Single action cylinder

.

1. 1







Examining the Operation of Single-Action
Front Spring Cylinder with 3/2 Button Spring
Button Spring Normally Closed Direction
Control Valve



Student Name: Rawa Abdullah Taha
Class: Fourth Group (A2)
Course Title: Control laboratory
Department: Mechanics and Mechatronics




College of Engineering
Salahaddin University - Erbil
Academic Year 2020 – 2021

2. 2
INTRODUCTION

the pneumatic system consists of the following main parts:
1- Air compressor
2- Pneumatic control valves
o Directional control valves
o Pressure control valves
o Flow control valve
3- Pneumatic actuators
o Single acting cylinders
o Double acting cylinders
o Motors

Single acting cylinder:
Single acting cylinder is an output device. The
function of the SAC is to convert the pressure
energy to a mechanical energy (linear motion).
In single acting cylinder, the forward stroke is
achieved by the compressed air, while the
backward stroke is achieved by the spring. Thus the single acting cylinder
produces the work in only one direction (forward
stroke).

Figure (2.1.a) shows the picture of the single acting
cylinder. Figure (2.1.b) shows the ISO symbol of the
single acting cylinder

3. 3
3/2 way directional control valve*
* 3/2 way directional control valve - Normally Closed (NC)

Way of operation: A 3/2-way valve has 3 ports
(1, 2 and 3) and 2 switching positions (before
operating and after operating). It’s represented
by the normal position. Normally closed
means that compressed air cannot flow
through the valve as shown in figure (2.2.a).
When the pushbutton is actuated the valve is
opened, thus allowing the air to flow from port
(1) to port (2).


Un-actuated In normally closed 3/2 way valve,
a spring-loaded disk seal blocks the air flow from
the air supply port (1) to the working port (2). The
working port (2) is connected with exhaust port
(3) as shown in Figure (2.3.a).
Actuated
Actuating this valve results in allowing the flow
from port (1) to port (2) and blocking the exhaust
port (3) as shown in figure (5.2.b)
Figure (2.3.c) shows the ISO symbol of 3/2 way
valve normally closed (N/C) and spring reset

4. 4
Advantages
• Switching without overlap
• Larger flow cross-section with shorter
actuation stroke
• Insensitive to dirt
• Long service life



3/2-Way Valve - Normally Open Position
Way of operation:
Way of operation: A 3/2-way valve has 3 ports (1,
2 and 3) and 2 switching positions (before
operating and after operating). It’s represented by
the normal position. Normally open which means
that compressed air flows through the valve as
shown in figure (3.2.a). When the pushbutton is
actuated the valve is closed, thus stopping the air
to flow from port (1) to port (2)
Un-actuated
In normally closed 3/2 way valve, a spring loaded disk blocks exhaust
port (3). The air supply port (1) is connected to the working port (2)
Actuated
Actuating this valve results in allowing the flow
from port (2) to port (3) and blocking the supply air
port (1)
Figure (2.4.b) shows the ISO symbol of 3/2 way
valve normally open (N/O) and spring reset.

5. 5
Advantages
• Switching without overlap
• Larger flow cross-section with shorter actuation stroke
• Insensitive to dirt
• Long service life

Valve actuators
The pneumatic directional control valves can be
actuated (operated) in several ways such as follows:
4.1 Manual actuators
Figure (2.5.a) shows (from left to right) three manual
actuation methods: manual, push button and foot
pedal
4.2 Mechanical actuators
Figure (2.5.b) shows (from left to right) two
mechanical actuation methods: roller and idle return
roller.
4.3 Electrical actuators
Figure (2.5.c) shows an example of electrical
actuation (solenoid valve)
4.4 Pneumatic actuators
Figure (2.5.d) shows an example of pneumatic
(pressure) actuation

6. 6
Control Valve
Thia valve is also known as directional control valves, the foremost
function of a pneumatic valve is to switch airflow. These valves are
capable to maintain the pressure. The range of pneumatic valves is vast
and there are many categories of pneumatic valves. Pneumatic valves are
categorized according to their style, type, design principle, type of
operation, function, size, and application. The pneumatic valve can do the
simplest function of switching a single flow path on and off, to the
exacting proportional control of pressure and flow
Some of types :
• Bottom spring valve
• Lever valve
• Puller valve
• Push button valve

VEM( emergency valve):
VEM is a 2 ways / 2 positions valve, ecy valvmanual emergen eTh
normally closed, direct acting. The oil
.flow is allowed in both directions
The manual acting opens the valve
VEM, allowing the oil flow in both
directions. The valve is normally
closed and opens by pushing the button
on the top of the cartridge. The return
in closed position is assured thanks to a
spring once released the pushbutton.
Emergency valves VEM
are available with sizes SAE8 (cavity 3/4-16 UNF) and SAE10 (cavity
7/8-14UNF) for recommended working flow up to 50 l/min (13,2
USgpm). Maximum working pressure is 320 bar. The valves series VEM
are leak-proof valves. A steel poppet, hardened and grinded avoid

7. 7
leakages in both directions. The external components are built with steel
and protected against the corrosion with zinc plating treatment. For
application with extremely aggressive corrosive agents (e.g. marine
applications) the protection can be improved with Zinc-Nickel plating.
Emergency pushbutton is built with aluminium and is protected with red
anodization.

Air regulator with pressure and filter:
Filter Regulator : Filter and regulator designed as a single unit Air is first
filtered then directed to the primary side of the regulator Pressure is then
reduced to a working value Only one unit to install Cost saving when
compared to two separate
units







To increase pressure P 2, pull the adjusting knob Pressure regulator

8. 8
until new P 2 pressure up to disengage the locking teeth Turn clockwise
reached The higher spring force pushes the valve open The rising
pressure P 2 acts under the diaphragm to balance the spring and allow the
valve to close.

CALCULATION

P1=4bar = 4*10
5
Pa
P2=0.3bar = 0.3*10
5
Pa FIND (F1) AND (F2) when A=π/4 *d
2
=1 η , m
3-
= 20*10 20mm=d
solution:
F1= P1 *A * η
F1=4*10
5
* π/4 *( 20*10
-3
)
2
*1


F1=125.6N

F2= P2 *A * η
F2=0.3*10
5
* π/4 *( 20*10
-3
)
2
*1


F2=9.42N

F(ACTUAL) =f1-f2
F(ACTUAL) =125.6 - 9.42
F(ACTUAL) =116.18 N

9. 9
DISCUSSION
1.What is the position and what is the reason of single-action front spring
cylinder ?
ANSWER: single acting cylinder work with compressed air to motivate
the piston in one direction and spring force to return to the base position.
Work can be performed in the air driven direction. The cylinder has one
port that is used to both stock and vent compressed air.
2. Hold down the button of 3/2 button spring N.C. valve. What happened
to the position of the valve?
ANSWER:. the spring extends and The valve opens.
3.What is the position and what is the reason of the cylinder?
ANSWER: The cylinder is stretched owing to the pressure of 4 bars
coming from the compressor.
4.What shall be the position of the valve and position of the cylinder,
when we remove our hands over button?
ANSWER: The valve is would be closed when we remove our hand from
the button.
5.Pressing the button, start to lower the value of filter regulator, what
happened to the cylinder’s motion and its pressure value?
ANSWER: The cylinder extends slower than when the pressure is fully
open because of the lower pressure.