ABSTRACT
Generally
in printing machine is operated by manual work by means of electric power
source, this taken more time for manufacturing a batch of cards. This
inconvenience can be over comed by utilizing our coding unit. Our project is
about Automatic pneumatic printing press that it may called as Pneumatic coding
unit. This machine is used for printing visiting cards, Identity cards etc…by
applying pneumatic forces. The importance of doing this project is it avoid
screen printing, and also it reduce the time consumption. Here, we are using
pneumatic method, as the name implish pneumatic system typically uses air
(rather than gas) as the fluid medium is air because it is safe, low cost,
readily available fluid. This machine can be used for mass production. This machine
is very easy to replace the die, for feeding the cards.
TABLE
OF CONENTS
CHAPTER TITLE
PAGE
NO.
NO.
ABSTRACT
4
LIST OF FIGURES 8
1 INTRODUCTION
10
2
CONSTRUCTION 12
3 PRINCIPLES OF PNEUMATIC CONTROL 14
3.1
Basic of Pneumatic circuit 14
3.2
Pneumatic circuit diagram 14
3.3
Manually operated pneumatic components
15
3.4
Basic principles
16
3.5
The setting circuit diagram 17
3.6
The basic rules of circuit diagram 18
3.7
Different kinds basic circuits 19
3.8
Flow amplification
20
3.9
Signal inversion
20
3.10
Memory function
21
3.11
Delay function
21
3.12
On - signal delay
22
3.13
OFF – signal delay 22
3.14
Single acting cylinder control 23
3.15
Direct control and speed control 23
3.16
OR Function
24
3.17
AND Function
24
3.18
NOT Function
25
3.19
Double acting cylinder 25
3.19.1
Direct control
25
3.19.2Single
control 26
3.20
Transport system 26
3.21Vehicle
door operating system
27
4 BLOCK
DIARAM
28
5 COMPONENTS 29
5.1 Major components 29
5.2 Basic side plate 30
5.3 Guide and slide
30
5.4 Sliding block
30
5.5 Side and link
plate
31
5.6 Ink tray steno
pad
31
5.7 Cylinder block 31
5.8 Food operating
valve
31
5.9 Cylinder
32
5.10 Pressure gauge
32
5.11 FRL unit.
32
5.12Polyurethane tube
33
5.13 Flow control unit
33
5.14 Compressor
33
6
WORKING PRINCIPLE 35
7
ADVANTAGES
37
8
APPLICATIONS
40
9
SAFETY MEASURES WHEN USING PNEUMATIC
CONTROL SYSTEMS
42
10 CONCLUSION
44
11 REFERENCE
45
12 FURTHER MODIFICATION 46
LIST
OF FIGURES
FIGURES
PAGE NO.
Fig.1 Basic principles of pneumatic circuit
diagrams 16
Fig. 2
The setting of circuit diagrams 17
Fig. 3
The basic rules of circuit diagrams 18
Fig. 4
Different kinds of basic circuits 19
Fig. 5
Flow amplification
20
Fig. 6
Signal inversion
20
Fig. 7
Memory function
21
Fig.
8 Delay function 21
Fig. 9 ON-signal delay
22
Fig. 10 OFF-signal delay 22
Fig.11 Direct control and speed control of single acting cylinder 23
Fig. 12 OR Function
24
Fig. 13
AND Function
24
Fig. 14 NOT
Function
25
Fig. 15
Direct control of double acting cylinder 25
Fig. 16 Single
control of double acting cylinder 26
Fig. 17
Transport system 26
Fig.1 8
Vehicle door operating system 27
Fig.1 9
Original view of Double acting cylinder
31
Fig.20
Original view of polyurethane tube 33
Fig.21 Flow
control valve diagram
33
Fig.22
Compressor diagram
33
CHAPTER
1
INTRODUCTION
Ø Pneumatic
system use pressurizes air to transmit and control power.
Ø As
the name implies, pneumatic system typically is air (rather than some other) as the medium due to following
reasons.
Ø Air
is safe (it is particularly safe in environment where as electrical spark could ignite
leads from system component)
Ø Low cost
Ø Readily
available fluid
Ø Liquid exhibit greater inertia the gases
Ø Liquid exhibit greater viscosity gases
Ø It is less expensive then hydraulic system
Ø However,
because of the compressibility of air, it is impossible to obtain precise
controlled actual velocity of the system also precise positioning control is
not obtainable.
Ø By
applying the live smooth and steady against available loads, the air exhaust
from the actuator is normally metered here as pneumatic quite.
Ø Low
due to compressor design limitation(less than 250 Psi), hydraulically pressure
can be high as 10,000 Psi, Thus the pneumatic system are confined to low power
applications.
Ø Pneumatic
system can be readily to drive, rotary actuated as well as linear cylinder.
Ø The
pneumatic system are used in industrial applications such as stamping,
Drilling, Hoisting, Punching, Clamping, Assembling, riveting, handling
operations.
Ø Usually
hydraulic and pneumatic systems and equipment do not compete.
Ø They
are so dissimilar that there are few problems in selecting any of them that
cannot be readily resolved.
Ø Certainly,
availability is one of the important factors of selection but this may be
outweighed by other factors.
Ø In
numerous instances, for example, air is preferred to meet certain unalterable
conditions, that is, in “hot spots” where there is an open furnace or other
potential ignition hazard or in operations where motion is required at
extremely high speeds.
Ø It
is often found more efficient to use a combined circuit in which oil is used in
one part and air in another on the same machine or process.
CHAPTER 2
CONSTRUCTION
v In
pneumatic system, compressor will increase the pressure of a gas reducing its
volume as described by perfect gas law.
v The
pneumatic system normally use a large
centralized air compressor which is considered to be an infinite air
source similar to an electrical system where
it similarly plug in to an electrical outlet for electricity.
v In
this way, pressurized air can be piped from one sources to various location
throughout an entire industrial plant.
v The
compressed air is piped to each circuit through an air filter to remove
contaminants which might harm to closely fitting parts of pneumatic component
such as valves and cylinder.
v The
air is flow through a pressure which reduces the pressure to the desired level
for the particular circuit applications.
v Because
of air is not a good lubricant (contains above 20% of oxygen), pneumatic system
requires a lubricator to inject a very fine mist of oil in to the air
discharging from the pressure regulator.
v This
prevents of the closely fitting moving parts of pneumatic components.
v Free
air from the atmosphere contents varying amount of moisture.
v The
moisture can be harmful in that it can wash away lubricant and thus cause
excessive wear and corrosion.
v Hence
in some application an driers is needed to Remover this undesirable moisture.
v Since
pneumatic system exhausts directly in to the atmosphere, they are capable if
generating excessive noise.
v These
for , muffles are mounted on exhaust ports of air valves and actuator to
reduces noise and prevent operating personal from high speed airborne
particles.
CHAPTER 3
PRINCIPLES OF PNEUMATIC CONTROL
3.1
Pneumatic circuit
Pneumatic control systems can be
designed in the form of pneumatic circuits. A pneumatic Circuit is formed by
various pneumatic components, such as cylinders, directional control valves,
flow control valves, etc.
Pneumatic
circuits have the following functions:
v
To
control the injection and release of compressed air in the cylinders.
v
To
use one valve to control another valve.
3.2
Pneumatic circuit diagram
v A pneumatic
circuit diagram uses pneumatic symbols to describe its design. Some basic rules
must be followed when drawing pneumatic diagrams.
v A pneumatic
circuit diagram represents the circuit in static form and assumes there is no
Supply of pressure. The placement of the pneumatic components on the circuit
also follows this assumption.
v The pneumatic
symbol of a directional control valve is formed by one or more squares. The
Inlet and exhaust are drawn underneath the square, while the outlet is drawn on
the top. Each function of the valve (the position of the valve) shall be
represented by a square. If there are two or more functions, the squares should
be arranged horizontally3/2 directional control valve Fig 17 3/2
directional control valve (normally closed type) (normally closed type)
v Arrows are used
to indicate the flow direction of air current. If the external port is not
connected to the internal parts, the symbol is used. The symbol underneath the
square represents the air input, while the symbol represents the exhaust.
v The pneumatic
symbols of operational components should be drawn on the outside of the
squares. They can be divided into two classes: mechanical and manual
Technological Studies Pneumatic Systems
3.3
Manually operated pneumatic components
5. Pneumatic operation signal
pressure lines should be drawn on one side of the squares, while triangles are
used to represent the direction of air flow Pneumatic operation signal pressure
line
3.4
Basic principles
Shows some of the basic principles of drawing
pneumatic circuit diagrams, the
Numbers in the diagram correspond
to the following points:
Basic
principles of drawing pneumatic circuit diagrams
v
When
the manual switch is not operated, the spring will restore the valve to its
original position.
v
From
the position of the spring, one can deduce that the block is operating. The
other block will not operate until the switch is pushed.
v
Air
pressure exists along this line because it is connected to the source of
compressed air.
v
As
this cylinder cavity and piston rod are under the influence of pressure, the
piston rod is in its restored position.
v
The
rear cylinder cavity and this line are connected to the exhaust, where air is
released.
3.5
The setting of circuit diagrams
Power level, logic level
and signal input level
v When drawing a
complete circuit diagram, one should place the pneumatic components on
different levels and positions, so the
relations between the components can be expressed clearly.
v This is called
the setting of circuit diagrams. A circuit diagram is usually divided into
three levels:
v Power level,
logic level and signal input level.
3.6
The basic rules of circuit diagram setting are as follows:
v
In
a pneumatic circuit, the flow of energy is from the bottom to the top.
Therefore, the air supply unit should be put at the bottom left corner. The
work cycle should be drawn from left to right. The first operating cylinder
should be placed at the upper left corner.
v
Power
control valves should be drawn directly under the cylinder controlled by them,
forming a power unit.
v
Control
cylinders and operational valves (signal components) driven by power control
valves should be placed at the lower levels of the diagram.
v
Assistance
valves, such as those with logic functions (for example, memory, ‘AND’, ‘OR’,
‘NOT’, delayed), can be put between the pneumatic components And the power
control valves.
v
Use
the line which represents the connecting pipe to Connect the entire air supply
unit and the pneumatic components to complete the pneumatic circuit. Check
carefully the circuit and the logic of the operation before use to avoid any
accident.
3.7 Different kinds of basic circuits
v
Basic
circuit is a pneumatic circuit designed to perform basic tasks, such as flow
amplification, signal inversion, memory, delay, single acting cylinder control,
double acting cylinder control, etc.
3.8
Flow amplification
Cylinders with a large
capacity require a larger flow of air, which can be hazardous to users. It’s
unsafe to manually operate pneumatic directional control valves with large flow
capacity. Instead we should first operate manually a small control valve and
use it to operate the pneumatic control system with large flow capacity. This
is called flow amplification, which can greatly ensure the safety of the
operators. During operation, valves with large flow capacity should be placed
near the cylinder, while valves with smaller flow capacity should be placed on
control boards some distances away.
3.9
Signal inversion
The pneumatic diagram shows how directional control valves can be
switched.
When operating control valve
control valve will stop producing pressure output.
When
Control valve ceases
operation and is restored to its original position; control valve will
Resume its output. Therefore, at any given time, the pressure output of control
valve is the exact Opposite of that of control valve .Signal inversion system Technological
Studies Pneumatic Systems
3.10
Memory Function
Memory is a common basic
function. It can keep a component at a certain state
Permanently until there is a change
of signals. A memory function circuit. When control valve is operated
momentarily (that is, pressed for a short time), the output signal of the5/2
directional control valve will be set to ON. The signal will stay
that way until control valve is operated
momentarily and generates another signal to replace it, causing it to stay
permanently
at OFF.
3.11Delay
function
A pneumatic delay circuit can
delay the operating time of the next control valve. Its principle Of operation
involves the use of an orifice to slow down the flow of air and control the
time of Pneumatic operation. Delay functions can be divided into two classes:
ON-signal delay and OFF signal delay.
3.12
ON-signal delay
Circuit diagram of an ON-signal
delay circuit, which delays the output of the
Next control valve. When control
valve is operated, the one way flow control
valve will slowdown the flow of air, thus delaying the signal output of the
outlet of control valve (A), resulting in a persistent ON-signal.
The time when control valve will be restored
to its original position is not affected.
3.13
OFF-signal Delay
Circuit diagram of an OFF-signal
delay circuit, which delays the output of
The next control valve. This
circuit is similar to an ON-signal delay circuit. The only difference is that
the one way flow control valve is connected in the opposite direction.
Therefore, when control valve is operated, the outlet of control valve
(A) will continue to output signals.
However, when control valve is restored to its original position,
the release of air is slowed down by throne way flow control valve, resulting
in a persistent OFF-signal
3.14
Single acting cylinder control
Single acting cylinders can be
controlled manually. However, they can also be controlled by two or more
valves. This is called logic control. Examples of logic control include ‘OR’
function,’ AND’ function, ‘NOT’ function, etc.
3.15
Direct control and speed control
If a single acting cylinder is
connected to a manual 3/2 directional control valve, when the control valve is
operated, it will cause the cylinder to work (Fig. 28). Therefore, the circuit
allows the cylinder to be controlled manually.
Direct control of a single acting
cylinderThe only way to change the extension speed of the piston of a single
acting cylinder is torestrict the flow of air at the inlet and uses the spring
to determine the speed of retraction. Therefore one way flow control valve is
placed in the circuit to control the speed.
3.16 OR Function
The single acting cylinder in
Fig. 29 can be operated by two different circuits. Examples include manual
operation and relying on automatic circuit signals, that is, when either
control valve or control valve is operated, the
cylinder will work. Therefore, the circuit in possesses the OR function.
However, if the output of two 3/2 directional control valves are connected
through the port of a triode, the air current from control valve will be released
through the exhaust of
Control valve , and so the
cylinder will not work. This problem can be solved by connecting shuttle valve
to the port of the triode.
3.17AND
Function
Another name for an AND function
is interlock control. This means control is possible only when two conditions
are satisfied. A classic example is a pneumatic system that works only when its
safety door is closed and its manual control valve is operated. The flow
passage will open only when both control valves are operated. The circuit
diagram of an AND function circuit. The cylinder will work only when both valve
and are operated. Circuit diagram of an
AND function circuit Technological Studies Pneumatic Systems
3.18
NOT Function
Another name for a NOT function
is inverse control. In order to hold or lock an operating conveyor or a similar
machine, the cylinder must be locked until a signal for cancelling the lock is
received. Therefore, the signal for cancelling the lock should be operated by a
normally open type control valve. However, to cancel the lock, the same signal
must also cancel the locks on other devices, like the indication signal. Shows
how the normally closed type control valve can be used to cut off the normally
open type control valve and achieve the goal of changing the signal.
3.19Double
acting cylinder
3.19.1
Direct control
The only difference between a
single acting cylinder and a double acting cylinder is that double acting
cylinder uses a 5/2 directional control valve instead of a 3/2 directional
control valve . Usually, when a double acting cylinder is not operated, outlet
‘B’ and inlet ‘P’ will be connected. In this circuit, whenever the operation
button is pushed manually, the double acting cylinder will move back and forth
once. Circuit diagram of a double acting cylinder direct control circuit Technological
Studies Pneumatic Systems In order to control the speed in both directions,
flow control valves are connected to the inlet son both sides of the cylinder.
The direction of the flow control valve is opposite to that of the release of
air by the flow control valve of the single acting cylinder. Compared to the throttle
inlet, the flow control valve is tougher and more stable. Connecting the
circuit in this way allows the input of sufficient air pressure and energy to
drive the piston.
3.19.2
Single control
A cylinder always has to maintain
its position in a lot of situations, even after the Operational signal has
disappeared. This can be achieved by the use of a circuit that possesses the
memory function. As shown in the extension path of a double acting cylinder
inactivated by control valve, while retraction is governed by control valve.
Control valve, on the other hand, maintains the position of the cylinder by
maintaining its own position. Control valve will be changed only when one of
the manual control valves is pushed. If both control valves and
are operated at the same time,
control valve will be subject to the same pressure
and will remain in its original position. Circuit that maintains the position of a
double acting cylinder.
3.20
Transport system
When the button switch is pushed, the cylinder
will push one of the goods from the shelf onto the transfer belt. When the
button switch is released, the cylinder will retract automatically. Shows the circuit diagram of the transport
system.
3.21
Vehicle door operation system
Pneumatic systems can be used to
operate the doors of public vehicles. Assuming that the opening and closing of
the doors are controlled by two button switches ON and OFF. When the button
switch ON is pressed, the doors will open. When the button switch OFF is pushed,
the Doors will close. shows a pneumatic system that can be used to operate the
doors of Vehicle
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