4

Basic Princi
ple of pick and place devices


This class of device includes two
-
axis motion with a fixed sequence, used to
handle objects,

in particular work pieces of small and medium size and mass.

Pick and Place device have fixed motion sequences, paths or

angles which can be
changed only by replacing components or re
-
adjusting these.


There are a number of other terms which mean the same thing as “Pick and
place device “,such as “Loader”,

”Fee
der”,

”Non

Servo Robots” or “fixed
-
sequence
robot”(Japan).Because of the hard impact which devices of kinds used to produce at
end positions, American engineers have also christened them “bang
-
bang robots”.
“Pick
-
and
-
place device” is nonetheless a good term, reflecting the fact that an object
is lif
ted and set down at a defined point. A typical motion sequence for pick
-
and
-
place
device is shown in fig.

16



Figure
1

Motion sequence for pick
-
and
-
place device

The following motion operations take place:

-
Working gripping (pick
-
up)

-
Work piece movement (transfer)


-
Opening of gripper, set down of work piece (placing)


2.
5

Gripper design considerations
:

The design of grippers is governed by the load required to achieve a secure holding
function
. The forces and torque values during a
handling sequence may vary as a
function of location, direction of motion and time. Vibration may also be involved.
Grippers and gripped objects must therefore always be considered as systems. Force
transmission is governed by the following factors




Physi
cal arrangement of the gripper in relation to the handling device



Resulting force, influenced by mass, inertia and centrifugal force, among other
things



Geometry of gripped object or gripping area



Design of gripper jaws with regard to the force components
absorbed by
positive locking and force
-
locking connections



Surface properties of work pieces and gripper jaws



Environmental influences such as dust, drilling emulsions, temperature and
vibration

17


2.
6

Suction cups:

Suction cups are a popular and simple solution for repetitive gripping application of
the “pick up, move, set down” type, provided that the
work pieces

in question have
flat non
-
porous faces. A further
advantage

is that suction cup can used with non
-
magnet
ic material such as glass, ceramic and wood.


We can make a general distinction between two types of suction cup applications:

Large suction area and small pressure difference:

T
he advantage here is that the holding force can be build up quickly and that

there is
little deformation of soft flexible work pieces. In case of slightly porous material, air
is not drawn through these.

Small suction area and large pressure difference:

This means high gripping forces as the suction cups used become smaller. This
allows
the clearance radius of manipulators to be made smaller,

which is often decisive factor
when space is limited
.


Figure
3

Functions of suction cups

[1.Vacuum line 2.Pressure Switch 3.
Angular
freedom 4.Quick exhausts

5.Vertical freedom 6.
Quick inter
changeability 7. Generation of holding force 8
.
Work piece

contact sensor

18



Fig 3
shows the most importance function of suction cup. Not all these functions will
be used in every application.

Suction
cups are suitable for large number of handling
operations, such as sorting,
feeding, clamping, turning and stacking, and are used as gripers with lifting devices,
balancers, feed device, stacking systems, packing machines and production lines.
Suctions cups are particularly convenient when work

pieces
have the following
features.



Awkward dimensions



Susceptible to deformation



Non
-
magnetic



Surfaces
-
sensitive to scratching (ground, polished, painted)



Undulating but non
-
porous surfaces.














19


2.
7

S
uction cup shapes & design


There are different
shapes & designs of suction cups:

Figure
4

Types of Suction Cup


[
1. Bellows suction cup 2.Flat suction sups 3.Deep suction cups 4.
Ribbed suction cup 5. Profile suction cup
6.Suction cup with cellular rubber seal 7. Lifting Suction cup

8.Oval suction cup

with metal plate 9.Duoble suction
cup 10. Double lip suction cup 11.Self adhering suction cup]


1. Bellows

suction cup
:

Suitable for slightly curved, inclined, easily deformable & uneven surfaces. Provides
a slight lifting motion; compensates for height
differences, can have up to 6.5 pleats.
Small diameter of this type is suitable for thin materials, Bellows suction cups or
external support spring to provide additional rigidity.

2. Flat

suction cups
:

In general terms universal suction cups, suitable for
non
-
porous flat & slightly curved
surfaces, able to transmit high vertical forces.

3. Deep suction cups
:

Good adaptation to round surfaces & profile suctions. Should not be used for flat
surfaces, since rigidity is low & wear is rapid.

4. Ribbed suction c
ups
:

Suitable for flat & unstable surfaces. The ribs across the mouth of cups
p
revent thin
materials from being drawn into the cups &

make these more resistant to lateral
deformation. This type of suction cup is also useful for use with vertical surfaces,
since the ribs provide increased friction when the work piece is in contact with these
20


after being picked up. Since the lips of sucti
on cups do not flex very much, virtually
100% of effective suction area is maintained. The more rigid design means on the one
hand that suction cups can be produced in larger sizes without a support plate but on
the other means that the suction cups cannot

grip objects with any pronounce curve.

5. S
uction cups with cellular rubber seal
:

These provide a good seal with uneven and heavily textured surfaces, such as
corrugated sheet metal, textured glass, concrete slabs, fire
-
proof bricks etc. not good
for appl
ications with vertical work pieces.

6.
Oval suction cups
:

Good for long, narrow or slightly curved work pieces. Can be used for “spiders”
(large grippers with a large number of suction cups spread over their area) in the
automobile industry: typical featu
res are metal base
-
plates and narrow flexible sealing
lips.

7.
Double lip suction cups
:

A seal is provided by a combination of sealing lip and a sealing ring. This gives great
elasticity. When operated at closed to maximum load, these suction cups may
alt
ernate in a relatively uncontrolled way between their inner and outer sealing lips.

8.
Self
-
adhering suction cups:

These are not connected to an external vacuum source. A vacuum is created by
suction cup itself as it presses against a
work piece
. There is

no compensation for
leakage losses. A hand
-
leaver valve is used to break the vacuum. As the cup is
pressed against the a

work piece
, its volume is reduced, causing air to be displaced.
As the cup springs back into shape, a vacuum is created under the
suction cup. The
level of this vacuum is, however, hard to define, since the deformation force can vary
widely.

9.
Lifting suction cups
:

Combination of a piston system and a suction cup. Once a work

piece has adhered to
the suction cup, it rises away from
the work

piece stack. A lifting suction cup can
therefore make a separate lifting axis unnecessary. Stroke of up to 50 mm are
normally available. This type of suction cup is used to handle cut cardboard, paper,
foil pieces, thin sheet metal, packaging item
, etc.

21


3. Proposed Solutions:


3.1

Printer mechanism

Process
-

As like printer selects one page at a time for further printing we decided to
use the same principle in our
project. As

shown in fig in this printer rotary vacuum
cup is used to pick one patch form stack of
patches. It

will pass this patch on
continuously rotating belt. Belt is rotated using servomotors for some specific time.




First patch is placed manually by worker.



Sen
sor will sense this patch and activate the rotary vacuum cup as well as
servomotors



Vacuum cup will pick one patch and will place on belt.



Belt will carry this patch and will pass on tube.



as per our patching distance required we will adjust the sensor pos
ition and
speed of patch travel on belt.















22


3.2

Transfer device for flat work pieces one cylinder and suction grippers.



Figure 5 Transfer device for flat work pieces


Figure shows a transfer device which picks up plates by means of suction
cups and transfer this from one conveyor section to another. The coupling
rods are able to swing through between the roller conveyor sections.
Suction cups pick up the flat work piece. There is plenty of time for the
transfer operation. The rotary drive is

require
d

to turn slowly and evenly.
The angle of rotation is less than 180
o
. It is not easy to produce slow
speeds with compressed air. It is therefore not sufficient in this case to
use a one
-
way flow control valve for the cylinder exhaust air. A better
solution is to use two double one
-
way flow control valves.





23


3.3 Linear unit with two cylinders and suction grippers.



Figure
6
Linear unit with two cylinder



DESCRIPTION:

The figure shows a system which has a side opening and can accept all the necessary
cables and pneumatic tubing. This system can be used with a number of optional inlet
openings together with cable ducts and hardware fittings.



Two pneumatic cylinders are
used in this mechanism. One is horizontal and
other is vertical.



Vacuum cup is used to pick up and placing the patch.

24


3.4
Overhead swivel motion feed machine
:

Figure
7

Overhead swivel motion feed machine

[
1.Optical sensor 2.Lifting table 3.Swivel unit 4.M
achine Tool 5.Indexed conveyor belt]

Fig.
7
shows the feed of a machine tool by means of an overhead swivel
motion. T
his
operation is advisable only for
relatively light
work pieces
. During transfer, the swivel
arm plunges between the indexed conveyor belts, passing on either the inside or
outside. The conveyor belt system must be configured to allow this. The feed device
in this example is a direct local replacement for the human op
erator.

3.5
Feeding machine from two magazines:

In case of machines with continuous throughput,
the

problem is occasionally
encountered that a pick and place device is not able to deliver the required
performance. One way out would be alterna
te feed from
2 magazines (
Fig.8)


The machine tool has an
in feed

conveyor belt onto which the work pieces need to be
placed. This method, too, avoids idle motions, since while one work piece is being set
down, the other vertical unit operates in parallel to prepare th
e next work piece. The
cost of motion however is modest
-

just 3 linear
units are required. With
larger work

pieces, the distance and t
hus the linear strokes are also
larger.


Figure
8
Feeding a machine from two magazines

25


3.4

Rotary arm using 2 cylinders


Figure
9

Rotary arm using 2 cylinders

DESCRIPTION:



Rotary arm system uses two cylinders, one for horizontal motion and other for
vertical pick up of patch.



Horizontal cylinder forces the link to give oscillating motion
,
while the
vertical cylinder is used

for lifting and placing patch.



Vacuum cup is used to pick up and placing the patch.



Bearing is used to support vertical shaft and provide rotary motion to arm.



A link is welded on vertical shaft at one end and another end is pinned to
piston of horizontal

cylinder.


After considering all the ideas that we had initially proposed, we arrived
at a final
mech
anism that would work

to perform the required tasks of picking and placing the
patch. The robot consists of two cylinders, one for horizontal motion and other for
vertical pick up of patch.

The

tasks to
be performed are:

1. Lifting the patch.

2. Planar transfer of patch up

to the conveyor.

3.

Placing of patch on tubes.

26


4.
CIRCUIT DESIGN AND SELECTION OF COMPONENTS


4.1 OBJECTIVE
:
The functional requirements of the machine are as follows:

1.

Pick up patch one at a time.

2.

It should be able to place it accurately on all sizes of t
ubes

3.

Patch should stick to the tube


With these objectives in mind the following design was chosen:

We used a vertical cylinder attached with a suction cup which performs the picking
and placing of the patch. The vertical cylinder is fully adjustable on a
horizontal ar
m.
The suction cup is adjustable or

positioned

according to the size of the tube.

The manipulator (vertical cylinder & suction cup) is moved from the pick position, to
the place position, using a pneumatic cylinder which turns the horizontal
arm through
90

.

The manipulator presses the patch against the tube to stick it on the tube.

The sequence of motio
n



Figure
10

Assembly


Cylinder to
rotate arm





Slider

Horizontal arm

Vertical cylinder

Suction Cup

27




Figure
11
Electro
-
Pneumatic Circuit

4.2 Components
:

1.

Infrared sensor

2.

Timer 1

3.

4/2 Solenoid operated spring return DCV

4.

3/2 Solenoid operated spring return DCV

5.

Main Cylinder (Double acting)

6.

Proximity sensor 1

7.

Proximity sensor 2

8.

Small cylinder (Single acting

spring ret
urn)

9.

Timer 2

10.

Timer 3

11.

Vacuum Cup

12.

2/2 Solenoid Operated DCV

13.

Vacuum pump

14.

FRL Unit

15.

Compressor

28


4.3
WORKING:


The Arrangement of Electro
-
Pneumatic Circuit is as shown in fig.
11


1.

When yellow patch is sensed by the pho
to sensor it gives signal to SOV

1 and
also to timer 1


2.

SOV

1 actuates the horizontal cylinder to
extend

at the same time
,

timer starts
counting.


3.

W
hen cylinder extends completely
,

proximity
sensor (LS
-
2) gives signal to
SOV
-
2 and timer
-
2.


4.

SOV
-
2 actuat
es the small cylinder to extend
, at

the same time the timer
-
2
starts counting.


5.

Proxy. Sensor
-
2(PS
-
2) also signal
s
Timer
-
3 and SOV
-
3 to actuate and stop the
vacuum supply.


6.

Time is set on the timers so that proper sequence of operation is achieved.


7.

Firstly, timer
-
3 stops

signalling

SOV
-
3 t
o start the vacuum supply again.


8.

Secondly, Timer
-
2 stops
signalling

to SOV
-
2 to retract small cylinder.


9.

A
t last Timer
-
1 stops;
signalling

SOV
-
1 to retract horizontal cylinder.


10.

When the horizontal cylinder is retracted PS
-
1 will signal to SOV
-
2 and
Timer
-
2 start counting.


11.

After timer 2 stops counting it signals SOV
-
2 to retract

the vertical cylinder.


12.

Above cycle repeat
s

the same procedure for every patching.










29


4.4
SELECTION OF COMPONENTS


4.4.1
Selection of suction cup

The purpose of this is

to define the vacuum in the suction chamber and the size of the
suction area in such a way that these compensate reliably for all the forces occurring
during manipulation operations. In the case of slow motions, such as the movement of
suction h3eld work
pieces on a balancer, it is sufficient to consider static forces. With
high speed motions dynamic forces must also be considered. As a general principle,

F
= (
p
o
-

p
u
).A.n.

.z.




………………………………………………………………
(i)

The terms used in the above equation are:

A =
Theoretical area of suction cup.

F = Working Load; weight force of gripper object.

n = coefficient of deformation. As the patch is flexible the co ef
ficient of deformation
of the cup

is 1.


P
0

= Atmospheric pressure;


P
u
= pressure in seal suction chamber
.

S = Safety factor to guard against detachment of work piece. A state

of equilibrium is
not
sufficient
-

the gripped object must be pressed against the suction cup with a
certain force.


(S= 2 to 3)


z = Number of suction cups.




= Efficiency of system, including leakage allowance




30



Figure 12 Force conditions with suction cup

F = weight = 0.5 gram

P
o
= 1.013 bar

A = 706.85 mm
2

(For a cup of diameter 30mm)

n = 1



= 0.95

z= 1

S = 2

Using equation (i)

We have,

Suction pressure = P
u

= 1.01285 bar


Flat suction cups are suitable for non
-
porous flat and slightly curved surfaces and are able to
transmit high vertical forces

Hence we select
flat suction cup

for the patch picking application











31


4.4.2
Selection of
main cylinder

The plant produces about 600 tubes per hour. Hence, 1 tube is made in 6 seconds. So,
the machine should be ready to apply a new patch every 4 seconds. That means the
operation of picking
-
placing and again picking should be completed in 4 seco
nds. The
whole process can be divided into following operations:


Figure 13 Cycle of operations


After receiving the signal,
we have 4 seconds to rotate
-
place
-
rotate
-
pickup. Hence for
one rotation through 90

,
we have 1 second.

Hence



radians per second =







n = 15rpm


The length of link attached to the rotating arm is 100mm = 0.1m. Hence velocity of
piston of main cylinder will be

v = r



= 0.1*





= 0.157 m/s



The load on the cylinder is due to inertia of the system, so torque will be given by


= I


This torque is equal to

(Force exerted by the cylinder)* (Length of crank)

……………………………….
(i
i
)


Receive
signal

Rotate

Place

Rotate
again

Pick up

32


The moment of inertia of the system about axis of rotation is I= 12.
64 Kgm
2
.

The angular acceleration is



rad/sec
2

Hence


= 19.86 Nm



From equation (i
i
)

Force exerted by the cylinder =








We take length of crank = 100mm=0.1m



F=








= 198.6 N


From the manufacturers catalogue w
e select a cylinder of piston/bore diameter 50mm
and rod diameter 15mm.


Pressure, P =





=












= 101145.912 N/m
2

= 1.01145 bar


Flow rate = A
p
*v = 1.9635*10
-
3

*0.157 = 3.082*10
-
4

m
3
/sec


The maximum working pressure of the cylinder as
given by manufacturer is 7 kg/cm
2


Our selection is safe.


4.4.3
Selection of vertical cylinder:



Our requirement was a cylinder with small stroke which is suitable to press the patch
on the tube as well as to pick up patches from a stack of papers about

25mm thick.

Hence we choose a cylinder with a stroke of 25mm.



4.4.4
Selection of direction control valves:


1.

For Vacuum On
-
Off:

We have used 2/2 valve which is suitable for working pressure of 0
-
7 kg/cm
2
.

2.

For main cylinder:

A 4/2 DCV is used which is
suitable for working pressure of 0
-
7 kg/cm
2
.

3.

For Vertical cylinder:

A spring return 3/2 DCV is used which is suitable for working pressure of

0
-
7 kg/cm
2
.

The air conveying pipes used are PU

tubes of 8mm diameter and all 1/4” push in
fittings.




33



Photograp
hs of the components:




Photograph 1. Main cylinder


Photograph 2.

3/2 DCV




Photograph 3
. Pr
oximity Sensor Photograph 4.

2/2 DCV




Photograph 5.

Suction Cup


Photograph6.
Fig.

PU Tube





34


Photograph

of the assembly:





Photograph 7. Assembly












35


5. Design and analysis of the machine structure

5.1

Analysis of Shaft


Figure
13
Forces on the assembly

The shaft is made of plain carbon steel 45C8 and the
tensile yield strength is 380
N/
mm
2.
The weight W=65.4955 N of the arm and the vertical cylinder acts at a
distance of 408.7mm from the axis of the shaft. A force F
1
=196.35 N acts as shown in
the figure. F
1

is the force generated by the main cylinder.

Acco
rding to maximum shear stress theory

S
sy
=0.5S
yt
=0.5(380) =190N/mm
2

The permissible shear stress


will be



=





=



=95 N/mm
2
……………………………………………...

(
i
ii
)


The stresses are critical at point A, which is subjected to a combined bending and
torsion moment




M
b
= 408.701 (65.4955)


=26728.967 N
-
mm

W

F
1

A

36



M
t
= 100(196.53)


= 19653 N/mm
2




The shaft has a
circular cross section

and is hollow, Thus,




I =
















b
=






=



















……………………………………………………

(
i
v
)



J=

















=





=



=




















………………………………………………….(v
)



max

= [









]* 10
3
























95 N/mm
2
……………………...(
iv)





We take a hollow shaft of external diameter d
0
=20 mm and internal diameter d
i
=16
mm



we have





















=
17.33 N/mm
2

≤ 95 N/mm
2

Hence the shear stress on the shaft is less than the permissible shear stress. Thus our
assumption is correct and the
design is safe
.






3
7


5.2

Design of bearing




Figure
14

Forces on the bearing


Forces acting in the vertical plane are:


W= Weight of the arm =
65.4955 N

R
v
=

Vertical reaction from the bearing





F
x
=0
……………………………………………………………………….
(i)


F
y
=0
………………………………………………………………………

(ii)




R
v
= W = 65.4955 N



Forces
acting in the horizontal plane are:

F = Force generated by the main cylinder

R
H

=

Horizontal reaction from the bearing




F
x
=0
………………………………………………………………………

(i)


F
y
=0
……………………………………………………………………….

(ii)

Bearing

W

F

R
v

R
h

38




R
H

= F= 196.35 N


F
R1

=










= 206.98 N



P = F
R1
= 206.98 N
…………………………………………………………………

(iii)


As the machine is used continuously for about 14 hours a day we take recommended
life of bearing as 30000hrs.




[Ref. V.B Bhandari Section15.8]


L =










=











=27
million revolutions


The dynamic load capacity


C = P* L
(1/3)
(Load factor)


Load factor = 1.2 (for low impact machines)


C= 206.98*27
(1/3)
*1.2


= 745.128 N


Hence,


We select ball bearing of


d = 20mm;


D= 32;


B=7


Designation of bearing 61804




39


5.3
Analysis of welded joint

The circular shaft is welded to the arm by means of a fillet weld as shown in the
figure. The permissible shear stress in the weld is limited to 95 N/mm
2
. The joint is
subjected to bending moment due to weight of the assembly. The
weight acts
eccentrically at a distance of 408.7 mm. The weight of the assembly is W= 65.4955N.

`


Figure 15 Welded joint


The primary shear stress in the weld is given by



=



=




=









=





N/mm
2
……………………………………...
(i)

Consider an elemental section of area


as shown in the Fig. It is located at an angle


and subtends an angle d



Now,



W

Welded
joint

Y= r sin




t
t




d


40




= r d


. t

And,


(I
xx
) =

Ay
2


=(r

d
.t)(r sin

)
2
0


= tr
3
sin
2


d


The moment of inertia of an annular fillet weld is obtained by integration. Thus,


I
xx


= 2















= 2tr
3












= 2tr
3














= 2tr
3




Or I
xx

=

tr
3


For the above welded joint,


I
xx

=


*
(t)
*
(10
3
) mm
4




b

=










=



















=






N/mm
2

The maximum shear stress in the weld is given by
,






=















=



















41





=






N/mm
2

Since
permissible shear stress in the weld is 95 N/mm
2
,










t = 0.447 mm

And h=



























1 mm


Welding has been done for more than 2 mm thickness.

Hence the welded joint is
safe.
















42


5.4 Assembly Drawings


Elevation


Plan


Figure
16
Assembly Drawings


43


6. COST ANALYSIS

6.1

Cost of manufacturing and the
components:



Considering life of all components to be 1 year


Total one time investment project cost = Rs. 21
,
290

Fixed cost/month



Total one time investment project cost/month=Rs. 1775



Electricity cost/month=Rs.2000






Variable cost/month



Maintenance cost /month=Rs.3000

Total cost of project /month

= Fixed cost/month + Variable cost/month








= 1775+2000+3000

=

Rs. 6775



Conventional /Manual process
cost
=
Rs. 8000

Savings / month






=

Rs.8000


6775

= Rs
. 1225




SR.NO

MATERIALS REQUIRD

COST(IN
R
UPEES)

1.


Metallic arm

150

2.


Cylinders



Small cylinder

Stroke
-

100mm

Bore


32mm



Big cylinder

Stroke
-

300mm

Bore


100mm



840



3900

3.


Suction cup (FESTO)

700

4.


Electrical equipments



Proximity switch (2 no.)



ON/OFF Timers (4 no.)


350*2 = 700

2200*4 = 8800

5.


Bearing (inner dia. 30mm)

300

6.


Photo /colour /patch
sensor

1500

7.


Direction control valve



3/2 DCV (FEST
O TYPE) (1 no.)



4/2 DCV (FEST
O TYPE) (1 no.)



Vacuum controlling DCV


1200

1200

2000

44


6.2 Cost of rework:


1.
Amount of rubber used


=

750 kg/hr

2.
Number of hours plant works

=

14

hr

3.
Amount of rubber put to rework

=

60 g/kg



Total amount for

rework


=









kg =630

kg/day


Load calculation:

1. Cooling water pump motor rating

=

3

hp

2. Dryer rating

=

1
3

hp

3. Conveyor motor ratings:

i.

Overhead motors

=

3* 1

hp

= 3
hp

ii.

Motors for conveyor 3 and 4

=

.
2* 3

hp

= 6

hp

4. Extruder Rating


=

60
hp

5.
Mixer Rating



=

60 hp



Total load on the system

=

145 hp = 108

kW

6.
No. of units per hour



=


108

kW

7. Electricity Cost

=

Rs.8/
kW


630 kg of
rework takes approximately 0.84 hours

Hence No. of units utilized = 108.126*0.84 = 90.825

8. Cost of 90.825 units


= 90.825*8


= Rs 726



Cost per month
= 726.606 *30


= Rs.21,798


Hence cost savings for
zero rework = Rs 21,798
/ month



As the cost savings is as mentioned above, and cost of the machine made is

Rs

21,290. Hence the pay
-
back
period is of 1 month.

This means that the
investment made on installing an automatic patching

machine can be recovered within
1 month. The installation of the machine saves rework of about 1 hour every day.


45


7
. BENEFIT AND FU
TURE
DEVELOPMENT


The main benefit of this project is to save time, money and to make

beneficiary

improvements in the
manufacturing process line.

The pick and place pneumatic
system will replace a worker performing

the pick and place operation who, on an
average can work continuously for not

more than 8

hours. The system will be able to
perform the operation for as long

a
s it is required without any interruption thereby
providing continuous flow in

the process and also will be consistent in its actions.


The initial cost of the machine may be high but this will easily be

compensated by the
amount being spent on the two wor
kers who work for

8

hours each on 2 shifts in
compan
y.
Maintenance

cost is almost negligible

and the life of the system and its
co
mponents is also high. Hence,
proving

this system beneficial.

The pick and place
system that we have made is very basic when

compared to the state
-
of
-
the
-
art pick
and place machines and robots available.

The patching can be done still faster by increasing the no. of suction cups
i.e.

using
two suction cups at both ends of the horizontal arm will result in quick operation and
the

cycle time will be reduced












46


8
. REFERENCES


1.
FRANK

EBEL,

PETER CROSER ‘Basic Level Pneumatics’, FESTO

reference

catalogue

2. FESTO CONTROLS (P) LTD., Pneumatic Catalogue (2001 edition)

3. ANDREW PARR, Hydraulics and Pneumatics, JAICO
publications,2002

4.
MARK.D.OVIATT,
RICHARD.K.MILLER.

Industrial Pneumatic

systems, The


Fairmont Press Inc. (1971)

5. SULLIVAN JAMES A, Fluid Power Theory and Applications, Reston


Publishing Company Inc. (1975)

6. PESSEN, DAVID.W, Industrial Automa
tion, John Wiley and Sons


(1990)

7. LEIBFRITZ K.W.,
‘Pneumatic

Systems’, 1976 edition

8. FESTO, ‘pick and place station’ manual (2004)